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in 1861 , two scientists got into a very brainy argument . specifically , they had opposing ideas of how speech and memory operated within the human brain . ernest aubertin , with his localistic model , argued that a particular region or the brain was devoted to each separate process . pierre gratiolet , on the other hand , argued for the distributed model , where different regions work together to accomplish all of these various functions . the debate they began reverberated throughout the rest of the century , involving some of the greatest scientific minds of the time . aubertin and his localistic model had some big names on his side . in the 17th century , rené descartes had assigned the quality of free will and the human soul to the pineal gland . and in the late 18th century , a young student named franz joseph gall had observed that the best memorizers in his class had the most prominent eyes and decided that this was due to higher development in the adjacent part of the brain . as a physician , gall went on to establish the study of phrenology , which held that strong mental faculties corresponded to highly developed brain regions , observable as bumps in the skull . the widespread popularity of phrenology throughout the early 19th century tipped the scales towards aubertin 's localism . but the problem was that gall had never bothered to scientifically test whether the individual brain maps he had constructed applied to all people . and in the 1840 's , pierre flourens challenged phrenology by selectively destroying parts of animal brains and observing which functions were lost . flourens found that damaging the cortex interfered with judgement or movement in general , but failed to identify any region associated with one specific function , concluding that the cortex carried out brain functions as an entire unit . flourens had scored a victory for gratiolet , but it was not to last . gall 's former student , jean-baptiste bouillaud , challenged flourens ' conclusion , observing that patients with speech disorders all had damage to the frontal lobe . and after paul broca 's 1861 autopsy of a patient who had lost the power to produce speech , but not the power to understand it , revealed highly localized frontal lobe damage , the distributed model seemed doomed . localism took off . in the 1870 's , karl wernicke associated part of the left temporal lobe with speech comprehension . soon after , eduard hitzig and gustav fritsch stimulated a dog 's cortex and discovered a frontal lobe region responsible for muscular movements . building on their work , david ferrier mapped each piece of cortex associated with moving a part of the body . and in 1909 , korbinian brodmann built his own cortex map with 52 separate areas . it appeared that the victory of aubertin 's localistic model was sealed . but neurologist karl wernicke had come up with an interesting idea . he reasoned that since the regions for speech production and comprehension were not adjacent , then injuring the area connecting them might result in a special type of language loss , now known as receptive aphasia . wernicke 's connectionist model helped explain disorders that did n't result from the dysfunction of just one area . modern neuroscience tools reveal a brain more complex than gratiolet , aubertin , or even wernicke imagined . today , the hippocampus is associated with two distinct brain functions : creating memories and processing location in space . we also now measure two kinds of connectivity : anatomical connectivity between two adjoining regions of cortex working together , and functional connectivity between separated regions working together to accomplish one process . a seemingly basic function like vision is actually composed of many smaller functions , with different parts of the cortex representing shape , color and location in space . when certain areas stop functioning , we may recognize an object , but not see it , or vice versa . there are even different kinds of memory for facts and for routines . and remembering something like your first bicycle involves a network of different regions each representing the concept of vehicles , the bicycle 's shape , the sound of the bell , and the emotions associated with that memory . in the end , both gratiolet and aubertin turned out to be right . and we still use both of their models to understand how cognition happens . for example , we can now measure brain activity on such a fine time scale that we can see the individual localized processes that comprise a single act of remembering . but it is the integration of these different processes and regions that creates the coherent memory we experience . the supposedly competing theories prove to be two aspects of a more comprehensive model , which will in turn be revised and refined as our scientific techologies and methods for understanding the brain improve .
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a seemingly basic function like vision is actually composed of many smaller functions , with different parts of the cortex representing shape , color and location in space . when certain areas stop functioning , we may recognize an object , but not see it , or vice versa . there are even different kinds of memory for facts and for routines .
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if you damaged large areas of an animals brain but they were still able to see and learn , what could you conclude ?
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o polônio foi outro elemento descoberto por madame curie , a madame curie ela polonesa , mas fez boa parte da pesquisa , se não toda , em paris . polônio é um nome por causa da polônia polônio é um elemento que tem sido não muito importante , até a invenção da bomba atômica , e o polônio tornou-se um material absolutamente crucial pq é usado , ou foi usado , como um gatilho no centro da bomba atômica original . uma das dificuldades é que tem uma meia-vida muito curta . se vc tem um pedaço de polônio , metade dele decai em 138 dias se vc mantém por muito tempo , ele se vai , ou quase todo se vai , e portanto , no início da produção de bombas atômicas , das de hiroshima e nagasaki , o fator limitante na produção de bombas era a produção de polônio para o gatilho . em vez do enriquecimento de urânio ou plutônio , que eram usados para as bombas . bem recentemente o polônio teve uma nova notoriedade , pq foi usado neste caso trágico de envenenamento . no qual uma grande dose de polônio foi dado a um infeliz cidadão russo , que visitava a inglaterra . e ainda não está claro de onde veio o polônio . mas é um material bem pouco comum . e difícil para alguém comum encontrar . se for ingerido , pq decai muito rápido , a radioatividade pode causar todo tipo de efeitos desagradáveis . e , novamente , é provavelmente venenoso ele mesmo . traduzido por prof. dr. luís brudna
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o polônio foi outro elemento descoberto por madame curie , a madame curie ela polonesa , mas fez boa parte da pesquisa , se não toda , em paris . polônio é um nome por causa da polônia polônio é um elemento que tem sido não muito importante , até a invenção da bomba atômica , e o polônio tornou-se um material absolutamente crucial pq é usado , ou foi usado , como um gatilho no centro da bomba atômica original .
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where was madame curie born ?
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one , two , three , four , five , six , seven , eight , nine , and zero . with just these ten symbols , we can write any rational number imaginable . but why these particular symbols ? why ten of them ? and why do we arrange them the way we do ? numbers have been a fact of life throughout recorded history . early humans likely counted animals in a flock or members in a tribe using body parts or tally marks . but as the complexity of life increased , along with the number of things to count , these methods were no longer sufficient . so as they developed , different civilizations came up with ways of recording higher numbers . many of these systems , like greek , hebrew , and egyptian numerals , were just extensions of tally marks with new symbols added to represent larger magnitudes of value . each symbol was repeated as many times as necessary and all were added together . roman numerals added another twist . if a numeral appeared before one with a higher value , it would be subtracted rather than added . but even with this innovation , it was still a cumbersome method for writing large numbers . the way to a more useful and elegant system lay in something called positional notation . previous number systems needed to draw many symbols repeatedly and invent a new symbol for each larger magnitude . but a positional system could reuse the same symbols , assigning them different values based on their position in the sequence . several civilizations developed positional notation independently , including the babylonians , the ancient chinese , and the aztecs . by the 8th century , indian mathematicians had perfected such a system and over the next several centuries , arab merchants , scholars , and conquerors began to spread it into europe . this was a decimal , or base ten , system , which could represent any number using only ten unique glyphs . the positions of these symbols indicate different powers of ten , starting on the right and increasing as we move left . for example , the number 316 reads as 6x10^0 plus 1x10^1 plus 3x10^2 . a key breakthrough of this system , which was also independently developed by the mayans , was the number zero . older positional notation systems that lacked this symbol would leave a blank in its place , making it hard to distinguish between 63 and 603 , or 12 and 120 . the understanding of zero as both a value and a placeholder made for reliable and consistent notation . of course , it 's possible to use any ten symbols to represent the numerals zero through nine . for a long time , the glyphs varied regionally . most scholars agree that our current digits evolved from those used in the north african maghreb region of the arab empire . and by the 15th century , what we now know as the hindu-arabic numeral system had replaced roman numerals in everyday life to become the most commonly used number system in the world . so why did the hindu-arabic system , along with so many others , use base ten ? the most likely answer is the simplest . that also explains why the aztecs used a base 20 , or vigesimal system . but other bases are possible , too . babylonian numerals were sexigesimal , or base 60 . any many people think that a base 12 , or duodecimal system , would be a good idea . like 60 , 12 is a highly composite number that can be divided by two , three , four , and six , making it much better for representing common fractions . in fact , both systems appear in our everyday lives , from how we measure degrees and time , to common measurements , like a dozen or a gross . and , of course , the base two , or binary system , is used in all of our digital devices , though programmers also use base eight and base 16 for more compact notation . so the next time you use a large number , think of the massive quantity captured in just these few symbols , and see if you can come up with a different way to represent it .
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but as the complexity of life increased , along with the number of things to count , these methods were no longer sufficient . so as they developed , different civilizations came up with ways of recording higher numbers . many of these systems , like greek , hebrew , and egyptian numerals , were just extensions of tally marks with new symbols added to represent larger magnitudes of value .
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what did different civilizations use to record larger quantities ?
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a handful of species on earth share a seemingly mysterious trait : a menstrual cycle . we 're one of the select few . monkeys , apes , bats , humans , and possibly elephant shrews are the only mammals on earth that menstruate . we also do it more than any other animal , even though its a waste of nutrients and can be a physical inconvenience . so where 's the sense in this uncommon biological process ? the answer begins with pregnancy . during this process , the body 's resources are cleverly used to shape a suitable environment for a fetus , creating an internal haven for a mother to nurture her growing child . in this respect , pregnancy is awe-inspiring , but that 's only half the story . the other half reveals that pregnancy places a mother and her child at odds . as for all living creatures , the human body evolved to promote the spread of its genes . for the mother , that means she should try to provide equally for all her offspring . but a mother and her fetus do n't share exactly the same genes . the fetus inherits genes from its father , as well , and those genes can promote their own survival by extracting more than their fair share of resources from the mother . this evolutionary conflict of interests places a woman and her unborn child in a biological tug-of-war that plays out inside the womb . one factor contributing to this internal tussle is the placenta , the fetal organ that connects to the mother 's blood supply and nourishes the fetus while it grows . in most mammals , the placenta is confined behind a barrier of maternal cells . this barrier lets the mother control the supply of nutrients to the fetus . but in humans and a few other species , the placenta actually penetrates right into the mother 's circulatory system to directly access her blood stream . through its placenta , the fetus pumps the mother 's arteries with hormones that keep them open to provide a permanent flow of nutrient-rich blood . a fetus with such unrestricted access can manufacture hormones to increase the mother 's blood sugar , dilate her arteries , and inflate her blood pressure . most mammal mothers can expel or reabsorb embryos if required , but in humans , once the fetus is connected to the blood supply , severing that connection can result in hemorrhage . if the fetus develops poorly or dies , the mother 's health is endangered . as it grows , a fetus 's ongoing need for resources can cause intense fatigue , high blood pressure , and conditions like diabetes and preeclampsia . because of these risks , pregnancy is always a huge , and sometimes dangerous , investment . so it makes sense that the body should screen embryos carefully to find out which ones are worth the challenge . this is where menstruation fits in . pregnancy starts with a process called implantation , where the embryo embeds itself in the endometrium that lines the uterus . the endometrium evolved to make implantation difficult so that only the healthy embryos could survive . but in doing so , it also selected for the most vigorously invasive embryos , creating an evolutionary feedback loop . the embryo engages in a complex , exquisitely timed hormonal dialogue that transforms the endometrium to allow implantation . what happens when an embryo fails the test ? it might still manage to attach , or even get partly through the endometrium . as it slowly dies , it could leave its mother vulnerable to infection , and all the time , it may be emitting hormonal signals that disrupt her tissues . the body avoids this problem by simply removing every possible risk . each time ovulation does n't result in a healthy pregnancy , the womb gets rid of its endometrial lining , along with any unfertilized eggs , sick , dying , or dead embryos . that protective process is known as menstruation , leading to the period . this biological trait , bizarre as it may be , sets us on course for the continuation of the human race .
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this barrier lets the mother control the supply of nutrients to the fetus . but in humans and a few other species , the placenta actually penetrates right into the mother 's circulatory system to directly access her blood stream . through its placenta , the fetus pumps the mother 's arteries with hormones that keep them open to provide a permanent flow of nutrient-rich blood .
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which body system does the placenta penetrate ?
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is there a disease that makes us love cats , and do you have it ? maybe , and it 's more likely than you 'd think . we 're talking about toxoplasmosis , a disease caused by toxoplasma gondii . like all parasites , toxoplasma lives at the expense of its host , and needs its host to produce offspring . to do that , toxo orchestrates a brain manipulation scheme involving cats , their rodent prey , and virtually all other birds and mammals , including humans . documented human infections go as far back as ancient egypt . we found samples in mummies . today , about a third of the world 's population is infected , and most of them never even know it . in healthy people , symptoms often do n't show up at all . when they do , they 're mild and flu-like . but those are just the physical symptoms . toxoplasma also nestles into our brains and meddles with our behavior behind the scenes . to understand why , let 's take a look at the parasite 's life cycle . while the parasite can multiply in practically any host , it can only reproduce sexually in the intestines of cats . the offspring , called oocysts , are shed in the cat 's feces . a single cat can shed up to a hundred million oocysts . if another animal , like a mouse , accidentally ingests them , they 'll invade the mouse 's tissues and mature to form tissue cysts . if the mouse gets eaten by a cat , the tissue cysts become active and release offspring that mate to form new oocysts , completing the cycle . but there 's a problem . a mouse 's natural desire to avoid a cat makes it tough to close this loop . toxoplasma has a solution for that . the parasites invade white blood cells to hitch a ride to the brain where they seem to override the innate fear of predators . infected rodents are more reckless and have slower reaction times . strangest of all , they 're actually attracted to feline urine , which probably makes them more likely to cross paths with a cat and help the parasite complete its life cycle . how does the parasite pull this off ? although the exact mechanism is n't known , toxo appears to increase dopamine , a brain neurotransmitter that is involved in novelty-seeking behavior . thus , one idea is that toxo tinkers with neurotransmitters , the chemical signals that modulate emotions . the result ? fatal attraction . but mice are n't the only animals that end up with these parasites , and that 's where humans , and all of toxo 's other hosts , come in . we can accidentally ingest oocysts in contaminated water , or unwashed produce , or from playing in sandboxes , or cleaning out litter boxes . this is behind the common recommendation that pregnant women not change cat litter . toxo can cause serious birth defects . we can also get toxo from eating undercooked meat from other animals that picked up some oocysts . and it turns out that toxo can mess with our brains , too . studies have found connections between toxo and schizophrenia , biopolar disorder , obsessive compulsive disorder , and aggression . it also slows reactions and decreases concentration , which may be why one study found that people involved in traffic accidents were almost three times more likely to have toxoplasma . so is toxo manipulating our brains as an evolutionary strategy to get predatory cats to eat us ? or are our brains just similar enough to a rodent 's that the same neurological tricks that lure them in catch us in the net , too ? and is toxo the reason so many people love cats and keep them as pets ? well , the jury 's still out on that one . some recent studies even contradict the idea . regardless , toxoplasma has definitely benefited from humans to become one of the world 's most successful parasites . it 's not just our willingness to let cats on our dining room tables or in our beds . raising livestock and building cities which attract rodents has provided billions of new hosts , and you and your cat may be two of them .
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a mouse 's natural desire to avoid a cat makes it tough to close this loop . toxoplasma has a solution for that . the parasites invade white blood cells to hitch a ride to the brain where they seem to override the innate fear of predators .
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which of the following are not symptoms of infection with toxoplasma ?
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in 1978 , louise brown became the world 's first baby to be born by in vitro fertilization , or ivf . her birth revolutionized the field of reproductive medicine . given that approximately one in eight heterosexual couples has difficulty conceiving , and that homosexual couples and single parents often need clinical help to make a baby , the demand for ivf has been growing . ivf is so common , that more than 5 million babies have been born through this technology . ivf works by mimicking the brilliant design of sexual reproduction . in order to understand ivf , we first need to take a look at the natural process of baby making . believe it or not , it all starts in the brain . roughly fifteen days before fertilization can happen , the anterior pituitary gland secretes follicle stimulating hormone , fsh , which ripens a handful of follicles of the ovary that then release estrogen . each follicle contains one egg , and on average , only one follicle becomes fully mature . as it grows and continues to release estrogen , this hormone not only helps coordinate growth and preparation of the uterus , it also communicates to the brain how well the follicle is developing . when the estrogen level is high enough , the anterior pituitary releases a surge of luteinizing hormone , lh , which triggers ovulation and causes the follicle to rupture and release the egg . once the egg leaves the ovary , it is directed into the fallopian tube by the finger-like fimbriae . if the egg is not fertilized by sperm within 24 hours , the unfertilized egg will die , and the entire system will reset itself , preparing to create a new egg and uterine lining the following month . the egg is the largest cell in the body and is protected by a thick , extracellular shell of sugar and protein called the zona pellucida . the zona thwarts the entry and fusion of more than one sperm , the smallest cell in the body . it takes a man two to three months to make sperm , and the process constantly renews . each ejaculation during sexual intercourse releases more than 100 million sperm . but only 100 or so will ultimately make it to the proximity of the egg , and only one will successfully penetrate through the armor of the zona pellucida . upon successful fertilization , the zygote immediately begins developing into an embryo , and takes about three days to reach the uterus . there , it requires another three or so days to implant firmly into the endometrium , the inner lining of the uterus . once implanted , the cells that are to become the placenta secrete a hormone that signals to the ovulated follicle that there is a pregnancy in the uterus . this helps rescue that follicle , now called the corpus luteum , from degenerating as it normally would do in that stage of the menstrual cycle . the corpus luteum is responsible for producing the progesterone required to maintain the pregnancy until six to seven weeks of gestation , when the placenta develops and takes over , until the baby is born approximately 40 weeks later . now , how do you make a baby in a lab ? in patients undergoing ivf , fsh is administered at levels that are higher than naturally occuring to cause a controlled overstimulation of the ovaries so that they ultimately produce multiple eggs . the eggs are then retrieved just before ovulation would occur , while the woman is under anesthesia , through an aspirating needle that is guided by ultrasound . most sperm samples are produced by masturbation . in the laboratory , the identified eggs are stripped of surrounding cells and prepared for fertilization in a petri dish . fertilization can occur by one of two techniques . in the first , the eggs are incubated with thousands of sperm and fertilization occurs naturally over a few hours . the second technique maximizes certainty of fertilization by using a needle to place a single sperm inside the egg . this is particularly useful when there is a problem with the quality of the sperm . after fertilization , embryos can be further screened for genetic suitability , frozen for later attempted pregnancies , or delivered into the woman 's uterus via catheter . common convention is to transfer the embryo three days after fertilization , when the embryo has eight cells , or on day five , when the embryo is called a blastocyst , and has hundreds of cells . if the woman 's eggs are of poor quality due to age or toxic exposures , or have been removed due to cancer , donor eggs may be used . in the case that the intended mother has a problematic uterus , or lacks one , another woman , called the gestational carrier or surrogate , can use her uterus to carry the pregnancy . to increase the odds of success , which are as high as 40 % for a woman younger than 35 , doctors sometimes transfer multiple embryos at once , which is why ivf results in twins and triplets more often than natural pregnancies . however , most clinics seek to minimize the chances of multiple pregnancies , as they are riskier for mothers and babies . millions of babies , like louise brown , have been born from ivf and have had normal , healthy lives . the long-term health consequences of ovarian stimulation with ivf medicines are less clear , though so far , ivf seems safe for women . because of better genetic testing , delayed childbearing , increased accessibility and diminishing cost , it 's not inconceivable that artificial baby making via ivf and related techniques could outpace natural reproduction in years to come .
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roughly fifteen days before fertilization can happen , the anterior pituitary gland secretes follicle stimulating hormone , fsh , which ripens a handful of follicles of the ovary that then release estrogen . each follicle contains one egg , and on average , only one follicle becomes fully mature . as it grows and continues to release estrogen , this hormone not only helps coordinate growth and preparation of the uterus , it also communicates to the brain how well the follicle is developing .
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why does the female body only release one-egg ( on average ) each month while a man can produce millions of sperm multiple times a month ?
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the dead coming back to life sounds scary . but for scientists , it can be a wonderful opportunity . of course , we 're not talking about zombies . rather , this particular opportunity came in the unlikely form of large , slow-moving fish called the coelacanth . this oddity dates back 360 million years , and was believed to have died out during the same mass extinction event that wiped out the dinosaurs 65 million years ago . to biologists and paleontologists , this creature was a very old and fascinating but entirely extinct fish , forever fossilized . that is , until 1938 when marjorie courtenay-latimer , a curator at a south african museum , came across a prehistoric looking , gleaming blue fish hauled up at the nearby docks . she had a hunch that this strange , 1.5 meter long specimen was important but could n't preserve it in time to be studied and had it taxidermied . when she finally was able to reach j.l.b . smith , a local fish expert , he was able to confirm , at first site , that the creature was indeed a coelacanth . but it was another 14 years before a live specimen was found in the comoros islands , allowing scientists to closely study a creature that had barely evolved in 300 million years . a living fossil . decades later , a second species was found near indonesia . the survival of creatures thought extinct for so long proved to be one of the biggest discoveries of the century . but the fact that the coelacanth came back from the dead is n't all that makes this fish so astounding . even more intriguing is the fact that genetically and morphologically , the coelacanth has more in common with four-limbed vertebrates than almost any other fish , and its smaller genome is ideal for study . this makes the coelacanth a powerful link between aquatic and land vertebrates , a living record of their transition from water to land millions of years ago . the secret to this transition is in the fins . while the majority of ocean fish fall into the category of ray-finned fishes , coelacanths are part of a much smaller , evolutionarily distinct group with thicker fins known as lobe-finned fish . six of the coelacanth 's fins contain bones organized much like our limbs , with one bone connecting the fin to the body , another two connecting the bone to the tip of the fin , and several small , finger-like bones at the tip . not only are those fins structured in pairs to move in a synchronized way , the coelacanth even shares the same genetic sequence that promotes limb development in land vertebrates . so although the coelacanth itself is n't a land-walker , its fins do resemble those of its close relatives who first hauled their bodies onto land with the help of these sturdy , flexible appendages , acting as an evolutionary bridge to the land lovers that followed . so that 's how this prehistoric fish helps explain the evolutionary movement of vertebrates from water to land . over millions of years , that transition led to the spread of all four-limbed animals , called tetrapods , like amphibians , birds , and even the mammals that are our ancestors . there 's even another powerful clue in that unlike most fish , coelacanths do n't lay eggs , instead giving birth to live , young pups , just like mammals . and this prehistoric fish will continue to provide us with fascinating information about the migration of vertebrates out of the ocean over 300 million years ago . a journey that ultimately drove our own evolution , survival and existence . today the coelacanth remains the symbol of the wondrous mysteries that remain to be uncovered by science . with so much left to learn about this fish , the ocean depths and evolution itself , who knows what other well-kept secrets our future discoveries may bring to life !
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there 's even another powerful clue in that unlike most fish , coelacanths do n't lay eggs , instead giving birth to live , young pups , just like mammals . and this prehistoric fish will continue to provide us with fascinating information about the migration of vertebrates out of the ocean over 300 million years ago . a journey that ultimately drove our own evolution , survival and existence .
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briefly explain the link between the coelacanth and the migration of vertebrates out of the ocean nearly 300 million years ago .
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long before descartes famously declared , `` i think , therefore i am , '' and long after that , scientists and philosophers alike have puzzled over what they call the mind-body problem . is the mind some separate , non-material entity piloting a machine of flesh ? or if it 's just a particularly elusive part of our physical body , how can it translate the input of our animal senses into the seemingly non-physical experiences that we call thoughts ? but though the answers have been debated endlessly , new research suggests that part of the problem lies in how we pose the question in the first place , assuming a distinction between our sensory perception and our ideas that may not really be there . the traditional model of our mental function has been that the senses provide separate data to our brain which are then translated into the appropriate mental phenomena : visual images into trees , auditory experiences into bird songs , and so on . but occasionally , we have come across people whose senses seem to mingle together , allowing them to hear colors , or taste sounds . until recently , the common understanding was that this phenomenon , called synesthesia , was a direct connection between the parts of the brain responsible for sensory stimuli such as seeing the color yellow immediately upon hearing the tone of b flat . but newer studies have shown that synesthesia is actually mediated through our understanding of the shapes , colors and sounds that our senses apprehend . in order for the cross-sensory experiences to occur , the higher level ideas and concepts that our minds associate with the sensory input must be activated . for example , this shape can be seen as either the letter `` s '' or the number `` 5 , '' and synesthetes associate each with different colors or sounds based on how they interpret it despite the purely visual stimulus remaining identical . in another study , synesthetes created novel color associations for unfamiliar letters after learning what the letters were . so because it relies on a connection between ideas and senses , this mental phenomenon underlying synesthesia is known as ideasthesia . synesthesia only occurs in some people , although it may be more common than previously thought . but ideasthesia itself is a fundamental part of our lives . virtually all of us recognize the color red as warm and blue as cold . many would agree that bright colors , italic letters and thin lines are high-pitched , while earth tones are low-pitched . and while many of these associations are acquired through cultural exposure , others have been demonstrated even in infants and apes , suggesting that at least some associations are inborn . when asked to choose between two possible names for these shapes , people from entirely different cultural and language backgrounds overwhelmingly agree that `` kiki '' is the spiky star , while `` bouba '' is the rounded blob , both because of the sounds themselves and the shapes our mouths make to produce them . and this leads to even more associations within a rich semantic network . kiki is described as nervous and clever , while bouba is perceived as lazy and slow . what all of this suggests is that our everyday experiences of colors , sounds and other stimuli do not live on separate sensory islands but are organized in a network of associations similar to our language network . this is what enables us to understand metaphors even though they make no logical sense , such as the comparison of snow to a white blanket , based on the shared sensations of softness and lightness . ideasthesia may even be crucial to art , which relies on a synthesis of the conceptual and the emotional . in great art , idea and aesthesia enhance each other , whether it 's song lyrics combining perfectly with a melody , the thematic content of a painting heightened by its use of colors and brushstrokes , or the well constructed plot of a novel conveyed through perfectly crafted sentences . most importantly , the network of associations formed by ideasethesia may not only be similar to our linguistic network but may , in fact , be an integral part of it . rather than the traditional view , where our senses first capture a collection of colors and shapes , or some vibrations in the air , and our mind then classifies them as a tree or a siren , ideasthesia suggests that the two processes occur simultaneously . our sensory perceptions are shaped by our conceptual understanding of the world . and the two are so connected that one can not exist without the other . if this model suggested by ideasthesia is accurate , it may have major implications for some of the biggest scientific and philosophical issues surrounding the study of mind . without a preexisting concept of self , descartes would not have had an `` i '' to attribute the thinking to . and without a preexisting network of interrelated and distinct concepts , our sensory experience of the world would be an undifferentiated mass rather than the discrete objects we actually apprehend . for science , the task is to find where this network lies , how it is formed , and how it interacts with external stimuli . for philosophy , the challenge is to rethink what this new model of consciousness means for our understanding of our selves and our relation to the world around us .
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if this model suggested by ideasthesia is accurate , it may have major implications for some of the biggest scientific and philosophical issues surrounding the study of mind . without a preexisting concept of self , descartes would not have had an `` i '' to attribute the thinking to . and without a preexisting network of interrelated and distinct concepts , our sensory experience of the world would be an undifferentiated mass rather than the discrete objects we actually apprehend .
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in descartes ' `` i think , therefore i am , '' an important concept contributing to the experience of thinking may be :
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feldspar mineral ... from the ytterby quarry . how many elements does it contain ? shall we take it home ? so terbium , just like europium , is often used in television screens and various types of displays and where it comes in is that it gives green and yellow colours , which in contrast to the red and blue which europium gives you , gives you the full selection that you need to give colour images . so ytterby gruva , ytterby mine , what a great place , the snow is falling . this is designated ytterby mine , a historical landmark for the discovery of four periodic elements : yttrium , terbium , erbium , and ytterbium . terbium was eventually discovered or eventually isolated by the chemist mosander in 1843 . it was from an earth called itrea which was originated in this quarry where we are right now in ytterby in sweden . terbium is a really unusual element . it ’ s a metal ; moderate abundance . it ’ s called a rare earth element , which is really quite ironic because it ’ s not as rare as its name would suggest . the abundance is something like 20 to 30 times that of silver , so i don ’ t think it ’ s really rare . it doesn ’ t really have much biological activity but we do find terbium within the bones in the human body and in animals but also within the kidneys so you do find small concentrations but it doesn ’ t really have a perceived biological activity . terbium is also used in certain magnetic devices and when you include it in certain alloys it forms magnetic devices which increase or decrease in size depending on the strength or type of magnetic field which they are placed into which has various technological applications . so terbium alloys are really quite interesting because they have what ’ s called magnetostrictive behaviour . so what that means is that the size of the crystal or the size of the structure of the alloy itself gets either larger or smaller when it ’ s exposed to a large or strong magnetic field . so , there ’ s much research going into these terbium alloys for small motors or small switches perhaps and also to use as strain gauges and other types of really quite elaborate instruments . so these may well provide us a lot of new research in the areas of nano-science and nano-machines . also , because of its fluorescence nature it ’ s often used as a marker in biochemistry so if you want to stain cells and determine whether certain types are present then you can use it for that too . so in terms of day-to-day life , where do we find terbium ? well we find it in unusual devices like energy-saving light-bulbs because it stimulates or it increases the yield of light in the mercury discharge that we use to run fluorescent strips . so we found it around us in shops and houses , in factories , street-lighting , everywhere . but what i think is a really quite nice and important application of terbium is the fact that it ’ s used to make phosphorescent materials . so these are materials which generate light or allow us to develop pictures if we irradiate them with something like an x-ray . and , in fact , terbium is used to make very , very high light yielding phosphors for use in screens and visualisation screens for x- rays . so what this means is that if i go into the hospital for diagnostic x- ray i no longer have to be exposed to long periods of x-rays because the terbium screen allows the generation of the pictures at much , much lower dose of x-ray . so it ’ s really quite a significant advance . it ’ s really quite nice chemistry as well .
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so these may well provide us a lot of new research in the areas of nano-science and nano-machines . also , because of its fluorescence nature it ’ s often used as a marker in biochemistry so if you want to stain cells and determine whether certain types are present then you can use it for that too . so in terms of day-to-day life , where do we find terbium ? well we find it in unusual devices like energy-saving light-bulbs because it stimulates or it increases the yield of light in the mercury discharge that we use to run fluorescent strips .
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as stephen explained , which property allows us to use terbium as a marker in biochemistry ?
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( electronic instrumental music ) ( instrumental synthesizer music ) - [ carl ] that 's inevitable that humans would project their hopes and fears upon the cosmos . the standard hollywood attempts are to portray the extraterrestrials as red of claw and fang . pointed heads and nasty dispositions . steven spielberg has made an important step forward , e.t . and close encounters of the third kind , to show the possibility of benign extraterrestrials , but even there , the extraterrestrials are only slight variants on human beings , when the evolutionary record is clear that extraterrestrials would be very different from us and also they 're not awfully smart , his extraterrestrials . - [ studs ] sweet , but not smart . - [ carl ] sweet , but not smart . if you look at timescales , you realize that our civilization is the most backward civilization in the galaxy that could communicate at all , because we 've just invented radio telescopes , just a few decades ago . we had not the ghost of a chance of communicating with anybody else . so if we receive a message , it ca n't be from anybody less capable than we , because anybody less capable ca n't communicate at all . so it has to be somebody much in advance of us and maybe as much in advance of us as we are in advance of the ants , say , or the worms . - [ studs ] you , carl sagan , scientist , astronomer , enlighten me . you think that indeed there may be some sort of intelligence out there ? - [ carl ] may , surely , surely may . there is , we now realize , an enormous number of planets . a range of planetary systems around the nearby stars . so there 's a lot of potential abodes for life . that 's one thing . then there 's the question of organic matter . the carbon-rich complex molecules that are essential for the kind of life we know about , are fantastically abundant . they litter the universe . we see them in asteroids , in comets , in the moons in the outer solar system and even in the cold dark spaces between the stars , so the stuff of life is everywhere , and then there 's time . there are billions of years for biological evolution on all those worlds , there are many worlds that are much older than ours . so you put those together , lots of places , lots of organic matter , lots of time and it seems very hard to believe that our paltry little planet is the only one that 's inhabited . - [ studs ] you know , there 's a phrase you use about the earth people us , we , are so benighted . `` the earth is the ghetto of the universe . '' we 're the ghetto of the universe . - [ carl ] well in an extremely backward and obscure part of the milky way galaxy . we 're 30,000 light years from the center of the galaxy . we 're in the galactic boondocks . this whole galaxy is only one of probably hundreds of billions of other galaxies , a useful calibration of our place in the universe . - [ studs ] there 's also religion and science . - [ carl ] there is a tendency in both schools of thought to think that they have a corner on the truth . i mean , a way to look at it is the following , science and religion on some level are after the same thing . take the question of our origins . both science and religion attempt to approach this question . but the religions all contradict each other , so they ca n't all be right . the judeo-christian islamic religion holds that the world is about 6,000 years old , you just count up the begats in the old testament . it 's very clear , 6,000 years old . the hindus have an infinitely old universe with an infinite number of creations and destructions of the whole universe . now those two major religions ca n't both be right . how do you tell which is right and which is wrong ? well , the only way is to appeal to the natural world around us and the natural world around us shows that the earth , for example , is about four point six billion years old and nothing like 6,000 years old . so a literal reading of the bible simply is a mistake , i mean it 's just wrong , it 's just wrong . as a work of science , it is flawed , it 's the science of the babylonians in the sixth century b.c . we 've learned something since then . - [ voiceover ] this special episode of blank on blank is supported by squarespace . whether your story is out of the ordinary or simply out of this world , you should tell it in an unforgettable way . with user-friendly tools and templates , squarespace helps you capture your story with a captivating website . start your trial today . visit squarespace.com/blankonblank . - [ studs ] well you quote einstein . the cosmic religious feeling , he is religious in that sense , is the strongest , noblest mode of a scientific research , so there 's a religion of sorts that einstein believed in . - [ carl ] right , but it 's very different from most people 's view of religion . einstein talked about god , but for einstein , god was little more than the sum total of the laws of the universe . there was no hint of intervention in daily life , of the efficacy of prayer , of life after death or any of those accouterments of the judeo-christian islamic religion . - [ voiceover ] this episode was also supported by the alfred p. sloan foundation , enhancing public understanding of science , technology and economic performance . more information on sloan at sloan.org . ( peaceful instrumental music ) ( tape reversing )
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so it has to be somebody much in advance of us and maybe as much in advance of us as we are in advance of the ants , say , or the worms . - [ studs ] you , carl sagan , scientist , astronomer , enlighten me . you think that indeed there may be some sort of intelligence out there ?
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carl sagan argues that if we were to receive a message from an extraterrestrial civilization , the civilization would have to be far more sophisticated and technologically advanced than our 's . what evidence does he use to back this up ?
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how is it that so many intergalactic species in movies and tv just happen to speak perfect english ? the short answer is that no one wants to watch a starship crew spend years compiling an alien dictionary . but to keep things consistent , the creators of star trek and other science-fiction worlds have introduced the concept of a universal translator , a portable device that can instantly translate between any languages . so is a universal translator possible in real life ? we already have many programs that claim to do just that , taking a word , sentence , or entire book in one language and translating it into almost any other , whether it 's modern english or ancient sanskrit . and if translation were just a matter of looking up words in a dictionary , these programs would run circles around humans . the reality , however , is a bit more complicated . a rule-based translation program uses a lexical database , which includes all the words you 'd find in a dictionary and all grammatical forms they can take , and set of rules to recognize the basic linguistic elements in the input language . for a seemingly simple sentence like , `` the children eat the muffins , '' the program first parses its syntax , or grammatical structure , by identifying the children as the subject , and the rest of the sentence as the predicate consisting of a verb `` eat , '' and a direct object `` the muffins . '' it then needs to recognize english morphology , or how the language can be broken down into its smallest meaningful units , such as the word muffin and the suffix `` s , '' used to indicate plural . finally , it needs to understand the semantics , what the different parts of the sentence actually mean . to translate this sentence properly , the program would refer to a different set of vocabulary and rules for each element of the target language . but this is where it gets tricky . the syntax of some languages allows words to be arranged in any order , while in others , doing so could make the muffin eat the child . morphology can also pose a problem . slovene distinguishes between two children and three or more using a dual suffix absent in many other languages , while russian 's lack of definite articles might leave you wondering whether the children are eating some particular muffins , or just eat muffins in general . finally , even when the semantics are technically correct , the program might miss their finer points , such as whether the children `` mangiano '' the muffins , or `` divorano '' them . another method is statistical machine translation , which analyzes a database of books , articles , and documents that have already been translated by humans . by finding matches between source and translated text that are unlikely to occur by chance , the program can identify corresponding phrases and patterns , and use them for future translations . however , the quality of this type of translation depends on the size of the initial database and the availability of samples for certain languages or styles of writing . the difficulty that computers have with the exceptions , irregularities and shades of meaning that seem to come instinctively to humans has led some researchers to believe that our understanding of language is a unique product of our biological brain structure . in fact , one of the most famous fictional universal translators , the babel fish from `` the hitchhiker 's guide to the galaxy '' , is not a machine at all but a small creature that translates the brain waves and nerve signals of sentient species through a form of telepathy . for now , learning a language the old fashioned way will still give you better results than any currently available computer program . but this is no easy task , and the sheer number of languages in the world , as well as the increasing interaction between the people who speak them , will only continue to spur greater advances in automatic translation . perhaps by the time we encounter intergalactic life forms , we 'll be able to communicate with them through a tiny gizmo , or we might have to start compiling that dictionary , after all .
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in fact , one of the most famous fictional universal translators , the babel fish from `` the hitchhiker 's guide to the galaxy '' , is not a machine at all but a small creature that translates the brain waves and nerve signals of sentient species through a form of telepathy . for now , learning a language the old fashioned way will still give you better results than any currently available computer program . but this is no easy task , and the sheer number of languages in the world , as well as the increasing interaction between the people who speak them , will only continue to spur greater advances in automatic translation .
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using your own innate knowledge of your native language , give one or two examples of an irregularity or exception that could cause problems for a machine translator .
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hi , i ’ m john green . this is crash course world history and today we ’ re going to talk about world war ii . finally , a war with some color film ! so , here at crash course we try to make history reasonably entertaining , and fortunately , world war ii was hilarious ... said no one ever . mr. green , mr. green ! is this , like , gon na be one of the unfunny ones where you build to the big melodramatic conclusion about how i have to imagine the world more complexly ? me from the past , as long as you have that eighth rate soup-strainer , i ’ m not even going to acknowledge your existence . [ theme music ] right , so you ’ ve probably heard a lot about world war ii from movies and books , the history channel , before it decided that swamp people were history , the incessant droning of your grandparents , etc . we ’ re not gon na try to give you a detailed synopsis of the war today . instead , we ’ re going to try to give a bit of perspective on how the most destructive war in human history happened , and why it still matters globally . so one of the reasons history classes tend to be really into wars is that they ’ re easy to put on tests . they start on one day and they end on another day . and they ’ re caused by social , political , and economic conditions that can be examined in a multiple choice kind of manner . except , not really . like , when did world war ii start ? in september 1939 , when the nazis invaded poland ? i ’ d say no - it actually started when japan invaded manchuria in 1931 , or at the very latest when the japanese invaded china in 1937 , because they didn ’ t stop fighting until 1945 . then again , you could also argue 1933 , when hitler took power , or 1941 , when america started fighting . it ’ s complicated . but anyway , in china the fighting was very brutal , as exemplified by the infamous rape of nanking , which featured the slaughter of hundreds of thousands of chinese people and is still so controversial today that : 1 . it affects relations between japan & amp ; amp ; china and 2 . even though i have not described it in detail , you can rest assured that there will be angry comments about my use of the word “ slaughter. ” but the world war ii we know the most about from movies and tv is primarily the war in the european theater , the one that adolf hitler started . hitler is the rare individual who really did make history - specifically he made it worse - and if he hadn ’ t existed , it ’ s very unlikely that world war ii would ’ ve ever happened . but he did exist , and after coming to power in 1933 , with the standard revolutionary promises to return the homeland to its former glory , infused with quite a bit of paranoia and anti-semitism , germany saw rapid re-militarization and eventually , inevitably , war . in the beginning , it was characterized by a new style of combat made possible by the mechanized technology of tanks , airplanes , and especially , trucks . this was the blitzkrieg , a devastating tactic combining quick movement of troops , tanks , and massive use of air power to support infantry movements . and in the very early years of the war , it was extremely effective . the nazis were able to roll over poland , norway , denmark , the netherlands , and then all of france , all within about 9 months between the fall of 1939 and the summer of 1940 . so after knocking out most of central europe , the nazis set their sights on great britain , but they didn ’ t invade the island , choosing instead to attack it with massive air strikes . i mean , you look at this poster and think , “ man , the queen wants me to finish my term paper , so i can do it , ” but when this poster was first produced in 1939 , it was to quell terror in the face of bombardment . the battle of britain was a duel between the royal air force and the luftwaffe , and while the raf denied the nazis total control of british airspace , the nazis were still able to bomb great britain over and over again in what ’ s known as the blitz . stan , no . no jokes this time . yes , the blitz . meanwhile , europeans were also fighting each other in north africa . the desert campaigns started in 1940 and lasted through 1942 - this is where british general “ monty ” montgomery outfoxed german general irwin “ the desert fox ” rommel . it ’ s also the place where americans first fought nazis in large numbers . but most importantly , it ’ s where indiana jones discovered the ark of the covenant . okay , let ’ s go to the thought bubble . 1941 was a big year for world war ii . first , the nazis invaded russia , breaking a non-aggression pact that the two powers had signed in 1939 . this hugely escalated the war , and also made allies of the most powerful capitalist countries and the most powerful communist one , an alliance that would stand the test of time and never end ... until like three seconds after the defeat of the nazis . the nazi invasion of russia opened the war up on the so-called eastern front , although if you were russian , it was the western front , and it led to millions of deaths , mostly russian . also , 1941 saw a day that would `` live in infamy '' when the japanese bombed pearl harbor , hoping that such an audacious attack would frighten the united states into staying neutral , which was a pretty stupid gamble because : 1 . the u.s. was already giving massive aid to the allies and was hardly neutral and 2 . the united states is not exactly famed for its pacifism or political neutrality . 1941 also saw japan invading much of southeast asia , which made australia and new zealand understandably nervous . as part of the british commonwealth , they were already involved in the war , but now they could fight the japanese closer to home . and shut up about how i never talk about you australians . i just gave you 1.5 sentences . but by the time the americans and australians started fighting the japanese , it was already a world war . sometimes this meant fighting or starving or being bombed ; other times , it meant production for the war - you don ’ t think of argentina as being a world war ii powerhouse , for instance , but they were vital to the allies , supplying 40 % of british meat during world war ii . thanks , thought bubble . so , not to sound jingoistic , but the entry of the u.s. into the war really did change everything , although i doubt the nazis could ’ ve taken russia regardless . no one conquers russia in the wintertime , unless you are - wait for it - the mongols . okay , we ’ re going to skip most of the big battles of 1942 - like the battle of midway , which effectively ended japan ’ s chance of winning the war - and focus on the battle of stalingrad . the german attack on stalingrad , now known as volgograd because stalin sucks , was one of the bloodiest battles in the history of war , with more than two million dead . the germans began by dropping more than 1,000 tons of bombs on stalingrad , and then the russians responded by “ hugging ” the germans , staying as close to their front lines as possible so that german air support would kill germans and russians alike . this kind of worked , although the germans still took most of the city . but then , a soviet counterattack left the sixth army of the nazis completely cut off . and after that , due partly to hitler ’ s overreaching megalomania and partly to lots of people being scared of him , the sixth army slowly froze and starved to death before finally surrendering . and of the 91,000 axis pows from stalingrad , only about 6,000 ever returned home . stalingrad turned the war in europe and by 1944 , the american strategy of “ island hopping ” in the pacific was taking gis closer and closer to japan . rome was liberated in june by americans and canadians ; and the successful british , canadian , and american d-day invasion of normandy was the beginning of the end for the nazis . oh , it ’ s time for the open letter ? an open letter to canada . but first , let ’ s see what ’ s in the secret compartment today . oh , it ’ s canadian mittens . i wan na thank the canadian crash course fans , who sent us these mittens . canadians are just so nice , stan . like , all we ever do on this show is make fun of them , and they ’ re just like , “ it ’ s so kind of you to mention us . here ’ s some mittens ! ” dear canada , we ’ re not always nice to you here on crash course , but you are awesome . i ’ m pointing , but you can ’ t tell because i ’ m wearing mittens . 45,000 canadians died fighting for the allies in world war ii , which means that , per capita , canada lost more people than the united states . you fought with the royal air force to defend great britain from the beginning of the war and you were there on d-day , successfully invading juno beach . and , as many of you have pointed out in comments , you defeated the united states in the war of 1812 , meaning that , arguably , canada , you are the greater military power . plus , you have lumberjacks , and excellent beer , and hockey , and universal healthcare , and justin bieber . i ’ m jealous ! that 's what it is - i 'm jealous ! best wishes , john green . so , by the end of 1944 , the allies were advancing from the west and the russian red army was advancing from the east and then , the last-ditch german offensive at the battle of the bulge in the winter of 1944-1945 failed . mussolini was executed in april of 1945 . hitler committed suicide at the end of that month . and , on may 8 , 1945 the allies declared victory in europe after germany surrendered unconditionally . three months later , the united states dropped the only two nuclear weapons ever deployed in war , japan surrendered , and world war ii was over . the war had a definite cause : unbridled military expansion by germany , japan , and , to a small extent , italy . now , it ’ s easy to claim that hitler was crazy or evil , and , in fact , he was certainly both , but that doesn ’ t explain the nazis decision to invade russia , and it sure doesn ’ t explain japan ’ s decision to bomb pearl harbor . and there are many possible explanations beyond mere evil ; but the most interesting one , to me , involves food . hitler had a number of reasons for wanting to expand germany ’ s territory , but he often talked about lebensraum or living space for the german people . german agriculture was really inefficiently organized into lots of small farms , and that meant that germany needed a lot of land in order to be self-sufficient in food production . the plan was to take poland , the ukraine , and eastern russia , and then resettle that land with lots of germans , so that it could feed german people . this was called the hunger plan because the plan called for 20 million people to starve to death . many would be the poles , ukrainians , and russians who ’ d previously lived on the land . the rest would be europe ’ s jews , who would be worked to death . six million jews were killed by the nazis , many by starvation , but many through a chillingly planned effort of extermination in death camps . these death camps can be distinguished from concentration camps or labor camps in that their primary purpose was extermination of jews , roma people , communists , homosexuals , disabled people , and others that the nazis deemed unfit . some historians believe that the nazis opened the death camps because the jews weren ’ t dying as fast as the hunger plan had intended . this was a sickening plan , but it made a kind of demented sense . rather than becoming more involved in global trade , as the british had , the germans would feed themselves by taking land and killing the people who ’ d previously lived there . similarly , japan , at the beginning of the war , was suffering from an acute fear of food shortage because its agricultural sector was having trouble keeping up with population growth . and the japanese too , sought to expand their agricultural holdings by , for instance , resettling farmers in korea . so while it ’ s tempting to say that world war ii was about the allies fighting for democratic ideals against the totalitarian militaristic imperialism of the fascist axis powers , it just doesn ’ t hold up to scrutiny . for instance , a hugely important allied power , stalin ’ s soviet union , was , like , the least democratic place , ever . stan just said that was hyperbole , but it ’ s not . stalin ’ s soviet union is tied with all of the other completely undemocratic countries for last place on the democracy scale . it ’ s a big community there , at last place , but they ’ re definitely in there somewhere . and , by far , the biggest imperialists of the war were the british . they couldn ’ t have fed or clothed themselves - or resisted the nazis - without their colonies and commonwealth . so , why is world war ii so important ? well first , it proved the old roman adage homo homini lupus : man is a wolf to man . this is seen most clearly in the holocaust , but all the statistics are staggering . more than a million indian british subjects died , mainly due to famine that could have been avoided if the british had redistributed food . and their failure to do so helped convince indians that the so-called superior civilization of the british was a sham . more than a million vietnamese died , mainly due to famine . 418,000 americans . more than a million noncombatants in both germany and japan . and 20 million people in the soviet union , most of them civilians . these civilians were targeted because they helped sustain the war , mostly through industrial and agricultural production . in a total war , when a nation is at war , not just its army , there is no such thing as a non-military target . from the firebombing of dresden to tokyo to hiroshima , the line between soldier and civilian blurred . and then , of course , there is the holocaust , which horrifies us because the elements of western progress - record-keeping , industrial production , technology - were used to slaughter millions . world war ii saw modern industrial nations , which represented the best of the enlightenment and the scientific revolution , descend into once unimaginable cruelty . and what makes world war ii such a historical watershed is that in its wake , all of us - in the west or otherwise - were forced to question whether western dominance of this planet could , or should , be considered progress . thanks for watching . i ’ ll see you next week . crash course is produced and directed by stan muller . our script supervisor is meredith danko . our associate producer is danica johnson . the show is written by my high school history teacher , raoul meyer , and myself . and our graphics team is thought bubble . last week ’ s phrase of the week was “ an end to history. ” if you want to guess at this week ’ s phrase of the week or suggest future ones , you can do so in comments , where you can also ask questions about today ’ s video that will be answered by our team of historians . if you enjoy crash course , make sure you ’ re subscribed . thanks for watching , and as we say in my hometown , don ’ t forget to be awesome .
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except , not really . like , when did world war ii start ? in september 1939 , when the nazis invaded poland ?
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depending on how you view the origins of world war ii , there are multiple events that `` started '' the war . which of the following timelines has those events in the correct order ?
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fu manchu was one of the most notorious escape artists at the omaha zoo in the 1960s . but he was n't a performer , he was an orangutan . the keepers who locked his enclosure every night were baffled to find him outside the next day hanging out with friends in a tree , or sunning on the roof . only after installing cameras did they realize fu manchu had been picking the lock with a metal wire that he kept hidden under his cheek pouch . the keepers should n't have been surprised at fu manchu 's cunningness . along with our other great ape cousins , the gorillas , chimps , and bonobos , they belong to our hominidae family tree , which stretches back 14 million years . but it 's not just their striking red hair that makes orangutans unique among our cousins . as the only great apes from asia , orangutans have adapted to a life high in the rain forest canopies . many of the skills they learn are transmitted through the special bond they have with their mothers , the most extended in the animal kingdom next to humans . orangutan mothers usually give birth to one baby at a time , waiting up to eight years before having another . this gives the young , who begin as fully dependent infants , plenty of time to learn how to climb and distinguish the hundreds of plants and fruits that make up their diet . female orangutans even stay with their mothers into their teen years to learn child-rearing . as they grow up , orangutans also develop a complex set of cooperative social skills by interacting with their peers and siblings . much like ourselves , young orangutans involuntarily mimic the facial expressions and emotions of their playmates , with behaviors that closely parallel human smiling and laughter . once they finally venture out on their own , orangutans continue to develop their resourcefulness , putting the skills they 've learned into practice . adults build a new nest each night by carefully weaving twigs together , topping them with soft leaves , pillows , and blankets . this process requires dexterity , coordination , and an eye for design . orangutans also use a variety of tools to make their lives in the jungle easier . they turn branches into fly swatters and back scratchers , construct umbrellas when it rains , make gloves from leafy pads , and even use leaves as bandages to dress their wounds . but orangutan intelligence goes far beyond jungle survival . research in controlled environments has shown that orangutans are self-aware , being one of the few species to recognize their own reflections . they also display remarkable foresight , planning , and cognition . in one experiment , researchers taught an orangutan to use a straw to extract his favorite fruit soup from a box . that orangutan was later given the choice between the straw or a grape that could be eaten right away , and he chose the straw just in case he was given another box of soup . in another experiment , orangutans figured out how to reach peanuts at the bottom of long tubes by spitting water into them . while orangutans are able to pass cognitive tests with flying colors , there are certain problems that they need our help to solve . indonesia has the world 's highest rate of deforestation , and millions of acres of rain forest are burned annually to support the logging and palm oil industries . deforestation exposes the 30,000 orangutans remaining in the wild to poachers . they kill mothers so that baby orangutans can be sold as exotic pets . but fortunately , the story often does n't end here . orphans can be confiscated and given a second chance . at special forest schools , they recover from emotional trauma and continue to develop essential life skills . against all odds , these orphans demonstrate incredible resilience and readiness to learn . in malay , the word orangutan translates literally to `` the person of the forest , '' a reminder of our common lineage . and despite orangutans being some of the smartest animals on earth , outsmarting their extinction requires the creativity , empathy , and foresight that our species share .
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many of the skills they learn are transmitted through the special bond they have with their mothers , the most extended in the animal kingdom next to humans . orangutan mothers usually give birth to one baby at a time , waiting up to eight years before having another . this gives the young , who begin as fully dependent infants , plenty of time to learn how to climb and distinguish the hundreds of plants and fruits that make up their diet .
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why does a baby orangutan stay with its mother for so long ?
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this is the story of three plastic bottles , empty and discarded . their journeys are about to diverge with outcomes that impact nothing less than the fate of the planet . but they were n't always this way . to understand where these bottles end up , we must first explore their origins . the heroes of our story were conceived in this oil refinery . the plastic in their bodies was formed by chemically bonding oil and gas molecules together to make monomers . in turn , these monomers were bonded into long polymer chains to make plastic in the form of millions of pellets . those were melted at manufacturing plants and reformed in molds to create the resilient material that makes up the triplets ' bodies . machines filled the bottles with sweet bubbily liquid and they were then wrapped , shipped , bought , opened , consumed and unceremoniously discarded . and now here they lie , poised at the edge of the unknown . bottle one , like hundreds of millions of tons of his plastic brethren , ends up in a landfill . this huge dump expands each day as more trash comes in and continues to take up space . as plastics sit there being compressed amongst layers of other junk , rainwater flows through the waste and absorbs the water-soluble compounds it contains , and some of those are highly toxic . together , they create a harmful stew called leachate , which can move into groundwater , soil and streams , poisoning ecosystems and harming wildlife . it can take bottle one an agonizing 1,000 years to decompose . bottle two 's journey is stranger but , unfortunately , no happier . he floats on a trickle that reaches a stream , a stream that flows into a river , and a river that reaches the ocean . after months lost at sea , he 's slowly drawn into a massive vortex , where trash accumulates , a place known as the great pacific garbage patch . here the ocean 's currents have trapped millions of pieces of plastic debris . this is one of five plastic-filled gyres in the world 's seas . places where the pollutants turn the water into a cloudy plastic soup . some animals , like seabirds , get entangled in the mess . they , and others , mistake the brightly colored plastic bits for food . plastic makes them feel full when they 're not , so they starve to death and pass the toxins from the plastic up the food chain . for example , it 's eaten by lanternfish , the lanternfish are eaten by squid , the squid are eaten by tuna , and the tuna are eaten by us . and most plastics do n't biodegrade , which means they 're destined to break down into smaller and smaller pieces called micro plastics , which might rotate in the sea eternally . but bottle three is spared the cruel purgatories of his brothers . a truck brings him to a plant where he and his companions are squeezed flat and compressed into a block . okay , this sounds pretty bad , too , but hang in there . it gets better . the blocks are shredded into tiny pieces , which are washed and melted , so they become the raw materials that can be used again . as if by magic , bottle three is now ready to be reborn as something completely new . for this bit of plastic with such humble origins , suddenly the sky is the limit .
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for example , it 's eaten by lanternfish , the lanternfish are eaten by squid , the squid are eaten by tuna , and the tuna are eaten by us . and most plastics do n't biodegrade , which means they 're destined to break down into smaller and smaller pieces called micro plastics , which might rotate in the sea eternally . but bottle three is spared the cruel purgatories of his brothers .
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make a list of some products you think recycled plastics could be turned into .
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imagine a group of people . how big do you think the group would have to be before there 's more than a 50 % chance that two people in the group have the same birthday ? assume for the sake of argument that there are no twins , that every birthday is equally likely , and ignore leap years . take a moment to think about it . the answer may seem surprisingly low . in a group of 23 people , there 's a 50.73 % chance that two people will share the same birthday . but with 365 days in a year , how 's it possible that you need such a small group to get even odds of a shared birthday ? why is our intuition so wrong ? to figure out the answer , let 's look at one way a mathematician might calculate the odds of a birthday match . we can use a field of mathematics known as combinatorics , which deals with the likelihoods of different combinations . the first step is to flip the problem . trying to calculate the odds of a match directly is challenging because there are many ways you could get a birthday match in a group . instead , it 's easier to calculate the odds that everyone 's birthday is different . how does that help ? either there 's a birthday match in the group , or there is n't , so the odds of a match and the odds of no match must add up to 100 % . that means we can find the probability of a match by subtracting the probability of no match from 100 . to calculate the odds of no match , start small . calculate the odds that just one pair of people have different birthdays . one day of the year will be person a 's birthday , which leaves only 364 possible birthdays for person b . the probability of different birthdays for a and b , or any pair of people , is 364 out of 365 , about 0.997 , or 99.7 % , pretty high . bring in person c. the probability that she has a unique birthday in this small group is 363 out of 365 because there are two birthdates already accounted for by a and b . d 's odds will be 362 out of 365 , and so on , all the way down to w 's odds of 343 out of 365 . multiply all of those terms together , and you 'll get the probability that no one shares a birthday . this works out to 0.4927 , so there 's a 49.27 % chance that no one in the group of 23 people shares a birthday . when we subtract that from 100 , we get a 50.73 % chance of at least one birthday match , better than even odds . the key to such a high probability of a match in a relatively small group is the surprisingly large number of possible pairs . as a group grows , the number of possible combinations gets bigger much faster . a group of five people has ten possible pairs . each of the five people can be paired with any of the other four . half of those combinations are redundant because pairing person a with person b is the same as pairing b with a , so we divide by two . by the same reasoning , a group of ten people has 45 pairs , and a group of 23 has 253 . the number of pairs grows quadratically , meaning it 's proportional to the square of the number of people in the group . unfortunately , our brains are notoriously bad at intuitively grasping non-linear functions . so it seems improbable at first that 23 people could produce 253 possible pairs . once our brains accept that , the birthday problem makes more sense . every one of those 253 pairs is a chance for a birthday match . for the same reason , in a group of 70 people , there are 2,415 possible pairs , and the probability that two people have the same birthday is more than 99.9 % . the birthday problem is just one example where math can show that things that seem impossible , like the same person winning the lottery twice , actually are n't unlikely at all . sometimes coincidences are n't as coincidental as they seem .
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imagine a group of people . how big do you think the group would have to be before there 's more than a 50 % chance that two people in the group have the same birthday ?
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a group of 10 people has _____ pairwise combinations , while a group of 15 has _____ combinations .
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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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odd can also be used to describe a number that is somewhat higher than the given approximation – as in , for example , 50-odd years . how does this definition relate to the first ?
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there is a curse that has plagued humanity since ancient times . the greeks fought it by chewing aromatic resins , while the chinese resorted to egg shells . in the ancient jewish talmud , it 's even considered legal grounds for divorce . this horrible scourge is halitosis , otherwise known as bad breath . but what causes it , and why is it so universally terrifying ? well , think of some of the worst odors you can imagine , like garbage , feces or rotting meat . all of these smells come from the activity of microorganisms , particularly bacteria , and , as disgusting as it may sound , similar bacteria live in the moisture-rich environment of your mouth . do n't panic . the presence of bacteria in your body is not only normal , it 's actually vital for all sorts of things , like digestion and disease prevention . but like all living things , bacteria need to eat . the bacteria in your mouth feed off of mucus , food remnants , and dead tissue cells . in order to absorb nutrients through their cell membranes , they must break down the organic matter into much smaller molecules . for example , they 'll break proteins into their component amino acids and then break those down even further into various compounds . some of the foul-smelling byproducts of these reactions , such as hydrogen sulfide and cadaverine , escape into the air and waft their way towards unsuspecting noses . our sensitivity to these odors and interpretation of them as bad smells may be an evolutionary mechanism warning us of rotten food and the presence of disease . smell is one of our most intimate and primal senses , playing a huge role in our attraction to potential mates . in one poll , 59 % of men and 70 % of women said they would n't go on a date with someone who has bad breath , which may be why americans alone spend $ 1 billion a year on various breath products . fortunately , most bad breath is easily treated . the worst smelling byproducts come from gram-negative bacteria that live in the spaces between gums and teeth and on the back of the tongue . by brushing and flossing our teeth , using antibacterial mouthwash at bedtime , gently cleaning the back of the tongue with a plastic scraper and even just eating a healthy breakfast , we can remove many of these bacteria and their food sources . in some cases , these measures may not be enough due to dental problems , nasal conditions , or rarer ailments , such as liver disease and uncontrolled diabetes . behaviors like smoking and excessive alcohol consumption also have a very recognizable odor . regardless of cause , the bad smell almost always originates in the mouth and not the stomach or elsewhere in the body . but one of the biggest challenges lies in actually determining how our breath smells in the first place , and it 's unclear why . it may be that we 're too acclimatized to the smell inside our own mouths to judge it . and methods like cupping your hands over your mouth , or licking and smelling your wrist do n't work perfectly either . one study showed that even when people do this , they tend to rate the smell subjectively according to how bad they thought it was going to be . but there 's one simple , if socially difficult , way of finding out how your breath smells : just take a deep breath and ask a friend .
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but what causes it , and why is it so universally terrifying ? well , think of some of the worst odors you can imagine , like garbage , feces or rotting meat . all of these smells come from the activity of microorganisms , particularly bacteria , and , as disgusting as it may sound , similar bacteria live in the moisture-rich environment of your mouth .
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do you think that bacteria cause other body odors ? develop an experiment to find out .
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`` all men are created equal and they are endowed with the rights to life , liberty and the pursuit of happiness . '' not so fast , mr. jefferson ! these words from the declaration of independence , and the facts behind them , are well known . in june of 1776 , a little more than a year after the war against england began with the shots fired at lexington and concord , the continental congress was meeting in philadelphia to discuss american independence . after long debates , a resolution of independence was approved on july 2 , 1776 . america was free ! and men like john adams thought we would celebrate that date forever . but it was two days later that the gentlemen in congress voted to adopt the declaration of independence , largely written by thomas jefferson , offering all the reasons why the country should be free . more than 235 years later , we celebrate that day as america 's birthday . but there are some pieces of the story you may not know . first of all , thomas jefferson gets the credit for writing the declaration , but five men had been given the job to come up with a document explaining why america should be independent : robert livingston , roger sherman , benjamin franklin and john adams were all named first . and it was adams who suggested that the young , and little known , thomas jefferson join them because they needed a man from the influential virginia delegation , and adams thought jefferson was a much better writer than he was . second , though jefferson never used footnotes , or credited his sources , some of his memorable words and phrases were borrowed from other writers and slightly tweaked . then , franklin and adams offered a few suggestions . but the most important change came after the declaration was turned over to the full congress . for two days , a very unhappy thomas jefferson sat and fumed while his words were picked over . in the end , the congress made a few , minor word changes , and one big deletion . in the long list of charges that jefferson made against the king of england , the author of the declaration had included the idea that george the third was responsible for the slave trade , and was preventing america from ending slavery . that was not only untrue , but congress wanted no mention of slavery in the nation 's founding document . the reference was cut out before the declaration was approved and sent to the printer . but it leaves open the hard question : how could the men , who were about to sign a document , celebrating liberty and equality , accept a system in which some people owned others ? it is a question that would eventually bring the nation to civil war and one we can still ask today .
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not so fast , mr. jefferson ! these words from the declaration of independence , and the facts behind them , are well known . in june of 1776 , a little more than a year after the war against england began with the shots fired at lexington and concord , the continental congress was meeting in philadelphia to discuss american independence .
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according to the narrator , the assignment to write the declaration was assigned to :
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as the story goes , the legendary marksman william tell was forced into a cruel challenge by a corrupt lord . william 's son was to be executed unless william could shoot an apple off his head . william succeeded , but let 's imagine two variations on the tale . in the first variation , the lord hires a bandit to steal william 's trusty crossbow , so he is forced to borrow an inferior one from a peasant . however , the borrowed crossbow is n't adjusted perfectly , and william finds that his practice shots cluster in a tight spread beneath the bullseye . fortunately , he has time to correct for it before it 's too late . variation two : william begins to doubt his skills in the long hours before the challenge and his hand develops a tremor . his practice shots still cluster around the apple but in a random pattern . occasionally , he hits the apple , but with the wobble , there is no guarantee of a bullseye . he must settle his nervous hand and restore the certainty in his aim to save his son . at the heart of these variations are two terms often used interchangeably : accuracy and precision . the distinction between the two is actually critical for many scientific endeavours . accuracy involves how close you come to the correct result . your accuracy improves with tools that are calibrated correctly and that you 're well-trained on . precision , on the other hand , is how consistently you can get that result using the same method . your precision improves with more finely incremented tools that require less estimation . the story of the stolen crossbow was one of precision without accuracy . william got the same wrong result each time he fired . the variation with the shaky hand was one of accuracy without precision . william 's bolts clustered around the correct result , but without certainty of a bullseye for any given shot . you can probably get away with low accuracy or low precision in everyday tasks . but engineers and researchers often require accuracy on microscopic levels with a high certainty of being right every time . factories and labs increase precision through better equipment and more detailed procedures . these improvements can be expensive , so managers must decide what the acceptable uncertainty for each project is . however , investments in precision can take us beyond what was previously possible , even as far as mars . it may surprise you that nasa does not know exactly where their probes are going to touch down on another planet . predicting where they will land requires extensive calculations fed by measurements that do n't always have a precise answer . how does the martian atmosphere 's density change at different elevations ? what angle will the probe hit the atmosphere at ? what will be the speed of the probe upon entry ? computer simulators run thousands of different landing scenarios , mixing and matching values for all of the variables . weighing all the possibilities , the computer spits out the potential area of impact in the form of a landing ellipse . in 1976 , the landing ellipse for the mars viking lander was 62 x 174 miles , nearly the area of new jersey . with such a limitation , nasa had to ignore many interesting but risky landing areas . since then , new information about the martian atmosphere , improved spacecraft technology , and more powerful computer simulations have drastically reduced uncertainty . in 2012 , the landing ellipse for the curiosity lander was only 4 miles wide by 12 miles long , an area more than 200 times smaller than viking 's . this allowed nasa to target a specific spot in gale crater , a previously un-landable area of high scientific interest . while we ultimately strive for accuracy , precision reflects our certainty of reliably achieving it . with these two principles in mind , we can shoot for the stars and be confident of hitting them every time .
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computer simulators run thousands of different landing scenarios , mixing and matching values for all of the variables . weighing all the possibilities , the computer spits out the potential area of impact in the form of a landing ellipse . in 1976 , the landing ellipse for the mars viking lander was 62 x 174 miles , nearly the area of new jersey .
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you are setting up a drill to make a hole in a circuit board . which of the following is not a potential advantage of your efforts ?
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i want to tell you all about a piece of american history that is so secret , that nobody has done anything about it for 167 years , until right now . and the way that we 're going to uncover this vestigial organ of america past is by asking this question : why ? as we all know -- ( laughter ) we are in the middle of another presidential election , hotly contested , as you can see . ( laughter ) but what you may not know is that american voter turnout ranks near the bottom of all countries in the entire world , 138th of 172 nations . this is the world 's most famous democracy . so ... why do we vote on tuesday ? does anybody know ? and as a matter of fact , michigan and arizona are voting today . here 's the answer : absolutely no good reason whatsoever . ( laughter ) i 'm not joking . you will not find the answer in the declaration of independence , nor will you find it in the constitution . it is just a stupid law from 1845 . ( laughter ) in 1845 , americans traveled by horse and buggy . as did i , evidently . it took a day to get to the county seat to vote , a day to get back , and you could n't travel on the sabbath , so , tuesday it was . i do n't often travel by horse and buggy , i would imagine most of you do n't , so when i found out about this , i was fascinated . i linked up with a group called , what else -- `` why tuesday ? '' to go and ask our nation 's most prominent elected leaders if they knew the answer to the question , `` why do we vote on tuesday ? '' ( video ) rick santorum : anybody knows ? ok , i 'm going to be stumped on this . anybody knows why we vote on tuesdays ? jacob soboroff : do you happen to know ? ron paul : on tuesdays ? js : the day after the first monday in november . rp : i do n't know how that originated . js : do you know why we do vote on tuesday ? newt gingrich : no . dick lugar : no , i do n't . ( laughter ) dianne feinstein : i do n't . darrell issa : no . john kerry : in truth , really , i 'm not sure why . js : ok , thanks very much . ( laughter ) js : these are people that live for election day , yet they do n't know why we vote on that very day . ( laughter ) chris rock said , `` they do n't want you to vote . if they did , we would n't vote on a tuesday in november . have you ever thrown a party on a tuesday ? ( laughter ) no , of course not . nobody would show up . '' ( laughter ) here 's the cool part . because we asked this question , `` why tuesday ? '' there is now this bill , the weekend voting act in the congress of the united states of america . it would move election day from tuesday to the weekend , so that -- duh -- more people can vote . ( applause ) it has only taken 167 years , but finally , we are on the verge of changing american history . thank you very much . ( applause ) thanks a lot . ( applause )
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ok , i 'm going to be stumped on this . anybody knows why we vote on tuesdays ? jacob soboroff : do you happen to know ?
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think about the logistical needs to be able to vote on tuesdays ? how does voting on tuesdays impact or not impact different demographics of people ?
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( music ) eight to be great : the eight traits successful people have in common . number two : work . when i was interviewing all these successful people , they kept telling me how hard they worked . and i remember standing there thinking , `` ah , jeez , another comment about work ? why do n't they tell me the real secret to their success ? '' then finally i realized , hard work is a real secret to their success . all successful people work very hard . martha stewart said to me , `` i 'm a real hard worker . i work and work and work all the time . '' media tycoon rupert murdoch said , `` it 's all hard work . nothing comes easily . but i have a lot of fun . '' did he say fun ? yes . successful people have fun working . that 's why i say they 're not really workaholics . they 're workafrolics . jim pattison , chairman of the jim pattison group , is a workafrolic . he says , `` business is my recreation . i 'd rather go to our factories and meet with our people than go to the beach , i can tell you that . '' dave lavery , the nasa whiz who builds those robots for mars , said to me , `` we work our fingers to the bone . but it does n't seem like work . it 's fun . it 's what we want to do . we do n't want to put things down and go home . '' bill gates is a workafrolic . even after he was a multimillionaire , he worked most nights until 10 p.m. , and only took two weeks off in seven years . and he probably spent them on his computer . oprah is a workafrolic . she says , `` i never see daylight . i 'd come into work at 5:30 in the morning when it was dark , and leave at 7 or 8 when it was dark . '' i 'm a workafrolic . and over the years , i 've gone through many days and even weeks without much sleep , just because i was having so much fun . and i got ta admit , at times like that you say to yourself , `` am i the only one working this hard ? '' because there 's a myth it comes easy to some people . you turn on the tv , nobody 's working that hard . a guy like chris rock stands up on stage , tells a few jokes . what 's hard about that ? but even chris says , `` i was n't the funniest guy growing up , but i was the guy who worked on being funny the hardest . '' trust me . i 've interviewed over 500 successful people , not one of them said it came easy , even though they were doing what they loved . we tend to underestimate work and overestimate talent . but in the end , work tops talent . arthur benjamin , america 's best math whiz , said to me , `` i think numbers and i have always gotten along . but i 'm sure my 'talent ' is just due to the time and hours and work that i 've put into it . '' many talented people do n't achieve as much success as they could , unfortunately , because they sit back on their talent and never learn to work hard . that 's what happened to michael jordan when he first started playing basketball . he had the talent , but he was n't putting in the work , and the coach actually cut him from the high school basketball team . boy , that was a wake-up call . he says , `` i was very disappointed . i started working on my game the day after i was cut . '' and he soon became the hardest working player in basketball , who made fun of the other players who were n't working hard . and that hard work is what made him the greatest basketball player of all time . so i 'd say the real gift is n't talent , it 's the ability to work hard . and we tend to underestimate work and overestimate smarts . but in the end , work wins over smarts . in fact , many successful people are n't the smartest , they just work the hardest . francois parenteau , who business week called the top independent analyst on wall street , said to me , `` i 'm certainly not that smart . i ca n't even remember my own zip code . '' but he also says , `` work is a big part of my life . i think about investments pretty much 24 hours a day , seven days a week . '' nez hallett iii is ceo of smart wireless , and i thought , that 's ironic because he told me he 's not that smart . he says , `` i graduated from high school with a c average , and college with a c-minus average . '' but now the smart phd 's are reporting to him . how did he do it ? he said , `` if you 're going to be successful at anything , the key thing is to work hard . '' i 'm not smart . as proof , here 's my actual 12th grade report card . it was the only one my parents ever kept . do n't ask me why they kept it ; it 's nothing to brag about . as you can see , i was a c student , not an a student . i do n't think i 'd even make it into college these days . so how did i achieve some success and wealth ? i just worked hard , many 60- to 80-hour weeks . and now i know i 'm not alone . thomas stanley studied hundreds of millionaires , and he discovered most millionaires were n't a students , did n't score high on tests and teachers did n't think they 'd ever succeed . but they did succeed , because they worked hard . so the good news is if you 're not the smartest , if you 're a c student , not an a student , the really good news is you can still succeed . because the word `` success '' has two c 's and no a 's . ( laughter ) you can still succeed as long as you work hard . and what if you are smart ? well , i 'm sorry , there 's absolutely no hope for you . because many smart people do n't achieve as much success as they could , unfortunately , because they rest on their smarts and never learn to work hard . jeong kim , president of lucent technologies , says , `` people who are the smartest sometimes do n't realize their full potential , because things get too easy , so they do n't push themselves hard . '' after a talk i gave at one of the world 's top 10 business schools , a man came up to me and said , `` you know , when i got my mba here a few years ago , i was one of the smartest people in the class . i thought i had it made . so after i graduated , i sat back and i did n't work hard . and i went downhill . and now , at this point in my life , i 've gone nowhere . i have n't achieved any success at all . '' he said , `` thanks for the wake-up call . now i know what i need to do . i need to work . '' so the bottom line is , whether you 're smart or not , whether you 're talented or not , just keep working . ( applause )
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i 'd rather go to our factories and meet with our people than go to the beach , i can tell you that . '' dave lavery , the nasa whiz who builds those robots for mars , said to me , `` we work our fingers to the bone . but it does n't seem like work .
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finish this quote by dave lavery : “ we work our fingers to the bone… ”
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we like to think of romantic feelings as spontaneous and indescribable things that come from the heart . but it 's actually your brain running a complex series of calculations within a matter of seconds that 's responsible for determining attraction . does n't sound quite as poetic , does it ? but just because the calculations are happening in your brain does n't mean those warm , fuzzy feelings are all in your head . in fact , all five of your senses play a role , each able to vote for , or veto , a budding attraction . the eyes are the first components in attraction . many visual beauty standards vary between cultures and eras , and signs of youth , fertility and good health , such as long lustrous hair , or smooth , scar-free skin , are almost always in demand because they 're associated with reproductive fitness . and when the eyes spot something they like , our instinct is to move closer so the other senses can investigate . the nose 's contribution to romance is more than noticing perfume or cologne . it 's able to pick up on natural chemical signals known as pheromones . these not only convey important physical or genetic information about their source but are able to activate a physiological or behavioral response in the recipient . in one study , a group of women at different points in their ovulation cycles wore the same t-shirts for three nights . after male volunteers were randomly assigned to smell either one of the worn shirts , or a new unworn one , saliva samples showed an increase in testosterone in those who had smelled a shirt worn by an ovulating woman . such a testosterone boost may give a man the nudge to pursue a woman he might not have otherwise noticed . a woman 's nose is particularly attuned to mhc molecules , which are used to fight disease . in this case , opposites attract . when a study asked women to smell t-shirts that had been worn by different men , they preferred the odors of those whose mhc molecules differed from theirs . this makes sense . genes that result in a greater variety of immunities may give offspring a major survival advantage . our ears also determine attraction . men prefer females with high-pitched , breathy voices , and wide formant spacing , correlated with smaller body size . while women prefer low-pitched voices with a narrow formant spacing that suggest a larger body size . and not surprisingly , touch turns out to be crucial for romance . in this experiment , not realizing the study had begun , participants were asked to briefly hold the coffee , either hot or iced . later , the participants read a story about a hypothetical person , and were asked to rate their personality . those who had held the hot cup of coffee perceived the person in the story as happier , more social , more generous and better-natured than those who had held the cup of iced coffee , who rated the person as cold , stoic , and unaffectionate . if a potential mate has managed to pass all these tests , there 's still one more : the infamous first kiss , a rich and complex exchange of tactile and chemical cues , such as the smell of one 's breath , and the taste of their mouth . this magical moment is so critical that a majority of men and women have reported losing their attraction to someone after a bad first kiss . once attraction is confirmed , your bloodstream is flooded with norepinephrine , activating your fight or flight system . your heart beats faster , your pupils dilate , and your body releases glucose for additional energy , not because you 're in danger but because your body is telling you that something important is happening . to help you focus , norepinephrine creates a sort of tunnel vision , blocking out surrounding distractions , possibly even warping your sense of time , and enhancing your memory . this might explain why people never forget their first kiss . the idea of so much of our attraction being influenced by chemicals and evolutionary biology may seem cold and scientific rather than romantic , but the next time you see someone you like , try to appreciate how your entire body is playing matchmaker to decide if that beautiful stranger is right for you .
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this magical moment is so critical that a majority of men and women have reported losing their attraction to someone after a bad first kiss . once attraction is confirmed , your bloodstream is flooded with norepinephrine , activating your fight or flight system . your heart beats faster , your pupils dilate , and your body releases glucose for additional energy , not because you 're in danger but because your body is telling you that something important is happening .
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once attraction is confirmed , your bloodstream floods with what ?
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we check the time every day , all day long . but did you ever wonder - where did telling time come from ? why does it matter what time it is ? who determined the clock and why in the world are there so many different time zones ? the first form of telling time was the sundial and the earliest sundials known from the archaeological record are obelisks from nearly 5,000 years ago . sundials indicate the time by casting a shadow onto a surface . the object that casts the shadow is a stick in the center known as a gnomon . a well-constructed sundial can measure time with remarkable accuracy , and sundials were used to monitor the performance of clocks until the modern era . but sundials have their limitations too . obviously they require the sun to shine , so they do n't work at all during the night when it 's dark . many different devices have been used over the years to estimate the passage of time : candles and sticks of incense that burn down at fairly predictable speeds have been used , along with the hourglass . hourglasses are devices in which fine sand pours through a tiny hole at a constant rate and indicates a predetermined passage of an arbitrary period of time . the origin of the hourglass is uncertain , although beginning in the 14th century , the hourglass was used commonly , especially on board ships . the motion of the boat on the water did not affect the hourglass , unlike other time-measuring devices . the mechanical clock was invented in the 13th century which sparked a big change in traditional timekeeping methods . this modern clock relied on the swing of a pendulum or the vibration of a quartz crystal , which was far more accurate than sand or candles . today , the basis for scientific time is a continuous count of seconds based on atomic clocks all around the world , known as the international atomic time . why does it matter that we keep track of time ? well , time regulates our daily lives and makes it possible to accurately communicate with people all over the world . without a time system , we would have many challenges in farming , social structures , communication , and business . take the american railroad system , for example . in the mid-19th century , each railroad used its own standard time generally based on the local time of its headquarters , and the railroad 's train schedules were published using its own time . some major railroad junctions served by several different railroads had a separate clock for each railroad , each showing a different time . the distance between new york and boston is about 2 degrees , or 8 minutes , which can be the difference between making or missing your train connection . if the difference between new york and boston is 8 minutes , imagine the difference between boston and australia . the use of time zones irons out these differences and makes communication significantly smoother . a time zone is a region on earth that has a uniform standard time . there are 40 time zones on land because the earliest and latest time zones are 26 hours apart . any given calendar date exists at some point on the globe for 50 hours . so the next time someone asks you `` what time is it ? '' your answer may be a whole lot more complicated than it used to be .
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hourglasses are devices in which fine sand pours through a tiny hole at a constant rate and indicates a predetermined passage of an arbitrary period of time . the origin of the hourglass is uncertain , although beginning in the 14th century , the hourglass was used commonly , especially on board ships . the motion of the boat on the water did not affect the hourglass , unlike other time-measuring devices .
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the origin of the hourglass is uncertain although beginning in the 14th century it was especially common to see the hourglass used :
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translator : andrea mcdonough reviewer : bedirhan cinar as any current or past geometry student knows , the father of geometry was euclid , a greek mathematician who lived in alexandria , egypt , around 300 b.c.e . euclid is known as the author of a singularly influential work known as `` elements . '' you think your math book is long ? euclid 's `` elements '' is 13 volumes full of just geometry . in `` elements , '' euclid structured and supplemented the work of many mathematicians that came before him , such as pythagoras , eudoxus , hippocrates and others . euclid laid it all out as a logical system of proof built up from a set of definitions , common notions , and his five famous postulates . four of these postulates are very simple and straightforward , two points determine a line , for example . the fifth one , however , is the seed that grows our story . this fifth mysterious postulate is known simply as the parallel postulate . you see , unlike the first four , the fifth postulate is worded in a very convoluted way . euclid 's version states that , `` if a line falls on two other lines so that the measure of the two interior angles on the same side of the transversal add up to less than two right angles , then the lines eventually intersect on that side , and therefore are not parallel . '' wow , that is a mouthful ! here 's the simpler , more familiar version : `` in a plane , through any point not on a given line , only one new line can be drawn that 's parallel to the original one . '' many mathematicians over the centuries tried to prove the parallel postulate from the other four , but were n't able to do so . in the process , they began looking at what would happen logically if the fifth postulate were actually not true . some of the greatest minds in the history of mathematics ask this question , people like ibn al-haytham , omar khayyam , nasir al-din al-tusi , giovanni saccheri , jános bolyai , carl gauss , and nikolai lobachevsky . they all experimented with negating the parallel postulate , only to discover that this gave rise to entire alternative geometries . these geometries became collectively known as non-euclidean geometries . we 'll leave the details of these different geometries for another lesson . the main difference depends on the curvature of the surface upon which the lines are constructed . turns out euclid did not tell us the entire story in `` elements , '' and merely described one possible way to look at the universe . it all depends on the context of what you 're looking at . flat surfaces behave one way , while positively and negatively curved surfaces display very different characteristics . at first these alternative geometries seemed strange , but were soon found to be equally adept at describing the world around us . navigating our planet requires elliptical geometry while the much of the art of m.c . escher displays hyperbolic geometry . albert einstein used non-euclidean geometry as well to describe how space-time becomes warped in the presence of matter , as part of his general theory of relativity . the big mystery is whether euclid had any inkling of the existence of these different geometries when he wrote his postulate . we may never know , but it 's hard to believe he had no idea whatsoever of their nature , being the great intellect that he was and understanding the field as thoroughly as he did . maybe he did know and he wrote the postulate in such a way as to leave curious minds after him to flush out the details . if so , he 's probably pleased . these discoveries could never have been made without gifted , progressive thinkers able to suspend their preconceived notions and think outside of what they 've been taught . we , too , must be willing at times to put aside our preconceived notions and physical experiences and look at the larger picture , or we risk not seeing the rest of the story .
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the main difference depends on the curvature of the surface upon which the lines are constructed . turns out euclid did not tell us the entire story in `` elements , '' and merely described one possible way to look at the universe . it all depends on the context of what you 're looking at .
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if you wanted to lead future generations to take a deep look into the nature of the universe to discover things that you suspected were worthy of discovering , what kinds of things would you do to `` covertly '' help guide them to that end ?
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caffeine a legal stimulant that most of us are pretty familiar with , many of us use every day , and some of us are addicted to . if you are a caffeine user , you probably know your limits . for me one small cup of coffee in the morning can help keep me alert and focused , whereas two small cups of coffee in the morning can turn me into a cat on catnip . well for the purposes of this video and to best demonstrate the physical and mental effects of caffeine , i 'm going to get very very caffeinated very very fast . for science . go big or go home . caffeine is a stimulant drug that acts on your central nervous system . because caffeine is both lipid and water soluble it can easily pass through the blood-brain barrier and act on the interior of your brain once there , caffeine works by diminishing the effect of a neurotransmitter called adenosine . adenosine acts as a suppressor for your nervous system , reducing neural activity and slowing everything down . caffeine and adenosine have similar shapes so caffeine can bind to the same neuroreceptors that adenosine does . but because caffeine is not adenosine , it does n't turn these neuroreceptors on . this is called competitive inhibition . caffeine competes with adenosine to bind with the same receptors , and because caffeine is bound , adenosine can not bind and its effects are inhibited . long story short , caffeine prevents adenosine from slowing down your nervous system . so this explain part of why you feel more awake , alert and active with caffeine flowing through your veins . but adenosine inhibition is n't the only thing that caffeine does . oh no . caffeine also stimulates the production of adrenaline or epinephrine . adrenaline is a pretty well known hormone involved in the fight-or-flight response . it causes all sort of physiological reactions ! it increases your heart rate , increases the blood flow to your muscles , opens up your airways , causes your blood pressure to rise , and also causes you 're your liver to release extra sugar into your blood stream for an added boost of energy . it also causes your muscle to tighten up , which would be useful if you were the lone human on the savannah , deciding or not to fight or flee from that lion over the distance , but as a modern twenty something sitting in from of my camera , it just give me the jitters . finally caffeine also plays with the dopamine levels in your brain . awesome , yeah . caffeine increases the amount of dopamine present in your brain by slowing down its reabsorption , much in the same way that cocaine increases the amount of dopamine present by slowing down how quickly it can be sucked back into your brain tissue . this means that caffeine also makes you feel good and this interaction with dopamine is how you can actually build a caffeine addiction . so now you 're a happy , jittery , fight or flight ready bundle caffeine ! now what ? well the now what really depends on how your specific body metabolizes caffeine . the average half-life of caffeine in the human body is about six hours . so this means that if you have two hundred milligrams of caffeine in your average cup of coffee at 9am in the morning , then 6 hours later half of that will be left , so at 3pm you will have a hundred milligrams of caffeine left , and then another 6 hours later you will have half of the hundred you will have half of the hundred so you will have 50 milligrams of caffeine left at 9 o'clock at night . but dude , who stops at just one cup of coffee ? not this chick . so how much caffeine is too much caffeine ? a lethal dose of caffeine is about two hundred milligrams per kilogram so it would take about nine thousand five hundred milligrams of caffeine to kill me . now , there are about two hundred milligrams of caffeine in a standard cup of coffee , so that 's about forty eight cups of coffee , which is a surprisingly low number , but i would have to drink all 48 of those before my body started to metabolize the caffeine , which means i would literally have to chug 48 cups of coffee . i literally would n't be able to drink that much coffee , both because my stomach could n't hold that volume of liquid and also because as every coffee drinker knows , caffeine is a diuretic . before i got to cup forty anyways , the stimulant effect of caffeine would be jacked up so high that that the alertness and awakeness would be transformed into mania , disorientation and hallucinations ... great ! what would eventually kill you would be ventricular fibrillation , which basically means that your heart would caffeine jitter itself to death . so moral of the story , caffeine is a drug . it is a stimulant that has some pretty noticeable effects on your body , can cause addiction , and , in high enough doses , can kill you . so caffeinate wisely ! go forth , do science ! my hand is actually not shaking too bad right now . do n't try this at home , i know a lot of people do drink that much caffeine all on one day and sometimes i approach it , but i certainly do n't do it over the span of 20 minutes . i actually do n't feel as terrible as i thought i would have after that amount , but i certainly do n't feel good either .
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but because caffeine is not adenosine , it does n't turn these neuroreceptors on . this is called competitive inhibition . caffeine competes with adenosine to bind with the same receptors , and because caffeine is bound , adenosine can not bind and its effects are inhibited .
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what is competitive inhibition ? what example of competitive inhibition is given in the video ?
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translator : andrea mcdonough reviewer : jessica ruby one of the reasons that i 'm fascinated by the ocean is that it 's really an alien world on our own planet . from our perspective , sitting on the shoreline or even out on a boat , we 're given only the tiniest glimpses at the real action that 's happening beneath the surface of the waves . and even if you were able to go down there , you would n't see very much because light does n't travel very far in the ocean . so , to answer questions about how the ocean works , in my research , we use sound . we use sonars that send out pulses of sound made up of a number of different frequencies , or pitches , that are shown with different colors . that sound bounces off things in the habitat and comes back to us . if it were to bounce off this dolphin , the signal we got back would look very much like the one we sent out where all the colors are represented pretty evenly . however , if we were to bounce that same sound off of a squid , which in this case is about the same size as that dolphin , we 'd instead only get the lowest frequencies back strongly , shown here in the red . and if we were to look at the prey of that squid , the tiny little krill that they 're eating , we would instead only get the highest frequencies back . and so by looking at this , we can tell what kinds of animals are in the ocean , we can look at how dense they are , where they are distributed , look at their interactions and even their behavior to start to study the ecology of the ocean . when we do that , we come up with something sort of surprising : on average , there is n't very much food in the ocean . so even in places which we think of as rich , the coasts , we 're talking about two parts of every million contain food . so what does that mean ? well , that means that in the volume of this theater , there would be one tub of movie theater popcorn available to be eaten . but of course , it would n't be collected for you neatly in this bucket . instead , you 'd actually have to be swimming through this entire volume willy wonka style , picking off individual kernels of popcorn , or perhaps if you were lucky , getting a hold of a few small clumps . but , of course , if you were in the ocean , this popcorn would n't be sitting here waiting for you to eat it . it would , instead , be trying to avoid becoming your dinner . so i want to know how do animals solve this challenge ? we 're going to talk about animals in the bering sea . this is where you may have see `` deadliest catch '' framed , in the northernmost part of the pacific ocean . we 've been looking specifically at krill , one of the most important food items in this habitat . these half-inch long shrimp-like critters are about the caloric equivalent of a heavily buttered kernel of popcorn . and they 're eaten by everything from birds and fur seals that pick them up one at a time to large whales that engulf them in huge mouthfuls . so i 'm going to focus in the area around three breeding colonies for birds and fur seals in the southeastern bering sea . and this is a map of that habitat that we made making maps of food the way we 've always made maps of food . this is how many krill are in this area of the ocean . red areas represent lots of krill and purple basically none . and you can see that around the northern two most islands , which are highlighted with white circles because they are so tiny , it looks like there 's a lot of food to be eaten . and yet , the fur seals and birds on these islands are crashing . their populations are declining despite decades of protection . and while on that southern island at the very bottom of the screen it does n't look like there 's anything to eat , those populations are doing incredibly well . so this left us with a dilemma . our observations of food do n't make any sense in the context of our observations of these animals . so we started to think about how we could do this differently . and this map shows not how many krill there are , but how many clumps of krill there are , how aggregated are they . and what you get is a very different picture of the landscape . now that southern island looks like a pretty good place to be , and when we combine this with other information about prey , it starts to explain the population observations . but we can also ask that question differently . we can have the animals tell us what 's important . by tagging and tracking these animals and looking at how they use this habitat , we are able to say , `` what matters to you ? '' about the prey . and what they 've told us is that how many krill there are really is n't important . it is how closely spaced those krill are because that 's how they are able to make a living . we see the same pattern when we look in very different ocean , further south in the pacific , in the warm waters around the hawaiian islands . so a very different habitat , and yet the same story . under some conditions , the physics and the nutrients , the fertilizer , set up aggregations in the plants , the phytoplankton . and when that happens , these very dense aggregations of phytoplankton attract their predators , which themselves form very dense layers . that changes the behavior and distribution of their predators as well , starting to set up how this entire ecosystem functions . finally , the predators that eat these small fish , shrimp , and squid , we 're talking about two- to three-inch long prey here , changes how they use their habitat and how they forage . and so we see changes in the spinner dolphins that are related to the changes we 're seeing in the plant life . and just by measuring the plants , we can actually predict very well what 's going to happen in the top predator three steps away in the food web . but what 's interesting is that even the densest aggregations of their prey are n't enough for spinner dolphins to make it . it 's a pretty tough life there in the ocean . so these animals actually work together to herd their prey into even denser aggregations , starting with patches that they find in the first place . and that 's what you 're going to see in this visualization . we have a group of 20 dolphins , you notice they 're all set up in pairs , that are working together to basically bulldoze prey to accumulate it on top of itself . and once they do that , they form a circle around that prey to maintain that really dense patch that is a couple thousand times higher density than the background that they started with before individual pairs of dolphins start to take turns feeding inside this circle of prey that they 've created . and so , this work is showing us that animals can first give us the answers that aggregation is critical to how they make their living . and by looking more deeply at the ocean , we 're starting to understand our interactions with it and finding more effective ways of conserving it . thank you .
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and just by measuring the plants , we can actually predict very well what 's going to happen in the top predator three steps away in the food web . but what 's interesting is that even the densest aggregations of their prey are n't enough for spinner dolphins to make it . it 's a pretty tough life there in the ocean .
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how do the spinner dolphins create an easier way to eat ?
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once upon a time , south america lived harmoniously alongside africa until a crack in the earth drove the two continents apart . this breakup began about 200 million years ago during the separation of the supercontinent known as pangaea . their proximity back then explains why the same plant fossils and reptile fossils , like the mesosaurus , can be found on the south american east coast and african west coast . however , this evidence does not account for how the continents moved apart . for that , we 'll need to take a close look at the earth below our feet . though you may not realize it , the ground below you is traveling across the earth at a rate of about 10 cm/year , or the speed at which your fingernails grow . this is due to plate tectonics , or the large-scale movement of earth 's continents . the motion occurs within the top two layers of the earth 's mantle , the lithosphere and asthenosphere . the lithosphere , which includes the crust and uppermost mantle , comprises the land around you . beneath the lithosphere is the asthenosphere the highly viscous but solid rock portion of the upper mantle . it 's between 80 and 200 km below the earth 's surface . while the asthenosphere wraps around the earth 's core as one connected region , the lithosphere is separated on top into tectonic plates . there are seven primary tectonic plates that compose the shape of the planet we know today . like the other smaller tectonic plates , the primary plates are about 100 km thick and are composed of one or two layers : continental crust and oceanic crust . continental crust forms the continents and areas of shallow water close to their shores , whereas oceanic crust forms the ocean basins . the transition from the granitic continental crust to the basaltic oceanic crust occurs beyond the continentel shelf , in which the shore suddenly slopes down towards the ocean floor . the south american plate is an example of a tectonic plate made of two crusts : the continent we know from today 's map and a large region of the atlantic ocean around it . collectively comprising the lithosphere , these plates are brittler and stiffer than the heated , malleable layer of the asthenosphere below . because of this , the tectonic plates float on top of this layer , independently of one another . the speed and direction in which these tectonic plates move depends on the temperature and pressure of the asthenosphere below . scientists are still trying to nail down the driving forces behind this movement , with some theories pointing towards mantle convection , while others are examining the influence of the earth 's rotation and gravitational pull . though the mechanics have not been sorted out , the scientific community agrees that our tectonic plates are moving and have been for billions of years . because these plates move independently , a fair amount of pushing and pulling between the plates occurs . the first type of interaction is a divergent boundary , in which two plates move away from one another . we see this in the mid-atlantic ridge between south america and africa . the next interaction is when two plates collide , known as a convergent boundary . in this instance , the land is pushed upward to form large mountain ranges , like the himalayas . in fact , the indian plate is still colliding with the eurasian plate , which is why mount everest grows one cm/year . finally , there 's the transform boundaries , where two plates scrape past one another . the grinding of the transform boundary leads to many earthquakes , which is what happens in the 810 mile-long san andreas fault . the moving earth is unstoppable , and , while a shift of 10 cm/year may not seem like a lot , over millions of years our planet will continue to dramatically change . mountains will rise , shorelines will recede , islands will pop up . in fact , one projected map shows the cities of los angeles and san francisco on top of each other . maybe south america and africa will come together again , too . only time will tell .
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though you may not realize it , the ground below you is traveling across the earth at a rate of about 10 cm/year , or the speed at which your fingernails grow . this is due to plate tectonics , or the large-scale movement of earth 's continents . the motion occurs within the top two layers of the earth 's mantle , the lithosphere and asthenosphere . the lithosphere , which includes the crust and uppermost mantle , comprises the land around you .
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what are the different layers of the earth , and how do they interact ?
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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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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 !
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the average us teenager spends ____ hours per week connected to some kind of media device .
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testing , testing , one , two , three . when your band is trying to perform , feedback is an annoying obstacle , but in the grand orchestra of nature , feedback is not only beneficial , it 's what makes everything work . what exactly is feedback ? the key element , whether in sound , the environment or social science , is a phenomenon called mutual causal interaction , where x affects y , y affects x , and so on , creating an ongoing process called a feedback loop . and the natural world is full of these mechanisms formed by the links between living and nonliving things that build resilience by governing the way populations and food webs respond to events . when plants die , the dead material enriches the soil with humus , a stable mass of organic matter , providing moisture and nutrients for other plants to grow . the more plants grow and die , the more humus is produced , allowing even more plants to grow , and so on . this is an example of positive feedback , an essential force in the buildup of ecosystems . but it 's not called positive feedback because it 's beneficial . rather , it is positive because it amplifies a particular effect or change from previous conditions . these positive , or amplifying , loops can also be harmful , like when removing a forest makes it vulnerable to erosion , which removes organic matter and nutrients from the earth , leaving less plants to anchor the soil , and leading to more erosion . in contrast , negative feedback diminishes or counteracts changes in an ecosystem to maintain a more stable balance . consider predators and their prey . when lynx eat snowshoe hares , they reduce their population , but this drop in the lynx 's food source will soon cause their own population to decline , reducing the predation rate and allowing the hare population to increase again . the ongoing cycle creates an up and down wavelike pattern , maintaining a long-term equilibrium and allowing a food chain to persist over time . feedback processes might seem counterintuitive because many of us are used to more predictable linear scenarios of cause and effect . for instance , it seems simple enough that spraying pesticides would help plants grow by killing pest insects , but it may trigger a host of other unexpected reactions . for example , if spraying pushes down the insect population , its predators will have less food . as their population dips , the reduced predation would allow the insect population to rise , counteracting the effects of our pesticides . note that each feedback is the product of the links in the loop . add one negative link and it will reverse the feedback force entirely , and one weak link will reduce the effect of the entire feedback considerably . lose a link , and the whole loop is broken . but this is only a simple example , since natural communities consist not of separate food chains , but networks of interactions . feedback loops will often be indirect , occurring through longer chains . a food web containing twenty populations can generate thousands of loops of up to twenty links in length . but instead of forming a disordered cacophany , feedback loops in ecological systems play together , creating regular patterns just like multiple instruments , coming together to create a complex but harmonious piece of music . wide-ranging negative feedbacks keep the positive feedbacks in check , like drums maintaining a rhythm . you can look at the way a particular ecosystem functions within its unique habitat as representing its trademark sound . ocean environments dominated by predator-prey interactions , and strong negative and positive loops stabilized by self-damping feedback , are powerful and loud , with many oscillations . desert ecosystems , where the turn over of biomass is slow , and the weak feedbacks loops through dead matter are more like a constant drone . and the tropical rainforest , with its great diversity of species , high nutrient turnover , and strong feedbacks among both living and dead matter , is like a lush panoply of sounds . despite their stabilizing effects , many of these habitats and their ecosystems develop and change over time , as do the harmonies they create . deforestation may turn lush tropics into a barren patch , like a successful ensemble breaking up after losing its star performers . but an abandoned patch of farmland may also become a forest over time , like a garage band growing into a magnificent orchestra .
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when your band is trying to perform , feedback is an annoying obstacle , but in the grand orchestra of nature , feedback is not only beneficial , it 's what makes everything work . what exactly is feedback ? the key element , whether in sound , the environment or social science , is a phenomenon called mutual causal interaction , where x affects y , y affects x , and so on , creating an ongoing process called a feedback loop .
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the strength of a feedback loop is ________ .
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translator : andrea mcdonough reviewer : bedirhan cinar have you ever wondered how things are built within our bodies ? why our bodies can regrow and repair themselves , and how we can pass on genes from one generation to the next ? yet , none of our man-made objects have these traits ; they 're simply thrown away when they break and they definitely ca n't reproduce . the answer lies in something called self assembly . self assembly is a system where unordered parts come together in an organized structure , completely on their own . this means that a pile of parts on your desk should , in theory , be able to move around on their own , find one another , and build something useful . this seems impossible , like transformers or the sandman , but it 's exactly how our bodies are built , how our immune system works , and why we can reproduce . self assembly is the factory and copy machines within our bodies that make proteins fold and dna replicate . it 's a process that not only happens in the biological and chemical world , but is a phenomenon that can be seen from magnets to snowflakes , robotics , social networks , the formations of cities and galaxies , to name just a few . in biology and chemistry , self assembly is everywhere , from atomic interactions , cellular replication to dna , rna , and protein folding . proteins are like bicycle chains with sequences of amino acid links . they self assemble into 3-d structures because of the interaction between the amino acids along the chain , as well as the relationship between the chain and the environment . these forces make the flexible chain fold into a 3-d shape that governs the function in the protein . viruses , on the other hand , are like soccer balls . they 're made up of a series of sub-units with specific shapes . those shapes have attraction to one another , so they fit together in precise ways . image you want to build a perfect sphere . it turns out that making a precise sphere through traditional means is actually quite difficult . alternatively , you could try to self assemble the sphere . one way would be to inflate the sphere like a bubble or a balloon . another option would be to create many identical pieces that would come together to make a perfect sphere . you could try to put the pieces together one-by-one , but it might take a long time and you would still have human errors . instead you could design a connection between the components like magnets and dump them into a container . when you shook the container , all the parts would find one another and build the sphere for you . self assembly is being used as a new design , science , and engineering tool for making the next generation of technologies easier to build , more adaptive , and less reliant on fossil fuels . scientists are now making molecular microchips for computers where small , molecular elements are given the right conditions to form themselves into organized pathways . similarly , we can now use self assembly as a way to make 3-d structures with dna , like capsules that could deliver drugs inside the body , releasing them only if certain conditions are met . soon , self assembly will be used for larger applications , where materials can repair themselves , water pipes can reconfigure on demand , buildings can adapt on their own to environment or dynamic loading , and space structures can self assemble without humans . imagine if our factories were more like organisms or brains and our construction sites were like gardens that grow and adapt independently . the possibilities are endless and it 's now up to us to design a better world through self assembly .
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yet , none of our man-made objects have these traits ; they 're simply thrown away when they break and they definitely ca n't reproduce . the answer lies in something called self assembly . self assembly is a system where unordered parts come together in an organized structure , completely on their own .
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what is self-assembly ?
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without water , a human can only survive for about 100 hours . but there 's a creature so resilient that it can go without it for decades . this one millimeter animal can survive both the hottest and coldest environments on earth , and can even withstand high levels of radiation . this is the tardigrade , and it 's one of the toughest creatures on earth , even if it does look more like a chubby , eight-legged gummy bear . most organisms need water to survive . water allows metabolism to occur , which is the process that drives all the biochemical reactions that take place in cells . but creatures like the tardigrade , also known as the water bear , get around this restriction with a process called anhydrobiosis , from the greek meaning life without water . and however extraordinary , tardigrades are n't alone . bacteria , single-celled organisms called archaea , plants , and even other animals can all survive drying up . for many tardigrades , this requires that they go through something called a tun state . they curl up into a ball , pulling their head and eight legs inside their body and wait until water returns . it 's thought that as water becomes scarce and tardigrades enter their tun state , they start synthesize special molecules , which fill the tardigrade 's cells to replace lost water by forming a matrix . components of the cells that are sensitive to dryness , like dna , proteins , and membranes , get trapped in this matrix . it 's thought that this keeps these molecules locked in position to stop them from unfolding , breaking apart , or fusing together . once the organism is rehydrated , the matrix dissolves , leaving behind undamaged , functional cells . beyond dryness , tardigrades can also tolerate other extreme stresses : being frozen , heated up past the boiling point of water , high levels of radiation , and even the vacuum of outer space . this has led to some erroneous speculation that tardigrades are extraterrestrial beings . while that 's fun to think about , scientific evidence places their origin firmly on earth where they 've evolved over time . in fact , this earthly evolution has given rise to over 1100 known species of tardigrades and there are probably many others yet to be discovered . and because tardigrades are so hardy , they exist just about everywhere . they live on every continent , including antarctica . and they 're in diverse biomes including deserts , ice sheets , the sea , fresh water , rainforests , and the highest mountain peaks . but you can find tardigrades in the most ordinary places , too , like moss or lichen found in yards , parks , and forests . all you need to find them is a little patience and a microscope . scientists are now to trying to find out whether tardigrades use the tun state , their anti-drying technique , to survive other stresses . if we can understand how they , and other creatures , stabilize their sensitive biological molecules , perhaps we could apply this knowledge to help us stabilize vaccines , or to develop stress-tolerant crops that can cope with earth 's changing climate . and by studying how tardigrades survive prolonged exposure to the vacuum of outer space , scientists can generate clues about the environmental limits of life and how to safeguard astronauts . in the process , tardigrades could even help us answer a critical question : could life survive on planets much less hospitable than our own ?
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and they 're in diverse biomes including deserts , ice sheets , the sea , fresh water , rainforests , and the highest mountain peaks . but you can find tardigrades in the most ordinary places , too , like moss or lichen found in yards , parks , and forests . all you need to find them is a little patience and a microscope .
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where are tardigrades normally found ?
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spray-painted subway cars , tagged bridges , mural-covered walls . graffiti pops up boldly throughout our cities . it can make statements about identity , art , empowerment , and politics , while simultaneously being associated with destruction . and , it turns out , it 's nothing new . graffiti , or the act of writing or scribbling on public property , has been around for thousands of years . and across that span of time , it 's raised the same questions we debate now : is it art ? is it vandalism ? in the 1st century bce , romans regularly inscribed messages on public walls , while oceans away , mayans were prolifically scratching drawings onto their surfaces . and it was n't always a subversive act . in pompeii , ordinary citizens regularly marked public walls with magic spells , prose about unrequited love , political campaign slogans , and even messages to champion their favorite gladiators . some , including the greek philosopher plutarch , pushed back , deeming graffiti ridiculous and pointless . but it was n't until the 5th century that the roots of the modern concept of vandalism were planted . at that time , a barbaric tribe known as the vandals swept through rome , pillaging and destroying the city . but it was n't until centuries later that the term vandalism was actually coined in an outcry against the defacing of art during the french revolution . and as graffiti became increasingly associated with deliberate rebellion and provocativeness , it took on its vandalist label . that 's part of the reason why , today , many graffiti artists stay underground . some assume alternate identities to avoid retribution , while others do so to establish comradery and make claim to territory . beginning with the tags of the 1960s , a novel overlap of celebrity and anonymity hit the streets of new york city and philadelphia . taggers used coded labels to trace their movements around cities while often alluding to their origins . and the very illegality of graffiti-making that forced it into the shadows also added to its intrigue and growing base of followers . the question of space and ownership is central to graffiti 's history . its contemporary evolution has gone hand in hand with counterculture scenes . while these movements raised their anti-establishment voices , graffiti artists likewise challenged established boundaries of public property . they reclaimed subway cars , billboards , and even once went so far as to paint an elephant in the city zoo . political movements , too , have used wall writing to visually spread their messages . during world war ii , both the nazi party and resistance groups covered walls with propaganda . and the berlin wall 's one-sided graffiti can be seen as a striking symbol of repression versus relatively unrestricted public access . as the counterculture movements associated with graffiti become mainstream , does graffiti , too , become accepted ? since the creation of so-called graffiti unions in the 1970s and the admission of select graffiti artists into art galleries a decade later , graffiti has straddled the line between being outside and inside the mainstream . and the appropriation of graffiti styles by marketers and typographers has made this definition even more unclear . the once unlikely partnerships of graffiti artists with traditional museums and brands , have brought these artists out of the underground and into the spotlight . although graffiti is linked to destruction , it 's also a medium of unrestricted artistic expression . today , the debate about the boundary between defacing and beautifying continues . meanwhile , graffiti artists challenge common consensus about the value of art and the degree to which any space can be owned . whether spraying , scrawling , or scratching , graffiti brings these questions of ownership , art , and acceptability to the surface .
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and the berlin wall 's one-sided graffiti can be seen as a striking symbol of repression versus relatively unrestricted public access . as the counterculture movements associated with graffiti become mainstream , does graffiti , too , become accepted ? since the creation of so-called graffiti unions in the 1970s and the admission of select graffiti artists into art galleries a decade later , graffiti has straddled the line between being outside and inside the mainstream .
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graffiti :
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♪ a treasure trove of planets found astronomers are celebrating a new discovery . sean carey , manager , spitzer science center , caltech ipac the big news is that around a very nearby cold , small star we found seven rocky , earth-sized planets , all of which could potentially have liquid water . three of them orbit in the habitable zone around the star . and liquid water could exist on any of the seven planets given the right conditions . nikole lewis , james webb telescope project scientist , space telescope science institute for me it 's mind-blowing . the first time i saw what the system had in it , i was just like , `` you got to be kidding me ! '' then i looked at the data myself . i 'm like , `` yup , there they all are . '' it 's just , i would have never predicted this . it 's beyond , you know , anything i could 've ever dreamt of . the planetary system is called trappist-1 after the belgian-operated telescope in chile . trappist found two planets in 2016 . nasa 's spitzer space telescope , with the help of ground-based telescopes , discovered five more . michael gillon , principal investigator , trappist , university of liege , belgium i felt super-excited . amazed by the very existence of this system ... was kind of ... of yeah ... of shock . the trappist-1 planets are extremely close to one another . from a planet 's surface you could easily see other trappist-1 planets in the sky . if you were standing on one of these planets you 'd actually see a lot of them sort of in the sky whipping by on these very short orbital periods . nasa 's james webb telescope , launching in 2018 , could teach us even more about the trappist-1 system . it will be able to detect the chemical fingerprints of water , methane and oxygen of potential atmospheres , key ingredients in assessing habitability . it is an excellent , fantastic discovery . all images of planets are artist 's conceptions . jet propulsion laboratory california institute of technology
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it 's beyond , you know , anything i could 've ever dreamt of . the planetary system is called trappist-1 after the belgian-operated telescope in chile . trappist found two planets in 2016 .
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what is the name of the planetary system ?
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good afternoon , ladies and gentlemen . let us welcome you to the final day of dramatic battle between great tragedians . it is a spring day here in ancient greece . nearly 17,000 patrons are filing into the theatre of dionysus to watch top playwrights , including favorites aeschylus and sophocles duke it out to see whose hero may be deemed most tragic , whose story most awful . well seacrestopolis , in last week 's battle of the choruses , all 50 members of each playwright 's chorus traveled back and forth across the stage , singing the strophe and antistrophe , telling misbegotten tales of woe . today 's first chorus is entering through the parados , taking their positions in the orchestra at the bottom of the stage . mario lopedokia , this is nothing we have n't seen before . all 50 members speaking from the depths of their souls . wait , what is this ? i 've not seen this before , seacrestopolis . there is one actor stepping out of choral formation , assuming an independent role in this play . can you make out who it is ? that looks like thespis . it seems he 's changing his mask , and taking on the role of another character . incredible . surely , thespis will go down in history as the very first actor . he has changed the face of theater forever . and that was just the warm-up act . on to the main attraction . aeschylus will have the stage first . let 's see what he does . we expect great things . last competition , sophocles beat him by a smidge , but aeschylus is still considered the father of tragedy . now , aeschylus frequently competes at this festival , the city dionysia . though his plays are violent , the bloodshed is never seen by the audience , which allows the dramatic tension to take center stage . let 's see what he does today to try to win his title back . here comes aeschylus 's chorus , but they seem to be missing quite a few people . what is going on here ? not only are they down a few people . there are two actors taking center stage . this is absolutely unheard of . he has build on thespis 's idea and added a second actor to the mix . aeschylus is relying on the two individuals to tell the story . the dialogue possible in tragedy now has taken precedence over the chorus . no wonder he drastically shrunk its size . this applause is well deserved . the crowd has hushed . sophocles 's actors and chorus are taking the stage for the play , `` oedipus rex . '' as usual , the chorus is set up in the orchestra . and what 's this ? sophocles has added a third actor . will this one-upmanship never end ? three actors , and they are changing their masks to take on several different roles as they weave the tale of oedipus , a nice fellow who kills his father and marries his mother . kills his father and marries his mother . that sounds pretty tragic to me . it is most tragic , mario lopedokia . call me crazy , but i 'm willing to bet that future generations will hold this play up as the perfect example of tragedy . excuse me , seacrestopolis . oedipus has left the stage after realizing jocasta was his wife and also his mother . where has he gone ? i ca n't even imagine . wait . the messenger has stepped on stage and is telling us of the great king 's actions . he says that oedipus , upon finding his mother , wife , whatever , jocasta , dead of her own hand in their incestuous bedroom , took the broaches from her dress and stabbed his eyes repeatedly . you ca n't blame the guy , can you ? bedded his mother , killed his father , is father and brother to his children . i might do the same . my friend , i do believe we 've seen it all . indeed , we have . there is nothing more tragic than oedipus . and sure enough , the judges who have been chosen by lot from all over greece are ready to announce the winner . oh , folks ! this is one for the history books . dark horse playwright , philocles , has taken first prize . what an upset . what a tragedy . what a night , folks . we have witnessed the laying of the foundation of modern theater and some great innovations : the shrinking of the chorus , the addition of three actors , and such catharsis . does n't a great tragedy just make you feel renewed and cleansed ? it sure does , but now we are out of time . i 'm seacrestopolis , and i 'm mario lopedokia . peace , love and catharsis .
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surely , thespis will go down in history as the very first actor . he has changed the face of theater forever . and that was just the warm-up act .
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all of the following are aspects of ancient greek theater except :
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translator : tom carter reviewer : bedirhan cinar in society , we have to follow laws that maintain order . did you know all chemical matter follows certain laws as well ? in fact , we can describe those laws by looking at relationships . some easy laws to begin with are the ones that govern the gases . back in 1662 , robert boyle realized that gases had an interesting response when he put them into containers and changed their volume . take an empty bottle and put the cap on it , closing that container . now squeeze your bottle , and what happens ? the pressure inside the bottle increases when the size of the container decreases . you can only crush that container so much until the gases inside push back on your hand . this is called an inverse proportion , and it changes at the same rate for every gas . boyle 's law allows chemists to predict the volume of any gas at any given pressure because the relationship is always the same . in 1780 , jacques charles noticed a different relationship between gases and their temperature . if you 've ever seen a hot-air balloon , you 've seen this law in action . when the ballons are laid out , they 're totally flat . instead of blowing the balloon up like a party balloon , they use a giant flame to heat the air inside that envelope . as the air is heated up , the balloon begins to inflate as the gas volume increases . the hotter the gas becomes , the larger the volume , and that 's charles ' law . notice this law is different from boyle 's . charles ' law is a direct relationship . as the temperature increases , the volume increases as well . the third law is also easily demonstrated . when you 're blowing up party balloons , the volume increases . as you are blowing , you 're forcing more and more gas particles into the balloon from your lungs . this causes the balloon volume to increase . this is avogadro 's law in action . as the number of particles of gas added to a container are increased , the volume will increase as well . if you add too many particles , well , you know what happens next . laws are everywhere , even in the tiniest particles of gas . if you squeeze them , the pressure will increase as the particles are pushed together . low volume means a high pressure because those particles push back . as the temperature increases , gases move away from one another , and the volume increases as well . finally , if you add gas to a closed container , that container 's volume will expand . but be careful not to add too much , because otherwise you could end up with a burst balloon .
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as the temperature increases , gases move away from one another , and the volume increases as well . finally , if you add gas to a closed container , that container 's volume will expand . but be careful not to add too much , because otherwise you could end up with a burst balloon .
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how does the pressure of a container change as the volume is changed ?
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we 've all seen movies about terrible insects from outer space or stories of abduction by little green men , but the study of life in the universe , including the possibility of extraterrestrial life , is also a serious , scientific pursuit . astrobiology draws on diverse fields , such as physics , biology , astronomy , and geology , to study how life was formed on earth , how it could form elsewhere , and how we might detect it . many ancient religions described other worlds inhabited by known human beings , but these are more like mythical realms or parallel universes than other planets existing in the same physical world . it is only within the last century that scientists have been able to seriously undertake the search for extraterrestrial life . we know that at the most basic level organisms on earth need three things : liquid water , a source of energy , and organic , carbon-based material . we also know that the earth is just the right distance from the sun , so as not to be either frozen or molten . so , planets within such a habitable range from their own stars may be able to support life . but while we used to think that life could only exist in such earth-like environments , one of the most amazing discoveries of astrobiology has been just how versatile life is . we now know that life can thrive in some of the most extreme environments that 'd be fatal for most known organisms . life is found everywhere , from black smoke of hydrothermal vents in the dark depths of earth 's oceans , to bubbling , hot , acidic springs on the flanks of volcanoes , to high up in the atmosphere . organisms that live in these challenging environments are called extremophiles , and they can survive at extremes of temperature , pressure , and radiation , as well as salinity , acidity , and limited availability of sunlight , water , or oxygen . what is most remarkable about these extremophiles is that they are found thriving in environments that mimic those on alien worlds . one of the most important of these worlds is our red and dusty neighbor , mars . today , astrobiologists are exploring places where life might once have existed on mars using nasa 's curiosity rover . one of these is gale crater , an impact crater created when a meteor hit the surface of mars nearly 3.8 billions years ago . evidence from orbit suggest past traces of water , which means the crater might once have supported life . planets are not the only places astrobiologists are looking at . for example , europa , one of the moons of jupiter , and enceladus and titan , two of saturn 's moons , are all exciting possibilities . although these moons are extremely cold and two are covered in thick ice , there is evidence of liquid oceans beneath the shell . could life be floating around in these oceans , or could it be living around black smoker vents at the bottom ? titan is particularly promising as it has an atmosphere and earth-like lakes , seas , and rivers flowing across the surface . it is very cold , however , too cold for liquid water , so these rivers may instead be flowing with liquid hydrocarbons such as methane and ethane . these are composed of hydrogen , and , more importantly , carbon , which is the basic building block of all life as we know it . so , could life be found in these lakes ? although instruments are being designed to study these distant worlds , it takes many years to build them and even longer to get them where they need to be . in the meantime , astrobiologists work in our own natural laboratory , the earth , to learn about all the weird and wonderful forms of life that can exist and to help us one day answer one of humanity 's oldest questions : are we alone ?
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we also know that the earth is just the right distance from the sun , so as not to be either frozen or molten . so , planets within such a habitable range from their own stars may be able to support life . but while we used to think that life could only exist in such earth-like environments , one of the most amazing discoveries of astrobiology has been just how versatile life is . we now know that life can thrive in some of the most extreme environments that 'd be fatal for most known organisms .
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which of these things is not always needed for life on earth ?
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our story is about a girl named iris . iris is very sensitive . ( bird cawing ) so much that she is always in tears . she cries when she 's sad , when she 's happy , ( godzilla roars ) and even tears up when things just get to her . she has special lacrimal glands to make new tears and special tubes , called lacrimal puncta , to drain old ones away . and she cries so much that she goes through ten ounces of tears per day , thirty gallons a year ! in fact , if you look closely , you 'll see that she 's crying a little bit all the time . the basal tears that iris constantly produces form a thin coating of three layers that cover her and keep dirt and debris away . right next to iris is the mucus layer , which keeps the whole thing fastened to her . on top of it is the aqueous layer , which keeps iris hydrated , repels invasive bacteria , and protects her skin , or cornea , from damage . and , finally , there is the lipid layer , an oily outer film that keeps the surface smooth for iris to see through , and prevents the other layers from evaporating . normally , iris goes about her day without really noticing the basal tears doing their thing . that 's kind of their whole point . but one day , she meets a girl named onion . iris is immediately smitten . onion looks gorgeous in her bright purple jacket , and she smells terrific . so , iris invites onion to her house for dinner . but when she comes in and takes off her jacket , something terrible happens . you see , when onion 's jacket is removed , a chemical reaction happens , converting the sulfoxides that make her smell so great into sulfenic acid , which then becomes a nasty substance with a long name : syn-propanethial s-oxide . the gas stings iris , and suddenly , she ca n't help it , she starts weeping uncontrollably . these reflex tears are different from the basal tears that iris is used to . because they 're designed to wash away harmful substances , or particles , they 're released in much larger amounts , and their aqueous layer contains more antibodies to stop any microorganisms that may be trying to get in , as well . both iris and onion are devastated . they know they ca n't continue their relationship if iris is going to hurt and cry every time onion takes off her jacket . so , they decide to break up . as onion walks out the door , iris stops crying . and immediately starts again . only now , she 's not crying reflex tears but emotional tears . when someone is either too sad or too happy , it feels like a loss of control , which can be dangerous . so , emotional tears are sent in to stabilize the mood as quickly as possible , along with other physical reactions , such as an increased heart rate and slower breathing . but scientists still are n't sure exactly how or why the tears themselves are helpful . they may be a social mechanism to elicit sympathy or show submission . but some studies have also found that emotional tears contain higher levels of stress hormones , such as acth and enkephalin , an endorphin and natural pain killer . in this case , emotional tears are also directly calming iris down , as well as signaling her emotional state to others . sorry things did n't work out with onion , iris , but do n't worry . as long as you have all three kinds of tears working to keep you balanced and healthy , it will get better . you 'll see .
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she cries when she 's sad , when she 's happy , ( godzilla roars ) and even tears up when things just get to her . she has special lacrimal glands to make new tears and special tubes , called lacrimal puncta , to drain old ones away . and she cries so much that she goes through ten ounces of tears per day , thirty gallons a year !
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what are the special glands called that make new tears ?
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translator : andrea mcdonough reviewer : jessica ruby hello , humans . my name is matt and for the next several moments , you are going to listen to me . mwah , ha , ha , ha , ha . sorry . i 'm just joking . this is my normal voice . have you ever taken direction from a mysterious voice on the computer before ? no ? perfect ! i want to try an experiment with you , but i ca n't tell you what that experiment entails because if i do , it wo n't work . you 'll just have to trust me . this will all make sense soon , hopefully . if you 're sitting down , stand up from your chair and take a step back . in a moment , i 'm going to have you twirl around , so give yourself a bit of space . need to move some furniture around ? take your time . i 'll wait . on the count of three , you 're going to start hopping on one foot . are you ready ? one , two , three ! hop , hop , hop , hop , hop . nice work ! ok , while you 're still hopping , i now want you to begin barking like a dog . ruff , ruff ; ruff , ruff ; ruff , ruff . wow , that 's quite a bark ! and a few more . ruff , ruff , ruff . and three , two , one , stop ! feel free to relax and sit back down . now , i want you think about how much time passed between the moment i said , `` go ! '' and you began hopping on one foot to the moment i said , `` stop ! '' take a guess . i 'm looking for an exact number of seconds or minutes . now , with a pen and paper , write that number down . all done ? the exact time was actually 26 seconds . did you overestimate ? chances are that you did . so , what was the culprit ? the culprit was time perception . although we can make shockingly precise time estimates , when we experience something new , unusual , or dynamic , like hopping on one foot while taking instructions from a voice on the computer , or , say , jumping out of an airplane , we often miscalculate how much time has passed . meaning , if you bungee jump for the first time , your fall to the bottom may seem like it lasted for 10 seconds while the recorded time may actually show that the jump only lasted for 5 . the reason for this difference is unlike your body 's physical drop to the bottom , your brain 's perception of time does not follow a straight line between two points . some scientists even believe your brain follows more of a curved path that is dependent on the amount of information you take in as you fall downwards . for example , david eagleman , a neuroscientist at baylor college of medicine , believes time perception is heavily influenced by the number of memories and data you record onto your brain . when you have a new experience , like jumping off a high dive for the first time , your senses are heightened . you 're taking in more details about sights , sounds , and smells than you normally would . and you store more data onto your brain in the form of memories . so , the more data you store in your brain , like the smell of chlorine as you leapt from the high dive or the color of the water , the longer your perception of that experience . meaning , the number of memories and data you record on your brain has a direct impact on how long you believe that experience to have lasted . have you ever heard a person recount what it 's like to be in a car accident ? although automotive accidents typically last seconds , those involved often say they felt the accident lasted far longer . time perception can also account for why your childhood may have seem to have lasted forever . by adulthood , a year can slip by in a heartbeat , but children record more data onto their brains . this occurs because many of the experiences we have as children are new and unfamiliar to us . the stack of encoded memories on your brain is so dense that reading them back makes you believe your experiences must have taken forever . additionally , when you 're 5 years old , one year is 1/5 of your life . but , when you 're 25 , one year makes up 1/25 , further altering your perception of time . and , if you 're an adult , think about a trip that you may have taken to a far-away land for the first time . did n't those two weeks you spent exploring your surroundings seem to have lasted far longer than 14 days ? though time perception is rooted in both hard science and theory , it provides a great lesson for us on how to live our lives . i 'm sure you have all heard that a person should n't sit on a couch and let life pass them by . well , time perception tells us why that is . if you get up and engage with the world and have new experiences , and maybe even hop around on one foot and bark like a dog , you will literally perceive your own life to have lasted for a longer period of time .
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so , what was the culprit ? the culprit was time perception . although we can make shockingly precise time estimates , when we experience something new , unusual , or dynamic , like hopping on one foot while taking instructions from a voice on the computer , or , say , jumping out of an airplane , we often miscalculate how much time has passed .
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some scientists believe time perception accounts for the difference between the time you believe has elapsed and ____________ .
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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 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 ?
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what is the english translation for the sanskrit word 'eka ' ?
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translator : andrea mcdonough reviewer : bedirhan cinar what does `` going viral '' on the internet really mean , and why does it happen so quickly ? why is a financial institution too big to fail ? how does a virus in africa end up in the united states in a matter of hours ? why are facebook and google such powerful companies at creating global connections ? well , in a word : networks . but what are networks ? everyone knows about their social network , but there are all different kinds of networks you probably have n't thought about . networks are collections of links which combine by specific rules and behaviors if they are alive . we say that networks are alive because they are in constant change . over time , the connections within a network migrate and concentrate in new places , forming evolving structures . how the evolution and concentration of constantly changing connections occurs is the subject of a whole discipline called network theory . we can think of networks as neighborhoods . neighborhoods are defined by maps . a google map demonstrates the relationship between locations in exactly the same fashion a network connects hubs and nodes , using streets as links to connect neighborhoods . the reason a network can expand and evolve so quickly is based upon a mathematical concept called power functions . a power function is a mathematical amplification mechanism , which over specific and very small ranges , accelerates changes logarithmically . that is , a very small change in one parameter produces a huge change in another over a very specific range of values . an example of how network structure emerges is the algorithm used by google . as the number of links around a search term , say `` friends '' , increases , connections begin to form among millions of different searches using the term `` friend '' . what google has cleverly accomplished is a real-time mathematical model for how to predict the emergence of growing connections among billions of search terms . the algorithm google derived collects the number of references to any search object . as references to a search object increase , the number of links also increases , creating a node . as the node increases in size , it eventually becomes a hub , which links to many nodes . networks will continue to emerge as new ways of connecting and creating neighborhoods are defined . perhaps you can begin to see why networks are so powerful . as google continues to collect the billions of daily searches , new clusters of links will rapidly emerge , forming additional and growing networks . despite the logarithmic expansion of your network , the laws of six degrees of separation still apply . therefore , if you explore a close friend or acquaintances in you facebook network , everyone on average will be separated by six individuals or less and a map of your social network will create neighborhoods linked by common connections among friends .
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why are facebook and google such powerful companies at creating global connections ? well , in a word : networks . but what are networks ? everyone knows about their social network , but there are all different kinds of networks you probably have n't thought about .
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how involved are you in social networks ? other than ones you find online , what networks are you involved in ?
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are you sleeping restlessly , feeling irritable or moody , forgetting little things , and feeling overwhelmed and isolated ? do n't worry . we 've all been there . you 're probably just stressed out . stress is n't always a bad thing . it can be handy for a burst of extra energy and focus , like when you 're playing a competitive sport , or have to speak in public . but when its continuous , the kind most of us face day in and day out , it actually begins to change your brain . chronic stress , like being overworked or having arguments at home , can affect brain size , its structure , and how it functions , right down to the level of your genes . stress begins with something called the hypothalamus pituitary adrenal axis , a series of interactions between endocrine glands in the brain and on the kidney , which controls your body 's reaction to stress . when your brain detects a stressful situation , your hpa axis is instantly activated and releases a hormone called cortisol , which primes your body for instant action . but high levels of cortisol over long periods of time wreak havoc on your brain . for example , chronic stress increases the activity level and number of neural connections in the amygdala , your brain 's fear center . and as levels of cortisol rise , electric signals in your hippocampus , the part of the brain associated with learning , memories , and stress control , deteriorate . the hippocampus also inhibits the activity of the hpa axis , so when it weakens , so does your ability to control your stress . that 's not all , though . cortisol can literally cause your brain to shrink in size . too much of it results in the loss of synaptic connections between neurons and the shrinking of your prefrontal cortex , the part of your brain the regulates behaviors like concentration , decision-making , judgement , and social interaction . it also leads to fewer new brain cells being made in the hippocampus . this means chronic stress might make it harder for you to learn and remember things , and also set the stage for more serious mental problems , like depression and eventually alzheimer 's disease . the effects of stress may filter right down to your brain 's dna . an experiment showed that the amount of nurturing a mother rat provides its newborn baby plays a part in determining how that baby responds to stress later in life . the pups of nurturing moms turned out less sensitive to stress because their brains developed more cortisol receptors , which stick to cortisol and dampen the stress response . the pups of negligent moms had the opposite outcome , and so became more sensitive to stress throughout life . these are considered epigenetic changes , meaning that they effect which genes are expressed without directly changing the genetic code . and these changes can be reversed if the moms are swapped . but there 's a surprising result . the epigenetic changes caused by one single mother rat were passed down to many generations of rats after her . in other words , the results of these actions were inheritable . it 's not all bad news , though . there are many ways to reverse what cortisol does to your stressed brain . the most powerful weapons are exercise and meditation , which involves breathing deeply and being aware and focused on your surroundings . both of these activities decrease your stress and increase the size of the hippocampus , thereby improving your memory . so do n't feel defeated by the pressures of daily life . get in control of your stress before it takes control of you .
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and as levels of cortisol rise , electric signals in your hippocampus , the part of the brain associated with learning , memories , and stress control , deteriorate . the hippocampus also inhibits the activity of the hpa axis , so when it weakens , so does your ability to control your stress . that 's not all , though .
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where are the endocrine glands that control the hpa axis ?
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how do you get what you want using just your words ? aristotle set out to answer exactly that question over 2,000 years ago with the treatise on rhetoric . rhetoric , according to aristotle , is the art of seeing the available means of persuasion . and today we apply it to any form of communication . aristotle focused on oration , though , and he described three types of persuasive speech . forensic , or judicial , rhetoric establishes facts and judgements about the past , similar to detectives at a crime scene . epideictic , or demonstrative , rhetoric makes a proclamation about the present situation , as in wedding speeches . but the way to accomplish change is through deliberative rhetoric , or symbouleutikon . rather than the past or the present , deliberative rhetoric focuses on the future . it 's the rhetoric of politicians debating a new law by imagining what effect it might have , like when ronald regan warned that the introduction of medicare would lead to a socialist future spent telling our children and our children 's children what it once was like in america when men were free . but it 's also the rhetoric of activists urging change , such as martin luther king jr 's dream that his children will one day live in a nation where they will not be judged by the color of their skin , but by the content of their character . in both cases , the speaker 's present their audience with a possible future and try to enlist their help in avoiding or achieving it . but what makes for good deliberative rhetoric , besides the future tense ? according to aristotle , there are three persuasive appeals : ethos , logos , and pathos . ethos is how you convince an audience of your credibility . winston churchill began his 1941 address to the u.s. congress by declaring , `` i have been in full harmony all my life with the tides which have flowed on both sides of the atlantic against privilege and monopoly , '' thus highlighting his virtue as someone committed to democracy . much earlier , in his defense of the poet archias , roman consul cicero appealed to his own practical wisdom and expertise as a politician : `` drawn from my study of the liberal sciences and from that careful training to which i admit that at no part of my life i have ever been disinclined . '' and finally , you can demonstrate disinterest , or that you 're not motivated by personal gain . logos is the use of logic and reason . this method can employ rhetorical devices such as analogies , examples , and citations of research or statistics . but it 's not just facts and figures . it 's also the structure and content of the speech itself . the point is to use factual knowledge to convince the audience , as in sojourner truth 's argument for women 's rights : `` i have as much muscle as any man and can do as much work as any man . i have plowed and reaped and husked and chopped and mowed and can any man do more than that ? '' unfortunately , speakers can also manipulate people with false information that the audience thinks is true , such as the debunked but still widely believed claim that vaccines cause autism . and finally , pathos appeals to emotion , and in our age of mass media , it 's often the most effective mode . pathos is neither inherently good nor bad , but it may be irrational and unpredictable . it can just as easily rally people for peace as incite them to war . most advertising , from beauty products that promise to relieve our physical insecurities to cars that make us feel powerful , relies on pathos . aristotle 's rhetorical appeals still remain powerful tools today , but deciding which of them to use is a matter of knowing your audience and purpose , as well as the right place and time . and perhaps just as important is being able to notice when these same methods of persuasion are being used on you .
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but what makes for good deliberative rhetoric , besides the future tense ? according to aristotle , there are three persuasive appeals : ethos , logos , and pathos . ethos is how you convince an audience of your credibility .
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the most persuasive , but often least ethical , rhetorical appeal is :
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if you ca n't imagine life without chocolate , you 're lucky you were n't born before the 16th century . until then , chocolate only existed in mesoamerica in a form quite different from what we know . as far back as 1900 bce , the people of that region had learned to prepare the beans of the native cacao tree . the earliest records tell us the beans were ground and mixed with cornmeal and chili peppers to create a drink - not a relaxing cup of hot cocoa , but a bitter , invigorating concoction frothing with foam . and if you thought we make a big deal about chocolate today , the mesoamericans had us beat . they believed that cacao was a heavenly food gifted to humans by a feathered serpent god , known to the maya as kukulkan and to the aztecs as quetzalcoatl . aztecs used cacao beans as currency and drank chocolate at royal feasts , gave it to soldiers as a reward for success in battle , and used it in rituals . the first transatlantic chocolate encounter occurred in 1519 when hernán cortés visited the court of moctezuma at tenochtitlan . as recorded by cortés 's lieutenant , the king had 50 jugs of the drink brought out and poured into golden cups . when the colonists returned with shipments of the strange new bean , missionaries ' salacious accounts of native customs gave it a reputation as an aphrodisiac . at first , its bitter taste made it suitable as a medicine for ailments , like upset stomachs , but sweetening it with honey , sugar , or vanilla quickly made chocolate a popular delicacy in the spanish court . and soon , no aristocratic home was complete without dedicated chocolate ware . the fashionable drink was difficult and time consuming to produce on a large scale . that involved using plantations and imported slave labor in the caribbean and on islands off the coast of africa . the world of chocolate would change forever in 1828 with the introduction of the cocoa press by coenraad van houten of amsterdam . van houten 's invention could separate the cocoa 's natural fat , or cocoa butter . this left a powder that could be mixed into a drinkable solution or recombined with the cocoa butter to create the solid chocolate we know today . not long after , a swiss chocolatier named daniel peter added powdered milk to the mix , thus inventing milk chocolate . by the 20th century , chocolate was no longer an elite luxury but had become a treat for the public . meeting the massive demand required more cultivation of cocoa , which can only grow near the equator . now , instead of african slaves being shipped to south american cocoa plantations , cocoa production itself would shift to west africa with cote d'ivoire providing two-fifths of the world 's cocoa as of 2015 . yet along with the growth of the industry , there have been horrific abuses of human rights . many of the plantations throughout west africa , which supply western companies , use slave and child labor , with an estimation of more than 2 million children affected . this is a complex problem that persists despite efforts from major chocolate companies to partner with african nations to reduce child and indentured labor practices . today , chocolate has established itself in the rituals of our modern culture . due to its colonial association with native cultures , combined with the power of advertising , chocolate retains an aura of something sensual , decadent , and forbidden . yet knowing more about its fascinating and often cruel history , as well as its production today , tells us where these associations originate and what they hide . so as you unwrap your next bar of chocolate , take a moment to consider that not everything about chocolate is sweet .
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aztecs used cacao beans as currency and drank chocolate at royal feasts , gave it to soldiers as a reward for success in battle , and used it in rituals . the first transatlantic chocolate encounter occurred in 1519 when hernán cortés visited the court of moctezuma at tenochtitlan . as recorded by cortés 's lieutenant , the king had 50 jugs of the drink brought out and poured into golden cups .
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the first transatlantic chocolate encounter occurred in :
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as an experiment , we gave recordings of the same walt whitman poem to 3 different animators . each interpreted the text with no knowledge of what the others were creating here 's the result . `` a noiseless patient spider '' by walt whitman interpretation # 1 by jeremiah dickey , medium : paint on glass `` a noiseless patient spider , i mark 'd where on a little promontory it stood isolated , mark 'd how to explore the vacant vast surrounding , it launch 'd forth filament , filament , filament , out of itself , ever unreeling them , ever tirelessly speeding them . and you o my soul where you stand , surrounded , detached , in measureless oceans of space , ceaselessly musing , venturing , throwing , seeking the spheres to connect them , till the bridge you will need be form 'd , till the ductile anchor hold , till the gossamer thread you fling catch somewhere , o my soul . '' interpretation # 2 by biljana labovic , medium : video `` a noiseless patient spider , i mark ’ d where on a little promontory it stood isolated , mark ’ d how to explore the vacant vast surrounding , it launch ’ d forth filament , filament , filament , out of itself , ever unreeling them , ever tirelessly speeding them . and you o my soul where you stand , surrounded , detached , in measureless oceans of space , ceaselessly musing , venturing , throwing , seeking the spheres to connect them , till the bridge you will need be form ’ d , till the ductile anchor hold , till the gossamer thread you fling catch somewhere , o my soul . '' interpretation # 3 by lisa labracio , medium : scratchboard `` a noiseless patient spider , i mark ’ d where on a little promontory it stood isolated , mark ’ d how to explore the vacant vast surrounding , it launch ’ d forth filament , filament , filament , out of itself , ever unreeling them , ever tirelessly speeding them . and you o my soul where you stand , surrounded , detached , in measureless oceans of space , ceaselessly musing , venturing , throwing , seeking the spheres to connect them , till the bridge you will need be form ’ d , till the ductile anchor hold , till the gossamer thread you fling catch somewhere , o my soul . ''
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as an experiment , we gave recordings of the same walt whitman poem to 3 different animators . each interpreted the text with no knowledge of what the others were creating here 's the result .
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whitman repeats the phrase “ till the , ” twice at the beginning of each of the last two lines of the poem . why might he have done this ?
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chat with a friend about an established scientific theory and she might reply , `` well , that 's just a theory . '' but a conversation about an established scientific law rarely ends with , `` well , that 's just a law . '' why is that ? what is the difference between a theory and a law , and is one better ? scientific laws and theories have different jobs to do . a scientific law predicts the results of certain initial conditions . it might predict your unborn child 's possible hair colors , or how far a baseball travels when launched at a certain angle . in contrast , a theory tries to provide the most logical explanation about why things happen as they do . a theory might invoke dominant and recessive genes to explain how brown-haired parents ended up with a red-headed child , or use gravity to shed light on the parabolic trajectory of a baseball . in simplest terms , a law predicts what happens while a theory proposes why . a theory will never grow up into a law , though the development of one often triggers progress on the other . in the 17th century , johannes kepler theorized cosmic musical harmonies to explain the nature of planetary orbits . he developed three brilliant laws of planetary motion while he was studying decades of precise astronomical data in an effort to find support for his theory . while his three laws are still in use today , gravity replaced his theory of harmonics to explain the planets ' motions . how did kepler get part of it wrong ? well , we were n't handed a universal instruction manual . instead , we continually propose , challenge , revise , or even replace our scientific ideas as a work in progress . laws usually resist change since they would n't have been adopted if they did n't fit the data , though we occasionally revise laws in the face of new unexpected information . a theory 's acceptance , however , is often gladiatorial . multiple theories may compete to supply the best explanation of a new scientific discovery . upon further research , scientists tend to favor the theory that can explain most of the data , though there may still be gaps in our understanding . scientists also like when a new theory successfully predicts previously unobserved phenomena , like when dmitri mendeleev 's theory about the periodic table predicted several undiscovered elements . the term scientific theory covers a broad swath . some theories are new ideas with little experimental evidence that scientists eye with suspicion , or even ridicule . other theories , like those involving the big bang , evolution , and climate change , have endured years of experimental confirmation before earning acceptance by the majority of the scientific community . you would need to learn more about a specific explanation before you 'd know how well scientists perceive it . the word theory alone does n't tell you . in full disclosure , the scientific community has bet on the wrong horse before : alchemy , the geocentric model , spontaneous generation , and the interstellar aether are just a few of many theories discarded in favor of better ones . but even incorrect theories have their value . discredited alchemy was the birthplace of modern chemistry , and medicine made great strides long before we understood the roles of bacteria and viruses . that said , better theories often lead to exciting new discoveries that were unimaginable under the old way of thinking . nor should we assume all of our current scientific theories will stand the test of time . a single unexpected result is enough to challenge the status quo . however , vulnerability to some potentially better explanation does n't weaken a current scientific theory . instead , it shields science from becoming unchallenged dogma . a good scientific law is a finely-tuned machine , accomplishing its task brilliantly but ignorant of why it works as well as it does . a good scientific theory is a bruised , but unbowed , fighter who risks defeat if unable to overpower or adapt to the next challenger . though different , science needs both laws and theories to understand the whole picture . so next time someone comments that it 's just a theory , challenge them to go nine rounds with the champ and see if they can do any better .
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a theory 's acceptance , however , is often gladiatorial . multiple theories may compete to supply the best explanation of a new scientific discovery . upon further research , scientists tend to favor the theory that can explain most of the data , though there may still be gaps in our understanding . scientists also like when a new theory successfully predicts previously unobserved phenomena , like when dmitri mendeleev 's theory about the periodic table predicted several undiscovered elements . the term scientific theory covers a broad swath .
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new data is found which goes against what scientists predicted should happen . which of the following is not a potential result of the new research ?
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what makes a book a book ? is it just anything that stores and communicates information ? or does it have to do with paper , binding , font , ink , its weight in your hands , the smell of the pages ? is this a book ? probably not . but is this ? to answer these questions , we need to go back to the start of the book as we know it and understand how these elements came together to make something more than the sum of their parts . the earliest object that we think of as a book is the codex , a stack of pages bound along one edge . but the real turning point in book history was johannes gutenberg 's printing press in the mid-15th century . the concept of moveable type had been invented much earlier in eastern culture , but the introduction of gutenberg 's press had a profound effect . suddenly , an elite class of monks and the ruling class no longer controlled the production of texts . messages could spread more easily , and copies could constantly be produced , so printing houses popped up all over europe . the product of this bibliographic boom is familiar to us in some respects , but markedly different in others . the skeleton of the book is paper , type , and cover . more than 2000 years ago , china invented paper as a writing surface , which was itself predated by egyptian papyrus . however , until the 16th century , europeans mainly wrote on thin sheets of wood and durable parchment made of stretched animal skins . eventually , the popularity of paper spread throughout europe , replacing parchment for most printings because it was less expensive in bulk . inks had been made by combining organic plant and animal dyes with water or wine , but since water does n't stick to metal type , use of the printing press required a change to oil-based ink . printers used black ink made of a mixture of lamp soot , turpentine , and walnut oil . and what about font size and type ? the earliest movable type pieces consisted of reversed letters cast in relief on the ends of lead alloy stocks . they were handmade and expensive , and the designs were as different as the people who carved their molds . standardization was not really possible until mass manufacturing and the creation of an accessible word processing system . as for style , we can thank nicolas jenson for developing two types of roman font that led to thousands of others , including the familiar times roman . something had to hold all this together , and until the late 15th century , covers consisted of either wood , or sheets of paper pasted together . these would eventually be replaced by rope fiber millboard , originally intended for high quality bindings in the late 17th century , but later as a less expensive option . and while today 's mass produced cover illustrations are marketing tools , the cover designs of early books were made to order . even spines have a history . initially , they were not considered aesthetically important , and the earliest ones were flat , rather than rounded . the flat form made the books easier to read by allowing the book to rest easily on a table . but those spines were damaged easily from the stresses of normal use . a rounded form solved that issue , although new problems arose , like having the book close in on itself . but flexibility was more important , especially for the on-the-go reader . as the book evolves and we replace bound texts with flat screens and electronic ink , are these objects and files really books ? does the feel of the cover or the smell of the paper add something crucial to the experience ? or does the magic live only within the words , no matter what their presentation ?
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messages could spread more easily , and copies could constantly be produced , so printing houses popped up all over europe . the product of this bibliographic boom is familiar to us in some respects , but markedly different in others . the skeleton of the book is paper , type , and cover .
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what are the benefits of digital texts ? does a digital text offer a different or similar reading experience ?
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the universe is bustling with matter and energy . even in the vast apparent emptiness of intergalactic space , there 's one hydrogen atom per cubic meter . that 's not the mention a barrage of particles and electromagnetic radiation passing every which way from stars , galaxies , and into black holes . there 's even radiation left over from the big bang . so is there such thing as a total absence of everything ? this is n't just a thought experiment . empty spaces , or vacuums , are incredibly useful . inside our homes , most vacuum cleaners work by using a fan to create a low-pressure relatively empty area that sucks matter in to fill the void . but that 's far from empty . there 's still plenty of matter bouncing around . manufacturers rely on more thorough , sealed vacuums for all sorts of purposes . that includes vacuum-packed food that stays fresh longer , and the vacuums inside early light bulbs that protected filaments from degrading . these vacuums are generally created with some version of what a vacuum cleaner does using high-powered pumps that create enough suction to remove as many stray atoms as possible . but the best of these industrial processes tends to leave hundreds of millions of atoms per cubic centimeter of space . that is n't empty enough for scientists who work on experiments , like the large hadron collider , where particle beams need to circulate at close to the speed of light for up to ten hours without hitting any stray atoms . so how do they create a vacuum ? the lhc 's pipes are made of materials , like stainless steel , that do n't release any of their own molecules and are lined with a special coating to absorb stray gases . raising the temperature to 200 degrees celsius burns off any moisture , and hundreds of vacuum pumps take two weeks to trap enough gas and debris out of the pipes for the collider 's incredibly sensitive experiments . even with all this , the large hadron collider is n't a perfect vacuum . in the emptiest places , there are still about 100,000 particles per cubic centimeter . but let 's say an experiment like that could somehow get every last atom out . there 's still an unfathomably huge amount of radiation all around us that can pass right through the walls . every second , about 50 muons from cosmic rays , 10 million neutrinos coming directly from the big bang , 30 million photons from the cosmic microwave background , and 300 trillion neutrinos from the sun pass through your body . it is possible to shield vacuum chambers with substances , including water , that absorb and reflect this radiation , except for neutrinos . let 's say you 've somehow removed all of the atoms and blocked all of the radiation . is the space now totally empty ? actually , no . all space is filled with what physicists call quantum fields . what we think of as subatomic particles , electrons and photons and their relatives , are actually vibrations in a quantum fabric that extends throughout the universe . and because of a physical law called the heisenberg principle , these fields never stop oscillating , even without any particles to set off the ripples . they always have some minimum fluctuation called a vacuum fluctuation . this means they have energy , a huge amount of it . because einstein 's equations tell us that mass and energy are equivalent , the quantum fluctuations in every cubic meter of space have an energy that corresponds to a mass of about four protons . in other words , the seemingly empty space inside your vacuum would actually weigh a small amount . quantum fluctuations have existed since the earliest moments of the universe . in the moments after the big bang , as the universe expanded , they were amplified and stretched out to cosmic scales . cosmologists believe that these original quantum fluctuations were the seeds of everything we see today : galaxies and the entire large scale structure of the universe , as well as planets and solar systems . they 're also the center of one of the greatest scientific mysteries of our time because according to the current theories , the quantum fluctuations in the vacuum of space ought to have 120 orders of magnitude more energy than we observe . solving the mystery of that missing energy may entirely rewrite our understanding of physics and the universe .
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every second , about 50 muons from cosmic rays , 10 million neutrinos coming directly from the big bang , 30 million photons from the cosmic microwave background , and 300 trillion neutrinos from the sun pass through your body . it is possible to shield vacuum chambers with substances , including water , that absorb and reflect this radiation , except for neutrinos . let 's say you 've somehow removed all of the atoms and blocked all of the radiation . is the space now totally empty ?
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after removing all the atoms and blocking all the radiation , what will remain in the space ?
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translator : andrea mcdonough reviewer : jessica ruby your car , the heating system in your house , your gas stove . most of the energy you use comes from fossil fuels , which present a couple of problems . first , there are limited supplies of fossil fuels , so the more we use , the less we 've got . and second , the use of fossil fuels is the main cause of climate change because it releases large amounts of carbon dioxide into the atmosphere . biofuels come from natural , renewable sources like plants , so they have the potential to reduce our reliance on those limited supply fossil fuels and reduce the risk of climate change . most biofuels today are made from corn grain that is fermented into ethanol . but we have a limited supply of this corn , so it 's not a solution to the limited supply part of the quandary . it also takes a lot of resources to grow corn grain . strike 2 ! a potential solution : using cellulose instead of corn grain to make ethanol . cellulose is far more abundant than corn grain and takes less energy to produce . in fact , it 's the most abundant organic molecule on the planet ! cellulose is the main ingredient found in a plant 's cell wall . plants generate cellulose from water and carbon dioxide during photosynthesis . so , where as using fossil fuels produce carbon dioxide , using cellulose-based ethanol might help remove carbon dioxide from the atmosphere . the main obstacle is that the cellulose molecule , a long , connected chain of glucose sugar protected by a tough , molecular sheath , is difficult to break apart . creating cellulose-based ethanol means first unwrapping that protective sheath and then chopping up the cellulose into its individual glucose molecule . only once we have unpacked each glucose molecule , can we begin fermentation . but some microorganisms , like bacteria or fungi , break down cellulose for energy all the time . for example , dairy cows eat foods like hay or alfalfa , which are full of cellulose . microbes that live in their stomachs produce an enzyme called cellulase , which breaks apart the cellulose molecules so that the cow can use what 's left for energy . researchers are now studying these kinds of microorganisms in the hopes of finding better ways to break down cellulose so we can use it for our own energy needs . the solution , they think , lies in finding microbes in nature that can produce the kinds of cellulase enzymes that we need . this process of searching for species in nature that can produce valuable products is called bioprospecting . to test whether or not a sample of microbes can break down cellulose effectively , researchers first grow the microbe in a test tube . then , they add a source of cellulose as the sole form of energy . if the microbe ca n't produce cellulase and break down cellulose , the test tube will remain unchanged . but if the microbe produces the enzymes we are looking for , it will be able to break down cellulose , use it for energy , and thrive in its test tube environment . if our microbial sample can break down the cellulose in the test tube , there is a chance we could use it to create a renewable and sustainable source of fuel for our cars from cellulose .
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but if the microbe produces the enzymes we are looking for , it will be able to break down cellulose , use it for energy , and thrive in its test tube environment . if our microbial sample can break down the cellulose in the test tube , there is a chance we could use it to create a renewable and sustainable source of fuel for our cars from cellulose .
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what is the main problem with trying to use cellulose as a source of biofuels ?
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this is a 20-minute vhs tape about a lego character called jack stone . when it came out in 2001 , it was the first real computer-animated lego movie . … but it hasn ’ t aged that well . `` incredible ! '' `` fantastic . '' thirteen years later , the lego movie looked like this : let ’ s watch that again . this is 2001 . `` there you have it . '' and this is 2014 . `` yes , that 's me . '' that is a huge difference . here ’ s how they made it happen . “ my name is grant freckelton , i ’ m a production designer at animal logic. ” he ’ s overseen the animation style of movies like legend of the guardians , 300 , and more recently , the lego movie , with co-directors chris miller and phil lord . “ chris and phil were determined to sort of make sure the audience was confused about what they were seeing . you know is it actually stop motion , or is it cg film ? ” and that became a big debate . before the movie came out , there was a lot of conversation about whether the movie was stop motion or computer animation . `` it is , i would say 99 % cg animation , but it respects the rules of stop motion animation , and is designed to emulate that style. ” to understand what made that style so unique , you have to look back at what lego movies used to look like . early productions for themes like bionicle , star wars , and batman helped establish the whimsical feel of lego movies — but the animation didn ’ t fit the physics of the toy itself . “ there was this tendency to sort of treat the plastic like it was flexible rubber , which meant that the characters could flex and move a lot more than they might be able to in real life. ” that style is typical of more traditional computer animation , like what you ’ d expect to see in a pixar movie . take a shot like this , for example . the background isn ’ t made of actual blocks , plastic limbs are bending in ways they couldn ’ t , and the faces are a bizarre blend of skin-like texture and lego geometry . it doesn ’ t look like a scene you could make at home with your own legos . compare that to scenes from the lego movie , where everything — gunshots , smoke , water , fire , explosions , clouds , even mud on the camera lens — are all made up of lego pieces as they look in real life . “ we respected the hardness of the plastic by not necessarily bending on the elbow , which you can ’ t do on a real lego minifig. ” that means that any movement you see onscreen simulates the adjustment or replacement of an individual lego piece . a joint or facial expression will never actually bend or stretch — it ’ ll either move slightly or be replaced by another piece . early lego movies lacked that level of discipline . they struggled because they fought back against the limitations of the medium instead of embracing them . but the creators of the lego movie saw things differently . “ characters that have limitations force you to find solutions and charming ways of doing things in different ways . i mean , look at r2-d2 : he ’ s like , the ultimate limited character , he ’ s basically a bin with wheels that makes beeping noises , and that ’ s all he 's got to work with . and yet he ’ s a really charming character and everybody loves him . same with bb-8 . and other characters . same with the muppets , they ’ re essentially sock puppets with googly eyes that you do n't really have much control over . but it ’ s from those limitations that you actually get a lot of charm. ” every now and then , the lego movie animators would let some joints overextend slightly to make room for a nod or a shrug of the shoulders ... but overall , sticking to the plastic rule made for a believable movie . you can freeze frame any part of the lego movie and look at a scene that you could practically make at home . “ we were always trying to echo and hark back to how a child might make a film . so we would alternate between thinking like responsible filmmakers working on a large-budget warner brothers animated film , and then we would suddenly approach a scene as if we were like a kid animating in their basement. ” but the history of lego movies actually does start with kids animating in their basements . in 1973 , two danish cousins , aged 10 and 12 , shot a short film called journey to the moon on super 8 film . they made it for their grandparents ’ 50th wedding anniversary — and it ’ s widely considered to be the first time anyone made a motion picture with lego blocks . note that the “ people ” in this film are just little cylinder blocks — this was before any version of the minifigure design came out . movies like this came to be known as “ brickfilms. ” when fans were making these at home , they shot them in traditional stop motion . footage was usually shot “ on twos , ” which meant that they would take 12 pictures — adjusting the characters every other frame — to make one second of film . shooting “ on ones ” meant taking 24 pictures per second — this was usually reserved for making faster movements like running look smoother . when the danish cousins sent their movie to the managing director of the lego group , they were rewarded with a tour of the lego factory and sent home with large lego sets . but lego hasn ’ t always had the most positive reaction to homemade fan films like this one . between 1985 and 1989 , a teenage animator named lindsay fleay worked on a 16-minute short called the magic portal . he used borrowed equipment to shoot it in his parents ’ basement . before entering festivals and competitions , fleay sent the film to lego to see if they were interested in doing something with it . at first , lego responded with a letter of approval . but soon , the company started expressing legal concerns and issued a letter demanding fleay surrender all copies of the film within seven days . lego ultimately backed down , but fleay had already missed out on most major film festivals by then . fleay actually went on to work at animal logic . he left before production on lego projects began , but his movie had a huge influence on the world of brickfilms . “ if you look at the live action portion of the lego movie , you 'll see finn , the little kid , holds up a sort of cardboard tube and across the side is written magic portal . '' the lego movie , of course , was a huge technical feat . there are 15,080,330 animated lego pieces and 182 unique minifigures in the movie . early mockups of buildings and vehicles were drafted on a free software called lego digital designer later on , in the animation software maya , each brick was given profiles for fingerprints , dents , seam lines , scratches , and dust . it ’ s hard to imagine what the lego movie would be if it weren ’ t for the legacy of these early home experiments . where most animated films use soft lighting modeled after paintings , the lego movie ’ s lighting was harsh , replicating the actual lamps that animators like fleay used . playful non-stop motion interludes — like levitation via fishing line — were part of journey to the moon long before they appeared in the lego movie . even the final break from the lego world into the real world to meet a human creator parallels the magic portal really closely . ah , my film ! it ’ s easy to miss on-screen , but the lego movie pays tribute to fan films in the background of this scene — these four clips are shorts submitted by fans . “ look at all these things that people built ! ” the homage was a nod to the fans . by doing that , the movie embraced the idea that amateur creators matter — and sometimes , the way they handle source material is far better than the way major studios are used to doing it . if you want to try any of this at home , you can actually use the same software that the animators of the lego movie used . it ’ s called lego digital designer , it ’ s totally free off the internet . when i talked to grant freckelton , he challenged me to make this sort of pig-drawn carriage . i tried . i got the pigs , i got the wheels , but not much else . it ’ s very , very difficult .
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but overall , sticking to the plastic rule made for a believable movie . you can freeze frame any part of the lego movie and look at a scene that you could practically make at home . “ we were always trying to echo and hark back to how a child might make a film .
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why do you think it mattered to the creators that you can freeze almost any scene and re-create it at home ?
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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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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 .
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which of the following is not used to treat allergies ?
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dating back at least to the time of socrates , some early societies decided that certain disputes , such as whether a person committed a particular crime , should be heard by a group of citizens . several centuries later , trial by jury was introduced to england , where it became a fundamental feature of the legal system , checking the government and involving citizens in decision-making . juries decided whether defendants would be tried on crimes , determined whether the accused defendants were guilty , and resolved monetary disputes . while the american colonies eventually cast off england 's rule , its legal tradition of the jury persisted . the united states constitution instructed a grand jury to decide whether criminal cases proceeded , required a jury to try all crimes , except impeachment , and provided for juries in civil cases as well . yet , in the us today , grand juries often are not convened , and juries decide less than 4 % of criminal cases and less than 1 % of civil cases filed in court . that 's at the same time as jury systems in other countries are growing . so what happened in the u.s. ? part of the story lies in how the supreme court has interpreted the constitution . it 's permitted plea bargaining , which now occurs in almost every criminal case . the way it works is the prosecutor presents the accused with a decision of whether to plead guilty . if they accept the plea , the case wo n't go in front of a jury , but they 'll receive a shorter prison sentence than they 'd get if a jury did convict them . the risk of a much greater prison sentence after a trial can frighten even an innocent defendant into taking a plea . between the 19th century and the 21st century , the proportion of guilty pleas has increased from around 20 % to 90 % , and the numbers continue to grow . the supreme court has permitted the use of another procedure that interferes with the jury called summary judgement . using summary judgement , judges can decide that civil trials are unnecessary if the people who sue have insufficient evidence . this is intended only for cases where no reasonable jury would disagree . that 's a difficult thing to determine , yet usage of summary judgement has stretched to the point where some would argue it 's being abused . for instance , judges grant fully , or in part , over 70 % of employers ' requests to dismiss employment discrimination cases . in other cases , both the person who sues and the person who defends forgo their right to go to court , instead resolving their dispute through a professional arbitrator . these are generally lawyers , professors , or former judges . arbitration can be a smart decision by both parties to avoid the requirements of a trial in court , but it 's often agreed to unwittingly when people sign contracts like employment applications and consumer agreements . that can become a problem . for example , some arbitrators may be biased towards the companies that give them cases . these are just some of the ways in which juries have disappeared . but could the disappearance of juries be a good thing ? well , juries are n't perfect . they 're costly , time-consuming , and may make errors . and they 're not always necessary , like when people can simply agree to settle their disputes . but juries have their advantages . when properly selected , jurors are more representative of the general population and do n't have the same incentives as prosecutors , legislators , or judges seeking reelection or promotion . the founders of the united states trusted in the wisdom of impartial groups of citizens to check the power of all three branches of government . and the jury trial itself has given ordinary citizens a central role in upholding the social fabric . so will the jury system in the u.s. survive into the future ?
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part of the story lies in how the supreme court has interpreted the constitution . it 's permitted plea bargaining , which now occurs in almost every criminal case . the way it works is the prosecutor presents the accused with a decision of whether to plead guilty .
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for what reason would a criminal defendant plead guilty in a plea bargaining arrangement with the prosecutor ?
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ah , romantic love - beautiful and intoxicating , heartbreaking and soul-crushing , often all at the same time . why do we choose to put ourselves through its emotional wringer ? does love make our lives meaningful , or is it an escape from our loneliness and suffering ? is love a disguise for our sexual desire , or a trick of biology to make us procreate ? is it all we need ? do we need it at all ? if romantic love has a purpose , neither science nor psychology has discovered it yet . but over the course of history , some of our most respected philosophers have put forward some intriguing theories . love makes us whole , again . the ancient greek philosopher plato explored the idea that we love in order to become complete . in his `` symposium '' , he wrote about a dinner party , at which aristophanes , a comic playwright , regales the guests with the following story : humans were once creatures with four arms , four legs , and two faces . one day , they angered the gods , and zeus sliced them all in two . since then , every person has been missing half of him or herself . love is the longing to find a soulmate who 'll make us feel whole again , or , at least , that 's what plato believed a drunken comedian would say at a party . love tricks us into having babies . much , much later , german philosopher arthur schopenhauer maintained that love based in sexual desire was a voluptuous illusion . he suggested that we love because our desires lead us to believe that another person will make us happy , but we are sorely mistaken . nature is tricking us into procreating , and the loving fusion we seek is consummated in our children . when our sexual desires are satisfied , we are thrown back into our tormented existences , and we succeed only in maintaining the species and perpetuating the cycle of human drudgery . sounds like somebody needs a hug . love is escape from our loneliness . according to the nobel prize-winning british philosopher bertrand russell , we love in order to quench our physical and psychological desires . humans are designed to procreate , but without the ecstasy of passionate love , sex is unsatisfying . our fear of the cold , cruel world tempts us to build hard shells to protect and isolate ourselves . love 's delight , intimacy , and warmth helps us overcome our fear of the world , escape our lonely shells , and engage more abundantly in life . love enriches our whole being , making it the best thing in life . love is a misleading affliction . siddhārtha gautama , who became known as the buddha , or the enlightened one , probably would have had some interesting arguments with russell . buddha proposed that we love because we are trying to satisfy our base desires . yet , our passionate cravings are defects , and attachments , even romantic love , are a great source of suffering . luckily , buddha discovered the eight-fold path , a sort of program for extinguishing the fires of desire so that we can reach nirvana , an enlightened state of peace , clarity , wisdom , and compassion . the novelist cao xueqin illustrated this buddhist sentiment that romantic love is folly in one of china 's greatest classical novels , `` dream of the red chamber . '' in a subplot , jia rui falls in love with xi-feng who tricks and humiliates him . conflicting emotions of love and hate tear him apart , so a taoist gives him a magic mirror that can cure him as long as he does n't look at the front of it . but of course , he looks at the front of it . he sees xi-feng . his soul enters the mirror and he is dragged away in iron chains to die . not all buddhists think this way about romantic and erotic love , but the moral of this story is that such attachments spell tragedy , and should , along with magic mirrors , be avoided . love lets us reach beyond ourselves . let 's end on a slightly more positive note . the french philosopher simone de beauvoir proposed that love is the desire to integrate with another and that it infuses our lives with meaning . however , she was less concerned with why we love and more interested in how we can love better . she saw that the problem with traditional romantic love is it can be so captivating , that we are tempted to make it our only reason for being . yet , dependence on another to justify our existence easily leads to boredom and power games . to avoid this trap , beauvoir advised loving authentically , which is more like a great friendship . lovers support each other in discovering themselves , reaching beyond themselves , and enriching their lives and the world together . though we might never know why we fall in love , we can be certain that it will be an emotional rollercoaster ride . it 's scary and exhilarating . it makes us suffer and makes us soar . maybe we lose ourselves . maybe we find ourselves . it might be heartbreaking , or it might just be the best thing in life . will you dare to find out ?
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let 's end on a slightly more positive note . the french philosopher simone de beauvoir proposed that love is the desire to integrate with another and that it infuses our lives with meaning . however , she was less concerned with why we love and more interested in how we can love better .
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simone de beauvoir recommended loving :
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imagine you 're on a game show , and you can choose between two prizes : a diamond or a bottle of water . it 's an easy choice . the diamonds are clearly more valuable . now imagine being given the same choice again , only this time , you 're not on a game show , but dehydrated in the desert after wandering for days . do you choose differently ? why ? are n't diamonds still more valuable ? this is the paradox of value , famously described by pioneering economist adam smith . and what it tells us is that defining value is not as simple as it seems . on the game show , you were thinking about each item 's exchange value , what you could obtain for them at a later time , but in an emergency , like the desert scenario , what matters far more is their use value , how helpful they are in your current situation . and because we only get to choose one of the options , we also have to consider its opportunity cost , or what we lose by giving up the other choice . after all , it does n't matter how much you could get from selling the diamond if you never make it out of the desert . most modern economists deal with the paradox of value by attempting to unify these considerations under the concept of utility , how well something satisfies a person 's wants or needs . utility can apply to anything from the basic need for food to the pleasure of hearing a favorite song , and will naturally vary for different people and circumstances . a market economy provides us with an easy way to track utility . put simply , the utility something has to you is reflected by how much you 'd be willing to pay for it . now , imagine yourself back in the desert , only this time , you get offered a new diamond or a fresh bottle of water every five minutes . if you 're like most people , you 'll first choose enough water to last the trip , and then as many diamonds as you can carry . this is because of something called marginal utility , and it means that when you choose between diamonds and water , you compare utility obtained from every additional bottle of water to every additional diamond . and you do this each time an offer is made . the first bottle of water is worth more to you than any amount of diamonds , but eventually , you have all the water you need . after a while , every additional bottle becomes a burden . that 's when you begin to choose diamonds over water . and it 's not just necessities like water . when it comes to most things , the more of it you acquire , the less useful or enjoyable every additional bit becomes . this is the law of diminishing marginal utility . you might gladly buy two or three helpings of your favorite food , but the fourth would make you nauseated , and the hundredth would spoil before you could even get to it . or you could pay to see the same movie over and over until you got bored of it or spent all of your money . either way , you 'd eventually reach a point where the marginal utility for buying another movie ticket became zero . utility applies not just to buying things , but to all our decisions . and the intuitive way to maximize it and avoid diminishing returns is to vary the way we spend our time and resources . after our basic needs are met , we 'd theoretically decide to invest in choices only to the point they 're useful or enjoyable . of course , how effectively any of us manage to maximize utility in real life is another matter . but it helps to remember that the ultimate source of value comes from us , the needs we share , the things we enjoy , and the choices we make .
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on the game show , you were thinking about each item 's exchange value , what you could obtain for them at a later time , but in an emergency , like the desert scenario , what matters far more is their use value , how helpful they are in your current situation . and because we only get to choose one of the options , we also have to consider its opportunity cost , or what we lose by giving up the other choice . after all , it does n't matter how much you could get from selling the diamond if you never make it out of the desert .
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amy can either eat an apple or an orange . what is the opportunity cost of eating the apple ?
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you and nine other individuals have been captured by super intelligent alien overlords . the aliens think humans look quite tasty , but their civilization forbids eating highly logical and cooperative beings . unfortunately , they 're not sure whether you qualify , so they decide to give you all a test . through its universal translator , the alien guarding you tells you the following : you will be placed in a single-file line facing forward in size order so that each of you can see everyone lined up ahead of you . you will not be able to look behind you or step out of line . each of you will have either a black or a white hat on your head assigned randomly , and i wo n't tell you how many of each color there are . when i say to begin , each of you must guess the color of your hat starting with the person in the back and moving up the line . and do n't even try saying words other than black or white or signaling some other way , like intonation or volume ; you 'll all be eaten immediately . if at least nine of you guess correctly , you 'll all be spared . you have five minutes to discuss and come up with a plan , and then i 'll line you up , assign your hats , and we 'll begin . can you think of a strategy guaranteed to save everyone ? pause the video now to figure it out for yourself . answer in : 3 answer in : 2 answer in : 1 the key is that the person at the back of the line who can see everyone else 's hats can use the words `` black '' or `` white '' to communicate some coded information . so what meaning can be assigned to those words that will allow everyone else to deduce their hat colors ? it ca n't be the total number of black or white hats . there are more than two possible values , but what does have two possible values is that number 's parity , that is whether it 's odd or even . so the solution is to agree that whoever goes first will , for example , say `` black '' if he sees an odd number of black hats and `` white '' if he sees an even number of black hats . let 's see how it would play out if the hats were distributed like this . the tallest captive sees three black hats in front of him , so he says `` black , '' telling everyone else he sees an odd number of black hats . he gets his own hat color wrong , but that 's okay since you 're collectively allowed to have one wrong answer . prisoner two also sees an odd number of black hats , so she knows hers is white , and answers correctly . prisoner three sees an even number of black hats , so he knows that his must be one of the black hats the first two prisoners saw . prisoner four hears that and knows that she should be looking for an even number of black hats since one was behind her . but she only sees one , so she deduces that her hat is also black . prisoners five through nine are each looking for an odd number of black hats , which they see , so they figure out that their hats are white . now it all comes down to you at the front of the line . if the ninth prisoner saw an odd number of black hats , that can only mean one thing . you 'll find that this strategy works for any possible arrangement of the hats . the first prisoner has a 50 % chance of giving a wrong answer about his own hat , but the parity information he conveys allows everyone else to guess theirs with absolute certainty . each begins by expecting to see an odd or even number of hats of the specified color . if what they count does n't match , that means their own hat is that color . and everytime this happens , the next person in line will switch the parity they expect to see . so that 's it , you 're free to go . it looks like these aliens will have to go hungry , or find some less logical organisms to abduct .
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you 'll find that this strategy works for any possible arrangement of the hats . the first prisoner has a 50 % chance of giving a wrong answer about his own hat , but the parity information he conveys allows everyone else to guess theirs with absolute certainty . each begins by expecting to see an odd or even number of hats of the specified color . if what they count does n't match , that means their own hat is that color . and everytime this happens , the next person in line will switch the parity they expect to see .
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what process does each person after the first use to figure out their hat color ?
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translator : tom carter reviewer : bedirhan cinar the most important walls in western history are n't even in the west . they surround the modern city of istanbul , constantinople as the romans called it . and for a thousand years , the fate of europe depended on them . constantinople was designed to be the center of the world . when the frontiers of the roman empire began to crumble in the 4th century , the capital was moved to the cultured , wealthy , and still stable east . there , at the crossroads between europe and asia , the hub of the major trade routes of the ancient world , the emperor constantine built his city . this was the city of libraries and universities , 20 times the size of london or paris at the time . it contained the priceless knowledge of the classical world which was fading in the west . to protect this masterpiece from its many enemies , constantine 's successors built the finest defensive fortifications ever made . the first line of protection was a moat 60 feet wide and 22 feet deep , stretching all four miles from coast to coast . pipes from inside the city could fill it at the first sight of the enemy , and a short wall protected archers who could fire at the soaked soldiers trying to swim across . those who were lucky enough to clear the moat had to contend with an unceasing barrage from the 27 foot outer wall above . arrows , spears , or far worse , greek fire -- an ancient form of napalm that would ignite on contact and could n't be extinguished by water -- would rain down on them . squads of roman defenders would carry portable flame throwers , spraying anyone trying to climb out of the moat . the terrified victims would leap back , only to find that they still burned underwater . at times , the romans would also mount siphons onto the ramparts , and launch clay pots full of greek fire from catapults at an invading army . the front lines would turn into an inferno , making it appear as if the earth itself was on fire . if , by some miracle , the outer wall was compromised , attackers would be faced with the final defense : the great inner wall . these walls were wide enough to have four men ride side by side , allowing troops to be rushed wherever they were needed . attilla the hun , destroyer of civilizations , who named himself the scourge of god , took one look at them and turned around . the avars battled the walls uselessly til their catapults ran out of rocks . the turks tried to tunnel under them , but found the foundations too solid . the arabs tried to starve the city into submission , but ran out of food themselves and had to resort to cannibalism . it took the guns of the modern world to finally bring them down . in 1453 , the turks brought their super weapon : a monster cannon that could fire a 15 hundred pound stone ball over a mile . together with more than a hundred smaller guns , they kept up a steady bombardment day and night . a section of the old walls collapsed , but even in their death throes they proved formidable . the rubble absorbed the shock of the cannonballs better than the solid wall . it took a month and a half of continuous blasting to finally open a breach . the last roman emperor , constantine the 11th , drew his sword and jumped into the gap to stop the onrushing horde , disappearing into legend . the city was taken , and the roman empire finally disappeared . but those broken walls had one last gift . as the survivors fled the doomed city , they brought with them their precious books and their ancient traditions . they traveled west to italy , reintroduced the greek language and learning to western europe , and ignited the renaissance . thanks to constantinople 's walls , that pile of brick and marble that guarded them for so long , we still have our classical past .
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they surround the modern city of istanbul , constantinople as the romans called it . and for a thousand years , the fate of europe depended on them . constantinople was designed to be the center of the world . when the frontiers of the roman empire began to crumble in the 4th century , the capital was moved to the cultured , wealthy , and still stable east .
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how might the world be different if constantinople hadn ’ t successfully defended itself for a thousand years ? how would western history look without most of its greek and roman legacy ?
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translator : andrea mcdonough reviewer : bedirhan cinar so as an astronomer , when i look at the sky with other people , they always ask me , `` what is your favorite place in the universe ? what is your favorite galaxy ? what is your favorite planet ? '' my answer is earth . that 's right . this is a very special place , even for an astronomer . we look at a lot of places , but there 's only one that we know of in the whole universe that we can live on . it 's an amazing planet , there is an amazing number of things happening , some of them , you are hearing about it today . that 's the only place in the universe where we know that there is life , so that makes it extremely special . what i 'm going to talk to you about is this great adventure in astronomy that is happening where we are actually actively looking for other places like this . it 's impossible to imagine the number of possibilities , what happens on those other planets that can be habitable . so that 's what i 'm going to tell you about . so , the first thing we have to think of is , well , what makes a planet habitable ? and , the easiest thing to do is to look at our own solar system . we have multiple examples . the first thing we learn is that size matters . we ca n't have a planet that 's too small or too big . if we look at a planet that is too small , it does n't have an atmosphere . the moon , technically not a planet , but a good example for this , is too small , it does n't hold an atmosphere . jupiter - very , very big - and it actually is mostly composed of gas , it has no surface you can stand on . the earth is just right . the second thing that we learned is that the planet has to be at the right distance from its star . if the planet is too close to its star , it 's too hot . that 's the case for venus . here i have a picture that was taken by a spacecraft that landed on venus , and the surface , although it 's rocky and quite familiar to us compared to earth , it 's really too hot . at the opposite end , if a planet is too far from the star , it is too cold . that 's the case for mars . so , we need to look for planets that are at the right distance from their star and also of the right size . so , one other thing , you know , you might think , `` oh , this is really hard because the planet has to be just right . it only happened once in our solar system . '' but when you look at the sky at night , and here 's a video that i took actually from hawaii , a dark place where you can see a lot of stars , the first thing you notice is that there are a lot of stars . so , the odds are in our favor , even if a small fraction of the stars have habitable planets . there are a lot of stars . on a moonless night , in a dark site , if you count the stars in the sky and you count five stars per second , it would take you 15 minutes to count all of the stars in the sky . that is a tiny fraction of the stars in our galaxy . if you count all the stars in our galaxy , and you also count at five stars per second , it would take you more than 1,000 years to count all the stars in our galaxy . and then , if you manage to count the galaxies in the universe , if you count five galaxies per second , it would take you also more than 1,000 years to count all of the galaxies in the universe . so the numbers are just astronomical , there 's a lot of opportunities for exoplanets . there has to be a large number of exoplanets along which there are , on which there could be life . so this is very exciting . so let 's imagine that maybe only 1 in 100 stars has the right kind of planet , and i think this is pessimistic . if you could visit one of those planets per second , it 'll take you sixty years to actually visit all of them in our galaxy alone . that 's , i think , one second is not enough to study them . so , there 's a few hundred of us in this room . if we divided the task and each of us basically took a couple of minutes to study each planet , it would take us a life time to do this . meet back again and tell those amazing stories of what we would have seen in maybe some ted senior event . so , why is it hard ? why do n't we have pictures of exoplanets with aliens on them ? well , here 's an example . this is a picture that was taken by the cassinni spacecraft as it was orbiting saturn . it 's actually behind saturn , so what you see is the sun that is blocked by saturn . and if you look very , in detail , if you have very sharp eyesight , you will see all of us . we 're all on that picture . here is where we are . um , so that 's what earth starts to look like when we look at it from far away . now , we have to do the same thing around other stars , and the planet is very close to the star . so this is zooming in to us . all of us are on that little dot at the time the picture was taken . so , what i work on is inventing optics , tricks to actually do this , to take images of planets around those other stars . this is my easiest coronagraph . we call this optic tricks , `` coronagraph '' . this is the easiest one i ever built . i just put my thumb in front of the sun and then you can see things around it . that 's what we 're trying to do , but we need to do it much better than what i did in this picture . and , there are two things we need to do : we need a much better eye , call them telescopes , and we need more fancy , clever ways to do it than putting a thumb . so as an example , one of the projects i work on is for the subaru telescope , which you can see here in this picture . it 's a very large telescope , so i replace my eye by a large telescope . and , the other thing that we do is the coronagraph is not just a stupid thumb , it 's this very complicated thing that 's shown in that picture that i would love to have time to tell you about . just to give you a sense for size , this arrow points to a door on the side of the telescope , and if you have very sharp eyes , you can see that there is a railing going around the telescope , so it 's a really big eye . so , i think the most exciting thing for me is actually to look at the night sky , to see all these stars and wonder , `` well , are there people on planets around those stars ? '' because there must be amazing things happening around those stars that we do n't know yet . during your life time , we will start to actually figure out those things . and the most exciting thing for me is to think about , maybe , beings on those stars looking back at our star and wondering the same thing . so i think the future will be extremely exciting because we are starting to figure out those things and amazing range of possibilities is , i think , even wider than our imagination . thank you .
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translator : andrea mcdonough reviewer : bedirhan cinar so as an astronomer , when i look at the sky with other people , they always ask me , `` what is your favorite place in the universe ? what is your favorite galaxy ?
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what is coronagraphy ?
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they say the pen is mightier than the sword , and authorities have often agreed . from outlawed religious tracts and revolutionary manifestos to censored and burned books , we know the potential power of words to overturn the social order . but as strange as it may seem , some numbers have also been considered dangerous enough to ban . our distant ancestors long counted objects using simple tally marks . but as they developed agriculture and began living together in larger groups , this was no longer enough . as numbers grew more complex , people began not just using them , but thinking about what they are and how they work . and by 600 b.c.e . in ancient greece , the study of numbers was well-developed . the mathematician pythagoras and his school of followers found numerical patterns in shapes , music , and the stars . for them , mathematics held the deepest secrets of the universe . but one pythagorean named hippasus discovered something disturbing . some quantities , like the diagonal of a square with sides of length one could n't be expressed by any combination of whole numbers or fractions , no matter how small . these numbers , which we call irrational numbers , were perceived as a threat to the pythagorean 's notion of a perfect universe . they imagined a reality that could be described with rational , numerical patterns . historians write that hippasus was exhiled for publicizing his findings , while legends claim he was drowned as punishment from the gods . while irrational numbers upset philosophers , later mathematical inventions would draw attention from political and religious authorities , as well . in the middle ages , while europe was still using roman numerals , other cultures had developed positional systems that included a symbol for zero . when arab travelers brought this system to the bustling maritime cities of italy , its advantages for merchants and bankers was clear . but the authorities were more wary . hindu-arabic numerals were considered easier to forge or alter , especially since they were less familiar to customers than to merchants . and the concept of zero opened the door to negative numbers and the recording of debt at a time when moneylending was regarded with suspicion . in the 13th century , florence banned the use of hindu-arabic numerals for record keeping . and though they soon proved too useful to ignore , controversies over zero and negative numbers continued for a long time . negative numbers were dismissed as absurd well into the 19th century . and prominent mathematicians , like gerolamo cardano , avoided using zero , even though it would have made it much easier to find solutions to cubic and the quartic equations . even today it 's illegal to use some numbers for different reasons . some are banned because of what they represent . for example , governments have prohibited the display of numbers that have symbolic meaning , such as the date of a revolution or connections to oppositional political figures or parties . other numbers are potentially illegal because of the information they carry . just about any information , whether text , image , video , or executable programs can be translated into a string of numbers . but this means that protected information , whether copyrights , proprietary materials , or state secrets can also be represented as numbers , so possessing or publishing these numbers may be treated as a criminal offense . this idea gathered attention in 2001 when code that could be used to decrypt dvds was widely shared and distributed in the form of a large prime number . the idea of illegal numbers may sound absurd , but like words , written numbers are a way of expressing concepts and information . and in a world where calculations and algorithms shape more and more of our lives , the mathematician 's pencil grows stronger by the day .
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but as strange as it may seem , some numbers have also been considered dangerous enough to ban . our distant ancestors long counted objects using simple tally marks . but as they developed agriculture and began living together in larger groups , this was no longer enough .
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our distant ancestors counted objects using :
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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 ♪ ] 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 .
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how can art help us understand ourselves ?
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modern computers are revolutionizing our lives , performing tasks unimaginable only decades ago . this was made possible by a long series of innovations , but there 's one foundational invention that almost everything else relies upon : the transistor . so what is that , and how does such a device enable all the amazing things computers can do ? well , at their core , all computers are just what the name implies , machines that perform mathematical operations . the earliest computers were manual counting devices , like the abacus , while later ones used mechanical parts . what made them computers was having a way to represent numbers and a system for manipulating them . electronic computers work the same way , but instead of physical arrangements , the numbers are represented by electric voltages . most such computers use a type of math called boolean logic that has only two possible values , the logical conditions true and false , denoted by binary digits one and zero . they are represented by high and low voltages . equations are implemented via logic gate circuits that produce an output of one or zero based on whether the inputs satisfy a certain logical statement . these circuits perform three fundamental logical operations , conjunction , disjunction , and negation . the way conjunction works is an `` and gate '' provides a high-voltage output only if it receives two high-voltage inputs , and the other gates work by similar principles . circuits can be combined to perform complex operations , like addition and subtraction . and computer programs consist of instructions for electronically performing these operations . this kind of system needs a reliable and accurate method for controlling electric current . early electronic computers , like the eniac , used a device called the vacuum tube . its early form , the diode , consisted of two electrodes in an evacuated glass container . applying a voltage to the cathode makes it heat up and release electrons . if the anode is at a slightly higher positive potential , the electrons are attracted to it , completing the circuit . this unidirectional current flow could be controlled by varying the voltage to the cathode , which makes it release more or less electrons . the next stage was the triode , which uses a third electrode called the grid . this is a wire screen between the cathode and anode through which electrons could pass . varying its voltage makes it either repel or attract the electrons emitted by the cathode , thus , enabling fast current-switching . the ability to amplify signals also made the triode crucial for radio and long distance communication . but despite these advancements , vacuum tubes were unreliable and bulky . with 18,000 triodes , eniac was nearly the size of a tennis court and weighed 30 tons . tubes failed every other day , and in one hour , it consumed the amount of electricity used by 15 homes in a day . the solution was the transistor . instead of electrodes , it uses a semiconductor , like silicon treated with different elements to create an electron-emitting n-type , and an electron absorbing p-type . these are arranged in three alternating layers with a terminal at each . the emitter , the base , and the collector . in this typical npn transistor , due to certain phenomena at the p-n interface , a special region called a p-n junction forms between the emitter and base . it only conducts electricity when a voltage exceeding a certain threshold is applied . otherwise , it remains switched off . in this way , small variations in the input voltage can be used to quickly switch between high and low-output currents . the advantage of the transistor lies in its efficiency and compactness . because they do n't require heating , they 're more durable and use less power . eniac 's functionality can now be surpassed by a single fingernail-sized microchip containing billions of transistors . at trillions of calculations per second , today 's computers may seem like they 're performing miracles , but underneath it all , each individual operation is still as simple as the flick of a switch .
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tubes failed every other day , and in one hour , it consumed the amount of electricity used by 15 homes in a day . the solution was the transistor . instead of electrodes , it uses a semiconductor , like silicon treated with different elements to create an electron-emitting n-type , and an electron absorbing p-type .
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what material is used to fabricate a transistor ?
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can you imagine a party where every movement , from the slightest gesture to walking across the room , and every visual detail , from furniture to hemline length , were governed by a complex system of rules and procedures ? for centuries , such rituals were commonplace for european nobility . and while they 've gone out of fashion , we recognize the components under a familiar label : ballet . ballet , from italian `` balletto , '' or little dance , originated in renaissance italy as a combination of social dance and choreographed display at aristocratic gatherings . in many aspects , it was a way of controlling people in court with acceptable forms of behavior , such as the manner in which people stepped , bowed , or took someone 's hand . it also involved rules governing everything from attire to where one could walk or sit in relation to the king . over time , the study of ballet became a central element of court life , and proper grasp of the etiquette could make or break one 's success as a courtier . many of these court gestures can still be seen in modern ballet techniques . ballet was brought to france in the 16th century by catherine de ' medici , the italian wife of king henry ii . as celebrations became more lavish , so did the dance , with dancing masters teaching elaborate steps to young nobles and story elements providing a unifying theme . the focus shifted from participation to performance , and the form acquired more theatrical trappings , such as professionally designed sets and a slightly raised platform or stage with curtains and wings . but it was in the 17th century court of louis xiv that ballet was refined into the art we know today . louis himself had been trained in ballet from childhood . his early role as the sun god apollo at age fifteen cemented the central role ballet would play during his reign . it also earned him the title of sun king , with his splendid golden costume and choreography that promoted the idea of the king as a divinely ordained ruler . louis would go on to perform 80 roles in 40 major ballets , either as a majestic lead , or sometimes playing minor or comedic parts before emerging in the lead role as the end . he trained daily in ballet , as well as fencing and riding , and through his example , dancing became an essential skill for all gentlemen of the era . but louis xiv 's main contribution to ballet was not as a performer . his founding of the royal academy of dance in 1661 shifted control of ballet from local guilds to the royal court . as director , he appointed his personal ballet master and frequent performance partner pierre beauchamp , who codified the five main positions of the body still used today . through is collaborations with jean-baptiste lully , the director of the royal music academy , and famed playwright molière , beauchamp helped establish ballet as a grand spectacle . and in 1669 , a separate ballet academy was founded . the paris opera ballet survives today as the oldest ballet company in the world . ballet moved away from the royal court to the theater and survived the democratic revolutions and reforms that followed over the next century . with the advent of the romantic movement , fantasy and folklore themes became common motifs . and though the influence of ballet in france would decline , other countries , such as russia , would play a major role in its further development . fortunately , today most of us do n't have to learn a complicated set of steps just to socialize at a wedding . instead , we can go to the theater to see professionals who spend their lives training rigorously to perform feats that would have been unimagineable in louis xiv 's day .
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he trained daily in ballet , as well as fencing and riding , and through his example , dancing became an essential skill for all gentlemen of the era . but louis xiv 's main contribution to ballet was not as a performer . his founding of the royal academy of dance in 1661 shifted control of ballet from local guilds to the royal court .
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louis xiv ’ s main contribution to ballet was as ( a ) :
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( music ) aw , thank you , thank you . as you can probably tell , i 'm an astronaut . no , i 'm a dj/producer , as it says on the screen . i am also a high school student , just like many of you guys . how many high school students do we have out here ? ( cheers ) oh , okay ! a good amount . i 'm a proud member of my school 's marching band , and i run track , as well , so if any of you guys are into that , it 's one of my other passions . i have been djing and producing for a little over three years now , and i 've worked with artists that you may know , like avicii , skrillex , major lazer , krewella , porter robinsion , carnage , and many others . how many of you guys like dance music ? show off hands , dance music , oh okay . how many of you guys like rap or trap hip hop ? okay , good amount . jazz ? classical ? that 's good , you guys have smart minds , that 's good . what 's great about djing is that you can combine all these genres into one idea , and what i like to do is combine dance , hip hop , trap , dubstep , even movie samples , and kind of combine them into one set . djing creates this , sort of , combined culture that really unites many fans . a good example of this is skrillex and a $ ap rocky 's collaboration `` wild for the night '' or , most recently , avicii and ella black 's `` wake me up . '' how many of you guys know that song ? it 's a great track . now , what exactly does a dj do ? well , as you just saw earlier , they mix tracks . what i just did was mix a kanye west intro from `` black skinheads '' with a track called `` lrad . '' one of the main goals is to really trigger samples , tracks , or clips and kind of create this long journey . i 'm going to do another little example for you guys right now of what djs call a `` mashup , '' which is taking two or more tracks and combining them into one . this mashup was made famous by a hungarian duo myon & amp ; amp ; shane 54 , and it takes the vocals from krewella 's `` alive . '' how many of you guys know that song ? `` alive '' ? yeah , okay . i 'm going to take the vocals from that track and the song `` language '' by porter robinson . so , let me just play you the vocals first . ( music ) so , that 's the vocals , and here 's the actual track . ( music ) so , what i 'm going to do is i 'm going to fill these vocals on top of the track and create a new song , a kind of combined song , with the two vocals . ( music ) if you turn it down , you can just hear i 'm playing it a capella or just the song by itself . ( music ) now , what i 'm going to do after this drops is change it into another song . one of the most important things about dance music is really the drop , so i 'm going to change it into another song and really catch you by surprise . ( music ) and that 's one example right there . ( applause ) so , as you saw , i took three different songs and kind of combined them into one new idea , which is something plenty of djs do out there on the professional circuit . there are plenty of ways to get started djing . one of the main things i did was really take the time to study djs that inspired me . whether it was watching podcasts , watching live sets , or just really looking them up online . i really tried to take in what it meant to be a fantastic dj . one of the best ways to really learn is to ask a friend , you know , a friend who knows how to dj . just go over there , ask him a few questions . if no that , thankfully we have a lot of great online resources . one of the things you can do is check out youtube , check out some demonstrations . now , many djs , a high percentage of them , check out beatport or soundcloud to find a lot of the tracks . there are also many other blog sites , such as billboard 's code , edmtunes , edm sauce , or dancing astronaut . now , there are multiple ways to dj , and what could originally only be done on turntables and vinyl , by legends such as larry levan , grandmaster flash , and paul oakenfold , can now be done with many more pieces of equipment , such as cdjs , which are , sort of , digital turntables and what i learned on and what i still use to this day . there are many other amazing programs now , such as ableton , traktor pro , serato , or even apps for tablets and touchscreens . there are many hardware systems just like my apc40 here that can launch samples , clips and tracks . you can also just use turntables , cdjs , an s4 controller , or an novation launchpad . and all of these really kind of do the same thing , and that 's mix tracks . so , what i 'm going to do now is show you guys another mix demonstration . i 'm going to start with one of my own songs that i did with my friend matt dzyacky , and from there i 'm going to go in a sort of medley of different tracks and show you the different styles of mixing that you can do . ( music ) so i 'll show you guys when i start mixing the new track , so you can hear it coming in . ( music ) you can hear in the back , a new song is mixing in . ( music ) now , another thing that djs use is what 's called a mixer , and a mixer has many different effects , such as a beat roll , filter effects , and any other different ones . there 's plenty of effects to use . ( music ) so , now i 'm going into a new song , and after this drops , i 'm going to drop it in another song and kind of change it up . ( music ) and that 's a new song bite . ( music ) so i 'm just going to straight mash up another song right when this one breaks down . ( music ) now , if i want to change up the music , let 's say , throw in some new beats , i can just choose a trap beat i want to throw over the breakdown . ( music ) so , i get ready to throw in my new beats now . ( music ) and that is the end of that demo . ( applause ) thank you , thank you ! now , the great thing about technologies now is whether it 's a two dollar app or a couple hundred dollar equipment , which i 'm sure most parents wo n't want to buy for their child , is that almost anyone who has a passion for djing and a passion for the music and who might want to pursue a career in it really has the ability to , well , pursue it , such as myself . you can start with an app on a tablet or an app on your phone , even , an app on your ipad , and then move on to bigger equipment . the opportunities are endless , and , as you saw , you can mix many different styles of music . so , thank you !
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one of the main goals is to really trigger samples , tracks , or clips and kind of create this long journey . i 'm going to do another little example for you guys right now of what djs call a `` mashup , '' which is taking two or more tracks and combining them into one . this mashup was made famous by a hungarian duo myon & amp ; amp ; shane 54 , and it takes the vocals from krewella 's `` alive . '' how many of you guys know that song ?
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what is a mashup ?
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[ go project films ] i think that facing death changes people ... which is what happened with me . before this experience , i was a completely different person with a completely different dream . my last dream which was to treat cancer and right now my dream of changing the world in another way . [ welcome to canada ] [ over 4.8 million syrians are refugees living in neighboring countries . ] [ 6.5 million more are displaced within syria . ] [ in november 2015 , the government of canada promised ] [ to resettle 25,000 syrian refugees within 6 months . ] [ the 2400 court motel in vancouver is one of 9 temporary housing sites ] [ for the newly arrived refugees . ] [ may 2016 , vancouver , canada ] staying at the motel is this hard transitional stage . you are homesick and you 're also thinking about remaining family members overseas living under horrendous circumstances . i try my best to introduce the new reality . i try my best to ease the impact of their resettlement process as refugees , as someone who did n't choose to come here , as someone who had to come here . hi , my name is mohammed from immigrant services society of british columbia , iss of bc contacting you regarding your place on craigslist . [ tell me we have three children . ] you 're looking at the two bedroom or the three bedroom ? - two bedroom , two bedroom . - two bedroom ? okay . - oh , two bedroom ? - the two bedroom , yeah . how many people you have ? a family of five people with three small kids . - yeah , that too many . - that is too many ? [ she 's telling you that 's too many people . ] [ okay , tell her thank you ... they are young . ] thank you . i 'm with my clients right now . so i 'm helping him . he wants to share with you , the kids are so small and the ages are ... the place is too small for five people . oh , oh , i see . [ - she 's saying the house is too small to fit five people . ] [ - what about the 3 bedroom ... what 's the rental cost ? ] okay , what about the three bedroom that you have ? $ 3,500 a month . that will be expensive for a new immigrant family . is it possible for you to see the kids and ... i can not accommodate five people in that place . yeah , thank you so much . i 'm sorry . [ the two bedroom house , it 's too small to accommodate five people . ] [ the other house with 3 bedrooms , it 's too expensive , it 's $ 3,500 a month . ] moving to canada is not easy at all . my job is all about providing first language services [ oh my god . ] to the newly arrived refugees . [ we 're going to try and find you another house . ] i 'm the person who welcomes them and i will help them with everything that they will need in their resettlement process . it 's really hard to explain the reality on the ground in syria . it keeps on changing on a daily basis . syrians are just caught up in the middle of this non-sense chaos . many of them have spent many years in refugee camps in neighboring countries trying to just wait for this crazy war to finish . when they realized it 's going to be much longer , this syrian refugee crisis started . [ this is a transitional stage and it 's very difficult . ] [ i was just like you when i came here . ] [ the same reception center , same counselor ] [ and even signed the same papers . ] [ attended the same orientation , and was looking for a house . ] [ so you have been through this before . ] [ the exact same thing . ] [ -i would not encourage you to work right away ] [ -of course not , i need to learn the language first . ] [ excellent thinking . focus on english . ] [ your life starts tomorrow . ] [ god willing , we will start a new life tomorrow . ] before 2011 , before everything has started , we were living a happy life . i was born in al-hasakah , syria , a very peaceful city , a city of so many languages , ethnic components , and religious components with the idea and the notion of accepting others . i was in my fourth year of my medical studies in syria , i was trying my best to become a doctor , and my dream was to treat cancer . my generation was dreaming of having freedom , having some basic things that the average canadian would not think about . [ filmed by mohammed in homs , syria ] we never thought we could have faced such a brutal , barbaric response from your own government , just for gathering in the street and shouting the word `` freedom . '' we were just standing there and surprisingly they started shooting and people started falling ... at that point everyone started running , everyone who had survived it , started running , and some people were just on the ground covered with blood . i 'm calling you regarding clients of mine who are moving to your place tomorrow morning . [ -what 's happening in aleppo is breaking my heart . ] [ -a lot of problems are happening there . ] yeah , because we 're in the middle of , you know , arranging all the transportation needed for all of these families . all righty . thank you so much . [ this boy is dying . ] [ i want my brother . where is my mother and father ? ] [ where is my mom ? ] [ say , `` there is no god but god . '' ] for syrians , it is so normal to open your facebook and see the death of your friend on social media . it is something that is really hard and that is really difficult to accept , to observe , and to even think about . [ there is no power except what lies in god 's hands . ] i 'm about to turn 27 next month . in this small lifetime , i have been arrested three times . i have been in five different detention places . the first thing that they did in the detention center was hanging me from the ceiling . they had handcuffs on my hands like this and they had a chain coming down from the ceiling , and they have hooked that chain to my hands like this , and they kept me like this for three days . after spending three days like this , the actual torture started . they spent so many days practicing all kinds of torture on me , and on other syrian people , in that detention center . i can never forget this old man who was sleeping next to me ... he used to say , `` you see all of this ... one day , all of this will be just a story that you will be telling to other people . '' after 120 days of torture , i was finally released ... i was finally able to see sunlight again . the only thing that i wanted to do is talk to my family . i just wanted to see them but also say goodbye to them ... get the hell out of there and never look back . i took a taxi from damascus to beirut where there was no shelling , no explosions , just a normal life ... three hours away from where i was , from where i was tortured , it was unbelievable for me . iss of bc kingsway . good morning . syrians in lebanon are not allowed to work , are not allowed to go to school . syrians in lebanon are simply not welcomed . the best job that i could find was washing cars from 9 am to 9 pm for $ 20 a day . i was just struggling to have a life . my whole life changed with a single phone call . i pick up the phone , it was this same phone . so i pick up and i was told that , `` this is the canadian embassy calling for mohammed alsaleh , '' i was like , `` yes , speaking . '' so they told me , `` we have an application on your behalf to come to canada , are you interested ? '' and i was like , `` yes , i 'm . '' [ in november 2014 mohammed was granted asylum in canada and arrived in vancouver . ] [ to date thousands of syrian families have arrived in canada . ] each syrian family is thinking about someone who 's left behind ... if it was a brother , if it was a mother , or if it was a father . this is something that i can see among the people that i 'm helping , and this is something that i can relate to on a personal level because of the situation of my family . my family had to illegally cross the border between syria and turkey . they had to crawl in the mud in order to make it to safety . come on , pick up . [ hello . ] [ hello ... hello . ] [ hello , mama . ] [ how are you , mother ? ] [ i swear we miss you . we miss you so much . ] [ me too . i miss you so so much . ] [ shahad , what is this beautiful hair ? ] [ this is the new style , with these bangs . ] [ wow , look , look your hair is so long now . ] when i last saw my family , my youngest sister was seven , right now she is ten , and i do n't know how old would she be when i meet her . it 's really hard to know that you might not be able to meet them . [ look at how my hair looks . ] [ güzel ! güzel like the turkish say . ] [ are you learning turkish ? ] [ a little bit , not much yet . ] [ we try a little bit when we go out , things like that . ] [ -great . ] [ even though we are in turkey , the situation is tough here . ] [ we are always stressed and tired . life is hard here . ] [ what 's important is that you guys are safe and sound ] [ and you are not in danger , ] [ and we do n't have to worry about your life being in danger . ] [ and that 's the most important thing right now , ] [ to let these few months pass while everything is processed and you get here . ] [ god willing , because the situation here is n't comfortable and one does n't feel at home . ] [ -yes , yes . -you always feel like something is missing . ] [ god willing , we will all be together soon here in canada . ] [ that 's what we hope for . hopefully everything will work out . ] [ i miss you so so so much . ] in order for people to get settled and to feel like home , i think the only missing part is time . they just need time . [ speaking foreign language ] [ welcome , welcome to our new house . ] [ a hundred congratulations on the new house , it 's a lovely home . ] [ god bless you , it 's lovely having you all here . ] my first client was a family of 13 people who have just came to canada . [ the best thing you did was to get this property . ] [ here you can play , whatever you want is here . ] i was telling them , `` you 're safe now . one year ago , i was standing exactly where you are and right now i 'm helping you , so do n't worry everything 's going to be fine . '' i want everyone to realize how tremendous , how beautiful it is to offer people a place to call home ... which is something priceless that i really , really appreciate having right now . it 's heart breaking to see the country that you grew up in get destroyed . i 'm one of the ones lucky enough to come back from the dead , to tell their stories , to share their suffering with the rest of the world , which is something that i think is part of my obligation toward syrians and toward canadians . [ mohammed continues to support his family as he works to bring them safely to canada . ] [ according to the un , approximately 250,000 people ] [ have been killed in syria and 13.5 million people are in urgent need of humanitarian assistance . ] [ to date , 29,817 syrian refugees have been welcomed to canada . ] [ 2016 go project films ]
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[ welcome to canada ] [ over 4.8 million syrians are refugees living in neighboring countries . ] [ 6.5 million more are displaced within syria . ] [ in november 2015 , the government of canada promised ] [ to resettle 25,000 syrian refugees within 6 months . ]
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approximately how many syrians are displaced within syria ?
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we like to think of romantic feelings as spontaneous and indescribable things that come from the heart . but it 's actually your brain running a complex series of calculations within a matter of seconds that 's responsible for determining attraction . does n't sound quite as poetic , does it ? but just because the calculations are happening in your brain does n't mean those warm , fuzzy feelings are all in your head . in fact , all five of your senses play a role , each able to vote for , or veto , a budding attraction . the eyes are the first components in attraction . many visual beauty standards vary between cultures and eras , and signs of youth , fertility and good health , such as long lustrous hair , or smooth , scar-free skin , are almost always in demand because they 're associated with reproductive fitness . and when the eyes spot something they like , our instinct is to move closer so the other senses can investigate . the nose 's contribution to romance is more than noticing perfume or cologne . it 's able to pick up on natural chemical signals known as pheromones . these not only convey important physical or genetic information about their source but are able to activate a physiological or behavioral response in the recipient . in one study , a group of women at different points in their ovulation cycles wore the same t-shirts for three nights . after male volunteers were randomly assigned to smell either one of the worn shirts , or a new unworn one , saliva samples showed an increase in testosterone in those who had smelled a shirt worn by an ovulating woman . such a testosterone boost may give a man the nudge to pursue a woman he might not have otherwise noticed . a woman 's nose is particularly attuned to mhc molecules , which are used to fight disease . in this case , opposites attract . when a study asked women to smell t-shirts that had been worn by different men , they preferred the odors of those whose mhc molecules differed from theirs . this makes sense . genes that result in a greater variety of immunities may give offspring a major survival advantage . our ears also determine attraction . men prefer females with high-pitched , breathy voices , and wide formant spacing , correlated with smaller body size . while women prefer low-pitched voices with a narrow formant spacing that suggest a larger body size . and not surprisingly , touch turns out to be crucial for romance . in this experiment , not realizing the study had begun , participants were asked to briefly hold the coffee , either hot or iced . later , the participants read a story about a hypothetical person , and were asked to rate their personality . those who had held the hot cup of coffee perceived the person in the story as happier , more social , more generous and better-natured than those who had held the cup of iced coffee , who rated the person as cold , stoic , and unaffectionate . if a potential mate has managed to pass all these tests , there 's still one more : the infamous first kiss , a rich and complex exchange of tactile and chemical cues , such as the smell of one 's breath , and the taste of their mouth . this magical moment is so critical that a majority of men and women have reported losing their attraction to someone after a bad first kiss . once attraction is confirmed , your bloodstream is flooded with norepinephrine , activating your fight or flight system . your heart beats faster , your pupils dilate , and your body releases glucose for additional energy , not because you 're in danger but because your body is telling you that something important is happening . to help you focus , norepinephrine creates a sort of tunnel vision , blocking out surrounding distractions , possibly even warping your sense of time , and enhancing your memory . this might explain why people never forget their first kiss . the idea of so much of our attraction being influenced by chemicals and evolutionary biology may seem cold and scientific rather than romantic , but the next time you see someone you like , try to appreciate how your entire body is playing matchmaker to decide if that beautiful stranger is right for you .
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in one study , a group of women at different points in their ovulation cycles wore the same t-shirts for three nights . after male volunteers were randomly assigned to smell either one of the worn shirts , or a new unworn one , saliva samples showed an increase in testosterone in those who had smelled a shirt worn by an ovulating woman . such a testosterone boost may give a man the nudge to pursue a woman he might not have otherwise noticed .
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sometimes , a man ’ s testosterone increases when her smells a shirt worn my a _________women ?
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in many ways , our memories make us who we are , helping us remember our past , learn and retain skills , and plan for the future . and for the computers that often act as extensions of ourselves , memory plays much the same role , whether it 's a two-hour movie , a two-word text file , or the instructions for opening either , everything in a computer 's memory takes the form of basic units called bits , or binary digits . each of these is stored in a memory cell that can switch between two states for two possible values , 0 and 1 . files and programs consist of millions of these bits , all processed in the central processing unit , or cpu , that acts as the computer 's brain . and as the number of bits needing to be processed grows exponentially , computer designers face a constant struggle between size , cost , and speed . like us , computers have short-term memory for immediate tasks , and long-term memory for more permanent storage . when you run a program , your operating system allocates area within the short-term memory for performing those instructions . for example , when you press a key in a word processor , the cpu will access one of these locations to retrieve bits of data . it could also modify them , or create new ones . the time this takes is known as the memory 's latency . and because program instructions must be processed quickly and continuously , all locations within the short-term memory can be accessed in any order , hence the name random access memory . the most common type of ram is dynamic ram , or dram . there , each memory cell consists of a tiny transistor and a capacitor that store electrical charges , a 0 when there 's no charge , or a 1 when charged . such memory is called dynamic because it only holds charges briefly before they leak away , requiring periodic recharging to retain data . but even its low latency of 100 nanoseconds is too long for modern cpus , so there 's also a small , high-speed internal memory cache made from static ram . that 's usually made up of six interlocked transistors which do n't need refreshing . sram is the fastest memory in a computer system , but also the most expensive , and takes up three times more space than dram . but ram and cache can only hold data as long as they 're powered . for data to remain once the device is turned off , it must be transferred into a long-term storage device , which comes in three major types . in magnetic storage , which is the cheapest , data is stored as a magnetic pattern on a spinning disc coated with magnetic film . but because the disc must rotate to where the data is located in order to be read , the latency for such drives is 100,000 times slower than that of dram . on the other hand , optical-based storage like dvd and blu-ray also uses spinning discs , but with a reflective coating . bits are encoded as light and dark spots using a dye that can be read by a laser . while optical storage media are cheap and removable , they have even slower latencies than magnetic storage and lower capacity as well . finally , the newest and fastest types of long-term storage are solid-state drives , like flash sticks . these have no moving parts , instead using floating gate transistors that store bits by trapping or removing electrical charges within their specially designed internal structures . so how reliable are these billions of bits ? we tend to think of computer memory as stable and permanent , but it actually degrades fairly quickly . the heat generated from a device and its environment will eventually demagnetize hard drives , degrade the dye in optical media , and cause charge leakage in floating gates . solid-state drives also have an additional weakness . repeatedly writing to floating gate transistors corrodes them , eventually rendering them useless . with data on most current storage media having less than a ten-year life expectancy , scientists are working to exploit the physical properties of materials down to the quantum level in the hopes of making memory devices faster , smaller , and more durable . for now , immortality remains out of reach , for humans and computers alike .
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so how reliable are these billions of bits ? we tend to think of computer memory as stable and permanent , but it actually degrades fairly quickly . the heat generated from a device and its environment will eventually demagnetize hard drives , degrade the dye in optical media , and cause charge leakage in floating gates .
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an unopened photo is kept in the _____ of a computer .
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what is at the center of the universe ? it 's an essential question that humans have been wondering about for centuries . but the journey toward an answer has been a strange one . if you wanted to know the answer to this question in third century b.c.e . greece , you might look up at the night sky and trust what you see . that 's what aristotle , the guy to ask back then , did . he thought that since we 're on earth , looking up , it must be the center , right ? for him , the sphere of the world was made up of four elements : earth , water , air , and fire . these elements shifted around a nested set of solid crystalline spheres . each of the wandering stars , the planets , had their own crystal sphere . the rest of the universe and all of its stars were on the last crystal sphere . if you watch the sky change over time , you could see that this idea worked fine at explaining the motion you saw . for centuries , this was central to how europe and the islamic world saw the universe . but in 1543 , a guy named copernicus proposed a different model . he believed that the sun was at the center of the universe . this radically new idea was hard for a lot of people to accept . after all , aristotle 's ideas made sense with what they could see , and they were pretty flattering to humans . but a series of subsequent discoveries made the sun-centric model hard to ignore . first , johannes kepler pointed out that orbits are n't perfect circles or spheres . then , galileo 's telescope caught jupiter 's moons orbiting around jupiter , totally ignoring earth . and then , newton proposed the theory of universal gravitation , demonstrating that all objects are pulling on each other . eventually , we had to let go of the idea that we were at the center of the universe . shortly after copernicus , in the 1580s , an italian friar , giordano bruno , suggested the stars were suns that likely had their own planets and that the universe was infinite . this idea did n't go over well . bruno was burned at the stake for his radical suggestion . centuries later , the philosopher rene descartes proposed that the universe was a series of whirlpools , which he called vortices , and that each star was at the center of a whirlpool . in time , we realized there were far more stars than aristotle ever dreamed . as astronomers like william herschel got more and more advanced telescopes , it became clear that our sun is actually one of many stars inside the milky way . and those smudges we see in the night sky ? they 're other galaxies , just as vast as our milky way home . maybe we 're farther from the center than we ever realized . in the 1920s , astronomers studying the nebuli wanted to figure out how they were moving . based on the doppler effect , they expected to see blue shift for objects moving toward us , and red shift for ones moving away . but all they saw was a red shift . everything was moving away from us , fast . this observation is one of the pieces of evidence for what we now call the big bang theory . according to this theory , all matter in the universe was once a singular , infinitely dense particle . in a sense , our piece of the universe was once at the center . but this theory eliminates the whole idea of a center since there ca n't be a center to an infinite universe . the big bang was n't just an explosion in space ; it was an explosion of space . what each new discovery proves is that while our observations are limited , our ability to speculate and dream of what 's out there is n't . what we think we know today can change tomorrow . as with many of the thinkers we just met , sometimes our wildest guesses lead to wonderful and humbling answers and propel us toward even more perplexing questions .
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it 's an essential question that humans have been wondering about for centuries . but the journey toward an answer has been a strange one . if you wanted to know the answer to this question in third century b.c.e . greece , you might look up at the night sky and trust what you see .
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as demonstrated by the video , many people have been passionately involved in understanding what is at the center of the universe . do you think the answer to that question matters ? why should ( or shouldn ’ t ) we care about the answer ?
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translator : tom carter reviewer : bedirhan cinar ( stories from the sea : how life came to land ) life for my kind was n't always this way . there was a time when no animals lived on land . all life was in the ocean . the ocean 's where all of us animals got our start , more than half a billion years ago , this is where all animal body types -- or phyla , as scientists call them -- first evolved . you know , there are more than 30 animal phyla , but only a handful of major ones had what it took to do something completely daring : step out of the ocean , and on to dry land . so , which of these land-dwelling phyla first invaded the land ? was it me and my mollusc friends , with our amazing mantles and single foot ? perhaps the chordate crowd , with their notochords , segmented muscles and big bony skeletons . or maybe those lowly annelid worms , with their powerful ringed bodies . or did the arthropods first make landfall , with their little flexible suits of armor -- their exoskeleton ? ah , yes . the arthropods . from crustaceans to millipedes , spiders to insects , the arthropods outnumber all animals on land . so what 's their secret ? their exoskeleton is key , but here 's the real kicker : jointed appendages . they 're like little living swiss army knives : antennae , multiple mouth parts , an obscene number of legs , if you ask me . there 's one group of arthropods -- the insects -- that really rule the land . three body parts , six legs , and an annoying tendency to take over . sure , they have to molt to grow , but that does n't seem to pose a problem . the insects even invented the first wings , and conquered the skies . ah , well . so what if arthropods were the first to reach land and invent flight , a hundred million years before the rest of us ? so what if they pollinate crops around the world , and make up 75 % of all land animal species ? and that for every single human , there 's 200 million of them ? sure , those leggy arthropods may still be in the lead when it comes to conquering land , but we still rule in the sea . there are more species of molluscs in the ocean than any other animal phylum . we 're just getting started up here on land . besides , the seas are rising . just give us some time . who knows who 'll end up ruling this ocean planet ?
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ah , yes . the arthropods . from crustaceans to millipedes , spiders to insects , the arthropods outnumber all animals on land .
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what key feature ( s ) enabled arthropods to successfully establish life on dry land ?
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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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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 .
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why do you think the wasp goes through all the trouble to paralyze the cockroach ? would n't it just be easier to build a nest ?
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in a time-lapse video , it looks like a monster coming alive . for a moment , it sits there innocuously . then , ripples move across its surface . it bulges outwards , bursting with weird boils . it triples in volume . its color darkens ominously , and its surface hardens into an alien topography of peaks and craters . then , the kitchen timer dings . your cookie is ready . what happened inside that oven ? do n't let the apron deceive you ! bakers are mad scientists . when you slide the pan into the oven , you 're setting off a series of chemical reactions that transform one substance , dough , into another , cookies . when the dough reaches 92 degrees fahrenheit , the butter inside melts , causing the dough to start spreading out . butter is an emulsion , or mixture of two substances that do n't want to stay together , in this case , water and fat , along with some dairy solids that help hold them together . as the butter melts , its trapped water is released . and as the cookie gets hotter , the water expands into steam . it pushes against the dough from the inside , trying to escape through the cookie walls like ridley scott 's chest-bursting alien . your eggs may have been home to squirming salmonella bacteria . an estimated 142,000 americans are infected this way each year . though salmonella can live for weeks outside a living body and even survive freezing , 136 degrees is too hot for them . when your dough reaches that temperature , they die off . you 'll live to test your fate with a bite of raw dough you sneak from your next batch . at 144 degrees , changes begin in the proteins , which come mostly from the eggs in your dough . eggs are composed of dozens of different kinds of proteins , each sensitive to a different temperature . in an egg fresh from the hen , these proteins look like coiled up balls of string . when they 're exposed to heat energy , the protein strings unfold and get tangled up with their neighbors . this linked structure makes the runny egg nearly solid , giving substance to squishy dough . water boils away at 212 degrees , so like mud baking in the sun , your cookie gets dried out and it stiffens . cracks spread across its surface . the steam that was bubbling inside evaporates , leaving behind airy pockets that make the cookie light and flaky . helping this along is your leavening agent , sodium bicarbonate , or baking soda . the sodium bicarbonate reacts with acids in the dough to create carbon dioxide gas , which makes airy pockets in your cookie . now , it 's nearly ready for a refreshing dunk in a cool glass of milk . one of science 's tastiest reactions occurs at 310 degrees . this is the temperature for maillard reactions . maillard reactions result when proteins and sugars break down and rearrange themselves , forming ring-like structures , which reflect light in a way that gives foods like thanksgiving turkey and hamburgers their distinctive , rich brown color . as this reaction occurs , it produces a range of flavor and aroma compounds , which also react with each other , forming even more complex tastes and smells . caramelization is the last reaction to take place inside your cookie . caramelization is what happens when sugar molecules break down under high heat , forming the sweet , nutty , and slightly bitter flavor compounds that define , well , caramel . and , in fact , if your recipe calls for a 350 degree oven , it 'll never happen , since caramelization starts at 356 degrees . if your ideal cookie is barely browned , like a northeasterner on a beach vacation , you could have set your oven to 310 degrees . if you like your cookies to have a nice tan , crank up the heat . caramelization continues up to 390 degrees . and here 's another trick : you do n't need that kitchen timer ; your nose is a sensitive scientific instrument . when you smell the nutty , toasty aromas of the maillard reaction and caramelization , your cookies are ready . grab your glass of milk , put your feet up , and reflect that science can be pretty sweet .
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then , the kitchen timer dings . your cookie is ready . what happened inside that oven ?
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how would adding or removing ingredients change your final cookie ?
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tattoos have often been presented in popular media as either marks of the dangerous and deviant or trendy youth fads . but while tattoo styles come and go , and their meaning has differed greatly across cultures , the practice is as old as civilization itself . decorative skin markings have been discovered in human remains all over the world , with the oldest found on a peruvian mummy dating back to 6,000 bce . but have you ever wondered how tattooing really works ? you may know that we shed our skin , losing about 30-40,000 skin cells per hour . that 's about 1,000,000 per day . so , how come the tattoo does n't gradually flake off along with them ? the simple answer is that tattooing involves getting pigment deeper into the skin than the outermost layer that gets shed . throughout history , different cultures have used various methods to accomplish this . but the first modern tattooing machine was modeled after thomas edison 's engraving machine and ran on electricity . tattooing machines used today insert tiny needles , loaded with dye , into the skin at a frequency of 50 to 3,000 times per minute . the needles punch through the epidermis , allowing ink to seep deep into the dermis , which is composed of collagen fibers , nerves , glands , blood vessels and more . every time a needle penetrates , it causes a wound that alerts the body to begin the inflammatory process , calling immune system cells to the wound site to begin repairing the skin . and it is this very process that makes tattoos permanent . first , specialized cells called macrophages eat the invading material in an attempt to clean up the inflammatory mess . as these cells travel through the lymphatic system , some of them are carried back with a belly full of dye into the lymph nodes while others remain in the dermis . with no way to dispose of the pigment , the dyes inside them remain visible through the skin . some of the ink particles are also suspended in the gel-like matrix of the dermis , while others are engulfed by dermal cells called fibroblasts . initially , ink is deposited into the epidermis as well , but as the skin heals , the damaged epidermal cells are shed and replaced by new , dye-free cells with the topmost layer peeling off like a heeling sunburn . blistering or crusting is not typically seen with professional tattoos and complete epidermal regeneration requires 2-4 weeks , during which excess sun exposure and swimming should be avoided to prevent fading . dermal cells , however , remain in place until they die . when they do , they are taken up , ink and all , by younger cells nearby , so the ink stays where it is . but with time , tattoos do fade naturally as the body reacts to the alien pigment particles , slowly breaking them down to be carried off by the immune system 's macrophages . ultraviolet radiation can also contribute to this pigment breakdown , though it can be mitigated by the use of sunblock . but since the dermal cells are relatively stable , much of the ink will remain deep in the skin for a person 's whole life . but if tattoos are embedded in your skin for life , is there any way to erase them ? technically , yes . today , a laser is used to penetrate the epidermis and blast apart underlying pigment colors of various wavelengths , black being the easiest to target . the laser beam breaks the ink globules into smaller particles that can then be cleared away by the macrophages . but some color inks are harder to remove than others , and there could be complications . for this reason , removing a tattoo is still more difficult than getting one , but not impossible . so a single tattoo may not truly last forever , but tattoos have been around longer than any existing culture . and their continuing popularity means that the art of tattooing is here to stay .
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so , how come the tattoo does n't gradually flake off along with them ? the simple answer is that tattooing involves getting pigment deeper into the skin than the outermost layer that gets shed . throughout history , different cultures have used various methods to accomplish this .
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what is the outermost skin layer called ?
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shall i ask for a show of hands or a clapping of people in different generations ? i 'm interested in how many are three to 12 years old . ( laughter ) none , huh ? ( laughter ) all right . i 'm going to talk about dinosaurs . do you remember dinosaurs when you were that age ? ( applause ) dinosaurs are kind of funny , you know . ( laughter ) we 're going to kind of go in a different direction right now . i hope you all realize that . so i 'll just give you my message up front : try not to go extinct . ( laughter ) that 's it . ( laughter ) people ask me a lot -- in fact , one of the most asked questions i get is , why do children like dinosaurs so much ? what 's the fascination ? and i usually just say , `` well , dinosaurs were big , different and gone . '' they 're all gone . well that 's not true , but we 'll get to the goose in a minute . so that 's sort of the theme : big , different and gone . the title of my talk : shape-shifting dinosaurs : the cause of a premature extinction . now i assume that we remember dinosaurs . and there 's lots of different shapes . lots of different kinds . a long time ago , back in the early 1900s , museums were out looking for dinosaurs . they went out and gathered them up . and this is an interesting story . every museum wanted a little bigger or better one than anybody else had . so if the museum in toronto went out and collected a tyrannosaur , a big one , then the museum in ottawa wanted a bigger one , and a better one . and that happened for all museums . so everyone was out looking for all these bigger and better dinosaurs . and this was in the early 1900s . by about 1970 , some scientists were sitting around and they thought , `` what in the world -- look at these dinosaurs , they 're all big . where are all the little ones ? '' ( laughter ) and they thought about it and they even wrote papers about it : `` where are the little dinosaurs ? '' ( laughter ) well , go to a museum , you 'll see , see how many baby dinosaurs there are . people assumed -- and this was actually a problem -- people assumed that if they had little dinosaurs , if they had juvenile dinosaurs , they 'd be easy to identify . you 'd have a big dinosaur and a littler dinosaur . ( laughter ) but all they had were big dinosaurs . and it comes down to a couple of things . first off , scientists have egos , and scientists like to name dinosaurs . they like to name anything . everybody likes to have their own animal that they named . ( laughter ) and so every time they found something that looked a little different , they named it something different . and what happened , of course , is we ended up with a whole bunch of different dinosaurs . in 1975 , a light went on in somebody 's head . dr. peter dodson at the university of pennsylvania actually realized that dinosaurs grew kind of like birds do , which is different than the way reptiles grow . and in fact , he used the cassowary as an example . and it 's kind of cool -- if you look at the cassowary , or any of the birds that have crests on their heads , they grow to about 80 percent adult size before the crest starts to grow . now think about that . they 're basically retaining their juvenile characteristics very late in what we call ontogeny . so allometric cranial ontogeny is relative skull growth . so you can see that if you actually found one that was 80 percent grown and you did n't know that it was going to grow up to a cassowary , you would think they were two different animals . so this was a problem , and peter dodson pointed this out using some duck-billed dinosaurs then called hypacrosaurus . and he showed that if you were to take a baby and an adult and make an average of what it should look like , if it grew in sort of a linear fashion , it would have a crest about half the size of the adult . but the actual subadult at 65 percent had no crest at all . so this was interesting . so this is where people went astray again . i mean , if they 'd have just taken that , taken peter dodson 's work , and gone on with that , then we would have a lot less dinosaurs than we have . but scientists have egos ; they like to name things . and so they went on naming dinosaurs because they were different . now we have a way of actually testing to see whether a dinosaur , or any animal , is a young one or an older one . and that 's by actually cutting into their bones . but cutting into the bones of a dinosaur is hard to do , as you can imagine , because in museums , bones are precious . you go into a museum , and they take really good care of them . they put them in foam , little containers . they 're very well taken care of . they do n't like it if you come in and want to saw them open and look inside . ( laughter ) so they do n't normally let you do that . ( laughter ) but i have a museum and i collect dinosaurs and i can saw mine open . so that 's what i do . ( applause ) so if you cut open a little dinosaur , it 's very spongy inside , like a . and if you cut into an older dinosaur , it 's very massive . you can tell it 's mature bone . so it 's real easy to tell them apart . so what i want to do is show you these . in north america in the northern plains of the united states and the southern plains of alberta and saskatchewan , there 's this unit of rock called the hell creek formation that produces the last dinosaurs that lived on earth . and there are 12 of them that everyone recognizes -- i mean the 12 primary dinosaurs that went extinct . and so we will evaluate them . and that 's sort of what i 've been doing . so my students , my staff , we 've been cutting them open . now as you can imagine , cutting open a leg bone is one thing , but when you go to a museum and say , `` you do n't mind if i cut open your dinosaur 's skull , do you ? '' they say , `` go away . '' ( laughter ) so here are 12 dinosaurs . and we want to look at these three first . so these are dinosaurs that are called pachycephalosaurus . and everybody knows that these three animals are related . and the assumption is that they 're related like cousins or whatever . but no one ever considered that they might be more closely related . in other words , people looked at them and they saw the differences . and you all know that if you are going to determine whether you 're related to your brother or your sister , you ca n't do it by looking at differences . you can only determine relatedness by looking for similarities . so people were looking at these and they were talking about how different they are . pachycephalosaurus has a big , thick dome on its head , and it 's got some little bumps on the back of its head , and it 's got a bunch of gnarly things on the end of its nose . and then stygimoloch , another dinosaur from the same age , lived at the same time , has spikes sticking out the back of its head . it 's got a little , tiny dome , and it 's got a bunch of gnarly stuff on its nose . and then there 's this thing called dracorex hogwartsia . guess where that came from ? dragon . so here 's a dinosaur that has spikes sticking out of its head , no dome and gnarly stuff on its nose . nobody noticed the gnarly stuff sort of looked alike . but they did look at these three and they said , `` these are three different dinosaurs , and dracorex is probably the most primitive of them . and the other one is more primitive than the other . '' it 's unclear to me how they actually sorted these three of them out . but if you line them up , if you just take those three skulls and just line them up , they line up like this . dracorex is the littlest one , stygimoloch is the middle-size one , pachycephalosaurus is the largest one . and one would think , that should give me a clue . ( laughter ) but it did n't give them a clue . ( laughter ) because , well we know why . scientists like to name things . so if we cut open dracorex -- i cut open our dracorex -- and look , it was spongy inside , really spongy inside . i mean , it is a juvenile and it 's growing really fast . so it is going to get bigger . if you cut open stygimoloch , it is doing the same thing . the dome , that little dome , is growing really fast . it 's inflating very fast . what 's interesting is the spike on the back of the dracorex was growing very fast as well . the spikes on the back of the stygimoloch are actually resorbing , which means they 're getting smaller as that dome is getting bigger . and if we look at pachycephalosaurus , pachycephalosaurus has a solid dome and its little bumps on the back of its head were also resorbing . so just with these three dinosaurs , as a scientist , we can easily hypothesize that it is just a growth series of the same animal . which of course means that stygimoloch and dracorex are extinct . ( laughter ) ok. ( laughter ) which of course means we have 10 primary dinosaurs to deal with . so a colleague of mine at berkeley -- he and i were looking at triceratops . and before the year 2000 -- now remember , triceratops was first found in the 1800s -- before 2000 , no one had ever seen a juvenile triceratops . there 's a triceratops in every museum in the world , but no one had ever collected a juvenile . and we know why , right ? because everybody wants to have a big one . so everyone had a big one . so we went out and collected a whole bunch of stuff and we found a whole bunch of little ones . they 're everywhere , they 're all over the place . so we have a whole bunch of them at our museum . ( laughter ) and everybody says it 's because i have a little museum . when you have a little museum , you have little dinosaurs . ( laughter ) if you look at the triceratops , you can see it 's changing , it 's shape-shifting . as the juveniles are growing up , their horns actually curve backwards . and then as they get older , the horns grow forward . and that 's pretty cool . if you look along the edge of the frill , they have these little triangular bones that actually grow big as triangles and then they flatten against the frill pretty much like the spikes do on the pachycephalosaurs . and then , because the juveniles are in my collection , i cut them open ... ( laughter ) and look inside . and the little one is really spongy . and the middle-size one is really spongy . but what was interesting was the adult triceratops was also spongy . and this is a skull that is two meters long . it 's a big skull . but there 's another dinosaur that is found in this formation that looks like a triceratops , except it 's bigger , and it 's called torosaurus . and torosaurus , when we cut into it , has mature bone . but it 's got these big holes in its shield . and everybody says , `` a triceratops and a torosaurus ca n't possibly be the same animal because one of them 's bigger than the other one . '' ( laughter ) `` and it has holes in its frill . '' and i said , `` well do we have any juvenile torosauruses ? '' and they said , `` well , no , but it has holes in its frill . '' so one of my graduate students , john scannella , looked through our whole collection and he actually discovered that the hole starting to form in triceratops and , of course it 's open , in torosaurus -- so he found the transitional ones between triceratops and torosaurus , which was pretty cool . so now we know that torosaurus is actually a grown-up triceratops . now when we name dinosaurs , when we name anything , the original name gets to stick and the second name is thrown out . so torosaurus is extinct . triceratops , if you 've heard the news , a lot of the newscasters got it all wrong . they thought torosaurus should be kept and triceratops thrown out , but that 's not going to happen . ( laughter ) all right , so we can do this with a bunch of dinosaurs . i mean , here 's edmontosaurus and anatotitan . anatotitan : giant duck . it 's a giant duck-bill dinosaur . here 's another one . so we look at the bone histology . the bone histology tells us that edmontosaurus is a juvenile , or at least a subadult , and the other one is an adult , and we have an ontogeny . and we get rid of anatotitan . so we can just keep doing this . and the last one is t. rex . so there 's these two dinosaurs , t. rex and nanotyrannus . ( laughter ) again , it makes you wonder . ( laughter ) but they had a good question . they were looking at them and they said , `` one 's got 17 teeth , and the biggest one 's got 12 teeth . and that does n't make any sense at all , because we do n't know of any dinosaurs that gain teeth as they get older . so it must be true -- they must be different . '' so we cut into them . and sure enough , nanotyrannus has juvenile bone and the bigger one has more mature bone . it looks like it could still get bigger . and at the museum of the rockies where we work , i have four t. rexes , so i can cut a whole bunch of them . but i did n't have to cut any of them really , because i just lined up their jaws and it turned out the biggest one had 12 teeth and the next smallest one had 13 and the next smallest had 14 . and of course , nano has 17 . and we just went out and looked at other people 's collections and we found one that has sort of 15 teeth . so again , real easy to say that tyrannosaurus ontogeny included nanotyrannus , and therefore we can take out another dinosaur . ( laughter ) so when it comes down to our end cretaceous , we have seven left . and that 's a good number . that 's a good number to go extinct , i think . now as you can imagine , this is not very popular with fourth-graders . ( laughter ) fourth-graders love their dinosaurs , they memorize them . and they 're not happy with this . ( laughter ) thank you very much . ( applause )
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people assumed -- and this was actually a problem -- people assumed that if they had little dinosaurs , if they had juvenile dinosaurs , they 'd be easy to identify . you 'd have a big dinosaur and a littler dinosaur . ( laughter ) but all they had were big dinosaurs .
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how is the inside of an adult dinosaur ’ s bone different from that of a baby dinosaur ?
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translator : andrea mcdonough reviewer : bedirhan cinar what do harry potter , katniss everdeen , and frodo all have in common with the heroes of ancient myths ? ( roar ) what if i told you they are all variants of the same hero ? do you believe that ? joseph campbell did . he studied myths from all over the world and published a book called `` the hero with a thousand faces , '' retelling dozens of stories and explaining how each represents the mono-myth , or hero 's journey . so , what is the `` hero 's journey '' ? think of it as a cycle . the journey begins and ends in a hero 's ordinary world , but the quest passes through an unfamiliar , special world . along the way , there are some key events . think about your favorite book or movie . does it follow this pattern ? status quo , that 's where we start . 1:00 : call to adventure . the hero receives a mysterious message . an invitation , a challenge ? 2:00 : assistance the hero needs some help , probably from someone older , wiser . 3:00 : departure the hero crosses the threshold from his normal , safe home , and enters the special world and adventure . we 're not in kansas anymore . 4:00 : trials being a hero is hard work : our hero solves a riddle , slays a monster , escapes from a trap . 5:00 : approach it 's time to face the biggest ordeal , the hero 's worst fear . ( roar ) 6:00 : crisis this is the hero 's darkest hour . he faces death and possibly even dies , only to be reborn . 7:00 : treasure ( roar ) as a result , the hero claims some treasure , special recognition , or power . 8:00 : result this can vary between stories . do the monsters bow down before the hero , or do they chase him as he flees from the special world ? 9:00 : return after all that adventure , the hero returns to his ordinary world . 10:00 : new life this quest has changed the hero ; he has outgrown his old life . 11:00 : resolution all the tangled plot lines get straightened out . 12:00 : status quo , but upgraded to a new level . nothing is quite the same once you are a hero . many popular books and movies follow this ancient formula pretty closely . but let 's see how well `` the hunger games '' fits the hero 's journey template . when does katniss everdeen hear her call to adventure that gets the story moving ? when her sister 's name is called from the lottery . how about assistance ? is anyone going to help her on her adventure ? haymitch . what about departure ? does she leave her ordinary world ? she gets on a train to the capital . ok , so you get the idea . what do you have in common with harry potter , katniss everdeen , and frodo ? well , you 're human , just like them . the hero 's journey myth exists in all human cultures and keeps getting updated , because we humans reflect on our world through symbolic stories of our own lives . you leave your comfort zone , have an experience that transforms you , and then you recover and do it again . you do n't literally slay dragons or fight voldemort , but you face problems just as scary . joseph campbell said , `` in the cave you fear to enter lies the treasure you seek . '' what is the symbolic cave you fear to enter ? auditions for the school play ? baseball tryouts ? love ? watch for this formula in books , movies , and tv shows you come across . you will certainly see it again . but also be sensitive to it in your own life . listen for your call to adventure . accept the challenge . conquer your fear and claim the treasure you seek . and then , do it all over again .
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he studied myths from all over the world and published a book called `` the hero with a thousand faces , '' retelling dozens of stories and explaining how each represents the mono-myth , or hero 's journey . so , what is the `` hero 's journey '' ? think of it as a cycle .
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according to the hero ’ s journey paradigm , the treasure you seek lies…
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cell membranes are structures of contradictions . these oily films are hundreds of times thinner than a strand of spider silk , yet strong enough to protect the delicate contents of life : the cell 's watery cytoplasm , genetic material , organelles , and all the molecules it needs to survive . how does the membrane work , and where does that strength come from ? first of all , it 's tempting to think of a cell membrane like the tight skin of a balloon , but it 's actually something much more complex . in reality , it 's constantly in flux , shifting components back and forth to help the cell take in food , remove waste , let specific molecules in and out , communicate with other cells , gather information about the environment , and repair itself . the cell membrane gets this resilience , flexibility , and functionality by combining a variety of floating components in what biologists call a fluid mosaic . the primary component of the fluid mosaic is a simple molecule called a phospholipid . a phospholipid has a polar , electrically-charged head , which attracts water , and a non-polar tail , which repels it . they pair up tail-to-tail in a two layer sheet just five to ten nanometers thick that extends all around the cell . the heads point in towards the cytoplasm and out towards the watery fluid external to the cell with the lipid tails sandwiched in between . this bilayer , which at body temperature has the consistency of vegetable oil , is studded with other types of molecules , including proteins , carbohydrates , and cholesterol . cholesterol keeps the membrane at the right fluidity . it also helps regulate communication between cells . sometimes , cells talk to each other by releasing and capturing chemicals and proteins . the release of proteins is easy , but the capture of them is more complicated . that happens through a process called endocytosis in which sections of the membrane engulf substances and transport them into the cell as vesicles . once the contents have been released , the vesicles are recycled and returned to the cell membrane . the most complex components of the fluid mosaic are proteins . one of their key jobs is to make sure that the right molecules get in and out of the cell . non-polar molecules , like oxygen , carbon dioxide , and certain vitamins can cross the phospholipid bilayer easily . but polar and charged molecules ca n't make it through the fatty inner layer . transmembrane proteins stretch across the bilayer to create channels that allow specific molecules through , like sodium and potassium ions . peripheral proteins floating in the inner face of the bilayer help anchor the membrane to the cell 's interior scaffolding . other proteins in cell membranes can help fuse two different bilayers . that can work to our benefit , like when a sperm fertilizes an egg , but also harm us , as it does when a virus enters a cell . and some proteins move within the fluid mosaic , coming together to form complexes that carry out specific jobs . for instance , one complex might activate cells in our immune system , then move apart when the job is done . cell membranes are also the site of an ongoing war between us and all the things that want to infect us . in fact , some of the most toxic substances we know of are membrane-breaching proteins made by infectious bacteria . these pore-forming toxins poke giant holes in our cell membranes , causing a cell 's contents to leak out . scientists are working on developing ways to defend against them , like using a nano-sponge that saves our cells by soaking up the membrane-damaging toxins . the fluid mosaic is what makes all the functions of life possible . without a cell membrane , there could be no cells , and without cells , there would be no bacteria , no parasites , no fungi , no animals , and no us .
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cell membranes are also the site of an ongoing war between us and all the things that want to infect us . in fact , some of the most toxic substances we know of are membrane-breaching proteins made by infectious bacteria . these pore-forming toxins poke giant holes in our cell membranes , causing a cell 's contents to leak out . scientists are working on developing ways to defend against them , like using a nano-sponge that saves our cells by soaking up the membrane-damaging toxins .
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a ________ protein is fully on one side or the other of the cell membrane .
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this is a crystal of sugar . if you press on it , it will actually generate its own electricity . how can this simple crystal act like a tiny power source ? because sugar is piezoelectric . piezoelectric materials turn mechanical stress , like pressure , sound waves , and other vibrations into electricity and vice versa . this odd phenomenon was first discovered by the physicist pierre curie and his brother jacques in 1880 . they discovered that if they compressed thin slices of certain crystals , positive and negative charges would appear on opposite faces . this difference in charge , or voltage , meant that the compressed crystal could drive current through a circuit , like a battery . and it worked the other way around , too . running electricity through these crystals made them change shape . both of these results , turning mechanical energy into electrical , and electrical energy into mechanical , were remarkable . but the discovery went uncelebrated for several decades . the first practical application was in sonar instruments used to detect german submarines during world war i. piezoelectric quartz crystals in the sonar 's transmitter vibrated when they were subjected to alternating voltage . that sent ultrasound waves through the water . measuring how long it took these waves to bounce back from an object revealed how far away it was . for the opposite transformation , converting mechanical energy to electrical , consider the lights that turn on when you clap . clapping your hands send sound vibrations through the air and causes the piezo element to bend back and forth . this creates a voltage that can drive enough current to light up the leds , though it 's conventional sources of electricity that keep them on . so what makes a material piezoelectric ? the answer depends on two factors : the materials atomic structure , and how electric charge is distributed within it . many materials are crystalline , meaning they 're made of atoms or ions arranged in an orderly three-dimensional pattern . that pattern has a building block called a unit cell that repeats over and over . in most non-piezoelectric crystalline materials , the atoms in their unit cells are distributed symmetrically around a central point . but some crystalline materials do n't possess a center of symmetry making them candidates for piezoelectricity . let 's look at quartz , a piezoelectric material made of silicon and oxygen . the oxygens have a slight negative charge and silicons have a slight positive , creating a separation of charge , or a dipole along each bond . normally , these dipoles cancel each other out , so there 's no net separation of charge in the unit cell . but if a quartz crystal is squeezed along a certain direction , the atoms shift . because of the resulting asymmetry in charge distribution , the dipoles no longer cancel each other out . the stretched cell ends up with a net negative charge on one side and a net positive on the other . this charge imbalance is repeated all the way through the material , and opposite charges collect on opposite faces of the crystal . this results in a voltage that can drive electricity through a circuit . piezoelectric materials can have different structures . but what they all have in common is unit cells which lack a center of symmetry . and the stronger the compression on piezoelectric materials , the larger the voltage generated . stretch the crystal , instead , and the voltage will switch , making current flow the other way . more materials are piezoelectric than you might think . dna , bone , and silk all have this ability to turn mechanical energy into electrical . scientists have created a variety of synthetic piezoelectric materials and found applications for them in everything from medical imaging to ink jet printers . piezoelectricity is responsible for the rhythmic oscillations of the quartz crystals that keep watches running on time , the speakers of musical birthday cards , and the spark that ignites the gas in some barbecue grill lighters when you flick the switch . and piezoelectric devices may become even more common since electricity is in high demand and mechanical energy is abundant . there are already train stations that use passengers ' footsteps to power the ticket gates and displays and a dance club where piezoelectricity helps power the lights . could basketball players running back and forth power the scoreboard ? or might walking down the street charge your electronic devices ? what 's next for piezoelectricity ?
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running electricity through these crystals made them change shape . both of these results , turning mechanical energy into electrical , and electrical energy into mechanical , were remarkable . but the discovery went uncelebrated for several decades .
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in which of the following applications does the piezo element convert mechanical energy into electrical energy ?
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all the material objects around you are composed of submicroscopic units we call molecules . and molecules in turn are composed of individual atoms . molecules frequently break apart and then form new molecules . on the other hand , virtually all the atoms you come in to contact with through the course of your life , the ones in the ground beneath you , the air you breath , the food you eat , those that make up every living thing , including you , have existed for billions of years and were created in places very unlike our planet . how those atoms came about is what i want to share with you . it all started 14 billion years ago with an event we call the big bang , which resulted in a universe consisting of gas alone . there were no stars and no planets . the gas was made up only of atoms belonging to the simplest elements . it was about 75 percent hydrogen and almost all the rest was helium . no elements like carbon , oxygen or nitrogen existed . no iron , silver or gold . in some places , the density of this gas was slightly higher than in others . due to gravity , those places attracted even more gas , which further strengthened the pull of gravity , which then drew more gas in , and so on . eventually , large dense gas balls formed , shrinking under their own gravity and consequently heating up on the inside . at some point , the core of such a ball gets hot enough that nuclear fusion occurs . hydrogen atoms smash together to form helium , accompanied by a great release of energy , strong enough to counteract the shrinking force of the gravity . when the energy pushing out from the fusion reactions matches the gravity pulling all the gas inwards , an equilibrium occurs . from this a star is born . over its lifetime , the fusion reactions in the core of a massive star will produce not only helium , but also carbon , oxygen , nitrogen and all the other elements in the periodic table up to iron . but eventually , the core 's fuel runs out , leaving it to collapse completely . that causes an unbelievably powerful explosion we call a supernova . now there are two things to note about how supernovas create elements . first , this explosion releases so much energy that fusion goes wild forming elements with atoms even heavier than iron like silver , gold and uranium . second , all the elements that had been accumulating in the core of the star , like carbon , oxygen , nitrogen , iron , as well as all of those formed in the supernova explosion , are ejected in to interstellar space where they mix with the gas that 's already there . history then repeats itself . gas clouds , now containing many elements besides the original hydrogen and helium , have higher density areas that attract more matter , and so on . as before , new stars result . our sun was born this way about 5 billion years ago . that means that the gas it arose from had itself been enriched with many elements from supernova explosions since the universe began . so that 's how the sun wound up with all the elements . it 's still mostly hydrogen at 71 percent , with most of the rest being helium at 27 percent . but bear in mind that while the first stars were made up of hydrogen and helium alone , the remaining elements in the periodic table make up two percent of the sun . and what about earth ? planets form as an incidental process to star formation out of the same gas cloud as the star itself . small planets like ours do n't have enough gravity to hold on to much hydrogen or helium gas since both of those are very light . so , even though carbon , nitrogen , oxygen and so on made up only two percent of the gas cloud from which earth was formed , these heavier elements form the bulk of our planet and everything on it . think about this : with the exception of hydrogen and some helium , the ground you walk on , the air you breath , you , everything is made of atoms that were created inside stars . when scientists first worked this out over the first half of the 20th century , the famous astronomer harlow shapley commented , `` we are brothers of the boulders , cousins of the clouds . ''
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gas clouds , now containing many elements besides the original hydrogen and helium , have higher density areas that attract more matter , and so on . as before , new stars result . our sun was born this way about 5 billion years ago .
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stars form ________ .
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so this sample , it ’ s a very , very interesting sample ; it ’ s arsenic . so this is quality arsenic . so arsenic used to much more common in the community than it is nowadays . it was used as a pigment in the nineteenth century for green wallpaper contained copper arsenite , because there weren ’ t any other good green pigments to make the wallpaper . and when the rooms were damp , victorians didn ’ t like opening the windows in their rooms , then mould would grow on the wall . and because arsenic is poisonous to most life forms the mould would convert the arsenic into a volatile compound , trimethylarsine , and the trimethylarsine went into the air and several people were killed by the arsenic coming from their wall paper . now arsenic as we know is very toxic and there have been a number of very high profile and very famous cases of people that have poisoned perhaps their partners or their business partners using arsenic . okay , so i ’ m going to very carefully take this vial out . he says very carefully then knocks it really hard . arsenic was also used quite widely by people to dispose of husbands , wives , lovers . though now it is much less common . it is used in the electronics industry for getting electronic properties for making transistors . and also it is still sometimes used for medication for feeding to livestock . it is only quite recently that the use of arsenic has been banned as an additive to chicken feed in the united states . so here you see the arsenic powder okay . now this is a metallic very dark metal , but i ’ m not going to open this because like i said it ’ s very , very toxic . it ’ s a very dark metallic sample , you can see a very fine powder in the bottom of this vial . now i ’ m going to put this back in before i get any on my skin because it ’ s a very toxic material and i don ’ t want to expose myself .
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and when the rooms were damp , victorians didn ’ t like opening the windows in their rooms , then mould would grow on the wall . and because arsenic is poisonous to most life forms the mould would convert the arsenic into a volatile compound , trimethylarsine , and the trimethylarsine went into the air and several people were killed by the arsenic coming from their wall paper . now arsenic as we know is very toxic and there have been a number of very high profile and very famous cases of people that have poisoned perhaps their partners or their business partners using arsenic .
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people in the 19th century were sometimes killed by a volatile compound of arsenic . it was a product of the metabolism of the mold in the wallpapers painted with paris green . what is this poisonous compound ?
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if you 've watched the news or followed politics chances are you 've heard the term orwellian thrown around in one context or another . but have you ever stopped to think about what it really means , or why it 's used so often ? the term was named after british author eric blair known by his pen name george orwell . because his most famous work , the novel `` 1984 , '' depicts an oppressive society under a totalitarian government , `` orwellian '' is often used simply to mean authoritarian . but using the term in this way not only fails to fully convey orwell 's message , it actually risks doing precisely what he tried to warn against . orwell was indeed opposed to all forms of tyranny , spending much of his life fighting against anti-democratic forces of both the left-wing and the right . but he was also deeply concerned with how such ideologies proliferate . and one of his most profound insights was the importance that language plays in shaping our thoughts and opinions . the government of `` 1984 '' 's oceania controls its people 's actions and speech in some ways that are obvious . their every move and word is watched and heard , and the threat of what happens to those who step out of line is always looming overhead . other forms of control are not so obvious . the population is inundated with a constant barrage of propaganda made up of historical facts and statistics manufactured in the ministry of truth . the ministry of peace is the military . labor camps are called `` joycamps . '' political prisoners are detained and tortured in the ministry of love . this deliberate irony is an example of doublespeak , when words are used not to convey meaning but to undermine it , corrupting the very ideas they refer to . the regime 's control of language goes even further , eliminating words from the english language to create the official dialect of newspeak , a crudely limited collection of acronyms and simple concrete nouns lacking any words complex enough to encourage nuanced or critical thought . this has an effect on the psyche orwell calls , `` doublethink , '' a hypnotic state of cognitive dissonance in which one is compelled to disregard their own perception in place of the officially dictated version of events , leaving the individual completely dependent on the state 's definition of reality itself . the result is a world in which even the privacy of one 's own thought process is violated , where one may be found guilty of thoughtcrime by talking in their sleep , and keeping a diary or having a love affair equals a subversive act of rebellion . this might sound like something that can only happen in totalitarian regimes , but orwell was warning us about the potential for this occurring even in democratic societies . and this is why `` authoritarian '' alone does not `` orwellian '' make . in his essay , `` politics and the english language , '' he described techniques like using pretentious words to project authority , or making atrocities sound acceptable by burying them in euphemisms and convoluted sentence structures . but even more mundane abuses of language can affect the way we think about things . the words you see and hear in everyday advertising have been crafted to appeal to you and affect your behavior , as have the soundbites and talking points of political campaigns which rarely present the most nuanced perspective on the issues . and the way that we use ready-made phrases and responses gleaned from media reports or copied from the internet makes it easy to get away with not thinking too deeply or questioning your assumptions . so the next time you hear someone use the word orwellian , pay close attention . if they 're talking about the deceptive and manipulative use of language , they 're on the right track . if they 're talking about mass surveillance and intrusive government , they 're describing something authoritarian but not necessarily orwellian . and if they use it as an all-purpose word for any ideas they dislike , it 's possible their statements are more orwellian than whatever it is they 're criticizing . words have the power to shape thought . language is the currency of politics , forming the basis of society from the most common , everyday interactions to the highest ideals . orwell urged us to protect our language because ultimately our ability to think and communicate clearly is what stands between us and a world where war is peace and freedom is slavery .
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and the way that we use ready-made phrases and responses gleaned from media reports or copied from the internet makes it easy to get away with not thinking too deeply or questioning your assumptions . so the next time you hear someone use the word orwellian , pay close attention . if they 're talking about the deceptive and manipulative use of language , they 're on the right track .
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the word orwellian refers to the work of :
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the politics of 19th century europe were messy . ( what 's changed ? ) it was made up of various empires spreading across the world , trying to show each other who was the biggest power . they each built up massive armies to stave off war , thinking that everyone else would be too scared to fight against them , or so they thought ... things all changed when a gang of yugoslav nationalists who did n't like being part of austria-hungary shot the austro-hungarian archduke franz ferdinand while he was in sarajevo . swiftly the austro-hungarian empire declared war on serbia . russia came in to aid serbia , so germany decided to declare war on russia ! knowing that france would go to war with germany , germany decided to attack france quickly and invaded via neutral belgium and luxembourg and because of this , great britain stepped in to stop the germans getting any closer . it was a mess of allegiances and old rivalries with two sides forming the allies and the central powers . and so began what became known at the time as the great war ; the war to end all wars ! a new form of warfare evolved as these fully industrialized armies with engines , machine guns , airplanes and new chemical gas weapons fought against each other . it was the dawn of modern warfare . at the time , national pride was at an all-time high and men were proud to go off and fight for their country . it was seen as a romantic idea to go off and be a hero ! boys as young as 12 managed to lie their way into the army ranks only to discover that it was not such a sweet and honourable thing to die for one 's country ! germany marched on paris but was stopped by the french and both sides dug themselves into trenches in what became known as the western front . on the eastern front , the russians invaded austria-hungary but were stopped in eastern prussia by the germans . the ottoman empire joined in on the site of the central powers in 1914 . more and more nations from all over the world joined the fight as the war spread across europe . trench warfare was quite terrible . each army would dig a long network of trenches in the ground , fortifying the front with barbed wire and sandbags . i was a long stalemate where neither side dared advance on the other . machine guns were a new and very effective weapon . when the time was right , the army would climb up over the top and charge across no-man 's land to the enemy trench and capture it , thus gaining more land and taking another step towards their goal ! at least that was the plan ... spirits were high at least when the first christmas came by . both forces climbed out of their trenches to celebrate christmas together , talk , share stories and play football . when christmas ended , they would climb back into their trenches to become enemies once again . conditions in the trenches were dreadful . soldiers in france and belgium found their feet rotting away from the constant damp . in contrast , australian , new zealand and ottoman soldiers fighting in gallipoli had blisteringly hot trenches where rain and cold were replaced with dehydration and overheating . disease was everywhere in the trenches . 1916 saw a renewed push on the western front from both sides . thousands of french died at verdun as the germans unleashed their chlorine gas . the infamous battle of the somme was a long and grueling battle that lasted from july to november . the first day alone saw over 80,000 men wounded or killed ; mostly british , due to disastrous attacks . fundamental errors and contradictions from the high command led to confusion and unclear plans . in places , soldiers were n't organized in time to charge so by the time that they got going , the artillery had stopped firing on the germans , allowing them to easily fire upon their attackers . planes and artillery were supposed to clear the german barbed wire , but the shrapnel was ineffective against the wire . when the order came to go over the top , thousands of men ran out to their death to be caught on the barbed wire and picked off one by one by the german machine guns . this battle saw the first use of tanks by the british . ultimately , france and britain pushed against germany and gained much ground . by christmas 1916 , no man wanted good cheer wished upon their faceless enemy . during 1916 also , before the somme , irish republicans staged an uprising in dublin in the hopes to catch britain while they were distracted by the war . it was crushed by britain but after executing the rebel leaders irish support for britain and the war dropped , at least in the south of ireland . most irish troops after that came from the protestant north . on the sea britain mined many patches of international water to stop movement of german ships . germany was blockaded . after many naval battles , britain tried to stay in control of the seas , above the water at least ! germany were on the attack with the u-boat submarines adding a new dimension to naval warfare ; they could attack without warning ! they sank many ships including the ship the lusitania and because this broke loads of war rules , it ultimately influenced the united states of america to enter the war ... two years later ! the british pushed up through the arabian peninsula with t.e . lawrence aka lawrence of arabia helping to organize the arab revolt against the ottoman empire . in 1917 , the russians had a series of revolutions . in the february revolution , the tsars were gotten rid of , but russia remained in the war , and the october revolution , the bolsheviks took control and brought power to the people and sowed the seeds for communism in russia . the russians signed a treaty with germany and pulled out of the war causing an initial difficulty for the enemies of the central powers . the allies however became refreshed with reinforcements from the united states of america who eventually decided to enter the war in 1917 after germany tried to convince mexico to attack them . germany made a fierce and effective push before the allies could use their advantage . however , american troops continued to arrive in such great numbers that germany 's army could n't last any longer . the allies pushed up from italy , the balkans , and the middle east putting austria-hungary , bulgaria and the ottoman empire out of the war . as the allies advanced the western front , germany called for an armistice to stop the fighting , bringing victory to the allies and an end to the war . the fighting stopped on the 11th hour of the 11th day of the 11th month , 1918 . it took six months to negotiate terms and it was ultimately decided that the central powers were to pay for the damages they had caused in the war . germany only fully paid off this debt in 2010 . the map of europe was redrawn . soldiers who made it home again were changed men . they were haunted by the horrors which they had seen in the trenches . gas attacks , friends dying by their side , and the constant shelling of enemy artillery ; they were shell-shocked and so many found it impossible to go back to normal life after the trenches . many great poets and writers were inspired by their hell in the trenches such as wilfred owen , jrr tolkien and ernest hemingway of the so-called lost generation ? some survived , many did not . the world was a changed place after the world war . people had seen the death and destruction that could be dealt by mankind . the men who left to become heroes came back scarred , or worse never returned at all . the poppy is used to remember the millions who died in this war as it was just about the only flower to grow in the carnage-ridden wasteland between the trenches . the world was now a darker place . people hoped that it would indeed be the war to end all wars ! unfortunately , they were mistaken ... if you liked this video , please subscribe and you can follow me on twitter at @ johndruddy or find me on facebook through manny man comic and john d ruddy artisty actory guy and if you want to find out more about world war one and also the easter rising of 1916 i 'll be doing an irish tour of the play the rising by joe o ' byrne where we tell the story of the easter rising through the eyes of two friendly foes . billy mckeague , a loyalist from belfast and paddy o'brien , a republican from dublin . the dates are up here and you can find out more on facebook . thanks so much for the support glad you enjoy it !
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after many naval battles , britain tried to stay in control of the seas , above the water at least ! germany were on the attack with the u-boat submarines adding a new dimension to naval warfare ; they could attack without warning ! they sank many ships including the ship the lusitania and because this broke loads of war rules , it ultimately influenced the united states of america to enter the war ... two years later !
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what did germany use in the water to attack british vessels ?
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when i was in fourth grade , my teacher said to us one day : `` there are as many even numbers as there are numbers . '' `` really ? `` , i thought . well , yeah , there are infinitely many of both , so i suppose there are the same number of them . but even numbers are only part of the whole numbers , all the odd numbers are left over , so there 's got to be more whole numbers than even numbers , right ? to see what my teacher was getting at , let 's first think about what it means for two sets to be the same size . what do i mean when i say i have the same number of fingers on my right hand as i do on left hand ? of course , i have five fingers on each , but it 's actually simpler than that . i do n't have to count , i only need to see that i can match them up , one to one . in fact , we think that some ancient people who spoke languages that did n't have words for numbers greater than three used this sort of magic . for instance , if you let your sheep out of a pen to graze , you can keep track of how many went out by setting aside a stone for each one , and putting those stones back one by one when the sheep return , so you know if any are missing without really counting . as another example of matching being more fundamental than counting , if i 'm speaking to a packed auditorium , where every seat is taken and no one is standing , i know that there are the same number of chairs as people in the audience , even though i do n't know how many there are of either . so , what we really mean when we say that two sets are the same size is that the elements in those sets can be matched up one by one in some way . my fourth grade teacher showed us the whole numbers laid out in a row , and below each we have its double . as you can see , the bottom row contains all the even numbers , and we have a one-to-one match . that is , there are as many even numbers as there are numbers . but what still bothers us is our distress over the fact that even numbers seem to be only part of the whole numbers . but does this convince you that i do n't have the same number of fingers on my right hand as i do on my left ? of course not . it does n't matter if you try to match the elements in some way and it does n't work , that does n't convince us of anything . if you can find one way in which the elements of two sets do match up , then we say those two sets have the same number of elements . can you make a list of all the fractions ? this might be hard , there are a lot of fractions ! and it 's not obvious what to put first , or how to be sure all of them are on the list . nevertheless , there is a very clever way that we can make a list of all the fractions . this was first done by georg cantor , in the late eighteen hundreds . first , we put all the fractions into a grid . they 're all there . for instance , you can find , say , 117/243 , in the 117th row and 223rd column . now we make a list out of this by starting at the upper left and sweeping back and forth diagonally , skipping over any fraction , like 2/2 , that represents the same number as one the we 've already picked . we get a list of all the fractions , which means we 've created a one-to-one match between the whole numbers and the fractions , despite the fact that we thought maybe there ought to be more fractions . ok , here 's where it gets really interesting . you may know that not all real numbers -- that is , not all the numbers on a number line -- are fractions . the square root of two and pi , for instance . any number like this is called irrational . not because it 's crazy , or anything , but because the fractions are ratios of whole numbers , and so are called rationals ; meaning the rest are non-rational , that is , irrational . irrationals are represented by infinite , non-repeating decimals . so , can we make a one-to-one match between the whole numbers and the set of all the decimals , both the rationals and the irrationals ? that is , can we make a list of all the decimal numbers ? candor showed that you ca n't . not merely that we do n't know how , but that it ca n't be done . look , suppose you claim you have made a list of all the decimals . i 'm going to show you that you did n't succeed , by producing a decimal that is not on your list . i 'll construct my decimal one place at a time . for the first decimal place of my number , i 'll look at the first decimal place of your first number . if it 's a one , i 'll make mine a two ; otherwise i 'll make mine a one . for the second place of my number , i 'll look at the second place of your second number . again , if yours is a one , i 'll make mine a two , and otherwise i 'll make mine a one . see how this is going ? the decimal i 've produced ca n't be on your list . why ? could it be , say , your 143rd number ? no , because the 143rd place of my decimal is different from the 143rd place of your 143rd number . i made it that way . your list is incomplete . it does n't contain my decimal number . and , no matter what list you give me , i can do the same thing , and produce a decimal that 's not on that list . so we 're faced with this astounding conclusion : the decimal numbers can not be put on a list . they represent a bigger infinity that the infinity of whole numbers . so , even though we 're familiar with only a few irrationals , like square root of two and pi , the infinity of irrationals is actually greater than the infinity of fractions . someone once said that the rationals -- the fractions -- are like the stars in the night sky . the irrationals are like the blackness . cantor also showed that , for any infinite set , forming a new set made of all the subsets of the original set represents a bigger infinity than that original set . this means that , once you have one infinity , you can always make a bigger one by making the set of all subsets of that first set . and then an even bigger one by making the set of all the subsets of that one . and so on . and so , there are an infinite number of infinities of different sizes . if these ideas make you uncomfortable , you are not alone . some of the greatest mathematicians of cantor 's day were very upset with this stuff . they tried to make this different infinities irrelevant , to make mathematics work without them somehow . cantor was even vilified personally , and it got so bad for him that he suffered severe depression , and spent the last half of his life in and out of mental institutions . but eventually , his ideas won out . today , they 're considered fundamental and magnificent . all research mathematicians accept these ideas , every college math major learns them , and i 've explained them to you in a few minutes . some day , perhaps , they 'll be common knowledge . there 's more . we just pointed out that the set of decimal numbers -- that is , the real numbers -- is a bigger infinity than the set of whole numbers . candor wondered whether there are infinities of different sizes between these two infinities . he did n't believe there were , but could n't prove it . candor 's conjecture became known as the continuum hypothesis . in 1900 , the great mathematician david hilbert listed the continuum hypothesis as the most important unsolved problem in mathematics . the 20th century saw a resolution of this problem , but in a completely unexpected , paradigm-shattering way . in the 1920s , kurt gödel showed that you can never prove that the continuum hypothesis is false . then , in the 1960s , paul j. cohen showed that you can never prove that the continuum hypothesis is true . taken together , these results mean that there are unanswerable questions in mathematics . a very stunning conclusion . mathematics is rightly considered the pinnacle of human reasoning , but we now know that even mathematics has its limitations . still , mathematics has some truly amazing things for us to think about .
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well , yeah , there are infinitely many of both , so i suppose there are the same number of them . but even numbers are only part of the whole numbers , all the odd numbers are left over , so there 's got to be more whole numbers than even numbers , right ? to see what my teacher was getting at , let 's first think about what it means for two sets to be the same size .
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which of the numbers below which are irrational .
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translator : andrea mcdonough reviewer : bedirhan cinar i am going to start with a challenge . i want you to imagine each of these two scenes in as much detail as you can . scene number one : `` they gave us a hearty welcome . '' well , who are the people who are giving a hearty welcome ? what are they wearing ? what are they drinking ? ok , scene two : `` they gave us a cordial reception . '' how are these people standing ? what expressions are on their faces ? what are they wearing and drinking ? fix these pictures in your mind 's eye and then jot down a sentence or two to describe them . we 'll come back to them later . now on to our story . in the year 400 c.e . the celts in britain were ruled by romans . this had one benefit for the celts : the romans protected them from the barbarian saxon tribes of northern europe . but then the roman empire began to crumble , and the romans withdrew from britain . with the romans gone , the germanic tribes , the angles , saxons , jutes , and frisians quickly sailed across the water , did away with the celts , and formed kingdoms in the british isles . for several centuries , these tribes lived in britain , and their germanic language , anglo saxon , became the common language , what we call old english . although modern english speakers may think old english sounds like a different language , if you look and listen closely , you 'll find many words that are recognizable . for example , here is what the lord 's prayer looks like in old english . at first glance , it may look unfamiliar , but update the spelling a bit , and you 'll see many common english words . so the centuries passed with britains happily speaking old english , but in the 700 's , a series of viking invasions began , which continued until a treaty split the island in half . on one side were the saxons . on the other side were the danes who spoke a language called old norse . as saxons fell in love with their cute danish neighbors and marriages blurred the boundaries , old norse mixed with old english , and many old norse words like freckle , leg , root , skin , and want are still a part of our language . 300 years later , in 1066 , the norman conquest brought war again to the british isles . the normans were vikings who settled in france . they had abandoned the viking language and culture in favor of a french lifestyle , but they still fought like vikings . they placed a norman king on the english throne and for three centuries , french was the language of the british royalty . society in britain came to have two levels : french-speaking aristocracy and old english-speaking peasants . the french also brought many roman catholic clergymen with them who added latin words to the mix . old english adapted and grew as thousands of words flowed in , many having to do with government , law , and aristocracy . words like council , marriage , sovereign , govern , damage , and parliament . as the language expanded , english speakers quickly realized what to do if they wanted to sound sophisticated : they would use words that had come from french or latin . anglo saxon words seemed so plain like the anglo saxon peasants who spoke them . let 's go back to the two sentences you thought about earlier . when you pictured the hearty welcome , did you see an earthy scene with relatives hugging and talking loudly ? were they drinking beer ? were they wearing lumberjack shirts and jeans ? and what about the cordial reception ? i bet you pictured a far more classy and refined crowd . blazers and skirts , wine and caviar . why is this ? how is it that phrases that are considered just about synonymous by the dictionary can evoke such different pictures and feelings ? `` hearty '' and `` welcome '' are both saxon words . `` cordial '' and `` reception '' come from french . the connotation of nobility and authority has persisted around words of french origin . and the connotation of peasantry , real people , salt of the earth , has persisted around saxon words . even if you never heard this history before , the memory of it persists in the feelings evoked by the words you speak . on some level , it 's a story you already knew because whether we realize it consciously or only subconsciously , our history lives in the words we speak and hear .
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with the romans gone , the germanic tribes , the angles , saxons , jutes , and frisians quickly sailed across the water , did away with the celts , and formed kingdoms in the british isles . for several centuries , these tribes lived in britain , and their germanic language , anglo saxon , became the common language , what we call old english . although modern english speakers may think old english sounds like a different language , if you look and listen closely , you 'll find many words that are recognizable . for example , here is what the lord 's prayer looks like in old english .
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based on the increasingly diverse population in the united states and on the past history of english , what prediction can you make about the future of the english language ? what factors may influence the future evolution of our language ?
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take a look at the water in this glass . refreshing , hydrating , and invaluable to your survival . before you take a sip , though , how do you know that the water inside is free from disease-causing organisms and pollutants ? one out of ten people in the world ca n't actually be sure that their water is clean and safe to drink . why is that ? inadequate sanitation , poor protection of drinking water sources , and improper hygiene often lead to sewage and feces-contaminated water . that 's the ideal breeding ground for dangerous bacteria , viruses , and parasites . and the effects of these pathogens are staggering . diarrheal disease from unsafe water is one of the leading causes of death around the world for children under five . and according to a u.n. report from 2010 , microbial water-borne illnesses killed more people per year than war . proper treatment processes , though , can address these threats . they usually have three parts : sedimentation , filtration , and disinfection . once water has been collected in a treatment facility , it 's ready for cleaning . the first step , sedimentation , just takes time . the water sits undisturbed , allowing heavier particles to sink to the bottom . often , though , particles are just too small to be removed by sedimentation alone and need to be filtered . gravity pulls the water downward through layers of sand that catch leftover particles in their pores , prepping the water for its final treatment , a dose of disinfectant . chemicals , primarily forms of chlorine and ozone , are mixed in to kill off any pathogens and to disinfect pipes and storage systems . chlorine is highly effective in destroying water 's living organisms , but its use remains government-regulated because it has potentially harmful chemical byproducts . and if an imbalance of chlorine occurs during the disinfection process , it can trigger other chemical reactions . for example , levels of chlorine byproducts , like trihalomethanes , could skyrocket , leading to pipe corrosion and the release of iron , copper , and lead into drinking water . water contamination from these and other sources including leaching , chemical spills , and runoffs , has been linked to long-term health effects , like cancer , cardiovascular and neurological diseases , and miscarriage . unfortunately , analyzing the exact risks of chemically contaminated water is difficult . so while it 's clear that disinfectants make us safer by removing disease-causing pathogens , experts have yet to determine the full scope of how the chemical cocktail in our drinking water really impacts human health . so how can you tell whether the water you have access to , whether from a tap or otherwise , is drinkable ? firstly , too much turbidity , trace organic compounds , or high-density heavy metals like arsenic , chromium , or lead , mean that the water is unsuitable for consumption . a lot of contaminants , like lead or arsenic , wo n't be obvious without tests , but some clues , like cloudiness , brown or yellow coloration , a foul odor , or an excessive chlorine smell can indicate the need to investigate further . water testing kits can go a step further and confirm the presence of many different contaminants and chemicals . with many types of contamination , there are ways of treating water where it 's used instead of close to its source . point-of-use treatment has actually been around for thousands of years . ancient egyptians boiled away many organic contaminants with the sun 's heat . and in ancient greece , hippocrates designed a bag that trapped bad tasting sediments from water . today , point-of-use processes usually involve ionization to lower mineral content . they also use adsorption filtration , where a porous material called activated carbon strains the water to remove contaminants and chemical byproducts . while it 's not always an effective long-term solution , point-of-use treatment is portable , easy to install , and adaptable . and in regions where large-scale systems are unavailable , or where water has been contaminated further along its journey , these systems can mean the difference between life and death . clean water remains a precious and often scarce commodity . there are nearly 800 million of us who still do n't have regular access to it . the good news is that continued developments in water treatment , both on a large and small scale , can alleviate a lot of unsafe conditions . implementing proper systems where they 're needed and paying careful attention to the ones already in place will fulfill one of the most basic of our human needs .
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so how can you tell whether the water you have access to , whether from a tap or otherwise , is drinkable ? firstly , too much turbidity , trace organic compounds , or high-density heavy metals like arsenic , chromium , or lead , mean that the water is unsuitable for consumption . a lot of contaminants , like lead or arsenic , wo n't be obvious without tests , but some clues , like cloudiness , brown or yellow coloration , a foul odor , or an excessive chlorine smell can indicate the need to investigate further .
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from the context of the lesson , define the following terms : leaching , runoff , turbidity .
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you 're the realm 's greatest mathematician , but ever since you criticized the emperor 's tax laws , you 've been locked in the dungeon with only a marker to count the days . but one day , you 're suddenly brought before the emperor who looks even angrier than usual . one of his twelve governors has been convicted of paying his taxes with a counterfeit coin which has already made its way into the treasury . as the kingdom 's greatest mathematician , you 've been granted a chance to earn your freedom by identifying the fake . before you are the twelve identical looking coins and a balance scale . you know that the false coin will be very slightly lighter or heavier than the rest . but the emperor 's not a patient man . you may only use the scale three times before you 'll be thrown back into the dungeon . you look around for anything else you can use , but there 's nothing in the room - just the coins , the scale , and your trusty marker . how do you identify the counterfeit ? pause here if you want to figure it out for yourself ! answer in : 3 answer in : 2 answer in : 1 obviously you ca n't weigh each coin against all of the others , so you 'll have to weigh several coins at the same time by splitting the stack into multiple piles then narrowing down where the false coin is . start by dividing the twelve coins into three equal piles of four . placing two of these on the scale gives us two possible outcomes . if the two sides balance , all eight coins on the scale are real , and the fake must be among the remaining four . so how do you keep track of these results ? that 's where the marker comes in . mark the eight authentic coins with a zero . now , take three of them and weigh them against three unmarked coins . if they balance , the remaining unmarked coin must be the fake . if they do n't , draw a plus on the three unmarked coins if they 're heavier or a minus if they 're lighter . now , take two of the newly marked coins and weigh them against each other . if they balance , the third coin is fake . otherwise , look at their marks . if they are plus coins , the heavier one is the imposter . if they are marked with minus , it 's the lighter one . but what if the first two piles you weigh do n't balance ? mark the coins on the heavier side with a plus and those on the lighter side with a minus . you can also mark the remaining four coins with zeros since you know the fake one is already somewhere on the scale . now , you 'll need to think strategically so you can remove all remaining ambiguity in just two more weighings . to do this , you 'll need to reassemble the piles . one method is to replace three of the plus coins with three of the minus coins , and replace those with three of the zero coins . > from here , you have three possibilities . if the previously heavier side of the scale is still heavier , that means either the remaining plus coin on that side is actually the heavier one , or the remaining minus coin on the lighter side is actually the lighter one . choose either one of them , and weigh it against one of the regular coins to see which is true . if the previously heavier side became lighter , that means one of the three minus coins you moved is actually the lighter one . weigh two of them against each other . if they balance , the third is counterfeit . if not , the lighter one is . similarly , if the two sides balanced after your substitution , then one of the three plus coins you removed must be the heavier one . weigh two of them against each other . if they balance , the third one is fake . if not , then it 's the heavier one . the emperor nods approvingly at your finding , and the counterfeiting lord takes your place in the dungeon .
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you look around for anything else you can use , but there 's nothing in the room - just the coins , the scale , and your trusty marker . how do you identify the counterfeit ? pause here if you want to figure it out for yourself !
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if you know the single counterfeit coin is heavier than the others , what expression can be used to represent the maximum number of coins for which n weighs are guaranteed to reveal the counterfeit ?
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translator : andrea mcdonough reviewer : bedirhan cinar i am going to start with a challenge . i want you to imagine each of these two scenes in as much detail as you can . scene number one : `` they gave us a hearty welcome . '' well , who are the people who are giving a hearty welcome ? what are they wearing ? what are they drinking ? ok , scene two : `` they gave us a cordial reception . '' how are these people standing ? what expressions are on their faces ? what are they wearing and drinking ? fix these pictures in your mind 's eye and then jot down a sentence or two to describe them . we 'll come back to them later . now on to our story . in the year 400 c.e . the celts in britain were ruled by romans . this had one benefit for the celts : the romans protected them from the barbarian saxon tribes of northern europe . but then the roman empire began to crumble , and the romans withdrew from britain . with the romans gone , the germanic tribes , the angles , saxons , jutes , and frisians quickly sailed across the water , did away with the celts , and formed kingdoms in the british isles . for several centuries , these tribes lived in britain , and their germanic language , anglo saxon , became the common language , what we call old english . although modern english speakers may think old english sounds like a different language , if you look and listen closely , you 'll find many words that are recognizable . for example , here is what the lord 's prayer looks like in old english . at first glance , it may look unfamiliar , but update the spelling a bit , and you 'll see many common english words . so the centuries passed with britains happily speaking old english , but in the 700 's , a series of viking invasions began , which continued until a treaty split the island in half . on one side were the saxons . on the other side were the danes who spoke a language called old norse . as saxons fell in love with their cute danish neighbors and marriages blurred the boundaries , old norse mixed with old english , and many old norse words like freckle , leg , root , skin , and want are still a part of our language . 300 years later , in 1066 , the norman conquest brought war again to the british isles . the normans were vikings who settled in france . they had abandoned the viking language and culture in favor of a french lifestyle , but they still fought like vikings . they placed a norman king on the english throne and for three centuries , french was the language of the british royalty . society in britain came to have two levels : french-speaking aristocracy and old english-speaking peasants . the french also brought many roman catholic clergymen with them who added latin words to the mix . old english adapted and grew as thousands of words flowed in , many having to do with government , law , and aristocracy . words like council , marriage , sovereign , govern , damage , and parliament . as the language expanded , english speakers quickly realized what to do if they wanted to sound sophisticated : they would use words that had come from french or latin . anglo saxon words seemed so plain like the anglo saxon peasants who spoke them . let 's go back to the two sentences you thought about earlier . when you pictured the hearty welcome , did you see an earthy scene with relatives hugging and talking loudly ? were they drinking beer ? were they wearing lumberjack shirts and jeans ? and what about the cordial reception ? i bet you pictured a far more classy and refined crowd . blazers and skirts , wine and caviar . why is this ? how is it that phrases that are considered just about synonymous by the dictionary can evoke such different pictures and feelings ? `` hearty '' and `` welcome '' are both saxon words . `` cordial '' and `` reception '' come from french . the connotation of nobility and authority has persisted around words of french origin . and the connotation of peasantry , real people , salt of the earth , has persisted around saxon words . even if you never heard this history before , the memory of it persists in the feelings evoked by the words you speak . on some level , it 's a story you already knew because whether we realize it consciously or only subconsciously , our history lives in the words we speak and hear .
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what are they drinking ? ok , scene two : `` they gave us a cordial reception . '' how are these people standing ?
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why do english speakers have such predictable responses to the two phrases , “ they gave us a hearty welcome , ” and “ they gave us a cordial reception. ” ?
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hi , everybody ! i am a comparative anatomist . a comparative anatomist is someone who studies the structure of the body of lots of different animals . and my favorite animals are whales . i like to study whales because they 're so interesting . they 've adapted to a unique environment of living in the water . and what i 'm going to tell you about is how whales make sounds by basically farting with their face . you know that they do this farting thing with their blowhole ; they blow out air like that , but they also use air in lots of other ways . they use it for sound production , which is what i 'll focus on , but i also study other things they do with air , like keep it out of their bloodstream so they do n't get bubbles , which is what happens to human scuba divers when they get decompression sickness . but i 'd like to start with the story of how these animals make these farting noises , and that story begins with understanding how hard it is to look at whales , because they live underwater and they 're really big , so they 're hard animals to study . and in this picture -- you see that animal in the middle ? that 's a baby whale and it 's already the size of a bus ! when you look at whales , start with the top of their head because their nose is on the top of their head , kind of like a built-in snorkel . they breathe through that because they 're mammals and mammals breathe air . their nose can be opened and closed , as if you were to pinch it like this . you can see it 's open in the bottom frame , where the red arrows are . but not all whales have two nostrils . whales include the groups of dolphins and porpoises , and dolphins and porpoises , the small whales , have only one nostril on the top of their head , and they open and close that nostril by taking what is essentially an upper lip , like this , and turning it back over their nose , like this . that 's how they open and close their nose . so when they make sounds , what they 're basically doing is a raspberry , ( makes raspberry sound ) which is kind of like a fart , right ? or up in new york , we call it a bronx cheer . and the way they do that is by taking that big , fatty structure of a big fat lip , which , as you can see here in this picture , which is a cut through the middle of a dolphin 's head , that big fat lip is that big yellow portion there , and they roll it back and forth over the top of their nose so that they vibrate it , kind of like when you let the air out of a balloon and it makes that weird vibration sound . so this is what it sounds like when they make their noise : ( vibration noise ) hear it ? he 'll do it again when he faces the camera . ( vibration noise ) sounds like it 's farting underwater . what that dolphin is actually doing , though , is echolocation , which is making these series of pulses , and it uses it like a bat uses sonar . well , a bat uses radar , but when it 's underwater it 's sonar , so this animal is using sonar to see its world in sound . trying to understand how this works , you have to look at it as if you were looking at the amplifier speakers of a sound system . the small-toothed whales are basically the `` tweeters , '' and the sound is coming from that little nose that 's moving back and forth and coming out of their forehead . but the big whales are kind of like the `` woofers , '' the big speakers that you have in an amplifier system . and what 's happening is their sound is coming out of the throat . so if you tried to make sound like a whale -- make a sound right now , and go , `` ahhhhhh . '' ok , now put your hand on your throat , on your adam 's apple . you feel that vibration right there ? that is lost energy for you , because that 's not how you communicate to everybody . you do it out of the mouth . but if you open your mouth underwater , no one will hear you . you have to be able to take this energy and amplify it through the water . that 's what whales do . and when you hear their sound -- ( squeaking sound ) it 's kind of like when you squeak the air out of a balloon . so they get a lot of squeaky noises , but they also have this sound : ( vibrating sound ) it sounds like it 's farting , does n't it ? it 's like it 's got this giant whoopee cushion in its throat . so , how do you know that 's what a whale is doing ? well , we study whales that come to us from strandings . these are animals that die on the beach . small whales like dolphins and porpoises are easy ; we can take them to the lab . but the big whales -- we 've got to bring the lab to the whale . and this is what that looks like . i 'm the one in the middle with the red hat . i 'm not a very tall person , so you can see how big this whale was compared to me . the whale is 65 feet long . and my scalpel is this little tool on the side here . it basically looks like a hockey stick with a blade on the end of it . and doing a dissection of a whale is a very difficult process . you literally have to get into your work . it 's kind of like a giant bloody construction zone . you 're wearing a hard hat , you 're working with heavy machinery . in this case , by the way , that 's just the voice box of a blue whale . just the voice box . i 'm only five feet tall -- you can see it 's like 12 feet long . how do we know what 's going on ? well , we look at the voice box , or larynx , and we see -- this is from a baby whale so it 's much smaller . you see this little u-shaped thing i 've outlined in blue . that 's the part that 's vibrating . it 's kind of like our vocal folds . when i put my hand in there , where that blue sleeve is , you can see there 's a sack underneath it . that 's the whoopee cushion . that 's the air bubble or the balloon . so what these animals are doing -- and you can see , there 's this big black balloon in the throat , where the digestive tract , which is in blue , meets the breathing tract , which is in light blue , and right in the middle is that black sack . these animals are using that sack to make these sounds . and so they vibrate that and send it out . small-toothed whales also have air sacks ; they 're all over their heads , so it 's like they 're airheads . they use this to capture as much air as they can to take down with them when they 're diving , because when you dive , pressures increase , and that decreases the volume of air you have available . but more importantly , having that sack allows them to recycle the air that they 're using , because air is a precious commodity . you do n't want to have to go back up to the surface to get more . so when you make a sound underwater , if you 're a whale -- let 's hear you start making a sound , go `` ahhhh . '' but whales keep their mouths closed , so go `` ahhhmm . '' ( audience makes noise ) you 're all humming , right ? but whales keep their nose closed and go , `` mmmm . '' ( makes noise ) what happened ? you ca n't make the sound anymore once you close your nose because you 've pressurized the system . whales , by having air sacks , keep themselves from pressurizing the system , which means the air continues to flow , and so if you had a bag on the end of your nose , you 'd be able to make air continue to flow . so i hope you 've enjoyed that . that 's what a comparative anatomist does for a living . we study the structure of these animals . we try to mimic it ; we apply it back to the human situation , maybe making new technologies for protective devices or maybe even making new treatments for medicines for people 's diseases who mimic these weird environments . so i hope you enjoyed that . thank you . ( applause )
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they 've adapted to a unique environment of living in the water . and what i 'm going to tell you about is how whales make sounds by basically farting with their face . you know that they do this farting thing with their blowhole ; they blow out air like that , but they also use air in lots of other ways .
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toothed whales , such as dolphins , make echolocation sounds by vibrating a fatty structure derived from the :
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sea turtles are miraculous . first , they 've been around since the late jurassic , roughly 150 million years ago . cohorts of the dinosaurs , sea turtles have survived through the challenges of eons , existing still today , where many others have ended their evolutionary run . second , throughout the centuries and up till today , every living adult sea turtle has overcome the odds , existing as a consequence of chance , skill , and capability . the gauntlet each sea turtle faces in the course of its lifetime goes thus : first , deposited as a clutch of leathery , ping-pong ball-sized eggs into a nesting pit dug by its mother high on the beach , of the 50 to 200 eggs laid , roughly 20 percent will never hatch . roughly a month and a half after having been laid , the surviving eggs hatch , and the young turtles , each small enough to fit in the palm of your hand , squirm to the surface , emerging from the sand en masse , and making their desperate dash for the sea . along the way , debris , pitfalls , crabs , gulls , raccoons , and other threats will claim roughly 50 percent of those who rose from the sand . for those that actually reach the surf , they trade one set of threats for another , as they first face the repelling force of the waves , and then find a whole new host of predators awaiting them : various fish , dolphins , sharks , and sea birds , as the young turtles come to the surface for air . for their first few days of life , should they count themselves amongst the living , the vulnerable turtles swim frantically forward . ultimately , they will often look to settle in a patch of flotsam , preferably a patch of floating seaweed . now for the next several months , they will seek to avoid those that would eat them , find that which they might eat themselves , and not fall to the pressures of challenging weather or unfortunate currents . in this phase , roughly 50 percent of those who reach the surf will perish . ultimately , with the passage of years , the survivors will increase in size , from that of a dinner plate at year one to that of a dinner table , in the case of one species at least , the leatherback , a decade or so later . with size comes some measure of protection . the only truly worrisome predators now are some of the larger shark species -- bulls , tigers , and whites -- and the occasional killer whale . at approximately two decades of age , the survivors will be old enough themselves to breed , and continue the cycle which their very existence heralds . of those that began as eggs on a distant beach , now less than 10 percent remain , at least , those were the odds prior to significant human interference . over the past century , and in particular in the last several decades , human endeavors , from beach development to plastic refuse to poaching , long lines , nets , and even noxious chemicals , including oil , have upped the ante for sea turtles , causing their survival rate to drop to around one percent or less , from each nesting cycle . it is this added human pressure which has pushed each of the eight sea turtle species into either a threatened or endangered state . for while they have evolved to overcome a host of obstacles , the most recent has arisen so quickly and at such scale that the species find themselves overwhelmed . so let 's quickly recap this cycle of odds . using a hypothetical nesting season , for females may nest multiple times in a single year , of 1,000 eggs , for sake of ease . 1000 eggs laid . 800 hatch . 400 make it to the water . 200 progress toward adulthood . 20 survive to breeding age -- that is , without human interference . two survive to breeding age with human interference . so a breeding adult sea turtle is the very embodiment of a long shot . it is the exception , not the rule . a jackpot . it is , in a very real sense , a miracle .
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sea turtles are miraculous . first , they 've been around since the late jurassic , roughly 150 million years ago .
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approximately how many decades does it take a female sea turtle to reach the stage where she can return to the beach and nest herself ?
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since the dawn of humanity , an estimated 100.8 billion people have lived and died , a number that increases by about .8 % of the world 's population each year . what happens to all of those people 's bodies after they die and will the planet eventually run out of burial space ? when a person 's heart stops beating , the body passes through several stages before it begins decomposing . within minutes after death , the blood begins settling in the lower-most parts of the body . usually eight to twelve hours later , the skin in those areas is discolored by livor mortis , or post-mortem stain . and while at the moment of death the body 's muscles relax completely in a condition called primary flaccidity , they stiffen about two to six hours later in what 's known as rigor mortis . this stiffening spreads through the muscles , and its speed can be affected by age , gender , and the surrounding environment . the body also changes temperature , usually cooling off to match its environment . next comes decomposition , the process by which bacteria and insects break apart the body . many factors affect the rate of decomposition . there is , however , a basic guide of the effect of the environment on decompositon called casper 's law . it says that if all other factors are equal , a body exposed to air decomposes twice as fast as one immersed in water and eight times as fast as one buried in earth . soil acidity also greatly affects bone preservation . high-acidity soils with a ph of less than 5.3 will rapidly decompose bone , whereas in a neutral or basic soil with a ph of 7 or more , a skeleton can remain in relatively good condition for centuries . different cultures throughout history have developed unique approaches to burials . as far back as the first neanderthal burials , death was accompanied by rituals , like the positioning , coloring , or decorating of corpses . traditional christian burials decorate the body in dress , while in traditional islam , a body is wrapped in a piece of ritual fabric with the face oriented toward mecca . traditional hindus ceremonially burn the body , and zoroastrians , followers of one of the oldest monotheistic religions , traditionally place bodies atop a tower to expose them to the sun and scavenging birds.` before the industrial revolution , burials were simple and accessible . these days , with suitable burial land running out in high-population areas , purchasing private gravesites can be costly , and many people ca n't afford simple burials . even cremation , the second most common burial practice in the world , comes with a high cost . as for the question of running out of space , the issue is n't so much about total land in the world as it is that large populations cluster together within cities . most of the big cities in the world may run out of suitable burial grounds within a century . for london , it 's even sooner . that may happen by 2035 . so are there alternatives to traditional burials that might help with the space issue ? in some countries , skyscraper cemeteries enable vertical burials . some options focus on the body 's relationship with the environment . promession , for example , freeze-dries and pulverizes the body , creating a powder that can turn into compost when mixed with oxygen and water . there are also green burials that use special materials , such as biodegradable caskets , urns that sprout trees , and burial suits that grow mushrooms . eternal reefs take that concept to the depths of the ocean using a mixture of ashes and cement to create marine habitats for sea life . death is an inevitable part of the human condition , but how we treat bodies and burials continues to evolve . we may each have different spiritual , religious , or practical approaches to dying , but the ever-increasing demand for burial space might give us a push to be creative about where our bodies go after the final stages of life .
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high-acidity soils with a ph of less than 5.3 will rapidly decompose bone , whereas in a neutral or basic soil with a ph of 7 or more , a skeleton can remain in relatively good condition for centuries . different cultures throughout history have developed unique approaches to burials . as far back as the first neanderthal burials , death was accompanied by rituals , like the positioning , coloring , or decorating of corpses .
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as burial space ran low after the industrial revolution in different cities , what new methods were developed ?
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in 1845 , ireland 's vast potato fields were struck by an invasive fungal disease that rapidly infested this staple crop . the effect was devastating . one million people died of famine , and over a million more were forced to leave ireland . nowadays , we avoid such agricultural catastrophes with the help of pesticides . those are a range of manmade chemicals that control insects , unwanted weeds , funguses , rodents , and bacteria that may threaten our food supply . they 've become an essential part of our food system . as populations have grown , monoculture , single crop farming , has helped us feed people efficiently . but it 's also left our food vulnerable to extensive attack by pests . in turn , we 've become more dependent on pesticides . today , we annually shower over 5 billion pounds of pesticides across the earth to control these unwanted visitors . the battle against pests , especially insects , has marked agriculture 's long history . records from thousands of years ago suggest that humans actively burned some of their crops after harvest to rid them of pests . there 's even evidence from ancient times that we recruited other insects to help . in 300 a.d. , chinese farmers specially bred ferocious predatory ants in orange orchards to protect the trees from other bugs . later , as large-scale farming spread , we began sprinkling arsenic , lead , and copper treatments on crops . but these were incredibly toxic to humans as well . as our demand for more , safer produce increased , so did the need for effective chemicals that could control pests on a grander scale . this ushered in the era of chemical pesticides . in 1948 , a swiss chemist named paul hermann müller was awarded a nobel prize for his discovery of dichlorodiphenyltrichloroethane , also known as ddt . this new molecule had unparalleled power to control many insect species until the 1950s , when insects became resistant to it . worse , the chemical actually drove dramatic declines in bird populations , poisoned water sources , and was eventually found to cause long-term health problems in humans . by 1972 , ddt had been banned in the united states , and yet traces still linger in the environment today . since then , chemists have been searching for alternatives . with each new wave of inventions , they 've encountered the same obstacle - rapid species evolution . as pesticides destroy pest populations , they leave behind only the most resistant individuals . they then pass on their pesticide-resisting genes to the next generation . that 's lead to the rise of super bugs , such as the colorado potato beetle , which is resistant to over 50 different insecticides . another downside is that other bugs get caught in the crossfire . some of these are helpful predators of plant pests or vital pollinators , so erasing them from agriculture wipes out their benefits , too . pesticides have improved over time and are currently regulated by strict safety standards , but they still have the potential to pollute soil and water , impact wildlife , and even harm us . so considering all these risks , why do we continue using pesticides ? although they 're imperfect , they currently may be our best bet against major agricultural disasters , not to mention mosquito-born diseases . today , scientists are on a quest for alternative pest control strategies that balance the demands of food production with environmental concerns . nature has become a major source of inspiration , from natural plant and fungal chemicals that can repel or attract insects , to recruiting other insects as crop bodyguards . we 're also turning to high-tech solutions , like drones . programmed to fly over crops , these machines can use their sensors and gps to carry out more targeted sprays that limit a pesticide 's wider environmental impact . with a combination of biological understanding , environmental awareness , and improved technologies , we have a better chance of finding a holistic solution to pests . chemical pesticides may never shake their controversial reputation , but with their help , we can ensure that agricultural catastrophes stay firmly in our past .
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today , scientists are on a quest for alternative pest control strategies that balance the demands of food production with environmental concerns . nature has become a major source of inspiration , from natural plant and fungal chemicals that can repel or attract insects , to recruiting other insects as crop bodyguards . we 're also turning to high-tech solutions , like drones .
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if pesticides are openly applied in fields , why do some insects evolve pesticide resistance while others don ’ t ?
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if you lined up all the blood vessels in your body , they 'd be 95,000 kilometers long and everyday , they carry the equivalent of over 7,500 liters of blood , though that 's actually the same four or five liters recycled over and over , delivering oxygen , and precious nutrients like glucose and amino acids to the body 's tissues . all that blood exerts a force on the muscular walls of the blood vessels . that force is called blood pressure , and it rises and falls with the phases of the heartbeat . it 's highest during systole , when the heart contracts to force blood through the arteries . this is your systolic blood pressure . when the heart is at rest between beats , blood pressure falls to its lowest value , the diastolic pressure . a typical healthy individual produces a systolic pressure between 90 and 120 millimeters of mercury , and diastolic pressure between 60 and 80 . taken together , a normal reading is a bit less than 120 over 80 . the blood traverses the landscape of the body through the pipes of the circulatory system . in any plumbing system , several things can increase the force on the walls of the pipes : the properties of the fluid , extra fluid , or narrower pipes . so if the blood thickens , a higher pressure is needed to push it , so the heart will pump harder . a high-salt diet will lead to a similar result . the salt promotes water retention , and the extra fluid increases the blood volume and blood pressure , and stress , like the fight or flight response , releases hormones , like epinephrine and norepinephrine that constrict key vessels , increasing the resistance to flow and raising the pressure upstream . blood vessels can usually handle these fluctuations easily . elastic fibers embedded in their walls make them resilient , but if your blood pressure regularly rises above about 140 over 90 , what we call hypertension , and stays there , it can cause serious problems . that 's because the extra strain on the arterial wall can produce small tears . when the injured tissue swells up , substances that respond to the inflammation , like white blood cells , collect around the tears . fat and cholesterol floating in the blood latch on , too , eventually building up to form a plaque that stiffens and thickens the inner arterial wall . this condition is called atherosclerosis , and it can have dangerous consequences . if the plaque ruptures , a blood clot forms on top of the tear , clogging the already narrowed pipe . if the clot is big enough , it can completely block the flow of oxygen and nutrients to cells downstream . in vessels that feed the heart , that will cause a heart attack , when oxygen-deprived cardiac muscle cells start to die . if the clot cuts off blood flow to the brain , it causes a stroke . dangerously clogged blood vessels can be widened by a procedure called an angioplasty . there , doctors thread a wire through the vessel to the obstructed site , and then place a deflated balloon catheter over the wire . when the balloon is inflated , it forces the passageway open again . sometimes a rigid tube called a stent is placed in a vessel to held hold it open , letting the blood flow freely to replenish the oxygen-starved cells downstream . staying flexible under pressure is a tough job for arteries . the fluid they pump is composed of substances that can get sticky and clog them , and your typical healthy heart beats about 70 times a minute , and at least 2.5 billion times during an average lifetime . that may sound like an insurmountable amount of pressure , but do n't worry , your arteries are well suited for the challenge .
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it 's highest during systole , when the heart contracts to force blood through the arteries . this is your systolic blood pressure . when the heart is at rest between beats , blood pressure falls to its lowest value , the diastolic pressure .
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hypertension occurs when systolic and diastolic blood pressure regularly rises above _____ and _____ millimeters of mercury , respectively .
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after the french revolution erupted in 1789 , europe was thrown into chaos . neighboring countries ' monarchs feared they would share the fate of louis xvi , and attacked the new republic , while at home , extremism and mistrust between factions lead to bloodshed . in the midst of all this conflict , a powerful figure emerged to take charge of france . but did he save the revolution or destroy it ? `` order , order , who 's the defendant today ? i do n't see anyone . '' `` your honor , this is napoléon bonaparte , the tyrant who invaded nearly all of europe to compensate for his personal stature-based insecurities . '' `` actually , napoléon was at least average height for his time . the idea that he was short comes only from british wartime propaganda . and he was no tyrant . he was safeguarding the young republic from being crushed by the european monarchies . '' `` by overthrowing its government and seizing power himself ? '' `` your honor , as a young and successful military officer , napoléon fully supported the french revolution , and its ideals of liberty , equality , and fraternity . but the revolutionaries were incapable of real leadership . robespierre and the jacobins who first came to power unleashed a reign of terror on the population , with their anti-catholic extremism and nonstop executions of everyone who disagreed with them . and the directory that replaced them was an unstable and incompetent oligarchy . they needed a strong leader who could govern wisely and justly . '' `` so , france went through that whole revolution just to end up with another all-powerful ruler ? '' `` not quite . napoléon 's new powers were derived from the constitution that was approved by a popular vote in the consulate . '' `` ha ! the constitution was practically dictated at gunpoint in a military coup , and the public only accepted the tyrant because they were tired of constant civil war . '' `` be that as it may , napoléon introduced a new constitution and a legal code that kept some of the most important achievements of the revolution in tact : freedom of religion abolition of hereditary privilege , and equality before the law for all men . '' `` all men , indeed . he deprived women of the rights that the revolution had given them and even reinstated slavery in the french colonies . haiti is still recovering from the consequences centuries later . what kind of equality is that ? '' `` the only kind that could be stably maintained at the time , and still far ahead of france 's neighbors . '' `` speaking of neighbors , what was with all the invasions ? '' `` great question , your honor . '' `` which invasions are we talking about ? it was the neighboring empires who had invaded france trying to restore the monarchy , and prevent the spread of liberty across europe , twice by the time napoléon took charge . having defended france as a soldier and a general in those wars , he knew that the best defense is a good offense . '' `` an offense against the entire continent ? peace was secured by 1802 , and other european powers recognized the new french regime . but bonaparte could n't rest unless he had control of the whole continent , and all he knew was fighting . he tried to enforce a european-wide blockade of britain , invaded any country that did n't comply , and launched more wars to hold onto his gains . and what was the result ? millions dead all over the continent , and the whole international order shattered . '' `` you forgot the other result : the spread of democratic and liberal ideals across europe . it was thanks to napoléon that the continent was reshaped from a chaotic patchwork of fragmented feudal and religious territories into efficient , modern , and secular nation states where the people held more power and rights than ever before . '' `` should we also thank him for the rise of nationalism and the massive increase in army sizes ? you can see how well that turned out a century later . '' `` so what would european history have been like if it were n't for napoléon ? '' `` unimaginably better/worse . '' napoléon seemingly unstoppable momentum would die in the russian winter snows , along with most of his army . but even after being deposed and exiled , he refused to give up , escaping from his prison and launching a bold attempt at restoring his empire before being defeated for the second and final time . bonaparte was a ruler full of contradictions , defending a popular revolution by imposing absolute dictatorship , and spreading liberal ideals through imperial wars , and though he never achieved his dream of conquering europe , he undoubtedly left his mark on it , for better or for worse .
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after the french revolution erupted in 1789 , europe was thrown into chaos . neighboring countries ' monarchs feared they would share the fate of louis xvi , and attacked the new republic , while at home , extremism and mistrust between factions lead to bloodshed .
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in what ways did napoleon uphold the ideals of the french revolution , and how did he subvert them ?
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translator : andrea mcdonough reviewer : bedirhan cinar ever see a medieval painting of baby jesus sitting or standing on his mother 's lap and wonder why she 's so large ? paintings like cimabue 's enthroned madonna with angels or duccio 's maesta also appear out of proportion . if mary were to stand up , it seems , the angels in the picture would be as tall as her shin bone , and her torso would be disproportionately small when compared to her legs . maybe you thought the artist simply was n't skilled enough to paint realistically or lacked the mathematical skill of perspective . but that 's not the full story . to understand why , we need to go back to the late fifth century when the city of rome was attacked by the goths . rome was built in marble and meant to last forever . it represented , for many years , the pinnacle of human civilization , so its destruction left a huge void . theologians , who preached about a world beyond the physical , began attracting an audience as rome crumbled , and christianity started to fill the void left by the empire . as a replacement for the physical beauty of rome , christianity offered a metaphysical beauty of virtue and an eternal heaven that could not be destroyed as rome had . after the fall of rome , early medieval theologians turned away from physical beauty , rejecting it in favor of inner-beauty . they maintained that while the physical world was temporary , virtue and religion were permanent . beautiful objects could lead to a misguided worship of the object rather than the worship of goodness . it is said that the early sixth century preacher , st. benedict , upon thinking of a beautiful woman , threw himself into a thorn patch , and through his suffering , regained his focus on spiritual beauty . he feared his desire for the beautiful woman would distract him from his desire to love god . as european civilization transitioned away from empires and towards religion , monasteries became the gatekeepers of knowledge , which meant that classical books that praised physical pleasures were not copied or protected . without protection , they became the victims of natural decay , fire , flooding , or pests . and without the help of monks transcribing new copies , these texts and the philosophies they carried disappeared in western europe and were replaced by the works of people like st. benedict , which brings us back to these depictions of jesus and mary . because christianity had so fervently rejected physical beauty , these medieval artists purposefully avoided aesthetically pleasing forms . at first , decorations for churches or palaces were limited to interesting geometric patterns , which could be pleasing without inspiring sinful thoughts of physical pleasure . as the medieval period progressed , depictions of jesus and mary were tolerated , but the artist clearly made an effort to veil mary and give her disproportionately large legs , with those enormous shin bones . the fear remained that a beautiful illustration of mary might inspire the viewer to love the painting or the physical form of mary , rather than the virtue she 's meant to represent . so even though it may be fun to think we can paint more realistically than cimabuey or duccio , we need to remember that they had different goals when picking up a paintbrush .
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but that 's not the full story . to understand why , we need to go back to the late fifth century when the city of rome was attacked by the goths . rome was built in marble and meant to last forever .
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who attacked rome in the late fifth century , affecting the way people were depicted in art ?
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today lots of girls play sports . but , for a long time , girls were not encouraged to kick , throw , run , jump , shoot , slide , or hit like boys . so , why did things change ? and how much have they changed ? are girls and boys treated equally when it comes to sports ? to begin to answer these questions , we have to look back . in 1972 , congress passed a law called title ix , which protected girls and women from discrimination in schools , colleges , and universities . this included discrimination in school-sponsored sports . at that time , only 15 % of college athletes were women , and in high schools , only 7 % of athletes were girls . female athletes did n't get a lot of support either and often had to provide their own uniforms and equipment . it was title ix that forced school administrators to make sports more equal . but what does equal mean in sports ? the government developed rules to measure equality under two general categories : participation and treatment . in the early days of title ix , the number of girls playing sports was so low that it would have been very difficult for schools to suddenly provide exactly the same number of opportunities for girls and boys . instead , the government wrote rules that gave schools three options , or tests , to demonstrate fairness in opportunities for girls . the three tests are proportionality , progress , and satisfied interests . a school can pick which test to follow . proportionality means that girls should receive the same percentage of athletic opportunities as the percentage of girls in the student body . so , if 51 % of students are girls , then girls should have approximately 51 % of the opportunities to play sports . the second test , progress , requires schools to make up for the days when girls had fewer opportunities by adding new sports for girls on a regular basis . the third test asks if girls interested in athletics are satisfied . under this test , a school must regularly ask female students what sports they are interested in and also take into consideration the popularity of certain sports in the area where the school is located . it must , then , add teams according to the girls ' interests . another important part of title ix is that it does n't just look at how many athletic opportunities are available to each sex but whether those opportunities are of equal quality . specifically , title ix requires equality between boys and girls teams for things like equipment and supplies , publicity , the scheduling of games and practice times , and the quality and number of coaches . girls should also have equal access to locker rooms , practice spaces , and competitive facilities , as well as medical services . so , if the best time to play basketball is on friday nights because that 's when most parents and fans can come , then the girls and boys teams should take turns playing on friday night . if boys teams play in a stadium with lights , scoreboards , and concession stands , then girls teams must have the same opportunity , either by sharing those facilities or getting their own of equal quality . but , as we all know , just because a law exists does n't mean that everybody follows it . school officials are responsible for making sure there is fairness in sports , but you can help , too , by keeping an eye on your own school . look around . are there a lot more boys than girls who play sports ? is the boys ' soccer field better than the girls ' ? are athletic trainers available to all teams equally ? does the baseball team get new uniforms every year , while the softball team gets them every three years ? if you think there might be inequality in your schools , you can approach a school administrator , a parent , or the office of civil rights , a government agency that makes sure schools comply with title ix because equality is important for everyone , both on the field and off .
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it must , then , add teams according to the girls ' interests . another important part of title ix is that it does n't just look at how many athletic opportunities are available to each sex but whether those opportunities are of equal quality . specifically , title ix requires equality between boys and girls teams for things like equipment and supplies , publicity , the scheduling of games and practice times , and the quality and number of coaches .
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which of the following is not an option for schools to measure equality in the number of athletic opportunities for each sex ?
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energy is all around us , a physical quantity that follows precise natural laws . our universe has a finite amount of it ; it 's neither created nor destroyed but can take different forms , such as kinetic or potential energy , with different properties and formulas to remember . for instance , an led desk lamp 's 6 watt bulb transfers 6 joules of light energy per second . but let 's jump back up into space to look at our planet , its systems , and their energy flow . earth 's physical systems include the atmosphere , hydrosphere , lithosphere , and biosphere . energy moves in and out of these systems , and during any energy transfer between them , some is lost to the surroundings , as heat , light , sound , vibration , or movement . our planet 's energy comes from internal and external sources . geothermal energy from radioactive isotopes and rotational energy from the spinning of the earth are internal sources of energy , while the sun is the major external source , driving certain systems , like our weather and climate . sunlight warms the surface and atmosphere in varying amounts , and this causes convection , producing winds and influencing ocean currents . infrared radiation , radiating out from the warmed surface of the earth , gets trapped by greenhouse gases and further affects the energy flow . the sun is also the major source of energy for organisms . plants , algae , and cyanobacteria use sunlight to produce organic matter from carbon dioxide and water , powering the biosphere 's food chains . we release this food energy using chemical reactions , like combustion and respiration . at each level in a food chain , some energy is stored in newly made chemical structures , but most is lost to the surroundings , as heat , like your body heat , released by your digestion of food . now , as plants are eaten by primary consumers , only about 10 % of their total energy is passed on to the next level . since energy can only flow in one direction in a food chain , from producers on to consumers and decomposers , an organism that eats lower on the food chain , is more efficient than one higher up . so eating producers is the most efficient level at which an animal can get its energy , but without continual input of energy to those producers , mostly from sunlight , life on earth as we know it would cease to exist . we humans , of course , spend our energy doing a lot of things besides eating . we travel , we build , we power all sorts of technology . to do all this , we use sources like fossil fuels : coal , oil , and natural gas , which contain energy that plants captured from sunlight long ago and stored in the form of carbon . when we burn fossil fuels in power plants , we release this stored energy to generate electricity . to generate electricity , heat from burning fossil fuels is used to power turbines that rotate magnets , which , in turn , create magnetic field changes relative to a coil of wire , causing electrons to be induced to flow in the wire . modern civilization depends on our ability to keep powering that flow of electrons . fortunately , we are n't limited to burning non-renewable fossil fuels to generate electricity . electrons can also be induced to flow by direct interaction with light particles , which is how a solar cell operates . other renewable energy sources , such as wind , water , geothermal , and biofuels can also be used to generate electricity . global demand for energy is increasing , but the planet has limited energy resources to access through a complex energy infrastructure . as populations rise , alongside rates of industrialization and development , our energy decisions grow more and more important . access to energy impacts health , education , political power , and socioeconomic status . if we improve our energy efficiency , we can use our natural resources more responsibly and improve quality of life for everyone .
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energy moves in and out of these systems , and during any energy transfer between them , some is lost to the surroundings , as heat , light , sound , vibration , or movement . our planet 's energy comes from internal and external sources . geothermal energy from radioactive isotopes and rotational energy from the spinning of the earth are internal sources of energy , while the sun is the major external source , driving certain systems , like our weather and climate . sunlight warms the surface and atmosphere in varying amounts , and this causes convection , producing winds and influencing ocean currents .
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what is a source of energy that is internal to the earth systems ?
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on july 26 , 1943 , los angeles was blanketed by a thick gas that stung people 's eyes and blocked out the sun . panicked residents believed their city had been attacked using chemical warfare . but the cloud was n't an act of war . it was smog . a portmanteau of smoke and fog , the word smog was coined at the beginning of the 20th century to describe the thick gray haze that covered cities such as london , glasgow , and edinburgh . this industrial smog was known to form when smoke from coal-burning home stoves and factories combined with moisture in the air . but the smog behind the la panic was different . it was yellowish with a chemical odor . since the city did n't burn much coal , its cause would remain a mystery until a chemist named arie haagen-smit identified two culprits , volatile organic compounds , or vocs , and nitrous oxides . vocs are compounds that easily become vapors and may contain elements , such as carbon , oxygen , hydrogen , chlorine , and sulfur . some are naturally produced by plants and animals , but others come from manmade sources , like solvents , paints , glues , and petroleum . meanwhile , the incomplete combustion of gas in motor vehicles releases nitrous oxide . that 's what gives this type of smog its yellowish color . vocs and nitrous oxide react with sunlight to produce secondary pollutants called pans and tropospheric , or ground level , ozone . pans and ozone cause eye irritation and damage lung tissue . both are key ingredients in photochemical smog , which is what had been plaguing la . so why does smog affect some cities but not others ? both industrial and photochemical smog combine manmade pollution with local weather and geography . london 's high humidity made it a prime location for industrial smog . photochemical smog is strongest in urban areas with calm winds and dry , warm , sunny weather . the ultraviolet radiation from sunlight provides the energy necessary to breakdown molecules that contribute to smog formation . cities surrounded by mountains , like la , or lying in a basin , like beijing , are also especially vulnerable to smog since there 's nowhere for it to dissipate . that 's also partially due to a phenomenon known as temperature inversion , where instead of warm air continuously rising upward , a pollution-filled layer of air remains trapped near the earth 's surface by a slightly warmer layer above . smog is n't just an aesthetic eyesore . both forms of smog irritate the eyes , nose , and throat , exacerbate conditions like asthma and emphysema , and increase the risk of respiratory infections like bronchitis . smog can be especially harmful to young children and older people and exposure in pregnant women has been linked to low birth weight and potential birth defects . secondary pollutants found in photochemical smog can damage and weaken crops and decrease yield , making them more susceptible to insects . yet for decades , smog was seen as the inevitable price of civilization . londoners had become accustomed to the notorious pea soup fog swirling over their streets until 1952 , when the great smog of london shut down all transportation in the city for days and caused more than 4,000 respiratory deaths . as a result , the clean air act of 1956 banned burning coal in certain areas of the city , leading to a massive reduction in smog . similarly , regulations on vehicle emissions and gas content in the us reduced the volatile compounds in the air and smog levels along with them . smog remains a major problem around the world . countries like china and poland that depend on coal for energy experience high levels of industrial smog . photochemical smog and airborne particles from vehicle emissions affect many rapidly developing cities , from mexico city and santiago to new delhi and tehran . governments have tried many methods to tackle it , such as banning cars from driving for days at a time . as more than half of the world 's population crowds into cities , considering a shift to mass transit and away from fossil fuels may allow us to breathe easier .
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but the cloud was n't an act of war . it was smog . a portmanteau of smoke and fog , the word smog was coined at the beginning of the 20th century to describe the thick gray haze that covered cities such as london , glasgow , and edinburgh .
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smog formation will continue to increase as urban growth occurs across the world . brainstorm three ways to decrease smog formation in areas that are prone to it .
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probability is an area of mathematics that is everywhere . we hear about it in weather forecasts , like there 's an 80 % chance of snow tomorrow . it 's used in making predictions in sports , such as determining the odds for who will win the super bowl . probability is also used in helping to set auto insurance rates and it 's what keeps casinos and lotteries in business . how can probability affect you ? let 's look at a simple probability problem . does it pay to randomly guess on all 10 questions on a true/ false quiz ? in other words , if you were to toss a fair coin 10 times , and use it to choose the answers , what is the probability you would get a perfect score ? it seems simple enough . there are only two possible outcomes for each question . but with a 10-question true/ false quiz , there are lots of possible ways to write down different combinations of ts and fs . to understand how many different combinations , let 's think about a much smaller true/ false quiz with only two questions . you could answer `` true true , '' or `` false false , '' or one of each . first `` false '' then `` true , '' or first `` true '' then `` false . '' so that 's four different ways to write the answers for a two-question quiz . what about a 10-question quiz ? well , this time , there are too many to count and list by hand . in order to answer this question , we need to know the fundamental counting principle . the fundamental counting principle states that if there are a possible outcomes for one event , and b possible outcomes for another event , then there are a times b ways to pair the outcomes . clearly this works for a two-question true/ false quiz . there are two different answers you could write for the first question , and two different answers you could write for the second question . that makes 2 times 2 , or , 4 different ways to write the answers for a two-question quiz . now let 's consider the 10-question quiz . to do this , we just need to extend the fundamental counting principle a bit . we need to realize that there are two possible answers for each of the 10 questions . so the number of possible outcomes is 2 , times 2 , times 2 , times 2 , times 2 , times 2 , times 2 , times 2 , times 2 , times 2 . or , a shorter way to say that is 2 to the 10th power , which is equal to 1,024 . that means of all the ways you could write down your ts and fs , only one of the 1,024 ways would match the teacher 's answer key perfectly . so the probability of you getting a perfect score by guessing is only 1 out of 1,024 , or about a 10th of a percent . clearly , guessing is n't a good idea . in fact , what would be the most common score if you and all your friends were to always randomly guess at every question on a 10-question true/ false quiz ? well , not everyone would get exactly 5 out of 10 . but the average score , in the long run , would be 5 . in a situation like this , there are two possible outcomes : a question is right or wrong , and the probability of being right by guessing is always the same : 1/2 . to find the average number you would get right by guessing , you multiply the number of questions by the probability of getting the question right . here , that is 10 times 1/2 , or 5 . hopefully you study for quizzes , since it clearly does n't pay to guess . but at one point , you probably took a standardized test like the sat , and most people have to guess on a few questions . if there are 20 questions and five possible answers for each question , what is the probability you would get all 20 right by randomly guessing ? and what should you expect your score to be ? let 's use the ideas from before . first , since the probability of getting a question right by guessing is 1/5 , we would expect to get 1/5 of the 20 questions right . yikes - that 's only four questions ! are you thinking that the probability of getting all 20 questions correct is pretty small ? let 's find out just how small . do you recall the fundamental counting principle that was stated before ? with five possible outcomes for each question , we would multiply 5 times 5 times 5 times 5 times ... well , we would just use 5 as a factor 20 times , and 5 to the 20th power is 95 trillion , 365 billion , 431 million , 648 thousand , 625 . wow - that 's huge ! so the probability of getting all questions correct by randomly guessing is about 1 in 95 trillion .
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the fundamental counting principle states that if there are a possible outcomes for one event , and b possible outcomes for another event , then there are a times b ways to pair the outcomes . clearly this works for a two-question true/ false quiz . there are two different answers you could write for the first question , and two different answers you could write for the second question .
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what is the probability of getting a perfect score on a ten-question true-false quiz by randomly guessing ?
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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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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 .
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the papez circuit showed the link between what two cognitive abilities ?
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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 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 .
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correctly use the following words in a well-written , scientifically correct paragraph . be sure to clearly distinguish the differences between each of them and how they intertwine ! be sure to provide examples . species diversity , biological diversity , ecosystem diversity , genetic diversity .
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it 's a common saying that elephants never forget , but these magnificent animals are more than giant walking hard drives . the more we learn about elephants , the more it appears that their impressive memory is only one aspect of an incredible intelligence that makes them some of the most social , creative , and benevolent creatures on earth . unlike many proverbs , the one about elephant memory is scientifically accurate . elephants know every member in their herd , able to recognize as many as 30 companions by sight or smell . this is a great help when migrating or encountering other potentially hostile elephants . they also remember and distinguish particular cues that signal danger and can recall important locations long after their last visit . but it 's the memories unrelated to survival that are the most fascinating . elephants remember not only their herd companions but other creatures who have made a strong impression on them . in one case , two circus elephants that had briefly performed together rejoiced when crossing paths 23 years later . this recognition is n't limited to others of their species . elephants have also recognized humans they 've bonded with after decades apart . all of this shows that elephant memory goes beyond responses to stimuli . looking inside their heads , we can see why . the elephant boasts the largest brain of any land mammal , as well as an impressive encephalization quotient . this is the size of the brain relative to what we 'd expect for an animal 's body size , and the elephant 's eq is nearly as high as a chimpanzee 's . and despite the distant relation , convergent evolution has made it remarkably similar to the human brain , with as many neurons and synapses and a highly developed hippocampus and cerebral cortex . it is the hippocampus , strongly associated with emotion , that aids recollection by encoding important experiences into long-term memories . the ability to distinguish this importance makes elephant memory a complex and adaptable faculty beyond rote memorization . it 's what allows elephants who survived a drought in their youth to recognize its warning signs in adulthood , which is why clans with older matriarchs have higher survival rates . unfortunately , it 's also what makes elephants one of the few non-human animals to suffer from post-traumatic stress disorder . the cerebral cortex , on the other hand , enables problem solving , which elephants display in many creative ways . they also tackle problems cooperatively , sometimes even outwitting the researchers and manipulating their partners . and they 've grasped basic arithmetic , keeping track of the relative amounts of fruit in two baskets after multiple changes . the rare combination of memory and problem solving can explain some of elephants ' most clever behaviors , but it does n't explain some of the things we 're just beginning to learn about their mental lives . elephants communicate using everything from body signals and vocalizations , to infrasound rumbles that can be heard kilometers away . and their understanding of syntax suggests that they have their own language and grammar . this sense of language may even go beyond simple communication . elephants create art by carefully choosing and combining different colors and elements . they can also recognize twelve distinct tones of music and recreate melodies . and yes , there is an elephant band . but perhaps the most amazing thing about elephants is a capacity even more important than cleverness : their sense of empathy , altruism , and justice . elephants are the only non-human animals to mourn their dead , performing burial rituals and returning to visit graves . they have shown concern for other species , as well . one working elephant refused to set a log down into a hole where a dog was sleeping , while elephants encountering injured humans have sometimes stood guard and gently comforted them with their trunk . on the other hand , elephant attacks on human villages have usually occurred right after massive poachings or cullings , suggesting deliberate revenge . when we consider all this evidence , along with the fact that elephants are one of the few species who can recognize themselves in a mirror , it 's hard to escape the conclusion that they are conscious , intelligent , and emotional beings . unfortunately , humanity 's treatment of elephants does not reflect this , as they continue to suffer from habitat destruction in asia , ivory poaching in africa , and mistreatment in captivity worldwide . given what we now know about elephants and what they continue to teach us about animal intelligence , it is more important than ever to ensure that what the english poet john donne described as `` nature 's great masterpiece '' does not vanish from the world 's canvas .
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looking inside their heads , we can see why . the elephant boasts the largest brain of any land mammal , as well as an impressive encephalization quotient . this is the size of the brain relative to what we 'd expect for an animal 's body size , and the elephant 's eq is nearly as high as a chimpanzee 's . and despite the distant relation , convergent evolution has made it remarkably similar to the human brain , with as many neurons and synapses and a highly developed hippocampus and cerebral cortex .
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how is an elephant 's brain size related to its intelligence ?
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85 % of the matter in our universe is a mystery . we do n't know what it 's made of , which is why we call it dark matter . but we know it 's out there because we can observe its gravitational attraction on galaxies and other celestial objects . we 've yet to directly observe dark matter , but scientists theorize that we may actually be able to create it in the most powerful particle collider in the world . that 's the 27 kilometer-long large hadron collider , or lhc , in geneva , switzerland . so how would that work ? in the lhc , two proton beams move in opposite directions and are accelerated to near the speed of light . at four collision points , the beams cross and protons smash into each other . protons are made of much smaller components called quarks and gluons in most ordinary collisions , the two protons pass through each other without any significant outcome . however , in about one in a million collisions , two components hit each other so violently , that most of the collision energy is set free producing thousands of new particles . it 's only in these collisions that very massive particles , like the theorized dark matter , can be produced . the collision points are surrounded by detectors containing about 100 million sensors . like huge three-dimensional cameras , they gather information on those new particles , including their trajectory , electrical charge , and energy . once processed , the computers can depict a collision as an image . each line is the path of a different particle , and different types of particles are color-coded . data from the detectors allows scientists to determine what each of these particles is , things like photons and electrons . now , the detectors take snapshots of about a billion of these collisions per second to find signs of extremely rare massive particles . to add to the difficulty , the particles we 're looking for may be unstable and decay into more familiar particles before reaching the sensors . take , for example , the higgs boson , a long-theorized particle that was n't observed until 2012 . the odds of a given collision producing a higgs boson are about one in 10 billion , and it only lasts for a tiny fraction of a second before decaying . but scientists developed theoretical models to tell them what to look for . for the higgs , they thought it would sometimes decay into two photons . so they first examined only the high-energy events that included two photons . but there 's a problem here . there are innumerable particle interactions that can produce two random photons . so how do you separate out the higgs from everything else ? the answer is mass . the information gathered by the detectors allows the scientists to go a step back and determine the mass of whatever it was that produced two photons . they put that mass value into a graph and then repeat the process for all events with two photons . the vast majority of these events are just random photon observations , what scientists call background events . but when a higgs boson is produced and decays into two photons , the mass always comes out to be the same . therefore , the tell-tale sign of the higgs boson would be a little bump sitting on top of the background . it takes billions of observations before a bump like this can appear , and it 's only considered a meaningful result if that bump becomes significantly higher than the background . in the case of the higgs boson , the scientists at the lhc announced their groundbreaking result when there was only a one in 3 million chance this bump could have appeared by a statistical fluke . so back to the dark matter . if the lhc 's proton beams have enough energy to produce it , that 's probably an even rarer occurrence than the higgs boson . so it takes quadrillions of collisions combined with theoretical models to even start to look . that 's what the lhc is currently doing . by generating a mountain of data , we 're hoping to find more tiny bumps in graphs that will provide evidence for yet unknown particles , like dark matter . or maybe what we 'll find wo n't be dark matter , but something else that would reshape our understanding of how the universe works entirely . that 's part of the fun at this point . we have no idea what we 're going to find .
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so how would that work ? in the lhc , two proton beams move in opposite directions and are accelerated to near the speed of light . at four collision points , the beams cross and protons smash into each other .
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imagine an unknown particle is produced in proton-proton collisions in the lhc . what are the main steps until the discovery of this particle can be claimed ?
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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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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 .
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define the principle of utilitarianism , and explain how it applies to the trolley problem .
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magnesium is one of the lightest elements . it ’ s right at the beginning of the period table and , in fact , it ’ s the first of the light metals that you can actually use . lithium and sodium react violently with water so you can ’ t really use them as a metal and beryllium is fantastically poisonous so unless you are using it in the lab where you can be sure that nobody is going to touch it , it ’ s useless , so magnesium is the lightest metal you can use . so , for example , if you are trying to make mobile phones that are really light , then you can make the frame of the mobile phone out of magnesium . you can use it for laptops . there is a professor in germany , who has promised to send me a laptop frame made of magnesium , but it hasn ’ t arrived yet . so another classroom classic . normally comes along in chemistry lesson number three i guess , time to combust a reactive metal in the air , so the reactive metal we are going to look at is magnesium . the other thing that is good about magnesium is that there is a lot of magnesium about in the world , so it is not an element that is difficult to get . if you look at this periodic table here , which is from barcelona so it is in catalan , the areas of these , each element are approximately the abundance in the world . some of the rarer elements have a slightly bigger squares than they should do so you can read the letters , but you see magnesium here is pretty large , so magnesium and sodium are pretty common , beryllium is much less common , and lithium is even less common than that , so there is lots of magnesium . magnesium is very light , it is very reactive , very pliable metal , it is very nice , it is easily alloyed with things like aluminium and other light metals to make very strong , very robust materials . used in construction , it ’ s used in high-performance components of cars . when i was a child when we got , had indigestion , we were given ‘ milk of magnesia ’ . magnesium oxide in water which came in these really nice blue bottles , sort of white looking liquid , didn ’ t taste very nice , but it was meant to be good for you , i am not sure if it was . it is used in the hulls of ships , you know like , warships , things like that , so incredibly strong , incredibly light but incredibly reactive if you give it enough energy . so we are going to combust it in the oxygen and see what happens . magnesium as you know , burns , and one of the ways that magnesium used to be used was for photographic flashlights , and you use bulbs like these which contain magnesium , inside a bulb filled with oxygen . and for each photograph you had to put this on the top of the camera . so i ’ ve got one here that i have taken out . so , if you look at it , so much heat has been produced by this tiny amount of magnesium , that it has melted the glass . so , let ’ s see what happens when we light it . you can see , really fierce bright white light that classical glow , everyone has seen this in the chemistry lab at school , fantastic reaction . it is one of the few metals which is meant to burn in nitrogen . in theory you can take a piece of magnesium , set fire to it in air so its burning well and then plunge it into nitrogen gas , and it should continue burning . i have tried this experiment lots of times and it ’ s never worked . in fact for 25 years i demonstrated this experiment to my lecture class when i was talking about nitrogen , and every time , it didn ’ t work , and the students thought , the poor professor , he has been made a fool of , it hasn ’ t worked and they didn ’ t know that it never worked and i would have been more surprised if it had done , but it taught them a bit about the chemistry of nitrogen and magnesium . why did you keep doing it if it never worked ? because it is a really good experiment , because it got such a good reaction from the audience . because it went wrong ? yes ! you were playing the fool on purpose ? yes ! so this is magnesium metal , but the magnesium metal here is not the ribbon which we normally see in perhaps , scientific labs or perhaps in school labs , this is a very , very fine powder of magnesium , so what we are going to do in a moment is bring on a really very powerful torch , a gas flame and we are going to see what happens when we sprinkle a little of this material into the flame . magnesium is also very important in all our lives , because magnesium is found in the green pigments in the leaves of all plants , in chlorophyll . chlorophyll is an organic molecule , carbon , hydrogen and nitrogen and in the middle there is an atom of magnesium , and it is chlorophyll which catches the sunlight and transfers it eventually to cause the reaction of carbon dioxide and water to make all the sugars and other things in the plant . if that didn ’ t happen none of us would be alive , because we all rely either directly or indirectly on plants , to give us the energy to live . i don ’ t understand completely the mechanism of photosynthesis , because the energy that is absorbed by one molecule , is transferred to another and another one as it were along a chain , but the magnesium is very important , if you don ’ t have magnesium there it is not nearly as efficient . let ’ s light it again .
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used in construction , it ’ s used in high-performance components of cars . when i was a child when we got , had indigestion , we were given ‘ milk of magnesia ’ . magnesium oxide in water which came in these really nice blue bottles , sort of white looking liquid , didn ’ t taste very nice , but it was meant to be good for you , i am not sure if it was .
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what was the composition of “ milk of magnesia ” that was given to the professor as a child when he had indigestion ?
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what if you could absorb another organism and take on its abilities ? imagine you swallowed a small bird and suddenly gained the ability to fly . or if you engulfed a cobra and were then able to spit poisonous venom from your teeth . throughout the history of life , specifically during the evolution of complex eukaryotic cells , things like this happened all the time . one organism absorbed another , and they united to become a new organism with the combined abilities of both . we think that around 2 billion years ago , the only living organisms on earth were prokaryotes , single-celled organisms lacking membrane-bound organelles . let 's look closely at just three of them . one was a big , simple blob-like cell with the ability to absorb things by wrapping its cell membrane around them . another was a bacterial cell that converted solar energy into sugar molecules through photosynthesis . a third used oxygen gas to break down materials like sugar and release its energy into a form useful for life activities . the blob cells would occasionally absorb the little photosynthetic bacteria . these bacteria then lived inside the blob and divided like they always had , but their existence became linked . if you stumbled upon this living arrangement , you might just think that the whole thing was one organism , that the green photosynthetic bacteria were just a part of the blob that performed one of its life functions , just like your heart is a part of you that performs the function of pumping your blood . this process of cells living together is called endosymbiosis , one organism living inside another . but the endosymbiosis did n't stop there . what would happen if the other bacteria moved in , too ? now the cells of this species started becoming highly complex . they were big and full of intricate structures that we call chloroplasts and mitochondria . these structures work together to harness sunlight , make sugar , and break down that sugar using the oxygen that right around this time started to appear in the earth 's atmosphere . organisms absorbing other organisms was one way species adapted to the changing environmental conditions of their surroundings . this little story highlights what biologists call the endosymbiotic theory , the current best explanation of how complex cells evolved . there 's a lot of evidence that supports this theory , but let 's look at three main pieces . first , the chloroplasts and mitochondria in our cells multiply the very same way as those ancient bacteria , which are still around , by the way . in fact , if you destroy these structures in a cell , no new ones will appear . the cell ca n't make them . they can only make more of themselves . second piece of evidence . chloroplasts and mitochondria both contain their own dna and ribosomes . their dna has a circular structure that is strikingly similar to the dna of the ancient bacteria , and it also contains many similar genes . the ribosomes , or protein assembly machines of chloroplasts and mitochondria , also have the same structure as ribosomes of ancient bacteria , but are different from the ribosomes hanging around the rest of eukaryotic cell . lastly , think about the membranes involved in the engulfing process . chloroplasts and mitochondria both have two membranes surrounding them , an inner and outer membrane . their inner membrane contains some particular lipids and proteins that are not present in the outer membrane . why is that significant ? because their outer membrane used to belong to the blob cell . when they were engulfed in the endosymbiosis process , they got wrapped up in that membrane and kept their own as their inner one . surely enough , those same lipids and proteins are found on the membranes of the ancient bacteria . biologists now use this theory to explain the origin of the vast variety of eukaryotic organisms . take the green algae that grow on the walls of swimming pools . a larger eukaryotic cell with spinning tail structures , or flagella , at some point absorbed algae like these to form what we now call euglena . euglena can perform photosynthesis , break down sugar using oxygen , and swim around pond water . and as the theory would predict , the chloroplasts in these euglena have three membranes since they had two before being engulfed . the absorbing process of endosymbiotic theory allowed organisms to combine powerful abilities to become better adapted to life on earth . the results were species capable of much more than when they were separate organisms , and this was an evolutionary leap that lead to the microorganisms , plants , and animals we observe on the planet today .
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what would happen if the other bacteria moved in , too ? now the cells of this species started becoming highly complex . they were big and full of intricate structures that we call chloroplasts and mitochondria .
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what types of biological abilities can be combined to create more capable , more complex cells ?
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