郑州300度近视建议手术吗(郑州9岁近视200度能矫正吗) (今日更新中)

WASHINGTON, Nov. 8 (Xinhua) -- Children with autism have more brain cells and heavier brains compared to typically developing children, according to a study to be published on Wednesday in the Journal of the American Medical Association.The small, preliminary study provides direct evidence for possible prenatal causes of autism.The prefrontal cortex is involved in various higher order functions such as language and communication, social behavior, mood, and attention. Children who have autism tend to show deficits in such functions.Eric Courchesne, of the University of San Diego School of Medicine Autism Center of Excellence, and colleagues conducted direct counts of brain cells in specific regions of the prefrontal cortex in postmortem brains of seven boys who had autism and six typically developing males, ranging in age from 2-16 years. Most participants had died in accidents, but the researchers did not base their selection on causes of death.The researchers found that children with autism had 67 percent more neurons in the prefrontal cortex and heavier brains for their age compared to typically developing children. Since these neurons are produced before birth, the study's findings suggest that faulty prenatal cell birth or maintenance may be involved in the development of autism. Another possible factor that may contribute to the neuronal excess is a reduction in apoptosis, or programmed cell death, which normally occurs during the third trimester and early postnatal life.Though small, this preliminary study examined all relevant postmortem tissue available at the time. The relative scarcity of tissue from very young children may limit future research as well, but efforts to include a larger number of samples are needed to confirm these findings and to identify patterns of age-related changes in autism, the researchers say."Earlier studies of head circumference and early brain overgrowth have pointed us in this direction, but there have been few quantitative neuroanatomical studies due to the lack of postmortem tissue from children with autism," said Thomas Insel, director of the National Institute of Mental Health, in a statement. "These new results, along with an earlier study reporting altered wiring of the prefrontal cortex, focus our attention on this critical area of the brain in autism."

JIUQUAN/BEIJING, Nov. 1 (Xinhua) -- Commander-in-chief of China's manned space program Chang Wanquan announced early Tuesday that the launch of Shenzhou-8 unmanned spacecraft was successful.The spacecraft was sent into the designated orbit after the blastoff at 5:58 a.m. from the Jiuquan Satellite Launch Center in northwest Gobi desert, carried by an upgraded Long March-2F rocket.It is heading for rendezvous with Tiangong-1, or "the Heavenly Palace" that was put into space on Sept. 29 for the country's first space docking.The move, if successful, will pave the way for China to operate a permanent space station around 2020 and make the nation the world's third to do so.The combined photo taken on Nov. 1, 2011 shows the blast-off of a modified model of the Long March CZ-2F rocket carrying the unmanned spacecraft Shenzhou-8 at the Jiuquan Satellite Launch Center in northwest China's Gansu Province. Commander-in-chief of China's manned space program Chang Wanquan announced that the launch of the spacecraft was successful.Chinese Vice Premier Zhang Dejiang viewed the launch at the Jiuquan center. The launch was also observed on site by senior officials from the European Space Agency and the German Aerospace Center.The docking is scheduled to occur within two days after the launch of Shenzhou-8 and at a height of 343 km above the Earth's surface. It will return to the Earth after two docking tryouts.Chinese and German scientists will conduct 17 life science space experiments on the Chinese spacecraft Shenzhou-8, Wu Ping, spokeswoman for China's manned space program, said Monday.To ensure the success of the mission, Chinese space engineers have made "considerable modifications" on Shenzhou-8 to previous versions of the spacecraft.Shenzhou-8, with a length of nine meters and a maximum diameter of 2.8 meters, has a liftoff weight of 8.082 tonnes."More than half of the 600 or so sets of equipment have been modified, while newly designed devices account for about 15 percent of the total," Wu said.The modifications were mainly aimed at arming the spacecraft with automatic and manual rendezvous and docking capacities, and enhancing the vehicle's performance, safety and reliability, Wu said."After the improvements, the spacecraft will be able to connect with the target spacecraft Tiangong-1 for 180 days," Wu said.The unmanned spacecraft is also equipped with devices for recording real images and mechanical parameters during its flight, to test the space docking before a manned attempt.Once China has mastered the technologies of rendezvous and docking, it will be equipped with the basic technologies and capacity required for building a space station, said Zhou Jianping, chief designer of China's manned space program.Tuesday's mission will be followed by launches of spaceships Shenzhou-9 and -10 in 2012, which are also expected to dock with Tiangong-1. "At least one mission of the two will be manned," Wu said.The crew members, including probably two female astronauts, have already been selected for the possible manual space docking mission in 2012 and are being trained for manual docking skills.The space docking tests and experiments will provide crucial experience of China's construction of a 60-tonne permanent manned space station around 2020 when Chinese astronauts are expected to operate more research projects in space."It will make it possible for China to carry out space exploration of a larger scale," Zhou said.

CANBERRA, Dec. 9 (Xinhua) -- Scientists from Australia's University of New England on Friday said they had discovered the remarkably fossil isa metre-long arthropod with excellent vision called anomalocaris from Emu Bay Shale of South Australia.The scientists reported their finding on the anomalocaris in thescience journal Nature this week.It is reported that anomalocaris is a fearsome ancient predator that swam in the Cambrian oceans 500 million years ago. The researchers said the presence of anomalocaris would have driven the development of protective adaptations in prey animals. Such an escalatory 'arms race' would have seen, for instance, the evolution of such adaptations in prey as shells, camouflage and burrowing into sediments. "It has been unbelievably frustrating being able to see eyes like these at fossil sites like the Burgess Shale (in the Canadian Rocky Mountains), but not have any details. It is really refreshing to have our ideas about these animals confirmed at last, " comments Simon Conway Morris, a palaeontologist at the University of Cambridge, the United Kingdom.The research team was led by paleontologist Dr John Paterson, of the University of New England. He said the most surprising discovery of anomalocaris is the huge number of tiny hardened lenses in each eyes."When you consider that a modern housefly, for example, has about 3000 lenses, it's pretty impressive that an animal half a billion years old already has remarkable vision like this," Paterson said in statement."The fact that each eye in anomalocaris would have had over 16, 000 lenses means it would have very, very good resolution."Paterson said the acute vision of Anomalocaris gave it a distinct advantage over competing predators and prey, as many Cambrian animals either had poor vision or were completely blind. Its acute vision rivals or exceeds that of most living insects and was probably comparable to predatory dragonflies today.He said their findings support the idea that compound eyes evolved very early on in arthropod evolution, before the evolution of jointed legs or hardened exoskeletons.The research team hopes they can find the more fossil remains of Cambrian creatures in the Emu Bay Shale.

HONOLULU, United States, Nov. 12 (Xinhua) -- Chinese President Hu Jintao met his U.S. counterpart Barack Obama in Honolulu, Hawaii, Saturday to discuss Sino-U.S. ties and major world and regional issues.Hu and Obama were meeting before the Economic Leaders Meeting of the Asia-Pacific Economic Cooperation (APEC) scheduled for Saturday and Sunday in Hawaii.In a meeting with U.S. Secretary of State Hillary Clinton on Thursday in Honolulu, Chinese Foreign Minister Yang Jiechi said the Hu-Obama meeting has great significance for the steady development of China-U.S. relations.He noted that under the current situation, China is ready to make concerted efforts with the United States to deepen understanding, enhance mutual trust and better carry out the consensus reached by the two countries' leaders, so as to build a cooperative partnership based on mutual respect and mutual benefit.Clinton said President Obama looked forward to his meeting with President Hu.The U.S. side values its cooperative partnership with China, which is not only in the interests of both sides, but also holds great importance to the world at large, she said.Earlier this month, Hu and Obama met in Cannes, France, on the sidelines of a summit of the Group of Twenty (G20) and exchanged views on bilateral ties and the G20 summit.

SEOUL, Nov. 8 (Xinhua) -- Samsung Electronics, the world's largest flat screen TV vendor, said Tuesday that it has suspended its plan to develop active shutter three-dimensional (3D) TVs with RealD, the U.S.-based 3D technology supplier."Samsung has decided to focus on our own initiatives of 3D technology, and continues to research and develop next-generation 3D display technologies, including a glasses-free 3D solution for the home," the tech firm said in an e-mailed statement.The active shutter 3D technology drew public attention after Samsung reached a deal with RealD earlier this year to jointly develop such technology, aiming to unveil 3D TVs based on the technology early next year.The active shutter is a next generation 3D technology that incorporates merits from both shutter-glass (SG) technology, which Samsung adopted, and film patterned retarder (FPR) technology, which LG introduced in December last year.The SG technology has been touted as better picture quality and deeper 3D images, but the eyewear is heavier because it requires batteries and chips to work. The active shutter 3D technology moved its function of 3D image creation from eyewear to flat panel, making the eyewear lighter.Despite the upgraded technology and its convenience, Samsung decided to focus on its existing SG technology as the global TV market is grappling with weak demand. The penetration rate, which gauges the ratio of 3D sets against the total flat screen TVs, was expected to rise to 9.9 percent by year-end from the 3 percent a year earlier, according to Woori Investment & Securities, a local securities firm.

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