【Native Speaker每日综合训练—30系列】【30-16】科技

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大家好!胖胖翔来了! 今天的文章比较广泛，有生物--神经、吃鸟的飞鱼；天文--新发现的星体；考古—失落的文化；科技—网络战。Enjoy~

Part I：Speaker

【Rephrase1】
Article 1
Experimental Tool Uses Light To Tweak The Living Brain

[Dialog, 4: 34]

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Source:
http://www.npr.org/blogs/health/2013/12/26/256881128/experimental-tool-uses-light-to-tweak-the-living-brain

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Part II：Speed

【Time 2】
Article 2
Lasers Unearth Lost 'Agropolis' of New England

Hidden ruins are customary in the wild jungles of South America or on the white shores of the Mediterranean Sea. Now, researchers have uncovered a long-lost culture closer to Western civilization—in New England.

Today, southern New England is shrouded by lush forests, whose autumnal colors attract thousands of tourists and hikers each year. Urban hubs—Boston, Providence, Hartford—are peppered throughout. Rewind the clock 300 years, however, and the landscape would be unrecognizable, with much of the wooded countryside replaced by hundred-acre farms. Agriculture was king in New England until widespread industrialization in the 19th century led farmers to abandon their fields and move to cities. The forest stirred and soon reclaimed the disavowed land, cloaking the structural relics of a vast agrarian past.

In a new study, which will be published in the March issue of the Journal of Archaeological Science, geographers Katharine Johnson and William Ouimet of the University of Connecticut, Storrs, uncovered these preserved sites without ever lifting a shovel. Using aerial surveys created by LiDAR, a laser-guided mapping technique, the team detected the barely perceptible remnants of a former “agropolis” around three rural New England towns.

Near Ashford, Connecticut, a vast network of roads offset by stone walls came to light underneath a canopy of oak and spruce trees. More than half of the town has become reforested since 1870, according to historical documents, exemplifying the extent of the rural flight that marked the late 1800s. Some structures were less than 2 feet high and buried in inaccessible portions of the forest, making them essentially invisible to on-the-ground cartography.

In rural Westport, Massachusetts, modern property boundaries overlapped with weathered stone walls that were unveiled by LiDAR. By examining historic maps from the early 1700s, the team learned these demarcations had barely changed over the centuries.


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【Time 3】


The untold consequences of this agricultural abandonment on the modern ecosystem are another story told by LiDAR archaeology. Invasive plants like Japanese barberry shrubs capitalized on abandoned open fields that were reverting to forests. Native species benefited as well. White pine, an aggressive timber species, gained a foothold in New England in the mid-19th century through the mid-20th century as farms were abandoned, says ecologist David Foster of Harvard University, who was not involved with the work. “The basic fact is the history of a site strongly influences the environmental conditions and the type of vegetation that develops,” he says. “Therefore, it ends up having a legacy of impacts on the vegetation today.”

“This fabulous work opens the eyes of people like me and other researchers,” says Foster, who plans to use LiDAR in his future investigations of forest ancestry in Massachusetts. It shows “that with relatively little effort, you can generate a completely new data set of information about the landscape.”

Discoveries like a dam and the forgotten walls of a once-buzzing sawmill near Tiverton, Rhode Island, will help quantify the impact that English-style agriculture had on the continuity between historic and modern landscapes, Johnson says. Studying vegetation dynamics near the sites could create a living history of the ecosystem, she says, that explains how much earth was moved by farmers or how humans impacted river systems in the past to guide land conservation in the future. She will also help historical societies document new landmarks. Given that some ruins reside on private land, this mapping will preserve a fuller historical picture, in case the land is ever sold and developed, she says.


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Source:
http://news.sciencemag.org/archaeology/2014/01/lasers-unearth-lost-agropolis-new-england


【Time 4】
Article 3
NASA's Kepler Provides Insights On Enigmatic Planets

Jan. 13, 2014 — More than three-quarters of the planet candidates discovered by NASA's Kepler spacecraft have sizes ranging from that of Earth to that of Neptune, which is nearly four times as big as Earth. Such planets dominate the galactic census but are not represented in our own solar system. Astronomers don't know how they form or if they are made of rock, water or gas.

The Kepler team today reports on four years of ground-based follow-up observations targeting Kepler's exoplanet systems at the American Astronomical Society meeting in Washington. These observations confirm the numerous Kepler discoveries are indeed planets and yield mass measurements of these enigmatic worlds that vary between Earth and Neptune in size.

Included in the findings are five new rocky planets ranging in size from 10 to 80 percent larger than Earth. Two of the new rocky worlds, dubbed Kepler-99b and Kepler-406b, are both 40 percent larger in size than Earth and have a density similar to lead. The planets orbit their host stars in less than five and three days respectively, making these worlds too hot for life as we know it.

A major component of these follow-up observations was Doppler measurements of the planets' host stars. The team measured the reflex wobble of the host star, caused by the gravitational tug on the star exerted by the orbiting planet. That measured wobble reveals the mass of the planet: the higher the mass of the planet, the greater the gravitational tug on the star and hence the greater the wobble.

"This marvelous avalanche of information about the mini-Neptune planets is telling us about their core-envelope structure, not unlike a peach with its pit and fruit," said Geoff Marcy, professor of astronomy at the University of California, Berkeley, who led the summary analysis of the high-precision Doppler study. "We now face daunting questions about how these enigmas formed and why our solar system is devoid of the most populous residents in the galaxy."


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【Time 5】


Using one of the world's largest ground-based telescopes at the W. M. Keck Observatory in Hawaii, scientists confirmed 41 of the exoplanets discovered by Kepler and determined the masses of 16. With the mass and diameter in hand, scientists could immediately determine the density of the planets, characterizing them as rocky or gaseous, or mixtures of the two.

The density measurements dictate the possible chemical composition of these strange, but ubiquitous planets. The density measurements suggest that the planets smaller than Neptune -- or mini-Neptunes -- have a rocky core but the proportions of hydrogen, helium and hydrogen-rich molecules in the envelope surrounding that core vary dramatically, with some having no envelope at all.

The ground-based observation research validates 38 new planets, six of which are non-transiting planets only seen in the Doppler data. The paper detailing the research is published in the Astrophysical Journal today.

A complementary technique used to determine mass, and in turn density of a planet, is by measuring the transit timing variations (TTV). Much like the gravitational force of a planet on its star, neighboring planets can tug on one another, causing one planet to accelerate and another planet to decelerate along its orbit.

Ji-Wei Xie of the University of Toronto used TTV to validate 15 pairs of Kepler planets ranging from Earth-sized to a little larger than Neptune. Xie measured masses of the 30 planets, thereby adding to the compendium of planetary characteristics for this new class of planets. The result also was published in the Astrophysical Journal in Dec. 2013.

"Kepler's primary objective is to determine the prevalence of planets of varying sizes and orbits. Of particular interest to the search for life is the prevalence of Earth-sized planets in the habitable zone," said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center in Moffett Field, Calif. "But the question in the back of our minds is: are all planets the size of Earth rocky? Might some be scaled-down versions of icy Neptunes or steamy water worlds? What fraction are recognizable as kin of our rocky, terrestrial globe?"

The dynamical mass measurements produced by Doppler and TTV analyses will help to answer these questions. The results hint that a large fraction of planets smaller than 1.5 times the radius of Earth may be comprised of the silicates, iron, nickel and magnesium that are found in the terrestrial planets here in the solar system.

Armed with this type of information, scientists will be able to turn the fraction of stars harboring Earth-sizes planets into the fraction of stars harboring bona-fide rocky planets. And that's a step closer to finding a habitable environment beyond the solar system.


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Source:
http://www.sciencedaily.com/releases/2014/01/140113130748.htm


【Time 6】
Article 4
Fish leaps to catch birds on the wing
Tigerfish swallows swallows after grabbing them out of the air over African lake.

The waters of the African lake seem calm and peaceful. A few migrant swallows flit near the surface. Suddenly, leaping from the water, a fish grabs one of the famously speedy birds straight out of the air.

“The whole action of jumping and catching the swallow in flight happens so incredibly quickly that after we first saw it, it took all of us a while to really fully comprehend what we had just seen,” says Nico Smit, director of the Unit for Environmental Sciences and Management at North-West University in Potchefstroom, South Africa.

After the images did sink in, he adds, “the first reaction was one of pure joy, because we realized that we were spectators to something really incredible and unique”.

This is the first confirmed record of a freshwater fish preying on birds in flight, the team reports in the Journal of Fish Biology1. Rumours of such behaviour by the African tigerfish (Hydrocynus vittatus), which has been reported as reaching one metre in length, have circulated since the 1940s. But Smit says that his team was “never really convinced by the anecdotal reports”. So, when they set out to study of the migration and habitat use of these animals in a South African lake in the Mapungubwe National Park, near the border with Botswana and Zimbabwe, they were not necessarily looking for fish flying out of the water.

Nevertheless, during their time at the lake, the researchers saw as many as 20 successful fish strikes on barn swallows (Hirundo rustica) every day. These ranged from pursuits by fish at the surface, followed by leaps, to direct attacks from deeper water.

Smit says that this remarkable behaviour has been under the radar until now because the study of freshwater fish in Africa is very limited. “We hope that our findings will really focus the attention on the importance of basic freshwater research, and specifically fish behaviour,” he adds.


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Source:
http://www.nature.com/news/video-fish-leaps-to-catch-birds-on-the-wing-1.14496

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Part III： Obstacle

【Paraphase7】
Article 5
The best time to wage cyberwar
Maths model calculates whether it is worth waiting to hit enemies at their most vulnerable.

If you discover a way to hack into your enemy's computers, do you strike while the iron is hot, or patiently wait for a better opportunity to arise? Wait too long, and a vigilant enemy might spot its vulnerabilities and fix them. Strike too soon, however, and you will have blown your chance to wreak havoc when you might really need it.

A new mathematical model, built on analyses of double-agent spies and code-breaking during the Second World War1, provides a way to calculate the ideal timing of a surprise cyberattack. The work, developed by political scientists Robert Axelrod and Rumen Iliev of the University of Michigan in Ann Arbor, is published this week in Proceedings of the National Academy of Sciences2.

Modern cyberweapons can be sneaky. For example, when the Stuxnet computer worm infected an Iranian nuclear enrichment plant in 2009 and disabled many of its isotope-separation centrifuges, it managed to trick the control room so that the worm went unnoticed for almost a year and a half. The new model suggests that the better your malicious code is at burrowing undetected, “the more readily you can use it, because you won't have to worry as much about losing it — and you may be able to use it again”, Axelrod says. In this instance, unleashing Stuxnet as quickly as possible rather than waiting for a more opportune time was the 'rational' approach.

Sitting ducks
In conventional warfare, most situations are of small consequence (skirmishes without a great loss of life, for example). But a few situations have enormous stakes (large battles with thousands of casualties). If international cyberconflict were to follow the same pattern, then a rational nation should be patient and hold on to its cyberweaponry for those rare occasions when political stakes are high — just as Britain held off acting on information from its double agents until D Day was at hand, Axelrod says.

That does not mean that a country should feel safe when things are quiet: a rational opponent knows that stakes can change quickly and so is probably sitting on its best weapons until the right opportunity arises. Terrorists, by contrast, might want to cause as much damage as they can, and for them, “next month is not that different from this month”, says Axelrod. “They tend to use capabilities as soon as they get them.”

The shelf life of an unused weapon also plays a role in the rational timing of an attack. So-called zero-day cyberattacks rely on security vulnerabilities about which the target is blissfully unaware (thus giving the target “zero days” to prepare for the attack). If a group believes that the cyberweapon in its back pocket will not go obsolete any time soon — because its target is unlikely to patch important vulnerabilities on its own before a bug can sneak in — then it’s most reasonable to save the weapon for a high-stakes situation. Stuxnet, for example, probably had a short shelf life, Axelrod says, because it relied on four different computer vulnerabilities in the nuclear enrichment plant remaining open at the same time, so it was likely deployed as soon as possible.

Short-term gains
The findings therefore have the counter-intuitive implication that cybersecurity can hurt in the short term, something that is “absolutely fascinating”, says John Arquilla, a defence analyst at the Naval Postgraduate School in Monterey, California, who first coined the term cyberwar. If an opponent thinks your vulnerabilities will remain unfixed, they will assume their weapon to have a longer shelf life. “Whereas if we got really, really good at cybersecurity and decided to improve it, and we’re out there discovering vulnerabilities every day, we might actually spark a flurry of attacks upon ourselves,” he says.

Not all cyberexperts agree with Axelrod and Iliev's model. “This focus is too simplistic,” says political scientist Thomas Rid of King’s College London, author of the book Cyber War Will Not Take Place (Hurst, 2013). “The more important policy question, as [a US presidential panel report] recognised last year, is whether using offensive resources is productive in the first place.” The model also ignores other valuable issues, he says, such as what happens when a cyberattack escalates a situation.

Axelrod admits that this model is a first step, and he hopes to expand it to include back-and-forth responses with an opponent, which would bring this work in line with his celebrated game-theory work on a problem known as the prisoner’s dilemma3. He points out that it took from 1945 until 1960 for analysts to develop a viable strategy of nuclear deterrence. “Our aspiration here is that it shouldn’t take 15 years to do the same thing with cyberconflict.”


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Source:
http://www.nature.com/news/the-best-time-to-wage-cyberwar-1.14502

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