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沙发
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发表于 2014-6-18 08:34:38
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Part II: Speed
World Cup teams could suffer from too much talent
BY Nathan Collins | 17 June 2014
[Time 2]
There's such a thing as too much talent, at least when it comes to sports teams. Psychologists reached that conclusion by studying World Cup soccer games, where players from top professional clubs compete on national squads alongside others from lesser leagues. Analyzing rankings from the 2010 and 2014 World Cup qualification periods, the researchers found that a team benefits from more elite footballers until they make up about three-quarters of the squad. Go past that, and the team’s ranking starts to decline. Two American sports suggest why. In the National Basketball Association, having more top-scoring players helps only until they make up about 60% of the team, whereas Major League Baseball teams rack up more wins as their proportion of top players goes up. The difference? Because their roles overlap more, soccer and basketball players alike can end up fighting over the ball, competing with each other for the most points. In baseball, the various positions are far more specialized. The results, to be published in an upcoming issue of Psychological Science, might be news to French national team coach Didier Deschamps. After five losses last year, Deschamps told Agence France-Presse that the more players he could get from elite French and European professional teams, the better his team (including forward Karim Benzema, above, playing Honduras yesterday) would perform in the future. Maybe he’s got it backward: The more top players he has, the more they’ll just hog the ball.
[240 words]
Source: science
http://news.sciencemag.org/brain-behavior/2014/06/world-cup-teams-could-suffer-too-much-talent?rss=1
Antarctic icebergs decimating seafloor life
BY Carolyn Gramling | 17 June 2014
[Time 3]
A decade ago, the sea floor off the coast of the west Antarctic Peninsula (WAP) was a patchwork quilt of different colors and species. But now, icebergs are increasingly scouring the sea floor as they drift close to shore, fundamentally altering that rich ecosystem in the process. That’s the conclusion of a study reported this week in Current Biology. Each winter, the WAP sea surface freezes over, forming a skin of “fast ice” that holds back the bergs. But with climate change, the WAP is experiencing rapid regional warming, with fewer days each year of fast ice—letting the icebergs into the shallows more often, where they carve huge gashes through the habitat of the colorful, tentacled invertebrate animals carpeting the sea floor. The team examined the spatial distribution, diversity, and interactions between and within species from 1997 to 2013, along with scours from the ice each year. What it found was sobering: Most species weren’t able to recover from the increasingly frequent pounding by the ice. Instead, one species—a nondescript white mosslike animal encrusted on the rocks—emerged as an all-conquering winner, edging out the rest by its sheer ability to take a beating. It now has a near-monopoly in the area, the study found—and that could make the whole region more vulnerable to invading species.
[219 words]
Source: science
http://news.sciencemag.org/climate/2014/06/antarctic-icebergs-decimating-seafloor-life
Mystery of 1918 Flu That Killed 50 Million Solved?
Children born in the late 1800s lacked exposure to influenza before the deadliest pandemic of the early 20th century hit.
BY Dan Vergano| 28 April, 2014
[Time 4]
Scientists announced Monday that they may have solved one of history's biggest biomedical mysteries—why the deadly 1918 "Spanish flu" pandemic, which killed perhaps 50 million people worldwide, largely targeted healthy young adults. (Related: "How Flu Viruses Attack.")
The explanation turns out to be surprisingly simple: People born after 1889 were not exposed as kids to the kind of flu that struck in 1918, leaving them uniquely vulnerable. Older people, meanwhile, had been exposed to flu strains more closely related to the 1918 flu, offering some immunity.
Simply put, the Spanish flu owed its ferocity to a switch in dominant influenza varieties that had occurred a generation earlier. (Related: "1918 Flu That Killed 50 Million Originated in China.")
"All a matter of timing," says virologist Vincent Racaniello of Columbia University in New York, who was not part of the study.
Researchers involved in the study looked at the evolutionary history of the components of the 1918 flu, which was built of genes from human and avian flu strains. They unraveled the history of dominant flu strains stretching back to 1830.
The evolutionary biologists found that a worldwide 1889 outbreak of the so-called Russian flu, the H3N8 flu virus, left a generation of children that had not been exposed to anything resembling the Spanish flu, which was an H1N1 strain. (The H and N in the flu designation stand for proteins called hemagglutinin and neuraminidase, respectively).
[235 words]
[Time 5]
The spread of a more closely related H1 flu variety after 1900 provided partial immunity to children born after that time. That closed the window of vulnerability.
"You have the most deadly flu pandemic in history essentially leaving the elderly, its most frequent victims, completely alone," says biologist Michael Worobey of the University of Arizona in Tucson, who led the Proceedings of the National Academy of Sciences report.
Instead, people aged 18 to 29 died in droves during the outbreak, which killed about 1 in 200 of victims.
Experts have suggested that such a window of vulnerability partly explained the 1918 pandemic, Racaniello notes. But the new study provides computational evidence that the 1918 flu's precursor originated around 1907, he says, and explains how the window of vulnerability opened and closed for the disease.
The new finding may help public health officials deal with future pandemics, amid current worries about deadly avian flu strains jumping to humans.
It may also alter how we vaccinate against future flu outbreaks, keying vaccines not to current seasonal flavor, but instead to strains that people didn't gain immunity to as children. (Related: "Influenza—A Killer Cold?")
Flu Fluctuations
Seasonal flu strains typically enjoy decades of dominance in the human population. These periods are often capped by outbreaks of new flu varieties, such as the 2009 H1N1 flu pandemic that led to the current reign of this strain of flu, which killed perhaps 284,000 people worldwide, according to the U.S. Centers for Disease Control and Prevention.
"The seasonal drift is normal and is the reason why we have yearly vaccines produced to protect against these seasonal changes," says immunologist Michael Gale, Jr., of the University of Washington in Seattle.
[284 words]
[Time 6]
The key to the team's reconstruction was the realization that flu genes evolve at different speeds in birds, pigs, and people, Worobey says (it's faster in chickens, for example). Once the evolution of flu strains is reset with timing tuned to each carrier species, "the picture came clear," he says.
Rather than a sudden movement of avian flu genes in 1918 explaining the Spanish flu, the study suggests that many of them moved into seasonal flu after 1900. A change in the kind of hemagglutinin used by an already-existent flu strain likely led to the pandemic around 1918.
Universal Vaccine
The overall message of the study is a hopeful one, say the researchers, because the bacterial pneumonia secondary to the 1918 flu that killed most of its victims is treatable with modern antibiotics.
"If there was something particularly deadly about the 1918 strain, then you are out of luck when something like it happens again," Worobey says. "But if this is just the effect of lack of exposure, then we can be more confident of treatment."
If that's the case, the makers of future flu vaccines may want to tune their ingredients to people's ages, aiming to arm them against flu strains they likely missed exposure to during childhood, the prime age for getting the flu.
"It really offers a lot of support for a 'universal' flu vaccine that aims to prevent all varieties of flu," Worobey says. Such a vaccine would be aimed at all strains of flu viruses, not just the current dominant seasonal ones.
[257 words]
Source: nationalgeographic
http://news.nationalgeographic.com/news/2014/04/140428-1918-flu-avian-swine-science-health-science/
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