Science News
Oxygen wafted into Earth's atmosphere earlier than thought
Date pushed back to 3 billion years ago
By Jessica Shugart
The date of Earth’s first whiff of oxygen may have occurred 300 million to 400 million years earlier than scientists thought. According to an analysis of ancient sediment, hints of oxygen graced the Earth’s atmosphere around 3 billion years ago.
The new date places oxygen on the Earth more than 600 million years before the Great Oxidation Event, when levels of atmospheric oxygen rose dramatically. In the last six years, a handful of geologic studies have dated transient wisps of oxygen to 2.6 billion to 2.7 billion years ago. Scientists think that photosynthetic microorganisms such as cyanobacteria produced the oxygen. So the timing of the first atmospheric oxygen has implications for how photosynthetic life evolved on the planet.
Because photosynthesis is complex, says geologist Sean Crowe who jointly led the study with Lasse Døssing of the University of Southern Denmark in Odense, scientists have thought “that it took a very long time to evolve.” The team’s data, along with the earlier reports that suggest oxygen was present before the Great Oxidation Event, chip away at that notion, says Crowe, who is now at the University of British Columbia in Vancouver.
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Faulty Justice: Italian Earthquake Scientist Speaks Out against His Conviction
Geophysicist Enzo Boschi slams the poor communication that could put him behind bars for six years
By Larry Greenemeier
A year ago an Italian court sentenced six scientists and an ex-government official to six years in prison for manslaughter. More specifically, the judge found them guilty for failing to give adequate advance warning to the population of L’Aquila, a city in the Abruzzo region of Italy, about the risk of the April 2009 earthquake that caused 309 deaths. As they await word of their appeal, the scientists maintain that the true culprit in that disaster was the government’s inability to communicate nuanced scientific information to L’Aquila’s citizens.
Much of the prosecution’s case hinged on a meeting of the National Commission for the Forecast and Prevention of Major Risks in L’Aquila one week prior to the earthquake. That confab, run by the Italian government, featured a committee of scientists who discussed the difficulty of predicting seismic activity but also pointed out that Abruzzo—L’Aquila in particular—sits on one of the worst earthquake zones in the country. Following the meeting, the government downplayed the risk of an earthquake, giving residents a false sense of security that discouraged them from fleeing to safety once the magnitude 6.3 quake had begun, according to prosecutors.
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Technology News
Spirals of Light May Lead to Better Electronics
California Institute of Technology
Sep. 26, 2013 — A group of researchers at the California Institute of Technology (Caltech) has created the optical equivalent of a tuning fork -- a device that can help steady the electrical currents needed to power high-end electronics and stabilize the signals of high-quality lasers. The work marks the first time that such a device has been miniaturized to fit on a chip and may pave the way to improvements in high-speed communications, navigation, and remote sensing.
"When you're tuning a piano, a tuning fork gives a standardized pitch, or reference sound frequency; in optical resonators the 'pitch' corresponds to the color, or wavelength, of the light. Our device provides a consistent light frequency that improves both optical and electronic devices when it is used as a reference," says Kerry Vahala, Ted and Ginger Jenkins Professor of Information Science and Technology and Applied Physics. Vahala is also executive officer for applied physics and materials science and an author on the study describing this new work, published in the journal Nature Communications.
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Carbon Nanotube Computer Hints at Future Beyond Silicon Semiconductors
More of Moore’s Law: A scalable process could realize the dream of carbon nanotube transistors that would be much smaller and more efficient than today’s silicon chips
By Jeremy Hsu
Modern lifestyles may not need to curb their appetites for smaller, faster smartphones and tablets when the digital age finally runs up against the physical limits of silicon-based computer chips. New research by Stanford University engineers might have just crowned a silicon successor by showing how to build a computer out of carbon nanotubes.
The 178-transistor computer only operates on one bit of information and a single instruction, which may seem unimpressive compared with modern computers that are based on 32-bit or 64-bit processors relying on millions to billions of transistors. But the Stanford University computer's use of carbon nanotubes—hollow cylindrical structures made from a sheet of carbon atoms—could pave the way for many future computing devices that run faster and use less energy. "It's a simple computer, but it's not a one-off computer," says Subhasish Mitra, an electrical engineer at Stanford and coauthor of a new paper detailed in the September 25 issue of Nature. (Scientific American is part of Nature Publishing Group.)
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Environmental News
News in Brief: Slashing greenhouse gas emissions could save millions of lives
Simulations suggest reduced air pollution would improve public health
By Erin Wayman
Cutting greenhouse gas emissions should improve air quality and thereby save millions of people’s lives by the end of the century, new simulations find.
Burning fossil fuels emits both climate-warming gases and other air pollutants such as particulate matter. Greenhouse gases also contribute to the formation of ground-level ozone, the main component of smog. Because particulate matter and ozone can cause heart and lung disease, researchers think that reducing greenhouse gases would improve public health.
J. Jason West of the University of North Carolina at Chapel Hill and colleagues simulated climate and air quality through 2100. In a simulation with reductions in fossil fuel use, the model found 2.2 million premature deaths per year could be avoided by the beginning of the next century, compared with a simulation without climate change mitigation.
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Banned Flame Retardants Finally Declining in Women
Scientists have documented for the first time that banned flame retardants have declined in people in the United States in a small study
By Lindsey Konkel and Environmental Health News
Scientists have documented for the first time that banned flame retardants have declined in people in the United States, where levels of the chemicals had been growing exponentially.
The small study, published today, reported that levels in pregnant California women were 65 percent lower than in a similar group of women tested three years earlier.
The two flame retardants have been banned in the United States since 2004. But many experts have been concerned about their persistence because they break down slowly in human tissues and were widely used in products, such as sofas, that people keep for many years.
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Medical News
An on-off switch for eating
By triggering or silencing certain brain cells, scientists can get mice to feed regardless of hunger
By Laura Sanders
By hijacking connections between neurons deep within the brain, scientists forced full mice to keep eating and hungry mice to shun food. By identifying precise groups of cells that cause eating and others that curb it, the results begin to clarify the intricate web of checks and balances in the brain that control feeding.
“This is a really important missing piece of the puzzle,” says neuroscientist Seth Blackshaw of Johns Hopkins University in Baltimore. “These are cell types that weren’t even predicted to exist.” A deeper understanding of how the brain orchestrates eating behavior could lead to better treatments for disorders such as anorexia and obesity, he says.
Scientists led by Joshua Jennings and Garret Stuber of the University of North Carolina at Chapel Hill genetically tweaked mice so that a small group of neurons would respond to light. When a laser shone into the brain, these cells would either fire or, in a different experiment, stay quiet. These neurons reside in a brain locale called the bed nucleus of the stria terminalis, or BNST. Some of the message-sending arms of these neurons reach into the lateral hypothalamus, a brain region known to play a big role in feeding.
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Mental rotation gears up by age 5 for both boys and girls
Math-related visualization skill emerges rapidly in preschool years
By Bruce Bower
Cartoon ghosts have scared up evidence that the ability to visualize objects in one’s mind materializes between ages 3 and 5.
When asked to pick which of two mirror-image ghost cutouts or drawings fit in a ghost-shaped hole, few 3-year-olds, a substantial minority of 4-year-olds and most 5-year-olds regularly succeeded, say psychologist Andrea Frick of the University of Bern, Switzerland, and her colleagues. Girls performed as well as boys on the task, suggesting that men’s much-studied advantage over women in mental rotation doesn’t emerge until after age 5, the researchers report Sept. 17 in Cognitive Development.
Mental rotation is a spatial skill regarded as essential for science and math achievement. Most tasks that researchers use to assess mental rotation skills involve pressing keys to indicate whether block patterns oriented at different angles are the same or different. That challenge overwhelms most preschoolers. Babies apparently distinguish block patterns from mirror images of those patterns (SN: 12/20/08, p. 8), but it’s unclear whether that ability enables mental rotation later in life.
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Space News
Curiosity gets the dirt on Mars
Rover completes analysis of first soil collected from Gale Crater
By Beth Mole
Whiffs of chemicals found in rocket fuel, a dark pyramid that resembles rare volcanic rocks on Earth and glassy particles bearing traces of water are among the Curiosity rover’s finds in its first chemical investigation of Martian dirt.
“This is the first time we’ve known precisely and definitively what this stuff is made of,” says astrobiologist David Blake of the NASA Ames Research Center in Moffett Field, Calif. He and his colleagues report the results of the analysis September 26 in Science.
In samples scooped from Martian dust, Blake and his colleagues found a mix of crystals from volcanic rocks plus glassy particles. Researchers discovered the blend by bombarding soil with radioactive alpha particles and using the energy signatures bounced back to identify the soil’s chemical contents.
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Observations Reveal Critical Interplay of Interstellar Dust, Hydrogen
University of Wisconsin-Madison
Sep. 26, 2013 — For astrophysicists, the interplay of hydrogen -- the most common molecule in the universe -- and the vast clouds of dust that fill the voids of interstellar space has been an intractable puzzle of stellar evolution.
The dust, astronomers believe, is a key phase in the life cycle of stars, which are formed in dusty nurseries throughout the cosmos. But how the dust interacts with hydrogen and is oriented by the magnetic fields in deep space has proved a six-decade-long theoretical challenge.
Now, an international team of astronomers reports key observations that confirm a theory devised by University of Wisconsin-Madison astrophysicist Alexandre Lazarian and Wisconsin graduate student Thiem Hoang. The theory describes how dust grains in interstellar space, like soldiers in lock-drill formation, spin and organize themselves in the presence of magnetic fields to precisely align in key astrophysical environments.
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Odd News
Singing Mice Protect Their Turf With High-Pitched Tunes
University of Texas at Austin
Sep. 26, 2013 — Two species of tawny brown singing mice that live deep in the mountain cloud forests of Costa Rica and Panama set their boundaries by emitting high-pitched trills, researchers at The University of Texas at Austin have discovered.
Although males of both the Alston's singing mouse (Scotinomys teguina) and Chiriqui singing mouse (S. xerampelinus) sing to attract mates and repel rivals within their respective species, the findings show for the first time that communication is being used to create geographic boundaries between species.
In this case, the smaller Alston's mouse steers clear of its larger cousin, the Chiriqui.
"Most people are puzzled by the existence of singing mice, but in reality many rodents produce complex vocalizations, including mice, rats and even pet hamsters," said Bret Pasch, a postdoctoral fellow in the Department of Integrative Biology and lead author on the paper, which was published online in The American Naturalist. "Often they're high-pitched and above the range of human hearing."
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