Tuesday, January 11, 2011


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Wind turbines in Midwestern farm fields may be doing more than churning out electricity. The giant turbine blades that generate renewable energy might also help corn and soybean crops stay cooler and dryer, help them fend off fungal infestations and improve their ability to extract growth-enhancing carbon dioxide [CO2] from the air and soil.

Speaking at the annual meeting of the American Geophysical Union, a scientific society, in San Francisco today, a researcher at the U.S. Department of Energy’s Ames Laboratory and his co-researcher from the University of Colorado announced the preliminary findings of a months-long research program aimed at studying how wind turbines on farmlands interact with surrounding crops.

“We’ve finished the first phase of our research, and we’re confident that wind turbines do produce measureable effects on the microclimate near crops,” said Ames Laboratory associate and agricultural meteorology expert Gene Takle. According to Takle, who is also a professor of agricultural meteorology and director of the Climate Science Program at Iowa State University, the slow-moving turbine blades that have become a familiar sight along Midwestern highways, channel air downwards, in effect bathing the crops below via the increased airflow they create.

His colleague in the research is Julie Lundquist, assistant professor, Department of Atmospheric and Oceanic Sciences, at the University of Colorado at Boulder, joint appointee at the U.S. Department of Energy’s National Renewable Energy Laboratory, and Fellow of the Renewable and Sustainable Energy Institute. Lundquist’s team uses a specialized laser known as a lidar to measure winds and turbulence from near the Earth’s surface to well above the top tip of a turbine blade.

“Our laser instrument could detect a beautiful plume of increased turbulence that persisted even a quarter-mile downwind of a turbine,” Lundquist said.

Both Takle and Lundquist stressed that their early findings have yet to definitively establish whether or not wind turbines are in fact beneficial to the health and yield potential of soybeans and corn planted nearby. However, their finding that the turbines increase airflow over surrounding crops, suggests this is a realistic possibility.

“The turbulence resulting from wind turbines may speed up natural exchange processes between crop plants and the lower atmosphere,” Takle said.

For instance, crops warm up when the sun shines on them, and some of that heat is given off to the atmosphere. Extra air turbulence likely speeds up this heat exchange, so crops stay slightly cooler during hot days. On cold nights, turbulence stirs the lower atmosphere and keeps nighttime temperatures around the crops warmer.

“In this case, we anticipate turbines’ effects are good in the spring and fall because they would keep the crop a little warmer and help prevent a frost,” said Takle. “Wind turbines could possibly ward off early fall frosts and extend the growing season.”

Other benefits of wind turbines could result from their effects on crop moisture levels. Extra turbulence may help dry the dew that settles on plants beginning in late afternoon, minimizing the amount of time fungi and toxins can grow on plant leaves. Additionally, drier crops at harvest help farmers reduce the cost of artificially drying corn or soybeans.

Another potential benefit to crops is that increased airflows could enable corn and soybean plants to more readily extract atmospheric CO2, a needed “fuel” for crops. The extra turbulence might also pump extra CO2 from the soil. Both results could facilitate the crops ability to perform photosynthesis.

Takle’s wind turbine predictions are based on years of research on so-called agricultural shelter belts, which are the rows of trees in a field, designed to slow high-speed natural winds.

“In a simplistic sense, a wind turbine is nothing more than a tall tree with a well-pruned stem. For a starting point for this research, we adapted a computational fluid model that we use to understand trees,” said Takle. “But we plan to develop a new model specific to wind turbines as we gather more data.”

The team’s initial measurements consisted of visual observations of wind turbulence upwind and downwind of the turbines. The team also used wind-measuring instruments called anemometers to determine the intensity of the turbulence. The bulk of the wind-turbulence measurements and the crop-moisture, temperature and CO2 measurements took place in the spring of 2010.

“We anticipate the impact of wind turbines to be subtle. But in certain years and under certain circumstances the effects could be significant,” said Takle. “When you think about a summer with a string of 105-degree days, extra wind turbulence from wind turbines might be helpful. If turbines can bring the temperature down below 100 degrees that could be a big help for crops.”

(Photo: Ames Lab.)

Ames Laboratory


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Maybe age really is just a number. How young or old someone feels has a huge influence on their health and how other people view them. An article published in Perspectives on Psychological Science, a journal of the Association for Psychological Science, reviews the research and suggests that feeling young can actually make you look young—and have the health of a younger person, too.

Harvard psychological scientist Ellen Langer has been studying how the mind influences the body for over three decades. In one classic study, she had old men live in a retreat that was retrofitted to look like it was 20 years earlier, while they pretended that they were living in that year. “Their minds were in the past. Their vision improved, their strength improved, and so on,” she says. Langer cowrote the new article with Laura M. Hsu of Harvard and Jaewoo Chung of the Massachusetts Institute of Technology.

In one study by Langer and her colleagues, women had their hair cut and dyed at a hair salon, and volunteers looked at before and after pictures of the women. Those women who believed having their hair dyed made them look younger actually did look younger after the salon visit, according to the observers who were shown photos of their faces only. Women who didn’t believe they looked younger with dyed hair didn’t have that benefit.

Past research has found that male-pattern baldness increases the risk of prostate cancer. Langer and her colleagues hypothesize that this might be because balding men feel older; every day in the mirror, they get a stark visual reminder that they’re aging. (Prostate cancer is more common in older men.) Some heart problems are also linked with balding. There’s no clear biological reason for why hair loss and heart problems would go together; the men’s own feelings about their age could be partly to blame.

Older first-time mothers are often healthier as they age than women who have their first children younger—maybe, Langer says, because they’re spending their time with younger women at playgrounds and preschools. And people who marry older partners have a shorter life expectancy, while those who marry younger partners live younger.

So if Langer and her colleagues are right, and feeling young makes you healthier, what can you do about it? One route is to dress like a teenager, dye your hair, and find a younger boyfriend. But Langer has another solution: “Don’t buy the mindset in the first place. Then you won’t be vulnerable to it,” she says. “I think we have far more control over our health and wellbeing than most of us realize.”

Association for Psychological Science


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Clues to future climate may be found in the way an ordinary drinking glass shatters.

Results of a study published in the journal Proceedings of the National Academy of Sciences find that microscopic particles of dust can break apart in patterns that are similar to the fragment patterns of broken glass and other brittle objects.

The research, by National Center for Atmospheric Research (NCAR) scientist Jasper Kok, suggests there are several times more dust particles pumped into the atmosphere than previously believed, since shattered dust appears to produce an unexpectedly high number of large fragments.

The finding has implications for understanding future climate change because dust plays a significant role in controlling the amount of solar energy in the atmosphere.

Depending on their size and other characteristics, some dust particles reflect solar energy and cool the planet, while others trap energy as heat.

"As small as they are, conglomerates of dust particles in soils behave the same way on impact as a glass dropped on a kitchen floor," Kok says. "Knowing this pattern can help us put together a clearer picture of what our future climate will look like."

The study may also improve the accuracy of weather forecasting, especially in dust-prone regions. Dust particles affect clouds and precipitation, as well as temperature.

"This research provides valuable new information on the nature and distribution of dust aerosols in the atmosphere," says Sarah Ruth, program director in the National Science Foundation (NSF)'s Division of Atmospheric and Geospace Sciences, which funds NCAR.

"The results may lead to improvements in our ability to model and predict both weather and climate."

Kok's research focused on a type of airborne particle known as mineral dust.

These particles are usually emitted when grains of sand are blown into soil, shattering dirt and sending fragments into the air.

The fragments can be as large as about 50 microns in diameter, or about the thickness of a fine strand of human hair.

The smallest particles, which are classified as clay and are as tiny as 2 microns in diameter, remain in the atmosphere for about a week, circling much of the globe and exerting a cooling influence by reflecting heat from the Sun back into space.

Larger particles, classified as silt, fall out of the atmosphere after a few days. The larger the particle, the more it will tend to have a heating effect on the atmosphere.

Kok's research indicates that the ratio of silt particles to clay particles is two to eight times greater than represented in climate models.

Since climate scientists carefully calibrate the models to simulate the actual number of clay particles in the atmosphere, the paper suggests that models most likely err when it comes to silt particles.

Most of these larger particles swirl in the atmosphere within about 1,000 miles of desert regions, so adjusting their quantity in computer models should generate better projections of future climate in desert regions, such as the southwestern United States and northern Africa.

Additional research will be needed to determine whether future temperatures in those regions will increase as much or more than currently indicated by computer models.

The study results also suggest that marine ecosystems, which draw down carbon dioxide from the atmosphere, may receive substantially more iron from airborne particles than previously estimated.

The iron enhances biological activity, benefiting ocean food webs, including plants that take up carbon during photosynthesis.

In addition to influencing the amount of solar heat in the atmosphere, dust particles also are deposited on mountain snowpacks, where they absorb heat and accelerate snowmelt.

Physicists have long known that certain brittle objects, such as glass, rocks, or even atomic nuclei, fracture in predictable patterns. The resulting fragments follow a certain range of sizes, with a predictable distribution of small, medium, and large pieces.

Scientists refer to this type of pattern as scale invariance or self-similarity.

Physicists have devised mathematical formulas for the process by which cracks propagate in predictable ways as a brittle object breaks.

Kok theorized that it would be possible to use these formulas to estimate the range of dust particle sizes. By applying the formulas for fracture patterns of brittle objects to soil measurements, Kok determined the size distribution of emitted dust particles.

To his surprise, the formulas described measurements of dust particle sizes almost exactly.

"The idea that all these objects shatter in the same way is a beautiful thing, actually," Kok says. "It's nature's way of creating order in chaos."

(Photo: NCAR)

The National Science Foundation


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A design feature well known in skirts and trousers has now been identified in curved, two-dimensional crystals. As University of Chicago physicist William Irvine and his colleagues report in this week’s Nature, crystalline arrays of microscopic particles grown on a negatively curved surface can develop linear defects analogous to fabric pleats. The results will facilitate a more general exploration of defects in curved spaces, including potential applications in engineered materials.

The problem of tiling a curved surface with hexagons is familiar from soccer balls and geodesic domes, in which pentagons are added to accommodate the spherical (positive) curvature. Interacting particles that form hexagonal patterns on a plane — known as ‘colloidal crystals’ — adopt these and other types of topological defects when grown on a sphere.

Irvine, an assistant professor in physics, and colleagues have developed an experimental system that allows them to investigate crystal order on surfaces with spatially varying curvature, both positive and negative. On negatively curved surfaces, they observed two types of defect that hadn’t been seen before: isolated heptagons (analogous to the pentagons on a sphere) and pleats.

The pleats allow a finer control of crystal order with curvature than is possible with isolated point defects, and may find application in curved structures such as waisted nanotubes (long, thin microscopic cylinders of material that display novel properties), or in materials created by techniques that permit control at the atomic and molecular levels, such as soft lithography or directed self-assembly.

(Photo: William Irvine)

University of Chicago


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Brain scans may be able to predict which children with dyslexia are likely to improve their reading skills over time, according to a new study led by MIT and Stanford researchers.

Some 5 to 17 percent of U.S. children suffer from dyslexia, a learning disorder that makes it difficult to read. Many dyslexic children are able to make substantial improvements in reading ability, but how they do so is not well-understood, and standardized reading tests cannot predict which children are likely to become stronger readers.

If the findings are confirmed in larger studies, brain scans could be used as a prognostic tool to predict reading improvement in dyslexic children. They could also help scientists and educators develop new teaching methods that take advantage of the brain pathways that dyslexic children appear to use to compensate for their disability, says John Gabrieli, MIT professor of brain and cognitive sciences. Such strategies may be able to help dyslexic children regardless of which brain patterns they show.

Gabrieli, who is also a member of MIT’s McGovern Institute for Brain Research, is a senior author of the paper on the work appearing in the Proceedings of the National Academy of Sciences the week of Dec. 20. The lead author is Fumiko Hoeft of Stanford University School of Medicine.

Experts disagree on a precise definition of dyslexia, with the consensus view being that children with dyslexia have difficulty learning to read, despite normal intelligence. Preschool-age children who will go on to become dyslexic often exhibit weakness in analyzing the sounds of language, such as whether or not words rhyme. As they get older, dyslexic children have difficulty associating sounds with letters, and decoding written words. However, around 25 to 50 percent of dyslexic children eventually develop compensatory strategies that enable them to read well enough to do their schoolwork.

Over the past decade, a type of brain scan known as functional magnetic resonance imaging (fMRI) has allowed researchers to learn a great deal about the brain regions that may be involved in dyslexia. However, so far this has not led to any direct benefits for patients, says Gabrieli. “I got interested in how brain imaging could do something that would get you closer to helping people,” he says.

In the new paper, Gabrieli and colleagues studied 25 dyslexic children, all ranging from 11 to 14 years old, as well as 20 normal readers of the same ages. Each subject’s brain was imaged as he or she decided whether pairs of words rhymed.

Two and a half years later, the researchers examined the reading ability of the same dyslexic children. They found that the children who improved the most were those who had the most activity in the right prefrontal cortex and also the strongest white-matter connections in the right prefrontal cortex during the first test (white matter consists of nerve bundles that carry messages from one area to another). The combination of these two brain measures was an even stronger predictor than either one alone. These brain regions were unrelated to reading gains in typical children.

Dyslexic children may be using the right prefrontal cortex, which is believed to be involved in visual memory, to memorize words, says Gabrieli. In contrast, normal readers use the right prefrontal cortex less and less as they move from memorizing words to figuring out words “on the fly” by translating letters into sounds. That task requires language-processing areas located in the left hemisphere.

The role of the extra-strong organization in the right-hemisphere white matter is still a mystery, says Gabrieli. In the left prefrontal cortex, white matter connects language areas. However, it’s not known what the corresponding white matter in the right prefrontal cortex does, or how activity in those areas would help dyslexic children read, says Gabrieli.

The new findings suggest that dyslexic children who overcome their reading difficulties somehow bypass brain regions normally used for reading, says Gabrieli. “It seems like they’re better off using a completely different strategy,” he says.

That could prompt educators to develop new ways of teaching dyslexic students, focusing on the appropriate brain regions, says Gabrieli. “Current interventions try to get kids to use typical approaches to reading. But you may be better off promoting a different approach to reading altogether in older children,” he says. One possibility would be to emphasize a more visual approach, similar to “speed reading,” as opposed to teaching dyslexic children to translate letters into sounds.

“Those children who did not improve might have the most to gain if instructions were developed that took into account alternative reading strategies, instead of trying to get struggling readers to read like good readers,” says Gabrieli. “Those who improved might have discovered on their own what works for them, and those who failed to improve might most be in need of explicit instruction and support to try a different strategy.”

Manuel Casanova, professor of psychiatry at the University of Louisville, says the study’s most important contribution is revealing that the behavioral and intelligence measures commonly used to evaluate a dyslexic child’s chances of improvement — such as IQ tests and standardized reading tests — are not reliable. “The conventional wisdom until now has been behavioral measurements,” says Casanova. “I am blown away by the fact that IQ is not predictive of the ability to improve.”

However, he points out that evaluating children at a younger age, when they are more likely to be able to improve, would be more useful to doctors and educators.

Gabrieli plans to repeat his fMRI study in younger children with dyslexia, and he is also studying the prognostic ability of fMRI in other brain disorders. He is optimistic that fMRI has potential to help doctors select the best treatment for individual patients, not just for dyslexics but those who suffer from many other brain disorders such as depression, anxiety and schizophrenia.

(Photo: MIT)



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Environmental influences experienced by a father can be passed down to the next generation, "reprogramming" how genes function in offspring, scientists at The University of Texas at Austin and the University of Massachusetts Medical School (UMMS) have discovered.

A new study published in Cell shows environmental cues — in this case, diet — influence genes in mammals from one generation to the next, evidence that until now has been sparse.

These insights, coupled with previous human epidemiological studies, suggest paternal environmental effects may play a more important role in complex diseases such as diabetes and heart disease than previously believed.

"Knowing what your parents were doing before you were conceived is turning out to be important in determining what disease risk factors you may be carrying," said Oliver Rando, associate professor of biochemistry and molecular pharmacology at UMMS and coauthor of the study with Hans Hofmann, associate professor of integrative biology at The University of Texas at Austin.

The study details how paternal diet can increase production of cholesterol synthesis genes in first-generation offspring.

The human genome is often described as the set of instructions that govern the development and functioning of life. Most contemporary genetic research focuses on understanding and cataloging how mutations and changes to our DNA — the basis of those "instructions" — cause disease and affect health.

A number of recent studies, however, have begun to draw attention to the role epigenetic inheritance — inherited changes in gene expression caused by mechanisms other than changes in the underlying DNA sequence — may play in a host of illnesses.

"A major and under-appreciated aspect of what is transmitted from parent to child is ancestral environment," said Rando. "Our findings suggest that there are many ways that parents can 'tell' their children about what they 'saw.'"

To test their hypothesis that environmental influences experienced by the father can be passed down to the next generation in the form of changed epigenetic information, Rando, Hofmann and colleagues fed different diets to two groups of male mice. The first group received a standard diet, while the second received a low-protein diet. To control for maternal influences, all females were fed the same, standard diet. The researchers observed that offspring of the mice fed the low-protein diet exhibited a marked increase in the genes responsible for lipid and cholesterol synthesis in comparison to offspring of the control group fed the standard diet.

These observations are consistent with epidemiological data from two well-known human studies suggesting that parental diet has an effect on the health of offspring.

One of these studies, called the Överkalix Cohort Study, conducted among residents of an isolated community in the far northeast of Sweden, found that poor diet during the paternal grandfather's adolescence increased the risk of diabetes, obesity and cardiovascular disease in second-generation offspring. However, because these studies are retrospective and involve dynamic populations, they are unable to completely account for all social and economic variables.

"Our study begins to rule out the possibility that social and economic factors, or differences in the DNA sequence, may be contributing to what we're seeing," said Rando. "It strongly implicates epigenetic inheritance as a contributing factor to changes in gene function."

The results also have implications for our understanding of evolutionary processes, Hofmann said.

"It has increasingly become clear in recent years that mothers can endow their offspring with information about the environment, for instance via early experience and maternal factors, and thus make them possibly better adapted to environmental change," said Hofmann. "Our results show that offspring can inherit such acquired characters even from a parent they have never directly interacted with, which provides a novel mechanism through which natural selection could act in the course of evolution."

Such a process was first proposed by the early evolutionist Jean-Baptiste Lamarck, but then dismissed by 20th century biologists when genetic evidence seemed to provide a sufficient explanation.

Taken together, these studies suggest a better understanding of the environment experienced by our parents, such as diet, may be a useful clinical tool for assessing disease risk for illnesses, such as diabetes or heart disease.

"We often look at a patient's behavior and their genes to assess risk," said Rando. "If the patient smokes, they are going to be at an increased risk for cancer. If the family has a long history of heart disease, they might carry a gene that makes them more susceptible to heart disease. But we're more than just our genes and our behavior. Knowing what environmental factors your parents experienced is also important."

The next step for the scientists is to explore how and why this genetic reprogramming is being transmitted from generation to generation.

"We don't know why these genes are being reprogrammed or how, precisely, that information is being passed down to the next generation," said Rando. "It's consistent with the idea that when parents go hungry, it's best for offspring to hoard calories. However, it's not clear if these changes are advantageous in the context of a low-protein diet."

University of Texas




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