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大家好!胖胖翔来了!欢迎周一发科技文的“捉妖”和我一起来和大家分享科技文章！Just enjoy!
Part I：Speaker 【Rephrase1】 Article 1 Smartphone Security Could Be Based on User Behavior With implicit identification, aka implicit authentication, your smartphone would shut down after recognizing it was lost or stolen based on how the new user was fiddling with its functions. Larry Greenemeier reports Transcript hided [Dialog, 1:15]
Apple’s new Touch ID biometric fingerprint sensor has people thinking about new ways to secure their smartphones. One approach in the works is “implicit identification,” sometimes called “implicit authentication.” Instead of a password or fingerprint, your phone would recognize you by your behavior. According to an article on the global business news outlet Quartz, researchers at the Palo Alto Research Center, U.C. Davis, Carnegie Mellon and elsewhere are investigating implicit identification for mobile gadgets. Such systems would ID you based on where you go measured by the phone’s GPS, apps you use and Web sites you visit. Add phone call, text and e-mail patterns to the mix as well. Implicit ID could even factor in your typing skills to verify your identity. Of course, none of this keeps your phone from being stolen. And a thief might be able to access some of your info before your phone figures out what’s happened and hits the kill switch. Implicit authentication likely won’t banish passwords. But it could be used alongside them to help your smartphone cover your digital assets if they fall into the wrong hands. —Larry Greenemeier Source: http://www.scientificamerican.com/podcast/episode.cfm?id=smartphone-security-could-be-based-13-09-26
Part II：Speed 【Time 2】 Article 2 The Most Common Tree in the Amazon
The Amazon remains a mystery to botanists, who haven't known how many kinds of trees live in the extremely diverse forests or even what species is most common. Turns out, it's a slender palm called Euterpe precatoria. After counting up tree species from 1170 research sites studied by hundreds of scientists, a team extrapolated the number likely to exist across the entire region. They estimate that Amazonia has about 16,000 species of trees (although they admit the statistical model has some problems, such as not accounting for environmental preferences of various species). Remarkably, half of all the trees belong to only 227 species that dominate in various regions, probably because they resist diseases and herbivores, such as insects. Others may have been planted by humans before Europeans arrived. Many species—11,000—are extremely rare, accounting for a mere 0.12% of trees. Half of these are probably rare enough to be considered globally threatened and may go extinct before they are discovered.
字数[161] Source: http://news.sciencemag.org/latin-america/2013/10/scienceshot-most-common-tree-amazon
【Time 3】
Article 3
Armageddon 2
Want to know if that meteor that just struck Earth has a companion? Take a look at its trail. A new study shows that images of a meteor’s streak through the atmosphere taken by Earth-gazing probes, including weather satellites, can pin down the object’s orbit, enabling scientists to check and see whether another planet-threatening object is traveling in the same trajectory. The finding comes thanks to the almost-20-meter-wide meteoroid that blazed into Earth’s atmosphere in February and exploded over Chelyabinsk, Russia, damaging buildings there and injuring hundreds. Soon after it streaked over the country (main image)—in some cases, mere minutes later—a number of satellites snapped views of the trail from on high (example, inset). Analyses of those images enabled researchers to confirm the trail’s location, height, and orientation, which in turn allowed them to determine the orbit that the object had been following before it slammed into the atmosphere. The orbit estimated using satellite data alone reasonably matched the one estimated via ground-based videos, the team reports online today in the Proceedings of the National Academy of Sciences. In situations where objects enter Earth’s atmosphere in more remote locations—over the ocean far from land, for example—satellites may be the only sources of data that could be used to determine an object’s orbit. The threat to our planet from an object’s orbital companions isn’t merely an abstract concern, the researchers contend: One recent study suggests that about 15% of the asteroids that cross Earth’s path may be part of double or triple asteroid systems.
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Source: http://news.sciencemag.org/space/2013/10/scienceshot-armageddon-2
【Time 4】
Article 4
Fields of gold Research on transgenic crops must be done outside industry if it is to fulfil its early promise.
It was 30 years ago this month that scientists first published the news that they could place functional foreign genes into plant cells. The feat promised to launch an exciting phase in biotechnology, in which desired traits and abilities could be coaxed into plants used for food, fibres and even fuel. Genetically modified (GM) crops promised to make life easier and nature’s bounty even more desirable.
As a series of articles in this week’s Nature explores, things have not worked out that way (see page 21). The future matters more than the past, but when it comes to GM crops, the past is instructive.
Soon after the 1983 breakthrough, biotechnology companies developing GM crops became hugely attractive to investors. Calgene in Davis, California, for example, developed the Flavr Savr tomato — engineered to remain firm after ripening — which captured attention, especially when the iconic Campbell Soup Company invested in its development. Like many at the time, Campbell’s was fascinated by the promise that tomatoes could be ripened on the vine to accentuate their flavour and still make the trip to the supermarket and the dinner table without turning to mush.
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【Time 5】
In early 1992, analysts predicted regulatory approval for the GM tomato within a month, and a market of at least US$500 million a year. But less than a decade after their birth, GM crops were already facing a difficult adolescence. What was once deemed biological wizardry was increasingly being labelled Frankenfood. Consumers in Europe were bristling at the aggressive marketing of GM giant Monsanto, based in St Louis, Missouri. The Flavr Savr suffered more than a year of delays at the US Food and Drug Administration, and Campbell’s began to state that it had no intention of putting the tomatoes in its soups without approval from the public. What had gone wrong? According to one analyst quoted at the time, the biotech sector had failed to prepare consumers appropriately: “Now, they realize that they have to be articulate and educate an uninformed public.”
The Flavr Savr was approved in 1994 but never took off commercially. In the meantime, the biotech industry had shifted much of its attention to traits that aimed not to delight consumers, but rather to increase farm yields. Herbicide-tolerant and pest-resistant crops proliferated in the United States and more than two dozen other countries. GM organisms were to become agricultural tools.
In many places where they are planted, these GM crops have replaced conventional planting almost entirely. Yields and profits have increased, farmers have been generally happy to adopt the transgenic seeds and the technology has even made good on some of its promises to help the environment by reducing the amount and variety of pesticides needed.
GM crops, of course, still face a public-relations problem. Fears of the unfamiliar and ‘unnatural’, and concerns about health or environmental impacts, have frequently prevented approval and adoption of the crops, especially in Europe, where protesters have destroyed experiments. The United States, the world’s most active user of GM crops, has seen renewed backlash as calls grow for foods with GM ingredients to be clearly labelled.
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【Time 6】
The analyst who spoke of an uninformed public may have been correct in 1993, but such a claim no longer applies. People are positively swimming in information about GM technologies. Much of it is wrong — on both sides of the debate. But a lot of this incorrect information is sophisticated, backed by legitimate-sounding research and written with certitude. (With GM crops, a good gauge of a statement’s fallacy is the conviction with which it is delivered.)
Armed with misinformation, debaters have taken to the streets, the supermarkets and social media. With a topic as sensitive and dear to people as the food they eat and give to their children, those who play to the fears, concerns and uncertainty surrounding GM crops often seem to have the upper hand. And the fears are entwined with mistrust of the seed companies. Supporting GM crops can seem a thankless job: it is worthwhile to stand up for good science and the promise that it holds, but defending profit-hungry corporations feels less rewarding.
Still, there is reason to stand up for the continued use and develop ment of GM crops. Genetic modification is a nascent technology for which development has moved very quickly to commercialization. That has forced most research into the for-profit sector. Without broader research programmes outside the seed industry, developments will continue to be profit-driven, limiting the chance for many of the advances that were promised 30 years ago — such as feeding the planet’s burgeoning population sustainably, reducing the environmental footprint of farming and delivering products that amaze and delight. Transgenic technologies are by no means the only way to achieve these aims, but the speed and precision that they offer over traditional breeding techniques made them indispensable 30 years ago. They still are today.
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Source: http://www.nature.com/news/fields-of-gold-1.12897 Part III： Obstacle
【Paraphase7】
Article 5
Hot News: Fusion Researchers Recommend ITER Design Tweaks
Researchers are recommending that this key part of ITER, an exhaust system known as the divertor that must withstand high temperatures, be coated with tungsten instead of carbon.
Scientific advisers to the ITER fusion reactor project have recommended several key changes to its design that could increase technical risks—but also smooth the path to producing excess energy. The recommendations, made last week by ITER’s Science and Technology Advisory Committee (STAC), will have to be approved by the full ITER council in November. But if approved, as expected, “the chance of surprises later is reduced,” says Alberto Loarte, head of ITER’s confinement and modeling section. “The risk will pay off.”
ITER, being built in France by an international collaboration, aims to show that nuclear fusion, the reaction that powers the sun, can be controlled on earth to produce energy. But reaching that goal involves heating hydrogen gas to more than 150 million°C so that hydrogen nuclei slam together with enough force to fuse. To do this, researchers are building a huge doughnut-shaped container called a tokamak to confine the ionized gas—or plasma—using enormously strong magnetic fields. ITER’s goal is to coax the plasma to produce 500 megawatts (MW) of heat, 10 times the 50 MW of power required to heat the plasma; this multiplying effect is known as a gain of 10.
The most significant change decided at the STAC meeting concerns a structure at the base of the tokamak vessel called the divertor. Its main function is to remove the helium that is the “exhaust” gas of the fusion reaction. The divertor is the only part of the vessel where the superhot plasma actually touches a solid surface, so it has to be able to absorb huge quantities of heat, as much as 10 MW per square meter of surface.
Existing plans call for making ITER’s first divertor with an outer layer of carbon. This is the safe option: Carbon is well proven in tokamak interiors; it can easily withstand the temperatures; and if any is blasted off into the plasma, it doesn’t affect the performance very much. The problem with carbon, however, is that it happily reacts with hydrogen, binding atoms into its structure. This wouldn’t be a problem during the early phases of ITER operation when researchers plan to use simple hydrogen or helium in the machine to get the hang of how it works. But a carbon coating could be a huge problem in later phases, when researchers plan to switch to real fusion fuel—a more reactive mixture of the hydrogen isotopes deuterium and tritium. Tritium is radioactive and so needs to be carefully controlled and accounted for. Nuclear regulators would never accept a divertor material that absorbs tritium and so makes it impossible to locate.
To address that problem, planners had proposed running ITER for several years with the carbon-coated divertor, and then switching to one made of tungsten. Tungsten has the highest melting point of any metal: 3422°C. That should be fine for withstanding the heat produced during normal, steady ITER operations. But any unexpected bursts of heat could potentially melt the divertor, and tungsten—unlike carbon—instantly poisons the plasma, bringing fusion to a halt. So ITER’s operators would have to run the reactor much more carefully with a tungsten divertor, not pushing it to limits where the plasma might become unstable.
Despite this drawback of tungsten, STAC has recommended that ITER be built with a tungsten divertor from the start. “It was not an easy decision,” says STAC Chair Joaquín Sánchez, head of Spain’s National Fusion Laboratory in Madrid. The decision was made after years of research at other tokamak laboratories, in particular the Joint European Torus (JET) at Culham in the United Kingdom, which is the closest machine to ITER in size and design. Several years ago, JET researchers refitted the reactor with a tungsten divertor and beryllium lining (as ITER will have). After a year of testing, they confirmed that this “ITER-like wall” worked well enough not to cause problems for ITER.
Although some fusion researchers think that it would be safer to start ITER with a well understood carbon divertor, allowing them to push the reactor to extremes in search of high performance, starting with tungsten has advantages, too. Changing divertors is a complex process that would take many months. In addition, once operation with deuterium-tritium fuel has started, the interior of the vessel becomes radioactive (or “activated”), making it much harder to modify internal components. “If we start with tungsten, we save the cost of the change,” Sánchez says. “We know tungsten will be more difficult, but we will start learning earlier in the nonactivated phase and if there is a problem we can send people inside to fix it.”
The other design changes concern two separate magnetic coils to be inserted inside the reactor vessel to fine-tune control of the plasma. ITER’s main plasma-confining magnets are outside the vessel and act as something of a blunt instrument. About 5 years ago, researchers highlighted the fact that operators would have difficulty keeping the vertical position of the plasma steady, and so proposed some extra magnetic coils on the inside.
In addition to those for vertical stability, researchers proposed installing a second set of internal coils to combat a troubling phenomenon in superhot fusion plasma called edge-localized modes, or ELMs. ELMs occur when energy builds up in the plasma during fusion and then bursts out of the edge unpredictably, potentially damaging the lining or the divertor. The second set of coils deploys a magnetic field to roughen up the surface of the plasma so that it leaks energy at a constant rate rather than in erratic bursts.
Anything inside the vessel is subjected to extreme heat, radioactivity, and magnetic forces, so researchers had to persuade STAC that these two sets of coils could be made resilient enough to survive. “There was some reluctance in STAC and the ITER Organization because of the technical issues of installation,” Loarte says. Experiments at other labs around the world reassured them. “The results obtained were very positive,” he says.
STAC also took a hard look at the delivery schedule of components for ITER. The original plan called for everything—heating systems, instruments, ELM mitigation—to be in place when ITER is completed in 2020. But delays have meant that some items will be arriving later. “We needed to redo the schedule with a logic consistent with [achieving deuterium-tritium operation] faster. It was not consistent before and that led to criticism,” Loarte says. “Now we have to do the organizational part, which is not simple.”
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Source: http://news.sciencemag.org/europe/2013/10/hot-news-fusion-researchers-recommend-iter-design-tweaks?rss=1 | 
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发表于 2013-10-22 20:12:26
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谢谢PPX ，不过物理渣昨天今天在这里挣扎了N久。
