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BEIJING, June 29 (Xinhuanet) -- Twitter Inc. co-founders Biz Stone and Evan Williams said they are moving on from the microblogging service, media reports said Wednesday.“The Twitter crew and its leadership team have grown incredibly productive,” Stone said on the blog. “I’ve decided that the most effective use of my time is to get out of the way until I’m called upon to be of some specific use.”The two will continue to advise Twitter on strategic matters, but devote the lions' share of their time to The Obvious Corporation, Stone said.Obvious was first created by Williams to buy back a company from investors that he and Stone failed to sell about six years ago, Stone said. The two began working together after leaving Google in 2005.The company will also be run by Jason Goldman, a former Twitter executive, Stone said.

LOS ANGELES, June 3 (Xinhua) -- Eating earth may protect the stomach against toxins, parasites and pathogens, a new study suggests.To examine the possible benefits from eating earth, researchers at Cornell University analyzed reports from missionaries, plantation doctors, explorers, and anthropologists to put together a database of more than 480 cultural accounts of geophagy -- the eating of earth.The database includes as many details as possible about the circumstances under which earth was consumed, and by whom. The researchers could then use patterns in the data to evaluate each potential explanation.Studies in the database indicate that geophagy is common even when food is plentiful. Moreover, when people eat dirt they tend to eat only small quantities that are unlikely to fill an empty stomach.The database shows that geophagy is documented most commonly in women in the early stages of pregnancy and in pre-adolescent children. Both categories of people are especially sensitive to parasites and pathogens, according to the researchers.In addition, geophagy is most common in tropical climates where foodborne microbes are abundant. Finally, the database shows that people often eat earth during episodes of gastrointestinal stress.It's unlikely the intestinal problems are caused by the dirt itself because the type of clay people usually eat comes from deep in the ground, where pathogens and parasites are unlikely to contaminate it. Plus, people usually boil the clay before eating it.More study would be helpful to confirm the protection hypothesis, the researchers say, but the available data at this point clearly support it over the other explanations for eating earth."We hope this paper stimulates (more) research," said Sera Young, a researcher at Cornell University and the study's lead author. "More importantly, we hope readers agree that it is time to stop regarding geophagy as a bizarre, non-adaptive gustatory mistake.""With these data, it is clear that geophagy is a widespread behavior in humans ...that occurs during both vulnerable life stages and when facing ecological conditions that require protection."The study is appearing in the June issue of The Quarterly Review of Biology.

PHNOM PENH, Aug. 17 (Xinhua) -- The critically endangered Irrawaddy dolphin population in the Mekong River numbers just 85, World Wildlife Fund (WWF) new research revealed on Wednesday.Calf survival was found to be very low, leading researchers to conclude that the small population is declining and at high risk of extinction, said the Fund's statement sent to Xinhua News Agency on Wednesday.According to Li Lifeng, Director of WWF's Freshwater Program, the research is based on photographic identification of dolphins through individually unique features of their dorsal fins. "Most of the dolphins can be identified, and we use that information to estimate the population size," he said.Although this population estimate is slightly higher than the previous estimate, the researchers were quick to note that the population had not increased over the last few years."With a larger dataset and recent analytical advances, previously unidentifiable dolphins which had few marks on their dorsal fins have been included," he added.However, surveys conducted from 2007 to 2010 show the population slowly declining."Evidence is strong that very few young animals survive to adulthood, as older dolphins die off and are not replaced," he explained."Pressures of gill net entanglement and high calf mortality we are really worried for the future of dolphins," Li said.However, Touch Seang Tana, chairman of Cambodia's Commission for Conversation and Development of the Mekong River Dolphins Eco- tourism Zone, rejected the WWF's finding, saying that last year, 4 dolphins were killed by fishing nets, but up to 7 newborn dolphin babies were found.He estimated that the total population of Mekong dolphins in the north-eastern provinces of Kratie and Stung Treng is between 155 and 177 now, up from just 100 in 2006.The Mekong River Irrawaddy dolphin has been listed as critically endangered on the World Conservation Union Red List of Threatened Species since 2004.

CANBERRA, Sept. 6 (Xinhua) -- A rare virus that can be contracted by humans has killed a large number of Victorian pigeons after being detected in the Australian state for the first time, Agriculture Department confirmed on Tuesday.According to the Australian Chief Veterinary Officer, Dr Mark Schipp, the avian paramyxo virus has already started killing some hobby birds, and threatens to spread to Victoria's chicken population.He said the affected birds have died suddenly in large numbers and have sometimes appeared tired or have shown neurological signs such as circling or head flicking before death.He added that the bug can also cause conjunctivitis or influenza-like symptoms in humans."The virus causes only mild, short-term conjunctivitis or influenza-like symptoms (in humans)," Australia Associated Press quoted Schipp as reporting on Tuesday."Human infection with this virus is extremely rare and usually occurs only in people who have close direct contact with infected birds."At this stage, there are no reports of the virus causing disease in wild birds, but the Australian Wildlife Health Network has been asked to monitor the situation.

LOS ANGELES, July 18 (Xinhua) -- The spacecraft Dawn of the National Aeronautics and Space Administration (NASA) has returned the first close-up image of the giant asteroid Vesta after entering its orbit for the first time last week, the Jet Propulsion Laboratory (JPL) announced on Monday.The image taken for navigation purposes shows Vesta in greater detail than ever before, said JPL in Pasadena, California.On July 15, Dawn became the first probe to enter orbit around an object in the main asteroid belt between Mars and Jupiter.When Vesta captured Dawn into its orbit, there were approximately 9,900 miles (about 16,000 kilometers) between the spacecraft and the asteroid.Vesta is 330 miles (about 530 kilometers) in diameter and the second most massive object in the asteroid belt.NASA's Dawn spacecraft obtained this image with its framing camera on July 17, 2011. It was taken from a distance of about 9,500 miles (15,000 kilometers) away from the protoplanet Vesta. Each pixel in the image corresponds to roughly 0.88 miles (1.4 kilometers). Ground- and space-based telescopes have obtained images of Vesta for about two centuries, but they have not been able to see much detail on its surface."We are beginning the study of arguably the oldest extant primordial surface in the solar system," said Dawn principal investigator Christopher Russell from the University of California, Los Angeles, which is responsible for Dawn's mission science. " This region of space has been ignored for far too long. So far, the images received to date reveal a complex surface that seems to have preserved some of the earliest events in Vesta's history, as well as logging the onslaught that Vesta has suffered in the intervening eons."Vesta is thought to be the source of a large number of meteorites that fall to Earth. Vesta and its new NASA neighbor, Dawn, are currently approximately 117 million miles (about 188 million kilometers) away from Earth. The Dawn team will begin gathering science data in August.Observations will provide unprecedented data to help scientists understand the earliest chapter of the solar system and pave the way for future human space missions, according to JPL."Dawn slipped gently into orbit with the same grace it has displayed during its years of ion thrusting through interplanetary space," said Marc Rayman, Dawn chief engineer and mission manager at NASA's JPL. "It is fantastically exciting that we will begin providing humankind its first detailed views of one of the last unexplored worlds in the inner solar system."Although orbit capture is complete, the approach phase will continue for about three weeks. During approach, the Dawn team will continue a search for possible moons around the asteroid; obtain more images for navigation; observe Vesta's physical properties; and obtain calibration data.In addition, navigators will measure the strength of Vesta's gravitational tug on the spacecraft to compute the asteroid's mass with much greater accuracy than has been previously available, according to JPL.Dawn will spend one year orbiting Vesta, then travel to a second destination, the dwarf planet Ceres, arriving in February 2015. The mission to Vesta and Ceres is managed by JPL for the agency's Science Mission Directorate in Washington.Dawn is a project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alaska.