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WASHINGTON, July 13 (Xinhua) -- Human neural stem cells are capable of helping people regain learning and memory abilities lost due to radiation treatment for brain tumors, a University of California, Irvine (UCI) study suggests.Research with rats found that stem cells transplanted two days after cranial irradiation restored cognitive function, as measured in one- and four-month assessments. In contrast, irradiated rats not treated with stem cells showed no cognitive improvement."Our findings provide solid evidence that such cells can be used to reverse radiation-induced damage of healthy tissue in the brain," said Charles Limoli, a UCI radiation oncology professor.Study results will appear Friday in Cancer Research, a journal of the American Association for Cancer Research.Radiotherapy for brain tumors is limited by how well the surrounding tissue tolerates it. Patients receiving radiation at effective levels suffer varying degrees of learning and memory loss that can adversely affect their quality of life."In almost every instance, people experience severe cognitive impairment that's progressive and debilitating," Limoli said. " Pediatric cancer patients can experience a drop of up to three IQ points per year."For the UCI study, multipotent human neural stem cells were transplanted into the brains of rats that had undergone radiation treatment. They migrated throughout the hippocampus -- a region known for the growth of new neurons -- and developed into brain cells.Researchers assessed the rats one month and four months after transplantation, noting enhanced learning and memory abilities at both intervals.Additionally, they found that transplanting as few as 100,000 human neural stem cells was sufficient to improve cognition after cranial irradiation. Of cells surviving the process, about 15 percent turned into new neurons, while another 45 percent became astrocytes and oligodendrocytes -- cells that support cerebral neurons.Most notably, Limoli said, he and his colleagues discovered that about 11 percent of the engrafted cells expressed a behaviorally induced marker of learning, indicating the functional integration of those cells into memory circuits in the hippocampus."This research suggests that stem cell therapies may one day be implemented in the clinic to provide relief to patients suffering from cognitive impairments incurred as a result of their cancer treatments," Limoli said.

BEIJING, July 19 (Xinhuanet) -- Amazon on Monday launched its Kindle textbook rental service, which allows students to rent "tens of thousands of textbooks", according to Los Angeles Times.The e-book textbook rental service will help students save as much as 80 percent on some titles.Amazon said that students can now rent textbooks from 30 to 360 days and can either rent them again or purchase them once the rental period is up."Students tell us that they enjoy the low prices we offer on new and used print textbooks. Now we're excited to offer students an option to rent Kindle textbooks and only pay for the time they need—with savings up to 80 percent off the print list price on a 30-day rental," Dave Limp, vice president of Amazon Kindle said, according to PC Magazine.Rentals can be read on Amazon's Kindle eReaders, and Kindle apps for PCs, as well as smartphones and tablet computers running Apple's iOS, Microsoft Windows Phone 7 and Google's Android operating system.Rentals also have a clear advantage over physical copies that students' notes and highlighted content will be stored in the Amazon Cloud, and can be accessed if students rent the books again or buy at a later time.

MOSCOW, Aug. 6 (Xinhua) -- The Arctic is getting warmer at a fast pace with the Russian Arctic sector's ice areas contracting to historically low levels, according to Russian meteorological bureau Rosgidromet.According to a Rosgidromet report cited by Itar-Tass news agency Saturday, the polar cap in the Russian sector has shrunk to the historical low registered in 2007, with no ice expected to block the Northern Seaway at least until September."Currently, Arctic navigation conditions are very favorable. By early August, navigation can be done without icebreakers almost along the entire route," said Valery Martyshchenko, head of Rosgidromet's environment pollution monitoring department.According to the Arctic and Antarctic Research Institute, the current ice cover in the Arctic Ocean is 6,860 million square kilometers, way below average.Martyshchenko said the longer period of icebreaker-free navigation would benefit the regions located in the Arctic area, allowing longer access to food and energy supplies, but the warming of the climate also posed new threats, such as melting of ice and forming of icebergs.

SAN FRANCISCO, July 6 (Xinhua) -- Facebook on Wednesday introduced a new video calling feature powered by Skype and some improvements to the chat designs on the social networking site.According to Facebook, users can reach video calling from a new "Call" button on a friend's profile or from the chat panel after downloading a Skype application. A recipient will receive an alert that they are being called and can then accept or decline.At the press event held at Facebook headquarters in Palo Alto, California, CEO Mark Zuckerberg said the feature will begin with one-on-one video chat. Skype CEO Tony Bates, whose company has been acquired by Microsoft, said Skype is considering having its paid product within the Facebook product.The social networking company also introduced "Ad Hoc Group Chat", which enables users to start a group chat instantly without creating a group with those multiple friends at first. The new group chat feature is also available for Facebook's mobile interfaces.Facebook also introduces a sidebar that lists the people a user messages most, enabling users to chat with close friends, professional contacts or co-workers without being interrupted. The sidebar can adjust with the size of users' browser window and automatically appears when the window is wide enough.In the opening remarks at the press event, Zuckerberg confirmed that Facebook had surpassed 750 million monthly active users. He said the company had declined to announce the number earlier because it has become focused on other metrics, like how actively users are sharing information.The CEO said users are now sharing 4 billion "things" on Facebook every day, which grew at an exponential rate compared to the amount users share a year ago."Social networking is at an inflection point," said Zuckerberg, adding that he believes social networking now is more about the strength of connecting people rather than the quantity of users or ubiquity of the technology.Zuckerberg presented a graph to show how Facebook product launches have helped drive the growth of sharing. He said the social network expects more innovations from other companies involved in everything from music to communication to help drive the growth.