中山便血医院怎样(中山长痔疮症状) (今日更新中)

BEIJING, Aug. 22 (Xinhuanet) -- Researchers have discovered how a human egg captures an incoming sperm for fertilization, paving the way to help couples suffering from infertility, according to media reports on Monday.An international team of researchers found that a sugar chain known as the sialyl-lewis-x sequence (SLeX) makes the outer coat of the egg “sticky,” which has proven to be helpful in binding the egg and the sperm.As a result, this observation has filled in a huge gap in the understanding of fertility and provides hope for ultimately helping couples who currently cannot conceive.Scientists and doctors know that a sperm identifies an egg when proteins on the head of the sperm match and bind to a series of specific sugars in the egg’s outer coating. With a successful match of proteins, the outside surfaces of the sperm and egg then bind together before merging, which is then followed by delivery of sperm’s DNA into egg.To identify this molecules, the researchers used ultra-sensitive mass-spectrometric imaging technology to observe and identify which molecules are most likely to be key in the binding process.They experimented with a range of synthesised sugars in the laboratory and found that it is SLeX that specifically binds sperm to an egg.According to the World Health Organisation, infertility affects about 15 percent of reproductive-aged couples around the world and almost one in every seven couples in Britain has problems conceiving a child for various reasons.

WASHINGTON, June 15 (Xinhua) -- Using the deepest X-ray image ever taken, astronomers found the first direct evidence that massive black holes were common in the early universe, the U.S. National Aeronautics and Space Administration (NASA) said Wednesday in a statement.The discovery from NASA's Chandra X-ray Observatory shows that very young black holes grew more aggressively than previously thought, in tandem with the growth of their host galaxies.By pointing Chandra at a patch of sky for more than six weeks, astronomers obtained what is known as the Chandra Deep Field South (CDFS). When combined with very deep optical and infrared images from NASA's Hubble Space Telescope, the new Chandra data allowed astronomers to search for black holes in 200 distant galaxies, from when the universe was between about 800 million to 950 million years old."Until now, we had no idea what the black holes in these early galaxies were doing, or if they even existed," said Ezequiel Treister of the University of Hawaii, lead author of the study to appear Thursday in journal Nature. "Now we know they are there, and they are growing like gangbusters."The super-sized growth means that the black holes in the CDFS are less extreme versions of quasars -- very luminous, rare objects powered by material falling onto supermassive black holes. However, the sources in the CDFS are about a hundred times fainter and the black holes are about a thousand times less massive than the ones in quasars.The observations found that between 30 and 100 percent of the distant galaxies contain growing supermassive black holes. Extrapolating these results from the small observed field to the full sky, there are at least 30 million supermassive black holes in the early universe. This is a factor of 10,000 larger than the estimated number of quasars in the early universe."It appears we've found a whole new population of baby black holes," said co-author Kevin Schawinski of Yale University. "We think these babies will grow by a factor of about a hundred or a thousand, eventually becoming like the giant black holes we see today almost 13 billion years later."

SAN FRANCISCO, Sept. 9 (Xinhua) -- AOL's chief executive officer (CEO) Tim Armstrong has reached out to Yahoo for talks of a merger of the two companies, U.S. media reported on Friday.Armstrong is discussing options for a combination aimed at strengthening the two Internet companies, Bloomberg quoted two people who are familiar with the matter as saying.The report said that the AOL CEO had been interested in a merger with Yahoo last year but was rejected while Carol Bartz served as Yahoo CEO, who was ousted by Yahoo's board on Tuesday.Reconsidering the option after Bartz's departure, Armstrong has talked with private equity firms and investment bankers from Allen & Co. working with Yahoo.Under one scenario being considered, Yahoo would acquire AOL and Armstrong would become CEO of the combined company, said the source.Both Yahoo and AOL are suffering from declining revenues, struggling to compete against companies like Google and Facebook. Some analysts said that the merger could not provide a long-term solution to the problems the two companies face after they failed to keep up with Internet trends.

SAN FRANCISCO, July 29 (Xinhua) -- Apple has ousted Nokia as the world's largest smartphone maker as global mobile phone market grew more than 11.3 percent in the second quarter of 2011, according to two separate market research studies.After becoming the largest smartphone vendor in terms of revenue and profits, Apple has become the world's largest smartphone vendor by volume with 18.5 percent market share, said the latest research from Strategy Analytics released on Friday.The Cupertino, California-based company sold 20.3 million iPhones in the second quarter,up 142 percent compared with the same period a year earlier.Samsung's shipments of 19.2 million units grew a huge 520 percent year over year, accounting for 17.5 percent global smartphone market share in the second quarter of 2011.Apple and Samsung overtook long-time volume leader Nokia for the two spots. The Finnish mobile phone giant accounted for 15.2 percent of global smartphone market share in the last quarter, which is less than half of what it was just one year earlier.In the second quarter of 2010, Nokia was the No.1 smartphone maker by volume in the world with 38.1 percent of market share. The industry is now waiting Nokia's pending transition to Windows Phone 7.According to a separate report by International Data Corporation (IDC) released on Thursday, the worldwide mobile phone market grew by 11.3 percent year over year in the second quarter of 2011 despite a decline of the feature phone market for the first time in almost two years.The feature phone market was down by 4 percent in the last quarter, said the IDC Worldwide Mobile Phone Tracker report. It noted that the decline in shipments was mainly in economically mature regions, such as the United States, Japan and Western Europe, as users making rapid transition to smartphones.The shrinking feature phone market had a great impact on some of the world's largest suppliers of mobile phones, such as Nokia, which is losing share in the feature phone category to low-cost suppliers, said the report.For the overall market, global mobile phone vendors shipped 365. 4 million units in the second quarter, compared to 328.4 million units in the same period last year, with Nokia still holding the top spot with a market share of 24.2 percent, followed by Samsung, LG Electronics, Apple and ZTE.But the 11.3 percent growth was lower than IDC's forecast for the quarter and also below the 16.8 percent growth in the first quarter of 2011.IDC said the feature phone forecast isn't expected to be any rosier in the future and the shipment growth of feature phones won 't exceed 1.1 percent in the coming years.

LOS ANGELES, June 20 (Xinhua) -- NASA's Cassini spacecraft has successfully completed its second-closest encounter with Saturn's icy moon Helene, beaming down raw images of the small moon, the Jet Propulsion Laboratory (JPL) said on Monday.At closest approach on June 18 Cassini flew within 4,330 miles (6,968 kilometers) of Helene's surface, the second closest approach to Helene of the entire mission, said JPL in Pasadena, Los Angeles.This flyby will enable scientists to finish creating a global map of Helene, so they can better understand the history of impacts to the moon and gully-like features seen on previous flybys, according to JPL.Passing from Helene's night side to the moon's sunlit side, Cassini also captured images of the Saturn-facing side of the moon in sunlight, a region that was only illuminated by sunlight reflected off Saturn the last time Cassini closely encountered with the moon in March 2010.The closest Helene encounter of the mission took place on March 10, 2010, when Cassini flew within 1,131 miles (1,820 kilometers) of the moon.The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL, while the imaging team is based at the Space Science Institute in Boulder, Colorado.

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