1,800 research outputs found

    Regeneration experiments below 10K in a regenerative-cycle cryocooler

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    At temperatures below 10K, regenerative cycle cryocoolers are limited by regeneration losses in the helium working fluid which result from the decreasing heat capacity of the regenerating material and the increasing density of helium. Experiments examining several approaches to improving the low-temperature regeneration in a four-stage regenerative cycle cooler constructed primarily of fiberglass materials are discussed. Using an interchangeable fourth stage, the experiments included configurations with multiple regeneration passages, and a static helium volume for increased heat capacity. Experiments using helium-3 as the working fluid and a Malone stage are planned. Results indicate that, using these techniques, it should be possible to construct a regenerative cycle cooler which will operate below 6K

    Shipboard fisheries management terminals

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    The needs of the National Marine Fisheries Service (NMGS), National Weather Service, and the U.S. Coast Guard for locational, biological, and environmental data were assessed. The fisheries conservation zones and the yellowfin tuna jurisdiction of the NMFS operates observer programs on foreign and domestic fishing vessels. Data input terminal and data transfer and processing technology are reviewed to establish available capability. A matrix of implementation options is generated to identify the benefits of each option, and preliminary cost estimates are made. Recommendations are made for incremental application of available off the shelf hardware to obtain improved performance and benefits within a well bounded cost. Terminal recommendations are made for three interdependent shipboard units emphasizing: (1) the determination of location and fishing activity; (2) hand held data inputting and formatting in the fishing work areas; and (3) data manipulation, merging, and editing

    Apple Pie Propaganda? The Smith–Mundt Act Before and After the Repeal of the Domestic Dissemination Ban

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    For over sixty years, the Smith–Mundt Act prohibited the U.S. Department of State and the Broadcasting Board of Governors (BBG) from disseminating government-produced programming within the United States over fears that these agencies would “propagandize” the American people. However, in 2013, Congress abolished the domestic dissemination ban, which has led to a heated debate about the role of the federal government in free public discourse. Although the 2013 repeal of the domestic dissemination ban promotes greater government transparency and may help counter anti-American sentiment at home, it also gives the federal government great power to covertly influence public opinion. To curb the potential harm of surreptitious government propaganda, while also preserving the benefits of repeal, this Note advocates for requiring the State Department and the BBG to clearly attribute any government-produced programming these agencies disseminate within the United States. This Note contends that attribution can be best accomplished in one of two ways: by passing new attribution legislation similar to that of the failed Truth in Broadcasting Act of 2005 or by expanding the judicially created government speech doctrine to require these agencies to properly attribute any materials they distribute to the American public

    Liberation Pragmatism: Dussel and Dewey in Dialogue

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    Enrique Dussel and John Dewey share commitments to philosophical theory and practice aimed at addressing human problems, democratic modes of inquiry, and progressive social reform, but also maintain productive differences in their fundamental starting point for political philosophy and their use of the social sciences. Dussel provides a corrective to Dewey’s Eurocentrism and to his tendency to underplay the challenges of incorporating marginalized populations by insisting that social and political philosophy begin from the perspective of the marginalized and excluded. Simultaneously, Dewey encourages a modest experimental and fallibilist approach to social transformation that promises more feasible social reforms than Dussel’s approach rooted in phenomenology and the critical social sciences

    Excretion of Cannabinoids in Urine after Ingestion of Cannabis Seed Oil

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    Gas chromatographic-mass spectrometric (GC-MS) quantitation of 25 cannabis sed oils determined Δ9-tetrahydrocannabinol (THC) concentrations from 3 to 1500 µg/g oil. In a pilot study, the morning urine of six volunteers who had ingested 11 or 22 g of the oil, which contained the highest THC content (1500 µg/g), was collected for six days. The urine samples were screened by immunoassay, and the content of 11-nor-9-carboxy-Δ9-THC (THCCOOH) was determined by GC-MS. Urine samples were found cannabis positive for up to six days with THCCOOH-equivalent concentrations up to 243 ng/ml, by the Abuscreen OnLine immunoassay and THCCOOH contents from 5 to 431 ng/mL by the GC-MS method. All subjects reported THC-specific psychotropic effect

    Development of physical and mathematical models for the Porous Ceramic Tube Plant Nutrification System (PCTPNS)

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    A physical model of the Porous Ceramic Tube Plant Nutrification System (PCTPNS) was developed through microscopic observations of the tube surface under various operational conditions. In addition, a mathematical model of this system was developed which incorporated the effects of the applied suction pressure, surface tension, and gravitational forces as well as the porosity and physical dimensions of the tubes. The flow of liquid through the PCTPNS was thus characterized for non-biological situations. One of the key factors in the verification of these models is the accurate and rapid measurement of the 'wetness' or holding capacity of the ceramic tubes. This study evaluated a thermistor based moisture sensor device and recommendations for future research on alternative sensing devices are proposed. In addition, extensions of the physical and mathematical models to include the effects of plant physiology and growth are also discussed for future research

    A summary of porous tube plant nutrient delivery system investigations from 1985 to 1991

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    The Controlled Ecological Life Support System (CELSS) Program is a research effort to evaluate biological processes at a one person scale to provide air, water, and food for humans in closed environments for space habitation. This program focuses currently on the use of conventional crop plants and the use of hydroponic systems to grow them. Because conventional hydroponic systems are dependent on gravity to conduct solution flow, they cannot be used in the microgravity of space. Thus, there is a need for a system that will deliver water and nutrients to plant roots under microgravity conditions. The Plant Space Biology Program is interested in investigating the effect that the space environment has on the growth and development of plants. Thus, there is also a need to have a standard nutrient delivery method for growing plants in space for research into plant responses to microgravity. The Porous Tube Plant Nutrient Delivery System (PTPNDS) utilizes a hydrophilic, microporous material to control water and nutrient delivery to plant roots. It has been designed and analyzed to support plant growth independent of gravity and plans are progressing to test it in microgravity. It has been used successfully to grow food crops to maturity in an earth-bound laboratory. This document includes a bibliography and summary reports from the growth trials performed utilizing the PTPNDS
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