北京干细胞治强直性脊柱炎(北京类风湿因子300多) (今日更新中)

WASHINGTON, July 7 (Xinhua) -- Space shuttle Atlantis will soar into the sky Friday on NASA's 135th and final flight. Its scheduled return to Earth later this month will mark the end of NASA's 30-year space program.Since its onset with the launch of space shuttle Columbia, the program has been seen as a cheap, safe and reliable way for space exploration.Despite its great contributions to U.S. manned space flight, it has also left some grave and tragic lessons, making its termination inevitable.HIKING COSTSLaunched in 1972 by then President Richard Nixon, the shuttle program aimed to provide a new system of affordable space travel and proved to be NASA's most enduring project in its 50 years of existence.In 1981, shuttle Columbia made its first shuttle flight for two days. It was the ultimate hybrid and the first reusable spacecraft.Launched like a rocket and gliding back to Earth like an airplane, space shuttles not only can act as a space taxi to carry astronauts, but have the muscle of a long-distance trucker to haul heavy machinery.The spaceship boasts more than 3,500 subsystems and 2.5 million parts and is nine times faster than a speeding bullet as it climbs heavenward. That versatility, however, has translated into higher costs.NASA originally estimated the program would cost about 90 billion U.S. dollars. However, its actual cost stands at about 200 billion dollars, compared with the 151 billion dollars spent on Apollo which took Americans to the moon in 1969.In an article in Technology Review, John Logsdon, former head of the Space Policy Institute at George Washington University, drew a direct connection between the ravenous shuttle budget and the lack of other large advances in manned space flight."By operating the system for 30 years, with its high costs and high risk, rather than replacing it with a less expensive, less risky second-generation system, NASA compounded the original mistake of developing the most ambitious version of the vehicle," he wrote."The shuttle's cost has been an obstacle to NASA starting other major projects," he added.HIGH RISKIn terms of safety, the shuttles have never been as reliable as their designers had envisioned.On average, one out of every 67 flights ended up with fatal accidents. Based on the rate of deaths per million miles traveled, the space shuttle is 138 times riskier than a passenger jet.Seven astronauts onboard died when Challenger exploded about a minute after launch in 1986. Nearly two decades after the tragic blast, a new catastrophe descended when the shuttle Columbia disintegrated moments before landing in 2003, killing another seven spacemen.Again, the shuttle program was shelved for more than two years as NASA stepped up efforts to make it safer. But experts say the fundamental problem related to shuttles' safety cannot be solved due to their "birth defects.""It is in the nation's interest to replace the Shuttle as soon as possible," concluded the panel that investigated the 2003 Columbia accident.

HOHHOT, Aug. 27 (Xinhua) -- A 5,000-year old rock carving in north China's Inner Mongolia Autonomous Region depicts a falling meteor, said archaeologists on Saturday.A rock on the side of Dahei Mountain in the city of Chifeng has images of people, domed houses and a fire ball with a long tail falling from the sky engraved on it, said Wu Jiacai, head of the Inner Mongolia rock paintings protection association."I believe it shows prehistoric people returning at dusk from a hunting trip to their domed houses, as a meteor falls from the sky," Wu shared his findings at the 6th Hongshan Cultural Forum that runs from August 25 to 27.He added that in the same location several years ago, another set of carvings were found showing people fleeing, snakes slithering and birds flying away, which might be what happened after the meteor hit the earth.The area has about 1000 carvings all believed to be made by the Neolithic Hongshan people, Wu said."The pictures can shed some light on the disappearance of the Hongshan culture, which was quite developed," Wu said.

SINGAPORE, July 10 (Xinhua) -- The upcoming Natural History Museum in Singapore launched a drive on Sunday to raise 12 million Singapore dollars (9.8 million U.S. dollars) by the end of the month to buy three dinosaur fossils from a company in Wyoming, the United States.The three dinosaurs on offer from the company Dinosauria International, thought to be a family, were found between 2007 and last year in the United States, the Straits Times reported on Sunday.Appollo and Prince, the two adult diplodocid sauropods, is about 24 meters long, while the baby Twinky is about 12 meters.The natural history museum is expected to be completed by 2014. The three dinosaur fossils will cost 870 million Singapore dollars, and an additional 370 million Singapore dollars will be spent to set up the exhibition."They wanted the museum to tell the story of the history of life and evolution. Dinosaurs are the history of life," said Professor Peter Ng, director of the Raffles Museum of Biodiversity Research, referring to the approval from the scientific advisory committee for the acquisition.The Raffles Museum of Biodiversity Research of the National University of Singapore went on an intensive fund raising campaign last year to build the dedicated Natural History Museum.The museum said it has found the amount to be challenging. It is therefore appealing for help from the public through the media."The idea was always to have a central gallery and put something there that would make people go 'Whoa!,'" said Ng.

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.

WASHINGTON, Sept. 15 (Xinhua) -- A team of researchers has discovered a planet that orbits around a pair of stars, the U.S. space agency NASA announced Thursday.This is the first instance of astronomers finding direct evidence of a so-called circumbinary planet. A few other planets have been suspected of orbiting around both members of a dual-star system, but the transits of the circumbinary planet have never been detected previously.The team, led by Laurance Doyle of the SETI Institute in California, used photometric data from the NASA Kepler space telescope, which monitors the brightness of 155,000 stars.NASA's Kepler mission has discovered a world where two suns set over the horizon instead of just one. The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy. Tatooine is the name of Luke Skywalker's home world in the science fiction movie Star Wars. In this case, the planet it not thought to be habitable. It is a cold world, with a gaseous surface, but like Tatooine, it circles two stars.They found the binary star system by detecting a system where the stars eclipsed each other from the perspective of the Kepler spacecraft. These stars have two eclipses: A primary eclipse when the larger star is partially blocked by the smaller star and a secondary eclipse where the smaller star is fully blocked by the larger star.But the researchers also noticed other times when the brightness of the two stars dropped, even when they were not in an eclipse position. This pattern suggested that there was likely a third object involved. The fact that these so-called tertiary and quaternary eclipses recurred after varying intervals of time, and were of different depths, indicated that the stars were in different positions in their orbit at each instance. This result showed that the tertiary and quaternary eclipses were being caused by something circling both stars, and not an object circling one or the other star.Measurements of the variations in the timing of all four types of eclipses, resulting from the mutual gravitational interactions of the two stars and the third body, demonstrated that the third object was, indeed, a planet. Their work indicates that the planet is less massive than Jupiter, possibly comparable in mass to Saturn, and that the larger of the two binary stars is smaller than our Sun.Their findings will be published Friday in Science."This discovery confirms a new class of planetary systems that could harbor life," Kepler principal investigator William Borucki said in a statement. "Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now."

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