昌吉27岁割包茎(昌吉那家医院带环) (今日更新中)

WASHINGTON, June 9 (Xinhua) -- Observations from NASA's Voyager spacecraft suggest the edge of our solar system may not be smooth, but filled with a turbulent sea of magnetic bubbles, the U.S. space agency said Thursday in a statement.While using a new computer model to analyze Voyager data, scientists found the sun's distant magnetic field is made up of bubbles approximately 100 million miles wide. The bubbles are created when magnetic field lines reorganize. The new model suggests the field lines are broken up into self-contained structures disconnected from the solar magnetic field. The findings are described Thursday in the Astrophysical Journal.Like Earth, our sun has a magnetic field with a north pole and a south pole. The field lines are stretched outward by the solar wind or a stream of charged particles emanating from the star that interacts with material expelled from others in our corner of the Milky Way galaxy.The Voyager spacecraft, more than nine billion miles away from Earth, are traveling in a boundary region. In that area, the solar wind and magnetic field are affected by material expelled from other stars in our corner of the Milky Way galaxy."The sun's magnetic field extends all the way to the edge of the solar system," said astronomer Merav Opher of Boston University. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up."Understanding the structure of the sun's magnetic field will allow scientists to explain how galactic cosmic rays enter our solar system and help define how the star interacts with the rest of the galaxy.So far, much of the evidence for the existence of the bubbles originates from an instrument aboard the spacecraft that measures energetic particles. Investigators are studying more information and hoping to find signatures of the bubbles in the Voyager magnetic field data."We are still trying to wrap our minds around the implications of the findings," said University of Maryland physicist Jim Drake, one of Opher's colleagues.Launched in 1977, the Voyager twin spacecraft have been on a 33- year journey. They are en route to reach the edge of interstellar space. NASA's Jet Propulsion Laboratory built the spacecraft and continues to operate them.

BEIJING, July 15 (Xinhua) -- The Chinese Academy of Agricultural Sciences (CAAS) announced Friday that a group of international scientists has finished sequencing the genetic code of the potato.The Potato Genome Sequencing Consortium (PGSC), which is led by Chinese scientists and made up of 97 researchers from 14 countries, has sequenced the complete potato genome and published a report of its findings in the latest issue of the scientific journal Nature, said the CAAS.The research took six years and revealed that the potato contains about 39,000 genes, said the CAAS.Qu Dongyu, a potato farming specialist with the Crop Science Society of China and a promoter of the PGSC, said the study helped discover genes that define the growth and insect resistance of potatoes.The sequenced genome will enable scientists to create new varieties of potato that are high in yield and quality and more resistant to insects and diseases, he said.Huang Sanwen, a researcher with the CAAS and one of the three corresponding authors of the report, said the sequencing will also allow potato breeders to accelerate the breeding process of new seeds from 10 to 12 years to about 5 years.China is the world's top potato grower, with its farmers planting potatoes on nearly 90 million mu (6 million hectares) of land each year. The average yield per mu stands at 1,000 kg, only one-third of that harvested by countries with advanced technologies, Qu said.

LOS ANGELES, July 18 (Xinhua) -- The spacecraft Dawn of the National Aeronautics and Space Administration (NASA) has returned the first close-up image of the giant asteroid Vesta after entering its orbit for the first time last week, the Jet Propulsion Laboratory (JPL) announced on Monday.The image taken for navigation purposes shows Vesta in greater detail than ever before, said JPL in Pasadena, California.On July 15, Dawn became the first probe to enter orbit around an object in the main asteroid belt between Mars and Jupiter.When Vesta captured Dawn into its orbit, there were approximately 9,900 miles (about 16,000 kilometers) between the spacecraft and the asteroid.Vesta is 330 miles (about 530 kilometers) in diameter and the second most massive object in the asteroid belt.NASA's Dawn spacecraft obtained this image with its framing camera on July 17, 2011. It was taken from a distance of about 9,500 miles (15,000 kilometers) away from the protoplanet Vesta. Each pixel in the image corresponds to roughly 0.88 miles (1.4 kilometers). Ground- and space-based telescopes have obtained images of Vesta for about two centuries, but they have not been able to see much detail on its surface."We are beginning the study of arguably the oldest extant primordial surface in the solar system," said Dawn principal investigator Christopher Russell from the University of California, Los Angeles, which is responsible for Dawn's mission science. " This region of space has been ignored for far too long. So far, the images received to date reveal a complex surface that seems to have preserved some of the earliest events in Vesta's history, as well as logging the onslaught that Vesta has suffered in the intervening eons."Vesta is thought to be the source of a large number of meteorites that fall to Earth. Vesta and its new NASA neighbor, Dawn, are currently approximately 117 million miles (about 188 million kilometers) away from Earth. The Dawn team will begin gathering science data in August.Observations will provide unprecedented data to help scientists understand the earliest chapter of the solar system and pave the way for future human space missions, according to JPL."Dawn slipped gently into orbit with the same grace it has displayed during its years of ion thrusting through interplanetary space," said Marc Rayman, Dawn chief engineer and mission manager at NASA's JPL. "It is fantastically exciting that we will begin providing humankind its first detailed views of one of the last unexplored worlds in the inner solar system."Although orbit capture is complete, the approach phase will continue for about three weeks. During approach, the Dawn team will continue a search for possible moons around the asteroid; obtain more images for navigation; observe Vesta's physical properties; and obtain calibration data.In addition, navigators will measure the strength of Vesta's gravitational tug on the spacecraft to compute the asteroid's mass with much greater accuracy than has been previously available, according to JPL.Dawn will spend one year orbiting Vesta, then travel to a second destination, the dwarf planet Ceres, arriving in February 2015. The mission to Vesta and Ceres is managed by JPL for the agency's Science Mission Directorate in Washington.Dawn is a project of the directorate's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alaska.

CANBERRA, Sept. 9 (Xinhua) -- Managing other people at work triggers structural changes in the brain, protecting its memory and learning center well into old age, Australia's study revealed on Friday.Australia's University of New South Wales (UNSW) researchers have, for the first time, identified a clear link between managerial experience throughout a person's working life, and the integrity and larger size of an individual's hippocampus (the area of the brain responsible for learning and memory) at the age of 80. "We found a clear relationship between the number of employees a person may have supervised or been responsible for and the size of the hippocampus," Dr Michael Valenzuela, Leader of Regenerative Neuroscience in UNSW's School of Psychiatry, said in a statement released on Friday."This could be linked to the unique mental demands of managing people, which requires continuous problem solving, short term memory and a lot of emotional intelligence, such as the ability to put yourself in another person's shoes. Over time this could translate into the structural brain changes we observed."The findings confirmed that staying mentally active promotes brain health, potentially warding off neurodegenerative diseases such as Alzheimer's.Using MRI imagery in a cohort of 75-92 year-olds, researchers found larger hippocampal volumes in those with managerial experience compared to those without. The effect was also seen in women who had taken on managerial roles in nursing or teaching, for example.The study was presented at this week's Brain Sciences UNSW symposium Brain Plasticity The Adaptable Brain, held in Australia.

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.

来源：资阳报