- New Images of Enceladus Show More Plumes and Heat
- Sperm Whales Use Team Work to Hunt Prey
- Virulent Bird-Human Flu Hybrid Made in Lab
- DOE Ponies Up $10 Billion in Financing for Solar, Nuclear Plants
- Math Shows Some Crime Hot Spots Can Be Cooled, Others Only Relocated
Posted: 23 Feb 2010 05:06 PM PST
The Cassini spacecraft's November flyby of Saturn's moon Enceladus has revealed new features including at least 20 more icy plumes spewing from the moon's southern pole.
New infrared data gives scientists the highest resolution temperature map of one particular warm fissure called a "tiger stripe." The moon's four tiger stripes arefractures that spew a mix of ice particles, water vapor and organic compounds into space. They are a key clue for scientists trying to figure out if small moon harbors a liquid water ocean under its frosty surface. Now, scientists know that their temperatures can exceed 180 Kelvin (minus 135 degrees Fahrenheit).
"The fractures are chilly by Earth standards, but they're a cozy oasis compared to the numbing 50 Kelvin (-370 Fahrenheit) of their surroundings," said John Spencer, a composite infrared spectrometer team member based at Southwest Research Institute in Boulder, Colorado.
"The huge amount of heat pouring out of the tiger stripe fractures may be enough to melt the ice underground," Spencer said."Results like this make Enceladus one of the most exciting places we've found in the solar system."
Enceladus is obviously too distant for the sun heat the moon to temperatures that could keep water in its freely flowing phase. Instead, the planet'swarmth appears to result from "tidal heating." Saturn's gravitational force deforms the satellite as it rotates. The back-and-forth pull heats up the satellite like a human repeatedly bending a spoon.
The new detailed temperature map of the tiger stripe, "Baghdad Sulcus," shows that the temperature varies along the length of the fracture. The warm spots are confined to an area just half a mile across. For those hoping to find simple extraterrestrial life within our solar system, those might be the most interesting canyons outside planet Earth.
More images of this remarkable celestial object below.
The area that was examined in detail in the image aboveis highlighted here.
Enceladus is just 310 miles in diameter, but may have the most easily accessible liquid ocean beyond Earth.
This close-up 3-D view of the Baghdad Sulcus shows 10 miles of the fracture in dramatic relief.
Images: 1) NASA/JPL/Space Science Institute. 2) NASA/JPL/GSFC/SWRI/SSI. 3-5) NASA/JPL/SSI
Posted: 23 Feb 2010 03:09 PM PST
PORTLAND — Sperm whales sometimes collaborate when they forage the depths, new tracking data suggest, with some individuals herding prey into dense schools while others lunge into the fray and feed.
Scientists have long known that sperm whales, like many other toothed whales, form long-lasting social groups that typically consist of females and their young. While some researchers have suggested that the females in such groups collaboratively raise their young, the new data are the first to hint that the whales may engage in tag-team hunting. Bruce Mate, director of Oregon State University's Marine Mammal Institute in Newport reported February 22 at the American Geophysical Union's Ocean Sciences meeting.
In 2007 and 2008, Mate and his colleagues tagged sperm whales in the Gulf of California with a new type of data-gathering sensor. These hockey-puck-size instruments included a Global Positioning System receiver, which gathered data when the creatures were at the ocean's surface, and other sensors that recorded water depth. In essence, Mate said, the instruments are flight data recorders for whales.
After taking data once every two seconds for as long as 28 days the instruments broke free and floated to the ocean surface, where they could be recovered by the researchers.
One of the whale groups the team studied consisted of between 10 and 15 individuals, three of which were tagged with recorders. Data showed that during some deep dives, whales zigzagged back and forth or suddenly surged forward, probably when they foraged on the Humboldt squid prevalent in the area. Sometimes the three tagged whales, presumably accompanied by others in the group, dove to great depths at the same time.
"We expected their dives to be similar, but often one of the three whales went deeper than the other two," Mate said. This behavior is similar to that of sea lions and dolphins, which sometimes collaboratively prey upon fish by herding them into tight groups known as "bait balls."
Mate and his colleagues speculate that the whale that dove deepest during each coordinated excursion helped prevent squid from escaping downward.
Sperm whales engaging in such behavior apparently share deep-diving patrol duty, Mate said, probably because the forays — which sometimes extend to depths of 1,500 meters — are physiologically stressful.
The new findings suggest but don't prove collaborative foraging among sperm whales, comments Kelly Benoit-Bird, a biological oceanographer at Oregon State's main campus in Corvallis. For one thing, she notes, the team's data reveal the behavior of the whales but not their prey, and it's not clear that squid respond to groups of predators by forming concentrated "bait balls" the same way that fish sometimes do.
Mate and his colleagues are now working to address that issue. Developing a technique to observe squid at depth is a somewhat difficult task, he notes, because unlike fish squid don't have air-filled bladders that show up well on sonar images.
Meanwhile, the new data recorders deployed by Mate and his colleagues can also be used for other behavioral research in whales. For instance, Mate suggests, the instruments could reveal how whales respond to various sources of aquatic noise such as sonar or the often intense pressure pulses generated during submarine seismic surveys used in research or oil and gas exploration.
Image: A sperm whale calf only hours old, swims next to its mother and a pod of sperm whales./ AP Photo/Guam Variety News, Chris Bangs.
Posted: 23 Feb 2010 01:38 PM PST
Engineered hybrids of bird and human flu strains have proven virulent in mice, raising the disturbing possibility that a natural recombination could be deadly to humans.
For years, researchers have worried that H5N1 avian influenza would mix with human flu viruses, evolving into a form that keeps its current lethality but is far more contagious. That hasn't happened — but the latest findings, publishedFeb. 22in the Proceedings of the National Academy of Sciences, show how easily it might.
"Fortunately, the H5N1 viruses still lack the ability to transmit efficiently among humans." However, this obstacle may be overcome by mixing with flu strains common in people, wrote researchers led by University of Wisconsin virologist Yoshihiro Kawaoka. "The next pandemic then will be inevitable."
Current strains of H5N1 have infected 478 people since 2003, and killed 286 of them. It's difficult to transmit in humans, requiring close contact with an infected person or animal. In birds, however, H5N1 is far more contagious, and his killed tens of millions of fowl. Cases have been concentrated in Africa and Eurasia, but as the swine flu pandemic demonstrated, any flu contagious to humans will likely go global, fast.
Influenza viruses swap genes easily, with co-infections turning animals into mobile petri dishes. In 2008, hoping to learn more about how H5N1 might evolve, researchers from the Centers for Disease Control and Prevention combined it with a common human flu strain. The hybrids proved less virulent than the original bird flu strain. Researchers wondered whether more contagious bird flu would necessarily alwaysbe less deadly in humans.
The PNAS findings suggest this may not be so.The researchers engineeredall 254 possible variants of hybridization between a deadly bird flu strain found in Borneo, and a human flu virus from Tokyo. They identified three strains that, at least in mice,were both contagious and deadly.
A flu virus that kills mice won't necessarily kill humans, but the results are suggestive. All three killer hybrid strains possessed a protein taken from the human strain. Called PB2,the proteinappeared to help the virus survive in the mice's upper respiratory tract. As of now, bird flu stays in the lower respiratory tract, where it's less likely to be casually transmitted.
The findings come as the World Health Organization meets to decide whether the swine flu pandemic has abated. Though the pandemic has not proved as lethal as originally feared, it exposed how unprepared the world is for new influenza strains.
In May, Hong Kong University virologist Yi Guan, best known for finding the animal origin of SARS, was asked by Science Insider about the possibility of H5N1 and swine flu mixing.
"If that happens, I will retire immediately and lock myself" in a sealed laboratory, said Guan.
Photo: A person feeds northern pintail ducks and whooper swans in Northern Honshu, Japan; in spring 2008, highly pathogenic H5N1 was found there in both bird species./USGS
Citation: "Reassortment between avian H5N1 and human H3N2 inﬂuenza viruses creates hybrid viruses with substantial virulence." By Chengjun Li, Masato Hatta, Chairul A. Nidom, Yukiko Muramoto, Shinji Watanabe, Gabriele Neumann, and Yoshihiro Kawaoka. Proceedings of the National Academy of Sciences, Vol. 107 No. 8, February 23, 2010.
Posted: 23 Feb 2010 11:41 AM PST
The Department of Energy has provided almost $10 billion in loan guarantees for two nuclear and three solar power plants in just the past week.
The moves mark a new DOE strategy to finance the large-scale deployment of low-carbon technologies in the United States.
The Oakland-based company BrightSource will conditionally receive $1.4 billion in loans for a solar complex in the Mojave Desert, while a consortium led by the Southern Company will get a whopping $8.33 billion to build two new nuclear reactors in the city of Burke, Georgia.
The dual moves would have been almost unthinkablefor allthe administrations since Reagan took office in 1981. Traditionally, promoting nuclear power has been seen as a right-wing issue, while the left has preferred solar.
"What I hope this announcement underscores is both our commitment to meeting the energy challenge– and our willingness to look at this challenge not as a partisan issue, but as a matter far more important than politics," Barack Obama said in a release Feb. 16 announcing the nuclear power plant funding.
Loan guarantees are one of a series of indirect financial incentives that could accelerate the introduction of new energy technology. The 2005 Energy Act gave the DOE authorization to make such moves. By making the loan guarantees, the government ensures the projects will get money through the Federal Financing Bank at a below-market rate.
Some policy wonks argue that providing loans to private companies to build innovative new plants is essential for commercializing technologies that are trying to make the jump from small demonstration plant to full-scale facility.
It's a risky step, so such subsidies may be necessary to deploy new types of plants. Most of our electrical infrastructure depends on technologies developed before 1970. Seventy percent of electricity in the United States is generated by burning fossil fuels to create heat which can be converted into electricity. The fundamentals haven't changed for a century.
The Obama Administration has made it clear that technologies with substantially lower carbon-intensity are a major priority. Both nuclear and renewable technologies fit the bill, although both types of power have their detractors. BrightSource has encountered opposition from environmentalists concerned with the impact the solar plant may have on the desert tortoise. Organized opposition to nuclear power generally focuses on the plants' radioactive waste issues or fears of catastrophic plant failure or terrorist attack.
Energy Secretary Steve Chu recognized that the Democratic administration's support for the new nuclear plants was particularly controversial and responded on his Facebook page with his rationale for supporting a form of energy that has not been popular on the American political left.
"The sun isn't always shining, and the wind isn't always blowing. Without technological breakthroughs in efficient, large-scale energy storage, it will be difficult to rely on intermittent renewables for much more than 20 to 30 percent of our electricity," Chu wrote in a post entitled Why We Need More Nuclear Power.
"To overcome this problem, we are pursuing breakthrough approaches to grid-scale energy storage as well as stimulating the widespread adoption of known technologies such as pumped hydro energy storage," he wrote. "But nuclear power can provide large amounts of carbon-free power that is always available."
The two new nuclear plants would be the first reactors built in the United States in almost 30 years. In the intervening decades, the performance record of nuclear power plants has improved a lot. In the late '70s, the average plant was out of operation four out of every 10 days. Now, the plants are online 90 percent of the time.
Nuclear advocates celebrated the new guarantees as a sign the long-awaited "nuclear renaissance" might begin under Obama. His new budget proposes more than $54 billion in funding for nuclear loan guarantees.
Wall Street banks have been loathe to invest in nuclear power plants since the industry's grisly collapse in the '70s and '80swhen about 100 projects were abandoned during construction. Plant designers say they've eliminated many of the problems that plagued the first nuclear era, but the perceived high risk involved in plant construction makes borrowing the money to build new reactors expensive or impossible. Government financing doesn't eliminate the risk of construction issues; it shifts the burden onto taxpayers if anything goes wrong.
A 2006 paper in Environmental Science and Technology authored by Dan Kammen, an energy specialist at UC Berkeley, and two colleagues, looked at the costs of almost all the reactors built in the United States. Many plants were actually completed within a reasonable time frame, but there was a troubling clump of very overbudget projects. Kammen argued that new plants may be subject to cost "surprises."
But until new plants get built, optimistic or pessimistic speculations about their costs and build times will remain just that.
BrightSource is the descendant of the most successful solar thermal company of all time. Luz International built 354 megawatts of solar thermal plants in the Mojave Desert in the late 1980s. They continue to generate power today for Southern California Edison. At the time they were built, they represented more than 90 percent of the solar electricity capacity in the world. Luz itself went bankrupt in 1992 because of a combination of low fossil fuel prices and a quiver-full of regulatory changes that hurt the company's bottom line. Still, the company's achievements were impressive: It brought the cost of the power from its plants down from 24 cents per kilowatt hour to 8 cents per kilowatt hour, nearly competitive with fossil fuels.
After years working on other projects, Luz's founder, Arnold Goldman, got together a new company earlier this decade, which was eventually christened BrightSource. Goldman is the chairman of the board and his very first engineering hire, Israel Kroizer, is the company's Chief Operating Officer.
The company's technology in this go-round is not exactly the same as it was. Luz employed parabolic trough technology in which curved mirrors focus the sun's rays on a special liquid-filled tube running their length. That liquid is run to a heat exchanger which turns water into steam and drives a traditional generator. Eight of Luz's nine plants could also run on natural gas, which allowed the plant's operators to generate electricity under any weather conditions.
The DOE's other big loan guarantee, for the solar company BrightSource, had long been expected by the outfit's management. With the guarantees in hand, the company wants to begin construction on the first of three plants near Ivanpah, California later this year, with commercial operation beginning in 2012. First, they have to finish the extensive environmental permitting process and secure hundreds of millions of dollars in private financing. If all goes as planned, the project's lead contractor, Bechtel will complete all three plants by the end of 2013. They'll have a peak capacity of about 400 megawatts.
BrightSource is using a "power tower" design for its new plants. A field of mirrors surround a tower with a water-filled boiler sitting on top of it. The mirrors focus the sun's rays onto the boiler, which heats up the water and transforms it into steam. That steam can be used to impart mechanical energy to a generator and create electricity. The company's demonstration tower has been producing steam in Israel's Negev Desert has been operating for the past year.
Taken together, the DOE announcements signal a return of solar and nuclear energy to the prominence they once enjoyed in the 1970s. Back then, Alvin Weinberg, who headed Oak Ridge National Laboratory, wrote a paper about the nation's post-fossil energy future asking the question, "Can the sun replace uranium?"
From the recent funding announcements, theDOE still doesn't know the answer to that question, but the push to find out is finally taking shape.
Posted: 23 Feb 2010 10:13 AM PST
SAN DIEGO — Not all crime hot spots are created equal, a new mathematical model suggests. For some areas repeatedly hit hard with crime, police intervention can shut down lawlessness and keep it down. But for others, police involvement just shifts the trouble around.
"If you see a hot area of crime, you want to know: If you send the police in, will that displace the crime or get rid of the crime altogether?" said Andrea Bertozzi, a mathematician at UCLA who presented the new model Feb. 20 at the annual meeting of the American Association for the Advancement of Science. "We were able to predict the ability to suppress or otherwise displace hot spots." The results will also appear Feb. 22 in the Proceedings of the National Academy of Sciences.
The study "makes a major contribution to the theory of hot spots of crime," comments John Eck, a criminologist at the University of Cincinnati.
Working with anthropologists, criminologists and the Los Angeles Police Department, Bertozzi built a mathematical representation of how areas with frequent, repeated crimes form within a city and change over time.
The team modeled a city as a two-dimensional grid populated with burglars and houses to rob. The researchers used previous studies to add a mathematical description of how attractive a region is to a burglar. Data has shown, for example, that the house next door to a house with a broken window is more likely to be robbed.
Bertozzi and colleagues ran simulations that led to the formation of crime hot spots and then simulated police intervention. Two sharply distinct outcomes emerged. Certain kinds of hot spots just moved around in response to police efforts to quash them. "It's impossible," Bertozzi said. "You hit one and it pops up somewhere else."
But for others, suppressing the hot spot once erased it forever.
The difference comes from how the hot spot forms in the first place. The model shows that a high-risk zone forms around every break-in. If the boundaries of risk zones overlap, then a persistent hot spot forms. "The diffusion of risk basically binds together local crimes, which then will seed more crimes," Bertozzi said.
But suppressible hot spots can form from one large crime spike, in which a single event draws in more criminals. A good example of this might be the formation of a drug market, said UCLA anthropologist Jeffrey Brantingham, a co-author of the paper.
"You wouldn't suspect this was the case from just mapping the hot spots," Brantingham said. "Empirically they look very much the same." The math was able to show that there may be two different types of hot spots when the data alone could not, he said.
"This is something that would be important for us in real life," Bertozzi said, "to be able to go and tell the police, in this situation you're going to be able to get rid of the crimes, and in this other situation you're only going to displace them."
Though the researchers compared the model's predictions of where and when burglaries would happen with real data from a region of the San Fernando Valley, Eck says he would want to test the model's police intervention predictions. Still, he says, it makes "a really elegant start."
Image: invisible city photography/Flickr
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