天津在线咨询白癜风医院(河北白癜风的特征及诱因) (今日更新中)

WASHINGTON, Aug. 11 (Xinhua) -- The unique fossils of an adult plesiosaur and its unborn baby may provide the first evidence that these ancient animals gave live birth like mammals, according to a new study to be published Friday in the journal Science.The 78-million-year-old, 15.4-foot-long (4.7-meter-long) adult specimen is a Polycotylus latippinus, one of the giant, carnivorous, four-flippered reptiles that lived during the Mesozoic Era.Dr. Robin O'Keefe of Marshall University in West Virginia and Dr. Luis Chiappe, Dinosaur Institute director of the Natural History Museum in Los Angeles County, have determined that it is the fossil of an embryonic marine reptile contained within the fossil of its mother.The embryonic skeleton contained within shows much of the developing body, including ribs, 20 vertebrae, shoulders, hips, and paddle bones.O'Keefe and Chiappe have also determined that plesiosaurs were unique among aquatic reptiles in giving birth to a single, large offspring, and that they may have lived in social groups and engaged in parental care.Although live birth has been documented in several other groups of Mesozoic aquatic reptiles, no previous evidence of it has been found in the important order of plesiosaurs."Scientists have long known that the bodies of plesiosaurs were not well suited to climbing onto land and laying eggs in a nest," O'Keefe said."So the lack of evidence of live birth in plesiosaurs has been puzzling. This fossil documents live birth in plesiosaurs for the first time, and so finally resolves this mystery."

BEIJING, Sept. 6 (Xinhuanet) -- The amount of space junks floating in Earth's orbit has reached a critical level, warned scientists.The future space missions may become too dangerous to fly for a risk of colliding with space junks, said a report released recently by the U.S. National Research Council (NRC).The kinds of space junks range from huge, the report said, there are thousands of discarded satellites and rocket boosters and countless tiny pieces of daily gabages from space missions.The debris are traveling in orbit at 17,500mph, at such a speed even a tiny clash can destroy a spacecraft.The NRC recommended that NASA should launch a plan to clean up the floating debris and called on other major space nations' cooperation."The current space environment is growing increasingly hazardous to spacecraft and astronauts," said Kessler, an ex-NASA researcher, "NASA needs to determine the best path forward for tackling the multifaceted problems caused by meteoroids and orbital debris that put human and robotic space operations at risk."

TOKYO, June 19 (Xinhua) -- The Japanese gaming company Sega Corp. said in a statement on Sunday some personal information from more than 1.2 million registered users had been stolen after the website of its subsidiary based in Britain was hacked.The Sega Pass website operated by Sega Europe limited was designed to provide product news. The services were shutdown following the breach detected on Friday. They are still not resumed on the official website of the company late Sunday night and the company said it is investigating the hacking.The company said most of the users of the hacked website are in Europe and North America. A similar cyberattack had troubled the Sony group earlier in April. The hacking affected about 100 million people.

BEIJING, Aug. 22 (Xinhuanet) -- Researchers have discovered how a human egg captures an incoming sperm for fertilization, paving the way to help couples suffering from infertility, according to media reports on Monday.An international team of researchers found that a sugar chain known as the sialyl-lewis-x sequence (SLeX) makes the outer coat of the egg “sticky,” which has proven to be helpful in binding the egg and the sperm.As a result, this observation has filled in a huge gap in the understanding of fertility and provides hope for ultimately helping couples who currently cannot conceive.Scientists and doctors know that a sperm identifies an egg when proteins on the head of the sperm match and bind to a series of specific sugars in the egg’s outer coating. With a successful match of proteins, the outside surfaces of the sperm and egg then bind together before merging, which is then followed by delivery of sperm’s DNA into egg.To identify this molecules, the researchers used ultra-sensitive mass-spectrometric imaging technology to observe and identify which molecules are most likely to be key in the binding process.They experimented with a range of synthesised sugars in the laboratory and found that it is SLeX that specifically binds sperm to an egg.According to the World Health Organisation, infertility affects about 15 percent of reproductive-aged couples around the world and almost one in every seven couples in Britain has problems conceiving a child for various reasons.

BEIJING, June 28 (Xinhuanet) -- The figure of adults with diabetes has risen to 347 million worldwide, which is more than doubled in the past three decades, according to a study published in the British journal Lancet.The study, which analyzed data compiled from 2.7 million participants aged 25 and over from across the world, shows approximately 138 million in China have diabetes, and 36 million in the United States.Among high-income countries, diabetes rates were the highest in the U.S., Greenland, Malta, New Zealand, and Spain. The Netherlands, Austria, and France boasted the lowest rates, suggested the study published online by The Lancet journal on June 25.Majid Ezzati, a lead author of the study, said on Reuters: “Diabetes is becoming more common almost everywhere in the world.”Danaei added: “Unless we develop better programs for detecting people with elevated blood sugar and helping them to improve their diet and physical activity and control their weight, diabetes will inevitably continue to impose a major burden on health systems around the world.”

来源：资阳报