April 26, 2006, 6:54 PM CT

Virtual 'forest' used to measure navigation skills

A new study recently published in Journal of Vision, an online, free access publication of the Association for Research in Vision and Ophthalmology (ARVO), shows that an individual's navigation skills can be measured by using an immersive virtual "forest" in which peripheral visual field losses are simulated.

The study, conducted by scientists from the Lions Vision Center, Wilmer Eye Institute, Johns Hopkins University in Baltimore, Md., involved varying the study participants' visual field of view and recording several performance measures such as walking time and path efficiency. Participants were then identified as either "good navigators" or "poor navigators." The results suggest that poor navigators rely on visual information to solve the task while good navigators are able to use visual information in conjunction with an internal representation of the environment. As a result of these differences, the performance of the poor navigators improved more than the performance of the good navigators as the amount of available visual information increased.

"By simulating peripheral visual field losses during navigation, we were able to create a paradigm that systematically controls the amount of external visual information available to participants. This allows us to directly test the extent to which participants rely on this type of information, and identify those individuals who are able to rely on alternative sources of information to learn about their environments," said lead researcher Francesca Fortenbaugh, BS. "Knowing what types of information individuals use when navigating and how performance deteriorates when that information is removed is important not only for understanding human navigation in general, but also for the development of rehabilitation protocols for individuals with visual impairments".........

Posted by: Jessica      Permalink         Source

April 23, 2006, 11:36 PM CT

Automated System Predicts Grape Yields

Estimating grape yields is a time-consuming, laborious affair. But that could change, thanks to a high-tech helping hand from Agricultural Research Service (ARS) researchers in Prosser, Wash.

There, ARS horticulturist Julie Tarara and his colleagues have developed an automated system for estimating grape yields based on tension changes in the trellis wire used to support the vine crop. Her team is still field-testing the system. The hope is that the yield estimates it produces will allow growers and processors to better synchronize their pruning, watering, picking and juice-making operations.

As per Tarara, who works in ARS' Horticultural Crops Research Unit at Prosser, the current method of estimating grape yields involves counting berry clusters on sample vines, followed by counting and weighing of individual berries. The averages are then compared to records from past seasons to predict the current crop's likely yield.

Imprecise estimates can sometimes be costly. For example, an inflated yield estimate might lead a winery to order more barrels than it actually needs. The "pain" is in the price tag: New American oak barrels start at around $300, while new French oak barrels cost from $600 to around $800 each.

The scientists' automated system employs a device called a load cell to detect increases in the tension of trellis wire as grape clusters form and berries enlarge. A data logger records signals generated by the tension changes every 10 seconds, formulating an average every 15 minutes. Now, Tarara's team must download, inspect and "clean" data logger information for processing and eventual use in predicting grape yield. Once validated with field tests, though, the process will be completely automated, providing users with real-time information on their crop's progress, as per Tarara.........

Posted by: Jessica      Permalink         Source

April 20, 2006, 11:06 PM CT

The Future Of Tropical Forest Species

Deforestation and habitat loss are widely expected to precipitate an extinction crisis among tropical forest species. Humans cause deforestation, and humans living in rural settings have the greatest impact on extant forest area in the tropics.

Current human demographic trends, including slowing population growth and intense urbanization, give reason to hope that deforestation will slow, natural forest regeneration through secondary succession will accelerate, and the widely anticipated mass extinction of tropical forest species will be avoided.

In the article "The future of tropical forest species" published online in Biotropica by STRI's S. Joseph and Helene Muller-Landau, the researchers show that the proportion of potential forest cover remaining is closely correlated with human population density among countries, in both the tropics and the temperate zone. Wright and Muller-Landau use United Nations population projections and continent-specific relationships between both total and rural population density and forest remaining today to project future tropical forest cover.

"Our projections suggest that deforestation rates will decrease as population growth slows, and that a much larger area will continue to be forested than previous studies suggest".........

Posted by: Jessica      Permalink         Source

April 17, 2006, 11:49 AM CT

Making Better Peanuts

Agricultural Research Service (ARS) scientists in Stillwater, Okla., are an integral part of a new initiative to improve the peanut.

The researchers, with ARS' Wheat, Peanut and Other Field Crops Research Unit, are joining the Oklahoma Peanut Commission and state research and extension professionals in a new, wide-ranging program to produce disease-resistant plants with tasty, fresh and healthful peanuts for consumers.

Plant pathologist Hassan Melouk and biologist Kelly Chenault lead the ARS team. According to their research leader, Dave Porter, the new program fortifies and expands the ARS unit's efforts to enhance, through breeding, peanut plants' genetic diversity, and to develop superior peanut products.

The new initiative, which was started in response to recent declines in peanut production in southern Plains states, can help growers meet an increasing demand for peanuts through economical, sustainable and environmentally compatible management strategies, as well as spur improved crop production that allows for less pesticide use and greater product value, quality and safety, according to Porter.

This united effort will benefit from the continuation of Melouk's work on combining traits of peanut plants that resist diseases with those that boost oleic acid content. Studies have shown that oleic acid-which staves off deterioration and gives peanut products longer shelf life-may promote a lower risk of coronary heart disease.........

Posted by: Jessica      Permalink         Source

April 13, 2006, 0:11 AM CT

Higher Carbon Dioxide, Lack Of Nitrogen Limit Plant Growth

Earth's plant life will not be able to "store" excess carbon from rising atmospheric carbon dioxide levels as well as scientists once thought because plants likely cannot get enough nutrients, such as nitrogen, when there are higher levels of carbon dioxide, according to scientists publishing in this week's issue of the journal Nature.

That, in turn, is likely to dampen the ability of plants to offset increases in atmospheric carbon dioxide.

"We found that atmospheric carbon dioxide levels may rise even faster than anticipated, because ecosystems likely will not store as much carbon as had been predicted," said Peter Reich of the University of Minnesota, lead author of the study, which was conducted at the National Science Foundation (NSF)'s Cedar Creek Long-Term Ecological Research (LTER) site in Minn.

"As a result, soils will be unable to sustain plant growth over time [as atmospheric carbon dioxide continues to increase]," said plant ecologist David Ellsworth of the University of Michigan.

Estimating the role of terrestrial ecosystems as current and future sinks--or storage places--for excess carbon dioxide hinges on an ability to understand the complex interaction between atmospheric carbon dioxide and nitrogen in soils, the scientists believe.........

Posted by: Jessica      Permalink         Source

April 11, 2006, 10:49 PM CT

Arsenic-eating Plants

Environmental arsenic pollution is a serious and growing environmental problem, particularly on the Indian subcontinent. Scientists at the University of Georgia had, several years ago, used genetic techniques to create "arsenic-eating" plants that could be planted on polluted sites.

There was a problem, however. The arsenic sequestered from soil remained largely in the roots of the plant, making it difficult to harvest for safe disposal. Now, the research team, led by geneticist Richard Meagher, has discovered a way to move the arsenic from roots to shoots. The payoff could be a new and effective tool in cleaning up thousands of sites where arsenic presents serious dangers to human health.

The research was just reported in the Proceedings of the National Academy of Sciences (PNAS). Other authors of the paper include Om Parkash Dhankher and Elizabeth McKinney from the department of genetics at UGA and Barry Rosen of Wayne State University.

"High levels of arsenic in soil and drinking water have been reported around the world," said Meagher, "but the situation is worst in India and Bangladesh, where around 400 million people are at risk of arsenic poisoning. Unfortunately, the high cost of using excavation and reburial at these sites makes these technologies unacceptable for cleaning up the vast areas of the planet that need arsenic remediation. As a result, the overwhelming majority of arsenic-contaminated sites are not being cleaned up."........

Posted by: Jessica      Permalink         Source

April 10, 2006, 8:17 PM CT

Nature Can Help Reduce Greenhouse Gas

Plants apparently do much less than previously thought to counteract global warming, as per a paper would be published in next week's online edition of Proceedings of the National Academy of Sciences.

The authors, including Bruce Hungate of Northern Arizona University and lead author Kees-Jan van Groenigen of UC Davis, discovered that plants are limited in their impact on global warming because of their dependence on nitrogen and other trace elements. These elements are essential to photosynthesis, whereby plants remove carbon dioxide, a greenhouse gas, from the air and transfer carbon back into the soil.

"What our paper shows is that in order for soils to lock away more carbon as carbon dioxide rises, there has to be quite a bit of extra nitrogen available--far more than what is normally available in most ecosystems," said Hungate of NAU's Merriam-Powell Center for Environmental Research.

The paper notes that various plants can pump nitrogen from the air into soils, and some scientists expected rising carbon dioxide to speed up this natural nitrogen pump, providing the nitrogen needed to store soil carbon. However, the research team found that this process, called nitrogen fixation, cannot keep up with increasing carbon dioxide unless other essential nutrients, such as potassium, phosphorus and molybdenum, are added as fertilizers.........

Posted by: Brooke      Permalink         Source

April 10, 2006, 7:43 PM CT

Complexity Of Tropical Forest Structure

In the last decade, the new theory of metabolic ecology has derived general predictions for a wide range of ecological patterns from fundamental physical and biochemical principles. Predictions for tree growth, mortality and size distributions are particularly significant in light of their potential to help explain globally important carbon stores and fluxes of tropical forests. In a forthcoming pair of papers in Ecology Letters, Muller-Landau and collaborators associated with the Center for Tropical Science test these predictions using large datasets from tropical forests around the world.

Observed patterns of tree growth, mortality and abundance deviate substantially from the predictions of metabolic ecology theory, especially for large trees. Variation within and among forests is more consistent with alternative models presented by Muller-Landau and colleagues, models that can incorporate some of the complex variation in tree shapes, growing conditions, and mortality threats within and among diverse tropical forests.........

Posted by: Jessica      Permalink         Source

March 25, 2006, 10:46 AM CT

Tastier Tomatoes In Making?

Tomatoes are a major nutrient for humans. In 2004, 120,000 tonnes of tomatoes were harvested worldwide - and every year this number increases. Numerous medical studies have shown the health value of tomatoes. Lycopen, the pigment that makes tomatoes red, can for example prevent heart disease. Tomatoes furthermore contain a lot of vitamins C and E, indispensable for human nourishment. But after centuries of cultivation for shape, colour, and other useful qualities, our cultured tomatoes today are of small genetic diversity, in comparison with wild types. This has affected the taste and health value of the fruits.

To cultivate tomato strains with particular characteristics, researchers have to increase the genetic diversity of cultured tomatoes. This can be done either by cross-breeding them with wild tomatoes, or changing their genetic make-up technologically. Scientists from the Max Planck Institute for Molecular Plant Physiology in Golm, and their Israeli colleagues at Hebrew University in Jerusalem, chose the second option. They investigated strains of tomatoes created from the crossing of cultured and wild types. Their goal was to identify the biochemical composition of fruits and determine which factors control their development. The German-Israeli research team used a method of analysis developed at the Max Planck Institute for Molecular Plant Physiology. The technique - a combination of mass spectrometry and gas chromatography - analyzes the composition of biological samples. It can be used to quickly and simultaneously look into a fruit's amino acids, organic acids, sugar and vitamins.........

Posted by: Jessica      Permalink         Source

March 9, 2006, 11:41 PM CT

Yellowstone's Deep Secret

Satellite images acquired by ESA's ERS-2 revealed the recently discovered changes in Yellowstone's caldera are the result of molten rock movement 15 kilometres below the Earth's surface, as per a recent study published in Nature.

Using Synthetic Aperture Radar Interferometry, InSAR for short, Charles Wicks, Wayne Thatcher and other U.S. Geological Survey (USGS) researchers mapped the changes in the northern rim of the caldera, or crater, and discovered it had risen about 13 centimetres from 1997 to 2003.

InSAR, a sophisticated version of 'spot the difference', involves mathematically combining different radar images, acquired from as near as possible to the same point in space at different times, to create digital elevation models and reveal otherwise undetectable changes occurring between image acquisitions.

"We know now how mobile and restless the Yellowstone caldera actually is. Ground-based measurements can be more efficiently deployed because of our work," Thatcher said. "The research could not have been done without satellite radar data." .

About 640,000 years ago, a massive volcano erupted in Yellowstone, creating the caldera, which measures some 45 kilometres wide and 75 kilometres long, in the centre of Yellowstone National Park.........

Posted by: Tyler      Permalink         Source

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