Sun, 28 Oct 2007 03:27:35 GMT

Unidentified Moss

Apparently, identifying the species of moss residing on top of a rock in the middle of a river is quite difficult. I put in a call to one of the local moss experts explaining my photograph, naively thinking that there can't be that many species of mosses living on stream-rocks. It turns out that there can be that many. Similar to terrestrial species of moss, a good macro photograph with fruiting structures (or even better, a specimen in hand) is required to take a stab at identification.

This photograph was taken in-camera and processed a bit less than I normally do. The effect of the water is due to a specialized glass filter and long exposure. Posted by: Daniel Mosquin      Read more     Source

October 26, 2007, 5:15 AM CT

'Nervous' birds take more risks

Researchers have shown that birds with higher stress levels adopt bolder behaviour than their normally more relaxed peers in stressful situations. A University of Exeter research team studied zebra finches, which had been selectively bred to produce three distinct types laid-back, normal and stressed based on their levels of stress hormone. The group was surprised to find that the stressed birds were bolder and took more risks in a new environment than the group that was commonly more laid-back. Their findings are published recently (26 October) in the journal Hormones and Behaviour.

Like other animals including humans, birds respond to stress, created by the appearance of a predator or a change in their environment for example, by producing a hormone. In birds, this hormone is called corticosterone and some individuals have higher levels of the hormone than others. The zebra finches in this experiment were bred to have three different corticosterone levels, with the laid-back birds having lower levels than the stressed birds. The scientists put the birds into a new environment, which housed several unfamiliar objects, including new feeders. The stressed birds were the first to visit the new feeders, which they also returned to more quickly than the other birds after being startled. Overall, they approached more objects than their normally more relaxed peers, showing greater risk-taking behaviour and arguably handling the situation better......... Posted by: Ashley      Read more         Source

October 25, 2007, 10:26 PM CT

Some Neanderthals were redheads

Ancient DNA retrieved from the bones of two Neanderthals suggests that at least some of them had red hair and pale skin, researchers report this week in the journal Science. The international team says that Neanderthals' pigmentation may even have been as varied as that of modern humans, and that at least 1 percent of Neanderthals were likely redheads.

The researchers -- led by Holger Rmpler of Harvard University and the University of Leipzig, Carles Lalueza-Fox of the University of Barcelona, and Michael Hofreiter of the Max Planck Institute for Evolutionary Anthropology in Leipzig -- extracted, amplified, and sequenced a pigmentation gene called MC1R from the bones of a 43,000-year-old Neanderthal from El Sidrn, Spain, and a 50,000-year-old individual from Monti Lessini, Italy.

"Together with other genes, this MC1R gene dictates hair and skin color in humans and other mammals," says Rmpler, a postdoctoral researcher working with Hopi E. Hoekstra in Harvard's Department of Organismic and Evolutionary Biology. "The two Neanderthal individuals we studied showed a point mutation not seen in modern humans. When we induced such a mutation in human cells, we observed that it impaired MC1R activity, a condition that leads to red hair and pale skin in modern humans"......... Posted by: William      Read more         Source

October 25, 2007, 10:04 PM CT

How lasers cut flesh

Lasers are at the cutting edge of surgery.

From cosmetic to brain surgery, intense beams of coherent light are gradually replacing the steel scalpel for a number of procedures.

Despite this increasing popularity, there is still a lot that researchers do not know about the ways in which laser light interacts with living tissue. Now, some of these basic questions have been answered in the first investigation of how ultraviolet lasers similar to those used in LASIK eye surgery cut living tissues. It was published online in Physical Review Letters on October 10.

The effect that powerful lasers have on actual flesh varies both with the wavelength, or color, of the light and the duration of the pulses that they produce. The specific wavelengths of light that are absorbed by, reflected from or pass through different types of tissue can vary substantially. Therefore, different types of lasers work best in different medical procedures.

For lasers with pulse lengths of a millionth of a second or less, there are two basic cutting regimes:

• Mid-infrared lasers with long wavelengths cut by burning. That is, they heat up the tissue to the point where the chemical bonds holding it together break down. Because they automatically cauterize the cuts that they make, infrared lasers are used frequently for surgery in areas where there is a lot of bleeding.

........ Posted by: Kevin      Read more         Source

October 25, 2007, 9:59 PM CT

Lakes A Major Source Of Prehistoric Methane

A team of researchers led by a researcher at the University of Alaska Fairbanks has identified a new likely source of a spike in atmospheric methane coming out of the North during the end of the last ice age.

Methane bubbling from arctic lakes could have been responsible for up to 87 percent of that methane spike, said UAF researcher Katey Walter, lead author of a report printed in the Oct. 26 issue of Science magazine. The findings could help researchers understand how current warming might affect atmospheric levels of methane, a gas that is thought to contribute to climate change.

"It tells us that this isn't just something that is ongoing now. It would have been a positive feedback to climate warming then, as it is today," said Walter. "We estimate that as much as 10 times the amount of methane that is currently in the atmosphere will come out of these lakes according tomafrost thaws in the future. The timing of this emission is uncertain, but likely we are talking about a time frame of hundreds to thousands of years, if climate warming continues as projected."

Ice cores from Greenland and Antarctica have shown that during the early Holocene Period--about 14,000 to 11,500 years ago--the levels of methane in the atmosphere rose significantly, Walter said. "They observed that an unidentified northern source (of methane) appeared during that time."........ Posted by: Tyler      Read more         Source

October 25, 2007, 9:54 PM CT

Human Migration From Asia To Americas

Questions about human migration from Asia to the Americas have perplexed anthropologists for decades, but as scenarios about the peopling of the New World come and go, the big questions have remained. Do the ancestors of Native Americans derive from only a small number of "founders" who trekked to the Americas via the Bering land bridge? How did their migration to the New World proceed? What, if anything, did the climate have to do with their migration? And what took them so long?

A team of 21 researchers, led by Ripan Malhi, a geneticist in the department of anthropology at the University of Illinois, has a new set of ideas. One is a striking hypothesis that seems to map the peopling process during the pioneering phase and well beyond, and at the same time show that there was much more genetic diversity in the founder population than was previously thought.

The team's findings are published in a recent issue of the Public Library of Science in an article titled, "Beringian Standstill and Spread of Native American Founders".

"Our phylogeographic analysis of a new mitochondrial genome dataset allows us to draw several conclusions," the authors wrote.

"First, before spreading across the Americas, the ancestral population paused in Beringia long enough for specific mutations to accumulate that separate the New World founder lineages from their Asian sister-clades." (A clade is a group of mitochondrial DNAs (mtDNAs ) that share a recent common ancestor, Malhi said. Sister-clades would include two groups of mtDNAs that each share a recent common ancestor and the common ancestor for each clade is closely related.)......... Posted by: Tyler      Read more         Source

October 24, 2007, 8:32 PM CT

Not just humans benefit from animal biotechnology

Laboratory animals are the source of major discoveries and breakthroughs in biology, not just in tackling disease but also unravelling fundamental molecular processes. Delegates at a recent research conference organised by the European Science Foundation (ESF) and Wellcome Trust heard how technology capable of analysing animal genes across the whole genome is yielding a number of benefits for agriculture and human society.

In breeding both domestic and farm animals for example, it is now possible to select individuals with a wide spectrum of desirable traits in a single generation. In the past selective breeding of animals has been confined to traits that are obvious or easy to measure, and it has been difficult to produce individuals with a broad combination of desirable qualities, as per Helen Sang, chair of the recent ESF/Wellcome conference on Animal Biotechnology.

There is the potential to increase the effectiveness of genetic selection, even for traits that are difficult or take a long time to measure, said Sang from the Roslin Institute Department of Gene Function & Development Edinburgh United Kingdom. The key point here is that it is now possible to identify individual animals for breeding, and select offspring, with the best overall combination of gene variants (alleles) rather than focusing on just one or two traits. Sang is also......... Posted by: Ashley      Read more         Source

October 24, 2007, 7:31 PM CT

First-Known Belt Of Moonlets In Saturn Rings

A narrow belt harboring moonlets as large as football stadiums discovered in Saturn's outermost ring probably resulted when a larger moon was shattered by a wayward asteroid or comet eons ago, as per a University of Colorado at Boulder study.

Images taken by a camera onboard the NASA Cassini spacecraft revealed a series of eight propeller-shaped "wakes" in a thin belt of the outermost "A" ring, indicating the presence of corresponding moonlets, said CU-Boulder Research Associate Miodrag Sremcevic, lead author of the study reported in the Oct. 25 issue of Nature. The propeller wakes highlight tiny areas of the belt where ring material has been perturbed by the gravitational forces caused by individual moonlets, Sremcevic said.

The team calculated that there likely are thousands of moonlets ranging in size from semi-trailers to sports arenas embedded in the "A" ring's thin moonlet belt that circles the planet. At about 2,000 miles across, the belt of moonlets is only about 1/80th the diameter of Saturn's total ring system, which at roughly 155,000 miles across would stretch about two-thirds of the way from Earth to the moon.

"This is the first evidence of a moonlet belt in any of Saturn's rings," said Sremcevic of CU-Boulder's Laboratory for Atmospheric and Space Physics. "We have firmly established these moonlets exist in a relatively narrow region of the "A" ring, and the evidence indicates they are remnants of a larger moon that was shattered by a meteoroid or comet."........ Posted by: Brooke      Read more         Source

October 23, 2007, 10:02 PM CT

Gerhard Ertl wins Nobel Prize in Chemistry

"The Max Planck researcher has succeeded in providing a detailed description of how chemical reactions take place on solid surfaces," said the Swedish Academy of Sciences today in Stockholm in a statement.

The prize, which Ertl does not have to share with any other colleague, is worth roughly 1.1 million euros. "I have the highest regard for Mr Ertl - not only as an outstanding scientist but also as an individual of great integrity, whose commitment to the Max Planck Society has been invaluable", said Peter Gruss, President of the Max Planck Society in Munich on Wednesday. "This award is a special gift for Mr Ertl, who also celebrates his 71st birthday today".

How fuel cells function.

"Gerhard Ertl has laid the foundations for understanding industrial catalysts and catalytic processes", said Ferdi Schüth of the Max Planck Institute for Coal Research, a colleague of the Nobel Prize laureate. "His research helps to explain such varied processes as how fuel cells function and catalysts in automobiles work." This science is important in a number of industrial processes, such as in the production of artificial fertilizers. Surface chemistry can even explain the thinning of the ozone layer.

"I was at a loss for words".

Ertl was overjoyed. "I never expected to win," he said. While he had been aware that he was on the list of candidates, he was nevertheless at a loss for words after hearing that he had won the Nobel Prize. The Prize Committee gave him 20 minutes to collect himself and to get ready for the press. "Now the phones are ringing off the hook". All his staff members gathered outside his office to toast the news with him with a glass of champagne......... Posted by: Sarah      Read more         Source

October 23, 2007, 9:31 PM CT

Gel Changes Color On Demand

MIT scientists have created a new structured gel that can rapidly change color in response to a variety of stimuli, including temperature, pressure, salt concentration and humidity.

Among other applications, the structured gel could be used as a fast and inexpensive chemical sensor, said Edwin Thomas, MIT's Morris Cohen Professor of Materials Science and Engineering. One place where such an environmental sensor could be useful is a food processing plant, where the sensor could indicate whether food that must remain dry has been overly exposed to humidity.

Thomas is senior author of a paper on the work would be reported in the Oct. 21 online edition of Nature Materials.

Structured gels are those that feature an internal pattern such as layers. A critical component of the structured gel developed at MIT is a material that expands or contracts when exposed to certain stimuli. Those changes in the thickness of the gel cause it to change color, through the entire range of the visible spectrum of light.

Objects that reflect different colors depending on which way you look at them already exist, but once those objects are manufactured, their properties can't change. The MIT team set out to create a material that would change color in response to external stimuli......... Posted by: Kevin      Read more         Source