464 research outputs found

    Fission Decay Widths for Heavy-Ion Fusion-Fission Reactions

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    Cross-section and neutron-emission data from heavy-ion fusion-fission reactions are consistent with a Kramers-modified statistical model which takes into account the collective motion of the system about the ground state; the temperature dependence of the location of fission transition points; and the orientation degree of freedom. We see no evidence to suggest that the nuclear viscosity departs from the surface-plus-window dissipation model. The strong increase in the nuclear viscosity above a temperature of ~1 MeV deduced by others is an artifact generated by an inadequate fission model.Comment: 14 pg, 6 fig, submitted to Physical Revie

    \u3ci\u3eStachybotrys atra\u3c/i\u3e, an Effective Aggregator of Peorian Loess

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    Twelve cellulose-decomposing fungi were tested for aggregating ability with Peorian loess containing ground straw at a concentration of 1%. Of the 12 fungi, Stachybotrys atra was the most effective soil aggregator. Under laboratory conditions used, it produced from 2 to 30 times more aggregation than any of the other fungi tested. Studies were made of the influence of various environmental factors on the degree of aggregation effected by S. atra. An incubation time of 1 week was sufficient for a relatively high degree of aggregation. In comparison, longer periods resulted in only slightly improved aggregation. Varying the temperature between 20° and 28° C. had no appreciable effect on the aggregation by S. atra. Approximately equivalent aggregations were attained at the moisture levels of 20, 25, and 30%, which were definitely superior to the 10 and 15% levels. Alfalfa and straw, either separately or as a mixture, were satisfactory sources of energy material for S. atra. The aggregation obtained with alfalfa, however, was somewhat higher than that obtained with straw

    THE IMPLICATIONS OF A NORTH AMERICAN FREE TRADE AREA FOR AGRICULTURE

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    This is one of two papers commissioned by the International Agricultural Trade Research Consortium on various aspects related to the agricultural sector of a prospective North American Free Trade Agreement. The companion paper to this one has been prepared by a working group chaired by Thomas Grennes, North Carolina State University. To minimize duplication with the Grennes paper, this paper has given greater attention to the general trade policy issues raised by a NAFTA, institutional factors, additional commodity detail in cereals, fruit and vegetables, and the relevance of other regional trade agreements such as the Canada-U.S. Trade Agreement. This work has also benefitted from an earlier report and its annexes, prepared for the Fraser Institute, under the direction of Tim Josling.International Relations/Trade,

    Strategic Cooperation in Peripheral Ports: The Case of Atlantic Canada’s Ports

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    This paper examines ports on the geographical periphery of the port business: they are off the main shipping routes or not located proximal to large domestic markets. These ports have development potential, but reaching it requires specific strategies. The paper first discusses the nature of peripheral ports followed by a conceptualization of two development strategies: cooperation among seaports and coordination of supply chain operators with the emphasis on cooperation. The paper considers Atlantic Canada’s ports and their current cooperation initiatives concluding with recommendations on how these ports may better serve their interests through applying cooperation strategies found elsewhere

    Setting Agricultural Research Priorities: Lessons from the CGIAR Study

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    The Consultative Group on International Agfi-cultural Research (CGIAR) is .1 loose BSSOCtft' lion of 40 donor agencies who provide about 250 million dollars annually to support international agricultural research on developing country problems in 18 institutes. The CGIAR is a relatively small actor on the global scene, representing less than 5% of agricultural research expenditures in developing countries and less than 2% of global public seclor expenditure on agricultural research (Gryseels and Anderson). Therefore, it has always had to be selective in choosing the nature and focus of the research it supports. Priority setting and advice on resource allocation is provided by an independent Technical Advisory Committee (TAC). In this paper we provide a brief review of TAC's approaches to priority setting before focusing on their most recent exercise completed in 1992. This effort was by far the most comprehensive attempt io use quantitative analysis to identify priorities and link them to resource allocation. The approach described in TAC/CGIAR (1992) is best characterized as a modified congruence approach or scoring model, using a spreadsheet The paper concludes with a critical appraisal of the strengths and weaknesses of the TAC approach relative lo other approaches

    A strategic framework for improving food security in Arab countries

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    In 2007 and the first half of 2008, a sharp rise in agricultural commodity and food prices triggered grave concerns about food security, malnutrition and increased poverty. While the threat of a prolonged food-price shock receded in the second half of 2008, many factors underlying the price volatility are likely to persist, and will require careful management if future food-price shocks are to be avoided. This paper suggests three strategies that, together, could reduce vulnerability to price shocks: (1) strengthen safety nets, improve access to family planning services, and promote education; (2) enhance domestic food production and improve rural livelihoods through increased investment in research and development to increase productivity; and (3) reduce exposure to market volatility through more efficient supply chains and better use of financial instruments to hedge risk. The challenge of food security will require a global response, involving governments, international and regional funding and lending institutions, United Nations agencies, non-governmental organizations, civil society, and the private sector

    Supporting Peer Help and Collaboration in Distributed Workplace Environments

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    Special Issue on Computer Supported Collaborative LearningIncreasingly, organizations are geographically distributed with activities coordinated and integrated through the use of information technology. Such organizations face constant change and the corresponding need for continual learning and renewal of their workers. In this paper we describe a prototype system called PHelpS (Peer Help System) that facilitates workers in carrying out such "life long learning". PHelpS supports workers as they perform their tasks, offers assistance in finding peer helpers when required, and mediates communication on task-related topics. When a worker runs into difficulty in carrying out a task, PHelpS provides a list of other workers who are ready, willing and able to help him or her. The worker then selects a particular helper with PHelpS supporting the subsequent help interaction. The PHelpS system acts as a facilitator to stimulate learning and collaboration, rather than as a directive agent imposing its perspectives on the workers. In this way PHelpS facilitates the creation of extensive informal peer help networks, where workers help one another with tasks and opens up new research avenues for further exploration of AI-based computer-supported collaborative learning. (http://aied.inf.ed.ac.uk/members98/archive/vol_9/greer/full.html

    Paper Session II-D - Project Vision: A Model Program to Educate the Next Generation of Engineers, Scientists, and Mathematicians

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    Project VISION (Very Intensive Scientific Intercurricular On-Site Education) is a joint effort among NASA/John F. Kennedy Space Center, Florida International University, Universidad del Turabo, Miami-Dade County Public Schools and the Caguas/Gurabo Public Schools in Puerto Rico. The project\u27s main mission is to institutionalize change among the elementary and middle school science and math teachers at participating schools. Thereafter, the teachers provide their students with continuously enriched instruction in the principles of science and math through the use of hands-on and minds-on experiments called learning modules. These learning modules have been classified according to the national science and math education standards established by the National Committee on Science Education Standards and Assessments and the National Council of Teachers of Mathematics, respectively

    Escherichia coli YafP protein modulates DNA damaging property of the nitroaromatic compounds

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    Escherichia coli SOS functions constitute a multifaceted response to DNA damage. We undertook to study the role of yafP, a SOS gene with unknown function. yafP is part of an operon also containing the dinB gene coding for DNA Polymerase IV (PolIV). Our phylogenetic analysis showed that the gene content of this operon is variable but that the dinB and the yafP genes are conserved in the majority of E. coli natural isolates. Therefore, we studied if these proteins are functionally linked. Using a murine septicaemia model, we showed that YafP activity reduced the bacterial fitness in the absence of PolIV. Similarly, YafP increased cytotoxicity of two DNA damaging nitroaromatic compounds, 4-nitroquinoline-1-oxide (NQO) and nitrofurazone, in the absence of PolIV. The fact that PolIV counterbalances YafP-induced cytotoxicity could explain why these two genes are transcriptionally linked. We also studied the involvement of YafP in genotoxic-stress induced mutagenesis and found that PolIV and YafP reduced NQO-induced mutagenicity. The YafP antimutator activity was independent of the PolIV activity. Given that YafP was annotated as a putative acetyltransferase, it could be that YafP participates in the metabolic transformation of genotoxic compounds, hence modulating the balance between their mutagenicity and cytotoxicity

    Paper Session II-D - Project Vision (Very Intensive Scientific Intercurricular Onsite Education): A Partnership Among NASA/John F. Kennedy Space Center, Florida International University, Universidad del Turabo, Dade County Public Schools, and the Caguas/Gurabo Public Schools.

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    Project VISION is a joint effort among NASA/John F. Kennedy Space Center, Florida International University, Universidad del Turabo, Dade County Public Schools and the Caguas/ Gurabo Public Schools. The project’s main mission is to institutionalize change among the 7th grade science and mathematics teachers at participating public middle schools. A further aspect of the mission is to enhance the science and math education of the public middle school students during the phase of institutionalization. Project VISION will not need to generate any new educational materials to fulfill its mission. Rather than generating new materials, Project VISION will use the vast quantities of high quality learning modules, lessons, hands-on experiments and other educational materials available at NASA and other scientific depositories. The project will identify, adopt and then adapt these learning modules or learning materials to best meet the needs and capabilities of the target student and teacher populations. A further goal of this project lies within the realm of NASA’s Mission - to specifically focus our activities on middle schools that serve socially and economically disadvantaged students. Additionally, the project will invite members of the private and public sectors to serve as lecturers, mentors and role models. The project will perform program evaluations to measure the levels of success and accomplishments of each of the proposed activities
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