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WASHINGTON, Sept. 15 (Xinhua) -- A team of researchers has discovered a planet that orbits around a pair of stars, the U.S. space agency NASA announced Thursday.This is the first instance of astronomers finding direct evidence of a so-called circumbinary planet. A few other planets have been suspected of orbiting around both members of a dual-star system, but the transits of the circumbinary planet have never been detected previously.The team, led by Laurance Doyle of the SETI Institute in California, used photometric data from the NASA Kepler space telescope, which monitors the brightness of 155,000 stars.NASA's Kepler mission has discovered a world where two suns set over the horizon instead of just one. The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy. Tatooine is the name of Luke Skywalker's home world in the science fiction movie Star Wars. In this case, the planet it not thought to be habitable. It is a cold world, with a gaseous surface, but like Tatooine, it circles two stars.They found the binary star system by detecting a system where the stars eclipsed each other from the perspective of the Kepler spacecraft. These stars have two eclipses: A primary eclipse when the larger star is partially blocked by the smaller star and a secondary eclipse where the smaller star is fully blocked by the larger star.But the researchers also noticed other times when the brightness of the two stars dropped, even when they were not in an eclipse position. This pattern suggested that there was likely a third object involved. The fact that these so-called tertiary and quaternary eclipses recurred after varying intervals of time, and were of different depths, indicated that the stars were in different positions in their orbit at each instance. This result showed that the tertiary and quaternary eclipses were being caused by something circling both stars, and not an object circling one or the other star.Measurements of the variations in the timing of all four types of eclipses, resulting from the mutual gravitational interactions of the two stars and the third body, demonstrated that the third object was, indeed, a planet. Their work indicates that the planet is less massive than Jupiter, possibly comparable in mass to Saturn, and that the larger of the two binary stars is smaller than our Sun.Their findings will be published Friday in Science."This discovery confirms a new class of planetary systems that could harbor life," Kepler principal investigator William Borucki said in a statement. "Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now."

CANBERRA, Sept. 23 (Xinhua) -- A genetic study on Friday found Aboriginal Australians are descended from the first people to leave Africa up to 75,000 years ago.Researchers from the University of Western Australia, Murdoch University and an international team analyzed genetic material of a 100-year-old West Australian Aboriginal man's hair, and found he was directly descended from a migration out of Africa into Asia.The study revealed that Australian Aboriginal ancestors split from the first modern human populations to leave Africa, between 64,000 and 75,000 years ago, at least 24,000 years before other human migrations.According to Dr. Joe Dortch, an archaeologist at the University of Western Australia, the discovery rewrites the history of the human species by confirming humans moved out of Africa in waves of migrations rather than in one single out-of-Africa diaspora.It also rewrites the story about how Aborigines arrived in Australia some 50,000 years ago."So far there are no [archaeological] sites that are over 50, 000 years old so it puts a time limit on that and focuses our future efforts," he said in a statement released on Friday.Dr. Dortch believes the finding will foster a sense of pride in modern Australian Aborigines."No-one else in the world can say 'I am descended from people who have been here 75,000 years'."Associate Professor Darren Curnoe, leader of the Human Evolutionary Biology Lab in the School of Biological, Earth & Environmental Sciences at the University of New South Wales, said the study powerfully confirms that Aboriginal Australians are one of the oldest living populations in the world, certainly the oldest outside of Africa."Australians are truly one of the world's great human populations and a very ancient one at that, with deep connections to the Australian continent and broader Asian region. About this now there can be no dispute," he told Xinhua in an email note.Meanwhile, Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, said while this is a major step forward, the key unresolved question remains the unique story of Aboriginal history within Australia, such as what has happened in those 50,000 years of life in the harsh Australian environment."Unfortunately, the information from a single individual tells us very little about this fascinating, and critically important part of human history. Aborigines are one of the oldest continuous human populations outside Africa, as they note in the paper, and due to the geographic isolation and limited archaeological records remain one of the most mysterious chapters in human history," he told Xinhua on Friday.The study is published on Friday in the journal Science.Indigenous Australians are the original inhabitants of the Australian continent and nearby islands. They together make up more than 2.5 percent of Australia's population.

BEIJING, August 23 (Xinhuanet) -- In the U.S., the rate of injuries related to children and teens falling out of windows declined over a 19-year period, although not nearly as fast as in some cities with comprehensive prevention programs, researchers found.From 1990 to 2008, the overall rate of injuries in children and teens was 7.3 per 100,000 per year, going as high as 11.4 in 1992 and as low as 5.8 in 1999, according to Gary Smith, MD, DrPh, of the Research Institute at Nationwide Children's Hospital in Columbus, Ohio, and colleagues.The annual rate of injuries fell slightly but significantly over the study period, driven entirely by a reduction of 0.426 cases per 100,000 per year in children up to age four, the researchers reported online ahead of the September issue of Pediatrics.That is much less than the reduction seen in previous studies of fall prevention programs in New York City and Boston, which achieved declines of up to 96 percent during a 10-year period through education, increased access to window guards, and a mandate to use window guards in certain homes (only in New York City)."The slower decrease followed by a plateau in injury rates found in this study underscores the fact that prevention efforts of the magnitude undertaken in New York and Boston have not occurred nationwide," Smith and hiscolleagues wrote.The researchers also acknowledged that the study underestimated the number of injuries related to falling out of a window because it included only those children treated in emergency rooms. An additional limitation is that the case narratives often lacked details about the circumstances surrounding the injury, including any suicidal intent.

BEIJING, Aug. 13 (Xinhua) -- The quality of the products China exported to the European Union (EU) improved during the first half of this year due to strict quality control measures, according to quality control authorities.The number of quality complaints made by the EU regarding Chinese imports declined by 45 percent in the first half of 2011, according to the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ).The administration attributed the improved quality to its nationwide crackdown on counterfeited and substandard products.The administration launched a nationwide quality checkup in the first half of this year. Of the 4,815 batches of products that the quality control authorities checked between January and June, just 9.4 percent failed quality tests, 1.7 percentage points lower than that of the same period of last year, according to the administration.A total of 218,000 counterfeiting cases have been investigated so far this year, involving goods worth a total of 9.5 billion yuan (1.49 billion U.S. dollars), the administration said.