Tuesday, October 19, 2010


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You’d think that people choosing to live near to outdoor recreation amenities would have a lower body mass index, thanks to an increase in all that healthy outdoor activity right on one’s doorstep. Yet a new University of Alberta study looking at the relationship between reasons for choosing a neighbourhood to live in, physical activity and BMI, shows that’s simply not the case.

In fact, researchers found that those who said choosing a neighbourhood that was close to outdoor recreation opportunities was important to them actually showed an increase in BMI over the six years of a longitudinal study conducted from 2002 to 2008, and led by Tanya Berry of the Faculty of Physical Education and Recreation.

“One of the things we analyzed in this paper was the movers and non-movers,” says Berry. “Those who had moved over the six years of the study and had indicated that choosing a neighbourhood for ease of walking was very important to them had a very stable BMI and didn’t change much over the six years.”

Berry and her team conducted two studies, one longitudinal (from 2002–2008 with 822 participants) and one cross-sectional (2008 with 1,505 participants), to look at the relationship between BMI and neighbourhood walkability, socio-economic status, reasons for choosing their neighbourhood, how physically active they were, fruit and vegetable intake, and demographic variables such as age, gender, job status and education, which were self-reported.

Berry says the relationship between those who chose to move to a walkable neighbourhood and BMI was clear. “For those people who had moved for ease of walking and thought it was important, their BMIs didn’t change and they were able to maintain their weight. But for those for whom it was not important at all, they showed an increase in BMI and that was matched with the cross-sectional data.”

Berry says that, as expected, those in lower socio-economic status neighbourhoods had higher BMIs. “Socio-economic status is an important factor and we really should be paying more attention to how to help people in lower SES neighbourhoods overcome the barriers they face to health.

“Those who are choosing neighbourhoods because they can walk are, at least in terms of BMI, the healthiest of all. So this is a very important factor in the built environment/BMI relationship and needs further study.”

University of Alberta


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New research has linked psychosis with an abnormal relationship between two signalling chemicals in the brain. The findings, published in the journal Biological Psychiatry, suggest a new approach to preventing psychotic symptoms, which could lead to better drugs for schizophrenia.

Schizophrenia is one of the most common severe mental health conditions. Sufferers experience symptoms of psychosis – an inability to distinguish between reality and imagination – such as hallucinations and delusions. The condition tends to begin in the late teens or twenties, and usually persists for the rest of the sufferer’s life.

Brain chemicals called neurotransmitters carry signals from one nerve cell to another. Research has linked schizophrenia with abnormally high levels of a neurotransmitter called dopamine in a region of the brain called the striatum. Drugs currently used to treat schizophrenia block the effects of dopamine in the brain. These drugs are not effective for all patients, and can have serious side effects.

The new pilot research, funded by the Medical Research Council (MRC), provides evidence that high levels of dopamine in people with psychotic symptoms occur as a consequence of changes in another brain chemical, glutamate. Glutamate-releasing cells in a brain region called the hippocampus connect to the striatum and influence the activity of dopamine-releasing cells. Drugs that interfere with glutamate signals in the brain might therefore be able to prevent psychotic symptoms in people with schizophrenia.

“Schizophrenia is a devastating illness that destroys the lives of people who are afflicted and those around them,” said Dr James Stone of the Department of Medicine at Imperial College London, first author of the study. “At the moment, the drugs we have just aren’t adequate. They don’t help everybody, and they don’t stop some of the most debilitating symptoms.”

The researchers carried out brain scans on 16 people with an at-risk mental state for psychosis and 12 healthy volunteers, to measure the levels of glutamate and dopamine. In people with early signs of psychotic symptoms, there was a negative correlation between glutamate levels in the hippocampus and dopamine levels in the striatum area. There was a particularly marked correlation in the subjects who went on to develop psychosis later. There was no correlation in the healthy subjects.

“In healthy volunteers, there’s no clear relationship between glutamate and dopamine, but in people with early signs of psychosis, we see this abnormal relationship,” Dr Stone said. “This suggests that the signalling pathway between the hippocampus and the striatum is dysfunctional, and we might be able to treat this by targeting the glutamate system. If drugs that act on glutamate signalling can prevent psychotic symptoms, it would mean a real shift in the way that people are treated for schizophrenia.

“The next step will be to see if these results are confirmed in a larger group of people. There are already a number of promising drug candidates that interfere with glutamate signalling, so hopefully in a few years we’ll be able to start testing new treatments for people with schizophrenia.”

Professor Chris Kennard, chair of the MRC Neuroscience and Mental Health Board, said:

“Studies like these are helping to unravel the complex mechanisms of psychiatric illness and bring us a step closer to more effective, targeted drugs for patients with schizophrenia. The MRC funds research like this in order to bring scientific findings from the lab bench to patient bedside, more quickly. If we can develop new drugs that prevent psychotic symptoms, it would mean a real benefit for patients with schizophrenia.”

(Photo: ICL)



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You’ve heard them at tennis matches – loud, emphatic grunts with each player’s stroke. A new study by University of British Columbia and University of Hawaii researchers suggest these grunts may hinder opponents’ ability to accurately perceive and respond to the ball.

Scott Sinnett, assistant professor of psychology at the University of Hawaii at Mānoa, and Alan Kingstone, psychology professor at UBC, are the first to study the effects of noise on shot perception during a tennis match. Their work is published in an online issue of Public Library of Science ONE.

In the study, UBC undergraduate students viewed videos of a tennis player hitting a ball to either side of a tennis court in a laboratory setting. Half of the shots were accompanied with a brief, 60-decibel sound at the same time as contact, comparable in volume to the grunts of such tennis stars as Maria Sharapova and Rafael Nadal.

Participants were required to indicate the direction of the shot in each video clip on a keyboard as quickly and accurately as possible. According to the study, the “grunts” produced significantly slower response times and more decision and accuracy errors for participants.

“Conservatively, our findings suggest that a tennis ball struck along with a loud grunt can travel an extra two feet in the air before the opponent is able to respond,” says Sinnett, adding that some professional tennis players’ grunts are as loud as 100 decibels. “This could increase the likelihood that opponents are wrong-footed, or out of position, and make returning the ball more difficult.”

If the laboratory findings translate onto the tennis court, Sinnett says the effects of grunts would be even greater on faster surfaces, such as the grass courts of Wimbledon or hard courts of the Australian and U.S. Open.

“This phenomenon of grunting in tennis is a perfect real-world scenario to explore the larger question of sound and its relationship to our ability to perceive the world,” says Sinnett, who conducted the work as a postdoctoral fellow at UBC. “The study raises a number of interesting questions for tennis. For example, if Rafael Nadal is grunting and Roger Federer is not, is that fair? Are there strategies players can use to limit the negative effects of these sounds?”

Sinnett, a Vancouver native, is now researching whether top tennis players have developed strategies to mitigate the effects of opponents’ grunting.

University of British Columbia


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It's easy to be a pessimist in a world full of calamities. But for those worried about the continuing availability of natural resources, data from the ocean makes a good case for optimism, says economic geologist Lawrence Cathles.

In a review paper published June 23 online in the journal Mineralium Deposita, Cathles, Cornell professor of earth and atmospheric sciences, writes that while land-based deposits may be a dwindling source of valuable minerals, deposits on the ocean floor could power humanity for centuries.

The minerals, including sulfur, copper, zinc, iron and precious metals, are contained in volcanogenic massive sulfide (VMS) deposits that form on the ocean floor where tectonic plates pull apart and allow magma (molten rock) to invade the Earth's 3.7-mile- (6 kilometer-) thick crust. The magma heats seawater to 662 degrees Fahrenheit (350 degrees Celsius) and moves it through the ocean crust via convection; and the seawater deposits the minerals where it discharges along the ridge axis.

According to model simulations by Cathles and colleagues combined with heat flow measurements from the 1980s around the Galapagos Islands, the seawater convection cools the entire crust -- "like a homeowner who lights a fire in his fireplace for the express purpose of cooling his house," said Cathles.

That knowledge, along with the known thickness of the ocean crust, allows researchers to calculate the quantity of dissolved minerals that could be transported over each square meter of ocean floor.

If just 3 percent of the dissolved minerals precipitate -- an estimate based on earlier studies -- the ocean floor would hold reserves vastly greater than those on land, Cathles said.

In the case of copper -- a key component in construction, power generation and transmission, industrial machinery, transportation, electronics, plumbing, heating and cooling systems, telecommunications and more -- calculations show that just half of the total accumulated amount could be enough to bring the world's growing population up to a modern standard of living and maintain it for centuries.

"I think there's a good chance that it's a lot more than 3 percent," Cathles said. "But even just taking 3 percent, if you calculate how long the copper on the ocean floor would last, just half of it could last humanity 50 centuries or more.

"You go back to Christ, and then you go twice as far again, and you've got that much copper," he said. "That's everyone living at a European standard of living, essentially forever." Equally large quantities of uranium, lithium, phosphate, potash and other minerals are dissolved in ocean water and could be extracted, he added.

With the necessary precautions, extracting the underwater deposits may also be a more environmentally friendly process than mining on land, Cathles said.

And it could provide other benefits, both scientific and psychological. Undersea exploration around ocean ridges could open doors to new research on the fundamental processes behind the formation of Earth's crust, he noted; and a more positive outlook on the future could lead to fewer wars and more positive engagement.

"We are not resource limited on planet Earth. For a human on Earth to complain about resources is like a trillionaire's child complaining about his allowance or inheritance. It just doesn't have much credibility in my view," he said.

"I think there's real risk if we don't really carefully, and in a credible way, articulate that there are enough resources for everybody," he added. "We don't have to fight over these things."

Cornell University


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Geoengineering could prevent the potentially catastrophic climate-change tipping points that loom just ahead, reports a new Cornell study.

Cornell earth system scientist Charles Greene, the lead author of the study published in the September-October issue of Solutions magazine (Vol. 1, No. 5), says time is running out, yet governments have done little to reverse rising carbon dioxide (CO2) levels.

Many scientists warn that to avoid excessive warming, sea level rise and extreme weather, CO2 in the atmosphere needs to be reduced to 350 parts-per-million (ppm) by the end of this century from the current level of around 390 ppm.

If actions aren't taken soon, ocean acidification and greenhouse warming in the atmosphere will reach a tipping point this century that will take more than 1,000 years to reverse, the paper warns.

It suggests that one way to reduce atmospheric CO2 by the end of the century is by setting up fields of air-capture devices that absorb CO2, very similar to the carbon capture and storage technology being developed for coal plants. The devices would use algal bioenergy as a power source to capture, extract and pipe CO2 for storage or industrial use. Algae provide a preferred bioenergy source relative to land plants because they are more productive, more efficient in their use of nutrients and do not need to compete with food crops for prime agricultural land, Greene said.

The price tag for using this technology over the remainder of the century? Some $85.5 trillion to remove the 855 gigatons of carbon needed to bring atmospheric CO2 down to 350 ppm.

Although $85.5 trillion seems high, it is comparable to the estimated cost of using carbon emission reduction strategies to reduce atmospheric CO2 down to a lesser goal of 450 ppm, according to the paper. Corresponding to less than 1 percent of the global GDP for the rest of the century, such a cost is considered affordable compared with the alternative consequences of catastrophic climate change.

Still, it will take decades to develop air capture and algal bioenergy systems, scale up prototypes, prepare underground carbon repositories and deploy such systems on a global scale.

"In an ideal case, we could have full deployment on a global scale by 2050," said Greene.

To buy time, another geoengineering strategy that many scientists are exploring involves altering the Earth's radiation budget by injecting sulfate aerosols into the atmosphere and blocking the sun's rays, mimicking what happens after a volcanic eruption, says the paper. Other strategies involve injecting seawater droplets into clouds and deploying shades or mirrors in space, all to block the sun's rays from reaching Earth's surface.

Such solar radiation management strategies "can be done quickly, but should only be considered as a last resort to buy ourselves some time" since they simply "cover up the problem without doing anything about the CO2," said Greene.

The paper's co-authors include Bruce Monger, a senior research associate in earth and atmospheric sciences at Cornell, and Mark Huntley, the chief scientific officer for Cellana LLC in Kona, Hawaii.

(Photo: Charles Greene)

Cornell University


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Dogs and cats, Harry Potter and Voldemort, superconductivity and magnetism -- they tend not to coexist. Superconductivity, the flow of electrons without resistance, is typically suppressed by magnetic fields, which disrupt the intricately choreographed electron motion.

Theoretical physicists at Cornell, working with experimental physicists at Rice University, have carefully engineered a system in which these conflicting properties are believed to put aside their differences.

Publishing online Sept. 30 in the journal Nature, the researchers made and tested an ultra-thin, ultra-cold analogue of a magnetic superconductor -- a sort of one-dimensional wire filled with lithium atoms.

The researchers placed the lithium atoms into bundles of narrow tubes, each of which was only one atom thick. In order to see superconducting properties, they cooled the tubes to about 10 nanokelvin (less than one-hundred-millionth of a degree above absolute zero).

Inside the tubes, the atoms could only bounce off each other in a straight line along the tube. This kinetic restriction stabilizes a "spin density wave" wherein the magnetism is periodically modulated along the tube, on an atomic scale. Superconductivity predominantly builds up in the regions where the magnetism is weakest.

The Cornell theory team, which included assistant professor Erich Mueller and graduate student Stefan Baur, analyzed the experimental data and produced microscopic models of the system. Their principal mathematical technique, the Bethe-Ansatz, was invented by Cornell physicist and Nobel laureate Hans Bethe in the 1930s. Mueller describes the technique as "one of Bethe's greatest legacies."

The work was supported by the Defense Advanced Research Projects Agency's Optical Lattice Emulator program, which seeks to understand and explore the quantum mechanical properties of materials through experiments on atomic clouds.

(Photo: Nature Supplementary Information)

Cornell University




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