吉林一般割包皮大概花多少钱(吉林导致慢性前列腺炎的原因) (今日更新中)

WASHINGTON, July 20 (Xinhua) -- Using the Hubble Space Telescope, astronomers have discovered a fourth moon orbiting the icy dwarf planet Pluto, the U.S. National Aeronautics and Space Administration (NASA) announced Wednesday in a statement. The tiny, new satellite, temporarily designated P4, was uncovered in a Hubble survey searching for rings around the dwarf planet.P4 was first seen in a photo taken with Hubble's Wide Field Camera 3 on June 28. It was confirmed in subsequent Hubble pictures taken on July 3 and July 18. It is the smallest moon discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Charon, Pluto's largest moon, is 648 miles (1,043 km) across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter (32 to 113 km).Two labeled images of the Pluto system taken by the Hubble Space Telescope's Wide Field Camera 3 ultraviolet visible instrument with newly discovered fourth moon P4 circled. The image on the left was taken on June 28, 2011. The image of the right was taken on July 3, 2011."I find it remarkable that Hubble's cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km)," said Mark Showalter of the SETI Institute in California, who led this observing program with Hubble.P4 is located between the orbits of Nix and Hydra, which Hubble discovered in 2005. Charon was discovered in 1978 at the U.S. Naval Observatory and first resolved using Hubble in 1990 as a separate body from Pluto.The dwarf planet's entire moon system is believed to have formed by a collision between Pluto and another planet-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto.The finding is a result of ongoing work to support NASA's New Horizons mission, scheduled to fly through the Pluto system in 2015. The mission is designed to provide new insights about worlds at the edge of our solar system. Hubble's mapping of Pluto's surface and discovery of its satellites have been invaluable to planning for New Horizons' close encounter."This is a fantastic discovery," said New Horizons' principal investigator Alan Stern of the Southwest Research Institute in Colorado. "Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby."

WASHINGTON, June 23 (Xinhua) -- NASA's next Mars rover has completed the journey from its California birthplace to Florida in preparation for launch this fall, the U.S. space agency said Thursday in a statement.The Mars Science Laboratory (MSL) rover, also known as Curiosity, arrived Wednesday at NASA's Kennedy Space Center aboard an Air Force C-17 transport plane. It was accompanied by the rocket-powered descent stage that will fly the rover during the final moments before landing on Mars.The rover's aeroshell -- the protective covering for the trip to the Red Planet -- and the cruise stage, which will guide it to Mars, arrived at Kennedy last month. The mission is targeted to launch from Cape Canaveral Air Force Station between Nov. 25 and Dec. 18. The car-size rover will land on Mars in August 2012.The rover and other spacecraft components will undergo more testing before mission staff stack them and fuel the onboard propulsion systems. Curiosity should be enclosed in its aeroshell for the final time in September and delivered to Kennedy's Launch Complex 41 in early November for integration with a United Launch Alliance Atlas V rocket.Curiosity is about twice as long and more than five times as heavy as any previous Mars rover. Its 10 science instruments include two for ingesting and analyzing samples of powdered rock delivered by the rover's robotic arm. During a prime mission lasting one Martian year -- nearly two Earth years -- researchers will use the rover's tools to study whether the landing region has had environmental conditions favorable for supporting microbial life and favorable for preserving clues about whether life existed.

SAN FRANCISCO, Sept. 13 (Xinhua) -- Researchers in San Francisco, U.S. have found in a latest study that bisphenol A (BPA) and methylparaben, two chemicals commonly used in consumer products, can interfere with the breast cancer drugs, local media reported on Tuesday.In the study, doctors from California Pacific Medical Center in San Francisco found that healthy breast cells from high-risk patients started to find ways to bypass breast cancer drugs after they were exposed to BPA and methylparaben in the lab.The cells exposed to the two chemicals kept growing and didn't die after they were introduced with Tamoxifen, a current standard drug therapy for female breast cancer and most common used treatment for male breast cancer, Dr. William Goodson, lead author of the study, told San Francisco Chronicle.Goodson said that BPA and methylparaben not only mimic estrogen 's ability to drive cancer, but appear to be even better than the natural hormone in bypassing the ability of drugs to treat it. The finds have been published online in the British medical journal Carcinogenesis.The research shows more evidence of safety issues of BPA, a chemical primarily used to make plastic baby bottles, food containers, household electronics and etc, as well as the less known methylparaben, a chemical preservative used in cosmetics and other personal care products.The researchers noted that the breast cancer rates have been growing by about the same amount in men as in women over the past three decades. Scientists have been looking at environmental causes for the disease and wondering where the hormones are coming from.Goodson said BPA and methylparaben are used so widely and even found in household dust, noting that it is still unknown whether the effects of exposure to the chemicals are reversible.Since 2008, several governments issued reports questioning the negative health effects of BPA, especially raising concerns regarding exposure of fetuses, infants and children. BPA use has been banned in baby bottles in a lot of countries and regions.As for methylparaben, the U.S. Food and Drug Administration said on its website that "at the present time there is no reason for consumers to be concerned about the uses of cosmetics containing parabens (including methylparaben)."

BEIJING, Aug. 5 (Xinhuanet) -- A study conducted by Israeli researchers at the Albert Einstein College of Medicine in New York shows that genes, rather than good eating and lifestyle habits, determine longevity, according to media reports Friday. "This study suggests that centenarians may possess additional longevity genes that help to buffer them against the harmful effects of an unhealthy lifestyle," said senior author Nir Barzilai, director of the Institute for Aging Research at Yeshiva University's Albert Einstein College of Medicine.The study involves 477 Ashkenazi Jews between the ages of 95 and 122, of whom 75 percent are women. According to the study, Ashkenazi Jews are chosen as subjects because they are more "genetically uniform than other populations, making it easier to spot gene differences that are present."The study also found that the long-lived Ashkenazi Jews drank slightly more and exercised less than their average counterparts. But Barzilai also warned: “Although this study demonstrates that centenarians can be obese, smoke and avoid exercise, those lifestyle habits are not good choices for most of us who do not have a family history of longevity.""We should watch our weight, avoid smoking and be sure to exercise, since these activities have been shown to have great health benefits for the general population, including a longer lifespan," He added.

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