Wednesday, September 9, 2009


0 comentarios

When it comes to potential mates, women may be as complicated as men claim they are, according to psychologists.

"We have found that women evaluate facial attractiveness on two levels -- a sexual level, based on specific facial features like the jawbone, cheekbone and lips, and a nonsexual level based on overall aesthetics," said Robert G. Franklin, graduate student in psychology working with Reginald Adams, assistant professor of psychology and neurology, Penn State. "At the most basic sexual level, attractiveness represents a quality that should increase reproductive potential, like fertility or health."

On the nonsexual side, attractiveness can be perceived on the whole, where brains judge beauty based on the sum of the parts they see.

"But up until now, this (dual-process) concept had not been tested," Franklin explained. The researchers report the findings of their tests in the current issue of the Journal of Experimental Social Psychology.

To study how women use these methods of determining facial attractiveness, the psychologists showed fifty heterosexual female college students a variety of male and female faces. They asked the participants to rate what they saw as both hypothetical dates and hypothetical lab partners on a scale of one to seven. The first question was designed to invoke a sexual basis of determining attractiveness, while the second was geared to an aesthetic one. This part of the experiment served as a baseline for next phase.

The psychologists then presented the same faces to another set of fifty heterosexual female students. Some of these faces, however, were split horizontally, with the upper and lower halves shifted in opposite directions. The scientists asked these participants to rate the overall attractiveness of the split and whole faces on the same scale.

By dividing the faces in half and disrupting the test subjects' total facial processing, the researchers believed that women would rely more on specific facial features to determine attractiveness. They thought that this sexual route would come into play particularly when the participants saw faces that were suited as hypothetical dates rather than lab partners. The study showed exactly that.

"The whole face ratings of the second group correlated better with the nonsexual 'lab partner' ratings of the first group." Franklin said. With the faces intact, the participants could evaluate them on an overall, nonsexual level.

"The split face ratings of the second group also correlated with the nonsexual ratings of the first group when the participants were looking at female faces," he added. "The only change occurred when we showed the second group split, male faces. These ratings correlated better with the 'hypothetical date' ratings of the first group."

The bottom line is that, at a statistically significant level, splitting the faces in half made the women rely on a purely sexual strategy of processing male faces. The study verifies that these two ways of assessing facial appeal exist and can be separated for women.

"We do not know whether attractiveness is a cultural effect or just how our brains process this information," Franklin admitted. "In the future, we plan to study how cultural differences in our participants play a role in how they rate these faces. We also want to see how hormonal changes women experience at different stages in the menstrual cycle affect how they evaluate attractiveness on these two levels."

Researchers have long known that women's biological routes of sexual attraction derive from an instinctive reproductive desire, relying on estrogen and related hormones to regulate them. The overall aesthetic approach is a less reward-based function, driven by progesterone.

How this complex network of hormones interacts and is channeled through the conscious brain and the human culture that shapes it is a mystery.

"It is a complicated picture," Franklin added. "We are trying to find what features in the brain are at play, here."

(Photo: Robert G. Franklin, Penn State)


0 comentarios
A smaller scale, economically efficient nuclear reactor that could be mass-assembled in factories and supply power for a medium-size city or military base has been designed by Sandia National Laboratories.

The exportable, proliferation-resistant “right-sized reactor” was conceived by a Sandia research team led by Tom Sanders.

Sanders has been collaborating with numerous Sandians on advancing the small reactor concept to an integrated design that incorporates intrinsic safeguards, security and safety. This opens the way for possible exportation of the reactor to developing countries that do not have the infrastructure to support large power sources. The smaller reactor design decreases the potential need for countries to develop an advanced nuclear regulatory framework.

Incorporated into the design, said team member Gary Rochau, is what is referred to as “nuke-star,” an integrated monitoring system that provides the exporters of such technologies a means of assuring the safe, secure, and legitimate use of nuclear technology.

“This small reactor would produce somewhere in the range of 100 to 300 megawatts of thermal power and could supply energy to remote areas and developing countries at lower costs and with a manufacturing turnaround period of two years as opposed to seven for its larger relatives,” Sanders said. “It could also be a more practical means to implement nuclear base load capacity comparable to natural gas-fired generating stations and with more manageable financial demands than a conventional power plant.”

About the size of half a fairly large office building, a right-sized reactor facility will be considerably smaller than conventional nuclear power plants in the U.S. that typically produce 3,000 megawatts of power.

With approximately 85 percent of the design efforts completed for the reactor core, Sanders and his team are seeking an industry partner through a cooperative research and development agreement (CRADA). The CRADA team will be able to complete the reactor design and enhance the plant side, which is responsible for turning the steam into electricity.

Team member Steve Wright is doing research using internal Sandia Laboratory Directed Research and Development (LDRD) program funding. The right-sized reactor is expected to operate at efficiencies greater than any current designs, ultimately giving the reactor the greatest return on investment.

“In the past, concerns over nuclear proliferation and waste stymied and eventually brought to a halt nuclear energy R&D in the United States and caused constraints on U.S. supply industries that eventually forced them offshore,” Sanders said. “Today the prospects of nuclear proliferation, terrorism, global warming and environmental degradation have resulted in growing recognition that a U.S.-led nuclear power enterprise can prevent proliferation while providing a green source of energy to a developing country.”

Sanders said developing countries around the world have notified the International Atomic Energy Agency (IAEA) of their intent to enter the nuclear playing field. This technology will provide a large, ready market for properly scaled, affordable power systems. The right-sized nuclear power system is poised to have the right combination of features to meet export requirements, cost considerations and waste concerns.

The reactor system is built around a small uranium core, submerged in a tank of liquid sodium. The liquid sodium is piped through the core to carry the heat away to a heat exchanger also submerged in the tank of sodium. In the Sandia system, the reactor heat is transferred to a very efficient supercritical CO2 turbine to produce electricity.

These smaller reactors would be factory built and mass-assembled, with potential production of 50 a year. They all would have the exact same design, allowing for quick licensing and deployment. Mass production will keep the costs down, possibly to as low as $250 million per unit. Just as Henry Ford revolutionized the automobile industry with mass production of automobiles via an assembly line, the team’s concept would revolutionize the current nuclear industry, Sanders said.

Because the right-sized reactors are breeder reactors — meaning they generate their own fuel as they operate — they are designed to have an extended operational life and only need to be refueled once every couple of decades, which helps alleviate proliferation concerns. The reactor core is replaced as a unit and “in effect is a cartridge core for which any intrusion attempt is easily monitored and detected,” Sanders said. The reactor system has no need for fuel handling. Conventional nuclear power plants in the U.S. have their reactors refueled once every 18 months.

Sanders said much of the reactor technology needed for the smaller fission machines has been demonstrated through 50 years of operating experimental breeder reactors in Idaho. In addition, he said, Sandia is one of a handful of research facilities that has the capability to put together a project of this magnitude. The project would tap into the Labs’ expertise in complex systems engineering involving high performance computing systems for advanced modeling and simulation, advanced manufacturing, robotics and sensors as well as its experience in moving from research to development to deployment.

“Sandia operates one of three nuclear reactors and the only fuel-critical test facility remaining in the DOE complex,” Sanders said. “It is the nation’s lead laboratory for the development of all radiation-hardened semiconductor components as well as the lead lab for testing these components in extreme radiation environments.”

The goal of the right-sized reactors is to produce electricity at less than five cents per kilowatt hour, making them economically comparable to gas turbine systems.

Sanders said the smaller reactors will probably be built initially to provide power to military bases, both in the U.S. and outside the country.

Sandia National Laboratories


0 comentarios

New research by scientists at UC Santa Barbara indicates a possible Antarctic location for ice that seemed to be missing at a key point in climate history 34 million years ago. The research, which has important implications for climate change, is described in a paper published in Geophysical Research Letters, a journal of the American Geophysical Union.

"Using data from prior geological studies, we have constructed a model for the topography of West Antarctic bedrock at the time of the start of the global climate transition from warm ‘greenhouse' earth to the current cool ‘icehouse' earth some 34 million years ago," explained Douglas S. Wilson, first author and an associate research geophysicist with UCSB's Department of Earth Science and Marine Science Institute.

Wilson and his co-author, Bruce Luyendyk, a professor in the Department of Earth Science, discovered that, contrary to most current models for bedrock elevations of West Antarctica, the bedrock in the past was of much higher elevation and covered a much larger area than today. Current models assume that an archipelago of large islands existed under the ice at the start of the climate transition, similar to today, but Wilson and Luyendyk found that does not fit their new model. In fact, the authors state that the land area above sea level of West Antarctica was about 25 percent greater in the past.

The existing theory leaves West Antarctica in a minor role in terms of the ice accumulation beginning 34 million years ago. Ice sheet growth on earth is believed to have developed on the higher and larger East Antarctic subcontinent while West Antarctica joined the process later around 14 million years ago. "But a problem exists with leaving West Antarctica out of the early ice history," said Wilson. "From other evidence, it is believed that the amount of ice that grew on earth at the 34 million year climate transition was too large to be accounted for by formation on East Antarctica alone, the most obvious location for ice sheet growth. Another site is needed to host the extra missing ice."

Evidence for that large mass of ice comes from two sources: the chemical and isotopic composition in shell material of marine microfossils, which are sensitive to ocean temperatures and the amount of ice on land; and from geologic records of lowered sea level at the time that indicate how much ice formed on land to produce the sea level drop.

The new study, by showing that West Antarctica had a higher elevation 34 million years ago than previously thought, reveals a possible site for the accumulation of the early ice that is unaccounted for. "Preliminary climate modeling by researchers at Pennsylvania State University demonstrates that this new model of higher elevation West Antarctica bedrock topography can indeed host the missing ice," said Luyendyk. "Our results, therefore, have opened up a new paradigm for the history of the growth of the great global ice sheets. Both East and West Antarctica hosted the growing ice."

The new hypothesis may solve another conflict among climate scientists. Given that more ice grew than could be hosted on East Antarctica alone, some researchers have proposed that the missing ice formed in the northern hemisphere. This would have been many millions of years before the well-known documentation of ice growth there, which started about three million years ago; evidence for ice sheets in the northern hemisphere prior to that time is not established. The new bedrock model shows it is not necessary to have ice hosted in the northern polar regions at the start of global climate transition; West Antarctica could have accommodated the extra ice.

(Photo: UCSB)




Selected Science News. Copyright 2008 All Rights Reserved Revolution Two Church theme by Brian Gardner Converted into Blogger Template by Bloganol dot com