267 research outputs found

    Scattering of the Radiation Field of a Loop Antenna by a Conducting Cylinder Immersed in a Cold Plasma

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    Combine Losses From Wide and Narrow Corn Rows

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    Growers of 38-cm (15-in.) narrow row com typically use either a wider row cornhead or locally modify an existing head to this row spacing. A three-year field experiment compared visible machine losses of a 76-cm (30-in.) cornhead used on 76-cm (30-in.) and 38-cm (15-in.) rows and a single gathering chain 38-cm (15-in.) cornhead used on 38-cm (15-in.) rows. Total machine losses were divided into head and threshing/separating losses

    Effects of Wall Permittivity and Plasma Thickness on the Plasma Reflection Coefficient

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    Developing Dental Faculty for the Future: ADEA/AAL Institute for Teaching and Learning, 2006–09

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    This report summarizes the history and curriculum of the American Dental Education Association/Academy for Academic Leadership Institute for Teaching and Learning (ADEA/AAL ITL) Program for Dental School Faculty, describes participant feedback, and reviews how the program serves the faculty development initiatives of the American Dental Education Association. The fifty-hour program (6.5 days), conducted in two phases at collaborating dental schools, enhances core academic competencies of new and transitional faculty, including faculty members whose responsibilities include predoctoral, allied, and postdoctoral dental education. The program's mission is to prepare participants to become more effective teachers and develop other skills that will facilitate confidence, job satisfaction, and professional growth in the academic environment. From 2005 to 2009, 174 individuals graduated from the program, representing forty-three schools of dentistry in the United States and Canada and twenty-nine private practices. A total of forty scholarships have been awarded to participants by the American Academy of Periodontology Foundation, the American Academy of Pediatric Dentistry, and the American Association of Orthodontists. In an online survey completed by 75 percent of ADEA/AAL ITL participants, 99 percent indicated they were positive or highly positive about their learning experience in this faculty development program. Ninety-six percent stated that the program had been important or very important in their effectiveness as a teacher. In 2010, the program will be held at the University of North Carolina at Chapel Hill School of Dentistry, with phase I occurring on August 19-22, 2010, and phase II on October 22-24, 2010. In summary, the ADEA/AAL ITL is addressing an unmet need through a formal professional development program designed to help new and potential faculty members thrive as educators and become future leaders in academic health care

    Sustainable Sourcing of Global Agricultural Raw Materials: Assessing Gaps in Key Impact and Vulnerability Issues and Indicators.

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    Understanding how to source agricultural raw materials sustainably is challenging in today's globalized food system given the variety of issues to be considered and the multitude of suggested indicators for representing these issues. Furthermore, stakeholders in the global food system both impact these issues and are themselves vulnerable to these issues, an important duality that is often implied but not explicitly described. The attention given to these issues and conceptual frameworks varies greatly--depending largely on the stakeholder perspective--as does the set of indicators developed to measure them. To better structure these complex relationships and assess any gaps, we collate a comprehensive list of sustainability issues and a database of sustainability indicators to represent them. To assure a breadth of inclusion, the issues are pulled from the following three perspectives: major global sustainability assessments, sustainability communications from global food companies, and conceptual frameworks of sustainable livelihoods from academic publications. These terms are integrated across perspectives using a common vocabulary, classified by their relevance to impacts and vulnerabilities, and categorized into groups by economic, environmental, physical, human, social, and political characteristics. These issues are then associated with over 2,000 sustainability indicators gathered from existing sources. A gap analysis is then performed to determine if particular issues and issue groups are over or underrepresented. This process results in 44 "integrated" issues--24 impact issues and 36 vulnerability issues--that are composed of 318 "component" issues. The gap analysis shows that although every integrated issue is mentioned at least 40% of the time across perspectives, no issue is mentioned more than 70% of the time. A few issues infrequently mentioned across perspectives also have relatively few indicators available to fully represent them. Issues in the impact framework generally have fewer gaps than those in the vulnerability framework

    Substantial carbon loss respired from a corn-soybean agroecosystem highlights the importance of careful management as we adapt to changing climate

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    Understanding agroecosystem carbon (C) cycle response to climate change and management is vital for maintaining their long-term C storage. We demonstrate this importance through an in-depth examination of a ten-year eddy covariance dataset from a corn-corn-soybean crop rotation grown in the Midwest United States. Ten-year average annual net ecosystem exchange (NEE) showed a net C sink of -0.39 Mg C ha-1 yr-1. However, NEE in 2014 and 2015 from the corn ecosystem was 3.58 and 2.56 Mg C ha-1 yr-1, respectively. Most C loss occurred during the growing season, when photosynthesis should dominate and C fluxes should reflect a net ecosystem gain. Partitioning NEE into gross primary productivity (GPP) and ecosystem respiration (ER) showed this C \u27burp\u27 was driven by higher ER, with a 51% (2014) and 57% (2015) increase from the ten-year average (15.84 Mg C ha-1 yr-1). GPP was also higher than average (16.24 Mg C ha-1 yr-1) by 25% (2014) and 37% (2015), but this was not enough to offset the C emitted from ER. This increased ER was likely driven by enhanced soil microbial respiration associated with ideal growing season climate, substrate availability, nutrient additions, and a potential legacy effect from drought

    Predicting tensile properties of Ti-6Al-4V produced via directed energy deposition

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    Advanced manufacturing approaches, including additive manufacturing (i.e., “3D printing”) of metallic structures requires a change to qualification strategies. One approach, informed qualification, integrates modeling strategies to make predictions of material characteristics, including the prediction of tensile properties for given chemistries and microstructures. In this work, constitutive equations are developed and presented that can predict the yield strength of additively manufactured Ti-6Al-4V subjected to one of three different heat-treatments: a stress relief anneal in the α+β phase field; a hot isostatic press treatment in the α+β phase field; and a β-anneal. The equations are nominally identical, though different strengthening mechanisms are active according to subtle microstructural differences. To achieve an equation that can predict the yield strength of the material, it is also necessary to include an assessment of dramatic reduction in the tensile strength due to texture (i.e., a “knock-down” effect). This has been experimentally measured, and included in this paper. The resulting predictions of yield strength are generally within 5% of their experimentally measured values

    The Lore of Low Methane Livestock:Co-Producing Technology and Animals for Reduced Climate Change Impact

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    Methane emissions from sheep and cattle production have gained increasing profile in the context of climate change. Policy and scientific research communities have suggested a number of technological approaches to mitigate these emissions. This paper uses the concept of co-production as an analytical framework to understand farmers’ evaluation of a 'good animal’. It examines how technology and sheep and beef cattle are co-produced in the context of concerns about the climate change impact of methane. Drawing on 42 semi-structured interviews, this paper demonstrates that methane emissions are viewed as a natural and integral part of sheep and beef cattle by farmers, rather than as a pollutant. Sheep and beef cattle farmers in the UK are found to be an extremely heterogeneous group that need to be understood in their specific social, environmental and consumer contexts. Some are more amenable to appropriating methane reducing measures than others, but largely because animals are already co-constructed from the natural and the technical for reasons of increased production efficiency

    Creative and Stylistic Devices Employed by Children During a Storybook Narrative Task: A Cross-Cultural Study

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    Purpose: The purpose of this study was to analyze the effects of culture on the creative and stylistic features children employ when producing narratives based on wordless picture books. Method: Participants included 60 first- and second-grade African American, Latino American, and Caucasian children. A subset of narratives based on wordless picture books collected as part of a larger study was coded and analyzed for the following creative and stylistic conventions: organizational style (topic centered, linear, cyclical), dialogue (direct, indirect), reference to character relationships (nature, naming, conduct), embellishment (fantasy, suspense, conflict), and paralinguistic devices (expressive sounds, exclamatory utterances). Results: Many similarities and differences between ethnic groups were found. No significant differences were found between ethnic groups in organizational style or use of paralinguistic devices. African American children included more fantasy in their stories, Latino children named their characters more often, and Caucasian children made more references to the nature of character relationships. Conclusion: Even within the context of a highly structured narrative task based on wordless picture books, culture influences children’s production of narratives. Enhanced understanding of narrative structure, creativity, and style is necessary to provide ecologically valid narrative assessment and intervention for children from diverse cultural backgrounds
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