November 1, 2006, 7:45 PM CT

Microscope Probes Nano-electronics

A new form of scanning microscopy that simultaneously reveals physical and electronic profiles of metal nanostructures has been demonstrated at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and University of Colorado at Boulder. The new instrument is expected to be particularly useful for analyzing the make-up and properties of nanoscale electronics and nanoparticles.

Scanning photoionization microscopy (SPIM), described in a new paper,* combines the high spatial resolution of optical microscopy with the high sensitivity to subtle electrical activity made possible by detecting the low-energy electrons emitted by a material as it is illuminated with laser pulses. The technique potentially could be used to make pictures of both electronic and physical patterns in devices such as nanostructured transistors or electrode sensors, or to identify chemicals or even elements in such structures.

"You make images by virtue of how readily electrons are photoejected from a material," says NIST Fellow David Nesbitt, leader of the research group. "The method is in its infancy, but nevertheless it really does have the power to provide a new set of eyes for looking at nanostructured metals and semiconductors".

The JILA-built apparatus includes a moving optical microscopy stage in a vacuum, an ultrafast near-ultraviolet laser beam that provides sufficient peak power to inject two photons (particles of light) into a metal at virtually the same time, and equipment for measuring the numbers and energy of electrons ejected from the material. By comparing SPIM images of nanostructured gold films to scans using atomic force microscopy, which profiles surface topology, the researchers confirmed the correlations and physical mapping accuracy of the new technique. They also determined that lines in SPIM images correspond to spikes in electron energy, or current, and that contrast depends on the depth of electrons escaping from the metal as well as variations in material thickness.........

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November 1, 2006, 4:30 PM CT

Why Do Plants Shed Leaves?

In a study from the recent issue of The American Naturalist, scientists Alex Boonman and co-workers from the Netherlands show that it is beneficial for plants growing in a dense stand to shed their oldest, lower leaves once these become shaded. By using transgenic tobacco plants that do not shed their lower leaves, they were able to show that shaded old leaves become a burden to a plant because they no longer photosynthesize but still require energy to be maintained.

Moreover, the nutrients in these leaves can be more usefully employed by the plant when re-allocated to new leaves at the top of the canopy, where more light is available and higher photosynthetic rates can be attained. Previously, theoretical modeling has been extensively used to investigate how plants should distribute their leaf area and nutrients to maximize their photosynthesis and fitness. However, a direct experimental test was lacking till now.

"Keeping up with the neighbors is important for plants in leaf canopies" Alex Boonman states, "because failure to project enough leaf area at the top of the canopy means that some other plant will do it, with shading and therefore diminished photosynthesis as the consequence." The transgenics, which were originally developed by Susheng Gan and Richard Amasino at the University of Wisconsin, indeed produced less leaf area in the upper canopy layer than normal plants and performed less well in competition exeriments.........

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October 31, 2006, 9:26 PM CT

Save Threatened Turtles

Ecology and conservation experts from the University of Exeter today urge international governments to work together to protect threatened Caribbean sea turtle populations.

The Cayman Islands, a UK Overseas Territory, once supported one of the world's largest sea turtle rookeries, which comprised some 6.5 million adult green and loggerhead turtles. These populations were driven into decline from the mid-1600s onwards, when massive harvesting of nesting turtles began. Only a few dozen individuals survive today.

New research, led by the University of Exeter's School of Biosciences and the Cayman Islands Department of Environment, reveals the astonishing distances these animals travel and the extent to which they are now threatened. The study was published open access today in the international conservation journal Endangered Species Research.

Marine turtles spend most of their lives at sea, but where these Cayman Islands survivors live when they are not nesting has been a mystery until now. Experts from the University of Exeter, the Cayman Islands Department of Environment and Duke University, USA, followed the journeys of ten endangered adult females over three years.

Using satellite transmitters, the team tracked the turtles travelling as far as Belize, Guatemala, Honduras, Mexico, Nicaragua and the USA. On these long journeys, turtles face the risk of being caught for meat, as well as accidentally captured by shrimp trawls, longlines, and gillnets. As turtles travel across boundaries between countries, conservation legislation is inconsistently applied and enforced, leaving them vulnerable.........

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October 31, 2006, 7:52 PM CT

Warmer, Wetter World this Century

Recent episodes of deadly heat in the United States and Europe, long dry spells across the U.S. West, and heavy bursts of rain and snow across much of North America and Eurasia hint at longer-term changes to come, according to a new study based on several of the world's most advanced climate models. Much of the world will face an enhanced risk of heat waves, intense precipitation, and other weather extremes, conclude scientists from the National Center for Atmospheric Research (NCAR), Texas Tech University, and Australia's Bureau of Meteorology Research Centre.

The new study, "Going to the Extremes," will appear in the recent issue of the journal Climatic Change.

Many previous studies have looked at how average temperature or rainfall might change in the next century as greenhouse gases increase. However, the new research looks more specifically at how weather extremes could change.

"It's the extremes, not the averages, that cause the most damage to society and to many ecosystems," says NCAR scientist Claudia Tebaldi, lead author for the report. "We now have the first model-based consensus on how the risk of dangerous heat waves, intense rains, and other kinds of extreme weather will change in the next century".

The study is one of the first analyses to draw on extensive and sophisticated computer modeling recently carried out for the Intergovernmental Panel on Climate Change. The IPCC's next assessment report will be released early in 2007.........

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October 31, 2006, 6:59 PM CT

Snake on a Galactic Plane!

Something scary appears to be slithering across the plane of our Milky Way galaxy in this new Halloween image from NASA's Spitzer Space Telescope. The snake-like object is actually the core of a thick, sooty cloud large enough to swallow dozens of solar systems. In fact, astronomers say its "belly" may be harboring beastly stars in the process of forming.

"The snake is an ideal place to hunt for massive forming stars as they have not had time to heat up and destroy the cloud they are born in," said Dr. Sean Carey, also known as "Dr. Scarey," of NASA's Spitzer Science Center. Dr. Scarey, who is leading the new research, was also principal investigator of a prior Halloween image from Spitzer, showing a 'great galactic ghoul'.

Spitzer was able to spot the sinuous cloud using its heat-seeking infrared vision. The object is hiding in the dusty plane of our Milky Way galaxy, invisible to optical telescopes. Because its heat, or infrared light, can sneak through the dust, it first showed up in infrared images from past missions. The cloud is so thick with dust that if you were to somehow transport yourself into the middle of it, you would see nothing but black, not even a star in the sky. Now, that's spooky!

Spitzer's new view of the snake provides the best look at what lurks inside. The yellow and orange spots located on and around it are massive stars just beginning to take shape. The bright red spot located on its belly is a monstrous stellar embryo, with about 20 to 50 times the mass of our sun.........

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October 31, 2006, 5:07 AM CT

New Species Discovered Inhawaiian Islands

A three-week scientific expedition to French Frigate Shoals in the Northwestern Hawaiian Islands Marine National Monument returned to Honolulu on Sunday with the discovery of many new species and a better understanding of marine biodiversity in the Hawaiian Archipelago.

An all-star team of world-renowned taxonomists (biologists specializing in identifying and naming organisms) and an experienced support crew collected and photographed many species that they cannot identify and are thought to be new species to science. The expedition found several potentially new species of crabs, corals, sea cucumbers, sea quirts, worms, sea stars, snails, and clams. Many other species were found that are known from other areas but have never been recorded from French Frigate Shoals, the Northwestern Hawaiian Islands, or even the Hawaiian Archipelago. From this expedition, well over a hundred new species records will likely be identified for French Frigate Shoals.

Scientists aboard the National Oceanic and Atmospheric Administration Ship Oscar Elton Sette conducted biodiversity surveys at French Frigate Shoals, with a focus on the small marine organisms - crabs, worms, and many other invertebrates, algae, and even microbes - which are often overlooked but that make up the majority of living diversity on coral reefs. "It was a very successful expedition by almost any criterion, and the discovery phase has really only just begun. In the coming months, and even over the next several years, we will be conducting morphological examinations and analyzing genetic sequence data in order to further identify and classify these organisms, and possibly to shed some light on where these species originated," said Dr. Joel W. Martin of the Natural History Museum of Los Angeles County. "What we did not find is also important. There were several groups of animals that we expected to find but did not find, or found only rarely, such as porcellanid crabs. The apparent absence of these common reef organisms may provide insight into how the unique flora and fauna of French Frigate Shoals came to be".........

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October 31, 2006, 4:51 AM CT

Global Warming And Insect Population Growth

Insects have proven to be highly adaptable organisms, able through evolution to cope with a variety of environmental changes, including relatively recent changes in the world's climate. But like something out of a scary Halloween tale, new University of Washington research suggests insects' ability to adapt to warmer temperatures carries an unexpected consequence - more insects.

It appears that insect species that adapt to warmer climates also will increase their maximum rates of population growth, which UW scientists say is likely to have widespread affects on agriculture, public health and conservation.

A number of studies have shown that insects readily adapt to the temperature of their environment. For example, those living in deserts easily tolerate high temperatures but are much less tolerant of cold temperatures than insects living in mountains. Now UW biology scientists have observed that insect species that have adapted to warmer environments also have faster population growth rates. The research shows, in effect, that "warmer is better" for insects, said Melanie Frazier, a UW biology doctoral student.

"Enhanced population growth rates for butterflies might be a good thing, but enhanced growth rates for mosquito populations is much more dubious," said Frazier, who is lead author of the new research, reported in the October edition of the journal The American Naturalist.........

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October 31, 2006, 4:22 AM CT

Insights Into Spiders' Polymer Art

A team of MIT engineers has identified two key physical processes that lend spider silk its unrivaled strength and durability, bringing closer to reality the long-sought goal of spinning artificial spider silk.

Manufactured spider silk could be used for artificial tendons and ligaments, sutures, parachutes and bulletproof vests. But engineers have not managed to do what spiders do effortlessly.

As per a research findings reported in the recent issue of the Journal of Experimental Biology, Gareth H. McKinley, professor of mechanical engineering, and his colleagues examined how spiders spin their native silk fibers, with hopes of ultimately reproducing the process artificially.

McKinley heads the Non-Newtonian Fluid Dynamics research group in MIT's Department of Mechanical Engineering. Non-Newtonian fluids behave in strange and unexpected ways because their viscosity, or consistency, changes with both the rate and the total amount of strain applied to them.

Spider silk is a protein solution that undergoes pronounced changes as part of the spinning process. Egg whites, another non-Newtonian fluid, change from a watery gel to a rubbery solid when heated. Spider silk, it turns out, undergoes similar irreversible physical changes.

Stickiness and Flow........

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October 30, 2006, 8:47 PM CT

Brain's Response To Pleasing

We all have tastes we love, and tastes we hate. And yet, our "taste" for certain flavors and foods can change over time, as we get older or we get tired of eating the same old thing.

Now, a new University of Michigan study gives new evidence about what's going on in the brain when we taste something we like, or develop a liking for something we once hated.

And although the study used rats instead of people, it has direct implications for understanding the way we perceive pleasure and the reasons why some people develop problems, such as drug abuse, depression or anorexia, that knock their pleasure response off balance.

In a new paper in the recent issue of the Journal of Neurophysiology, U-M neuroscientists and psychologists report the findings from direct monitoring of an area of the brain known as the ventral pallidum. Located deep in the brain, it's a kind of traffic center for signals from different areas of the brain that process tastes and pleasurable sensations.

The researchers were able to track the activity of brain cells in that area while the rats received water, salt water and sugar water directly into their mouths. They also recorded how the rats behaved while they tasted those different solutions, including signs that they liked or disliked the tastes. And, they repeated the tests when the rats had been treated with drugs that greatly reduced their bodies' salt levels.........

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October 30, 2006, 8:30 PM CT

3-D ultrasound and robotic surgery

Duke University engineers have shown that a three-dimensional ultrasound scanner they developed can successfully guide a surgical robot.

The scanner could find application in various medical settings, as per the researchers. They said the scanner ultimately might enable surgeries to be performed without surgeons, a capability that could prove valuable in space stations or other remote locations.

"It's the first time, to our knowledge, that anyone has used the information in a 3-D ultrasound scan to actually guide a robot," said Stephen Smith, professor of biomedical engineering at Duke's Pratt School of Engineering.

Smith and Eric Pua, a Pratt graduate student who participated in the research, reported the findings in the cover article of the November 2006 issue of the journal IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control http://www.ieee-uffc.org/tr/covers/2006toc.htm#nov06.

The work was supported by the National Institutes of Health and the National Science Foundation.

In their demonstration, the scientists used 3-D ultrasound images to pinpoint in real time the exact location of targets in a simulated surgical procedure. That spatial information then guided a robotically controlled surgical instrument right to its mark.........

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