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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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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 .
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explain , step by step , how an electrical current is generated in the electrocytes .
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translator : andrea mcdonough reviewer : bedirhan cinar i would like to introduce you to my favorite parasite . there are millions that i could choose from and this is it : it 's called the jewel wasp . you can find it in parts of africa and asia . it 's a little under an inch long , and it is a beautiful looking parasite . now , you may be saying to yourself , `` this is not a parasite . it 's not a tapeworm , it 's not a virus , how could a wasp be a parasite ? '' you are probably thinking about regular wasps , you know , the ones that build paper nests as their house . well , the thing is that the jewel wasp makes its house inside a living cockroach . here 's how it happens . a jewel wasp is flying around , looking for a cockroach . when it sees one , it lands and bites on its wing . so , i 'll be the cockroach . be-wha ! bewha ! and the cockroach starts shaking it off , `` get away from me ! '' the wasp very quickly starts stinging the cockroach . all of a sudden , the cockroach ca n't move , for about a minute . and then it recovers and stands up . it could run away now , but it does n't . it just does n't want to . it just stays there . it 's become a zombie slave . again , i 'm not making this up . the wasp goes off , it walks away and finds a hole and digs it out , makes it into a burrow . it walks back . this can take up to half an hour . the cockroach is still there . what do we do now ? the wasps grabs onto one of the antenna , bites down on it , of the cockroach , and pulls the cockroach . and the cockroach says , `` alright , '' and walks like a dog on a leash . the wasp takes it all the way down into the burrow . the cockroach says , `` nice place . '' the wasp takes care of some business and then goes and leaves the burrow and seals it shut , leaving the cockroach entombed in darkness , still alive . the cockroach says , `` alright , i 'll stay here if you want . '' now , i mentioned that the cockroach took care , ah , the wasp took care of a little business before it left the burrow . the business was laying an egg on the underside of the cockroach . the egg hatches . out comes a wasp larva . it looks kind of like a maggot with big , nasty jaws . it chews a hole into the cockroach and starts to feed from the outside . it gets bigger , like you can see over here . and then when it gets big enough , it decides to crawl into the hole , into the cockroach . so now it 's inside the still-living cockroach and the cockroach does n't mind much . this goes on for about a month . the larva grows and grows and grows , then makes a pupa , kind of like a cocoon . inside there it grows eyes , it grows wings , it grows legs , the cockroach is still alive , still waiting . finally the wasp is ready to leave , and that 's when the cockroach finally dies because the fullly-formed adult wasp crawls out of the cockroach 's dying body . the wasp shakes itself off , climbs out of the burrow , goes and finds another wasp to mate with to start this whole , crazy cycle again . so , this is not science fiction , this happens every day , all over the world . and scientists are totally fascinated by this . they 're just starting to figure out how all this happens . and , when you really start to look at the science of it , you start to kind of respect this very creepy wasp . you see , the thing is that when it attacks the cockroach , it 's not just stinging wildly , it delivers two precise stings . it knows this cockroach 's nervous system like you know the back of your hand . the first sting goes to that spot there , called the `` walking rhythm generators , '' and , as you can guess , those are the neurons that send signals to the legs to move . it blocks the channels that the neurons use to send these signals . so the cockroach wants to go , it wants to run away , but it ca n't because it ca n't move its legs . and that lasted for about a minute . this is really sophisticated pharmacology . we actually use the same method , a drug called ivermectin , to cure river blindness , which is caused by a parasitic worm that gets into your eye . if you take ivermectin , you paralyze the worm using the same strategy . now , we discovered this in the 1970s , the wasp has been doing this for millions of years . then comes the second sting . now the second sting actually hits two places along the way . and to try to imagine how this can happen , i want you to picture yourself with a friend who 's got a very long , very , very scary looking needle . and your friend , or at least you thought he was your friend , sticks it in your neck , goes into your skull , stops off at one part of your brain and injects some drugs , then keeps going in your brain and injects some more . these are two particular spots , marked here , `` seg '' , and you can see the tip of it in the brain , marked `` br '' . now , we can do this , but it 's really hard for us . it 's called stereotactic drug delivery . you have to put a patient in a big metal frame to hold them still , you need cat scans to know where you 're going , so you look at the picture and say , `` are we going the right way ? '' the jewel wasp has sensors on its stinger and scientists think that it can actually feel its way through the cockroach 's brain until it gets to the exact , right place , and then penetrates an individual neuron and then delivers the goods . so , this is quite amazing stuff , and what seems to happen then is that the wasp is taking away the control that the cockroach has over its own body . it 's taking away the cockroach 's free will . we did n't really appreciate that cockroaches have free will until this wasp showed us . and , we have no idea how it 's doing this , we do n't know yet what the venom has in it and we do n't know which circuits it 's hitting in the cockroach 's brain , and i think that 's why this is , most of all , my favorite parasite because we have so much left to learn from it . thank you very much .
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this can take up to half an hour . the cockroach is still there . what do we do now ?
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what moves into the cockroach ?
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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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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 .
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the world wide web and the internet are the same thing , just called different names .
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way before the first selfie , the ancient greeks and romans had a myth about someone a little too obsessed with his own image . in one telling , narcissus was a handsome guy wandering the world in search of someone to love . after rejecting a nymph named echo , he caught a glimpse of his own reflection in a river , and fell in love with it . unable to tear himself away , narcissus drowned . a flower marked the spot of where he died , and we call that flower the narcissus . the myth captures the basic idea of narcissism , elevated and sometimes detrimental self-involvement . but it 's not just a personality type that shows up in advice columns . it 's actually a set of traits classified and studied by psychologists . the psychological definition of narcissism is an inflated , grandiose self-image . to varying degrees , narcissists think they 're better looking , smarter , and more important than other people , and that they deserve special treatment . psychologists recognize two forms of narcissism as a personality trait : grandiose and vulnerable narcissism . there 's also narcissistic personality disorder , a more extreme form , which we 'll return to shortly . grandiose narcissism is the most familiar kind , characterized by extroversion , dominance , and attention seeking . grandiose narcissists pursue attention and power , sometimes as politicians , celebrities , or cultural leaders . of course , not everyone who pursues these positions of power is narcissistic . many do it for very positive reasons , like reaching their full potential , or helping make people 's lives better . but narcissistic individuals seek power for the status and attention that goes with it . meanwhile , vulnerable narcissists can be quiet and reserved . they have a strong sense of entitlement , but are easily threatened or slighted . in either case , the dark side of narcissism shows up over the long term . narcissists tend to act selfishly , so narcissistic leaders may make risky or unethical decisions , and narcissistic partners may be dishonest or unfaithful . when their rosy view of themselves is challenged , they can become resentful and aggressive . it 's like a disease where the sufferers feel pretty good , but the people around them suffer . taken to the extreme , this behavior is classified as a psychological disorder called narcissistic personality disorder . it affects one to two percent of the population , more commonly men . it is also a diagnosis reserved for adults . young people , especially children , can be very self-centered , but this might just be a normal part of development . the fifth edition of the american psychiatric association 's diagnostic and statistical manual describes several traits associated with narcissistic personality disorder . they include a grandiose view of oneself , problems with empathy , a sense of entitlement , and a need for admiration or attention . what makes these trait a true personality disorder is that they take over people 's lives and cause significant problems . imagine that instead of caring for your spouse or children , you used them as a source of attention or admiration . or imagine that instead of seeking constructive feedback about your performance , you instead told everyone who tried to help you that they were wrong . so what causes narcissism ? twin studies show a strong genetic component , although we do n't know which genes are involved . but environment matters , too . parents who put their child on a pedestal can foster grandiose narcissism . and cold , controlling parents can contribute to vulnerable narcissism . narcissism also seems to be higher in cultures that value individuality and self-promotion . in the united states , for example , narcissism as a personality trait has been rising since the 1970s , when the communal focus of the 60s gave way to the self-esteem movement and a rise in materialism . more recently , social media has multiplied the possibilities for self-promotion , though it 's worth noting that there 's no clear evidence that social media causes narcissism . rather , it provides narcissists a means to seek social status and attention . so can narcissists improve on those negative traits ? yes ! anything that promotes honest reflection on their own behavior and caring for others , like psychotherapy or practicing compassion towards others , can be helpful . the difficulty is it can be challenging for people with narcissistic personality disorder to keep working at self-betterment . for a narcissist , self-reflection is hard from an unflattering angle .
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to varying degrees , narcissists think they 're better looking , smarter , and more important than other people , and that they deserve special treatment . psychologists recognize two forms of narcissism as a personality trait : grandiose and vulnerable narcissism . there 's also narcissistic personality disorder , a more extreme form , which we 'll return to shortly .
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grandiose narcissism includes traits like :
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i 'm gon na give you guys three numbers . a three number sequence and i have a rule in mind that these three numbers obey and i want you to try to figure out what that rule is . but the way you can get information is by proposing your own set of three numbers , to which i will say yes that follows my rule or no it does n't follow my rule . and then you can propose what you think the rule is . is that fair ? okay , so here are the three numbers : 2 , 4 , 8 . 2 , 4 , 8 . you do n't need to continue the sequence , you can propose a totally different sequence , whatever you want to propose and i will simply say yes or no 2 , 4 , 8 ? 16 , 32 16 32 and 64 ? those also follow my rule . ok what 's the rule you think ? multiply by 2 ? that is ... not my rule . what ? that 's not my rule . but you 're allowed , if you want , propose 3 other numbers . 3 , 6 , 12 . 3 , 6 , 12 ? follows my rule . 10 , 20 , 40 . that follows the rule . i 'm still multiplying by two i know [ laughter ] i know what you 're doing . and yes it follows my rule but no it 's not my rule . 5 , 10 and 20 ? follows my rule 100 , 200 , 400 ? follows my rule 500 , 1000 , 2000 follows my rule . you want me to keep going ? but do i just keep going ? you going to tell me or what ? [ laughter ] am i doing it the wrong way ? am i approaching this the wrong way ? you 're totally fine , but you 're approaching the way most people approach it . like think strategically about this . you want information . i have information . the point of the three numbers , right , is to allow you to figure out what the rule is . okay , i 'm going to give you the numbers that i do n't think fits the sequence and see what you 'll say . so i 'll say 2 , 4 , 7 . fits my rule so , whatever i propose is right ? so , is your rule like you can propose any number ? so , the rule is anything we say is yes ? no damn it [ laughter ] but you were on the right track now . hit me with three numbers . 3 , 6 , 9 . follows my rule . hmm ... oh , that did n't follow my rule . this is good , right ? 5 , 10 , 15 . that follows my rule . what ? oh ... really ? yeah i do n't believe this . 1 , 2 , 3 ? follows the rule what about 7 , 8 , 9 ? [ laughter ] yes , that follows the rule . 8 16 39 fits the rule . excellent . but we 're no closer to the rule . i want you get to the rule . how about 1 , 7 , 13 ? follows the rule . 11 , 12 , 13 ? how does this make sense ? follows the rule . 10 , 9 , 8 ? i do n't know how to do this . does not follow the rule . 10 , 9 , 8 does not . oh , so , is it all in ascending order ? boo yeah ! up top ! yes . first ones to get it . you guys nailed it that 's the rule that 's the rule . numbers in increasing order . awww numbers in ascending order 1 , 2 , 3 , 4 , 5 , 6 , 10 , 15 , 25 , does n't matter . any numbers in ascending order . i was inspired to make this video by the book the black swan by nassim taleb . now , the black swan is a metaphor for the unknown and the unexpected . i mean in the old world the theory was that all swans were white . so , each instance of a white swan would make you think , `` yeah , that theory is pretty good . '' but the point is you can never prove a theory true and in fact when people found australia they realized that there were black swans . what was interesting for me was that everyone i spoke to came up with a rule very early on and then only proposed numbers that fit with that rule they were thinking . i was looking for you guys to propose a set of numbers that did n't follow your rule and did n't follow my rule . i was looking for you guys not to try to confirm what you believe . you 're always asking something where you expect the answer to be yes , right ? like , you 're trying to get at it . but , instead you want to get the no 's . you want to get the no because that 's much more informational for you then yes , like everything is a yes.. that is true . that is really true and once you say that . that is what 's so important about the scientific method . we set out to disprove our theories and it 's when ca n't disprove them that we say this must be getting at something really true about our reality . so , i think we should do that in all aspects of our lives if you think that something is true you should try as hard as you can to disprove it . only then can you really get at the truth and not fool yourself .
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up top ! yes . first ones to get it .
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near the end of the video , it is stated that a `` no '' was much more helpful than a `` yes '' . is trying to disprove your theory a good way to get at the truth ?
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yeah . hey it 's me destin , welcome back to smarter every day . so i 've seen enough videos on the internet of a mantis shrimp punching to have a good idea of what 's going on , but i do n't understand it , like at the mechanical level . so today on smarter every day my sister has volunteered to model three seemingly unrelated objects to help us understand this a little bit better . but first , let 's go to james cook university and watch one punch in slow motion . ok where are we going ? -we 're gon na we 're gon na go to a place called yorkeys knob . - shut up ! - that 's the name of it . - to get some crabs . - we 're not ! - from yorkeys knob . ( destin ) [ laughs ] i was hoping i could use that.. but ... i ca n't . - it 's true , the place is called yorkeys knob . ( destin ) you were n't lying . so yorkeys knob , now i have to find crabs . - that one . that 's a good one . grab that one . got him ? -got him . - there you go . crabs in test tubes . ( destin ) i have to say , i 've never seen that before . - it works . it 'll be cool . so what we 'll do is we 'll take one of the test tubes with the crab in it , we 'll put the test tube down here which will keep the crab there . he 'll come out and go.. bang.. hit the crab and smash the test tube . ( destin ) really ? so the mantis shrimp is.. it 's a peacock mantis shrimp . - yep . - look at that joker . it 's pretty awesome . hey do n't they see more colors than any other animal ? - yeah . they 've got incredible vision and their eyes are setup in parts of three . so the top bits look in a different part from the middle , which look at a different part from the bottom . - kind of like the fovea on our eyes is different from.. - yeah . - ok. - out we come . move little crab . [ loud click ] - bang ! - it triggered . - pull him out . [ bang ] [ breaking glass ] ( destin ) yeah , that 's crazy . so let 's back it up and watch again and you 'll notice that there 's a cavitation bubble generated at the exact point of impact . ok first of all , a mantis shrimp is n't even a shrimp . it 's actually a stomatopod . we call it a shrimp because it kinda looks like it , but we also call it a mantis because it 's similar to a preying mantis with its forearms . they have similar hunting strategies . dr seymour says that punch is so fast that it ca n't be accomplished by muscle movement alone , there has to be something else going on , which brings up sheila patek . believe it or not , dr patek has determined that the shape of this potato chip is the secret to the punch of the mantis shrimp . seriously . this shape is called a hyperbolic paraboloid , and if you 've ever taken calculus you 've seen it . it 's basically a saddle shape and they 're super strong . this saddle is located on top of the smasher , and the stomatopod uses his muscles to compress it like a spring and he holds it back with a latch mechanism . he then releases this potential energy and it drives the club forward at a much higher velocity than would be possible with muscle alone . so the next time you eat one of these remember there 's another animal eating with the same shape you are , only he 's doing it at the bottom of the ocean and he 's got that shape integrated into the top of his arm . if you 've ever played with a vice clamp before , you 've seen this type of mechanism . you can slowly clamp down on the tool , which uses a cam-over action to lock it in place , and if you have it set right and squeeze it hard , you store mechanical strain energy . when you trip the latch the energy 's released and the arm flies forward real fast , but think about this . mantis shrimp use their little clubber to break open shells that are really hard right ? so why does the shell break and the club does n't ? let 's watch another clip . this is dr seymour feeding a crab to the stomatopod except this time there 's no test tube . - it 's flicking the.. it 's flicking the rock . ohhhh ! - did you get it ? - dunno , might have . - ohhhh i feel for that crab . [ laughs ] [ bang ] ( destin ) watch again closer and see if you can see the saddle release the energy . - look at that . - good grief . snapped it straight in half . we 're talking about serious forces here . in engineering we take two materials and we combine them together into composites to make them stronger . for example plywood is made of many layers of wood with the fibers oriented in two different directions . mantis shrimps however take this to the next level with an organic polymer called chitin . at the wyss institute for biologically inspired engineering at harvard , they determined that these fibers are n't rotated only in two principle directions like plywood , it 's an entire helix , which gives the structure strength in many different directions . these strands are then bonded together in a mineralized matrix which makes the whole thing an incredibly strong smasher . but it gets crazier than that . the team put a section of the smasher in a synchrotron so they could analyze the material makeup . a synchrotron ! that 's like a particle accelerator . this is crazy science . they bombarded it hundreds of times to understand the density and the local orientation of the crystals in the material , and guess what . they found that the crystals near the surface were oriented perpendicular to the impact site and that orientation changed as we move away from the impact site . basically the material changes composition and strength at different locations on the inside . the impact surface is incredibly hard , but the internal structure transitions smoothly to allow the distribution of a huge impulse load throughout the rest of that structure so it can punch stuff all day long without breaking . so instead of a normal composite like plywood , which are identical layers stacked up and glued together , a mantis shrimp club is a variable composite , meaning you can vary the material makeup and the strength orientation wherever you need it . this is an incredibly smart way to design a system . in summary , i want you to love the mantis shrimp . i do n't want you to love it just because of the mechanics of how it throws the punch . not because of the chemistry of the variable composition of the crystalline structure . the optics.. it can see circularly polarized light . this is an incredible , incredible animal , and i want you to think about it every time you eat a chip like this . can you do that for me ? ok i hope you enjoyed learning how mantis shrimp club . it 's all about the hyperbolic paraboloid , or as my cal 3 teacher taught me , hyperbowic pawabawoid . anyway , i 'm destin , you 're getting smarter every day . if you 're interested in supporting the crazy trips i do , please consider supporting on audible . audible.com/smarter . you can get any audiobook you want . ( i apologize if you 're deaf ... it makes no sense for you to support via audible . ) i listened to 20,000 leagues under the sea when i did this series because i wanted to learn more about marine life . jules verne nailed it . 20,000 leagues under the sea , audible.com/smarter . thank you so much for your support . i 'll leave a link in the video description . i 'm destin , you 're getting smarter every day , have a good one . it 's derek ! he video bombed me . [ laugh ] ( destin ) ho ! - [ laughs ] we could bring the lighting down on the chip please . perfect . [ laughs ] that was really dumb . ( destin ) which is why i think i 'm gon na use it .
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( destin ) really ? so the mantis shrimp is.. it 's a peacock mantis shrimp . - yep .
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the mantis shrimp is not actually a shrimp , but a stomatopod . how did it get its name ?
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imagine an airplane flying one millimeter above the ground and circling the earth once every 25 seconds while counting every blade of grass . shrink all that down so that it fits in the palm of your hand , and you 'd have something equivalent to a modern hard drive , an object that can likely hold more information than your local library . so how does it store so much information in such a small space ? at the heart of every hard drive is a stack of high-speed spinning discs with a recording head flying over each surface . each disc is coated with a film of microscopic magnetised metal grains , and your data does n't live there in a form you can recognize . instead , it is recorded as a magnetic pattern formed by groups of those tiny grains . in each group , also known as a bit , all of the grains have their magnetization 's aligned in one of two possible states , which correspond to zeroes and ones . data is written onto the disc by converting strings of bits into electrical current fed through an electromagnet . this magnet generates a field strong enough to change the direction of the metal grain 's magnetization . once this information is written onto the disc , the drive uses a magnetic reader to turn it back into a useful form , much like a phonograph needle translates a record 's grooves into music . but how can you get so much information out of just zeroes and ones ? well , by putting lots of them together . for example , a letter is represented in one byte , or eight bits , and your average photo takes up several megabytes , each of which is 8 million bits . because each bit must be written onto a physical area of the disc , we 're always seeking to increase the disc 's areal density , or how many bits can be squeezed into one square inch . the areal density of a modern hard drive is about 600 gigabits per square inch , 300 million times greater than that of ibm 's first hard drive from 1957 . this amazing advance in storage capacity was n't just a matter of making everything smaller , but involved multiple innovations . a technique called the thin film lithography process allowed engineers to shrink the reader and writer . and despite its size , the reader became more sensitive by taking advantage of new discoveries in magnetic and quantum properties of matter . bits could also be packed closer together thanks to mathematical algorithms that filter out noise from magnetic interference , and find the most likely bit sequences from each chunk of read-back signal . and thermal expansion control of the head , enabled by placing a heater under the magnetic writer , allowed it to fly less than five nanometers above the disc 's surface , about the width of two strands of dna . for the past several decades , the exponential growth in computer storage capacity and processing power has followed a pattern known as moore 's law , which , in 1975 , predicted that information density would double every two years . but at around 100 gigabits per square inch , shrinking the magnetic grains further or cramming them closer together posed a new risk called the superparamagnetic effect . when a magnetic grain volume is too small , its magnetization is easily disturbed by heat energy and can cause bits to switch unintentionally , leading to data loss . scientists resolved this limitation in a remarkably simple way : by changing the direction of recording from longitudinal to perpendicular , allowing areal density to approach one terabit per square inch . recently , the potential limit has been increased yet again through heat assisted magnetic recording . this uses an even more thermally stable recording medium , whose magnetic resistance is momentarily reduced by heating up a particular spot with a laser and allowing data to be written . and while those drives are currently in the prototype stage , scientists already have the next potential trick up their sleeves : bit-patterned media , where bit locations are arranged in separate , nano-sized structures , potentially allowing for areal densities of twenty terabits per square inch or more . so it 's thanks to the combined efforts of generations of engineers , material scientists , and quantum physicists that this tool of incredible power and precision can spin in the palm of your hand .
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the areal density of a modern hard drive is about 600 gigabits per square inch , 300 million times greater than that of ibm 's first hard drive from 1957 . this amazing advance in storage capacity was n't just a matter of making everything smaller , but involved multiple innovations . a technique called the thin film lithography process allowed engineers to shrink the reader and writer .
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ever increasing areal density means more storage capacity at lower costs . give a few examples of how having cheap and large storage capacity has changed ( or can change ) the quality of our lives .
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sunscreen comes in many forms , each with its own impacts on your body and the environment . with so many options , how do you choose which sunscreen is best for you ? to answer that question , we first have to understand how sunscreens work . sunlight is composed of electromagnetic waves and is our primary source of ultraviolet radiation , which has a shorter wavelength than visible light and carries more energy . uva , uvb , and uvc are classified according to their wavelengths . short wavelength uvc never reaches the earth 's surface , but uvb and uva do . medium wavelength uvb rays can enter the skin 's superficial layers and long length uva rays can penetrate into the deeper layers . uvb in small amounts actually helps us make vitamin d , which enables our bodies to build and maintain strong bones . however , prolonged exposure to uva and uvb can damage dna , age your skin , and promote the development of potentially deadly skin cancer . sunscreen protects your skin either physically by deflecting uv rays with an inorganic blocker like zinc oxide or titanium dioxide , or chemically by using carbon-based compounds to absorb uv photons that are then harmlessly dissipated as heat . so , what differentiates one sunscreen from another ? when we choose a sunscreen , we can compare application method , the spf , and the active ingredients . sprays can be convenient to put on , especially when you 're wet , but a recent study found that most people do n't apply a thick enough layer to get full protection . and the possible health risks of inhaling sunscreen compounds from a spray cloud might make you consider reaching for that bottle of lotion instead . opt for a sunscreen with an spf of at least 15 , although 30 is better . spf is a nonlinear scale of how much uvb radiation is needed to give protected skin a sunburn . spf 15 does a pretty good job by blocking 93 % of uvb rays . you get a slight increase as spf goes up , with spf 30 blocking 97 % , and 50 blocking 98 % . spf is based on the quantity of solar exposure . so how much time you have before you start to burn really depends on a long list of factors , including your genetics , and when , where , and how you spend your time in the sun . even though us marketed sunscreens have been deemed safe by the fda , scientists are still researching the effects of many active ingredients on the human body . so if you 're worried about potential irritants , look for mineral-based formulas with zinc oxide or titanium dioxide . even though they may go on a bit thick at first , they 're less irritating than carbon-based chemical sunscreens . these mineral-based sunscreens are preferential for the environment , too . if you plan on catching rays while splashing in a river or the ocean , keep in mind that carbon-based chemical sunscreens can harm marine life . take coral reefs , for example . although they cover less than 1 % of the earth 's underwater surface , they 're home to nearly 25 % of all fish species , making them the most diverse and productive marine ecosystems . research shows that carbon-based chemical sunscreen ingredients , like oxybenzone , butylparaben , octinoxate , and 4mbc contribute to a stress condition called coral bleaching in corals , which are living creatures . exposure to these organic compounds results in the death of the coral 's symbiotic algae . in addition to providing a reliable food source , these algae give coral their brilliant rainbow of colors . without them , corals turn a bleached white and are susceptible to disease and possibly death . and once the coral dies , the entire reef ecosystem is not far behind . so you 're now ready to make an informed choice when picking out your next sunscreen . spf is clearly labeled on the front . on the back under `` active ingredients , '' you can find whether zinc oxide , titanium dioxide , and those coral-harming components are present . taking a bit more time to check can be well worth it for both you and the environment .
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if you plan on catching rays while splashing in a river or the ocean , keep in mind that carbon-based chemical sunscreens can harm marine life . take coral reefs , for example . although they cover less than 1 % of the earth 's underwater surface , they 're home to nearly 25 % of all fish species , making them the most diverse and productive marine ecosystems .
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why should you care about coral reefs if you do n't live in close proximity to one ?
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we 've all seen the movies where a monster , created by a scientist in a laboratory , escapes to wreak havoc on the outside world . but what if the monster was not some giant rampaging beast , destroying a city , but just a tiny amount of seaweed with the potential to disrupt entire coastal ecosystems ? this is the story of caulerpa taxifolia , originally a naturally occurring seaweed native to tropical waters . in the 1980s , one strain was found to thrive in colder environments . this trait , combined with its beautiful , bright green color and ability to grow quickly without maintenance made it ideal for aquariums , which it helped keep clean by consuming nutrients and chemicals in the water . further selective breeding made it even heartier , and soon it was used in aquariums around the world . but it was not long before a sample of this aquarium-developed super algae turned up in the mediterranean sea near the famed oceanographic museum of monaco . the marine biologist who found it believed that the museum had accidentally realeased it into the ocean along with aquarium waters , while museum directors claimed it had be carried into the area by ocean currents . regardless of how it ended up there , the non-native caulerpa multiplied rapidly , having no natural predators due to releasing a toxin that keeps fish away . and like some mythical monster , even a tiny piece that broke off could grow into a whole new colony . through water currents and contact with boat anchors and fishing lines , it fragmented and spread throughout mediterranean coastal cities covering coral reefs . so what was the result of this invasion ? well , it depends on who you ask . many scientists warned that the spread of caulerpa reduces biodiversity by crowding out native species of seaweed that are eaten by fish , with the biologist who first discovered its presence dubbing it killer algae . other studies instead claim that the algae actually had a beneficial effect by consuming chemical pollutants -- one reason the aquariums strain was developed . but the disruption of a natural ecosystem by an introduced foreign species can have unpredictable and uncontrollable effects that may not be immediately visible . so when culerpa taxifolia was discovered at carlsbad 's agua hedionda lagoon , near san diego in the year 2000 , having most likely come from the dumping of home aquarium water into a connecting storm drain , it was decided to stop it before it spread . tarps were placed over the culerpa colonies and chlorine injected inside . although this method killed all other marine life trapped under the tarps , it did succeed in eradicating the algae and native eelgrass was able to emerge in its place . by responding quickly , authorities in california were able to prevent culerpa from propagating . but another occurrence of the strain , in the coastal wetlands of southeast australia , was left unchecked and allowed to spread . and unfortunately , a tarp can not cover the mediterranean sea or the australian coast . invasive species are not a new problem , and can indeed occur naturally . but when such species are the results of human directed selective breeding or genetic modification and then released into the natural environment , their effect on ecosystems can be far more radical and irreversible . with the proliferation of new technologies and multiple threats to the environment , it is more important than ever for scientists to monitor and evaluate the risks and dangers , and for the rest of us to remember that what starts in our backyard can effect ecosystems half a world away .
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regardless of how it ended up there , the non-native caulerpa multiplied rapidly , having no natural predators due to releasing a toxin that keeps fish away . and like some mythical monster , even a tiny piece that broke off could grow into a whole new colony . through water currents and contact with boat anchors and fishing lines , it fragmented and spread throughout mediterranean coastal cities covering coral reefs .
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fragmentation refers to a tiny piece of the caulerpa seaweed getting disconnected . the disconnected piece can then start the growth of a new colony . therefore , touching the caulerpa , anchors , and fishing lines can lead to fragmentation , that is why the eradication technique in carlsbad involved :
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nicolas steno is rarely heard of outside intro to geology , but anyone hoping to understand life on earth should see how steno expanded and connected those very concepts : earth , life , and understanding . born niels stensen in 1638 denmark , son of a goldsmith , he was a sickly kid whose school chums died of plague . he survived to cut up corpses as an anatomist , studying organs shared across species . he found a duct in animal skulls that sends saliva to the mouth . he refuted descartes ' idea that only humans had a pineal gland , proving it was n't the seat of the soul , arguably , the debut of neuroscience . most remarkable for the time was his method . steno never let ancient texts , aristotelian metaphysics , or cartesian deductions overrule empirical , experimental evidence . his vision , uncluttered by speculation or rationalization , went deep . steno had seen how gallstones form in wet organs by accretion . they obeyed molding principles he knew from the goldsmith trade , rules useful across disciplines for understanding solids by their structural relationships . later , the grand duke of tuscany had him dissect a shark . its teeth resembled tongue stones , odd rocks seen inside other rocks in malta and the mountains near florence . pliny the elder , old roman naturalist , said these fell from the sky . in the dark ages , folks said they were snake tongues , petrified by saint paul . steno saw that tongue stones were shark teeth and vice versa , with the same signs of structural growth . figuring similar things are made in similar ways , he argued the ancient teeth came from ancient sharks in waters that formed rock around the teeth and became mountains . rock layers were once layers of watery sediment , which would lay out horizontally , one atop another , oldest up to newest . if layers were deformed , tilted , cut by a fault or a canyon , that change came after the layer formed . sounds simple today ; back then , revolutionary . he 'd invented stratigraphy and laid geology 's ground work . by finding one origin for shark teeth from two eras by stating natural laws ruling the present also ruled the past , steno planted seeds for uniformitarianism , the idea that the past was shaped by processes observable today . in the 18th and 19th centuries , english uniformitarian geologists , james hutton and charles lyell , studied current , very slow rates of erosion and sedimentation and realized the earth had to be way older than the biblical guestimate , 6000 years . out of their work came the rock cycle , which combined with plate tectonics in the mid-twentieth century to give us the great molten-crusting , quaking , all-encircling theory of the earth , from a gallstone to a 4.5 billion-year-old planet . now think bigger , take it to biology . say you see shark teeth in one layer and a fossil of an organism you 've never seen under that . the deeper fossil 's older , yes ? you now have evidence of the origin and extinction of species over time . get uniformitarian . maybe a process still active today caused changes not just in rocks but in life . it might also explain similarities and differences between species found by anatomists like steno . it 's a lot to ponder , but charles darwin had the time on a long trip to the galapagos , reading a copy of his friend charles lyell 's `` principles of geology , '' which steno sort of founded . sometimes giants stand on the shoulders of curious little people . nicolas steno helped evolve evolution , broke ground for geology , and showed how unbiased , empirical observation can cut across intellectual borders to deepen our perspective . his finest accomplishment , though , may be his maxim , casting the search for truth beyond our senses and our current understanding as the pursuit of the beauty of the as yet unknown . beautiful is what we see , more beautiful is what we know , most beautiful , by far , is what we do n't .
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he found a duct in animal skulls that sends saliva to the mouth . he refuted descartes ' idea that only humans had a pineal gland , proving it was n't the seat of the soul , arguably , the debut of neuroscience . most remarkable for the time was his method .
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how did steno prove descartes was wrong to locate the human soul in the pineal gland ?
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imagine , for a second , a duck teaching a french class , a ping-pong match in orbit around a black hole , a dolphin balancing a pineapple . you probably have n't actually seen any of these things , but you could imagine them instantly . how does your brain produce an image of something you 've never seen ? that may not seem hard , but that 's only because we 're so used to doing it . it turns out that this is actually a complex problem that requires sophisticated coordination inside your brain . that 's because to create these new , weird images , your brain takes familiar pieces and assembles them in new ways , like a collage made from fragments of photos . the brain has to juggle a sea of thousands of electrical signals getting them all to their destination at precisely the right time . when you look at an object , thousands of neurons in your posterior cortex fire . these neurons encode various characteristics of the object : spiky , fruit , brown , green , and yellow . this synchronous firing strengthens the connections between that set of neurons , linking them together into what 's known as a neuronal ensemble , in this case the one for pineapple . in neuroscience , this is called the hebbian principle , neurons that fire together wire together . if you try to imagine a pineapple later , the whole ensemble will light up , assembling a complete mental image . dolphins are encoded by a different neuronal ensemble . in fact , every object that you 've seen is encoded by a neuronal ensemble associated with it , the neurons wired together by that synchronized firing . but this principle does n't explain the infinite number of objects that we can conjure up in our imaginations without ever seeing them . the neuronal ensemble for a dolphin balancing a pineapple does n't exist . so how come you can imagine it anyway ? one hypothesis , called the mental synthesis theory , says that , again , timing is key . if the neuronal ensembles for the dolphin and pineapple are activated at the same time , we can perceive the two separate objects as a single image . but something in your brain has to coordinate that firing . one plausible candidate is the prefrontal cortex , which is involved in all complex cognitive functions . prefrontal cortex neurons are connected to the posterior cortex by long , spindly cell extensions called neural fibers . the mental synthesis theory proposes that like a puppeteer pulling the strings , the prefrontal cortex neurons send electrical signals down these neural fibers to multiple ensembles in the posterior cortex . this activates them in unison . if the neuronal ensembles are turned on at the same time , you experience the composite image just as if you 'd actually seen it . this conscious purposeful synchronization of different neuronal ensembles by the prefrontal cortex is called mental synthesis . in order for mental sythesis to work , signals would have to arrive at both neuronal ensembles at the same time . the problem is that some neurons are much farther away from the prefrontal cortex than others . if the signals travel down both fibers at the same rate , they 'd arrive out of sync . you ca n't change the length of the connections , but your brain , especially as it develops in childhood , does have a way to change the conduction velocity . neural fibers are wrapped in a fatty substance called myelin . myelin is an insulator and speeds up the electrical signals zipping down the nerve fiber . some neural fibers have as many as 100 layers of myelin . others only have a few . and fibers with thicker layers of myelin can conduct signals 100 times faster or more than those with thinner ones . some scientists now think that this difference in myelination could be the key to uniform conduction time in the brain , and consequently , to our mental synthesis ability . a lot of this myelination happens in childhood , so from an early age , our vibrant imaginations may have a lot to do with building up brains whose carefully myelinated connections can craft creative symphonies throughout our lives .
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this synchronous firing strengthens the connections between that set of neurons , linking them together into what 's known as a neuronal ensemble , in this case the one for pineapple . in neuroscience , this is called the hebbian principle , neurons that fire together wire together . if you try to imagine a pineapple later , the whole ensemble will light up , assembling a complete mental image .
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the hebbian principle is based on the principle that : “ neurons that fire together , _____ . ”
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`` beauty is a curse , '' psyche thought as she looked over the cliff 's edge where she 'd been abandoned by her father . she 'd been born with the physical perfection so complete that she was worshipped as a new incarnation of venus , the goddess of love . but real-life human lovers were too intimidated even to approach her . when her father asked for guidance from the oracle of apollo , the god of light , reason , and prophecy . he was told to abandon his daughter on a rocky crag where she would marry a cruel and savage serpent-like winged evil . alone on the crag , psyche felt zephyr the west wind gently lifting her into the air . it set her down before a palace . `` you are home , '' she heard an unseen voice say . `` your husband awaits you in the bedroom , if you dare to meet him . '' she was brave enough , psyche told herself . the bedroom was so dark that she could n't see her husband . but he did n't feel serpent-like at all . his skin was soft , and his voice and manner were gentle . she asked him who he was , but he told her this was the one question he could never answer . if she loved him , she would not need to know . his visits continued night after night . before long , psyche was pregnant . she rejoiced , but was also conflicted . how could she raise her baby with a man she 'd never seen ? that night , psyche approached her sleeping husband holding an oil lamp . what she found was the god cupid who sent gods and humans lusting after each other with the pinpricks of his arrows . psyche dropped her lamp , burning cupid with hot oil . he said he 'd been in love with psyche ever since his jealous mother , venus , asked him to embarrass the young woman by pricking her with an arrow . but taken with psyche 's beauty , cupid used the arrow on himself . he did n't believe , however , that gods and humans could love as equals . now that she knew his true form , their hopes for happiness were dashed , so he flew away . psyche was left in despair until the unseen voice returned and told her that it was indeed possible for her and cupid to love each other as equals . encouraged , she set out to find him . but venus intercepted psyche and said she and cupid could only wed if she completed a series of impossible tasks . first , psyche was told to sort a huge , messy pile of seeds in a single night . just as she was abandoning hope , an ant colony took pity on her and helped with the work . successfully passing the first trial , psyche next had to bring venus the fleece of the golden sheep , who had a reputation for disemboweling stray adventurers , but a river god showed her how to collect the fleece the sheep had snagged on briars , and she succeeded . finally , psyche had to travel to the underworld and convince proserpina , queen of the dead , to put a drop of her beauty in a box for venus . once again , the unseen voice came to psyche 's aide . it told her to bring barley cakes for cerberus , the guard dog to the underworld and coins to pay the boatman , charon to ferry her across the river styx . with her third and final task complete , psyche returned to the land of the living . just outside venus 's palace , she opened the box of proserpina 's beauty , hoping to keep some for herself . but the box was filled with sleep , not beauty , and psyche collapsed in the road . cupid , now recovered from his wounds , flew to his sleeping bride . he told her he 'd been wrong and foolish . her fearlessness in the face of the unknown proved that she was more than his equal . cupid gave psyche amborsia , the nectar of the gods , making her immortal . shortly after , psyche bore their daughter . they named her pleasure , and she , cupid , and psyche , whose name means soul , have been complicating people 's love lives ever since .
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finally , psyche had to travel to the underworld and convince proserpina , queen of the dead , to put a drop of her beauty in a box for venus . once again , the unseen voice came to psyche 's aide . it told her to bring barley cakes for cerberus , the guard dog to the underworld and coins to pay the boatman , charon to ferry her across the river styx .
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the voice psyche hears :
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mendelevium , which is named after one of the most important people as far as the periodic table is concerned , which is dimitri mendeleev . mendelevium is named after mendeleev , in russia the periodic table is called the mendeleev table , and you can see here on my tie i ’ ve got a picture of mendeleev . it ’ s another element which has absolutely zero use in the real world . he is one of the iconic , iconic , pictures of chemists that most chemists will recognise mendeleev . ah , mendeleev was all to do with how it was discovered to put the periodic table together , for a long time , people knew that there were different elements and that they knew that they had different properties . what they couldn ’ t do , was rationalise those properties and understand why certain elements behaved in a similar manner even though in principle they should have been very different . but mendeleev has another cause of fame ; he is famous in russia because he was the person who worked out the standard for the strength of vodka . so here i have a bottle of russian mendeleev , you ’ ll see it says mendeleev here and vodka , with a periodic table on it , and here ’ s the formula , ethanol plus water , and mendeleev was the person that worked out the standard of 40 % of ethanol in water as being vodka . and in fact it ’ s remarkable the number of experiments you read where people have used 40 % ethanol in water as the solvent for their reaction doubtless because they had a handy bottle of vodka or some similar drink .
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mendelevium , which is named after one of the most important people as far as the periodic table is concerned , which is dimitri mendeleev . mendelevium is named after mendeleev , in russia the periodic table is called the mendeleev table , and you can see here on my tie i ’ ve got a picture of mendeleev . it ’ s another element which has absolutely zero use in the real world .
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when did dmitri mendeleev publish the first periodic table of the elements ?
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albert einstein played a key role in launching quantum mechanics through his theory of the photoelectric effect but remained deeply bothered by its philosophical implications . and though most of us still remember him for deriving e=mc^2 , his last great contribution to physics was actually a 1935 paper , coauthored with his young colleagues boris podolsky and nathan rosen . regarded as an odd philosophical footnote well into the 1980s , this epr paper has recently become central to a new understanding of quantum physics , with its description of a strange phenomenon now known as entangled states . the paper begins by considering a source that spits out pairs of particles , each with two measurable properties . each of these measurements has two possible results of equal probability . let 's say zero or one for the first property , and a or b for the second . once a measurement is performed , subsequent measurements of the same property in the same particle will yield the same result . the strange implication of this scenario is not only that the state of a single particle is indeterminate until it 's measured , but that the measurement then determines the state . what 's more , the measurements affect each other . if you measure a particle as being in state 1 , and follow it up with the second type of measurement , you 'll have a 50 % chance of getting either a or b , but if you then repeat the first measurement , you 'll have a a 50 % chance of getting zero even though the particle had already been measured at one . so switching the property being measured scrambles the original result , allowing for a new , random value . things get even stranger when you look at both particles . each of the particles will produce random results , but if you compare the two , you will find that they are always perfectly correlated . for example , if both particles are measured at zero , the relationship will always hold . the states of the two are entangled . measuring one will tell you the other with absolute certainty . but this entanglement seems to defy einstein 's famous theory of relativity because there is nothing to limit the distance between particles . if you measure one in new york at noon , and the other in san francisco a nanosecond later , they still give exactly the same result . but if the measurement does determine the value , then this would require one particle sending some sort of signal to the other at 13,000,000 times the speed of light , which according to relativity , is impossible . for this reason , einstein dismissed entanglement as `` spuckafte ferwirklung , '' or spooky action at a distance . he decided that quantum mechanics must be incomplete , a mere approximation of a deeper reality in which both particles have predetermined states that are hidden from us . supporters of orthodox quantum theory lead by niels bohr maintained that quantum states really are fundamentally indeterminate , and entanglement allows the state of one particle to depend on that of its distant partner . for 30 years , physics remained at an impasse , until john bell figured out that the key to testing the epr argument was to look at cases involving different measurements on the two particles . the local hidden variable theories favored by einstein , podolsky and rosen , strictly limited how often you could get results like 1a or b0 because the outcomes would have to be defined in advanced . bell showed that the purely quantum approach , where the state is truly indeterminate until measured , has different limits and predicts mixed measurement results that are impossible in the predetermined scenario . once bell had worked out how to test the epr argument , physicists went out and did it . beginning with john clauster in the 70s and alain aspect in the early 80s , dozens of experiments have tested the epr prediction , and all have found the same thing : quantum mechanics is correct . the correlations between the indeterminate states of entangled particles are real and can not be explained by any deeper variable . the epr paper turned out to be wrong but brilliantly so . by leading physicists to think deeply about the foundations of quantum physics , it led to further elaboration of the theory and helped launch research into subjects like quantum information , now a thriving field with the potential to develop computers of unparalleled power . unfortunately , the randomness of the measured results prevents science fiction scenarios , like using entangled particles to send messages faster than light . so relativity is safe , for now . but the quantum universe is far stranger than einstein wanted to believe .
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once a measurement is performed , subsequent measurements of the same property in the same particle will yield the same result . the strange implication of this scenario is not only that the state of a single particle is indeterminate until it 's measured , but that the measurement then determines the state . what 's more , the measurements affect each other .
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the simplest test of entanglement uses a detector that makes a “ click ” when it detects state 1 , but does nothing for state 0. the lack of a click is then taken as a measurement of state 0. if the detectors are not 100 % efficient , though ( that is , they occasionally fail to produce a “ click ” when they ’ re supposed to ) , this opens a loophole in the experiment that might allow a local hidden variable theory to survive . how might this work ?
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okay weíre going to be looking today at copper . this is something looking back at the old video , itís a short video and there isnít any experimentation in it so i thought weíd do something a bit practical . copper is an element which people are very familiar with because itís such a characteristic coloured metal , sort of reddish colour , though it gets darker when oxide forms . but itís quite a soft metal and you can cut it quite easily if you have a cutter like this which has steel blades , it will just dig into the metal and it should just cut off . when you cut the metal you get this very nice , shiny , fresh surface coloured just like copper . this is a ball of copper , copper metal . as you might imagine itís a ball of metal so therefore it is quite dense and heavy . i mean itís not as dense as , i think steve told me this morning , that if we had a ball this size of plutonium he told me it would weigh about a kilo and a half so he thought . so itís not quite as heavy as that but still itís pretty heavy and dense . so this is a very , very nice sample of very fine copper wire . so the copper wire here is , what width is this ? this isö phew ! point zero , iím not even going toöthatís just too small , so itís point one of a millimetre . so inside the beaker weíve got a solution called sodium potassium tartrate , so no copper in there at the moment . weíre going to introduce that through this . this is a solution of copper sulphate . copper is very popular for architectural use because if you put it on the roofs of buildings it then reacts , particularly with carbon dioxide in the air , to give a very nice green colour . first of all though we need to heat this to about 50∞c , and to the sodium potassium tartrate we need to add some very weak , hydrogen peroxide so this is only 3 % hydrogen peroxide , so in it goes . we need to make sure they mix together which is why thereís a stirring bar at the bottom there stirring away . okay so thatís stirring nicely , so as i said sodium potassium tartrate and hydrogen peroxide and we need to add only one mill so thatís 1cm3 of the copper sulphate . the copper wire here is very , very high grade , this is grade one copper wire and itís point one of a millimetre in diameter and you can see the wonderful copperas lustre coming off the side there . what do you mean by grade one copper ? so this is very high purity , this is like 99.99 % copper , used for electronics fabrications and high quality research samples . itís also used for electrical wiring , in fact itís used so much that in a country like the uk each person has about 175 kilos of copper associated with each person , in the piping , the wiring and so on . the problem is that in many other countries , for example in china , people have very much less copper associated with them , there isnít so much electrical wiring in rural parts of china . and if everybody in china had the same amount of copper associated with them as those in england or america or canada there wouldnít be enough copper in all the known deposits around the world . copper is actually necessary for life , plants and animals use copper . but actually you can have a disease called wilsonís disease which basically your body canít metabolise copper properly , itís actually an inherited disease . ready ? whatís going on there is itís producing a lot of gas so itís reacting to form a complex . and itís going from the potassium tartrate complex there to well , its producing carbon dioxide and oxygen , mainly oxygen gas is being produced which is why youíre seeing the fizzing . and itís become copper oxide , cuprous oxide actually . copper is found as a metal lying around in various places in the world . i believe the name came from the island of cyprus in the middle of the mediterranean , but copper has always been know even in pre-historic times people found small amounts of copper . but as we use more and more copper people have had to dig deeper and deeper mines . the mine in chile where those very brave miners were entombed for more than two months and then rescued was a copper mine . and to get the metal that we need weíre going to have to go deeper and deeper and deeper into the earth . so what weíve got in there now is cuprous oxide itís copper 1 oxide . and itís actually gone from what was a kind of clear see-through , all right itís got a colour on it , but see-through solution to something thatís very cloudy . so what weíve got there is a precipitate of copper oxide . copper is very good because it has very high thermal and electrical conductivity . what that means is that heat flows through it very well and also electricity . if you make wires for electrical transmission out of copper , when the electricity goes through them you get very much less heating than say if you made the wires out of iron , and all this heating is of course lost energy . youíd do even better if you made the wires out of silver , but silver is too expensive . ok . so letís see if we can change this reaction back . so at the moment it started out as being about 50∞c and itís shot up to about 63∞c , i imagine it was even hotter than that when it originally changed colour . so weíll see if we can take it back , iíll put that back in . i actually bought this from the british geological survey which is just down the road from here , i think it is in keyworth i think . and i just saw this and it was a christmas present from my husband and i picked it out . i just think itís really cool actually . what did your husband think of getting that as a christmas present ? he knows what iím like ! so he buys these things for me he knows iím a bit of a magpie , i like to collect shiny things , and pretty things , thatís my copper . so the colour is gradually changing , itís gone from orange and now kind of a murky yellow . you can see itís kind of green now . and again a gradual change , it wasnít a sudden spontaneous straight back to being blue and see-through , you know clear . now weíve got back to that clear solution . and again you can see on the stirrer bar all the bubbles of the oxygen , little bit of c02 forming on that . most organisms , you and me , use iron in our blood to transport oxygen , thatís what makes our blood red . but in some sorts of crustaceans , crabs and lobsters , theyíre different they use copper . they use a compound called hemocyanin , itís a blue compound of copper . cyanine is some classical word for blue . so they really have blue blood . and these hemocyanin use two atoms of copper in each molecule to transport the oxygen around the body of the crab or lobster . but itís not nearly as good as haemoglobin , so if you start running after a crab or lobster it quickly gets tired compared to running after a rabbit or something like that , which can keep going faster than you can .
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copper is found as a metal lying around in various places in the world . i believe the name came from the island of cyprus in the middle of the mediterranean , but copper has always been know even in pre-historic times people found small amounts of copper . but as we use more and more copper people have had to dig deeper and deeper mines .
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what mediterranean island gave its name to copper ?
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take a series of still , sequential images . let 's look at them one by one . faster . now , let 's remove the gaps , go faster still . wait for it ... bam ! motion ! why is that ? intellectually , we know we 're just looking at a series of still images , but when we see them change fast enough , they produce the optical illusion of appearing as a single , persistent image that 's gradually changing form and position . this effect is the basis for all motion picture technology , from our led screens of today to their 20th-century cathode ray forebearers , from cinematic film projection to the novelty toy , even , it 's been suggested , all the way back to the stone age when humans began painting on cave walls . this phenomenon of perceiving apparent motion in successive images is due to a characteristic of human perception historically referred to as `` persistence of vision . '' the term is attributed to the english-swiss physicist peter mark roget , who , in the early 19th century , used it to describe a particular defect of the eye that resulted in a moving object appearing to be still when it reached a certain speed . not long after , the term was applied to describe the opposite , the apparent motion of still images , by belgian physicist joseph plateau , inventor of the phenakistoscope . he defined persistence of vision as the result of successive afterimages , which were retained and then combined in the retina , making us believe that what we were seeing is a single object in motion . this explanation was widely accepted in the decades to follow and up through the turn of the 20th century , when some began to question what was physiologically going on . in 1912 , german psychologist max wertheimer outlined the basic primary stages of apparent motion using simple optical illusions . these experiments led him to conclude the phenomenon was due to processes which lie behind the retina . in 1915 , hugo münsterberg , a german-american pioneer in applied psychology , also suggested that the apparent motion of successive images is not due to their being retained in the eye , but is superadded by the action of the mind . in the century to follow , experiments by physiologists have pretty much confirmed their conclusions . as it relates to the illusion of motion pictures , persistence of vision has less to do with vision itself than how it 's interpreted in the brain . research has shown that different aspects of what the eye sees , like form , color , depth , and motion , are transmitted to different areas of the visual cortex via different pathways from the retina . it 's the continuous interaction of various computations in the visual cortex that stitch those different aspects together and culminate in the perception . our brains are constantly working , synchronizing what we see , hear , smell , and touch into meaningful experience in the moment-to-moment flow of the present . so , in order to create the illusion of motion in successive images , we need to get the timing of our intervals close to the speed at which our brains process the present . so , how fast is the present happening according to our brains ? well , we can get an idea by measuring how fast the images need to be changing for the illusion to work . let 's see if we can figure it out by repeating our experiment . here 's the sequence presented at a rate of one frame per two seconds with one second of black in between . at this rate of change , with the blank space separating the images , there 's no real motion perceptible . as we lessen the duration of blank space , a slight change in position becomes more apparent , and you start to get an inkling of a sense of motion between the disparate frames . one frame per second . two frames per second . four frames per second . now we 're starting to get a feeling of motion , but it 's really not very smooth . we 're still aware of the fact that we 're looking at separate images . let 's speed up . eight frames per second . 12 frames per second . it looks like we 're about there . at 24 frames per second , the motion looks even smoother . this is standard full speed . so , the point at which we lose awareness of the intervals and begin to see apparent motion seems to kick in at around eight to 12 frames per second . this is in the neighborhood of what science has determined to be the general threshold of our awareness of seeing separate images . generally speaking , we being to lose that awareness at intervals of around 100 milliseconds per image , which is equal to a frame rate of around ten frames per second . as the frame rate increases , we lose awareness of the intervals completely and are all the more convinced of the reality of the illusion .
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the term is attributed to the english-swiss physicist peter mark roget , who , in the early 19th century , used it to describe a particular defect of the eye that resulted in a moving object appearing to be still when it reached a certain speed . not long after , the term was applied to describe the opposite , the apparent motion of still images , by belgian physicist joseph plateau , inventor of the phenakistoscope . he defined persistence of vision as the result of successive afterimages , which were retained and then combined in the retina , making us believe that what we were seeing is a single object in motion .
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who invented the phenakistoscope ?
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imagine setting sail from hawaii in a canoe . your target is a small island thousands of kilometers away in the middle of the pacific ocean . that 's a body of water that covers more than 160 million square kilometers , greater than all the landmasses on earth combined . for thousands of years , polynesian navigators managed voyages like this without the help of modern navigational aids . ancient polynesians used the sun , moon , stars , planets , ocean currents , and clouds as guides that allowed them to see the ocean as a series of pathways rather than an obstacle . their voyages began around 1500 b.c . when the people who would settle polynesia first set sail from southeast asia . early polynesians eventually settled a vast area of islands spread over 40 million square kilometers of the pacific ocean . some historians believe the voyagers moved from place to place to avoid overpopulation . others , that they were driven by war . voyages became less frequent by around 1300 a.d. as polynesian societies became more rooted in specific locations . during the voyaging period , successful journeys depended on a number of factors : well-built canoes , the skill of navigators , and weather being some of the biggest . voyages relied on sturdy wa'a kaulua , or double-hulled canoes , which were powered by sails and steered with a single large oar . canoe building involved the whole community , bringing together the navigators , canoe builders , priests , chanters , and hula dancers . navigators were keen observers of the natural world . they were abundantly familiar with trade wind-generated ocean swells , which typically flow northeast or southeast . by day , navigators could identify direction by the rocking motion of their canoes caused by these swells . but sunrise and sunset were even more useful . the sun 's position indicated east and west and created low light on the ocean that made it possible to see swells directly . at night , navigators used something called a star compass , which was n't a physical object , but rather a sort of mental map . they memorized the rising and setting points of stars and constellations at different times of the year . they used those to divide the sky into four quadrants , subdivided into 32 houses , with the canoe in the middle . so , for example , when they saw the star pira ‘ atea rising from the ocean , they knew that to be northeast . they had some other tricks , too . the earth 's axis points towards hokupa'a , or the north star , so called because it 's the one fixed point in the sky as the earth rotates and always indicates north . however , it 's not visible south of the equator , so navigators there could use a constellation called newe , or the southern cross , and some mental tricks to estimate where south is . for instance , draw a line through these two stars , extend it 4.5 times , and draw another line from there to the horizon . that 's south . but the sky also contains navigational aids much closer to earth , the clouds . besides being useful weather cues , under the right conditions , they can indicate landmasses . for instance , the lagoons of pacific atolls can actually be seen reflected on the underside of clouds , if you know what to look for . and high masses of clouds can indicate mountainous islands . once navigators neared their destination , other clues , such as the flight patterns of birds , floating debris or vegetation , and types of fish in the area helped determine the proximity of land . for example , the manu-o-ku had a known flight range of 190 kilometers , and could be followed back to shore . so how do we know all of this ? partially through evidence in petroglyphs , written observations of european explorers , and polynesian oral traditions . but also by trying them out for ourselves . in 2017 , a voyaging canoe called hokulea completed a worldwide voyage using only these techniques . if that seems remarkable , remember the ancient polynesians , who through close study and kinship with nature , were able to forge these paths across an unfathomably vast , vibrant living ocean .
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the sun 's position indicated east and west and created low light on the ocean that made it possible to see swells directly . at night , navigators used something called a star compass , which was n't a physical object , but rather a sort of mental map . they memorized the rising and setting points of stars and constellations at different times of the year .
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explain how the star compass works . what would be some of the hindrances to using this tool ?
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the first standardized tests that we know of were administered in china over 2,000 years ago during the han dynasty . chinese officials used them to determine aptitude for various government posts . the subject matter included philosophy , farming , and even military tactics . standardized tests continued to be used around the world for the next two millennia , and today , they 're used for everything from evaluating stair climbs for firefighters in france to language examinations for diplomats in canada to students in schools . some standardized tests measure scores only in relation to the results of other test takers . others measure performances on how well test takers meet predetermined criteria . so the stair climb for the firefighter could be measured by comparing the time of the climb to that of all other firefighters . this might be expressed in what many call a bell curve . or it could be evaluated with reference to set criteria , such as carrying a certain amount of weight a certain distance up a certain number of stairs . similarly , the diplomat might be measured against other test-taking diplomats , or against a set of fixed criteria , which demonstrate different levels of language proficiency . and all of these results can be expressed using something called a percentile . if a diplomat is in the 70th percentile , 70 % of test takers scored below her . if she scored in the 30th percentile , 70 % of test takers scored above her . although standardized tests are sometimes controversial , they 're simply a tool . as a thought experiment , think of a standardized test as a ruler . a ruler 's usefulness depends on two things . first , the job we ask it to do . our ruler ca n't measure the temperature outside or how loud someone is singing . second , the ruler 's usefulness depends on its design . say you need to measure the circumference of an orange . our ruler measures length , which is the right quantity , but it has n't been designed with the flexibility required for the task at hand . so , if standardized tests are given the wrong job , or are n't designed properly , they may end up measuring the wrong things . in the case of schools , students with test anxiety may have trouble performing their best on a standardized test , not because they do n't know the answers , but because they 're feeling too nervous to share what they 've learned . students with reading challenges may struggle with the wording of a math problem , so their test results may better reflect their literacy rather than numeracy skills . and students who were confused by examples on tests that contain unfamiliar cultural references may do poorly , telling us more about the test taker 's cultural familiarity than their academic learning . in these cases , the tests may need to be designed differently . standardized tests can also have a hard time measuring abstract characteristics or skills , such as creativity , critical thinking , and collaboration . if we design a test poorly , or ask it to do the wrong job , or a job it 's not very good at , the results may not be reliable or valid . reliability and validity are two critical ideas for understanding standardized tests . to understand the difference between them , we can use the metaphor of two broken thermometers . an unreliable thermometer gives you a different reading each time you take your temperature , and the reliable but invalid thermometer is consistently ten degrees too hot . validity also depends on accurate interpretations of results . if people say results of a test mean something they do n't , that test may have a validity problem . just as we would n't expect a ruler to tell us how much an elephant weighs , or what it had for breakfast , we ca n't expect standardized tests alone to reliably tell us how smart someone is , how diplomats will handle a tough situation , or how brave a firefighter might turn out to be . so standardized tests may help us learn a little about a lot of people in a short time , but they usually ca n't tell us a lot about a single person . many social scientists worry about test scores resulting in sweeping and often negative changes for test takers , sometimes with long-term life consequences . we ca n't blame the tests , though . it 's up to us to use the right tests for the right jobs , and to interpret results appropriately .
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an unreliable thermometer gives you a different reading each time you take your temperature , and the reliable but invalid thermometer is consistently ten degrees too hot . validity also depends on accurate interpretations of results . if people say results of a test mean something they do n't , that test may have a validity problem . just as we would n't expect a ruler to tell us how much an elephant weighs , or what it had for breakfast , we ca n't expect standardized tests alone to reliably tell us how smart someone is , how diplomats will handle a tough situation , or how brave a firefighter might turn out to be .
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if a scale provides unreliable results , which of the following is possible ?
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what keeps us healthy and happy as we go through life ? if you were going to invest now in your future best self , where would you put your time and your energy ? there was a recent survey of millennials asking them what their most important life goals were , and over 80 percent said that a major life goal for them was to get rich . and another 50 percent of those same young adults said that another major life goal was to become famous . ( laughter ) and we 're constantly told to lean in to work , to push harder and achieve more . we 're given the impression that these are the things that we need to go after in order to have a good life . pictures of entire lives , of the choices that people make and how those choices work out for them , those pictures are almost impossible to get . most of what we know about human life we know from asking people to remember the past , and as we know , hindsight is anything but 20/20 . we forget vast amounts of what happens to us in life , and sometimes memory is downright creative . but what if we could watch entire lives as they unfold through time ? what if we could study people from the time that they were teenagers all the way into old age to see what really keeps people happy and healthy ? we did that . the harvard study of adult development may be the longest study of adult life that 's ever been done . for 75 years , we 've tracked the lives of 724 men , year after year , asking about their work , their home lives , their health , and of course asking all along the way without knowing how their life stories were going to turn out . studies like this are exceedingly rare . almost all projects of this kind fall apart within a decade because too many people drop out of the study , or funding for the research dries up , or the researchers get distracted , or they die , and nobody moves the ball further down the field . but through a combination of luck and the persistence of several generations of researchers , this study has survived . about 60 of our original 724 men are still alive , still participating in the study , most of them in their 90s . and we are now beginning to study the more than 2,000 children of these men . and i 'm the fourth director of the study . since 1938 , we 've tracked the lives of two groups of men . the first group started in the study when they were sophomores at harvard college . they all finished college during world war ii , and then most went off to serve in the war . and the second group that we 've followed was a group of boys from boston 's poorest neighborhoods , boys who were chosen for the study specifically because they were from some of the most troubled and disadvantaged families in the boston of the 1930s . most lived in tenements , many without hot and cold running water . when they entered the study , all of these teenagers were interviewed . they were given medical exams . we went to their homes and we interviewed their parents . and then these teenagers grew up into adults who entered all walks of life . they became factory workers and lawyers and bricklayers and doctors , one president of the united states . some developed alcoholism . a few developed schizophrenia . some climbed the social ladder from the bottom all the way to the very top , and some made that journey in the opposite direction . the founders of this study would never in their wildest dreams have imagined that i would be standing here today , 75 years later , telling you that the study still continues . every two years , our patient and dedicated research staff calls up our men and asks them if we can send them yet one more set of questions about their lives . many of the inner city boston men ask us , `` why do you keep wanting to study me ? my life just is n't that interesting . '' the harvard men never ask that question . ( laughter ) to get the clearest picture of these lives , we do n't just send them questionnaires . we interview them in their living rooms . we get their medical records from their doctors . we draw their blood , we scan their brains , we talk to their children . we videotape them talking with their wives about their deepest concerns . and when , about a decade ago , we finally asked the wives if they would join us as members of the study , many of the women said , `` you know , it 's about time . '' ( laughter ) so what have we learned ? what are the lessons that come from the tens of thousands of pages of information that we 've generated on these lives ? well , the lessons are n't about wealth or fame or working harder and harder . the clearest message that we get from this 75-year study is this : good relationships keep us happier and healthier . period . we 've learned three big lessons about relationships . the first is that social connections are really good for us , and that loneliness kills . it turns out that people who are more socially connected to family , to friends , to community , are happier , they 're physically healthier , and they live longer than people who are less well connected . and the experience of loneliness turns out to be toxic . people who are more isolated than they want to be from others find that they are less happy , their health declines earlier in midlife , their brain functioning declines sooner and they live shorter lives than people who are not lonely . and the sad fact is that at any given time , more than one in five americans will report that they 're lonely . and we know that you can be lonely in a crowd and you can be lonely in a marriage , so the second big lesson that we learned is that it 's not just the number of friends you have , and it 's not whether or not you 're in a committed relationship , but it 's the quality of your close relationships that matters . it turns out that living in the midst of conflict is really bad for our health . high-conflict marriages , for example , without much affection , turn out to be very bad for our health , perhaps worse than getting divorced . and living in the midst of good , warm relationships is protective . once we had followed our men all the way into their 80s , we wanted to look back at them at midlife and to see if we could predict who was going to grow into a happy , healthy octogenarian and who was n't . and when we gathered together everything we knew about them at age 50 , it was n't their middle age cholesterol levels that predicted how they were going to grow old . it was how satisfied they were in their relationships . the people who were the most satisfied in their relationships at age 50 were the healthiest at age 80 . and good , close relationships seem to buffer us from some of the slings and arrows of getting old . our most happily partnered men and women reported , in their 80s , that on the days when they had more physical pain , their mood stayed just as happy . but the people who were in unhappy relationships , on the days when they reported more physical pain , it was magnified by more emotional pain . and the third big lesson that we learned about relationships and our health is that good relationships do n't just protect our bodies , they protect our brains . it turns out that being in a securely attached relationship to another person in your 80s is protective , that the people who are in relationships where they really feel they can count on the other person in times of need , those people 's memories stay sharper longer . and the people in relationships where they feel they really ca n't count on the other one , those are the people who experience earlier memory decline . and those good relationships , they do n't have to be smooth all the time . some of our octogenarian couples could bicker with each other day in and day out , but as long as they felt that they could really count on the other when the going got tough , those arguments did n't take a toll on their memories . so this message , that good , close relationships are good for our health and well-being , this is wisdom that 's as old as the hills . why is this so hard to get and so easy to ignore ? well , we 're human . what we 'd really like is a quick fix , something we can get that 'll make our lives good and keep them that way . relationships are messy and they 're complicated and the hard work of tending to family and friends , it 's not sexy or glamorous . it 's also lifelong . it never ends . the people in our 75-year study who were the happiest in retirement were the people who had actively worked to replace workmates with new playmates . just like the millennials in that recent survey , many of our men when they were starting out as young adults really believed that fame and wealth and high achievement were what they needed to go after to have a good life . but over and over , over these 75 years , our study has shown that the people who fared the best were the people who leaned in to relationships , with family , with friends , with community . so what about you ? let 's say you 're 25 , or you 're 40 , or you 're 60 . what might leaning in to relationships even look like ? well , the possibilities are practically endless . it might be something as simple as replacing screen time with people time or livening up a stale relationship by doing something new together , long walks or date nights , or reaching out to that family member who you have n't spoken to in years , because those all-too-common family feuds take a terrible toll on the people who hold the grudges . i 'd like to close with a quote from mark twain . more than a century ago , he was looking back on his life , and he wrote this : `` there is n't time , so brief is life , for bickerings , apologies , heartburnings , callings to account . there is only time for loving , and but an instant , so to speak , for that . '' the good life is built with good relationships . thank you . ( applause )
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for 75 years , we 've tracked the lives of 724 men , year after year , asking about their work , their home lives , their health , and of course asking all along the way without knowing how their life stories were going to turn out . studies like this are exceedingly rare . almost all projects of this kind fall apart within a decade because too many people drop out of the study , or funding for the research dries up , or the researchers get distracted , or they die , and nobody moves the ball further down the field .
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why do long-term studies like this typically not work ?
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translator : andrea mcdonough reviewer : jessica ruby there are all sorts of things that happen every day that might make you ask , `` why ? why do we drive on a parkway and park on a driveway ? why does my hair get frizzy when it 's humid ? and why do my fingers get all pruney when they 're wet ? '' often we simply ca n't know the answers to these questions . but progress can often be made , and , when it comes to your pruney fingers , scientists have a few interesting ideas . the story here begins with an observation made in the 1930s in the emergency room . doctors noticed that patients with nerve damage to their hands did not get pruney fingertips like most of us do in a bath , which might make you wonder , `` why would primates want wrinkly fingers , presumably when it 's rainy or dewy ? '' what could this trait be for ? what if these wrinkles functioned like rain treads ? think about car tires . when the ground is dry , it 's generally best to have smooth tires , and race cars do . smooth tires means more rubber or surface area in contact with the road , which gives them better grip . but in rainy and muddy conditions , it 's a different story , and here 's where treads come into play . treads reduce the amount of rubber on the road , but they help channel out water when it rains , lowering the risk of hydroplaning . well , if your fingers really are like rain treads , you should be able to predict the optimal shape for them , right ? so , what would the predicted wrinkle shapes be ? that is , are our prunes actually the right shape to be rain treads ? let 's take a detour into rivers . when we think of river networks , we usually imagine lots of smaller river channels joining to make larger river channels downstream , which is what happens in concave basins . in these cases , the divides , the regions between the river segments , are disconnected from one another and diverge away from one another uphill . but river networks look fundamentally different on convex promontories or protrusions . here , the river channels are disconnected from one another and diverge away from one another downstream , not very river-like . in these cases , it 's the divides that link together to form a tree , with its trunk uphill at the top of the promontory . here , it 's the divides that look more traditionally river-like . if our pruney fingers are drainage networks , designed to channel out water when they grip , then we expect to find similar shapes on our fingers as we find out there among rivers . there should be a tree network of divides , or ridges , with their trunk near the top of the fingertip and with their more leaky parts reaching out downhill , away from the tip . the channels themselves , through which the water is channeled during a grip , should not connect to one another , and instead should diverge away from one another downhill . if pruney fingers are rain treads , then they should look like the river networks on convex promontories . in fact , that 's exactly the morphology we find among pruney fingers ! when we grip , then , our pruney wrinkles really do channel out the water . but does it actually help us grip ? new behavioral experiments have shown that they do . in a task where subjects had to grasp wet marbles and move them through a hole and out the other side , those with pruney fingers finished the task significantly faster than those with smooth fingers . pruney fingers not only ought to enhance grip in wet conditions but do . so , pruney fingers may be a crucial part of the primate repertoire . maybe , once primates lost their claws in favor of fingernails , rain treads were needed to deal with the especially challenging , often wet , grip-heavy forest habitats . by looking closely at the mysteries in our world and trying to find things that look similar , like our wet fingers and rain treads , we can come up with ideas about what 's happening . and that 's a good way to think about all sorts of questions in life , too .
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the story here begins with an observation made in the 1930s in the emergency room . doctors noticed that patients with nerve damage to their hands did not get pruney fingertips like most of us do in a bath , which might make you wonder , `` why would primates want wrinkly fingers , presumably when it 's rainy or dewy ? '' what could this trait be for ?
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what advantage might pruney fingers have for primates ?
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this just in : `` thief robs town with world 's largest chocolate bunny . '' wait , so are we talking about this , or this ? that 's a classic case of a misplaced modifier , a common grammatical mistake that can dramatically change the meaning of a sentence . and lest you think this is a bit far-fetched , confusing headlines like this appear all the time . modifiers are words , phrases , and clauses that add information about other parts of a sentence , which is usually helpful . but when modifiers are n't linked clearly enough to the words they 're actually referring to , they can create unintentional ambiguity . that happens because the modifying words , in this case , `` with world 's largest chocolate bunny , '' modify the wrong thing , the robber 's actions instead of the town . to correct this particular sentence , we simply rephrase to make it clearer what the modifying phrase is talking about . `` town with world 's largest chocolate bunny robbed by thief . '' now , at least it 's clear that the thief was n't armed with a giant chocolate animal . sometimes , modifying words , phrases , or clauses do n't appear to be modifying anything at all . that 's called a dangling modifier . `` having robbed the bank in record time , it was possible to make off with the town 's chocolate rabbit as well . '' the modifying phrase in this sentence seems unrelated to anything else , and so we 're clueless about who the chocolate-loving criminal could possibly be . giving the modifier something to modify will solve the problem . then there 's another group called the squinting modifiers because they 're stuck between two things and could feasibly refer to either . often , these modifiers are adverbs , like the one in this sentence : `` robbers who steal chocolate bunnies rapidly attract the outrage of onlookers . '' `` rapidly '' is the modifier , here , but what 's not clear is whether it 's referring to the speed of the chocolate thievery , or how quickly it alerts the furious onlookers . to clarify , we can either put the modifier closer to its intended phrase , which works in some cases , or we can entirely reword the sentence so that the modifier no longer squints , but clearly applies to only one part . `` chocolate bunny-thieving robbers rapidly attract the outrage of onlookers . '' justice will eventually come to the chocolate thief , but in the meantime , our task is to avoid verbal ambiguity by making it clear which parts of the sentences modifiers belong to . that way , we can at least maintain grammatical law and order .
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justice will eventually come to the chocolate thief , but in the meantime , our task is to avoid verbal ambiguity by making it clear which parts of the sentences modifiers belong to . that way , we can at least maintain grammatical law and order .
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modifiers are always wrong ; there 's no correct way to use them .
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on a december afternoon in chicago during the middle of world war ii , scientists cracked open the nucleus at the center of the uranium atom and turned nuclear mass into energy over and over again . they did this by creating for the first time a chain reaction inside a new engineering marvel : the nuclear reactor . since then , the ability to mine great amounts of energy from uranium nuclei has led some to bill nuclear power as a plentiful utopian source of electricity . a modern nuclear reactor generates enough electricity from one kilogram of fuel to power an average american household for nearly 34 years . but rather than dominate the global electricity market , nuclear power has declined from an all-time high of 18 % in 1996 to 11 % today . and it 's expected to drop further in the coming decades . what happened to the great promise of this technology ? it turns out nuclear power faces many hurdles , including high construction costs and public opposition . and behind these problems lie a series of unique engineering challenges . nuclear power relies on the fission of uranium nuclei and a controlled chain reaction that reproduces this splitting in many more nuclei . the atomic nucleus is densely packed with protons and neutrons bound by a powerful nuclear force . most uranium atoms have a total of 238 protons and neutrons , but roughly one in every 140 lacks three neutrons , and this lighter isotope is less tightly bound . compared to its more abundant cousin , a strike by a neutron easily splits the u-235 nuclei into lighter , radioactive elements called fission products , in addition to two to three neutrons , gamma rays , and a few neutrinos . during fission , some nuclear mass transforms into energy . a fraction of the newfound energy powers the fast-moving neutrons , and if some of them strike uranium nuclei , fission results in a second larger generation of neutrons . if this second generation of neutrons strike more uranium nuclei , more fission results in an even larger third generation , and so on . but inside a nuclear reactor , this spiraling chain reaction is tamed using control rods made of elements that capture excess neutrons and keep their number in check . with a controlled chain reaction , a reactor draws power steadily and stably for years . the neutron-led chain reaction is a potent process driving nuclear power , but there 's a catch that can result in unique demands on the production of its fuel . it turns out , most of the neutrons emitted from fission have too much kinetic energy to be captured by uranium nuclei . the fission rate is too low and the chain reaction fizzles out . the first nuclear reactor built in chicago used graphite as a moderator to scatter and slow down neutrons just enough to increase their capture by uranium and raise the rate of fission . modern reactors commonly use purified water as a moderator , but the scattered neutrons are still a little too fast . to compensate and keep up the chain reaction , the concentration of u-235 is enriched to four to seven times its natural abundance . today , enrichment is often done by passing a gaseous uranium compound through centrifuges to separate lighter u-235 from heavier u-238 . but the same process can be continued to highly enrich u-235 up to 130 times its natural abundance and create an explosive chain reaction in a bomb . methods like centrifuge processing must be carefully regulated to limit the spread of bomb-grade fuel . remember , only a fraction of the released fission energy goes into speeding up neutrons . most of the nuclear power goes into the kinetic energy of the fission products . those are captured inside the reactor as heat by a coolant , usually purified water . this heat is eventually used to drive an electric turbine generator by steam just outside the reactor . water flow is critical not only to create electricity , but also to guard against the most dreaded type of reactor accident , the meltdown . if water flow stops because a pipe carrying it breaks , or the pumps that push it fail , the uranium heats up very quickly and melts . during a nuclear meltdown , radioactive vapors escape into the reactor , and if the reactor fails to hold them , a steel and concrete containment building is the last line of defense . but if the radioactive gas pressure is too high , containment fails and the gasses escape into the air , spreading as far and wide as the wind blows . the radioactive fission products in these vapors eventually decay into stable elements . while some decay in a few seconds , others take hundreds of thousands of years . the greatest challenge for a nuclear reactor is to safely contain these products and keep them from harming humans or the environment . containment does n't stop mattering once the fuel is used up . in fact , it becomes an even greater storage problem . every one to two years , some spent fuel is removed from reactors and stored in pools of water that cool the waste and block its radioactive emissions . the irradiated fuel is a mix of uranium that failed to fission , fission products , and plutonium , a radioactive material not found in nature . this mix must be isolated from the environment until it has all safely decayed . many countries propose deep time storage in tunnels drilled far underground , but none have been built , and there 's great uncertainty about their long-term security . how can a nation that has existed for only a few hundred years plan to guard plutonium through its radioactive half-life of 24,000 years ? today , many nuclear power plants sit on their waste , instead , storing them indefinitely on site . apart from radioactivity , there 's an even greater danger with spent fuel . plutonium can sustain a chain reaction and can be mined from the waste to make bombs . storing spent fuel is thus not only a safety risk for the environment , but also a security risk for nations . who should be the watchmen to guard it ? visionary scientists from the early years of the nuclear age pioneered how to reliably tap the tremendous amount of energy inside an atom - as an explosive bomb and as a controlled power source with incredible potential . but their successors have learned humbling insights about the technology 's not-so-utopian industrial limits . mining the subatomic realm makes for complex , expensive , and risky engineering .
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the fission rate is too low and the chain reaction fizzles out . the first nuclear reactor built in chicago used graphite as a moderator to scatter and slow down neutrons just enough to increase their capture by uranium and raise the rate of fission . modern reactors commonly use purified water as a moderator , but the scattered neutrons are still a little too fast .
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what substance is used as a moderator to scatter and slow down neutrons just enough to increase their capture by uranium and raise the rate of fission ?
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translator : andrea mcdonough reviewer : bedirhan cinar blue whales are the largest animals that have ever roamed the planet . they 're at least two times as big as the biggest dinosaurs , `` that 's big ! '' the length of a basketball court , and as heavy as 40 african elephants . if that 's not enough to make you marvel , here 's something that will . they 're grown to this enormous size by feeding exclusively on tiny shrimp-like creatures called krill that are no bigger than your little finger . in many ways , the sheer size of krill seems to have driven the evolution of the blue whale . see , krill are so small but are found in dense patches . for increased efficiency , blue whales have evolved to use a feeding strategy called lunge feeding . basically , the whale accelerates towards a prey patch and opens its mouth wide . to increase the capacity , its mouth expands . the special , accordion-like blubber layer that extends from its snout to its belly button enables the whale to engulf large quantities of prey-laden water . with each giant gulp , the whale takes in 125 % of its body weight in water and krill . the whale must then expel the water while retaining the yummy krill . to do this , it uses its baleen , the comb-like structure made of the same stuff our nails and hair are made of , and its tongue . it 's pretty crazy that the blue whale 's heart is as big as a small car , a child could crawl through its arteries , its tongue weighs as much as an elephant , but its esophagus is so small , the whale could choke on a loaf of bread . these whales are really not designed to feed on anything larger than krill . it 's estimated that blue whales eat four tons of krill per day . because of the incredible design , each dive provides the blue whale with 90 times as much energy as is used . every mouthful of krill provides almost 480,000 calories , the same amount you get from eating 1,900 hamburgers . but , why are blue whales so big ? blue whales are considerably larger than the largest living land animal , the elephant . the heavier an animal is , the greater its relative surface area . as weight increases , there 's a point at which the legs of that animal would simply collapse . that explains why elephants do n't stand on the delicate legs of a horse . they need legs shaped like stout pedestals to hold their bodies up against gravity . in water , the situation is quite different . buoyancy counteracts the gravitational pull on the body and their great bulk is therefore partially supported by the water . so , the ocean is a great place for species that want to grow bigger . the other secret to their size is their diet . by evolving such a huge mouth , the whale 's have specialized to catch enormous quantities of highly abundant and nutritious prey , which provides the energy needed to grow so big . but , now maybe you 're wondering why blue whales are n't any bigger ? after all , the ocean sounds like nirvana for any growing beast . well , while lunge feeding may have allowed blue whales to become the biggest animal to have ever roamed the planet , by enabling them to feed efficiently in dense prey patches , it is n't cost free . scientists compared all the costs involved with lunge feeding to the energy gained from the krill they eat . what they found is that when the whale 's body increases in size , the energy that body demands rises faster than the extra energy they get from their food . feeding whales needs 15 times the energy required to remain still and 5 times more energy than used when swimming . calculations show that the largest a lunge feeder can grow is 33 meters , pretty much blue whale size . turns out blue whales have a lot to thank krill for : neat , evolutionary adaptations that would not have been possible if krill were not so small . it 's incredible that these tiny creatures have allowed blue whales to really push the limits of size on our planet . makes you wonder if that old adage , `` you are what you eat , '' really does apply in blue whale world .
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feeding whales needs 15 times the energy required to remain still and 5 times more energy than used when swimming . calculations show that the largest a lunge feeder can grow is 33 meters , pretty much blue whale size . turns out blue whales have a lot to thank krill for : neat , evolutionary adaptations that would not have been possible if krill were not so small .
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based on scientific research , what is the largest a lunge feeder can grow ?
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translator : andrea mcdonough reviewer : bedirhan cinar what do horror movies and comedies have in common ? the two genres might seem totally different , but the reason they 're both so popular is perhaps because what they have in common : their use of dramatic irony . first , let 's clarify . there are three types of irony out there . situational irony is when you expect one thing , but get the opposite . verbal irony is when someone says something , but truly means the opposite . dramatic irony , though , is what we will be looking at right now . dramatic irony is when the audience seems to know more about an event , a situation , or a conversation than the characters in the movie , on the show , or in the book do . the audience is in on a secret that the characters have missed . this is a great story-telling device that creates tremendous emotion within that text . think about it for a moment . how does it feel when , in a horror film , you know that the scary villain is hiding behind that door in the darkened room . the music becomes eerie , the lighting creates complete shadows , this has to be bad for the hero ! of course , though , that hero must enter the room to find the villain . you feel tremendous tension and the suspense of knowing that someone will jump out and be scary , but you just do n't know when . that tension is dramatic irony : you know something more than the characters in the film . now , take the typical comedy . there will probably be some type of `` misunderstanding '' . again , we know more of what is going on than the characters do . picture two characters making a plan for a birthday surprise for their roommate while that roommate overhears the entire conversation from the hallway . from there , confusion and misunderstanding occur , and the tension builds . this is n't the same tension as the horror film since it is probably pretty funny as the character tries to figure out the whos and the whats , but it serves as a great example of the tension and suspense of dramatic irony . this tension or suspense in both genres drives the story and keeps the plot progressing . the audience wants , no , needs , to see the tension of the dramatic irony broken either by the scary person jumping out of the shadows or by someone finally revealing someone 's true identity and clearing up the confusion . so , when you feel like you are in on a secret , that is dramatic irony , a hallmark of all the great writers , from shakespeare to hitchcock .
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verbal irony is when someone says something , but truly means the opposite . dramatic irony , though , is what we will be looking at right now . dramatic irony is when the audience seems to know more about an event , a situation , or a conversation than the characters in the movie , on the show , or in the book do .
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dramatic irony is when the audience is in on a secret that the __________ .
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there 's a lot of buzz in the news about de-extinction . with the growing interest in technologies and research , that could possibly bring animals and plants back from being , well , extinct . one of the candidates high on that list is the woolly mammoth . they 're the closest relatives to our living asian elephants today , and only widely disappeared about 10,000 years ago . with some isolated populations hanging on until about 4,700 years ago . that may seem like a long time , but at that period in the not-so-distant past , glass was being invented and the great pyramids of giza were being built . so , really , it 's a blip in the scheme of things . since woolly mammoth 's genetic information has been so well preserved in the permafrost , where recent specimens have been discovered , scientists have been able to sequence their genomes and now different groups are trying to figure out a way to insert mammoth genes into living elephant cells and maybe , in a way , bring them back . but my question is , why mammoths ? why not , say , mastodons ? no , not the heavy metal group , the late miocene megafauna . modern day elephants , mammoths and mastodons are all in the order proboscidea , along with other exinct tusked creatures , like palaeomastodons and gomphotheres . from the outside , mammoths and mastodons may look pretty similar , but they 've been different for a very long time . about 25 million years . mastodons were on earth long before the mammoths , who showed up a little late to the pleistocene party about 20 million years later . so you could n't hope to have good luck splicing mastodon dna into the asian elephant genome . that 's like putting human cells into a gibbon . it would n't work because the two are too genetically different . in addition to genetic differences between mammoths and mastodons , they 're also morphologically different . this is most obviously seen in their teeth . mammoths have large , flat , grinding surfaces on top of their molars , whereas mastodons have giant , mountain-like cusps . these cusps even inspired their scientific name , from the greek word `` masto '' for `` breast '' and `` odon '' for `` tooth . '' literally breast tooth . the shape of their teeth gives us clues about their diets , too . mammoths were grazers , like cows and elephants today and as such , they have flat grinding surfaces on their teeth for breaking down grasses . mastodons were browsers , like goats . the bulbous cusps on their teeth were useful for breaking down sticks and shrubs . so , remember , mammoths : cows . matsodons : breast-toothed goats . in addition to differences in their dentition , mastodons were shorter stockier than mammoths with smaller ears , but there were some exceptions . mammoths and mastodons are in two different genera , mammut and mammuthus . there were four different mastodon species and ten different species of mammoth . you 're probably most familiar with the woolly mammoth but there was also a pygmy species , the dwarf mammoth , which was about as tall as i am . this species was found on the channel islands off of california and its small size was most likely result of island dwarfism . this can happen when a large species gets isolated on an island , since smaller animals require fewer food resources , and in the absence of predators , small animals tend to breed more quickly than their larger counterparts . as to how they got to the island , how else ? they swam ! elephants today are great long-distance swimmers with their built-in snorkels and buoyant mass . smelling delicious grasses from mainland california , a group of columbian mammoths departed the coast , swimming out into the ocean towards the smell . fast forward 30,000 years and congratulations ! almost puppy sized mammoths . while there is n't yet a conclusive answer as to what caused the extinction for both mammoths and mastodons in the last 10,000 years , whether it was from over-hunting by humans or climate related changes , a few questions remain . if we can resurrect the mammoth genome , should we ? and where would we put them ?
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you 're probably most familiar with the woolly mammoth but there was also a pygmy species , the dwarf mammoth , which was about as tall as i am . this species was found on the channel islands off of california and its small size was most likely result of island dwarfism . this can happen when a large species gets isolated on an island , since smaller animals require fewer food resources , and in the absence of predators , small animals tend to breed more quickly than their larger counterparts .
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name two factors that lead to island dwarfism .
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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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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 .
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artifacts are objects from the past that inform us about the way that people lived . choose any artifact from the hagia sophia and retrace its life from the time it was created to the to the time it was discovered . use the artifact to trace the social history of the people who used it , admired it and eventually recovered or restored it . which life would the artifact prefer , their past life or present one ?
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for most of history , humans had no idea what purpose the heart served . in fact , the organ so confused leonardo da vinci , that he gave up studying it . although everyone could feel their own heart beating , it was n't always clear what each thump was achieving . now we know that the heart pumps blood . but that fact was n't always obvious , because if a heart was exposed or taken out , the body would perish quickly . it 's also impossible to see through the blood vessels , and even if that were possible , the blood itself is opaque , making it difficult to see the heart valves working . even in the 21st century , only a few people in surgery teams have actually seen a working heart . internet searches for heart function , point to crude models , diagrams or animations that do n't really show how it works . it 's as if there has been a centuries old conspiracy amongst teachers and students to accept that heart function can not be demonstrated . meaning that the next best thing is simply to cut it open and label the parts . that way students might not fully grasp the way it works , but can superficially understand it , learning such concepts as the heart is a four-chambered organ , or potentially misleading statements like , mammals have a dual-circulation : one with blood going to the lungs and back , and another to the body and back . in reality , mammals have a figure-eight circulation . blood goes from one heart pump to the lungs , back to the second heart pump , which sends it to the body , and then back to the first pump . that 's an important difference because it marks two completely different morphologies . this confusion makes many students wary of the heart in biology lessons , thinking it signals an intimidating subject full of complicated names and diagrams . only those who end up studying medicine compeltely understand how it all actually works . that 's when its functions become apparent as medics get to observe the motion of the heart 's valves . so , let 's imagine you 're a medic for a day . what you 'll need to get started is a whole fresh heart , like one from a sheep or pig . immerse this heart in water and you 'll see that it does n't pump when squeezed by hand . that 's because water does n't enter the heart cleanly enough for the pumping mechanism to work . we can solve this problem in an extraordinarly simple way . simply identify the two atria and cut them off , trimming them down to the tops of the ventricles . this makes the heart look less complicated because the atria have several incoming veins attached . so without them there , the only vessels remaining are the two major heart arteries : the aorta and pulmonary artery , which rise like white columns from between the ventricles . it looks -- and really is -- very simple . if you run water into the right ventricle from a tap ( the left also works , but less spectacularly ) , you 'll see that the ventricular valve tries to close against the incoming stream . and then ventricle inflates with water . squeeze the ventricle and a stream of water squirts out of the pulmonary artery . the ventricular valves , called the tricuspid in the right ventricle and the mitral in the left , can be seen through the clear water opening and closing like parachutes as the ventricle is rhythmically squeezed . this flow of water mimics the flow of blood in life . the valves are completely efficient . you 'll notice they do n't leak at all when the ventricles are squeezed . over time , they also close against each other with very little wear and tear , which explains how this mechanism continues to work seamlessly for more than 2 billion beats a heart gives in its lifetime . now , anyone studying the heart can hold one in their hands , make it pump for real and watch the action unfold . so place your hand above your own and feel its rhymic beat . understanding how this dependable inner pump works gives new resonance to the feeling you get when you run a race , drink too much caffeine or catch the eye of the one you love .
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if you run water into the right ventricle from a tap ( the left also works , but less spectacularly ) , you 'll see that the ventricular valve tries to close against the incoming stream . and then ventricle inflates with water . squeeze the ventricle and a stream of water squirts out of the pulmonary artery . the ventricular valves , called the tricuspid in the right ventricle and the mitral in the left , can be seen through the clear water opening and closing like parachutes as the ventricle is rhythmically squeezed .
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when you compress the heart in this demonstration , why does the water squirt out of the artery ?
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imagine you 're watching a runaway trolley barreling down the tracks straight towards five workers who ca n't escape . you happen to be standing next to a switch that will divert the trolley onto a second track . here 's the problem . that track has a worker on it , too , but just one . what do you do ? do you sacrifice one person to save five ? this is the trolley problem , a version of an ethical dilemma that philosopher philippa foot devised in 1967 . it 's popular because it forces us to think about how to choose when there are no good choices . do we pick the action with the best outcome or stick to a moral code that prohibits causing someone 's death ? in one survey , about 90 % of respondents said that it 's okay to flip the switch , letting one worker die to save five , and other studies , including a virtual reality simulation of the dilemma , have found similar results . these judgments are consistent with the philosophical principle of utilitarianism which argues that the morally correct decision is the one that maximizes well-being for the greatest number of people . the five lives outweigh one , even if achieving that outcome requires condemning someone to death . but people do n't always take the utilitarian view , which we can see by changing the trolley problem a bit . this time , you 're standing on a bridge over the track as the runaway trolley approaches . now there 's no second track , but there is a very large man on the bridge next to you . if you push him over , his body will stop the trolley , saving the five workers , but he 'll die . to utilitarians , the decision is exactly the same , lose one life to save five . but in this case , only about 10 % of people say that it 's ok to throw the man onto the tracks . our instincts tell us that deliberately causing someone 's death is different than allowing them to die as collateral damage . it just feels wrong for reasons that are hard to explain . this intersection between ethics and psychology is what 's so interesting about the trolley problem . the dilemma in its many variations reveal that what we think is right or wrong depends on factors other than a logical weighing of the pros and cons . for example , men are more likely than women to say it 's okay to push the man over the bridge . so are people who watch a comedy clip before doing the thought experiment . and in one virtual reality study , people were more willing to sacrifice men than women . researchers have studied the brain activity of people thinking through the classic and bridge versions . both scenarios activate areas of the brain involved in conscious decision-making and emotional responses . but in the bridge version , the emotional response is much stronger . so is activity in an area of the brain associated with processing internal conflict . why the difference ? one explanation is that pushing someone to their death feels more personal , activating an emotional aversion to killing another person , but we feel conflicted because we know it 's still the logical choice . trolleyology has been criticized by some philosophers and psychologists . they argue that it does n't reveal anything because its premise is so unrealistic that study participants do n't take it seriously . but new technology is making this kind of ethical analysis more important than ever . for example , driver-less cars may have to handle choices like causing a small accident to prevent a larger one . meanwhile , governments are researching autonomous military drones that could wind up making decisions of whether they 'll risk civilian casualties to attack a high-value target . if we want these actions to be ethical , we have to decide in advance how to value human life and judge the greater good . so researchers who study autonomous systems are collaborating with philosophers to address the complex problem of programming ethics into machines , which goes to show that even hypothetical dilemmas can wind up on a collision course with the real world .
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the five lives outweigh one , even if achieving that outcome requires condemning someone to death . but people do n't always take the utilitarian view , which we can see by changing the trolley problem a bit . this time , you 're standing on a bridge over the track as the runaway trolley approaches .
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in surveys , how do people say they would respond to the classic trolley problem ?
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so copernicium , or copernicium as the discoverers would prefer it to be pronounced , is the latest name to go up on the periodic table and it is really very exciting because it is the first time in as many years that a new name has appeared . and not only has it appeared but quite excitingly , it has appeared with a bit of controversy - what should the symbol be ? the first suggestion was that it should be called , the symbol should be cp , capital c with little p and that has got really quite an argument inorganic chemists who use organic groups in their compounds got quite excited because cp is the symbol that is used for cyclopentadienyl ion which binds to all sorts of different metals and then it was discovered or realised that , many , many years ago , cp was used as an alternative symbol for element number 71 , lutetium , which in some countries we called cassiopeium . and i ’ ve looked in lots and lots of books that i have got at home and i can ’ t find one of them that uses this name , but the reason why it is important is because now more and more old papers , old books are being digitised on the internet , if you start searching for the symbol cp it will start throwing up old papers and cause confusion . so the decision has been made by the international union of pure and applied chemistry or the recommendation is that the symbol should be cn , capital c , little n. and i think that this is a very sensible suggestion because it is unlikely that it can be confused with cyanide which is capital c , capital n. and it is also nice for our chinese colleagues because cn is the domain name for chinese websites and i think most chemists will be very happy with that . the element itself was first made quite a few years ago , and it ’ s made like all these heavy elements by taking the nuclei of two atoms that are lighter and banging them together and if you are aiming for element 112 then you need to take 2 nuclei , which have atomic numbers which when you add them together come up to 112 , so in this case you take lead which is atomic number 82 and so to get from 82 to 112 you need to add 30 , so you accelerate zinc atoms which have atomic number of 30 towards these in a high speed accelerator and every so often , and quite rarely , these two nuclei fuse together to give you an element or an atom of element 112 . when you make the atom , it exists , for a short time which might be a thousandth of a second , or a few thousandths of a second or it might be as long as half a second or even a second . and then the nucleus of the atom starts to decay . now it doesn ’ t blow into parts which are just protons and neutrons in one great whoosh ! but instead it starts going down by steps , usually the atomic number changes by two units or one unit depending what sort of particle is ejected from the nucleus . so in the case of 112 , and i don ’ t know the details yet , it will decay . for example , the first step may be going from 112 to 110 then the second step may be just one unit to 109 , and then two down to 107 and so on . until you get to an element below the mass of uranium the mass of 92 - which is stable .
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so copernicium , or copernicium as the discoverers would prefer it to be pronounced , is the latest name to go up on the periodic table and it is really very exciting because it is the first time in as many years that a new name has appeared . and not only has it appeared but quite excitingly , it has appeared with a bit of controversy - what should the symbol be ?
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what was the provisional name of element 112 before iupac accepted the definitive name copernicium ?
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the heisenberg uncertainty principle is one of a handful of ideas from quantum physics to expand into general pop culture . it says that you can never simultaneously know the exact position and the exact speed of an object and shows up as a metaphor in everything from literary criticism to sports commentary . uncertainty is often explained as a result of measurement , that the act of measuring an object 's position changes its speed , or vice versa . the real origin is much deeper and more amazing . the uncertainty principle exists because everything in the universe behaves like both a particle and a wave at the same time . in quantum mechanics , the exact position and exact speed of an object have no meaning . to understand this , we need to think about what it means to behave like a particle or a wave . particles , by definition , exist in a single place at any instant in time . we can represent this by a graph showing the probability of finding the object at a particular place , which looks like a spike , 100 % at one specific position , and zero everywhere else . waves , on the other hand , are disturbances spread out in space , like ripples covering the surface of a pond . we can clearly identify features of the wave pattern as a whole , most importantly , its wavelength , which is the distance between two neighboring peaks , or two neighboring valleys . but we ca n't assign it a single position . it has a good probability of being in lots of different places . wavelength is essential for quantum physics because an object 's wavelength is related to its momentum , mass times velocity . a fast-moving object has lots of momentum , which corresponds to a very short wavelength . a heavy object has lots of momentum even if it 's not moving very fast , which again means a very short wavelength . this is why we do n't notice the wave nature of everyday objects . if you toss a baseball up in the air , its wavelength is a billionth of a trillionth of a trillionth of a meter , far too tiny to ever detect . small things , like atoms or electrons though , can have wavelengths big enough to measure in physics experiments . so , if we have a pure wave , we can measure its wavelength , and thus its momentum , but it has no position . we can know a particles position very well , but it does n't have a wavelength , so we do n't know its momentum . to get a particle with both position and momentum , we need to mix the two pictures to make a graph that has waves , but only in a small area . how can we do this ? by combining waves with different wavelengths , which means giving our quantum object some possibility of having different momenta . when we add two waves , we find that there are places where the peaks line up , making a bigger wave , and other places where the peaks of one fill in the valleys of the other . the result has regions where we see waves separated by regions of nothing at all . if we add a third wave , the regions where the waves cancel out get bigger , a fourth and they get bigger still , with the wavier regions becoming narrower . if we keep adding waves , we can make a wave packet with a clear wavelength in one small region . that 's a quantum object with both wave and particle nature , but to accomplish this , we had to lose certainty about both position and momentum . the positions is n't restricted to a single point . there 's a good probability of finding it within some range of the center of the wave packet , and we made the wave packet by adding lots of waves , which means there 's some probability of finding it with the momentum corresponding to any one of those . both position and momentum are now uncertain , and the uncertainties are connected . if you want to reduce the position uncertainty by making a smaller wave packet , you need to add more waves , which means a bigger momentum uncertainty . if you want to know the momentum better , you need a bigger wave packet , which means a bigger position uncertainty . that 's the heisenberg uncertainty principle , first stated by german physicist werner heisenberg back in 1927 . this uncertainty is n't a matter of measuring well or badly , but an inevitable result of combining particle and wave nature . the uncertainty principle is n't just a practical limit on measurment . it 's a limit on what properties an object can have , built into the fundamental structure of the universe itself .
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it has a good probability of being in lots of different places . wavelength is essential for quantum physics because an object 's wavelength is related to its momentum , mass times velocity . a fast-moving object has lots of momentum , which corresponds to a very short wavelength .
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the wavelength of a quantum object is determined by its :
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which is the hardest word to translate in this sentence ? `` know '' is easy to translate . `` pep rally '' does n't have a direct analog in a lot of languages and cultures , but can be approximated . but the hardest word there is actually one of the smallest : `` you . '' as simple as it seems , it 's often impossible to accurately translate `` you '' without knowing a lot more about the situation where it 's being said . to start with , how familiar are you with the person you 're talking to ? many cultures have different levels of formality . a close friend , someone much older or much younger , a stranger , a boss . these all may be slightly different `` you 's . '' in many languages , the pronoun reflects these differences through what 's known as the t–v distinction . in french , for example , you would say `` tu '' when talking to your friend at school , but `` vous '' when addressing your teacher . even english once had something similar . remember the old-timey `` thou ? '' ironically , it was actually the informal pronoun for people you 're close with , while `` you '' was the formal and polite version . that distinction was lost when the english decided to just be polite all the time . but the difficulty in translating `` you '' does n't end there . in languages like hausa or korana , the `` you '' form depends on the listener 's gender . in many more , it depends on whether they are one or many , such as with german `` du '' or `` ihr . '' even in english , some dialects use words like `` y'all '' or `` youse '' the same way . some plural forms , like the french `` vous '' and russian `` вы '' are also used for a single person to show that the addressee is that much more important , much like the royal `` we . '' and a few languages even have a specific form for addressing exactly two people , like slovenian `` vidva . '' if that was n't complicated enough , formality , number , and gender can all come into play at the same time . in spanish , `` tú '' is unisex informal singular , `` usted '' is unisex formal singular , `` vosotros '' is masculine informal plural , `` vosotras '' is feminine informal plural , and `` ustedes '' is the unisex formal plural . phew ! after all that , it may come as a relief that some languages often leave out the second person pronoun . in languages like romanian and portuguese , the pronoun can be dropped from sentences because it 's clearly implied by the way the verbs are conjugated . and in languages like korean , thai , and chinese , pronouns can be dropped without any grammatical hints . speakers often would rather have the listener guess the pronoun from context than use the wrong one and risk being seen as rude . so if you 're ever working as a translator and come across this sentence without any context : `` you and you , no , not you , you , your job is to translate 'you ' for yourselves '' ... well , good luck . and to the volunteer community who will be translating this video into multiple languages : sorry about that !
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these all may be slightly different `` you 's . '' in many languages , the pronoun reflects these differences through what 's known as the t–v distinction . in french , for example , you would say `` tu '' when talking to your friend at school , but `` vous '' when addressing your teacher .
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what is the t-v distinction ?
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what if william shakespeare had a sister who matched his imagination , his wit , and his way with words ? would she have gone to school and set the stage alight ? in her essay `` a room of one 's own , '' virginia woolf argues that this would have been impossible . she concocts a fictional sister who 's stuck at home , snatching time to scribble a few pages before she finds herself betrothed and runs away . while her brother finds fame and fortune , she remains abandoned and anonymous . in this thought experiment , woolf demonstrates the tragedy of genius restricted , and looks back through time for hints of these hidden histories . she wrote , `` when one reads of a witch being ducked , of a woman possessed by devils , of a wise woman selling herbs , or even a very remarkable man who had a mother , then i think we 're on the track of a lost novelist , a suppressed poet , of some mute and inglorious jane austen . '' `` a room of one 's own '' considers a world denied great works of art due to exclusion and inequality . how best can we understand the internal experience of alienation ? in both her essays and fiction , virginia woolf shapes the slippery nature of subjective experience into words . her characters frequently lead inner lives that are deeply at odds with their external existence . to help make sense of these disparities , the next time you read woolf , here are some aspects of her life and work to consider . she was born adeline virginia stephen in 1882 to a large and wealthy family , which enabled her to pursue a life in the arts . the death of her mother in 1895 was followed by that of her half-sister , father , and brother within the next ten years . these losses led to woolf 's first depressive episode and subsequent institutionalization . as a young woman , she purchased a house in the bloomsbury area of london with her siblings . this brought her into contact with a circle of creatives , including e.m. forster , clive bell , roger fry , and leonard woolf . these friends became known as the bloomsbury group , and virginia and leonard married in 1912 . the members of this group were prominent figures in modernism , a cultural movement that sought to push the boundaries of how reality is represented . key features of modernist writing include the use of stream of consciousness , interior monologue , distortions in time , and multiple or shifting perspectives . these appear in the work of ezra pound , gertrude stein , james joyce , and woolf herself . while reading joyce 's `` ulysses , '' woolf began writing `` mrs . dalloway . '' like `` ulysses , '' the text takes place over the course of a single day and opens under seemingly mundane circumstances . `` mrs. dalloway said she would buy the flowers herself . '' but the novel dives deeply into the characters ' traumatic pasts , weaving the inner world of numbed socialite clarissa dalloway , with that of the shell-shocked veteran septimus warren smith . woolf uses interior monologue to contrast the rich world of the mind against her characters ' external existences . in her novel `` to the lighthouse , '' mundane moments , like a dinner party , or losing a necklace trigger psychological revelations in the lives of the ramsay 's , a fictionalized version of woolf 's family growing up . `` to the lighthouse '' also contains one of the most famous examples of woolf 's radical representation of time . in the time passes section , ten years are distilled into about 20 pages . here , the lack of human presence in the ramsays ' beach house allows woolf to reimagine time in flashes and fragments of prose . `` the house was left . the house was deserted . it was left like a shell on a sand hill to fill with dry salt grains now that life had left it . '' in her novel `` the waves , '' there is little distinction between the narratives of the six main characters . woolf experiments with collective consciousness , at times collapsing the six voices into one . `` it is not one life that i look back upon : i am not one person : i am many people : i do not altogether know who i am , jinny , susan , neville , rhoda or louis , or how to distinguish my life from their 's . '' in `` the waves , '' six become one , but in the gender-bending `` orlando , '' a single character inhabits multiple identities . the protagonist is a poet who switches between genders and lives for 300 years . with its fluid language and approach to identity , `` orlando '' is considered a key text in gender studies . the mind can only fly so far from the body before it returns to the constraints of life . like many of her characters , woolf 's life ended in tragedy when she drowned herself at the age of 59 . yet , she expressed hope beyond suffering . through deep thought , woolf 's characters are shown to temporarily transcend their material reality , and in its careful consideration of the complexity of the mind , her work charts the importance of making our inner lives known to each other .
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would she have gone to school and set the stage alight ? in her essay `` a room of one 's own , '' virginia woolf argues that this would have been impossible . she concocts a fictional sister who 's stuck at home , snatching time to scribble a few pages before she finds herself betrothed and runs away .
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are the arguments put forth in `` a room of one ’ s own '' still relevant today ? are the limitations woolf describes still imposed on female artists ?
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like many heroes of greek myths , the philosopher hippasus was rumored to have been mortally punished by the gods . but what was his crime ? did he murder guests , or disrupt a sacred ritual ? no , hippasus 's transgression was a mathematical proof : the discovery of irrational numbers . hippasus belonged to a group called the pythagorean mathematicians who had a religious reverence for numbers . their dictum of , `` all is number , '' suggested that numbers were the building blocks of the universe and part of this belief was that everything from cosmology and metaphysics to music and morals followed eternal rules describable as ratios of numbers . thus , any number could be written as such a ratio . 5 as 5/1 , 0.5 as 1/2 and so on . even an infinitely extending decimal like this could be expressed exactly as 34/45 . all of these are what we now call rational numbers . but hippasus found one number that violated this harmonious rule , one that was not supposed to exist . the problem began with a simple shape , a square with each side measuring one unit . according to pythagoras theorem , the diagonal length would be square root of two , but try as he might , hippasus could not express this as a ratio of two integers . and instead of giving up , he decided to prove it could n't be done . hippasus began by assuming that the pythagorean worldview was true , that root 2 could be expressed as a ratio of two integers . he labeled these hypothetical integers p and q . assuming the ratio was reduced to its simplest form , p and q could not have any common factors . to prove that root 2 was not rational , hippasus just had to prove that p/q can not exist . so he multiplied both sides of the equation by q and squared both sides . which gave him this equation . multiplying any number by 2 results in an even number , so p^2 had to be even . that could n't be true if p was odd because an odd number times itself is always odd , so p was even as well . thus , p could be expressed as 2a , where a is an integer . substituting this into the equation and simplifying gave q^2 = 2a^2 once again , two times any number produces an even number , so q^2 must have been even , and q must have been even as well , making both p and q even . but if that was true , then they had a common factor of two , which contradicted the initial statement , and that 's how hippasus concluded that no such ratio exists . that 's called a proof by contradiction , and according to the legend , the gods did not appreciate being contradicted . interestingly , even though we ca n't express irrational numbers as ratios of integers , it is possible to precisely plot some of them on the number line . take root 2 . all we need to do is form a right triangle with two sides each measuring one unit . the hypotenuse has a length of root 2 , which can be extended along the line . we can then form another right triangle with a base of that length and a one unit height , and its hypotenuse would equal root three , which can be extended along the line , as well . the key here is that decimals and ratios are only ways to express numbers . root 2 simply is the hypotenuse of a right triangle with sides of a length one . similarly , the famous irrational number pi is always equal to exactly what it represents , the ratio of a circle 's circumference to its diameter . approximations like 22/7 , or 355/113 will never precisely equal pi . we 'll never know what really happened to hippasus , but what we do know is that his discovery revolutionized mathematics . so whatever the myths may say , do n't be afraid to explore the impossible .
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thus , any number could be written as such a ratio . 5 as 5/1 , 0.5 as 1/2 and so on . even an infinitely extending decimal like this could be expressed exactly as 34/45 .
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which of these numbers is/are rational : a ) 3 b ) 12.1 c ) √5
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many elements of traditional japanese culture , such as cuisine and martial arts , are well-known throughout the world . kabuki , a form of classical theater performance , may not be as well understood in the west but has evolved over 400 years to still maintain influence and popularity to this day . the word kabuki is derived from the japanese verb kabuku , meaning out of the ordinary or bizarre . its history began in early 17th century kyoto , where a shrine maiden named izumo no okuni would use the city 's dry kamo riverbed as a stage to perform unusual dances for passerby , who found her daring parodies of buddhist prayers both entertaining and mesmerizing . soon other troops began performing in the same style , and kabuki made history as japan 's first dramatic performance form catering to the common people . by relying on makeup , or keshou , and facial expressions instead of masks and focusing on historical events and everyday life rather than folk tales , kabuki set itself apart from the upper-class dance theater form known as noh and provided a unique commentary on society during the edo period . at first , the dance was practiced only by females and commonly referred to as onna-kabuki . it soon evolved to an ensemble performance and became a regular attraction at tea houses , drawing audiences from all social classes . at this point , onna-kabuki was often risque as geishas performed not only to show off their singing and dancing abilities but also to advertise their bodies to potential clients . a ban by the conservative tokugawa shogunate in 1629 led to the emergence of wakashu-kabuki with young boys as actors . but when this was also banned for similar reasons , there was a transition to yaro-kabuki , performed by men , necessitating elaborate costumes and makeup for those playing female roles , or onnagata . attempts by the government to control kabuki did n't end with bans on the gender or age of performers . the tokugawa military group , or bakufu , was fueled by confucian ideals and often enacted sanctions on costume fabrics , stage weaponry , and the subject matter of the plot . at the same time , kabuki became closely associated with and influenced by bunraku , an elaborate form of puppet theater . due to these influences , the once spontaneous , one-act dance evolved into a structured , five-act play often based on the tenets of confucian philosophy . before 1868 , when the tokugawa shogunate fell and emperor meiji was restored to power , japan had practiced isolation from other countries , or sakoku . and thus , the development of kabuki had mostly been shaped by domestic influences . but even before this period , european artists , such as claude monet , had become interested in and inspired by japanese art , such as woodblock prints , as well as live performance . after 1868 , others such as vincent van gogh and composer claude debussy began to incorporate kabuki influences in their work , while kabuki itself underwent much change and experimentation to adapt to the new modern era . like other traditional art forms , kabuki suffered in popularity in the wake of world war ii . but innovation by artists such as director tetsuji takechi led to a resurgence shortly after . indeed , kabuki was even considered a popular form of entertainment amongst american troops stationed in japan despite initial u.s. censorship of japanese traditions . today , kabuki still lives on as an integral part of japan 's rich cultural heritage , extending its influence beyond the stage to television , film , and anime . the art form pioneered by okuni continues to delight audiences with the actors ' elaborate makeup , extravagant and delicately embroidered costumes , and the unmistakable melodrama of the stories told on stage .
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soon other troops began performing in the same style , and kabuki made history as japan 's first dramatic performance form catering to the common people . by relying on makeup , or keshou , and facial expressions instead of masks and focusing on historical events and everyday life rather than folk tales , kabuki set itself apart from the upper-class dance theater form known as noh and provided a unique commentary on society during the edo period . at first , the dance was practiced only by females and commonly referred to as onna-kabuki .
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one way kabuki differs from the _______ theater is that it relies on heavy makeup , rather than masks .
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picture warm , gooey cookies , crunchy candies , velvety cakes , waffle cones piled high with ice cream . is your mouth watering ? are you craving dessert ? why ? what happens in the brain that makes sugary foods so hard to resist ? sugar is a general term used to describe a class of molecules called carbohydrates , and it 's found in a wide variety of food and drink . just check the labels on sweet products you buy . glucose , fructose , sucrose , maltose , lactose , dextrose , and starch are all forms of sugar . so are high-fructose corn syrup , fruit juice , raw sugar , and honey . and sugar is n't just in candies and desserts , it 's also added to tomato sauce , yogurt , dried fruit , flavored waters , or granola bars . since sugar is everywhere , it 's important to understand how it affects the brain . what happens when sugar hits your tongue ? and does eating a little bit of sugar make you crave more ? you take a bite of cereal . the sugars it contains activate the sweet-taste receptors , part of the taste buds on the tongue . these receptors send a signal up to the brain stem , and from there , it forks off into many areas of the forebrain , one of which is the cerebral cortex . different sections of the cerebral cortex process different tastes : bitter , salty , umami , and , in our case , sweet . from here , the signal activates the brain 's reward system . this reward system is a series of electrical and chemical pathways across several different regions of the brain . it 's a complicated network , but it helps answer a single , subconscious question : should i do that again ? that warm , fuzzy feeling you get when you taste grandma 's chocolate cake ? that 's your reward system saying , `` mmm , yes ! '' and it 's not just activated by food . socializing , sexual behavior , and drugs are just a few examples of things and experiences that also activate the reward system . but overactivating this reward system kickstarts a series of unfortunate events : loss of control , craving , and increased tolerance to sugar . let 's get back to our bite of cereal . it travels down into your stomach and eventually into your gut . and guess what ? there are sugar receptors here , too . they are not taste buds , but they do send signals telling your brain that you 're full or that your body should produce more insulin to deal with the extra sugar you 're eating . the major currency of our reward system is dopamine , an important chemical or neurotransmitter . there are many dopamine receptors in the forebrain , but they 're not evenly distributed . certain areas contain dense clusters of receptors , and these dopamine hot spots are a part of our reward system . drugs like alcohol , nicotine , or heroin send dopamine into overdrive , leading some people to constantly seek that high , in other words , to be addicted . sugar also causes dopamine to be released , though not as violently as drugs . and sugar is rare among dopamine-inducing foods . broccoli , for example , has no effect , which probably explains why it 's so hard to get kids to eat their veggies . speaking of healthy foods , let 's say you 're hungry and decide to eat a balanced meal . you do , and dopamine levels spike in the reward system hot spots . but if you eat that same dish many days in a row , dopamine levels will spike less and less , eventually leveling out . that 's because when it comes to food , the brain evolved to pay special attention to new or different tastes . why ? two reasons : first , to detect food that 's gone bad . and second , because the more variety we have in our diet , the more likely we are to get all the nutrients we need . to keep that variety up , we need to be able to recognize a new food , and more importantly , we need to want to keep eating new foods . and that 's why the dopamine levels off when a food becomes boring . now , back to that meal . what happens if in place of the healthy , balanced dish , you eat sugar-rich food instead ? if you rarely eat sugar or do n't eat much at a time , the effect is similar to that of the balanced meal . but if you eat too much , the dopamine response does not level out . in other words , eating lots of sugar will continue to feel rewarding . in this way , sugar behaves a little bit like a drug . it 's one reason people seem to be hooked on sugary foods . so , think back to all those different kinds of sugar . each one is unique , but every time any sugar is consumed , it kickstarts a domino effect in the brain that sparks a rewarding feeling . too much , too often , and things can go into overdrive . so , yes , overconsumption of sugar can have addictive effects on the brain , but a wedge of cake once in a while wo n't hurt you .
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different sections of the cerebral cortex process different tastes : bitter , salty , umami , and , in our case , sweet . from here , the signal activates the brain 's reward system . this reward system is a series of electrical and chemical pathways across several different regions of the brain .
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sugar consumption causes distinct changes to the brain ’ s reward system . what other stimuli activate this system and what are similar behaviors seen between them and sugar overconsumption ?
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in the early hours of august 13 , 1961 , east german construction workers flanked by soldiers and police began tearing up streets and erecting barriers throughout the city of berlin and its surroundings . this night marked the beginning of one of history 's most infamous dividing lines , the berlin wall . construction on the wall continued for the next decade as it cut through neighborhoods , separated families , and divided not just germany , but the world . to understand how we got to this point , we have to go back to world war ii . america , britain , and france joined forces with the soviet union against the axis powers . after they defeated nazi germany , each of the victorious nations occupied part of the country . the division was meant to be temporary , but the former allies found themselves at odds over their visions for post-war europe . while western powers promoted liberal market economies , the soviet union sought to surround itself with obedient communist nations , including a weakened germany . as their relations deteriorated , the federal republic of germany was formed in the west while the soviets established the german democratic republic in the east . the soviet satellite countries restricted western trade and movement , so a virtually impassable border formed . it became known as the iron curtain . in the former german capital of berlin , things were particularly complicated . although the city lay fully within the east german territory of the gdr , the post-war agreement gave the allies joint administration . so america , britain , and france created a democratic enclave in berlin 's western districts . while east germans were officially banned from leaving the country , in berlin , it was simply a matter of walking , or riding a subway , streetcar or bus , to the western half , then traveling on to west germany or beyond . this open border posed a problem for the east german leadership . they had staked a claim to represent the communist resistance against hitler and portrayed western germany as a continuation of the nazi regime . while the u.s. and its allies poured money into west germany 's reconstruction , the soviet union extracted resources from the east as war reparations , making its planned economy even less competitive . life in east germany passed under the watchful eye of the stasi , the secret police whose wiretaps and informants monitored citizens for any hint of disloyalty . while there was free health care and education in the east , the west boasted higher salaries , more consumer goods , and greater personal freedom . by 1961 , about 3.5 million people , nearly 20 % of the east german population , had left , including many young professionals . to prevent further losses , east germany decided to close the border , and that 's where the berlin wall came in . extending for 43 kilometers through berlin , and a further 112 through east germany , the initial barrier consisted of barbed wire and mesh fencing . some berliners escaped by jumping over the wire or leaving from windows , but as the wall expanded , this became more difficult . by 1965 , 106 kilometers of 3.6-meter-high concrete barricades had been added topped with a smooth pipe to prevent climbing . over the coming years , the barrier was strengthened with spike strips , guard dogs , and even landmines , along with 302 watchtowers and 20 bunkers . a parallel fence in the rear set off a 100-meter area called the death strip . there , all buildings were demolished and the ground covered with sand to provide a clear line of sight for the hundreds of guards ordered to shoot anyone attempting to cross . nevertheless , nearly 5,000 people in total managed to flee east germany between 1961 and 1989 . some were diplomats or athletes who defected while abroad , but others were ordinary citizens who dug tunnels , swam across canals , flew hot air balloons , or even crashed a stolen tank through the wall . yet the risk was great . over 138 people died while attempting escape . some shot in full view of west germans powerless to help them . the wall stabilized east germany 's economy by preventing its work force from leaving , but tarnished its reputation , becoming a global symbol of communist repression . as part of reconciliation with the east , the basic treaty of 1972 recognized east germany pragmatically while west germany retained its hope for eventual reunification . although the eastern regime gradually allowed family visits , it tried to discourage people from exercising these rights with an arduous bureaucratic process and high fees . nonetheless , it was still overwhelmed by applications . by the end of the 1980 's , the liberalization of other eastern bloc regimes caused mass demonstrations for free travel and demands for democracy . on the evening of november 9 , 1989 , east germany tried to defuse tension by making travel permits easier to obtain . but the announcement brought thousands of east berliners to the border crossing points in the wall , forcing the surprised guards to open the gates immediately . rejoicing crowds poured into west berlin as people from both sides danced atop the wall . and others began to demolish it with whatever tools they could find . although the border guards initially tried to maintain order , it was soon clear that the years of division were at an end . after four decades , germany was officially reunified in october 1990 . and the soviet union fell soon after . today , parts of the wall still stand as a reminder that any barriers we put up to impede freedom , we can also break down .
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but the announcement brought thousands of east berliners to the border crossing points in the wall , forcing the surprised guards to open the gates immediately . rejoicing crowds poured into west berlin as people from both sides danced atop the wall . and others began to demolish it with whatever tools they could find .
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the berlin wall :
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what do euclid , twelve-year-old einstein , and american president james garfield have in common ? they all came up with elegant proofs for the famous pythagorean theorem , the rule that says for a right triangle , the square of one side plus the square of the other side is equal to the square of the hypotenuse . in other words , a²+b²=c² . this statement is one of the most fundamental rules of geometry , and the basis for practical applications , like constructing stable buildings and triangulating gps coordinates . the theorem is named for pythagoras , a greek philosopher and mathematician in the 6th century b.c. , but it was known more than a thousand years earlier . a babylonian tablet from around 1800 b.c . lists 15 sets of numbers that satisfy the theorem . some historians speculate that ancient egyptian surveyors used one such set of numbers , 3 , 4 , 5 , to make square corners . the theory is that surveyors could stretch a knotted rope with twelve equal segments to form a triangle with sides of length 3 , 4 and 5 . according to the converse of the pythagorean theorem , that has to make a right triangle , and , therefore , a square corner . and the earliest known indian mathematical texts written between 800 and 600 b.c . state that a rope stretched across the diagonal of a square produces a square twice as large as the original one . that relationship can be derived from the pythagorean theorem . but how do we know that the theorem is true for every right triangle on a flat surface , not just the ones these mathematicians and surveyors knew about ? because we can prove it . proofs use existing mathematical rules and logic to demonstrate that a theorem must hold true all the time . one classic proof often attributed to pythagoras himself uses a strategy called proof by rearrangement . take four identical right triangles with side lengths a and b and hypotenuse length c. arrange them so that their hypotenuses form a tilted square . the area of that square is c² . now rearrange the triangles into two rectangles , leaving smaller squares on either side . the areas of those squares are a² and b² . here 's the key . the total area of the figure did n't change , and the areas of the triangles did n't change . so the empty space in one , c² must be equal to the empty space in the other , a² + b² . another proof comes from a fellow greek mathematician euclid and was also stumbled upon almost 2,000 years later by twelve-year-old einstein . this proof divides one right triangle into two others and uses the principle that if the corresponding angles of two triangles are the same , the ratio of their sides is the same , too . so for these three similar triangles , you can write these expressions for their sides . next , rearrange the terms . and finally , add the two equations together and simplify to get ab²+ac²=bc² , or a²+b²=c² . here 's one that uses tessellation , a repeating geometric pattern for a more visual proof . can you see how it works ? pause the video if you 'd like some time to think about it . here 's the answer . the dark gray square is a² and the light gray one is b² . the one outlined in blue is c² . each blue outlined square contains the pieces of exactly one dark and one light gray square , proving the pythagorean theorem again . and if you 'd really like to convince yourself , you could build a turntable with three square boxes of equal depth connected to each other around a right triangle . if you fill the largest square with water and spin the turntable , the water from the large square will perfectly fill the two smaller ones . the pythagorean theorem has more than 350 proofs , and counting , ranging from brilliant to obscure . can you add your own to the mix ?
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state that a rope stretched across the diagonal of a square produces a square twice as large as the original one . that relationship can be derived from the pythagorean theorem . but how do we know that the theorem is true for every right triangle on a flat surface , not just the ones these mathematicians and surveyors knew about ?
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what are some practical applications of the pythagorean theorem that impact our modern society ?
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here 's a conundrum : identical twins originate from the same dna , so how can they turn out so different even in traits that have a significant genetic component ? for instance , why might one twin get heart disease at 55 , while her sister runs marathons in perfect health ? nature versus nurture has a lot to do with it , but a deeper related answer can be found within something called epigenetics . that 's the study of how dna interacts with the multitude of smaller molecules found within cells , which can activate and deactivate genes . if you think of dna as a recipe book , those molecules are largely what determine what gets cooked when . they are n't making any conscious choices themselves , rather their presence and concentration within cells makes the difference . so how does that work ? genes in dna are expressed when they 're read and transcribed into rna , which is translated into proteins by structures called ribosomes . and proteins are much of what determines a cell 's characteristics and function . epigenetic changes can boost or interfere with the transcription of specific genes . the most common way interference happens is that dna , or the proteins it 's wrapped around , gets labeled with small chemical tags . the set of all of the chemical tags that are attached to the genome of a given cell is called the epigenome . some of these , like a methyl group , inhibit gene expression by derailing the cellular transcription machinery or causing the dna to coil more tightly , making it inaccessible . the gene is still there , but it 's silent . boosting transcription is essentially the opposite . some chemical tags will unwind the dna , making it easier to transcribe , which ramps up production of the associated protein . epigenetic changes can survive cell division , which means they could affect an organism for its entire life . sometimes that 's a good thing . epigenetic changes are part of normal development . the cells in an embryo start with one master genome . as the cells divide , some genes are activated and others inhibited . over time , through this epigenetic reprogramming , some cells develop into heart cells , and others into liver cells . each of the approximately 200 cell types in your body has essentially the same genome but its own distinct epigenome . the epigenome also mediates a lifelong dialogue between genes and the environment . the chemical tags that turn genes on and off can be influenced by factors including diet , chemical exposure , and medication . the resulting epigenetic changes can eventually lead to disease , if , for example , they turn off a gene that makes a tumor-suppressing protein . environmentally-induced epigenetic changes are part of the reason why genetically identical twins can grow up to have very different lives . as twins get older , their epigenomes diverge , affecting the way they age and their susceptibility to disease . even social experiences can cause epigenetic changes . in one famous experiment , when mother rats were n't attentive enough to their pups , genes in the babies that helped them manage stress were methylated and turned off . and it might not stop with that generation . most epigenetic marks are erased when egg and sperm cells are formed . but now researchers think that some of those imprints survive , passing those epigenetic traits on to the next generation . your mother 's or your father 's experiences as a child , or choices as adults , could actually shape your own epigenome . but even though epigenetic changes are sticky , they 're not necessarily permanent . a balanced lifestyle that includes a healthy diet , exercise , and avoiding exposure to contaminants may in the long run create a healthy epigenome . it 's an exciting time to be studying this . scientists are just beginning to understand how epigenetics could explain mechanisms of human development and aging , as well as the origins of cancer , heart disease , mental illness , addiction , and many other conditions . meanwhile , new genome editing techniques are making it much easier to identify which epigenetic changes really matter for health and disease . once we understand how our epigenome influences us , we might be able to influence it , too .
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over time , through this epigenetic reprogramming , some cells develop into heart cells , and others into liver cells . each of the approximately 200 cell types in your body has essentially the same genome but its own distinct epigenome . the epigenome also mediates a lifelong dialogue between genes and the environment . the chemical tags that turn genes on and off can be influenced by factors including diet , chemical exposure , and medication .
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the epigenome is :
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many of us have hundreds of things on our minds at any moment , often struggling to keep track of everything we need to do . but fortunately , there 's one important thing we do n't have to worry about remembering : breathing . when you breathe , you transport oxygen to the body 's cells to keep them working and clear your system of the carbon dioxide that this work generates . breathing , in other words , keeps the body alive . so , how do we accomplish this crucial and complex task without even thinking about it ? the answer lies in our body 's respiratory system . like any machinery , it consists of specialized components , and requires a trigger to start functioning . here , the components are the structures and tissues making up the lungs , as well as the various other respiratory organs connected to them . and to get this machine moving , we need the autonomic nervous system , our brain 's unconscious control center for the vital functions . as the body prepares to take in oxygen-rich air , this system sends a signal to the muscles around your lungs , flattening the diaphragm and contracting the intercostal muscles between your ribs to create more space for the lungs to expand . air then wooshes into your nose and mouth , through your trachea , and into the bronchi that split at the trachea 's base , with one entering each lung . like tree branches , these small tubes divide into thousands of tinier passages called bronchioles . it 's tempting to think of the lungs as huge balloons , but instead of being hollow , they 're actually spongy inside , with the bronchioles running throughout the parenchyma tissue . at the end of each bronchiole is a little air sack called an alveolus , wrapped in capillaries full of red blood cells containing special proteins called hemoglobin . the air you 've breathed in fills these sacks , causing the lungs to inflate . here is where the vital exchange occurs . at this point , the capillaries are packed with carbon dioxide , and the air sacks are full of oxygen . but due to the basic process of diffusion , the molecules of each gas want to move to a place where there 's a lower concentration of their kind . so as oxygen crosses over to the capillaries , the hemoglobin grabs it up , while the carbon dioxide is unloaded into the lungs . the oxygen-rich hemoglobin is then transported throughout the body via the bloodstream . but what do our lungs do with all that carbon dioxide ? exhale it , of course . the autonomic nervous system kicks in again , causing the diaphragm to ball up , and the intercostal muscles to relax , making the chest cavities smaller and forcing the lungs to compress . the carbon dioxide-rich air is expelled , and the cycle begins again . so that 's how these spongy organs keep our bodies efficiently supplied with air . lungs inhale and exhale between 15 and 25 times a minute , which amounts to an incredible 10,000 liters of air each day . that 's a lot of work , but do n't sweat it . your lungs and your autonomic nervous system have got it covered .
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but fortunately , there 's one important thing we do n't have to worry about remembering : breathing . when you breathe , you transport oxygen to the body 's cells to keep them working and clear your system of the carbon dioxide that this work generates . breathing , in other words , keeps the body alive .
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why do you think the body 's cells need oxygen ?
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translator : tom carter reviewer : bedirhan cinar why are gas stations always built right next to other gas stations ? why can i drive for a mile without finding a coffee shop and then stumble across three on the same corner ? why do grocery stores , auto repair shops and restaurants always seem to exist in groups instead of being spread evenly throughout a community ? while there are several factors that might go into deciding where to place your business , clusters of similar companies can be explained by a very simple story called hotelling 's model of spatial competition . imagine that you sell ice cream at the beach . your beach is one mile long and you have no competition . where would you place your cart in order to sell the most product ? in the middle . the one-half-mile walk may be too far for some people at each end of the beach , but your cart serves as many people as possible . one day you show up at work just as your cousin teddy is arriving at the beach with his own ice cream cart . in fact , he 's selling exactly the same type of ice cream as you are . you agree that you will split the beach in half . in order to ensure that customers do n't have to walk too far you set up your cart a quarter mile south of the beach center , right in the middle of your territory . teddy sets up a quarter mile north of the center , in the middle of teddy territory . with this agreement , everyone south of you buys ice cream from you . everyone north of teddy buys from him , and the 50 % of beachgoers in between walk to the closest cart . no one walks more than a quarter of a mile , and both vendors sell to half of the beachgoers . game theorists consider this a socially optimal solution . it minimizes the maximum number of steps any visitor must take in order to reach an ice cream cart . the next day , when you arrive at work , teddy has set up his cart in the middle of the beach . you return to your location a quarter mile south of center and get the 25 % of customers to the south of you . teddy still gets all of the customers north in teddy territory , but now you split the 25 % of people in between the two carts . day three of the ice cream wars , you get to the beach early , and set up right in the center of teddy territory , assuming you 'll serve the 75 % of beachgoers to your south , leaving your cousin to sell to the 25 % of customers to the north . when teddy arrives , he sets up just south of you stealing all of the southerly customers , and leaving you with a small group of people to the north . not to be outdone , you move 10 paces south of teddy to regain your customers . when you take a mid-day break , teddy shuffles 10 paces south of you , and again , steals back all the customers to the far end of the beach . throughout the course of the day , both of you continue to periodically move south towards the bulk of the ice cream buyers , until both of you eventually end up at the center of the beach , back to back , each serving 50 % of the ice-cream-hungry beachgoers . at this point , you and your competitive cousin have reached what game theorists call a nash equilibrium - the point where neither of you can improve your position by deviating from your current strategy . your original strategy , where you were each a quarter mile from the middle of the beach , did n't last , because it was n't a nash equilibrium . either of you could move your cart towards the other to sell more ice cream . with both of you now in the center of the beach , you ca n't reposition your cart closer to your furthest customers without making your current customers worse off . however , you no longer have a socially optimal solution , since customers at either end of the beach have to walk further than necessary to get a sweet treat . think about all the fast food chains , clothing boutiques , or mobile phone kiosks at the mall . customers may be better served by distributing services throughout a community , but this leaves businesses vulnerable to aggressive competition . in the real world , customers come from more than one direction , and businesses are free to compete with marketing strategies , by differentiating their product line , and with price cuts , but at the heart of their strategy , companies like to keep their competition as close as possible .
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however , you no longer have a socially optimal solution , since customers at either end of the beach have to walk further than necessary to get a sweet treat . think about all the fast food chains , clothing boutiques , or mobile phone kiosks at the mall . customers may be better served by distributing services throughout a community , but this leaves businesses vulnerable to aggressive competition . in the real world , customers come from more than one direction , and businesses are free to compete with marketing strategies , by differentiating their product line , and with price cuts , but at the heart of their strategy , companies like to keep their competition as close as possible .
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think about your own community . draw a map that indicates each retail location and its type . are similar types together ? are there any outliers ? what are the most popular spots and are they surrounded by similar businesses ?
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vsauce , i ’ m jake and thank you for visiting because i have been stuck in this chair for weeks . why you ask ? let me tell you ! it is because of this ! what is that ? well my dear friend , as you may know i have cancer and to try and stop it from spreading , they removed a lot of flesh , muscle , tissue and bone and replaced it with something else…and that got me thinking , about what makes you you . which then in turn got me thinking about paradoxes . specifically logical paradoxes or thought experiments . ya know there is one in particular that pertains to the removal and replacement of certain things…let 's go outside quick little side note : i also figured out teleportation but we ’ ll discuss that later…ya know you should come out here too . so we can discuss the ship of theseus ! the ship of theseus is pretty straightforward as far as logical paradoxes go . let 's say we have a ship , and it 's a very nice ship . but after a while we end up replacing all the wood and then a while later we replace the sails , then a while later we replace the hooks . is it still the same ship ? or is it a new ship ? a different ship ? let ’ s go a step further . let ’ s say we kept all the pieces of this ship that we replaced and used them to make another ship ... an identical one . is this one the original or is this one ? or are they both not original ? what makes something truly original ? i need some sand . here i have what i would consider a heap of sand which leads us into our next logical paradox . the sorites paradox . sorites in ancient greek meaning heap . so , we have our heap , right ? but what happens if we take away a grain of sand ? well , it 's still a heap . but then we take away another grain… still a heap . but then we take another , and another , until we get this . is this a heap ? what about this ? or this ? if we remove a grain until only one is left…is this still a heap ? at what point do we no longer consider it a heap ? let ’ s reverse it . we start with a single grain of sand . obviously not what we would call a heap . but then we add a grain and another , and another . when does it become a heap of sand ? ya know , instead of using objects as our examples , let ’ s discuss a paradox that instead , uses words . we interact with words every day but today we are going to focus on just two words , autological and heterological , these are essential for the grelling-nelson paradox . an autological word is a word that describes itself . for example : pronounceable is pronounceable , polysyllabic is polysyllabic , and a noun is a noun . then there is heterological where a word does not describe itself . for example : purple is not purple , triangle is not a triangle and hyphenated is not hyphenated . the paradox comes into play when we ask the question : is the word “ heterological ” heterological ? if you say no , then heteorological does not describe itself . and if it ’ s not heterological then it must be autological and describe itself . but if it is autological then heterological describes itself and therefor heterological is heterological . paradox . if you say yes , heterological does not describe itself then that means heterological is not heterological . paradox . let ’ s try something . let ’ s combine aspects of the ship of theseus and the sorites paradox and apply it to ourselves . even though part of my leg was replaced i am still me , right ? if my entire leg were removed , i ’ d still be me . so at what point am i no longer myself ? how much would have to be removed for you to no longer be you ? or is what makes us us our memories of who we are and of who we were ? for example , you are different than when you were a baby . obviously you are taller , a little bit heavier , you have different hair , different teeth , and all of your cells have been replaced since birth . i mean your personality has changed . your opinions have changed…so how are you the same person ? ya know ... maybe we should lay off the teleportation for a little not just because of that but also because i 've been thinking of something ... the teletransportation paradox . let ’ s say we have a machine that can teleport you from here to there . in order to transmit you though , the machine kills you and instantly breaks you down into all the atoms that once made you up . it then transmits all the data of what you were to another machine in a different location which remakes you . putting different atoms in the right spot . so the question is , is the person who went into the machine the same person coming out of the other machine ? you have the same memories , the same thoughts , but everything that physically makes you is different . you ’ d remember everything up to being teleported and reemerging on the other side - everything in between would be lost . so , is it your identity , your emotions , feelings and is it your thoughts that make you you ? ya know , you should come a little bit closer . when you wake up in the morning , how do you know that you ’ re the same person as who went to sleep ? how do i know that when i close my eyes , is the same jake opening them ? maybe every time we open our eyes we are being created again and again from the idea of who we are…from our sense of identity . and , as always , thanks for watching .
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but if it is autological then heterological describes itself and therefor heterological is heterological . paradox . if you say yes , heterological does not describe itself then that means heterological is not heterological .
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what question does the ship of theseus paradox seek to address ?
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some people ca n't see the forest for the trees , but before stephen sillett , no one could see or even imagine the forest in the trees . stephen was an explorer of new worlds from the start . he spent his boyhood in harrisburg , pennsylvania reading tolkien and playing dungeons and dragons with his brother scott . but when the sillett family visited their grandparent 's cabin near gettysburg , their grandmother helen poe sillett , would take the boys into the nearby mountains and forests to bird-watch . they called grandma sillett poe , and she taught the boys to identify songbirds , plants and even lichens , creatures that often look like splotches of carpet glued to the shady sides of rocks and tree trunks . looking upwards , both boys found their callings . scott became a research scientist specializing in migratory birds . stephen was more interested in the trees . the tangle of branches and leaves attracted his curiosity . what could be hidden up there ? by the time stephen was in college , that curiosity pulled him skyward to the tallest trees on earth : the ancient coast redwoods of northern california . rising from trunks up to 20 feet in diameter , redwoods can grow up to 380 feet , or 38 stories , over a 2,000 year lifetime . but no one had thought to investigate the crowns of these natural skyscrapers . were there more than just branches up there ? stephen decided to find out firsthand . in 1987 , stephen , his brother scott and his friend marwood drove from reed college in oregon to prairie creek redwoods state park in northern california . deep inside the park , stephen picked the tallest redwood he could find . its lowest branches were almost 100 feet up , far beyond his reach . but he saw a younger , shorter redwood growing next to the target tree . with a running start , he leapt and grabbed the lowest branch , pulled himself up and scurried upwards . he was free climbing without ropes or a harness , one misstep meant death . but up he went , and when he reached the peak , he swayed and leapt across the gap of space onto a branch of the target tree and into a world never seen before . his buddy marwood followed him up , and the two young men free climbed high into the redwood 's crown . stephen came across lichens like grandma poe had shown him as a boy . he noticed that the higher he went , the thicker the branches were , not the case with most trees . he found moist mats of soil many inches thick , made from fallen needles , bark , other plant debris and dust from the sky piled on the tops of the large branches . he even found reiterations : new redwood tree trunks growing out from the main trunk . the redwood had cloned itself . when stephen reached the pinnacle , he rested on a platform of crisscrossing branches and needles . growing in the soil mat was a huckleberry bush with ripe berries ! he ate some and waited for his friend . stephen had discovered a new world hundreds of feet above the ground . his climb led to more excursions , with safety equipment , thank goodness , up other ancient redwoods as he mapped and measured the architecture of branches and additional trunks in the canopy of an entire grove . stephen became an expert in the ecology of the tallest trees on earth and the rich diversity of life in their crowns , aerial ecosystems no one had imagined . there are ferns , fungi and epiphytic trees normally found at ground level like douglas firs , hemlocks and tan oaks whose roots had taken hold in the rich wet soil mats . invertebrates such as ants , bumblebees , mites , beetles , earthworms and aquatic crustacean copepods make their homes alongside flowering plants like rhododendrons , currant and elderberry bushes . ospreys , spotted owls , and jays search the canopy for food . even the marbled murrelet , a pacific seabird , flies many miles from the ocean to nest there . squirrels and voles peek out of penthouse burrows . and the top predator ? the mighty wandering salamander ! sillett 's research has changed how we think about tall trees , and bolstered the case for their conservation , not just as impressive individual organisms but as homes to countless other species . so when you look up into the branches and leaves of a tree , ask , `` what else is up there ? '' a new world might be just out of reach . so leap for it .
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what could be hidden up there ? by the time stephen was in college , that curiosity pulled him skyward to the tallest trees on earth : the ancient coast redwoods of northern california . rising from trunks up to 20 feet in diameter , redwoods can grow up to 380 feet , or 38 stories , over a 2,000 year lifetime . but no one had thought to investigate the crowns of these natural skyscrapers .
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ancient coast redwoods can grow up to ______ feet and live for ______ years .
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would you like to know what 's in our future ? what 's going to happen tomorrow , next year , or even a millennium from now ? well , you 're not alone . everyone from governments to militaries to industry leaders do , as well , and they all employ people called futurists who attempt to forecast the future . some are able to do this with surprising accuracy . in the middle of the 20th century , a think tank known as the rand corporation consulted dozens of scientists and futurists who together forecast many of the technologies we take for granted today , including artificial organs , the use of birth control pills , and libraries able to look up research material for the reader . one way futurists arrive at their predictions is by analyzing movements and trends in society , and charting the paths they are likely to follow into the future with varying degrees of probability . their work informs the decisions of policymakers and world leaders , enabling them to weigh options for the future that otherwise could not have been imagined in such depth or detail . of course , there are obvious limits to how certain anyone can be about the future . there are always unimaginable discoveries that arise which would make no sense to anyone in the present . imagine , for example , transporting a physicist from the middle of the 19th century into the 21st . you explain to him that a strange material exists , uranium 235 , that of its own accord can produce enough energy to power an entire city , or destroy it one fell swoop . `` how can such energy come from nowhere ? '' he would demand to know . `` that 's not science , that 's magic . '' and for all intents and purposes , he would be right . his 19th century grasp of science includes no knowledge of radioactivity or nuclear physics . in his day , no forecast of the future could have predicted x-rays , or the atom bomb , let alone the theory of relativity or quantum mechanics . as arthur c. clarke has said , `` any sufficiently advanced technology is indistinguishable from magic . '' how can we prepare , then , for a future that will be as magical to us as our present would appear to someone from the 19th century ? we may think our modern technology and advanced data analysis techniques might allow us to predict the future with much more accuracy than our 19th century counterpart , and rightly so . however , it 's also true that our technological progress has brought with it new increasingly complex and unpredictable challenges . the stakes for future generations to be able to imagine the unimaginable are higher than ever before . so the question remains : how do we do that ? one promising answer has actually been with us since the 19th century and the industrial revolution that laid the foundation for our modern world . during this time of explosive development and invention , a new form of literature , science fiction , also emerged . inspired by the innovations of the day , jules verne , h.g . wells , and other prolific thinkers explored fantastic scenarios , depicting new frontiers of human endeavor . and throughout the 20th century and into the 21st , storytellers have continued to share their visions of the future and correctly predicted many aspects of the world we inhabit decades later . in `` brave new world , '' aldous huxley foretold the use of antidepressants in 1932 , long before such medication became popular . in 1953 , ray bradbury 's `` fahrenheit 451 , '' forecast earbuds , `` thimble radios , '' in his words . and in `` 2001 : a space odyssey , '' arthur c. clarke described a portable , flat-screen news pad in 1968 . in works that often combine entertainment and social commentary , we are invited to suspend our disbelief and consider the consequences of radical shifts in familiar and deeply engrained institutions . in this sense , the best science fiction fulfills the words of philosopher michel foucault , `` i 'm no prophet . my job is making windows where there were once walls . '' free from the constraints of the present and our assumptions of what 's impossible , science fiction serves as a useful tool for thinking outside of the box . many futurists recognize this , and some are beginning to employ science fictions writers in their teams . just recently , a project called iknow proposed scenarios that look much like science fiction stories . they include the discovery of an alien civilization , development of a way for humans and animals to communicate flawlessly , and radical life extension . so , what does the future hold ? of course , we ca n't know for certain , but science fiction shows us many possibilities . ultimately , it is our responsibility to determine which we will work towards making a reality .
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free from the constraints of the present and our assumptions of what 's impossible , science fiction serves as a useful tool for thinking outside of the box . many futurists recognize this , and some are beginning to employ science fictions writers in their teams . just recently , a project called iknow proposed scenarios that look much like science fiction stories . they include the discovery of an alien civilization , development of a way for humans and animals to communicate flawlessly , and radical life extension .
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do you think that science fiction writers should take part in governmental and international relations discussions ? should politicians consult science fiction writers ?
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so this is manganese metal . you know , very often in chemistry we use manganese in the form of permanganate as an oxidizing agent but this is manganese metal . manganese is right in the middle of the row of transition metals and it has 5 electrons , which can give it a really very rich chemistry . so here you can see it is a brand new sample although the bottle looks very , very old , it is 100grams . so i am going to pour a small amount of manganese out , so that we can have a closer look . one of the main uses of manganese at the moment is as a catalyst for making the plastic which you find in plastic water bottles . you can see my big display of water bottles up there . and manganese is a key catalyst in the reaction between xylene , which is the raw material which you get from crude oil to make terephthalic acid which is one of the components in this plastic . and the reason it is important is that manganese can add and lose electrons which help in the reaction between xylene and oxygen . there is some paper on the top . manganese is also important in old batteries , the older batteries that you used in torches , the sort that leaked , contained manganese dioxide . so here we have the manganese and we are going to pour a small amount out so that we can have a look at this element . and you can see how the colour refracts off the top , really a quite lovely sample of the manganese metal itself . so we are looking at manganese crystals growing from the surface because this material would have been made from a high temperature , crystal growing-type process . so you can see the manganese is growing and seeding new crystallites of the surface - seeding off in every direction . it ’ s cool .
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there is some paper on the top . manganese is also important in old batteries , the older batteries that you used in torches , the sort that leaked , contained manganese dioxide . so here we have the manganese and we are going to pour a small amount out so that we can have a look at this element .
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what is the manganese compound used as the cathode ( electron acceptor ) in alkaline batteries ?
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[ go project films ] [ when a town runs dry ] [ ♪ music ♪ ] my grandfather started the farm . and we 've been farming here ever since . for the last couple years , we have n't had the crop production that we 're used to when we have adequate water . we 're struggling . i 've had to sell some property to try to keep in business . the little bit of land that we did sell was a very emotional thing to do because that 's land that i worked with my dad and it 's gone . growing up in stratford was a wonderful thing as a child . [ children talking ] the canals were always filled with water . we could spend a whole day at the canal trying to catch crawdads , hunting for frogs , fishing . we 'd ride our bikes off into the river . and we would swim in it . nowadays , there 's no water there . i grew up in yemen . living over there was really hard . so that is why we came to the united states . first we moved to oakland but i did n't feel like home there . i wanted to move to a smaller city . that 's when i found stratford . i really like living here but sometimes it gets hard with the work . since the drought has started we lost half the business . most of the people that come to my store they work for the farmers . most of the farmers they get broke , the workers they go somewhere else to find work . i really feel bad about the people . they have a rough time . this makes me sad because we were welcomed by all the people here . being able to work with the ground and with nature has been very satisfying . but of late when the water has become scarce we do n't get a lot of help from the people who want the food that we grow . this year probably two-thirds to half of our farm has not been put into cultivation because of lack of water . without food production , there 's no jobs out in the rural communities . when you have the commodity we tend to not plan for the future . otherwise we should have been planning years ago . you do n't start thinking about reality until you start seeing the writing on the wall . water is one thing , but you take a step back and you look at what 's going on in the community , and it 's heartbreaking . you 've got to be grateful for the people that are there from dusk to dawn or even later than that . when those stores close their doors , we 're really going to be hurting in that little community . you know , where are our kids going to be able to go to go get a snack ? when people do n't have the money i start to run a tab with them . some people they pay me back , some people they ca n't because no work . okay kenny , thank you . - you have a good day . - we 'll see you next time . when you know the people when they ca n't make no money , no work , it 's hard to say `` you know '' pay me my money back and you know they do n't have it . we lost a lot . sometimes you think i do n't know what to do anymore and we just keep going . anything helps , you know , anything helps . any time someone puts a little bit more effort into the community , [ whistle ] the community stands stronger . and you just hope that it grasps and it keeps moving forward . i would like my kids to take over the farm and keep it going but if it continues to deteriorate then the future is not bright in agriculture . [ cheering ] the only thing we can do is sell more land and that 's like selling part of yourself . [ screams ] there 's no better life . it 's not fast . there 's not a lot of money in it , but it 's a fair living . so it would really be sad for me to see this lifestyle come to an end . i hope the water is coming back . when the rain comes back i hope a lot of work and a lot of people come back . i really like living in this town . i do n't want to leave this town . [ credits ] [ ©2016 go project films ]
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[ go project films ] [ when a town runs dry ] [ ♪ music ♪ ] my grandfather started the farm . and we 've been farming here ever since .
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describe the occupations of the three main characters in the film .
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ok , so thulium is a very expensive lanthanide . it ’ s very expensive because it ’ s very hard to separate it from its neighbours . the lanthanides from the left to right undergo this contraction where they get smaller and smaller and over on the right-hand-side at this point that they are all of a very similar size . now we can separate them now but it is quite difficult to do and therefore quite expensive , so thulium is not used very often . however thulium , as well as being able to obtain the plus-3 oxidation state , it is also one of those ones which can obtain the plus-2 oxidation state , which means that chemists are now beginning to find uses for it which they hadn ’ t expected before . so you may see the use of thulium increase in years to come . because it ’ s very hard to isolate because it ’ s of a very similar size to its neighbours , it took a guy called charles james , in 1911 , a famous 15,000 times of recrystalization to isolate thulium in a pure , albeit as a chloride , but a pure nonetheless , compound for the first time .
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so you may see the use of thulium increase in years to come . because it ’ s very hard to isolate because it ’ s of a very similar size to its neighbours , it took a guy called charles james , in 1911 , a famous 15,000 times of recrystalization to isolate thulium in a pure , albeit as a chloride , but a pure nonetheless , compound for the first time .
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how many recrystallizations did it take for charles james to obtain a pure thulium compound for the first time in 1911 ?
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translator : tom carter reviewer : bedirhan cinar this is the story of an invention that changed the world . imagine a machine that could cut 10 hours of work down to one . a machine so efficient that it would free up people to do other things , kind of like the personal computer . but the machine i 'm going to tell you about did none of this . in fact , it accomplished just the opposite . in the late 1700s , just as america was getting on its feet as a republic under the new u.s constitution , slavery was a tragic american fact of life . george washington and thomas jefferson both became president while owning slaves , knowing that this peculiar institution contradicted the ideals and principles for which they fought a revolution . but both men believed that slavery was going to die out as the 19th century dawned , they were , of course , tragically mistaken . the reason was an invention , a machine they probably told you about in elementary school : mr. eli whitney 's cotton gin . a yale graduate , 28-year-old whitney had come to south carolina to work as a tutor in 1793 . supposedly he was told by some local planters about the difficulty of cleaning cotton . separating the seeds from the cotton lint was tedious and time consuming . working by hand , a slave could clean about a pound of cotton a day . but the industrial revolution was underway , and the demand was increasing . large mills in great britain and new england were hungry for cotton to mass produce cloth . as the story was told , whitney had a `` eureka moment '' and invented the gin , short for engine . the truth is that the cotton gin already existed for centuries in small but inefficient forms . in 1794 , whitney simply improved upon the existing gins and then patented his `` invention '' : a small machine that employed a set of cones that could separate seeds from lint mechanically , as a crank was turned . with it , a single worker could eventually clean from 300 to one thousand pounds of cotton a day . in 1790 , about 3,000 bales of cotton were produced in america each year . a bale was equal to about 500 pounds . by 1801 , with the spread of the cotton gin , cotton production grew to 100 thousand bales a year . after the destructions of the war of 1812 , production reached 400 thousand bales a year . as america was expanding through the land acquired in the louisiana purchase of 1803 , yearly production exploded to four million bales . cotton was king . it exceeded the value of all other american products combined , about three fifths of america 's economic output . but instead of reducing the need for labor , the cotton gin propelled it , as more slaves were needed to plant and harvest king cotton . the cotton gin and the demand of northern and english factories re-charted the course of american slavery . in 1790 , america 's first official census counted nearly 700 thousand slaves . by 1810 , two years after the slave trade was banned in america , the number had shot up to more than one million . during the next 50 years , that number exploded to nearly four million slaves in 1860 , the eve of the civil war . as for whitney , he suffered the fate of many an inventor . despite his patent , other planters easily built copies of his machine , or made improvements of their own . you might say his design was pirated . whitney made very little money from the device that transformed america . but to the bigger picture , and the larger questions . what should we make of the cotton gin ? history has proven that inventions can be double-edged swords . they often carry unintended consequences . the factories of the industrial revolution spurred innovation and an economic boom in america . but they also depended on child labor , and led to tragedies like the triangle shirtwaist fire that killed more than 100 women in 1911 . disposable diapers made life easy for parents , but they killed off diaper delivery services . and do we want landfills overwhelmed by dirty diapers ? and of course , einstein 's extraordinary equation opened a world of possibilities . but what if one of them is hiroshima ?
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but they also depended on child labor , and led to tragedies like the triangle shirtwaist fire that killed more than 100 women in 1911 . disposable diapers made life easy for parents , but they killed off diaper delivery services . and do we want landfills overwhelmed by dirty diapers ?
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is there anything that has made your life easier , but you feel uncomfortable about it ? an suv instead of a hybrid ? disposable plastic as opposed to a reusable container ? describe this innovation and explain how you justify the personal dilemma .
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imagine an airplane flying one millimeter above the ground and circling the earth once every 25 seconds while counting every blade of grass . shrink all that down so that it fits in the palm of your hand , and you 'd have something equivalent to a modern hard drive , an object that can likely hold more information than your local library . so how does it store so much information in such a small space ? at the heart of every hard drive is a stack of high-speed spinning discs with a recording head flying over each surface . each disc is coated with a film of microscopic magnetised metal grains , and your data does n't live there in a form you can recognize . instead , it is recorded as a magnetic pattern formed by groups of those tiny grains . in each group , also known as a bit , all of the grains have their magnetization 's aligned in one of two possible states , which correspond to zeroes and ones . data is written onto the disc by converting strings of bits into electrical current fed through an electromagnet . this magnet generates a field strong enough to change the direction of the metal grain 's magnetization . once this information is written onto the disc , the drive uses a magnetic reader to turn it back into a useful form , much like a phonograph needle translates a record 's grooves into music . but how can you get so much information out of just zeroes and ones ? well , by putting lots of them together . for example , a letter is represented in one byte , or eight bits , and your average photo takes up several megabytes , each of which is 8 million bits . because each bit must be written onto a physical area of the disc , we 're always seeking to increase the disc 's areal density , or how many bits can be squeezed into one square inch . the areal density of a modern hard drive is about 600 gigabits per square inch , 300 million times greater than that of ibm 's first hard drive from 1957 . this amazing advance in storage capacity was n't just a matter of making everything smaller , but involved multiple innovations . a technique called the thin film lithography process allowed engineers to shrink the reader and writer . and despite its size , the reader became more sensitive by taking advantage of new discoveries in magnetic and quantum properties of matter . bits could also be packed closer together thanks to mathematical algorithms that filter out noise from magnetic interference , and find the most likely bit sequences from each chunk of read-back signal . and thermal expansion control of the head , enabled by placing a heater under the magnetic writer , allowed it to fly less than five nanometers above the disc 's surface , about the width of two strands of dna . for the past several decades , the exponential growth in computer storage capacity and processing power has followed a pattern known as moore 's law , which , in 1975 , predicted that information density would double every two years . but at around 100 gigabits per square inch , shrinking the magnetic grains further or cramming them closer together posed a new risk called the superparamagnetic effect . when a magnetic grain volume is too small , its magnetization is easily disturbed by heat energy and can cause bits to switch unintentionally , leading to data loss . scientists resolved this limitation in a remarkably simple way : by changing the direction of recording from longitudinal to perpendicular , allowing areal density to approach one terabit per square inch . recently , the potential limit has been increased yet again through heat assisted magnetic recording . this uses an even more thermally stable recording medium , whose magnetic resistance is momentarily reduced by heating up a particular spot with a laser and allowing data to be written . and while those drives are currently in the prototype stage , scientists already have the next potential trick up their sleeves : bit-patterned media , where bit locations are arranged in separate , nano-sized structures , potentially allowing for areal densities of twenty terabits per square inch or more . so it 's thanks to the combined efforts of generations of engineers , material scientists , and quantum physicists that this tool of incredible power and precision can spin in the palm of your hand .
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because each bit must be written onto a physical area of the disc , we 're always seeking to increase the disc 's areal density , or how many bits can be squeezed into one square inch . the areal density of a modern hard drive is about 600 gigabits per square inch , 300 million times greater than that of ibm 's first hard drive from 1957 . this amazing advance in storage capacity was n't just a matter of making everything smaller , but involved multiple innovations .
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what components are in hard drives ?
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some people ca n't see the forest for the trees , but before stephen sillett , no one could see or even imagine the forest in the trees . stephen was an explorer of new worlds from the start . he spent his boyhood in harrisburg , pennsylvania reading tolkien and playing dungeons and dragons with his brother scott . but when the sillett family visited their grandparent 's cabin near gettysburg , their grandmother helen poe sillett , would take the boys into the nearby mountains and forests to bird-watch . they called grandma sillett poe , and she taught the boys to identify songbirds , plants and even lichens , creatures that often look like splotches of carpet glued to the shady sides of rocks and tree trunks . looking upwards , both boys found their callings . scott became a research scientist specializing in migratory birds . stephen was more interested in the trees . the tangle of branches and leaves attracted his curiosity . what could be hidden up there ? by the time stephen was in college , that curiosity pulled him skyward to the tallest trees on earth : the ancient coast redwoods of northern california . rising from trunks up to 20 feet in diameter , redwoods can grow up to 380 feet , or 38 stories , over a 2,000 year lifetime . but no one had thought to investigate the crowns of these natural skyscrapers . were there more than just branches up there ? stephen decided to find out firsthand . in 1987 , stephen , his brother scott and his friend marwood drove from reed college in oregon to prairie creek redwoods state park in northern california . deep inside the park , stephen picked the tallest redwood he could find . its lowest branches were almost 100 feet up , far beyond his reach . but he saw a younger , shorter redwood growing next to the target tree . with a running start , he leapt and grabbed the lowest branch , pulled himself up and scurried upwards . he was free climbing without ropes or a harness , one misstep meant death . but up he went , and when he reached the peak , he swayed and leapt across the gap of space onto a branch of the target tree and into a world never seen before . his buddy marwood followed him up , and the two young men free climbed high into the redwood 's crown . stephen came across lichens like grandma poe had shown him as a boy . he noticed that the higher he went , the thicker the branches were , not the case with most trees . he found moist mats of soil many inches thick , made from fallen needles , bark , other plant debris and dust from the sky piled on the tops of the large branches . he even found reiterations : new redwood tree trunks growing out from the main trunk . the redwood had cloned itself . when stephen reached the pinnacle , he rested on a platform of crisscrossing branches and needles . growing in the soil mat was a huckleberry bush with ripe berries ! he ate some and waited for his friend . stephen had discovered a new world hundreds of feet above the ground . his climb led to more excursions , with safety equipment , thank goodness , up other ancient redwoods as he mapped and measured the architecture of branches and additional trunks in the canopy of an entire grove . stephen became an expert in the ecology of the tallest trees on earth and the rich diversity of life in their crowns , aerial ecosystems no one had imagined . there are ferns , fungi and epiphytic trees normally found at ground level like douglas firs , hemlocks and tan oaks whose roots had taken hold in the rich wet soil mats . invertebrates such as ants , bumblebees , mites , beetles , earthworms and aquatic crustacean copepods make their homes alongside flowering plants like rhododendrons , currant and elderberry bushes . ospreys , spotted owls , and jays search the canopy for food . even the marbled murrelet , a pacific seabird , flies many miles from the ocean to nest there . squirrels and voles peek out of penthouse burrows . and the top predator ? the mighty wandering salamander ! sillett 's research has changed how we think about tall trees , and bolstered the case for their conservation , not just as impressive individual organisms but as homes to countless other species . so when you look up into the branches and leaves of a tree , ask , `` what else is up there ? '' a new world might be just out of reach . so leap for it .
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his buddy marwood followed him up , and the two young men free climbed high into the redwood 's crown . stephen came across lichens like grandma poe had shown him as a boy . he noticed that the higher he went , the thicker the branches were , not the case with most trees .
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during visits to their grandparent ’ s cabin , what did grandma poe teach stephen and scott sillett ?
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what could octopuses possibly have in common with us ? after all , they do n't have lungs , spines , or even a plural noun we can all agree on . but what they do have is the ability to solve puzzles , learn through observation , and even use tools , just like some other animals we know . and what makes octopus intelligence so amazing is that it comes from a biological structure completely different from ours . the 200 or so species of octopuses are mollusks belonging to the order cephalopoda , greek for head-feet . those heads contain impressively large brains , with a brain to body ratio similar to that of other intelligent animals , and a complex nervous system with about as many neurons as that of a dog . but instead of being centralized in the brain , these 500 million neurons are spread out in a network of interconnected ganglia organized into three basic structures . the central brain only contains about 10 % of the neurons , while the two huge optic lobes contain about 30 % . the other 60 % are in the tentacles , which for humans would be like our arms having minds of their own . this is where things get even more interesting . vertebrates like us have a rigid skeleton to support our bodies , with joints that allow us to move . but not all types of movement are allowed . you ca n't bend your knee backwards , or bend your forearm in the middle , for example . cephalopods , on the other hand , have no bones at all , allowing them to bend their limbs at any point and in any direction . so shaping their tentacles into any one of the virtually limitless number of possible arrangements is unlike anything we are used to . consider a simple task , like grabbing and eating an apple . the human brain contains a neurological map of our body . when you see the apple , your brain 's motor center activates the appropriate muscles , allowing you to reach out with your arm , grab it with your hand , bend your elbow joint , and bring it to your mouth . for an octopus , the process is quite different . rather than a body map , the cephalopod brain has a behavior library . so when an octopus sees food , its brain does n't activate a specific body part , but rather a behavioral response to grab . as the signal travels through the network , the arm neurons pick up the message and jump into action to command the movement . as soon as the arm touches the food , a muscle activation wave travels all the way through the arm to its base , while the arm sends back another wave from the base to the tip . the signals meet halfway between the food and the base of the arm , letting it know to bend at that spot . what all this means is that each of an octopus 's eight arms can essentially think for itself . this gives it amazing flexibility and creativity when facing a new situation or problem , whether its opening a bottle to reach food , escaping through a maze , moving around in a new environment , changing the texture and the color of its skin to blend into the scenery , or even mimicking other creatures to scare away enemies . cephalopods may have evolved complex brains long before our vertebrate relatives . and octopus intelligence is n't just useful for octopuses . their radically different nervous system and autonomously thinking appendages have inspired new research in developing flexible robots made of soft materials . and studying how intelligence can arise along such a divergent evolutionary path can help us understand more about intelligence and consciousness in general . who knows what other forms of intelligent life are possible , or how they process the world around them .
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and octopus intelligence is n't just useful for octopuses . their radically different nervous system and autonomously thinking appendages have inspired new research in developing flexible robots made of soft materials . and studying how intelligence can arise along such a divergent evolutionary path can help us understand more about intelligence and consciousness in general .
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the majority of the octopod nervous system is composed of :
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it 's not hard to imagine a world where at any given moment , you and everyone you know could be wiped out without warning at the push of a button . this was the reality for millions of people during the 45-year period after world war ii , now known as the cold war . as the united states and soviet union faced off across the globe , each knew that the other had nuclear weapons capable of destroying it . and destruction never loomed closer than during the 13 days of the cuban missile crisis . in 1961 , the u.s. unsuccessfully tried to overthrow cuba 's new communist government . that failed attempt was known as the bay of pigs , and it convinced cuba to seek help from the u.s.s.r. soviet premier nikita khrushchev was happy to comply by secretly deploying nuclear missiles to cuba , not only to protect the island , but to counteract the threat from u.s. missiles in italy and turkey . by the time u.s. intelligence discovered the plan , the materials to create the missiles were already in place . at an emergency meeting on october 16 , 1962 , military advisors urged an airstrike on missile sites and invasion of the island . but president john f. kennedy chose a more careful approach . on october 22 , he announced that the the u.s. navy would intercept all shipments to cuba . there was just one problem : a naval blockade was considered an act of war . although the president called it a quarantine that did not block basic necessities , the soviets did n't appreciate the distinction . in an outraged letter to kennedy , khrushchev wrote , `` the violation of freedom to use international waters and international airspace is an act of aggression which pushes mankind toward the abyss of world nuclear missile war . '' thus ensued the most intense six days of the cold war . while the u.s. demanded the removal of the missiles , cuba and the u.s.s.r insisted they were only defensive . and as the weapons continued to be armed , the u.s. prepared for a possible invasion . on october 27 , a spy plane piloted by major rudolph anderson was shot down by a soviet missile . the same day , a nuclear-armed soviet submarine was hit by a small-depth charge from a u.s. navy vessel trying to signal it to come up . the commanders on the sub , too deep to communicate with the surface , thought war had begun and prepared to launch a nuclear torpedo . that decision had to be made unanimously by three officers . the captain and political officer both authorized the launch , but vasili arkhipov , second in command , refused . his decision saved the day and perhaps the world . but the crisis was n't over . for the first time in history , the u.s. military set itself to defcon 2 , the defense readiness one step away from nuclear war . with hundreds of nuclear missiles ready to launch , the metaphorical doomsday clock stood at one minute to midnight . but diplomacy carried on . in washington , d.c. , attorney general robert kennedy secretly met with soviet ambassador anatoly dobrynin . after intense negotiation , they reached the following proposal . the u.s. would remove their missiles from turkey and italy and promise to never invade cuba in exchange for the soviet withdrawal from cuba under u.n. inspection . once the meeting had concluded , dobrynin cabled moscow saying time is of the essence and we should n't miss the chance . and at 9 a.m. the next day , a message arrived from khrushchev announcing the soviet missiles would be removed from cuba . the crisis was now over . while criticized at the time by their respective governments for bargaining with the enemy , contemporary historical analysis shows great admiration for kennedy 's and khrushchev 's ability to diplomatically solve the crisis . but the disturbing lesson was that a slight communication error , or split-second decision by a commander , could have thwarted all their efforts , as it nearly did if not for vasili arkhipov 's courageous choice . the cuban missile crisis revealed just how fragile human politics are compared to the terrifying power they can unleash .
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and at 9 a.m. the next day , a message arrived from khrushchev announcing the soviet missiles would be removed from cuba . the crisis was now over . while criticized at the time by their respective governments for bargaining with the enemy , contemporary historical analysis shows great admiration for kennedy 's and khrushchev 's ability to diplomatically solve the crisis .
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which government individuals negotiated the end of the crisis on october 27 ?
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translator : andrea mcdonough reviewer : jessica ruby imagine a world in which you see numbers and letters as colored even though they 're printed in black , in which music or voices trigger a swirl of moving , colored shapes , in which words and names fill your mouth with unusual flavors . jail tastes like cold , hard bacon while derek tastes like earwax . welcome to synesthesia , the neurological phenomenon that couples two or more senses in 4 % of the population . a synesthete might not only hear my voice , but also see it , taste it , or feel it as a physical touch . sharing the same root with anesthesia , meaning no sensation , synesthesia means joined sensation . having one type , such as colored hearing , gives you a 50 % chance of having a second , third , or fourth type . one in 90 among us experience graphemes , the written elements of language , like letters , numerals , and punctuation marks , as saturated with color . some even have gender or personality . for gail , 3 is athletic and sporty , 9 is a vain , elitist girl . by contrast , the sound units of language , or phonemes , trigger synestetic tastes . for james , college tastes like sausage , as does message and similar words with the -age ending . synesthesia is a trait , like having blue eyes , rather than a disorder because there 's nothing wrong . in fact , all the extra hooks endow synesthetes with superior memories . for example , a girl runs into someone she met long ago . `` let 's see , she had a green name . d 's are green : debra , darby , dorothy , denise . yes ! her name is denise ! '' once established in childhood , pairings remain fixed for life . synesthetes inherit a biological propensity for hyperconnecting brain neurons , but then must be exposed to cultural artifacts , such as calendars , food names , and alphabets . the amazing thing is that a single nucleotide change in the sequence of one 's dna alters perception . in this way , synesthesia provides a path to understanding subjective differences , how two people can see the same thing differently . take sean , who prefers blue tasting food , such as milk , oranges , and spinach . the gene heightens normally occurring connections between the taste area in his frontal lobe and the color area further back . but suppose in someone else that the gene acted in non-sensory areas . you would then have the ability to link seemingly unrelated things , which is the definition of metaphor , seeing the similar in the dissimilar . not surprisingly , synesthesia is more common in artists who excel at making metaphors , like novelist vladimir nabokov , painter david hockney , and composers billy joel and lady gaga . but why do the rest of us non-synesthetes understand metaphors like `` sharp cheese '' or `` sweet person '' ? it so happens that sight , sound , and movement already map to one another so closely , that even bad ventriloquists convince us that the dummy is talking . movies , likewise , can convince us that the sound is coming from the actors ' mouths rather than surrounding speakers . so , inwardly , we 're all synesthetes , outwardly unaware of the perceptual couplings happening all the time . cross-talk in the brain is the rule , not the exception . and that sounds like a sweet deal to me !
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you would then have the ability to link seemingly unrelated things , which is the definition of metaphor , seeing the similar in the dissimilar . not surprisingly , synesthesia is more common in artists who excel at making metaphors , like novelist vladimir nabokov , painter david hockney , and composers billy joel and lady gaga . but why do the rest of us non-synesthetes understand metaphors like `` sharp cheese '' or `` sweet person '' ?
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synesthesia is more common in artists who excel in making metaphors .
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ok , fermium , it has absolutely no use as far as anyone knows except that it ’ s extremely radioactive . it ’ s named after enrico fermi who is a well-known physicist . fermi was an italian physicist who in the 1930s was the first person to discover artificial radioactivity . this is where neutrons , which had only recently been discovered when they did these experiments , hit an element that is not radioactive , increase the weight of the nucleus but not the number of protons and cause it to fall apart by radioactive decay . and it also , like einsteinium , where it was first found in the debris of a nuclear bomb , in fact the very first nuclear bomb that was ever tested . shortly after the fascists took power in italy , fermi moved to the united states and , as part of the manhattan project for building the atomic bomb , he built the first nuclear reactor under the football stadium , in the squash courts under the football stadium at chicago university , the university of chicago , right in the centre of chicago , and they filled the squash courts with blocks of carbon with holes in the middle through which they put rods of uranium . so the first ever sustained nuclear reaction took place in the sports field of university of chicago and if you go now there , the stadium itself has been completely demolished , but there ’ s a rather fine monument to the birth of the atomic era .
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ok , fermium , it has absolutely no use as far as anyone knows except that it ’ s extremely radioactive . it ’ s named after enrico fermi who is a well-known physicist .
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as explained by steve , what is the main use of fermium ?
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that 's what we like to see ... haha have this one handy as well ... . so zinc again is an abundant metal but it 's a metal that we all need for life , it 's part of enzymes and it 's part of of many many biologically mediated processes . i do n't know what else to say about zinc it 's a pretty boring metal . it really is a boring metal . - now i understand what my collegue said thinks bit boring . this is n't always the case and when you combine it with some other elements , it can get quite frisky , as you 'll see in a bit . - zinc is a really soft metal , it 's sort of greyish in colour , it reacts very easily with acids to produce hydrogen . in fact it 's the way that people make hydrogen in the lab , or used to . now they usually buy it in cylinders . - zinc is often found on things like roofs as well , very very high quality roofing material , very slow to oxidise . - zinc is used very widely as a coating on iron . so called galvanizing . you put a thin layer of zinc and the zinc then corrodes instead of the iron , so that it stops the iron rusting , at least for quite a long time . you can see it on corrugated iron roofs , metal gates in the countryside and so on . so this is diethylzinc , so it 's c4h10zn . - zinc is quite important biologically , and there are all sorts of enzymes in our bodies that use zinc . and particularly one called carbonic anhydrase that catalyse at the reaction of co2 and water and so without zinc , none of us could survive . the delivery of the statement that zinc is boring were greatly under anticipating the result of this experiment . really , you 've built it up now . that 's what we like to see . have this one handy as well . let 's give this a go . - i told you to fix the stuff . so who says zinc 's boring ? shall we do it again ? wow ... no i do n't think zinc is in the least bit boring . i do n't think that most elements are interesting , but zinc is interesting because it 's in the same group as cadmium and mercury and cadmium and mercury are both pretty poisonous . but zinc is essential to life . if you do n't have enough zinc you ca n't smell things . there are all sorts of enzymes in your body and those of other creatures , that wo n't work without zinc . so it 's really good . you may be bored about it , but if you did n't have zinc , you would n't even be able to be bored . www.periodicvideos.com . . . . . . . . . . . . captions by www.subply.com
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this is n't always the case and when you combine it with some other elements , it can get quite frisky , as you 'll see in a bit . - zinc is a really soft metal , it 's sort of greyish in colour , it reacts very easily with acids to produce hydrogen . in fact it 's the way that people make hydrogen in the lab , or used to . now they usually buy it in cylinders .
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how can you obtain hydrogen gas in the lab , using metallic zinc ?
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as 1905 dawned , the soon-to-be 26-year-old albert einstein faced life as a failed academic . most physicists of the time would have scoffed at the idea that this minor civil servant could have much to contribute to science . yet within the following year , einstein would publish not one , not two , not three , but four extraordinary papers , each on a different topic , that were destined to radically transform our understanding of the universe . the myth that einstein had failed math is just that . he had mastered calculus on his own by the age of 15 and done well at both his munich secondary school and at the swiss polytechnic , where he studied for a math and physics teaching diploma . but skipping classes to spend more time in the lab and neglecting to show proper deference to his professors had derailed his intended career path . passed over even for a lab assistant position , he had to settle for a job at the swiss patent office , obtained with the help of a friend 's father . working six days a week as a patent clerk , einstein still managed to make some time for physics , discussing the latest work with a few close friends , and publishing a couple of minor papers . it came as a major surprise when in march 1905 he submitted a paper with a shocking hypothesis . despite decades of evidence that light was a wave , einstein proposed that it could , in fact , be a particle , showing that mysterious phenomena , such as the photoelectric effect , could be explained by his hypothesis . the idea was derided for years to come , but einstein was simply twenty years ahead of his time . wave-particle duality was slated to become a cornerstone of the quantum revolution . two months later in may , einstein submitted a second paper , this time tackling the centuries old question of whether atoms actually exist . though certain theories were built on the idea of invisible atoms , some prominent scientists still believed them to be a useful fiction , rather than actual physical objects . but einstein used an ingenious argument , showing that the behavior of small particles randomly moving around in a liquid , known as brownian motion , could be precisely predicted by the collisions of millions of invisible atoms . experiments soon confirmed einstein 's model , and atomic skeptics threw in the towel . the third paper came in june . for a long time , einstein had been troubled by an inconsistency between two fundamental principles of physics . the well established principle of relativity , going all the way back to galileo , stated that absolute motion could not be defined . yet electromagnetic theory , also well established , asserted that absolute motion did exist . the discrepancy , and his inability to resolve it , left einstein in what he described as a state of psychic tension . but one day in may , after he had mulled over the puzzle with his friend michele besso , the clouds parted . einstein realized that the contradiction could be resolved if it was the speed of light that remained constant , regardless of reference frame , while both time and space were relative to the observer . it took einstein only a few weeks to work out the details and formulate what came to be known as special relativity . the theory not only shattered our previous understanding of reality but would also pave the way for technologies , ranging from particle accelerators , to the global positioning system . one might think that this was enough , but in september , a fourth paper arrived as a `` by the way '' follow-up to the special relativity paper . einstein had thought a little bit more about his theory , and realized it also implied that mass and energy , one apparently solid and the other supposedly ethereal , were actually equivalent . and their relationship could be expressed in what was to become the most famous and consequential equation in history : e=mc^2 . einstein would not become a world famous icon for nearly another fifteen years . it was only after his later general theory of relativity was confirmed in 1919 by measuring the bending of starlight during a solar eclipse that the press would turn him into a celebrity . but even if he had disappeared back into the patent office and accomplished nothing else after 1905 , those four papers of his miracle year would have remained the gold standard of startling unexpected genius .
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yet within the following year , einstein would publish not one , not two , not three , but four extraordinary papers , each on a different topic , that were destined to radically transform our understanding of the universe . the myth that einstein had failed math is just that . he had mastered calculus on his own by the age of 15 and done well at both his munich secondary school and at the swiss polytechnic , where he studied for a math and physics teaching diploma .
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after you viewed this lesson , how did your perception of einstein change or stay the same ?
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some of the best opportunities to learn are the moments in which we are perplexed . those moments in which you begin to wonder and question . these moments have happened throughout history . and have led to some truly amazing discoveries . take this story , for example . there once was a fellow named archimedes . he was born in 287 b.c . in the city of syracuse in sicily . he was a greek mathematician , physicist , engineer , inventor , and astronomer . one day , archimedes was summoned by the king of sicily to investigate if he had been cheated by a goldsmith . the king said he had given a goldsmith the exact amount of gold needed to make a crown . however , when the crown was ready , the king suspected that the goldsmith cheated and slipped some silver into the crown , keeping some of the gold for himself . the king asked archimedes to solve the problem . but there was a catch : he could n't do any damage to the crown . one day , while taking his bath , archimedes noticed that the water level in the bathtub rose and overflowed as he immersed himself into the tub . he suddenly realized that how much water was displaced depended on how much of his body was immersed . this discovery excited him so much that he jumped out of the tub and ran through the streets naked , shouting `` eureka ! '' which comes from the ancient greek meaning `` i found it . '' what did he find ? well , he found a way to solve the king 's problem . you see , archimedes needed to check the crown 's density to see if it was the same as the density of pure gold . density is a measure of an object 's mass divided by its volume . pure gold is very dense , while silver is less dense . so if there was silver in the crown , it would be less dense than if it were made of pure gold . but no matter what it was made of , the crown would be the same shape , which means the same volume . so if archimedes could measure the mass of the crown first , and then measure its volume , he could find out how dense it was . but it is not easy to measure a crown 's volume - it has an irregular shape , that 's different from a simple box or ball . you ca n't measure its size and multiply like you might for other shapes . the solution , archimedes realized , was to give the crown a bath . by placing it in water and seeing how much water was displaced , he could measure the volume , and he 'd calculate the density of the crown . if the crown was less dense than pure gold , then the goldsmith most definitely cheated the king . when archimedes went back to the king and did his test , the story says , he found that the goldsmith had indeed cheated the king , and slipped some silver in . these days , using the way an object displaces water to measure volume is called archimedes ' principle . the next time you take a bath , you can see archimedes ' principle in action , and maybe you 'll have a genius idea of your own .
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when archimedes went back to the king and did his test , the story says , he found that the goldsmith had indeed cheated the king , and slipped some silver in . these days , using the way an object displaces water to measure volume is called archimedes ' principle . the next time you take a bath , you can see archimedes ' principle in action , and maybe you 'll have a genius idea of your own .
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these days , using the way an object displaces water to determine volume is called :
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packed inside every cell in your body is a set of genetic instructions , 3.2 billion base pairs long . deciphering these directions would be a monumental task but could offer unprecedented insight about the human body . in 1990 , a consortium of 20 international research centers embarked on the world 's largest biological collaboration to accomplish this mission . the human genome project proposed to sequence the entire human genome over 15 years with $ 3 billion of public funds . then , seven years before its scheduled completion , a private company called celera announced that they could accomplish the same goal in just three years and at a fraction of the cost . the two camps discussed a joint venture , but talks quickly fell apart as disagreements arose over legal and ethical issues of genetic property . and so the race began . though both teams used the same technology to sequence the entire human genome , it was their strategies that made all the difference . their paths diverged in the most critical of steps : the first one . in the human genome project 's approach , the genome was first divided into smaller , more manageable chunks about 150,000 base pairs long that overlapped each other a little bit on both ends . each of these fragments of dna was inserted inside a bacterial artificial chromosome where they were cloned and fingerprinted . the fingerprints showed scientists where the fragments overlapped without knowing the actual sequence . using the overlapping bits as a guide , the researchers marked each fragment 's place in the genome to create a contiguous map , a process that took about six years . the cloned fragments were sequenced in labs around the world following one of the project 's two major principles : that collaboration on our shared heritage was open to all nations . in each case , the fragments were arbitrarily broken up into small , overlapping pieces about 1,000 base pairs long . then , using a technology called the sanger method , each piece was sequenced letter by letter . this rigorous map-based approach called hierarchical shotgun sequencing minimized the risk of misassembly , a huge hazard of sequencing genomes with many repetitive portions , like the human genome . the consortium 's `` better safe than sorry '' approach contrasted starkly with celera 's strategy called whole genome shotgun sequencing . it hinged on skipping the mapping phase entirely , a faster , though foolhardy , approach according to some . the entire genome was directly chopped up into a giant heap of small , overlapping bits . once these bits were sequenced via the sanger method , celera would take the formidable risk of reconstructing the genome using just the overlaps . but perhaps their decision was n't such a gamble because guess whose freshly completed map was available online for free ? the human genome consortium , in accordance with the project 's second major principle which held that all of the project 's data would be shared publicly within 24 hours of collection . so in 1998 , scientists around the world were furiously sequencing lines of genetic code using the tried and true , yet laborious , sanger method . finally , after three exhausting years of continuous sequencing and assembling , the verdict was in . in february 2001 , both groups simultaneously published working drafts of more than 90 % of the human genome , several years ahead of the consortium 's schedule . the race ended in a tie . the human genome project 's practice of immediately sharing its data was an unusual one . it is more typical for scientists to closely guard their data until they are able to analyze it and publish their conclusions . instead , the human genome project accelerated the pace of research and created an international collaboration on an unprecedented scale . since then , robust investment in both the public and private sector has led to the identification of many disease related genes and remarkable advances in sequencing technology . today , a person 's genome can be sequenced in just a few days . however , reading the genome is only the first step . we 're a long way away from understanding what most of our genes do and how they are controlled . those are some of the challenges for the next generation of ambitious research initiatives .
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deciphering these directions would be a monumental task but could offer unprecedented insight about the human body . in 1990 , a consortium of 20 international research centers embarked on the world 's largest biological collaboration to accomplish this mission . the human genome project proposed to sequence the entire human genome over 15 years with $ 3 billion of public funds . then , seven years before its scheduled completion , a private company called celera announced that they could accomplish the same goal in just three years and at a fraction of the cost .
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more than 20 research centers contributed to the human genome project -- what are some challenges and benefits associated with collaborating with so many partners ?
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imagine an airplane flying one millimeter above the ground and circling the earth once every 25 seconds while counting every blade of grass . shrink all that down so that it fits in the palm of your hand , and you 'd have something equivalent to a modern hard drive , an object that can likely hold more information than your local library . so how does it store so much information in such a small space ? at the heart of every hard drive is a stack of high-speed spinning discs with a recording head flying over each surface . each disc is coated with a film of microscopic magnetised metal grains , and your data does n't live there in a form you can recognize . instead , it is recorded as a magnetic pattern formed by groups of those tiny grains . in each group , also known as a bit , all of the grains have their magnetization 's aligned in one of two possible states , which correspond to zeroes and ones . data is written onto the disc by converting strings of bits into electrical current fed through an electromagnet . this magnet generates a field strong enough to change the direction of the metal grain 's magnetization . once this information is written onto the disc , the drive uses a magnetic reader to turn it back into a useful form , much like a phonograph needle translates a record 's grooves into music . but how can you get so much information out of just zeroes and ones ? well , by putting lots of them together . for example , a letter is represented in one byte , or eight bits , and your average photo takes up several megabytes , each of which is 8 million bits . because each bit must be written onto a physical area of the disc , we 're always seeking to increase the disc 's areal density , or how many bits can be squeezed into one square inch . the areal density of a modern hard drive is about 600 gigabits per square inch , 300 million times greater than that of ibm 's first hard drive from 1957 . this amazing advance in storage capacity was n't just a matter of making everything smaller , but involved multiple innovations . a technique called the thin film lithography process allowed engineers to shrink the reader and writer . and despite its size , the reader became more sensitive by taking advantage of new discoveries in magnetic and quantum properties of matter . bits could also be packed closer together thanks to mathematical algorithms that filter out noise from magnetic interference , and find the most likely bit sequences from each chunk of read-back signal . and thermal expansion control of the head , enabled by placing a heater under the magnetic writer , allowed it to fly less than five nanometers above the disc 's surface , about the width of two strands of dna . for the past several decades , the exponential growth in computer storage capacity and processing power has followed a pattern known as moore 's law , which , in 1975 , predicted that information density would double every two years . but at around 100 gigabits per square inch , shrinking the magnetic grains further or cramming them closer together posed a new risk called the superparamagnetic effect . when a magnetic grain volume is too small , its magnetization is easily disturbed by heat energy and can cause bits to switch unintentionally , leading to data loss . scientists resolved this limitation in a remarkably simple way : by changing the direction of recording from longitudinal to perpendicular , allowing areal density to approach one terabit per square inch . recently , the potential limit has been increased yet again through heat assisted magnetic recording . this uses an even more thermally stable recording medium , whose magnetic resistance is momentarily reduced by heating up a particular spot with a laser and allowing data to be written . and while those drives are currently in the prototype stage , scientists already have the next potential trick up their sleeves : bit-patterned media , where bit locations are arranged in separate , nano-sized structures , potentially allowing for areal densities of twenty terabits per square inch or more . so it 's thanks to the combined efforts of generations of engineers , material scientists , and quantum physicists that this tool of incredible power and precision can spin in the palm of your hand .
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for example , a letter is represented in one byte , or eight bits , and your average photo takes up several megabytes , each of which is 8 million bits . because each bit must be written onto a physical area of the disc , we 're always seeking to increase the disc 's areal density , or how many bits can be squeezed into one square inch . the areal density of a modern hard drive is about 600 gigabits per square inch , 300 million times greater than that of ibm 's first hard drive from 1957 . this amazing advance in storage capacity was n't just a matter of making everything smaller , but involved multiple innovations .
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what is not one of the innovations that help increasing areal density of hard drives ?
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in the 18th century , swedish botanist carolus linnaeus designed the flower clock , a timepiece made of flowering plants that bloom and close at specific times of day . linnaeus 's plan was n't perfect , but the idea behind it was correct . flowers can indeed sense time , after a fashion . mornings glories unfurl their petals like clockwork in the early morning . a closing white water lily signals that it 's late afternoon , and moon flowers , as the name suggests , only bloom under the night sky . but what gives plants this innate sense of time ? it 's not just plants , in fact . many organisms on earth have a seemingly inherent awareness of where they are in the day 's cycle . that 's because of circadian rhythms , the internal timekeepers that tick away inside many living things . these biological clocks allow organisms to keep track of time and pick up on environmental cues that help them adapt . that 's important , because the planet 's rotations and revolutions put us in a state of constant flux , although it plays out in a repetitive , predictable way . circadian rhythms incorporate various cues to regulate when an organism should wake and sleep , and perform certain activities . for plants , light and temperature are the cues which trigger reactions that play out at a molecular scale . the cells in stems , leaves , and flowers contain phytochromes , tiny molecules that detect light . when that happens , phytochromes initiate a chain of chemical reactions , passing the message down into the cellular nuclei . there , transcription factors trigger the manufacture of proteins required to carry out light-dependent processes , like photosynthesis . these phytochromes not only sense the amount of light the plant receives , but can also detect tiny differences in the distribution of wavelengths the plant takes in . with this fine-tuned sensing , phytochromes allow the plant to discern both time , the difference between the middle of the day and the evening , and place , whether it is in direct sunlight or shade , enabling the plant to match its chemical reactions to its environment . this makes for early risers . a few hours before sunrise , a typical plant is already active , creating mrna templates for its photosynthesizing machinery . as the phytochromes detect increasing sunlight , the plant readies its light-capturing molecules so it can photosynthesize and grow throughout the morning . after harvesting their morning light , plants use the rest of the day to build long chains of energy in the form of glucose polymers , like starch . the sun sets , and the day 's work is done , though a plant is anything but inactive at night . in the absence of sunlight , they metabolize and grow , breaking down the starch from the previous day 's energy harvest . many plants have seasonal rhythms as well . as spring melts the winter frost , phytochromes sense the longer days and increasing light , and a currently unknown mechanism detects the temperature change . these systems pass the news throughout the plant and make it produce blooming flowers in preparation for the pollinators brought out by warmer weather . circadian rhythms act as a link between a plant and its environment . these oscillations come from the plants themselves . each one has a default rhythm . even so , these clocks can adapt their oscillations to environmental changes and cues . on a planet that 's in constant flux , it 's the circadian rhythms that enable a plant to stay true to its schedule and to keep its own time .
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in the 18th century , swedish botanist carolus linnaeus designed the flower clock , a timepiece made of flowering plants that bloom and close at specific times of day . linnaeus 's plan was n't perfect , but the idea behind it was correct .
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what was the flower clock ?
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translator : andrea mcdonough reviewer : bedirhan cinar ever wonder where most of the food you eat every day comes from ? well , about 60 % of the food you eat is carbohydrates . as you can probably tell from its name , carbohydrates contain carbon , hydrogen , and oxygen . but where do these atoms originally come from and how do they join together to make delicious foods like fruits and pasta ? it actually all starts with the air you are exhaling this very minute , specifically the carbon dioxide molecules . plants are going to breath in this very same carbon dioxide through pores in their skin , called stomata . plants drink in water from their roots to get the needed oxygen and hydrogen atoms , and their electrons , in order to build carbohydrates . what is that thing ? well , that 's a special plant organelle inside the leaves of plants called a chloroplast . it 's green beceause of a special light-absorbing pigment called chlorophyll . each leaf has about 44,000 cells and every cell can have anywhere between 20 to 100 chloroplasts . that 's up to 4,400,000 chloroplasts ! by now , you 've probably guessed that we 're talking about the process of photosynthesis and you might be wondering when the sun is going to make its entrance . let 's go back to that original molecule of water . the plant has to split this molecule of water so it can get electrons from it . but , the plant ca n't pull that water apart by itself . it needs help from the high-energy rays of the sun . so now that the chloroplast has all the building blocks - carbon , hydrogen , oxygen , and electrons - it can use them to go through the rest of the steps of photosynthesis to transform that original carbon dioxide gas into a simple carbohydrate called glucose , c-6-h-12-o-6 . that little glucose molecule then helps to build bigger and better carbohydrates like cellulose . cellulose is a type of carbohydrate found in plants that our body can not break down . we call it fiber and we eat it in vegetables like lettuce , broccoli , and celery . plants use cellulose to keep themselves strong . the plant could also turn that glucose into starch , a large molecule that stores energy for the plant . we love eating starch from plants like potatoes , corn , and rice . so you see , when you eat plants , we 're actually benefiting from photosynthesis . the plant makes things like starch , which we eat and then break back down into glucose , the first form the plant made . then , the mitochondria in our cells , powered by the oxygen we breath , can turn glucose into pure energy molecules called atp . atp powers all work done by each and every one of your cells , things like communication , movement , and transport . but why do we have to turn that glucose into atp ? well , think of it like this . you 're excited to start your summer job at the local ice cream stand , but your boss has just told you that she is going to pay you in ice cream cones . what are you going to be able to do with those ice cream cones ? nothing , which is why you kindly asked to be paid in dollars . atp is just like dollars . it is the currency that all cells of life use while glucose is , well , kind of like ice cream . even plants have mitochondria in their cells to break down the glucose they make into atp . so as you can see , humans and plants are intricately connected . the air we breath out is used by plants to make the carbohydrates we enjoy so much . and , in the process , they are releasing the very same oxygen molecules we need to breath in in order that our mitochondria can break down our delicous carbohydrate meal .
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we call it fiber and we eat it in vegetables like lettuce , broccoli , and celery . plants use cellulose to keep themselves strong . the plant could also turn that glucose into starch , a large molecule that stores energy for the plant .
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what 's another name for cellulose ?
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so here , this is a really quite unusual sample from goodfellow and you see this is samarium , so this is one of the lanthanides . ok so samarium is a beautiful element to work with as it can change what we refer to as oxidation states very easily which gives it many more things it can do in chemistry . it ’ s also a fascinating element in the sense that we can use it to date samples from the moon . so this is a sample of samarium and there ’ s is a very small amount of it here , perhaps half of a gram . but you know there 's some interesting things we can see about this package because we can see on this label it says “ packed in argon – handle with care. ” now it ’ s packed in argon because argon is very , very inert , it doesn ’ t react with anything , so it ’ s used to store , safely , this sample so that we can get it to carry out research . but i think that this sample has perhaps become damaged because , i think , the packets maybe broken because the samarium is gone and all you can see there inside is this white powder which , i suspect , is samarium oxide , so unfortunately not elemental samarium , but close . samarium is also very important because it ’ s a neutron absorber , which means it ’ s got a lot of use in nuclear power stations . basically to stop them going ‘ boom ’ .
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but you know there 's some interesting things we can see about this package because we can see on this label it says “ packed in argon – handle with care. ” now it ’ s packed in argon because argon is very , very inert , it doesn ’ t react with anything , so it ’ s used to store , safely , this sample so that we can get it to carry out research . but i think that this sample has perhaps become damaged because , i think , the packets maybe broken because the samarium is gone and all you can see there inside is this white powder which , i suspect , is samarium oxide , so unfortunately not elemental samarium , but close . samarium is also very important because it ’ s a neutron absorber , which means it ’ s got a lot of use in nuclear power stations . basically to stop them going ‘ boom ’ .
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what is the safety role of samarium in nuclear plants ?
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it 's 4 a.m. , and the big test is in eight hours , followed by a piano recital . you 've been studying and playing for days , but you still do n't feel ready for either . so , what can you do ? well , you can drink another cup of coffee and spend the next few hours cramming and practicing , but believe it or not , you might be better off closing the books , putting away the music , and going to sleep . sleep occupies nearly a third of our lives , but many of us give surprisingly little attention and care to it . this neglect is often the result of a major misunderstanding . sleep is n't lost time , or just a way to rest when all our important work is done . instead , it 's a critical function , during which your body balances and regulates its vital systems , affecting respiration and regulating everything from circulation to growth and immune response . that 's great , but you can worry about all those things after this test , right ? well , not so fast . it turns out that sleep is also crucial for your brain , with a fifth of your body 's circulatory blood being channeled to it as you drift off . and what goes on in your brain while you sleep is an intensely active period of restructuring that 's crucial for how our memory works . at first glance , our ability to remember things does n't seem very impressive at all . 19th century psychologist herman ebbinghaus demonstrated that we normally forget 40 % of new material within the first twenty minutes , a phenomenon known as the forgetting curve . but this loss can be prevented through memory consolidation , the process by which information is moved from our fleeting short-term memory to our more durable long-term memory . this consolidation occurs with the help of a major part of the brain , known as the hippocampus . its role in long-term memory formation was demonstrated in the 1950s by brenda milner in her research with a patient known as h.m. after having his hippocampus removed , h.m. 's ability to form new short-term memories was damaged , but he was able to learn physical tasks through repetition . due to the removal of his hippocampus , h.m. 's ability to form long-term memories was also damaged . what this case revealed , among other things , was that the hippocampus was specifically involved in the consolidation of long-term declarative memory , such as the facts and concepts you need to remember for that test , rather than procedural memory , such as the finger movements you need to master for that recital . milner 's findings , along with work by eric kandel in the 90 's , have given us our current model of how this consolidation process works . sensory data is initially transcribed and temporarily recorded in the neurons as short-term memory . from there , it travels to the hippocampus , which strengthens and enhances the neurons in that cortical area . thanks to the phenomenon of neuroplasticity , new synaptic buds are formed , allowing new connections between neurons , and strengthening the neural network where the information will be returned as long-term memory . so why do we remember some things and not others ? well , there are a few ways to influence the extent and effectiveness of memory retention . for example , memories that are formed in times of heightened feeling , or even stress , will be better recorded due to the hippocampus ' link with emotion . but one of the major factors contributing to memory consolidation is , you guessed it , a good night 's sleep . sleep is composed of four stages , the deepest of which are known as slow-wave sleep and rapid eye movement . eeg machines monitoring people during these stages have shown electrical impulses moving between the brainstem , hippocampus , thalamus , and cortex , which serve as relay stations of memory formation . and the different stages of sleep have been shown to help consolidate different types of memories . during the non-rem slow-wave sleep , declarative memory is encoded into a temporary store in the anterior part of the hippocampus . through a continuing dialogue between the cortex and hippocampus , it is then repeatedly reactivated , driving its gradual redistribution to long-term storage in the cortex . rem sleep , on the other hand , with its similarity to waking brain activity , is associated with the consolidation of procedural memory . so based on the studies , going to sleep three hours after memorizing your formulas and one hour after practicing your scales would be the most ideal . so hopefully you can see now that skimping on sleep not only harms your long-term health , but actually makes it less likely that you 'll retain all that knowledge and practice from the previous night , all of which just goes to affirm the wisdom of the phrase , `` sleep on it . '' when you think about all the internal restructuring and forming of new connections that occurs while you slumber , you could even say that proper sleep will have you waking up every morning with a new and improved brain , ready to face the challenges ahead .
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instead , it 's a critical function , during which your body balances and regulates its vital systems , affecting respiration and regulating everything from circulation to growth and immune response . that 's great , but you can worry about all those things after this test , right ? well , not so fast .
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if you are getting ready for an important test at school , you should :
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our planet 's diverse thriving ecosystems may seem like permanent fixtures , but they 're actually vulnerable to collapse . jungles can become deserts , and reefs can become lifeless rocks , even without cataclysmic events , like volcanoes and asteroids . what makes one ecosystem strong and another weak in the face of change ? the answer , to a large extent , is biodiversity . biodiversity is built out of three intertwined features : ecosystem diversity , species diversity , and genetic diversity . the more intertwining there is between these features , the denser and more resilient the weave becomes . take the amazon rainforest , one of the most biodiverse regions on earth due to its complex ecosystems , huge mix of species , and the genetic variety within those species . here are tangled liana vines , which crawl up from the forest floor to the canopy , intertwining with treetops and growing thick wooden stems that support these towering trees . helped along by the vines , trees provide the seeds , fruits and leaves to herbivores , such as the tapir and the agouti , which disperse their seeds throughout the forest so they can grow . leftovers are consumed by the millions of insects that decompose and recycle nutrients to create rich soil . the rainforest is a huge system filled with many smaller systems , like this , each packed with interconnected species . every link provides stability to the next , strengthening biodiversity 's weave . that weave is further reinforced by the genetic diversity within individual species , which allows them to cope with changes . species that lack genetic diversity due to isolation or low population numbers , are much more vulnerable to fluctuations caused by climate change , disease or habitat fragmentation . whenever a species disappears because of its weakened gene pool , a knot is untied and parts of the net disintegrate . so , what if we were to remove one species from the rainforest ? would the system fall apart ? probably not . the volume of species , their genetic diversity , and the complexity of the ecosystems form such rich biodiversity in this forest that one species gap in the weave wo n't cause it to unravel . the forest can stay resilient and recover from change . but that 's not true in every case . in some environments , taking away just one important component can undermine the entire system . take coral reefs , for instance . many organisms in a reef are dependent on the coral . it provides key microhabitats , shelter and breeding grounds for thousand of species of fish , crustaceans and mollusks . corals also form interdependent relationships with fungi and bacteria . the coral itself is a loom that allows the tangled net of biodiversity to be woven . that makes coral a keystone organism , one that many others depend on for their suvival . so what happens when destructive fishing practices , pollution and ocean acidification weaken coral or even kill it altogether ? exactly what you might think . the loss of this keystone species leaves its dependents at a loss , too , threatening the entire fabric of the reef . ecosystem , species and genetic diversity together form the complex tangled weave of biodiversity that is vital for the survival of organisms on earth . we humans are woven into this biodiversity , too . when just a few strands are lost , our own well-being is threatened . cut too many links , and we risk unraveling it all . what the future brings is unpredictable , but biodiversity can give us an insurance policy , earth 's own safety net to safeguard our survival .
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the coral itself is a loom that allows the tangled net of biodiversity to be woven . that makes coral a keystone organism , one that many others depend on for their suvival . so what happens when destructive fishing practices , pollution and ocean acidification weaken coral or even kill it altogether ?
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an organism that others may depend on for survival is called a ( n ) :
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at about six o'clock in the morning on september 14 , 2015 , scientists witnessed something no human had ever seen : two black holes colliding . both about 30 times as massive as our sun , they had been orbiting each other for millions of years . as they got closer together , they circled each other faster and faster . finally , they collided and merged into a single , even bigger , black hole . a fraction of a second before their crash , they sent a vibration across the universe at the speed of light . and on earth , billions of years later , a detector called the laser interferometer gravitational wave observatory , or ligo for short , picked it up . the signal only lasted a fifth of a second and was the detector 's first observation of gravitational waves . what are these ripples in space ? the answer starts with gravity , the force that pulls any two objects together . that 's the case for everything in the observable universe . you 're pulling on the earth , the moon , the sun , and every single star , and they 're pulling on you . the more mass something has , the stronger its gravitational pull . the farther away the object , the lower its pull . if every mass has an effect on every other mass in the universe , no matter how small , then changes in gravity can tell us about what those objects are doing . fluctuations in the gravity coming from the universe are called gravitational waves . gravitational waves move out from what caused them , like ripples on a pond , getting smaller as they travel farther from their center . but what are they ripples on ? when einstein devised his theory of relativity , he imagined gravity as a curve in a surface called space-time . a mass in space creates a depression in space-time , and a ball rolling across a depression will curve like it 's being attracted to the other mass . the bigger the mass , the deeper the depression and the stronger the gravity . when the mass making the depression moves , that sends out ripples in space-time . these are gravitationl waves . what would a gravitational wave feel like ? if our bodies were sensitive enough to detect them , we 'd feel like we were being stretched sideways while being compressed vertically . and in the next instant , stretched up and down while being compressed horizontally , sideways , then up and down . this back and forth would happen over and over as the gravitational wave passed right through you . but this happens on such a minute scale that we ca n't feel any of it . so we 've built detectors that can feel it for us . that 's what the ligo detectors do . and they 're not the only ones . there are gravitational wave detectors spread across the world . these l-shaped instruments have long arms , whose exact length is measured with lasers . if the length changes , it could be because gravitational waves are stretching and compressing the arms . once the detectors feel a gravitational wave , scientists can extract information about the wave 's source . in a way , detectors like ligo are big gravitational wave radios . radio waves are traveling all around you , but you ca n't feel them or hear the music they carry . it takes the right kind of detector to extract the music . ligo detects a gravitational wave signal , which scientists then study for data about the object that generated it . they can derive information , like its mass and the shape of its orbit . we can also hear gravitational waves by playing their signals through speakers , just like the music a radio extracts from radio waves . so those two black holes colliding sounds like this . scientists call this slide whistle-like noise a chirp , and it 's the signature of any two objects orbiting into each other . the black hole collision was just one example of what gravitational waves can tell us . other high-energy astronomical events will leave gravitational echoes , too . the collapse of a star before it explodes in a supernova , or a very dense neutron stars colliding . every time we create a new tool to look at space , we discover something we did n't expect , something that might revolutionize our understanding of the universe . ligo 's no different . in the short time it 's been on , ligo 's already revealed surprises , like that black holes collide more often than we ever expected . it 's impossible to say , but exciting to imagine , what revelations may now be propagating across space towards our tiny blue planet and its new way of perceiving the universe .
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they can derive information , like its mass and the shape of its orbit . we can also hear gravitational waves by playing their signals through speakers , just like the music a radio extracts from radio waves . so those two black holes colliding sounds like this . scientists call this slide whistle-like noise a chirp , and it 's the signature of any two objects orbiting into each other .
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black holes colliding , neutron stars colliding , and a star collapsing before a supernova are just a few sources of gravitational waves . what do these have in common ; that is , what is happening to the mass in each of these that makes the gravitational waves ?
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penguins have long captured the imagination and the hearts of people the world over . but while popular culture depicts them as clumsy , adorable birds with endlessly abundant populations , the truth is that penguins are exceedingly graceful , often ornery , and their populations are in rapid free fall . their real life situation is far more precarious than people think . and if current trends do not change , it may not be long before penguins can only be found in movies . there are many things about penguins that make them odd birds , so to speak . for one thing , they are one of the few bird species that can not fly , having evolved from flight-capable birds about 60 million years ago . surprisingly , their closest living relative is the albatross , a bird known for its enormous wingspan and extraordinary soaring abilities . it may seem strange that losing the ability to fly would be an evolutionary advantage , but the penguin 's short , flipper-like wings and solid bones allow them to swim faster and dive deeper than any other bird on earth , filling an ecological niche that no other bird can . penguins inhabit the southern hemisphere , being one of the few bird species able to breed in the coldest environments . but contrary to popular belief , they are not restricted to cold regions nor are there any at the north pole . in fact , only 4 of the 18 penguin species regularly live and breed in antarctica . most penguins live in subtemperate to temperate regions . and the galapagos penguin even lives and breeds right near the equator off the coast of south america . they are also found in south africa , namibia , australia , and new zealand , as well as on a number of islands in the southern atlantic , pacific , indian , and antarctic oceans . although penguins spend 75 % of their lives at sea , they must come to shore every year to reproduce and to molt their feathers . they do this in a variety of places , from the temporary ice sheets of the antarctic to the beaches of south africa and namibia , to the rocky shores of subantarctic islands , to the craggy lava surfaces in the galapagos . different penguin species have different nesting practices . some dig burrows into dirt , sand , or dried guano ; some nest in tussock grasses ; some build nests out of small rocks , sticks , and bones ; while others do n't build any nests at all . although most penguins lay a clutch of two eggs , the two largest species , the king and the emperor , lay a single egg that they incubate on top of their feet for approximately two months . unfortunately , 15 of the 18 penguin species are currently listed as threatened , near-threatened , or endangered by the international union for conservation of nature . in the last several decades , we have seen the world populations of most penguin species decline by up to 90 % , with two of them , the yellow-eyed and galapagos penguins , down to just a few thousand birds . penguins are an indicator species , the proverbial `` canary in the coal mine . '' simply put , if penguins are dying , it means our oceans are dying . and sadly , most of this decline is attributable to human activities . historically , penguins have had to deal with multiple disturbances . the mass collection of penguin eggs and the harvesting of the seabird guano they nested in caused the dramatic decline of several penguin species . if you 're wondering what humans would want with seabird poop , it was used as an ingredient in fertilizer and in gunpowder , being so valuable that in the 19th century , it was known as white gold . current threats to penguins include the destruction of both marine and terrestrial habitats , introduced predators , entrapment in fishing nets , and pollution from plastics and chemicals . there have also been several large-scale oil spills over the past 50 years that have killed or impacted tens of thousands of penguins around the world . but the two major threats to penguins today are global warming and overfishing . global warming impacts penguins in multiple ways , from interrupting the production of krill due to decreased sea ice formation in the antarctic , to increasing the frequency and severity of storms that destroy nests , to shifting the cold water currents carrying the penguins ' prey too far away from penguin breeding and foraging grounds . even though humans may be the greatest threat to penguins , we are also their greatest hope . many research and conservation projects are underway to protect penguin habitats and restore vulnerable populations . with a little help from us and some changes in the practices that impact our planet and oceans , there is hope that our tuxedo-clad friends will still be around in the next century .
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although most penguins lay a clutch of two eggs , the two largest species , the king and the emperor , lay a single egg that they incubate on top of their feet for approximately two months . unfortunately , 15 of the 18 penguin species are currently listed as threatened , near-threatened , or endangered by the international union for conservation of nature . in the last several decades , we have seen the world populations of most penguin species decline by up to 90 % , with two of them , the yellow-eyed and galapagos penguins , down to just a few thousand birds .
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how many of the 18 penguin species are listed as near-threatened , threatened , or endangered ?
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so here we have a sample of vanadium . so vanadium is used to do catalysis , it is used for a whole range of different things . so vanadium is the third of the transition metals and , because it has more electrons , it has really quite interesting chemistry . it is also used in nature and there are a number of mushrooms that are vanadium rich . the amavadins especially is one of the materials . so here if we open , we can see on our reel is a very nice sample of vanadium wire . so this is the elemental vanadium and as you can see it is about 0.1 mm in diameter and there is 20 metres of it on this reel . some of its compounds are very reactive . i can remember that my lab mate paul was working with a compound called vanadium hexacarbonyl . he got a sample it was quite expensive , and he poured it , it came in a sealed glass vessel so he cut open the glass and poured it out and before his eyes it burst into flames and disappeared .
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so here we have a sample of vanadium . so vanadium is used to do catalysis , it is used for a whole range of different things .
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impurities of vanadium and its neighbor , chromium , are responsible for the green color of a beautiful green gemstone . what is its name ?
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translator : andrea mcdonough reviewer : bedirhan cinar so how many of you have a robot at home ? ok , i see about 20 , 30 hands . that 's actually pretty good . how many of you would want your own personal robot at home ? i know i would ! ok , so why does n't this exist ? why ca n't i go to the convenience store or the department store and , you know , go up to the cashier and say , `` yeah , i want my personal robot '' ? well , i 'm going to talk to you about how to make that happen . the thing that we need to do is to make robots smarter . now , no one will argue that we do n't have robots . we have rovers that are going to mars and are getting science data and expanding our understanding of the world . we have manufacturing robots that are helping to build our cars that we drive today . we even have robots that are helping our military , that are out disposing of bombs so our soldiers can come home safely . so we have all this , so why do n't we have the personal robot ? why do n't i have my robot chef ? because i ca n't cook . ( laughter ) so , here 's one of my robots , this is a simple walking robot , but it is by no means smart . and so , what we need to do is we need to change the definition of what a robot is . how do we do that ? well , the first step , before we even start designing and getting our hands dirty , we have to come up with rules , kind of the laws , rules of conduct . and why is this ? because if these robots are smart , they might be capable of more than we want . and so we have to come up with rules . thou , robot , shall not harm a human . thou shall obey me , and only me . thou shall always protect me at all possible times . so we have to lay the boundaries , the rules of engagement , before we actually start designing . and then we have to come up with tools . so i believe that the way to make robots smarter is to mimic people . now , our brains are complex , there 's a lot going on in there , and so , it 'd be hard to try to open up the brain and actually figure out how to mimic humans . the best way is to observe , is to actually watch people do things , and figure out what are they doing , what are their thoughts , what are their actions , what are their emotions ? and so , part of making robots smarter is actually trying to mimic humans , mimic how we do things , so maybe they can do it a little bit better . and so , some of the tools are varied . and so , i 'm classically trained as an electrical engineer . i never thought i 'd have to understand things like child psychology , infant development . so , understanding that the way infants develop to children , develop to adults , and how they learn and interact is actually important for robotics . i did n't understand that i 'd actually have to watch tapes of monkeys interacting and communicating , because they have a whole social kind of mechanism where they learn from each other , and so that 's really good to make robots smarter . and , of course , neuroscience , i 've always been fascinated with neuroscience , but i never understood that i had to figure out why do the neurons fire , what about the environment helps us to learn , and all of those really contribute to making robots a little bit smarter . and so , some of the things that i do -- and this is just a little snapshot -- one of the things is mirroring . so they say our ability to look in a mirror and wave and actually recognize that the person on the other side is us , that self-awareness , is a sign of intelligence , and that allows us to then look at someone pitch a ball and figure out , `` ok , i know how to pitch a ball , i 'm going to mirror their improvement . '' and so i actually have a robot where we are trying to design a robot health coach . and so , i have an exercise physiologist showing the robot how to do some exercises . you know , we want to get strong . and then , the other thing is learning . so , learning is important . we do this as children , we do this even as adults , we do this as elder . and yet , one form of learning is muscle memory . so how many of you play an instrument ? ok , so when you start off , for example , if you think about the violin , you start off and your instructor might actually come and move your hand a little bit or maybe move your bow a little bit up . so they actually touch you in order to give you muscle memory . and that helps you understand how to do things a little better . and so we actually have a learning methodology where of course , we 're not going to take the motors and move the legs , and so we have to nunchuk to give our robot muscle memory in terms of how to do dance moves . and then , lastly , is creativity . so , you might ask , `` robots ? creativity ? i do n't get this . why does the robot have to be creative ? what about creativity makes them smarter ? '' well , creativity and imagination , those are the things that allow us to create problems when we do n't know how to attack it . they allow us to make something out of nothing . i mean , if you look at the apps that at out there and the tablets , and the ipads , and the iphones , and the androids -- 20 years ago they did n't exist . so , how is it that we got from something where there was nothing and expanded ? it was our imagination . it was our creativity . and these are the things that allow us to figure out new things . and so , i have a robot that is creative , it plays piano , is a composer , and if you listen , it plays `` twinkle , twinkle little star . '' ( music ) so , all of this together , the last thing is interaction . so , you have a robot , you want it to be your playmate , your teacher , your instructor , you want it to interact . and is n't it so cute ? ( laughter ) so , interaction is key , it is key to understanding how to work in our world with us , and so the interaction piece is very important . it deals with communication , it deals with understanding , it deals with gaze , it deals with attention . all of these things together allow that interaction and our robots to be smart . and so these are just some of the tools that we use in order to make robots smarter . so , i want to leave you with one thought . so , i 'm all for robots and smart robots . i mean , that 's what i do , i 'd be out of a job if i did n't believe in that . but yet , where does it end ? how far do we push it ? how far and how smart should we make our smart robots ? thank you . ( applause )
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so , you might ask , `` robots ? creativity ? i do n't get this .
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how do you define creativity ?
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bees are very busy little matchmakers . wingmen in every sense of the word . you see , the bees ' side of the whole `` birds and the bees '' business is to help plants find mates and reproduce . in their work as pollinators , honeybees are integral to the production of nearly 1/3 of the food that we eat . and these bees , dutifully helping lonely plants have sex , are n't alone . but rather are part of a very complex network of matchmaking creatures , critical for the pollination of natural ecosystems and crops . plants in many natural ecosystems need help to have sex . like many of us , they 're too busy to find a relationship . they have too much photosynthesis to do , and they ca n't find the time to evolve feet and walk to a singles bar . those places are called meat markets for a reason , because plants ca n't walk . so they need matchmaker pollinators to transport their pollen grains to flowers of the same plant species , and they pay these pollinators with food . today , around 170,000 plant species receive pollination services from more than 200,000 pollinator species . pollinators include many species of bees , butterflies , moths , flies , wasps , beetles , even birds and bats , who together help pollinate many species of trees , shrubs and other flowering plants . in return , flowering plants are an abundant and diverse food source for pollinators . for instance , fossil records suggest bees may have evolved from wasps that gave up hunting after they acquired a taste for nectar . plant pollinator networks are everywhere . ecologists record these networks in the field by observing which pollinators visit which plants , or by analyzing the identity of pollen loads on their bodies . networks , registered in these ways , contain from 20 to 800 species . these networks show a repeated structure , or architecture . pollinators interact with plants in a very heterogenous way . most plants are specialists , they have only one or a few matchmakers . meanwhile , only a few generalist plants hire a diverse team of matchmakers , getting visits from almost all the pollinators of the network . the same occurs with pollinators . most are specialists that feed on only a few plant species , while a few pollinators , including the honeybee usually , are generalists , busily feeding from and matchmaking for almost all the plant species in that ecosystem . what 's interesting is that specialists and generalists across both plants and pollinators , sort themselves out in a particular pattern . most pollinator networks , for which we have data , are nested . in a nested network , specialists tend to interact more with generalists than with other specialists . this is because if you 're a specialist plant , and your only matchmaker also specializes on you as its only food source , you 're each more vulnerable to extinction . so , you 're better off specializing on a generalist pollinator that has other sources of food to ensure its persistence in bad years . the same goes if you 're a specialist pollinator . you 're better off in the long run specializing on a generalist plant that gets pollinated by other species in times when you 're not around to help . finally , in addition to nestedness , the networks are usually modular . this means that the species in a network are compartmentalized into modules of plants and animals that interact more with each other than with species in other modules . think of them like social cliques . a plant or pollinator dying off will effect the species in its module , but those effects will be less severe on the rest of the network . why 's all that important ? because plant pollinator network structure effects the stability of ecosystems . heterogeneous distribution , nestedness and modularity enable networks to better prevent and respond to extinctions . that 's critical because nature is never static . some species may not show up every year . plants flower at different times . pollinators mature on varying schedules . generalist pollinators have to adapt their preferences depending on who 's flowering when . so from one flowering season to the next , the participants and patterns of matchmaking can drastically change . with all those variables , you can understand the importance of generalist pollinators , like bees , to the stability of not only a crop harvest , but the entire network of plants and pollinators we see in nature , and rely on for life . next time you see a bee fly by , remember that it belongs to a complex network of matchmakers critical to the love lives of plants all around you .
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in return , flowering plants are an abundant and diverse food source for pollinators . for instance , fossil records suggest bees may have evolved from wasps that gave up hunting after they acquired a taste for nectar . plant pollinator networks are everywhere .
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fossil records suggest bees may have evolved from ________ that gave up hunting after they acquired a taste for nectar .
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translator : andrea mcdonough reviewer : bedirhan cinar this is zeno of elea , an ancient greek philosopher famous for inventing a number of paradoxes , arguments that seem logical , but whose conclusion is absurd or contradictory . for more than 2,000 years , zeno 's mind-bending riddles have inspired mathematicians and philosophers to better understand the nature of infinity . one of the best known of zeno 's problems is called the dichotomy paradox , which means , `` the paradox of cutting in two '' in ancient greek . it goes something like this : after a long day of sitting around , thinking , zeno decides to walk from his house to the park . the fresh air clears his mind and help him think better . in order to get to the park , he first has to get half way to the park . this portion of his journey takes some finite amount of time . once he gets to the halfway point , he needs to walk half the remaining distance . again , this takes a finite amount of time . once he gets there , he still needs to walk half the distance that 's left , which takes another finite amount of time . this happens again and again and again . you can see that we can keep going like this forever , dividing whatever distance is left into smaller and smaller pieces , each of which takes some finite time to traverse . so , how long does it take zeno to get to the park ? well , to find out , you need to add the times of each of the pieces of the journey . the problem is , there are infinitely many of these finite-sized pieces . so , should n't the total time be infinity ? this argument , by the way , is completely general . it says that traveling from any location to any other location should take an infinite amount of time . in other words , it says that all motion is impossible . this conclusion is clearly absurd , but where is the flaw in the logic ? to resolve the paradox , it helps to turn the story into a math problem . let 's supposed that zeno 's house is one mile from the park and that zeno walks at one mile per hour . common sense tells us that the time for the journey should be one hour . but , let 's look at things from zeno 's point of view and divide up the journey into pieces . the first half of the journey takes half an hour , the next part takes quarter of an hour , the third part takes an eighth of an hour , and so on . summing up all these times , we get a series that looks like this . `` now '' , zeno might say , `` since there are infinitely many of terms on the right side of the equation , and each individual term is finite , the sum should equal infinity , right ? '' this is the problem with zeno 's argument . as mathematicians have since realized , it is possible to add up infinitely many finite-sized terms and still get a finite answer . `` how ? '' you ask . well , let 's think of it this way . let 's start with a square that has area of one meter . now let 's chop the square in half , and then chop the remaining half in half , and so on . while we 're doing this , let 's keep track of the areas of the pieces . the first slice makes two parts , each with an area of one-half the next slice divides one of those halves in half , and so on . but , no matter how many times we slice up the boxes , the total area is still the sum of the areas of all the pieces . now you can see why we choose this particular way of cutting up the square . we 've obtained the same infinite series as we had for the time of zeno 's journey . as we construct more and more blue pieces , to use the math jargon , as we take the limit as n tends to infinity , the entire square becomes covered with blue . but the area of the square is just one unit , and so the infinite sum must equal one . going back to zeno 's journey , we can now see how how the paradox is resolved . not only does the infinite series sum to a finite answer , but that finite answer is the same one that common sense tells us is true . zeno 's journey takes one hour .
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for more than 2,000 years , zeno 's mind-bending riddles have inspired mathematicians and philosophers to better understand the nature of infinity . one of the best known of zeno 's problems is called the dichotomy paradox , which means , `` the paradox of cutting in two '' in ancient greek . it goes something like this : after a long day of sitting around , thinking , zeno decides to walk from his house to the park .
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the word “ dichotomy ” translates as
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ah , spring . grass growing , flowers blooming , trees growing new leaves , but if you get allergies , this explosion of new life probably inspires more dread than joy . step outside , and within minutes , you 're sneezing and congested . your nose is running , your eyes are swollen and watery , your throat is itchy . for you and millions of others , it 's seasonal allergy time . so what 's behind this onslaught of mucus ? the answer lies within you . it 's your immune system . seasonal allergies , also called hay fever , or allergic rhinitis , are a hypersensitive immune response to something that 's not actually harmful . pollen from trees and grass , and mold spores from tiny fungi find their way into your mucous membranes and your body attacks these innocuous travelers the same way it would infectious bacteria . the immune system has a memory . when a foreign substance gets tagged as threatening , white blood cells produce customized antibodies that will recognize the offender the next time around . they then promptly recruit the body 's defense team . but sometimes , the immune system accidentally discriminates against harmless substances , like pollen . when it wafts in again , antibodies on the surface of white blood cells recognize it and latch on . this triggers the cell to release inflammatory chemicals , like histamine , which stimulate nerve cells , and cause blood vessels in the mucous membranes to swell and leak fluid . in other words , itchiness , sneezing , congestion , and a runny nose . allergies usually , but not always , show up for the first time during childhood . but why do some people get allergies and others do n't ? allergies tend to run in families , so genetics may be one culprit . in fact , errors in a gene that helps regulate the immune system are associated with higher rates of allergies . the environment you grow up in matters , too . being exposed to an allergen as a baby makes you less likely to actually develop an allergy to it . people who grow up on farms , in big families , and in the developing world also tend to have fewer allergies , although there are plenty of exceptions , partly thanks to genetics . one theory is that as children , they encounter more of the microbes and parasites that co-evolved with traditional hunter-gatherer societies . called the hygiene hypothesis , the idea is that when the immune system is n't exposed to the familiar cast of microbes , it 'll keep itself busy mounting defenses against harmless substances , like pollen . another theory is that an immune system toughened up by a barrage of pathogens is less likely to overreact to allergens . pollen is a common offender , just because we encounter so much of it , but there 's a long list of substances : dust , animal dander , insect venom , medications , certain foods , that can send your immune system into overdrive . some of these reactions can be scary . an allergy can develop into full-blown anaphylaxis , which typically brings on severe swelling , shortness of breath , and very low blood pressure . it can be deadly . the body can even have an allergic reaction to itself causing auto-immune disorders , like multiple sclerosis , lupus , and type 1 diabetes . but even non-life threatening allergy symptoms can make you miserable , so what can you do about it ? medications can help reduce the symptoms . the most common ones keep histamines from binding to your cells . these antihistamines stop the inflammation response . steroids can help dial down the immune system . another more permanent option is immunotherapy . deliberate , controlled exposure to gradually increasing amounts of an allergen can teach the immune system that it is n't dangerous after all . and if you 're really adventurous , there 's a less traditional option : intestinal parasites . when hookworms sink their teeth into the intestinal wall , they secrete chemicals that blunt the immune system . some studies suggest that hookworms can treat allergies , which may be another reason allergies are more common in industrialized countries where hookworms are few and far between . of course , you can always just wait your seasonal allergies out . the spring pollen onslaught dwindles by mid-summer , just in time for ragweed season .
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some studies suggest that hookworms can treat allergies , which may be another reason allergies are more common in industrialized countries where hookworms are few and far between . of course , you can always just wait your seasonal allergies out . the spring pollen onslaught dwindles by mid-summer , just in time for ragweed season .
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some people claim that eating local honey will reduce seasonal allergies . is this strategy related to any of the treatments mentioned in the lesson ?
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translator : tom carter reviewer : bedirhan cinar the periodic table is instantly recognizable . it 's not just in every chemistry lab worldwide , it 's found on t-shirts , coffee mugs , and shower curtains . but the periodic table is n't just another trendy icon . it 's a massive slab of human genius , up there with the taj mahal , the mona lisa , and the ice cream sandwich -- and the table 's creator , dmitri mendeleev , is a bonafide science hall-of-famer . but why ? what 's so great about him and his table ? is it because he made a comprehensive list of the known elements ? nah , you do n't earn a spot in science valhalla just for making a list . besides , mendeleev was far from the first person to do that . is it because mendeleev arranged elements with similar properties together ? not really , that had already been done too . so what was mendeleev 's genius ? let 's look at one of the first versions of the periodic table from around 1870 . here we see elements designated by their two-letter symbols arranged in a table . check out the entry of the third column , fifth row . there 's a dash there . from that unassuming placeholder springs the raw brilliance of mendeleev . that dash is science . by putting that dash there , dmitri was making a bold statement . he said -- and i 'm paraphrasing here -- y'all have n't discovered this element yet . in the meantime , i 'm going to give it a name . it 's one step away from aluminum , so we 'll call it eka-aluminum , `` eka '' being sanskrit for one . nobody 's found eka-aluminum yet , so we do n't know anything about it , right ? wrong ! based on where it 's located , i can tell you all about it . first of all , an atom of eka-aluminum has an atomic weight of 68 , about 68 times heavier than a hydrogen atom . when eka-aluminum is isolated , you 'll see it 's a solid metal at room temperature . it 's shiny , it conducts heat really well , it can be flattened into a sheet , stretched into a wire , but its melting point is low . like , freakishly low . oh , and a cubic centimeter of it will weigh six grams . mendeleev could predict all of these things simply from where the blank spot was , and his understanding of how the elements surrounding it behave . a few years after this prediction , a french guy named paul emile lecoq de boisbaudran discovered a new element in ore samples and named it gallium after gaul , the historical name for france . gallium is one step away from aluminum on the periodic table . it 's eka-aluminum . so were mendeleev 's predictions right ? gallium 's atomic weight is 69.72 . a cubic centimeter of it weighs 5.9 grams . it 's a solid metal at room temperature , but it melts at a paltry 30 degrees celcius , 85 degrees fahrenheit . it melts in your mouth and in your hand . not only did mendeleev completely nail gallium , he predicted other elements that were unknown at the time : scandium , germanium , rhenium . the element he called eka-manganese is now called technetium . technetium is so rare it could n't be isolated until it was synthesized in a cyclotron in 1937 , almost 70 years after dmitri predicted its existence , 30 years after he died . dmitri died without a nobel prize in 1907 , but he wound up receiving a much more exclusive honor . in 1955 , scientists at uc berkeley successfully created 17 atoms of a previously undiscovered element . this element filled an empty spot in the perodic table at number 101 , and was officially named mendelevium in 1963 . there have been well over 800 nobel prize winners , but only 15 scientists have an element named after them . so the next time you stare at a periodic table , whether it 's on the wall of a university classroom or on a five-dollar coffee mug , dmitri mendeleev , the architect of the periodic table , will be staring back .
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in 1955 , scientists at uc berkeley successfully created 17 atoms of a previously undiscovered element . this element filled an empty spot in the perodic table at number 101 , and was officially named mendelevium in 1963 . there have been well over 800 nobel prize winners , but only 15 scientists have an element named after them .
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in 1963 , what did scientists officially name the element at 101 on the periodic table ?
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a national hero ? or public enemy number one ? historical figures are often controversial , but few were as deified or vilified in their lifetime as the seventh president of the united states . this is history vs. andrew jackson . `` order , order , hm , uh , what were we ... ah yes , mr. jackson ! you stand accused of degrading the office of the presidency , causing financial collapse and wanton cruelty against american indians . how do you plead ? '' `` now , your honor , i am not a big city lawyer , but i do know a few things . and i know that president jackson was a self-made frontiersman , a great general , a real man of the people . '' `` your honor , this 'man of the people ' was a gambler , a drunk , and a brawler . why , i 've heard it said that he would fight at the drop of the hat and then drop the hat himself . i ask you , was such a man fit for the most distinguished office in the nation ? can we forget the debacle of his inauguration ? who ever heard of inviting a drunken mob into the white house ? it took ages to get the upholstery clean . '' `` that drunken mob , sir , was the american people , and they deserve to celebrate their victory . '' `` order , order ! now , did this celebration have pie ? '' `` very well . mr. jackson , is it not the case that immediately upon assuming office you introduced the spoils system , replacing hundreds of perfectly good federal employees with incompetent party loyalists ? '' `` your honor , the president did no such thing . he tried to institute rotation in office to avoid any profiteering or funny business . it was the rest of the party who insisted on giving posts to their lackeys . '' `` but mr. jackson complied , did he not ? '' `` now , uh , see here . '' `` moving on . mr. jackson , did you not help to cause the financial panic of 1837 , and the ensuing economic depression with your obsessive war against the bank of the united states ? was not vetoing its reauthorization , as you did in 1832 , an act of irresponsible populace pandering that made no economic sense ? '' `` your honor , the gentleman has quite the imagination . that bank was just a way for rich yanks to get richer . and all that money panic was caused when british banks raised interest rates and cut lending . to blame it on the president is preposterous , i say . '' `` but if mr. jackson had not destroyed the national bank , it would have been able to lend to farmers and businesses when other credit dried up , would it not ? '' `` hm , this is all highly speculative . can we move on ? '' `` certainly , your honor . we now come to mr. jackson 's most terrible offense : forcing entire tribes out of their native lands via the indian removal act . '' `` i resent that accusation , sir . the u.s. of a. bought that land from the indians fair and square . '' `` do you call coercion and threats by a nation with a far more powerful army fair and square ? or signing a treaty for removing the cherokee with a small group that did n't include their actual leaders ? they did n't have time to properly supply themselves before the army came and forced them to march the trail of tears . '' `` now , hold on a minute . this was all van buren 's doing after president jackson left office . '' `` but mr. jackson laid the groundwork and made sure the treaty was ratified . all president van buren had to do afterwards was enforce it . '' `` look here , your honor . our government 's been purchasing indian land since the beginning , and my client was negotiating these deals even before he was president . president jackson truly believed it was best for the indians to get compensated for their land and move out west , where there was plenty of space for them to keep living the way they were accustomed , rather than stick around and keep butting heads with the white settlers . some of whom , i remind our court , wanted to exterminate them outright . it was a different time . '' `` and yet , even in this different time , there were many in congress and even the supreme court who saw how wrong the removal act was and loudly opposed it , were there not ? '' `` my client was under a great deal of pressure . i say , do you think it 's easy governing such a huge country and keeping the union together , when states are fixing to nullify federal laws ? president jackson barely got south carolina to back down over those import tariffs , and then georgia had to go discover gold and start grabbing up cherokee land . it was either get the indians to move or get in another fight with a state government . '' `` so , you admit that mr. jackson sacrified moral principles to achieve some political goals ? '' `` i do declare , show me one leader who has n't . '' as societies change and morals evolve , yesterday 's hero may become tomorrow 's villain , or vice versa . history may be past , but our understanding of it is always on trial .
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`` certainly , your honor . we now come to mr. jackson 's most terrible offense : forcing entire tribes out of their native lands via the indian removal act . '' `` i resent that accusation , sir .
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the indian removal act sought to relocate the _________ tribe west of the mississippi river ?
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you know how sometimes you go to bake a cake but your bananas have all gone rotten , your utensils have rusted , you trip and pour all of your baking soda into the vinegar jug , and then your oven explodes ? my friend , you and your chemical reactions have fallen victim to enthalpy and entropy and , boy , are they forces to be reckoned with . now , your reactants are all products . so , what are these `` e '' words , and what 's their big idea ? let 's start with enthalpy , an increase or decrease of energy during a chemical reaction . every molecule has a certain amount of chemical potential energy stored within the bonds between its atoms . chemicals with more energy are less stable , and thus , more likely to react . let 's visualize the energy flow in a reaction , the combustion of hydrogen and oxygen , by playing a round of crazy golf . our goal is to get a ball , the reactant , up a small rise and down the other much steeper slope . where the hill goes up , we need to add energy to the ball , and where it goes down , the ball releases energy into its surroundings . the hole represents the product , or result of the reaction . when the reaction period ends , the ball is inside the hole , and we have our product : water . this , like when our oven exploded , is an exothermic reaction , meaning that the chemical 's final energy is less than its starting energy , and the difference has been added to the surrounding environment as light and heat . we can also play out the opposite type of reaction , an endothermic reaction , where the final energy is greater than the starting energy . that 's what we were trying to achieve by baking our cake . the added heat from the oven would change the chemical structure of the proteins in the eggs and various compounds in the butter . so that 's enthalpy . as you might suspect , exothermic reactions are more likely to happen than endothermic ones because they require less energy to occur . but there 's another independent factor that can make reactions happen : entropy . entropy measures a chemical 's randomness . here 's an enormous pyramid of golf balls . its ordered structure means it has low entropy . however , when it collapses , we have chaos everywhere , balls bouncing high and wide . so much so that some even go over the hill . this shift to instability , or higher entropy , can allow reactions to happen . as with the golf balls , in actual chemicals this transition from structure to disorder gets some reactants past the hump and lets them start a reaction . you can see both enthalpy and entropy at play when you go to light a campfire to cook dinner . your match adds enough energy to activate the exothermic reaction of combustion , converting the high-energy combustible material in the wood to lower energy carbon dioxide and water . entropy also increases and helps the reaction along because the neat , organized log of wood is now converted into randomly moving water vapor and carbon dioxide . the energy shed by this exothermic reaction powers the endothermic reaction of cooking your dinner . bon appétit !
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but there 's another independent factor that can make reactions happen : entropy . entropy measures a chemical 's randomness . here 's an enormous pyramid of golf balls .
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when a neat , ordered chemical is changed into a more disordered chemical , there is an increase in _____ .
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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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cicadas are very loud . can you think of other animals that call for mates like cicadas do ?
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for the microscopic lab worm , c. elegans life equates to just a few short weeks on earth . compare that with the tortoise , which can age to more than 100 years . mice and rats reach the end of their lives after just four years , while for the bowhead whale , earth 's longest-lived mammal , death can come after 200 . like most living things , the vast majority of animals gradually degenerate after reaching sexual maturity in the process known as aging . but what does it really mean to age ? the drivers behind this process are varied and complicated , but aging is ultimately caused by cell death and dysfunction . when we 're young , we constantly regenerate cells in order to replace dead and dying ones . but as we age , this process slows down . in addition , older cells do n't perform their functions as well as young ones . that makes our bodies go into a decline , which eventually results in disease and death . but if that 's consistently true , why the huge variance in aging patterns and lifespan within the animal kingdom ? the answer lies in several factors , including environment and body size . these can place powerful evolutionary pressures on animals to adapt , which in turn makes the aging process different across species . consider the cold depths of the atlantic and arctic seas , where greenland sharks can live to over 400 years , and the arctic clam known as the quahog can live up to 500 . perhaps the most impressive of these ocean-dwelling ancients is the antarctic glass sponge , which can survive over 10,000 years in frigid waters . in cold environments like these , heartbeats and metabolic rates slow down . researchers theorize that this also causes a slowing of the aging process . in this way , the environment shapes longevity . when it comes to size , it 's often , but not always , the case that larger species have a longer lifespan than smaller ones . for instance , an elephant or whale will live much longer than a mouse , rat , or vole , which in turn have years on flies and worms . some small animals , like worms and flies , are also limited by the mechanics of their cell division . they 're mostly made up of cells that ca n't divide and be replaced when damaged , so their bodies expire more quickly . and size is a powerful evolutionary driver in animals . smaller creatures are more prone to predators . a mouse , for instance , can hardly expect to survive more than a year in the wild . so , it has evolved to grow and reproduce more rapidly , like an evolutionary defense mechanism against its shorter lifespan . larger animals , by contrast , are better at fending off predators , and so they have the luxury of time to grow to large sizes and reproduce multiple times during their lives . exceptions to the size rule include bats , birds , moles , and turtles , but in each case , these animals have other adaptations that allow them to escape predators . but there are still cases where animals with similar defining features , like size and habitat , age at completely different rates . in these cases , genetic differences , like how each organism 's cells respond to threats , often account for the discrepancies in longevity . so it 's the combination of all these factors playing out to differing degrees in different animals that explains the variability we see in the animal kingdom . so what about us ? humans currently have an average life expectancy of 71 years , meaning that we 're not even close to being the longest living inhabitants on earth . but we are very good at increasing our life expectancy . in the early 1900s , humans only lived an average of 50 years . since then , we 've learned to adapt by managing many of the factors that cause deaths , like environmental exposure and nutrition . this , and other increases in life expectancy make us possibly the only species on earth to take control over our natural fate .
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a mouse , for instance , can hardly expect to survive more than a year in the wild . so , it has evolved to grow and reproduce more rapidly , like an evolutionary defense mechanism against its shorter lifespan . larger animals , by contrast , are better at fending off predators , and so they have the luxury of time to grow to large sizes and reproduce multiple times during their lives .
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which of the following has the shortest lifespan ?
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the victory of the underdog over the favored team . the last minute penalty shot that wins the tournament . the high-energy training montages . many people love to glorify victory on the playing field , cheer for favorite teams , and play sports . but here 's a question : should we be so obsessed with sports ? is playing sports actually as good for us as we make it out to be , or just a fun and entertaining pastime ? what does science have to say ? first of all , it 's well accepted that exercise is good for our bodies and minds , and that 's definitely true . exercising , especially when we 're young , has all sorts of health benefits , like strengthening our bones , clearing out bad cholesterol from our arteries , and decreasing the risk of stroke , high blood pressure , and diabetes . our brains also release a number of chemicals when we workout , including endorphins . these natural hormones , which control pain and pleasure responses in the cental nervous system , can lead to feelings of euphoria , or , what 's often called , a runner 's high . increased endorphins and consistent physical activity in general can sharpen your focus and improve your mood and memory . so does that mean we get just as much benefit going to the gym five days a week as we would joining a team and competing ? well , here 's where it gets interesting : because it turns out that if you can find a sport and a team you like , studies show that there are all sorts of benefits that go beyond the physical and mental benefits of exercise alone . some of the most significant are psychological benefits , both in the short and long term . some of those come from the communal experience of being on a team , for instance , learning to trust and depend on others , to accept help , to give help , and to work together towards a common goal . in addition , commitment to a team and doing something fun can also make it easier to establish a regular habit of exercise . school sport participation has also been shown to reduce the risk of suffering from depression for up to four years . meanwhile , your self-esteem and confidence can get a big boost . there are a few reasons for that . one is found in training . just by working and working at skills , especially with a good coach , you reinforce a growth mindset within yourself . that 's when you say , `` even if i ca n't do something today , i can improve myself through practice and achieve it eventually . '' that mindset is useful in all walks of life . and then there 's learning through failure , one of the most transformative , long-term benefits of playing sports . the experience of coming to terms with defeat can build the resilience and self-awareness necessary to manage academic , social , and physical hurdles . so even if your team is n't winning all the time , or at all , there 's a real benefit to your experience . now , not everyone will enjoy every sport . perhaps one team is too competitive , or not competitive enough . it can also take time to find a sport that plays to your strengths . that 's completely okay . but if you spend some time looking , you 'll be able to find a sport that fits your individual needs , and if you do , there are so many benefits . you 'll be a part of a supportive community , you 'll be building your confidence , you 'll be exercising your body , and you 'll be nurturing your mind , not to mention having fun .
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some of the most significant are psychological benefits , both in the short and long term . some of those come from the communal experience of being on a team , for instance , learning to trust and depend on others , to accept help , to give help , and to work together towards a common goal . in addition , commitment to a team and doing something fun can also make it easier to establish a regular habit of exercise .
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being on a sports team means learning to trust and depend on others , accept and give help , and work together towards a common goal . therefore , being on a team can lead to :
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when reverend jim jones founded the peoples temple in 1955 , few could have imagined its horrifying end . this progressive religious movement rose in popularity and gained support from some of san francisco 's most prominent politicians . but in 1977 , amidst revelations of brainwashing and abuse , jones moved with several hundred followers to establish the commune of jonestown in guyana . billed as a utopian paradise , the colony was more like a prison camp , and when a congressional delegation arrived to investigate its conditions , jones executed his final plan . on november 18 , 1978 , 909 men , women , and children died after being forced to drink poisoned flavor aid . that grizzly image has since been immortalized as shorthand slang for single-minded cult-like thinking , `` they drank the kool-aid . '' today , there are thousands of cults around the world . it 's important to note two things about them . first , not all cults are religious . some are political , therapy-based , focused on self-improvement , or otherwise . and on the flip side , not all new religions are what we 're referring to as cults . so what exactly defines our modern understanding of cults , and why do people join them ? broadly speaking , a cult is a group or movement with a shared commitment to a usually extreme ideology that 's typically embodied in a charismatic leader . and while few turn out as deadly as jonestown or heaven 's gate , which ended in a mass suicide of 39 people in 1997 , most cults share some basic characteristics . a typical cult requires a high level of commitment from its members and maintains a strict hierarchy , separating unsuspecting supporters and recruits from the inner workings . it claims to provide answers to life 's biggest questions through its doctrine , along with the required recipe for change that shapes a new member into a true believer . and most importantly , it uses both formal and informal systems of influence and control to keep members obedient , with little tolerance for internal disagreement or external scrutiny . you might wonder whether some of these descriptions might also apply to established religions . in fact , the world `` cultus '' originally described people who cultivated the worship of certain gods by performing rituals and maintaining temples . but in time , it came to mean excessive devotion . many religions began as cults , but integrated into the fabric of the larger society as they grew . a modern cult , by contrast , separates its members from others . rather than providing guidelines for members to live better lives , a cult seeks to directly control them , from personal and family relationships , to financial assets and living arrangements . cults also demand obedience to human leaders who tend to be highly persuasive people with authoritarian and narcissistic streaks motivated by money , sex , power , or all three . while a cult leader uses personal charisma to attract initial followers , further expansion works like a pyramid scheme , with early members recruiting new ones . cults are skilled at knowing whom to target , often focusing on those new to an area , or who have recently undergone some personal or professional loss . loneliness and a desire for meaning make one susceptible to friendly people offering community . the recruitment process can be subtle , sometimes taking months to establish a relationship . in fact , more than two-thirds of cult members are recruited by a friend , family member , or co-worker whose invitations are harder to refuse . once in the cult , members are subjected to multiple forms of indoctrination . some play on our natural inclination to mimic social behaviors or follow orders . other methods may be more intense using techniques of coercive persuasion involving guilt , shame , and fear . and in many cases , members may willingly submit out of desire to belong and to attain the promised rewards . the cult environment discourages critical thinking , making it hard to voice doubts when everyone around you is modeling absolute faith . the resulting internal conflict , known as cognitive dissonance , keeps you trapped , as each compromise makes it more painful to admit you 've been deceived . and though most cults do n't lead members to their death , they can still be harmful . by denying basic freedoms of thought , speech , and association , cults stunt their members ' psychological and emotional growth , a particular problem for children , who are deprived of normal developmental activities and milestones . nevertheless , many cult members eventually find a way out , whether through their own realizations , the help of family and friends , or when the cult falls apart due to external pressure or scandals . many cults may be hard to identify , and for some , their beliefs , no matter how strange , are protected under religious freedom . but when their practices involve harassment , threats , illegal activities , or abuse , the law can intervene . believing in something should not come at the cost of your family and friends , and if someone tells you to sacrifice your relationships or morality for the greater good , they 're most likely exploiting you for their own .
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many religions began as cults , but integrated into the fabric of the larger society as they grew . a modern cult , by contrast , separates its members from others . rather than providing guidelines for members to live better lives , a cult seeks to directly control them , from personal and family relationships , to financial assets and living arrangements .
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most cult members are lonely people who get recruited by friendly strangers .
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the story of the buddha ’ s life , like all of buddhism , is a story about confronting suffering . he was born between the sixth and fourth century b.c. , the son of a wealthy king in the himalayan foothills of nepal . it was prophesied that the young buddha — then called siddhartha gautama — would either become the emperor of india or a very holy man . since siddhartha ’ s father desperately wanted him to become the former , he kept the child isolated in a palace . young gautama had every imaginable luxury : jewels , servants , lotus ponds , even beautiful dancing women . for 29 years , gautama lived in bliss , protected from the smallest misfortunes of the outside world but then , he left the palace for short excursions . what he saw amazed him : first he met a sick man , then an aging man , and then a dying man . show these kind of people in india—add them to the same image one by one he was astounded to discover that these unfortunate people represented normal—indeed , inevitable—parts of the human condition that would one day touch him , too . horrified and fascinated , gautama made a fourth trip outside the palace walls—and encountered a holy man , who had learned to seek spiritual life in the midst of the vastness of human suffering . inspired by the holy man , gautama left the palace for good . he tried to learn from other holy men . he almost starved himself to death by avoiding all physical comforts and pleasures , as they did . perhaps unsurprisingly , it did not bring him solace from suffering . then he thought of a moment when he was a small boy : sitting by the river , he ’ d noticed that when the grass was cut , the insects and their eggs were trampled and destroyed . as a child , he ’ d felt a deep compassion for the tiny insects . reflecting on his childhood compassion , gautama felt a profound sense of peace . he ate , meditated , and finally reached the highest state of enlightenment : nirvana it refers to the “ blowing out ” of the flames of desire . with this , gautama had become the buddha , “ the awakened one ” . the buddha awoke by recognising that all of creation , from distraught ants to dying human beings , is unified by suffering . recognising this , the buddha discovered how to best approach suffering . first , one shouldn ’ t bathe in luxury , nor abstain from food and comforts altogether . instead , one ought to live in moderation . the buddha called this the middle way this allows for maximal concentration on cultivating compassion for others and seeking enlightenment next , the buddha described a path to transcending suffering called the four noble truths the first noble truth is the realisation that first prompted the buddha ’ s journey : that there is suffering and constant dissatisfaction in the world . the second is that this suffering is caused by our desires . as the buddha said , “ attachment is the root of all suffering. ” the third truth is that we can transcend suffering by removing or managing these desires . the buddha thus made the remarkable claim that we must change our outlook , not our circumstances . we are unhappy not because we don ’ t have enough money , love or status but because we are greedy , vain , and insecure . by re-orienting our mind we can grow to be content . the people become happier—superimpose smiles or use a second image of their face with the correct behaviour and what we now term a mindful attitude , we can also become better people . we can invert negative emotions and states of mind , turning ignorance into wisdom , anger into compassion , and greed into generosity . the fourth and final noble truth the buddha uncovered is that we can learn to move beyond suffering through what he termed the noble eightfold path . the eightfold path involves a series of aspects of behaving “ right ” and wisely : right view , right intention , right speech , right action , right livelihood , right effort , right mindfulness , and right concentration . what strikes the western observer is the notion that wisdom is a habit , not merely an intellectual realisation . one must exercise one ’ s nobler impulses on a regular basis , as one would train a limb . the moment of understanding is only one part of becoming a better person . after his death , the buddha ’ s followers collected his “ sutras ” ( sermons or sayings ) into scripture , and developed texts to guide followers in meditation , ethics , and mindful living . the monasteries that had developed during the buddha ’ s lifetime grew and multiplied , throughout china and east asia . for a time , buddhism was particularly uncommon in india itself , and only a few quiet groups of yellow-clad monks and nuns roamed the countryside , meditating quietly in nature . but then , in the 3rd century b.c. , an indian king named ashoka grew troubled by the wars he had fought and converted to buddhism . he sent monks and nuns far and wide to spread the practice . buddhist spiritual tradition spread across asia and eventually throughout the world . buddha ’ s followers divided into two main schools : theravada buddhism which colonised southeast asia , and mahayana buddhism which took hold in china and northeast asia . today , there are between a half and one and a half billion buddhists in both east and west following the buddha ’ s teachings and seeking a more enlightened and compassionate state of mind . intriguingly , the buddha ’ s teachings are important regardless of our spiritual identification . like the buddha , we are all born into the world not realising how much suffering it contains , and unable to fully comprehend that misfortune , sickness , and death will come to us too . as we grow older , this reality often feels overwhelming , and we may seek to avoid it altogether . but the buddha ’ s teachings remind us of the importance of facing suffering directly . we must do our best to liberate ourselves from the grip of our own desires , and recognise that suffering can be viewed as part of our common connection with others , spurring us to compassion and gentleness .
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the buddha awoke by recognising that all of creation , from distraught ants to dying human beings , is unified by suffering . recognising this , the buddha discovered how to best approach suffering . first , one shouldn ’ t bathe in luxury , nor abstain from food and comforts altogether .
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what does the word `` buddha '' mean ?
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translator : tom carter reviewer : bedirhan cinar ( zombie noises ) doctor 1 : so , here we are again . you know , i 've been thinking . why is this thing so angry ? doctor 2 : maybe he 's just hungry . d1 : ( laughs ) i 'm not going in there to feed it . no , this seems like something very primal . d2 : this is kind of a hard one , because we do n't really have any biological definitions for emotions like anger . sure , brain imaging studies have shown that some brain regions are more active when people are angry , but these are almost always correlational . when it 's warmer outside , people wear less clothing , but if i strip down to my birthday suit , it does n't make it sunny . d1 : ( laughs ) it 's like having someone run on a treadmill and saying `` look at how much more his arms move when he runs faster ! the arms must be where running happens . '' d2 : that 's why working with people with brain lesions is so important to neuroscience . it adds some causal evidence that a brain area might be required for a behavior . same with brain simulation studies . if stimulating a brain area causes a behavior , then that 's good evidence that the brain region is involved in that behavior . so like studies with cats in the 1950s showed that stimulating a small almond-shaped area deep in the brain called the amygdala leads to aggressive or predatory behaviors . these things look pretty aggressive to me . d1 : right . but other studies have shown that stimulating different parts of the amygdala can actually suppress predatory behaviors . so it 's kind of a complicated little brain structure . d2 : yeah . and fmri studies have found that the amygdala is active in violent criminals . d1 : whoa , whoa , whoa . careful there . just because criminals have the same active brain regions as people who are angry , does n't mean that they 're inherently aggressive . that 's like saying because i kiss with the same face hole that i use to burp , then these two things are related . it 's a false equivalence . d2 : huh ! never thought of it like that . that 's a good point . d1 : you know , the amygdala is part of the papez circuit . this system was discovered by james papez , who used the rabies virus to lesion different areas in the cat 's brain . he found that the amygdala was physically connected to another region called the hippocampus -- a little seahorse-shaped area that is needed to turn short-term memories into long-term memories . it 's thought that this connection between the amygdala and hippocampus links emotion and memory together , so that you remember really emotional stuff better than boring everyday things . d2 : yeah , like patient h.m . in the 1950s , surgeons removed both his left and right hippocampuses to treat his epilepsy . but after the surgery , he could n't remember any new information for longer than a few minutes . zombies appear to be pretty forgetful , would n't you agree ? d1 : ( laughs ) absolutely . between the amygdala-related aggression , and memory deficits from the hippocampus , papez may have actually accidentally created the first zombie cat . d2 : aw , come on now , let 's not get carried away . but now we do have some testable hypotheses . i 'd put money on its aggression and memory problems being linked to abnormalities in its amygdala and hippocampus , respectively . d1 : great ! so all we need to do now is figure out how to experimentally test this . do you think it 'll let us examine its brain to verify our hypothesis ? d2 : uh , you know , i think i might be more comfortable not knowing the answer to this one . d1 : hmm . maybe we could get a graduate student to do it for us ?
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it adds some causal evidence that a brain area might be required for a behavior . same with brain simulation studies . if stimulating a brain area causes a behavior , then that 's good evidence that the brain region is involved in that behavior .
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studies on patients with brain lesions are important for science because :
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you know , back in the '40s and '50s , the original standard television had a 4 to 3 width to height ratio . that shape was chosen to be a slight rectangle , but still mostly square , thus having the maximal screen area for the given dimensions . and that 's still the ratio on many tvs and computer monitors in today 's homes . the problem is , hardly anybody today treats video content in a 4 to 3 ratio . see , this whole problem started when people wanted to watch movies from the theater in the comfort of their own homes . movie screens are considerably larger than our home television . more important , the screen is completely different rectangle and ca n't mathematically fit on our tv screens without manipulation . a typical tv is one and a third times wider than it is tall some movie screens could be up to three times as wide as it is tall . so what 're we going to do to make it fit ? well , we have all kinds of options . well , we could squeeze and stretch and mangle everything onto the screen , to make it all fill up , and everyone would look ridiculously thin and compressed . the good news is the sound would be just fine , although i do n't think people would be too happy about that option , particularly the actors in the movie . we could just cut a chunk of the original movie like a cookie cutter and just see that frame of the movie . the problem with that would be people and objects would be speaking from off the screen , or , even worse , they might be cut in half . some movie editors use what 's called the `` pan and scan '' technique to allow the full height of the tv screen to be used , but pick and choose what section of the original movie should be shown on your screen thus eliminating the annoying cutting of people . imagine that job : staring at a 4 to 3 hole watching movies all day , deciding for everyone which piece of the screen is the most important part for people to see . now let 's do a little quick math . if we compare a major cinematic film produced on a 2.35 to 1 aspect frame with my standard 4 to 3 tv screen , we find out that only 55 % of the movie can actually fit on the screen at any one time . just over half ! you 've seen the disclaimer at the beginning of the movie on tv or dvd that says , `` this film has been modified from its original format to fit on your tv screen . '' well , what it should say is , `` we are only displaying 55 % of the movie of our choosing . '' now for all the full-screen tv lovers , this is your dilemma : do you want to see all the movie , or is 55 % good enough ? how about new tvs ? around the start of the century , some widescreen tvs emerged in a 16 to 9 , or 1.78 times wider than it is tall . well , this screen fits the movie a little better , but still only shows 75 % of the original movie at one time . suppose someone made a tv for your living room that was actually 2.35 to 1 to show those full movies ? well , the tv with the same height as the most current 50-inch tvs - that tv would be close to six feet long . and on top of that , you 'd only use the full screen when you watched movies . most of the other content would have to be stretched , or have empty space on the sides of the screen . of course , there is one more option . we can just shrink the movie screen proportionally , to fit the width of your home television . we can mathematically scale the original to fit exactly the width of the screen and this 'll preserve the entire movie screen , but show the infamous black bars along the top and bottom that so many television watchers abhor . of course , now you can argue that we 're only using 75 % of that screen . and that is where the real question is : do you want your full screen , or do you want to see the entire movie ? most likely , you just need a bigger tv .
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you know , back in the '40s and '50s , the original standard television had a 4 to 3 width to height ratio . that shape was chosen to be a slight rectangle , but still mostly square , thus having the maximal screen area for the given dimensions .
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in the 1940 's and 1950 's , the original standard television had a
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you can think of your cells as the kitchen in a busy restaurant . sometimes your body orders chicken . other times , it orders steak . your cells have to be able to crank out whatever the body needs and quickly . when an order comes in , the chef looks to the cookbook , your dna , for the recipe . she then transcribes that message onto a piece of paper called rna and brings it back to her countertop , the ribosome . there , she can translate the recipe into a meal , or for your cells , a protein , by following the directions that she 's copied down . but rna does more for the cell than just act as a messenger between a cook and her cookbook . it can move in reverse and create dna , it can direct amino acids to their targets , or it can take part in rna interference , or rnai . but wait ! why would rna want to interfere with itself ? well , sometimes a cell does n't want to turn all of the messenger rna it creates into protein , or it may need to destroy rna injected into the cell by an attacking virus . say , for example , in our cellular kitchen , that someone wanted to cancel their order or decided they wanted chips instead of fries . that 's where rnai comes in . thankfully , your cells have the perfect knives for just this kind of job . when the cell finds or produces long , double-stranded rna molecules , it chops these molecules up with a protein actually named dicer . now , these short snippets of rna are floating around in the cell , and they 're picked up by something called risc , the rna silencing complex . it 's composed of a few different proteins , the most important being slicer . this is another aptly named protein , and we 'll get to why in just a second . risc strips these small chunks of double-stranded rna in half , using the single strand to target matching mrna , looking for pieces that fit together like two halves of a sandwich . when it finds the matching piece of mrna , risc 's slicer protein slices it up . the cell then realizes there are odd , strangely sized pieces of rna floating around and destroys them , preventing the mrna from being turned into protein . so , you have double-stranded rna , you dice it up , it targets mrna , and then that gets sliced up , too . voila ! you 've prevented expression and saved yourself some unhappy diners . so , how did anybody ever figure this out ? well , the process was first discovered in petunias when botanists trying to create deep purple blooms introduced a pigment-producing gene into the flowers . but instead of darker flowers , they found flowers with white patches and no pigment at all . instead of using the rna produced by the new gene to create more pigment , the flowers were actually using it to knock down the pigment-producing pathway , destroying rna from the plant 's original genes with rnai , and leaving them with pigment-free white flowers . scientists saw a similar phenomena in tiny worms called c. elegans , and once they figured out what was happening , they realized they could use rnai to their advantage . want to see what happens when a certain gene is knocked out of a worm or a fly ? introduce an rnai construct for that gene , and bam ! no more protein expression . you can even get creative and target that effect to certain systems , knocking down genes in just the brain , or just the liver , or just the heart . figuring out what happens when you knock down a gene in a certain system can be an important step in figuring out what that gene does . but rnai is n't just for understanding how things happen . it can also be a powerful , therapeutic tool and could be a way for us to manipulate what is happening within own cells . researchers have been experimenting with using it to their advantage in medicine , including targeting rna and tumor cells in the hopes of turning off cancer-causing genes . in theory , our cellular kitchens could serve up an order of cells , hold the cancer .
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say , for example , in our cellular kitchen , that someone wanted to cancel their order or decided they wanted chips instead of fries . that 's where rnai comes in . thankfully , your cells have the perfect knives for just this kind of job .
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rnai could be used to :
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tens of millions of years ago , a force of nature set two giant masses on an unavoidable collision course that would change the face of the earth and spell life or death for thousands of species . the force of nature was plate tectonics , and the bodies were north and south america . and even though they were hurdling towards each other at an underwhelming 2.5 cm per year , their collision actually did have massive biological reprocussions by causing one of the greatest episodes of biological migration in earth 's history : the great american biotic interchange . our story begins 65 million years ago , the beginning of the age of mammals , when what is now north and south america were continents separated by a marine connection between the pacific and atlantic oceans . during this time , south america was the home of fauna that included armored glyptodonts as large as compact cars , giant ground sloths weighing more than a ton , opossums , monkeys , and carnivorous terror birds . north america had its own species , such as horses , bears , and saber-toothed cats . over 20 million years , the shifting of the farallon and caribbean plates produced the central america volcanic arc , a peninsula connected to north america , with only a very narrow seaway separating it from south america . as these plates continued to surf the earth 's magma layer far beneath the pacific ocean floor , the caribbean plate migrated eastward , and about 15 million years ago , south america finally collided with this central american arc . this gradually closed the water connection between the pacific and the caribbean , creating a land bridge , which connected north america to south america . terrestrial organisms could now cross between the two continents , and from the fossil records , it 's evident that different waves of their dispersals took place . even though plants do n't physically move , they are easily dispersed by wind and waves , so they migrated first , along with a few species of birds . they were followed by some freshwater fishes and amphibians , and finally , various mammals began to traverse the bridge . from south america , mammals like ground sloths and glyptodonts were widly distributed in north america . moreover , many south american tropical mammals , like monkeys and bats , colonized the forests of central america , and are very abundant today . south american predator marsupials went extinct 3 million years ago , at which point north american predators , such as cats , bears and foxes , migrated south and occupied the ecological space left behind . horses , llamas , tapirs , cougars , saber-toothed cats , gomphotheres , and later humans also headed south across the land bridge . but what happened on land is only half the story . what had been one giant ocean was now two , creating differences in temperature and salinity for the two bodies of water . the isthmus also became a barrier for many marine organisms , like mollusks , crustaceans , foraminifera , bryozoans , and fish , and separated the populations of many marine species . it also allowed the establishment of the thermohaline circulation , a global water conveyor belt , which transports warm water across the atlantic , and influences the climate of the east coast of north america , the west coast of europe , and many other areas . it 's a challenge to track all of the ways the collision of the americas changed the world , but it 's safe to say that the ripples of the great american biotic interchange have propagated through the history of life on the planet , and that of mankind . what if these species had n't gone extinct , or if there were no monkeys in central america , or jaguars in south america ? what if the thermohaline circulation was n't flowing ? would the east coast of north america be much colder ? it all goes to show some of the most impactful transformations of our planet are n't the explosive ones that happen in an instant , but the ones that crawl towards irreversible change . we are the product of history .
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they were followed by some freshwater fishes and amphibians , and finally , various mammals began to traverse the bridge . from south america , mammals like ground sloths and glyptodonts were widly distributed in north america . moreover , many south american tropical mammals , like monkeys and bats , colonized the forests of central america , and are very abundant today .
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when did the predatory marsupials become extinct in south america ?
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[ goproject films ] [ traffic sounds ] [ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] [ ♪ orchestral music ♪ ] i discovered working with tea really by accident . [ ♪ orchestral music ♪ ] i spilled the tea on a drawing . [ ♪ orchestral music ♪ ] i look at them , and i read them like somebody would read coffee beans . [ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] [ silent crescendo ] [ ♪ orchestral music ♪ ] a drink this beautiful of chinese pu-ehr tea . [ ♪ orchestral music ♪ ] the element of slowing down . [ ♪ orchestral music ♪ ] the tea allows us to breathe , to move . [ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] the whole things starts with big splashes of tea . [ ♪ orchestral music ♪ ] it 's like some empty space inside the mind . [ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] [ ♪ orchestral music ♪ ] i start with the pen , [ ♪ orchestral music ♪ ] and then i look at the markings . [ ♪ orchestral music ♪ ] it 's almost like a little oracle . i am not drawing it to be holy , to be out of this world . i just allow myself a little space , a little , a little moment . [ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] [ ♪ orchestral music continues ♪ ] there is no attempt to be original . originality 's totally irrelevant . if they look like something else , why not ? [ ♪ orchestral music ♪ ] there is some deep , internal intelligence . some almost non-verbal narrative which nourishes us , which has its own natural wellspring . and so these drawings try to , you know , touch the rim of that . [ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] [ ♪ orchestral music continues ♪ ] [ directed by emmanuel vaughan-lee ] [ produced by dorothée royal-hedinger ] [ filmed & amp ; amp ; edited by elias koch ] [ sound recording by emmanuel vaughan-lee ] [ music by h. scott salinas ] [ sound mix by d. chris smith ] [ www.globalonenessproject.org ]
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[ ♪ orchestral music ♪ ] [ ♪ orchestral music continues ♪ ] [ silent crescendo ] [ ♪ orchestral music ♪ ] a drink this beautiful of chinese pu-ehr tea . [ ♪ orchestral music ♪ ] the element of slowing down . [ ♪ orchestral music ♪ ] the tea allows us to breathe , to move .
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what is the significance of slowing down when slobodan creates his drawings ? what happens ?
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translator : andrea mcdonough reviewer : jessica ruby mysteries of vernacular : odd , different from what is usual or expected . though the modern word odd has many meanings , mathematical or not , they can all be traced back to the indo-european root uzdho , meaning pointing upwards . inspired by the idea of a vertical-pointed object , speakers of old norse modified this root into a new word , oddi , which was used to refer to a triangle , the simplest pointed object geometrically speaking . a triangle with a long point , like an arrow head or a piece of land jutting out into the sea , was recognized to have two paired angles and a third that stood alone . and over time , oddi began to refer to something that was n't matched or paired . in old norse , oddi also came to mean any number indivisible by two . and odda mathr , the odd man , was used to describe the unpaired man whose vote could break a tie . though the english never called a triangle odd , they did borrow the odd number and the odd man . and finally , in the 16th century , the notion of the odd man out gave rise to our modern meaning peculiar .
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and odda mathr , the odd man , was used to describe the unpaired man whose vote could break a tie . though the english never called a triangle odd , they did borrow the odd number and the odd man . and finally , in the 16th century , the notion of the odd man out gave rise to our modern meaning peculiar .
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is zero an even number or an odd number ?
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it 's a good day to be a pirate . amaro and his four mateys , bart , charlotte , daniel , and eliza have struck gold : a chest with 100 coins . but now , they must divvy up the booty according to the pirate code . as captain , amaro gets to propose how to distribute the coins . then , each pirate , including amaro himself , gets to vote either yarr or nay . if the vote passes , or if there 's a tie , the coins are divided according to plan . but if the majority votes nay , amaro must walk the plank and bart becomes captain . then , bart gets to propose a new distribution and all remaining pirates vote again . if his plan is rejected , he walks the plank , too , and charlotte takes his place . this process repeats , with the captain 's hat moving to daniel and then eliza until either a proposal is accepted or there 's only one pirate left . naturally , each pirate wants to stay alive while getting as much gold as possible . but being pirates , none of them trust each other , so they ca n't collaborate in advance . and being blood-thirsty pirates , if anyone thinks they 'll end up with the same amount of gold either way , they 'll vote to make the captain walk the plank just for fun . finally , each pirate is excellent at logical deduction and knows that the others are , too . what distribution should amaro propose to make sure he lives ? pause here if you want to figure it out for yourself ! answer in : 3 answer in : 2 answer in : 1 if we follow our intuition , it seems like amaro should try to bribe the other pirates with most of the gold to increase the chances of his plan being accepted . but it turns out he can do much better than that . why ? like we said , the pirates all know each other to be top-notch logicians . so when each votes , they wo n't just be thinking about the current proposal , but about all possible outcomes down the line . and because the rank order is known in advance , each can accurately predict how the others would vote in any situation and adjust their own votes accordingly . because eliza 's last , she has the most outcomes to consider , so let 's start by following her thought process . she 'd reason this out by working backwards from the last possible scenario with only her and daniel remaining . daniel would obviously propose to keep all the gold and eliza 's one vote would not be enough to override him , so eliza wants to avoid this situation at all costs . now we move to the previous decision point with three pirates left and charlotte making the proposal . everyone knows that if she 's outvoted , the decision moves to daniel , who will then get all the gold while eliza gets nothing . so to secure eliza 's vote , charlotte only needs to offer her slightly more than nothing , one coin . since this ensures her support , charlotte does n't need to offer daniel anything at all . what if there are four pirates ? as captain , bart would still only need one other vote for his plan to pass . he knows that daniel would n't want the decision to pass to charlotte , so he would offer daniel one coin for his support with nothing for charlotte or eliza . now we 're back at the initial vote with all five pirates standing . having considered all the other scenarios , amaro knows that if he goes overboard , the decision comes down to bart , which would be bad news for charlotte and eliza . so he offers them one coin each , keeping 98 for himself . bart and daniel vote nay , but charlotte and eliza grudgingly vote yarr knowing that the alternative would be worse for them . the pirate game involves some interesting concepts from game theory . one is the concept of common knowledge where each person is aware of what the others know and uses this to predict their reasoning . and the final distribution is an example of a nash equilibrium where each player knows every other players ' strategy and chooses theirs accordingly . even though it may lead to a worse outcome for everyone than cooperating would , no individual player can benefit by changing their strategy . so it looks like amaro gets to keep most of the gold , and the other pirates might need to find better ways to use those impressive logic skills , like revising this absurd pirate code .
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having considered all the other scenarios , amaro knows that if he goes overboard , the decision comes down to bart , which would be bad news for charlotte and eliza . so he offers them one coin each , keeping 98 for himself . bart and daniel vote nay , but charlotte and eliza grudgingly vote yarr knowing that the alternative would be worse for them .
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which of the following is not one of the conditions ?
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what 's the definition of comedy ? thinkers and philosophers from plato and aristotle to hobbes , freud , and beyond , including anyone misguided enough to try to explain a joke , have pondered it , and no one has settled it . you 're lucky you found this video to sort it out . to define comedy , you should first ask why it seems comedy defies definition . the answer 's simple . comedy is the defiance of definition because definitions sometimes need defiance . consider definition itself . when we define , we use language to set borders around a thing that we 've perceived in the whirling chaos of existence . we say what the thing means and fit that in a system of meanings . chaos becomes cosmos . the universe is translated into a cosmological construct of knowledge . and let 's be honest , we need some logical cosmic order , otherwise we 'd have pure chaos . chaos can be rough , so we build a thing that we call reality . now think about logic and logos , that tight knot connecting a word and truth . and let 's jump back to thinking about what 's funny , because some people say it 's real simple : truth is funny . it 's funny because it 's true . but that 's simplistic . plenty of lies are funny . comedic fiction can be funny . made-up nonsense jibberish is frequently hilarious . for instance , florp -- hysterical ! and plenty of truths are n't funny . two plus two truly equals four , but i 'm not laughing just because that 's the case . you can tell a true anecdote , but your date may not laugh . so , why are some untruths and only some truths funny ? how do these laughable truths and untruths relate to that capital-t truth , the cosmological reality of facts and definitions ? and what makes any of them funny ? there 's a frenchman who can help , another thinker who did n't define comedy because he expressly did n't want to . henri bergson 's a french philosopher who prefaced his essay on laughter by saying he would n't define `` the comic '' because it 's a living thing . he argued laughter has a social function to destroy mechanical inelasticity in people 's attitudes and behavior . someone doing the same thing over and over , or building up a false image of themself and the world , or not adapting to reality by just noticing the banana peel on the ground -- this is automatism , ignorance of one 's own mindless rigidity , and it 's dangerous but also laughable and comic ridicule helps correct it . the comic is a kinetic , vital force , or elan vital , that helps us adapt . bergson elaborates on this idea to study what 's funny about all sorts of things . but let 's stay on this . at the base of this concept of comedy is contradiction between vital , adaptive humanity and dehumanized automatism . a set system that claims to define reality might be one of those dehumanizing forces that comedy tends to destroy . now , let 's go back to aristotle . not poetics , where he drops a few thoughts on comedy , no , metaphysics , the fundamental law of non-contradiction , the bedrock of logic . contradictory statements are not at the same time true . if a is an axiomatic statement , it ca n't be the case that a and the opposite of a are both true . comedy seems to live here , to subsist on the illogic of logical contradiction and its derivatives . we laugh when the order we project on the world is disrupted and disproven , like when the way we all act contradicts truths we do n't like talking about , or when strange observations we all make in the silent darkness of private thought are dragged into public by a good stand-up , and when cats play piano , because cats that are also somehow humans disrupt our reality . so , we do n't just laugh at truth , we laugh at the pleasurable , edifying revelation of flaws , incongruities , overlaps , and outright conflicts in the supposedly ordered system of truths we use to define the world and ourselves . when we think too highly of our thinking , when we think things are true just because we all say they 're logos and stop adapting , we become the butt of jokes played on us by that wacky little trickster , chaos . comedy conveys that destructive , instructive playfulness , but has no logical definition because it acts upon our logic paralogically from outside its finite borders . far from having a definite definition , it has an infinite infinition . and the infinition of comedy is that anything can be mined for comedy . thus , all definitions of reality , especially those that claim to be universal , logical , cosmic , capital-t truth become laughable .
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now think about logic and logos , that tight knot connecting a word and truth . and let 's jump back to thinking about what 's funny , because some people say it 's real simple : truth is funny . it 's funny because it 's true .
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why do people want or need to define reality ? at what point does that tendency become funny ?
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it may sound like a paradox , or some cruel joke , but whatever it is , it 's true . beethoven , the composer of some of the most celebrated music in history , spent most of his career going deaf . so how was he still able to create such intricate and moving compositions ? the answer lies in the patterns hidden beneath the beautiful sounds . let 's take a look at the famous `` moonlight sonata , '' which opens with a slow , steady stream of notes grouped into triplets : one-and-a-two-and-a-three-and-a . but though they sound deceptively simple , each triplet contains an elegant melodic structure , revealing the fascinating relationship between music and math . beethoven once said , `` i always have a picture in my mind when composing and follow its lines . '' similarly , we can picture a standard piano octave consisting of thirteen keys , each separated by a half step . a standard major or minor scale uses eight of these keys , with five whole step intervals and two half step ones . and the first half of measure 50 , for example , consists of three notes in d major , separated by intervals called thirds , that skip over the next note in the scale . by stacking the scale 's first , third and fifth notes , d , f-sharp and a , we get a harmonic pattern known as a triad . but these are n't just arbitrary magic numbers . rather , they represent the mathematical relationship between the pitch frequencies of different notes which form a geometric series . if we begin with the note a3 at 220 hertz , the series can be expressed with this equation , where `` n '' corresponds to successive notes on the keyboard . the d major triplet from the moonlight sonata uses `` n '' values five , nine , and twelve . and by plugging these into the function , we can graph the sine wave for each note , allowing us to see the patterns that beethoven could not hear . when all three of the sine waves are graphed , they intersect at their starting point of 0,0 and again at 0,0.042 . within this span , the d goes through two full cycles , f-sharp through two and a half , and a goes through three . this pattern is known as consonance , which sounds naturally pleasant to our ears . but perhaps equally captivating is beethoven 's use of dissonance . take a look at measures 52 through 54 , which feature triplets containing the notes b and c. as their sine graphs show , the waves are largely out of sync , matching up rarely , if at all . and it is by contrasting this dissonance with the consonance of the d major triad in the preceding measures that beethoven adds the unquantifiable elements of emotion and creativity to the certainty of mathematics , creating what hector berlioz described as `` one of those poems that human language does not know how to qualify . '' so although we can investigate the underlying mathematical patterns of musical pieces , it is yet to be discovered why certain sequences of these patterns strike the hearts of listeners in certain ways . and beethoven 's true genius lay not only in his ability to see the patterns without hearing the music , but to feel their effect . as james sylvester wrote , `` may not music be described as the mathematics of the sense , mathematics as music of the reason ? '' the musician feels mathematics . the mathematician thinks music . music , the dream . mathematics , the working life .
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but these are n't just arbitrary magic numbers . rather , they represent the mathematical relationship between the pitch frequencies of different notes which form a geometric series . if we begin with the note a3 at 220 hertz , the series can be expressed with this equation , where `` n '' corresponds to successive notes on the keyboard .
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the frequency theories of ratios for consonance and dissonance do not always hold true . investigate the frequencies of notes that are 4 half-steps apart and make an 11:12 ratio . how does this produce a different outcome from the pattern in the video ?
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imagine the brain could reboot , updating its withered and damaged cells with new , improved units . that may sound like science fiction , but it 's a potential reality scientists are investigating right now . will our brains one day be able to self-repair ? it 's well known that embryonic cells in our young developing brains produce new neurons , the microscopic units that make up the brain 's tissue . those newly generated neurons migrate to various parts of the developing brain , making it self-organize into different structures . but until recently , scientists thought cell production came to an abrupt halt soon after this initial growth , leading them to conclude that neurological diseases , like alzheimer 's and parkinson 's , and damaging events , like strokes , are irreversible . but a series of recent discoveries has revealed that adult brains actually do continue to produce new cells in at least three specialized locations . this process , known as neurogenesis , involves dedicated brain cells , called neural stem cells and progenitor cells , which manufacture new neurons or replace the old ones . the three regions where neurogenesis has been discovered are the dentate gyrus , associated with learning and memory , the subventricular zone , which may supply neurons to the olfactory bulb for communication between the nose and brain , and the striatum , which helps manage movement . scientists do n't yet have a good grasp on exactly what role neurogenesis plays in any of these regions , or why they have this ability that 's absent from the rest of the brain , but the mere presence of a mechanism to grown new neurons in the adult brain opens up an amazing possibility . could we harness that mechanism to get the brain to heal its scars similar to how new skin grows to patch up a wound , or a broken bone stitches itself back together ? so here 's where we stand . certain proteins and other small molecules that mimick those proteins can be administered to the brain to make neural stem cells and progenitor cells produce more neurons in those three locations . this technique still needs improvement so that the cells reproduce more efficiently and more cells survive . but research shows that progenitor cells from these areas can actually migrate to places where injury has occurred and give rise to new neurons there . and another promising possible approach is to transplant healthy human neural stem cells , which are cultured in a laboratory , to injured tissue , like we can do with skin . scientists are currently experimenting to determine whether transplanted donor cells can divide , differentiate and successfully give rise to new neurons in a damaged brain . they 've also discovered that we might be able to teach other kinds of brain cells , such as astrocytes or oligodendrocytes to behave like neural stem cells and start generating neurons , too . so , a couple of decades from now will our brains be able to self-repair ? we ca n't say for sure , but that has become one of the major goals of regenerative medicine . the human brain has 100 billion neurons and we 're still figuring out the wiring behind this huge biological motherboard . but everyday , research on neurogenesis brings us closer to that reboot switch .
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will our brains one day be able to self-repair ? it 's well known that embryonic cells in our young developing brains produce new neurons , the microscopic units that make up the brain 's tissue . those newly generated neurons migrate to various parts of the developing brain , making it self-organize into different structures . but until recently , scientists thought cell production came to an abrupt halt soon after this initial growth , leading them to conclude that neurological diseases , like alzheimer 's and parkinson 's , and damaging events , like strokes , are irreversible .
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which of the following is not an area where new neurons are generated ?
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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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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 ? ''
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an equilateral triangle and a square both have a perimeter of 12 units . what is the area of both polygons ? do you think that the area of a regular hexagon would be greater than , less than , or in between the areas of the square and and triangle ? why ?
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studies have shown that taking vitamins is good for your health and bad for your health . that newly discovered herb can improve your memory or destroy your liver . headlines proclaim a promising new cancer treatment and never mention it again . on a daily basis , we are bombarded with attention-grabbing news , backed up by scientific studies , but what are these studies ? how are they performed ? and how do we know whether they 're reliable ? when it comes to dietary or medical information , the first thing to remember is that while studies on animals or individual cells can point the way towards further research , the only way to know how something will affect humans is through a study involving human subjects . and when it comes to human studies , the scientific gold standard is the randomized clinical trial , or rct . the key to rcts is that the subjects are randomly assigned to their study groups . they are often blinded to make them more rigorous . this process attempts to ensure that the only difference between the groups is the one the researchers are attempting to study . for example , when testing a new headache medication , a large pool of people with headaches would be randomly divided into two groups , one receiving the medication and another receiving a placebo . with proper randomization , the only significant overall difference between the two groups will be whether or not they received the medication , rather than other differences that could affect results . randomized clinical trials are incredible tools , and , in fact , the us food and drug administration often requires at least two to be conducted before a new drug can be marketed . but the problem is that an rct is not possible in many cases , either because it 's not practical or would require too many volunteers . in such cases , scientists use an epidemiological study , which simply observes people going about their usual behavior , rather than randomly assigning active participants to control invariable groups . let 's say we wanted to study whether an herbal ingredient on the market causes nausea . rather than deliberately giving people something that might make them nauseated , we would find those who already take the ingredient in their everyday lives . this group is called the cohort . we would also need a comparison group of people who do not have exposure to the ingredient . and we would then compare statistics . if the rate of nausea is higher in the herbal cohort , it suggests an association between the herbal supplement and nausea . epidemiological studies are great tools to study the health effects of almost anything , without directly interfering in people 's lives or assigning them to potentially dangerous exposures . so , why ca n't we rely on these studies to establish causal relationships between substances and their effects on health ? the problem is that even the best conducted epidemiological studies have inherent flaws . precisely because the test subjects are not randomly assigned to their groups . for example , if the cohort in our herbal study consisted of people who took the supplement for health reasons , they may have already had higher rates of nausea than the other people in the sample . or the cohort group could 've been composed of people who shop at health food stores and have different diets or better access to healthcare . these factors that can affect results , in addition to the factor being studied , are known as confounding variables . these two major pitfalls , combined with more general dangers , such as conflicts of interest or selective use of data , can make the findings of any particular epidemiological study suspect , and a good study must go out of its way to prove that its authors have taken steps to eliminate these types of errors . but even when this has been done , the very nature of epidemiological studies , which examine differences between preexisting groups , rather than deliberately inducing changes within the same individuals , means that a single study can only demonstrate a correlation between a substance and a health outcome , rather than a true cause and effect relationship . at the end of the day , epidemiological studies have served as excellent guides to public health , alerting us to critical health hazards , such as smoking , asbestos , lead , and many more . but these were demonstrated through multiple , well-conducted epidemiological studies , all pointing in the same direction . so , the next time you see a headline about a new miracle cure or the terrible danger posed by an everyday substance , try to learn more about the original study and the limitations inherent in any epidemiological study or clinical trial before jumping to conclusions .
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these two major pitfalls , combined with more general dangers , such as conflicts of interest or selective use of data , can make the findings of any particular epidemiological study suspect , and a good study must go out of its way to prove that its authors have taken steps to eliminate these types of errors . but even when this has been done , the very nature of epidemiological studies , which examine differences between preexisting groups , rather than deliberately inducing changes within the same individuals , means that a single study can only demonstrate a correlation between a substance and a health outcome , rather than a true cause and effect relationship . at the end of the day , epidemiological studies have served as excellent guides to public health , alerting us to critical health hazards , such as smoking , asbestos , lead , and many more .
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a single epidemiological or observational study can demonstrate cause and effect .
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you 'd have a hard time finding königsberg on any modern maps , but one particular quirk in its geography has made it one of the most famous cities in mathematics . the medieval german city lay on both sides of the pregel river . at the center were two large islands . the two islands were connected to each other and to the river banks by seven bridges . carl gottlieb ehler , a mathematician who later became the mayor of a nearby town , grew obsessed with these islands and bridges . he kept coming back to a single question : which route would allow someone to cross all seven bridges without crossing any of them more than once ? think about it for a moment . 7 6 5 4 3 2 1 give up ? you should . it 's not possible . but attempting to explain why led famous mathematician leonhard euler to invent a new field of mathematics . carl wrote to euler for help with the problem . euler first dismissed the question as having nothing to do with math . but the more he wrestled with it , the more it seemed there might be something there after all . the answer he came up with had to do with a type of geometry that did not quite exist yet , what he called the geometry of position , now known as graph theory . euler 's first insight was that the route taken between entering an island or a riverbank and leaving it did n't actually matter . thus , the map could be simplified with each of the four landmasses represented as a single point , what we now call a node , with lines , or edges , between them to represent the bridges . and this simplified graph allows us to easily count the degrees of each node . that 's the number of bridges each land mass touches . why do the degrees matter ? well , according to the rules of the challenge , once travelers arrive onto a landmass by one bridge , they would have to leave it via a different bridge . in other words , the bridges leading to and from each node on any route must occur in distinct pairs , meaning that the number of bridges touching each landmass visited must be even . the only possible exceptions would be the locations of the beginning and end of the walk . looking at the graph , it becomes apparent that all four nodes have an odd degree . so no matter which path is chosen , at some point , a bridge will have to be crossed twice . euler used this proof to formulate a general theory that applies to all graphs with two or more nodes . a eulerian path that visits each edge only once is only possible in one of two scenarios . the first is when there are exactly two nodes of odd degree , meaning all the rest are even . there , the starting point is one of the odd nodes , and the end point is the other . the second is when all the nodes are of even degree . then , the eulerian path will start and stop in the same location , which also makes it something called a eulerian circuit . so how might you create a eulerian path in königsberg ? it 's simple . just remove any one bridge . and it turns out , history created a eulerian path of its own . during world war ii , the soviet air force destroyed two of the city 's bridges , making a eulerian path easily possible . though , to be fair , that probably was n't their intention . these bombings pretty much wiped königsberg off the map , and it was later rebuilt as the russian city of kaliningrad . so while königsberg and her seven bridges may not be around anymore , they will be remembered throughout history by the seemingly trivial riddle which led to the emergence of a whole new field of mathematics .
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then , the eulerian path will start and stop in the same location , which also makes it something called a eulerian circuit . so how might you create a eulerian path in königsberg ? it 's simple .
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what was the name of the river that passed through königsberg ?
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translator : jennifer cody reviewer : jessica ruby when faced with a big challenge where potential failure seems to lurk at every corner , maybe you 've heard this advice before : `` be more confident . '' and most likely , this is what you think when you hear it : `` if only it were that simple . '' but what is confidence ? take the belief that you are valuable , worthwhile , and capable , also known as self-esteem , add in the optimism that comes when you are certain of your abilities , and then empowered by these , act courageously to face a challenge head-on . this is confidence . it turns thoughts into action . so where does confidence even come from ? there are several factors that impact confidence . one : what you 're born with , such as your genes , which will impact things like the balance of neurochemicals in your brain . two : how you 're treated . this includes the social pressures of your environment . and three : the part you have control over , the choices you make , the risks you take , and how you think about and respond to challenges and setbacks . it is n't possible to completely untangle these three factors , but the personal choices we make certainly play a major role in confidence development . so , by keeping in mind a few practical tips , we do actually have the power to cultivate our own confidence . tip 1 : a quick fix . there are a few tricks that can give you an immediate confidence boost in the short term . picture your success when you 're beginning a difficult task , something as simple as listening to music with deep bass ; it can promote feelings of power . you can even strike a powerful pose or give yourself a pep talk . tip two : believe in your ability to improve . if you 're looking for a long-term change , consider the way you think about your abilities and talents . do you think they are fixed at birth , or that they can be developed , like a muscle ? these beliefs matter because they can influence how you act when you 're faced with setbacks . if you have a fixed mindset , meaning that you think your talents are locked in place , you might give up , assuming you 've discovered something you 're not very good at . but if you have a growth mindset and think your abilities can improve , a challenge is an opportunity to learn and grow . neuroscience supports the growth mindset . the connections in your brain do get stronger and grow with study and practice . it also turns out , on average , people who have a growth mindset are more successful , getting better grades , and doing better in the face of challenges . tip three : practice failure . face it , you 're going to fail sometimes . everyone does . j.k. rowling was rejected by twelve different publishers before one picked up `` harry potter . '' the wright brothers built on history 's failed attempts at flight , including some of their own , before designing a successful airplane . studies show that those who fail regularly and keep trying anyway are better equipped to respond to challenges and setbacks in a constructive way . they learn how to try different strategies , ask others for advice , and perservere . so , think of a challenge you want to take on , realize it 's not going to be easy , accept that you 'll make mistakes , and be kind to yourself when you do . give yourself a pep talk , stand up , and go for it . the excitement you 'll feel knowing that whatever the result , you 'll have gained greater knowledge and understanding . this is confidence .
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but if you have a growth mindset and think your abilities can improve , a challenge is an opportunity to learn and grow . neuroscience supports the growth mindset . the connections in your brain do get stronger and grow with study and practice .
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this statement is an example of a `` fixed mindset '' :
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translator : andrea mcdonough reviewer : bedirhan cinar this might seem like a far-away place in a far-away land . my house is right there in the middle . this was 1992 l.a . riots . and i remember being 8 years old and looking out there and thinking to myself , `` this is it , this is game over . i 'm done . '' the military came in , the cops came in , and i thought they were going to save us , and for some reason they kept on pointing the guns at my people . so i grew up angry , i grew up mad . i struggled watching my parents pay rent at the end of the month . sometimes they had to take food out of their mouths so that we , my two younger sisters and i , could eat . and the people that i saw taking care of their family and taking care of business were the gang members . so i considered that as a career path , not because they were the ones that , you know , had the girls , had the cars , it was because they were the ones who took care of their families . and i love my family enough to even to consider that as a possibility . but it was n't always bad . if you have n't put two and two together , i 'm a dodgers fan . i like the dodgers even more so because dodgers stadium sits in the middle of the elysian park , one of the biggest parks in l.a. , and i remember going out on the weekends with my family and for la carne asada and sharing our cultura and them taking me on trails and showing me all this amazing stuff that they knew . i grew up , i went to dorsey high school . you might not know dorsey that much , but you might know crenshaw high school . crenshaw and dorsey are rival high schools , but they are more than just rivals in the traditional sense of rival high schools , they are the birth place of the bloods and the crips . so i was in 9th grade detention , and they gave me an ultimatum : they said , `` either you stay in detention , or you go to this thing called eco club . '' and i said , `` what ? ! ? eco club ? forget you ! '' but i took a chance and i went over to eco club . and the first thing that they said was , `` grab a bag of seeds and let 's go out . '' and i picked jalapeños because i wanted to grill salsa for my mom at the end of that . and they tricked me ! then all of a sudden , i started worrying about photosynthesis and the ph balance , and the uv radiation , and all this different stuff that would make my jalapeños grow . at the end of that semester , they gave me an opportunity to go to the teton science schools in wyoming . for a kid who has never been out of south central , to see mountains for the first time , to look up at the night sky and count , i could n't even count , the stars . for the first time in my life at the age of 15 i saw more stars than i could count . i had to pinch myself and look at that shooting star and say , `` no , that 's not the ghetto bird coming up at me . '' and the ghetto bird , you wo n't find in the audobon book , it 's a police helicopter in case you do n't know . and i went back home and i found mentors and friends and family and people who supported me in this , and in 2005 , this guy named richard louv wrote a book called < i > last child in the woods < /i > , and he coined a phrase called `` nature-deficit disorder '' . it 's not a medical term , do n't worry , you do n't have to take drugs for it , it 's an easy fix : all you have to do is get outside . because we have 7 billion people in the world today , but if you were to put all those 7 billion people shoulder-to-shoulder with each other , they could all fit in the city of l.a . it 's not necessarily that we are running out of space , it 's how we are using that space up . the average u.s. teenager now spends somewhere between 40 and 65 hours a week connected to some type of media device , some kind of technology . that 's a full-time job ! we 're not saying that its bad , we 're just saying get out , have fun ! and i got together with some friends and we created this thing called the `` natural leaders network '' . and we wanted to find out how other people are getting outside all over the world . we thought it was just us here in the u.s. , but no , no , it 's all over the world . and we started getting amazing things back : the beaches , the mountains , in the middle of the city , how people got out , just the pure joy of celebrating our connection with nature . and it all started with that one group . i want to give you this new motivation about a new nature movement , and 7 reasons for a new nature movement . you can create your own reasons , but these are 7 reasons that we 're talking about . i 'm going to speed up a little bit because of time . but , take it from these kids , let 's go get outside ! last year i got to climb the grand teton . i went from being that kid from south central realizing that somehow i was connected to those mountains , that my community in south central l.a. was connected to the mountains up there . and it all made sense , the world made sense to me . science , and math , and history , and english , and all the different things that were happening in this world made sense to me because of that . i went out to be the first one to graduate from my family in high school . i 'm the first one . i 'm a national geographic explorer today . i do these amazing talks , and i 'm not telling you these things so i can brag about it , or that i can show off , i 'm telling you these things because if a kid from south central who was about to be a gang member can grow up to be a national geographic explorer and sit here in front of you and address you like i am today , then do n't ever , ever in your life doubt what you can do . at the end of the day , i do what i do because of my family . my family means the world to me and from this day forward , each one of you in this room is part of that family . i want you go to away with that and i 'll leave it with this one quote , which has driven me to this point : `` once social change begins , it can not be reversed . you can not uneducate the person who has learned to read . you can not humiliate the person who feels pride . you can not oppress the people who are not afraid anymore . we have seen the future , and the future is ours . '' it 's your future , it 's our future , so go get 'em !
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at the end of that semester , they gave me an opportunity to go to the teton science schools in wyoming . for a kid who has never been out of south central , to see mountains for the first time , to look up at the night sky and count , i could n't even count , the stars . for the first time in my life at the age of 15 i saw more stars than i could count .
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where did martinez travel to see mountains for the first time ?
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you may have heard a lot about how dogs have an incredibly keen sense of smell , and it ’ s true . an average dog ’ s nose is anywhere between ten thousand to one hundred thousand times more sensitive that yours . so how can dogs with their super sense of smell be so interested in their k9 compatriot ’ s rear ends ? well folks , the answer is more complex and interesting thank you think . when a dog smells another dog ’ s butt , it ’ s actually collecting a bunch of information about the other dog – its diet , its gender , its emotional state and so on . think of it kind of like speaking with chemicals . in fact , this butt-sniffing action is just one of many examples of chemical communication in the animal kingdom . but what chemicals are packed in a fido ’ s rear end and where do they come from ? we talked to dr. george preti of the monell chemical senses center in philadelphia . dr. preti currently studies the complexity of human body odors and pheromones . but back in 1975 , he was on the cutting edge of dog butts science . he and his team of researchers examined the anal secretions of dogs and wild coyotes . so on both sides of sparky ’ s back door is a stinky , small pouch called an anal sac . this sac houses glands that excrete the chemicals dogs use to get to know each other . the apocrine gland is most responsible for that “ dog smell ” , but the sebaceous glands also play a part . petri discovered the primary chemical compounds that produce a dog ’ s aroma are trimethylamine and a host of short chain acids . as you might expect , anal sac secretions have a very powerful , sharp odor as a result of the acids inside . but a dog ’ s genetics , diet , and the current state of their immune system can all influence this aroma through chemical changes in the secretions . you ’ d think the smell of dog poop would overpower rover ’ s sensitive snout . but dogs have a second olfactory system in their hyper-sensitive nose called the jacobson ’ s organ . the organ is designed specifically for chemical communication . it has its own set of nerves that lead directly to the brain , so there ’ s absolutely no interference from other odors . the same organ is used when a dog sniffs a fire hydrant , or anywhere else there happens to be dog pee . so , there you have it folks . your precious pet isn ’ t obsessed with other dog ’ s butts per say . they ’ re just getting to know each other in a professional aromatic way . hey speaking of aroma , you should check out this video on why bacon smells so good , because bacon is to people , as butts are to dogs . thanks for watching folks , don ’ t forget to subscribe and we ’ ll see you again soon .
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you ’ d think the smell of dog poop would overpower rover ’ s sensitive snout . but dogs have a second olfactory system in their hyper-sensitive nose called the jacobson ’ s organ . the organ is designed specifically for chemical communication .
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what is the name of the second olfactory system at play in a dog 's nose ? what does it do ?
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translator : marcia de brito reviewer : ariana bleau lugo ( guitar music throughout ) music is a language . both music and verbal languages serve the same purpose . they are both forms of expression . they can be used as a way to communicate with others . they can be read and written . they can make you laugh or cry , think or question , and can speak to one or many . and both can definitely make you move . in some instances , music works better than the spoken word , because it does n't have to be understood to be effective . although many musicians agree that music is a language , it is rarely treated as such . many of us treat it as something that can only be learned by following a strict regimen , under the tutelage of a skilled teacher . this approach has been followed for hundreds of years with proven success , but it takes a long time . too long . think about the first language you learn as a child . more importantly , think about how you learned it . you were a baby when you first started speaking , and even though you spoke the language incorrectly you were allowed to make mistakes . and the more mistakes you made , the more your parents smiled . learning to speak was not something you were sent somewhere to do only a few times a week . and the majority of the people you spoke to were not beginners . they were already proficient speakers . imagine your parents forcing you to only speak to other babies until you were good enough to speak to them . you would probably be an adult before you could carry on a proper conversation . to use a musical term , as a baby , you were allowed to jam with professionals . if we approach music in the same natural way we approached our first language , we will learn to speak it in the same short time it took to speak our first language . proof of this could be seen in almost any family where a child grows up with other musicians in the family . here are a few keys to follow in learning or teaching music . in the beginning , embrace mistakes , instead of correcting them . like a child playing air guitar , there are no wrong notes . allow young musicians to play and perform with accomplished musicians on a daily basis . encourage young musicians to play more than they practice . the more they play the more they will practice on their own . music comes from the musician , not the instrument . and most importantly , remember that a language works best when we have something interesting to say . many music teachers never find out what their students have to say . we only tell them what they are supposed to say . a child speaks a language for years before they even learn the alphabet . too many rules at the onset , will actually slow them down . in my eyes , the approach to music should be the same . after all , music is a language too .
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although many musicians agree that music is a language , it is rarely treated as such . many of us treat it as something that can only be learned by following a strict regimen , under the tutelage of a skilled teacher . this approach has been followed for hundreds of years with proven success , but it takes a long time .
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what does wooten say about following a strict regiment under the tutelage of a skilled teacher ?
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we all know that there are certain virtues that are good for us . intelligence , wisdom , bravery , justice , respect , responsibility , honesty , unselfishness , compassion , patience , and perseverance always have been and always will be positive virtues . think of some people who have those traits . maybe it 's martin luther king or abraham lincoln or george washington . i bet you know a lot of facts about these historical figures , but maybe you 've never taken the time to think about their character . let 's talk about sybil ludington . she 's a little-known revolutionary figure , but boy , was she something ! she rode 40 miles through the damp , cold night of april 26 , 1777 to alert the colonial militia of a british attack . her action was similar to that of paul revere , only she rode twice as far and was only 16 years old . that takes some real guts ! beriah green ? anyone ever heard of beriah green ? he was president of the first integrated school in the united states . he also spent the majority of his life fighting for the immediate abolition of slavery . he used his voice , pen , and good deed to fight slavery . beriah green was fiercely devoted to abolition before it was popular because he believed it was the right thing to do . and then there 's abraham lincoln . you know he was president during the civil war . he wrote the emancipation proclaimation and is credited with freeing the slaves . he went to war with the south to save the union . he helped the country get through one of its most difficult times . he kept the united states united . but , above all that , abraham lincoln showed great leadership . could any of these people have done the deeds they 're famous for without bravery , compassion , dedication , or wisdom ? no ! history can teach us much more than just the facts . it 's full of examples of how to live better . and for you , even if you 're not freeing the slaves or riding 40 miles on horseback , bravery and wisdom will help you get an a on that test , ask out that cute boy , and get that great job .
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beriah green was fiercely devoted to abolition before it was popular because he believed it was the right thing to do . and then there 's abraham lincoln . you know he was president during the civil war .
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what virtue did president lincoln demonstrate by his ability keeping the union together ?
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if you wake up one morning with 1,000 times the strength you had the night before , how will you handle delicate day-to-day tasks ? everything must seem so fragile to you since the scale of your strength has expanded one thousand times . you 'd have to be very careful when you 're shaking someone 's hand so you do n't end up breaking their bones or crushing everyone you hug . and using a fork to pick up a piece of broccoli from a styrofoam plate without driving the fork through the plate is going to be as difficult as brain surgery . say the day comes and you get the chance to save a damsel in distress falling from a helicopter . so , you hold out your arms , hoping to catch her . seconds later , you will find yourself holding her lifeless body . what happened ? well , pressure is force divided by area . the smaller the area , the bigger the pressure . this is why we can lift heavy objects without breaking our skin , but a tiny needle can make us bleed with just a little poke . the pressure that will be exerted on her body can be calculated by force divided by the area on the top of your arms that comes in contact with her . it does n't matter if your arms are strong enough to catch her body without breaking your bones . her spine is not strong enough to be caught by you without being damaged . even if you rip off the nearest door to provide a bigger area to catch her with , you still would n't be able to save her anyway . remember , it 's not the fall that kills her , but the sudden stop at the bottom . let 's say she 's falling from a 32 story building , about 300 feet , and you are 6 feet tall , maybe 10 feet on your tippy-toes , with your arms above your head holding a door , in hopes of distributing the pressure across a larger surface area , but all you 're doing is essentially moving the ground up by 10 feet . so , she 's now falling from 290 feet , instead of 300 feet , reaching the speed of 173 feet per second just before impact , not counting air resistance . it 's the equivalent of crashing at 94 miles per hour into a wall with a door in front of it . the only thing that could save her is flying . but that power comes with its own host of scientific issues . if you could fly , what you must do is fly up to her , start flying down at the speed she is falling , hold on to her , then gradually slow down until you come to a complete stop . this process requires a lot of cushion space between the point she starts falling and the ground . every second you waste on changing into your superhero costume and flying up to her height , her head is getting that much closer to the pavement ! if she 's falling from a high place , and you ca n't get to her until she 's only a few feet above the ground , there 's really nothing you can do other than magically turn the pavement into marshmellow to allow her enough time to slowly come to a stop . then , break out the chocolate and graham crackers and you 've got s'mores . mmmm , delicious ! now , which superpower physics lesson will you explore next ? shifting body size and content , super speed , flight , super strength , immortality , and invisibility .
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remember , it 's not the fall that kills her , but the sudden stop at the bottom . let 's say she 's falling from a 32 story building , about 300 feet , and you are 6 feet tall , maybe 10 feet on your tippy-toes , with your arms above your head holding a door , in hopes of distributing the pressure across a larger surface area , but all you 're doing is essentially moving the ground up by 10 feet . so , she 's now falling from 290 feet , instead of 300 feet , reaching the speed of 173 feet per second just before impact , not counting air resistance .
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if a superhero catches a girl falling from a 30-story building , what scenario would most likely take place ?
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hmmm , that 's not what we want , is it ? today 's digital cameras do a lot for us , but there 's no replacement for the human eye . it 's important to learn how cameras work with light to create an image , that way we 'll know what 's going on when it 's time to capture a moment . there are three variables that determine if you 're getting the right amount of light for the correct exposure . with a manual camera , we 're able to change any of the variable ourselves . different settings can result in really different pictures . let 's look at the process together . first , see this here ? this is the aperture . it 's the hole that light passes through . if we make the aperture big , we 'll have more light , true , but the sharpness of your photo will decrease very quickly from your focus point , backward and forward . this is what we call shallow depth of field . if we have a very small aperture , we 'll have less light but a deeper depth of field . for portraits , it can be nice to have a sharp figure separate from a somewhat blurry background so i would suggest a large aperture . aperture is measured in f-stops . this can get a little confusing because lower numbers mean bigger apertures and higher numbers mean smaller apertures . next , there 's shutter speed to think about . the shutter acts like a curtain that covers the sensor , and it only opens when you release the shutter button . if we want less light , we open the shutter for a shorter time . if we want more light , we open it for a longer time , but we run the risk of getting a motion-blurred picture . the speed is measured in seconds and fractions of seconds . for shooting sports or anything with a lot of movement , we 'll need faster speeds . for taking awesome night landscapes , longer exposures will be better , but we 'll need a tripod to steady the shot and prevent motion blur . another cool thing we can do with light exposures is light painting , drawing in the dark with a torch or the light of a cell phone . lastly , iso sensitivity controls how sensitive the sensor is to light . if we use low sensitivity , we 'll need more light to register a photo . with a higher sensitivity , we 'll be able to get a picture with less available light . 100 iso is a low sensitivity , while 6400 iso is a high one . if we increase sensitivity , we 'll be able to use faster speeds and smaller apertures , but we 'll get noisier images . good thing we have something to tell us if we 're getting the correct amount of light to get a good exposure , the light meter . sound good to you ? now it 's time to get out there and practice taking pictures under different conditions , so you know what to do any time you want to take the best picture .
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for portraits , it can be nice to have a sharp figure separate from a somewhat blurry background so i would suggest a large aperture . aperture is measured in f-stops . this can get a little confusing because lower numbers mean bigger apertures and higher numbers mean smaller apertures .
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the aperture is measured in
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what if william shakespeare had a sister who matched his imagination , his wit , and his way with words ? would she have gone to school and set the stage alight ? in her essay `` a room of one 's own , '' virginia woolf argues that this would have been impossible . she concocts a fictional sister who 's stuck at home , snatching time to scribble a few pages before she finds herself betrothed and runs away . while her brother finds fame and fortune , she remains abandoned and anonymous . in this thought experiment , woolf demonstrates the tragedy of genius restricted , and looks back through time for hints of these hidden histories . she wrote , `` when one reads of a witch being ducked , of a woman possessed by devils , of a wise woman selling herbs , or even a very remarkable man who had a mother , then i think we 're on the track of a lost novelist , a suppressed poet , of some mute and inglorious jane austen . '' `` a room of one 's own '' considers a world denied great works of art due to exclusion and inequality . how best can we understand the internal experience of alienation ? in both her essays and fiction , virginia woolf shapes the slippery nature of subjective experience into words . her characters frequently lead inner lives that are deeply at odds with their external existence . to help make sense of these disparities , the next time you read woolf , here are some aspects of her life and work to consider . she was born adeline virginia stephen in 1882 to a large and wealthy family , which enabled her to pursue a life in the arts . the death of her mother in 1895 was followed by that of her half-sister , father , and brother within the next ten years . these losses led to woolf 's first depressive episode and subsequent institutionalization . as a young woman , she purchased a house in the bloomsbury area of london with her siblings . this brought her into contact with a circle of creatives , including e.m. forster , clive bell , roger fry , and leonard woolf . these friends became known as the bloomsbury group , and virginia and leonard married in 1912 . the members of this group were prominent figures in modernism , a cultural movement that sought to push the boundaries of how reality is represented . key features of modernist writing include the use of stream of consciousness , interior monologue , distortions in time , and multiple or shifting perspectives . these appear in the work of ezra pound , gertrude stein , james joyce , and woolf herself . while reading joyce 's `` ulysses , '' woolf began writing `` mrs . dalloway . '' like `` ulysses , '' the text takes place over the course of a single day and opens under seemingly mundane circumstances . `` mrs. dalloway said she would buy the flowers herself . '' but the novel dives deeply into the characters ' traumatic pasts , weaving the inner world of numbed socialite clarissa dalloway , with that of the shell-shocked veteran septimus warren smith . woolf uses interior monologue to contrast the rich world of the mind against her characters ' external existences . in her novel `` to the lighthouse , '' mundane moments , like a dinner party , or losing a necklace trigger psychological revelations in the lives of the ramsay 's , a fictionalized version of woolf 's family growing up . `` to the lighthouse '' also contains one of the most famous examples of woolf 's radical representation of time . in the time passes section , ten years are distilled into about 20 pages . here , the lack of human presence in the ramsays ' beach house allows woolf to reimagine time in flashes and fragments of prose . `` the house was left . the house was deserted . it was left like a shell on a sand hill to fill with dry salt grains now that life had left it . '' in her novel `` the waves , '' there is little distinction between the narratives of the six main characters . woolf experiments with collective consciousness , at times collapsing the six voices into one . `` it is not one life that i look back upon : i am not one person : i am many people : i do not altogether know who i am , jinny , susan , neville , rhoda or louis , or how to distinguish my life from their 's . '' in `` the waves , '' six become one , but in the gender-bending `` orlando , '' a single character inhabits multiple identities . the protagonist is a poet who switches between genders and lives for 300 years . with its fluid language and approach to identity , `` orlando '' is considered a key text in gender studies . the mind can only fly so far from the body before it returns to the constraints of life . like many of her characters , woolf 's life ended in tragedy when she drowned herself at the age of 59 . yet , she expressed hope beyond suffering . through deep thought , woolf 's characters are shown to temporarily transcend their material reality , and in its careful consideration of the complexity of the mind , her work charts the importance of making our inner lives known to each other .
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would she have gone to school and set the stage alight ? in her essay `` a room of one 's own , '' virginia woolf argues that this would have been impossible . she concocts a fictional sister who 's stuck at home , snatching time to scribble a few pages before she finds herself betrothed and runs away .
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`` a room of one ’ s own '' argues that :
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i must look rather strange to you , all covered in spines , without even a face . but i 've taken many forms during my life . i started out just like you : a tiny egg in a watery world . my parents never knew each other . one moonlit night before a storm , thousands of urchins , clams and corals released trillions of sperm and eggs into the open sea . my father 's sperm somehow met my mother 's egg , and they fused . fertilization . instantly , i became an embryo the size of a speck of dust . after a few hours of drifting , i cleaved in two , then four , then eight cells . then so many , i lost count . in less than a day , i developed a gut and a skeleton . i became a rocket ship , a pluteus larva . i floated through the world of plankton , searching for tiny algae to eat . for weeks , i was surrounded by all kinds of organisms , larvae of all sorts . most are so different from their adult form that biologists have a tough time figuring out who they are . try matching these youngsters to their parents . this veliger larvae will turn into a snail ; this zoea , into a crab ; and this planula , into a clytia jelly . some of my young companions are easier to picture as grown-ups . these baby jellies , known as ephyrae , already resemble their beautiful but deadly parents . here in the plankton , there 's more than one way to get your genes into the next generation . most medusa jellies make special structures called polyps , that simply bud off babies with no need for sex . salps are similar . when food is abundant , they just clone themselves into long chains . the plankton is full of surprises when it comes to sex . meet the hermaphrodites . these comb jellies and arrow worms produce , store and release both sperm and eggs . they can fertilize themselves , or another . when you 're floating in a vast sea , with little control over who you may meet , it can pay to play both sides of the field . the majority of species here , however , never mate , nor form any sort of lasting bonds . that was my parents ' strategy . there were so many of us pluteus larvae , i just hid in the crowd , while most of my kin were devoured . not all parents leave the survival of their offspring to chance . some have far fewer young and take much better care of them , brooding their precious cargo for days , even months . this speedy copepod totes her beautifully packaged eggs for days . this phronima crustacean carries her babies on her chest , then carefully places them in a gelatinous barrel . but the black-eyed squid takes the prize . she cradles her eggs in long arms for nine months , the same time it takes to gestate a human infant . eventually , all youngsters have to make it on their own in this drifting world . some will spend their whole lives in the plankton , but others , like me , move on . a few weeks after i was conceived , i decided to settle down , and metamorphosed into a recognizable urchin . so now you know a bit of my story . i may just be a slow-moving ball of spines , but do n't let my calm adult exterior fool you . i was a rocket ship . i was a wild child .
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here in the plankton , there 's more than one way to get your genes into the next generation . most medusa jellies make special structures called polyps , that simply bud off babies with no need for sex . salps are similar .
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what do you think are the benefits and disadvantages of the varying reproductive habits of medusa jellies , salps and comb jellies ?
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