郑州近视中子镜价格郑州做近视眼手术医院,郑州近视眼手术费,郑州近视做激光多少钱,郑州近视眼做手术多少钱,郑州近视眼一大一小,郑州眼睛近视200度能当兵吗,郑州眼睛做激光手术好不好

You can think of NASA's Discovery program as a sort of outer-space American Idol: every few years the agency invites scientists to propose unmanned planetary missions. The projects have to address some sort of fundamental science question, and (this is the tough part) they have to be relatively cheap to pull off — say, half a billion dollars or so. Then the proposals go through a grueling competition before judges who aren't as nasty as Simon Cowell but who are every bit as tough. The one left standing at the end gets the equivalent of a recording contract: NASA supplies the funding and the launch vehicle, and away the winner goes — to orbit Mercury, as the Messenger spacecraft is doing right now; or to rendezvous with a couple of asteroids, as the Dawn mission will start doing this July; or to smash into a comet on purpose, a feat achieved by Deep Impact in 2005, a mission not to be confused with the movie of the same name. Now it's time for the next contenders. NASA has just announced that the first round of the latest Discovery competition is over, with three entries out of 28 moving on to the finals. They are, in increasing distance from Earth: the Geophysical Monitoring Station (GEMS) lander, which would use seismometers to study the interior of Mars; the Comet Hopper, which would do just that, leaping from place to place across the surface of Comet 46P/Wirtanen to see how different parts of the tumbling body react to heating by the sun; and the Titan Mare Explorer (TiME), which would plop into a sea of liquid hydrocarbons on Saturn's moon Titan — the first oceangoing vessel ever to set sail on another world. If you had to come up with a theme that ties all three missions together, it would be "origins." The Titan explorer, for example, will be studying a place that — in a crude way, at least — resembles the early planet Earth at a time when life arose here. Titan, with a thick atmosphere and a bizarro-world form of weather featuring toxic winds and hydrocarbon rain, is home to a mix of complex chemistry, complete with organic molecules. The oceans provide a medium in which the molecules can move around and interact with each other. It's even conceivable, though clearly a long shot, that some form of microscopic life already exists on this frigid moon. The Mars lander, by contrast, would visit a place where the seas — plain water in this case — vanished long ago. But the mission of GEMS goes far deeper than that. By analyzing Marsquakes on the Red Planet, GEMS will try to get a handle on what the interior of Mars is like. Scientists don't currently know whether the planet's core is liquid, like Earth's, or solid, or some mushy consistency in between. It all depends on how efficiently Mars has cooled since it formed 4.5 billion years ago, and that depends in turn on the planet's internal structure. "That's the mission," says Bruce Banerdt, of NASA's Jet Propulsion Laboratory, the lead scientist for GEMS. "We want to understand how Mars was built." Along with sensitive seismographic equipment, GEMS will drill down about 20 ft. (6 m) with a thermometer-equipped probe, trying to figure out how quickly the temperature rises with depth. "That will let us extrapolate all the way down to the center," Banerdt says, "which will tell us how fast Mars is cooling."

LOS ANGELES, March 5 (Xinhua) -- Law enforcement agencies are now using smart phones to track and arrest graffiti vandals in Los Angeles, a newspaper report said on Saturday.The graffiti-tracking program, spearheaded by the Tracking and Automated Graffiti Removal System, or TAGRS, allows graffiti- cleaning crews equipped with smart phones to photograph the markings and upload them to a Los Angeles Police Department (LAPD) database, the Los Angeles Times said.The photos are used to gather evidence for prosecution and restitution, the paper quoted city officials as saying.Once the graffiti suspects' identities are discovered, the information is added to the TAGRS database and may eventually uncover incidents involving the same suspects, the paper said.The LAPD launched a pilot project in 2009 in Van Nuys near Los Angeles, modeling its version on one run by the Orange County Sheriff's Department, according to the report.The program is now anchored at four LAPD stations, Van Nuys, Hollenbeck, Central and Harbor, said Mayor Antonio Villaraigosa's spokeswoman Casey Hernandez.Los Angeles spends about 10 million dollars a year cleaning up graffiti, Hernandez said.

MOSCOW, Jan. 24 (Xinhua) -- China and Russia held the fifth round of strategic security talks here Monday, pledging more joint efforts to strengthen national, regional and international security.The Chinese delegation, led by Chinese State Councilor Dai Bingguo, was visiting Russia at the invitation of Russian Security Council Secretary Nikolai Patrushev.During the talks, the two parties exchanged views on major international issues and the further development of strategic partnership and interaction between Russia and China.Both sides agreed that their close bilateral cooperation on global issues has helped maintain regional and world peace, safety and stability.The two countries acknowledged that in order to further enhance strategic mutual trust and improve the security situation around the global, the two sides should chart the development of Sino- Russian relations for the next 10 years from a strategic and comprehensive perspective.As long-time strategic partners, Russia and China will adhere to the principles of mutual trust, win-win cooperation and good neighborliness while conducting strategic coordination, the two sides pledged.The fourth round of Sino-Russian security consultations took place in Beijing in December 2009, when Russia and China signed a protocol on cooperation in the strategic security sphere. The next round of talks is scheduled to be held later this year in China.

BEIJING, Feb. 27 (Xinhua) -- A total of 2.64 billion trips in China were recorded by road or ships during the 40-day Spring Festival transportation season which ended Sunday, the Ministry of Transport said.The figure was 13.6 percent higher than the same period last year, noted ministry spokesman He Jianzhong.To ensure smooth transportation, 840,000 buses were put into use each day during the busy season, as well as 13,089 ships, He said.Statistics on railway transportation are not yet available.However, statistics from the Beijing railway administration showed 20.63 million tourists had left Beijing during the transportation season from Jan. 19 to Feb. 27, up 3.9 percent year on year.The busy Spring Festival transportation season runs for 40 days and is calculated in two phases: 15 days before and 25 days after the Spring Festival.

LOS ANGELES, April 1 (Xinhua) -- A NASA Gulfstream-III aircraft equipped with a synthetic aperture radar is scheduled to depart Sunday, April 3 on a nine-day mission to image Hawaii volcanoes, the Jet Propulsion Laboratory (JPL) announced on Friday.The aircraft will fly from the Dryden Aircraft Operations Facility in Palmdale, California to the Big Island of Hawaii to study the Kilauea volcano that recently erupted, said JPL in Pasadena, Los Angeles.The mission will help scientists better understand processes occurring under Earth's surface, JPL said.Developed by JPL, the Uninhabited Aerial Vehicle Synthetic Aperture Radar, or UAVSAR, uses a technique called interferometric synthetic aperture radar that sends pulses of microwave energy from the aircraft to the ground to detect and measure very subtle deformations in Earth's surface, such as those caused by earthquakes, volcanoes, landslides and glacier movements.As the Gulfstream-III flies at an altitude of about 12,500 meters, the radar, located in a pod under the aircraft's belly, will collect data over Kilauea, according to JPL.The UAVSAR's first data acquisitions over this volcanic region took place in January 2010, when the radar flew over the volcano daily for a week. The UAVSAR detected deflation of Kilauea's caldera over one day, part of a series of deflation-inflation events observed at Kilauea as magma is pumped into the volcano's east rift zone.This month's flights will repeat the 2010 flight paths to an accuracy of within 5 meters, or about 16.5 feet, assisted by a Platform Precision Autopilot designed by engineers at NASA's Dryden Flight Research Center on Edwards Air Force Base, California, JPL said.By comparing these camera-like images, interferograms are formed that reveal changes in Earth's surface, said JPL.Between March 5 and 11, 2011, a spectacular fissure eruption occurred along the east rift zone. Satellite radar imagery captured the progression of this volcanic event."The April 2011 UAVSAR flights will capture the March 2011 fissure eruption surface displacements at high resolution and from multiple viewing directions, giving us an improved resolution of the magma injected into the east rift zone that caused the eruption," said JPL research scientist Paul Lundgren."Our goal is to be able to deploy the UAVSAR on short notice to better understand and aid in responding to hazards from Kilauea and other volcanoes in the Pacific region covered by this study," Lundgren added.