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WASHINGTON, May 4 (Xinhua) -- The U.S. National Aeronautics and Space Administration (NASA) announced Wednesday that its Gravity Probe B (GP-B) mission has confirmed two key predictions derived from Albert Einstein's general theory of relativity, which the spacecraft was designed to test.The experiment, launched in 2004, used four ultra-precise gyroscopes to measure the hypothesized geodetic effect, the warping of space and time around a gravitational body, and frame- dragging, the amount a spinning object pulls space and time with it as it rotates.GP-B determined both effects with unprecedented precision by pointing at a single star, IM Pegasi, while in a polar orbit around Earth. If gravity did not affect space and time, GP-B's gyroscopes would point in the same direction forever while in orbit. But in confirmation of Einstein's theories, the gyroscopes experienced measurable, minute changes in the direction of their spin, while Earth's gravity pulled at them.The findings are available online in the journal Physical Review Letters."Imagine the Earth as if it were immersed in honey. As the planet rotates, the honey around it would swirl, and it's the same with space and time," said Francis Everitt, GP-B principal investigator at Stanford University. "GP-B confirmed two of the most profound predictions of Einstein's universe, having far- reaching implications across astrophysics research."GP-B is one of the longest running projects in NASA history, with agency involvement starting in the fall of 1963 with initial funding to develop a relativity gyroscope experiment. Subsequent decades of development led to groundbreaking technologies to control environmental disturbances on spacecraft, such as aerodynamic drag, magnetic fields and thermal variations. The mission's star tracker and gyroscopes were the most precise ever designed and produced.GP-B completed its data collection operations and was decommissioned in December 2010."The mission results will have a long-term impact on the work of theoretical physicists," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington. "Every future challenge to Einstein's theories of general relativity will have to seek more precise measurements than the remarkable work GP-B accomplished."

JINAN, May 14 (Xinhua) -- Chinese scientists said Saturday that they have found a new species of giant theropod dinosaur in the eastern province of Shandong.The new species, described as a close relative of Tyrannosaurus rex (T. rex), has been named "Zhuchengtyrannus magnus". Paleontological experts found it has unique upper jawbones after examining the skull and jawbones discovered in the city of Zhucheng.It was estimated to be about 11 meters long and 4 meters tall, weighing close to 7 tonnes."We discovered two kinds of tyrannosaurus fossils here and the identity of the other one still remains unclear," said Xu Xing, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology under the Chinese Academy of Sciences."We've named the new genus Zhuchengtyrannus magnus, which means the 'Tyrant from Zhucheng' because the bones were found in Zhucheng," Xu said.The bones were a few centimeters smaller than the similar bones in the largest T. Rex specimen, so there was no doubt that Zhuchengtyrannus was a huge tyrannosaur, Xu said.According to Xu, Zhuchengtyrannus magnus belonged to a specialized group of gigantic theropods called tyrannosaurines which existed in North America and eastern Asia during the Late Cretaceous Period that dated back about 65 to 99 million years.All tyrannosaurs were carnivorous, bipedal animals that generally had small arms and large skulls. Among the tyrannosaurs, the tyrannosaurines were the largest and characterized by having just two fingers on each hand and large powerful jaws to deliver a bone crushing bite. They were likely both predators and scavengers.The fossil quarry in Zhucheng contains one of the largest concentrations of dinosaur bones in the world. At least 10 dinosaur species have been found in three rounds of excavations since the 1960s, including Tyrannosaurus and Hadrosaurs.

HONG KONG, March 18 (Xinhua) -- After over a year's efforts, scientists from Shanghai and Hong Kong announced on Friday that they have completed the whole genomic sequencing work of Isaria cicada, a rare herb highly valued in traditional Chinese medicine, which will help facilitate its further development in medical and nutrition fields.It is the first time that the whole genomic sequence of Isaria cicada has been released, said the scientists from Shanghai Institute of Bio-Asia Life Science and the Hong Kong University of Science and Technology (HKUST), who participated in the research.The result was announced at the International Biomedical Scientists and Biotechnology Forum 2011 held in the day at the Hong Kong Science Park.According to the result, the genomic size of Isaria cicada, a medicine traditionally used to treat children's diseases, is about one eightieth of human genome, containing about 16,000 genes.The tests that had been done proved that Isaria cicada, with many high-quality genes not recognized or used by human beings yet, has been deeply involved in important life processes like metabolism, providing new ways for further development of Isaria cicad in bio-medical area, said a scientist from HKUST.The genome map will also help accelerate the artificial cultivation of Isaria cicada, enhancing its medicine and nutrition value and making it available in a larger market, according to the scientist.

LOS ANGELES, April 6 (Xinhua) -- Freeze-dried strawberries may play a role in the prevention of esophageal cancer, a new study suggests."Strawberries may be an alternative or work together with other chemopreventive drugs for the prevention of esophageal cancer," said lead researcher Tong Chen, M.D., Ph.D., assistant professor, division of medical oncology, department of internal medicine at the Ohio State University.Study findings were presented at the ongoing 102nd annual meeting of the American Association for Cancer Research (AACR) in Orlando, Florida, according to the American Association for the Advancement of Science (AAAS) on Wednesday."We concluded from this study that six months of eating strawberries is safe and easy to consume. In addition, our preliminary data suggests that strawberries can decrease histological grade of precancerous lesions and reduce cancer- related molecular events," said Chen, who is also a member of the Molecular Carcinogenesis and Chemoprevention Program in the Ohio State University Comprehensive Cancer Center.The study involved a group of participants who consumed 60 grams of freeze-dried strawberries daily for six months and completed a dietary diary chronicling their strawberry consumption.The researchers obtained biopsy specimens before and after strawberry consumption. The results showed that 29 out of 36 participants experienced a decrease in histological grade of the precancerous lesions during the study.Using freeze-dried strawberries was important because by removing the water from the berries, they concentrated the preventive substances by nearly 10-fold, Chen said.Esophageal cancer is the third most common gastrointestinal cancer and the sixth most frequent cause of cancer death in the world, she noted.Chen and her team are studying esophageal squamous cell carcinoma (SCC) which makes up 95 percent of cases of esophageal cancer worldwide. China, where this study took place, has the highest incidence of esophageal SCC, according to the AAAS.In a previous study, Chen and colleagues found that freeze- dried strawberries significantly inhibited tumor development in the esophagus of rats. Based on these results, they embarked on a Phase Ib trial that included participants with esophageal precancerous lesions who were at high risk for esophageal cancer."Our study is important because it shows that strawberries may slow the progression of precancerous lesion in the esophagus," Chen said.But she said they need to test this in randomized placebo- controlled trials in the future.

来源：资阳报