1,925 research outputs found

    PESTICIDE TAX, CROPPING PATTERNS, AND WATER QUALITY IN SOUTH CENTRAL TEXAS

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    The impact of an ad valorem pesticide tax on cropping patterns and pesticide use was examined in the South Central Texas Crop Reporting District. Output supply equations were econometrically estimated and used in the simulation. A 25 percent tax on pesticide was estimated to have major impacts on cropping patterns and on pesticide use. Assuming other input and output prices were unaffected, the supply of one important crop would fall by more than half. Demand for some of the highly soluble and persistent pesticides, which present the greatest threat to groundwater quality, would also decrease substantially (some as much as 50 percent).Crops, Dual model, Pesticides, Water quality, Supply, Crop Production/Industries,

    Computation of steady and unsteady quasi-one-dimensional viscous/inviscid interacting internal flows at subsonic, transonic, and supersonic Mach numbers

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    Computations of viscous-inviscid interacting internal flowfields are presented for steady and unsteady quasi-one-dimensional (Q1D) test cases. The unsteady Q1D Euler equations are coupled with integral boundary-layer equations for unsteady, two-dimensional (planar or axisymmetric), turbulent flow over impermeable, adiabatic walls. The coupling methodology differs from that used in most techniques reported previously in that the above mentioned equation sets are written as a complete system and solved simultaneously; that is, the coupling is carried out directly through the equations as opposed to coupling the solutions of the different equation sets. Solutions to the coupled system of equations are obtained using both explicit and implicit numerical schemes for steady subsonic, steady transonic, and both steady and unsteady supersonic internal flowfields. Computed solutions are compared with measurements as well as Navier-Stokes and inverse boundary-layer methods. An analysis of the eigenvalues of the coefficient matrix associated with the quasi-linear form of the coupled system of equations indicates the presence of complex eigenvalues for certain flow conditions. It is concluded that although reasonable solutions can be obtained numerically, these complex eigenvalues contribute to the overall difficulty in obtaining numerical solutions to the coupled system of equations

    Hospitality Administration Program Administrators View Core Areas of Knowledge

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    In 1992 the Accrediting Commission on Programs of Hospitality Administration established standards for hospitality administration programs. The authors surveyed program administrators regarding the current and preferred location for the teaching of the common core areas of hospitality administration knowledge

    East-West Genetic Differentiation in Musk Ducks (Biziura lobata) of Australia Suggests Late Pleistocene Divergence at the Nullarbor Plain

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    Musk Ducks (Biziura lobata) are endemic to Australia and occur as two geographically isolated populations separated by the Nullarbor Plain, a vast arid region in southern Australia. We studied genetic variation in Musk Duck populations at coarse (eastern versus western Australia) and fine scales (four sites within eastern Australia). We found significant genetic structure between eastern and western Australia in the mtDNA control region (UST = 0.747), one nuclear intron (UST = 0.193) and eight microsatellite loci (FST = 0.035). In contrast, there was little genetic structure between Kangaroo Island and adjacent mainland regions within eastern Australia. One small population of Musk Ducks in Victoria (Lake Wendouree) differed from both Kangaroo Island and the remainder of mainland eastern Australia, possibly due to genetic drift exacerbated by inbreeding and small population size. The observed low pairwise distance between the eastern and western mtDNA lineages (0.36%) suggests that they diverged near the end of the Pleistocene, a period characterised by frequent shifts between wet and arid conditions in central Australia. Our genetic results corroborate the display call divergence and Mathews’ (Austral Avian Record 2:83–107, 1914) subspecies classification, and confirm that eastern and western populations of Musk Duck are currently isolated from each other

    SecuCode: Intrinsic PUF Entangled Secure Wireless Code Dissemination for Computational RFID Devices

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    The simplicity of deployment and perpetual operation of energy harvesting devices provides a compelling proposition for a new class of edge devices for the Internet of Things. In particular, Computational Radio Frequency Identification (CRFID) devices are an emerging class of battery-free, computational, sensing enhanced devices that harvest all of their energy for operation. Despite wireless connectivity and powering, secure wireless firmware updates remains an open challenge for CRFID devices due to: intermittent powering, limited computational capabilities, and the absence of a supervisory operating system. We present, for the first time, a secure wireless code dissemination (SecuCode) mechanism for CRFIDs by entangling a device intrinsic hardware security primitive Static Random Access Memory Physical Unclonable Function (SRAM PUF) to a firmware update protocol. The design of SecuCode: i) overcomes the resource-constrained and intermittently powered nature of the CRFID devices; ii) is fully compatible with existing communication protocols employed by CRFID devices in particular, ISO-18000-6C protocol; and ii) is built upon a standard and industry compliant firmware compilation and update method realized by extending a recent framework for firmware updates provided by Texas Instruments. We build an end-to-end SecuCode implementation and conduct extensive experiments to demonstrate standards compliance, evaluate performance and security.Comment: Accepted to the IEEE Transactions on Dependable and Secure Computin

    Myocardial bioenergetic abnormalities in experimental uremia.

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    PURPOSE: Cardiac bioenergetics are known to be abnormal in experimental uremia as exemplified by a reduced phosphocreatine (PCr)/adenosine triphosphate (ATP) ratio. However, the progression of these bioenergetic changes during the development of uremia still requires further study and was therefore investigated at baseline, 4 weeks and 8 weeks after partial nephrectomy (PNx). METHODS: A two-stage PNx uremia model in male Wistar rats was used to explore in vivo cardiac and skeletal muscles' bioenergetic changes over time. High-energy phosphate nucleotides were determined by phosphorus-31 nuclear magnetic resonance ((31)P-NMR) and capillary zone electrophoresis. RESULTS: (31)P-NMR spectroscopy revealed lower PCr/ATP ratios in PNx hearts compared to sham (SH)-operated animals 4 weeks after PNx (median values given ± SD, 0.64±0.16 PNx, 1.13±0.31 SH, P<0.02). However, 8 weeks after PNx, the same ratio was more comparable between the two groups (0.84±0.15 PNx, 1.04±0.44 SH, P= not significant), suggestive of an adaptive mechanism. When 8-week hearts were prestressed with dobutamine, the PCr/ATP ratio was again lower in the PNx group (1.08±0.36 PNx, 1.55±0.38 SH, P<0.02), indicating a reduced energy reserve during the progression of uremic heart disease. (31)P-NMR data were confirmed by capillary zone electrophoresis, and the changes in myocardial bioenergetics were replicated in the skeletal muscle. CONCLUSION: This study provides evidence of the changes that occur in myocardial energetics in experimental uremia and highlights how skeletal muscle bioenergetics mirror those found in the cardiac tissue and so might potentially serve as a practical surrogate tissue during clinical cardiac NMR investigations

    The climatology of dew points and fire weather related parameters in the Missouri-Arkansas region

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    Title from PDF of title page (University of Missouri--Columbia, viewed on March 28, 2011).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. Anthony Lupo.Includes bibliographical references.M.S. University of Missouri--Columbia 2010.Dissertations, Academic -- University of Missouri--Columbia -- Soil, environmental and atmospheric sciences.Forecasting fire weather in the Springfield, Missouri and Little Rock, Arkansas Weather Forecast Offices (SGF and LZK WFO, respectively) across the greater Missouri and Arkansas regions (MoArk) county warning areas has been described as a challenge for wildfire managers. It is known that wildfire managers rely on their local WFO to provide fire weather forecast that are vital in the decision making process for wildfire suppression and prescribe fire management. Many climatic factors that affect fire hazards, including soil moisture, synoptic conditions, dewpoint, temperature and wind are indirectly impacted by ENSO. The climatology of dewpoint, temperature, Palmer Index, and synoptic conditions of fire weather flow regimes are presented here using the synoptic station observation network covering the MoArk region. A statistical analysis was performed in order to find useful interannual variability in the climatology of dew points and fire weather related parameters and their relationship to El Niño and La Niña. The data set used here contains monthly average dewpoint temperatures dating back to 1948 for three sites within Missouri: St. Louis, Columbia, and Springfield and one site in Arkansas: Little Rock. Dewpoint rather than relative humidity was chosen for this research because it is a measure of the actual amount of moisture in the air and is useful for seasonal fire weather
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