science of daily

Budding Research Links Climate Change and Earlier Flowering Plants

2011-01-02T22:10:00.000-08:00

University of Cincinnati biologist Denis Conover has done extensive plant studies in Hamilton County Parks and the Oxbow area. Here he studies a specimen at Burnet Woods.

According to research published November 16 by a University of Cincinnati faculty member, native plants in southwestern Ohio are flowering significantly earlier, a finding he attributes, at least in part, to global warming.

UC biologist Denis Conover, field service associate professor, has spent countless hours walking the Shaker Trace Wetlands at Miami Whitewater Forest over the last 18 years to survey hundreds of different plant species.

Conover's results, published in the December issue of Ecological Restoration, reveal that for species that were observed flowering during two distinct multi-year surveys, a significant number of wild plants (39 percent) bloomed earlier from 2005 to 2008 than when he recorded the same species' blooming times from 1992 to 1996. Forty-five percent of the plants bloomed at the same time, and 16 percent bloomed earlier.

"I was doing a plant survey to see how the wetlands had changed over the years, and I noticed a lot of the plants were blooming earlier than they had in the previous survey," said Conover.

The biologist pointed out that the mean annual temperature during the survey periods increased nearly 2 degrees from 53.38 degrees (11.88 C) to 55.27 degrees (12.93 C) in roughly a decade's time.

"This is a big change for such a short time period," said Conover. "There is a lot of data coming from all over the world indicating that biological communities are being impacted by warmer temperatures."

To determine the impact of these changes, Conover said scientists would need to look closely at the complete ecological picture, including the impact on insects and birds that interact with the plants.

"If the right insects aren't out at the right time, it could affect some of the cross-pollination that goes on," he said. Or it could affect certain birds that depend on the seeds from those plants. Everything is interrelated. It is hard to say what impact it will have. We could also see things like more invasive species moving in because of the warmer conditions."

Conover worked closely with UC's Steve Pelikan, a math professor, who crunched all the data from the surveys. Pelikan said he found both the number of earlier-flowering plants and the temperature change from one survey to the next to be statistically significant.

Conover's wild-plant research follows a similar pattern of findings from a recent 30-year garden-plant study in southwestern Ohio (McEwan, et al.). Pelikan points out that Conover's published research is significant because it is one of the first to highlight the earlier flowering phenomena among plants in a natural habitat as opposed to a more-controlled garden setting.

"His is one of the first papers to reach this conclusion when working with native plants in a native setting," said Pelikan.

Further substantiating the work, Conover has found that his observations also aren't unique to the Shaker Trace Wetlands. He's finding similar results as he compares data he collected from a plant survey in 2000 at Oxbow -- a wetland at the confluence of the Great Miami and Ohio Rivers that spans southeastern Indiana and southwestern Ohio -- to data from today.

He's also noticed the presence of new invasive species in the Oxbow area such as Callery pear, Japanese stiltgrass and Japanese chaff flower.

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Type 1 Diabetes Computer Model's Predictive Success Validated Through Lab Testing

2011-01-02T22:07:00.000-08:00

A La Jolla Institute team, led by leading type 1 diabetes researcher Matthias von Herrath, M.D., has demonstrated the effectiveness of a recently developed computer model in predicting key information about nasal insulin treatment regimens in type 1 (juvenile) diabetes.

The findings, which also showed the platform's ability to predict critical type 1 diabetes molecular "biomarkers," were published in the December issue of the scientific journal Diabetes, and further validate the importance of the new model as a valuable research tool in type 1 diabetes. The software is designed to enable researchers to rapidly streamline laboratory research through the evaluation of alternative scenarios for therapeutic strategies that show the most promise for working in humans.

"Since laboratory studies can cost hundreds of thousands of dollars, and early stage human clinical trials can cost $10 million dollars or more, predicting the right conditions to try is important," said Dr. von Herrath, director of the Type 1 Diabetes Research Center at the La Jolla Institute for Allergy & Immunology, where the studies were conducted.

Development of the software, the Type 1 Diabetes PhysioLab® Platform, was funded through the peer-reviewed grant program of the American Diabetes Association.

"We've found that using this in silico (computer analysis) prediction platform can quicken the pace and effectiveness of type 1 diabetes research," he continued. "By allowing us to pre-test our theories in computer models, we can ensure that the more time-intensive and costly process of laboratory testing is focused on the most promising therapeutic strategies, with the greatest chance of success."

The platform, developed by Entelos Inc., a life sciences company specializing in predictive technologies, has previously been shown to successfully predict various data from published type 1 diabetes experiments. Dr. von Herrath's team used a different approach to test the model, asking it to predict the outcome of a hypothetical experiment on nasal insulin dosing frequency in animal models that had not yet been performed. The prediction was then tested in the laboratory, where its results were confirmed.

In addition, he said, the model was able to accurately identify the particular time frame at which key type 1 diabetes "biomarkers" kicked in. Biomarkers are specific cell types or proteins that tell researchers at what point a therapeutic option is working or when it is time to start treatment. In the case of the La Jolla Institute study, the model successfully predicted the onset of biomarkers indicating beta cell protection in the NOD mouse.

"The model accurately predicted that implementing a low frequency nasal insulin dosing regimen in animal models was more beneficial in controlling type 1 diabetes than a high frequency regimen," said Dr. von Herrath, noting that the software's prediction of the biomarkers was key in this process. "These results confirmed our hypotheses on the benefits of low-frequency nasal insulin dosing. But even more importantly, the advantage of applying computer modeling in optimizing the therapeutic efficacy of nasal insulin immunotherapy was confirmed."

The results were reported in the paper "Virtual Optimization of Nasal Insulin Therapy Predicts Immunization Frequency To Be Crucial for Diabetes Protection." Dr. von Herrath was senior author on the paper and La Jolla Institute scientist Georgia Fousteri, Ph.D., and Jason Chan, Ph.D., from Entelos' R&D group, were first co-authors.

The Type 1 Diabetes PhysioLab® Platform is a large-scale mathematical model of disease pathogenesis based on non-obese diabetic (NOD) mice. The platform was developed with input from an independent scientific team of leading type 1 diabetes experts. The research support group of the American Diabetes Association funded the work of the software's development to provide a new scientific tool for enhancing the speed and effectiveness of type 1 diabetes research.

More than 400,000 children worldwide suffer from type 1 diabetes, a chronic disease that can lead to severe complications, such as blindness, cardiovascular disease, renal disease, coma or even death.

The platform, developed over two years, simulates autoimmune processes and subsequent destruction of pancreatic beta cells from birth through frank diabetes onset (hyperglycemia). The destruction of insulin-producing beta cells in the pancreas is the underlying cause of type 1 diabetes.

Specifically, Dr. von Herrath's team employed the model to investigate the possible mechanisms underlying the effectiveness of nasal insulin therapy, using the B: 9-23 peptide. "The experimental aim was to evaluate the impact of dose, frequency of administration and age at treatment on key molecular mechanisms and optimal therapeutic outcome," he said.

Using parameters input by the scientific team, the model accurately predicted that less frequent doses of nasal insulin, started at an early disease stage, would protect more effectively against beta cell destruction than higher frequency doses in NOD mice.

Dr. von Herrath added that the positive results add credence to the idea of creating computer models for analyzing therapeutic interventions in human disease. "These results support the development and application of humanized platforms for the design of clinical trials," he said.

Source Story by Sciencedaily

Neandertals’ Extinction Not Caused by Deficient Diets, Tooth Analysis Shows

2011-01-02T22:04:00.000-08:00

Neandertal teeth from Shanidar cave.

Researchers from George Washington University and the Smithsonian Institution have discovered evidence to debunk the theory that Neandertals' disappearance was caused in part by a deficient diet -- one that lacked variety and was overly reliant on meat. After discovering starch granules from plant food trapped in the dental calculus on 40-thousand-year-old Neandertal teeth, the scientists believe that Neandertals ate a wide variety of plants and included cooked grains as part of a more sophisticated, diverse diet similar to early modern humans.

"Neandertals are often portrayed as very backwards or primitive," said Amanda Henry, lead researcher and a post-doctoral researcher at GW. "Now we are beginning to understand that they had some quite advanced technologies and behaviors."

Dr. Henry made this discovery together with Alison Brooks, professor of anthropology and international affairs at GW, and Dolores Piperno, a GW research professor and senior scientist and curator of archaeobotany and South American archaeology at the Smithsonian National Museum of Natural History, Washington D.C., and Smithsonian Tropical Research Institute, Panama.

The discovery of starch granules in the calculus on Neandertal teeth provides direct evidence that they made sophisticated, thoughtful food choices and ate more nutrient-rich plants, for example date palms, legumes and grains such as barley. Until now, anthropologists have hypothesized that Neandertals were outlived by early modern humans due in part to the former's primitive, deficient diet, with some scientists arguing Neandertals' diets were specialized for meat-eating. As such, during major climate swings Neandertals could be outcompeted by early humans who incorporated diverse plant foods available in the local environment into their diets.

Drs. Henry, Brooks and Piperno's discovery suggests otherwise. The researchers discovered starch granules in dental calculus, which forms when plaque buildup hardens, on the fossilized teeth of Neandertal skeletons excavated from Shanidar Cave in Iraq and Spy Cave in Belgium. Starch granules are abundant in most human plant foods, but were not known to survive on fossil teeth this old until this study. The researchers' findings indicate that Neandertals' diets were more similar to those of early humans than originally thought. The researchers also determined from alterations they observed in the starch granules that Neandertals prepared and cooked starch-rich foods to make them taste better and easier to digest.

"Neandertals and early humans did not visit the dentist," said Dr. Brooks. "Therefore, the calculus or tartar remained on their teeth, preserving tiny clues to the previously unknown plant portion of their diets."

Dr. Henry is currently a post-doctoral researcher in the Columbian College of Arts and Sciences Hominid Paleobiology program at the George Washington University, where she also received her Ph.D. in Jan. 2010. Her research focuses on the uses of plant foods by human ancestors. In Jan. 2011, Dr. Henry will begin leading an independent research group focusing on the evolution of human diet at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Dr Brooks' research focuses on the evolution of modern human behavior. Dr. Piperno is a pioneer in the detection and study of plant microfossils and the evolution of human diets.

"This significant finding provides new insight on the plight of the Neandertals," said Peg Barratt, dean of GW's Columbian College of Arts and Sciences. "It's also an excellent example of our dynamic partnership with the Smithsonian to further advance learning and discovery."

The research was supported by a National Science Foundation IGERT award, a Wenner Gren Foundation doctoral dissertation award, a Smithsonian Institution pre-doctoral fellowship, a National Science Foundation HOMINID award to the Smithsonian Institution and a selective excellence award from the George Washington University.

Source story by Sciencedaily

Calculating Tidal Energy Turbines' Effects on Sediments and Fish

2011-01-02T22:02:00.000-08:00

Model results of the water speed around a turbine blade. Currents are slower (blue) behind the blade, and faster (red) at the blade's tip.

The emerging tidal-energy industry is spawning another in its shadow: tidal-energy monitoring. Little is known about tidal turbines' environmental effects and environmentalists, regulators and turbine manufacturers all need more data to allow the industry to grow.

Engineers at the University of Washington have developed a set of numerical models, solved by computers, to study how changing water pressure and speed around turbines affects sediment accumulation and fish health. They will present their findings this week at the American Geophysical Union's meeting in San Francisco.

The current numerical models look at windmill-style turbines that operate in fast-moving tidal channels. The turbine blade design creates a low-pressure region on one side of the blade, similar to an airplane wing. A small fish swimming past the turbine will be pulled along with the current and so will avoid hitting the blade, but might experience a sudden change in pressure.

Teymour Javaherchi, a UW mechanical engineering doctoral student, says his model shows these pressure changes would occur in less than 0.2 seconds, which could be too fast for the fish to adapt.

If the pressure change happens too quickly the fish would be unable to control their buoyancy and, like an inexperienced scuba diver, would either sink to the bottom or float to the surface. During this time the fish would become disoriented and risk being caught by predators. In a worst-case scenario, severe pressure changes could cause internal hemorrhaging and death.

It's too early to say whether tidal turbines could harm fish in this way, Javaherchi said. The existing model uses the blade geometry from a wind turbine.

"The competition between the companies is very tight and they are hesitant to share the designs," Javaherchi said.

The researchers are open to working with any company that wants to use the technique to assess a particular turbine design.

Another set of numerical modeling looked at whether changes in speed of water flow could affect the settling of suspended particles in a tidal channel. Slower water speeds behind the turbine would allow more particles to sink to the bottom rather than being carried along by the current.

Javaherchi's modeling work suggests this is the case, especially for mid-sized particles of about a half-centimeter in diameter, about two-tenths of an inch. This would mean that a rocky bottom near a tidal turbine might become sandier, which could affect marine life.

The UW research differs from most renewable energy calculations that seek to maximize the amount of energy generated.

"We are [also] interested in the amount of energy that can be extracted by the turbines, but we are aware that the limiting factor for the development of these technologies is the perception by the public that they might have a big environmental impact," said Alberto Aliseda, a UW assistant professor of mechanical engineering and Javaherchi's thesis adviser.

As to whether any negative effects discovered for tidal turbines would be preventable, Aliseda said, "Absolutely."

"We need to establish what is the lowest pressure that the animals can sustain and the period of time that they need to adjust," Aliseda said. "The blade can be shaped to minimize this effect."

Aliseda says engineers in the wind-turbine industry are already adapting the UW work to look at interactions between wind turbines and bats, since high-frequency pressure changes are now thought to be responsible for the mysterious deaths of bats caused by wind turbines.

"Maybe the best turbine is not the one that extracts the most energy, but the one that extracts a reasonable amount of energy and at the same time minimizes the environmental effects," he said.

The research was funded by a Department of Energy grant to the Northwest National Marine Renewable Energy Center. Joseph Seydel, a Boeing engineer and UW graduate in mechanical engineering, also contributed to the research.

Source Story by Sciencedaily

New Technology to Speed Cleanup of Nuclear Contaminated Sites

2011-01-02T21:59:00.000-08:00


This new spectrometer developed by engineers at Oregon State University will help speed the cleanup of nuclear waste sites and reduce costs.

Members of the engineering faculty at Oregon State University have invented a new type of radiation detection and measurement device that will be particularly useful for cleanup of sites with radioactive contamination, making the process faster, more accurate and less expensive.

A patent has been granted on this new type of radiation spectrometer, and the first production of devices will begin soon. The advance has also led to creation of a Corvallis-based spinoff company, Avicenna Instruments, based on the OSU research. The market for these instruments may ultimately be global, and thousands of them could be built, researchers say.

Hundreds of millions of dollars are spent on cleanup of some major sites contaminated by radioactivity, primarily from the historic production of nuclear weapons during and after World War II. These include the Hanford site in Washington, Savannah River site in South Carolina, and Oak Ridge National Laboratory in Tennessee.

"Unlike other detectors, this spectrometer is more efficient, and able to measure and quantify both gamma and beta radiation at the same time," said David Hamby, an OSU professor of health physics. "Before this two different types of detectors and other chemical tests were needed in a time-consuming process."

"This system will be able to provide accurate results in 15 minutes that previously might have taken half a day," Hamby said. "That saves steps, time and money."

The spectrometer, developed over 10 years by Hamby and Abi Farsoni, an assistant professor in the College of Engineering, can quickly tell the type and amount of radionuclides that are present in something like a soil sample -- contaminants such as cesium 137 or strontium 90 -- that were produced from reactor operations. And it can distinguish between gamma rays and beta particles, which is necessary to determine the level of contamination.

"Cleaning up radioactive contamination is something we can do, but the process is costly, and often the question when working in the field is how clean is clean enough," Hamby said. "At some point the remaining level of radioactivity is not a concern. So we need the ability to do frequent and accurate testing to protect the environment while also controlling costs."

This system should allow that, Hamby said, and may eventually be used in monitoring processes in the nuclear energy industry, or possibly medical applications in the use of radioactive tracers.

The OSU College of Engineering has contracted with Ludlum Instruments, a Sweetwater, Texas, manufacturer, to produce the first instruments, and the OSU Office of Technology Transfer is seeking a licensee for commercial development. The electronic systems for the spectrometers will be produced in Oregon by Avicenna Instruments, the researchers said.

Source Story by Sciencedaily

Light Dawns on Dark Gamma-Ray Bursts

2011-01-02T21:55:00.000-08:00


This artist's impression shows a dark gamma-ray burst in a star forming region. Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study of these dark gamma-ray bursts to date, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions, while puzzling, don't require exotic explanations. Their faintness is now fully explained by a combination of causes with the most important being the presence of dust between the Earth and the explosion.

Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the 2.2-meter MPG/ESO telescope at La Silla in Chile, has found that these explosions don't require exotic explanations. Their faintness is now explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion.

Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow.

While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim.

"Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany.

NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift data with new observations made using GROND [2] -- a dedicated gamma-ray burst follow-up observation instrument, which is attached to the 2.2-metre MPG/ESO telescope at La Silla in Chile. In doing so, astronomers have conclusively solved the puzzle of the missing optical afterglow.

What makes GROND exciting for the study of afterglows is its very fast response time -- it can observe a burst within minutes of an alert coming from Swift using a special system called the Rapid Response Mode -- and its ability to observe simultaneously through seven filters covering both the visible and near-infrared parts of the spectrum.

By combining GROND data taken through these seven filters with Swift observations, astronomers were able to accurately determine the amount of light emitted by the afterglow at widely differing wavelengths, all the way from high energy X-rays to the near-infrared. The astronomers used this information to directly measure the amount of obscuring dust that the light passed through en route to Earth. Previously, astronomers had to rely on rough estimates of the dust content [3].

The team used a range of data, including their own measurements from GROND, in addition to observations made by other large telescopes including the ESO Very Large Telescope, to estimate the distances to nearly all of the bursts in their sample. While they found that a significant proportion of bursts are dimmed to about 60-80 percent of the original intensity by obscuring dust, this effect is exaggerated for the very distant bursts, letting the observer see only 30-50 percent of the light [4]. The astronomers conclude that most dark gamma-ray bursts are therefore simply those that have had their small amount of visible light completely stripped away before it reaches us.

"Compared to many instruments on large telescopes, GROND is a low cost and relatively simple instrument, yet it has been able to conclusively resolve the mystery surrounding dark gamma-ray bursts," says Greiner.

Notes:

[1] Gamma-ray bursts lasting longer than two seconds are referred to as long bursts and those with a shorter duration are known as short bursts. Long bursts, which were observed in this study, are associated with the supernova explosions of massive young stars in star-forming galaxies. Short bursts are not well understood, but are thought to originate from the merger of two compact objects such as neutron stars.

[2] The Gamma-Ray burst Optical and Near-infrared Detector (GROND) was designed and built at the Max-Planck Institute for Extraterrestrial Physics in collaboration with the Tautenburg Observatory, and has been fully operational since August 2007.

[3] Other studies relating to dark gamma-ray bursts have been released. Early this year, astronomers used the Subaru Telescope to observe a single gamma-ray burst, from which they hypothesised that dark gamma-ray bursts may indeed be a separate sub-class that form through a different mechanism, such as the merger of binary stars. In another study published last year using the Keck Telescope, astronomers studied the host galaxies of 14 dark GRBs, and based on the derived low redshifts they infer dust as the likely mechanism to create the dark bursts. In the new work reported here, 39 GRBs were studied, including nearly 20 dark bursts, and it is the only study in which no prior assumptions have been made and the amount of dust has been directly measured.

[4] Because the afterglow light of very distant bursts is redshifted due to the expansion of the Universe, the light that left the object was originally bluer than the light we detect when it gets to Earth. Since the reduction of light intensity by dust is greater for blue and ultraviolet light than for red, this means that the overall dimming effect of dust is greater for the more distant gamma-ray bursts. This is why GROND's ability to observe near-infrared radiation makes such a difference.

Source Story by Sciencedaily

Bizarre Bioluminescent Snail

2011-01-02T21:52:00.000-08:00

This image shows examples of the clusterwink snail H. brasiliana emitting biolumuniescent light (right) and without light.

Bizarre Bioluminescent Snail: Secrets of Strange Mollusk and Its Use of Light as a Possible Defense Mechanism Revealed. Two scientists at Scripps Institution of Oceanography at UC San Diego have provided the first details about the mysterious flashes of dazzling bioluminescent light produced by a little-known sea snail.

Dimitri Deheyn and Nerida Wilson of Scripps Oceanography (Wilson is now at the Australian Museum in Sydney) studied a species of "clusterwink snail," a small marine snail typically found in tight clusters or groups at rocky shorelines. These snails were known to produce light, but the researchers discovered that rather than emitting a focused beam of light, the animal uses its shell to scatter and spread bright green bioluminescent light in all directions.

The researchers, who describe their findings in the Dec. 15 online version of Proceedings of the Royal Society B (Biological Sciences), say the luminous displays of Hinea brasiliana could be a deterrent to ward off potential predators by using diffused bioluminescent light to create an illusion of a larger animal.

In experiments conducted inside Scripps' Experimental Aquarium facility, Deheyn documented how H. brasiliana set off its glow, which he likens to a burglar alarm going off, when the snail was confronted by a threatening crab or a nearby swimming shrimp.

Wilson collected the snails used in the study in Australia and collaborated with Deheyn to characterize the bioluminescence.

"It's rare for any bottom-dwelling snails to produce bioluminescence," Wilson said. "So its even more amazing that this snail has a shell that maximizes the signal so efficiently."

Discovering how the snail spreads its light came as a surprise to the researchers since this species of clusterwink features opaque, yellowish shells that would seem to stifle light transmission. But in fact when the snail produces green bioluminescence from its body, the shell acts as a mechanism to specifically disperse only that particular color of light. Deheyn says such adaptations are of keen interest in optics and bioengineering research and development industries.

"The light diffusion capacity we see with this snail is much greater than comparative reference material," said Deheyn, of Scripps' Marine Biology Research Division. "Our next focus is to understand what makes the shell have this capacity and that could be important for building materials with better optical performance."

The study was funded by the Air Force Office of Scientific Research and the Mark Mitchell Foundation.

Walking Slows Progression of Alzheimer's, Study Suggests

2011-01-02T21:38:00.000-08:00

This figure compares the beneficial effects of physical activity on the brains of healthy aging individuals (n = 299) to the positive relationships between exercise and brain structure in cognitively impaired persons with either mild cognitive impairment or Alhzeimer's (n = 127). In both normal aging and cognitive impairment, physical activity preserves volume in brain areas that are important for memory, learning, and attention. These structures include the prefrontal cortex and temporal cortex. The top row of images shows these relationships in a 3-D rendering of the brain while the bottom row shows the prefrontal cortex findings in side view cutaway images of the brain.

Walking may slow cognitive decline in adults with mild cognitive impairment (MCI) and Alzheimer's disease, as well as in healthy adults, according to a study presented November 29 at the annual meeting of the Radiological Society of North America (RSNA)

"We found that walking five miles per week protects the brain structure over 10 years in people with Alzheimer's and MCI, especially in areas of the brain's key memory and learning centers," said Cyrus Raji, Ph.D., from the Department of Radiology at the University of Pittsburgh in Pennsylvania. "We also found that these people had a slower decline in memory loss over five years."

Alzheimer's disease is an irreversible, progressive brain disease that slowly destroys memory and cognitive skills. According to the National Institute on Aging, between 2.4 million and 5.1 million Americans have Alzheimer's disease. Based on current population trends, that number is expected to increase significantly over the next decade.

In cases of MCI, a person has cognitive or memory problems exceeding typical age-related memory loss, but not yet as severe as those found in Alzheimer's disease. About half of the people with MCI progress to Alzheimer's disease.

"Because a cure for Alzheimer's is not yet a reality, we hope to find ways of alleviating disease progression or symptoms in people who are already cognitively impaired," Dr. Raji said.

For the ongoing 20-year study, Dr. Raji and colleagues analyzed the relationship between physical activity and brain structure in 426 people, including 299 healthy adults (mean age 78), and 127 cognitively impaired adults (mean age 81), including 83 adults with MCI and 44 adults with Alzheimer's dementia.

Patients were recruited from the Cardiovascular Health Study. The researchers monitored how far each of the patients walked in a week. After 10 years, all patients underwent 3-D MRI exams to identify changes in brain volume.

"Volume is a vital sign for the brain," Dr. Raji said. "When it decreases, that means brain cells are dying. But when it remains higher, brain health is being maintained."

In addition, patients were given the mini-mental state exam (MMSE) to track cognitive decline over five years. Physical activity levels were correlated with MRI and MMSE results. The analysis adjusted for age, gender, body fat composition, head size, education and other factors.

The findings showed across the board that greater amounts of physical activity were associated with greater brain volume. Cognitively impaired people needed to walk at least 58 city blocks, or approximately five miles, per week to maintain brain volume and slow cognitive decline. The healthy adults needed to walk at least 72 city blocks, or six miles, per week to maintain brain volume and significantly reduce their risk for cognitive decline.

Over five years, MMSE scores decreased by an average of five points in cognitively impaired patients who did not engage in a sufficient level of physical activity, compared with a decrease of only one point in patients who met the physical activity requirement.

"Alzheimer's is a devastating illness, and unfortunately, walking is not a cure," Dr. Raji said. "But walking can improve your brain's resistance to the disease and reduce memory loss over time."

Coauthors are Kirk Erickson, Ph.D., Oscar Lopez, M.D., James Becker, Ph.D., Caterina Rosano, M.D., Anne Newman, M.D., M.P.H., H. Michael Gach, Ph.D., Paul Thompson, Ph.D., April Ho, B.S., and Lewis Kuller, M.D.

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First High-Temp Spin-Field-Effect Transistor Created

2010-12-25T05:17:00.000-08:00

ScienceDaily — An international team of researchers featuring Texas A&M University physicist Jairo Sinova has announced a breakthrough that gives a new spin to semiconductor nanoelectronics and the world of information technology.

The team has developed an electrically controllable device whose functionality is based on an electron's spin. Their results, the culmination of a 20-year scientific quest involving many international researchers and groups, are published in the current issue of Science.

The team, which also includes researchers from the Hitachi Cambridge Laboratory and the Universities of Cambridge and Nottingham in the United Kingdom as well as the Academy of Sciences and Charles University in the Czech Republic, is the first to combine the spin-helix state and anomalous Hall effect to create a realistic spin-field-effect transistor (FET) operable at high temperatures, complete with an AND-gate logic device -- the first such realization in the type of transistors originally proposed by Purdue University's Supriyo Datta and Biswajit Das in 1989.

"One of the major stumbling blocks was that to manipulate spin, one may also destroy it," Sinova explains. "It has only recently been realized that one could manipulate it without destroying it by choosing a particular set-up for the device and manipulating the material. One also has to detect it without destroying it, which we were able to do by exploiting our findings from our study of the spin Hall effect six years ago. It is the combination of these basic physics research projects that has given rise to the first spin-FET."

Sixty years after the transistor's discovery, its operation is still based on the same physical principles of electrical manipulation and detection of electronic charges in a semiconductor, says Hitachi's Dr. Jorg Wunderlich, senior researcher in the team. He says subsequent technology has focused on down-scaling the device size, succeeding to the point where we are approaching the ultimate limit, shifting the focus to establishing new physical principles of operation to overcome these limits -- specifically, using its elementary magnetic movement, or so-called "spin," as the logic variable instead of the charge.

This new approach constitutes the field of "spintronics," which promises potential advances in low-power electronics, hybrid electronic-magnetic systems and completely new functionalities.

Wunderlich says the 20-year-old theory of electrical manipulation and detection of electron's spin in semiconductors -- the cornerstone of which is the "holy grail" known as the spin transistor -- has proven to be unexpectedly difficult to experimentally realize.

"We used recently discovered quantum-relativistic phenomena for both spin manipulation and detection to realize and confirm all the principal phenomena of the spin transistor concept," Wunderlich explains.

To observe the electrical manipulation and detection of spins, the team made a specially designed planar photo-diode (as opposed to the typically used circularly polarized light source) placed next to the transistor channel. By shining light on the diode, they injected photo-excited electrons, rather than the customary spin-polarized electrons, into the transistor channel. Voltages were applied to input-gate electrodes to control the procession of spins via quantum-relativistic effects. These effects -- attributable to quantum relativity -- are also responsible for the onset of transverse electrical voltages in the device, which represent the output signal, dependent on the local orientation of processing electron spins in the transistor channel.

The new device can have a broad range of applications in spintronics research as an efficient tool for manipulating and detecting spins in semiconductors without disturbing the spin-polarized current or using magnetic elements.

Wunderlich notes the observed output electrical signals remain large at high temperatures and are linearly dependent on the degree of circular polarization of the incident light. The device therefore represents a realization of an electrically controllable solid-state polarimeter which directly converts polarization of light into electric voltage signals. He says future applications may exploit the device to detect the content of chiral molecules in solutions, for example, to measure the blood-sugar levels of patients or the sugar content of wine.

This work forms part of wider spintronics activity within Hitachi worldwide, which expects to develop new functionalities for use in fields as diverse as energy transfer, high-speed secure communications and various forms of sensor.

While Wunderlich acknowledges it is yet to be determined whether or not spin-based devices will become a viable alternative to or complement of their standard electron-charge-based counterparts in current information-processing devices, he says his team's discovery has shifted the focus from the theoretical academic speculation to prototype microelectronic device development.

"For spintronics to revolutionize information technology, one needs a further step of creating a spin amplifier," Sinova says. "For now, the device aspect -- the ability to inject, manipulate and create a logic step with spin alone -- has been achieved, and I am happy that Texas A&M University is a part of that accomplishment."

Story Source: sciencedaily

Fast Sepsis Test Can Save Lives

2010-12-25T05:08:00.000-08:00

ScienceDaily (Dec. 24, 2010) — Blood poisoning can be fatal. If you suffer from sepsis, you used to have to wait as much as 48 hours for laboratory findings. A new diagnostic platform as big as a credit card will now supply the analysis after as little as an hour. This system is based on nanoparticles that are automatically guided by magnetic forces.

Although it is the third most frequent cause of death in Germany, blood poisoning is frequently underestimated. In this country, 60,000 persons die every year from some form of sepsis, almost as many as from heart attacks. The Sepsis Nexus of Expertise states that patients arriving at the intensive care ward with blood poisoning only have a 50% chance of surviving. One of the reasons for the high mortality rate is the fact that patients are not correctly treated due to late diagnosis. The doctor and the patient used to have to wait as much as 48 hours for the laboratory analysis.

In future, a new mobile diagnostics platform will be guaranteeing fast and low-cost infection diagnostics even while the patient is being transported to the hospital. It's called MinoLab and it consists of a plastic card the size of a credit card that is inserted in an analysis unit that is smaller than a notebook. This system provides findings in less than one hour to enable the doctor to prescribe the life-saving therapy. This is based on magnetic particles that dock onto the cells to be studied in a blood sample and run through the system fully automatically with magnetic force. At the end of the process, the diagnosis is made with magnetic sensors. MinoLab is presently being developed in a project of the German Federal Ministry of Education and Research by the Fraunhofer Institute for Cell Therapy and Immunology (IZI) in Leipzig, Germany in collaboration with Magna Diagnostics, a company hived off from the Fraunhofer Society. Other project partners are the Fraunhofer Institute for Reliability and Microintegration (IZM) in Berlin as well as the companies Siemens, Dice, microfluidic Chip Shop and the Austrian Institute of Technology.

Dr. Dirk Kuhlmeier, a scientist at the Fraunhofer Institute for Cell Therapy and Immunology, explains how all that works: "After taking a sample of blood, magnetic nanoparticles bind themselves to the target cells in the blood sample through specific catcher molecules. We then use a simple magnet to transfer the particles onto the plastic card along with the pathogens and move them through various miniaturized reaction chambers which is where the polymerase chain reaction takes place. This is a method for copying even the smallest DNA sequences of pathogens millions of times. After it is copied, the nanoparticles transport the pathogen DNA into the detection chamber where a new type of magnetoresistive biochip can identify pathogens and antibiotics resistances." Our researcher goes on: "All reactions starting from sample preparation through isolating the target molecules right down to documentation are carried out without any contact and fully automatically." This means that routine operation is made much simpler for the laboratory technician and it reduces the risk of contamination from bacteria introduced from the environment that set off false alarms. But there is another benefit, as Dr. Kuhlmeier explains: "We not only save time with the combination of magnetic nanoparticles in a new type of micro-fluid. Miniaturization means we also save expensive apparatuses."

The experts have already been successful at using magnetic nanoparticles to isolate and document the sepsis pathogens, although Kuhlmeier says, "it will be another two years or so until we are able to produce a prototype of the diagnostic platform." Platform technology is not only suited for sepsis tests. It will be able to back up doctors in hospitals and private practices answering a wide range of molecular biological issues ranging from genetic predisposition right down to cancer diagnostics.

Story Source: sciencedaily

Most Challenging Christmas Plastic Wrapping Could Be Recycled With New Technology

2010-12-24T07:35:00.000-08:00

ScienceDaily (Dec. 24, 2010) — On average we each consume 120 grammes of plastic wrapping on Christmas gifts most of which is of a type which almost impossible to recycle. Now researchers at the University of Warwick have devised a new technique which could process 100% of Christmas and other household plastic instead of the tiny fraction that currently actually gets processed.

Warwick have devised a new technique which could process 100% of Christmas and other household plastic instead of the tiny fraction that currently actually gets processed -- typically only 12% of such waste is truly recycled often the rest is often put into land fill or simply burnt as fuel.

Some plastic still goes straight to land fill but householders currently spend a great deal of effort separating out the rest of their plastic waste believing it will be recycled yet typically only 12% of "Municipal Plastic Solid Waste" is truly recycled. It is often simply too time consuming to separate out and clean the various types of plastic of their persistent labels or other problems, as that requires significant laborious human intervention. An additional problem is that often objects are made of more than one plastic that would require different treatments.

However University of Warwick engineers have come up with a simple process that can cope with every piece of plastic waste and can even break some polymers such as polystyrene -- back down to its original monomers (styrene in the case of polysterene).

The Warwick researchers have devised a unit which uses pyrolysis (using heat in the absence of oxygen to decompose of materials) in a "fluidised bed" reactor. Tests completed in the last week have shown that the researchers have been able to literally shovel in to such a reactor a wide range of mixed plastics which can then be reduced down to useful products many of which can then be retrieved by simple distillation.

The products the Warwick team have been able to reclaim from the plastic mix include: wax that can be then used a lubricant; original monomers such as styrene that can be used to make new polystyrene; terephthalic acid which can be reused in PET plastic products, methylmetacrylate that can be used to make acrylic sheets, carbon which can be used as Carbon Black in paint pigments and tyres, and even the char left at the end of some of the reactions can be sold to use as activated carbon at a value of at least £400 a tonne.

This research could have a significant impact on the budgets of local authorities and produce considerable environmental benefits. The lab scale tests concluded this week have successfully produced distilled liquids and solids that can be taken away by the bucket load for processing into new products. The University of Warwick engineers are now working with the University's technology transfer arm, Warwick Ventures, who expect that their work will be of great interest to local authorities and waste disposal companies who could use the technology to create large scale reactor units at municipal tips which would produce tanker loads of reusable material.

The lead researcher on the project, University of Warwick Engineering Professor Jan Baeyens, said: "We envisage a typical large scale plant having an average capacity of 10,000 tonnes of plastic waste per year. In a year tankers would take away from each plant over £5 million worth of recycled chemicals and each plant would save £500,000 a year in land fill taxes alone. As the expected energy costs for each large plant would only be in the region of £50,000 a year the system will be commercially very attractive and give a rapid payback on capital and running costs."

Story Source: sciencedaily

NASA's Next Mars Rover to Zap Rocks With Laser

2010-12-24T07:19:00.000-08:00

ScienceDaily (Dec. 23, 2010) — A rock-zapping laser instrument on NASA's next Mars rover has roots in a demonstration that Roger Wiens saw 13 years ago in a colleague's room at Los Alamos National Laboratory in New Mexico.

The Chemistry and Camera (ChemCam) instrument on the rover Curiosity can hit rocks with a laser powerful enough to excite a pinhead-size spot into a glowing, ionized gas. ChemCam then observes the flash through a telescope and analyzes the spectrum of light to identify the chemical elements in the target.

That information about rocks or patches of soil up to about 7 meters (23 feet) away will help the rover team survey the rover's surroundings and choose which targets to drill into, or scoop up, for additional analysis by other instruments on Curiosity. With the 10 science instruments on the rover, the team will assess whether any environments in the landing area have been favorable for microbial life and for preserving evidence about whether life existed. In late 2011, NASA will launch Curiosity and the other parts of the flight system, delivering the rover to the surface of Mars in August 2012.

Wiens, a geochemist with the U.S. Department of Energy's Los Alamos National Laboratory, serves as ChemCam's principal investigator. An American and French team that he leads proposed the instrument during NASA's 2004 open competition for participation in the Mars Science Laboratory project, whose rover has since been named Curiosity.

In 1997, while working on an idea for using lasers to investigate the moon, Wiens visited a chemistry laboratory building where a colleague, Dave Cremers, had been experimenting with a different laser technique. Cremers set up a cigar-size laser powered by a little 9-volt radio battery and pointed at a rock across the room.

"The room was well used. Every flat surface was covered with instruments, lenses or optical mounts," Wiens recalls. "The filing cabinets looked like they had a bad case of acne. I found out later that they were used for laser target practice."

Cremers pressed a button. An invisible beam from the laser set off a flash on a rock across the room. The flash was ionized gas, or plasma, generated by the energy from the laser exciting atoms in the rock. A spectrometer pointed at the glowing plasma recorded the intensity of light at different wavelengths for determining the rock's atomic ingredients.

Researchers have used lasers for inducing plasmas for decades. What impressed Wiens in this demonstration was the capability to do it with such a low-voltage power source and compact hardware. Using this technology for a robot on another planet seemed feasible. From that point, more than a decade of international development and testing resulted in ChemCam being installed on Curiosity in September 2010.

The international collaboration came about in 2001 when Wiens introduced a former Los Alamos post-doctoral researcher, Sylvestre Maurice, to the project. The core technology of ChemCam, laser-induced breakdown spectroscopy, had been used for years in France as well as in America, but it was still unknown to space scientists there. "The technique is both flashy and very compelling scientifically, and the reviewers in France really liked that combination," Maurice said. A French team was formed, and work on a new laser began.

"The trick is very short bursts of the laser," Wiens said. "You really dump a lot of energy onto a small spot -- megawatts per square millimeter -- but just for a few nanoseconds."

The pinhead-size spot hit by ChemCam's laser gets as much power focused on it as a million light bulbs, for five one-billionths of a second. Light from the resulting flash comes back to ChemCam through the instrument's telescope, mounted beside the laser high on the rover's camera mast. The telescope directs the light down an optical fiber to three spectrometers inside the rover. The spectrometers record intensity at 6,144 different wavelengths of ultraviolet, visible and infrared light. Different chemical elements in the target emit light at different wavelengths.

If the rock has a coating of dust or a weathered rind, multiple shots from the laser can remove those layers to provide a clear shot to the rock's interior composition. "We can see what the progression of composition looks like as we get a little bit deeper with each shot," Wiens said.

Earlier Mars rover missions have lacked a way to identify some of the lighter elements, such as carbon, oxygen, hydrogen, lithium and boron, which can be clues to past environmental conditions in which the rock was formed or altered. After NASA's Mars Exploration Rover Spirit examined an outcrop called "Comanche" in 2005, it took years of analyzing indirect evidence before the team could confidently infer the presence of carbon in the rock. A single observation with ChemCam could detect carbon directly.

ChemCam will be able to interrogate multiple targets the same day, gaining information for the rover team's careful selection of where to drill or scoop samples for laboratory investigations that will take multiple days per target. It can also check the composition of targets inaccessible to the rover's other instruments, such as rock faces beyond the reach of Curiosity's arm.

The instrument's telescope doubles as the optics for the camera part of ChemCam, which records images on a one-megapixel detector. The telescopic camera will show context of the spots hit with the laser and can also be used independently of the laser.

The French half of the ChemCam team, headed by Maurice and funded by France's national space agency, provided the instrument's laser and telescope. Maurice is a spectroscopy expert with the Centre d'Étude Spatiale des Rayonnements, in Toulouse, France. Los Alamos National Laboratory supplied the spectrometers and data processor inside the rover. The optical design of the spectrometers came from Ocean Optics, Dunedin, Fla.

The ChemCam team includes experts in mineralogy, geology, astrobiology and other fields, with some members also on other Curiosity instrument teams.

With the instrument now installed on Curiosity, testing continues at NASA's Jet Propulsion Laboratory, Pasadena, Calif. JPL, a division of the California Institute of Technology in Pasadena, is assembling the rover and other components of the Mars Science Laboratory flight system for launch from Florida between Nov. 25 and Dec. 18, 2011.

Story Source: sciencedaily

Preplay: How Past Experiences Subconsciously Influence Behavior

2010-12-24T07:02:00.000-08:00

ScienceDaily (Dec. 22, 2010) — Researchers at MIT's Picower Institute for Learning and Memory report for the first time how animals' knowledge obtained through past experiences can subconsciously influence their behavior in new situations.

The work, which sheds light on how our past experiences inform our future choices, will be reported on Dec. 22 in an advance online publication of Nature.

Previous work has shown that when a mouse explores a new space, neurons in its hippocampus, the center of learning and memory, fire sequentially like gunpowder igniting a makeshift fuse. Individual neurons called place cells fire in a specific pattern that mirrors the animal's movement through space. By looking at the time-specific patterns and sequences recorded from the firing cells, researchers can tell which part of the maze the animal was running at the time.

In the current work, research scientist George Dragoi and Susumu Tonegawa, Picower Professor of Biology and Neuroscience and director of the RIKEN-MIT Center for Neural Circuit Genetics, found that some of the sequences of place cells in mice' brains that fired during a novel spatial experience such as running a new maze had already occurred while the animals rested before the experience.

"These findings explain at the neuronal circuit level the phenomenon through which prior knowledge influences our decisions when we encounter a new situation," Dragoi said. "This explains in part why different individuals form different representations and respond differently when faced with the same situation."

When a mouse pauses and rests while running a maze, it mentally replays its experience. Its neurons fire in the same pattern of activity that occurred while it was running. Unlike this version of mental replay, the phenomenon found by the MIT researchers is called preplay. It occurred before the animal even started the new maze.

"These results suggest that internal neuronal dynamics during resting organize cells within the hippocampus into time-based sequences that help encode a related experience occurring in the future," Tonegawa said.

"Previous work largely ignored internal neuronal activities representing prior knowledge that occurred before a new event, space or situation. Our work shows that an individual's access to prior knowledge can help predict a response to a new but similar experience," he said.

Funding was provided by the National Institutes of Health.

Story Source: sciencedaily

'Un-Growth Hormone' Increases Longevity, Researchers Find

2010-12-24T06:56:00.000-08:00

ScienceDaily (Dec. 23, 2010) — A compound which acts in the opposite way as growth hormone can reverse some of the signs of aging, a research team that includes a Saint Louis University physician has shown. The finding may be counter-intuitive to some older adults who take growth hormone, thinking it will help revitalize them.

Their research was published in the Dec. 6 online edition of the Proceedings of the National Academy of Sciences.

The findings are significant, says John E. Morley, M.D., study co-investigator and director of the divisions of geriatric medicine and endocrinology at Saint Louis University School of Medicine, because people sometimes take growth hormone, believing it will be the fountain of youth.

"Many older people have been taking growth hormone to rejuvenate themselves," Morley said. "These results strongly suggest that growth hormone, when given to middle aged and older people, may be hazardous."

The scientists studied the compound MZ-5-156, a "growth hormone-releasing hormone (GHRH) antagonist." They conducted their research in the SAMP8 mouse model, a strain engineered for studies of the aging process. Overall, the researchers found that MZ-5-156 had positive effects on oxidative stress in the brain, improving cognition, telomerase activity (the actions of an enzyme which protects DNA material) and life span, while decreasing tumor activity.

MZ-5-156, like many GHRH antagonists, inhibited several human cancers, including prostate, breast, brain and lung cancers. It also had positive effects on learning, and is linked to improvements in short-term memory. The antioxidant actions led to less oxidative stress, reversing cognitive impairment in the aging mouse.

William A. Banks, M.D., lead study author and professor of internal medicine and geriatrics at the University of Washington School of Medicine in Seattle, said the results lead the team "to determine that antagonists of growth hormone-releasing hormone have beneficial effects on aging."

The study team included as its corresponding author Andrew V. Schally, M.D., Ph.D., a professor in the department of pathology and division of hematology/oncology at the University of Miami Miller School of Medicine.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Story Source: sciencedaily

Pterygotid Sea Scorpions: No Terror of the Ancient Seas?

2010-12-24T06:45:00.000-08:00

ScienceDaily (Dec. 24, 2010) — Experiments by a team of researchers in New York and New Jersey have generated evidence that questions the common belief that the pterygotid eurypterids ("sea scorpions") were high-level predators in the Paleozoic oceans. This group, which ranged the seas from about 470 to 370 million years ago (long before the dinosaurs appeared), included the largest and, arguably, scariest-looking arthropods known to have evolved on planet Earth.

Reaching lengths of 2 ½ meters with a body supported by well-developed legs, and armed with a pair of forward-facing claws laden with sharp projecting spines, they seem like the Tyrannosaurus rex among the invertebrates.

But in a new study, published in volume 39 of the Bulletin of the Buffalo Society of Natural Sciences, Richard Laub (Buffalo Museum of Science) and his colleagues Victor Tollerton (Research Associate, New York State Museum) and Richard Berkof (Stevens Institute of Technology) show that the mechanical constraints on the claw of the pterygotid sea scorpion Acutiramus made it incapable of penetrating the external shell of a medium-sized horseshoe crab without danger of rupturing.

They suggest that these imposing sea scorpions, and by extension others of their family who lived in the seas about 470 to 370 million years ago, were not necessarily the voracious predators they are commonly believed to have been. The practical operational force that could be safely applied by the claw of Acutiramus without causing damage to it was no more than about 5 Newtons, whereas a force of 8-17 Newtons was required to penetrate the horseshoe crab's armor.

Laub's team also noted that the absence of an 'elbow joint' between the claws and the body of Acutiramus limited claw movement, making them more effective in grasping prey on the sea floor than capturing actively fleeing fish or other swimming animals. Armed with serrated spines, the claws may have been used together to both capture and shred the prey, but the predatory capabilities of Acutiramus would appear to lack the force necessary for this animal to operate as a major predator.

"I have long been suspicious of prevailing popular interpretations" said Dr. Roy Plotnick, Department of Earth and Environmental Sciences at the University of Illinois at Chicago, who was not involved in the study. "This is a welcome contribution that strongly supports an alternative interpretation of claw function" he said.

"Our results derail the image of these imposing-looking animals, the largest arthropods yet known to have existed, as fearsome predators, or at least as predators of other eurypterids and of the armored fishes of the time" said team leader Richard Laub, who noted that "it opens the possibility that they were scavengers or even vegetarians."

Story Source: sciencedaily.com