Tuesday, September 14, 2010

OVER 50? YOU PROBABLY PREFER NEGATIVE STORIES ABOUT YOUNG PEOPLE

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When given a choice, older people prefer to read negative news, rather than positive news, about young adults, a new study suggests.

In fact, older readers who chose to read negative stories about young individuals actually get a small boost in their self-esteem, according to the results.

And what about younger people? Well, they just prefer not to read about older people.

These results come from a study of 276 Germans who were asked to read what they thought was a test version of an online magazine featuring carefully selected stories about younger and older people.

“Our results bolster the argument that people use the media to enhance their social identity,” said Silvia Knobloch-Westerwick, lead author of the study and associate professor of communication at Ohio State University.

“Older people and younger people have different goals when they use the media, and it shows in what they choose to read.”

Younger people, who are less certain about their own identity, prefer to read about other younger people to see how they live their lives, Knobloch-Westerwick said.

Older people, on the other hand, have greater certainty regarding their identity. However, living in a youth-centered culture, they may appreciate a boost in self-esteem. That’s why they prefer the negative stories about younger people, who are seen as having a higher status in our society.

Knobloch-Westerwick conducted the study with Matthias Hastall of Zeppelin University Friedrichshafen in Germany. Their results appear in the September 2010 issue of the Journal of Communication.

The study included 178 younger adults (18 to 30 years old) and 98 older adults (50 to 65 years old). All came to a computer laboratory, where they were told they were testing an online magazine that was not yet available to the public.

The experimental magazine was created specifically for the study and contained 10 carefully pre-tested stories. Each story focused on one individual, but there were two different versions: one that had a negative spin and one with a positive spin (each participant was offered just one of the two versions).

For example, one positive article was headlined (translated here from German) “Visitation rights gained after daring protest – Demonstration at 100 feet high a success.” The negative version had the headline, “Visitation rights denied despite daring protest – Demonstration at 100 feet high in vain.”

The stories included a photo of the person involved: half were clearly an older person and half were clearly a younger person.

Participants in the study were told they would not have time to read all the stories and were asked to click on the stories that they found interesting. Each was given a random mix of positive and negative stories about younger and older people.

The computer secretly logged which stories each participant clicked on and how long they spent reading each article.

All of the stories were extensively pretested by other participants to ensure that the stories were clearly positive or negative, and that the photos were clearly differentiated by age and that the people pictured were similar in how likeable they appeared, Knobloch-Westerwick said.

Older people have greater certainty regarding their identity. However, living in a youth-centered culture, they may appreciate a boost in self-esteem. That’s why they prefer the negative stories about younger people, who are seen as having a higher status in our society.

Results showed that the older participants were more likely to select negative articles about younger people, but they did not show a strong preference for either positive or negative stories about people in their own age group.

Younger people showed low interest in articles about older individuals – regardless of whether the stories were positive or negative. They did choose to read more positive stories about their own age group than they did negative stories, she said.

After participants finished browsing and evaluating the online magazine, they were given a short questionnaire aimed at measuring their self-esteem.

Results showed that younger people showed no differences in self-esteem based on what they had read. However, the more that older people read negative stories about younger individuals, the higher the older people’s levels of self-esteem tended to be.

This study came about because a previous study by the same researchers, using this same data, had produced unexpected results, Knobloch-Westerwick said. The original study had hypothesized that people prefer media messages that portray people like themselves – people of the same age and the same gender, in this case.

Overall, the original study found that was indeed true. However, the researchers were puzzled by the fact that older people in that first study seemed as equally interested in stories about younger people as they were in stories about older people like themselves.

“Now we know why older people liked reading about the younger people – they were looking for negative stories about them,” she said.

“Our new results go along with other research showing that people’s social identity helps shape what media messages we choose. Age is just one type of social identity which may affect our media choices.”

(Photo: OSU)

Ohio State University

LARGE CO2 RELEASE SPEEDS UP ICE AGE MELTING

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Radiocarbon dating is used to determine the age of everything from ancient artifacts to prehistoric corals on the ocean bottom.

But in a recent study appearing in the Aug. 26 edition of the journal, Nature, a Lawrence Livermore scientist and his colleagues used the method to trace the pathway of carbon dioxide released from the deep ocean to the atmosphere at the end of the last ice age.

The team noticed that a rapid increase in atmospheric CO2 concentrations coincided with a reduced amount of carbon-14 relative to carbon-12 (the two isotopes of carbon that are used for carbon dating and are referred to as radiocarbon) in the atmosphere.

“This suggests that there was a release of very ‘old’ or low 14/12CO2 from the deep ocean to the atmosphere during the end of the last ice age,” said Tom Guilderson, an author on the paper and a scientist at LLNL’s Center for Accelerator Mass Spectrometry.

The study suggests that CO2 release may speed up the melting following an ice age.

Radiocarbon in the atmosphere is regulated largely by ocean circulation, which controls the sequestration of CO2 in the deep sea through atmosphere-ocean carbon exchange. During the last ice age ( approximately 110,000 to 10,000 years ago), lower atmospheric CO2 levels were accompanied by increased atmospheric radiocarbon concentrations that have been credited to greater storage of CO2 in a poorly ventilated abyssal ocean.

“The ocean circulation was significantly different than it is today and carbon was being stored in the deep ocean in a manner that we don’t completely understand,” Guilderson said.

Using two sediment cores from the sub-Antarctic and subtropic South Pacific near New Zealand, the team dated the cores to be between 13,000 and 19,000 years old. Guilderson was able to use the carbon-14 in the cores as a tracer to determine not only when the large CO2 release occurred but the ocean pathway by which it escaped.

“In this case, the absence of a signal is telling us something important,” Guilderson said. “Deeper waters substantially depleted in carbon-14 were drawn to the upper layers and this is the main source of the CO2 during deglaciation.

Data suggests that the upwelling of this water occurred in the Southern Ocean, near Antarctica. In our cores off New Zealand, which lie in the path of waters which ‘turn over’ in the Southern Ocean, we don’t find anomalously low carbon-14/12 ratios.

This implies that either water which upwelled in the Southern Ocean, after 16,500 years ago, had a vigorous exchange with the atmosphere, allowing its 14C-clock to be reset, or the circulation was significantly different than what the current paradigm is. If the paradigm is wrong, then during the glacial and deglaciation, the North Pacific is much more important than we give it credit for,” Guilderson said.

The large CO2 release sped up the melting, he said.

As for CO2 emissions contributing to recent global warming, Guilderson said the CO2 release from the last ice age is not relevant.

“We can radiocarbon date the CO2 in the atmosphere now and what we’ve found is that the isotopic signature indicates that it is really due to the use of fossil fuels,” he said.

The average lifetime of CO2 in the atmosphere is on the order of 70-100 years.

(Photo: LLNL)

Lawrence Livermore National Laboratory

IMPACT HYPOTHESIS LOSES ITS SPARKLE

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About 12,900 years ago, a sudden cold snap interrupted the gradual warming that had followed the last Ice Age. The cold lasted for the 1,300-year interval known as the Younger Dryas (YD) before the climate began to warm again.

In North America, large animals known as megafauna, such as mammoths, mastodons, saber-tooth tigers and giant short-faced bears, became extinct. The Paleo-Indian culture known as the Clovis culture for distinctively shaped fluted stone spear points abruptly vanished, eventually replaced by more localized regional cultures.

What had happened?

One theory is that either a comet airburst or a meteor impact somewhere in North America set off massive environmental changes that killed animals and disrupted human communities.

In sedimentary deposits dating to the beginning of the YD, impact proponents have reported finding carbon spherules containing tiny nano-scale diamonds, which they thought to be created by shock metamorphism or chemical vapor deposition when the impactor struck.

The nanodiamonds included lonsdaleite, an unusal form of diamond that has a hexagonal lattice rather than the usual cubic crystal lattice. Lonsdaleite is particularly interesting because it has been found inside meteorites and at known impact sites.

In the August 30 issue of the Proceedings of the National Academy of Sciences, a team of scientists led by Tyrone Daulton, PhD, a research scientist in the physics department at Washington University in St. Louis, reported that they could find no diamonds in YD boundary layer material.

Daulton and his colleagues, including Nicholas Pinter, PhD, professor of geology at Southern Illinois University In Carbondale and Andrew C. Scott, PhD, professor of applied paleobotany of Royal Holloway University of London, show that the material reported as diamond is instead forms of carbon related to commonplace graphite, the material used for pencils.

“Of all the evidence reported for a YD impact event, the presence of hexagonal diamond in YD boundary sediments represented the strongest evidence suggesting shock processing,” Daulton, who is also a member of WUSTL's Center for Materials Innovation, says.

However, a close examination of carbon spherules from the YD boundary using transmission electron microscopy by the Daulton team found no nanodiamonds. Instead, graphene- and graphene/graphane-oxide aggregates were found in all the specimens examined (including carbon spherules dated from before the YD to the present). Importantly, the researchers demonstrated that previous YD studies misidentified graphene/graphane-oxides as hexagonal diamond and likely misidentified graphene as cubic diamond.

The YD impact hypothesis was in trouble already before this latest finding. Many other lines of evidence — including: fullerenes, extraterrestrial forms of helium, purported spikes in radioactivity and iridium, and claims of unique spikes in magnetic meteorite particles — had already been discredited. According to Pinter, “nanodiamonds were the last man standing.”

“We should always have a skeptical attitude to new theories and test them thoroughly,” Scott says, “and if the evidence goes against them they should be abandoned.”

(Photo: WUSTL)

Washington University in St. Louis

FREE AS A BIRD?

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It may seem like birds have the freedom to fly wherever they like, but researchers at the University of Missouri have shown that what's on the ground has a great effect on where a bird flies. This information could be used by foresters and urban planners to improve bird habitats that would help maintain strong bird populations.

"Movement of individuals influences nearly every aspect of biology, from the existence of a single population to interactions within and among species," said Dylan Kesler, assistant professor in fisheries and wildlife at the University of Missouri's School of Natural Resources. "Movement determines where individual birds procreate. How they spread across the landscape affects who meets whom, which in turn dictates how genes are spread."

Kesler has found that non-migrating resident birds tend to travel over forest "corridors," which are areas protected by trees and used by wildlife to travel. Birds choose to travel over forests because they can make an easier escape from predators as well as find food.

Man-made features such as roads, as well as gaps forests from agriculture or rivers, can restrict birds to certain areas. When forests are removed, bird populations become isolated and disconnected, which can lead to inbreeding and weaker, more disease-prone birds.

Earlier this summer, Kesler and MU graduate student Allison Cox tagged 33 juvenile red-bellied woodpeckers in Missouri's Mark Twain National Forest. Kesler chose to study the red-bellied woodpecker because the bird lives in the same area year-round and is very loyal to specific sites. The tags used by the researchers enable their team to track the birds' daily flights using radiotelemetry and GPS technology. The tags are designed to fall off the birds after four months. The summer and fall months are important because this is when young birds are most active, establishing territories and finding mates, studies say.

The research team also hopes to discover more about natal dispersal, the time interval between when a bird moves from where it is hatched to an area where it will breed. Very little is known about what influences natal dispersal.

"In many territorial resident birds, natal dispersal is the only time an individual bird makes a substantial movement from one location to another," Kesler said. "Natal dispersal is, therefore, integral to gene flow among populations, colonizing vacant habitat, inbreeding avoidance and maintaining optimal population densities."

This year's work builds upon research Kesler has been conducting since 2005 on three species of woodpeckers and two Pacific island kingfishers. The study is funded by a University of Missouri program to encourage new faculty. Results will be published this fall in conservation-oriented science journals. Results from Kesler's previous research about dispersal appeared in the nation's top ornithological journal, The Auk, and another paper will soon be published in Behavioral Ecology.

(Photo: University of Missouri)

University of Missouri

BREAKTHROUGH NEWS INVOLVING MIGRAINE

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Investigators from the International Headache Genetics Consortium, a world-wide collaboration of researchers, have identified the first-ever genetic risk factor associated with common types of migraine. Researchers looked at genetic data of more than 50,000 people and found new insights into the triggers for migraines attacks, which commonly begin in puberty and but tend to affect people aged between 20 to 45 years of age. Migraine affects approximately one in six women and one in 12 men.

"This is a major stride in migraine science," said David W. Dodick, president of the American Headache Society, and professor of neurology at the Mayo Clinic College of Medicine, and the director of the Headache Program in Phoenix, Arizona. Underscoring the significance of the findings, Dr. Dodick said, "It is the first study to identify a genetic risk factor for the common subtypes of migraine, and provides some support for the general concept of migraine as a state of brain hyperexcitability. It also supports previous research findings on the potential role of glutamate in migraine, as well novel glutamate modulating drugs that are currently being tested in migraine. Further work may provide insight into the precise molecular mechanism(s) of migraine as well as future targets for novel therapies."

The team found that patients with a particular DNA variant on Chromosome 8 between two genes -- PGCP and MTDH/AEG-1 -- have a significantly greater risk for developing migraine. It appears that the associated DNA variant regulates levels of glutamate -- a chemical, known as a neurotransmitter, which transports messages between nerve cells in the brain. Prevention of the build up of glutamate at the synapse (space between nerve endings) may provide a promising target for novel therapeutics to ease the burden of the disease, according to Dr. Dodick. Although researchers have in the past described genetic mutations giving rise to rare and extreme forms of migraine, this is the first time a team has identified a genetic variant giving rise to the common forms of the condition.

American Headache Society

HIGH-SPEED FILTER USES ELECTRIFIED NANOSTRUCTURES TO PURIFY WATER AT LOW COST

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By dipping plain cotton cloth in a high-tech broth full of silver nanowires and carbon nanotubes, Stanford researchers have developed a new high-speed, low-cost filter that could easily be implemented to purify water in the developing world.

Instead of physically trapping bacteria as most existing filters do, the new filter lets them flow on through with the water. But by the time the pathogens have passed through, they have also passed on, because the device kills them with an electrical field that runs through the highly conductive "nano-coated" cotton.

In lab tests, over 98 percent of Escherichia coli bacteria that were exposed to 20 volts of electricity in the filter for several seconds were killed. Multiple layers of fabric were used to make the filter 2.5 inches thick.

"This really provides a new water treatment method to kill pathogens," said Yi Cui, an associate professor of materials science and engineering. "It can easily be used in remote areas where people don't have access to chemical treatments such as chlorine."

Cholera, typhoid and hepatitis are among the waterborne diseases that are a continuing problem in the developing world. Cui said the new filter could be used in water purification systems from cities to small villages.

Filters that physically trap bacteria must have pore spaces small enough to keep the pathogens from slipping through, but that restricts the filters' flow rate.

Since the new filter doesn't trap bacteria, it can have much larger pores, allowing water to speed through at a more rapid rate.

"Our filter is about 80,000 times faster than filters that trap bacteria," Cui said. He is the senior author of a paper describing the research that will be published in an upcoming issue of Nano Letters. The paper is available online now.

The larger pore spaces in Cui's filter also keep it from getting clogged, which is a problem with filters that physically pull bacteria out of the water.

Cui's research group teamed with that of Sarah Heilshorn, an assistant professor of materials science and engineering, whose group brought its bioengineering expertise to bear on designing the filters.

Silver has long been known to have chemical properties that kill bacteria. "In the days before pasteurization and refrigeration, people would sometimes drop silver dollars into milk bottles to combat bacteria, or even swallow it," Heilshorn said.

Cui's group knew from previous projects that carbon nanotubes were good electrical conductors, so the researchers reasoned the two materials in concert would be effective against bacteria. "This approach really takes silver out of the folk remedy realm and into a high-tech setting, where it is much more effective," Heilshorn said.

But the scientists also wanted to design the filters to be as inexpensive as possible. The amount of silver used for the nanowires was so small the cost was negligible, Cui said. Still, they needed a foundation material that was "cheap, widely available and chemically and mechanically robust." So they went with ordinary woven cotton fabric.

"We got it at Wal-mart," Cui said.

To turn their discount store cotton into a filter, they dipped it into a solution of carbon nanotubes, let it dry, then dipped it into the silver nanowire solution. They also tried mixing both nanomaterials together and doing a single dunk, which also worked. They let the cotton soak for at least a few minutes, sometimes up to 20, but that was all it took.

The big advantage of the nanomaterials is that their small size makes it easier for them to stick to the cotton, Cui said. The nanowires range from 40 to 100 billionths of a meter in diameter and up to 10 millionths of a meter in length. The nanotubes were only a few millionths of a meter long and as narrow as a single billionth of a meter. Because the nanomaterials stick so well, the nanotubes create a smooth, continuous surface on the cotton fibers. The longer nanowires generally have one end attached with the nanotubes and the other end branching off, poking into the void space between cotton fibers.

"With a continuous structure along the length, you can move the electrons very efficiently and really make the filter very conducting," he said. "That means the filter requires less voltage."

The electrical current that helps do the killing is only a few milliamperes strong – barely enough to cause a tingling sensation in a person and easily supplied by a small solar panel or a couple 12-volt car batteries. The electrical current can also be generated from a stationary bicycle or by a hand-cranked device.

The low electricity requirement of the new filter is another advantage over those that physically filter bacteria, which use electric pumps to force water through their tiny pores. Those pumps take a lot of electricity to operate, Cui said.

In some of the lab tests of the nano-filter, the electricity needed to run current through the filter was only a fifth of what a filtration pump would have needed to filter a comparable amount of water.

The pores in the nano-filter are large enough that no pumping is needed – the force of gravity is enough to send the water speeding through.

Although the new filter is designed to let bacteria pass through, an added advantage of using the silver nanowire is that if any bacteria were to linger, the silver would likely kill it. This avoids biofouling, in which bacteria form a film on a filter. Biofouling is a common problem in filters that use small pores to filter out bacteria.

Cui said the electricity passing through the conducting filter may also be altering the pH of the water near the filter surface, which could add to its lethality toward the bacteria.

Cui said the next steps in the research are to try the filter on different types of bacteria and to run tests using several successive filters.

"With one filter, we can kill 98 percent of the bacteria," Cui said. "For drinking water, you don't want any live bacteria in the water, so we will have to use multiple filter stages."

Cui's research group has gained attention recently for using nanomaterials to build batteries from paper and cloth.

(Photo: Stanford U.)

Stanford University

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