September 6, 2006, 5:05 AM CT

Tiny Shock Absorbers Help Bacteria

Bacteria have hair-like protrusions with a sticky protein on the tip that lets them cling to surfaces. The coiled, bungee cord-like structure of the protrusions helps the bacteria hang on tightly, even under rough fluid flow inside the body, researchers report in the journal PLoS Biology.

A group of researchers at the University of Washington in Seattle and ETH Zurich in Switzerland have been studying how the bacterium E. coli attaches to mucous membranes in the body. In their previous research, they explained how the protrusions, known as fimbriae, have an adhesive protein called FimH at their tip that binds in an unusual way to a sugar molecule on a surface.

The FimH-sugar combination makes a "catch bond" that acts like a finger trap, and actually gets stronger as drag force is exerted on a bacterium. Rather than being swept away by fluids moving through the human body, the bacterium grips even more tightly, helping it stick around and form an infection, like those seen in the urinary tract, for instance. The catch bonds release their grip when there is little or no force on the bacteria.

In new research, the scientists have learned that the mechanical properties of the bungee-like fimbriae also play a key role in the tenacity of E. coli clinging to mucousal surfaces. The tiny fiber-like protrusions are made up of interlocking protein segments in a tightly coiled helix shape, like a seven-nanometer-wide Slinky toy. The researchers found that under force, the fimbriae stretch to many times their original length as the protein segments uncoil one by one. If the force on them drops, the fimbriae coils are compressed, keeping tension on the bond between the bacterium and the mucous membrane.........

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September 5, 2006, 10:13 PM CT

Switch from Plant Molecule

Nanoresearchers have transformed a molecule of chlorophyll-a from spinach into a complex biological switch that has possible future applications for green energy, technology and medicine.

The study offers the first detailed image of chloropyhll-a - the main ingredient in the photosynthesis process - and shows how researchers can use new technology to manipulate the configuration of the spinach molecule in four different arrangements, report Ohio University physicists Saw-Wai Hla and Violeta Iancu in today's early edition of the journal Proceedings of the National Academy of Sciences.

The researchers used a scanning tunneling microscope to image chlorophyll-a and then injected it with a single electron to manipulate the molecule into four positions, ranging from straight to curved, at varying speeds. (View a movie here) Though the Ohio University team and others have created two-step molecule switches using scanning tunneling microscope manipulation in the past, the new experiment yields a more complex multi-step switch on the largest organic molecule to date.

The work has immediate implications for basic science research, as the configuration of molecules and proteins impacts biological functions. The study also suggests a novel route for creating nanoscale logic circuits or mechanical switches for future medical, computer technology or green energy applications, said Hla, an associate professor of physics.........

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September 5, 2006, 7:23 PM CT

Gold nanoparticles are highly efficient

Gold nanoparticles are highly efficient and sensitive "handles" for biological molecules being manipulated and tracked by lasers, but they also can heat up fast-by tens of degrees in just a few nanoseconds-which could either damage the molecules or help study them, according to scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and University of Colorado at Boulder.

Biophysicists often study nanoscale and even picoscale mechanics by using lasers to both apply force to and track the position of fragile biomolecules such as DNA or protein by manipulating a tiny sphere-typically polystyrene-attached to the molecule. The JILA team would like to find new microsphere materials that can be trapped by laser radiation pressure more efficiently, which would enable faster measurements and detection of smaller motions at the same laser power. As described in the Aug. 15 issue of Optics Letters,* the JILA team demonstrated that 100-nanometer-wide gold beads, as expected because of their metallic nature, can be trapped and detected six times more easily than polystyrene particles of a similar size.

However, the scientists also found that gold absorbs light and heats up quickly, by a remarkable 266 degrees (Celsius) per watt of laser power, at the wavelength most often used in optical traps. Unless very low laser power is used, the heat could damage the molecules under study. Thus, gold beads would not be useful for temperature-sensitive experiments or applying force to molecules. But the heating effect could be useful in raising local temperatures in certain experiments, such as heating a protein just enough to allow scientists to watch it unfold, the paper suggests.........

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September 5, 2006, 6:52 PM CT

Electron Beam And Atomic Switch

Researchers at the Commerce Department's National Institute of Standards and Technology (NIST) have used a beam of electrons to move a single atom in a small molecule back and forth between two positions on a crystal surface, a significant step toward learning how to build an "atomic switch" that turns electrical signals on and off in nanoscale devices.

The results, described in the Aug. 18, 2006, issue of Science,* are the first would be published about work at NIST's new Center for Nanoscale Science and Technology (www.nist.gov/public_affairs/releases/cnst.htm).

"It's still futuristic to talk about a real atomic switch but we're getting closer," says physicist Joseph Stroscio, lead author of the paper. In addition, by applying the findings to nanoscale fabrication on semiconductors and insulating thin films, it may be possible to develop new classes of electronic and magnetic devices constructed atom by atom.

In the work described in Science, NIST physicists used a custom-built, cryogenic scanning tunneling microscope (STM)-which provides a voltage and beam of electrons at its needle-like tip-to perform several different types of atomic scale measurements and manipulations. NIST theorists performed calculations of the atoms' electronic structure, which confirmed the experimental results.........

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September 4, 2006, 10:12 PM CT

Valuable data from SMART-1

Right up to its final orbits, SMART-1 continued delivering valuable data, extending the mission's legacy as a technology and scientific success. Scientists and engineers met today at ESOC to review mission achievements including final AMIE camera images.

At a press event held today at ESA's Spacecraft Operations Centre (ESOC), SMART-1 engineers, operations experts and scientists are presenting data and preliminary results obtained by the spacecraft prior to its impact on the Moon at 07:42 CEST, 3 September 2006.

Perhaps the most sentimental image sequence was taken by AMIE just four days before impact, on 29 August at 21:00 CEST (19:00 UT), when the camera was pointed back towards the Earth to capture, in the best tradition of many previous lunar missions, a view of our home planet. The sequence of images is centred over Brazil at approximately 44.9º West and 19.2º South (North is to the left). The Kourou area in French Guiana, from where SMART-1 was launched in 2003, is also visible.

Remarkably, this movie sequence shows the Moon passing in front of the Earth, beautifully underlining the close gravitational relationship between the Earth and its natural satellite.

Final orbits offered new imaging opportunities

During SMART-1's final orbits on 1 and 2 September, the spacecraft was passing at extremely low altitude over the Moon's surface, which was in darkness, prompting scientists to take advantage of this unique observational situation by pointing the AMIE camera laterally toward the Moon's limb (horizon). The camera gathered images of the thin dust envelope surrounding the Moon, which will be analysed by scientists in the future.........

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September 3, 2006, 8:17 AM CT

Nutritional Value Of Salad

"Rabbit food" is nutritious for people, too. Go ahead and indulge at the salad bar.

A new UCLA/Louisiana State University study of dietary data on more than 17,500 men and women finds consumption of salad and raw vegetables correlates with higher concentrations of folic acid, vitamins C and E, lycopene and alpha and beta carotene in the bloodstream.

Published in the September edition of the peer-reviewed Journal of the American Dietetic Association, the study also suggests that each serving of salad consumed correlates with a 165 percent higher likelihood of meeting recommended dietary allowances (RDA) for vitamin C in women and 119 percent greater likelihood in men.

The study is the first to examine the relationship between normal salad consumption and nutrient levels in the bloodstream, and also the first to examine the dietary adequacy of salad consumption using the latest nutritional guidelines of the Food and Nutrition Board of the National Academy of Sciences.

The findings blunt concerns about the human body's ability to absorb nutrients from raw vegetables, as well as concern that the structure and characteristics of some plants undercut nutritional value.

"The consistently higher levels of certain nutrients in the bloodstream of salad-eaters suggest these important components of a healthy diet are being well-absorbed from salad," said Lenore Arab, visiting professor of epidemiology at the UCLA School of Public Health and co-author of the study with L. Joseph Su, assistant professor at the LSU School of Public Health.........

Posted by: Beverly      Permalink         Source

September 3, 2006, 6:57 AM CT

Lockheed Martin Corp Is The Orion Contractor

Lessons from the past are guiding NASA's next step into the future, as the space agency prepares to replace the space shuttle with an Apollo-style vehicle for human explorers.

The vehicle is Orion, named for one of the brightest and most recognizable star formations in the sky. It will be a multi-purpose capsule -- the central member of a family of spacecraft and shuttle-derived launchers that NASA's Constellation Program is developing to carry astronauts back to the moon and later to Mars. The first flight with astronauts aboard is planned for no later than 2014. Orion's first flight to the moon is planned for no later than 2020.

NASA has selected Lockheed Martin Corp. as the prime contractor to design, develop, and build Orion, America's spacecraft for a new generation of explorers.

The Orion crew capsule will carry astronauts back to the moon and later to Mars. The first flight with astronauts aboard is planned for no later than 2014. Orion's first flight to the moon is planned for no later than 2020.

In what amounts to one of the most significant NASA procurements in more than 30 years, two industry teams, Northrop Grumman/Boeing and Lockheed Martin, spent the past 13 months refining concepts, analyzing requirements and sketching designs for Orion. On Thursday, managers of NASA's Exploration Systems Mission Directorate revealed that Lockheed Martin Corp. of Bethesda, Md., has been chosen to build it.........

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September 2, 2006, 10:00 PM CT

Weeds In The Garden This Year

Some years, no matter how diligently you pull, your backyard garden is always covered with weeds. Other years, with the minimum of effort, your garden remains weed-free. What is the cause of these oscillations? A group of weed researchers based at the Spanish National Research Council (CSIC) spent fifteen years studying flixweed a member of the mustard family usually found in areas where the ground has been cultivated or disturbed in an attempt to identify the processes underlying these fluctuations.

"The failure to recognize the intrinsic nature of a number of weed population changes may result in over-application of control inputs, with subsequent negative economic and environmental effects," says Jose Gonzalez-Andujar, who co-authored the study, forthcoming in The American Naturalist, with Cesar Fernandez-Quintanilla and Luis Navarrete.

A number of populations exhibit cyclic oscillations. Everybody can recall a summer where mosquitoes hindered attempts at al fresco dining. These cycles can be produced by climatic conditions or by internal feedback mechanisms. However, in contrast with studies of insect and animal populations, little attention has been directed at the study of cycles in plants. What happens with your garden weeds?

The scientists demonstrate that there are some intrinsic mechanisms that explain observed plant oscillations more specifically, evidence of cycles produced by delayed density dependence in a plant population growing under field conditions. This study can have a capital importance in crop protection.........

Posted by: Beverly      Permalink         Source

September 2, 2006, 9:52 PM CT

Spread Of Plant Diseases By Insects

Researchers from Penn State University and the University of Virginia show that the spread of diseases by insects can be described by equations similar to those that describe the force of gravity between planetary objects. Their findings are detailed in the recent issue of The American Naturalist.

Insects tend to transmit diseases in the course of feeding on plants, and their movement between plants is influenced by plant quality (how good of a meal they'll get) and the distance between plants, or, how far they'll have to travel to get to the next meal, explain Matthew Ferrari, Jessica Partain, Janis Antonovics, and Ottar Bjornstad.

"It turns out insects are more likely to move shorter distances between better plants," write the authors. "Interestingly, then, the probability of disease being passed between two plants goes up if they are closer and/or better, which parallels the stronger gravity between closer and larger planets".

The researchers tracked a fungal disease spread by bees and moths in the course of pollinating and feeding on nectar from white campion flowers at the University of Virginia's Mountain Lake Biological Station. As predicted by the behaviour of insects, the disease was more likely to spread shorter distances between plants that had many flowers.........

Posted by: Beverly      Permalink         Source

September 2, 2006, 9:26 PM CT

Real-Time Traffic Routing

Engineers have developed a system for taking anonymous cell-phone location information and turning it into an illuminated traffic map that identifies congestion in real time.The system takes advantage of the steady stream of positioning cues--untraced signals all cell phones produce, whether in use or not, as they seek towers with the strongest signals. It is the first traffic-solution technology that monitors patterns on rural roads and city streets as easily as on highways.

Developed by IntelliOne of Atlanta, Ga., the TrafficAid system could not only help guide drivers around tie-ups, but also tell emergency responders where accidents are or how effectively an evacuation is unfolding by pinpointing clusters of cell phones.

"Unlike sensors and other equipment along major freeways that are expensive and take years to deploy, our system takes advantage of existing cellular networks in which wireless carriers have already invested billions of dollars," said National Science Foundation (NSF) awardee and IntelliOne CEO Ron Herman, a former engineer and computer scientist.

Herman was inspired by a friend's demonstration several years ago of a proof-of-concept Palm Pilot software that used real-time California Department of Transportation travel-time data to route the drivers around traffic snarls."I was completely sold," said Herman. "I believed then the next 'killer app' for mobile would demand live traffic data for every road--not just select highways equipped with speed sensors--and set out to make it happen".........

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