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WASHINGTON, July 20 (Xinhua) -- Using the Hubble Space Telescope, astronomers have discovered a fourth moon orbiting the icy dwarf planet Pluto, the U.S. National Aeronautics and Space Administration (NASA) announced Wednesday in a statement. The tiny, new satellite, temporarily designated P4, was uncovered in a Hubble survey searching for rings around the dwarf planet.P4 was first seen in a photo taken with Hubble's Wide Field Camera 3 on June 28. It was confirmed in subsequent Hubble pictures taken on July 3 and July 18. It is the smallest moon discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Charon, Pluto's largest moon, is 648 miles (1,043 km) across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter (32 to 113 km).Two labeled images of the Pluto system taken by the Hubble Space Telescope's Wide Field Camera 3 ultraviolet visible instrument with newly discovered fourth moon P4 circled. The image on the left was taken on June 28, 2011. The image of the right was taken on July 3, 2011."I find it remarkable that Hubble's cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km)," said Mark Showalter of the SETI Institute in California, who led this observing program with Hubble.P4 is located between the orbits of Nix and Hydra, which Hubble discovered in 2005. Charon was discovered in 1978 at the U.S. Naval Observatory and first resolved using Hubble in 1990 as a separate body from Pluto.The dwarf planet's entire moon system is believed to have formed by a collision between Pluto and another planet-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto.The finding is a result of ongoing work to support NASA's New Horizons mission, scheduled to fly through the Pluto system in 2015. The mission is designed to provide new insights about worlds at the edge of our solar system. Hubble's mapping of Pluto's surface and discovery of its satellites have been invaluable to planning for New Horizons' close encounter."This is a fantastic discovery," said New Horizons' principal investigator Alan Stern of the Southwest Research Institute in Colorado. "Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby."

WELLINGTON, June 7 (Xinhua) -- Scientists in New Zealand have developed a new drug to fight previously untreatable hypoxic cancer tumors, which form in areas of the body starved of oxygen.The researchers at the Auckland University have entered an agreement for the clinical development of CEN-209, which was developed over 10 years of research, said a statement from the university Tuesday.CEN-209 was designed to enhance the effectiveness of radiotherapy and chemotherapy in solid hypoxic tumors, which were resistant to standard cancer therapies, said the statement. In lung cancer patients for example, about half of tumors had hypoxic regions.The new drug worked by damaging the DNA of hypoxic cancer cells, while leaving normal, healthy tissues alone.CEN-209 was designed and created by researchers at the university's Auckland Cancer Society Research Centre (ACSRC), using computer models of drug transport within tumors to accurately predict the anti-tumor activity of the drugs."Our computer models of drug transport developed in-house allowed the synthetic chemists to test their design theories and considerably shortened the discovery process," said Associate Professor Michael Hay, who led the ACSRC research chemists."CEN-209 improves markedly on previous agents in this class in terms of its ability to penetrate tumors, and this is reflected by its improved activity in the laboratory, when combined with long or short courses of radiotherapy," said researcher Professor Bill Wilson.Under the agreement between the university's Auckland UniServices Ltd. and California-based Centella Therapeutics, Inc., a subsidiary of Varian Medical Systems, Inc., Centella will have exclusive rights to CEN-209, which it will develop and trial with Cancer Research UK.The work on CEN-209 is the culmination of a program initiated with funding from the U.S. National Cancer Institute, and more recently from the Maurice Wilkins Centre for Biodiscovery. Ongoing preclinical research on CEN-209 and a backup compound was funded by grants from the Auckland Medical Research Foundation, Genesis Oncology Trust and Health Research Council of New Zealand, said the statement.

BEIJING, July 19 (Xinhuanet) -- Lifestyle changes such as exercise, eating healthily and not smoking could reduce the chances of having Alzheimer’s disease by half, researchers said in a study quoted by news reports Tuesday.Hundreds of thousands of patients could potentially avoid the devastating illness by simply changing bad habits, according to the study published in the journal Lancet NeurologyFor the first time, scientists have calculated the extent to which certain lifestyle traits -- including lack of exercise, smoking and obesity -- all contributed to the disease.Researchers found that in the Western world, an inactive “couch potato” lifestyle was the most important possible cause.Smoking, obesity in middle-age, high blood pressure and diabetes all increased the risk as they cause damage to blood vessels in the brain, leading to death of brain cells. Together, the modifiable risk factors contributed to 50 percent of Alzheimer’s cases worldwide.The researchers want to carry out more work to find out how many people can prevent the disease by making small changes to their lifestyle.

TAIYUAN, June 18 (Xinhua) -- A Chinese medical university will join hands with the Massey University of New Zealand to set up a community clinic specializing in chronic diseases in north China's Shanxi Province.The community clinic in Taiyuan, the provincial capital city, will provide medical services to more than 7,500 residents in the city's Hanxiguandong community, Ma Qianjin, vice president of the Shanxi University of Traditional Chinese Medicine, said on Friday.Residents will be able to seek advice from both Chinese and New Zealand experts on how to prevent chronic diseases like diabetes, said Ma.The clinic, which is expected to open this year, will also provide residents with free health check-ups and create health records for them.Bruce Ullrich, a Massey University board member, said on Friday that the clinic will integrate Western service with traditional Chinese medical techniques in its prevention and treatment of chronic diseases."The community clinic will mainly focus on people with obesity, diabetes and other chronic diseases. The cost of disease prevention will be dramatically lower than the cost of treatment," said Ullrich.Zhang Xinwei, deputy director of the provincial science and technology bureau, said that if the clinic's practices are successful, the model may be adopted by other regions in China.

来源：资阳报