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BEIJING, July 26 (Xinhuanet) -- Hong Kong scientists announced that they had determined the idea of time travel is impossible by proving nothing can travel faster than the speed of light.The finding is contained in a study done by a research team from Hong Kong University of Science and Technology. The study was published Monday in a scientific journal "Physical Review Letters" in the United States."The study, which showed that single photons also obey the speed limit c, confirms Einstein's causality, that is, an effect cannot occur before its cause," the university said on its website."By showing that single photons cannot travel faster than the speed of light, our results bring a closure to the debate on the true speed of information carried by a single photon." said Professor Du Shengwang, who led the study.The possibility of time travel was raised 10 years ago when scientists discovered the optical pulses in some specific medium might propagate information in a faster-than-light speed."Our findings will also likely have potential applications by giving scientists a better picture on the transmission of quantum information." Du said.

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."

LOS ANGELES, June 5 (Xinhua) -- U.S. researchers have developed two new drugs that can prolong the lives of patients with advanced melanoma, it was announced on Sunday.Research on both drugs was presented at the on-going annual meeting of the American Society of Clinical Oncology in Chicago, according to HealthDay News.This is the first big news in years for treatment of melanoma, one of the deadliest forms of skin cancer and one that is notoriously difficult to treat, let alone cure, the report said.The first treatment, vemurafenib, inhibits a gene mutation harbored in half of all melanoma patients, but is not yet approved by the U.S. Food and Drug Administration.The other drug, Yervoy (ipilumumab), is an immune system therapy that won approval in March."The March FDA approval of ipilumumab (Yervoy) was the first new drug approval for melanoma in 13 years," said Tim Turnham, executive director of the Melanoma Research Foundation.The two drugs were developed by researchers at Memorial Sloan- Kettering Cancer Center in New York City, the report said."This is really a huge step toward personalized care in melanoma," Dr. Paul Chapman, lead author of the first study and the attending physician in the melanoma/sarcoma service at Memorial Sloan-Kettering, said in a statement. "This (vemurafenib) is the first successful melanoma treatment tailored to patients who carry a specific gene mutation in their tumor, and could eventually become one of only two drugs available that improves overall survival in advanced cancers.""Having two trials that show a benefit in survival in patients with melanoma, both of these in first-line settings -- we weren't here just a few years ago," said Dr. Stephen Hodi, director of the Melanoma Center at Dana Farber Cancer Institute in Boston. "These are huge, paradigm-shifting results for the field."In the vemurafenib trial, sponsored by the drug's makers, researchers randomly assigned 675 patients with advanced, inoperable melanoma to receive either the chemotherapy drug dacarbazine or vemurafenib. Vemurafenib targets the V600E mutation in the BRAF gene.At the three-month mark, patients taking vemurafenib were 63 percent less likely to die and 74 percent less likely to die or see their cancer return, compared to patients taking dacarbazine alone.Few patients had side effects in the vemurafenib group, although some did develop squamous cell carcinoma, a less dangerous form of skin cancer.This is the first drug that has been proven superior to chemotherapy in this group of hard-to-treat patients, the researchers said."There was such a substantial benefit that we recommended that patients cross over," Chapman said at a Sunday news briefing. "It' s unprecedented to report a trial this early. The median follow-up time was three months." Yet the differences between the two groups became evident almost immediately.Dr. Lynn Schuchter, co-moderator of the briefing and division chief of hematology-oncology at Abramson Cancer Center of the University of Pennsylvania in Philadelphia, said symptoms subsided in some patients almost immediately, enabling them to cut back on pain medication in just 72 hours."The median time to progression with dacarbazine was 1.6 months versus three months with vemurafenib, which is a huge difference," said Chapman.In the second study, about 500 patients were randomly picked to receive Yervoy plus dacarbazine or dacarbazine alone.Those taking both drugs lived a median of 11.2 months compared to 9.1 months for those taking dacarbazine alone. Time to recurrence of disease was about the same for both groups: 2.8 months and 2.6 months, respectively.Almost half of those taking the combination therapy were alive after one year, compared to 36.3 percent in the other group. After two years, the rates were 28.5 percent and 17.9 percent, respectively.By three years out, 20.8 percent of those in the combination group were alive compared with 12.2 percent of those taking chemotherapy alone.This is the first study to combine chemotherapy and immunotherapy both safely and effectively.A study to test vemurafenib in combination with Yervoy has already begun, according to HealthDay News.

SAN FRANCISCO, Sept. 2 (Xinhua) -- A late-season potato blight has been detected on farms in Alaska, only the fourth time the disease appear in the U.S. state since 1995, local media reported on Friday.The disease was found this week in the fields of potato producers in cities of Delta Junction and Palmer, according to the Fairbanks Daily News-Miner, Alaska's second largest daily newspaper.Farmers in both fields are working to prevent the spread of the blight, a fungus-like disease that can kill plants in the field or cause potatoes to rot in storage, the newspaper reported.Growers have been asked to kill all affected plants within 100 feet, and plant samples from both sites will be examined to identify what type of late blight is involved.Experts said that blight can be controlled through the use of fungicides, but the cool, damp weather this summer in the areas has created an ideal environment for the disease to spread.Although Alaska's potato crop is tiny compared to other U.S. states, it has been viewed as a possible global source of seed potatoes in recent years because it is largely free of disease.A local university has explored partnerships with Chinese growers to export certified seed potatoes, noted the Fairbanks Daily News-Miner report.

SHENZHEN, June 18 (Xinhua) -- China established its first national gene bank on Friday in south China's city of Shenzhen with the support of the Beijing Genomics Institute (BGI), officials said.With the establishment of the National Gene Bank in Shenzhen, China will be able to better protect, research and utilize its precious genetic resources, boosting the genetics industry and safeguarding the country's genetic information, said Qi Chengyuan, head of the high-tech industry department of the National Development and Reform Committee (NDRC).The gene bank, which was approved by the NDRC in January, is based on data and facilities belonging to the BGI, but will grow with the help of extensive cooperation with other biological organizations both home and abroad, Qi said.The national gene bank "aims to lead the development of international bioindustry as one of the world's largest gene banks," said Yang Huanming, the BGI's president.The BGI, the world's largest genome-mapping institute, has more than 1,000 biological analysis devices working with top-of-the-line genome-sequencing machines.Analysts say the BGI differs from conventional labs, as it can handle data in vast quantities and industrialize its research. Some believe lower wages in China have also contributed to the BGI's competitiveness.Yang Bicheng, the BGI's spokesman, said the payment and welfare packages BGI offers are competitive in China's bioindustry."A researcher with about two years of experience earns around 100,000 yuan (15,440 U.S. dollars) a year. More outstanding researchers can get more, but the gap is not too great," Yang said.Yang said greater motivation comes from better prospects for academic achievements."Our young researchers can work with the world's leading scientists, participate in global science projects and be pioneers in new fields of research. Only BGI offers these kinds of opportunities in China," Yang said.The BGI has published 18 research papers in Science Magazine and the Nature Journal since 2007. The facility has become an international center for genome research and industrialization, with advanced technology and top talent, said Ji Xiaoming, head of the international cooperation department of the Ministry of Science and Technology.China is working to make its genetic research industry into one of the country's pillar industries.A plan approved by the State Council, or China's cabinet, in October 2010 said China will boost the industry by encouraging innovation, promoting industrial application of biological research, fostering market demand and deepening international cooperation.

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