May 12, 2009, 5:22 AM CT

West coast areas most affected by humans

Climate change, fishing, and commercial shipping top the list of threats to the ocean off the West Coast of the United States.

"Every single spot of the ocean along the West Coast," said Ben Halpern, a marine ecologist at the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California, Santa Barbara, "is affected by 10 to 15 different human activities annually".

In a two-year study to document the way humans are affecting the oceans in this region, Halpern and his colleagues overlaid data on the location and intensity of 25 human-derived sources of ecological stress, including climate change, commercial and recreational fishing, land-based sources of pollution, and ocean-based commercial activities.

With the information, they produced a composite map of the status of West Coast marine ecosystems.

The work was published online today in the journal Conservation Letters, and was conducted at NCEAS. NCEAS is primarily funded by NSF's Division of Environmental Biology.

"This important analysis of the geography and magnitude of land-based stressors should help focus attention on the hot-spots where coordinated management of land and ocean activities is needed," said Phillip Taylor, section head in NSF's Division of Ocean Sciences......... Posted by: Tyler      Read more         Source

May 7, 2009, 10:16 PM CT

Cutting cattle methane

Beef farmers can breathe easier thanks to University of Alberta scientists who have developed a formula to reduce methane gas in cattle.

By developing equations that balance starch, sugar, cellulose, ash, fat and other elements of feed, a Canada-wide team of researchers has given beef producers the tools to lessen the methane gas their cattle produce by as much as 25 per cent.

"That's good news for the environment," said Stephen Moore, a professor of agricultural, food and nutritional science at the University of Alberta in Canada. "Methane is a greenhouse gas, and in Canada, cattle account for 72 per cent of the total emissions. By identifying factors such as diet or genetics that can reduce emissions, we hope to give beef farmers a way to lessen the environmental footprint of their cattle production and methane reductions in the order of 25 per cent are certainly achievable".

Using information from prior studies, the scientists compiled an extensive database of methane production values measured on cattle and were able to formulate equations to predict how much methane a cow would produce based on diet.

The study was jointly conducted with the universities of Guelph and Manitoba, Agriculture and Agri-Food Canada and the International Atomic Energy Agency in Austria. It published recently in the Journal of Animal Science........ Posted by: Tyler      Read more         Source

May 5, 2009, 5:17 AM CT

Clues for self-cleaning materials

Self-cleaning walls, counter tops, fabrics, even micro-robots that can walk on water -- all those things and more could be closer to reality because of research recently completed by researchers at the University of Nebraska-Lincoln and at Japan's RIKEN institute.

Humans have marveled for millennia at how water beads up and rolls off flowers, caterpillars and some insects, and how insects like water striders are able to walk effortlessly on water. It's a property called super hydrophobia and it's been examined seriously by researchers since at least the 1930s.

"A lot of people study this and engineers particularly like the water strider because it can walk on water," said Xiao Cheng Zeng, Ameritas university professor of chemistry at UNL. "Their legs are super hydrophobic and each leg can hold about 15 times their weight. 'Hydrophobic' means water really doesn't like their legs and that's what keeps them on top. A lot of researchers and engineers want to develop surfaces that mimic this from nature".

In a paper to be reported in the May 4-8 online edition of the Proceedings of the National Academy of Sciences, Zeng and his Japanese colleagues, Takahiro Koishi of the University of Fukui and RIKEN, Kenji Yasuoka of Keio University, and Shigenori Fujikawa and Toshikazu Ebisuzaki of RIKEN, give engineers and materials researchers important clues in how to develop the long-sought super hydrophobic materials......... Posted by: Kevin      Read more         Source

May 5, 2009, 5:14 AM CT

Particles, molecules prefer not to mix

In the world of small things, shape, order and orientation are surprisingly important, as per findings from a newly released study by chemists at Washington University in St. Louis.

Lev Gelb, WUSTL associate professor of chemistry, his graduate student Brian Barnes, and postdoctoral researcher Daniel Siderius, used computer simulations to study a very simple model of molecules on surfaces, which looks a lot like the computer game "Tetris." They have observed that the shapes in this model (and in the game) do many surprising things.

"First, different shapes don't mix very well with each other; each shape prefers to associate with others of the same kind," Gelb says. "When you put a lot of different shapes together, they separate from each other on microscopic scales, forming little clusters of nearly pure fluids. This is true even for the mirror-image shapes.

"Second, the structures of the pure (single-shape) fluids are quite complex and not what we might have predicted. There is a very strong tendency for some of the shapes, like rods and S- and Z- shapes, to align in the same direction. Finally, how `different looking' the shapes are isn't a good predictor for how well they mix; it turns out that the hard-to-predict characteristic structures of the fluids are more important than the shapes themselves, in this regard."........ Posted by: Kevin      Read more         Source

May 4, 2009, 5:16 AM CT

Nanotechnology holds promise

Yale scientists describe a breakthrough in safe and effective administration of potential antiviral drugs small interfering RNA (siRNA) molecules that silence genes the first step in development of a new kind of therapy for sexually transmitted diseases (STDs). The work is reported May 4 as an advance online publication of Nature Materials

"RNA interference is a promising approach for prevention and therapy of human disease," said main author Kim Woodrow, Yale postdoctoral fellow in Yale's School of Engineering & Applied Science. "We wanted to develop a new strategy of delivering siRNAs with a FDA-approved material".

As their name suggests, siRNAs interfere and knock out the function of genes in higher organism as well as in microbes that may cause STDs. The scientists designed siRNAs to target a gene expressed widely in the lining of the female mouse reproductive tract, in this proof-of-principle work.

Using densely-loaded nanoparticles made of a biodegradable polymer known as PLGA, the scientists created a stable "time release" vehicle for delivery of siRNAs to sensitive mucosal tissue like that of the female reproductive system.

They observed that the particles, loaded with the drug agent, moved effectively in two important ways, penetrating to reach cells below the surface of the mucosa and distributing throughout the vaginal, cervical, and uterine regions. Furthermore, the siRNAs stayed in the tissues for at least a week and knockdown of gene activity lasted up to 14 days......... Posted by: Kevin      Read more         Source

May 1, 2009, 5:22 AM CT

Glacial Advances

The vast majority of the world's glaciers are retreating as the planet gets warmer. But a few, including glaciers south of the equator in South America and New Zealand, are inching forward.

A paper in this week's issue of the journal Science puts this enigma in perspective; for the last 7,000 years, New Zealand's largest glaciers have often moved out of step with glaciers in the Northern Hemisphere, pointing to strong regional variations in climate.

"This research should provide much more accurate reconstructions of glacial advances worldwide, allowing us in turn to make climate models more accurate," said Paul Filmer, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research.

Conventional wisdom holds that during the era of human civilization, climate has been relatively stable. The newly released study is the latest to challenge this view, by showing that New Zealand's glaciers have gone through rapid periods of growth and decline during the current interglacial period known as the Holocene.

"New Zealand's mountain glaciers have fluctuated frequently over the last 7,000 years, and glacial advances have become slightly smaller through time," said Joerg Schaefer, main author of the paper and a geochemist at Columbia University's Lamont-Doherty Earth Observatory......... Posted by: Tyler      Read more         Source

April 30, 2009, 5:50 PM CT

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April 29, 2009, 5:16 AM CT

Match between molecular, fossil data

During a seminar at another institution several years ago, University of Chicago paleontologist David Jablonski fielded a hostile question: Why bother classifying organisms as per their physical appearance, let alone analyze their evolutionary dynamics, when molecular techniques had already invalidated that approach?

With more than a few heads in the audience nodding their agreement, Jablonski, the William Kenan Jr. Professor in Geophysical Sciences, saw more work to be done. The question launched him on a rigorous study that has culminated in a new approach to reconciling the conflict between fossil and molecular data in evolutionary studies.

For more than two decades, debate has waxed and waned between biologists and paleontologists about the reliability of their different methods. Until now, attention has focused on the dramatically different evolutionary history of certain lineages as determined by fossils or by genetics.

Researchers using molecular techniques assert that genetics more accurately determines evolutionary relationships than does a comparison of physical characteristics preserved in fossils. But how inaccurate, really, were the fossils? Jablonski and the University of Michigan's John A. Finarelli have published the first quantitative evaluation of these assumed discrepancies in the Proceedings of the National Academy of Sciences........ Posted by: William      Read more         Source

April 29, 2009, 5:14 AM CT

Discovery of early African mammal fossils

A limestone countertop, a practiced eye and Google Earth all played roles in the discovery of a trove of fossils that may shed light on the origins of African wildlife.

The circuitous and serendipitous story, featuring University of Michigan paleontologists Philip Gingerich, Gregg Gunnell and Bill Sanders, is the subject of a segment on the award-winning television series "Wild Chronicles," currently airing on public television stations (Episode 412-Looking Back; check listings for local air dates). "Wild Chronicles" is produced by National Geographic Television and presented by WLIW21 in association with WNET.ORG.

The saga began when Gingerich, an authority on ancient whales, learned of a whale fossil from Egypt that had been discovered in a most unconventional way. At a stonecutting yard in Italy where blocks of stone from around the world are sliced up for countertops, masons had noticed what looked like cross-sections of a skeleton in slabs cut from a huge hunk of limestone imported from Egypt. Paleontologist Giovanni Bianucci of the University of Pisa recognized these as fossilized remains of a whale that lived in Egypt 40 million years ago, when the region was covered by ocean.

His curiosity piqued by the discovery, Gingerich wanted to visit the site where the limestone was quarried, but the exact location was something of a mystery. Bianucci had reported that the countertop whale came from a site near the Egyptian city of Sheikh Fadl, but a colleague in Egypt told Gingerich the quarry was probably farther east-exactly where, he wasn't sure......... Posted by: William      Read more         Source

April 29, 2009, 5:04 AM CT

'Chevrons' are not evidence of megatsunamis

A persistent school of thought in recent years has held that so-called "chevrons," large U- or V-shaped formations found in some of the world's coastal areas, are evidence of megatsunamis caused by asteroids or comets slamming into the ocean.

University of Washington geologist and tsunami expert Jody Bourgeois has a simple response: Nonsense.

The term "chevron" was introduced to describe large dunes shaped something like the stripes you might see on a soldier's uniform that are hundreds of meters to a kilometer in size and were originally found in Egypt and the Bahamas.

But the discovery of similar forms in Australia and Madagascar led some researchers to theorize that they were, in fact, deposits left by huge tsunami waves, perhaps 10 times larger than the devastating Indian Ocean tsunami of December 2005.

Such huge waves, they suggest, would result from the giant splash of an asteroid or comet hitting the ocean. They also suggest one such impact occurred 4,800 to 5,000 years ago, and that chevrons in Australia and Madagascar point to its location in the Indian Ocean.

But Bourgeois said the theory just doesn't hold water.

For example, she said, there are numerous chevrons on Madagascar, but a number of are parallel to the coastline. Models created by Bourgeois' colleague Robert Weiss show that if they were created by tsunamis they should point in the direction the waves were travelling, mostly perpendicular to the shore......... Posted by: Tyler      Read more         Source