昌吉做个无痛人流手术需要多少钱(昌吉医院男人精子检查) (今日更新中)

BEIJING, June 14 (Xinhuanet) -- Having a pet at home during the first year of a child may halve the risk of developing allergic to them later in life, a new study suggests.The study was published in the journal Clinical & Experimental Allergy.Researchers from Henry Ford Hospital in Detroit assessed 566 boys and girls who were followed from birth until age 18. They found that boys who had dogs and teens who had cats during their first year of life had 50 percent less risk of developing pet allergies later.Lead researcher Ganesha Wegienka said: "This research provides further evidence that experiences in the first year of life are associated with health status later in life, and that early life pet exposure does not put most children at risk of being sensitised to these animals later in life."The researchers said that exposure to animals at other times in childhood didn't appear to be as significant as the first year.However, Wegienka cautioned that this study doesn't prove a cause-and-effect relationship between having a pet and avoiding allergies, just an association between those two factors."We don't want to say that everyone should go out and get a dog or cat to prevent allergies," she said."More research is needed, though we think this is a worthwhile avenue to pursue."

RIO DE JANEIRO, Aug. 31 (Xinhua) -- The Brazilian city of Rio de Janeiroe may have an unprecedented dengue fever epidemic next summer, its mayor warned on Wednesday.The increasing number of dengue fever cases in the past few months shows similarities to the months predecing the 2002 and 2008 epidemics, Mayor Eduardo Paes said."Everything points to a new cycle of the disease, certainly the worst epidemic in Rio's history," he said.In 2008, Rio registered some 250,000 cases of dengue fever, with 174 people confirmed dead from the disease. In 2002, Rio had some 290,000 dengue fever cases and 91 people died.In efforts to halt the spread of the disease, Paes has declared a state of alert and is determined to take a series of measures to eliminate the habitat of the Aedes aegypti mosquito, which transmits dengue fever through its bite.Paes also announced an increase in the number of health care units for dengue fever patients. The total cost of a dengue prevention and combat program, which is expected to last until April 2012, will reach 42 million reais (26.25 million U.S. dollars).There is no vaccine against dengue fever, but Brazilian scientists are currently working on one which will immunize against four types of the disease.

WASHINGTON, Aug. 31 (Xinhua) -- Astronomers using NASA's Chandra X-ray Observatory discovered the first pair of supermassive black holes in a spiral galaxy similar to the Milky Way, NASA announced Wednesday.Approximately 160 million light years from Earth, the pair is the nearest known such phenomenon.The black holes are located near the center of the spiral galaxy NGC 3393. Separated by only 490 light years, the black holes are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago.Both of the supermassive black holes are heavily obscured by dust and gas, which makes them difficult to observe in optical light. Because X-rays are more energetic, they can penetrate this obscuring material. Chandra's X-ray spectra show clear signatures of a pair of supermassive black holes."If this galaxy weren't so close, we'd have no chance of separating the two black holes the way we have," said Pepi Fabbiano of the Harvard-Smithsonian Center for Astrophysics, who led the study that appeared Wednesday in on-line issue of the journal Nature. "Since this galaxy was right under our noses by cosmic standards, it makes us wonder how many of these black hole pairs we've been missing."Previous observations in X-rays and at other wavelengths indicated that a single supermassive black hole existed in the center of NGC 3393. However, a long look by Chandra allowed the researchers to detect and separate the dual black holes. Both black holes are actively growing and emitting X-rays as gas falls towards them and becomes hotter.When two equal-sized spiral galaxies merge, astronomers think it should result in the formation of a black hole pair and a galaxy with a disrupted appearance and intense star formation. A well-known example is the pair of supermassive black holes in NGC 6240, which is located about 330 million light years from Earth.However, NGC 3393 is a well-organized spiral galaxy, and its central bulge is dominated by old stars. These are unusual properties for a galaxy containing a pair of black holes.

BEIJING, Aug. 2 (Xinhuanet) -- The first close-up pictures of the asteroid Vesta, a protoplanet that dates back to the early days of the solar system, were revealed Monday by NASA scientists.The images were taken by the U.S. space agency's Dawn robotic probe, which is two weeks into a planned year-long survey of the second largest object in the main asteroid belt, located between Mars and Jupiter.About twice the size of California, Vesta is second in size only to Ceres, Dawn's next target and, along with Pluto, one of just five known dwarf planets. NASA is spending 466 million dollars to explore Vesta and Ceres during the course of a 10-year mission.Images from Dawn show Vesta a surprisingly diverse terrain and several unexplained geologic features. Chaotic terrain near the south pole is dominated by a towering central peak and huge ripple-like grooves stretching around its equatorial belt. Bright spots, dark pits and craters are filled with unexplained streaks of black and white debris. Terrain north of the grooves is much more heavily cratered.Scientists believe Vesta grew from a clump of gas and dust left over after the sun's birth some 4.65 billion years ago, a supernova explosion, which added radioactive materials to the growing body.Dawn will spend about a year circling Vesta, tweaking its orbit and altitude using an innovative technology called ion propulsion system, chief engineer Marc Rayman with NASA's Jet Propulsion Laboratory in California said.The ion propulsion system will enable Dawn to leave Vesta's orbit after a year of study and head off to Ceres, which is the largest object in the asteroid belt.

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