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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.

RIO DE JANEIRO, Aug. 31 (Xinhua) -- The Brazilian city of Rio de Janeiroe may have an unprecedented dengue fever epidemic next summer, its mayor warned on Wednesday.The increasing number of dengue fever cases in the past few months shows similarities to the months predecing the 2002 and 2008 epidemics, Mayor Eduardo Paes said."Everything points to a new cycle of the disease, certainly the worst epidemic in Rio's history," he said.In 2008, Rio registered some 250,000 cases of dengue fever, with 174 people confirmed dead from the disease. In 2002, Rio had some 290,000 dengue fever cases and 91 people died.In efforts to halt the spread of the disease, Paes has declared a state of alert and is determined to take a series of measures to eliminate the habitat of the Aedes aegypti mosquito, which transmits dengue fever through its bite.Paes also announced an increase in the number of health care units for dengue fever patients. The total cost of a dengue prevention and combat program, which is expected to last until April 2012, will reach 42 million reais (26.25 million U.S. dollars).There is no vaccine against dengue fever, but Brazilian scientists are currently working on one which will immunize against four types of the disease.

CANBERRA, Aug. 17 (Xinhua) -- Australian scientist on Wednesday said his international research team has discovered the trick on how butterfly learn to change its wing pattern to avoid being eaten by birds.The Amazonian butterfly, Heliconius numata, has learnt to carry out a single genetic switch to alter its wing pattern so it appears to be another bad-tasting butterfly that birds will avoid.Dr. Siu Fai (Ronald) Lee from the Department of Genetics and Bio21 Institute at Australia's University of Melbourne was part of the international research team, which was led by scientists at Centre National de la Recherche Scientifique (CNRS) and the University of Exeter in United Kingdom.Dr. Lee said the historical mystery had puzzled researchers for decades."Charles Darwin was puzzled by how butterflies evolved such similar patterns of warning coloration," Dr. Siu Fai (Ronald) Lee from the Department of Genetics and Bio21 Institute at the University of Melbourne told Western Australia Today."We have now solved this mystery, identifying the region of chromosome responsible for changing wing pattern."He said the research team identified a genetic switch known as a supergene, which allowed the butterfly to morph into several different forms, allowing one species to mimic another."It is amazing that by changing just one small region of the chromosomes, the butterfly is able to fool its predators by mimicking a range of different butterflies that taste bad," he said."The butterflies rearrange this supergene DNA like a small pack of cards, and the result is new wing patterns. It means that butterflies look completely different but have the same DNA."There are other butterflies doing similar tricks, but this is the most elegant one."I was just fascinated by how elegant they were."He said the discovery proves that small chromosomal changes can preserve successful gene combinations, and thus help a species to adapt.The findings of the study are published on August 14 in the international journal Nature.

VIENNA, Aug. 11 (Xinhua) -- Austrian researchers have developed a method of using fungi and produced enzymes to split Polyethylene Terephthalate (PET) material into their initial state, enabling the recovery of all individual components, said the Austrian Center of Industrial Biotechnology (ACIB) Thursday in a press release.Enzyme is a special protein that acts as biological catalyst, for example, bacteria and fungi in the nature can break down long chain molecules.Researchers from the Technical University of Graz, the Technical University of Vienna and the Agricultural University of Vienna jointly found that efficient enzymes are capable to break and split PET into small fragments.With different methods, the researchers forced the fungi to overproduce their precious "split-tools" after they are modified and improved by genetic engineering.Through the new method developed by the ACIB, it is now possible to decompose the PET polymer to its initial monomers with high product quality and from this to produce new high-quality materials again.This circuit avoids waste and thus saves resources and is friendly to the environment, said Geog Guebitz, head of the Research Department on Enzymes and Polymers in the ACIB.He further explained that the ACIB has established a partnership with some industrial enterprises to carry out application experiments. From the current splitting time of 24 hours, the researchers expect to shorten the whole process to "a few hours," he added.PET is a common plastic material in the polyester family, widely used in the textile industry. PET film is mainly used in electrical insulation materials, which can be also used for production of film, X-ray films and computer taps, even to produce plastic bottle and other blow molding products.

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