High level of 3^3He polarization of 81\% Maintained in an on-beam 3^3He spin filter using SEOP

Maintaining high levels of 3He polarization over long periods of time is important to many areas of fundamental and particle beam physics. Long measurement times are often required in such experiments and the data quality is a function of the 3He polarization. This is the case for neutron scattering where the 3He can be used to analyze the spin of a scattered neutron beam and relatively small fluxes of polarized neutrons leads to experiment times longer than several days. Consequently the J\"ulich Centre for Neutron Science (JCNS) is developing spin-exchange optical pumping (SEOP) systems capable of polarizing the 3He gas in place on a typical neutron instrument. Using a polarizer device we constructed a high level of 3He polarization of 81 % \pm2% was maintained with good time stability. Such levels of polarization maintained over time will be able to reduce the measurement times for such experiments and eliminate time dependent data corrections.Comment: 4 pages 2 figure

NEW NATIONAL CENTER FOR VALUE-ADDED AGRICULTURE

Farm Management,

Heat and Moisture Conduction in Unsaturated Soils

Mathematical models are developed for the prediction of heat transfer from hot water pipes buried in the soil. Heat transfer in the absence of moisture transfer is described as a function of the difference between the temperature of the pipe and the temperature of the soil surface. The energy balance is used to determine the longitudinal temperature distribution of the water. The method is extended to describe a system of equally spaced, parallel buried pipes. Soil temperature profiles around the pipes are presented. The model is used to calculate the land area that can be heated by an underground piping system carrying cooling water from the condensers of a 1000 MW nuclear-electric plant. A new development of the phenomenological equations for coupled heat and moisture flow, based on the theory of Irreversible Thermodynamics, is presented. Solutions of the equations for boundary conditions representative of buried piping systems designed for simultaneous soil heating and irrigation are presented

Reputations, Market Structure, and the Choice of Quality Assurance Systems in the Food Industry

Many food traits desired by consumers are costly to provide and difficult to verify. A complicating factor is that delivered quality can only be affected stochastically by producers and imperfectly observed by consumers. Markets for these goods will emerge only if supplying firms can be trusted. We develop a repeated purchases model to explore how quality discoverability, market structure, nature of reputations, market premiums, and discount factors drive firm choice about the stringency of quality assurance systems designed to gain consumer trust. Reputation protection is key incentive for firms to invest in high-quality goods and quality assurance systems.

A MODEL OF PESTICIDE RESISTANCE AS A COMMON PROPERTY AND EXHAUSTIBLE RESOURCE

A dynamic farm production model analyzes the interaction between the externalities caused by pest mobility and the development of pesticide resistance, a nonrenewable resource, in the context of agricultural biotechnologies. The model measures the effect of farmers' myopic behavior and the impact of pest mobility on the path of resistance.biotechnology, common property resource, European Corn Borer, externalities, pesticide resistance, intertemporal optimization, Research and Development/Tech Change/Emerging Technologies,

OPTIMAL DESIGN OF A VOLUNTARY GREEN PAYMENT PROGRAM UNDER ASYMMETRIC INFORMATION

Green payment programs, where the government pays farmers directly for environmental benefits, are an alternative to the current method of achieving environmental benefits which restricts farming practices in exchange for deficiency payments. This article presents a voluntary green payment program using the principles of mechanism design under asymmetric information. Information asymmetry arises because the government knows only the distribution of farmersÂ’' production situations, rather than farm-specific information. The program is demonstrated with irrigated corn production in the Oklahoma high plains. A green payment program can reduce budget costs and pollution, while increasing the net social value of corn production.Environmental Economics and Policy,

OPTIMAL PESTICIDE USAGE WITH RESISTANCE AND ENDOGENOUS TECHNOLOGICAL CHANGE

This paper develops a model analyzing the first best policy for a social planner when pesticide use causes resistance, the level of pest infestation is heterogeneous among farmers, and the development of a backstop technology is an endogenous and uncertain process which depends on the cumulative amount of R&D effort.Crop Production/Industries,

Reputations, Market Structure, and the Choice of Quality Assurance Systems in the Food Industry

A repeated-purchases model is developed to explore the fundamental economic factors that lie behind the choice of different quality assurance systems and their associated degrees of stringency by firms. Differences in the quality discoverability of a sought-after attribute, market structure, attractiveness of a market, nature of reputations, and the value placed in the future are among the factors contributing to the implementation of widely diverse systems across participants in different markets. Close attention is paid to the role of reputations in providing the incentives for firms to deliver high-quality goods. We model three different scenarios - monopoly, duopoly with firm-specific reputations, and duopoly with industry-wide reputations - and compare the resulting welfare of processors and their customers. We also provide a rationale for the branding efforts of many firms to distinguish their products along the supply chain.quality assurance, reputations, repeated purchases, product quality, supply chain, value-added agriculture, imperfect information, Marketing,

MANAGING PEST RESISTANCE: THE POTENTIAL OF CROP ROTATIONS AND SHREDDING

The current debate over resistance management plans mandated by the Environmental Protection Agency for transgenic crops ignores management practices that are complementary to refuge schemes. A dynamic production model is developed that measures the costs and benefits of crop rotation and shredding in terms of delaying resistance to Bt corn.biotechnology, common property resource, crop rotation, European Corn Borer, externalities, insecticide resistance, integrated pest management, intertemporal optimization, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,