Monday, June 15, 2009

SCIENTISTS RETURN FROM EXPEDITION TO DRILL BENEATH FROZEN RUSSIAN LAKE

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A team of scientists from the United States, Germany, Russia and Austria has just returned from a six-month drilling expedition to a frozen lake in Siberia: Lake El'gygytgyn, "Lake E" for short.

Lake E was created 3.6 million years ago when a meteor more than a half-mile wide hit Earth and formed an 11-mile wide crater.

There, the researchers collected the longest sediment core samples retrieved in the Arctic region. Information contained in the cores, say the scientists, is of unprecedented significance for understanding climate change in the Arctic.

With respect to time in Earth's history, the cores collected from three holes drilled under the frozen Lake E are more than 30 times longer than cores from the Greenland Ice Sheet, according to geoscientist Julie Brigham-Grette of the University of Massachusetts at Amherst, the lead U.S. scientist on the project.

The research team will compare this Arctic record with oceanic and land-based records from lower latitudes to better understand global climate change.

Nearly 3.5 tons of temperature-controlled sediment cores are being flown by special cargo plane from Siberia to St. Petersburg in early June, then on to a lab in Germany to begin analysis by paleoclimatologists.

Archived core halves will arrive later at the University of Minnesota's LacCore facility, where they will be preserved in cold storage.

Brigham-Grette says the team recovered a total of 1,165 feet of sediments; the sediment record collected extends back roughly 3.5 million years.

"Studying high-latitude systems is of great importance to an understanding of Earth's climate at all latitudes," says Paul Filmer, program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which co-funded the expedition to Lake E with NSF's Office of Polar Programs. "Of primary interest is determining why and how the Arctic evolved from a warm forested ecosystem to a cold permafrost ecosystem between two and three million years ago."

The continuous record collected in this unique lake "offers us a way to look at the glacial/interglacial climate change of the past," Brigham-Grette says.

"Earth's warm and cold cycles over the past one million years varied every 100,000 years at times. Before that, however, climate change, especially in high latitudes, varied over 41,000- and 23,000-year cycles. The record from Lake E will show the ramp up to that type of change in the Earth's climate."

Below the lake's sediments, cores drilled into bedrock will offer geologists a rare opportunity to study meteor impact melt rocks from one of the best preserved large meteor impact craters on Earth, and the only one formed in silicon-rich volcanic rock.

The team recovered roughly 40 meters (131 feet) of the earliest history of the lake in the warm middle Pliocene. This geologic time interval is fascinating, says Brigham-Grette, as a possible analog for future climate.

Initial results from the drilling are still limited.

The sediment cores could not opened in the field because of the remoteness of the drilling site, and rough transportation overland.

During pilot coring in November, the scientists recovered 141 meters (462 feet) of sediments showing alluvial fan and lake deposits in permafrost at the western edge of the lake outside the talik (unfrozen ground in an area of permafrost).

After drilling, the borehole was permanently instrumented for future ground temperature monitoring as part of the Global Terrestrial Network for Permafrost.


PEOPLE WHO WEAR ROSE-COLOURED GLASSES SEE MORE

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A University of Toronto study provides the first direct evidence that our mood literally changes the way our visual system filters our perceptual experience suggesting that seeing the world through rose-coloured glasses is more biological reality than metaphor.

“Good and bad moods literally change the way our visual cortex operates and how we see,” says Adam Anderson, a U of T professor of psychology. “Specifically our study shows that when in a positive mood, our visual cortex takes in more information, while negative moods result in tunnel vision. The study appears tomorrow in the Journal of Neuroscience.

The U of T team used functional magnetic resonance imaging to examine how our visual cortex processes sensory information when in good, bad, and neutral moods. They found that donning the rose-coloured glasses of a good mood is less about the colour and more about the expansiveness of the view.

The researchers first showed subjects a series images designed to generate a good, bad or neutral mood. Subjects were then shown a composite image, featuring a face in the centre, surrounded by “place” images, such as a house. To focus their attention on the central image, subjects were asked to identify the gender of the person’s face. When in a bad mood, the subjects did not process the images of places in the surrounding background. However, when viewing the same images in a good mood, they actually took in more information — they saw the central image of the face as well as the surrounding pictures of houses. The discovery came from looking at specific parts of the brain — the parahippocampal “place area” — that are known to process places and how this area relates to primary visual cortical responses, the first part of the cortex related to vision. Images from the experiment are at the Affect & Cognition Lab website.

“Under positive moods, people may process a greater number of objects in their environment, which sounds like a good thing, but it also can result in distraction,” says Taylor Schmitz, a graduate student of Anderson’s and lead author of the study. “Good moods enhance the literal size of the window through which we see the world. The upside of this is that we can see things from a more global, or integrative perspective. The downside is that this can lead to distraction on critical tasks that require narrow focus, such as operating dangerous machinery or airport screening of passenger baggage. Bad moods, on the other hand, may keep us more narrowly focused, preventing us from integrating information outside of our direct attentional focus.”


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