22,741 research outputs found

    TECHNOLOGICAL CHANGE IN MEAT AND POULTRY-PACKING AND PROCESSING

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    Nonparametric procedures are used to compare technological change in SIC 2011, meatpacking, and SIC 2015, poultry slaughter and processing. There has been a greater increase in total factor productivity in poultry than in the red meats. Evidence also suggests recent differences in the bias of this technological change, with production changes being labor using in poultry and biased towards greater efficiency in the use of live animal inputs in meatpacking.Red meat, Poultry, Meatpacking, Technological change, Nonparametric analysis, Livestock Production/Industries, Research and Development/Tech Change/Emerging Technologies,

    A COMPARISON OF DEPARTMENTAL TEACHING EFFICIENCY IN THE COLLEGE OF AGRICULTURE, FOOD SYSTEMS, AND NATURAL RESOURCES: AY2000-AY2004

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    Teaching efficiency is investigated for the nine departments in the College of Agriculture, Food Systems, and Natural Resources at North Dakota State University. Using Data Envelopment Analysis, departments are compared to their College peers in converting teaching faculty and teaching funds into three teaching outputs: student credit hours generated, undergraduate majors, and graduate students. Most departments are efficient in the technical conversion of inputs to outputs under variable returns to scale. Scale effects are evident, indicating some departments consistently extract higher average productivity from inputs in servicing undergraduate majors, graduate students, and in generating student credit hours.Teaching/Communication/Extension/Profession,

    Physical optics for oven-plate scattering prediction

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    An oven assembly design is described, which will be used to determine the effects of temperature on the electrical properties of materials which are used as coatings for metal plates. Experimentally, these plates will be heated to a very high temperature in the oven assembly, and measured using a microwave reflectance measurement system developed for the NASA Lewis Research Center, Near-Field Facility. One unknown in this measurement is the effect that the oven assembly will have on the reflectance properties of the plate. Since the oven will be much larger than the plate, the effect could potentially be significant as the size of the plate becomes smaller. Therefore, it is necessary to predict the effect of the oven on the measurement of the plate. A method for predicting the oven effect is described, and the theoretical oven effect is compared to experimental results of the oven material. The computer code which is used to predict the oven effect is also described

    Phylogenetic analysis accounting for age-dependent death and sampling with applications to epidemics

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    The reconstruction of phylogenetic trees based on viral genetic sequence data sequentially sampled from an epidemic provides estimates of the past transmission dynamics, by fitting epidemiological models to these trees. To our knowledge, none of the epidemiological models currently used in phylogenetics can account for recovery rates and sampling rates dependent on the time elapsed since transmission. Here we introduce an epidemiological model where infectives leave the epidemic, either by recovery or sampling, after some random time which may follow an arbitrary distribution. We derive an expression for the likelihood of the phylogenetic tree of sampled infectives under our general epidemiological model. The analytic concept developed in this paper will facilitate inference of past epidemiological dynamics and provide an analytical framework for performing very efficient simulations of phylogenetic trees under our model. The main idea of our analytic study is that the non-Markovian epidemiological model giving rise to phylogenetic trees growing vertically as time goes by, can be represented by a Markovian "coalescent point process" growing horizontally by the sequential addition of pairs of coalescence and sampling times. As examples, we discuss two special cases of our general model, namely an application to influenza and an application to HIV. Though phrased in epidemiological terms, our framework can also be used for instance to fit macroevolutionary models to phylogenies of extant and extinct species, accounting for general species lifetime distributions.Comment: 30 pages, 2 figure

    Dynamic power load simulator

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    Two independent models simulate dynamic and steady-state responses of electrical and electronic equipment under power load. One is resistance/capacitance/inductance network, and the other is variable resistance analog device. Resistance, inductance, and/or capacitance are selected by iterative process; time-domain response is compared with that of real equipment to select optimal values

    PROPERTY RIGHTS, GRAZING PERMITS, AND RANCHER WELFARE

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    This study attempts to link factors affecting the demand for Bureau of Land Management grazing to perceived changes in permittee welfare over the 1962-92 period. Annual demand for federal forage is found to be sensitive to active preference, beef cow and breeding ewe inventories, and grazing fees and nonfee allotment utilization costs. No evidence is found to support the notion that the demand for grazing has been affected by changes in property rights associated with the federal grazing permit that are not reflected in higher user costs. The total decrease in welfare generated from the permit that are not reflected in higher user costs. The total decrease in welfare generated from the permit to graze public lands has been about 9% per authorized cattle animal unit month and 65% per authorized sheep animal unit month over the study period.Land Economics/Use,

    AGRICULTURAL AND RECREATIONAL IMPACTS FROM SURFACE FLOW CHANGES DUE TO GOLD MINING OPERATIONS

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    Nevada ranks third in the world in gold production. In order to operate the massive open pit gold mines, the State of Nevada granted mining companies a temporary permit to pump groundwater from near the open pits and dispose of it. Certain instream flows have nearly doubled relative to average historical flows in recent years. Following pit closure, surface flows will likely decline from historical levels. This study measures the impacts of these changing water supplies on downstream agricultural and recreational users. We argue that the creation of temporary changes in water rights for the downstream users would likely mitigate future losses both groups are expected to experience.Resource /Energy Economics and Policy,
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