Back to the main page

Archives Of Science Blog

Subscribe To Science Blog RSS Feed  RSS content feed What is RSS feed?

April 23, 2007, 10:25 PM CT

Managing Forests in Hurricane Impact Zones

Managing Forests in Hurricane Impact Zones
Forest Service researchers have developed an adaptive strategy to help natural resource managers in the southeastern United States both prepare for and respond to disturbance from major hurricanes. In an article published in the journal Forest Ecology and Management, John Stanturf, Scott Goodrick, and Ken Outcalt from the Forest Service Southern Research Station (SRS) unit in Athens, GA, report the results of a case study based on the effects of hurricanes Katrina and Rita.

The past 10 hurricane seasons have been the most active on record, with climatologists predicting that heightened activity could continue for another 10 to 40 years. In early April, Colorado State University meteorologists predicted a very active 2007 hurricane season for the Atlantic coast, with 17 named storms, including 5 major Hurricanes. The analysis included a 74 percent probability of a major hurricane hitting the U.S. coast before the season ends on November 30.

"Coastal areas in the southern United States are adapted to disturbance from both fire and high wind," says Stanturf, project leader of the SRS disturbance ecology unit based in Athens, GA. "But those adaptations only go so far in the face of a major hurricane. Forest owners and natural resource managers need strategies to deal with hurricane damage to coastal forests".........

Posted by: John      Read more         Source

April 23, 2007, 10:17 PM CT

How much nitrogen is too much for corn?

How much nitrogen is too much for corn?
North Carolina State researchers recently discovered a test that quickly predicts nitrogen levels in the humid soil conditions of the southeastern United States. These scientists report that the Illinois Soil Nitrogen Test (ISNT) can assess the nitrogen levels in soil with more accuracy than current soil-based tests. This test will allow growers to cut back on the amount of nitrogen-based fertilizer added to soil, leading to economic and environmental benefits.

The proper management of nitrogen is critical to the success of many crop systems. Based on an assessment of the natural amount of nitrogen in soil, growers calculate their optimum nitrogen rates, the concentration of nitrogen that must be present in fertilizer in order to achieve expected crop yields. Under- and over-applying nitrogen fertilizer to corn crops often leads to adverse economic consequences for corn producers. Excess levels of nitrogen in nature also pose serious threats to environment. Agricultural application of nitrogen has been linked to rising nitrate levels and subsequent death of fish in the Gulf of Mexico and North Carolinas Neuse River.

"Although offsite nitrogen contamination of ground and surface waters could be reduced if nitrogen rates were adjusted based on actual field conditions, there is currently no effective soil nitrogen test for the humid southeastern U.S.," said Jared Williams, lead author of the North Carolina State study that was published in the March-April 2007 issue of the Soil Science Society of America Journal. This research was supported in part by USDA Initiative for Future Agricultural and Food Systems (IFAFS) grant.........

Posted by: Nora      Read more         Source

April 17, 2007, 11:06 PM CT

Critical Step in Membrane Fusion

Critical Step in Membrane Fusion
Cells constantly swap cargo bound in vesicles, miniscule membrane-enclosed packages of proteins and other chemicals. Before the swap can take place, the vesicle membrane must fuse with another membrane, creating channels packages can pass through.

This process, known as membrane fusion, is fundamental to health and disease. It occurs at fertilization and is especially critical to keep hormones circulating and brain cells firing. Membrane fusion is also how HIV and other viruses infect cells.

But membrane fusion occurs in less than a millisecond, making it difficult to see precisely how it unfolds. Now Brown University biologist Gary Wessel and his laboratory team have seen and recorded a critical step in the process in a live cell.

Scientists in the Wessel lab are experts in fertilization; they used sea urchin eggs to study membrane fusion. In urchin eggs, thousands of membrane-bound vesicles are attached to the plasma membrane. Within seconds after fertilization, the contents of these vesicles are rapidly released. Prior research has shown that special proteins kept these vesicles tethered to the egg's membrane. What about the membranes? What do they look like before vesicle cargo is released?

Wessel and his collaborators discovered that the membranes of the egg and the vesicles are hemifused - a state where the membranes are shared but the contents remain separate. Using fluorescent dyes and a high-resolution microscope, the scientists show that hemifusion is surprisingly stable in live cells.........

Posted by: John      Read more         Source

April 15, 2007, 8:39 PM CT

Freezing 'Dance' Of Nanoscale Drops

Freezing 'Dance' Of Nanoscale Drops
Using what is believed to be the worlds smallest pipette, two scientists at the U.S. Department of Energys Brookhaven National Laboratory have shown that tiny droplets of liquid metal freeze much differently than their larger counterparts. This study, focused on droplets just a billionth of a trillionth of a liter in size, is reported in the April 15, 2007, online edition of Nature Materials.

Our findings could advance the understanding of the freezing process, or crystallization, in a number of areas of nature and technology, said Eli Sutter, a scientist at Brookhavens Center for Functional Nanomaterials (CFN) and the lead author of the study.

Melting and crystallization are so-called phase transformations fundamental processes by which most substances change between a disordered liquid state (such as liquid water) and an ordered solid state (e.g., ice). When a liquid droplet is cooled, the motion of its atoms gradually slows until they come to a stop, resulting in a solid. For large droplets, this crystallization commonly starts at a small impurity (e.g., a speck of dirt), from which it rapidly spreads over the entire droplet. However, very pure substances lack such crystallization centers and have difficulty starting the phase transformation.

The accepted theory of crystallization, developed in the first half of the prior century, predicts that without impurities, a small solid core generated at random in the.........

Posted by: John      Read more         Source

April 12, 2007, 6:43 PM CT

Thirty-Two Mile Cable Installed

Thirty-Two Mile Cable Installed
Oceanographers have completed an important step in constructing the first deep-sea observatory off the continental United States. Workers in the multi-institution effort laid 32 miles (52 kilometers) of cable along the Monterey Bay sea floor that will provide electrical power to scientific instruments, video cameras, and robots 3,000 feet (900 meters) below the ocean surface. The link will also carry data from the instruments back to shore, for use by researchers and engineers from around the world.

The Monterey Accelerated Research System (MARS) observatory, due to be completed later this year, will provide ocean researchers with 24-hour-a-day access to instruments and experiments in the deep sea. The project is managed by the Monterey Bay Aquarium Research Institute (MBARI) and funded by the National Science Foundation (NSF).

Currently, almost all oceanographic instruments in the deep sea rely on batteries for power and store their data on hard disks or memory chips until they are brought back to the surface. With a continuous and uninterrupted power supply, instruments attached to the MARS observatory could remain on the sea floor for months or years.

"MARS represents the first step in a long-planned process to transform the way the oceans are studied," said Julie Morris, director of NSF's Division of Ocean Sciences. "Marine researchers will no longer be mandatory to go out to the ocean for their studies. The ocean is about to come into their offices".........

Posted by: John      Read more         Source

April 12, 2007, 6:20 PM CT

Cells Selectively Absorb Short Nanotubes

Cells Selectively Absorb Short Nanotubes Nanotube length threshold
DNA-wrapped single-walled carbon nanotubes (SWCNTs) shorter than about 200 nanometers readily enter into human lung cells and so may pose an increased risk to health, as per researchers at the National Institute of Standards and Technology (NIST). The results of their laboratory studies appear in an upcoming issue of Advanced Materials.*.

Eyed for uses ranging from electronic displays to fuel cells to water filtration, SWCNTs are tiny cylinders-essentially single-sheet rolls of carbon atoms. They are a number of times stronger than steel and possess superlative thermal, optical and electronic properties, but safety and biocompatibility remain an open question.

"Published data citing in vitro (outside the body) toxicity are especially inconsistent and widely disputed," writes biomaterials scientist Matthew Becker and his NIST colleagues. Public concerns surrounding the environmental, health and safety impacts of SWCNTs could derail efforts to fast track the development of nanotubes for advanced technology applications. A significant hurdle in outlining the parameters contributing to nanotube toxicity is to prepare well-defined and characterized nanotube samples, as they typically contain a distribution of lengths, diameters, twists and impurities.

The team chose to isolate the effects of nanotube length. They first adsorbed short DNA molecules onto the nanotubes because this renders them soluble in water and allows them to be sorted and separated by length. The scientists then exposed human lung fibroblasts to solutions containing unsorted nanotubes. Regardless of the concentration levels, the cells did not absorb between about one-fourth and one-third of the SWCNTs in the solutions. Further examination of the results revealed that only short nanotubes made it into the cellular interior.........

Posted by: John      Read more         Source

April 11, 2007, 10:24 PM CT

Virus-size 'Nanolamps'

Virus-size 'Nanolamps' Craighead Research Group
An illustrated closeup of an electrospun fiber. During experimentation the organic devices gave off an orange glow
To help light up the nanoworld, a Cornell interdisciplinary team of scientists has produced microscopic "nanolamps" -- light-emitting nanofibers about the size of a virus or the tiniest of bacteria.

In a collaboration of experts in organic materials and nanofabrication, scientists have created one of the smallest organic light-emitting devices to date, made up of synthetic fibers just 200 nanometers wide (1 nanometer is one-billionth of a meter). The potential applications are in flexible electronic products, which are being made increasingly smaller.

The fibers, made of a compound based on the metallic element ruthenium, are so small that they are less than the wavelength of the light they emit. Such a localized light source could prove beneficial in applications ranging from sensing to microscopy to flat-panel displays.

The work, reported in the recent issue of Nano Letters, was a collaboration of nine Cornell researchers, including first author Jose M. Moran-Mirabal, an applied physics Ph.D. student; Hector Abruña, the E.M. Chamot Professor of Chemistry and Chemical Biology; George Malliaras, associate professor of materials science and engineering and director of the Cornell NanoScale Facility; and Harold Craighead, the C.W. Lake Jr. Professor of Engineering and director of the National Science Foundation-funded Nanobiotechnology Center.........

Posted by: John      Read more         Source

April 11, 2007, 10:16 PM CT

Clarifying The Behavior Of Neutrinos

Clarifying The Behavior Of Neutrinos Bonnie Fleming with a photoreceptor from the MiniBooNE experiment.
Credit: Yal
New Haven, Conn. The initial data from the 10-year long "MiniBooNE" experiment at the Department of Energy's Fermilab significantly clarifies the overall picture of how the neutrino fundamental particles behave.

The project was designed to confirm or refute surprising observations from the Department of Energy's Los Alamos National Laboratory's Liquid Scintillator Neutrino Detector (LSND) experiments in the 1990's that were explained simply by the ability of neutrinos to transform from one type into another and back again, a process called neutrino oscillation. This research showed conclusively that there is more to the story.

A lecture by Yale Assistant Professor Bonnie Fleming, a MiniBoone project participant, will announce the results locally on Thursday, April 12 at 3:30 p.m. in room 57 of Sloane Physics Laboratories, at 217 Prospect Street. The talk is free and open to the public.

The MiniBooNE experiment mimicked the earlier Liquid Scintillator Neutrino Detector (LSND) experiment by looking for signs of muon neutrinos oscillating into electron neutrinos in the region indicated by the LSND observations. The team expected that the experiment would produce a distinct background and oscillation "signature".........

Posted by: John      Read more         Source

April 11, 2007, 9:20 PM CT

Nongreen Plants On Other Planets

Nongreen Plants On Other Planets
NASA scientists believe they have found a way to predict the color of plants on planets in other solar systems.

Green, yellow or even red-dominant plants may live on extra-solar planets, according to scientists whose two scientific papers appear in the recent issue of the journal, Astrobiology. The scientists studied light absorbed and reflected by organisms on Earth, and determined that if astronomers were to look at the light given off by planets circling distant stars, they might predict that some planets have mostly non-green plants.

"We can identify the strongest candidate wavelengths of light for the dominant color of photosynthesis on another planet," said Nancy Kiang, lead author of the study and a biometeorologist at NASA's Goddard Institute for Space Studies, New York. Kiang worked with a team of scientists from the Virtual Planetary Laboratory (VPL) at the California Institute of Technology, Pasadena, Calif. VPL was formed as part of the NASA Astrobiology Institute (NAI), based at the NASA Ames Research Center in California's Silicon Valley.

"This work broadens our understanding of how life may be detected on Earth-like planets around other stars, while simultaneously improving our understanding of life on Earth," said Carl Pilcher, director of the NAI at NASA Ames. "This approach -- studying Earth life to guide our search for life on other worlds -- is the essence of astrobiology".........

Posted by: Edwin      Read more         Source

April 10, 2007, 8:54 PM CT

Milk beats soy for post-weighlifting muscle gain

Milk beats soy for post-weighlifting muscle gain
Got milk? Weightlifters will want to raise a glass after a new study found that milk protein is significantly better than soy at building muscle mass.

The study, conducted by a team of researchers at McMaster Universitys Department of Kinesiology, was recently published in the American Journal of Clinical Nutrition. It compared how much muscle protein young men gained after completing a heavy weight workout followed by consumption of equivalent amounts of protein as either fluid skim milk or a soy drink.

"Our thinking going into the study was that milk would be better than soy. We suspected this would be the case because of work done by French researchers. However, we were really impressed by how much greater the gains in muscle protein with milk were," says Sarah Wilkinson, lead researcher and a graduate student in the department of kinesiology.

The findings would suggest that if men consume only skim milk (two cups) after each of their workouts, they would gain almost twice as much muscle in 10 weeks than if they drank the same amount of protein as a soy drink.

"This is an interesting finding, since soy and milk proteins are considered to be complete proteins that are basically equivalent from a nutritional standpoint," explains Stuart Phillips, associate professor of kinesiology, who was also involved in the study. "Our findings clearly show that milk proteins are a superior source of protein in producing muscle mass gains in response to weightlifting".........

Posted by: Nora      Read more         Source

Older Blog Entries   Older Blog Entries   1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51   52   53   54   55   56