2,155 research outputs found

    Amaranthus seed regeneration in plastic tents in greenhouses

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    Amaranthus germplasm is efficiently regenerated in plastic tents within greenhouses . This protocol involves the cultivation of 100-plant populations in 0.8 m2 x 1 m tall tents , and generally yields 40 000-120 000 seeds about 3 months after planting. Expsriments were performed to test the effectiveness of pollination control by isolating four monoecious Amaranthus species in these plastic tents . The estimated f requency of pollen contamination between tents was 0.01%. The estimated frequency of cross-pollination within tents was 3.9%

    A Chinese Sky Trust? Distributional Impacts of Carbon charges and Revenue Recycling in China

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    The introduction of carbon charges on the use of fossil fuels in China would have a progressive impact on income distribution. This outcome, which contrasts to the regressive distributional impact found in most studies of carbon charges in industrialized countries, is driven primarily by differences between urban and rural expenditure patterns. If carbon revenues were recycled on an equal per capita basis via a ‘sky trust,’ the progressive impact would be further enhanced: low-income (mainly rural) households would receive more in sky-trust dividends than they pay in carbon charges, and high-income (mainly urban) households would pay more than they receive in dividends. Thus a Chinese sky trust would contribute to both lower fossil fuel consumption and greater income equality.carbon charges, fossil fuels, China, income distribution, carbon revenues, fuel consumption, income equality

    Results of an exploration to expand the diversity of Daucus and Apiaceae germplasm collections

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    In volume 8 of this newsletter, Reitsma and Widrlechner {1998) reported on the status of Daucus and Apiaceae germplasm at the USDA-ARS North Central Regional Plant Introduction Station {NCRPIS), in Ames, Iowa. The NCRPIS is one of the primary active sites in the U.S. National Plant Germplasm System {NPGS), cons¢rving diverse collections of crop plants and their wild and weedy relatives and making them available for research and educational purposes at no cost to the user. Information about all NPGS collections can be obtained through the Germplasm Resources Information Network (GRIN) database, which can be searched via the Internet at http://www.ars-grin.gov/npgs. In 1999, Philipp Simon (USDA-ARS, Madison, WI), along with colleagues in Poland, Greece, Syria, and Turkey, organized and conducted an exploration through financial support provided by the USDA-ARS Plant Exchange Office {Williams, 2005). That exploration was designed to collect landrace and wild germplasm of Daucus and other Apiaceae from the eastern Mediterranean, a region with considerable umbel diversity. The incorporation of collections made by Simon and his colleagues during the summer of 1999 into the NPGS has made much of the information presented by Reitsma and Widrlechner {1998) obsolete. In this report, we wish to inform umbel researchers about our success in confirming the identity of these new collections, regenerating them, and making them available for research and education

    Measuring the Impact of Living Wage Laws: A Critical Appraisal of David Neumark's How Living Wage Laws Affect Low-Wage Workers and Low-Income Families

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    Drawing on data from the Current Population Survey (CPS), David Neumark (2002) finds that living wage laws have brought substantial wage increases for a high proportion of workers in cities that have passed these laws. He also finds that living wage laws significantly reduce employment opportunities for low-wage workers. We argue, first, that by truncating his sample to concentrate his analysis on low-wage workers, Neumark’s analysis is vulnerable to sample selection bias, and that his results are not robust to alternative specifications that utilize quantile regression to avoid such selection bias. In addition, we argue that Neumark has erroneously utilized the CPS data set to derive these results. We show that, with respect to both wage and employment effects, Neumark’s results are not robust to more accurate alternative classifications as to which workers are covered by living wage laws. We also show that the wage effects that Neumark observes for all U.S. cities with living wage laws can be more accurately explained as resulting from effects on sub-minimum wage workers in Los Angeles alone of a falling unemployment rate and rising minimum wage in that city.

    Zen and clinical social work: A spiritual approach to practice

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    This exploratory study examined the influence of a personal practice of Zen Buddhist meditation on the professional work of clinical social workers. Three areas were explored with a sample of 10 clinical social workers who had practiced Zen meditation for at least 5 years: practice framework, clinical practice, and interactions within larger systems. Analysis of the data generated from semistructured interviews revealed 3 interrelated, overarching themes: awareness, acceptance, and responsibility. Implications of these findings for the practice of clinical social work are offered

    Liquid nitrogen controls seed-borne chalcids without reducing germination in coriander seeds

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    Coriander seeds are susceptible to infestation by chalcid wasps which often render the seeds inviable. Control of chalcids in seeds is a prerequisite for supplying coriander germplasm to requestors throughout the world. Levels of chalcid infestation in coriander seed samples produced at the North Central Regional Plant Introduction Station, in Ames, IA, mandated the need to develop an effective control strategy without harming the seeds. Storing the seeds above liquid nitrogen for 16 hours proved effective in killing chalcids at all life stages without reducing seed germination. Results were based on germination tests, seed dissection, chalcid emergence, and digital x-ray images

    Role of HIV Subtype Diversity in the Development of Resistance to Antiviral Drugs

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    Despite the fact that over 90% of HIV-1 infected people worldwide harbor non-subtype B variants of HIV-1, knowledge of resistance mutations in non-B HIV-1 and their clinical relevance is limited. Due to historical delays in access to antiretroviral therapy (ART) on a worldwide basis, the vast majority of reports on drug resistance deal with subtype B infections in developed countries. However, both enzymatic and virological data support the concept that naturally occurring polymorphisms among different nonB subtypes can affect HIV-1 susceptibility to antiretroviral drugs (ARVs), the magnitude of resistance conferred by major mutations, and the propensity to acquire some resistance mutations. Tools need to be optimized to assure accurate measurements of drug susceptibility of non-B subtypes. Furthermore, there is a need to recognize that each subtype may have a distinct resistance profile and that differences in resistance pathways may also impact on cross-resistance and the selection of second-line regimens. It will be essential to pay attention to newer drug combinations in well designed long-term longitudinal studies involving patients infected by viruses of different subtypes

    Drag-n-fly: a Proposal in Response to a Low Reynolds Number Station Keeping Mission

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    The Drag-n-Fly is a remotely piloted, low Reynolds number vehicle. It was designed to maintain level controlled flight and fly a closed course at flight speeds corresponding to Reynolds numbers of less than 2 x 10(exp 5) and as close to 1 x 10(exp 5) as possible. The success of the mission will be associated with achieving the lowest mean chord Reynolds number possible and maximizing loiter time on the course. The flight plan for the Drag-n-Fly calls for the vehicle to ascent to a cruise altitude of 25 ft. The airfoil selected for the Drag-n-Fly is a Spica chosen for its high lift coefficient at low Reynolds number. The propulsion system for the Drag-n-Fly consists of a 10 inch diameter propeller mounted on the front of the vehicle. Structural support for the Drag-n-Fly comes from four box beams running the length of the fuselage. The tail and horizontal stabilizers are located far aft of the lifting surface in order to assure proper static stability. The present design for the Drag-n-Fly will meet the criteria for the present mission
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