The researchers found evidence that fungi can “lock” depleted uranium into a mineral form that may be less likely to find its way into plants, animals, or the water supply.

“This work provides yet another example of the incredible properties of microorganisms in effecting transformations of metals and minerals in the natural environment,” said Geoffrey Gadd of the University of Dundee in Scotland. “Because fungi are perfectly suited as biogeochemical agents, often dominate the biota in polluted soils, and play a major role in the establishment and survival of plants through their association with roots, fungal-based approaches should not be neglected in remediation attempts for metal-polluted soils.”

The testing of depleted-uranium ammunition and its recent use in Iraq and the Balkans has led to contamination of the environment with the unstable metal, Gadd explained. Depleted uranium differs from natural uranium in the balance of isotopes it contains. It is the byproduct of uranium enrichment for use in nuclear reactors or nuclear weapons and is valued for its very high density. Although less radioactive than natural uranium, depleted uranium is just as toxic and poses a threat to people.

In the new study, the researchers found that free-living and plant symbiotic (mycorrhizal) fungi can colonize depleted-uranium surfaces and transform the metal into uranyl phosphate minerals.

While they probably still pose some threat, he said, “The fungal-produced minerals are capable of long-term uranium retention, so this may help prevent uptake of uranium by plants, animals, and microbes. It might also prevent the spent uranium from leaching out from the soil.”

Gadd said that a combination of environmental and biological factors is involved in the process. First, the unstable uranium metal gets coated with a layer of oxides. Moisture in the environment also “corrodes” the depleted uranium, encouraging fungal colonization and growth. While the fungi grow, they produce acidic substances, which corrode the depleted uranium even further. Some of the substances produced include organic acids that convert the uranium into a form that the fungi can take up or that can interact with other compounds. Ultimately, he said, the interaction of soluble forms of uranium with phosphate leads to the formation of the new uranium minerals that get deposited around the fungal biomass.

“We have shown for the first time that fungi can transform metallic uranium into minerals, which are capable of long-term uranium retention,” the researchers concluded. “This phenomenon could be relevant to the future development of various remediation and revegetation techniques for uranium-polluted soils.”

[Cathleen Genova @ Cell Press]

Berkeley Lab has signed a collaboration agreement with Tensilica, Inc. to explore the use of Tensilica’s Xtensa processor cores as the basic building blocks in a massively parallel system design. Tensilica’s Xtensa processor is about 400 times more efficient in floating point operations per watt than the conventional server processor chip shown here.

In a paper published in the May issue of the International Journal of High Performance Computing Applications, Michael Wehner and Lenny Oliker of Berkeley Lab’s Computational Research Division, and John Shalf of the National Energy Research Scientific Computing Center (NERSC) lay out the benefit of a new class of supercomputers for modeling climate conditions and understanding climate change. Using the embedded microprocessor technology used in cell phones, iPods, toaster ovens and most other modern day electronic conveniences, they propose designing a cost-effective machine for running these models and improving climate predictions.

In April, Berkeley Lab signed a collaboration agreement with Tensilica, Inc. to explore such new design concepts for energy-efficient high-performance scientific computer systems. The joint effort is focused on novel processor and systems architectures using large numbers of small processor cores, connected together with optimized links, and tuned to the requirements of highly-parallel applications such as climate modeling.

Understanding how human activity is changing global climate is one of the great scientific challenges of our time. Scientists have tackled this issue by developing climate models that use the historical data of factors that shape the earth’s climate, such as rainfall, hurricanes, sea surface temperatures and carbon dioxide in the atmosphere. One of the greatest challenges in creating these models, however, is to develop accurate cloud simulations.

Although cloud systems have been included in climate models in the past, they lack the details that could improve the accuracy of climate predictions. Wehner, Oliker and Shalf set out to establish a practical estimate for building a supercomputer capable of creating climate models at 1-kilometer (km) scale. A cloud system model at the 1-km scale would provide rich details that are not available from existing models.

To develop a 1-km cloud model, scientists would need a supercomputer that is 1,000 times more powerful than what is available today, the researchers say. But building a supercomputer powerful enough to tackle this problem is a huge challenge.

Historically, supercomputer makers build larger and more powerful systems by increasing the number of conventional microprocessors — usually the same kinds of microprocessors used to build personal computers. Although feasible for building computers large enough to solve many scientific problems, using this approach to build a system capable of modeling clouds at a 1-km scale would cost about $1 billion. The system also would require 200 megawatts of electricity to operate, enough energy to power a small city of 100,000 residents.

In their paper, Towards Ultra-High Resolution models of Climate and Weather, the researchers present a radical alternative that would cost less to build and require less electricity to operate. They conclude that a supercomputer using about 20 million embedded microprocessors would deliver the results and cost $75 million to construct. This “climate computer” would consume less than 4 megawatts of power and achieve a peak performance of 200 petaflops.

“Without such a paradigm shift, power will ultimately limit the scale and performance of future supercomputing systems, and therefore fail to meet the demanding computational needs of important scientific challenges like the climate modeling,” Shalf said.

The researchers arrive at their findings by extrapolating performance data from the Community Atmospheric Model (CAM). CAM, developed at the National Center for Atmospheric Research in Boulder, Colorado, is a series of global atmosphere models commonly used by weather and climate researchers.

The “climate computer” is not merely a concept. Wehner, Oliker and Shalf, along with researchers from UC Berkeley, are working with scientists from Colorado State University to build a prototype system in order to run a new global atmospheric model developed at Colorado State.

“What we have demonstrated is that in the exascale computing regime, it makes more sense to target machine design for specific applications,” Wehner said. “It will be impractical from a cost and power perspective to build general-purpose machines like today’s supercomputers.”

Under the agreement with Tensilica, the team will use Tensilica’s Xtensa LX extensible processor cores as the basic building blocks in a massively parallel system design. Each processor will dissipate a few hundred milliwatts of power, yet deliver billions of floating point operations per second and be programmable using standard programming languages and tools. This equates to an order-of-magnitude improvement in floating point operations per watt, compared to conventional desktop and server processor chips. The small size and low power of these processors allows tight integration at the chip, board and rack level and scaling to millions of processors within a power budget of a few megawatts.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California. Visit our Website at www.lbl.gov.

[Ucilia Wang @ DOE/Lawrence Berkeley National Laboratory]

The Socratic dialogue is a particular way of developing children’s, as well as adults’, thinking skills through cooperative dialogue where significant human ideas and values are discussed. By participating in Socratic seminars regularly every other week, preschool children and older students develop their thinking skills. The seminars address literature and art work, with questions such as these: is Pippi Longstocking a good friend, is Jack stupid or smart when he sells his mother’s cow for some beans, or are we born good or evil? In the beginning the students have difficulty expressing their thoughts, but with time their ability to express themselves and to examine ideas critically and logically develops.

The study included seven groups of children, five to sixteen years old. The groups were filmed during three years of philosophizing in the classroom and the films were analyzed. The interaction in the classroom was positively influenced, according to Ann S Pihlgren. The teacher dominated less, more students spoke and the students gradually took over the responsibilities of the teacher to promote exploration in the dialogue. The ability to use the Socratic seminar is learned by students and teachers through practice and by testing the rules of the seminar. The students construct a supportive group culture through their silent interaction, where gestures, glances, and body language are used to show not only support or sympathy for each other, but also cooperation with each other when someone attempts to disturb or to provoke the dialogue. The teacher role changes to one of support, ensuring that the analysis is fruitful and that the dialogue is respectful.

Socratic methods have developed independently in various countries. They all describe a set of methodological steps to attain similar objectives. An opening question is answered by all participants and followed by cooperative, critical analysis. Finally, the new ideas are connected to the everyday life experience of the participants.

It seems as if this ritualized structure and the nurturing culture of the seminar provide a safe circle, helping the participants to try new, bold ideas that they might otherwise not have tested, Ann S. Pihlgren says. By cooperating when examining the ideas they also seem to learn a way to address problems on their own without teacher intervention.

To work with methods connected to the ancient philosopher Socrates may seem out-of-date in a modern school, but that is absolutely not the case, Ann S. Pihlgren states.

The Socratic seminars have been seen as a complement to traditional classroom teaching for hundreds of years. But it is not easy to learn how to stage them to get positive effects. It is especially hard for teachers, who often fall back to their traditional, controlling “teacher” roles. The dissertation offers excellent tools for teachers who want to develop students’ thinking and to foster cooperative group dialogue.

The name of the dissertation: Socrates in the Classroom. Rationales and Effects of Philosophizing with Children. The dissertation can be downloaded as a pdf here.

[Jonas Ablad @ Swedish Research Council]