The Bare Theory Has No Clothes

We criticize the bare theory of quantum mechanics -- a theory on which the Schrödinger equation is universally valid, and standard way of thinking about superpositions is correct

Polyetheretherketone as a Biomaterial for Spinal Applications

Threaded lumbar interbody spinal fusion devices (TIBFD) made from titanium have been reported to be 90% effective for single-level lumbar interbody fusion, although radiographic determination of fusion has been intensely debated in the literature. Using blinded radiographic, biomechanic, histologic, and statistical measures, we evaluated a radiolucent polyetheretherketone (PEEK)-threaded interbody fusion device packed with autograft or rhBMP-2 on an absorbable collagen sponge in 13 sheep at 6 months. Radiographic fusion, increased spinal level biomechanical stiffness, and histologic fusion were demonstrated for the PEEK cages filled with autograft or rhBMP-2 on a collagen sponge. No device degradation or wear debris was observed. Only mild chronic inflammation consisting of a few macrophages was observed in peri-implant tissues. Based on these results, the polymeric biomaterial PEEK may be a useful biomaterial for interbody fusion cages due to the polymer\u27s increased radiolucency and decreased stiffness

An Economic Risk Analysis of Tillage and Cropping Systems on the Arkansas Grand Prairie

No-till (NT) has been shown to reduce fuel, labor, and machinery costs compared to conventional-till (CT) but very few rice producers in Arkansas practice NT. The low adoption rate is most likely due to difficulties in management but also limited information on the profitability and risk of NT. Most rice producers are knowledgeable on NT costs savings but consider it less profitable due to yield reductions offsetting costs savings. This study evaluates production costs, crop yields, and economic risk of both NT and CT in five rice-based cropping systems (continuous rice, rice-soybean, rice-corn, rice-wheat, and rice-wheat-soybean-wheat). Yields, crop prices, and key input prices are simulated to create net return distributions. Stochastic efficiency with respect to a function (SERF) is used to evaluate profitability and risk efficiency. Results indicate that a risk-neutral and risk-averse producer in either NT or CT would prefer a rice-soybean rotation. NT would be preferred over CT in the rice-soybean rotation across all risk preferences. Overall, risk-neutral producers would prefer NT in four of five cropping systems while risk-averse producers would prefer NT in three of five cropping systems.cropping systems, rice, no-till, certainty equivalent, risk premium, Crop Production/Industries, Farm Management, Financial Economics, Land Economics/Use, Production Economics, Risk and Uncertainty,

Assessing the Impacts of Soil Carbon Credits and Risk on No-Till Rice Profitability

Rice is a major cash crop in eastern Arkansas, but most rice acres are intensively cultivated and grown on rented land. No-till is an effective means of sequestering soil carbon and reducing greenhouse gas emissions, and economic incentives exist for no-till in the form of carbon credits. Studies evaluating the economic potential of carbon credits focus on producers only and do not take into consideration the landlord’s perspective. This analysis evaluates the profitability and risk efficiency of no-till management and carbon credits in Arkansas rice production from the prospective if the landlord using simulation and stochastic efficiency with respect to a function (SERF). The results indicate carbon credits may have potential to enhance preference for no-till in rice production by risk-averse landlords.certainty equivalent, landlord, no-till, rice, risk premium, Farm Management, Production Economics, Risk and Uncertainty,

The Impacts of Farm Size and Economic Risk on No-Till Rice Whole-Farm Profitability

This study evaluated the impacts of farm size and stochastic return variability on no-till (NT) rice profitability at the whole-farm level. Mixed integer programming was used to determine optimal machinery complements, fuel consumption, and machinery labor requirements for conventional till (CT) and NT rice-soybean farms of 1200, 2400, and 3600 acres in size. Crop yields, market prices, and prices for key production inputs were simulated to construct stochastic whole-farm net returns for each farm size under CT and NT management, and both first and second degree stochastic dominance analysis were used to rank cumulative distribution functions of whole-farm returns according to specified risk preferences. The results indicate NT farms exhibit second degree stochastic dominance over CT farms regardless of farm size, and high input prices have less downward effect on the profitability of NT farms relative to CT farms.mixed integer programming, no-till, profitability, rice, risk, simulation, stochastic dominance, whole-farm, Farm Management, Production Economics, Risk and Uncertainty,

Microcomputer Intelligence for Technical Training (MITT): The evolution of an intelligent tutoring system

Microcomputer Intelligence for Technical Training (MITT) uses Intelligent Tutoring System (OTS) technology to deliver diagnostic training in a variety of complex technical domains. Over the past six years, MITT technology has been used to develop training systems for nuclear power plant diesel generator diagnosis, Space Shuttle fuel cell diagnosis, and message processing diagnosis for the Minuteman missile. Presented here is an overview of the MITT system, describing the evolution of the MITT software and the benefits of using the MITT system