Satellite shows high productivity from US corn belt

Data from satellite sensors show that during the Northern Hemisphere’s growing season, the Midwest region of the United States boasts more photosynthetic activity than any other spot on Earth, according to NASA and university scientists.Healthy plants convert light to energy via photosynthesis, but chlorophyll also emits a fraction of absorbed light as fluorescent glow that is invisible to the naked eye. The magnitude of the glow is an excellent indicator of the amount of photosynthesis, or gross productivity, of plants in a given region.Research in 2013 led by Joanna Joiner, of NASA’s Goddard Space Flight Center in Greenbelt, Md., demonstrated that fluorescence from plants could be teased out of data from existing satellites, which were designed and built for other purposes. The new research led by Luis Guanter of the Freie Universitt Berlin, used the data for the first time to estimate photosynthesis from agriculture. Results were published March 25 in Proceedings of the National Academy of Sciences.According to co-author Christian Frankenberg of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., “The paper shows that fluorescence is a much better proxy for agricultural productivity than anything we’ve had before. This can go a long way regarding monitoring — and maybe even predicting — regional crop yields.”Guanter, Joiner and Frankenberg launched their collaboration at a 2012 workshop, hosted by the Keck Institute for Space Studies at the California Institute of Technology in Pasadena, to explore measurements of photosynthesis from space. The team noticed that on an annual basis, the tropics are the most productive. But during the Northern Hemisphere’s growing season, the U.S. Corn Belt “really stands out,” Frankenberg said. “Areas all over the world are not as productive as this area.”The researchers set out to describe the phenomenon observed by carefully interpreting the data from the Global Ozone Monitoring Experiment 2 (GOME-2) on Metop-A, a European meteorological satellite. Data showed that fluorescence from the Corn Belt, which extends from Ohio to Nebraska and Kansas, peaks in July at levels 40 percent greater than those observed in the Amazon.Comparison with ground-based measurements from carbon flux towers and yield statistics confirmed the results.The match between ground-based measurements and satellite measurements was a “pleasant surprise,” said Joiner, a co-author on the paper. …

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Northern and southern hemisphere climates follow the beat of different drummers

Over the last 1000 years, temperature differences between the Northern and Southern Hemispheres were larger than previously thought. Using new data from the Southern Hemisphere, researchers have shown that climate model simulations overestimate the links between the climate variations across Earth with implications for regional predictions.These findings are demonstrated in a new international study coordinated by Raphael Neukom from the Oeschger Centre of the University of Bern and the Swiss Federal Research Institute WSL and are published today in the journal Nature Climate Change.The Southern Hemisphere is a challenging place for climate scientists. Its vast oceans, Antarctic ice, and deserts make it particularly difficult to collect information about present climate and, even more so, about past climate. However, multi-centennial reconstructions of past climate from so-called proxy archives such as tree-rings, lake sediments, corals, and ice-cores are required to understand the mechanisms of the climate system. Until now, these long-term estimates were almost entirely based on data from the Northern Hemisphere.Over the past few years, an international research team has made a coordinated effort to develop and analyse new records that provide clues about climate variation across the Southern Hemisphere. Climate scientists from Australia, Antarctic-experts, as well as data specialists and climate modellers from South and North America and Europe participated in the project. They compiled climate data from over 300 different locations and applied a range of methods to estimate Southern Hemisphere temperatures over the past 1000 years. In 99.7 percent of the results, the warmest decade of the millennium occurs after 1970.Surprisingly, only twice over the entire last millennium have both hemispheres simultaneously shown extreme temperatures. One of these occasions was a global cold period in the 17th century; the other one was the current warming phase, with uninterrupted global warm extremes since the 1970s. “The ‘Medieval Warm Period’, as identified in some European chronicles, was a regional phenomenon,” says Raphael Neukom. …

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Scientists identify gene linking brain structure to intelligence

For the first time, scientists at King’s College London have identified a gene linking the thickness of the grey matter in the brain to intelligence. The study is published today in Molecular Psychiatry and may help scientists understand biological mechanisms behind some forms of intellectual impairment.The researchers looked at the cerebral cortex, the outermost layer of the human brain. It is known as ‘grey matter’ and plays a key role in memory, attention, perceptual awareness, thought, language and consciousness. Previous studies have shown that the thickness of the cerebral cortex, or ‘cortical thickness’, closely correlates with intellectual ability, however no genes had yet been identified.An international team of scientists, led by King’s, analysed DNA samples and MRI scans from 1,583 healthy 14 year old teenagers, part of the IMAGEN cohort. The teenagers also underwent a series of tests to determine their verbal and non-verbal intelligence.Dr Sylvane Desrivires, from King’s College London’s Institute of Psychiatry and lead author of the study, said: “We wanted to find out how structural differences in the brain relate to differences in intellectual ability. The genetic variation we identified is linked to synaptic plasticity — how neurons communicate. This may help us understand what happens at a neuronal level in certain forms of intellectual impairments, where the ability of the neurons to communicate effectively is somehow compromised.”She adds: “It’s important to point out that intelligence is influenced by many genetic and environmental factors. The gene we identified only explains a tiny proportion of the differences in intellectual ability, so it’s by no means a ‘gene for intelligence’.”The researchers looked at over 54,000 genetic variants possibly involved in brain development. They found that, on average, teenagers carrying a particular gene variant had a thinner cortex in the left cerebral hemisphere, particularly in the frontal and temporal lobes, and performed less well on tests for intellectual ability. The genetic variation affects the expression of the NPTN gene, which encodes a protein acting at neuronal synapses and therefore affects how brain cells communicate.To confirm their findings, the researchers studied the NPTN gene in mouse and human brain cells. …

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Surprising underwater-sounds: Humpback whales also spend their winter in Antarctica

Sep. 9, 2013 — Biologists and physicists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, found out that not all of the Southern Hemisphere humpback whales (Megaptera novaeangliae) migrate towards the equator at the end of the Antarctic summer. Part of the population remains in Antarctic waters throughout the entire winter. The scientists report this in a current issue of scientific journal PLOS ONE. This surprising discovery based on underwater recordings from the Antarctic acoustic observatory PALAOA. It is located near the research base Neumayer Station III on the ice shelf and regularly records underwater sounds of humpback whales even in the austral winter months.Sometimes even scientists need the crucial little quantum of luck to obtain new research ideas. For instance Ilse Van Opzeeland, a marine biologist and expert on large whales at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). As she unlocked the door to her office one April morning and, as usual, switched on the live stream of PALAOA, the underwater acoustic observatory, the loudspeakers suddenly resounded with the calls of humpback whales — and this at a time during which the marine mammals should long have been swimming 7,000 kilometres further away in the warmer waters off Africa. “I was totally surprised, because the textbook-opinion until that day was that humpback whales migrate to Antarctic waters only in the austral summer months. And even then, standing believes were that they would only be feeding on krill in the ice-free regions around 60 degrees south latitude. …

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Harbor porpoises can thank their worst enemy, the killer whale, for their success

June 12, 2013 — The harbor porpoise (Phocoena phocoena) is a whale species that is doing quite well in coastal and busy waters. They are found in large numbers throughout the Northern Hemisphere from Mauritania to Alaska, and now researchers from the University of Southern Denmark explain why these small toothed whales are doing so well: The harbor porpoise can thank their worst enemy, the killer whale, for their success.Coastal areas are more challenging and potentially dangerous for a small whale. There is a risk of beaching and being caught in a fisherman’s net, but there are also benefits. Fish are plentiful and easier to find in coastal waters than in the open sea.Therefore, coastal waters are attractive for porpoises, and they are extremely skilled at navigating, locating prey and avoiding hazards near the coast. Like other toothed whales porpoises use echolocation for orientation and to detect prey. They emit a constant stream of sonar clicks, which, when these hit a rock, a fish or a ship nearby an echo is sent back to the porpoise. From the echo, the porpoise can distinguish the location of the object and often also can identify the object.Porpoises can locate even small fish and small objects such as net floats and fine fishing nets. This ability sets them apart from many other toothed whales, which do not have such sophisticated echolocation abilities. The secret of this ability is that the porpoise uses very short clicks and these are higher in frequency than those of many other toothed whales, explains Lee Miller from the Institute of Biology, University of Southern Denmark (SDU).Porpoise clicks last just a hundred-millionth of a second, and are about 130 kHz. For comparison, a human can hear up to 20 kHz and a dog up to about 60 kHz.Lee Miller and his colleague Magnus Wahlberg, also from the Institute of Biology, SDU, now believe that they have found an explanation why porpoise clicks are so high in frequency. …

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Exercise for stroke patients’ brains

June 11, 2013 — A new study finds that stroke patients’ brains show strong cortical motor activity when observing others performing physical tasks — a finding that offers new insight into stroke rehabilitation.Using functional magnetic resonance imaging (fMRI), a team of researchers from USC monitored the brains of 24 individuals — 12 who had suffered strokes and 12 age-matched people who had not — as they watched others performing actions made using the arm and hand that would be difficult for a person who can no longer use their arm due to stroke — actions like lifting a pencil or flipping a card.The researchers found that while the typical brain responded to the visual stimulus with activity in cortical motor regions that are generally activated when we watch others perform actions, in the stroke-affected brain, activity was strongest in these regions of the damaged hemisphere, and strongest when stroke patients viewed actions they would have the most difficulty performing.Activating regions near the damaged portion of the brain is like exercising it, building strength that can help it recover to a degree.”Watching others perform physical tasks leads to activations in motor areas of the damaged hemisphere of the brain after stroke, which is exactly what we’re trying to do in therapy,” said Kathleen Garrison, lead author of a paper on the research. “If we can help drive plasticity in these brain regions, we may be able to help individuals with stroke recover more of the ability to move their arm and hand.”Garrison, who completed this research while studying at USC and is currently a post-doctoral researcher at the Yale University School of Medicine, worked with Lisa Aziz-Zadeh of the USC Brain and Creativity Institute and the Division of Occupational Science and Occupational Therapy; Carolee Winstein, director of the Motor Behavior and Neurorehabilitation Laboratory in the Division of Biokinesiology and Physical Therapy at USC; and former USC doctoral student Sook-Lei Liew and postdoctoral researcher Savio Wong.Their research was posted online ahead of publication by the journal Stroke on June 6.Using action-observation in stroke rehabilitation has shown promise in early studies, and this study is among the first to explain why it may be effective.”It’s like you’re priming the pump,” Winstein said. “You’re getting these circuits engaged through the action-observation before they even attempt to move.” The process is a kind of virtual exercise program for the brain that prepares you for the real exercise that includes the brain and body.The study also offers support for expanding action-observation as a therapeutic technique — particularly for individuals who have been screened using fMRI and have shown a strong response to it.”We could make videos of what patients will be doing in therapy, and then have them watch it as homework,” Aziz-Zadeh said. “In some cases, it could pave the way for them to do better.”

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