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while touring the remains of ancient alexandria , egypt , there are a few things that present-day explorers should look for . first , as you travel along the great harbor , keep your eyes open for large columns and statues . across the bay to your left is the island where the great lighthouse once stood . and as you make your way through the palaces of the royal quarter and reach the area where the library of alexandria once stood , keep your eyes open for sharks . because if you visit this section of alexandria , you 'll be fifteen feet deep in the mediterranean sea . though people are most familiar with plato 's fictional atlantis , many real underwater cities actually exist . places like alexandria , port royal , jamaica , and pavlopetri , greece . sunken cities are studied by scientists to help us understand the lives of our ancestors , the dynamic nature of our planet , and the impact of each on the other . water is essential for life , food sources , and transport , so many cities have been built along coast lines and river banks . however , these benefits also come with risks because natural forces that can sink a city are at their doorstep . take , for instance , an earthquake . june 7 , 1692 seemed like a normal morning in port royal , jamaica , then one of the richest ports in the world , but when a massive earthquake struck , two-thirds of port royal immediately sank to its rooftops . today , many buildings and elements of everyday life remain surprisingly intact on the sea floor , frozen in time . that includes a 300-year-old pocket watch that stopped at 11:43 , the moment port royal slipped beneath the carribean . and during the winter of 373 bce , the greek city of helike was struck by an earthquake so strong that it liquefied the sandy ground upon which the city was built . minutes later , a tsunami struck the city , and helike and its inhabitants sunk downwards into the mediterranean sea . centuries later , roman tourists would sail on the lagoon that formed and peer down at the city 's remains . earthquakes are sudden , unpredictable disasters that have drowned cities in an instant . luckily , however , throughout history , the majority of sunken cities were not submerged by a single cataclysmic event , but by a combination of more gradual processes . for instance , pavlopetri , the oldest known sunken city , was built on the southern coastline of greece 5,000 years ago . it 's an example of a city that was submerged due to what is called isostatic sea level change . 18,000 years ago when the ice age ended , glaciers began melting and the sea level rose globally until about 5,000 years ago . isostatic sea level change is n't caused by that melt water , but rather the earth 's crust slowly springing back from the released weight of the glaciers , making some places rise , and others sink . the ground around pavlopetri is still sinking at an average rate of a millimeter per year . but the ancient inhabitants were able to move gradually inland over several generations before they finally abandoned the city about 3,000 years ago . today , divers swim over the streets of pavlopetri and peer through ancient door jams into the foundations of houses and community buildings . they learn about the people who lived there by observing what they left behind . natural geological events , such as earthquakes and tsunamis , will continue to shape our continents , just as they have for millions of years . as increased global warming melts our polar ice caps at accelerated rates and sea levels rise , we will be forced to adapt , like pavlopetri 's inhabitants . undoubtedly , over the coming centuries , some of the coastal areas that we live in today will eventually be claimed by the water , too - cities like venice , new orleans , amsterdam , miami , and tokyo . imagine what future civilizations will learn about us as they swim around the ancient ruins of the cities that we live in today .
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for instance , pavlopetri , the oldest known sunken city , was built on the southern coastline of greece 5,000 years ago . it 's an example of a city that was submerged due to what is called isostatic sea level change . 18,000 years ago when the ice age ended , glaciers began melting and the sea level rose globally until about 5,000 years ago .
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explain how multiple natural phenomena ( earthquake , tsunami , liquefaction , sea level change ) can combine to the submergence of a city .
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slavery , the treatment of human beings as property , deprived of personal rights , has occurred in many forms throughout the world . but one institution stands out for both its global scale and its lasting legacy . the atlantic slave trade , occurring from the late 15th to the mid 19th century and spanning three continents , forcibly brought more than 10 million africans to the americas . the impact it would leave affected not only these slaves and their descendants , but the economies and histories of large parts of the world . there had been centuries of contact between europe and africa via the mediterranean . but the atlantic slave trade began in the late 1400s with portuguese colonies in west africa , and spanish settlement of the americas shortly after . the crops grown in the new colonies , sugar cane , tobacco , and cotton , were labor intensive , and there were not enough settlers or indentured servants to cultivate all the new land . american natives were enslaved , but many died from new diseases , while others effectively resisted . and so to meet the massive demand for labor , the europeans looked to africa . african slavery had existed for centuries in various forms . some slaves were indentured servants , with a limited term and the chance to buy one 's freedom . others were more like european serfs . in some societies , slaves could be part of a master 's family , own land , and even rise to positions of power . but when white captains came offering manufactured goods , weapons , and rum for slaves , african kings and merchants had little reason to hesitate . they viewed the people they sold not as fellow africans but criminals , debtors , or prisoners of war from rival tribes . by selling them , kings enriched their own realms , and strengthened them against neighboring enemies . african kingdoms prospered from the slave trade , but meeting the european 's massive demand created intense competition . slavery replaced other criminal sentences , and capturing slaves became a motivation for war , rather than its result . to defend themselves from slave raids , neighboring kingdoms needed european firearms , which they also bought with slaves . the slave trade had become an arms race , altering societies and economies across the continent . as for the slaves themselves , they faced unimaginable brutality . after being marched to slave forts on the coast , shaved to prevent lice , and branded , they were loaded onto ships bound for the americas . about 20 % of them would never see land again . most captains of the day were tight packers , cramming as many men as possible below deck . while the lack of sanitation caused many to die of disease , and others were thrown overboard for being sick , or as discipline , the captain 's ensured their profits by cutting off slave 's ears as proof of purchase . some captives took matters into their own hands . many inland africans had never seen whites before , and thought them to be cannibals , constantly taking people away and returning for more . afraid of being eaten , or just to avoid further suffering , they committed suicide or starved themselves , believing that in death , their souls would return home . those who survived were completley dehumanized , treated as mere cargo . women and children were kept above deck and abused by the crew , while the men were made to perform dances in order to keep them exercised and curb rebellion . what happened to those africans who reached the new world and how the legacy of slavery still affects their descendants today is fairly well known . but what is not often discussed is the effect that the atlantic slave trade had on africa 's future . not only did the continent lose tens of millions of its able-bodied population , but because most of the slaves taken were men , the long-term demographic effect was even greater . when the slave trade was finally outlawed in the americas and europe , the african kingdoms whose economies it had come to dominate collapsed , leaving them open to conquest and colonization . and the increased competition and influx of european weapons fueled warfare and instability that continues to this day . the atlantic slave trade also contributed to the development of racist ideology . most african slavery had no deeper reason than legal punishment or intertribal warfare , but the europeans who preached a universal religion , and who had long ago outlawed enslaving fellow christians , needed justification for a practice so obviously at odds with their ideals of equality . so they claimed that africans were biologically inferior and destined to be slaves , making great efforts to justify this theory . thus , slavery in europe and the americas acquired a racial basis , making it impossible for slaves and their future descendants to attain equal status in society . in all of these ways , the atlantic slave trade was an injustice on a massive scale whose impact has continued long after its abolition .
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to defend themselves from slave raids , neighboring kingdoms needed european firearms , which they also bought with slaves . the slave trade had become an arms race , altering societies and economies across the continent . as for the slaves themselves , they faced unimaginable brutality .
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explain how tribalism created competition amongst tribes in africa ? in other words , how did the slave trade turn into an arms race between tribes , where the best defense was a good offense ?
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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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explain how self-assembly might remove the need for humans to complete repetitive , mundane tasks .
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imagine the brain could reboot , updating its withered and damaged cells with new , improved units . that may sound like science fiction , but it 's a potential reality scientists are investigating right now . will our brains one day be able to self-repair ? it 's well known that embryonic cells in our young developing brains produce new neurons , the microscopic units that make up the brain 's tissue . those newly generated neurons migrate to various parts of the developing brain , making it self-organize into different structures . but until recently , scientists thought cell production came to an abrupt halt soon after this initial growth , leading them to conclude that neurological diseases , like alzheimer 's and parkinson 's , and damaging events , like strokes , are irreversible . but a series of recent discoveries has revealed that adult brains actually do continue to produce new cells in at least three specialized locations . this process , known as neurogenesis , involves dedicated brain cells , called neural stem cells and progenitor cells , which manufacture new neurons or replace the old ones . the three regions where neurogenesis has been discovered are the dentate gyrus , associated with learning and memory , the subventricular zone , which may supply neurons to the olfactory bulb for communication between the nose and brain , and the striatum , which helps manage movement . scientists do n't yet have a good grasp on exactly what role neurogenesis plays in any of these regions , or why they have this ability that 's absent from the rest of the brain , but the mere presence of a mechanism to grown new neurons in the adult brain opens up an amazing possibility . could we harness that mechanism to get the brain to heal its scars similar to how new skin grows to patch up a wound , or a broken bone stitches itself back together ? so here 's where we stand . certain proteins and other small molecules that mimick those proteins can be administered to the brain to make neural stem cells and progenitor cells produce more neurons in those three locations . this technique still needs improvement so that the cells reproduce more efficiently and more cells survive . but research shows that progenitor cells from these areas can actually migrate to places where injury has occurred and give rise to new neurons there . and another promising possible approach is to transplant healthy human neural stem cells , which are cultured in a laboratory , to injured tissue , like we can do with skin . scientists are currently experimenting to determine whether transplanted donor cells can divide , differentiate and successfully give rise to new neurons in a damaged brain . they 've also discovered that we might be able to teach other kinds of brain cells , such as astrocytes or oligodendrocytes to behave like neural stem cells and start generating neurons , too . so , a couple of decades from now will our brains be able to self-repair ? we ca n't say for sure , but that has become one of the major goals of regenerative medicine . the human brain has 100 billion neurons and we 're still figuring out the wiring behind this huge biological motherboard . but everyday , research on neurogenesis brings us closer to that reboot switch .
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and another promising possible approach is to transplant healthy human neural stem cells , which are cultured in a laboratory , to injured tissue , like we can do with skin . scientists are currently experimenting to determine whether transplanted donor cells can divide , differentiate and successfully give rise to new neurons in a damaged brain . they 've also discovered that we might be able to teach other kinds of brain cells , such as astrocytes or oligodendrocytes to behave like neural stem cells and start generating neurons , too . so , a couple of decades from now will our brains be able to self-repair ?
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what would be the advantage of generating new neurons from astrocytes or oligodendrocytes within the brain instead of using donor cell transplantation ?
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we live in a society obsessed with music . we use music to worship , tell stories , to celebrate , to work , exercise , declare our love and sometimes our hatred , and , arguably most importantly , to dance . and , of course , we play music ourselves because , well , it 's a pleasant thing to do . thousands of years ago in ancient greece , when it came to music , things were n't much different . they might have had lyres and tunics instead of mp3 players and jeans , but the ancient greeks were just as obsessed with music as we are today . in fact , music was such an important part of ancient greek society that it makes us seem tame by comparison . to really understand just how integral music was to the ancient greeks , let 's begin by acquainting ourselves with a bit of their mythology . in ancient greek mythology , it was believed that human creativity was the result of divine inspiration from a group of goddesses known as the muses . while scholars have argued over the years that there are anything between 3 and 13 muses , the standard number accepted today is 9 . each muse oversees her own specific area of artistic expertise , ranging from song and dance to history and astronomy . it might seem strange to categorize history and astronomy as creative pursuits , but the ancient greeks saw these disciplines as more than just school subjects . these were the hallmarks of civilization in what , to their eyes , was a pretty barbaric world . an educated , civilized person was expected to be proficient in all aspects of creative thought inspired by the muses , and the common medium through which these disciplines were taught , studied , and disseminated was music . you see , it 's no coincidence that the word muse is very similar to the word music . it 's where the word originates . poetry , be it a love poem or an epic poem about a dragon-slaying hero , was sung with a musical accompaniment . dancing and singing , obviously , were accompanied by music . theater was always a combination of spoken word and music . history was recounted through song . even the study of astronomy was linked to the same physical principles as musical harmony , such as the belief held by many greek thinkers that each of the planets and stars created their own unique sound as they traveled through the cosmos , thrumming like an enormous guitar string light-years long . however , music pervaded more aspects of their lives than just education . ancient greeks considered music to be the basis for understanding the fundamental interconnectedness of all things in the universe . this concept of connectivity is known as harmonia , and it 's where we get the word harmony . music was used as a form of medicine to treat illnesses and physical complaints , as a vital accompaniment to sporting contests , and as a means to keep workers in time as they toiled away on monotonous or menial tasks . one of the most important applications of music in ancient greek society is found in the belief that music can affect a person 's ethos . a word we still use today , ethos is a person 's guiding beliefs or personal ethics , the way that one behaves towards oneself and others . the greek philosopher plato , one of the most famous and influential greek thinkers of the time , asserted that music had a direct effect on a person 's ethos . certain kinds of music could incite a person to violence while others could placate a person into a benign , unthinking stupor . according to plato , only very specific types of music were beneficial to a person 's ethos . one should only listen to music that promotes intelligence , self-discipline , and courage , and all other kinds of music must be avoided . furthermore , plato fervently denounced any music that deviated from established musical conventions , fearing that doing so would lead to the degradation of the standards of civilization , the corruption of youth , and eventually complete and utter anarchy . while plato 's fears can seem extreme , this argument has appeared in modern times to condemn musical trends such as jazz or punk or rap . what do you think plato would say about the music you listen to ? is it beneficial to your ethos , or will it degenerate you into a gibbering , amoral barbarian ?
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in ancient greek mythology , it was believed that human creativity was the result of divine inspiration from a group of goddesses known as the muses . while scholars have argued over the years that there are anything between 3 and 13 muses , the standard number accepted today is 9 . each muse oversees her own specific area of artistic expertise , ranging from song and dance to history and astronomy .
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modern scholars generally accept that there are _____ muses .
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some superheroes can grow to the size of a building at will . that 's very intimidating ! but a scientist must ask where the extra material is coming from . the law of conservation of mass implies that mass can neither be created nor destroyed , which means that our hero 's mass will not change just because his size changes . for instance , when we bake a fluffy sponge cake , even though the resulting delicious treat is much bigger in size than the cake batter that went into the oven , the weight of the cake batter should still equal the weight of the cake plus the moisture that has evaporated . in a chemical equation , molecules rearrange to make new compounds , but all the components should still be accounted for . when our hero expands from 6 feet tall to 18 feet tall , his height triples . galileo 's square cube law says his weight will be 27 - 3 times 3 times 3 equals 27 - times his regular weight since he has to expand in all three dimensions . so , when our superhero transforms into a giant , we are dealing with two possibilities . our hero towering at 18 feet still only weighs 200 pounds , the original weight in this human form . now , option two , our hero weighs 5,400 pounds - 200 pounds times 27 equals 5,400 pounds - when he is 18 feet tall , which means he also weighs 5,400 pounds when he is 6 feet tall . nobody can get in the same elevator with him without the alarm going off . now , option two seems a little more scientifically plausible , but it begs the question , how does he ever walk through the park without sinking into the ground since the pressure he is exerting on the soil is calculated by his mass divided by the area of the bottom of his feet ? and what kind of super socks and super shoes is he putting on his feet to withstand all the friction that results from dragging his 5,400 pound body against the road when he runs ? and can he even run ? and i wo n't even ask how he finds pants flexible enough to withstand the expansion . now , let 's explore the density of the two options mentioned above . density is defined as mass divided by volume . the human body is made out of bones and flesh , which has a relatively set density . in option one , if the hero weighs 200 pounds all the time , then he would be bones and flesh at normal size . when he expands to a bigger size while still weighing 200 pounds , he essentially turns himself into a giant , fluffy teddy bear . in option two , if the hero weighs 5,400 pounds all the time , then he would be bones and flesh at 18 feet with 5,400 pounds of weight supported by two legs . the weight would be exerted on the leg bones at different angles as he moves . bones , while hard , are not malleable , meaning they do not bend , so they break easily . the tendons would also be at risk of tearing . tall buildings stay standing because they have steel frames and do not run and jump around in the jungle . our hero , on the other hand , one landing at a bad angle and he 's down . assuming his bodily function is the same as any mammal 's , his heart would need to pump a large amount of blood throughout his body to provide enough oxygen for him to move 5,400 pounds of body weight around . this would take tremendous energy , which he would need to provide by consuming 27 times 3,000 calories of food every day . now , that is roughly 150 big macs . 27 times 3,000 calculated equals 81,000 calculated slash 550 calories equals 147 . he would n't have time to fight crime because he would be eating all the time and working a 9-to-5 job in order to afford all the food he eats . and what about superheroes who can turn their bodies into rocks or sand ? well , everything on earth is made out of elements . and what defines each element is the number of protons in the nucleus . that is how our periodic table is organized . hydrogen has one proton , helium , two protons , lithium , three protons , and so on . the primary component of the most common form of sand is silicon dioxide . meanwhile , the human body consists of 65 % oxygen , 18 % carbon , 10 % hydrogen , and 7 % of various other elements including 0.002 % of silicon . in a chemical reaction , the elements recombine to make new compounds . so , where is he getting all this silicon necessary to make the sand ? sure , we can alter elements by nuclear fusion or nuclear fission . however , nuclear fusion requires so much heat , the only natural occurrence of this process is in stars . in order to utilize fusion in a short amount of time , the temperature of the area needs to be hotter than the sun . every innocent bystander will be burned to a crisp . rapid nuclear fission is not any better since it often results in many radioactive particles . our hero would become a walking , talking nuclear power plant , ultimately harming every person he tries to save . and do you really want the heat of the sun or a radioactive nuclear plant inside of your body ? now , which superpower physics lesson will you explore next ? shifting body size and content , super speed , flight , super strength , immortality , and invisibility .
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he would n't have time to fight crime because he would be eating all the time and working a 9-to-5 job in order to afford all the food he eats . and what about superheroes who can turn their bodies into rocks or sand ? well , everything on earth is made out of elements .
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why is it unreasonable for a person to be able to rearrange the elements in his body and turn it into sand ?
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in 1996 , 56 volunteers took part in a study to test a new painkiller called trivaricaine . on each subject , one index finger was covered in the new painkiller while the other remained untouched . then , both were squeezed in painful clamps . the subjects reported that the treated finger hurt less than the untreated one . this should n't be surprising , except trivaricaine was n't actually a painkiller , just a fake concotion with no pain-easing properties at all . what made the students so sure this dummy drug had worked ? the answer lies in the placebo effect , an unexplained phenomenon wherein drugs , treatments , and therapies that are n't supposed to have an effect , and are often fake , miraculously make people feel better . doctors have used the term placebo since the 1700s when they realized the power of fake drugs to improve people 's symptoms . these were administered when proper drugs were n't available , or if someone imagined they were ill . in fact , the word placebo means `` i shall please '' in latin , hinting at a history of placating troubled patients . placebos had to mimic the real treatments in order to be convincing , so they took the form of sugar pills , water-filled injections , and even sham surgeries . soon , doctors realized that duping people in this way had another use : in clinical trials . by the 1950s , researchers were using placebos as a standard tool to test new treatments . to evaluate a new drug , for instance , half the patients in a trial might receive the real pill . the other half would get a placebo that looked the same . since patients would n't know whether they 'd received the real thing or a dud , the results would n't be biased , researchers believed . then , if the new drug showed a significant benefit compared to the placebo , it was proved effective . nowadays , it 's less common to use placebos this way because of ethical concerns . if it 's possible to compare a new drug against an older version , or another existing drug , that 's preferable to simply giving someone no treatment at all , especially if they have a serious ailment . in these cases , placebos are often used as a control to fine-tune the trial so that the effects of the new versus the old or alternative drug can be precisely compared . but of course , we know the placebos exert their own influence , too . thanks to the placebo effect , patients have experienced relief from a range of ailments , including heart problems , asthma , and severe pain , even though all they 'd received was a fake drug or sham surgery . we 're still trying to understand how . some believe that instead of being real , the placebo effect is merely confused with other factors , like patients trying to please doctors by falsely reporting improvements . on the other hand , researchers think that if a person believes a fake treatment is real , their expectations of recovery actually do trigger physiological factors that improve their symptoms . placebos seem to be capable of causing measurable change in blood pressure , heart rate , and the release of pain-reducing chemicals , like endorphins . that explains why subjects in pain studies often say placebos ease their discomfort . placebos may even reduce levels of stress hormones , like adrenaline , which can slow the harmful effects of an ailment . so should n't we celebrate the placebo 's bizarre benefits ? not necessarily . if somebody believes a fake treatment has cured them , they may miss out on drugs or therapies that are proven to work . plus , the positive effects may fade over time , and often do . placebos also cloud clinical results , making scientists even more motivated to discover how they wield such power over us . despite everything we know about the human body , there are still some strange and enduring mysteries , like the placebo effect . so what other undiscovered marvels might we contain ? it 's easy to investigate the world around us and forget that one of its most fascinating subjects lies right behind our eyes .
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in 1996 , 56 volunteers took part in a study to test a new painkiller called trivaricaine . on each subject , one index finger was covered in the new painkiller while the other remained untouched .
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trivaricaine was a real , effective painkiller .
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today when people complain about the state of american politics , they often mention the dominance of the democratic and republican parties , or the sharp split between red and blue states . but while it may seem like both of these things have been around forever , the situation looked quite different in 1850 , with the republican party not yet existing , and support for the dominant democrats and whigs cutting across geographic divides . the collapse of this second party system was at the center of increasing regional tensions that would lead to the birth of the republican party , the rise of abraham lincoln as its leader , and a civil war that would claim over half a million lives . and if this collapse could be blamed on a single event , it would be the kansas-nebraska act of 1854 . the story starts with the missouri compromise of 1820 . to balance the number of slave states and free states in the union , it allowed slavery in the newly admitted state of missouri , while making it off limits in the remaining federally administered louisiana territory . but compromises tend to last only as long as they 're convenient , and by the early 1850s , a tenacious democratic senator from illionis named stephen a. douglas found its terms very inconvenient . as an advocate of western expansion , he promoted constructing a transcontinental railroad across the northern plains with an eastern terminus in chicago , where he happened to own real estate . for his proposal to succeed , douglas felt that the territories through which the railroad passed , would have to be formally organized , which required the support of southern politicians . he was also a believer in popular sovereignty , arguing that the status of slavery in a territory should be decided by its residents rather than congress . so douglas introduced a bill designed to kill two birds with one stone . it would divide the large chunk of incorporated land into two new organized territories : nebraska and kansas , each of which would be open to slavery if the population voted to allow it . while douglas and his southern supporters tried to frame the bill as protecting the political rights of settlers , horrified northerners recognized it as repealing the 34-year-old missouri compromise and feared that its supporters ' ultimate goal was to extend slavery to the entire nation . congress was able to pass the kansas-nebraska act , but at the huge cost of bitterly dividing the nation , with 91 % of the opposition coming from northerners . in the house of representatives , politicians traded insults and brandished weapons until a sargent at arms restored order . president pierce signed the bill into law amidst a storm of protest , while georgia 's alexander stephens , future confederate vice president , hailed the act 's passage as , `` glory enough for one day . '' the new york tribune reported , `` the unanimous sentiment of the north is indignant resistance . '' douglas even admitted that he could travel from washington d.c. to chicago by the light of his own burning effigies . the political consequences of the kansas-nebraska act were stunning . previously , both whigs and democrats had included northern and southern lawmakers united around various issues , but now slavery became a dividing factor that could not be ignored . congressmen from both parties spoke out against the act , including an illinois whig named abraham lincoln , denouncing `` the monstrous injustice of slavery '' in an 1854 speech . by this time the whigs had all but ceased to exist , irreparably split between their northern and southern factions . in the same year , the new republican party was founded by the anti-slavery elements from both existing parties . although lincoln still ran for senate as a whig in 1854 , he was an early supporter of the new party , and helped to recruit others to its cause . meanwhile the democratic party was shaken when events in the newly formed kansas territory revealed the violent consequences of popular sovereignty . advertisements appeared across the north imploring people to emigrate to kansas to stem the advance of slavery . the south answered with border ruffians , pro-slavery missourians who crossed state lines to vote in fraudulent elections and raid anti-slavery settlements . one northern abolitionist , john brown , became notorious following the pottawatomie massacre of 1856 when he and his sons hacked to death five pro-slavery farmers with broad swords . in the end , more than 50 people died in bleeding kansas . while nominally still a national party , douglas 's democrats were increasingly divided along sectional lines , and many northern members left to join the republicans . abraham lincoln finally took up the republican party banner in 1856 and never looked back . that year , john c. fremont , the first republican presidential candidate , lost to democrat , james buchanan , but garnered 33 % of the popular vote all from northern states . two years later , lincoln challenged douglas for his illinois senate seat , and although he lost that contest , it elevated his status among republicans . lincoln would finally be vindicated in 1860 , when he was elected president of the united states , defeating in his own home state , a certain northern democrat , who was finally undone by the disastrous aftermath of the law he had masterminded . americans today continue to debate whether the civil war was inevitable , but there is no doubt that the kansas-nebraska act made the ghastly conflict much more likely . and for that reason , it should be remembered as one of the most consequential pieces of legislation in american history .
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the story starts with the missouri compromise of 1820 . to balance the number of slave states and free states in the union , it allowed slavery in the newly admitted state of missouri , while making it off limits in the remaining federally administered louisiana territory . but compromises tend to last only as long as they 're convenient , and by the early 1850s , a tenacious democratic senator from illionis named stephen a. douglas found its terms very inconvenient .
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before 1854 , slavery was banned from remaining louisiana purchase territory under the terms of ________ .
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me , myself , and i . you may be tempted to use these words interchangeably because they all refer to the same thing , but in fact , each one has a specific role in a sentence . `` i '' is a subject pronoun , `` me '' is an object pronoun , and `` myself '' is a reflexive or intensive pronoun . so what does that reveal about where each word belongs ? let 's start with the difference between subject and object . imagine the subject as the actor in a sentence and the object as the word that is acted upon . `` i invited her but she invited me . '' the object can also be the object of a preposition . `` she danced around me , while he shimmied up to me . '' in some languages , like latin and russian , most nouns have different forms that distinguish subjects from objects . however , in english , that 's only true of pronouns . but so long as you know how to distinguish subjects from objects , you can figure out what belongs where . and when you encounter a more complicated sentence , say one that involves multiple subjects or objects , and you 're not sure whether to use `` i '' or `` me , '' just temporarily eliminate the other person , and once again distinguish subject from object . here 's another . you would n't say , `` me heard gossip , '' but sub in `` i '' and you 're good to go . then what about `` myself ? '' this grand character is often substituted for `` me '' and `` i '' because it seems more impressive . `` please tell jack or myself '' may sound elegant , but in fact , `` me '' is the right pronoun here . so where should you use `` myself '' ? in its function as a reflexive pronoun , `` myself '' only works if it 's the object of a sentence whose subject is `` i . '' `` i consider myself the most important pronoun at this year 's party . '' `` myself '' can also add emphasis as an intensive pronoun . `` i , myself , have heard others agree . '' the sentence works without it , but that extra pronoun gives it oomph . to check if `` myself '' belongs in a sentence , simply ensure that there 's also an `` i '' that it 's reflecting or intensifying . so that 's `` me , '' `` myself , '' and `` i , '' ever ready to represent you , yourself , and you .
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you may be tempted to use these words interchangeably because they all refer to the same thing , but in fact , each one has a specific role in a sentence . `` i '' is a subject pronoun , `` me '' is an object pronoun , and `` myself '' is a reflexive or intensive pronoun . so what does that reveal about where each word belongs ?
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'myself ' can be an intensive pronoun and its job in that role is to :
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in this short video , we 're going to show you how we constructed and animated a pop-up book to explain earth 's tectonic plates . the supercontinent pangaea broke apart 200,000,000 years ago , but the pieces have n't stopped shifting . although with animation we can show this movement easily with drawings , we thought it 'd be more interesting to depict gigantic sliding slabs of rock using a tangible object that also moves and shifts . and the pop-up book idea was born . ( music ) to make your own pop-up book , you 'll need some basic paper tools , such as scissors , an x-acto knife , glue , double-sided scotch tape , a ruler , a bone folder or other creasing tool , and , of course , some paper . for this lesson , we first determined the visual style by making illustrations and deciding on the overall design , colors , shapes and elements we wanted on each page , or spread . you can have more detailed illustrations , but we wanted to illustrate this lesson simply by playing with shapes and colors . when you visualize your pop-up and choose a visual style , you will want to make a bunch of good old pencil sketches on paper and plan each movement for each spread . plan as much as you can : all the basic shapes and how they connect and how you want them to move , which parts you want to pop-up first . challenge yourself , and explore multiple possibilities of how your main element on the spread can pop up . for the next step , make a mock-up spread and see if your masterful paper engineering ideas translate from a sketch to the actual prototype . instead of using fancy paper , start with the cheap stuff and allow yourself to make mistakes and adjustments . this prototype lets you see how your preliminary sketches will come to life . you will want to first draw all individual parts on a single sheet , including all your main pieces , all the supporting pieces and the folds . you may be surprised that there are only two types of folds that can make your elements pop up the way you want : a step fold and a v-fold . here , you can see how we used a step fold to make each layer of the earth step out . then , cut all your individual elements and assemble using glue or double-sided scotch tape . ( music ) through trial and error , make sure that all the elements , shapes and placements are moving the way you imagined , and that they fold properly when closed and opened . ( music ) once your prototype is tested and complete , you can proceed to making the final product in color . draw or paint on your main pop-up elements as you see fit . for this lesson , we decided to just play with simple shapes in different colors to create the world of shifting continents we imagined . ( music ) when we were planning each spread , we knew we wanted some elements to move independently of the typical pop-up book using slight manipulations and animations . we had to plan well , but also use a few tricks . as always , when you 're making stop-motion , you may have to be creative and use all sorts of unusual tools and props to achieve the effect that you want . in this shot , the birds had to fly across and off the edge of the book , so we used fun-tak to move the clouds across the page . once they left the page , they had to be trimmed to get the illusion they flew off . when the pages of the book close at the end , we had to flip each page , supporting it in each position long enough to be photographed as an individual frame . we used binder clips , wedges , fun-tak , and almost every handy little thing you can think of . once all the individual frames were photographed , we put them all together and composited to make our pop-up book look like it 's moving on its own . so now , think of a special occasion where you can surprise someone with your own unique pop-up card , or an entire story that you want to tell , and start plotting the ins and outs of your pop-up book .
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and the pop-up book idea was born . ( music ) to make your own pop-up book , you 'll need some basic paper tools , such as scissors , an x-acto knife , glue , double-sided scotch tape , a ruler , a bone folder or other creasing tool , and , of course , some paper . for this lesson , we first determined the visual style by making illustrations and deciding on the overall design , colors , shapes and elements we wanted on each page , or spread .
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what are some essential tools you need to be a paper engineer ?
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imagine you 're asked to invent something new . it could be whatever you want made from anything you choose in any shape or size . that kind of creative freedom sounds so liberating , does n't it ? or does it ? if you 're like most people , you 'd probably be paralyzed by this task . without more guidance , where would you even begin ? as it turns out , boundless freedom is n't always helpful . in reality , any project is restricted by many factors , such as the cost , what materials you have at your disposal , and unbreakable laws of physics . these factors are called creative constraints , and they 're the requirements and limitations we have to address in order to accomplish a goal . creative constraints apply across professions , to architects and artists , writers , engineers , and scientists . in many fields , constraints play a special role as drivers of discovery and invention . during the scientific process in particular , constraints are an essential part of experimental design . for instance , a scientist studying a new virus would consider , `` how can i use the tools and techniques at hand to create an experiment that tells me how this virus infects the body 's cells ? and what are the limits of my knowledge that prevent me from understanding this new viral pathway ? '' in engineering , constraints have us apply our scientific discoveries to invent something new and useful . take , for example , the landers viking 1 and 2 , which relied on thrusters to arrive safely on the surface of mars . the problem ? those thrusters left foreign chemicals on the ground , contaminating soil samples . so a new constraint was introduced . how can we land a probe on mars without introducing chemicals from earth ? the next pathfinder mission used an airbag system to allow the rover to bounce and roll to a halt without burning contaminating fuel . years later , we wanted to send a much larger rover : curiosity . however , it was too large for the airbag design , so another constraint was defined . how can we land a large rover while still keeping rocket fuel away from the martian soil ? in response , engineers had a wild idea . they designed a skycrane . similar to the claw machine at toy stores , it would lower the rover from high above the surface . with each invention , the engineers demonstrated an essential habit of scientific thinking - that solutions must recognize the limitations of current technology in order to advance it . sometimes this progress is iterative , as in , `` how can i make a better parachute to land my rover ? '' and sometimes , it 's innovative , like how to reach our goal when the best possible parachute is n't going to work . in both cases , the constraints guide decision-making to ensure we reach each objective . here 's another mars problem yet to be solved . say we want to send astronauts who will need water . they 'd rely on a filtration system that keeps the water very clean and enables 100 % recovery . those are some pretty tough constraints , and we may not have the technology for it now . but in the process of trying to meet these objectives , we might discover other applications of any inventions that result . building an innovative water filtration system could provide a solution for farmers working in drought-stricken regions , or a way to clean municipal water in polluted cities . in fact , many scientific advances have occurred when serendipitous failures in one field address the constraints of another . when scientist alexander fleming mistakenly contaminated a petri dish in the lab , it led to the discovery of the first antibiotic , penicillin . the same is true of synthetic dye , plastic , and gunpowder . all were created mistakenly , but went on to address the constraints of other problems . understanding constraints guides scientific progress , and what 's true in science is also true in many other fields . constraints are n't the boundaries of creativity , but the foundation of it .
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the next pathfinder mission used an airbag system to allow the rover to bounce and roll to a halt without burning contaminating fuel . years later , we wanted to send a much larger rover : curiosity . however , it was too large for the airbag design , so another constraint was defined .
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what constraints were nasa trying to address by using airbags and the skycrane for the pathfinder and curiosity rover ? why not just use rockets to land on the surface of mars ?
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so a few years ago , i did something really brave , or some would say really stupid . i ran for congress . for years , i had existed safely behind the scenes in politics as a fundraiser , as an organizer , but in my heart , i always wanted to run . the sitting congresswoman had been in my district since 1992 . she had never lost a race , and no one had really even run against her in a democratic primary . but in my mind , this was my way to make a difference , to disrupt the status quo . the polls , however , told a very different story . my pollsters told me that i was crazy to run , that there was no way that i could win . but i ran anyway , and in 2012 , i became an upstart in a new york city congressional race . i swore i was going to win . i had the endorsement from the new york daily news , the wall street journal snapped pictures of me on election day , and cnbc called it one of the hottest races in the country . i raised money from everyone i knew , including indian aunties that were just so happy an indian girl was running . but on election day , the polls were right , and i only got 19 percent of the vote , and the same papers that said i was a rising political star now said i wasted 1.3 million dollars on 6,321 votes . do n't do the math . it was humiliating . now , before you get the wrong idea , this is not a talk about the importance of failure . nor is it about leaning in . i tell you the story of how i ran for congress because i was 33 years old and it was the first time in my entire life that i had done something that was truly brave , where i did n't worry about being perfect . and i 'm not alone : so many women i talk to tell me that they gravitate towards careers and professions that they know they 're going to be great in , that they know they 're going to be perfect in , and it 's no wonder why . most girls are taught to avoid risk and failure . we 're taught to smile pretty , play it safe , get all a 's . boys , on the other hand , are taught to play rough , swing high , crawl to the top of the monkey bars and then just jump off headfirst . and by the time they 're adults , whether they 're negotiating a raise or even asking someone out on a date , they 're habituated to take risk after risk . they 're rewarded for it . it 's often said in silicon valley , no one even takes you seriously unless you 've had two failed start-ups . in other words , we 're raising our girls to be perfect , and we 're raising our boys to be brave . some people worry about our federal deficit , but i , i worry about our bravery deficit . our economy , our society , we 're just losing out because we 're not raising our girls to be brave . the bravery deficit is why women are underrepresented in stem , in c-suites , in boardrooms , in congress , and pretty much everywhere you look . in the 1980s , psychologist carol dweck looked at how bright fifth graders handled an assignment that was too difficult for them . she found that bright girls were quick to give up . the higher the iq , the more likely they were to give up . bright boys , on the other hand , found the difficult material to be a challenge . they found it energizing . they were more likely to redouble their efforts . what 's going on ? well , at the fifth grade level , girls routinely outperform boys in every subject , including math and science , so it 's not a question of ability . the difference is in how boys and girls approach a challenge . and it does n't just end in fifth grade . an hp report found that men will apply for a job if they meet only 60 percent of the qualifications , but women , women will apply only if they meet 100 percent of the qualifications . 100 percent . this study is usually invoked as evidence that , well , women need a little more confidence . but i think it 's evidence that women have been socialized to aspire to perfection , and they 're overly cautious . ( applause ) and even when we 're ambitious , even when we 're leaning in , that socialization of perfection has caused us to take less risks in our careers . and so those 600,000 jobs that are open right now in computing and tech , women are being left behind , and it means our economy is being left behind on all the innovation and problems women would solve if they were socialized to be brave instead of socialized to be perfect . ( applause ) so in 2012 , i started a company to teach girls to code , and what i found is that by teaching them to code i had socialized them to be brave . coding , it 's an endless process of trial and error , of trying to get the right command in the right place , with sometimes just a semicolon making the difference between success and failure . code breaks and then it falls apart , and it often takes many , many tries until that magical moment when what you 're trying to build comes to life . it requires perseverance . it requires imperfection . we immediately see in our program our girls ' fear of not getting it right , of not being perfect . every girls who code teacher tells me the same story . during the first week , when the girls are learning how to code , a student will call her over and she 'll say , `` i do n't know what code to write . '' the teacher will look at her screen , and she 'll see a blank text editor . if she did n't know any better , she 'd think that her student spent the past 20 minutes just staring at the screen . but if she presses undo a few times , she 'll see that her student wrote code and then deleted it . she tried , she came close , but she did n't get it exactly right . instead of showing the progress that she made , she 'd rather show nothing at all . perfection or bust . it turns out that our girls are really good at coding , but it 's not enough just to teach them to code . my friend lev brie , who is a professor at the university of columbia and teaches intro to java tells me about his office hours with computer science students . when the guys are struggling with an assignment , they 'll come in and they 'll say , `` professor , there 's something wrong with my code . '' the girls will come in and say , `` professor , there 's something wrong with me . '' we have to begin to undo the socialization of perfection , but we 've got to combine it with building a sisterhood that lets girls know that they are not alone . because trying harder is not going to fix a broken system . i ca n't tell you how many women tell me , `` i 'm afraid to raise my hand , i 'm afraid to ask a question , because i do n't want to be the only one who does n't understand , the only one who is struggling . when we teach girls to be brave and we have a supportive network cheering them on , they will build incredible things , and i see this every day . take , for instance , two of our high school students who built a game called tampon run -- yes , tampon run -- to fight against the menstruation taboo and sexism in gaming . or the syrian refugee who dared show her love for her new country by building an app to help americans get to the polls . or a 16-year-old girl who built an algorithm to help detect whether a cancer is benign or malignant in the off chance that she can save her daddy 's life because he has cancer . these are just three examples of thousands , thousands of girls who have been socialized to be imperfect , who have learned to keep trying , who have learned perseverance . and whether they become coders or the next hillary clinton or beyoncé , they will not defer their dreams . and those dreams have never been more important for our country . for the american economy , for any economy to grow , to truly innovate , we can not leave behind half our population . we have to socialize our girls to be comfortable with imperfection , and we 've got to do it now . we can not wait for them to learn how to be brave like i did when i was 33 years old . we have to teach them to be brave in schools and early in their careers , when it has the most potential to impact their lives and the lives of others , and we have to show them that they will be loved and accepted not for being perfect but for being courageous . and so i need each of you to tell every young woman you know -- your sister , your niece , your employee , your colleague -- to be comfortable with imperfection , because when we teach girls to be imperfect , and we help them leverage it , we will build a movement of young women who are brave and who will build a better world for themselves and for each and every one of us . thank you . ( applause ) thank you . chris anderson : reshma , thank you . it 's such a powerful vision you have . you have a vision . tell me how it 's going . how many girls are involved now in your program ? reshma saujani : yeah . so in 2012 , we taught 20 girls . this year we 'll teach 40,000 in all 50 states . ( applause ) and that number is really powerful , because last year we only graduated 7,500 women in computer science . like , the problem is so bad that we can make that type of change quickly . ca : and you 're working with some of the companies in this room even , who are welcoming graduates from your program ? rs : yeah , we have about 80 partners , from twitter to facebook to adobe to ibm to microsoft to pixar to disney , i mean , every single company out there . and if you 're not signed up , i 'm going to find you , because we need every single tech company to embed a girls who code classroom in their office . ca : and you have some stories back from some of those companies that when you mix in more gender balance in the engineering teams , good things happen . rs : great things happen . i mean , i think that it 's crazy to me to think about the fact that right now 85 percent of all consumer purchases are made by women . women use social media at a rate of 600 percent more than men . we own the internet , and we should be building the companies of tomorrow . and i think when companies have diverse teams , and they have incredible women that are part of their engineering teams , they build awesome things , and we see it every day . ca : reshma , you saw the reaction there . you 're doing incredibly important work . this whole community is cheering you on . more power to you . thank you . rs : thank you . ( applause )
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well , at the fifth grade level , girls routinely outperform boys in every subject , including math and science , so it 's not a question of ability . the difference is in how boys and girls approach a challenge . and it does n't just end in fifth grade .
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how do we raise boys and girls differently and how does that affect them as they get older ?
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the term modern art sounds like it means art that is popular at the moment , but in fact , modern art is a style that originated over 150 years ago , and includes artists that by now have attained classic status , such as picasso , matisse , and gauguin . and what 's even more ironic is that the movement they pioneered , considered revolutionary and even scandalous at the time , was inspired largely by an object of a traditional and ancient design . as far back as the renaissance , the primary european art movements emphasized conventional representation and adherence to classical forms . but that began to change in the late 19th century as artists like van gogh and cézanne expanded the boundaries of painting . soon , a movement arose that sought to create an entirely new style of art , and one way of doing so was to look beyond western civilization . for example , paul gauguin moved to the island of tahiti in the 1890s . there , he found inspiration in the island 's inhabitants , landscape , and culture to create artwork that intertwined european themes and polynesian lore . others looked the cultures of the islamic world , but the most influential inspiration would come from sub-saharan africa . as european empires expanded deeper into the african continent , its artifacts and artworks made their way into the hands of museums and collectors . one such collector was henri matisse , who showed his friend picasso a mask he had acquired made by the dan tribe of the ivory coast . the mask awoke picasso 's curiosity , leading him to visit the trocadéro ethnographic museum in paris in 1907 . founded to house acquisitions from colonial conquests , the museum boasted a collection of african art , with stylized figures and masks made of wood and decorated with simple colors and materials . the visit was a revelation for picasso , who proclaimed that african masks were what painting was all about . at this time , picasso had been working on a painting of five nude women in a style that would later come to be known as cubism . and while three of these ladies show facial features found in ancient iberian art , a nod to picasso 's spanish heritage , the faces of the two on the right closely resemble african masks . created in 1907 after hundreds of sketches and studies , `` les demoiselles d'avignon '' has been considered the first truly 20th century masterpiece , breaking with many previously held notions in art . it was at once aggressive and abstract , distorted yet primal in its raw geometry , a new artistic language with new forms , colors , and meanings . and these avant-garde qualities caused a sensation when the painting was first exhibited almost ten years later . the public was shocked , critics denounced it as immoral , and even picasso 's own friends were simultaneously surprised , offended , and mesmerized at his audacity . more artists soon followed in picasso 's footsteps . constantin brâncuși and amedeo modigliani in paris , as well as the german expressionists , all drew on the aesthetics of african sculptures in their work . others looked to a different continent for their inspiration . british sculptor henry moore based many of his semi-abstract bronze sculptures on a replica of a chacmool , a distinctive reclining statue from the toltec-maya culture . pre-columbian art was also a major influence for josef albers . he created a series of compositions , such as the geometrical series homage to the square , that were inspired by pyramids and local art he encountered on his frequent visits to mexico . inspiration from ancient cultures initiated one of the most revolutionary movements in art history , but were these artists playing the role of explorers or conquistadors , appropriating ideas and profiting from cultures they considered primitive ? questions like this deserve scrutiny , as artists continue to redefine standards . perhaps not too long from now , the bold innovations of modern art will seem like stale orthodoxies , ready to be overturned by a new set of radical trailblazers drawing inspiration from another unlikely source .
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the term modern art sounds like it means art that is popular at the moment , but in fact , modern art is a style that originated over 150 years ago , and includes artists that by now have attained classic status , such as picasso , matisse , and gauguin . and what 's even more ironic is that the movement they pioneered , considered revolutionary and even scandalous at the time , was inspired largely by an object of a traditional and ancient design .
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how many years ago do you think the modern art movement originated ?
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translator : andrea mcdonough reviewer : bedirhan cinar i like to think of life science as one big pyramid . let 's call the pyramid , `` biological organization '' . let 's work our way from very small and specific concepts to very large and complex topics . so let 's start at the tip of the pyramid , with something so small , it ca n't be seen by the human eye , a single cell . a cell by itself is the most basic component of life . a single cell , which is capable of living on its own , is called a unicellular organism , organisms like bacteria or protists . these organisms are everywhere you look , you just ca n't see them . but , when cells join together , with more than one cell like itself to perform a similar function , it 's no longer a unicellular organism . it 's then called a tissue . no , not that kind of tissue . there are four types of tissues found in the human body : connective , muscle , nervous , and epithelial . bone tissue is a type of connective tissue and it 's not flimsy like a kleenex at all . blood is also an example of the same cells working together to perform the same job , but it 's a liquid , again , not like a kleenex at all . no matter what the consistency is , a tissue is a group of the same cells , working together to perform a similar function . any time there are different tissues working together , we then call it an organ . that 's the next level of the pyramid . animals are n't the only ones with organs ; plants have organs too . when we find multiple different organs working together to perform the same job , we then call it an organ system . take the digestive system , for example . it 's made up of a mouth , esophagus , stomach , pancreas , liver , gall bladder , small intestine , and large intestine , also known as your colon . although each individual organ in this organ system does a very different job , together , these organs work to achieve the one goal of taking all the nutrients out of the food we eat and getting rid of what we do n't need . an organ system , by definition , can only do one job , like get the nutrients from our food , send and receive electrical signals , or exchange oxygen for carbon dioxide . regardless of their individual function , all organ systems rely on one another to do the vital jobs which they ca n't do themselves . if one organ system does n't work , the others will shut down , too . an organism is a complicated , living thing , which requires the proper functioning of multiple organ systems to maintain stability . this stability is called homeostasis . when all organ systems are working together and maintaining homeostasis , then it results in a happy , living organism . organisms are incredibly diverse and can be as simple as a bacteria or as complex as you . when a group of the same organisms , also known as a species , live together in the same environment , we then call it a population . often there are several populations all living in one environment . that is what we call a community . each time you look out the window , you 're seeing a community . when we look at multiple communities , along with how all of the organisms interact with the physical environment , then we refer to it as an ecosystem . when you look at all the ecosystems of earth together , you 're looking at the earth . the earth is a big , round circle of life . that 's why we call it a biosphere - bio , meaning life and sphere , meaning circle . and there you go ! when you break it down to each level , a very complex concept and phrase becomes easy to understand . all life starts with a single cell . when cells join together , they are called a tissue . a group of different tissues are called an organ , and a group of different organs are an organ system . a group of organ systems working together make up an organism , and a group of the same organisms are a population . combining several different populations together give us a community . and several different communities in a large area is an ecosystem . and every ecosystem together makes up our biosphere . and that , my friends , is biological organization , the pyramid of life .
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when we find multiple different organs working together to perform the same job , we then call it an organ system . take the digestive system , for example . it 's made up of a mouth , esophagus , stomach , pancreas , liver , gall bladder , small intestine , and large intestine , also known as your colon .
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which of the following is an example of an organ system ?
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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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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 .
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why ca n't you see very much when you 're deep in the ocean ?
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translator : bedirhan cinar my wife is pregnant right now with our first child , and when people see her with her big baby bump , the first question people ask , almost without fail , is , `` is it a boy or is it a girl ? '' now , there are some assumptions behind that question that we take for granted because of our familiarity with our own human biology . for human babies , we take it for granted that there 's a 50/50 chance of either answer , boy or girl . but why is it that way ? well , the answer depends on the sex determination system that has evolved for our species . you see , for most mammals , the sex of a baby is determined genetically with the xy chromosome system . mammals have a pair of sex chromosomes , one passed down from mom , and one from dad . a pair of x 's gives us a girl , and an x and a y together gives us a boy . since females only have x 's to pass on in their egg cells , and males can give either an x or a y in their sperm cells , the sex is determined by the father and the chance of producing a male or a female is 50/50 . this system has worked well for mammals , but throughout the tree of life , we can see other systems that have worked just as well for other animals . there are other groups of animals that also have genetic sex determination , but their systems can be pretty different from ours . birds and some reptiles have their sex genetically determined , but instead of the sex being determined by dad , their sex is determined by mom . in those groups , a pair of z sex chromosomes produces a male , so these males only have z 's to give . however , in these animals , one z and one w chromosome together , as a pair , produces a female . in this system , the chance of a male or a female is still 50/50 , it just depends on whether mom puts a z or a w into her egg . certain groups have taken genetic sex determination in completely other directions . ants , for example , have one of the most interesting systems for determining sex , and because of it , if you are a male ant , you do not have a father . in an ant colony , there are dramatic divisions of labor . there are soldiers that defend the colony , there are workers that collect food , clean the nest and care for the young , and there 's a queen and a small group of male reproductives . now , the queen will mate and then store sperm from the males . and this is where the system gets really interesting . if the queen uses the stored sperm to fertilize an egg , then that egg will grow up to become female . however , if she lays an egg without fertilizing it , then that egg will still grow up to be an ant , but it will always be a male . so you see , it 's impossible for male ants to have fathers . and male ants live their life like this , with only one copy of every gene , much like a walking sex cell . this system is called a haplodiploid system , and we see it not only in ants , but also in other highly social insects like bees and wasps . since our own sex is determined by genes , and we do know of these other animals that have their sex determined by genes , it 's easy to assume that for all animals the sex of their babies still must be determined by genetics . however , for some animals , the question of whether it will be a boy or a girl has nothing to do with genes at all , and it can depend on something like the weather . these are animals like alligators and most turtles . in these animals , the sex of an embryo in a developing egg is determined by the temperature . in these species , the sex of the baby is not yet determined when the egg is laid , and it remains undetermined until sometime in the middle of the overall development period , when a critical time is reached . and during this time , the sex is completely determined by temperature in the nest . in painted turtles , for example , warm temperatures above the critical temperature will produce females within the eggs , and cool temperatures will produce a male . i 'm not sure who came up with this mnemonic , but you can remember that when it comes to painted turtles , they are all hot chicks and cool dudes . for some tropical fish , the question of will it be a boy or will it be a girl is n't settled until even later in life . you see , clownfish all start out their lives as males , however , as they mature , they become female . they also spend their lives in small groups with a strict dominance hierarchy where only the most dominant male and female reproduce . and amazingly , if the dominant female in the group dies , the largest and most dominant male will then quickly become female and take her place , and all of the other males will move up one rank in the hierarchy . in another very different ocean animal , the green spoonworm , the sex of the babies is determined by a completely different aspect of the environment . for this species , it is simply a matter of where a larva happens to randomly fall on the sea floor . if a larva lands on the open sea floor , then it will become a female . but if it lands on top of a female , then it will become a male . so for some species , the question of boy or girl is answered by genetics . for others , it 's answered by the environment . and for others still , they do n't even bother with the question at all . take whiptail lizards , for example . for those desert lizards , the answer is easy . it 's a girl . it 's always a girl . they are a nearly all-female species , and although they still lay eggs , these eggs hatch out female clones of themselves . so will it be a girl or will it be a boy ? throughout the entire animal kingdom , it does really all depend on the system of sex determination . for humans , that system is a genetic xy system . and for me and my wife , we found out it 's going to be a baby boy . ( kiss )
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however , for some animals , the question of whether it will be a boy or a girl has nothing to do with genes at all , and it can depend on something like the weather . these are animals like alligators and most turtles . in these animals , the sex of an embryo in a developing egg is determined by the temperature .
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one of the advantages of asexual reproduction , like we see in the whiptail lizards , is that no energy is expended to find a mate . however , some animals like rotifers ( microscopic aquatic animals ) use asexual reproduction or sexual reproduction depending on which form of reproduction the environmental conditions favor at the moment . which environmental conditions do you think would favor asexual reproduction ? which environmental conditions do you think would favor sexual reproduction ?
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to understand climate change , think of the game `` tetris . '' for eons , earth has played a version of this game with blocks of carbon . they enter the atmosphere as carbon dioxide gas from volcanoes , decaying plant matter , breathing creatures and the surface of the sea . and they leave the atmosphere when they 're used by plants during photosynthesis , absorbed back into the ocean , or stored in soil and sediment . this game of tetris is called the carbon cycle , and it 's the engine of life on earth . what 's the connection to climate ? well , when that carbon dioxide is in the air , waiting to be reabsorbed , it traps a portion of the sun 's heat , which would otherwise escape to space . that 's why carbon dioxide is called a greenhouse gas . it creates a blanket of warmth , known as the greenhouse effect , that keeps our earth from freezing like mars . the more carbon dioxide blocks hang out in the atmosphere waiting to be cleared , the warmer earth becomes . though the amount of carbon in the atmosphere has varied through ice ages and astroid impacts , over the past 8,000 years the stable climate we know took shape , allowing human civilization to thrive . but about 200 years ago , we began digging up that old carbon that had been stored in the soil . these fossil fuels , coal , oil and natural gas are made from the buried remains of plants and animals that died long before humans evolved . the energy stored inside them was able to power our factories , cars and power plants . but burning these fuels also injected new carbon blocks into earth 's tetris game . at the same time , we cleared forests for agriculture , reducing the earth 's ability to remove the blocks . and since 1750 , the amount of carbon in the atmosophere has increased by 40 % , and shows no sign of slowing . just like in tetris , the more blocks pile up , the harder it becomes to restore stability . the extra carbon dioxide in the atmosphere accelerates the greenhouse effect by trapping more heat near the surface and causing polar ice caps to melt . and the more they melt , the less sunlight they 're able to reflect , making the oceans warm even faster . sea levels rise , coastal populations are threatened with flooding , natural ecosystems are disrupted , and the weather becomes more extreme over time . climate change may effect different people and places in different ways . but , ultimately , it 's a game that we 're all stuck playing . and unlike in tetris , we wo n't get a chance to start over and try again .
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and they leave the atmosphere when they 're used by plants during photosynthesis , absorbed back into the ocean , or stored in soil and sediment . this game of tetris is called the carbon cycle , and it 's the engine of life on earth . what 's the connection to climate ?
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how have humans altered the carbon cycle ?
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more than a century after first emerging into the fog-bound , gas-lit streets of victorian london , sherlock holmes is universally recognizable . even his wardrobe and accessories are iconic : the inverness cape , deerstalker hat , and calabash pipe , and figures such as his best friend and housemate doctor watson , arch-nemesis moriarty , and housekeeper mrs. hudson have become part of the popular consciousness , as have his extraordinary , infallible powers of deduction utilized in the name of the law , his notorious drug use , and his popular catchphrase , `` elementary , my dear watson . '' and yet many of these most recognizable features of holmes do n't appear in arthur conan doyle 's original stories . doyle 's great detective solves crimes in all sorts of ways , not just using deduction . he speculates , and at times even guesses , and regularly makes false assumptions . furthermore , mrs. hudson is barely mentioned , no one says , `` elementary , my dear watson , '' and the detective and his sidekick live apart for much of the time . moriarty , the grand villain , only appears in two stories , the detective 's drug use is infrequent after the first two novels , and holmes is rarely enthralled to the english legal system ; he much prefers enacting his own form of natural justice to sticking to the letter of the law . finally , many of the most iconic elements of the holmesian legend are n't doyle 's either . the deerstalker cap and cape were first imagined by sidney paget , the story 's initial illustrator . the curved pipe was chosen by american actor william gillette so that audiences could more clearly see his face on stage , and the phrase , `` elementary , my dear watson , '' was coined by author and humorist p.g . wodehouse . so who exactly is sherlock holmes ? who 's the real great detective , and where do we find him ? purists might answer that the original sherlock inspired by arthur conan doyle 's university mentor dr. joseph bell is the real one . but the fact remains that that version of sherlock has been largely eclipsed by the sheer volume of interpretation , leaving doyle 's detective largely unrecognizable . so there 's another , more complex , but perhaps more satisfying answer to the question , but to get there , we must first consider the vast body of interpretations of the great detective . since conan doyle 's first story in 1887 , there have been thousands of adaptations of holmes , making him perhaps the most adapted fictional character in the world . that process began with victorian stage adaptations , and accelerated with the emergence of film . there were more than 100 film adaptations of holmes in the first two decades of the 20th century alone . and since then , there have many thousands more in print , and on film , television , stage , and radio . holmes has been reinterpreted by people everywhere , in remarkably different , and often contradictory ways . these adaptations demonstrate both holmes 's popularity and his malleability . for instance , he featured in a number of allied anti-nazi propaganda films during world war ii . and both winston churchill and franklin delano roosevelt were avid enthusiasts , the latter even joining the baker street irregulars , a holmesian appreciation society , and nicknaming one secret service hideout baker street . and yet , at the very same time , holmes also appeared in various german-language film adaptations , some of which were said to have been much-loved favorites of adolf hitler . so let 's return to our question . would the real sherlock holmes please stand up ? the truth is that this world of adaptation has made him into a palimpsest . sherlock is a cultural text , repeatedly altered over time as each new interpretation becomes superimposed over those that proceed it . this means that sherlock continually evolves , embodying ideas and values often far removed from those found in conan doyle . and after each particular story ends , sherlock rises again , a little changed , perhaps , with a new face and fresh mannerisms or turns of phrase , but still essentially sherlock , our sherlock .
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wodehouse . so who exactly is sherlock holmes ? who 's the real great detective , and where do we find him ?
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what musical instrument does sherlock holmes play ?
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translator : jennifer cody reviewer : jessica ruby when faced with a big challenge where potential failure seems to lurk at every corner , maybe you 've heard this advice before : `` be more confident . '' and most likely , this is what you think when you hear it : `` if only it were that simple . '' but what is confidence ? take the belief that you are valuable , worthwhile , and capable , also known as self-esteem , add in the optimism that comes when you are certain of your abilities , and then empowered by these , act courageously to face a challenge head-on . this is confidence . it turns thoughts into action . so where does confidence even come from ? there are several factors that impact confidence . one : what you 're born with , such as your genes , which will impact things like the balance of neurochemicals in your brain . two : how you 're treated . this includes the social pressures of your environment . and three : the part you have control over , the choices you make , the risks you take , and how you think about and respond to challenges and setbacks . it is n't possible to completely untangle these three factors , but the personal choices we make certainly play a major role in confidence development . so , by keeping in mind a few practical tips , we do actually have the power to cultivate our own confidence . tip 1 : a quick fix . there are a few tricks that can give you an immediate confidence boost in the short term . picture your success when you 're beginning a difficult task , something as simple as listening to music with deep bass ; it can promote feelings of power . you can even strike a powerful pose or give yourself a pep talk . tip two : believe in your ability to improve . if you 're looking for a long-term change , consider the way you think about your abilities and talents . do you think they are fixed at birth , or that they can be developed , like a muscle ? these beliefs matter because they can influence how you act when you 're faced with setbacks . if you have a fixed mindset , meaning that you think your talents are locked in place , you might give up , assuming you 've discovered something you 're not very good at . but if you have a growth mindset and think your abilities can improve , a challenge is an opportunity to learn and grow . neuroscience supports the growth mindset . the connections in your brain do get stronger and grow with study and practice . it also turns out , on average , people who have a growth mindset are more successful , getting better grades , and doing better in the face of challenges . tip three : practice failure . face it , you 're going to fail sometimes . everyone does . j.k. rowling was rejected by twelve different publishers before one picked up `` harry potter . '' the wright brothers built on history 's failed attempts at flight , including some of their own , before designing a successful airplane . studies show that those who fail regularly and keep trying anyway are better equipped to respond to challenges and setbacks in a constructive way . they learn how to try different strategies , ask others for advice , and perservere . so , think of a challenge you want to take on , realize it 's not going to be easy , accept that you 'll make mistakes , and be kind to yourself when you do . give yourself a pep talk , stand up , and go for it . the excitement you 'll feel knowing that whatever the result , you 'll have gained greater knowledge and understanding . this is confidence .
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take the belief that you are valuable , worthwhile , and capable , also known as self-esteem , add in the optimism that comes when you are certain of your abilities , and then empowered by these , act courageously to face a challenge head-on . this is confidence . it turns thoughts into action .
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it seems counterintuitive that persistence in response to failure could actually increase a person 's confidence level . explain why the opposite is true .
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translation - marie de hert in j.r.r . 's world , gandalf is one of five wizards sent by the valar to guide the inhabitants of middle earth in their struggles against the dark force of sauron . gandalf 's body was mortal , subject to the physical rules of middle earth , but his spirit was immortal , as seen when he died as gandalf the grey and resurrected as gandalf the white . according to the wachowski 's script , an awakened human only has to link up and hack the neon binary code of the matrix to learn how to fly a helicopter in a matter of seconds . or if you are the one , or one of the ones , you do n't even need a helicopter , you just need a cool pair of shades . cheshire cats can juggle their own heads . ipads are rudimentary . no quidditch match ends until the golden snitch is caught . and the answer to the ultimate question of life , the universe , and everything is most certainly 42 . just like real life , fictional worlds operate consistently within a spectrum of physical and societal rules . that 's what makes these intricate worlds believable , comprehensible , and worth exploring . in real life , the law of gravity holds seven book sets of `` harry potter '' to millions of bookshelves around the world . we know this to be true , but we also know that ever since j.k. typed the words wizard , wand , and `` wingardium leviosa , '' that law of gravity has ceased to exist on the trillions of pages resting between those bookends . authors of science fiction and fantasy literally build worlds . they make rules , maps , lineages , languages , cultures , universes , alternate universes within universes , and from those worlds sprout story , after story , after story . when it 's done well , readers can understand fictional worlds and their rules just as well as the characters that live in them do and sometimes , just as well or even better than the reader understands the world outside of the book . but how ? how can human-made squiggles on a page reflect lights into our eyes that send signals to our brains that we logically and emotionally decode as complex narratives that move us to fight , cry , sing , and think , that are strong enough not only to hold up a world that is completely invented by the author , but also to change the reader 's perspective on the real world that resumes only when the final squiggle is reached ? i 'm not sure anyone knows the answer to that question , yet fantastical , fictional worlds are created everyday in our minds , on computers , even on napkins at the restaurant down the street . the truth is your imagination and a willingness to , figuratively , live in your own world are all you need to get started writing a novel . i did n't dream up hogwarts or the star wars ' cantina , but i have written some science thrillers for kids and young adults . here are some questions and methods i 've used to help build the worlds in which those books take place . i start with a basic place and time . whether that 's a fantasy world or a futuristic setting in the real world , it 's important to know where you are and whether you 're working in the past , present , or future . i like to create a timeline showing how the world came to be . what past events have shaped the way it is now ? then i brainstorm answers to questions that draw out the details of my fictional world . what rules are in place here ? this covers everything from laws of gravity , or not , to the rules of society and the punishments for individuals who break them . what kind of government does this world have ? who has power , and who does n't ? what do people believe in here ? and what does this society value most ? then it 's time to think about day-to-day life . what 's the weather like in this world ? where do the inhabitants live and work and go to school ? what do they eat and how do they play ? how do they treat their young and their old ? what relationships do they have with the animals and plants of the world ? and what do those animals and plants look like ? what kind of technology exists ? transportation ? communication ? access to information ? there 's so much to think about ! so , spend some time living in those tasks and the answers to those questions , and you 're well on your way to building your own fictional world . once you know your world as well as you hope your reader will , set your characters free in it and see what happens . and ask yourself , `` how does this world you created shape the individuals who live in it ? and what kind of conflict is likely to emerge ? '' answer those questions , and you have your story . good luck , future world-builder !
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i start with a basic place and time . whether that 's a fantasy world or a futuristic setting in the real world , it 's important to know where you are and whether you 're working in the past , present , or future . i like to create a timeline showing how the world came to be .
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why is world building important for futuristic and fantasy novels , and how does the author ’ s work in this area affect the experience of the reader ?
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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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[ 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 .
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what could be the benefits of performing a ‘ daily ritual ’ when creating art ?
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translator : marcia de brito reviewer : ariana bleau lugo ( guitar music throughout ) music is a language . both music and verbal languages serve the same purpose . they are both forms of expression . they can be used as a way to communicate with others . they can be read and written . they can make you laugh or cry , think or question , and can speak to one or many . and both can definitely make you move . in some instances , music works better than the spoken word , because it does n't have to be understood to be effective . although many musicians agree that music is a language , it is rarely treated as such . many of us treat it as something that can only be learned by following a strict regimen , under the tutelage of a skilled teacher . this approach has been followed for hundreds of years with proven success , but it takes a long time . too long . think about the first language you learn as a child . more importantly , think about how you learned it . you were a baby when you first started speaking , and even though you spoke the language incorrectly you were allowed to make mistakes . and the more mistakes you made , the more your parents smiled . learning to speak was not something you were sent somewhere to do only a few times a week . and the majority of the people you spoke to were not beginners . they were already proficient speakers . imagine your parents forcing you to only speak to other babies until you were good enough to speak to them . you would probably be an adult before you could carry on a proper conversation . to use a musical term , as a baby , you were allowed to jam with professionals . if we approach music in the same natural way we approached our first language , we will learn to speak it in the same short time it took to speak our first language . proof of this could be seen in almost any family where a child grows up with other musicians in the family . here are a few keys to follow in learning or teaching music . in the beginning , embrace mistakes , instead of correcting them . like a child playing air guitar , there are no wrong notes . allow young musicians to play and perform with accomplished musicians on a daily basis . encourage young musicians to play more than they practice . the more they play the more they will practice on their own . music comes from the musician , not the instrument . and most importantly , remember that a language works best when we have something interesting to say . many music teachers never find out what their students have to say . we only tell them what they are supposed to say . a child speaks a language for years before they even learn the alphabet . too many rules at the onset , will actually slow them down . in my eyes , the approach to music should be the same . after all , music is a language too .
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here are a few keys to follow in learning or teaching music . in the beginning , embrace mistakes , instead of correcting them . like a child playing air guitar , there are no wrong notes .
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when you are first learning music , you should embrace mistakes instead of correcting them .
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around 1159 a.d. , a mathematician called bhaskara the learned sketched a design for a wheel containing curved reservoirs of mercury . he reasoned that as the wheels spun , the mercury would flow to the bottom of each reservoir , leaving one side of the wheel perpetually heavier than the other . the imbalance would keep the wheel turning forever . bhaskara 's drawing was one of the earliest designs for a perpetual motion machine , a device that can do work indefinitely without any external energy source . imagine a windmill that produced the breeze it needed to keep rotating . or a lightbulb whose glow provided its own electricity . these devices have captured many inventors ' imaginations because they could transform our relationship with energy . for example , if you could build a perpetual motion machine that included humans as part of its perfectly efficient system , it could sustain life indefinitely . there 's just one problem . they do n't work . ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics , the branch of physics that describes the relationship between different forms of energy . the first law of thermodynamics says that energy ca n't be created or destroyed . you ca n't get out more energy than you put in . that rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed . there would n't be any left over to power a car or charge a phone . but what if you just wanted the machine to keep itself moving ? inventors have proposed plenty of ideas . several of these have been variations on bhaskara 's over-balanced wheel with rolling balls or weights on swinging arms . none of them work . the moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle . with a low center of mass , the wheel just swings back and forth like a pendulum , then stops . what about a different approach ? in the 17th century , robert boyle came up with an idea for a self-watering pot . he theorized that capillary action , the attraction between liquids and surfaces that pulls water through thin tubes , might keep the water cycling around the bowl . but if the capillary action is strong enough to overcome gravity and draw the water up , it would also prevent it from falling back into the bowl . then there are versions with magnets , like this set of ramps . the ball is supposed to be pulled upwards by the magnet at the top , fall back down through the hole , and repeat the cycle . this one fails because like the self-watering pot , the magnet would simply hold the ball at the top . even if it somehow did keep moving , the magnet 's strength would degrade over time and eventually stop working . for each of these machines to keep moving , they 'd have to create some extra energy to nudge the system past its stopping point , breaking the first law of thermodynamics . there are ones that seem to keep going , but in reality , they invariably turn out to be drawing energy from some external source . even if engineers could somehow design a machine that did n't violate the first law of thermodynamics , it still would n't work in the real world because of the second law . the second law of thermodynamics tells us that energy tends to spread out through processes like friction . any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat , even in a vacuum . that heat is energy escaping , and it would keep leeching out , reducing the energy available to move the system itself until the machine inevitably stopped . so far , these two laws of thermodynamics have stymied every idea for perpetual motion and the dreams of perfectly efficient energy generation they imply . yet it 's hard to conclusively say we 'll never discover a perpetual motion machine because there 's still so much we do n't understand about the universe . perhaps we 'll find new exotic forms of matter that 'll force us to revisit the laws of thermodynamics . or maybe there 's perpetual motion on tiny quantum scales . what we can be reasonably sure about is that we 'll never stop looking . for now , the one thing that seems truly perpetual is our search .
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they do n't work . ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics , the branch of physics that describes the relationship between different forms of energy . the first law of thermodynamics says that energy ca n't be created or destroyed . you ca n't get out more energy than you put in .
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which of the laws of thermodynamics imposes a greater obstacle to the successful achievement of perpetual motion machines , and why : the first ( energy can not be created or destroyed ) or the second ( energy tends to `` leech out '' of systems ) ?
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is it a flying comma , or a quotation mark chopped in half ? either way , you may already be well-versed in how to use the apostrophe , but here 's a quick refresher on its usage . the apostrophe can be used in three ways : to mark possession , to mark contraction , to mark the plural of single letters . most of the time , if you see an apostrophe hovering helpfully near a word , it 's trying to mark possession or contraction . first , let 's look at how the apostrophe marks possession . as you can see , the placement of this punctuation mark can really change the meaning of a sentence . `` those robots in the sand are my sister 's . '' `` those robots in the sand are my sisters . ' '' `` those robots in the sand are my sisters . '' when showing possession , the apostrophe belongs next to the noun that owns or possesses something . the noun can be singular or plural . proper nouns work , too . so if lucy needs to get her robots under control before they cause mayhem , those dangerous creatures would be `` lucy 's robots . '' but what if lucy was lucas ? would we write `` lucas ' robots '' or `` lucas 's robots '' ? and what if lucas gave his robots to the robinsons family ? would it be `` the robinsons ' robots , '' or `` the robinsons 's robots '' ? the truth is , even grammar nerds disagree on the right thing to do . the use of 's after a proper noun ending in s is a style issue , not a hard and fast grammar rule . it 's a conundrum without a simple answer . professional writers solve this problem by learning what 's considered correct for a publication , and doing that . the important thing is to pick one style and stick with it throughout a piece of writing . one more wrinkle . certain pronouns already have possession built in and do n't need an apostrophe . remembering that will help you avoid one of the trickiest snags in english grammar : its vs. it 's . `` it 's '' only take an apostrophe when it 's a contraction for `` it is '' or `` it has . '' if you can replace `` it 's '' with one of those two phrases , use the apostrophe . if you 're showing possession , leave it out . otherwise , contractions are pretty straightforward . the apostrophe stands in for missing letters , and lets common phrases squash into a single word . in rare cases , you can have a double contraction , though those generally are n't accepted in writing , with the exception of dialogue . so it 's possessive , it 's often followed by s 's , and it 's sometimes tricky when it comes to its usage . it 's the apostrophe .
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most of the time , if you see an apostrophe hovering helpfully near a word , it 's trying to mark possession or contraction . first , let 's look at how the apostrophe marks possession . as you can see , the placement of this punctuation mark can really change the meaning of a sentence . `` those robots in the sand are my sister 's . ''
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the placement of an apostrophe can really change the meaning of a sentence . which of the following sentences demonstrates the power of apostrophe placement ?
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sunken relics , ghostly shipwrecks , and lost cities . these are n't just wonders found in fictional adventures . beneath the ocean 's surface , there are ruins where people once roamed and shipwrecks loaded with artifacts from another time . this is the domain of underwater archaeology , where researchers discover and study human artifacts that slipped into the sea . they 're not on a treasure hunt . underwater archaeology reveals important information about ancient climates and coastlines , it tells us how humans sailed the seas , and what life was like millennia ago . so what exactly can we find ? at shallow depths mingled in with modern-day items , we 've discovered all sorts of ancient artifacts . this zone contains evidence of how our ancestors fished , how they repaired their ships , disposed of their trash , and even their convicted pirates , who were buried below the tide line . and it 's not just our recent history . 800,000-year old footprints were found along the shore in norfolk , britain . in these shallow depths , the remains of sunken cities also loom up from the sea floor , deposited there by earthquakes , tsunamis , and earth 's sinking plates . almost every sunken city can be found at these shallow depths because the sea level has changed little in the several thousand years that city-building civilizations have existed . for instance , in shallow waters off the coast of italy lies baia , a roman seaside town over 2,000 years old . there , it 's possible to swim among the ruins of structures built by rome 's great families , senators , and emperors . and then there are shipwrecks . as ships grow too old for use , they 're usually abandoned near shore in out-of-the-way places like estuaries , rivers , and shallow bays . archaeologists use these like a timeline to map a harbor 's peaks and declines , and to get clues about the historic art of shipbuiding . at roskilde in denmark , for example , five purposefully sunken vessels reveal how vikings crafted their fearsome long ships 1,000 years ago . when we descend a bit further , we reach the zone where the deepest human structures lie , like ancient harbor walls and quays . we also see more shipwrecks sunk by storms , war , and collisions . we 're still excavating many of these wrecks today , like blackbeard 's ship , which is revealing secrets about life as an 18th century pirate . but past 50 feet , there are even deeper , better preserved shipwrecks , like the wreck at antikythera , which sank during the 1st century bc . when it was discovered , it contained statues , trade cargo , and also the earliest known computer , a mysterious device called the antikythera mechanism that kept track of astronomical changes and eclipses . today , it gives archaeologists vital information about the knowledge possessed by the ancient greeks . it is in this zone that we also begin to find aircraft and submarines , such as those from the world wars . plunging as deep as 200 feet , we can find some of the earliest and rarest signs of human history . prior to 5,000 years ago , there was a lot more dry land because glaciers trapped much of the water that now forms the sea . our ancestors spread across these lands , and so on the sea floor , we find their camps , stone tools , and the bones of animals they hunted . these sites give us invaluable knowledge about our ancestor 's migration patterns , hunting methods , and technologies . in the deepest zone , no human has ever walked . this area has been submerged since well before mankind evolved . the only artifacts we find are those that have drifted down from above , like nasa 's saturn v rocket engines at 14,000 feet , and the deepest shipwrecks . the ocean is like a huge underwater museum that constantly adds to our knowledge about humanity . with only a fraction of it explored , discoveries are sure to continue long into the future .
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these sites give us invaluable knowledge about our ancestor 's migration patterns , hunting methods , and technologies . in the deepest zone , no human has ever walked . this area has been submerged since well before mankind evolved .
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what is the deepest zone in the ocean that humans once walked ?
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back in ancient rome , the philosopher cicero described gratitude as the mother of all virtues . this concept of being thankful has been stressed in religion and philosophy for a long time . back in 1820 scottish philosopher thomas brown defined gratitude as “ that delightful emotion of love to him who has conferred a kindness on us. ” but scientifically , gratitude doesn ’ t qualify as a basic emotion like joy , sadness or anger . there ’ s no universal facial expression for it . as an emotion , gratitude is a little hard to define . today the oxford dictionary defines gratitude as “ the quality or condition of being thankful ; the appreciation of an inclination to return kindness. ” and we ’ ve only really started to study gratitude scientifically in the past 30 years . in a 2015 study , participants were asked to imagine how they would feel if a complete stranger saved their life . i mean , how would you feel ? the participants had to rate how grateful they were to strangers who provided them with gifts of food and clothing – all while they had their brain scanned in an fmri machine . researchers found their ratings of gratitude positively correlated with activity in brain areas associated with fairness and value judgements . it makes sense because gratitude is often thought of as a moral emotion . there are even benefits in just noting how grateful you are . another study asked people to write down three things that went well that day and why for one week . at the end of the week people were slightly happier than at the beginning , and over time , their happiness scores kept improving . after one month they were 5 % happier and after six months they were 9 % happier . just from one week of writing a journal . a similar study with participants with heart disease found that keeping a gratitude journal increased their heart health and quality of sleep , perhaps because it reduces stress . “ counting your blessings ” quite literally makes people happier and healthier . and some people are even hardwired to be more thankful . in a recent study of 77 couples , those with a particular genetic variation that affects the secretion of oxytocin expressed more gratitude towards their partners . oxytocin is thought to play a big role in promoting close social bonds , so gratitude is part of the glue that keeps these relationships together . so if you think it ’ s the thought that counts , think again . science shows there are some pretty amazing benefits to our mind , body and relationships when we say those two small words – thank you .
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it makes sense because gratitude is often thought of as a moral emotion . there are even benefits in just noting how grateful you are . another study asked people to write down three things that went well that day and why for one week . at the end of the week people were slightly happier than at the beginning , and over time , their happiness scores kept improving .
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7. who are you grateful for or to ? take a few minutes and write them a personal note . consider delivering it .
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translator : tom carter reviewer : bedirhan cinar dialogue gives a story color , makes it exciting and moves it forward . romeo : o , wilt thou leave me so unsatisfied ? juliet : what satisfaction canst thou have tonight ? romeo : the exchange of thy love 's faithful vows for mine . without dialogue : ( cricket sounds ) so what goes into writing effective dialogue ? well , there are social skills : making friends , solving conflicts , being pleasant and polite . we wo n't be using any of those today . instead , we 'll be working on -- let 's call them `` anti-social skills . '' if you 're a writer , you may already have a few of these . the first is eavesdropping . if you 're riding a bus and hear an interesting conversation , you could write it all down . of course , when you write fiction , you 're not describing real people , you 're making up characters . but sometimes the words you overhear can give you ideas . `` i did not , '' says one person . `` i saw you , '' the other replies . who might be saying those words ? maybe it 's two kids in a class , and the boy thinks the girl pushed him . maybe it 's a couple , but one of them is a vampire , and the woman vampire saw the man flirting with a zombie . or maybe not . maybe the characters are a teenager and his mother , and they 're supposed to be vegetarians , but the mother saw him eating a burger . so let 's say you 've decided on some characters . this is anti-social skill number two : start pretending they 're real . what are they like ? where are they from ? what music do they listen to ? spend some time with them . if you 're on a bus , think about what they might be doing if they were there too . would they talk on the phone , listen to music , draw pictures , sleep ? what we say depends on who we are . an older person might speak differently than a younger person . someone from the south might speak differently than someone from the north . once you know your characters , you can figure out how they talk . at this stage , it 's helpful to use anti-social skill number three : muttering to yourself . when you speak your character 's words , you can hear whether they sound natural , and fix them if necessary . remember , most people are usually pretty informal when they speak . they use simple language and contractions . so , `` do not attempt to lie to me '' sounds more natural as `` do n't try to lie to me . '' also keep it short . people tend to speak in short bursts , not lengthy speeches . and let the dialogue do the work . ask yourself : do i really need that adverb ? for instance , `` 'your money or your life , ' she said threateningly . '' here , `` threateningly '' is redundant , so you can get rid of it . but if the words and the actions do n't match , an adverb can be helpful . `` 'your money or your life , ' she said lovingly . '' so , to recap : first , eavesdrop . next , pretend imaginary people are real . finally , mutter to yourself , and write it all down . you already have everything you need . this is fictional dialogue , or `` how to hear voices in your head . ''
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remember , most people are usually pretty informal when they speak . they use simple language and contractions . so , `` do not attempt to lie to me '' sounds more natural as `` do n't try to lie to me . ''
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most people tend to speak rather informally , using simple language , contractions , slang , etc . however , there are instances in which formal speech fits a character or a story . what kind of character might use an academic vocabulary and formal grammar ? also , in what kind of situation might a character adopt a formal speaking style ?
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thinking of getting a tattoo ? decorating your birthday suit would add another personal story to a history of tattoos stretching back at least 8000 years . tattooed mummies from around the world attest to the universality of body modification across the millennia , and to the fact that you really were stuck with it forever if your civilization never got around to inventing laser removal . a mummy from the chinchorro culture in pre-incan peru has a mustache tattooed on his upper lip . ötzi , mummified iceman of the alps , has patterned charcoal tats along his spine , behind his knee and around his ankles , which might be from an early sort of acupuncture . the mummy of amunet , a priestess in middle kingdom egypt , features tattoos thought to symbolize sexuality and fertility . even older than the mummies , figurines of seemingly tattooed people , and tools possibly used for tattooing date back tens of thousands of years . tattoos do n't have one historical origin point that we know of , but why do we english speakers call them all tattoos ? the word is an anglophonic modification of `` tatao , '' a polynesian word used in tahiti , where english captain james cook landed in 1769 and encountered heavily tattooed men and women . stories of cook 's findings and the tattoos his crew acquired cemented our usage of `` tattoo '' over previous words like `` scarring , '' `` painting , '' and `` staining , '' and sparked a craze in victorian english high society . we might think of victorians having victorian attitudes about such a risque thing , and you can find such sentiments , and even bans , on tattooing throughout history . but while publicly some brits looked down their noses at tattoos , behind closed doors and away from their noses , lots of people had them . reputedly , queen victoria had a tiger fighting a python , and tattoos became very popular among cook 's fellow soldiers , who used them to note their travels . you crossed the atlantic ? get an anchor . been south of the equator ? time for your turtle tat . but westerners sported tattoos long before meeting the samoans and maori of the south pacific . crusaders got the jerusalem cross so if they died in battle , they 'd get a christian burial . roman soldiers on hadrian 's wall had military tattoos and called the picts beyond it `` picts , '' for the pictures painted on them . there 's also a long tradition of people being tattooed unwillingly . greeks and romans tattooed slaves and mercenaries to discourage escape and desertion . criminals in japan were tattooed as such as far back as the 7th century . most infamously , the nazis tattooed numbers on the chest or arms of jews and other prisoners at the auschwitz concentration camp in order to identify stripped corpses . but tattoos forced on prisoners and outcasts can be redefined as people take ownership of that status or history . primo levi survived auschwitz and wore short sleeves to germany after the war to remind people of the crime his number represented . today , some holocaust survivors ' descendants have their relatives numbers ' tattooed on their arms . the torah has rules against tattoos , but what if you want to make indelible what you feel should never be forgotten ? and those criminals and outcasts of japan , where tattooing was eventually outlawed from the mid-19th century to just after world war ii , added decoration to their penal tattoos , with designs borrowed from woodblock prints , popular literature and mythical spirtual iconography . yakuza gangs viewed their outsider tattoos as signs of lifelong loyalty and courage . after all , they lasted forever and it really hurt to get them . for the maori , those tattoos were an accepted mainstream tradition . if you shied away from the excruciating chiseling in of your moko design , your unfinished tattoo marked your cowardice . today , unless you go the traditional route , your tattoo artist will probably use a tattoo machine based on the one patented by samuel o'reilly in 1891 , itself based on thomas edison 's stencil machine from 1876 . but with the incredibly broad history of tattoos giving you so many options , what are you going to get ? this is a bold-lined expression of who you are , or you want to appear to be . as the naturalist aboard cook 's ship said of the tataoed tahitians , `` everyone is marked , thus in different parts of his body , according maybe to his humor or different circumstances of his life . '' maybe your particular humor and circumstances suggest getting a symbol of cultural heritage , a sign of spirituality , sexual energy , or good old-fashioned avant-garde defiance . a reminder of a great accomplishment , or of how you think it would look cool if hulk hogan rode a rhino . it 's your expression , your body , so it 's your call . just two rules : you have to find a tattooist who wo n't be ashamed to draw your idea , and when in doubt , you can never go wrong with `` mom . ''
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thinking of getting a tattoo ? decorating your birthday suit would add another personal story to a history of tattoos stretching back at least 8000 years .
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where does the word tattoo come from ?
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the biggest kidney stone on record weighed more than a kilogram and was 17 centimeters in diameter . the patient did n't actually swallow a stone the size of a coconut . kidney stones form inside the body , but unfortunately , they 're extremely painful to get out . a kidney stone is a hard mass of crystals that can form in the kidneys , ureters , bladder , or urethra . urine contains compounds that consist of calcium , sodium , potassium , oxalate , uric acid , and phosphate . if the levels of these particles get too high , or if urine becomes too acidic or basic , the particles can clump together and crystallize . unless the problem is addressed , the crystals will gradually grow over a few weeks , months , or even years , forming a detectable stone . calcium oxalate is the most common type of crystal to form this way , and accounts for about 80 % of kidney stones . less common kidney stones are made of calcium phosphate , or uric acid . a slightly different type of stone made of the minerals magnesium ammonium phosphate , or struvite , can be caused by bacterial infection . and even rarer stones can result from genetic disorders or certain medications . a kidney stone can go undetected until it starts to move . when a stone travels through the kidney and into the ureter , its sharp edges scratch the walls of the urinary tract . nerve endings embedded in this tissue transmit excruciating pain signals through the nervous system . and the scratches can send blood flowing into the urine . this can be accompanied by symptoms of nausea , vomiting , and a burning sensation while urinating . if a stone gets big enough to actually block the flow of urine , it can create an infection , or back flow , and damage the kidneys themselves . but most kidney stones do n't become this serious , or even require invasive treatment . masses less than five millimeters in diameter will usually pass out of the body on their own . a doctor will often simply recommend drinking large amounts of water to help speed the process along , and maybe taking some pain killers . if the stone is slightly larger , medications like alpha blockers can help by relaxing the muscles in the ureter and making it easier for the stone to get through . another medication called potassium citrate can help dissolve the stones by creating a less acidic urine . for medium-sized stones up to about ten millimeters , one option is pulverizing them with soundwaves . extracorporeal shock wave lithotripsy uses high-intensity pulses of focused ultrasonic energy aimed directly at the stone . the pulses create vibrations inside the stone itself and small bubbles jostle it . these combined forces crush the stone into smaller pieces that can pass out of the body more easily . but zapping a stone with sound does n't work as well if it 's simply too big . so sometimes , more invasive treatments are necessary . a rigid tube called a stent can be placed in the ureter to expand it . optical fibers can deliver laser pulses to break up the stone . stones can also be surgically removed through an incision in the patient 's back or groin . what about just avoiding kidney stones in the first place ? for people prone to them , their doctor may recommend drinking plenty of water , which dilutes the calcium oxalate and other compounds that eventually build up into painful stones . foods like potato chips , spinach , rhubarb , and beets are high in oxalate , so doctors might advise limiting them . even though calcium is often found in stones , calcium in foods and beverages can actually help by binding to oxalate in the digestive tract before it can be absorbed and reach the kidneys . if you do end up with a kidney stone , you 're not alone . data suggests that rates are rising , but that world record probably wo n't be broken any time soon .
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and even rarer stones can result from genetic disorders or certain medications . a kidney stone can go undetected until it starts to move . when a stone travels through the kidney and into the ureter , its sharp edges scratch the walls of the urinary tract .
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why might the rate of kidney stone formation be changing in the human population ?
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around 1159 a.d. , a mathematician called bhaskara the learned sketched a design for a wheel containing curved reservoirs of mercury . he reasoned that as the wheels spun , the mercury would flow to the bottom of each reservoir , leaving one side of the wheel perpetually heavier than the other . the imbalance would keep the wheel turning forever . bhaskara 's drawing was one of the earliest designs for a perpetual motion machine , a device that can do work indefinitely without any external energy source . imagine a windmill that produced the breeze it needed to keep rotating . or a lightbulb whose glow provided its own electricity . these devices have captured many inventors ' imaginations because they could transform our relationship with energy . for example , if you could build a perpetual motion machine that included humans as part of its perfectly efficient system , it could sustain life indefinitely . there 's just one problem . they do n't work . ideas for perpetual motion machines all violate one or more fundamental laws of thermodynamics , the branch of physics that describes the relationship between different forms of energy . the first law of thermodynamics says that energy ca n't be created or destroyed . you ca n't get out more energy than you put in . that rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed . there would n't be any left over to power a car or charge a phone . but what if you just wanted the machine to keep itself moving ? inventors have proposed plenty of ideas . several of these have been variations on bhaskara 's over-balanced wheel with rolling balls or weights on swinging arms . none of them work . the moving parts that make one side of the wheel heavier also shift its center of mass downward below the axle . with a low center of mass , the wheel just swings back and forth like a pendulum , then stops . what about a different approach ? in the 17th century , robert boyle came up with an idea for a self-watering pot . he theorized that capillary action , the attraction between liquids and surfaces that pulls water through thin tubes , might keep the water cycling around the bowl . but if the capillary action is strong enough to overcome gravity and draw the water up , it would also prevent it from falling back into the bowl . then there are versions with magnets , like this set of ramps . the ball is supposed to be pulled upwards by the magnet at the top , fall back down through the hole , and repeat the cycle . this one fails because like the self-watering pot , the magnet would simply hold the ball at the top . even if it somehow did keep moving , the magnet 's strength would degrade over time and eventually stop working . for each of these machines to keep moving , they 'd have to create some extra energy to nudge the system past its stopping point , breaking the first law of thermodynamics . there are ones that seem to keep going , but in reality , they invariably turn out to be drawing energy from some external source . even if engineers could somehow design a machine that did n't violate the first law of thermodynamics , it still would n't work in the real world because of the second law . the second law of thermodynamics tells us that energy tends to spread out through processes like friction . any real machine would have moving parts or interactions with air or liquid molecules that would generate tiny amounts of friction and heat , even in a vacuum . that heat is energy escaping , and it would keep leeching out , reducing the energy available to move the system itself until the machine inevitably stopped . so far , these two laws of thermodynamics have stymied every idea for perpetual motion and the dreams of perfectly efficient energy generation they imply . yet it 's hard to conclusively say we 'll never discover a perpetual motion machine because there 's still so much we do n't understand about the universe . perhaps we 'll find new exotic forms of matter that 'll force us to revisit the laws of thermodynamics . or maybe there 's perpetual motion on tiny quantum scales . what we can be reasonably sure about is that we 'll never stop looking . for now , the one thing that seems truly perpetual is our search .
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you ca n't get out more energy than you put in . that rules out a useful perpetual motion machine right away because a machine could only ever produce as much energy as it consumed . there would n't be any left over to power a car or charge a phone .
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which of the following correctly describes a perpetual motion machine ?
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fish are in trouble . the cod population off canada 's east coast collapsed in the 1990s , intense recreational and commercial fishing has decimated goliath grouper populations in south florida , and most populations of tuna have plummeted by over 50 % , with the southern atlantic bluefin on the verge of extinction . those are just a couple of many examples . overfishing is happening all over the world . how did this happen ? when some people think of fishing , they imagine relaxing in a boat and patiently reeling in the day 's catch . but modern industrial fishing , the kind that stocks our grocery shelves , looks more like warfare . in fact , the technologies they employ were developed for war . radar , sonar , helicopters , and spotter planes are all used to guide factory ships towards dwindling schools of fish . long lines with hundreds of hooks or huge nets round up massive amounts of fish , along with other species , like seabirds , turtles , and dolphins . and fish are hauled up onto giant boats , complete with onboard flash freezing and processing facilities . all of these technologies have enabled us to catch fish at greater depths and farther out at sea than ever before . and as the distance and depth of fishing have expanded , so has the variety of species we target . for example , the patagonian toothfish neither sounds nor looks very appetizing . and fishermen ignored it until the late 1970s . then it was rebranded and marketed to chefs in the u.s. as chilean sea bass , despite the animal actually being a type of cod . soon it was popping up in markets all over the world and is now a delicacy . unfortunately , these deep water fish do n't reproduce until they 're at least ten years old , making them extremely vulnerable to overfishing when the young are caught before they 've had the chance to spawn . consumer taste and prices can also have harmful effects . for example , shark fin soup is considered such a delicacy in china and vietnam that the fin has become the most profitable part of the shark . this leads many fishermen to fill their boats with fins leaving millions of dead sharks behind . the problems are n't unique to toothfish and sharks . almost 31 % of the world 's fish populations are overfished , and another 58 % are fished at the maximum sustainable level . wild fish simply ca n't reproduce as fast as 7 billion people can eat them . fishing also has impacts on broader ecosystems . wild shrimp are typically caught by dragging nets the size of a football field along the ocean bottom , disrupting or destroying seafloor habitats . the catch is often as little as 5 % shrimp . the rest is by-catch , unwanted animals that are thrown back dead . and coastal shrimp farming is n't much better . mangroves are bulldozed to make room for shrimp farms , robbing coastal communities of storm protection and natural water filtration and depriving fish of key nursery habitats . so what does it look like to give fish a break and let them recover ? protection can take many forms . in national waters , governments can set limits about how , when , where , and how much fishing occurs , with restrictions on certain boats and equipment . harmful practices , such as bottom trawling , can be banned altogether , and we can establish marine reserves closed to all fishing to help ecosystems restore themselves . there 's also a role for consumer awareness and boycotts to reduce wasteful practices , like shark finning , and push fishing industries towards more sustainable practices . past interventions have successfully helped depleted fish populations recover . there are many solutions . the best approach for each fishery must be considered based on science , respect for the local communities that rely on the ocean , and for fish as wild animals . and then the rules must be enforced . international collaboration is often needed , too , because fish do n't care about our borders . we need to end overfishing . ecosystems , food security , jobs , economies , and coastal cultures all depend on it .
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there are many solutions . the best approach for each fishery must be considered based on science , respect for the local communities that rely on the ocean , and for fish as wild animals . and then the rules must be enforced .
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what can communities do to ensure their local waters are fished sustainably ?
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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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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 .
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the destruction of the roman empire was a momentous occasion in art history . in the same way this connection was explained in this video , concisely explain a connection between an historical event and its effect on society .
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it starts with a tickle in your throat that becomes a cough . your muscles begin to ache , you grow irritable , and you lose your appetite . it 's official : you 've got the flu . it 's logical to assume that this miserable medley of symptoms is the result of the infection coursing through your body , but is that really the case ? what 's actually making you feel sick ? what if your body itself was driving this vicious onslaught ? you first get ill when a pathogen like the flu virus gets into your system , infecting and killing your cells . but this unwelcome intrusion has another effect : it alerts your body 's immune system to your plight . as soon as it becomes aware of infection , your body leaps to your defense . cells called macrophages charge in as the first line of attack , searching for and destroying the viruses and infected cells . afterwards , the macrophages release protein molecules called cytokines whose job is to recruit and organize more virus-busting cells from your immune system . if this coordinated effort is strong enough , it 'll wipe out the infection before you even notice it . but that 's just your body setting the scene for some real action . in some cases , viruses spread further , even into the blood and vital organs . to avoid this sometimes dangerous fate , your immune system must launch a stronger attack , coordinating its activity with the brain . that 's where those unpleasant symptoms come in , starting with the surging temperature , aches and pains , and sleepiness . so why do we experience this ? when the immune system is under serious attack , it secretes more cytokines , which trigger two responses . first , the vagus nerve , which runs through the body into the brain , quickly transmits the information to the brain stem , passing near an important area of pain processing . second , cytokines travel through the body to the hypothalamus , the part of the brain responsible for controlling temperature , thirst , hunger , and sleep , among other things . when it receives this message , the hypothalamus produces another molecule called prostaglandin e2 , which gears it up for war . the hypothalamus sends signals that instruct your muscles to contract and causes a rise in body temperature . it also makes you sleepy , and you lose your appetite and thirst . but what 's the point of all of these unpleasant symptoms ? well , we 're not yet sure , but some theorize that they aid in recovery . the rise in temperature can slow bacteria and help your immune system destroy pathogens . sleep lets your body channel more energy towards fighting infection . when you stop eating , your liver can take up much of the iron in your blood , and since iron is essential for bacterial survival , that effectively starves them . your reduced thirst makes you mildly dehydrated , diminishing transmission through sneezes , coughs , vomit , or diarrhea . though it 's worth noting that if you do n't drink enough water , that dehydration can become dangerous . even the body 's aches make you more sensitive , drawing attention to infected cuts that might be worsening , or even causing your condition . in addition to physical symptoms , sickness can also make you irritable , sad , and confused . that 's because cytokines and prostaglandin can reach even higher structures in your brain , disrupting the activity of neurotransmitters , like glutamate , endorphins , serotonin , and dopamine . this affects areas like the limbic system , which oversees emotions , and your cerebral cortex , which is involved in reasoning . so it 's actually the body 's own immune response that causes much of the discomfort you feel every time you get ill . unfortunately , it does n't always work perfectly . most notably , millions of people worldwide suffer from autoimmune diseases , in which the immune system treats normal bodily cues as threats , so the body attacks itself . but for the majority of the human race , millions of years of evolution have fine-tuned the immune system so that it works for , rather than against us . the symptoms of our illnesses are annoying , but collectively , they signify an ancient process that will continue barricading our bodies against the outside world for centuries to come .
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when the immune system is under serious attack , it secretes more cytokines , which trigger two responses . first , the vagus nerve , which runs through the body into the brain , quickly transmits the information to the brain stem , passing near an important area of pain processing . second , cytokines travel through the body to the hypothalamus , the part of the brain responsible for controlling temperature , thirst , hunger , and sleep , among other things .
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in experiments with rats when the vagus nerve is cut , some of the effects of inflammation are abolished such as depression . however , fever can persist . why do you think this is ?
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so holmium : holmium is a very interesting element because it has the highest magnetic moment of any known element in the periodic table , which is very high . this is basically the strength of the magnetic field which it ’ s producing , so it ’ s got lots of uses in magnetic materials for electronics for example . yeah it ’ s because it ’ s got the greatest number of unpaired electrons , and unpaired electrons is what gives rise to magnetism , which is why iron with unpaired electrons is known as a magnet .
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so holmium : holmium is a very interesting element because it has the highest magnetic moment of any known element in the periodic table , which is very high . this is basically the strength of the magnetic field which it ’ s producing , so it ’ s got lots of uses in magnetic materials for electronics for example .
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as steve explained , what is significant about holmium regarding its magnetic moment ?
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so you can see on the front of this instrument is a dome shaped device . that dome is a special vessel which is made so we can control the atmosphere inside and it is fabricated from beryllium metal . this is the beryllium which i don ’ t really want to get out . why not ? well , because it is a toxic chemical , a toxic metal . beryllium is an interesting element because most chemists don ’ t really know about it very much at all . so beryllium is a fantastic metal , it is really , really interesting , it ’ s got really lots of strange metallic properties , but one of the most important to me is that it is transparent to x-rays . so i can shine x-rays straight through the beryllium and the beryllium does not absorb it at all which most other metals especially those with higher molecular weights do . beryllium-laden dust has been shown to cause berylliosis which is actually an industrial lung disease which causes the formation of swollen nodules in the lungs called granulomas which is a bit gross , so i don ’ t really want to open up the jar . it ’ s near the beginning of the periodic table , but we rarely come across it . so at the moment we are at matt ’ s lab and we are doing some x-ray experiments on a really , really quite sensitive compound . so x-rays themselves are absorbed by everything , ok , so when we shoot it through the air it is absorbed by the air , so to measure the x-ray absorption of our compound which is sensitive to the air we need to be able to remove the air and encase it so we use beryllium to make a magic box around our sample , that the x-rays can come into , interact with our sample , and then exit without interacting with the material around them . so you can see on the front of this instrument , there is a dome shaped device , that dome , is a special vessel which is made so that we could control the atmosphere inside and it is fabricated from beryllium metal . i talk about in my lectures , i explain that beryllium chloride the molecule that has three atoms , two chlorine atoms and one beryllium atom , has the three atoms arranged in the row , so it is a straight molecule so called linear molecule . i have never seen beryllium chloride . chemists use it on x-ray defractometers because actually it is so lightweight it is actually got atomic number 4 . the beryllium allows the x-rays to come in and out without interacting at all . it is a fantastic device it is really useful for really sensitive chemistry , it is a really beautiful application . the cost of that beryllium though , that is significant , that small beryllium sample cost 15,000 euros . it only has four protons and a number of neutrons so if x-rays fall on atoms of beryllium they are not scattered very much so it ’ s like the difference between shining light through a glass window and if you made it out of a heavy material it would be like , shining through paper , it would be scattered you wouldn ’ t get a good image . i ’ m hoping to actually do some chemistry with beryllium which is why i ’ ve bought it . it is pretty toxic so we are going to have to be very , very careful . you can ’ t actually breathe in the dust at all , cause even actually one exposure has shown with some people one exposure is enough to cause this sort of sensitive reaction . but beryllium is very poisonous so if you do use these beryllium windows , you have to be careful not to lick your fingers . well good chemists shouldn ’ t lick their fingers anyway .
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so you can see on the front of this instrument , there is a dome shaped device , that dome , is a special vessel which is made so that we could control the atmosphere inside and it is fabricated from beryllium metal . i talk about in my lectures , i explain that beryllium chloride the molecule that has three atoms , two chlorine atoms and one beryllium atom , has the three atoms arranged in the row , so it is a straight molecule so called linear molecule . i have never seen beryllium chloride . chemists use it on x-ray defractometers because actually it is so lightweight it is actually got atomic number 4 .
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how many electrons does a beryllium atom have in its outer shell ?
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translator : andrea mcdonough reviewer : bedirhan cinar pretty much everyone loves eating pizza , but it can be a messy business . pizza is soft and bendable . so how can you stop all that cheese from falling off ? you might know some tricks : you can use two hands -- not so classy , or you can use a paper plate and allow only the tip of the pizza to peek out . there 's one other trick , though : holding the crust , you can sort of fold the slice down the middle . now the tip of the pizza is n't falling over , and you can eat it without getting tomato sauce all over yourself or accidentally biting off some of that paper plate . but why should the tip stay up just because you bent the crust ? to understand this , you need to know two things : a little bit about the math of curved shapes and a little about the physics of thin sheets . first , the math . suppose i have a flat sheet made out of rubber . it 's really thin and bendable , so it 's easy to roll into a cylinder . i do n't need to stretch the sheet at all , just bend it . this property where one shape can be transformed into another without stretching or crumpling , is called isometry . a mathematician would say that a flat sheet is isometric to a cylinder . but not all shapes are isometric . if i try to turn my flat sheet into part of a sphere , there 's no way i can do it . you can check this for yourself , by trying to fit a flat sheet of paper onto a soccer ball without stretching or crumpling the paper . it 's just not possible . so a mathematician would say that a flat sheet and a sphere are n't isometric . there 's one more familiar shape that is n't isometric to any of the shapes we 've seen so far : a potato chip . potato chip shapes are n't isometric to flat sheets . if you want to get a flat piece of rubber into the shape of a potato chip , you need to stretch it -- not just bend it , but stretch it as well . so , that 's the math . not so hard , right ? now for the physics . it can be summed up in one sentence : thin sheets are easy to bend but hard to stretch . this is really important . thin sheets are easy to bend but hard to stretch . remember when we rolled our flat sheet of rubber into a cylinder ? that was n't hard , right ? but imagine how hard you 'd have pull on the sheet to increase its area by 10 percent . it would be pretty difficult . the point is that bending a thin sheet takes a relatively small amount of force , but stretching or crumbling a thin sheet is much harder . now , finally , we get to talk about pizza . suppose you go down to the pizzeria and buy yourself a slice . you pick it up from the crust , first , without doing the fold . because of gravity , the slice bends downwards . pizza is pretty thin , after all , and we know that thin sheets are easy to bend . you ca n't get it in your mouth , cheese and tomato sauce dripping everywhere -- it 's a big mess . so you fold the crust . when you do , you force the pizza into something like a taco shape . that 's not hard to do -- after all , this shape is isometric to the original pizza , which was flat . but imagine what would happen if the pizza were to droop down while you 're bending it . now it looks like a droopy taco . and what does a droopy taco look like ? a potato chip ! but we know that potato chips are not isometric to flat pieces of rubber or flat pizzas , and that means that in order to get into the shape it 's in now , the slice of pizza had to stretch . since the pizza is thin , this takes a lot of force , compared to the amount of force it takes to bend the pizza in the first place . so , what 's the conclusion ? when you fold the pizza at the crust , you make it into a shape where a lot of force is needed to bend the tip down . often gravity is n't strong enough to provide this force . that was kind of a lot of information , so let 's do a quick backwards recap . when pizza is folded at the crust , gravity is n't strong enough to bend the tip . why ? because stretching a pizza is hard . and to bend the tip downwards , the pizza would have to stretch , because the shape the pizza would be in , the droopy taco shape , is n't isometric to the original flat pizza . why ? because of math . as the pizza example shows , we can learn a lot by looking at the mathematical properties of different shapes . and it 's especially nice when those shapes happen to be pizza slices .
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if i try to turn my flat sheet into part of a sphere , there 's no way i can do it . you can check this for yourself , by trying to fit a flat sheet of paper onto a soccer ball without stretching or crumpling the paper . it 's just not possible .
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many of the ideas in curved-surface math ( which is technically called “ differential geometry ” ) first originated when people tried to draw accurate maps of the earth ’ s surface . maps are drawings of pieces of the surface of the earth - which is approximately spherical - on flat pieces of paper . but we know that spheres and flat pieces of paper aren ’ t isometric , so you can ’ t transform one into the other without stretching . what consequences do you think this might have for the shapes of countries on a map of the world ? it helps to visualize this problem if you carefully peel a mandarin orange , and then try to lay the strips down flat on a table .
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sometimes when a fish is reeled up to the surface it will appear inflated , with its eyes bulging out of their sockets and its stomach projecting out of its mouth , as if its been blown up like a balloon . this type of bodily damage , caused by rapid changes in pressure , is called barotrauma . under the sea , pressure increases by 14.7 pounds per square inch for every 33 foot increase in depth . so , take the yelloweye rockfish , which can live as deep as 1800 feet , where there 's over 800 pounds of pressure on every square inch . that 's equivalent to the weight of a polar bear balancing on a quarter . now , boyle 's gas law states that the volume of a gas is inversely related to pressure . so , any air-filled spaces , like a rockfish 's swim bladder , or human lungs , will compress as they descend deeper and expand as they ascend . after a fish bites a fisherman 's hook and is quickly reeled up to the surface , the air in its swim bladder begins to expand . its rapid expansion actually forces the fish 's stomach out of its mouth , while the increased internal pressure pushes its eyes out of their sockets , a condition called exophthalmia . sometimes rockfish eyes will even have a crystallized appearance from corneal emphysemas , little gas bubbles that build up inside the cornea . thankfully , a scuba diver does n't have a closed swim bladder to worry about . a diver can regulate pressure in her lungs by breathing out as she ascends , but must be wary of other laws of physics that are at play under the sea . henry 's law states that the amount of a gas that dissolves in a liquid is proportional to its partial pressure . the air a diver breathes is 78 % nitrogen . at a higher pressure under the sea , the nitrogen from the air in a scuba tank diffuses into a diver 's tissues in greater concentrations than it would on land . if the diver ascends too quickly , this built up nitrogen can come out of solution and form microbubbles in her tissues , blood and joints , causing decompression sickness , aka the bends . this is similar to the fizz of carbon dioxide coming out of your soda . gas comes out of solution when the pressure 's released . but for a diver , the bubbles cause severe pain and sometimes even death . divers avoid falling victim to the bends by rising slowly and taking breaks along the way , called decompression stops , so the gas has time to diffuse back out of their tissues and to be released through their breath . just as a diver needs decompression , for a fish to recover , it needs recompression , which can be accomplished by putting it back in the sea . but that does n't mean that fish should just be tossed overboard . an inflated body will float and get scooped up by a hungry sea lion or pecked at by seagulls . there 's a common myth that piercing its stomach with a needle will let air escape , allowing the fish to swim back down on its own . but that is one balloon that should n't be popped . to return a fish properly to its habitat , fisherman can use a descending device instead to lower it on a fishing line and release it at the right depth . as it heads home and recompression reduces gas volume , its eyes can return to their sockets and heal , and its stomach can move back into place . this fish will live to see another day , once more free to swim , eat , reproduce and replenish the population .
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this type of bodily damage , caused by rapid changes in pressure , is called barotrauma . under the sea , pressure increases by 14.7 pounds per square inch for every 33 foot increase in depth . so , take the yelloweye rockfish , which can live as deep as 1800 feet , where there 's over 800 pounds of pressure on every square inch .
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under the sea pressure increases by 14.7 pounds per square inch for every _____ foot increase in depth .
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each year in the united states , players of sports and recreational activities receive between 2.5 and 4 million concussions . how dangerous are all those concussions ? the answer is complicated , and lies in how the brain responds when something strikes it . the brain is made of soft fatty tissue , with a consistency something like jello . inside its protective membranes and the skull 's hard casing , this delicate organ is usually well-shielded . but a sudden jolt can make the brain shift and bump against the skull 's hard interior , and unlike jello , the brain 's tissue is n't uniform . it 's made of a vast network of 90 billion neurons , which relay signals through their long axons to communicate throughout the brain and control our bodies . this spindly structure makes them very fragile so that when impacted , neurons will stretch and even tear . that not only disrupts their ability to communicate but as destroyed axons begin to degenerate , they also release toxins causing the death of other neurons , too . this combination of events causes a concussion . the damage can manifest in many different ways including blackout , headache , blurry vision , balance problems , altered mood and behavior , problems with memory , thinking , and sleeping , and the onset of anxiety and depression . every brain is different , which explains why people 's experiences of concussions vary so widely . luckily , the majority of concussions fully heal and symptoms disappear within a matter of days or weeks . lots of rest and a gradual return to activity allows the brain to heal itself . on the subject of rest , many people have heard that you 're not supposed to sleep shortly after receiving a concussion because you might slip into a coma . that 's a myth . so long as doctors are n't concerned there may also be a more severe brain injury , like a brain bleed , there 's no documented problem with going to sleep after a concussion . sometimes , victims of concussion can experience something called post-concussion syndrome , or pcs . people with pcs may experience constant headaches , learning difficulties , and behavioral symptoms that even affect their personal relationships for months or years after the injury . trying to play through a concussion , even for only a few minutes , or returning to sports too soon after a concussion , makes it more likely to develop pcs . in some cases , a concussion can be hard to diagnose because the symptoms unfold slowly over time . that 's often true of subconcussive impacts which result from lower impact jolts to the head than those that cause concussions . this category of injury does n't cause noticable symptoms right away , but can lead to severe degenerative brain diseases over time if it happens repeatedly . take soccer players , who are known for repeatedly heading soccer balls . using a technique called diffusion tensor imaging , we 're beginning to find out what effect that has on the brain . this method allows scientists to find large axon bundles and see how milder blows might alter them structurally . in 2013 , researchers using this technique discovered that athletes who had headed the ball most , about 1,800 times a year , had damaged the structural integrity of their axon bundles . the damage was similar to how a rope will fail when the individual fibers start to fray . those players also performed worse on short-term memory tests , so even though no one suffered full-blown concussions , these subconcussive hits added up to measurable damage over time . in fact , researchers know that an overload of subconcussive hits is linked to a degenerative brain disease known as chronic traumatic encephalopathy , or cte . people with cte suffer from changes in their mood and behavior that begin appearing in their 30s or 40s followed by problems with thinking and memory that can , in some cases , even result in dementia . the culprit is a protein called tau . usually , tau proteins support tiny tubes inside our axons called microtubules . it 's thought that repeated subconcussive hits damage the microtubules , causing the tau proteins to dislodge and clump together . the clumps disrupt transport and communication along the neuron and drive the breakdown of connections within the brain . once the tau proteins start clumping together , they cause more clumps to form and continue to spread throughout the brain , even after head impacts have stopped . the data show that at least among football players , between 50 and 80 % of concussions go unreported and untreated . sometimes that 's because it 's hard to tell a concussion has occurred in the first place . but it 's also often due to pressure or a desire to keep going despite the fact that something 's wrong . this does n't just undermine recovery . it 's also dangerous . our brains are n't invincible . they still need us to shield them from harm and help them undo damage once it 's been done .
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those players also performed worse on short-term memory tests , so even though no one suffered full-blown concussions , these subconcussive hits added up to measurable damage over time . in fact , researchers know that an overload of subconcussive hits is linked to a degenerative brain disease known as chronic traumatic encephalopathy , or cte . people with cte suffer from changes in their mood and behavior that begin appearing in their 30s or 40s followed by problems with thinking and memory that can , in some cases , even result in dementia .
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which of the following statements about chronic traumatic encephalopathy is false ?
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translator : andrea mcdonough reviewer : bedirhan cinar miss gayle 's 5 steps to slam poetry , a lesson of transformation . step 1 : write it all down . `` take one memory , explore it like a new land , '' the visiting poet tells the class . `` do n't leave anything out . '' tyler sits in this high school workshop , dizzy with where to start . memories wander in and out of his heart like vagrants searching for home . he bends to his desk , he writes , `` the snow goes black when the moon turns its eyes away , all paper is yellow , all letters spell eviction note , mama 's lies are footsteps too many to count . making excuses on black snow . 'i paid the rent , this is your room forever , baby . i love you . ' but , she would n't even look at me . '' step 2 : read out loud . as he writes , his lips try on words then toss them out like bad tenants . he pushes his desk back , stands . `` aunt jocelyn 's rice pudding was sweet , but that 's not what i want to write . have you ever been so cold your hair becomes an icicle ? your little sister 's fear of the dark freezes on her lips like she 's kissed the ice tray ? how hungry have you been ? '' step 3 : cut the fat . abandon extra words . his pen becomes a machete , slashing ands , thens , becauses . step 4 : read out loud , again . the 11th grade boy makes sure step 3 's cuts were n't too deep . step 5 : add flava . juice , power , movement , emotion . `` vanilla flavoring is the secret to my aunt 's pudding . i kick out a few raisins but leave one or two . life needs some bitter to man up the sweet . '' his hands reach out like shells to hold our disbelief . is this tyler speaking ? the one who keeps his eyes on the floor like they 're carrying something heavy ? voice rattles windows . `` i am free now . '' body quivers with the pulse of each word . `` the sun 's joy melts snow . '' fingers trace the curve of his jaw . `` my aunt 's face was warm as a water heater when she let us in that night . '' our boy is done , his transformation complete . step 1 : write it all down . step 2 : read out loud . step 3 : cut the fat . step 4 : read out loud . step 5 : add flava . tyler 's first poem takes residence in his heart . he flings his arms wide like an open door . welcome home !
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but , she would n't even look at me . '' step 2 : read out loud . as he writes , his lips try on words then toss them out like bad tenants .
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what 's ms. gayle 's step 2 ?
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for many of us , a typical day involves interactions with hundreds of companies . buying their goods , using their services , even wearing their names . corporations and companies have become such a familiar part of the modern landscape that it 's easy to forget they 're artificial entities created to allow real people to do business . but there are some types of companies that are n't engaged in any business at all . instead , these anonymous companies exist mainly to disguise people doing things they 'd rather not have the public know about . and these people go to great lengths to hide any links between their names and the companies they own . the life of an anonymous company usually begins in what 's known as a secrecy jurisdiction , a place whose laws allow new companies to be registered with little disclosure about who owns or controls them . some may simply not require collecting that information . others may collect it , but make it nearly inaccessible to anyone else . and the lack of incentive to verify companies ' real owners makes it easy for people to cover their tracks . for example , someone may register a company in the name of a relative , an associate , or even a nominee director who acts on instruction from the company 's actual owner while keeping their name confidential . once registered , a company can do many of the same things as a human being , like opening bank accounts , buying and owning assets , and transferring money . what 's more , it can be listed as the owner of other companies , including ones opened in places with stricter disclosure rules . this allows someone to create a complex world-wide chain of ownership that can take years to unravel . a company based in the u.s. may be wholly owned by another one in liechtenstein , which is owned in turn by one in the british virgin islands . and an anonymous company can be transferred to a new owner at any time with no public record of the change . so why all the anonymity ? defenders of financial secrecy argue that wealthy individuals need it to avoid intrusive media attention and threats to personal security . but while this may sometimes be justified , anonymous companies play a role in almost every type of economic crime , including many major corruption cases . they are used by corporations evading taxes , rogue governments skirting sanctions , terrorists buying arms , and dictators financing wars . organized crime groups launder their profits through anonymous companies . corrupt government officials award valuable contracts to corporations they secretly own . international oligarchs with criminal connections or questionable pasts have used anonymous companies to discretely buy luxury apartments in cities like london and new york city , keeping them as safe stores of wealth . and even when criminals are convicted , their anonymously held assets may be difficult for authorities to locate or seize , making it harder for victims to be compensated . efforts are now underway to chip away at these crime-enabling mechanisms . international authorities and ngos have called for requiring companies to state who ultimately makes their decisions and benefits from their assets . but while progress is being made , international cooperation has been difficult to achieve , as governments that profit from registering anonymous companies are reluctant to lose business . and some of the most popular places for this practice are located not on remote , tropical tax shelters , but within the same advanced nations which claim to be leading the fight for global financial transparency . but still , it 's a fight worth fighting . closing the legal loopholes that enable anonymous companies would help us cut down on corruption and illegal activity . it would also allow us , as the general public , to better understand the flow of enormous sums of money that impact politics , our daily lives , and the health of our world .
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they are used by corporations evading taxes , rogue governments skirting sanctions , terrorists buying arms , and dictators financing wars . organized crime groups launder their profits through anonymous companies . corrupt government officials award valuable contracts to corporations they secretly own .
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how can anonymous companies be used to launder money and facilitate crimes ?
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deep inside yale university 's beinecke rare book and manuscript library lies the only copy of a 240-page tome . recently carbon dated to around 1420 , its vellum pages features looping handwriting and hand-drawn images seemingly stolen from a dream . real and imaginary plants , floating castles , bathing women , astrology diagrams , zodiac rings , and suns and moons with faces accompany the text . this 24x16 centimeter book is called the voynich manuscript , and its one of history 's biggest unsolved mysteries . the reason why ? no one can figure out what it says . the name comes from wilfrid voynich , a polish bookseller who came across the document at a jesuit college in italy in 1912 . he was puzzled . who wrote it ? where was it made ? what do these bizarre words and vibrant drawings represent ? what secrets do its pages contain ? he purchased the manuscript from the cash-strapped priest at the college , and eventually brought it to the u.s. , where experts have continued to puzzle over it for more than a century . cryptologists say the writing has all the characteristics of a real language , just one that no one 's ever seen before . what makes it seem real is that in actual languages , letters and groups of letters appear with consistent frequencies , and the language in the voynich manuscript has patterns you would n't find from a random letter generator . other than that , we know little more than what we can see . the letters are varied in style and height . some are borrowed from other scripts , but many are unique . the taller letters have been named gallows characters . the manuscript is highly decorated throughout with scroll-like embellishments . it appears to be written by two or more hands , with the painting done by yet another party . over the years , three main theories about the manuscript 's text have emerged . the first is that it 's written in cypher , a secret code deliberately designed to hide secret meaning . the second is that the document is a hoax written in gibberish to make money off a gullible buyer . some speculate the author was a medieval con man . others , that it was voynich himself . the third theory is that the manuscript is written in an actual language , but in an unknown script . perhaps medieval scholars were attempting to create an alphabet for a language that was spoken but not yet written . in that case , the voynich manuscript might be like the rongorongo script invented on easter island , now unreadable after the culture that made it collapsed . though no one can read the voynich manuscript , that has n't stopped people from guessing what it might say . those who believe the manuscript was an attempt to create a new form of written language speculate that it might be an encyclopedia containing the knowledge of the culture that produced it . others believe it was written by the 13th century philosopher roger bacon , who attempted to understand the universal laws of grammar , or in the 16th century by the elizabethan mystic john dee , who practiced alchemy and divination . more fringe theories that the book was written by a coven of italian witches , or even by martians . after 100 years of frustration , scientists have recently shed a little light on the mystery . the first breakthrough was the carbon dating . also , contemporary historians have traced the provenance of the manuscript back through rome and prague to as early as 1612 , when it was perhaps passed from holy roman emperor rudolf ii to his physician , jacobus sinapius . in addition to these historical breakthroughs , linguistic researchers recently proposed the provisional identification of a few of the manuscript 's words . could the letters beside these seven stars spell tauran , a name for taurus , a constellation that includes the seven stars called the pleiades ? could this word be centaurun for the centaurea plant in the picture ? perhaps , but progress is slow . if we can crack its code , what might we find ? the dream journal of a 15th-century illustrator ? a bunch of nonsense ? or the lost knowledge of a forgotten culture ? what do you think it is ?
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real and imaginary plants , floating castles , bathing women , astrology diagrams , zodiac rings , and suns and moons with faces accompany the text . this 24x16 centimeter book is called the voynich manuscript , and its one of history 's biggest unsolved mysteries . the reason why ?
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the man who discovered the voynich manuscript was :
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translator : andrea mcdonough reviewer : bedirhan cinar in physics , the concepts of work and power help us understand and explain lots of things in our universe . let 's start with work . positive work is the energy we put into a system , and negative work is energy that is transferred out . think of positive work as money being added to your bank account , and negative work as money taken out . in the metric system , work and energy are measured in joules . as an example , let 's take a beautiful , old , mechanical grandfather clock . we transfer energy into the clock when we turn the crank to raise the heavy metal cylinders inside the clock . when we do this , we are doing positive work , adding energy to the clock , and that energy is stored as gravitational potential energy . we can calculate the amount of work done by multiplying the force we apply times the distance over which we apply the force . to raise the metal cylinders , we need to apply a force equal to their weight . that is , equal to the force of gravity pulling downward on the cylinders . these cylinders weight 300 newtons , which is pretty heavy , about as much as a small child , and if we lift them 1/2 meter , then we do 300 newtons times 1/2 meter or 150 joules of work . power is the rate at which energy is transferred . when we say rate , we mean the amount of energy transferred per unit of time . in the metric system , power is measured in joules per second , or watts . the term watt goes back to james watt , who came up with the concept of horsepower to measure the amount of power produced by a typical work horse . james watt was a producer of industrial steam engines , and he wanted his potential customers to be able to make comparisons between his steam engines and a familiar quanity , the power they could get from a working horse . it was such a useful idea that the metric system unit for power , the watt , is named after james watt . following in james watt 's footsteps , let 's compare the amount of power it takes to run this grandfather clock to the power we 'd need to run a bright , 100-watt light bulb . we can measure the power a person uses to wind the clock by dividing the amount of work they did by the time it took them to do it . if it takes 1 minute , or 60 seconds , to lift the weights , then they are doing 150 joules divided by 60 seconds , or 2.5 joules per second of work . they are adding energy to the clock in the rate of 2.5 watts . you would need about 40 times as much to run a bright , 100-watt light bulb . before we let the clock run , the energy is stored as gravitational potential energy of the cylinders . it 's like your bank account when you have just deposited money . but if we let the clock run , the cylinders slowly move downward . energy is leaving the clock . in fact , when the cylinders get to the bottom , all the energy that we put in will have left . so how much power does the clock use ? that is , how many joules of energy per second leave the clock if it takes 5 days for the cylinders to return to their original position ? we can figure this out because we already know how much work we did when we lifted the cylinders : 150 joules . but this time , it took 5 days rather than a minute . five days is 5 times 24 times 60 times 60 again or 432,000 seconds . so we divide the work done by the time and find the answer of about 0.00035 joules per second , or about 0.35 milliwatts . that 's a tiny amount of power . this clock uses so little power that you could run almost 300,000 clocks using the same power it takes to run one 100-watt light bulb . that 's right , you could run a clock in every house in a medium sized city with that much power . that 's a pretty amazing conclusion and it took knowledge of work and power to figure it out .
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in fact , when the cylinders get to the bottom , all the energy that we put in will have left . so how much power does the clock use ? that is , how many joules of energy per second leave the clock if it takes 5 days for the cylinders to return to their original position ?
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the work done to lift the metal cylinders while winding the clock is the same as the work done by the force of gravity lowering the cylinders while the clock runs . why is the power to run the clock so much less than the power to wind the clock ?
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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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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 .
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why do you think diamonds are priced higher than water ? can there ever be a situation where diamonds are priced equal to or maybe even lesser than water ?
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right now , you 're probably sitting down to watch this video and staying seated for a few minutes to view it is probably okay . but the longer you stay put , the more agitated your body becomes . it sits there counting down the moments until you stand up again and take it for a walk . that may sound ridiculous . our bodies love to sit , right ? not really . sure , sitting for brief periods can help us recover from stress or recuperate from exercise . but nowadays , our lifestyles make us sit much more than we move around , and our bodies simply are n't built for such a sedentary existence . in fact , just the opposite is true . the human body is built to move , and you can see evidence of that in the way it 's structured . inside us are over 360 joints , and about 700 skeletal muscles that enable easy , fluid motion . the body 's unique physical structure gives us the ability to stand up straight against the pull of gravity . our blood depends on us moving around to be able to circulate properly . our nerve cells benefit from movement , and our skin is elastic , meaning it molds to our motions . so if every inch of the body is ready and waiting for you to move , what happens when you just do n't ? let 's start with the backbone of the problem , literally . your spine is a long structure made of bones and the cartilage discs that sit between them . joints , muscles and ligaments that are attached to the bones hold it all together . a common way of sitting is with a curved back and slumped shoulders , a position that puts uneven pressure on your spine . over time , this causes wear and tear in your spinal discs , overworks certain ligaments and joints , and puts strain on muscles that stretch to accommodate your back 's curved position . this hunched shape also shrinks your chest cavity while you sit , meaning your lungs have less space to expand into when you breath . that 's a problem because it temporarily limits the amount of oxygen that fills your lungs and filters into your blood . around the skeleton are the muscles , nerves , arteries and veins that form the body 's soft tissue layers . the very act of sitting squashes , pressurizes and compresses , and these more delicate tissues really feel the brunt . have you ever experienced numbness and swelling in your limbs when you sit ? in areas that are the most compressed , your nerves , arteries and veins can become blocked , which limits nerve signaling , causing the numbness , and reduces blood flow in your limbs , causing them to swell . sitting for long periods also temporarily deactivates lipoprotein lipase , a special enzyme in the walls of blood capillaries that breaks down fats in the blood , so when you sit , you 're not burning fat nearly as well as when you move around . what effect does all of this stasis have on the brain ? most of the time , you probably sit down to use your brain , but ironically , lengthy periods of sitting actually run counter to this goal . being stationary reduces blood flow and the amount of oxygen entering your blood stream through your lungs . your brain requires both of those things to remain alert , so your concentration levels will most likely dip as your brain activity slows . unfortunately , the ill effects of being seated do n't only exist in the short term . recent studies have found that sitting for long periods is linked with some types of cancers and heart disease and can contribute to diabetes , kidney and liver problems . in fact , researchers have worked out that , worldwide , inactivity causes about 9 % of premature deaths a year . that 's over 5 million people . so what seems like such a harmless habit actually has the power to change our health . but luckily , the solutions to this mounting threat are simple and intuitive . when you have no choice but to sit , try switching the slouch for a straighter spine , and when you do n't have to be bound to your seat , aim to move around much more , perhaps by setting a reminder to yourself to get up every half hour . but mostly , just appreciate that bodies are built for motion , not for stillness . in fact , since the video 's almost over , why not stand up and stretch right now ? treat your body to a walk . it 'll thank you later .
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what effect does all of this stasis have on the brain ? most of the time , you probably sit down to use your brain , but ironically , lengthy periods of sitting actually run counter to this goal . being stationary reduces blood flow and the amount of oxygen entering your blood stream through your lungs .
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keep a daily log of how much time you spend sitting during a regular day . calculate the percentage of time you spent sitting versus moving . what can you do to change this ?
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have you ever seen a big , red `` no running '' sign at a public pool ? for the most part , the pace on the deck reflects this statement . but while the sign accurately describes the patrons ' movements , is n't it true that people are walking because the sign tells them no running ? so , is this sign portraying the pool 's environment , or is it doing something else , something more powerful ? the difference between a statement that describes and one that commands is an idea developed by british linguist j. l. austin . he defines this distinction as two separate parts of speech : constatives and performatives . constatives are sentences that describe something as true or false , and performatives are sentences that denote an action . in other words , a constative is , and a performative does . to help us distinguish these two parts of speech , let 's start by examining constatives around the park outside the pool . the first sign we encounter says , `` the park closes at 6 p.m. '' after checking with a friendly park official that the park does , indeed , close at 6 , we can confirm that this statement is a true constative . nearby , there 's a man on a bench with a newspaper , and the headline reads , `` heatwave ! '' however , the sky is cloudy and it feels quite chilly . today 's headline is a false constative as it has proven to be incorrect . before the rain starts to fall , let 's throw away our can of soda at the blue trash bin that says , `` recycle . '' it 's a performative . performatives are sentences that are meant to inspire actions . rather than conveying a message , it acts upon the world , it does something . in this case , the performative of `` recycle '' is requesting people to put their trash into the proper receptacle . words not only bring about actions , sometimes words themselves are actions . this is what is known as speech acts . these actions include , but are not limited to , ordering , promising , apologizing , warning , sentencing , christening , and even marrying . take a look at the wedding near the gazebo . the couple says the words , `` i do . '' the speech act here are the words , `` i do . '' these words cause them to marry one another . `` i do '' has acted upon them and profoundly changed their world . however , performatives depend on context and reception . these are known as felicity conditions . imagine if the mayor showed up to the wedding and said , `` by the power vested in me as mayor of the city , i name this gazebo 'the mayor 's pizza palace . ' '' his words would be a speech act by which he named the gazebo . and because he 's the mayor , the gazebo would be known by its new name . but if someone who is n't the mayor , just a normal passerby , decides to name the gazebo after her favorite cat , the chances are the name would not change . felicity conditions are the rules under which the performative can be enacted . these are fairly logical . the performative should have proper authority , it should be understood , it should be clear , and it should be able to be executed . if the performative does n't meet these conditions , then it does n't have the power to denote action . but just because a performative meets its conditions and is clearly stated , does n't mean that it 's implicitly followed . back at the pool , a rowdy group of teenagers races to the high dive . `` no running '' does not seem to have power over them , and they 'll have to face the consequences of breaking this performative . they may even have to force out some performatives of their own , such as apologizing to the life guard and promising to never run again . maybe the life guard will respond with another performative , sentencing them to be banished from the pool for the rest of the day . after all , these teenagers must learn to respect the power of words .
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the first sign we encounter says , `` the park closes at 6 p.m. '' after checking with a friendly park official that the park does , indeed , close at 6 , we can confirm that this statement is a true constative . nearby , there 's a man on a bench with a newspaper , and the headline reads , `` heatwave ! '' however , the sky is cloudy and it feels quite chilly . today 's headline is a false constative as it has proven to be incorrect .
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if the headline reads , `` heatwave ! , '' but the sky is cloudy and it feels cold outside , what best describes the headline ?
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translator : tom carter reviewer : bedirhan cinar we take a breath every few seconds . our life depends upon inhaling oxygen , but we never think about how we breathe . it just seems to happen automatically . how can something that seems so simple be the key to keeping us alive ? breathing starts with the environment around us . the air we breathe in , or inspire , has a mixture of gases including nitrogen , carbon dioxide and oxygen , which is the most important for our survival . it enters our body through the nose and mouth , moves down into the pharynx , trachea and bronchial tubes , and ultimately reaches the alveoli air sacs in the lungs . the alveoli use pressure to move oxygen and nutrients into the blood . the diaphragm and intercostal muscles are a pumping system that facilitates this air exchange . how you breathe affects your energy level , especially when you are under physical or emotional stress . think back to the last difficult test you had to take . it 's likely that as you became more nervous , the tension in your body increased , and your breathing quickly sped up . the shallower our breath , the less oxygen that reaches our brain , and the harder it is to focus . what 's our response to physical stress , like a fast-paced game of field hockey after school ? as we exert pressure on our bodies , the muscles require a great deal of energy and demand additional oxygen . our panting breath starts to kick in , which creates pressure to draw in more air and oxygen to the body , and regulates body temperature by allowing it to cool down naturally . these are n't the only times our breathing is affected or altered . think about the last time you got angry or emotional . anger creates a metabolic reaction in the body , which stresses it out and heats up our internal temperature . have you ever seen anyone lose their cool ? ultimately , if we 're breathing under stress over long periods of time , there are consequences . when the cells of a body are n't getting the oxygen they need , the nutrients available to the body decrease and toxins build up in the blood . it is thought that a hypoxic , or oxygen-poor environment , can increase cancerous cells . the good news is that we can control our breath much more than we realize . this means we can increase both the quality and quantity of the breath . the science of breathing has been around for thousands of years , from ancient yogis in india to respiratory therapists working with patients today . both would tell you that there are specific techniques that will help you improve your breathing . breathing is all about moving air from a higher-pressure to a lower-pressure environment . more breath means more oxygen , and ultimately a greater amount of nutrients that 's available for our cells and blood . we naturally do this when we let out a big sigh . changing the air pressure going into the lungs is one of the main ways to alter breathing . our body automatically does this when we cough , sneeze , or have the hiccups . here 's a simple experiment . close off your right nostril with your right thumb . breathe in and out just through the left nostril . notice how much harder it is to get the breath in . you have to focus your attention , and use your diaphragm and muscles much more than normal . by decreasing the surface area of the airways , you 're increasing the pressure of oxygen moving from the alveoli to the blood . yogis often practice alternate nostril breathing to slow down the breath , increase oxygen , and activate the body 's parasympathetic nervous system , which deals with the body 's operations when it 's at rest . let 's try another exercise . visualize the way a dog pants when it breathes . now try doing the same type of panting , first with your tongue out , then with your mouth closed . you will find yourself using your stomach muscles to push the air out as you exhale . place your hand under your nose , and you 'll feel the strength of the breath coming out . breathing this way is hard because it requires an active movement of our diaphragm and intercostal muscles . our body temperature changes quickly during this exercise from the amount of pressure we are exerting on our breath . it 's no surprise that you 'll find dogs doing this breath often to cool down on a hot day . when we sleep at night , the medulla center of the brain makes sure that we keep breathing . lucky for us we do n't have to think about it . during the day , our breath is much more vulnerable , especially under stressful or difficult situations . that 's why it 's helpful to pay attention to your breathing . if you can monitor and change your breath , you can improve both the quality and quantity of oxygen that enters your body . this lowers stress , increases energy , and strengthens your immune system . so the next time someone tells you to relax and take a deep breath , you 'll know exactly why .
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it enters our body through the nose and mouth , moves down into the pharynx , trachea and bronchial tubes , and ultimately reaches the alveoli air sacs in the lungs . the alveoli use pressure to move oxygen and nutrients into the blood . the diaphragm and intercostal muscles are a pumping system that facilitates this air exchange .
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how do the alveoli in the lungs move oxygen and nutrients into the bloodstream ?
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it may sound like a paradox , or some cruel joke , but whatever it is , it 's true . beethoven , the composer of some of the most celebrated music in history , spent most of his career going deaf . so how was he still able to create such intricate and moving compositions ? the answer lies in the patterns hidden beneath the beautiful sounds . let 's take a look at the famous `` moonlight sonata , '' which opens with a slow , steady stream of notes grouped into triplets : one-and-a-two-and-a-three-and-a . but though they sound deceptively simple , each triplet contains an elegant melodic structure , revealing the fascinating relationship between music and math . beethoven once said , `` i always have a picture in my mind when composing and follow its lines . '' similarly , we can picture a standard piano octave consisting of thirteen keys , each separated by a half step . a standard major or minor scale uses eight of these keys , with five whole step intervals and two half step ones . and the first half of measure 50 , for example , consists of three notes in d major , separated by intervals called thirds , that skip over the next note in the scale . by stacking the scale 's first , third and fifth notes , d , f-sharp and a , we get a harmonic pattern known as a triad . but these are n't just arbitrary magic numbers . rather , they represent the mathematical relationship between the pitch frequencies of different notes which form a geometric series . if we begin with the note a3 at 220 hertz , the series can be expressed with this equation , where `` n '' corresponds to successive notes on the keyboard . the d major triplet from the moonlight sonata uses `` n '' values five , nine , and twelve . and by plugging these into the function , we can graph the sine wave for each note , allowing us to see the patterns that beethoven could not hear . when all three of the sine waves are graphed , they intersect at their starting point of 0,0 and again at 0,0.042 . within this span , the d goes through two full cycles , f-sharp through two and a half , and a goes through three . this pattern is known as consonance , which sounds naturally pleasant to our ears . but perhaps equally captivating is beethoven 's use of dissonance . take a look at measures 52 through 54 , which feature triplets containing the notes b and c. as their sine graphs show , the waves are largely out of sync , matching up rarely , if at all . and it is by contrasting this dissonance with the consonance of the d major triad in the preceding measures that beethoven adds the unquantifiable elements of emotion and creativity to the certainty of mathematics , creating what hector berlioz described as `` one of those poems that human language does not know how to qualify . '' so although we can investigate the underlying mathematical patterns of musical pieces , it is yet to be discovered why certain sequences of these patterns strike the hearts of listeners in certain ways . and beethoven 's true genius lay not only in his ability to see the patterns without hearing the music , but to feel their effect . as james sylvester wrote , `` may not music be described as the mathematics of the sense , mathematics as music of the reason ? '' the musician feels mathematics . the mathematician thinks music . music , the dream . mathematics , the working life .
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this pattern is known as consonance , which sounds naturally pleasant to our ears . but perhaps equally captivating is beethoven 's use of dissonance . take a look at measures 52 through 54 , which feature triplets containing the notes b and c. as their sine graphs show , the waves are largely out of sync , matching up rarely , if at all .
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how is dissonance used in beethoven ’ s `` moonlight sonata '' ?
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bean bags are awesome . but i see a few people out there who are standing , we 've got some over here , and standing takes more work than lounging . using the live strong organization 's online database of weight loss resources , you can calculate that by the time i 'm done with this speech , those of you who are standing will have burned 7.5 more calories than those of you who are bean-bagging it . ( laughter ) okay , here 's a question , speaking of weight loss , specifically weight , this speech is live . i 'm actually here in front of you guys , we 're all here together . but this speech is being recorded and it will become a video that people can access all over the world on computers , mobile devices , televisions . i weight about 190 pounds . how much will the video weigh ? asking questions like that is what i do every week on my channel vsauce . for the last two years , i have been asking really fun questions , mind-boggling questions , and approaching them as sincerely as i can , celebrating scientific concepts and scientists . and i research and write and produce and host and edit and upload and run the social media all by myself , but it 's not lonely , because vsauce has more than 2 million subscribers , and every month , my videos are seen by more than 20 million people . yeah . ( applause ) it 's very exciting . i 've found that asking a strange question is a great way to get people in , not just people , but fans . and fans are different than just viewers or an audience , because fans want to come back . they subscribe to you on youtube and they want to watch everything you 've made and everything you plan to make in the future because we are curious people and sparking curiosity is great bait . it 's a great way to catch a human . and once you 've caught them , you have this captive audience that you can , with the goal in mind of answering the question , accidentally teach a lot of things to . so , let 's take a look at some of my videos . here are eight of them . but down here in the lower-right corner , `` what color is a mirror ? '' when people see that , it 's very difficult not to click , because you think , `` come on , are you serious ? how could you possibly answer that question ? '' well , so far , 7.6 million people have watched this five-minute video about what color a mirror is . and in that episode , i answer the question and i get a chance to explain what would normally be kind of dry topics : optics , diffuse versus specular reflection , how light works , how light works on the retina , and even the etymology of color terms like white and black . okay , spoiler alert : mirrors are not clear , they are not silvery , like they 're often illustrated . mirrors , technically speaking , are just a tiny , tiny , little bit ... green . you can demonstrate this by putting two mirrors next to each other , facing so they reflect back and forth forever . look down that infinite reflection , and it will get dimmer , because some light is lost or absorbed every time , but it will also become greener , because green light , that is light of a wavelength that we perceive as green , is best reflected by most mirrors . okay , so , how much does a video weigh ? well , when you stream a video onto your computer , that information is temporarily stored using electrons . and the number of electrons on your device wo n't actually increase or decrease . but it takes energy to store them in one place , and , thanks to our friend albert einstein , we know that energy and mass are related . okay , so here 's the thing : let 's say you 're watching a youtube video at a really nice resolution , 720p . assuming a typical bit rate , we can figure that a minute of youtube video is going to need to involve about 10 million electrons on your device . plugging all those electrons and the energy it takes to hold them in the correct place for you to see the video , into that formula , we can figure out that one minute of youtube video increases the mass of your computer by about 10 to the negative 19th grams . written out , it looks like this . ( whistle ) that 's like nothing . you could call that nothing , and you would n't really get in trouble , because the best scales we 've ever invented that we could try to use to actually to detect that change are only accurate to 10 to the negative 9th grams . so , we ca n't measure it , but we can , like we just did , calculate it . and that 's really cool because when i was a kid , my school had two shelves of science books . that was really cool , but i read all of them within , like , two grades , and it was hard to get more books because books are heavy , you need space for them and moving books around is tougher than what we can do today . with numbers that small , i can fit thousands of books on my own little personal electronic reader . i can stream hours and hours and days and days of youtube video without my computer ever getting measurably heavier . and as information becomes that light , it becomes a lot more democratic , meaning that more teachers and presenters and creators and viewers than ever before can be involved . right now , on youtube , there is an explosion of content like this happening . the three vsauce channels are down there in the corner . but everyone else , all together , collectively , their views dwarf what i can do alone or with the people that i work with , and that is really , really exciting . it turns out that tapping into people 's curiosity and responsibly answering their questions is a brilliant way to build fans and an audience and get in viewers . it 's even a great way for brands and companies to build trust . so , calculating the weight of a video is kind of a funny question , but i can not wait to see what we ask and answer next . as always , thanks for watching . ( applause )
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but this speech is being recorded and it will become a video that people can access all over the world on computers , mobile devices , televisions . i weight about 190 pounds . how much will the video weigh ? asking questions like that is what i do every week on my channel vsauce .
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by how much does a one minute youtube video increase the weight of your computer ?
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what you 're looking at is n't some weird x-ray . it 's actually a baby yellow tang surgeonfish at two months old . and you thought your childhood was awkward . but here is the same fish as an adult , a beautiful inhabitant of the indian and pacific oceans ' coral reefs and one of the most popular captive fish for salt water aquariums . of the 27,000 known fish species , over a quarter live on coral reefs that make up less than 1 % of the earth 's surface . but prior to settling down in this diverse tropical environment , baby coral reef fish face the difficult process of growing up on their own , undergoing drastic changes , and the journey of a lifetime before they find that reef to call home . the life cycle for most of these fish begins when their parents spew sperm and eggs into the water column . this can happen daily , seasonally , or yearly depending on the species , generally following lunar or seasonal tidal patterns . left to their fate , the fertilized eggs drift with the currents , and millions of baby larvae hatch into the world . when they first emerge , the larvae are tiny and vulnerable . some do n't even have gills yet and must absorb oxygen directly from the water through their tissue-thin skin . they may float in the water column anywhere from minutes to months , sometimes drifting thousands of miles across vast oceans , far from the reefs where they were born . along the way , they must successfully avoid predators , obtain food , and ride the right currents to find their way to a suitable adult habitat , which might as well be a needle in vast haystack of ocean . so , how did they accomplish this feat ? until recently , marine biologists thought of larval fish as largely passive drifters , dispersed by ocean currents to distant locales . but in the last 20 years , new research has suggested that larvae may not be as helpless as they seem , and are capable of taking their fate in their own fins to maximize their chances of survival . the larvae of many species are unexpectedly strong swimmers , and can move vertically in the water column to place themselves in different water masses and preferentially ride certain currents . these fish may be choosing the best routes to their eventual homes . when searching for these homes , evidence suggests that larvae navigate via a complex suite of sensory systems , detecting both sound and smell . odor , in particular , allows larvae to distinguish between different environments , even adjacent reefs , helping guide them toward their preferred adult habitats . many will head for far-flung locales miles away from their birth place . but some will use smell and other sensory cues to navigate back to the reefs where they were born , even if they remain in the larval stage for months . so , what happens when larvae do find a suitable coral reef ? do they risk it all in one jump from the water column , hoping to land in exactly the right spot to settle down and metamorphose into adults ? not exactly . instead , larvae appear to have more of a bungee system . larvae will drop down in the water column to check out a reef below . if conditions are n't right , they can jump back up into higher water masses and ride on , chancing that the next reef they find will be a better fit . but this is the point where our knowledge ends . we do n't know the geographic movements of individual larva for most species . nor do we know which exact environmental cues and behaviors they use to navigate to the reefs they will call home . but we do know that these tiny trekkers are more than the fragile and helpless creatures science once believed them to be . the secret lives of baby fish remain largely mysterious to us , unknown adventures waiting to be told .
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and you thought your childhood was awkward . but here is the same fish as an adult , a beautiful inhabitant of the indian and pacific oceans ' coral reefs and one of the most popular captive fish for salt water aquariums . of the 27,000 known fish species , over a quarter live on coral reefs that make up less than 1 % of the earth 's surface . but prior to settling down in this diverse tropical environment , baby coral reef fish face the difficult process of growing up on their own , undergoing drastic changes , and the journey of a lifetime before they find that reef to call home . the life cycle for most of these fish begins when their parents spew sperm and eggs into the water column .
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if you were a biologist interested in coral reefs , how might you study the large-scale geographic movements of tiny baby fish ?
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watch the center of this disk . you are getting sleepy . no , just kidding . i 'm not going to hypnotize you . but are you starting to see colors in the rings ? if so , your eyes are playing tricks on you . the disk was only ever black and white . you see , your eyes do n't always capture the world as a video camera would . in fact , there are quite a few differences , owing to the anatomy of your eye and the processing that takes place in your brain and its outgrowth , the retina . let 's start with some similarities . both have lenses to focus light and sensors to capture it , but even those things behave differently . the lens in a camera moves to stay focused on an object hurtling towards it , while the one in your eye responds by changing shape . most camera lenses are also achromatic , meaning they focus both red and blue light to the same point . your eye is different . when red light from an object is in focus , the blue light is out of focus . so why do n't things look partially out of focus all the time ? to answer that question , we first need to look at how your eye and the camera capture light : photoreceptors . the light-sensitive surface in a camera only has one kind of photoreceptor that is evenly distributed throughout the focusing surface . an array of red , green and blue filters on top of these photoreceptors causes them to respond selectively to long , medium and short wavelength light . your eye 's retinas , on the other hand , have several types of photoreceptors , usually three for normal light conditions , and only one type for lowlight , which is why we 're color blind in the dark . in normal light , unlike the camera , we have no need for a color filter because our photoreceptors already respond selectively to different wavelengths of light . also in contrast to a camera , your photoreceptors are unevenly distributed , with no receptors for dim light in the very center . this is why faint stars seem to disappear when you look directly at them . the center also has very few receptors that can detect blue light , which is why you do n't notice the blurred blue image from earlier . however , you still perceive blue there because your brain fills it in from context . also , the edges of our retinas have relatively few receptors for any wavelength light . so our visual acuity and ability to see color falls off rapidly from the center of our vision . there is also an area in our eyes called the blind spot where there are no photoreceptors of any kind . we do n't notice a lack of vision there because once again , our brain fills in the gaps . in a very real sense , we see with our brains , not our eyes . and because our brains , including the retinas , are so involved in the process , we are susceptible to visual illusions . here 's another illusion caused by the eye itself . does the center of this image look like it 's jittering around ? that 's because your eye actually jiggles most of the time . if it did n't , your vision would eventually shut down because the nerves on the retina stop responding to a stationary image of constant intensity . and unlike a camera , you briefly stop seeing whenever you make a larger movement with your eyes . that 's why you ca n't see your own eyes shift as you look from one to the other in a mirror . video cameras can capture details our eyes miss , magnify distant objects and accurately record what they see . but our eyes are remarkably efficient adaptations , the result of hundreds of millions of years of coevolution with our brains . and so what if we do n't always see the world exactly as it is . there 's a certain joy to be found watching stationary leaves waving on an illusive breeze , and maybe even an evolutionary advantage . but that 's a lesson for another day .
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and unlike a camera , you briefly stop seeing whenever you make a larger movement with your eyes . that 's why you ca n't see your own eyes shift as you look from one to the other in a mirror . video cameras can capture details our eyes miss , magnify distant objects and accurately record what they see . but our eyes are remarkably efficient adaptations , the result of hundreds of millions of years of coevolution with our brains .
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when following the development of objects designed by humans we often see that big leaps are made using totally different approaches and materials . for example pens used to be made from feathers and were dipped into a jar of ink , then ballpoint and felt tip pens were developed . in living organisms , we see gradual change and the use of preexisting structures for new purposes but no radically new approaches . for example , the small bones in our ears originated from jaw bones , they did n't just appear magically on their own . what examples can you see of this contrast between purposeful design and evolution when you look at the development of cameras and the evolution of the eye ?
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imagine something small enough to float on a particle of dust that holds the keys to understanding cancer , virology , and genetics . luckily for us , such a thing exists in the form of trillions upon trillions of human lab-grown cells called hela . let 's take a step back for a second . scientists grow human cells in the lab to study how they function , understand how diseases develop , and test new treatments without endangering patients . to make sure that they can repeat these experiments over and over , and compare the results with other scientists , they need huge populations of identical cells that can duplicate themselves faithfully for years , but until 1951 , all human cell lines that researchers tried to grow had died after a few days . then a john hopkins scientist named george gey received a sample of a strange looking tumor : dark purple , shiny , jelly-like . this sample was special . some of its cells just kept dividing , and dividing , and dividing . when individual cells died , generations of copies took their place and thrived . the result was an endless source of identical cells that 's still around today . the very first immortal human cell line . gey labeled it `` hela '' after the patient with the unusual tumor , henrietta lacks . born on a tobacco farm in virginia , she lived in baltimore with her husband and five children . she died of aggressive cervical cancer a few months after her tumorous cells were harvested , and she never knew about them . so what 's so special about the cells from henrietta lacks that lets them survive when other cell lines die ? the short answer is we do n't entirely know . normal human cells have built-in control mechanisms . they can divide about 50 times before they self destruct in a process called apoptosis . this prevents the propagation of genetic errors that creep in after repeated rounds of division . but cancer cells ignore these signals , dividing indefinitely and crowding out normal cells . still , most cell lines eventually die off , especially outside the human body . not hela , though , and that 's the part we ca n't yet explain . regardless , when dr. gey realized he had the first immortal line of human cells , he sent samples to labs all over the world . soon the world 's first cell production facility was churning out 6 trillion hela cells a week , and scientists put them to work in an ethically problematic way , building careers and fortunes off of henrietta 's cells without her or her family 's consent , or even knowledge until decades later . the polio epidemic was at its peak in the early 50s . hela cells , which easily took up and replicated the virus , allowed jonas salk to test his vaccine . they 've been used to study diseases , including measles , mumps , hiv , and ebola . we know that human cells have 46 chromosomes because a scientist working with hela discovered a chemcial that makes chromosomes visible . hela cells themselves actually have around 80 highly mutated chromosomes . hela cells were the first to be cloned . they 've traveled to outer space . telomerase , an enzyme that helps cancer cells evade destruction by repairing their dna , was discovered first in hela cells . in an interesting turn of fate , thanks to hela , we know that cervical cancer can be caused by a virus called hpv and now there 's a vaccine . hela-fueled discoveries have filled thousands of scientific papers , and that number is probably even higher than anyone knows . hela cells are so resilient that they can travel on almost any surface : a lab worker 's hand , a piece of dust , invading cultures of other cells and taking over like weeds , countless cures , patents and discoveries all made thanks to henrieta lacks .
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they 've traveled to outer space . telomerase , an enzyme that helps cancer cells evade destruction by repairing their dna , was discovered first in hela cells . in an interesting turn of fate , thanks to hela , we know that cervical cancer can be caused by a virus called hpv and now there 's a vaccine .
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what are some of the characteristics of cancer cells like hela that help them evade death ?
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welcome to the i grad fafsa tutorial this step-by-step instruction will walk you through an answer any questions , feel free to complete the fafsa alongside this video and press pause or rewind if you need it instant replay before you begin filling out the fafsa you may want to make sure you 're equipped with the following ... your driver 's license number , your social security number , a list to the schools you plan on applying to , or have already applied to , your tax return for the prior-year and your parents if you 're considered a dependent student here is how to determine whether you are dependent or independent student . to be considered an independent student you must meet at least one of the following criteria : be 24 years of age or older when you file a fafsa , be an orphan or a ward of court , be a us military veteran be a graduate or professional student , be married , have legal dependence of your own , have a financial aid administrator who is documented your independence because of unusual circumstances . even if you do n't live with your parents , they do n't claim you on their taxes or support you financially , you may still be considered a dependent student . if you are filling out the fafsa for the first time , you and one of your parents , if you 're a dependent will be asked at the end of the online form to apply for pin before signing electronically . make sure the pin and security question you choose are ones that you will remember , also , make sure that you have a printer nearby so that you can print up all the important documentation you 'll need this information every year you attend school the website for the fafsa is www.fafsa.ed.gov please note that filling out the fafsa is free and does not cost any money if you are being asked to pay for the form you are on the wrong site champ . okay let 's get started ... once you 're on the site you want to click the start here button , whether you 're filling out the fafsa for the first time or you 've done this before you 'll be asked 4 very important questions . your first and last name , your social security number , and your date of birth . just make sure to use your full legal name , as written on your social security card . click next and continue on to the next page . award years run from july 1st to june 30th , not january 1st to december 31st , so just make sure to pick the correct award year for your attendance , for example ... if you filling out the fafsa in february you 're not going to attend school until september , just make sure to select the correct award year that september falls within . you 'll then be asked to choose a password . this is different than your pin , but you should keep track of it just the same , once you 've filled out both entries for your password , go ahead and click next to continue . use the links on this page to answer any questions about the fafsa before getting started , otherwise just go ahead to the next section . as you can see the top portion of this form is already filled out for you , fill out all the information below that correctly , and then you have the option to enter in your driver 's license information , once you finished just click next . now , ... to confirm your eligibility just choose the option that best describes your citizenship status . if you 're neither a citizen nor an eligible non-citizen contact the financial aid department at the school to which you 're applying , they 'll assist you with determining your eligibility . the next question will ask you about your high school completion status for the upcoming award year , be sure to choose the best answer for your situation and degree or certificate if you 're unsure you can contact the financial aid department if you qualify , work-study programs at your school can be a great way for you to pay off your tuition costs but that sounds like a good option for you and your school offers it , click yes on the drop down option , if you 're unsure do a little research and if work-study just is n't for you choose the not interested option and continue on . make sure to choose the correct option for whether or not you have a bachelor 's degree , double check it too , because it could really cause trouble should you choose incorrectly . when the fafsa asked about your parents educational status these questions are designed to determine if you or a first-generation college student or not finish with this page in just click next . on the next page you 'll be asked the name city and state of the high school you attend okay ... in this section just enter all the schools that you 're applying to or which you 've been accepted . to choose schools for what you 're applying , click on the school 's state and city . at the bottom type in the school name or click on search for a list of all schools in the area choose your school from the box and add it to the selected school portion of the form . to choose more than one school , click add another school and just start the process over . make sure to apply to any school you may want to attend once you 're done double check to make sure they 're all correct . you will have the option of choosing whether you want to live on campus , off-campus , or with a parent . make your choice and click the next button . there are two types of students in the world ; dependent and independent . you 'll need to answer the following questions in order to determine your status , with each question there will be an explanation just to the right of the dependency section if you are under the age of 24 , but answered yes to one or more of these questions then you 're declared as an independent . if you answered yes to one or more the questions you may also be required to show documented proof . that 's why it 's important that you answer all the questions correctly and honestly . if you 're confused by a question or not sure if the situations applicable to you , you 'll want to contact your financial aid department at the schools to which you 've applied . if you choose emancipated minor-in foster care both parents are deceased a dependent or ward of the court or homeless , make sure you have the right documentation to follow up with these claims . if you answered no to all these questions but believe you have special circumstances that might declare you an independent contact the financial aid department and they 'll request the proper documentation from you in order to request the dependency change . however , supplying documentation does n't guarantee your dependency change request will be approved . if you 're dependent make sure you have your and your parents tax returns from the previous year . before we get started on entering in all that information it 's important to know that there is an irs data retrieval tool . that allows fafsa on the web applicants to a request and retrieve their tax information data right from the irs . in order to use the irs data retrieval tool applicants must ; have a valid social security number , have filed a federal tax return to the previous year , and have an unchanged marital status since december 31st of the previous year if you 've just filed your taxes you may not be able to use the tool . do n't worry though , if you have the proper documentation you can enter it manually on the fafsa form . if you 're eligible to use the irs data retrieval tool you 'll be led to the following pages , please note that if you 're dependent student your parents information will be required first , and then you 'll be redirected back to the beginning to enter your own information . first , choose from the drop down tab already filed if you answered no to the questions below you 'll be asked for your pin , then click the irs button to proceed . then you leave the fafsa website be led to the irs website click ok to continue . once on the irs website enter all of your information correctly , all information must match your tax return , once you 're done , click submit . if the irs is able to retrieve your information will then be asked if you like your information transferred to the fafsa , check the box and click transfer now then you 'll sign and submit your fafsa if you 're ineligible to use the irs data retrieval tool will need to enter everything in the old fashion way , ... so get to typing ! now this is the part where those tax returns will come in handy , if you just filed your tax return or have n't done so yet you may estimate the information from the prior year 's tax return , once you 've filed you can return to the fafsa and make corrections . you can also use the irs data retrieval tool to make those updates corrections if you have any questions or are n't sure what to enter you can always refer to the side of the page in the help and hints box . this will give you instructions to each question and assist you in filling everything out correctly and completely . continue filling out all your information and click next to continue . congratulations ! ... you have completed the fafsa on your way to be receiving financial aid to help pay for school the next page gives you when efc number efc stands for estimated family contribution , you later receive an award letter from the school or schools to which you applied . the award letter will tell you how much money you will be awarded ! thanks for watching our little igrad fafsa tutorial we wish you the best of luck this school season .
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make your choice and click the next button . there are two types of students in the world ; dependent and independent . you 'll need to answer the following questions in order to determine your status , with each question there will be an explanation just to the right of the dependency section if you are under the age of 24 , but answered yes to one or more of these questions then you 're declared as an independent .
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explain the difference in a dependent and independent student ?
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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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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 .
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you are measuring length with a meter stick . however , you do not realize that the first 4.0 centimeters of the meter stick are missing because a hungry beaver made a snack of it earlier that day . the measurements you take with the meter stick will be :
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translator : andrea mcdonough reviewer : bedirhan cinar how come some insects are able to walk on the surface of a pond , but you quickly sink to the bottom when you try to walk on water ? and why do lakes freeze from the top down in winter ? in a word , the answer to all these questions is polarity . water is a simple molecule made up of one oxygen atom and two hydrogen atoms , but it is essential to life . in fact , water makes up approximately 60 % of the adult human being 's body weight . the polarity within those water molecules gives this common substance the properties that make it unique and life-sustaining . polarity refers to the unequal sharing of electrons within a molecule . for water , the bonding between the oxygen atom and two hydrogen atoms within a single water molecule is like a tug-of-war between a big , strong football player and a cute little toddler . oxygen is a larger atom , with more protons in its nucleus than hydrogen . these positive charges are like a person 's physical strength . they 're able to attract the negatively charged electrons in the bond , just like a strong individual is able to overpower a weaker individual in a tug of war . so , oxygen is able to attract more than its fair share of electrons . because hydrogen is smaller and has less strength , or fewer protons , it loses the tug of war and attracts fewer than its fair share of electrons . so , the oxygen in water behaves as though it 's negative , and the hydrogens behave as though they 're positive . the bonds within a single water molecule are called polar covalent bonds . covalent means that the electrons are shared . but , as we just learned , polar means that these electrons are not shared equally . in water , the oxygen acts negative and the hydrogens act positive . since negative and positive attract , that oxygen is attracted to the hydrogen atoms in neighboring water molecules . a special type of bond forms between water molecules , known as a hydrogen bond . hydrogen bonds do n't just happen in water either . they can form between a water molecule and different substances that are polar or ionic . water 's ability to stick to itself is called cohesion , while water 's ability to stick to other substances is called adhesion . now , think back to the initial questions . first , why are some insects able to walk on water ? surface tension due to hydrogen bonding creates a thin film on the surface of water that gives enough resistance for super-light insects to walk on . you ca n't walk on it because the hydrogen bonds are n't strong enough to hold you up . why does ice float on top of liquid water ? for most other substances , the solid state is more dense than the liquid state , but that is not the case for water ! hydrogen bonds keep water molecules farther apart in frozen water than in liquid water . the farther apart the molecules are , the less dense that solid is . so ice is about 9 % less dense than water , which means it floats on the top . that 's why lakes freeze from the top down and aquatic life is able to survive through a cold winter every year . it is the polarity of the water molecule and the resulting hydrogen bonding that account for water 's unique properties . so , the reason that water is so special , from inside your cells to the world 's oceans , is simply because it is a polar molecule .
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they can form between a water molecule and different substances that are polar or ionic . water 's ability to stick to itself is called cohesion , while water 's ability to stick to other substances is called adhesion . now , think back to the initial questions .
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the property of water that refers to its ability to stick to itself is called _____________ .
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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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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 .
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the theory of ideasthesia suggests that the ability to understand a metaphor is based on :
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what does it mean to be one in a million ? not in the greeting card sense , in the scientific sense , where one part per million is a unit of measurement . parts per million counts the number of units of one substance per one million units of another . it can measure concentrations when a small amount makes a big difference . for example , a concentration of just 35 ppm of carbon monoxide in the air is poisonous to us . we encounter measurements like this pretty often , but because it 's hard to conceptualize really large numbers , it 's difficult to wrap our brain around what one part per million really means . so here are nine helpful ways to visualize it . if you had 11,363 pianos-worth of piano keys , one of those keys would be about one part per million . so would a single granule of sugar among 273 sugar cubes , one second in eleven and a half days , or four dots in the painting , `` a sunday afternoon on the island of la grande jatte . '' your bath tub 's capacity is about 60 gallons , so seven drops of ink would be one part per million . the english version of the harry potter series has 1,084,170 words , which makes `` hippogriff '' on page 221 of `` the prisoner of azkaban '' a little less than one part per million . a million kernels of corn is about 1,250 ears , so one kernel in that truckload would be one part per million . there are 10 million bricks in the empire state building , so one part per million would be a pile of just ten . and finally , 100 people worked together to animate this video . collectively , they have about 10 million hairs on their heads . pluck ten of those hairs , and you have one in a million .
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the english version of the harry potter series has 1,084,170 words , which makes `` hippogriff '' on page 221 of `` the prisoner of azkaban '' a little less than one part per million . a million kernels of corn is about 1,250 ears , so one kernel in that truckload would be one part per million . there are 10 million bricks in the empire state building , so one part per million would be a pile of just ten .
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your friend gives you a card that states that you 're “ one in a million. ” after watching this lesson , how might your reaction to this sentiment change ? rewrite the card using the phrase “ part per million ” instead .
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check this out : here 's a grid , nothing special , just a basic grid , very grid-y . but look closer , into this white spot at the center where the two central vertical and horizontal lines intersect . look very closely . notice anything funny about this spot ? yeah , nothing . but keep looking . get weird and stare at it . now , keeping your gaze fixed on this white spot , check what 's happening in your peripheral vision . the other spots , are they still white ? or do they show weird flashes of grey ? now look at this pan for baking muffins . oh , sorry , one of the cups is inverted . it pops up instead of dipping down . wait , no spin the pan . the other five are domed now ? whichever it is , this pan 's defective . here 's a photo of abraham lincoln , and here 's one upside down . nothing weird going on here . wait , turn that upside down one right side up . what have they done to abe ? those are just three optical illusions , images that seem to trick us . how do they work ? are magical things happening in the images themselves ? while we could certainly be sneaking flashes of grey into the peripheral white spots of our animated grid , first off , we promise we are n't . you 'll see the same effect with a grid printed on a plain old piece of paper . in reality , this grid really is just a grid . but not to your brain 's visual system . here 's how it interprets the light information you call this grid . the white intersections are surrounded by relatively more white on all four sides than any white point along a line segment . your retinal ganglion cells notice that there is more white around the intersections because they are organized to increase contrast with lateral inhibition . better contrast means it 's easier to see the edge of something . and things are what your eyes and brain have evolved to see . your retinal ganglion cells do n't respond as much at the crossings because there is more lateral inhibition for more white spots nearby compared to the lines , which are surrounded by black . this is n't just a defect in your eyes ; if you can see , then optical illusions can trick you with your glasses on or with this paper or computer screen right up in your face . what optical illusions show us is the way your photo receptors and brain assemble visual information into the three-dimensional world you see around you , where edges should get extra attention because things with edges can help you or kill you . look at that muffin pan again . you know what causes confusion here ? your brain 's visual cortex operates on assumptions about the lighting of this image . it expects light to come from a single source , shining down from above . and so these shading patterns could only have been caused by light shining down on the sloping sides of a dome , or the bottom of a hole . if we carefully recreate these clues by drawing shading patterns , even on a flat piece of paper , our brain reflexively creates the 3d concave or convex shape . now for that creepy lincoln upside down face . faces trigger activity in areas of the brain that have specifically evolved to help us recognize faces . like the fusiform face area and others in the occipital and temporal lobes . it makes sense , too , we 're very social animals with highly complex ways of interacting with each other . when we see faces , we have to recognize they are faces and figure out what they 're expressing very quickly . and what we focus on most are the eyes and mouth . that 's how we figure out if someone is mad at us or wants to be our friend . in the upside down lincoln face , the eyes and mouth were actually right side up , so you did n't notice anything was off . but when we flipped the whole image over , the most important parts of the face , the eyes and mouth , were now upside down , and you realized something fishy was up . you realized your brain had taken a short cut and missed something . but your brain was n't really being lazy , it 's just very busy . so it spends cognitive energy as efficiently as possible , using assumptions about visual information to create a tailored , edited vision of the world . imagine your brain calling out these edits on the fly : `` okay , those squares could be objects . let 's enhance that black-white contrast on the sides with lateral inhibition . darken those corners ! dark grey fading into light grey ? assume overhead sunlight falling on a sloping curve . next ! those eyes look like most eyes i 've seen before , nothing weird going on here . '' see ? our visual tricks have revealed your brain 's job as a busy director of 3d animation in a studio inside your skull , allocating cognitive energy and constructing a world on the fly with tried and mostly -- but not always -- true tricks of its own .
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those eyes look like most eyes i 've seen before , nothing weird going on here . '' see ? our visual tricks have revealed your brain 's job as a busy director of 3d animation in a studio inside your skull , allocating cognitive energy and constructing a world on the fly with tried and mostly -- but not always -- true tricks of its own .
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the connections between neurons in the retina , specifically the connections referred to as “ lateral inhibition , ” help us see which of the following better ?
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translator : andrea mcdonough reviewer : jessica ruby we often hear that studying literature involves finding a deeper meaning to a text . when writing about literary works , we 're expected to mentally dive below the surface in order to come back up with big ideas . but you may find yourself looking at the flat page of a book , wondering how deep it can really go ? how do we reach those ideas that turn into great essays ? well , there are two crucial thinking steps that can lead us in the right direction : practicing insight and acknowledging complexity . insight is the ability to arrive at an intuitive understanding of a big idea using only small clues to get there . if you 're practicing insight , you 'll able to use observations about character behavior to figure out their true emotions and motivations . pay attention to little things because they add up to what is really meaningful . for example , if you consider a character like mr. darcy from < i > pride and prejudice < /i > , who openly declares his dislike for miss lizzy bennet , you might , at first , assume he 's just a mean guy . but , using your powers of insight , you 're noticing other smaller things - how darcy 's eyes linger on lizzy 's face and how he seems all flustered when she 's around . add to the mix your knowledge that mr. darcy is in a much higher social class than lizzy , and your sense of insight should be telling you that there 's something more here . in this case , it will tell you that darcy 's surface behavior is in conflict with his true feelings of attraction because the difference in wealth between himself and lizzy makes him feel that it 'll never work . thinking about all those small clues gives us insight about some of the big , abstract ideas within the novel that we can approach in an essay : appearances versus reality , the power of wealth and social stratification , and the unpredictable nature of love and attraction . look at that ! deeper meaning . the second step to a sophisticated analysis is acknowledging complexity . let 's face it . in both life and literature , situations are complicated due to social forces like relationships , moral codes , personal desires , and power structures . this means that there are , at any given time , multiple factors that shape what is true . in order to acknowledge complexity in your writing , refrain from making broad generalizations about a text or establishing quick , simple judgements about a character . explore each facet of your subject carefully and make sure to consider multiple influences on events . explain the tension of multiple forces that create the story . for example , a basic analysis of toni morrison 's < i > beloved < i > , where the protagonist has killed her own child rather than allow her to grow up in slavery , might sound like this , `` sethe murdered her own daughter . this act was wrong , and causes the ghost of the child to haunt her throughout the novel . '' these observations are simplistic . they do n't acknowledge all the different forces that contribute to what the character has done . try something like this instead , `` a culture of slavery disturbs the ability to determine what is morally right . sethe 's past experiences with violence reinforce the fear she has for her child 's fate , and transform the murder into a protective act . as the novel progresses , sethe is haunted both by the angry spirit of her daughter and by the memories of everything else slavery took from her . '' here , we see those influential forces at work , and we 've shown off our ability to understand the complicated nature of the human experience , which , again , allows us to access those big ideas that reveal the deeper meaning of a story , ideas , in this case , like the parameters of maternal instinct , the consequences of injustice , and the question of whether or not ethics can even exist in a corrupted moral system . it 's impossible to sit down and write an amazing essay about literature without first thinking about it . before you hit the keys , go back to the text and fish out the small moments , the complicated moments in the story . line them up in your mind , practice insight , acknowledge complexity , arrive at some big ideas . before you know it , the deeper meaning will be close at hand .
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before you hit the keys , go back to the text and fish out the small moments , the complicated moments in the story . line them up in your mind , practice insight , acknowledge complexity , arrive at some big ideas . before you know it , the deeper meaning will be close at hand .
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considering your answers to question one and two , what might be some of these big ideas ( otherwise known as abstract concepts or thematic ideas ) in the text that you would want to address in an essay ? explain how you arrived at these ideas based off of your own insight and acknowledgement of the text ’ s complexity .
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translator : andrea mcdonough reviewer : bedirhan cinar it 's that time again . you need another internship to bolster your college applications . last year you worked at a local art museum , helping organize their collection and giving tours to visitors . this year , it 's going to be much more difficult . you want to work on an organic farm across the country in california . that 's your real passion . unfortunately , your friends ' list of contacts does n't include organic farmers . the same for your parents ' group of friends . they want to help you , but they simply do n't know of any internships in agriculture . the school counselor , she just laughed . to make your farming dreams come true , you 're going to have to press beyond your strong ties , people like your family and closest friends , and try tapping into your weaker ties . weak ties are a broader network , your friends of friends of friends . they 're important because they have access to resources that your strong ties do n't have . this works in both directions , by the way - you have access to resources that they do n't have . let 's say most people speak to three close friends on a regular basis . each time you reach beyond the next degree of contacts , you have access to three more people , like a tree that branches out three times per node , so you can look beyond your closest circles . during the last family get-together , did n't you hear that your aunt 's friend studied lighting with a nature photographer on the west coast ? in fact , you recall this because you saw a recent image by said photographer on the front cover of < i > the new york times < /i > . so , you email him and learn that the photographer 's wife 's cousin publishes a sustainability magazine , which employs a staff writer who pitches on a local baseball team with an umpire who , wait for it , is an organic farmer . bingo ! get ready to trade in those cuff links for some apple seeds , all because you reached out to your weak ties . that 's your key , remember ? every conversation is an opportunity . moreover , do n't wait for opportunity , make it happen . take kathryn minshew for example . she went from not knowing anyone at yahoo to three warm introductions to major executives in 30 days . here are her suggestions for three steps to networking . 1 - always say yes to invitations , even if it 's not clear what you 'll get out of the meeting . many of kathryn 's most productive relationships resulted from a meeting or call without a clear agenda . 2 - when you want something , broadcast it to everyone you meet . that does n't mean you beg everyone for help as soon as you meet them , but talk about what you 're trying to do . be excited , ask for feedback , and try to get them excited too . 3 - show up and often . be at the forefront of other 's minds when opportunities arise . you do n't want to be that person who only shows up when he needs something . be the one that people think of and want to reach out to when a new opportunity presents itself . so while networking may not be the most intuitive , or even for some of you introverts , the most comfortable skill , it 's a helpful tool to have as you think about getting a job , going to school , or most importantly , learning from others . good luck !
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here are her suggestions for three steps to networking . 1 - always say yes to invitations , even if it 's not clear what you 'll get out of the meeting . many of kathryn 's most productive relationships resulted from a meeting or call without a clear agenda .
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always say yes to invitations :
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imagine that one day , you 're summoned before a government panel . even though you have n't committed any crime , or been formally charged with one , you are repeatedly questioned about your political views , accused of disloyalty , and asked to incriminate your friends and associates . if you do n't cooperate , you risk jail or losing your job . this is exactly what happened in the united states in the 1950s as part of a campaign to expose suspected communists . named after its most notorious practitioner , the phenomenon known as mccarthyism destroyed thousands of lives and careers . for over a decade , american political leaders trampled democratic freedoms in the name of protecting them . during the 1930s and 1940s , there had been an active but small communist party in the united states . its record was mixed . while it played crucial roles in wider progressive struggles for labor and civil rights , it also supported the soviet union . from the start , the american communist party faced attacks from conservatives and business leaders , as well as from liberals who criticized its ties to the oppressive soviet regime . during world war ii , when the usa and ussr were allied against hitler , some american communists actually spied for the russians . when the cold war escalated and this espionage became known , domestic communism came to be seen as a threat to national security . but the attempt to eliminate that threat soon turned into the longest lasting and most widespread episode of political repression in american history . spurred on by a network of bureaucrats , politicians , journalists , and businessmen , the campaign wildly exaggerated the danger of communist subversion . the people behind it harassed anyone suspected of holding left-of-center political views or associating with those who did . if you hung modern art on your walls , had a multiracial social circle , or signed petitions against nuclear weapons , you might just have been a communist . starting in the late 1940s , fbi director j. edgar hoover used the resources of his agency to hunt down such supposed communists and eliminate them from any position of influence within american society . and the narrow criteria that hoover and his allies used to screen federal employees spread to the rest of the country . soon , hollywood studios , universities , car manufacturers , and thousands of other public and private employers were imposing the same political tests on the men and women who worked for them . meanwhile , congress conducted its own witchhunt subpoenaing hundreds of people to testify before investigative bodies like the house un-american activities committee . if they refused to cooperate , they could be jailed for contempt , or more commonly , fired and blacklisted . ambitious politicians , like richard nixon and joseph mccarthy , used such hearings as a partisan weapon accusing democrats of being soft on communism and deliberately losing china to the communist bloc . mccarthy , a republican senator from wisconsin became notorious by flaunting ever-changing lists of alleged communists within the state department . egged on by other politicians , he continued to make outrageous accusations while distorting or fabricating evidence . many citizens reviled mccarthy while others praised him . and when the korean war broke out , mccarthy seemed vindicated . once he became chair of the senate 's permanent subcommittee on investigations in 1953 , mccarthy recklessness increased . it was his investigation of the army that finally turned public opinion against him and diminished his power . mccarthy 's colleagues in the senate censured him and he died less than three years later , probably from alcoholism . mccarthyism ended as well . it had ruined hundreds , if not thousands , of lives and drastically narrowed the american political spectrum . its damage to democratic institutions would be long lasting . in all likelihood , there were both democrats and republicans who knew that the anti-communist purges were deeply unjust but feared that directly opposing them would hurt their careers . even the supreme court failed to stop the witchhunt , condoning serious violations of constitutional rights in the name of national security . was domestic communism an actual threat to the american government ? perhaps , though a small one . but the reaction to it was so extreme that it caused far more damage than the threat itself . and if new demagogues appeared in uncertain times to attack unpopular minorities in the name of patriotism , could it all happen again ?
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while it played crucial roles in wider progressive struggles for labor and civil rights , it also supported the soviet union . from the start , the american communist party faced attacks from conservatives and business leaders , as well as from liberals who criticized its ties to the oppressive soviet regime . during world war ii , when the usa and ussr were allied against hitler , some american communists actually spied for the russians .
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the american communist party faced attacks from :
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why are most manhole covers round ? sure , it makes them easy to roll and slide into place in any alignment but there 's another more compelling reason involving a peculiar geometric property of circles and other shapes . imagine a square separating two parallel lines . as it rotates , the lines first push apart , then come back together . but try this with a circle and the lines stay exactly the same distance apart , the diameter of the circle . this makes the circle unlike the square , a mathematical shape called a curve of constant width . another shape with this property is the reuleaux triangle . to create one , start with an equilateral triangle , then make one of the vertices the center of a circle that touches the other two . draw two more circles in the same way , centered on the other two vertices , and there it is , in the space where they all overlap . because reuleaux triangles can rotate between parallel lines without changing their distance , they can work as wheels , provided a little creative engineering . and if you rotate one while rolling its midpoint in a nearly circular path , its perimeter traces out a square with rounded corners , allowing triangular drill bits to carve out square holes . any polygon with an odd number of sides can be used to generate a curve of constant width using the same method we applied earlier , though there are many others that are n't made in this way . for example , if you roll any curve of constant width around another , you 'll make a third one . this collection of pointy curves fascinates mathematicians . they 've given us barbier 's theorem , which says that the perimeter of any curve of constant width , not just a circle , equals pi times the diameter . another theorem tells us that if you had a bunch of curves of constant width with the same width , they would all have the same perimeter , but the reuleaux triangle would have the smallest area . the circle , which is effectively a reuleaux polygon with an infinite number of sides , has the largest . in three dimensions , we can make surfaces of constant width , like the reuleaux tetrahedron , formed by taking a tetrahedron , expanding a sphere from each vertex until it touches the opposite vertices , and throwing everything away except the region where they overlap . surfaces of constant width maintain a constant distance between two parallel planes . so you could throw a bunch of reuleaux tetrahedra on the floor , and slide a board across them as smoothly as if they were marbles . now back to manhole covers . a square manhole cover 's short edge could line up with the wider part of the hole and fall right in . but a curve of constant width wo n't fall in any orientation . usually they 're circular , but keep your eyes open , and you just might come across a reuleaux triangle manhole .
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this collection of pointy curves fascinates mathematicians . they 've given us barbier 's theorem , which says that the perimeter of any curve of constant width , not just a circle , equals pi times the diameter . another theorem tells us that if you had a bunch of curves of constant width with the same width , they would all have the same perimeter , but the reuleaux triangle would have the smallest area .
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barbier 's theorem says that _____ .
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for most of human history , medical workers sought to treat diseases or cure them . the rise of vaccination in the 19th century enhanced the potential to prevent people from contracting illnesses in the first place . but only in recent decades did it become possible to ensure that a particular disease never threatens humanity again . the story of smallpox , the first and , so far , the only disease to be permanently eradicated from the world , shows how disease eradication can happen and why it is so difficult to achieve . smallpox emerged in human populations thousands of years ago as a contagious virus that spread rapidly , primarily through close , face to face contact , causing fever , aches and rashes . it killed up to 30 % of its victims and often left survivors with life-long disfiguring scars . the devastating impact of smallpox was so great that several cultures had religious deities specifically dedicated to it . in the 20th century alone , it is estimated to have killed more than 300 million people worldwide . with the effective deployment of vaccination , the number of cases began to decrease . by seeking out infected individuals , isolating them , and vaccinating their contacts to prevent further transmission , scientists realized that the spread of the disease could be haulted . in fact , because smallpox could only survive in human hosts , vaccinating all of an infected persons ' potential contacts would stop the virus dead in its tracks and eliminate it from that region . once this strategy had succeeded in ridding most industrialized countries from disease , health officials realized that eradicating it worldwide was within reach . but this was not an easy process , proving especially difficult in places suffering from poor infrastructure or civil wars . the eradication effort took decades and involved millions of people working together , from world leaders and international organizations to rural doctors and community workers . in india , one of the last strongholds of the disease , health workers visited every one of the country 's 100 million households to search for cases . through this unprecedented worldwide effort , in which even rival superpowers cooperated , smallpox was finally declared eradicated in 1980 , saving approximately 40 million lives over the following two decades . there were several factors that made smallpox an ideal candidate for eradication . first , humans are essential to the smallpox lifecycle , so breaking the chain of human to human transmission causes the virus to die out . in contrast , many other pathogens , like ebola or the bubonic plague , can survive in animal carriers , while the bacteria that cause tetanus can even live in the soil . secondly , individuals infected with smallpox displayed a characteristic rash , making them easy to identify , even without a lab test . the lack of such practical diagnostic tools for diseases with non-specific symptoms , or that have long incubation periods , such as aids , makes their eradication more difficult . third , the availability of a smallpox vaccine that provided immunity for five to ten years in a single dose meant that there was an effective intervention to stop the virus from spreading . and finally , the initial success of several countries in eliminating the disease within their borders served as a proof of principle for its eradication worldwide . today , the same criteria are applied to determine whether other diseases can be similarly eliminated . and even though smallpox remains the only success story thus far , several other pathogens may be next in line . great progress has been made towards eradicating guinea worm disease simply by use of water filters . and vaccination for polio , which previously disabled hundreds of thousands of people each year is estimated to have prevented 13 million cases of paralysis , and 650,000 deaths since 1988 . with a 99 % drop in infections since the eradication effort began , one final push is all that is needed to ensure that polio will never paralyze another child . disease eradication is one public health effort that benefits all of humanity and challenges us to work together as a global community . beyond eliminating specific diseases , eradication programs benefit local populations by improving health infrastructure . for example , nigeria recently used facilities and personnel from their polio eradication program to effectively control an ebola outbreak . further more , globalization and international travel means that even a single infection anywhere in the world can potentially spread to other regions . by helping to protect others , we help to protect ourselves . disease eradication is the ultimate gift we can give to everyone alive today , as well as all future generations of humanity .
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with a 99 % drop in infections since the eradication effort began , one final push is all that is needed to ensure that polio will never paralyze another child . disease eradication is one public health effort that benefits all of humanity and challenges us to work together as a global community . beyond eliminating specific diseases , eradication programs benefit local populations by improving health infrastructure .
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what are some challenges of disease eradication programs ?
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`` barbecue '' ! ! the word derives from the word `` barabicu '' , which to the taíno people in the caribbean islands meant `` sacred fire pit '' . we are definitely on sacred ground today . if we can get in . [ music ] i 'm here to learn a little about the science of bbq , so i came to a man who knows a little bit about that , aaron franklin ... well that 's debatable . how 's it going ? so what is bbq ? i think bbq is something that 's cooked over a live fire , so that could encompass grilling , slow offset cooking , cooking in the ground , cooking whole hogs over coals , any of those kinds of things i call bbq , but for me on a personal level , it 's a german/czech style , offset cooking . '' i experiment all the time , at the end of the day feel trumps black and white number or equation you could possibly have . if something 's not tender , it 's just not tender , if something 's dry , it 's just too dry . but , the science behind these things how wood burns , how airflow works , if you start thinking about fluid dynamics inside of a cooker , then science has a pretty huge part of it . i think good bbq is a balance between science and natural gut instinct . cooking is really just thermodynamics and chemistry , but tastier . inside the smoker , air molecules are moving around really rapidly thanks to that fire , they 're vibrating all crazy , and when they smack into the brisket , they transfer that energy to the meat , either contributing chemical reactions or raising the temperature . meat browns when it cooks , whether it 's direct heat like a steak or slow like bbq . heat breaks proteins down into amino acids , which then react with sugars to create molecular deliciousness , which happens to be brown . it 's not caramelization , it 's something called the maillard reaction . king of bbq here in texas is brisket . it started out with whole animals , you would sell what you could and then whatever was left , as a method of preservation , you would bbq stuff on sundays for us to fully understand the science of bbq , we need to know a little about the hunk of meat we 're cooking . meat in general is muscle , which is primarily protein , fat , some vitamins and minerals , and whole lot of water . brisket comes from across chest area of cow , right here , and since cattle do n't have collarbones like us , this muscle has to support more than half their body weight . that means it 's got a lot of three things : hard-working muscle , fat , and connective tissue . it 's basically the opposite of filet mignon . but if we apply the right kind of science , those three things can come together like voltron to make something very tasty . so at the end of the day you want it to be tender , juicy , good bark , with good fat render . some of you might not want to hear this , but making good bbq is like making jell-o . ribs , brisket , pork shoulder , all cuts of meat that have tons of connective tissue , the molecular glue that supports all those muscle fibers . collagen , one of the proteins in connective tissue , can make up a quarter of all the protein in a mammal 's body . cook 'em fast , and those proteins snap up tight like rubber bands , they have the texture of them too . if you cook them slow , they melt . when collagen is heated slowly and held there for hours ( and hours ) , its long protein chains break down and water works its way in . that collagen turns to gelatin , exactly the same stuff that 's in this box . that 's what makes good bbq so tender inside . it 's meat jell-o . bbq cuts also have a good amount of fat . animal fats are made of triglycerides which have mostly saturated fatty acids . these have much higher melting points than unsaturated fats like , say , vegetable or olive oil you have in your kitchen , because those straight triglyceride tails are stable , packed nice and close . as we heat these saturated fats up , slowly , we can disrupt those hydrogen bonds and turn to liquid , called rendering . which is delicious . together , melting collagen to gelatin and liquefying fat make the meat oh so tender . you need no teeth to eat dis beef . what 's fun about an oven ? there 's nothing fun about ovens . did they have ovens back in the early days , coming up through mexico ? no you dug a hole in the ground , you buried a head , on coals , you cooked on a fire . and that 's where i 'm coming from more on the traditional side of it . i 'm not gon na use electricity , not gon na use gas no assisted heat source of any kind.we have light bulbs , and i do n't even like that so much . and it tastes good . that gets into a whole other thing too , how you 're using wood , green wood , dry wood , post oak , hickory , mesquite , pecan , any of these different kinds of woods they all taste different , they all cook different . the hardwoods used in bbq smoke have lots of cellulose and lignin . when burnt slowly , cellulose caramelizes into sugar molecules that flavor the meat . and lignin is converted into all kinds of aromatic chemicals that flavor the meat , and can even act as chemical preservatives . you just ca n't have brisket , or any bbq , without that beautiful smoke ring . now this is some cool chemistry ! or hot chemistry . meat starts out pink because it 's full of oxygen-carrying molecule called myoglobin . that iron-containing myoglobin starts out red , but as it heats up the iron in its heme group oxidizes and it turns this brown color . so why is the ring still red ? well , bbq smoke contains gases like carbon monoxide and nitric oxide , made by burning wood . that gas diffuse into the edges of the meat , bind to the myoglobin in place of oxygen . and those nitric oxide-myoglobin compounds just so happen to be pink . the edge stays nice and red while the interior gets brown like normal . kinda the art of working a fire is to control those things and get certain flavors out of a piece of wood . it 's not just heat , it 's not just the temperature on a gauge , it 's how the smoke is coming out of the smokestack , it 's how a piece of wood if it flames up and dies out real quick , it 's about a heat curve , how long is it gon na last , are you forcing a piece of wood to do something it does n't want to do ? you ca n't really make a piece of meat do what you want it to do , you can only guide it to do what you think you want it to do . so , kind of go with that , it 's all about trial and error , do n't give up , keep working on it . and if you really wanted to you could watch the bbq with franklin videos . out here we might have beer cans and aprons instead of test tubes and lab coats , but bbq is science , y'all . it 's chemistry , it 's physics , and the best part is you get to eat your experiments . stay curious . and hungry . i 'm gon na go get some food . special thanks to aaron franklin and the whole crew at franklin bbq . if you 're ever in austin , texas , line up early , because this is the best bbq joint in the us . seriously , you can look it up .
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that 's what makes good bbq so tender inside . it 's meat jell-o . bbq cuts also have a good amount of fat .
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why does meat brown as it cooks ? why does this make the meat taste so delicious ?
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deep underground lies stores of once inaccessible natural gas . this gas was likely formed over millions of years as layers of decaying organisms were exposed to intense heat and pressure under the earth 's crust . there 's a technology called hydraulic fracturing , or fracking , that can extract this natural gas , potentially powering us for decades to come . so how does fracking work , and why it is a source of such heated controversy ? a fracking site can be anywhere with natural gas , from a remote desert to several hundred feet from your backyard . it starts out with a long vertical hole known as a wellbore drilled down through layers of sediment . when the well reaches 2500 - 3000 meters , it 's at its kickoff point where it can begin the process of horizontal drilling . it turns 90 degrees and extends horizontally for about 1.5 kilometers through a compressed black layer called the shale rock formation . a specialized perforating gun is then lowered and fired , creating a series of small , inch-long holes that burst through the well 's casing into the rock layer . about three to four months after the initial drilling , the well is ready for fracking to begin . fracking fluid is pumped down into the well at a pressure so high , it cracks the shale rock , creating fractures through which the trapped gas and oil can escape . the fluid itself is more than 90 % water . the rest is made up of concentrated chemical additives . these vary depending on the specific characteristics of the fracking site , but usually fall into three categories : acids for clearing debris and dissolving minerals , friction-reducing compounds to create a slippery form of water known as slickwater , and disinfectant to prevent bacteria growth . sand or clay is also mixed into the water to prop open the fissures so the gas and oil can keep leaking out , even after the pressure is released . it 's estimated that all of fracking 's intense pumping and flushing uses an average of 3-6 million gallons of water per well . that 's actually not a lot compared to agriculture , power plants , or even golf course maintenance , but it can have a notable impact on local water supply . and disposing of used fracking water is also an issue . along with the trapped gas that 's pumped up to the surface , millions of gallons of flow-back liquid come gushing up . this liquid containing contaminants like radioactive material , salts , heavy metals , and hydrocarbons , needs to be stored and disposed of . that 's usually done in pits on-site in deep wells or off-site at water treatment facilities . another option is to recycle the flow-back liquid , but the recycling process can actually increase levels of contamination since the water is more toxic with each use . wells are typically encased in steel and cement to prevent contaminants from leaking into groundwater . but any negligence or fracking-related accidents can have devastating effects . fracturing directly into underground water hazardous underground seepage and leakage , and inadequate treatment and disposal of highly-toxic waste water can potentially contaminate drinking water around a fracking site . there 's also concern about the threat of earthquakes and damaged infrastructure from pressure and waste water injection . links between fracking and increased seismic activity leave unresolved questions about long-term pressure imbalances that might be happening deep beneath our feet . fracking 's biggest controversy , though , is happening above the ground . the general consensus is that burning natural gas is better for the environment than burning coal since the gas collected from fracking emits only half the carbon dioxide as coal per unit of energy . the pollution caused by the fracking itself , though , is n't negligible . methane that leaks out during the drilling and pumping process is many times more potent than carbon dioxide as a greenhouse gas . some scientists argue that methane eventually dissipates , so has a relatively low long-term impact . but a greater question hangs in the air . does fracking take time , money , and research away from the development of cleaner renewable energy sources ? natural gas is non-renewable , and the short-run economic interests supporting fracking may fall short in the face of global climate change . experts are still examining fracking 's overarching effects . although modern fracking has been around since the 1940s , it 's boomed in the last few decades . as other sources of natural gas decrease , the costs of non-renewable energies rise , and cutting-edge technologies make it so accessible . but many countries and regions have already banned fracking in response to environmental concerns . it 's undeniable that fracking has reshaped the energy landscape around the world , but for what long-term benefit and at what cost ?
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about three to four months after the initial drilling , the well is ready for fracking to begin . fracking fluid is pumped down into the well at a pressure so high , it cracks the shale rock , creating fractures through which the trapped gas and oil can escape . the fluid itself is more than 90 % water .
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what causes the “ fracking ” of the shale rock ?
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about 66 million years ago , something terrible happened to life on our planet . ecosystems were hit with a double blow as massive volcanic eruptions filled the atmosphere with carbon dioxide and an asteroid roughly the size of manhattan struck the earth . the dust from the impact reduced or stopped photosynthesis from many plants , starving herbivores and the carnivores that preyed on them . within a short time span , three-quarters of the world 's species disappeared forever , and the giant dinosaurs , flying pterosaurs , shelled squids , and marine reptiles that had flourished for ages faded into prehistory . it may seem like the dinosaurs were especially unlucky , but extinctions of various severities have occurred throughout the earth 's history , and are still happening all around us today . environments change , pushing some species out of their comfort zones while creating new opportunities for others . invasive species arrive in new habitats , outcompeting the natives . and in some cases , entire species are wiped out as a result of activity by better adapted organisms . sometimes , however , massive changes in the environment occur too quickly for most living creatures to adapt , causing thousands of species to die off in a geological instant . we call this a mass extinction event , and although such events may be rare , paleontologists have been able to identify several of them through dramatic changes in the fossil record , where lineages that persisted through several geological layers suddenly disappear . in fact , these mass extinctions are used to divide the earth 's history into distinct periods . although the disappearance of the dinosaurs is the best known mass extinction event , the largest occurred long before dinosaurs ever existed . 252 million years ago , between the permian and triassic periods , the earth 's land masses gathered together into the single supercontinent pangaea . as it coalesced , its interior was filled with deserts , while the single coastline eliminated many of the shallow tropical seas where biodiversity thrived . huge volcanic eruptions occurred across siberia , coinciding with very high temperatures , suggesting a massive greenhouse effect . these catastrophes contributed to the extinction of 95 % of species in the ocean , and on land , the strange reptiles of the permian gave way to the ancestors of the far more familiar dinosaurs we know today . but mass extinctions are not just a thing of the distant past . over the last few million years , the fluctuation of massive ice sheets at our planet 's poles has caused sea levels to rise and fall , changing weather patterns and ocean currents along the way . as the ice sheets spread , retreated , and returned , some animals were either able to adapt to the changes , or migrate to a more suitable environment . others , however , such as giant ground sloths , giant hyenas , and mammoths went extinct . the extinction of these large mammals coincides with changes in the climate and ecosystem due to the melting ice caps . but there is also an uncomfortable overlap with the rise of a certain hominid species originating in africa 150,000 years ago . in the course of their adaptation to the new environment , creating new tools and methods for gathering food and hunting prey , humans may not have single-handedly caused the extinction of these large animals , as some were able to coexist with us for thousands of years . but it 's clear that today , our tools and methods have become so effective that humans are no longer reacting to the environment , but are actively changing it . the extinction of species is a normal occurrence in the background of ecosystems . but studies suggest that rates of extinction today for many organisms are hundreds to thousands of times higher than the normal background . but the same unique ability that makes humans capable of driving mass extinctions can also enable us to prevent them . by learning about past extinction events , recognizing what is happening today as environments change , and using this knowledge to lessen our effect on other species , we can transform humanity 's impact on the world from something as destructive as a massive asteroid into a collaborative part of a biologically diverse future .
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but it 's clear that today , our tools and methods have become so effective that humans are no longer reacting to the environment , but are actively changing it . the extinction of species is a normal occurrence in the background of ecosystems . but studies suggest that rates of extinction today for many organisms are hundreds to thousands of times higher than the normal background .
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species become vulnerable to extinction when :
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there 's a play so powerful that an old superstition says its name should never even be uttered in a theater , a play that begins with witchcraft and ends with a bloody severed head , a play filled with riddles , prophesies , nightmare visions , and lots of brutal murder , a play by william shakespeare sometimes referred to as the `` scottish play '' or the `` tragedy of macbeth . '' first performed at the globe theater in london in 1606 , `` macbeth '' is shakespeare 's shortest tragedy . it is also one of his most action-packed . in five acts , he recounts a story of a scottish nobleman who steals the throne , presides over a reign of terror , and then meets a bloody end . along the way , it asks important questions about ambition , power , and violence that spoke directly to the politics of shakespeare 's time and continue to echo in our own . england in the early 17th century was politically precarious . queen elizabeth i died in 1603 without producing an heir , and in a surprise move , her advisors passed the crown to james stewart , king of scotland . two years later , james was subject to an assassination attempt called the gunpowder plot . questions of what made for a legitimate king were on everyone 's lips . so shakespeare must have known he had potent material when he conflated and adapted the stories of a murderous 11th century scottish king named macbeth and those of several other scottish nobles . he found their annals in hollinshed 's `` chronicles , '' a popular 16th century history of britain and ireland . shakespeare would also have known he needed to tell his story in a way that would immediately grab the attention of his diverse and rowdy audience . the globe welcomed all sections of society . wealthier patrons watched the stage from covered balconies while poorer people paid a penny to take in the show from an open-air section called the pit . talking , jeering , and cheering was common during performances . there are even accounts of audiences throwing furniture when plays were flops . so `` macbeth '' opens with a literal bang . thunder cracks and three witches appear . they announce they 're searching for a scottish nobleman and war hero named macbeth , then fly off while chanting a curse that predicts a world gone mad . `` fair is foul and foul is fair . hover through the fog and filthy air . '' as seen later , they find macbeth and his fellow nobleman banquo . `` all hail macbeth , '' they prophesize , `` that shalt be king hereafter ! '' `` king ? '' macbeth wonders . just what would he have to do to gain the crown ? macbeth and his wife lady macbeth soon chart a course of murder , lies , and betrayal . in the ensuing bloodbath , shakespeare provides viewers with some of the most memorable passages in english literature . `` out , damned spot ! out , i say ! '' lady macbeth cries when she believes she ca n't wipe her victim 's blood off her hands . her obsession with guilt is one of many themes that runs through the play , along with the universal tendency to abuse power , the endless cycles of violence and betrayal , the defying political conflict . as is typical with shakespeare 's language , a number of phrases that got their start in the play have been repeated so many times that they now feel commonplace . they include `` the milk of human kindness , '' `` what 's done is done , '' and the famous witches ' spell , `` double , double toil and trouble ; fire burn , and caldron bubble . '' but shakespeare saves the juiciest bit of all for macbeth himself . towards the end of the play , macbeth reflects on the universality of death and the futility of life . `` out , out , brief candle ! '' he laments . `` life 's but a walking shadow , a poor player that struts and frets his hour upon the stage and then is heard no more . it is a tale told by an idiot , full of sound and fury signifying nothing . '' life may be a tale told my an idiot , but `` macbeth '' is not . shakespeare 's language and characters have entered our cultural consciousness to a rare extent . directors often use the story to shed light on abuses of power , ranging from the american mafia to dictators across the globe . the play has been adapted to film many times , including akira kurosawa 's `` throne of blood , '' which takes place in feudal japan , and a modernized version called `` scotland , pa , '' in which macbeth and his rivals are managers of competing fast food restaurants . no matter the presentation , questions of morality , politics , and power are still relevant today , and so , it seems , is shakespeare 's `` macbeth . ''
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he found their annals in hollinshed 's `` chronicles , '' a popular 16th century history of britain and ireland . shakespeare would also have known he needed to tell his story in a way that would immediately grab the attention of his diverse and rowdy audience . the globe welcomed all sections of society .
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why would people in shakespeare ’ s time have found the story of `` macbeth , '' which was about events that occurred centuries earlier , relevant to their own concerns ?
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in the 16th century , the mathematician robert recorde wrote a book called `` the whetstone of witte '' to teach english students algebra . but he was getting tired of writing the words `` is equal to '' over and over . his solution ? he replaced those words with two parallel horizontal line segments because the way he saw it , no two things can be more equal . could he have used four line segments instead of two ? of course . could he have used vertical line segments ? in fact , some people did . there 's no reason why the equals sign had to look the way it does today . at some point , it just caught on , sort of like a meme . more and more mathematicians began to use it , and eventually , it became a standard symbol for equality . math is full of symbols . lines , dots , arrows , english letters , greek letters , superscripts , subscripts . it can look like an illegible jumble . it 's normal to find this wealth of symbols a little intimidating and to wonder where they all came from . sometimes , as recorde himself noted about his equals sign , there 's an apt conformity between the symbol and what it represents . another example of that is the plus sign for addition , which originated from a condensing of the latin word et meaning and . sometimes , however , the choice of symbol is more arbitrary , such as when a mathematician named christian kramp introduced the exclamation mark for factorials just because he needed a shorthand for expressions like this . in fact , all of these symbols were invented or adopted by mathematicians who wanted to avoid repeating themselves or having to use a lot of words to write out mathematical ideas . many of the symbols used in mathematics are letters , usually from the latin alphabet or greek . characters are often found representing quantities that are unknown , and the relationships between variables . they also stand in for specific numbers that show up frequently but would be cumbersome or impossible to fully write out in decimal form . sets of numbers and whole equations can be represented with letters , too . other symbols are used to represent operations . some of these are especially valuable as shorthand because they condense repeated operations into a single expression . the repeated addition of the same number is abbreviated with a multiplication sign so it does n't take up more space than it has to . a number multiplied by itself is indicated with an exponent that tells you how many times to repeat the operation . and a long string of sequential terms added together is collapsed into a capital sigma . these symbols shorten lengthy calculations to smaller terms that are much easier to manipulate . symbols can also provide succinct instructions about how to perform calculations . consider the following set of operations on a number . take some number that you 're thinking of , multiply it by two , subtract one from the result , multiply the result of that by itself , divide the result of that by three , and then add one to get the final output . without our symbols and conventions , we 'd be faced with this block of text . with them , we have a compact , elegant expression . sometimes , as with equals , these symbols communicate meaning through form . many , however , are arbitrary . understanding them is a matter of memorizing what they mean and applying them in different contexts until they stick , as with any language . if we were to encounter an alien civilization , they 'd probably have a totally different set of symbols . but if they think anything like us , they 'd probably have symbols . and their symbols may even correspond directly to ours . they 'd have their own multiplication sign , symbol for pi , and , of course , equals .
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sets of numbers and whole equations can be represented with letters , too . other symbols are used to represent operations . some of these are especially valuable as shorthand because they condense repeated operations into a single expression .
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the symbol used to represent a factorial is the :
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take a moment to think about the us constitution . what 's the first thing that comes to mind ? freedom of speech ? protection from illegal searches ? the right to keep and bear arms ? these passages are cited so often that we can hardly imagine the document without them , but that 's exactly what the writers of the constitution did . the list of individual freedoms known as the bill of rights was not in the original text and was n't added for another three years . so does this mean the founders did n't consider them ? the answer goes back to the very origins of the constitution itself . even prior to the first shots of the american revolution , the thirteen colonies worked together through a provisional government called the continental congress . during the war in 1781 , the articles of confederation were ratified as the first truly national government . but establishing a new nation would prove easier than running it . congress had no power to make the states comply with their laws . when the national government proved unable to raise funds , enforce foreign treaties , or suppress rebellions , it was clear reform was needed . so in may 1787 , all the states but rhode island sent delegates to philidelphia for a constitutional convention . a majority of these delegates favored introducing a new national constitution to create a stronger federal government . thanks to compromises on issues like state representation , taxation power , and how to elect the president , their proposal gradually gained support . but the final text drafted in september still had to be approved by conventions held in the states . so over the next few months , ratification would be debated across the young nation . among those who championed the new document were leading statesmen alexander hamilton , james madison , and john jay . together , they laid out eloquent philosophical arguments for their positions in a series of 85 essays now known as the federalist papers . but others felt the constitution was overreaching and that more centralized authority would return the states to the sort of tyranny they had just escaped . these anti-federalists were especially worried by the text 's apparent lack of protections for individual liberties . as the conventions proceeded , many of these critics shifted from opposing the constitution entirely to insisting on adding an explicit declaration of rights . so what was the federalists problem with this idea ? while their opponents accused them of despotism , wanting to maintain absolute power in the central government , their real motives were mostly practical . changing the constitution when it had already been ratified by some states could complicate the entire process . more importantly , madison felt that people 's rights were already guaranteed through the democratic process , while adding extra provisions risked misinterpretation . and some feared that creating an explicit list of things the government ca n't do would imply that it can do everything else . after the first five states ratified the constitution quickly , the debate grew more intense . massachusetts and several other states would only ratify if they could propose their own amendments for consideration . leading federalists recognized the need to compromise and promised to give them due regard . once ratification by nine states finally brought the constitution into legal force , they made good on their promise . during a meeting of the first united states congress , representative james madison stood on the house floor to propose the very amendments he had previously believed to be unnecessary . after much debate and revision , first in the congress , and then in the states , ten amendments were ratified on december 15 , 1791 , over three years after the us constitution had become law . today , every sentence , word , and punctuation mark in the bill of rights is still considered fundamental to the freedoms americans enjoy , even though the original framers left them out .
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take a moment to think about the us constitution . what 's the first thing that comes to mind ?
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how does the logic of the anti-federalist opposition to the constitution assist in securing a bill of rights to the constitution ?
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ok , fermium , it has absolutely no use as far as anyone knows except that it ’ s extremely radioactive . it ’ s named after enrico fermi who is a well-known physicist . fermi was an italian physicist who in the 1930s was the first person to discover artificial radioactivity . this is where neutrons , which had only recently been discovered when they did these experiments , hit an element that is not radioactive , increase the weight of the nucleus but not the number of protons and cause it to fall apart by radioactive decay . and it also , like einsteinium , where it was first found in the debris of a nuclear bomb , in fact the very first nuclear bomb that was ever tested . shortly after the fascists took power in italy , fermi moved to the united states and , as part of the manhattan project for building the atomic bomb , he built the first nuclear reactor under the football stadium , in the squash courts under the football stadium at chicago university , the university of chicago , right in the centre of chicago , and they filled the squash courts with blocks of carbon with holes in the middle through which they put rods of uranium . so the first ever sustained nuclear reaction took place in the sports field of university of chicago and if you go now there , the stadium itself has been completely demolished , but there ’ s a rather fine monument to the birth of the atomic era .
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this is where neutrons , which had only recently been discovered when they did these experiments , hit an element that is not radioactive , increase the weight of the nucleus but not the number of protons and cause it to fall apart by radioactive decay . and it also , like einsteinium , where it was first found in the debris of a nuclear bomb , in fact the very first nuclear bomb that was ever tested . shortly after the fascists took power in italy , fermi moved to the united states and , as part of the manhattan project for building the atomic bomb , he built the first nuclear reactor under the football stadium , in the squash courts under the football stadium at chicago university , the university of chicago , right in the centre of chicago , and they filled the squash courts with blocks of carbon with holes in the middle through which they put rods of uranium .
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where did the first sustained nuclear chain reaction take place ?
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if someone asked you who the richest people in history were , who would you name ? perhaps a billionaire banker or corporate mogul , like bill gates or john d. rockefeller . how about african king musa keita i ? ruling the mali empire in the 14th century ce , mansa musa , or the king of kings , amassed a fortune that possibly made him one of the wealthiest people who ever lived . but his vast wealth was only one piece of his rich legacy . when mansa musa came to power in 1312 , much of europe was racked by famine and civil wars . but many african kingdoms and the islamic world were flourishing , and mansa musa played a great role in bringing the fruits of this flourishing to his own realm . by strategically annexing the city of timbuktu , and reestablishing power over the city of gao , he gained control over important trade routes between the mediterranean and the west african coast , continuing a period of expansion , which dramatically increased mali 's size . the territory of the mali empire was rich in natural resources , such as gold and salt . the world first witnessed the extent of mansa musa 's wealth in 1324 when he took his pilgrimage to mecca . not one to travel on a budget , he brought a caravan stretching as far as the eye could see . accounts of this journey are mostly based on an oral testimony and differing written records , so it 's difficult to determine the exact details . but what most agree on is the extravagant scale of the excursion . chroniclers describe an entourage of tens of thousands of soldiers , civilians , and slaves , 500 heralds bearing gold staffs and dressed in fine silks , and many camels and horses bearing an abundance of gold bars . stopping in cities such as cairo , mansa musa is said to have spent massive quantities of gold , giving to the poor , buying souvenirs , and even having mosques built along the way . in fact , his spending may have destabilized the regional economy , causing mass inflation . this journey reportedly took over a year , and by the time mansa musa returned , tales of his amazing wealth had spread to the ports of the mediterranean . mali and its king were elevated to near legendary status , cemented by their inclusion on the 1375 catalan atlas . one of the most important world maps of medieval europe , it depicted the king holding a scepter and a gleaming gold nugget . mansa musa had literally put his empire and himself on the map . but material riches were n't the king 's only concern . as a devout muslim , he took a particular interest in timbuktu , already a center of religion and learning prior to its annexation . upon returning from his pilgrimage , he had the great djinguereber mosque built there with the help of an andalusian architect . he also established a major university , further elevating the city 's reputation , and attracting scholars and students from all over the islamic world . under mansa musa , the empire became urbanized , with schools and mosques in hundreds of densely populated towns . the king 's rich legacy persisted for generations and to this day , there are mausoleums , libraries and mosques that stand as a testament to this golden age of mali 's history .
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one of the most important world maps of medieval europe , it depicted the king holding a scepter and a gleaming gold nugget . mansa musa had literally put his empire and himself on the map . but material riches were n't the king 's only concern .
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summarize mansa musa 's accomplishments and contributions to the mali empire upon his return from his pilgrimage to mecca .
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massive vines that blanket the southern united states , climbing as high as 100 feet as they uproot trees and swallow buildings . a ravenous snake that is capable of devouring an alligator . rabbit populations that eat themselves into starvation . these are n't horror movie concepts . they 're real stories , but how could such situations exist in nature ? all three are examples of invasive species , organisms harmful not because of what they are , but where they happen to be . the kudzu vine , for example , had grown quality in its native east asia , eaten by various insects and dying off during the cold winters . but its fortunes changed when it was imported into the southeastern united states for porch decoration and cattle feed . its planting was even subsidized by the government to fight soil erosion . with sunny fields , a mild climate , and no natural predators in its new home , the vine grew uncontrollably until it became known as the plant that ate the south . meanwhile in florida 's everglades , burmese pythons , thought to have been released by pet owners , are the cause of decreasing populations of organisms . they 're successfully outcompeting top predators , such as the alligator and panther , causing a significant reduction in their food sources . they 're not a problem in their native asia because diseases , parasites , and predators help to control their population size . and in australia , european rabbits eat so many plants that they wipe out the food supply for themselves and other herbivores . they 're a pretty recent addition , intentionally introduced to the continent because one man enjoyed hunting them . like the burmese pythons , various factors in their native habitat keep their numbers in control . but in australia , the lack of predators and a climate perfect for year-long reproduction allows their populations to skyrocket . so why does this keep happening ? most of the world 's ecosystems are the result of millennia of coevolution by organisms , adapting to their environment and each other until a stable balance is reached . healthy ecosystems maintain this balance via limiting factors , environmental conditions that restrict the size or range of a species . these include things like natural geography and climate , food availability , and the presence or absence of predators . for example , plant growth depends on levels of sunlight and soil nutrients . the amount of edible plants affects the population of herbivores , which in turn impacts the carnivores that feed on them . and a healthy predator population keeps the herbivores from becoming too numerous and devouring all the plants . but even minor changes in one factor can upset this balance , and the sudden introduction of non-native organisms can be a pretty major change . a species that is evolved in a separate habitat will be susceptible to different limiting factors , different predators , different energy sources , and different climates . if the new habitat 's limiting factors fail to restrict the species growth , it will continue to multiply , out-competing native organisms for resources and disrupting the entire ecosystem . species are sometimes introduced into new habitats through natural factors , like storms , ocean currents , or climate shifts . the majority of invasive species , though , are introduced by humans . often this happens unintentionally , as when the zebra mussel was accidentally brought to lake erie by cargo ships . but as people migrate around the world , we have also deliberately brought our plants and animals along , rarely considering the consequences . but now that we 're learning more about the effects of invasive species on ecosystems , many governments closely monitor the transport of plants and animals , and ban the imports of certain organisms . but could the species with the most drastic environmental impact be a group of primates who emerged from africa to cover most of the world ? are we an invasive species ?
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but as people migrate around the world , we have also deliberately brought our plants and animals along , rarely considering the consequences . but now that we 're learning more about the effects of invasive species on ecosystems , many governments closely monitor the transport of plants and animals , and ban the imports of certain organisms . but could the species with the most drastic environmental impact be a group of primates who emerged from africa to cover most of the world ?
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even though governments monitor the transport of plants and animals , what other strategies could be adopted to stop the unwanted introductions of non-native species ?
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tellurium is , is quite a nice element here . i shall pick it up carefully . tellurium . you ’ ve never had anything to do with this ? nothing to do with it in my life . so this is a new one for me . this is tellurium powder . so let ’ s see what ’ s inside the vial . so as we open it and tap out the glass vial . this one is going to be stubborn . this bell shape here is a sample of tellurium . the reason…shall i hold it for you ? … so , a sample of tellurium . i ’ m slightly cagey about touching this because as i think i explained with selenium that , if you ingest tellurium into the body it can get into your sweat and make you smell enough to really drive people mad . and these crystals like this one can be cut up and mounted into a piece of apparatus like this . so a chemist won ’ t deal with all the elements on the periodic table in his career normally . no , no , very few chemists will deal with more than perhaps a handful of different elements . so this is the tellurium and this is , again , this is very high standard material . 3 grams of the tellurium material and you can see it ’ s a very dark powder at the bottom of the vial . it was used in this piece of apparatus to shine in an infrared laser that ’ s like a heat ray at one frequency and it came out as twice the frequency . so you can use it to change the effect of the lasers . unfortunately the guy doing it didn ’ t make a very good job of it and you can see he ’ s completely burnt the surface of this piece of tellurium . so the main use of tellurium is as components like this for laser optics and it ’ s not widely used in the chemical industry or similar areas .
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i shall pick it up carefully . tellurium . you ’ ve never had anything to do with this ?
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what tellurium compound can you find in the rewritable data layer of cds , dvds , and blu-ray discs ?
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in 1977 , the physicist edward purcell calculated that if you push a bacteria and then let go , it will stop in about a millionth of a second . in that time , it will have traveled less than the width of a single atom . the same holds true for a sperm and many other microbes . it all has to do with being really small . microscopic creatures inhabit a world alien to us , where making it through an inch of water is an incredible endeavor . but why does size matter so much for a swimmer ? what makes the world of a sperm so fundamentally different from that of a sperm whale ? to find out , we need to dive into the physics of fluids . here 's a way to think about it . imagine you are swimming in a pool . it 's you and a whole bunch of water molecules . water molecules outnumber you a thousand trillion trillion to one . so , pushing past them with your gigantic body is easy , but if you were really small , say you were about the size of a water molecule , all of a sudden , it 's like you 're swimming in a pool of people . rather than simply swishing by all the teeny , tiny molecules , now every single water molecule is like another person you have to push past to get anywhere . in 1883 , the physicist osborne reynolds figured out that there is one simple number that can predict how a fluid will behave . it 's called the reynolds number , and it depends on simple properties like the size of the swimmer , its speed , the density of the fluid , and the stickiness , or the viscosity , of the fluid . what this means is that creatures of very different sizes inhabit vastly different worlds . for example , because of its huge size , a sperm whale inhabits the large reynolds number world . if it flaps its tail once , it can coast ahead for an incredible distance . meanwhile , sperm live in a low reynolds number world . if a sperm were to stop flapping its tail , it would n't even coast past a single atom . to imagine what it would feel like to be a sperm , you need to bring yourself down to its reynolds number . picture yourself in a tub of molasses with your arms moving about as slow as the minute hand of a clock , and you 'd have a pretty good idea of what a sperm is up against . so , how do microbes manage to get anywhere ? well , many do n't bother swimming at all . they just let the food drift to them . this is somewhat like a lazy cow that waits for the grass under its mouth to grow back . but many microbes do swim , and this is where those incredible adaptations come in . one trick they can use is to deform the shape of their paddle . by cleverly flexing their paddle to create more drag on the power stroke than on the recovery stroke , single-celled organisms like paramecia manage to inch their way through the crowd of water molecules . but there 's an even more ingenious solution arrived at by bacteria and sperm . instead of wagging their paddles back and forth , they wind them like a cork screw . just as a cork screw on a wine bottle converts winding motion into forward motion , these tiny creatures spin their helical tails to push themselves forward in a world where water feels as thick as cork . other strategies are even stranger . some bacteria take batman 's approach . they use grappling hooks to pull themselves along . they can even use this grappling hook like a sling shot and fling themselves forward . others use chemical engineering . h. pylori lives only in the slimy , acidic mucus inside our stomachs . it releases a chemical that thins out the surrounding mucus , allowing it to glide through slime . maybe it 's no surprise that these guys are also responsible for stomach ulcers . so , when you look really closely at our bodies and the world around us , you can see all sorts of tiny creatures finding clever ways to get around in a sticky situation . without these adaptations , bacteria would never find their hosts , and sperms would never make it to their eggs , which means you would never get stomach ulcers , but you would also never be born in the first place . ( pop )
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if it flaps its tail once , it can coast ahead for an incredible distance . meanwhile , sperm live in a low reynolds number world . if a sperm were to stop flapping its tail , it would n't even coast past a single atom .
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the video creates a distinction between the `` low reynolds number world '' inhabited by microbes such as bacteria and sperm , and the `` large reynolds number '' inhabited by macroscopic creatures like humans or whales . based on what your learned in the video , why is it more difficult to swim in a low reynolds number world compared to a large reynolds number world ?
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translator : tom carter reviewer : bedirhan cinar of all the spectacles mankind has viewed through a telescope , there are few lovelier than a spiral galaxy . majestic whirlpools of stars , they rotate in a stately and predictable dance . the fact that we see many billions of them in our telescopes tells us they are both common and stable . it is perhaps surprising that it is relatively easy to understand the inner workings of these cosmic pinwheels . by combining physical principles worked out by sir isaac newton in the late 17th century , with the observed amount of mass in a galaxy , scientists can calculate the rates at which these galaxies rotate . using these techniques , astronomers predict how fast stars at different distances from the center of the galaxy should move . stars very close to the center move slowly . that 's because there is very little mass between them and the center of the galaxy to pull them along . stars a bit further away move faster , because they are being pulled by all of the stars in between them and the center . as we get really far away , the stars are predicted to move slowly again . their great distance reduces gravity to a gentle tug , so they move leisurely in their orbits . knowing this , scientists looked at the galaxies and measured how fast stars were moving . to their surprise , they found that while the stars closer to the center of the galaxy behaved as predicted , those further away moved far too quickly . this observation was devastating to the tradtional theories of gravity and motion . if the stars were moving as fast as their measurement suggested , galaxies should have torn themselves apart . it was a crisis , and astronomers and physicists scrambled to find a mistake in their calculation . was newton 's theory of gravity wrong ? was his theory of motion wrong ? or was it possible that astronomers had incorrectly measured the galaxy 's mass ? all options were investigated , and all were ruled out . except one . today , scientists believe that the answer lies in a previously unknown kind of matter , called dark matter . this dark matter can be envisioned as a cloud which surrounds most galaxies . this matter is very unusual . it is affected by gravity , but it is invisible to visible light and all other forms of electromagnetic radiation . the name `` dark matter '' originates in this form of matter 's inability to emit or absorb light . dark matter adds to the gravity of the galaxy and explains the orbital speed of stars far from the galactic center . dark matter has not yet been directly observed , but scientists believe that it is likely to be real , mostly because the other options have been ruled out . using dozens of approaches , astronomers and physicists continue to search for direct evidence that would prove that the dark matter hypothesis is true . this question is one of the most important physics research questions of the 21st century .
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it is affected by gravity , but it is invisible to visible light and all other forms of electromagnetic radiation . the name `` dark matter '' originates in this form of matter 's inability to emit or absorb light . dark matter adds to the gravity of the galaxy and explains the orbital speed of stars far from the galactic center .
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dark matter appears to be about five times more common than the familiar form of matter that makes up you and me . when dark energy ( which is another component of the universe ) is taken into consideration , our regular form of matter comprises a mere 5 % of energy and matter in the universe . how do you feel about so much of the universe being comprised of matter that we have never directly observed ?
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i know , insects , it 's really weird , but bear with me . now , i am an entomologist . i confess to that . and , when i look at the planet , the reason i 'm an entomologist is because out of the 1.9 million species that are described on planet earth , over 1 million of them are insects . and i truly believe as a scientist today we live in the best of times because here we are enjoying ted , and facebook , and youtube , and this wonderful theater , healthcare , longer life spans . but we also live in the worst of times because we are on a planet with 7 billion people with a lot of problems . and for those of us who look at biodiversity , it 's a heart-wrenching and wonderful time all together because we see the links between nature and people , and we 're losing them at the same time . both honeybees and humans originate in east africa . and , here in kenya , a wonderful relationship exists where a bird called a honeyguide , up there , has this interesting phenomenon where it actually leads either humans , which it 's done for thousands of years , 77,000 year old paintings from tanzania , and the honey badger to the wild honeybee colony . now , for a long time we thought this relationship first evolved between the honeyguide and the honey badger . but it turns out that it actually evolved between the human and the honeyguide , and the badger 's a parasite . now , when we look at bees , there is this amazing diversity out there , 20,000 species . and one in three bites of food that we eat is thanks to an insect pollinator . so one of the things i 'm working on is looking at those links between nature and sustainable human life . and here are just a few of the beautiful bees that we have in kenya , in fact , not far from nairobi . now , how many of you like coffee ? yeah , i actually ca n't drink it because if i do , my hands shake , and i ca n't pick up ants and bees . chocolate ? i love chocolate , the darker the better , so i really like chocolate . now the thing is , without insect pollinators , there would be very little coffee and no chocolate on the planet . could you imagine that ? that 's really scary ! now , i want to show you out of thousands of examples that i could have brought here today to show you how insects are connected to your life , to every single human being on the planet . here are two colleagues and friends . domina is a farmer in mwanza in western tanzania , and peter is from the kerio valley in northwestern kenya . now , domina grows pigeon feed , cow feed , a whole wide range of legumes . and she feeds her family , she survives in a very remote area based off of these amazing crops , legumes , a lot of traditional vegetables , and all of them are pollinated by these different wild bee species . now , peter grows five varieties of mango on his farm , and he actually paid for his education by growing and selling mangoes . and i really like mangoes and so it 's really a great pleasure working on the farm with five different varieties of mango . and if you look at all these different fruits and crops here , one thing that connects us to biodiversity and one thing we do as a scientist , we write papers . we do research , and we write papers . nobody ever reads them , but here 's one of my papers . it 's on the african violet . this is in the u.s . this florist sells about 10,000 dollars worth of violets a year . it 's worth about 6 billion dollars in trade . it originates in east africa , and we never knew what pollinated it . well , i went off and studied this . one thing to say about pollinators is it comes done to being about sex . and how many of you like sex ? where are we , the vatican ? so what happens when insects help plants have sex is there 's really good sex . this is an example of really good sex . so basically the bee comes along , it vibrates the flower at a specific frequency , 11 to 12 hertz , pollen is released , and the plant survives in the wild . this is one of the world 's most endangered plants . we go up into the deserts of northern kenya , which are now very famous because of the discovery of oil . but i will tell you a little different story . these animals , the camel , which allow life in this very remote community , are browsing off of a shrub called indigofera , and indigofera is 100 % dependent on bee pollination . so all these wild bees produce the indigofera , which the camels and goats eat . and we look at a community like this , nalaray , northern samburu , and people will look at these children and say they are poor . and i disagree because over lunch we collected 30 different bee species in the acacia where they had their lunch and 400 pollinator species in the acacia tortilis where their classroom is located . so i want to leave you with a radical piece of technology called the bee hotel that you can innovate and build for yourself . create a habitat where bees can nest and live in your own backyard . but more importantly , please create space in your hearts for insects . spend five minutes a day with them if you can . and i believe that if the one lesson we can learn from insects is that meek shall inherit the earth .
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but it turns out that it actually evolved between the human and the honeyguide , and the badger 's a parasite . now , when we look at bees , there is this amazing diversity out there , 20,000 species . and one in three bites of food that we eat is thanks to an insect pollinator .
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how many species of bees exist ?
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so radium was the element that was discovered by madam curie and its chemistry is very similar to that of barium , except that it is radioactive and it was used quite widely for treatment of cancer in the days when radiation was used , radioactivity was used , for treating cancer . the idea is that cancer cells , well all cells are liable to be killed by radiation , by radioactivity when they are dividing so cancer cells are cells in the body which are dividing much faster , out-of-control compared to other cells , so if you radiate a patient , the cancer cells , because they are dividing faster , die quicker , so overall although a lot of cells die , the cancer cells die further . the people , who discovered radium , were really excited about it and they were mad with hindsight in the way they treated it . they carried sort of little glass tubes of radium in their pockets and were then surprised when they found burns on their flesh the next day and it ’ s thought that the reason why many of these researchers like madam curie ’ s husband and madam curie died rather young was the effect of the radioactivity of the elements that they handled . well in general as you go down the periodic table , heavier elements tend to be more dangerous . but even the very reactive ones like fluorine are usually not very dangerous because they react with something long before they get into the body . the radioactive elements tend to be dangerous because they can get into the body and then when they decay , they kill cells or even worse than killing the cells is that they change the dna so that the cells mutate into some more aggressive form of cancer .
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the idea is that cancer cells , well all cells are liable to be killed by radiation , by radioactivity when they are dividing so cancer cells are cells in the body which are dividing much faster , out-of-control compared to other cells , so if you radiate a patient , the cancer cells , because they are dividing faster , die quicker , so overall although a lot of cells die , the cancer cells die further . the people , who discovered radium , were really excited about it and they were mad with hindsight in the way they treated it . they carried sort of little glass tubes of radium in their pockets and were then surprised when they found burns on their flesh the next day and it ’ s thought that the reason why many of these researchers like madam curie ’ s husband and madam curie died rather young was the effect of the radioactivity of the elements that they handled .
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where in old watches can we find radium ?
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it starts with a cough , or a wheeze . soon , your chest feels tight . your breathing speeds up and gets shallower , making you feel short of breath . these are common symptoms of an asthma attack . around the world , more than 300 million people suffer from asthma , and around 250,000 people die from it each year . but why do people get asthma and how can this disease be deadly ? asthma affects the respiratory system , particularly the smaller airways , such as the bronchi and bronchioles . these airways have an inner lining called the mucosa that 's surrounded by a layer of smooth muscle . in people with asthma , the airways are chronically inflamed , which can make them hyper-responsive to certain triggers . some of the many asthma triggers include tobacco smoke , pollen , dust , fragrances , exercise , cold weather , stress , and even the common cold . when people with asthma are exposed to these triggers , an asthma attack , or exacerbation , can occur . but how exactly do such everyday factors lead to an asthma attack ? if an asthmatic is exposed to a trigger , the smooth rings of muscle that circle the small airways in their lungs contract and become narrow . simultaneously , the trigger worsens inflammation , causing the mucosal lining to become more swollen and secrete more mucus . under normal conditions , the body uses this mucus to trap and clear particles , like pollen or dust , but during an asthma attack , it blocks the narrowed airways , making it even harder to breathe . these effects lead to this symptoms of asthma . smooth muscle constriction results in the feeling of chest tightness . excess mucus and increased inflammation can cause coughing . and the wheezing noise ? that happens because as the airways constrict , air whistles as it passes through the narrowed space . these symptoms may make a person feel like they 're running out of air . yet counterintuitively , during an asthma attack , the inflammation can make it harder to exhale than inhale . over time , this leads to an excess of air in the lungs , a phenomenon known as hyperinflation . the trapping of air inside the lungs forces the body to work harder to move air in and out of them . over time , this can lead to reduced oxygen delivery to the body 's organs and tissues . sometimes , in untreated severe asthma attacks , the body ca n't keep up , which can lead to death from lack of oxygen . so how do we prevent these uncomfortable and potentially fatal attacks in people who have asthma ? one way is to reduce the presence of triggers . unfortunately , the world is an unpredictable place and exposure to triggers ca n't always be controlled . this is where inhalers , the primary treatment for asthma , come in . these medications help asthmatics both control and prevent their asthma symptoms . inhalers transport medication along the affected airways using a liquid mist or fine powder to treat the problem at its source . they come in two forms . there are reliever medications , which treat symptoms immediately and contain beta-agonists . beta-agonists relax constricted muslces , allowing the airways to widen so more air can travel into and out of the lungs . the other form of inhalers serve as preventive medications , which treat asthma symptoms over the long term , and contain corticosteroids . corticosteroids reduce airway sensitivity and inflammation , so asthma can be kept under control . they 're also crucial in preventing long-term damage from chronic inflammation , which can cause scarring of the airways . inhalers are known to be very effective , and have helped many people live better lives . although we 've come a long way in improving how we treat and diagnose asthma , we still do n't know its exact causes . we currently believe that a combination of genetic and environmental factors play a role , potentially acting during early childhood . recent research has even linked poverty to asthma incidents . this may be due to reasons ranging from exposure to additional pollutants and environmental irritants to difficulties in obtaining medical care or treatment . as our understanding of asthma improves , we can continue to find better ways to keep people 's airways happy and healthy .
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but why do people get asthma and how can this disease be deadly ? asthma affects the respiratory system , particularly the smaller airways , such as the bronchi and bronchioles . these airways have an inner lining called the mucosa that 's surrounded by a layer of smooth muscle .
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asthma primarily affects the ___ and ___ of the respiratory system .
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good evening ! what 's the matter ? are you afraid of vampires ? he he , no need to worry , i 'm not staying for dinner . ( laughter ) i 'm here to guide you through a brief history of vampires , illustrating how our image has changed from a shambling corpse to the dapper gentleman you see before you . vampires are nearly as old as you humans . stories about us , revenants , appear in cultures extending as far back as prehistoric times . but we were n't called vampires back then and most of us did not look the way we imagine vampires today . ha , far from it ! for example , the mesopotamian lamashtu was a creature with the head of a lion and the body of the donkey , and the ancient greek striges were simply described as bloodthirsty birds . others were even stranger . the philippine manananggal would sever her upper torso and sprout huge , bat-like wings to fly . the malaysian penanggalan was a flying female head with dangling entrails . ( laughter ) and the australian yara-ma-yha-who was a little red guy with a big head , a large mouth , and bloodsuckers on his hands and feet . oh , and let 's not forget the caribbean 's soucouyant , the west african obayifo , and the mexican tlahuelpuchi . ( laughter ) charming , are n't they ? though they may look vastly different , all of these beings have one common characteristic : they sustain themselves by consuming the life force of a living creature . this shared trait is what defines a vampire -- all the other attributes change with the tides . so , how do we arrive at the reanimated fellow you see before you ? our modern ideal emerges in 18th-century eastern europe . with the dramatic increase of vampire superstitions , stories of bloodsucking , shadowy creatures become nightly bedside terrors . and popular folklore , like the moroi among the romani people and the lugat in albania , provide the most common vampire traits known today , such as vampires being undead and nocturnal and shape-shifting . you see , eastern europe in the 18th century was a pretty grim place with many deaths occurring from unknown diseases and plagues . without medical explanations , people searched for supernatural causes and found what looked like evidence in the corpses of the victims . when villagers dug up bodies to discern the cause of the mysterious deaths , they would often find the cadavers looking very much alive -- longer hair and fingernails , bloated bellies , and blood at the corners of mouths . ( laughter ) clearly , these people were not really dead . heh , they were vampires ! and they had been leaving their graves to feast on the living . ( grunt ) the terrified villagers would quickly enact a ritual to kill the undead . the practices varied across the region , but usually included beheadings , burnings , and staking the body to the coffin to prevent it from getting up . ( laughter ) grizzly stuff ! but what the villagers interpreted as unholy reanimation were actually normal symptoms of death . when a body decomposes , the skin dehydrates , causing the hair and fingernails to extend . bacteria in the stomach creates gases that fill the belly , which force out blood and matter through the mouth . unfortunately , this science was not yet known , so the villagers kept digging . in fact , so many bodies were dug up that the empress of austria sent her physician around to disprove the vampire stories , and she even established a law prohibiting grave tampering . still , even after the vampire hunts had died down , the stories of legends survived in local superstition . this led to works of literature , such as polidori 's `` the vampyre , '' the gothic novel `` carmilla , '' and , most famously , bram stoker 's `` dracula . '' although stoker incorporated historical material , like elizabeth báthory 's virgin blood baths and the brutal executions of vlad dracul , it was these local myths that inspired the main elements of his story : the transylvanian setting , using garlic to defend oneself , and the staking of the heart . while these attributes are certainly familiar to us , elements he invented himself have also lasted over the years : fear of crucifixes , weakness in sunlight , and the vampire 's inability to see their reflection . by inventing new traits , stoker perfectly enacted the age-old tradition of elaborating upon and expanding the myth of vampires . as we saw , maybe you met my relatives , a huge of variety of creatures stalked the night before dracula , and many more will continue to creep through our nightmares . yet , so long as they subsist off a living being 's life force , they are part of my tribe . even sparkling vampires can be included . after all , it 's the continued storytelling and reimagining of the vampire legend that allows us to truly live forever . ( ominous laughter )
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( laughter ) grizzly stuff ! but what the villagers interpreted as unholy reanimation were actually normal symptoms of death . when a body decomposes , the skin dehydrates , causing the hair and fingernails to extend .
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what frightened villagers interpreted as unholy reanimation were actually normal symptoms of what ?
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what 's so great about the great lakes ? they 're known as america 's inland seas . the north american great lakes huron , ontario , michigan , erie , and superior are so massive that they border eight states and contain 23 quadrillion liters of water . that 's enough to cover the land area of the contiguous united states three meters deep . these vast bodies of water span forest , grassland , and wetland habitats , supporting a region that 's home to over 3,500 species . but how did such a vast and unique geological feature come to be ? the story begins near the end of the last ice age over 10,000 years ago , a time when the climate was warming and the glaciers that cloaked the earth 's surface began their slow retreat . these immense ice sheets carved out a series of basins . those basins filled with water as the ice began to melt , creating the world 's largest area of freshwater lakes . over time , channels developed between these basins , and water began to flow in an ongoing exchange that persists to this day . in fact , today , the interconnected great lakes contain almost 20 % of the world 's supply of fresh surface water . the water 's journey begins in the far north of lake superior , which is the deepest , coldest , and clearest of the lakes , containing half the system 's water . lake superior sinks to depths of 406 meters , creating a unique and diverse ecosystem that includes more that 80 fish species . a given drop of water spends on average 200 years in this lake before flowing into lake michigan or lake huron . linked by the straits of mackinac , these two lakes are technically one . to the west lies lake michigan , the third largest of the lakes by surface area . water slowly moves through its cul-de-sac shape and encounters the world 's largest freshwater dunes , many wildlife species , and unique fossilized coral . to the east is lake huron , which has the longest shoreline . it 's sparsely populated , but heavily forested , including 7,000-year-old petrified trees . below them , water continues to flow southeastwards from lake huron into lake erie . this lake 's status as the warmest and shallowest of the five has ensured an abundance of animal life , including millions of migrating birds . finally , the water reaches its last stop by dramatically plunging more than 50 meters down the thundering niagara falls into lake ontario , the smallest lake by surface area . from there , some of this well-traveled water enters the st. lawrence river , eventually reaching the atlantic ocean . in addition to being a natural wonder , the perpetually flowing great lakes bring us multiple benefits . they provide natural water filtration , flood control , and nutrients cycling . by moving water across more than 3,200 kilometers , the great lakes also provide drinking water for upward of 40 million people and 212 billion liters a day for the industries and farms that line their banks . but our dependence on the system is having a range of negative impacts , too . the great lakes coastal habitats are being degraded and increasingly populated , exposing the once pristine waters to industrial , urban , and agricultural pollutants . because less than 1 % of the water leaves the lake 's system annually , decades-old pollutants still lurk in its waters . humans have also inadvertently introduced more than 100 non-native and invasive species into the lakes , such as zebra and quagga mussels , and sea lampreys that have decimated some indigenous fish populations . on a larger scale , climate change is causing the waters to warm , thus reducing water levels and changing the distribution of aquatic life . luckily , in recent years , governments have started to recognize the immense value of this natural resource . partnerships between the united states and canada are underway to reduce pollution , protect coastal habitats , and halt the spread of invasive species . protecting something as massive as the great lakes system will require the collaboration of many organizations , but the effort is critical if we can preserve the wonder of this flowing inland sea .
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over time , channels developed between these basins , and water began to flow in an ongoing exchange that persists to this day . in fact , today , the interconnected great lakes contain almost 20 % of the world 's supply of fresh surface water . the water 's journey begins in the far north of lake superior , which is the deepest , coldest , and clearest of the lakes , containing half the system 's water .
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how much of earth ’ s available fresh surface water do the great lakes contain ?
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muscles . we have over 600 of them . they make up between 1/3 and 1/2 of our body weight , and along with connective tissue , they bind us together , hold us up , and help us move . and whether or not body building is your hobby , muscles need your constant attention because the way you treat them on a daily basis determines whether they will wither or grow . say you 're standing in front of a door , ready to pull it open . your brain and muscles are perfectly poised to help you achieve this goal . first , your brain sends a signal to motor neurons inside your arm . when they receive this message , they fire , causing muscles to contract and relax , which pull on the bones in your arm and generate the needed movement . the bigger the challenge becomes , the bigger the brain 's signal grows , and the more motor units it rallies to help you achieve your task . but what if the door is made of solid iron ? at this point , your arm muscles alone wo n't be able to generate enough tension to pull it open , so your brain appeals to other muscles for help . you plant your feet , tighten your belly , and tense your back , generating enough force to yank it open . your nervous system has just leveraged the resources you already have , other muscles , to meet the demand . while all this is happening , your muscle fibers undergo another kind of cellular change . as you expose them to stress , they experience microscopic damage , which , in this context , is a good thing . in response , the injured cells release inflammatory molecules called cytokines that activate the immune system to repair the injury . this is when the muscle-building magic happens . the greater the damage to the muscle tissue , the more your body will need to repair itself . the resulting cycle of damage and repair eventually makes muscles bigger and stronger as they adapt to progressively greater demands . since our bodies have already adapted to most everyday activities , those generally do n't produce enough stress to stimulate new muscle growth . so , to build new muscle , a process called hypertrophy , our cells need to be exposed to higher workloads than they are used to . in fact , if you do n't continuously expose your muscles to some resistance , they will shrink , a process known as muscular atrophy . in contrast , exposing the muscle to a high-degree of tension , especially while the muscle is lengthening , also called an eccentric contraction , generates effective conditions for new growth . however , muscles rely on more than just activity to grow . without proper nutrition , hormones , and rest , your body would never be able to repair damaged muscle fibers . protein in our diet preserves muscle mass by providing the building blocks for new tissue in the form of amino acids . adequate protein intake , along with naturally occurring hormones , like insulin-like growth factor and testosterone , help shift the body into a state where tissue is repaired and grown . this vital repair process mainly occurs when we 're resting , especially at night while sleeping . gender and age affect this repair mechanism , which is why young men with more testosterone have a leg up in the muscle building game . genetic factors also play a role in one 's ability to grow muscle . some people have more robust immune reactions to muscle damage , and are better able to repair and replace damaged muscle fibers , increasing their muscle-building potential . the body responds to the demands you place on it . if you tear your muscles up , eat right , rest and repeat , you 'll create the conditions to make your muscles as big and strong as possible . it is with muscles as it is with life : meaningful growth requires challenge and stress .
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the resulting cycle of damage and repair eventually makes muscles bigger and stronger as they adapt to progressively greater demands . since our bodies have already adapted to most everyday activities , those generally do n't produce enough stress to stimulate new muscle growth . so , to build new muscle , a process called hypertrophy , our cells need to be exposed to higher workloads than they are used to .
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everyday activities do not produce significant muscle growth because :
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which is correct : `` a dozen eggs is ? '' or `` a dozen eggs are ? '' i remember being in elementary school , and my teachers making a big deal about the unit . and i never really got that , until one day , i was in the grocery store , and i wanted to buy an apple , but i could n't buy one apple . i had to buy a whole bag of apples . so i did . i bought one bag of apples , i took it home , i took one apple out of the bag , and i cut it up . and then i ate one slice . one bag , one apple , one slice . which of these is the real `` one '' ? well , they all are of course , and that 's what my elementary teachers were trying to tell me . because this is the important idea behind whole number place value , decimal place value and fractions . our whole number system depends on being able to change what we count as `` one '' . our whole number system depends on being able to change units . there are two ways to change units . we can compose , and we can partition . when we compose units , we take a bunch of things , we put them together to make a bigger thing , like a dozen eggs . we take 12 eggs , put them together to make a group , and we call that group a dozen . a dozen eggs is a composed unit . other examples of composed units include a deck of cards , a pair of shoes , a jazz quartet and of course , barbie and ken make a couple . but think about a loaf of bread . that 's not a composed unit , because we do n't get a bunch of slices from a bunch of different bakeries and put them together to make a loaf . no , we start with a loaf of bread and we cut it into smaller pieces called slices , so each slice of bread is a partitioned unit . other examples of partitioned units include a square of a chocolate bar , a section of an orange and a slice of pizza . the important thing about units is that once we 've made a new unit , we can treat it just like we did the old unit . we can compose composed units , and we can partition partitioned units . think about toaster pastries . they come in packs of two , and then those packs get put together in sets of four to make a box . so when i buy one box of toaster pastries , am i buying one thing , four things , or eight things ? it depends on the unit . one box , four packs , eight pastries . and when i share a slice of pizza with a friend , we have to cut `` it '' into two smaller pieces . so a box of toaster pastries is composed of composed units , and when i split a slice of pizza , i 'm partitioning a partitioned unit . but what does that have to do with math ? in math , everything is certain . two plus two equals four , and one is just one . but that 's not really right . one is n't always one . here 's why : we start counting at one , and we count up to nine : 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , and then we get to 10 , and in order to write 10 , we write a one and a zero . that one means that we have one group , and the zero helps us remember that it means one group , not one thing . but 10 , just like one , just like a dozen eggs , just like an egg , 10 is a unit . and 10 tens make 100 . so when i think about 100 , it 's like the box of toaster pastries . is 100 one thing , 10 things or 100 things ? and that depends on what `` one '' is , it depends on what the unit is . so think about all the times in math when you write the number one . no matter what place that one is in , no matter how many things that one represents , one is .
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we take 12 eggs , put them together to make a group , and we call that group a dozen . a dozen eggs is a composed unit . other examples of composed units include a deck of cards , a pair of shoes , a jazz quartet and of course , barbie and ken make a couple .
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an example of a unit composed of composed units is :
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how do you imagine the life of a scientist ? boring and monotonous , spending endless hours in the lab with no social interaction ? maybe for some but not tycho brahe . the 16th century scholar who accurately predicted planetary motion and cataloged hundreds of stars before the telescope had been invented also had a cosmic-sized personal life . tycho brahe was born in 1546 to danish nobles , but at age two was kidnapped to be raised by his uncle instead . his parents did n't seem to mind . tycho was supposed to have a career in law , but after witnessing a solar eclipse at thirteen , he began spending more time with mathematics and science professors , who taught him the art of celestial observation . by the time tycho 's uncle sent him off to germany a few years later , he had lost interest in his law studies , instead reading astronomy books , improving his instruments , and taking careful notes of the night skies . it was n't long before his own measurements were more accurate than those in his books . while in germany , tycho got into a bit of an argument with another student at a party over a mathematical formula , resulting in a sword duel and tycho losing a good-sized chunk of his nose . after that , he was said to have worn a realistic prosthetic of gold and silver that he would glue onto his face . fortunately , tycho did n't need his nose to continue his astronomical work . he kept studying the night sky and creating all sorts of instruments , including a building-sized quadrant for measuring the angles of stars . after months of careful observation , tycho discovered a new star in the constellation cassiopeia . the publication of this discovery granted him rock star status and offers of scientific positions all over europe . wanting to keep him at home , the king of denmark offered to give tycho his own personal island with a state of the art observatory . called uraniborg and costing about 1 % of denmark 's entire budget , this observatory was more of a castle , containing formal gardens , rooms for family , staff and visiting royalty , and an underground section just for all the giant instruments . tycho also built a papermill and printing press for publishing his papers , and a lab for studying alchemy . and since no castle would be complete without entertainment , tycho employed a clairvoyant dwarf named jep as court jester . tycho lived on his island , studying and partying for about 20 years . but after falling out with the new danish king , he took up an invitation from the holy roman emperor to become the official imperial astronomer in prague . there , he met another famous astronomer johannes kepler , who became his assistant . while kepler 's work interested him , tycho was protective of his data , and the two often got into heated arguments . in 1601 , tycho attended a formal banquet where he drank quite a lot but was too polite to leave the table to relieve himself , deciding to tough it out instead . this proved to be a bad idea , as he quickly developed a bladder infection and died a few days later . but over 400 years after his death , tycho still had a few surprises up his sleeve . when his body was exhumed and studied in 2010 , the legendary gold and silver nose was nowhere to be found , with chemical traces suggesting that he wore a more casual brass nose instead . tycho 's mustache hair was also found to contain unusually high levels of toxic mercury . was it from a medicine used to treat his bladder infection ? a residue from his alchemy experiments ? or did his quarrelsome coworker johannes kepler poison him to acquire his data ? we may never know , but the next time you think scientists lead boring lives , dig a little deeper . a fascinating story may be just beyond the tip of your nose .
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after that , he was said to have worn a realistic prosthetic of gold and silver that he would glue onto his face . fortunately , tycho did n't need his nose to continue his astronomical work . he kept studying the night sky and creating all sorts of instruments , including a building-sized quadrant for measuring the angles of stars .
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as a result of his findings , brahe became a science celebrity and was granted nearly limitless resources to continue his work . what present-day scientists have attained celebrity status based on their work ?
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translator : sara xiao fei reviewer : sebastian betti so , this is a map of new york state that was made in 1937 by the general drafting company . it 's an extremely famous map among cartography nerds , because down here at the bottom of the catskill mountains there is a little town called roscoe - actually , this will go easier if i just put it up here - there 's roscoe , and then , right above roscoe , is rockland , new york , and then right above that is the tiny town of agloe , new york . agloe , new york , is very famous to cartographers , because it 's a paper town . it 's also known as a copyright trap . because my map of new york and your map of new york are going to look very similar , on account of the shape of new york . often , map makers will insert fake places onto their maps , in order to protect their copyright , because then , if my fake place shows up on your map , i can be well and truly sure that you have robbed me . agloe is a scrabblization of the initials of the two guys who made this map ernest g. alpers and otto lindberg , and they released this map in 1937 . decades later , rand mcnally releases a map with agloe , new york , on it , at the same exact intersection of two dirt roads in the middle of nowhere . well , you can imagine the delight over at general drafting . they immediately called rand mcnally , and they say , `` we 've caught you ! we made agloe , new york , up . it is a fake place . it 's a paper town . we 're going to sue your pants off ! '' and rand mcnally says , `` no , no , no , no , agloe is real . '' because people kept going to that intersection of two dirt roads ( laughter ) in the middle of nowhere , expecting there to be a place called agloe , someone built a place called agloe , new york . it had a gas station , a general store , two houses at its peak . ( laughter ) and this is of course a completely irresistible metaphor to a novelist , because we would all like to believe that the stuff that we write down on paper can change the actual world in which we 're actually living - which is why my third book is called `` paper towns '' . but what interests me ultimately more than the medium in which this happened is the phenomenon itself . it 's easy enough to say that the world shapes our maps of the world , right ? like the overall shape of the world is obviously going to affect our maps . but what i find a lot more interesting is the way that the manner in which we map the world changes the world . because the world would truly be a different place if north were down . and the world would be a truly different place if alaska and russia were n't on opposite sides of the map . and the world would be a different place if we projected europe to show it in its actual size . the world is changed by our maps of the world . the way that we choose to , sort of , our personal cartographic enterprise also shapes the map of our lives , and that in turn shapes our lives . i believe that what we map changes the life we lead . and i do n't mean that in some , like , secrecy oprah 's angels network , like , you-can-think-your-way-out -of-cancer sense . but i do believe that while maps do n't show you where you will go in your life , they show you where you might go . you very rarely go to a place that is n't on your personal map . so i was a really terrible student when i was a kid . my gpa was consistently in the low 2s , and i think the reason that i was such a terrible student is that i felt like education was just a series of hurdles that had been erected before me , and i had to jump over in order to achieve adulthood . and i did n't really want to jump over these hurdles , because they seemed completely arbitrary , so i often would n't , and then people would threaten me , you know , they 'd threaten me with `` this going on my permanent record '' , or `` you 'll never get a good job '' . i did n't want a good job ! as far as i could tell at eleven or twelve years old , like , people with good jobs woke up very early in the morning , ( laughter ) and the men who had good jobs , one of the first things they did was tie a strangulation item of clothing around their necks . they literally put nooses on themselves , and then they went off to their jobs , whatever they were . that 's not a recipe for a happy life . these people - in my , symbol-obsessed , twelve-year-old imagination , these people who are strangling themselves as one of the first things they do each morning , they ca n't possibly be happy . why would i want to jump over all these hurdles and have that be the end ? that 's a terrible end ! and then , when i was in tenth grade , i went to this school , indian springs school , a small boarding school , outside of birmingham , alabama , and all at once i became a learner . and i became a learner , because i found myself in a community of learners . i found myself surrounded by people who celebrated intellectualism and engagement , and who thought that my ironic oh-so-cool disengagement was n't clever , or funny , but , like , it was a simple and unspectacular response to very complicated and compelling problems . and so i started to learn , because learning was cool . i learned that some infinite sets are bigger than other infinite sets , and i learned what iambic pentameter is and why it sounds so good to human ears . i learned that the civil war was a nationalizing conflict , i learned some physics , i learned that correlation should n't be confused with causation - all of these things , by the way , enriched my life on a literally daily basis . and it 's true that i do n't use most of them for my `` job '' , but that 's not what it 's about for me . it 's about cartography . what is the process of cartography ? it 's , you know , sailing upon some land , and thinking `` i think i 'll draw that bit of land '' , and then wondering , `` maybe there 's some more land to draw '' . and that 's when learning really began for me . it 's true that i had teachers that did n't give up on me , and i was very fortunate to have those teachers , because i often gave them cause to think there was no reason to invest in me . but a lot of the learning that i did in high school was n't about what happened inside the classroom , it was about what happened outside of the classroom . for instance , i can tell you that , `` there 's a certain slant of light , [ on ] winter afternoons , that oppresses , like the heft [ weight ] of cathedral tunes '' , not because i memorized emily dickinson in school , when i was in high school , but because there was a girl , when i was in high school , and her name was amanda , and i had a crush on her , and she liked emily dickinson poetry . the reason i can tell you what opportunity cost is , is because one day when i was playing super mario kart on my couch , my friend emmet walked in , and he said , `` how long have you been playing super mario kart ? `` , and i said , `` i do n't know , like , six hours ? `` , and he said , `` you realize that if you 'd worked at baskin-robbins those six hours , you could have made thirty dollars , so in some ways , you just paid thirty dollars to play super mario kart '' , and i was , like , `` i 'll take that deal . '' ( laughter ) but i learned what opportunity cost is , and along the way , the map of my life got better , it got bigger , it contained more places . there were more things that might happen , more futures i might have . it was n't a formal organized learning process , and i 'm happy to admit that . it was spotty , it was inconsistent , there was a lot i did n't know . i might know , you know , that cantor 's idea that some infinite sets are larger than other infinite sets , but i did n't really understand the calculus behind that idea . i might know the idea of opportunity cost , but i did n't know the law of diminishing returns . but the great thing about imagining learning as cartography , instead of imagining it as arbitrary hurdles that you have to jump over is that you see a bit of coast line , and that makes you want to see more . and so now i do know at least some of the calculus that underlies all of that stuff . so , i had one learning community in high school , then i went to another for college , and then i went to another , when i started working at a magazine called `` booklist '' , where i was an assistant surrounded by astonishingly well-read people , and then i wrote a book , and like all authors dream of doing , i promptly quit my job . and for the first time since high school , i found myself without a learning community , and it was miserable . i hated it . i read many , many books during this two-year period . i read books about stalin , and books about how the uzbek people came to identify as muslims , and i read books about how to make atomic bombs , but it just felt like i was creating my own hurdles , and then jumping over them myself , instead of feeling the excitement of being part of a community of learners , a community of people who are engaged together in a cartographic enterprise of trying to better understand and map the world around us . and then , in 2006 , i met that guy . his name is ze frank . i did n't actually meet him , just on the internet . ze frank was running , at the time , a show called `` the show with ze frank '' , and that was my way back into being a community learner again . here 's ze talking about las vegas : ( video ) ze frank : las vegas was built in the middle of a huge hot desert , almost everything here was brought from somewhere else - the sort of rocks , the trees , the waterfalls . these fish are almost as out of place as my pig that flew . contrasted to the scorching desert that surrounds this place , so are these people . things from all over the world have been rebuilt here , away from their histories , and the people that experience them differently . sometimes , improvements were made . even the sphinx got a nose job . here , what you see is what you get , and there 's no reason to feel like you 're missing anything . this new york means the same to me as it does to everyone else . everything is out of context , and that means context allows for everything . self parking , events center , shark reef . this fabrication of place could be one of the world 's greatest achievements , because no one belongs here , everyone does . as i walked around this morning , i noticed most of the buildings were huge mirrors reflecting the sun back into the desert . but unlike most mirrors , which present you with an outside view of yourself embedded in a place , these mirrors come back empty . john green : it makes me nostalgic for the days when you could see the pixels in online video . ( laughter ) ze is n't just a great public intellectual , he 's also a brilliant community builder , and the community of people that built up around these videos was in many ways a community of learners , so we played ze frank at chess collaboratively , and we beat him . we organized ourselves to take a young man on a road trip across the united states . we turned the earth into a sandwich by having one person hold a piece of bread at one point on the earth , and on the exact opposite point of the earth having another person holding a piece of bread . i realize that these are silly ideas , but they are also 'learny ' ideas , and that was what was so exciting to me , and if you go online , you can find communities like this all over the place . follow the calculus tag on tumblr , and yes , you will see people complaining about calculus , but you 'll also see people re-blogging those complaints , making the argument that calculus is interesting and beautiful , and here 's a way in to thinking about the problem that you find unsolvable . you can go to places like reddit , and find sub-reddits , like 'ask a historian ' , or 'ask science ' , where you can ask people who are in these fields a wide range of questions , from very serious ones to very silly ones . but to me , the most interesting communities of learners that are growing up on the internet right now are on youtube , and admittedly i am biased . but i think in a lot of ways , the youtube page resembles a classroom . look for instance at `` minute physics '' , a guy who 's teaching the world about physics . ( video ) let 's cut to the chase . as of july 4th , 2012 , the higgs boson is the last fundamental piece of the standard model of particle physics to be discovered experimentally . but , you might ask , why was the higgs boson included in the standard model , alongside well-known particles like electrons and photons and quarks , if it had n't been discovered back then in the 1970s ? good question . there are two main reasons . first , just like the electron is an excitation in the electron field , the higgs boson is simply a particle which is an excitation of the everywhere-permeating higgs field . the higgs field in turn plays an integral role in our model for the weak nuclear force . in particular , the higgs field helps explain why it 's so weak . we 'll talk more about this in a later video , but even though weak nuclear theory was confirmed in the 1980s , in the equations , the higgs field is so inextricably jumbled with the weak force , that until now we 've been unable to confirm its actual and independent existence . jg : or here 's a video that i made as part of my show `` crash course '' , talking about world war i : ( video ) the immediate cause was of course the assassination in sarajevo of the austrian archduke franz ferdinand , on june 28 , 1914 , by a bosnian-serb nationalist named gavrilo princip . quick aside : it 's worth noting that the first big war of the twentieth century began with an act of terrorism . so franz ferdinand was n't particularly well-liked by his uncle , the emperor franz joseph - now that is a moustache ! - but even so , the assassination led austria to issue an ultimatum to serbia , whereupon serbia accepted some , but not all , of austria 's demands , leading austria to declare war against serbia . and then russia , due to its alliance with the serbs , mobilized its army . germany , because it had an alliance with austria , told russia to stop mobilizing , which russia failed to do , so then germany mobilized its own army , declared war on russia , cemented an alliance with the ottomans , and then declared war on france , because , you know - france ! ( laughter ) and it 's not just physics and world history that people are choosing to learn through youtube . here 's a video about abstract mathematics . ( video ) so you 're me , and you 're in math class yet again , because they make you go , like , every single day . and you 're learning about , i do n't know , the sums of infinite series . that 's a high school topic , right ? which is odd , because it 's a cool topic , but they somehow manage to ruin it anyway . so i guess that 's why they allow infinite series in the curriculum . so , in a quite understandable need for distraction , you 're doodling and thinking more about what the plural of `` series '' should be than about the topic at hand . `` serieses , '' `` seriese , '' `` seriesen , '' and `` serii ? '' or is it that the singular should be changed ? one `` serie , '' or `` serus , '' or `` serum ? '' just like the singular of `` sheep '' should be `` shoop . '' but the whole concept of things like 1/2 + 1/4 + 1/8 + 1/16 and so on , approaching one , is useful if , say , you want to draw a line of elephants each holding the tail of the next one : normal elephant , young elephant , baby elephant , dog-sized elephant , puppy-sized elephant ... all the way down to mr. tusks and beyond . which is at least a tiny bit awesome , because you can get an infinite number of elephants in a line and still have it fit across a single notebook page . jg : and lastly , here 's destin , from `` smarter every day '' , talking about the conservation of angular momentum and , since it 's youtube , cats : ( video ) hey , it 's me , destin . welcome back to `` smarter every day '' . so you 've probably observed that cats almost always land on their feet . today 's question is why ? like most simple questions , there 's a very complex answer . for instance , let me reword this question : how does a cat go from feet up to feet down in a falling reference frame without violating the conservation of angular momentum ? jg : so , here 's something all of these videos have in common : they all have more than half a million views on youtube . and those are people watching not in classrooms , but because they are part of the communities of learning that are being set up by these channels . and i said earlier that youtube is like a classroom to me , and in many ways it is , because here is the instructor - it 's like the old-fashioned classroom - here 's the instructor , and then beneath the instructor is the students , and they 're all having a conversation . and i know that youtube comments have a very bad reputation in the world of the internet , but in fact , if you go on comments for these channels , what you 'll find is people engaging the subject matter , asking difficult , complicated questions that are about the subject matter , and then other people answering those questions . and because the youtube page is set up so that the place in which i 'm talking to you is on the exact same page as your comments , you are participating in a live and real and active way in the conversation . and because i 'm in comments usually , i get to participate with you , and you find this whether it 's world history , or mathematics , or science , or whatever it is . you also see young people using the tools and the sort of genres of the internet in order to create places for intellectual engagement instead of the ironic detachment that maybe most of us associate with memes and other internet conventions , you know `` got bored - invented calculus '' , or here 's honey boo boo criticizing industrial capitalism [ `` liberal capitalism is not at all the good of humanity . quite the contrary ; it is the vehicle of savage destructive nihilism '' ] . in case you ca n't see what she says ... yeah . i really believe that these spaces , these communities have become , for a new generation of learners , the kind of communities , the kind of cartographic communities that i had when i was in high school , and then again when i was in college . and as an adult , re-finding these communities has re-introduced me to a community of learners , and has encouraged me to continue to be a learner even in my adulthood , so that i no longer feel like learning is something reserved for the young . vi hart and `` minute physics '' introduced me to all kinds of things that i did n't know before . and i know that we all hearken back to the days of the parisian salon in the enlightenment , or to the algonquin round table , and wish , `` oh , i wish i could have been a part of that , i wish i could have laughed at dorothy parker 's jokes '' . but i 'm here to tell you that these places exist , they still exist . they exist in corners of the internet , where old men fear to tread . ( laughter ) and i truly , truly believe that when we invented agloe , new york , in the 1960s , when we made agloe real , we were just getting started . thank you . ( applause )
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and because i 'm in comments usually , i get to participate with you , and you find this whether it 's world history , or mathematics , or science , or whatever it is . you also see young people using the tools and the sort of genres of the internet in order to create places for intellectual engagement instead of the ironic detachment that maybe most of us associate with memes and other internet conventions , you know `` got bored - invented calculus '' , or here 's honey boo boo criticizing industrial capitalism [ `` liberal capitalism is not at all the good of humanity . quite the contrary ; it is the vehicle of savage destructive nihilism '' ] .
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john green stated that `` young people [ are ] using the tools and the sort of genres of the internet in order to create places for intellectual engagement . '' what are some ways that you have engaged with a learning community on the internet ?
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in the 16th century , the mathematician robert recorde wrote a book called `` the whetstone of witte '' to teach english students algebra . but he was getting tired of writing the words `` is equal to '' over and over . his solution ? he replaced those words with two parallel horizontal line segments because the way he saw it , no two things can be more equal . could he have used four line segments instead of two ? of course . could he have used vertical line segments ? in fact , some people did . there 's no reason why the equals sign had to look the way it does today . at some point , it just caught on , sort of like a meme . more and more mathematicians began to use it , and eventually , it became a standard symbol for equality . math is full of symbols . lines , dots , arrows , english letters , greek letters , superscripts , subscripts . it can look like an illegible jumble . it 's normal to find this wealth of symbols a little intimidating and to wonder where they all came from . sometimes , as recorde himself noted about his equals sign , there 's an apt conformity between the symbol and what it represents . another example of that is the plus sign for addition , which originated from a condensing of the latin word et meaning and . sometimes , however , the choice of symbol is more arbitrary , such as when a mathematician named christian kramp introduced the exclamation mark for factorials just because he needed a shorthand for expressions like this . in fact , all of these symbols were invented or adopted by mathematicians who wanted to avoid repeating themselves or having to use a lot of words to write out mathematical ideas . many of the symbols used in mathematics are letters , usually from the latin alphabet or greek . characters are often found representing quantities that are unknown , and the relationships between variables . they also stand in for specific numbers that show up frequently but would be cumbersome or impossible to fully write out in decimal form . sets of numbers and whole equations can be represented with letters , too . other symbols are used to represent operations . some of these are especially valuable as shorthand because they condense repeated operations into a single expression . the repeated addition of the same number is abbreviated with a multiplication sign so it does n't take up more space than it has to . a number multiplied by itself is indicated with an exponent that tells you how many times to repeat the operation . and a long string of sequential terms added together is collapsed into a capital sigma . these symbols shorten lengthy calculations to smaller terms that are much easier to manipulate . symbols can also provide succinct instructions about how to perform calculations . consider the following set of operations on a number . take some number that you 're thinking of , multiply it by two , subtract one from the result , multiply the result of that by itself , divide the result of that by three , and then add one to get the final output . without our symbols and conventions , we 'd be faced with this block of text . with them , we have a compact , elegant expression . sometimes , as with equals , these symbols communicate meaning through form . many , however , are arbitrary . understanding them is a matter of memorizing what they mean and applying them in different contexts until they stick , as with any language . if we were to encounter an alien civilization , they 'd probably have a totally different set of symbols . but if they think anything like us , they 'd probably have symbols . and their symbols may even correspond directly to ours . they 'd have their own multiplication sign , symbol for pi , and , of course , equals .
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sets of numbers and whole equations can be represented with letters , too . other symbols are used to represent operations . some of these are especially valuable as shorthand because they condense repeated operations into a single expression .
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what are some sources of new mathematical symbols that have been widely used ?
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how and when did our universe begin ? how did it get to look like this ? how will it end ? humans have been discussing these questions for as long as they 've been around without ever reaching much agreement . today , cosmologists are working hard to find the answers . but how can anyone hope to find concrete answers to such profound questions ? and how is it possible to explore and study something as huge as the universe , most of which we 'll never be able to reach ? the answer is light . and although light from distant parts of the universe can take billions of years to reach us , it carries six unique messages that , when put together , can disclose an amazing amount of information to astronomers who know how to look for it . just as sunlight can be split up into the familiar rainbow , splitting the light from distant objects exposes different patterns of colors depending on its source . this distinctive light barcode can reveal not only an object 's composition , but also the temperature and pressure of its constituent parts . there 's even more we can discover from light . if you 've ever stood on a train platform , you might have noticed that the train sounds different depending on its direction with the pitch ascending when it approaches you and descending when it speeds away . but this is n't because the train conductor is practicing for a second career . rather , it 's because of something called the doppler effect where sound waves generated by an approaching object are compressed , while those from a receding object are stretched . but what has this to do with astronomy ? sound does not travel through a vacuum . in space , no one can you hear you scream ! but the same doppler effect applies to light whose source is moving at exceptional speed . if it 's moving towards us , the shorter wavelength will make the light appear to be bluer . while light from a source that 's moving away will have a longer wavelength , shifting towards red . so by analyzing the color pattern in the doppler shift of the light from any object observed with a telescope , we can learn what it 's made of , how hot it is and how much pressure it 's under , as well as whether it 's moving , in what direction and how fast . and these six measurements , like six points of light , reveal the history of the universe . the first person to study the light from distant galaxies was edwin hubble , and the light he observed was redshifted . the distant galaxies were all moving away from us , and the further away the were , the faster they were receding . hubble had discovered our universe is expanding , providing the first evidence for the big bang theory . along with the idea that the visible universe has been constantly expanding from a densely packed single point , one of this theory 's most important predictions is that the early universe consisted of just two gases : hydrogen and helium , in a ratio of three to one . and this prediction can also be tested with light . if we observe the light from a remote , quiet region of the universe and split it , we do indeed find the signatures of the two gases in just those proportions . another triumph for the big bang . however , many puzzles remain . although we know the visible universe is expanding , gravity should be applying the brakes . but recent measurements of light from distant dying stars show us that they 're farther away than predicted . so the expansion of the universe is actually accelerating . something appears to be pushing it , and many scientists believe that something is dark energy , making up over 2/3 of the universe and slowly tearing it apart . our knowledge of the behavior of matter and the precision of our instruments means that simply observing distant stars can tell us more about the universe than we ever thought possible . but there are other mysteries , like the nature of dark energy upon which we have yet to shed light .
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and these six measurements , like six points of light , reveal the history of the universe . the first person to study the light from distant galaxies was edwin hubble , and the light he observed was redshifted . the distant galaxies were all moving away from us , and the further away the were , the faster they were receding .
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what did edwin hubble notice about the light from distant galaxies ?
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stretched across a tree-peppered expanse in southern africa lies the magnificent ruins of great zimbabwe , a medieval stone city of astounding wealth and prestige . located in the present-day country of zimbabwe , it 's the sight of the largest known settlement ruins in sub-saharan africa , second on the continent only to the pyramids of egypt . but the history of this city is shrouded in controversy , defined by decades of dispute about who built it and why . its name comes from the shona word madzimbabwe , meaning big house of stone for its unscalable stone walls that reach heights of nearly ten meters and run for a length of about 250 meters . for its grandeur and historical significance , it was named a unesco world heritage site in 1986 . back in the 14th and 15th centuries , it was a thriving city . spread across nearly eight square-kilometers , great zimbabwe was defined by three main areas : the hill complex , where the king lived ; the great enclosure , reserved for members of the royal family ; and the valley complex , where regular citizens lived . rulers were both powerful economic and religious leaders for the region . at its highest point , the city had a bustling urban population of 18,000 people and was one of the major african trade centers at the time . what enabled this growth was great zimbabwe 's influential role in an intercontinental trade network . connected to several key city-states along the east african swahili coast , it was part of the larger indian ocean trade routes . the city generated its riches by controlling the sources and trade of the most prized items : gold , ivory , and copper . with this mercantile power , it was able to extend its sphere of influence across continents , fostering a strong arab and indian trader presence throughout its zenith . archaeologists have since pieced together the details of this history through artifacts discovered on site . there were pottery shards and glassworks from asia , as well as coins minted in the coastal trading city of kilwa kisiwani over 1,500 miles away . they also found soapstone bird figures , which are thought to represent each of the city 's rulers , and young calf bones , only unearthed near the royal residence , show how the diet of the elite differed from the general population . these clues have also led to theories about the city 's decline . by the mid-15th century , the buildings at great zimbabwe were almost all that remained . archaeological evidence points to overcrowding and sanitation issues as the cause , compounded by soil depletion triggered by overuse . eventually , as crops withered and conditions in the city worsened , the population of great zimbabwe is thought to have dispersed and formed the nearby mutapa and torwa states . centuries later , a new phase of great zimbabwe 's influence began to play out in the political realm as people debated who had built the famous city of stone . during the european colonization of africa , racist colonial officials claimed the ruins could n't be of african origin . so , without a detailed written record on hand , they instead relied on myths to explain the magnificence of great zimbabwe . some claimed it proved the bible story of the queen of sheba who lived in a city of riches . others argued it was built by the ancient greeks . then , in the early 20th century after extensive excavation at the site , the archaeologist david randall-maciver presented clear evidence that great zimbabwe was built by indigenous peoples . yet , at the time , the country 's white minority colonial government sought to discredit this theory because it challenged the legitimacy of their rule . in fact , the government actively encouraged historians to produce accounts that disputed the city 's african origins . over time , however , an overwhelming body of evidence mounted , identifying great zimbabwe as an african city built by africans . during the 1960s and 70s , great zimbabwe became an important symbol for the african nationalist movement that was spreading across the continent . today , the ruins at great zimbabwe , alluded to on the zimbabwean flag by a soapstone bird , still stand as a source of national pride and cultural value .
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yet , at the time , the country 's white minority colonial government sought to discredit this theory because it challenged the legitimacy of their rule . in fact , the government actively encouraged historians to produce accounts that disputed the city 's african origins . over time , however , an overwhelming body of evidence mounted , identifying great zimbabwe as an african city built by africans . during the 1960s and 70s , great zimbabwe became an important symbol for the african nationalist movement that was spreading across the continent .
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how did the colonial government try to hide the fact that local africans built great zimbabwe ?
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a lone priestess walks towards an underground chamber . people line the streets to watch as she proclaims her innocence . it does n't matter . she 's already been judged and found guilty . the sentence ? live burial . the underground chamber contains a portion of bread , water , milk , and oil . she will have a lamp , a bed , and a blanket , but she wo n't emerge alive . at the threshold , the priestess pauses , claims her innocence one last time , then enters the chamber never to be seen again by the roman people . the priestess is one of rome 's six vestal virgins , each carefully selected as children from rome 's most aristocratic families . but now with her death , there are only five , and a new priestess must be chosen . the six-year-old licinia witnessed the spectacle , never suspecting that a few days later , she 'd be chosen as the next vestal virgin . her age , her patrician family lineage , and her apparent good health makes her the best candidate to serve the goddess vesta in the eyes of the romans . her parents are proud that their daughter 's been chosen . licinia is afraid , but she has no choice in the matter . she must serve the goddess for at least the next 30 years . for the first ten years of licinia 's service , she 's considered in training , learning how to be a vestal virgin . her most important duty is keeping vigil over the flame of vesta , the virgin goddess of the hearth . vesta does n't have a statue like other roman gods and goddesses . instead , she 's represented by the flame which burns day and night in her temple located next to the forum in the center of the city . like all vestal priestesses , licinia spends part of each day on shift , watching and tending to the flame . the flame represents two things . the first is the continuation of rome as a power in the world . the romans believed that if the flame goes out , the city 's in danger . the flame also symbolizes the continuing virginity of vesta 's priestesses . for the romans , a vestal 's virginity signaled not only her castitas , or modest spirit and body , but also her ritual purity . so licinia knows she must never let the flame go out . her life , the lives of her fellow vestals , and the safety of rome itself depends upon it . licinia learns to collect water each day from a nearby fountain to cleanse the temple . she learns the fasti , the calendar of sacred rituals and she watches while the senior priestesses conduct sacrifices . by the time licinia completes her training , she 's 16 years old . licinia understands that the way she must act is a reflection of the goddess she serves . when it 's her turn to collect the water , she keeps her eyes lowered to the ground . when she performs sacrifices , she focuses intently on the task . licinia directs her energy towards being the best priestess she can be . she 's worried that someday the state will claim her life for its own purposes to protect itself from danger . licinia could be accused of incestum , meaning unchastity , at any time and be sacrificed whether she 's innocent or guilty . licinia fully understands now why her predecessor was buried alive . ten years ago , the flame of vesta went out . the priestesses knew that they could n't keep it a secret . the future of rome depended upon it . they went to the chief priest and he opened an investigation to discover why the flame had failed . someone came forward and claimed that one of the vestals was no longer a virgin . that was the beginning of the end . the accused protested her innocence , but it was n't enough . she was tried and found guilty . that vestal 's death was meant to protect the city , but licinia weeps for what has been lost and for what she knows now . her own path was paved by the death of another , and her life could be taken just as easily for something as simple as a flame going out .
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at the threshold , the priestess pauses , claims her innocence one last time , then enters the chamber never to be seen again by the roman people . the priestess is one of rome 's six vestal virgins , each carefully selected as children from rome 's most aristocratic families . but now with her death , there are only five , and a new priestess must be chosen .
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how many vestal virgins served at the same time ?
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in 1898 , marie and pierre curie discovered radium . claimed to have restorative properties , radium was added to toothpaste , medicine , water , and food . a glowing , luminous green , it was also used in beauty products and jewelry . it was n't until the mid-20th century we realized that radium 's harmful effects as a radioactive element outweighed its visual benefits . unfortunately , radium is n't the only pigment that historically seemed harmless or useful but turned out to be deadly . that lamentable distinction includes a trio of colors and pigments that we 've long used to decorate ourselves and the things we make : white , green , and orange . our story begins with white . as far back as the 4th century bce , the ancient greeks treated lead to make the brilliant white pigment we know today . the problem ? in humans , lead is directly absorbed into the body and distributed to the blood , soft tissues , and mineralized tissues . once in the nervous system , lead mimics and disrupts the normal functions of calcium , causing damages ranging from learning disabilities to high blood pressure . yet the practice of using this toxic pigment continued across time and cultures . lead white was the only practical choice for white oil or tempera paint until the 19th century . to make their paint , artists would grind a block of lead into powder , exposing highly toxic dust particles . the pigment 's liberal use resulted in what was known as painter 's colic , or what we 'd now call lead poisoning . artists who worked with lead complained of palseys , melancholy , coughing , enlarged retinas , and even blindness . but lead white 's density , opacity , and warm tone were irresistible to artists like vermeer , and later , the impressionists . its glow could n't be matched , and the pigment continued to be widely used until it was banned in the 1970s . as bad as all that sounds , white 's dangerous effects pale in comparison to another , more wide-spread pigment , green . two synthetic greens called scheele 's green and paris green were first introduced in the 18th century . they were far more vibrant and flashy than the relatively dull greens made from natural pigments , so they quickly became popular choices for paint as well as dye for textiles , wallpaper , soaps , cake decorations , toys , candy , and clothing . these green pigments were made from a compound called cupric hydrogen arsenic . in humans , exposure to arsenic can damage the way cells communicate and function . and high levels of arsenic have been directly linked to cancer and heart disease . as a result , 18th century fabric factory workers were often poisoned , and women in green dresses reportedly collapsed from exposure to arsenic on their skin . bed bugs were rumored not to live in green rooms , and it 's even been speculated that napoleon died from slow arsenic poisoning from sleeping in his green wallpapered bedroom . the intense toxicity of these green stayed under wraps until the arsenic recipe was published in 1822 . and a century later , it was repurposed as an insecticide . synthetic green was probably the most dangerous color in widespread use , but at least it did n't share radium 's property of radioactivity . another color did , though - orange . before world war ii , it was common for manufacturers of ceramic dinnerware to use uranium oxide in colored glazes . the compound produced brilliant reds and oranges , which were appealing attributes , if not for the radiation they emitted . of course , radiation was something we were unaware of until the late 1800s , let alone the associated cancer risks , which we discovered much later . during world war ii , the u.s. government confiscated all uranium for use in bomb development . however , the atomic energy commission relaxed these restrictions in 1959 , and depleted uranium returned to ceramics and glass factory floors . orange dishes made during the next decade may still have some hazardous qualities on their surfaces to this day . most notably , vintage fiestaware reads positive for radioactivity . and while the levels are low enough that they do n't officially pose a health risk if they 're on a shelf , the u.s. epa warns against eating food off of them . though we still occasionally run into issues with synthetic food dyes , our scientific understanding has helped us prune hazardous colors out of our lives .
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yet the practice of using this toxic pigment continued across time and cultures . lead white was the only practical choice for white oil or tempera paint until the 19th century . to make their paint , artists would grind a block of lead into powder , exposing highly toxic dust particles .
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lead , while helping to produce a bright white pigment , can be dangerous to humans . how ?
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sometime in the early 1750s , a 22-year-old man named benjamin banneker sat industriously carving cogs and gears out of wood . he pieced the parts together to create the complex inner working of a striking clock that would , hopefully , chime every hour . all he had to help him was a pocket watch for inspiration and his own calculations . and yet , his careful engineering worked . striking clocks had already been around for hundreds of years , but banneker 's may have been the first created in america , and it drew fascinated visitors from across the country . in a show of his brilliance , the clock continued to chime for the rest of banneker 's life . born in 1731 to freed slaves on a farm in baltimore , maryland , from his earliest days , the young banneker was obsessed with math and science . and his appetite for knowledge only grew as he taught himself astronomy , mathematics , engineering , and the study of the natural world . as an adult , he used astronomy to accurately predict lunar and solar events , like the solar eclipse of 1789 , and even applied his mathematical skills to land use planning . these talents caught the eye of a local baltimore businessman , andrew ellicott , who was also the surveyor general of the united states . recognizing banneker 's skills in 1791 , ellicott appointed him as an assistant to work on a prestigious new project , planning the layout of the nation 's capitol . meanwhile , banneker turned his brilliant mind to farming . he used his scientific expertise to pioneer new agricultural methods on his family 's tobacco farm . his fascination with the natural world also led to a study on the plague life cycle of locusts . then in 1792 , banneker began publishing almanacs . these provided detailed annual information on moon and sun cycles , weather forecasts , and planting and tidal time tables . banneker sent a handwritten copy of his first almanac to virginia 's secretary of state thomas jefferson . this was a decade before jefferson became president . banneker included a letter imploring jefferson to `` embrace every opportunity to eradicate that train of absurd and false ideas and opinions '' that caused prejudice against black people . jefferson read the almanac and wrote back in praise of banneker 's work . banneker 's correspondence with the future president is now considered to be one of the first documented examples of a civil rights protest letter in america . for the rest of his life , he fought for this cause , sharing his opposition to slavery through his writing . in 1806 at the age of 75 , banneker died after a lifetime of study and activism . on the day of his funeral , his house mysteriously burned down , and the majority of his life 's work , including his striking clock , was destroyed . but still , his legacy lives on .
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sometime in the early 1750s , a 22-year-old man named benjamin banneker sat industriously carving cogs and gears out of wood . he pieced the parts together to create the complex inner working of a striking clock that would , hopefully , chime every hour . all he had to help him was a pocket watch for inspiration and his own calculations .
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benjamin banneker ’ s striking clock chimed every _________ .
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translator : tom carter reviewer : bedirhan cinar we take a breath every few seconds . our life depends upon inhaling oxygen , but we never think about how we breathe . it just seems to happen automatically . how can something that seems so simple be the key to keeping us alive ? breathing starts with the environment around us . the air we breathe in , or inspire , has a mixture of gases including nitrogen , carbon dioxide and oxygen , which is the most important for our survival . it enters our body through the nose and mouth , moves down into the pharynx , trachea and bronchial tubes , and ultimately reaches the alveoli air sacs in the lungs . the alveoli use pressure to move oxygen and nutrients into the blood . the diaphragm and intercostal muscles are a pumping system that facilitates this air exchange . how you breathe affects your energy level , especially when you are under physical or emotional stress . think back to the last difficult test you had to take . it 's likely that as you became more nervous , the tension in your body increased , and your breathing quickly sped up . the shallower our breath , the less oxygen that reaches our brain , and the harder it is to focus . what 's our response to physical stress , like a fast-paced game of field hockey after school ? as we exert pressure on our bodies , the muscles require a great deal of energy and demand additional oxygen . our panting breath starts to kick in , which creates pressure to draw in more air and oxygen to the body , and regulates body temperature by allowing it to cool down naturally . these are n't the only times our breathing is affected or altered . think about the last time you got angry or emotional . anger creates a metabolic reaction in the body , which stresses it out and heats up our internal temperature . have you ever seen anyone lose their cool ? ultimately , if we 're breathing under stress over long periods of time , there are consequences . when the cells of a body are n't getting the oxygen they need , the nutrients available to the body decrease and toxins build up in the blood . it is thought that a hypoxic , or oxygen-poor environment , can increase cancerous cells . the good news is that we can control our breath much more than we realize . this means we can increase both the quality and quantity of the breath . the science of breathing has been around for thousands of years , from ancient yogis in india to respiratory therapists working with patients today . both would tell you that there are specific techniques that will help you improve your breathing . breathing is all about moving air from a higher-pressure to a lower-pressure environment . more breath means more oxygen , and ultimately a greater amount of nutrients that 's available for our cells and blood . we naturally do this when we let out a big sigh . changing the air pressure going into the lungs is one of the main ways to alter breathing . our body automatically does this when we cough , sneeze , or have the hiccups . here 's a simple experiment . close off your right nostril with your right thumb . breathe in and out just through the left nostril . notice how much harder it is to get the breath in . you have to focus your attention , and use your diaphragm and muscles much more than normal . by decreasing the surface area of the airways , you 're increasing the pressure of oxygen moving from the alveoli to the blood . yogis often practice alternate nostril breathing to slow down the breath , increase oxygen , and activate the body 's parasympathetic nervous system , which deals with the body 's operations when it 's at rest . let 's try another exercise . visualize the way a dog pants when it breathes . now try doing the same type of panting , first with your tongue out , then with your mouth closed . you will find yourself using your stomach muscles to push the air out as you exhale . place your hand under your nose , and you 'll feel the strength of the breath coming out . breathing this way is hard because it requires an active movement of our diaphragm and intercostal muscles . our body temperature changes quickly during this exercise from the amount of pressure we are exerting on our breath . it 's no surprise that you 'll find dogs doing this breath often to cool down on a hot day . when we sleep at night , the medulla center of the brain makes sure that we keep breathing . lucky for us we do n't have to think about it . during the day , our breath is much more vulnerable , especially under stressful or difficult situations . that 's why it 's helpful to pay attention to your breathing . if you can monitor and change your breath , you can improve both the quality and quantity of oxygen that enters your body . this lowers stress , increases energy , and strengthens your immune system . so the next time someone tells you to relax and take a deep breath , you 'll know exactly why .
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have you ever seen anyone lose their cool ? ultimately , if we 're breathing under stress over long periods of time , there are consequences . when the cells of a body are n't getting the oxygen they need , the nutrients available to the body decrease and toxins build up in the blood .
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what is yoga , and why is it so popular for people who are trying to lower their stress levels and get healthy ? how do the exercises used in yoga affect both the body and mind at the same time ? why do people feel a sense of calmness when they practice breathing techniques and yoga ?
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in 1956 , during a diplomatic reception in moscow , soviet leader nikita khrushchev told western bloc ambassadors , `` my vas pokhoronim ! '' his interpreter rendered that into english as , `` we will bury you ! '' this statement sent shockwaves through the western world , heightening the tension between the soviet union and the us who were in the thick of the cold war . some believe this incident alone set east/west relations back a decade . as it turns out , khrushchev 's remark was translated a bit too literally . given the context , his words should have been rendered as , `` we will live to see you buried , '' meaning that communism would outlast capitalism , a less threatening comment . though the intended meaning was eventually clarified , the initial impact of khrushchev 's apparent words put the world on a path that could have led to nuclear armageddon . so now , given the complexities of language and cultural exchange , how does this sort of thing not happen all the time ? much of the answer lies with the skill and training of interpreters to overcome language barriers . for most of history , interpretation was mainly done consecutively , with speakers and interpreters making pauses to allow each other to speak . but after the advent of radio technology , a new simultaneous interpretations system was developed in the wake of world war ii . in the simultaneous mode interpreters instantaneously translate a speaker 's words into a microphone while he speaks . without pauses , those in the audience can choose the language in which they want to follow . on the surface , it all looks seamless , but behind the scenes , human interpreters work incessantly to ensure every idea gets across as intended . and that is no easy task . it takes about two years of training for already fluent bilingual professionals to expand their vocabulary and master the skills necessary to become a conference interpreter . to get used to the unnatural task of speaking while they listen , students shadow speakers and repeat their every word exactly as heard in the same language . in time , they begin to paraphrase what is said , making stylistic adjustments as they go . at some point , a second language is introduced . practicing in this way creates new neural pathways in the interpreter 's brain , and the constant effort of reformulation gradually becomes second nature . over time and through much hard work , the interpreter masters a vast array of tricks to keep up with speed , deal with challenging terminology , and handle a multitude of foreign accents . they may resort to acronyms to shorten long names , choose generic terms over specific , or refer to slides and other visual aides . they can even leave a term in the original language , while they search for the most accurate equivalent . interpreters are also skilled at keeping aplomb in the face of chaos . remember , they have no control over who is going to say what , or how articulate the speaker will sound . a curveball can be thrown at any time . also , they often perform to thousands of people and in very intimidating settings , like the un general assembly . to keep their emotions in check , they carefully prepare for an assignment , building glossaries in advance , reading voraciously about the subject matter , and reviewing previous talks on the topic . finally , interpreters work in pairs . while one colleague is busy translating incoming speeches in real time , the other gives support by locating documents , looking up words , and tracking down pertinent information . because simultaneous interpretation requires intense concentration , every 30 minutes , the pair switches roles . success is heavily dependent on skillful collaboration . language is complex , and when abstract or nuanced concepts get lost in translation , the consequences may be catastrophic . as margaret atwood famously noted , `` war is what happens when language fails . '' conference interpreters of all people are aware of that and work diligently behind the scenes to make sure it never does .
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in 1956 , during a diplomatic reception in moscow , soviet leader nikita khrushchev told western bloc ambassadors , `` my vas pokhoronim ! '' his interpreter rendered that into english as , `` we will bury you ! ''
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which of the assertions below is false ?
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they say that if walls could talk , each building would have a story to tell , but few would tell so many fascinating stories in so many different voices as the hagia sophia , or holy wisdom . perched at the crossroads of continents and cultures , it has seen massive changes from the name of the city where it stands , to its own structure and purpose . and today , the elements from each era stand ready to tell their tales to any visitor who will listen . even before you arrive at the hagia sophia , the ancient fortifications hint at the strategic importance of the surrounding city , founded as byzantium by greek colonists in 657 bce . and successfully renamed as augusta antonia , new rome and constantinople as it was conquered , reconquered , destroyed and rebuilt by various greek , persian and roman rulers over the following centuries . and it was within these walls that the first megale ekklesia , or great church , was built in the fourth century . though it was soon burned to the ground in riots , it established the location for the region 's main religious structure for centuries to come . near the entrance , the marble stones with reliefs are the last reminders of the second church . built in 415 ce , it was destroyed during the nika riots of 532 when angry crowds at a chariot race nearly overthrew the emperor , justinian the first . having barely managed to retain power , he resolved to rebuild the church on a grander scale , and five years later , the edifice you see before you was completed . as you step inside , the stones of the foundation and walls murmur tales from their homelands of egypt and syria , while columns taken from the temple of artemis recall a more ancient past . runic inscriptions carved by the vikings of the emperor 's elite guard carry the lore of distant northern lands . but your attention is caught by the grand dome , representing the heavens . reaching over 50 meters high and over 30 meters in diameter and ringed by windows around its base , the golden dome appears suspended from heaven , light reflecting through its interior . beneath its grandiose symbolism , the sturdy reinforcing corinthian columns , brought from lebanon after the original dome was partially destroyed by an earthquake in 558 ce , quietly remind you of its fragility and the engineering skills such a marvel requires . if a picture is worth a thousand words , the mosaics from the next several centuries have the most to say not only about their biblical themes , but also the byzantine emperors who commissioned them , often depicted along with christ . but beneath their loud and clear voices , one hears the haunting echoes of the damaged and missing mosaics and icons , desecrated and looted during the latin occupation in the fourth crusade . within the floor , the tomb inscription of enrico dandolo , the venetian ruler who commanded the campaign , is a stark reminder of those 57 years that hagia sophia spent as a roman catholic church before returning to its orthodox roots upon the byzantine reconquest . but it would not remain a church for long . weakened by the crusades , constantinople fell to the ottomans in 1453 and would be known as istanbul thereafter . after allowing his soldiers three days of pillage , sultan mehmed the second entered the building . though heavily damaged , its grandeur was not lost on the young sultan who immediately rededicated it to allah , proclaiming that it would be the new imperial mosque . the four minarets built over the next century are the most obvious sign of this era , serving as architectural supports in addition to their religious purpose . but there are many others . ornate candle holders relate suleiman 's conquest of hungary , while giant caligraphy discs hung from the ceiling remind visitors for the first four caliphs who followed muhammad . though the building you see today still looks like a mosque , it is now a museum , a decision made in 1935 by kemal ataturk , the modernizing first president of turkey following the ottoman empire 's collapse . it was this secularization that allowed for removal of the carpets hiding the marble floor decorations and the plaster covering the christian mosaics . ongoing restoration work has allowed the multiplicity of voices in hagia sophia 's long history to be heard again after centuries of silence . but conflict remains . hidden mosaics cry out from beneath islamic calligraphy , valuable pieces of history that can not be uncovered without destroying others . meanwhile , calls sound from both muslim and christian communities to return the building to its former religious purposes . the story of the divine wisdom may be far from over , but one can only hope that the many voices residing there will be able to tell their part for years to come .
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it was this secularization that allowed for removal of the carpets hiding the marble floor decorations and the plaster covering the christian mosaics . ongoing restoration work has allowed the multiplicity of voices in hagia sophia 's long history to be heard again after centuries of silence . but conflict remains .
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each of the calligraphic disks hung inside of the hagia sophia represent ________ .
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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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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 .
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we ’ ve seen that while the earth and the sun are composed of the same elements , the proportion that a given element makes up of the earth is generally strikingly different from the proportion of the sun it constitutes . what about other planets ? are their chemical compositions more like the earth , more like the sun , or something entirely different ?
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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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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 .
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which of the following best describes how theories relate to laws ?
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maybe you 've recently seen the phrase `` gluten-free '' on food packaging , or take-out menus , shampoo bottles , apartment listings , the tag of your shirt , on a hammer , as a lower back tattoo , or in your friend 's resume . next time someone starts telling you about their newfound freedom from gluten , here are some questions you can ask , and the well-informed answers that your friend , being a reasonable individual making educated dietary choices , and by no means just following the latest diet craze , will tell you . what is gluten ? gluten is an insoluble protein composite made up of two proteins named gliadin and glutenin . where might you encounter gluten ? gluten is found in certain grains , particularly wheat , rye and barley . what has gluten been doing for the previous entirety of human history , and why do you suddenly care about it ? gluten is responsible for the elastic consistency of dough and the chewiness of foods made from wheat flour , like bread and pasta . for some people , these foods cause problems , namely wheat allergy , celiac disease , and non-celiac gluten sensitivity . wheat allergy is an uncommon condition that occurs when a person 's immune system mounts an allergic response to wheat proteins , leading to mild problems , and in rare cases , a potential dangerous reaction called anaphylaxis . celiac disease is an inherited disease , in which eating foods with gluten leads to inflammation and damage of the lining of the small intestine . this impairs intestinal function , leading to problems like belly pain , bloating , gas , diarrhea , weight loss , skin rash , bone problems like osteoporosis , iron deficiency , small stature , infertility , fatigue and depression . untreated , celiac disease increases the risk of developing certain types of cancer . celiac disease is present in one in every 100 to 200 persons in the u.s . when blood tests suggest the possibility of celiac , the diagnosis is confirmed with a biopsy . the most effective treatment is a gluten-free diet , which helps heal intestinal damage and improve symptoms . some people do n't have celiac disease or a wheat allergy , but still experience symptoms when they eat foods with gluten . these people have non-celiac gluten sensitivity . they experience painful gut symptoms and suffer from fatigue , brain fog , joint pain or skin rash . a gluten-free diet typically helps with these symptoms . so how many people actually have this gluten sensitivity you speak of ? gluten sensitivity 's occurrence in the general population is unclear , but likely much more common than wheat allergy or celiac disease . diagnosis is based on the development of symptoms , the absence of wheat allergy and celiac disease , and subsequent improvement on a gluten-free diet . there 's no reliable blood or tissue test , partly because gluten sensitivity is n't a single disease , and has a number of different possible causes . for example , it may be the case that gluten can activate the immune system in the small intestine , or cause it to become leaky . but sometimes , people claiming gluten sensitivity are actually sensitive not to wheat proteins , but sugars found in wheat and other foods , called fructans . the human intestine ca n't break down or absorb fructans , so they make their way to the large intestine or colon , where they 're fermented by bacteria , producing short-chain fatty acids and gases . this leads to unpleasant symptoms in some people with bowel problems . another possible explanation behind gluten sensitivity is the nocebo effect . this occurs when a person believes something will cause problems , and because of that belief , it does . it 's the opposite of the more well-known and much more fortuitous placebo effect . given how much bad press gluten is getting in the media , the nocebo response may play a role for some people who think they 're sensitive to gluten . for all these reasons , it 's clear that the problems people develop when they eat wheat and other grains are n't exclusively due to gluten . so a better name than non-celiac gluten sensitivty might be wheat intolerance .
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another possible explanation behind gluten sensitivity is the nocebo effect . this occurs when a person believes something will cause problems , and because of that belief , it does . it 's the opposite of the more well-known and much more fortuitous placebo effect .
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when a person believes something will cause problems and because of that belief , it does , it is called :
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so you see a few cubes sitting in an art gallery , and you think to yourself , `` this is the greatest hoax that anyone has ever pulled off . '' you immediately walk away , discouraged by the wide gulf between what you hope for when you walk into a museum and what they 've presented to you . how did we get here ? how could these cubes that the artist did n't even make with their own hands be important ? this is the case for minimalism . first off , we 're not talking about minimalism as a general sensibility or the life-changing magic of tidying up . we 're talking about the art of a particular moment in time . namely , the 1960s , when all of a sudden , there was a lot of geometric , abstract art . some of it was painting by artists like frank stella and ellsworth kelly , but most of it was sculpture by artists like donald judd , carl andre , dan flavin , anne truitt , robert morris , tony smith , ronald bladen , and sol lewitt . art critics called it abc art , object art , primary structures , and cool art , but the term minimalism prevailed . these artists never called their art minimalist , by the way , nor did they like the term , or the implication that the work was so reductive that it was minimally art . but minimalism was a rejection of what came before . specifically , abstract expressionism , which dominated the art market in the 1950s . these new artists wanted to remove expression completely , remove emotion , empty the work of idiosyncratic gesture , make it resistant to biographical reading . their hard-edged , basic shapes and forms avoided allusion , metaphor , and overt symbolism . the forms were often repeated , one thing after another in regular , non-hierarchical arrangements , rejecting compositional balancing . no artist hemming and hawing over the canvas here . the objects were impersonal , many of them machine-made , fabricated from new and industrial materials . sometimes this entailed ready-made units , like andre 's bricks , or flavin 's fluorescent tubes . they did n't want you to ooh and ah , or admire the handling of paint . as lewitt once said , `` it is best that the basic unit `` be deliberately uninteresting . '' robert morris wrote that he could hear a resounding no at the time . `` no to transcendence and spiritual values , `` heroic scale , anguished decisions , `` historicizing narrative , valuable artifact , `` intelligent structure , interesting visual experience . '' but what they were saying yes to was a new and startling realness . abandoning the pedestal to dismantle the separation between you and the art . judd claimed these works are neither painting nor sculpture , but instead specific objects occupying real space . these objects are n't pointing to anything or referencing anything . andre called his work a kind of plastic poetry , in which elements are combined to produce space . so there is no illusion of space , it just is space . minimalism had its haters from the start . in 1967 , art critic michael fried attacked the work for being theatrical . for him it was an object in a room that had presence before a viewer , but it did not have what good art has , which is presentness , or , `` an instant of aesthetic experience `` which occurs in no real space or time at all . '' but fried really just ended up affirming exactly what the artists were trying to do : proving how radical it really was . despite its detractors , minimalism became all the rage . this geometric , unadorned style flowed throughout the worlds of fashion , theater , and design . in short , it was cool . and then because these artists were never trying to be minimalist to begin with , they moved on to other things and other kinds of art had its day . but minimalism changed things . for centuries , art had been trying to trick you , convince you that the hunk of rock was something other than a hunk of rock . but not this . you feel like there 's got ta be some secret to it , but there is n't . there 's nothing to interpret . this is what it is . it was n't supposed to look like art of the past , and it was n't supposed to function like it either . with minimalism , meaning does n't rest inside the object , waiting to be unlocked . the meaning is in the context , and exists in your interaction with it . but minimalism is a resistant lover . it 's just not that into you . it encourages observation , but does n't draw you in , and it was never trying to . remember , these objects were supposed to be emptied of prevention , of mastery , of the usual seduction between art and viewer , and of the grand , glorious traditions that preceded them . but the fetishization and commodification of minimalist art has complicated and polluted these ideas . what 's less real than million-dollar plywood boxes ? and yet , for me at least , minimalist art can still impart a strong feeling , a feeling for space , light , for presence and absence . you 're aware of your own body in the gallery as you 've never been before . you notice that your position in the room shapes your perception of the thing . you appreciate the architecture and the spareness , and in a world filled with complexity and information and lots and lots of stuff , this is a balm . this is a world more simplified than the actual world is , and that i can appreciate .
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some of it was painting by artists like frank stella and ellsworth kelly , but most of it was sculpture by artists like donald judd , carl andre , dan flavin , anne truitt , robert morris , tony smith , ronald bladen , and sol lewitt . art critics called it abc art , object art , primary structures , and cool art , but the term minimalism prevailed . these artists never called their art minimalist , by the way , nor did they like the term , or the implication that the work was so reductive that it was minimally art .
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what decade sparked the minimalist art movement ?
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an estimated 20 million cases of blindness worldwide are caused by cataracts , a curable condition affecting the lens that focuses images onto the eye 's retina . a cataract occurs when proteins in the lens lose their normal arrangement , clumping together in a way that causes discoloration or clouding , and eventually blocks most vision . cataracts can be caused by eye injury , certain medications , ultraviolet radiation , diabetes , smoking , or some genetic disorders . but the most common cause is aging . in the united states , more than 50 % of people over the age of 80 develop them . cataracts were treated over 2,500 years ago in india , though similar procedures may have existed even earlier in ancient egypt and babylon . the most common procedure , called couching , involved pressing a sharp instrument into the eye to loosen and push the clouded lens out of the way . although this could increase the amount of light entering the eye , the lack of a lens would leave the patient 's vision out of focus . despite its low success rate , and high risk of infection or injury , couching is still performed in some parts of the world . later procedures would also focus on removing the cloudy lens , for example , by making an opening in the cornea to pull out the lens along with the membrane capsule surrounding it . while the invention of eyeglasses allowed for some restoration of focus , they had to be extremely thick to help . furthermore , such techniques still caused complications , like damaging the retina , or leaving the eye with uncomfortable stitches . but in the 20th century , something unexpected happened . eye surgeon sir harold ridley was treating world war ii casualties when he noticed that acrylic plastic from a shattered aircraft cockpit had become lodged in a pilot 's eyes without triggering an adverse reaction . this led him to propose surgically implanting artificial lenses into the eye to replace cataracts . and despite initial resistance , the method became standard practice by the 1980s . since ridley 's discovery , the intraocular lens has undergone several improvements . modern lenses can fit into the membrane capsule that the cataract is extracted from , leaving more of the eye 's natural anatomy intact . and the ability to fine-tune the lens curvature allows the surgery to restore a patient 's normal vision without the need for glasses . of course , surgical techniques have also progressed . microscopic procedures use small instruments or lasers to make precise incisions of one or two millimeters in the cornea , while an ultrasound probe breaks up and removes the cataracted lens with minimal trauma to the eye . low-tech versions of this operation have made the surgery quick and inexpensive , helping it spread across the developing world . places like aravind eye hospital in india have pioneered high-volume , low-cost cataract surgery for as little as six dollars . why then , with all these advances , are there still so many blind people in the world ? the main issue is access to health care , with poor infrastructure and a shortage of doctors being a major barrier in many regions . but this is not the only problem . in many rural areas with poor education , blindness is often accepted as an inevitable part of aging , for which someone might not think to seek treatment . this is why information is crucial . increased community awareness programs and the spread of mobile phones mean that many of those who might have remained blind for the rest of their lives due to cataracts are now reachable . and for them , a brighter future is in sight .
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a cataract occurs when proteins in the lens lose their normal arrangement , clumping together in a way that causes discoloration or clouding , and eventually blocks most vision . cataracts can be caused by eye injury , certain medications , ultraviolet radiation , diabetes , smoking , or some genetic disorders . but the most common cause is aging .
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cataracts affect the _____ of the eye .
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think about how your favorite stories hook you . `` when he was nearly 13 , my brother jim got his arm badly broken at the elbow . when it healed , and jim 's fears of never being able to play football were assuaged , he was seldom self conscious about his injury . '' `` all this happened , more or less . the war parts , anyway , are pretty much true . one guy i knew really was shot in dresden for taking a teapot that was n't his . '' `` my father 's family name being pirrip , and my christian name philip , my infant tongue could make of both names nothing longer or more explicit than 'pip . ' so i called myself pip , and came to be called pip . '' imagery , intrigue , emotion : each introduction makes you want to read more . if you have an assignment to write a literary analysis , your introduction will be just as important . there will be four elements in your essay : your introduction , thesis statement , analysis and conclusion . if you begin writing a literary analysis with the introduction , you may be discouraged . here 's a tip for writing a great introduction : write it last , and write your thesis first . figure out what you want to analyze before you actually analyze it . your thesis is the foundation for the rest of your essay , including your introduction . so how do you find your thesis ? start by asking questions . to charles dickens you may ask , `` why do you draw attention to characters ' hands ? '' `` what 's up with their names ? '' `` pumblechook ? really ? '' to narrow your concept for analysis , answer the questions yourself . `` estella ridicules pip 's hands , jaggers constantly washes his hands , pip insufferably burns his hands , mrs. joe brings pip up by hand . '' are there patterns in your answers ? `` estella 's comments smack of cruelty , while jaggers ' cleanses his immoral conscience . pip finds a second chance , while mrs. joe abuses a child under the guise of love and dedication . '' what can you analyze with this pattern ? `` hands symbolize social class inequities , and through dickens ' criticism , he exposes the dire need for reform in victorian london . what you will do next , which is an entirely different lesson , is to draft and revise your analysis . only after you write your analysis , return to your introduction . like authors earlier , try to intrigue and inspire your reader . avoid starting with famous quotations , dictionary definitions or rhetorical questions . consider the historical context of your topic , or an anecdote or some larger idea or concept . here 's an example : `` 27 bones in the hand and wrist allow humans to concurrently create and destroy . thousands of hands have been behind history 's astounding creations . hands represent a powerful symbol , one that was not lost on charles dickens . in great expectations , dickens uses hands to symbolize social class inequities , and through his criticism , he exposes the dire need for social reform in victorian london . '' take time crafting and revising your thesis and introduction . remember , if you are bored while writing , your reader will be bored while reading . by the way , did you notice the introduction to this lesson ? it did n't start with `` here 's how to write a thesis and introduction . '' would that have hooked you ?
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imagery , intrigue , emotion : each introduction makes you want to read more . if you have an assignment to write a literary analysis , your introduction will be just as important . there will be four elements in your essay : your introduction , thesis statement , analysis and conclusion . if you begin writing a literary analysis with the introduction , you may be discouraged .
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what is not one of the four elements that a literary analysis should include ?
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think of all the food made in the world each year . hard to picture ? then , imagine that you are all of humanity , and on a plate in front of you is the one lovely annual meal you make for yourself . you did all sorts of work putting that meal on your table . you must be eager to consume the fruits of your labor . and the vegetables and meats and waffles of your labor , too , right ? well , oddly enough , a third of that meal ends up in the trash . a third of the food we eat globally , an estimated 1.3 billion tons ends up as waste . all the work we put into producing that food is wasted . and what 's worse , it costs us . america alone spends an estimated 165 billion dollars a year managing food waste . we 're wasting food , energy , and money . perhaps worst of all , we 're wasting the chance to change , to make the system of food consumption more efficient . if you want to bring on that change , you should know about a humble yet diligent and ever-so-crucial ally : the worm . worms convert organic waste and other compostable products into natural fertilizers . up to 75 % of what we put in the waste stream can become food and bedding material for vermicomposting . you can create a worm bin in your own home to see the composting process in action . first off , you need worms and not your typical earthworms . you need redworms , eisenia foetida , the species responsible for most vermicomposting in north america . these red wigglers are surface dwellers who do n't burrow too deep , they 're optimal feeders around room temperature , and they 're well-suited to converting organic waste into usable fertilizer . now , your worms might be vermin , but they need a comfortable space to live and work : some bedding materials , either shredded paper or cardboard , some moisture , and , of course , food , mainly , your leftovers , slightly decomposed table scraps . the worms break down food waste and other organic matter into castings , a fancy synonym for worm poop . their excrement is absolutely teeming with microbes , which continue the decomposition process , making all those once-wasted nutrients available again as fertilizer . the timeline for the whole process varies depending on the quantity of worms , the temperature , and how much waste is added to the bin . and there 's another timeline to consider . in a healthy worm-bin habitat , worm reproduction will occur when the wigglers become sexually mature , indicated by an elongation of the segments into a bulbous structure . three-month old wigglers can produce two to three semi-translucent yellow worm cocoons a week . you thought only moths and butterflies come out of cocoons ? well , we ca n't all be majestic . it takes around 11 weeks for new babies to hatch . when your bin seems to be full of living vermicelli noodles , it 's time to share the bounty with your friends and start a vermicompost club . or keep those worms to yourself and start a business . vermicomposting is n't confined only to small worm bins , it 's an emerging entrepreneurial enterprise . large-scale facilities convert bulk organic waste and even manure into rich , black castings called black gold . its value as a soil additive is unparalleled , and it can help plants resist harmful pathogens . the lack of available land in urban environments , coupled with growing interest in smaller-scale farming means there is a market for vermicomposting . many communities use composting as part of zero-waste strategies , and they can sell their worm-eaten table scraps to local farms , hungry for rich fertilizer . so , instead of wasting money , dumping wasted food in landfills , we can remake waste into an asset , putting it back into our food system to make it more sustainable , all with the help of the humble worm , the tiny organism that can help us change the way we look at food 's place in our lives and our place in the world , as long as we give the little guy a place at our table . well , not an actual seat at the table . a bin in the shed is fine .
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well , oddly enough , a third of that meal ends up in the trash . a third of the food we eat globally , an estimated 1.3 billion tons ends up as waste . all the work we put into producing that food is wasted .
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according to the fao ( the food and agriculture organization of the united nations ) , what ratio of the food produced in the world ends up as waste ?
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translator : jessica ruby reviewer : brian greene could human civilization eventually spread across the whole milky way galaxy ? could we move beyond our small blue planet to establish colonies in the multitude of star systems out there ? this question 's a pretty daunting one . there are around 300 billion stars in the galaxy , which is about 160,000 light-years across . so far we 've sent a single spacecraft outside our solar system , trudging along at 0.006 % of the speed of light . at that rate , it would take over 2.5 billion years just to get from one end of the galaxy to the other . and then there 's the question of human survival . the gulf between stars is simply enormous . we could n't live sustainably on most planets , and we require a lot of resources to stay alive . and yet , decades ago , scholars found that it 's theoretically possible to not just spread human civilization across the galaxy , but to do so quite quickly , without breaking any known laws of physics . their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets . they would then mine the available resources and harvest energy , build replicas of themselves , launch those to the nearest planets , and continue the cycle . the result is the creation of millions of probes spreading outwards into the universe like a drop of ink in a fishbowl . scholars crunched the numbers and found that a single von neumann machine traveling at 5 % of the speed of light should be able to replicate throughout our galaxy in 4 million years or less . that may sound like a long time , but when you consider that our universe is 14 billion years old , on a cosmic scale , it 's incredibly fast - the equivalent of about 2.5 hours in an entire year . creating von neumann machines would require a few technologies we do n't have yet , including advanced artificial intelligence , miniaturization , and better propulsion systems . if we wanted to use them to spread actual humans throughout the galaxy , we would need yet another technological leap - the ability to artificially grow biological organisms and bodies using raw elements and genetic information . regardless , if in the last billion years an alien civilization created such a machine and set it multiplying its way toward us , our galaxy would be swarming with them by now . so then where are all these machines ? some astronomers , like carl sagan , say that intelligent aliens would n't build self-replicating machines at all . they might hurtle out of control , scavenging planets to their cores in order to keep replicating . others take the machines absence as proof that intelligent alien civilizations do n't exist , or that they go extinct before they can develop the necessary technologies . but all this has n't stopped people from imagining what it would be like if they were out there . science fiction author david brin writes about a universe in which many different von neumann machines exist and proliferate simultaneously . some are designed to greet young civilizations , others to locate and destroy them before they become a threat . in fact , in brin 's story `` lungfish , '' some von neumann machines are keeping a close watch over the earth right now , waiting for us to reach a certain level of sophistication before they make their move . for now , all we have is curiosity and theory . but the next time you look at the night sky , consider that billions of self-replicating machines could be advancing between stars in our galaxy right now . if they exist , one of them will eventually land on earth , or maybe , just maybe , they 're already here .
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and yet , decades ago , scholars found that it 's theoretically possible to not just spread human civilization across the galaxy , but to do so quite quickly , without breaking any known laws of physics . their idea is based on the work of a mathematician named john von neumann , who designed on paper machines that could self-replicate and create new generations of themselves . these would later come to be known as von neumann machines . in the context of space exploration , von neumann machines could be built on earth and launched into space . there , the self-sufficient machines would land on distant planets .
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what mechanisms could be installed in the machines so that they do not go out of control ?
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