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SAN FRANCISCO, July 15 (Xinhua) -- U.S. microblogging platform Twitter on Friday marked its fifth anniversary since public debut."Twitter, then called Twttr, opened to the public five years ago today," the company said in a Tweet, a short message within 140 characters users are allowed to communicate on the website."Twttr is a new mobile service that helps groups of friends bounce random thoughts around with SMS," co-founder Biz Stone described the service in a blog post on July 13, 2006, two days before its public debut."There were 224 Tweets sent on July 15, 2006. Today, users send that many Tweets in less than a tenth of a second," said the San Francisco-based company.Twitter said more than 600,000 new users signed up on Thursday while it took it more than 16 months to reach the first 600,000 Twitter accounts.The tipping point for the service's popularity was the 2007 South by Southwest festival, a set of film, interactive and music festivals and conferences that take place every March in Austin, Texas. During the event, the Tweets sent per day grew from 20,000 to 60,000.With an estimated user base of 200 million worldwide, some 200 million Tweets are generated and 1.6 billion search queries are handled every day, the company said.According to research firm EMarketer, advertising sales on Twitter is expected to reach 150 million U.S. dollars this year. SharesPost, a secondary market for privately held companies, has assessed Twitter's current worth at 6.8 billion dollars.

LOS ANGELES, July 22 (Xinhua) -- Two teams of astronomers have discovered the largest and farthest reservoir of water ever detected in the universe, NASA's Jet Propulsion Laboratory (JPL) said on Friday.The water, equivalent to 140 trillion times all the water in the world's ocean, surrounds a huge, feeding black hole, called a quasar, more than 12 billion light-years away, according to JPL in Pasadena, California."The environment around this quasar is very unique in that it's producing this huge mass of water," said Matt Bradford, a scientist at JPL. "It's another demonstration that water is pervasive throughout the universe, even at the very earliest times. "This artist's concept illustrates a quasar, or feeding black hole, similar to APM 08279+5255, where astronomers discovered huge amounts of water vapor. Gas and dust likely form a torus around the central black hole, with clouds of charged gas above and below. X-rays emerge from the very central region, while thermal infrared radiation is emitted by dust throughout most of the torus. While this figure shows the quasar's torus approximately edge-on, the torus around APM 08279+5255 is likely positioned face-on from our point of view.A quasar is powered by an enormous black hole that steadily consumes a surrounding disk of gas and dust. As it eats, the quasar spews out huge amounts of energy. Both groups of astronomers studied a particular quasar called APM 08279+5255, which harbors a black hole 20 billion times more massive than the sun and produces as much energy as a thousand trillion suns.Astronomers expected water vapor to be present even in the early, distant universe, but had not detected it this far away before. There's water vapor in the Milky Way, although the total amount is 4,000 times less than in the quasar, because most of the Milky Way's water is frozen in ice. Water vapor is an important trace gas that reveals the nature of the quasar. In this particular quasar, the water vapor is distributed around the black hole in a gaseous region spanning hundreds of light-years in size (a light-year is about six trillion miles).Its presence indicates that the quasar is bathing the gas in X- rays and infrared radiation, and that the gas is unusually warm and dense by astronomical standards, JPL said.Although the gas is at a chilly minus 63 degrees Fahrenheit ( minus 53 degrees Celsius) and is 300 trillion times less dense than Earth's atmosphere, it's still five times hotter and 10 to 100 times denser than what's typical in galaxies like the Milky Way, said JPL.Measurements of the water vapor and of other molecules, such as carbon monoxide, suggest there is enough gas to feed the black hole until it grows to about six times its size, JPL said.Whether this will happen is not clear, the astronomers say, since some of the gas may end up condensing into stars or might be ejected from the quasar.Bradford's team made their observations starting in 2008, using an instrument called "Z-Spec" at the California Institute of Technology's (Caltech's) Submillimeter Observatory, a 33-foot (10- meter) telescope near the summit of Mauna Kea in Hawaii. Follow-up observations were made with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), an array of radio dishes in the Inyo Mountains of Southern California.The second group, led by Dariusz Lis, senior research associate in physics at Caltech and deputy director of the Caltech Submillimeter Observatory, used the Plateau de Bure Interferometer in the French Alps to find water. In 2010, Lis's team serendipitously detected water in APM 8279+5255, observing one spectral signature.Bradford's team was able to get more information about the water, including its enormous mass, because they detected several spectral signatures of the water, according to JPL.

BEIJING, June 26 (Xinhua) -- China on Sunday issued a regulation on drug rehabilitation that encourages drug users to voluntarily undergo rehabilitation programs.The regulation took effect Sunday as a supplement of the country's anti-drug law that was implemented three years ago.Drug users who voluntarily receive intervention programs "will be exempt from punishment," said the regulation, promulgated on the 24th International Day Against Drug Abuse and Illicit Trafficking, which falls on Sunday.With seven chapters and 46 articles, it also stipulates the rights and obligations of drug addicts, as well as supporting measures for voluntary, community-based, and government-ordered drug rehabilitation.Up to date, more than two million Chinese have been receiving compulsive rehabilitation or treatment, statistics show. However, many of them find it difficult to completely give up the addiction.The regulation, aiming to explore effective ways to curb drug use, calls for boosting "the role of communities and families" in helping reduce drug users' dependency on narcotics.It asks rehabilitation centers to provide addicts with consulting services and education on the prevention of HIV/AIDS and other contagious diseases.Efforts should be made to "boost pharmaceutical management" so as to prevent loss or abuse of psychotropic substances and narcotics, the regulation says.The regulation also stipulates on the protection of drug addicts' personal information, saying "members of the police, judiciary and health departments who cause the leak of personal information must be punished."The regulation has solicited public comments before it was released.Transnational drug trafficking remains rampant in China, particularly in southwestern border regions of Yunnan and Guangxi.A report issued last month by China's National Narcotics Control Commission said authorities investigated 89,000 drug-related crimes and arrested 101,000 suspects last year.Law enforcers confiscated 5.3 metric tonnes of heroin and one metric tonne of opium in 2010, the report said, adding that intervention programs were used to treat and rehabilitate some 175,000 drug addicts last year.

WASHINGTON, July 8 (Xinhua) -- U.S. President Barack Obama on Friday hailed space shuttle Atlantis' final flight in NASA's shuttle program, saying Americans across the country watched with pride as America reached for the heavens once more.Obama expressed his "sincere gratitude" to Atlantis astronauts and space workers because they "helped our country lead the space age.""Today's launch may mark the final flight of the space shuttle, " Obama said in a statement. "But it propels us into the next era of our never-ending adventure to push the very frontiers of exploration and discovery in space."Friday's flight is the 33rd voyage for Atlantis. Its return to the earth later this month will mark the end of the 30-year shuttle program."What a truly awesome day today," said NASA Associate Administrator for Space Operations Bill Gerstenmaier at the STS- 135 postlaunch news conference. "What you saw is the finest launch team and shuttle preparation teams in the world.""It truly was an awesome, spectacular launch," added Kennedy Space Center Director Bob Cabana, who looked ahead to plans for future development beyond the shuttle program as space station operations continue.Atlantis will be the last shuttle to be retired. Discovery was first in March, followed by Endeavour at the beginning of June. Each shuttle will head to a museum.When the U.S. space shuttle program officially ends later this year, the Russian space program's Soyuz capsule will be the only method for transporting astronauts to and from the station.

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