1,289 research outputs found

    Electric and Magnetic fields due to Dirac particles in FRW spacetime

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    Some solutions of the Maxwell equations with Dirac particles for the source in FRW spacetime are discussed. The Green's function of the equation for the radial component of the Maxwell fields, F_{r\eta} and F_{\theta\phi} is solved. Green's function is found to reduce to that of Minkowskian spacetime in the appropriate limit. Also, the Lienard-Wiechert type solution is derived. Also, the solutions with the Dirac particle current is also presented. It is found that the F_{r\eta} is composed of even angular momentum states while the odd states constitue F_{\theta\phi} .Comment: 8 pages including 2 figure

    Field Procedure for Estimating the Measurement Area of Non-Contact Temperature Sensors

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    Transportation departments across the United States have installed sensors mounted on towers by the roadside to measure road surface temperatures. Since no guidelines exist for verifying the accuracy of such measurements, agencies are forced to accept claims made by vendors. To correct this situation, the Idaho Transportation Department (ITD) contracted with Boise State University (BSU) to test the accuracy of the non-contact, infrared temperature sensors installed throughout Idaho. Before collecting independent temperature data, BSU devised an easy-to-use procedure for determining the effective area viewed by the infrared sensors. According to ITD, the vendor claimed that at a distance of 10 m between the sensor and the road surface, the diameter of the effective area viewed by the sensor would be 80 cm. BSU’s field experiment revealed that the sensor’s viewing area was much larger than that claimed by the vendor. The discrepancy suggests that other claims made by the vendor regarding the accuracy and precision of their measurements cannot be relied upon and transportation departments will need to conduct independent tests to verify such claims

    Adoption of Technology, Management Practices, and Production Systems in U.S. Milk Production

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    We examine U.S. dairy farmer adopter characteristics and adoption rates of eleven technologies. Excepting grazing, technologies were generally adopted complementarily. Four were used on higher percentages of farms in 2005 than 2000. The interaction of farm size with adoption suggests greater percentages of milk being produced under each, excepting grazing.Technically Complementary, Technology, Management Practices, Production System, Farm Management, Livestock Production/Industries, Production Economics,

    Assessment of 137Cs in the Environment of Hetauda City, Nepal by In-Situ Gamma Ray Spectrometry

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    A significant amount of 137Cs radioactive fallout have been spread in the atmosphere due to nuclear weapon testing and nuclear reactor disasters. This fallout eventually settles on the Earth's surface, and because 137Cs has a long half-life, it remains in the environment for an extended period. Mapping the distribution of 137Cs is crucial, and this study aims to assess the radioactive deposition of 137Cs in the ground to establish baseline data for its distribution in the environment of Hetauda City, Nepal. Recently, Hetauda City has been designated as the capital city of the Bagmati province. To measure 137Cs deposition, portable (backpack) gamma ray spectrometer was used with a 0.347-liter NaI(Tl) detector.  Rapid measurement was carried out while walking at a pace of less than 2 km/h, and the distance between the detector and the ground was maintained at less than 1 m with the detector pointing downward. The surface activity of 137Cs was measured in the range of 0.003 to 2.382 kBq/m2, with an average value of 0.581 ± 0.343 kBq/m2. The spatial variability of 137Cs was found to be smooth in the area, and the mean annual effective dose calculated was 0.379 ± 0.224 µSv. The low dose rates and smooth spatial distribution of 137Cs in the environment indicate no contamination, and the trace amount present could be due to global fallout from weapons testing and nuclear accidents. The results were compared with previously reported values worldwide

    Economic Sustainability and Multiple Risk Management Strategies: Examining Interlinked Decisions of Small American Farms

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    Economic viability of small farms and farming businesses depends on multiple factors. These farms have limited production and financial resources to maintain their operation. Therefore, to sustain farming, adopting appropriate risk management strategies is a pivotal decision for small farmers. We surveyed Tennessee’s small farms and utilized multivariate probit models to study factors influencing the adoption of various risk management strategies. Our findings suggest that the decisions related to the adoption of risk management strategies are significantly interlinked. Along with factors representing the operator’s age, education, and farm operator’s income and land holdings, we also found that the government incentives (payments), smartphones, and farmers’ continuation plan significantly influence the strategic decisions of adopting risk management strategies

    Examining Farm Financial Management: How Do Small US Farms Meet Their Agricultural Expenses?

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    Small farms in the US have significant challenges in financial management. This study examines how small farmers undertake farm financial management to meet their agricultural and farm-related spending and expenses. Using primary survey data from Tennessee, the study investigates the factors influencing the extent of use of five financing sources to meet the spending and expenses: cash/fund directly generated from the sale of agricultural products, farmer’s past savings, farm household’s off-farm income, income/incentives from government payments, and external loans. Using negative binomial regression estimation of generalized linear models, findings suggest that the decision on the use of financing sources is significantly influenced in general by age, education, income and land acreage holdings, off-farm work, and risk factors related to farmer or farm household. However, the associated factors and their effects on the extent of use are different depending on the financing source
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