武清泌尿外科医院龙济(天津市龙济必尿外科医院怎么样) (今日更新中)

BEIJING, Sept. 2 (Xinhuanet) -- The amount of space junk orbiting the Earth could cause fatal leaks in spaceships or destroy valuable satellites, according to a report released by the U.S. National Research Council.Computer models have shown that the number of orbital debris "has reached a tipping point, with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures," the Research Council said Thursday.So far, there are 22,000 pieces of debris large enough to track from the ground, but smaller objects could still cause serious damage.New international regulations are needed to limit space junk.And more researches should be done to test the possible use of launching magnetic nets or giant umbrellas to push the debris further towards the Earth where it would burn up, or into a higher but safer orbit.

XICHANG, Sichuan, Aug. 12 (Xinhua) -- China launched a communications satellite PAKSAT-1R for Pakistan at 0:15 a.m. Friday from the Xichang Satellite Launch Center in southwest China's Sichuan Province.The satellite was carried by a Long March-3B carrier rocket, according to the launch center. It is China's first in-orbit delivery to Asian customers and also the first commercial satellite export to international users this year.According to statistics from the control center, the satellite successfully separated from its carrier rocket and entered geostationary transfer orbit as scheduled, 26 minutes after being launched.PAKSAT-1R will provide a range of services, including broadband Internet, telecom and broadcasting, covering some regions of Europe, South Asia, the Middle East, and the eastern Africa.The contract for the PAKSAT-1R was signed in 2008 between China Great Wall Industry Corporation and the Space and Upper Atmosphere Research Commission of Pakistan.China and Pakistan share a long history of space technology cooperation. Pakistan's first low-orbit satellite, BADR-A, was launched by China in 1990 with Long March 2E rocket.

RIO DE JANEIRO, Sept. 26 (Xinhua) -- Rio de Janeiro has the highest level of air pollution in Brazil, and is more polluted than many other world metropolis like New York, London and Paris, a World Health Organization (WHO) study said Monday.According to the study, which was carried out in 91 countries and regions, the air in Rio's metropolitan area contains 64 micrograms of fine particulate matter per cubic meter, over three times the upper limit set by the WHO, which is 20 micrograms per cubic meter.Despite being larger, having a bigger population and more vehicles, Sao Paulo's metropolitan area has less air pollution, with 38 micrograms of fine particulate matter per cubic meter.According to the WHO, "the largest contributors to urban outdoor air pollution include motor transport, small-scale manufacturers and other industries, burning of biomass and coal for cooking and heating, as well as coal-fired power plants." The organization said that residential wood and coal burning for heating also help increase air pollution, especially in rural areas in the cold months.The WHO expressed concern over air pollution levels in several cities, as some two million people worldwide die annually from conditions resulting from air pollution."Air pollution is a major environmental health issue, and it is vital that we increase efforts to reduce the health burden it creates," said Dr. Maria Neira, WHO's director for Public Health and Environment.According to the study, Ahwaz, Iran, has the most polluted air in the world, with 372 micrograms of fine particulate matter per cubic meter.

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."

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.

来源：资阳报