中山市知名肛肠医院(中山痔疮手术住院费用) (今日更新中)

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.

WASHINGTON, Aug. 10 (Xinhua) -- After a journey of almost three years, NASA's Mars rover Opportunity has reached the Red Planet's Endeavour crater to study rocks never seen before, the U.S. National Aeronautics and Space Administration (NASA) announced on Wednesday.Scientists hope it will find rocks and terrain much older than any other that the itinerant robot has examined during its seven years on the red planet.The U.S. space agency said that Opportunity arrived at the rim of Endeavour on Tuesday. The golf cart-size rover is expected to remain at the 22-kilometer-wide crater for the next few years.A portion of the west rim of Endeavour crater sweeps southward in this color view from NASA's Mars Exploration Rover Opportunity."NASA is continuing to write remarkable chapters in our nation' s story of exploration with discoveries on Mars and trips to an array of challenging new destinations," NASA Administrator Charles Bolden said in a statement. "Opportunity's findings and data ... will play a key role in making possible future human missions to Mars and other places where humans have not yet been."NASA's Mars Reconnaissance Orbiter, which has been circling the planet since late 2005, detected clay minerals that form in wet conditions in the crater. Scientists want to find out if the minerals date back to Mars' distant past, when the planet is believed to have been wetter and warmer than the dry frozen desert it is today."We're soon going to get the opportunity to sample a rock type the rovers haven't seen yet," said Matthew Golombek, Mars Exploration Rover science team member, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Clay minerals form in wet conditions so we may learn about a potentially habitable environment that appears to have been very different from those responsible for the rocks comprising the plains."NASA is searching for signs that Mars had a habitable environment billions of years ago. Knowledge of the Martian climate will be important to future manned missions there, and can shed light on the forces that shaped Earth's climate.NASA launched the Mars rovers Opportunity and Spirit in 2003 for what were planned to be three-month missions. But both continued operating well beyond that. Spirit stopped communicating in March 2010.

XICHANG, Sichuan, Aug. 12 (Xinhua) -- China launched a communications satellite PAKSAT-1R for Pakistan at 0:15 a.m. Friday from the Xichang Satellite Launch Center in southwest China's Sichuan Province.The satellite was carried by a Long March-3B carrier rocket, according to the launch center. It is China's first in-orbit delivery to Asian customers and also the first commercial satellite export to international users this year.According to statistics from the control center, the satellite successfully separated from its carrier rocket and entered geostationary transfer orbit as scheduled, 26 minutes after being launched.PAKSAT-1R will provide a range of services, including broadband Internet, telecom and broadcasting, covering some regions of Europe, South Asia, the Middle East, and the eastern Africa.The contract for the PAKSAT-1R was signed in 2008 between China Great Wall Industry Corporation and the Space and Upper Atmosphere Research Commission of Pakistan.China and Pakistan share a long history of space technology cooperation. Pakistan's first low-orbit satellite, BADR-A, was launched by China in 1990 with Long March 2E rocket.

MOSCOW, Aug. 30 (Xinhua) -- Russia's space agency said Tuesday that a Proton-M rocket launch failed earlier this month because of a malfunction in the upper stage.The conclusion was reached by an independent investigation commission following a series of checks, Roscosmos said in a report that was posted on its website."The commission reported that the time span reserved for the gyrostabilized platform's turn was miscalculated and narrowed, which caused the Briz-M upper stage's disorientation and the satellite's journey to a wrong orbit," the agency said.Other systems in the upper stage performed well, the agency said, adding it has lifted a ban on launches of the Proton-M carrier rockets equipped with the Briz-M upper stage.Local media reported the Briz-M, manufactured by the Khrunichev State Research and Production Space Center, has had five failures over its 12-year history of operation.On Aug. 18, a Proton-M carrier rocket failed to deliver a communications satellite into orbit. After the failure, Russia suspended launches of Proton-M rockets pending the outcome of an investigation into the failure.

SHANGHAI, July 19 (Xinhua) -- Baidu Inc., the largest Chinese search engine based in Beijing, said Tuesday it closed a deal that allows the company to provide download services of music from Universal Music, Warner Music and Sony Music.According to the deal signed between Baidu and One Stop China (OSC), a joint venture of the three music companies, Baidu will pay them on a per-play and per-download basis for all tracks delivered through its MP3 server, said a press release provided by Baidu.Users can have access to the authorized music free of charge, and Chinese songs, both in Mandarin and Cantonese, and some global content provided by the three music companies will be included in the catalogue.Baidu also launched a social music platform called "Baidu ting!" through which users can obtain and share some music-related information and content.Li Xinzhe, CFO of Baidu, described the deal as a "milestone" that can benefit not only Baidu and its partners but also music lovers and the privacy-stricken industry.Wang Bin, secretary general of Copyright Union of Internet Society of China, predicted that it would have a demonstrative effect on the Internet sector.In 2008, Universal, Warner and Sony Music sued Baidu for at least 63.5 million yuan (9.8 million U.S. dollars) in copyright infringement.

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