How did the equatorial ridge on Saturn's moon Iapetus form?
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- Raw image from Cassini space probe of the equatorial ridge on Saturns moon Iapetus. Image: NASA
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http://phys.org/news/2012-04-equatorial-ridge-saturn-moon-iapetus.html How did the equatorial ridge on Saturn's moon Iapetus form? Saturn's moon Iapetus is one of the most unusual moons in our solar system. Perhaps the most bizarre feature of Iapetus is its equatorial ridge, a 20-km (12.4- mi) high, 200-km (124-mi) wide mountain range that runs exactly along the equator, circling more than 75 percent of the moon. No other body in the solar system exhibits such a feature, and as Dombard et al. show, previous models have been unable to adequately explain how the ridge formed. 
The authors now propose that the ridge formed from an ancient giant impact that produced a subsatellite around Iapetus. Raw image from Cassini space probe of the equatorial ridge on Saturn's moon Iapetus. Image: NASA Tidal interactions with Iapetus ultimately led to orbital decay, eventually bringing the subsatellite close enough that the same forces tore it apart, forming a debris ring around Iapetus. Material from this debris ring then rained down on Iapetus, creating the mountain ring along the equator.
The trick to accomplish this is to deliver the poison directly to the right address in the body using something that virtually serves as a cab. In this case, the cab is an antibody whose highly specific arms attach to a cancer-typical cellular surface protein called EpCAM. The fungal toxin is linked to the antibody in a stable chemical conjugation. In the culture dish, the poison-loaded antibody arrested the growth of pancreatic, colorectal, breast and bile duct cancer cell lines. In mice bearing transplanted human pancreatic cancer, a single antibody injection was sufficient to inhibit tumor growth. Two injections of higher doses of the antibody even caused complete tumor regression in 90 percent of the animals. Even the higher doses did not cause any poison-related damage to the liver or other organs of the animals. EpCAM, the protein chosen by the Heidelberg immunologists as the tumor cell recognition structure, is a characteristic membrane protein of epithelial cells. This type of cells lines all inner and outer surfaces of the body. Most malignant tumors originate from such epithelial tissues. Many of these, such as pancreatic cancer, breast and ovarian cancers, bile duct carcinomas and tumors of the head and neck, produce too much EpCAM – and this is frequently associated with an extremely poor prognosis of the disease. EpCAM is therefore considered a suitable target structure for attacking tumor cells. "Treatments with unconjugated antibodies against EpCAM have already been tested in clinical trials such as for breast cancer. They were intended to attack the cancer solely with the weapons of the immune system, but they turned out to be clinically ineffective," said Gerhard Moldenhauer. "However, our amanitin-conjugated antibody has a much greater potential for killing cancer cells." Details are of vital importance Each antibody is linked to between four and eight toxin molecules. Amanitin is regarded as very suitable for this purpose. It is small enough not to be recognized as foreign by immune cells, while it is also robust enough to lend itself to chemical conjugation. "When developing toxin-conjugated antibodies you have to take an awful lot of things into account," Moldenhauer explains. "The cancer cell has to regularly take the target molecule including the attached antibody into its interior, for this is the only place where the poison can act. In the cell's interior, the poison needs to detach from the antibody or else it will not be effective. At the same time it is absolutely vital that it does not get lost while it is being carried through the body, because this could cause severe adverse side effects." The dosage of the amanitin antibody needs to be determined with the utmost care. One problem is that liver cells are extremely sensitive to the fungal toxin; another is that other healthy cells carry the EpCAM molecule as well and are therefore endangered. However, the results obtained in mice give reason to be optimistic, according to Gerhard Moldenhauer: "Even at high doses we have not detected any organ damage in the animals. We therefore expect that there is a sufficient therapeutic window for a dosage that kills cancer cells while leaving healthy tissue unaffected." Moldenhauer, who has many years of experience in developing therapeutic antibodies, already has plans for amanitin-conjugated guided missiles against other cancers. In particular, certain types of leukemia and lymphoma cells also carry highly specific surface molecules which lend themselves as target structures for poison-loaded antibodies.
LEAN back, let go of the steering wheel, ease your feet off the pedals and relax: your car is now in charge. The dream of a car that can drive itself has grown over the last decade as the necessary technologies have gradually proved their worth, but the idea has faced major legal hurdles. Not for much longer. Politicians are now scrambling to make self-driving cars a reality. From Hawaii to Florida, and Oxford to Berlin, the race is on to get driverless cars onto our streets. Promising improved safety, better fuel-efficiency and freedom from the boredom of long drives, autonomy has been coming piecemeal to our cars for some time - and it has always had its critics. In 1994, on a UK motorway, Jaguar and Lucas Industries demonstrated the safety of adaptive cruise control and automatic lane keeping; both technologies are now commonplace on our roads. The media were not impressed, describing the idea of cars that drive themselves as "madness". But concerns about the safety of autonomous cars are misplaced in a world where 1.2 million people die every year in road accidents due to human error, says Paul Newman, a robotics engineer at the University of Oxford, whose team is developing autonomous cars. "It's crazy to imagine that we are going to keep driving cars like we do now - that in 10 to 20 years we'll still have to sit behind a wheel, concentrating hard, not falling asleep and not running over people," he says. This notion now has powerful backers - and barriers are beginning to fall. In an act that came into force on 1 March, the state of Nevada now allows driverless cars to ply the state's road network provided they sport a special red licence plate, and the owners pay a $1 to $3 million insurance bond. Similar legislation is being considered in California, Arizona, Florida, Hawaii and Oklahoma. The phenomenon is not confined to the US either. In Germany, a driverless car research team led by Tinosch Ganjineh at the Free University of Berlin has permits to use the abandoned Templehof airport for autonomous tests. When necessary, team members get special permits to drive on Berlin's streets, and hope to drive on the autobahn soon. The Oxford team plan to approach the British government for similar permits. The Berlin team are automating a VW Passat, patriotically named MadeInGermany, while Oxford is turning a BAE Systems WildCat military jeep into a self-driving machine. Nissan has just joined the Oxford project, so the Leaf all-electric car may end up driverless too. Driverless cars first appeared in a meaningful way in the US Defence Advanced Research Project Agency's "grand challenges". Cars competed to drive fastest around desert courses in 2004 and 2005, and in an urban setting in 2007. Mike Montemerlo and Sebastian Thrun of Stanford University, California, whose car won the 2005 prize, lead Google's self-driving car research programme. Their cars, based on the Toyota Prius and Audi TT, typify the approaches of the Oxford and Berlin teams. All the cars have laser rangefinders, radar and optical cameras to sense the vehicle's changing real-time environment with high accuracy. They know where the traffic lights and road signs are, and which moving objects are animals, people, bikes, motorbikes or trucks. Newman's team are studying how algorithms can make sense of data streaming from a 3D laser rangefinder and quickly decide whether an object is a car or pedestrian, for example. His team is also looking at how a robotic visual system can build up a picture of its world and adapt to changing conditions, varying light levels or even seasons. The commercial sensors and software to make this happen are still some way off, though. "The Velodyne - the 64 spinning lasers on top of most driverless cars - give a quickly updated 360-degree, 3D view of the surroundings up to 40 metres away," says Newman. But cars of the future won't have unwieldy spinning lasers on them, he says. Ganjineh agrees that driverless technology has to be refined. "The size and price of these systems needs to come down. Today, half a trunk of equipment is needed for autonomous driving," he says. Another challenge, says Newman, is getting the cars to recognise the precursors to risky events - like sudden bright sun reflections on the road, truck spray, which may blind some sensors, or simply a burst tyre. Google's cars, meanwhile, tell each other about the roads they have travelled, such as exchanging data on how to negotiate awkward junctions, says Vinton Cerf, a Google technology evangelist. Ganjineh wants similar technology to broadcast GPS map changes car-to-car, when there are roadworks ahead, for example. However, driverless cars will not need to communicate wirelessly with expensive roadside technology as they need to be "independently smart" and aware of all risks around them at all times, says Newman. "Automation of cars is going to happen," he says. "Computing has caused devastating change and transport is going to be its next target."
Driverless cars could reduce insurance costs, says Paul Newman of the University of Oxford, by allowing the car to add to its own insurance as road conditions change. "On a dark icy night, when it is riskier to drive, the car could go online and bid for extra insurance cover until conditions change," he says. "If that proves too expensive, because conditions are tough for the autonomous system, the owner could take the wheel." Meanwhile, clear standards for programmers and developers of such cars need to be drawn up, says Tinosch Ganjineh at the Free University of Berlin, Germany, as accident liability may fall more often on software or sensor-makers. http://news.discovery.com/space/mars-dark-spots-120402.html Martian Dark Spots Reveal Heart of Glass Their finding represents the first detection of widespread surface weathering during the Amazonian epoch. Content provided by Stuart Gary, ABC Science Dark patches visible across much of the northern Martian hemisphere aren't canals or vegetation, as once thought, but volcanic glass according to a new study. The discovery by Briony Horgan and James Bell from Arizona State University, provides evidence of the same sort of processes seen on Earth, also happening on the Red Planet. Using near infrared spectroscopic data collected by the European Space Agency's Mars Express orbiter, Horgan and Bell found widespread weathered volcanic glass covering the surface of the Martian lowlands. "The volcanic glass (probably basalt) was created when hot magma reacted explosively with ice or water," says Horgan. "The same sort of thing happens in Iceland, where volcanoes erupt under glaciers. The interaction with the ice and the water causes the magma to become super-explosive, creating tonnes of sand sized black particles. These form vast sand dunes covering about a quarter of Iceland's surface, which is exactly what we're seeing on Mars," says Horgan. "We see these dark plains and enormous glassy sand dune fields up in the northern Martian polar regions." Horgan and Bell also found evidence of dips in the spectrum consistent with weathering caused by the glass being exposed to acidic water. Their finding, which appear in the journal Geology, represents the first detection of widespread surface weathering during the Amazonian epoch -- the most recent of the three Martian geologic periods. "The deposits are young by Martian standards, just a few billion years old, but that's still well after the planet's warm and wet period ended," says Horgan. According to Horgan, the evidence of weathering also supports the explosive magma hypothesis. "It works really well because we know there's lots of ice on Mars today," says Horgan. "In the past we think Mars went through multiple ice ages with huge icesheets, glaciers and snow packs covering the surface." Horgan says the melt water would have included dissolved chemicals that weathered the surface of the glass deposits even under the arid conditions of Mars. According to Horgan the creation of explosive volcanic glass also creates interesting habitats for study by astrobiologists. "If these things were created by magma ice interactions, they would have caused huge outflows of hot, chemically rich liquid water, which would have created a habitable environment which is one of the big drivers for the Mars Program today." http://www.eurekalert.org/pub_releases/2012-04/uot-sfe_1032812.php Scientists find evidence that human ancestors used fire one million years ago 300,000 years earlier than believed An international team led by the University of Toronto and Hebrew University has identified the earliest known evidence of the use of fire by human ancestors. Microscopic traces of wood ash, alongside animal bones and stone tools, were found in a layer dated to one million years ago at the Wonderwerk Cave in South Africa. "The analysis pushes the timing for the human use of fire back by 300,000 years, suggesting that human ancestors as early as Homo erectus may have begun using fire as part of their way of life," said U of T anthropologist Michael Chazan, co-director of the project and director of U of T's Archaeology Centre. The research will be published in the Proceedings of the National Academy of Sciences on April 2. Wonderwerk is a massive cave located near the edge of the Kalahari where earlier excavations by Peter Beaumont of the McGregor Museum in Kimberley, South Africa, had uncovered an extensive record of human occupation. A research project, co-directed by U of T's Chazan and Liora Kolska Horwitz of Hebrew University, has been doing detailed analysis of the material from Beaumont's excavation along with renewed field work on the Wonderwerk site. Analysis of sediment by lead authors Francesco Berna and Paul Goldberg of Boston University revealed ashed plant remains and burned bone fragments, both which appear to have been burned locally rather than carried into the cave by wind or water. The researchers also found extensive evidence of surface discoloration that is typical of burning. "The control of fire would have been a major turning point in human evolution," says Chazan. "The impact of cooking food is well documented, but the impact of control over fire would have touched all elements of human society. Socializing around a camp fire might actually be an essential aspect of what makes us human."
CHICAGO - Studies exploring the relationship between soy consumption and breast cancer have been mixed, but new research introduces a new thought: Could women with breast cancer who began eating soy as an adult develop a tumor more resistant to treatment? That's the suggestion of a new study in animal models that could provide important hints for women with breast cancer who eat soy. The research from Georgetown Lombardi Comprehensive Cancer Center was reported today at the American Association for Cancer Research (AACR) Annual Meeting 2012. For tumors that are sensitive to hormonal treatment (estrogen receptor and/or progesterone receptor positive), tamoxifen is often given after primary treatment to keep the cancer at bay. Unfortunately, many tumors become resistant to the tamoxifen --meaning the drug stops working and the cancer grows again. In the new research conducted in the laboratories of Leena Hilakivi-Clarke, PhD and Robert Clarke, PhD, DSc, both professors of oncology at Georgetown Lombardi, researchers looked at the impact soy consumption might have on breast tumors. For the study, female rats were fed soy isoflavone genistein (a estrogen-like compound in soy) at various points in their lifetime. At adulthood, all rats were exposed to a substance that triggered mammary tumors to develop and then given tamoxifen. The study groups were as follows: one group was never fed genistein until tamoxifen was started; a second group was fed genistein only in youth and not again until tamoxifen was started; a third group was fed genistein only as adults and continued after tamoxifen was given; and finally, a fourth group was fed genistein during youth and adulthood and continued after tamoxifen was given. "Genistein intake in adult life which continues during tamoxifen treatment appears to make the tumors resistant to tamoxifen," explains Hilakivi-Clarke, the study's senior author. "However, if animals were fed genistein during childhood, and intake continues before and after tumors develop, the tumors are highly sensitive to the tamoxifen," she explains. "These results suggest that western women who started soy intake as adults, should stop if diagnosed with breast cancer," Clarke concludes. The research was presented by the abstract’s lead author Xiyuan Zhang, M.S. Other authors include Anni Warri, Ph.D., Idalia M. Cruz, and Katherine Cook, Ph.D. The research was funded by the National Cancer Institute. The authors report having no personal financial interests related to the study. http://www.sciencedaily.com/releases/2012/04/120402144738.htm How Do I Love Me? Let Me Count the Ways, and Also Ace That Interview The secret to excelling in a job interview may not hinge on how much your interviewers like you, but in how much you like yourself. ScienceDaily - Narcissism, a trait considered obnoxious in most circumstances, actually pays off big-time in the short-term context of a job interview, according to a new study to be published in the Journal of Applied Social Psychology. Narcissists scored much higher in simulated job interviews than non-narcissists, researchers found. They pointed to narcissists' innate tendency to promote themselves, in part by engaging and speaking at length, which implied confidence and expertise even when they were held to account by expert interviewers. "This is one setting where it's OK to say nice things about yourself and there are no ramifications. In fact, it's expected," said Peter Harms, assistant professor of management at the University of Nebraska-Lincoln and a co-author of the study. "Simply put, those who are comfortable doing this tend to do much better than those who aren't." The two-part study examined the effectiveness of the types of behaviors that narcissists exhibit - which would be typically seen as maladjusted - in the narrow context of an interview. In the first part, 72 participants were videotaped in a simulated job-applicant setting. As expected narcissists were more likely to self-promote; however, it was when expert interviewers challenged applicants that narcissists started behaving in unexpected ways, Harms said. While normal individuals backed off of their self-promotion tactics when held accountable, narcissists actually increased their attempts to make themselves look better. "When feeling challenged, they tend to double down," Harms said. "It's as if they say 'Oh, you're going to challenge me? Then I'm not just great, I'm fantastic.' And in this setting, it tended to work." In the study's second part, 222 raters evaluated videos of applicants with similar job skills and varying levels of narcissism. The raters consistently awarded chronic self-promoters -- who spoke quickly and at length and who used ingratiation tactics such as smiling, gesturing and complimenting others -- far more positive evaluations. Meanwhile, equally qualified applicants who tended to rely on tactical modesty scored lower, according to the study. "This shows that what is getting (narcissists) the win is the delivery," Harms said. "These results show just how hard it is to effectively interview, and how fallible we can be when making interview judgments. We don't necessarily want to hire narcissists, but might end up doing so because they come off as being self-confident and capable." For interviewers, the study's findings mean they must become aware of the tactics used by narcissists, Harms said -- and, if necessary, avoid selecting people who chronically use self-promotion and ingratiation, unless those behaviors are appropriate for the position. "On the whole, we find very little evidence that narcissists are more or less effective workers. But what we do know is that they can be very disruptive and destructive when dealing with other people on a regular basis. If everything else is equal, it probably is best to avoid hiring them." In addition to UNL's Harms, the study was authored by Delroy L. Paulhus, Bryce G. Westlake and Stryker S. Calvez of the University of British Columbia. http://nyti.ms/HKJmJN Yüklə 205,91 Kb. Dostları ilə paylaş:
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