美国《科学六十秒》听力原文
60second-science(60秒科学)2014.6月 听力原文
Cool Kids Get Schooled With Age Kids deemed cool in early adolescence have a poor chance to keep that status by their early twenties, because their behavior gets old. Erika Beras reports.Here‟s something you might have figured out at your high school r eunion or by Facebook-stalking your old classmates: being one of the cool kids does not necessarily mean being cool for life. And now, a study in the journal Child Development confirms that suspicion. [Joseph P. Allen et al, What Ever Happened To The …Cool‟ Kids? Long-Term Sequelae Of Early Adolescent Pseudomature Behavior]Researchers followed ethnically and racially diverse suburban and urban kids from early adolescence to early adulthood. The kids who were deemed cool at a young age were high-status individuals with romantic relationships who broke rules and laws.But they were no longer viewed that way by peers by the time they were in their early 20‟s. The pseudo-mature behavior that seemed so admirable at a young age lost cache as the other kids gained actual maturity.Meanwhile, as the young James Deans and Miley Cyruses aged they had to engage in ever-riskier behavior to keep thinking of themselves as cool.By their early twenties, they were more likely to have drug and alcohol problems, relationship issues and criminal involvement. Turns out being a cool kid has a really short shelf life.—Erika Beras(The above text is a transcript of this podcast)White Bread May Actually Build Strong Bodies 1 WayThe guts of white bread eaters appear to contain more lactobacillus, a type of bacteria that wards off digestive disorders. Karen Hopkin reportsJun 20, 2014 |By Karen Hopkin[Audio of vintage Wonder Bread commercial]You can beat on Wonder Bread all you want. [Audio of columnist James Norton: “You can make a completely credible pillow out of this stuff.”]But it just keeps bouncing back—because despite its nutritional bad reputation, white bread appears to boost the growth of good gut bacteria. That‟s according to a pap er in the Journal of Agricultural and Food Chemistry. [Adriana Cuervo et al, Pilot Study of Diet and Microbiota: Interactive Associations of Fibers and Polyphenols with Human Intestinal Bacteria]In recent years, white bread has been shunned as a glutenous slab that lacks the health benefits of whole wheat. But this new study suggests there‟s more to the story.The researchers were looking at the effects of foods on the types of microbes that live in our intestines. They gathered data on the diets of 38 healthy adults and then analyzed the bacteria present in the subjects‟ stool samples. Hey, it‟s for science.Turns out that volunteers who ate white bread had more lactobacillus, a type of bacteria that wards off digestive disorders. Seems the starch and fibers in this sandwich staple are good for these germs.But before you make your lunch, another recent study showed that eating white bread is associated with obesity. So you should take all these findings with a pinch of salt. But not too much salt—especially if you have high blood pressure.—Karen Hopkin [The above text is a transcript of this podcast.]Plant Spores Hitch Long-Distance Feather RidesTiny spores from mosses, algae and lichens can stick in bird feathers, travel from the Arctic to the bottom of South America and grow into whole new specimens. Erika Beras reportsJun 18, 2014 |By Erika BerasYou could be in the Arctic and spot some moss. And then you could be at the tip of South America and spot the same kind of moss—and never find it in between. So how did this particular plant get so well-traveled? Turns out it flew.We‟ve long known that birds spread seeds. But new research says migrating birds also spread microscopic spores.The birds harbor tiny parts of plants and lichens in their feathers, setting up similar colonies thousands of miles apart. That‟s according to a study in the journal PeerJ. [Lily R. Lewis et al, First evidence of bryophyte diaspores in the plumage of transequatorial migrant birds]Scientists inspected feathers from birds in the Arctic that were about to leave for South America. Fragments from mosses, algae, lichens and liverworts were trapped in the feathers. All of which can grow into new whole organisms.The researchers think that long-distance fliers such as the American golden-plover and the white-rumped sandpiper picked up the spores while lining their nests. Then when the birds arrive in new places they molt, leaving behind the feathers and their precious cargo—to start growing again at the other end of the world.—Erika Beras [The above text is a transcript of this podcast.]Jellyfish Galaxies Get Guts Ripped OutRecently discovered galaxies shaped like jellyfish leave a long trail of hot gas and dust, victims of even hotter gas from their surrounding cluster of galaxiesJun 17, 2014 |By Ken Croswell and Steve MirskyA recently discovered breed of galaxies really caught astronomers‟ attention. Because they look like jellyfish.Astronomers found the first jellyfish galaxy a decade ago. Such a galaxy has a disk of stars, like our Milky Way—plus long blue tendrils. A jellyfish galaxy was once a spiral like the Milky Way, spawning new stars from its gas and dust. But unlike the Milky Way, a jellyfish belongs to a cluster of galaxies.A recent analysis of Hubble telescope images led to the conclusion that extremely hot gas from the cluster is behind the formation of jellyfish. That study is in the Astrophysical Journal Letters. [H. Ebeling, L. N. Stephenson, and A. C. Edge, Jellyfish: Evidence of extreme ram-pressure stripping in massive galaxy clusters]As the galaxy plows through space, this hot gas rips out the galaxy's own gas and dust, forming the long streamers behind the galaxy. This torn-out gas still gives birth to new stars. The brightest of these newborn stars shine blue. So the former disc-shaped galaxy metamorphosizes into a celestial jellyfish sporting long blue tendrils.The galaxy will eventually literally run out of gas, and thus lose the ability to create any more new stars. Jellyfish in the sea can be deadly. But in space, the mortally wounded victim is the jellyfish galaxy itself.—written by Ken Croswell, voiced by Steve Mirsky [The above text is a transcript of this podcast.]2-Face Moon Tells How It Got That WayA new analysis says that the asymmetry between the two faces of the moon is due to crust thickness differences that resulted from variable cooling rates after the molten formation of our companion. Karen Hopkin reportsJun 13, 2014 |By Karen HopkinThe dark side of the moon. It‟s remote and mysterious. And not just because we can‟t see it from Earth. When viewed from space, th e moon‟s back side looks totally different from its front. Now, researchers think they have a solution to the mystery, which they share in the Astrophysical Journal Letters. [Arpita Roy, Jason T. Wright, and Steinn Sigurðsson, Earthshine on a Young Moon: Explaining the Lunar Farside Highlands]You may have wondered about the "man in the moon," that facelike image made by the large flat plains on the lunar surface that faces us. But scientists wonder why the far side doesn‟t have comparable features.According to the new analysis, this asymmetry has to do with how the moon was made. Not long after the Earth formed, a Mars-sized hunk of intergalactic debris smacked into our baby planet, flinging off material that then became the moon. The crash left both bodies boiling hot. But the smaller moon cooled down more quickly than the molten Earth… especially the part that faced the other way.The minerals on the moon‟s cooler side started to p recipitate sooner. That head start gave the far side a thicker crust, which is more resistant to the weathering seen on the familiar side: weathering that gives a face character. Even on the moon.—Karen Hopkin [The above text is a transcript of this podcast.]Classroom Decorations Can Distract Young StudentsFive-year-olds in highly decorated classrooms were less able to hold their focus, spent more time off-task and had smaller learning gains than kids in bare rooms. Erika Beras reportsJun 11, 2014 |By Erika BerasRemember your kindergarten classroom? The maps on the wall, the charts of the seasons on bulletin boards, the alphabet over the blackboard? I know I spent hours staring at the brightly colored decorations—and not listening to what my teacher was saying. Maybe you did, too. And it looks like we‟re not alone.The more decorations in a classroom, the more distracted students may be. So finds a study in the journal Psychological Science. [Anna K. Fisher, Karrie E. Godwin and Howard Seltman, Visual Environment, Attention Allocation, and Learning in Young Children: When Too Much of a Good Thing May Be Bad]Researchers observed five-year-olds in highly decorated classrooms and in classrooms that were relatively bare. And the kids were less able to hold their focus, spent more time off-task and had smaller learning gains in the busy rooms than in the bare rooms.At that young age, attention regulation skills aren‟t fully formed. And yet it‟s at that stage of development that children find themselves surrounded by decorations irrelevant to what t hey‟re learning at any given time.The researchers are not prescribing a change from busy to bare rooms. They say there is more research to be done. But this study, along with previous work, suggests that the visual environment can affect how young childr en learn their reading, writing and …rithmetic.—Erika Beras[The above text is a transcript of this podcast.]Kid Scientist Finds Sweet Pest ControlEleven-year-old Simon Kaschock-Marenda's science fair project led to a publication about the insecticidal effects of the sweetener Truvia. Karen Hopkin reportsJun 10, 2014 |By Karen HopkinYou can catch more flies with honey than with vinegar. But if you want to kill them, you might try Truvia. Because a new study shows that the active ingredient in this popular sweetener can act as an insecticide.The study began as a sixth-grade science-fair project. Eleven-year-old Simon Kaschock-Marenda noticed that his parents had stopped using sugar. So he decided to see how different sweeteners affect the health of fruit flies. He and his dad, a card-carrying biologist, offered the flies food spiked with a variety of no-cal sweeteners. Six days into the experiment all the Truvia-fed flies were dead, while those stuck with Sweet-n-low, Splenda or Equal lived five to seven weeks.Why Truvia makes flies drop like flies is still a mystery. Back in the lab, the researchers confirmed that the bugs weren‟t starving: they all continued to eat. Mos t actually seemed to prefer Truvia to real sugar when offered a choice, findings published in the journal PLoS One. [Kaitlin M. Baudier et al, Erythritol, a Non-Nutritive Sugar Alcohol Sweetener and the Main Component of Truvia®, Is a Palatable Ingested Insecticide]Next, the researchers will see if the sweetener kills other bugs, like cockroaches or ants. Until then, try tossing a little Truvia in your coffee, and on the counter.—Karen Hopkin [The above text is a transcript of this podcast.]Light Colors Become Fashion Rage for Northern Europe's InsectsAs northern Europe warms, the light-colored butterflies and dragonflies typically found in the Mediterranean are moving north, and outcompeting their darker-colored rivals. Erika Beras reportsJun 9, 2014 |By Erika BerasFor insects in Europe, climate change has led to habitat change. In the past couple of decades, for example, Mediterranean butterfly and dragonfly species have been found flying around places previously off limits to them—new new northern climes such as Germany.Now a study in Nature Communications finds a colorful reason for the northern expansion. As northern Europe warms, the light-colored butterflies and dragonflies typically found in the Mediterranean find themselves able to survive in the newly warmer north, and to even outcompete their darker-colored rivals. [Dirk Zeuss et al, Global warming favours light-coloured insects in Europe]Lighter colors reflect sunlight while dark colors absorb it and heat up. Hence chocolate ice cream melts in the sun faster than vanilla. Lighter-colored insects thus function well in warmer climates. They don‟t overheat as easily and can stay active longer, giving them a leg up—well, six legs up—in our warming world.The researchers say this migrat ion of insects shows that climate change isn‟t something that‟s coming—it‟s already happening. And it could drastically affect which insects up end up where. Which will in turn affect us.—Erika Beras[The above text is a transcript of this podcast.][Scientific American is part of Nature Publishing Group.]London Fish Chip Away atHistorical UnknownsIsotope composition within fish tails found in London archaeological digs shows that the city began importing cod from northern Scandinavia some 800 years ago. Cynthia Graber reportsJun 6, 2014 |By Cynthia GraberLondoners love their fish. And according to a new study, in the early 13th Century they suddenly started importing it from as far away as the Arctic near Norway. The research is in the journal Antiquity. [David C. Orton et al, Fish for the city: meta-analysis of archaeological cod remains and the growth of London's northern trade]About the year 1000, sea fishing increased significantly in northern Europe. To see how that increase influenced urban growth, researchers looked at 95 excavation sites in London. Which included about 3,000 bones from cod fish.Cod are decapitated before being dried for transport. So finding heads meant the fish were local. And the researchers found that as fish heads appear to decrease in the early 1200s, fish tails dramatically increased—a sign of importation.Examination of the chemical isotopes in the tails matched those for fish in waters far to the north, probably off Norway close to the Arctic, more evidence of import.The scientists do not know if the rapid switch from local to imported cod happened because local fish were n‟t as plentiful as the population increased, or if the market became flooded with dried imports from the north. But these fish tails tell a story of London becoming a growing economic center, and part of a globalizing fish trade.—Cynthia Graber [The above text is a transcript of this podcast.]Meteor Storm Went from Sizzle to FizzleThe May Camelopardalids meteor outburst turned out to be a dud, because meteor storm prediction is not a sure thing, unlike, for example, calculating the next eclipseJun 4, 2014 |By Ken Croswell and Steve MirskyWhat if they held a meteor storm and no meteors came? That's what many people are asking after the well-hyped May Camelopardalids meteor outburst turned out to be a dud.Most meteors arise from mere dust grains and pebbles in space. When Earth passes through a stream of this debris shed by a comet, the particles burn up in our atmosphere, and we see a meteor shower.Some astronomers had predicted that on the night of May 23, particles from a comet called LINEAR would bring many meteors to the night sky. North America had the best seats for the event.And so a lot of people watched and waited. But no one saw much.Meteor showers are common, and the best produce about a hundred meteors per hour. But meteor storms, which can send out thousands of meteors per hour, are rare and notoriously unreliable.Not only can predicted storms go bust, but great storms can erupt without warning. In November 1966, the normally weak Leonids surprised everyone and roared back to life, producing more than 100,000 shooting stars in a single hour.You can still count on astronomers to tell you exactly when the next eclipse will be. But if they ever promise you a meteor storm, you should take it with a grain of, well, meteor dust.—written by Ken Croswell, voiced by Steve Mirsky [The above text is a transcript of this podcast.]。
2007年听力america science 60s 文本
Gadget Calculates Carbon FootprintIt’s popular today for people and companies to try to offset their carbon footprint. But there’s a lot of debate about just how to measure that footprint. Now a new program called Carbon Hero may have one solution. The device was invented by a graduate student at the Royal College of Art in London and recently won the 2007 European Satellite Navigation Competition. The idea is to get an accurate read on how much carbon you use as you travel. It’s a hand-held unit, about the size of a key chain. It automatically identifies the form of transportation the carrier is taking by measuring the speed, location, and pattern of the movement. Then the information is automatically downloaded to a cellphone, which immediately displays the carbon generated and the impact of the user’s actions.Of course, the device doesn't measure other aspects of a carbon footprint, such as the size of your house. And it’s not yet available to consumers. But the inventor hopes to develop the device, and that the immediate feedback will convince people to change their transportation. Maybe to walking. Which leaves a tiny footprint.—Cynthia Graber/podcast/episode.cfm?id=753B8587-C02E-0E98-A8CBE564ADDFC5752Recipe For Snow Includes Cloud MicrobesNext time you’re shoveling snow off your walk, don’t blame the weatherman—blame bacteria. Because an international team of scientists has found that microbes that float through the atmosphere can seed the formation of ice crystals in clouds. Crystals that then precipitate snow. The discovery is described in the February 29 issue of Science.Some bacteria, including bugs that infect plants, have been known to catalyze the growth of ice here on earth. So the scientists got to wondering whether they might do the same in the sky. Making atmospheric ice crystals is the first step in any recipe for precipitation, whether the final dish is rain or sleet or snow. So the scientists collected fresh snow from various places around the world, including the French Alps, Antarctica and Bozeman, Montana. They found that most of their samples contained cells and cell fragments, and that these biological materials were capable of nucleating the growth of ice.How the bugs got there in the first place is anybody’s guess. The scientists figure microbes may drift thousands of miles before they get caught up in a cloud and scare up a storm. Just something to ponder next time you stick out your tongue to catch a pretty snowflake.3Pavement Changes Weeds SeedsFor worse or for better, humans are changing the course of evolution. On February 26, we talked about how fishing practices may be driving the evolution of smaller, harder-to-catch trout. This week brings news that urbanization has changed the way weeds make seeds. The results appear in the current online edition of the Proceedings of the National Academy of Sciences. Scientists in the South of France were studying the sort of weed you see cropping up around the base of trees planted along city sidewalks. The weed, called Crepis sancta, can make two different kinds of seed: one that’s light like a dandelion seed with a feathery little parachute that gets carried by the wind; and another that’s heavy and just drops to the ground.The scientists compared weeds that were growing in these small urban patches to ones growing in an open field. They found that the urban weeds produced fewer of the fluffy seeds than their country cousins, which makes evolutionary sense because in a city setting, drifting seeds are more likely to hit pavement than soil. In the long run, though, that strategy might not be healthy. Because plants benefit from spreading their seeds. So that’s bad news for the weeds. But maybe not so bad news for the sidewalks.—Karen Hopkin4Conserving the GalapagosThe history of science is inextricably linked to the Galapagos and its influence on Darwin. In 2001, an oil tanker hit a reef in the Galapagos Islands and spilled potentially disastrous amounts of oil on one of the world’s most historic nature reserves. Today, the Galapagos are starting down a path to do away with imported oil. Ecuador, which owns the islands, recently installed three wind turbines, in cooperation with the UN and major energy companies. Wind power will replace half of the diesel previously needed. But there are challenges.First, the electrical grid must be updated to accommodate the intermittent power supplied by wind. And there are also ecological issues. One of the original proposed sites contained nests of birds known as petrels. But after they moved the site, researchers realized they knew little about the flight patterns of petrels. So they initiated a study. Once it was determined that the birds would fly safely out of the way of giant turbine blades, construction began. The addition of solar power could make the Galapagos nearly energy independent by 2015—and free from any further oil spills.—Cynthia Graber5Telescope Will Come To The Dark SidePutting a giant radio telescope on the dark side of the moon will enabled an unparalled "view" of the universe. Adam Hinterthuer reports.Earlier this month, NASA announced that an MIT physics professor will lead a team of scientists on a new mission. The objective? Build a giant radio telescope on the far side of the moon. You see, long, long ago—before there even was a galaxy far, far away—the universe settled into a cosmic Dark Age. It was a billion year period following the Big Bang and it produced the structure of space as we know it. Astronomers have long hoped to detect the faint, low-frequency radio emissions generated from this time so they could learn more. But thanks to interference from the ionosphere, not to mention tons of radio and TV signals, Earth is a lousy place to hear.Luckily, the moon rotates so that one side always faces out into space, making it free and clear of noise pollution. The MIT team will use automated vehicles to arrange hundreds of antennas across two square kilometers of the moon’s quiet side. From this perch, they hope to hear the waves produced from the birth of the universe and get in tune with how it all came to be.—Adam Hinterthuer6Nets Drive Evolution of Small FishIn a test lake stocked with two types of trout, fishing with nets mostly caught larger, faster-growing fish, leaving smaller, slower growers to survive and pass on those traits. Karen Hopkin reports. /Being a big fish in a small pond is more likely to get you noticed. That’s good news if you’re, say, the best pitcher in your little league division. But it’s not so good if you’re an actual fish. Because bigger fish are the ones that tend to get caught. Not only is that bad news for the fish, but it may be bad for the whole fish population. Or so say scientists from Australia and Canada in the online edition of the Proceedings of the National Academy of Sciences. They find that fishing for the largest individuals targets the fastest growers, leaving behind their slower-growing counterparts. Which means that current fishing practices may favor the evolution of slower-growing fish.The scientists stocked two small lakes in British Columbia with two strains of rainbow trout: one that grows quickly and is more aggressive in chasing down food and another that grows slowly and tends to be more cautious. They then used commercial gillnets to fish the lakes and found that they bagged the bolder fish three times faster than the shy ones, which were left behind to multiply. So we could inadvertently be breeding fearful small fry that are nearly impossible to catch. Which would make them…hard-to-see food.—Karen Hopkin7Better Beams Give More Big Bang For BuckParticle beams traveling at almost the speed of light get lined up after information going evenfaster tells devices to straighten things out. The result may provide information about the Big Bang. Cynthia Graber reports.-------------Physicists at the Brookhaven National Laboratory have been able to send information ahead of particle beams racing at nearly the speed of light. And the message to the beams is: Get in line. This technique has been developed at other labs but never used before with particle beams traveling in discrete bunches. These bunches are important in recreating that singular moment, the Big Bang.In these experiments, there are two different sets of ions, electrically charged particles, zooming towards each other around a 2.4 mile track. They collide into one another to recreate conditions that provide info about the Big Bang. But the ions spread out as they move. And this means that there are fewer collisions.In a technique called stochastic cooling, scientists first measure fluctuations in the beams of ions. Then they send signals even faster than these particles to devices up ahead that can kick these particles back into shape. Researchers say this technique allows them to create these collisions much more frequently and cheaply than other methods. And so they can get more and better data about what our universe might have been like just after it came into existence.—Cynthia Graber8This Is Your Brain On ArtsA three-year, multi-institutional study finds that early training in performing arts is really good for the brain. Steve Mirsky reports. For more info, go to Are smarter people drawn to music, theater and dance? Or does arts training in childhood change the brain in positive ways? In 2004, the philanthropic Dana Foundation created a consortium of neuroscientists from seven universities to address those questions. On March 4, the group released a report, Learning, Arts, and the Brain, available at . Some of the findings:An interest in performing arts helps develop sustained attention spans, which can improve other areas of cognition. Links exist between training in music and the ability to manipulate information in both short-term and long-term memory. Music training also appears to improve kids’ capacity forgeometric representation, as well as the acquisition of reading skills. Acting classes lead to improved memory, via better language skills. Dance learning is done through observation and mimicry, and that training appears to improve other cognitive skills. So science says that dance, theater and music can make life full of sound and glory, signifying something.—Steve Mirsky9A Bill of Rights for ScientistsThe Union of Concerned Scientists wants Congress to pass a Scientists' Bill of Rights to protect federal researchers from political pressure and intrusion. Steve Mirsky reports. For more information, go to /scientificfreedomOn February 14th, the Union of Concerned Scientists issued a call for the protection of federal scientists. The UCS press conference took place in space made available by the American Association for the Advancement of Science, whose annual meeting is taking place in Boston. Francesca Grifo is the director of the UCS’s scientific integrity program: “As we transition to the next administration, regardless of who we vote to place at its helm, we must ensure that the falsifying of data; the fabricating of results; the selective editing; the intimidation, censoring and suppression of scientists; the corruption of advisory panels; and the tampering with scientific procedures all stop.”To that end, the UCS wants Congress to pass a scientists’ bill of rights. Kurt Gottfriend is professor of physics emeritus at Cornell University and a cofounder of the UCS: “We therefore call on the next president and Congress to codify the basic freedoms that federal scientists must have if they are to produce the scientific knowledge that is needed by a government dedicated to the public good.”—Steve Mirsky, at the AAAS conference in Boston11Sperm Subject To Attack--By PollutionMice kept in cages near highways and steel mills suffered high rates of mutations in their sperm--in pieces of DNA related to gene expression and disease. Cynthia Graber reports.---------Air pollution is bad for our health, but scientists say we don’t know much about the long-term effects. So researchers in Canada and the Netherlands decided to gather genetic information in an urban industrial environment—by looking at mouse sperm. They published the study in the Proceedings of the National Academy of Sciences.The scientists placed cages of mature male mice near two steel mills and a major highway in the city of Hamilton, in Ontario, Canada. Some of the mice breathed in the ambient, particulate-filled air. The control mice breathed pure, filtered air. After ten weeks, researchers checked the two groups. The mice exposed to the polluted air had a 60 percent higher rate of sperm mutation. It occurred in a piece of DNA particularly susceptible to mutation.Researchers say these specific mutations are known to affect gene expression and genome stability, and could lead to changes in genetic composition and disease. They say they can’t yet extrapolate from these findings to the long-term health effects in humans, but they say the results definitely warrant a more detailed look at pollution’s effects on our genes.—Cynthia Graber13Parasitized Ants Get Berry SickA nematode parasite causes ants to look like berries that birds like, putting ants on the diet and helping to spread the parasite. Cynthia Graber reports.------------When is an ant like a piece of fruit? When it’s infected by a parasite. Researchers affiliated with the Smithsonian Tropical Research Institute discovered this bizarre occurrence in Central America as they were studying the gliding ability of a certain species of ant. They found some colony members with bright red swollen abdomens. The scientists took specimens back to the lab and discovered they were full of hundreds of nematode eggs. The bright red bellies look suspiciously like the brilliant red and pink berries that proliferate in the rainforest.Researchers think that the nematode makes the ant look like fruit to get birds to eat the ants. Birds usually keep the ants off their menu because of armor and a bad chemical taste. The birds then spread parasite eggs in their droppings. Ants forage through bird droppings for seeds. They feed the infected droppings to ant larvae, beginning the infection process all over again. The red-bellied ant is the first known case of a parasite causing fruit mimicry. One of the researchers was surprised that something "dumb as a nematode" can manipulate its host in such a sophisticated way. But evolution works no matter how dumb organisms are.--Cynthia Graber14electric GoldAt the nanoscale, gold wire can act as either a conductor or insulator, making it a candidate as a sensor. Steve Mirsky explains, with reporting by Harvey Black.-------------six atoms, the oxygenated gold becomes an insulator. The scientists reported their discovery in the journal Physical Review Letters.The researchers say these properties mean that gold nanowires might be used as sensors to detectmotion in nanoscale situations such as neurons or nanomachnes (futuristic devices built from individual atoms that might enter cells and fight disease). The wire could be a sensor because when it’s extended even slightly, it could switch from a conductor to an insulator. Using gold as a sensor in this way could never have been predicted from what is known about gold in bulk. But being very small can lead to some big changes.—Steve Mirsky, with reporting by Harvey Black15A Star Is FlungThe star called HE 0437-5439 looks like it was tossed out of the Large Magellenic Cloud by a hypothesized black hole. Steve Mirsky explains, with reporting by Harvey Black.-------------Astronomers have discovered a star that’s running away from home. The star is speeding away at a blistering 2.6 million kilometers/hour, apparently after being cast out of a neighboring galaxy to us, the Large Magellenic Cloud—probably by a massive black hole. The speeding star is the first hint that there indeed may be a black hole in the LMC.The astronomers, writing in an upcoming issue of Astrophysical Journal Letters, reckon that the flung fugitive was sent on its way much like a sling shot propels a stone. They think it was part of a two-star or binary system. Its companion got sucked into the black hole and this one, known as HE 0437-5439, was tossed on its way.The astronomers say that the star cannot be one of our own Milky Way buddies, because the elements composing it are in different amounts from those in the Milky Way. HE 0437 is not the only star fleeing the Milky Way, though. The researchers say there are nine others beating it away from our galaxy, but they say it’s clear that those are Milky Way natives.—Steve Mirsky, with reporting by Harvey Black16Pythons Warm to the U.S.Discarded pet Burmese pythons are breeding in the Everglades--and climate change could make a third of the US potential python habitat. Steve Mirsky reports.-------------Here’s another reason to stop global warming: to keep the Burmese pythons in Florida. Burmese pythons have been turning up in south Florida in recent years. Perhaps you’ve seen the famous photo of a python ripped apart by its efforts to ingest a large alligator. Apparently people with pythons as pets have been getting rid of the snakes when they get too big by dumping them in theEverglades. And in 2003, biologists confirmed the presence of a breeding population of the slithering serpents in Everglades National Park.Which sceeves me out, because I spend a lot of time there. I’m not afraid of timid alligators, but hungry Burmese pythons give me the willies. Anyway, the US Geological Survey recently did an analysis of potential temperatures around the country by the end of this century. And then analyzed where Burmese pythons would be comfortable, based on their home territory, from Pakistan to Indonesia. The result: pythons could colonize a third of the US. Did I mention that they can be over 20 feet long and 250 pounds? Might be the best motivation to do something about climate change.—Steve Mirsky17Warp of the WorldsWidely distributed emails claim--falsely--that Mars will get close enough to Earth to appear as large as the moon. Steve Mirsky and Orson Welles report.--------------------Audio clip of Orson Welles: “That grinning, glowing, globular invader of your living room is an inhabitant of the pumpkin patch. And if your doorbell rings and nobody’s there, that was no Martian—it’s Halloween.” That’s how Orson Welles ended his Mercury Theater version of HG Well’s War of the Worlds on October 30, 1938. The broadcast was designed to sound like live news coverage of an invasion of Earth by Martians. And a lot of people fell for it.Now there’s some more Martian misinformation fooling folks. This one’s not so scary. A lot of people are getting email claiming that in the next few weeks the planet Mars will get close enough to the Earth so that it will appear to be about the same size as the moon. Our friends at Sky and Telescope magazine report that email dating back to 2003 mentioned that in a 75x magnifying telescope Mars would look about as big as the moon does—to the naked eye. Somewhere along the line the telescope part got lost. So don’t worry. Mars, even at its closest, is still small and safely far away.Welles: “It’s Halloween.”18Explain the Universe In Your Sleep!Cosmology@Home is a new distributed computing project that tries to use off-duty home computers to unravel the secrets of the universe. Steve Mirsky reports. For more info, go to --------------------Turning off the computer at night can save energy. But if you’re going to leave it on, here’s something you might want to do with it—figure out the secrets of the universe.Distributed computing projects spread difficult problems out among numerous computers, sometimes around the world. The SETI@Home project is a well-known example, which searches radio telescope data for evidence of extraterrestrial signals. Another project looks for a special class of prime numbers called Mersenne primes.Now there’s a new distributed computing project called Cosmology@Home. The idea is that your unused computer power can help in cutting-edge cosmology research. The computers come up with predictions based on different theoretical models of the universe that have different parameters. These predictions can then be compared with the actual data that astronomers generate—data such as the acceleration of the universe, the way galaxies are distributed, even the way the cosmic microwave background radiation fluctuates. The models that make predictions that agree with the real data are probably the ones you can trust. The project is funded by the National Science Foundation. For more info, go to 19Autumn Leaves' Brilliant Colors Good For TreesThe bright red leaves of autumn deliver more nutrients to the trees than they would without the brilliant coloration. Karen Hopkin reports.-----------------Fall is here and across the country, leaves are turning their traditional autumn colors. And as always, the sight of so many trees decked out in brilliant reds, yellows, and golds, prompts leaf-peepers, kindergarteners, and even scientists to ponder—how come they do that?After all, it takes energy to produce all those pretty pigments. So why would a tree bother to do it, if those leaves are only gonna turn brown and fall off, anyway?Now, scientists at the University of North Carolina think they know the dirty secret: it’s the soil. Surveying the sweetgum and maple trees in a nature preserve in Charlotte, the North Carolina researchers found that trees that grew in nutrient-poor soil produced more red pigment, results they just presented at the annual meeting of the Geological Society of America.Their findings back a discovery made in 2003, by a researcher in Montana, who found that blocking the production of red pigments, in plants that like to make them, renders their leaves unusually sensitive to sunlight. These super-sensitive leaves deliver fewer nutrients to the plant.So when the soil is poor, it would make sense to make pigment, to keep those leaves workinglonger. Which is good for the trees—and for the peepers.20Prediction of Global Warming High May Be ImpossibleReseachers find that, no matter how much data they collect, they may not be able to get a good estimate of the highest temperature increases that global warming may bring. Karen Hopkin reports. Also see /29z39x-----------------Ben Franklin said that nothing’s certain but death and taxes. Today, scientists might add global warming to that list. But though most scientists are certain that more CO2 means a toastier globe, what they can’t pin down is how much warmer it’s going to get.If that sounds like a forecast only Heisenberg could love, well, too bad—that’s just the way it is. Or so say researchers at the University of Washington in Seattle in the October 26th issue of the journal Science.The researchers were working on equations to help climatologists get the most out of their climate models. The current models, run on decades worth of data, predict that we could be looking at a planet that’s 2 to 5 degrees warmer, although there’s a chance it could be closer to 10.What the researchers discovered is that no matter how much data the scientists feed into their models, they’re never going to get a more precise estimate of the high end than that.Perhaps the finding will encourage policymakers to act now, rather than calling for more data before making any decisions about the environment. Or the lack of definitive info about the worst case scenarios could give climate change skeptics an excuse to try to table any action.21First Land Vertebrates Probably Had Color VisionDNA from the retinas of lungfish, the closest living relatives to the first terrestrial vertebrates, is closer to retinal DNA from land animals than to retinal DNA from fish. The first land creatures thus probably had decent color vision. Steve Mirsky reports.----------------Look before you leap, the old adage has it. Well, it seems that the animals that first ventured out onto the land from the sea were well equipped to look when they made that leap. Researchers studied the retinas of the eyes of lungfish, which are thought to be the closest living relatives to the first vertebrates that lived on land. Lungfish use gills to take in oxygen, but can also breathe air if necessary. And they live in shallow freshwater habitats with a lot of light. So it wouldmake sense that they could see pretty well in a nearly terrestrial environment.And indeed, DNA in the genes for visual pigments in the retinas of the lungfish turned out to be much closer to the sequences found in four-legged animals than with other kinds of fish. The work appears in the journal Biomed Central Evolutionary Biology.So the early land-dwellers were probably pre-adapted to seeing well in their new environment, which must have come in handy for finding food and mates. How did the first creatures that crawled out of the sea smell? Probably pretty bad.22Height Affects Perception of HealthData from England show that shorter people perceive their health as being poorer than tall or average-height people do. Steve Mirsky reports.--------------Height is correlated with a lot of things. Up to a certain height, taller people make more money than the vertically challenged. And the taller presidential candidate almost always wins. Now a study finds that your height as an adult has a profound effect on your perception of your health. Short people judge their health to be worse than average or tall people judge theirs. The research was published in the journal Clinical Endocrinology.Data for the study came from the 2003 Health Survey for England. More than 14,000 participants filled out questionnaires and had their heights measured. The study only looked at how good the subject thought his or her health was, not their actual health. Questions focused on five areas: mobility, self-care, normal activities, pain or discomfort and anxiety or depression. Men shorter than about 5’4” and women shorter than 5’ reported the worst impressions. But small increases in height at the low end had much bigger effects on perception than the same increases among taller people. Other studies have shown, ironically, that shorter people on average actually live longer.23Good Vibrations May Stop Fat From FormingMice that spent 15 minutes a day on a vibrating platform had 30 percent less fat around their middles than mice on stationary surfaces. Karen Hopkin reports.---------------If you’re like me, somewhere in your closet, or maybe in a drawer, you probably have a pair of pants you hope to someday fit into. Again. But staying on a diet and finding time to exercise—it’sno walk in the park.But wait! Before you swear off the spaghetti, scientists at the State University of New York in Stony Brook have stumbled onto a new way to slenderize. They found that mice that spend 15 minutes a day standing on a vibrating platform are leaner than mice who just stand still. Their results appear in the current online edition of the Proceedings of the National Academy of Sciences.All the animals in the experiment were allowed to eat their fill. Interestingly, after 15 weeks, the shaken mice didn’t actually weigh any less. But compared to the mice who hung out on a stationary platform, they had about 30 percent less fat around their middles.The SUNY scientists think that the jiggling kept fat cells from forming. Whether it would do the same for people, you never know. And here you thought New Yorkers were lean and mean because they’re always in a hurry rushing here and there. Maybe it’s because they spend so much time standing on vibrating subway platforms, waiting for theuptown express.24Joe Torre and the Psychology of PersuasionFormer Yankee manager Joe Torre made good use of social psychology techniques that were outlined in a February 2001 Scientific American article by Robert Cialdini called The Science of Persuasion, available at . Steve Mirsky reports.----------------The 12-year tenure of New York Yankees manager Joe Torre ended last week. At a science conference in 2000, Washington Post baseball writer Tom Boswell discussed Torre’s success in terms of the principles set forth in a book called Influence: The Psychology of Persuasion, by Robert Cialdini. Scientific American went on to commission a February 2001 article by Cialdini, available at . The piece discusses six major persuasion factors, which Torre used to such great effect.One is reciprocity—you’re more likely to go out of your way for someone who has done so for you. The second is consistency—acting consistently shows people you can be trusted. Third, social validation—get enough people on the same page and the rest will likely follow due to peer pressure. Fourth is simply likeability—people are more likely to respond to somebody they like. Fifth is authority—Torre’s quiet dignity and outstanding record as a player himself gave him great authority with players. And sixth is scarcity—things in limited supply are more desirable. Which should make the one and only Joe Torre a hot commodity on the baseball market.25Brain Chemical Makes Good Glue。
【听力资料】科学美国人听力原文-科学家或揭开人们追寻记忆味道的奥秘
【听力资料】科学美国人听力原文-科学家或揭开人们追寻记忆味道的奥秘科学美国人听力原文-科学家或揭开人们追寻记忆味道的奥秘在托福听力练习中，我们究竟该选择怎样的材料呢?科学美国人的六十秒科学(简称SSS)是练习托福听力的利器材料，它短小精悍，仅仅有一分钟的时间，语速也非常快。
其中包含了许多科学知识和实验和托福的学术性息息相关，相信能为大家的托福听力提升带来很大的帮助。
听力原文In Marcel Proust’s iconic Remembrance of ThingsPast, a taste of cake elicitsa flood of memories.Now a study finds that the stronger your memory ofa particular food, the more likely you are to chooseit again.And it doesn’t matter how objectively unattractivethe food may be—which perhaps explains why you may crave those peanut butter andmarshmallow sandwiches from your youth or can’t break that fried chicken habit when trying todiet.The food-memory study is in the journal Neuron.Researchers asked 30 hungry young people to rate snacks such as potato chips and chocolate.No actual food was presented.The snacks were merely displayed on screens associated with locations.Then the study participants were asked to choose between two locations, as proxies for thesnacks.And the hungry subjects went with memory over taste preference—that is, they picked whatthey were better able to remember even if they had rated them lower in the first part ofthetest.And the researchers found that the exercise caused increased communication between thehippocampus, associated with memory, and the part of the frontal lobe home to decision-making.Which may show why when we’re making food deci sions, familiarity often wins out over otherfactors—and why your shopping list looks virtually the same week after week.。
60second-science(60秒科学)听力原文2014.5
Thieving Bird Apes Its VictimsThe fork-tailed drongo can mimic the alarm calls of dozens of other species of animals, including nonbirds, to drive them off and steal their food. Cynthia Graber reportsMay 5, 2014 |By Cynthia Graber[Music plays] Neil Young? No, that’s Jimmy Fallon imitating Neil Young. Doing impressions can be a valuable skill. In fact, a bird called the fork-tailed drongo makes a good living at it, in its home in Africa’s Kalahari Desert. The drongo can mimic the alarm calls of another bird. When that bird flees the imagined danger, the drongo swoops in to take any food left behind.An animal mimicking another animal is not rare. And targets can grow wise to the trick. The drongo’s real talent is that it can do the warning calls of multiple species. [Music plays] Like how Jimmy Fallon can also do Van Morrison.Researchers followed 64 wild drongos for nearly 850 hours. Drongos do sound accurate alarms in response to actual predators. But when they spot a tempting meal in another bird’s possession, they send out a false alarm. Here’s one mimicking a pied babbler. [Drongo call]Anoth er a glossy starling’s alarm. [Drongo call]And here’s a drongo mimicking a meerkat alarm. [Drongo call]The researchers saw almost 700 drongo attempts to steal food. They estimate that any one drongo might know up to 32 different species’ alarms. And st olen food accounted for nearly a quarter of their daily intake. The study is in the journal Science. [Tom P. Flower, Matthew Gribble and Amanda R. Ridley, Deception by Flexible Alarm Mimicry in an African Bird]Fool birds once? Shame on them. Fool birds multiple times? Success for the fork-tailed drongo.—Cynthia Graber[The above text is a transcript of this podcast.]Surgeons Try Cold Cutting for Critically InjuredA clinical trial tests whether induced hypothermia can allow surgeons to save critically wounded patients who would not survive surgery at normal temperatures. Erika Beras reportsMay 6, 2014 |By Erika BerasOn rare occasions, a swimmer can survive a near-drowning because cold water has protected their brains—even if they were submerged for up to an hour. Now a clinical trial is testing whether extreme cold can save critically injured gunshot and knife wound patients.It’s called the Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma Study. Lead Surgeon Sam Tisherman at the University of Pittsburgh Medical Center explains that patients are not declared dead, but:“They’d be close. They’re in cardiac arrest and certainly if we can’t get a pu lse back they’d be dead. But we’re not waiting to the point where the surgeons would declare them dead. We’re trying to do this right before this, and find the best window of opportunity where our standard of care hasn’t worked but it’s not too late to try something new.”Surgeons will cool the patients’ bodies to 50 degrees by pumping dozens of liters of cold saline into the heart. This induced hypothermia nearly halts all activity in the body and brain.By freezing patients, the surgeons will also freeze time—giving them the opportunity to repair wounds a warm patient wouldn’t typically survive. Should the procedure prove effective, it could give a new meaning to the phrase “cold comfort.”—Erika Beras[The above text is a transcript of this podcast.]Lasers ID Insects by Wing Beats Using laser sensing of insect wing beats, plus location and time of day, researchers report 99 percent accuracy identifying individuals in a group of six insect species.A future surveillance system would be of interest to farmers and insect-borne disease monitors. Cynthia Graber reportsMay 7, 2014 |By Cynthia GraberTo a farmer, good insects pollinate. And bad insects decimate. And they’ve o ften had a tough time knowing which flying creatures were invading their crops. Now eavesdropping researchers might offer help.For 60 years, scientists have tried to identify insects by their wing sounds. The challenge increases with distance, wind and other noises. So researchers created a monitor using lasers. When an insect crosses the laser, the shadow of the wing beats gets recorded and translated into an mp3. Here’s a female aedes aegypti mosquito. Here’s a female culex quinque fasciatus.The researchers spent three years gathering data from dozens of sensors. They have tens of millions of data points—more than had been previously collected all together—for their algorithms. Using wing beats plus location and time of day, they’ve achieved up to 99 percent accuracy identifying six insect species thus far.The research will be published in the Journal of Insect Behavior. [Yanping Chen, Eamonn Keogh et al, Flying Insect Classification With Inexpensive Sensors]The prototype was made of LEGOs, a 99-cent laser pointer and part of a TV remote. So researchers say a setup could be manufactured for less than $10. It could identify both farm pests and disease carriers. Which could help people picnic in peace. —Cynthia Graber[The above text is a transcript of this podcast.]Oenophiles Confirm Fruity Flavors Finish FirstWine researchers find that fruity flavors tend to finish quickest on the palate, whereas oaky flavors linger longer--as aficionados have long claimed. Christopher Intagliata reportsMay 12, 2014 |By Christopher IntagliataThe lore among wine aficionados is that fruity flavors tend to finish quickest on the palate, whereas oaky flavors linger longer.“And th en when you go to the scientific literature, you find out that really there haven't been scientific studies done on it.” Carolyn Ross, a sensory scientist at Washington State University.She and her colleagues investigated the claims. They identified four flavor compounds common in white wine, which give floral, fruity, mushroomy and oaky notes. They then studied the compounds in what’s known as a model wine: “Meaning that it had alcohol in it, it had some sugar, some acid in it, but it wasn't actually wine.”They added the compounds one at a time to their model wine, and asked trained tasters to clock how long it took flavors to fade. Fruity did indeed finish first—lasting a minute and a half. The others took 30 seconds longer to fade. And even when mixed with the other flavors, fruity still finished first—so the lore was right.The study appears in the journal Food Quality and Preference. [Emily S. Goodstein et al, Perception of flavor finish in model white wine: A time-intensity study]As for home tasters? “Pay attention to the finish,perhaps time it, if that's your thing.” It does happen to be ours.—Christopher Intagliata[The above text is a transcript of this podcast.]Healthy Lung Microbes Keep Mice Breathing EasyLike humans, mice start life with sterile lungs that soon get colonized by microbes, which appear to protect the lung tissue from an asthmalike reaction in the presence of dust mites. Cynthia Graber reportsMay 14, 2014 |By Cynthia GraberHuman cells are outnumbered ten-to-one by the microbes that thrive in and on us. Now a study finds that the tiny organisms living in our lungs may protect us from asthma.A newborn’s lungs start out sterile and then become colonized by microbes. To se e how lung microbes might influence disease susceptibility, researchers studied mice, which also start with sterile lungs that soon host microbes.In the first two weeks of life, these microbial communities shift and proliferate. So the scientists looked at three groups of mice: babies three days old, 15-day-old mice, and two-month old adults. All were exposed to dust mites, which provoke inflammation.The newborn mice developed inflamed lungs—similar to asthma. But the older groups remained mostly inflammation free, indicating a protective role for their lung microbes.The researchers then exposed older mice whose lungs had been kept sterile to mites. These mice did get inflamed lungs. The study is in the journal Nature Medicine. [Eva S. Gollwitzer et al, Lung microbiota promotes tolerance to allergens in neonates via PD-L1]The researchers say that early lung colonization by a diverse, protective microbial community appears crucial. They hope to extend these studies to human infants—to better understand our lung microbes, and help kids breathing freely. (Also see Drugs to Be Derived from Insights into Body-Dwelling Bacteria)—Cynthia Graber[The above text is a transcript of this podcast.][Scientific American is part of Nature Publishing Group.]Twitter Opinion Quickly Stabilizes A study of millions of tweets found that public opinion quickly solidifies, even without an overwhelming concensus. Allie Wilkinson reportsMay 15, 2014 |By Allie WilkinsonAll rise, the Twitter court of public opinion is now in session.And the next case on the docket will reach a quick verdict. Because public opinion solidifies rapidly on Twitter. That’s according to a study in the journal Chaos. [Fei Xiong and Yun Liu, Opinion formation on social media: An empirical approach] Researchers collected almost 6 million tweets during a six-month period. They sorted the tweets for either positive or negative sentiments, then focused on three topics related to electronics.At first opinions fluctuated, with one side gaining a slight advantage. This advantage grew gradually and then quickly leveled off, leaving one opinion in a stable and dominant position—but without an overwhelming consensus.And once public opinion is established, it is unlikely to change. Only those who see a large number of dissenting opinions among the people they follow on Twitter will reconsider and examine the opposing viewpoint.These results may offer a valuable lesson for companies, candidates and anyone elsein the spotlight. If you plan to sway the jury, be sure to make your case early. Because once public opinion stabilizes, the jury is dismissed.—Allie Wilkinson[The above text is a transcript of this podcast.]Wild Beluga Whales Pass Hearing Test Wild beluga whales were found to have hearing comparable with whales in captivity, which sets up a baseline test for hearing damage in other whalesin noisy waters. Christopher Intagliata reportsMay 20, 2014 |By Christopher IntagliataBeluga whales live in the world's cold northern seas, where they endure months of perpetual darkness.“So they have to use sound, rather than sight, in order to find their way around.” That's Aran Mooney, a marine biologist at Woods Hole Oceanographic Institution, in Massachusetts. He says belugas have really fast hearing, too: “Sound underwater travels five times faster than it does in air. And so those guys have to basically perceive and utilize sound five times faster than we do.”He and his colleagues traveled to Bristol Bay, Alaska, to test belugas' hearing in the wild. They captured seven belugas for routine physicals. And played them a series of frequencies, while measuring the whales' brain activity with electrodes.Turns out the whales' hearing was sharp, and similar to that of captive belugas. Which means they could appreciate sound ranging from about 4 kilohertz to 150—a frequency nearly eight times higher than the upper limit of our ears. The results arein The Journal of Experimental Biology. [Manuel Castellote et al, Baseline hearing abilities and variability in wild beluga whales (Delphinapterus leucas)]The older belugas tested in this survey still had decent hearing too. But that might not be the case for belugas living in noisier Cook Inlet, near Anchorage.“There's a lot of military activities, a lot of commercial activities in Cook Inlet, and those animals are known to be declining at a rate of about two percent per year. Andwe think noise is a major stressor to those animals.”And now that researchers know what wild belugas should be able to hear, they can test Cook Inlet belugas—to see whether that underwater noise is, literally, deafening. —Christopher Intagliata[The above text is a transcript of this podcast.]Don Corleone: Not a Nice Guy but No PsychopathMafiosi incarcerated in Italy scored lower than the threshold level for psychopathy on a standard test whereas half the run-of-the-mill inmates qualified as psychopaths. Allie Wilkinson reportsMay 21, 2014 |By Allie WilkinsonMobster. The word conjures images of someone who has no problem giving an enemy a pair of cement shoes and throwing them in the river—and doing so without remorse. In other words, a psychopath. But it turns out that many mobsters are actually less psychopathic than other criminals.Researchers interviewed 30 Mafiosi incarcerated in Italy, and another 39 prisoners who were not involved in organized crime. The inmates’ responses we re then rated against a standard psychological test, called the Psychopathy Checklist-Revised.None of the Mafia members scored higher than a 30, the generally accepted threshold for psychopathy, and only 10 percent had scores that would classify them as moderately psychopathic. Meanwhile, more than half of the non-Mafia men rated as either moderately or severely psychopathic. Mafia membership was also associated with low substance abuse and high family commitment. The study appears in Criminal Behaviour and Mental Health. [Adriano Schimmenti et al, Mafia and psychopathy]The researchers say the findings point to new hope for resocializing convicted mafia members. So that they might permanently “leave the gun…take the cannoli.”—Allie Wilkinson[The above text is a transcript of this podcast.]Polar Bear Rapid Evolution Lets Them Be Fat FitSince diverging from a common ancestor with brown bears less than half a million years ago, polar bears have accumulated genetic changes that allow them to eat a superhigh-fat diet without suffering cardiovascular consequences. Karen Hopkin reportsMay 22, 2014 |By Karen HopkinA triple bacon cheeseburger seems like a heart attack on a plate. So how can polar bears thrive on their version, seal blubber? Turns out they’ve stocked up on genes that let t hem clear fats from their blood. That’s according to a study in the journal Cell. [Shiping Liu et al, Population Genomics Reveal Recent Speciation and Rapid Evolutionary Adaptation in Polar Bears]Polar bears are well adapted to life on the sea ice. Up to half their body weight’s fat, which gives them extra insulation and buoyancy, and provides them with a ready source of energy.But how can an animal so fat also be so fit? Researchers compared the genomes of polar bears with those of brown bears, and found that polar bears have accumulated genetic changes that boost their heart health and fat metabolism. One gene in particular, called ApoB, helps move cholesterol out of the blood—where it causes problems in humans—and into cells.These genomic changes happened quickly, evolutionarily speaking. Polar bears and brown bears diverged from a common ancestor less than half a million years ago. But if that seems super speedy, the abili ty to digest lactose didn’t spread through human populations until we domesticated cows, just 10,000 years ago. A moooving testament to the power of natural selection.—Karen Hopkin[The above text is a transcript of this podcast.]European Invasion Changed Peru's CoastlineSections of Peru's coastline were stabilized by the activities of indigenous people, the demise of whom following the Spanish invasion led to an alteration of the geography. Cynthia Graber reportsMay 27, 2014 |By Cynthia GraberThe Spanish arrival in South America changed many things—including, it seems, even the Peruvian coastline.In dry northwestern Peru, unusual 19-mile-long sandy coastal ridges were formed through tectonic activity, El Niño storms and natural sediment deposit. The nine ridges still standing appear to have formed from 5,100 years ago until about 400 years ago. And they're topped with deposits of shells, rocks from fire pits and other human artifacts.Scientists studying the region found that the shells are from mollusks and barnacles, and primarily of species still fished there today. They thus concluded that the shells were left by native communities who long called the region home.The researchers also found that the clamshell and fire deposits stabilized the ridges and protected them from erosion. No such stable ridges exist along the coast from the past 400 years, after the local people died from disease or war, or were pushed inland. Any incipient ridges since were easily toppled by wind and storms.The research is in the Proceedings of the Natural Academy of Sciences. [Daniel F. Belknap and Daniel H. Sandweiss, Effect of the Spanish Conquest on coastal change in Northwestern Peru]Visitors now see what they may think is a natural landscape. But its formation depended on thousands of years of human activity.—Cynthia Graber[The above text is a transcript of this podcast.]。
sss(含原文)美国科学60秒 ----听力训练
The authors say farmers must learn to use marginal lands that could be prime location for crops such as millet, sorghum and cowpea. Also needed is more investment in livestock research, such as breeding for hardier animals. And wealthier nations that have a significant financial agricultural investment in the developing world should match that with a scientific one. Because helping these small-scale sustainable farmers is the way to feed the world’s poorest people.
These small-scale farmers may raise just a few crops and graze a handful of animals. They’ve been mostly ignored by agricultural assistance agencies—but according to the researchers, these farmers feed most of the world’s poorest billion people. They face challenges from an increasing population; land that’s overfarmed and worn out; and climate change, bringing with it worsening drought or increased rainfall.
2019年托福听力科学美国人60秒：未知星球
2019年托福听力科学美国人60秒：未知星球科学美国人60秒英文文本This is Scientific American 60 Secomds, Space. I'm Clara Moskowitz, got a minute?Solar system conspiracy theorists have long harbored suspicions that a hidden extra planet or dwarf star lies beyond the orbit of Pluto. As a planet, it’s been called Tyche or simply Planet X. As a star, Nemesis.But an exhaustive search has found no hints of this long-rumored object. NASA's Wide-Field Infrared Survey Explorer has scanned the entire sky in infrared light—twice—and ruled out any hidden bodies larger than Saturn out to 10,000 times the distance from the Earth to the sun.Furthermore, it found no evidence for anything bigger than Jupiter out to 26,000 times the Earth-sun distance. Pluto, for comparison, lies only 40 times farther from the sun than Earth.The finding deals a blow to theories that a Planet X- or Nemesis-type object may have caused periodic mass extinctions on Earth. Some theorists have mused that a hidden planet might have swept through bands of comets in the solar system, sending them crashing into Earth. Now it seems that for such mass species die-offs, the fault lies not in the stars.Thanks for the minute for Scientific American 60 Secomds, Tech. I'm Clara Moskowitz.科学美国人60秒中文翻译：这里是科学美国人60秒，太空系列。
2019年托福听力科学美国人60秒：游戏暴力倾向元凶
2019年托福听力科学美国人60秒：游戏暴力倾向元凶科学美国人60秒英文文本This is Scientific American 60 seconds Tech, I'm Larry Greenemeier, got a minute?Video game playing can make you angry or aggressive. But it seems that the key factor may not be the violence. It's the player's incompetence at the game that's behind the ramped-up emotions, whether they're upping their kill count in Grand Theft Auto 3 or simply trying to solve a puzzle in Tetris.That's the take-away from a study in the Journal of Personality and Social Psychology.Researchers tested violent and nonviolent variations of a custom-designed game on 600 players. They found that poorly designed or overly difficult games left participants as enraged, if not more so, than violent games did.Violent games have long been blamed for subsequentviolent behavior in players. And some research finds that long-term play changes regions in the brain associated with cognitive function and emotional control. Additional studies say such games increase aggression in children. But other investigators say the games actually have a calming effect on players, especially those with a preexisting mental health condition.All those research efforts may need to be re-examined in light of the new finding. In other words, don't hate the game, hate the player. Or at least his lack of skills.Thanks for the minute for the Scientific American 60 Seconds Tech, I'm Larry Greenemeier.科学美国人60秒中文翻译：这里是科学美国人60秒科技频道，我是拉里·格林梅耶。
2019年托福听力科学美国人60秒：进入太空心脏形状改变
2019年托福听力科学美国人60秒：进入太空心脏形状改变科学美国人60秒英文文本This is Scientific American 60 Secomds, Space. I'm Sophie Bushwick, got a minute?When astronauts float weightless in space, their muscles don't need to work as hard as on Earth. Muscles therefore atrophy during a long mission, which can cause trouble when space travelers return home. But what happens to that most vital of muscles, the heart?To find out, 12 astronauts learned how to do ultrasound scans of their hearts. Then they recorded the organ's shape before, during and after a stint on the International Space Station. The scans showed that while in microgravity the astronauts' hearts deformed into more spherical shapes. Back on Earth, they stretched back into their usual elongated forms. The work was presented at the annual scientific session of the American College of Cardiology.心脏.jpgKnowing how weightlessness changes the heart could help mission planners prevent long-term damage toastronauts'cardiovascular systems due to long space voyages. Astronauts on the space station already perform specific exercises to keep their weight-bearing muscles toned. Similarly well-designed workouts might keep hearts both in shape—and in the right shape.Thanks for the minute for Scientific American 60 Secomds, Tech. I'm Sophie Bushwick.科学美国人60秒中文翻译：这里是科学美国人60秒，太空系列。
2019年托福听力科学美国人60秒：秘密监视活动
2019年托福听力科学美国人60秒：秘密监视活动科学美国人60秒英文文本One of the year's biggest stories was the revelation of widespread surveillance by the government.We learned about the NSA's efforts to weaken cryptography standards, eavesdrop on electronic communications and gather billions of cell phone records.Then came news that what seemed like an urban legend is actually true：政府监听活动.jpgthe FBI can remotely activate a computer's digital camera to spy on the user—without turning on the light that indicates the camera is live.That news comes courtesy of court documents unearthed by The Washington Post.The FBI says they use this not-at-all-hidden camera trick to find transient terrorists.The use of webcams for spying comes as no shock to anyone who followed the 2010 case of a school district in suburban Philadelphia that was busted for using school-issued laptops to watch students at home.Yes, lawsuits are underway.So what happens now that everyone knows what the government's been doing?Will 2014 see attempts to curb data collection?Or have people grown comfortable with the demise of privacy?。
2019年托福听力科学美国人60秒：接受教育越多收入越多
2019年托福听力科学美国人60秒：接受教育越多收入越多科学美国人60秒英文文本This is Scientific American — 60-Second Science. I'mErika Beras.Got a minute?Turns out, education pays off. That's true whether you're a doctor or a lawyer—or even a mobster, according to a new study.Researchers compared the FBI files of more than seven hundred Italian-American mafia men from the '30's to the'40's to other nonmob men from the 1940 census—some were neighbors, others were first and second generation Italian-American immigrants and some were U.S. born white men.They found that mobsters tended to have a year less schooling than their neighbors—but for those who stayed in school a little longer, they tended to do better economically. More education increased their income—or moolah—by about 8 percent, on average.The Study is the Economics of Education Review.教育和收入.jpgOf course, this shouldn't be surprising. The mafia is essentially a corporation, involving complex organizational and numerical expertise. Weighing grams and running numbers takes more than basic math skills. And researchers found themobsters with the highest return were the ones involved with more complicated schemes—think embezzling, racketeering and loan sharking. Their profit was about three times higher than the mobsters involved with criminal activity like robberies.So study up! No matter what you plan to do, seems like the more you study, the bigger the payoff. Even if you ain't nothing but a wiseguy.Thanks for the minute for Scientific American — 60-Second Science Science. I'm Erika Beras.。
2017年托福听力科学美国人60秒：火星探测器出现液态水
科学美国⼈60秒中英⽂翻译：⽕星探测器出现液态⽔ This is Scientific American 60 Secomds, Space. I'm Clara Moskowitz, got a minute? If Martians exist, even the microbial sort, they probably need liquid water. Temperatures on the surface of the red planet are below freezing, but signs exist that water flowed in the past—and perhaps still does, thanks to a Martian version of anti-freeze. Salts lower the freezing point of water, as anyone knows who's thrown salt on an icy sidewalk. And both NASA's Phoenix and Curiosity missions found salts called perchlorates sprinkled around the Martian surface. To see how perchlorates might act on Mars, researchers recreated the pressure, humidity and temperature of the planet inside a metal cylinder. They put a thin layer of perchlorates on top of water ice inside the chamber. Within minutes, droplets of liquid water formed, even at minus 100 degrees Fahrenheit. Some scientists thought perchlorates might condense water vapor from the atmosphere. But within the cylinder, no liquid water formed in the presence of salts, either alone or on Mars-like soil, unless ice was present too. The study is in the journal Geophysical Research Letters. The finding study could explain mysterious globules seen on the leg of the Phoenix in 2008. The lander may have been dotted with drops of otherworldly water. Thanks for the minute for Scientific American 60 Secomds, Tech. I'm Clara Moskowitz. 科学美国⼈60秒中⽂翻译： 这⾥是科学美国⼈60秒，太空系列。
2019年托福听力科学美国人60秒：水獭的公厕社交
2019年托福听力科学美国人60秒：水獭的公厕社交科学美国人60秒英文文本This is Scientific American — 60-Second Science. I'm Jason Goldman.Got a minute?River otters, like other social animals, have tocarefully weigh the costs and benefits of hanging out in large groups. A big group makes it easier to catch fish, which seems like a good deal, but there's a downside tosocial life too. More otters means more chances for disease transmission, for example, or for aggressive conflict. So they balance these pressures by living in what researchers call a "fission-fusion society.""There's this constant dynamic of splitting and joining into larger groups."University of Wyoming ecologist Adi Barocas. To understand the factors that drive these social dynamics, Barocas's team, from the University of Wyoming and the Alaska Department of Fish & Game, has spent decades spying on the coastal river otters of Alaska near Prince William Sound. To do it, they use motion-activated camera traps as well as implanted radio trackers."The latrines, which are pretty much communal toiletsthat the river otters use, they seem to have an important function in the life of river otters."水獭.jpgThat's right： river otter society is organized aroundthe bathroom. It makes good sense. By investigating a latrine, an otter can sniff out just how many otters there are in the area, and who they might be.The researchers found that the otters performed more signaling behaviors like sniffing, body rubbing, or urinating, than social behaviors, like grooming or play, at what they called crossover latrines, which were located at thejunctions of water bodies.Thanks to all that communicative signaling, these crossover latrines were also more likely to host fusion events, resulting in large aggregations of up to eighteen otters. In other words, the otters see latrines as a place to exchange information, a sort of central marketplace.Because the location of crossover latrines was determined by the physical landscape, this suggests that the complexityof the physical environment plays an important role in determining their social behavior.Next, the researchers want to see just how and what the otters communicate at latrines."We often see the river otters sniffing at the latrines and also defecating, and before defecating they do a little ritualized behavior that we termed 'the poop dance.'"What scents are they trying to sniff out? Which olfactory compounds are at play? Can the otters control the scents they leave behind? Who's watching the poop dance?And most importantly, why doesn't anybody ever rememberto flush?Thanks for the minute for Scientific American — 60-Second Science Science. I'm Jason Goldman.科学美国人60秒中文翻译：This is Scientific American — 60-Second Science. I'm Jason Goldman. 这里是科学美国人——60秒科学。
托福听力科学美国人60秒：黑洞三兄弟
托福考试(TOEFL)/备考辅导2017年托福听力科学美国人60秒：黑洞三兄弟【导语】为了帮助大家高效备考托福，熟悉托福听力，小编为大家带来2017年托福听力科学美国人60秒，希望对大家托福备考有所帮助。
更多精彩尽请关注小编！科学美国人60秒中英文翻译：黑洞三兄弟科学美国人60秒英文文本This is Scientific American 60 Secomds, Space. I'm Clara Moskowitz, got a minute?Inside most galaxies a supermassive black hole lurks. But one galaxy about 4 billion light-years from us was recently discovered to have not one, not even two, but three gigantic black holes at its center.Such triple systems appear to be extremely rare—only four are known. The newfound system includes two black holes orbiting each other very closely, about 450 light-years apart, with a third black hole a bit farther out. The central pair zoomaround each other at a fast clip, about 300 times the speed of sound on Earth. The hole trinity also represents the tightest trio of black holes known to date. It's described in thejournal Nature.As these objects continue to orbit at the center of their galaxy, gravity will eventuallypull them closerand closer together. Ultimately, they may even merge. Researchers hope this triple-black-hole system may be a good place to look for space-time ripples called gravitational waves. As their orbits shrink, the black holes should radiate away some of their orbital energy as the sought-after gravitational waves, predicted by Einstein a century ago.Thanks for the minute for Scientific American 60 Secomds, Tech. I'm Clara Moskowitz.2017年托福听力科学美国人60秒：黑洞三兄弟.doc [全文共767字] 编号：8535578。
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Are you one of those people who can tell when a storm is approaching based on your achy knees? Well, you may think you are. But a new study of more than 1.5 million seniors finds no relationship between rainfall and doctor visits for pain. The results are in the British Medical Journal. [Anupam B. Jena et al., Association between rainfall and diagnoses of joint or back pain: retrospective claims analysis]
The idea that our bodies are barometers for all sorts of
weather-related phenomena—including changes in temperature, pressure and precipitation—is not a new one.
“Hippocrates himself actually postulated this idea in nearly 400 B.C.” Anupam Jena, a physician and expert in health care policy at Harvard Medical School and the Massachusetts General Hospital, who led the study.
“If you talk to people, I’d say millions and millions of people probably believe that things like rainfall influence symptoms of joint pain and stiffness. But if you look at the studies, there’s actually been surprisingly little evidence to suggest that is true. Most of the studies have been quite small. And we were interested in thinking about whether we could approach this question in a ‘big data’ sort of way.”He and his colleagues looked at information collected in more than 11 million visits that older Americans made to their primary care physicians. They compared these records with data on daily rainfall. And they asked: do more people report sore backs or swollen joints when the weather is inclement?
“And what we found is if you look at days where it rained versus days where it didn’t rain, there is no difference in the proportion of visits to a doctor that involved a complaint of joint pain or back pain.”They saw no “rain effect” even when it poured for seven days straight. And if you’re thinking, well, what if people couldn’t get an appointment until the skies cleared up…
“And if you look the week after a period of heavy rainfall, you still see no relationship. And that doesn’t mean that factors lik e rainfall or temperature or humidity don’t affect joint pain and symptoms of joint achiness and stiffness. But in this sort of big data approach, we didn’t find any evidence for it.”
Of course, it could still be that the pain from rain is not enough to
co mplain. “It could be that patients take over-the-counter pain medications once these symptoms hit, and so when they see their doctor they’re not actually in enough pain to mention it.” And the casualties of low-pressure fronts simply move on—gingerly. —Karen Hopkin
[The above text is a transcript of this podcast.]。