上海花千坊爱上海

Climate commotion
In “Changing Climate: 10 years after An Inconvenient Truth” (SN: 4/16/16, p. 22), Thomas Sumner reported on the progress scientists have made revising forecasts of the far-reaching effects of climate change — from extreme temperatures and sea level rise to severe drought and human conflict — in the decade since the Oscar-winning film’s release.

Reader response to the article was overwhelming, with hundreds of online comments. Some people enjoyed the in-depth look at climate change science, while others expressed skepticism about humans’ contribution to climate change and a general distrust of climate scientists.

“One of my goals for this article was to highlight that climate change research has itself changed over the last decade,” Sumner says. Scientists are still working to understand how the consequences of atmospheric warming will play out in the coming centuries. But one big message from the last decade of research is that the fundamentals have held up: Natural variability exists, says Sumner, but human activities are largely responsible for the current warming trend.
“The question now is what impact will human contributions have down the line and what should we do to prevent and mitigate those effects,” he says.
Plastic feast
Sarah Schwartz wrote about the discovery of a microbe, Ideonella sakaiensis, that chows down on a hard-to-degrade polymer in “This microbe makes a meal of plastic” (SN: 4/16/16, p. 5).
Online commenters were amazed by this new plastic-gobbling organism. “This is great news,” Dan said. “Our world would be doomed if there wasn’t a microbe able to do this.” Chuckawobbly wondered how long it takes I. sakaiensis to digest the plastic. And Jean Harlow was concerned about the potential by-products of worldwide plastic digestion. “The waste product would be a significant amount … of what?” she asked.

Researchers observed that I. sakaiensis almost completely degraded a thin film of polyethylene terephthalate, or PET, after six weeks in a laboratory. But when extracted from the bacterium, the proteins used to break down plastic begin working in about 18 hours.

I. sakaiensisappears to break PET into smaller molecules, like amino acids and carbon dioxide, says coauthor Kenji Miyamoto of Keio University in Yokohama, Japan. But it would probably be hard for the microbe to break down plastic in the outdoors because of its specific growth requirements, he says. Miyamoto envisions that it could be possible to use the specialized proteins in a closed environment to break PET down into molecules such as terephthalic acid— one of the plastic’s main building blocks, which seems benign in the environment.

Prairie dog predators
Herbivorous prairie dog mothers routinely kill baby ground squirrels that encroach on their territories, researchers found. Competition for resources may be a contributing factor to the killings, Susan Milius reported in “Killer prairie dogs make good moms” (SN: 4/16/16, p. 14).

One reader had other ideas. Audrey Boag wondered if prairie dog moms kill ground squirrels to protect their pups from predation or from diseases carried by the squirrels. “In either case, minimizing the number of ground squirrels would pay in lifetime biological fitness,” she wrote.

“We never observed a ground squirrel kill or injure an adult or juvenile prairie dog,” says study coauthor John Hoogland. “Perhaps such attacks sometimes occur underground.” Hoogland notes that the majority of ground squirrels killed by prairie dogs were juveniles, which are too small to be a threat.

One threat, however, is a species of disease-carrying flea that infests both animals. Hoogland found that prairie dog killers and their offspring had fewer fleas than nonkillers and their offspring, “but this trend was not significant,” he says.

No, that’s not the sun. It’s Jupiter, ablaze with infrared light in new images taken in preparation for the Juno spacecraft’s July 4 arrival at the king of the planets. This image shows how heat welling up from deep within the planet gets absorbed by gas in the atmosphere, which can tell researchers how stuff moves around beneath Jupiter’s thick blanket of clouds. Juno won’t look for infrared light, but it will (among other things) measure how much microwave radiation is being blocked by water lurking within Jupiter’s atmosphere.

The map is pieced together from multiple images obtained at the Very Large Telescope in Chile over the past several months. Ground-based images such as these will help researchers understand what Juno is peering at each time it swoops in close to Jupiter’s clouds over the next 20 months.

For women thinking about fertility treatments, there may be one less thing to worry about.

A long-term study shows that women who underwent in vitro fertilization are not significantly more likely to develop breast cancer than women in the general public or women who opted for other fertility treatments. The results are reported July 19 in JAMA.

The fertility treatment alters progesterone and estradiol levels in women trying to get pregnant. Yo-yoing hormones have been linked to an increase in a woman’s odds of developing breast cancer, but studies are divided on whether IVF itself actually ups cancer risk.

Alexandra van den Belt-Dusebout of the Netherlands Cancer Institute in Amsterdam and her colleagues tracked 19,158 women who underwent in vitro fertilization treatment between 1983 and 1995 and 5,950 women who underwent other fertility treatments between 1980 and 1995.

Following up two decades later, the team found that 948 of the women had developed breast cancer. But breast cancer rates didn’t differ much between groups: 163.5 per 100,000 women for those who had IVF compared to 167.2 women on other fertility treatments and 163.3 women in the general public.

These orderly patterns of dark blue dots indicate where individual chlorine atoms are missing from an otherwise regular grid of atoms. Scientists manipulated these vacancies to create a supersmall data storage device.

The locations of vacancies encode bits of information in the device, which Sander Otte of Delft University of Technology in the Netherlands and colleagues describe July 18 in Nature Nanotechnology. The team arranged and imaged the vacancies using a scanning tunneling microscope. The storage system, which can hold a kilobyte of data, must be cooled to a chilly −196° Celsius to work.
To demonstrate the technique, the researchers transcribed an excerpt from a famous 1959 lecture by physicist Richard Feynman, “There’s Plenty of Room at the Bottom,” which predicted the importance of nanotechnology. In each block, paired rows represent letters. Blocks marked with an “X” were unusable. The encoded 159 words of text fill a region a ten-thousandth of a millimeter wide.

If scaled up, the researchers say, the technology could store the full contents of the U.S. Library of Congress in a cube a tenth of a millimeter on each side.

Plastic cling wrap with nano-sized pores could give “cool clothes” a new meaning.

The material lets heat escape, instead of trapping it like traditional fabrics, Stanford University materials scientist Yi Cui and colleagues report in the Sept. 2 Science. It could help people keep cool in hot weather, Cui says, and even save energy by reducing the use of air conditioning.

“It’s a very bold new idea,” says MIT physicist Svetlana Boriskina, who wrote an accompanying commentary. Demand for the new material could be far-reaching, she says. “Every person who wears clothes could be a potential user of this product.”
Current cooling devices include wearable fans and wicking fabrics; both rely on evaporation to cool human skin. But skin also sheds heat in another way — as infrared radiation. Clothing holds this heat close to the body, Cui says. If infrared radiation could instead pass through fabric, he reasoned, people would feel a lot cooler.

But the fabric would have to be transparent only to infrared wavelengths. To visible light, it would need to be opaque. Otherwise, the clothing would be see-through.

Cui found just one material that satisfied both requirements: a commercially available plastic used in lithium-ion batteries. The material, called nanoporous polyethylene, or nanoPE, is a cling wrap‒like plastic that lets infrared radiation through. But unlike cling wrap, the material isn’t clear: It blocks visible light.

Tiny pores speckled throughout the fabric act as obstacles to visible light, Boriskina says. When blue light, for example, hits the pores, it scatters. So do other colors. The light “bounces around in different directions and scrambles together,” she says. To human eyes, the resulting color is white.

The pores scatter visible light because they’re both in the same size range: The diameters of the pores span 50 to 1,000 nanometers, and the wavelengths of visible light range from 400 to 700 nanometers. Infrared light emitted by the body has a much larger wavelength, 7,000 to 14,000 nanometers, so the plastic’s tiny pores can’t block it. To infrared light, the pores are barely bumps in the road, not barriers.
The pores are kind of like small rocks at a beach, Boriskina says. They’ll interfere with the motion of small waves, but big waves will wash right over.

Cui and colleagues tested nanoPE by laying it on a hot plate warmed up to human skin temperature — 33.5° Celsius. NanoPE raised the “skin” temperature by just 0.8 degrees(to 34.3° C). “But when you put on cotton, my God, it rose to 37,” Cui says. “It’s hot!”

The researchers also tried to make nanoPE more wearable than plastic wrap. They coated it with a water-wicking chemical, punched holes in it to make it breathable, and layered it with cotton mesh. Now, the team is working on weaving the fabric to make it feel more like traditional textiles.

“Within five years, I hope someone will start wearing it,” Cui says. “And within 10 years, I hope most people will be wearing it.”

Researchers have digitally unwrapped and read an ancient Hebrew scroll that’s so charred it can’t be touched without falling apart. It turns out the document contains the oldest known Biblical text outside of the roughly 2,000-year-old Dead Sea Scrolls, the investigators say.

Archaeologists discovered the scroll’s remnants in a synagogue’s holy ark during a 1970 excavation in Israel of En-Gedi, a Jewish community destroyed by fire around 600.

In a series of digital steps, slices from a 3-D scan of the En-Gedi scroll were analyzed to bring letters and words into relief on a pieced-together, virtual page. Those images revealed passages from the book of Leviticus written in ink on the scroll’s disintegrating sheets. Radiocarbon results date the scroll to approximately 300, making it the earliest copy of an Old Testament book ever found in a holy ark, scientists report September 21 in Science Advances.

This computerized recovery and conservation process can now be used to retrieve other ancient documents “from the brink of oblivion,” the researchers say.

DENVER — A period of skyrocketing global temperatures started with a bang, new research suggests.

Impact debris and evidence of widespread wildfires around eastern North America suggest that a large space rock whacked Earth around 56 million years ago at the beginning of the Paleocene-Eocene Thermal Maximum, also known as the PETM, a period of rapid warming and huge increases in carbon dioxide. The event is one of the closest historic analogs to modern global warming and is used to improve predictions of how Earth’s climate and ecosystems will fare in the coming decades.
Too little is known about the newfound impact to guess its origin, size or effect on the global climate, said geochemist Morgan Schaller of Rensselaer Polytechnic Institute in Troy, N.Y. But it fits in with the long-standing and controversial proposal that a comet impact caused the PETM. “The timing is nothing short of remarkable,” said Schaller, who presented the discovery September 27 at the Geological Society of America’s annual meeting.

The impact may have contributed to the rapid rise in CO2 by stirring carbon up into the atmosphere, but it was hardly the sole cause, said Sandra Kirtland Turner, a geochemist at the University of California, Riverside. Her own environmental simulations suggest that the influx of carbon that flooded Earth during the PETM probably took place over at least 2,500 years, far too drawn out to be caused by a single event, she said at the same meeting.

During the PETM, a massive influx of carbon flooded the atmosphere (SN: 5/30/15, p. 15) and Earth warmed by 5 to 8 degrees Celsius to temperatures much hotter than today. That carbon dump altered the relative abundance of different carbon isotopes in the atmosphere and oceans, leaving a signal in the sedimentary record.

While searching for that signal in roughly 56-million-year-old sediments from sites up and down the U.S. East Coast, Schaller spotted microscopic glassy spheres about the size of a dust mite. These specks resemble those blasted from previously identified large impact events. After switching from a black to a white sorting tray to more easily see the black debris, one of Schaller’s Rensselaer colleagues, micropaleontologist Megan Fung, discovered abundant charcoal pieces in the mix. That charcoal formed when wildfires sparked by the impact raged across the landscape, she proposed.

More evidence of the impact will help researchers to better constrain its location, scope and possible relationship to the start of the PETM, Schaller said.

Two more teeny moons might be lurking around Uranus. That’s in addition to the 27 we already know about. Fluctuations in the density of two of the planet’s dark rings, seen in radio data from the 1986 flyby of the Voyager 2 spacecraft, could be caused by unseen moonlets, Robert Chancia and Matthew Hedman, astronomers at the University of Idaho in Moscow, report online October 9 at arXiv.org.

At probably just 4 to 14 kilometers wide, both moons would be very difficult to detect in Voyager 2 images, the researchers report. New observations with ground-based telescopes might have better luck.

Traffic jams in the brain’s blood supply may play a role in Alzheimer’s disease. A new online game turns people at home into amateur traffic cops. This policing, which involves spotting hard-to-see sluggishness in tiny capillaries in mice, may ultimately help scientists better understand, and perhaps even treat, Alzheimer’s, a devastating disorder that affects over 5 million Americans.

The science behind the game, called Stall Catchers, comes from Cornell University. Chris Schaffer, Nozomi Nishimura and colleagues found that mice designed to exhibit symptoms similar to Alzheimer’s have more blocked blood vessels in their brains than regular mice. That difference can deprive the brain of sustenance and may be a key to understanding how Alzheimer’s damages the brain, the researchers suspect.
But finding congested capillaries is a slog. Computers haven’t been up to snuff, and experts could spend an entire year analyzing the thousands of microscope images needed to amass enough data to explore links between Alzheimer’s and blocked vessels. “I thought, if we could change that, it would be tremendous,” says Pietro Michelucci, director of the Human Computation Institute in Fairfax, Va. The institute is a nonprofit organization that runs the EyesOnALZ program, which aims to crowdsource Alzheimer’s research.

That’s where StallCatchers.com comes in. The website asks players to sift through short black-and-white videos of real mouse brains, on the prowl for blocked blood vessels. In the videos, moving blood appears white. But stationary black segments that appear between two white segments signal trouble — a stall. Players rack up points and ascend levels as they classify vessels. With practice, the task gets easier. And people who suffer from performance anxiety shouldn’t fret; each video will be scrutinized by multiple users to get the final verdict. With a little help from the crowd, “not only do [researchers] get answers faster, but they can ask more questions,” Michelucci says.

So far, nearly 1,000 users have played Stall Catchers, Michelucci says. Those players are beginning to generate data that will let researchers see how good these amateur traffic cops are. With luck, their eyes will help unstall the fight against Alzheimer’s.

NEW ORLEANS — Popular heartburn drugs — already under investigation for possible links to dementia, kidney and heart problems (SN: 6/11/16, p. 8) — have a new health concern to add to the list. An analysis of almost 250,000 medical records in Denmark has found an association with stroke.

Researchers from the Danish Heart Foundation in Copenhagen studied patients undergoing gastric endoscopy from 1997 to 2012. About 9,500 of all patients studied suffered from ischemic strokes, which occur when a blood clot blocks a blood vessel in the brain.

Overall, the risk of stroke was 21 percent higher in patients taking a proton pump inhibitor, a drug that relieves heartburn, the researchers reported November 15 during the American Heart Association’s annual meeting. While those patients also tended to be older and sicker to start with, the level of risk was associated with dose, the researchers found. People taking the lowest drug doses (between 10 and 20 milligrams a day, depending on the drug) did not have a higher risk. At the highest doses, though, Prevacid (more than 60 mg/day) carried a 30 percent higher risk and Protonix (more than 80 mg/day) a 94 percent higher risk. For Prilosec and Nexium, stroke risk fell within that range.

Introduced in the 1980s, proton pump inhibitors are available in both prescription and over-the-counter forms. While they are valuable drugs, “their use has been increasing rapidly,” says lead author Thomas Sehested, adding that people often take them for too long, or without a clear reason. Before taking them, he says, “patients need a conversation with their doctor to see if they really need these drugs.”