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周一的科技文来鸟~~
time2，3为一篇文章，time4，5为一篇文章，time6，time7各为一篇
主题比较杂一点，但是难度和长度都不是很大~ 希望大家耐心读完
上作业啦！！`(*∩_∩*)′
Part I：Speaker
[Rephrase 1]
We Probably Won't Recycle Shredded Paper
[Dialog, 1:25]
MP3：
[transcript hided]
If something looks like trash you are more likely to trash it. Even if it has value—such as recyclable items like aluminum cans or torn paper. That’s according to a study in the Journal of Consumer Research. Volunteers were asked to evaluate a pair of scissors. Some were told to cut up sheets of paper. The others were instructed to examine the scissors but to leave their sheets of paper alone, uncut and intact. All of the participants were asked to discard the paper as they left the room. At the exit sat two identical trash bins, one labeled for recycling, the other for trash. And the people who shredded the paper were less likely to toss it in the recycling bin than those who were left holding the pristine sheets. In another experiment, participants were less likely to recycle aluminum cans that were crumpled than empty cans still in good shape. More than two billion tons of trash gets tossed away every year around the globe. Figuring out how people think about what they’re going to discard should help the effort to squeeze more use out of less stuff. http://www.scientificamerican.com/podcast/episode.cfm?id=we-probably-wont-recycle-shredded-p-13-09-03
Part II：Speed
Bacteria from lean cage-mates help mice stay slim
But microbes are only part of the story — the effect also depends on a healthy diet.
【Time2】
Gut bacteria from lean mice can invade the guts of obesity-prone cage-mates and help their new hosts to fight weight gain.
Researchers led by Jeffrey Gordon, a biologist at Washington University in St. Louis, Missouri, set out to find direct evidence that gut bacteria have a role in obesity.
The team took gut bacteria from four sets of human twins in which one of each pair was lean and one was obese, and introduced the microbes into mice bred to be germ-free. Mice given bacteria from a lean twin stayed slim, whereas those given bacteria from an obese twin quickly gained weight, even though all the mice ate about the same amount of food.
The team wondered whether the gut microbiota of either group of mice would be influenced by mice with one type living in close quarters with animals harbouring the other type.
So the scientists took mice with the ‘lean’ microbiota and placed them in a cage with mice with the ‘obese’ type before those mice had a chance to start putting on weight.
“We knew the mice would readily exchange their microbes,” Gordon says — that is, eat each other’s faeces. Sure enough, the populations of bacteria in the obese-type mice changed to match those of their lean cage-mates, and their bodies remained lean, the team writes today in Science1.
The bacterial invasion travelled only in that direction, however: the bacteria of the obese mice could not colonize the lean neighbour. This makes sense, says Gordon, who found in earlier work that the population of gut bacteria in obese people is less diverse than that in lean people2, leaving unfilled niches in the microbiota. The bacteria from the lean mice seem to be able to find those vacancies, he says.
(words：292)
【Time3】
'The right ingredients'
But this left him wondering: if the bacteria of lean people are so good at setting up shop in the guts of the obese, “why don’t we have an epidemic of leanness in America?”
So the team fed the mice a more human diet, turning foods such as breakfast cereal and pizza into pellets for the mice. When the animals were fed a diet low in saturated fat and high in fruit and vegetables, the transfer of gut microbes from mice with the lean type to those with the obese type still occurred; however, when the mice were given a high-fat, low-vegetable diet this did not happen, and mice with the obese-type bacteria gained weight. “There’s an intricate relationship between our diet and how our gut bugs work,” says Gordon. “You have to have the right ingredients.”
Patrice Cani, who studies the interaction between gut bacteria and metabolism at the Catholic University of Leuven in Belgium, is impressed that the authors of the study were able to demonstrate causality between gut microbiota and a physical feature such as body type. And he says there is much more to be learned about the interaction of gut bacteria and diet from the work. “This paper is like a bank of information,” he says. “We can keep going back for a deeper look.”
Gordon agrees. “It’s a complex puzzle with many interesting parts,” he says. “The microbiota is just one piece.”
（word：241）
http://www.nature.com/news/bacteria-from-lean-cage-mates-help-mice-stay-slim-1.13693
Underwater volcano is Earth's biggest
Tamu Massif rivals the size of Olympus Mons on Mars.
【Time4】
Geophysicists have discovered what they say is the largest single volcano on Earth, a 650-kilometre-wide beast the size of the British Isles lurking beneath the waters of the northwest Pacific Ocean.
The megavolcano has been inactive for some 140 million years. But its very existence will help geophysicists to set limits on how much magma can be stored in Earth's crust and pour out onto the surface. It also shows that Earth can produce volcanoes on par with Olympus Mons on Mars, which, at 625 kilometres across, was until now the biggest volcano known in the Solar System.
“This says that here on Earth we have analogous volcanoes to the big ones we find on Mars,” says William Sager, a marine geologist at the University of Houston in Texas. “I’m not sure anybody would have guessed that.” Sager and his colleagues describe the structure, named Tamu Massif, inNature Geoscience on 8 September1. ‘Tamu’ is an acronym for Texas A&M University in College Station, where Sager was formerly employed.
Tamu Massif has been long known as one of three large mountains that make up an underwater range called the Shatsky Rise. The rise, about 1,500 kilometres east of Japan, formed near a junction where three plates of Earth’s crust once pulled apart.
(words:211)
【Time5】
Shallow rock cores from Tamu had previously revealed that it was made of lava. But geologists thought that the mountain, which rises 4 kilometres from the sea floor, might have built up from several volcanoes erupting such that their lava merged into one pile. The islands of Hawaii and Iceland were built this way.
Sager and his colleagues were startled by findings they made after sailing the research vesselMarcus G. Langseth over Tamu in 2010 and 2012. They used air guns to send seismic waves through the mountain, and monitored the reflections. The seismic waves penetrated several kilometres into the massif — and showed that all of its lava flows dipped away from the volcano’s summit, implying a central magma vent. “From whatever angle you look at it, the lava flows appear to come from the centre of this thing,” says Sager.
Scott Bryan, a geologist at the Queensland University of Technology in Brisbane, Australia, warns that not all of Tamu may have come from a single magma vent. There could be separate sources, deeper than the seismic waves penetrated, that could have oozed out lava and inflated the mountain from below, he says.
Because ship time is at a premium, the study is one of the first to peer at the internal geometry of these massive underwater mountains. It is possible that other megavolcanoes are waiting to be discovered. “There may be bigger ones out there,” says Sager.
(words:238)
http://www.nature.com/news/underwater-volcano-is-earth-s-biggest-1.13680
Device offers promise of no brain tumor left behind
【Time6】
A tiny probe equipped with a laser might reveal what the human eye doesn’t always see: the difference between a tumor and healthy tissue. A new study suggests the device might provide brain surgeons with a roadmap as they go about the delicate business of removing tumors.
Surgeons try to excise as much of brain tumors as possible, but they risk harming the patient if they remove healthy tissue. “This problem,” says surgeon Daniel Orringer of the University of Michigan in Ann Arbor, “has vexed brain surgeons for as long as they have taken out tumors,” since the first half of the 20th century. “Basically, we do it by feel — the texture, color and vascularity of the tissues. Tumors tend to bleed a little more than normal brain.”
Although removing and testing tissue samples, or biopsies, can help to characterize the tissue at the tumor margins, it’s a cumbersome and time-consuming process. In the new study, Orringer and his colleagues instead exposed such borderline brain tissues to a weak laser. Then they used Raman spectroscopy, a technique that reveals vibrations of specific chemical bonds in tissues. The revved up form of Raman spectroscopy that the researchers used is sensitive enough to distinguish between proteins and lipids. Since tumors are higher in protein than healthy brain tissue, the authors designed the technique to present protein signatures as blue images on a screen, and lipids as green.
Using the device as a probe, the researchers examined human brain tumor cells that had been implanted in live mice. The device could distinguish where the new tumor ended and healthy tissue began. A separate analysis of tissue that had recently been removed from a human brain cancer patient similarly revealed stark differences between the tumor and normal tissue. The findings appear in the Sept. 4 Science Translational Medicine.
The study offers “a very exciting advance,” says chemist Ji-Xin Cheng of Purdue University in West Lafayette, Ind.. The research establishes that visualization of the tumor margin using Raman spectroscopy is possible in a living animal, he says.
In patients, this could streamline surgery, says study coauthor Sunney Xie, a physical chemist at Harvard University whose team developed the new imaging technology. “We don’t need a biopsy,” he says. “You can do it in real time.”
Xie and Orringer estimate it could take five years or more of testing to get regulatory approval to use the technique with patients.
（words:403）
http://www.sciencenews.org/view/generic/id/353010/description/Device_offers_promise_of_no_brain_tumor_left_behind
Part III： Obstacle
How Window Glass Is Getting Smarter
A material that selectively blocks heat and light could finally make it practical to add smart windows to buildings.
【Time7】
Heliotrope Technologies, an early-stage startup currently incubating at Lawrence Berkeley National Laboratory, may have found the key to delivering the first cost-effective “smart window.” The company has developed a relatively inexpensive glass composite with the unprecedented capacity to selectively block the sun’s heat-producing infrared radiation as well as visible light. Buildings equipped with such glass could be more energy-efficient.
The company recently announced that it would begin sending samples to large glass manufacturers to “evaluate its potential for commercial and residential buildings.” It aims to produce its first product within three years.
Many experts see the emerging technology of “smart” or “dynamic” windows—which use glass whose transmittance of solar radiation can be changed on demand by applying heat (thermochromic), light (photochromic), or electricity (electrochromic)—as a promising way to curb the consumption of energy for cooling and lighting buildings. The National Renewable Energy Laboratory has estimated that widespread use of the technology could decrease energy use in the U.S. by about 5 percent. The market for smart glass remains minuscule, however, and is mostly confined to niche applications like tintable rearview mirrors in cars. Demand for smart windows is low because the upfront costs are prohibitively high for most potential buyers.
Two companies, View and Sage Electrochromics, have taken the lead in the fledgling industry. The latter was recently acquired by major glass manufacturer, Saint-Gobain. But the first-generation products these companies are making mainly modulate visible light, and any small variation in their ability to block infrared (IR) radiation can only occur at the same time that visible light is also blocked, says Delia Milliron, a Heliotrope cofounder, the company’s chief scientific officer, and staff scientist at LBNL. “There’s no separation as a function of voltage that we have in our materials.”
Milliron’s group at LBNL published a paper last month in Nature in which it described a new glass composite material that can be reversibly tinted and can block infrared radiation while remaining transparent—the first demonstration of glass that allowed for independent control over the transmittance of visible light and IR radiation. The new material can switch between three modes, in fact—fully transparent, transparent but blocking IR radiation, and blocking of both visible and IR radiation—according to the amount of applied voltage. And once the glass has switched, it is no longer necessary to run current through it.
An electrochromic window essentially works like a transparent rechargeable battery. Two pieces of conducting glass sandwich an electrolyte material, and changes in transmittance of the glass occur in response to electrochemical charging and discharging.
In the design demonstrated by Milliron’s group, the new composite, made of indium tin oxide nanocrystals embedded in niobium oxide glass, is deposited on one side and serves as an electrode; another electrode is placed on the opposite side of the electrolyte. Applying a moderate voltage causes the nanocrystals to become electronically charged, which in turn causes IR radiation to be absorbed and blocked. Applying a somewhat larger voltage causes the niobium oxide glass to become electrochemically reduced, which results in tinting. Finally, another modest voltage makes the glass switch back to fully transparent.
While Heliotrope isn’t using the exact materials employed in Milliron’s published research, the company’s proprietary compositions are “similar” to those her group has demonstrated, says cofounder and president Jason Holt.
The powerful new functionality of Heliotrope’s material is not even its most important distinguishing feature, at least in the near term, according to Holt. “I think what’s really going to expand the market for smart windows is a product that’s much cheaper than what’s out there.”
The products that View and Sage are making are about twice as expensive per square foot to the end-user compared to a typical static, double-paned window, he says. Since Heliotrope’s material can be made using relatively low-cost solution deposition techniques, and doesn’t require the more expensive vacuum deposition techniques generally used to make electrochromics, Holt believes the company can eventually make products with prices more in line with those of the standard double-paned windows. “That’s where you need to be if you want to start looking at these as energy-efficiency products, and subjecting them to energy payback metrics and stuff like that.”
Current smart glass products are so expensive, and the payback period for them is so long, that “buying smart glass purely on the basis of its energy efficiency is not something that’s really happening today,” says Eric Bloom, a senior analyst at Navigant Research who recently authored a report focused on the smart glass market. In fact, for the next few years, as Sage and View ramp up their manufacturing capacity, the market will likely be driven mostly by buyers who can afford to buy smart glass simply because “it’s cool,” says Bloom. Costs are coming down, though, and from an energy savings perspective, he says, “the business case for smart glass will look a lot more compelling in about five years.”
For now, Heliotrope will focus on adapting its fabrication technology to make prototypes measured in square feet instead of square inches. If all goes as planned, says Holt, the company will be making “small form factor” devices, perhaps as large as a skylight window, within about two and a half years.
(words:872)
http://www.technologyreview.com/news/518821/how-window-glass-is-getting-smarter/
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发表于 2013-9-10 00:58:42
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