| Huge Holes in the Earth: Open-Pit Mines Seen From Space
October 15, 2009 at 7:40 pm
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| | People have become significant earth movers, outpacing all sources of natural erosion. More and more of our footprint can be seen from space in many forms, including cities, reservoirs, agriculture and deforestation. Among the most impressive human scars on the planet are open-pit mines. We’ve gathered some of the biggest, most spectacular and interesting mines, as captured by astronauts and satellites on the following pages. Above: Berkeley Pit, Butte, Montana This former copper mine operated between 1955 and 1982. Gold and silver were also mined. An elaborate system of pumps and drains kept the local water level low enough for mining. Today, the 1,780 foot-deep pit is filled with around 900 feet of very contaminated water filled with metals and chemicals such as arsenic, cadmium, pyrite, zinc, copper and sulfuric acid. The water can be as acidic as battery acid, and copper can actually be “mined” directly from the water. Currently, the 1-mile-by-0.5-mile pit is listed as a federal Superfund site with the potential to contaminate surrounding ground water, and, surprisingly, is also a tourist attraction, complete with gift shop and $2 admission fee. This photograph was taken Aug. 2, 2006, by astronauts aboard the International Space Station. Image: NASA 
 
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| Edge of Solar System Is Not What We Expected
October 15, 2009 at 5:18 pm
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The edge of the solar system is tied up with a ribbon, astronomers have discovered. The first global map of the solar system reveals that its edge is nothing like what had been predicted. Neutral atoms, which are the only way to image the fringes of the solar system, are densely packed into a narrow ribbon rather than evenly distributed.  "Our maps show structure and energy spectra that are completely different from what any model has predicted," says study co-author Herbert Funsten of the Los Alamos National Laboratory in New Mexico.
NASA's Interstellar Boundary Explorer satellite, or IBEX, discovered the narrow ribbon, which completes nearly a full circle across the sky. The density of neutral atoms in the band is two to three times that in adjacent regions. These and related findings, reported in six papers posted online Oct. 15 in Science, will not only send theorists back to the drawing board, researchers say, but may ultimately provide new insight on the interaction between the heliosphere — the vast bubble in which the solar system resides — and surrounding space. The bubble is inflated by solar wind, the high-speed stream of charged particles blowing out from the sun to the solar system's very edge. For 48 years, researchers have assumed that the solar wind sculpted the structure at the heliosphere's boundary with interstellar space, says Tom Krimigis of Johns Hopkins University's Applied Physics Laboratory in Laurel, Maryland. But the newly found ribbon's orientation suggests that the galaxy's magnetic field, just outside the heliosphere, seems to be the chief organizer of structure in this region, says theorist Nathan Schwadron of Boston University, a lead author of one of the studies. It's not known whether the ribbon lasts for just a few years or is a permanent feature.
Equally puzzling are observations of the same boundary region with an instrument on the Cassini spacecraft, which recorded the density of atoms at higher energies, above 6,000 electron volts. From its vantage point at Saturn, Cassini sees a belt rather than a ribbonlike structure, a team led by Krimigis also reports in Science. The belt is substantially broader than the ribbon seen by IBEX but is in the same general area. The heliosphere shields the solar system from 90 percent of energetic cosmic rays — high-speed charged particles that would otherwise bombard the planets and harm life. Understanding more about the heliosphere and its ability to filter out galactic cosmic rays could be critical for assessing the safety of human space travel, Schwadron notes. The new findings may also help predict how the heliosphere varies in shape and size as it moves through the galaxy and encounters regions of space having different densities and magnetic field strengths.  The ribbon found by IBEX, recorded at energies between 200 and 6,000 electron volts, is brightest at about 1,000 electron volts and lies between about 100 and 125 astronomical units from the sun, notes David McComas of the Southwest Research Institute in San Antonio. One astronomical unit is the distance between the Earth and the sun. The atoms recorded by IBEX, which orbits Earth, took a year or two, depending on their energies, to reach the craft from the outer edge of the heliosphere.
The IBEX ribbon runs perpendicular to the direction of the galaxy's magnetic field at the interstellar boundary, an indication that the field has a much stronger than expected influence on the sun's environs, report Schwadron and his colleagues. One possibility is that pressure from this external magnetic field has forced particles just inside the heliosphere to bunch together into a ribbon. "First and foremost, this is a big surprise because we thought we know a lot about this region, the edge of the heliosphere," McComas says. The Voyager 1 craft in 2004 (Science News: 1/3/04, p. 7) and the Voyager 2 craft in 2007 (Science News: 8/2/08, p. 7) journeyed to opposite sides of this fringe region of the solar system and crossed the termination shock — where the solar wind encounters a shock that precedes the influx of particles drifting into the solar system from interstellar space. Both craft recorded the density of particles and the strength of the magnetic fields. Both Voyager 1 and 2 missed seeing the newly found ribbon because it spans a region between their flight paths, says McComas. No existing model can explain the ribbon, he adds, which was found independently by two instruments on IBEX. Researchers had assumed that the pressure from the solar wind would compress in the heliosphere in the direction that the solar system was moving through space and create a cometlike tail in the opposite direction, notes Krimigis. "Now we know that's wrong," he says. IBEX has also generated the first maps of neutral hydrogen and oxygen atoms entering the solar system from interstellar space. Previous observations had traced only incoming helium atoms. The sensitivity of the IBEX instruments allowed researchers to record the relatively small number of oxygen atoms that travel from beyond the termination shock, about 16 billion kilometers from Earth, to the spacecraft, notes study co-author Stephen Fuselier of the Lockheed Martin Advanced Technology Center in Palo Alto, California. Hydrogen atoms are more abundant than either helium or oxygen but their low mass means they are easily swept aside by the high-speed solar wind and can't readily be detected. The sun's unusually low activity during the current minimum in the solar cycle allowed more of the hydrogen atoms from the outer heliosphere to travel unimpeded to the inner solar system, enabling IBEX to record those atoms, Fuselier says. Images: 1) NASA. 2) Southwest Research Institute.
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| Sour: It's What Carbonation Tastes Like
October 15, 2009 at 2:51 pm
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The carbon dioxide in your favorite soda pop tastes sour to your tongue, thanks to an enzyme that converts CO2 into protons that sour-sensing cells can detect. That means your Coca Cola isn’t just packed with high-fructose sweetness, but, perhaps counterintuitively, its carbonation delivers a delicious squirt of sour too, according to a new study in mice, published Thursday in the journal Science. “The same taste cell has all the machinery to turn carbon dioxide into protons and then detect the protons as sour taste stimuli,” said Alexander Bachmanov, who was not involved in the study. The discovery is of particular interest in the food and beverage world, Bachmanov said, because carbonation has long been recognized as a complex phenomenon for the mouth. Even if the sour-sensing cells signal that the carbonation is sour, there are more elements to the process of actually tasting, say, soda water.
 “If you think about carbonation, it has more than one attribute,” he said. “One is sourness, which we perceive, but there is probably also some tactile sensation how the bubbles form and burst, tickling the tongue.”
The researchers, led by longtime taste researcher Charles Zuker, now at Columbia University Medical Center, conducted the study using mice that had been genetically altered to lack sour-sensing cells. They found that such mice could not detect carbon dioxide, as seen in the chart. While the study was carried out with mice, the mechanism is expected to have been preserved in other mammals. Zuker and his colleagues posed a natural evolutionary question: Why would mammals have developed such an excellent carbon dioxide detector? “CO2 detection could have evolved as a mechanism to recognize CO2-producing sources — for instance, to avoid fermenting foods,” they wrote. One happy irony of such a hypothesis is that the very same mechanism that allowed our deep ancestors to recognize and avoid fermentation allows modern humans to intentionally create the fermented beverages beer and champagne. Or, our carbonation-detecting skills could be an accident. The sour-cell enzymes might be maintaining the pH balance of the taste buds, and the tang of soda water is just fallout. Accident or adaptation, from sparkling wine to Coca Cola to energy drinks to the carbonated yogurt popular in Iran called doogh, humans love carbonation in its many forms. Though their share of the beverage market might be slipping a bit, the world’s population still spends half its drink money on carbonated quenchers. Zuker’s company Senomyx develops artificial flavors, and have disclosed that they have a partnership with Coca Cola, among other companies.
Image: adamcomerford/Flickr
See Also: WiSci 2.0: Alexis Madrigal’s Twitter, Google Reader feed, and green tech history research site; Wired Science on Twitter and Facebook. 
 
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| Wires Inserted Into Human Reveal Speech Surprise
October 15, 2009 at 1:12 pm
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A rare set of high-resolution readouts taken directly from the wired-in brains of epileptics has provided an unprecedented look at how the brain processes language. Though only a glimpse, it was enough to show that part of the brain’s language center handles multiple tasks, rather than one. “If the same part of the brain does different things at different times, that’s a thunderously complex level of organization,” said Ned Sahin, a cognitive scientist at the University of California, San Diego. In a study published Thursday in Science, Sahin’s team studied a region known as Broca’s center, named for French anatomist Paul Pierre Broca who observed that two people with damage to a certain spot in the front of their brains had lost the ability to speak, but could still think. Broca’s discovery was made in 1865, but subsequent research has been relatively incremental, reinforcing the language-central role of this area but saying little about what goes on inside it. Speech can’t be tested in any life form other than ourselves, and the standard tool for reading the human brain is fMRI, which averages the activity of millions of neurons at set intervals. It’s useful for highlighting regions of the brain that are involved in cognitive tasks, but can’t detail what’s happening inside those areas. Sahin’s team benefited from a brain-reading technology called intra-cranial electrophysiology, or ICE, in which electrodes are positioned inside the brain itself. It’s a medical rather than a research tool, used to precisely measure electrical activity in the brains of epileptics who don’t respond to treatment. ICE lets doctors see exactly which parts of a patient’s brain may be surgically removed to prevent future seizures. Though it’s far too invasive and risky to ever be used for academic research, it gave Sahin’s team a chance to watch brains as they processed language. The patients are “just sitting in a hospital bed, looking at a laptop, and they’re jacked in, with wires right into their brain. And we’re listening to the brain cells talking,” said Sahin. “It’s fantastic that we cold get so close to the actual neural data. Compared to fMRI, it’s like a close-up, high-speed camera where you can see each beat of a hummingbird’s wings, versus taking a picture of the bird flying around a flower.” During the several days that three patients at Massachusetts General Hospital were medically wired, Sahin’s team asked them to repeat words verbatim, and translate them to past and present tense. In the space of a quarter-second, a small part of Broca’s area — the only part read by the electrodes — received each word, put the word in a correct tense, and sent it to the brain’s speech centers. This tested only one type of verbal cognition, cautioned Sahin, and the focus was unavoidably narrow, but it was enough to show that Broca’s area is involved not only in translating speech, but receiving it. That role was considered specific to part of the brain called Wernicke’s area. More broadly, the findings may represent a general rule for Broca’s area, and perhaps other brain regions: Each part plays multiple roles, rather than performing a single task. “It’s very distinct from a model where part A does job A. Instead it’s part A doing jobs A, B and C,” said Sahin. In a commentary accompanying the findings, Max Planck Institute cognitive scientists Peter Hagoort and Willem Levelt said that since Broca’s original observations, “relatively little progress has been made in understanding the neural infrastructure that supports speech production.” The fine-grained Science data “suggests that we are witnessing the ‘first go’ process at work here,” they said. In further ICE studies of patients, Sahin’s team will study other parts of the language process, as well as the role of Broca’s area in music and movement. In addition to illuminating the brain’s complex choreography, researchers hope the findings will eventually be applied to treating language disorders. “I’m happy to contribute a piece to the puzzle,” said Sahin. “And the puzzle seems to get more complicated each time you put another piece into it.” Image: Ned Sahin See Also: Citations: “Sequential Processing of Lexical, Grammatical, and Phonological Information Within Broca's Area.” By Ned T. Sahin, Steven Pinker, Sydney S. Cash, Donald Schomer, Eric Halgren. Science, Vol. 326 No. 5951, October 16, 2009. “The Speaking Brain.” By Peter Hagoort and Willem Levelt. Science, Vol. 326 No. 5951, October 16, 2009. Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecosystem and planetary tipping points. 
 
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