November 13, 2009, 8:21 AM CT

Record High Temperatures Far Outpace Record Lows

Spurred by a warming climate, daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States, new research shows. The ratio of record highs to lows is likely to increase dramatically in coming decades if emissions of greenhouse gases continue to climb.

"Climate change is making itself felt in terms of day-to-day weather in the United States," says Gerald Meehl, the main author and a senior scientist at the National Center for Atmospheric Research (NCAR). "The ways these records are being broken show how our climate is already shifting".

The study, by authors at NCAR, Climate Central, The Weather Channel, and the National Oceanic and Atmospheric Administration (NOAA), has been accepted for publication in Geophysical Research Letters. It was funded by the National Science Foundation, NCAR's sponsor, the Department of Energy, and Climate Central.

If temperatures were not warming, the number of record daily highs and lows being set each year would be approximately even. Instead, for the period from January 1, 2000, to September 30, 2009, the continental United States set 291,237 record highs and 142,420 record lows, as the country experienced uncommonly mild winter weather and intense summer heat waves......... Posted by: Beverly      Read more         Source

November 11, 2009, 8:10 AM CT

Smaller transistors and more powerful chips

Purdue University scientists progress in developing a new type of transistor that uses a finlike structure instead of the conventional flat design, possibly enabling engineers to create faster and more compact circuits and computer chips.

The fins are made not of silicon, like conventional transistors, but from a material called indium-gallium-arsenide. Called finFETs, for fin field-effect-transistors, scientists from around the world have been working to perfect the devices as potential replacements for conventional transistors.

In work led by Peide Ye, an associate professor of electrical and computer engineering, the Purdue scientists are the first to create finFETs using a technology called atomic layer deposition. Because atomic layer deposition is usually used in industry, the new finFET technique may represent a practical solution to the coming limits of conventional silicon transistors.

"We have just demonstrated the proof of concept here," Ye said.

Findings are detailed in three research papers being presented during the International Electron Devices Meeting on Dec. 7-9 in Baltimore. The work is led by doctoral student Yanqing Wu, who provided major contributions for two of the papers.

The finFETs might enable engineers to sidestep a problem threatening to derail the electronics industry. New technologies will be needed for industry to keep pace with Moore's law, an unofficial rule stating that the number of transistors on a computer chip doubles about every 18 months, resulting in rapid progress in computers and telecommunications. Doubling the number of devices that can fit on a computer chip translates into a similar increase in performance. However, it is becoming increasingly difficult to continue shrinking electronic devices made of conventional silicon-based semiconductors......... Posted by: Beverly      Read more         Source

October 7, 2009, 7:15 AM CT

How dinosaurs coped with slippery slopes

A new investigation of a fossilized tracksite in southern Africa shows how early dinosaurs made on-the-fly adjustments to their movements to cope with slippery and sloping terrain. Differences in how early dinosaurs made these adjustments provide insight into the later evolution of the group.

This research, which was conducted by scientists at the University of Michigan, Argentina's Universidad de Buenos Aires, and the Iziko South African Museum in Cape Town, South Africa, will be published online Oct. 6 in the open-access journal PLoS ONE

The Moyeni tracksite in Lesotho contains more than 250 footprints made by a variety of four-legged animals near the beginning of the Jurassic Period (about 200 million years ago), when the Earth's landmasses were united as Pangea. The site was first discovered and described in the 1960s and 1970s by French paleontologist Paul Ellenberger but has not since been examined in detail. In their re-analysis of the fossil tracksite, the scientists created a high-resolution map of trackway surface using a combination of traditional mapping techniques and a 3D surface scanner, which recorded millimeter-scale detail. The digital record of the site will serve as an archive and will be the source of future research, said U-M's Jeffrey Wilson, an assistant professor in the Department of Geological Sciences and an assistant curator in the Museum of Paleontology......... Posted by: Beverly      Read more         Source

September 29, 2009, 10:29 PM CT

North Meets South?

Results of a newly released study add evidence that climate swings in the northern hemisphere over the past 12,000 years have been tightly associated with changes in the tropics.

The findings, published this week in the journal Science, suggest that a prolonged cold spell that caused glaciers in Europe and North America to creep forward several hundred years ago may have affected climate patterns as far south as Peru, causing tropical glaciers there to expand, too.

Glaciers in both the tropics and North Atlantic region reached their most recent maximum extents during the so-called Little Ice Age, about 1650 AD to 1850 AD, as per the researchers conducting the research.

To make the discovery, they employed a cutting-edge technique for dating glacial deposits.

"The results bring us one step closer to understanding global-scale patterns of glacier activity and climate during the Little Ice Age," says main author Joe Licciardi, a glacial geologist at the University of New Hampshire.

By understanding how glaciers behaved in the past, the georesearchers hope to predict how parts of the world will react as the planet warms.

Human civilization arose during fairly stable temperatures since the end of the last ice age, about 12,000 years ago. But research shows that even during this time glaciers fluctuated in large and sometimes surprising ways......... Posted by: Beverly      Read more         Source

September 23, 2009, 7:11 AM CT

Single molecules in microdroplets

Inventing a useful new tool for creating chemical reactions between single molecules, researchers at the National Institute of Standards and Technology (NIST) have employed microfluidicsthe manipulation of fluids at the microscopic scaleto make microdroplets that contain single molecules of interest. By combining this new microfluidic "droplet-on-demand" method with "optical tweezers" that could merge multiple droplets and cause their molecular contents to react, the research may ultimately lead to a compact, integrated setup for obtaining single-molecule information on the structure and function of important organic materials, such as proteins, enzymes, and DNA.

With the aid of NIST's Center for Nanoscale Science and Technology, physicists Carlos Lpez-Mariscal and Kristian Helmerson created a tiny microfluidic device with a channel through which water can flow. Squeezed into a narrow stream by a mixture of oils whose viscosity, or resistance to flow, exerts pressure on it, the water then enters a narrow constriction. The water's abrupt pressure dropaccompanied by a dash of detergentbreaks its surface tension, splitting it into small droplets. (This same effect occurs when a thin stream of water falling from a faucet breaks up into small drops.).

The droplet sizes are highly uniform and can be tuned by adjusting the width of the constriction. With this technique, the scientists made droplets about a micrometer in diameteror half an attoliter (half a billionth of a billionth of a liter) in volume......... Posted by: Beverly      Read more         Source

Wed, 16 Sep 2009 03:56:06 GMT

LG releases XD3 minimalist, portable HDDs

It seems LG has sent out its portable HDDs for a facelift and ended up with a luscious makeover - the XD3 slim, portable HDDs announced for the Korean market.

And the results are appreciable in a single glance - a high-quality, brushed aluminum casing that comes in four colors (red, gold, black and silver) and with rubber padding for shock absorption, plus an enviable 13mm thickness. While it comes to specs under the hood however, there aren"t many to make you blush - as with earlier storage drives from LG (XD1 and XD2), the XD3 is available in capacities of 320GB and 500GB, with the same USB and SATA II connectivity. It retails in Korea at a price of 110,000 Won (US $90).

Via Engadget. Posted by: Sarah      Read more     Source

September 15, 2009, 2:39 PM CT

An uncertain future for forests

The composition of some of our nation's forests may be quite different 200 to 400 years from today according to a recent study at the University of Illinois. The study found that temperature and photosynthetic active radiation were the two most important variables in predicting what forest landscapes may look like in the future. The uncertainties became very high after the year 2200.

Approximately 100,000 acres of forested area west of Lake Superior which make up the Boundary Waters Canoe Area was used for the study. Using computer models PnET-II and LANDIS-II, the researchers were able to simulate 209 possible scenarios, including 13 tree species and 27 possible climate profiles to predict how the landscape will look over time.

"The tools that we developed and we're using for the research project can be applied to any discipline dealing with risk and uncertainty in decision making," said U of I researcher George Gertner.

"We were dealing with the uncertainties in global change predictions using the projections established by the United Nations Intergovernmental Panel of Climate Change. These projections were based on different CO 2 reduction scenarios and global circulation models. ".

The study found that the most important source of uncertainty in the forest composition prediction is from the uncertainty in temperature predictions. The second most important source is photosynthetic active radiation, the third is carbon dioxide, and the fourth is precipitation......... Posted by: Beverly      Read more         Source

September 11, 2009, 7:35 AM CT

Carbon nanotubes could make efficient solar cells

Using a carbon nanotube instead of traditional silicon, Cornell scientists have created the basic elements of a solar cell that hopefully will lead to much more efficient ways of converting light to electricity than now used in calculators and on rooftops.

The scientists fabricated, tested and measured a simple solar cell called a photodiode, formed from an individual carbon nanotube. Reported online Sept. 11 in the journal Science, the scientists -- led by Paul McEuen, the Goldwin Smith Professor of Physics, and Jiwoong Park, assistant professor of chemistry and chemical biology -- describe how their device converts light to electricity in an extremely efficient process that multiplies the amount of electrical current that flows. This process could prove important for next-generation high efficiency solar cells, the scientists say.

"We are not only looking at a new material, but we actually put it into an application -- a true solar cell device," said first author Nathan Gabor, a graduate student in McEuen's lab.

The scientists used a single-walled carbon nanotube, which is essentially a rolled-up sheet of graphene, to create their solar cell. About the size of a DNA molecule, the nanotube was wired between two electrical contacts and close to two electrical gates, one negatively and one positively charged. Their work was inspired in part by prior research in which researchers created a diode, which is a simple transistor that allows current to flow in only one direction, using a single-walled nanotube. The Cornell team wanted to see what would happen if they built something similar, but this time shined light on it......... Posted by: Beverly      Read more         Source

August 26, 2009, 11:01 PM CT

Hankering for molecular electronics?

The sandwich recipe recently concocted by researchers working at the National Institute of Standards and Technology (NIST) may prove tasty for computer chip designers, who have long had an appetite for molecule-sized electronic components but no clear way to satisfy it until now.

The research team, which includes collaborators from the University of Maryland, has found a simple method of sandwiching organic molecules between silicon and metal, two materials fundamental to electronic components. By doing so, the team may have overcome one of the principal obstacles in creating switches made from individual molecules, which represent perhaps the ultimate in miniaturization for the electronics industry.

The idea of using molecules as switches has been around for years, carrying the promise of components that can be produced cheaply in huge numbers, perform faster as a group than their larger silicon brethren, and use only a tiny fraction of their energy. But eventhough there has been progress in creating the switching molecules themselves, the overall concept has been stuck on drawing boards in large part because organic molecules are delicate and tend to be damaged irreparably when subjected to one especially stressful step in the chip-building process: attaching them to electrical contacts......... Posted by: Beverly      Read more         Source

August 20, 2009, 6:42 AM CT

Increased climate volatility expected to worsen poverty

A newly released study supported by the World Bank has for the first time tried to combine, understand and predict the effects of climate change on food prices and wages in developing countries to assess how badly different socio-economic strata in sixteen vulnerable countries will be hit by extreme weather conditions, linked to climate change such as annual-scale hot, dry and wet extremes.

Using the same methodology for climate prediction as the International Panel on Climate Change and data from the Food and Agriculture Organization of the United Nations, the report, published in IOP Publishing's Environmental Research Letters today, Thursday, 20 August, is a crucial stepping stone in the fight to help those most at risk. Find the report http://stacks.iop.org/ERL/4/034004 from Thursday.

The paper, 'Climate volatility deepens poverty vulnerability in developing countries', written by scientists from the Development Research Group at the World Bank and climate scientists at Purdue University in Indiana, US, explains why extreme exposure to food price increases for the urban poor in countries such as Bangladesh, Mexico, Mozambique, Malawi, Tanzania and Zambia, suggest that it is the urban poor who will be hardest hit and enter most rapidly in to poverty as the climate changes throughout this century......... Posted by: Beverly      Read more         Source