An Incentive System for Salmonella Control in the Pork Supply Chain

This paper presents a dynamic principal-agent analysis of an incentive system for Salmonella control in the pork supply chain. The incentive system determines quality premiums to the producer, testing frequencies for hogs delivered, as well as charges to the producer for testing and penalties. Using cost estimates and technical parameters, we evaluate the cost effectiveness of plant and farm control measures and trade-offs between prevalence reduction and related costs and gains. We also assess the impact of ownership structure on incentive system parameters and performance for a wide range of prevalence threshold levels. Differences in control actions, bacteriological prevalence and the overall welfare gain for the chain are very small across ownership structures. Changes in the prevalence threshold level lead to substantial changes in the use of farm and plant control packages and performance measures.dynamic programming, food quality, principal-agent, Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,

Predicting Land Reclamation of Bond Released Surface Mines

Accurately measuring the recovery of released surface mines in the UnitedStates poses crucial challenges. This study aims to develop a prediction of land classification, that considers various environmental and coal mine variables. By utilizing this prediction, the researchers and environmentalists (specifically Appalachian Voices, the group heading this research) can better understand the relevant factors for successful reclamation. Efficient management of mine recovery is essential for environmental sustainability, regulatory compliance, and resource utilization. This study focuses on the Appalachian Forest area, which risks becoming a net carbon source (a place that emits more carbon than it absorbs) due to mine recovery. Machine and deep learning methods will be employed using Dynamic World land classification probabilities to identify areas requiring intervention and to provide ongoing insight into released mine conditions. The findings enable decision-making for prioritized reclamation and restoration measures

Report of the panel on geopotential fields: Magnetic field, section 9

The objective of the NASA Geodynamics program for magnetic field measurements is to study the physical state, processes and evolution of the Earth and its environment via interpretation of measurements of the near Earth magnetic field in conjunction with other geophysical data. The fields measured derive from sources in the core, the lithosphere, the ionosphere, and the magnetosphere. Panel recommendations include initiation of multi-decade long continuous scalar and vector measurements of the Earth's magnetic field by launching a five year satellite mission to measure the field to about 1 nT accuracy, improvement of our resolution of the lithographic component of the field by developing a low altitude satellite mission, and support of theoretical studies and continuing analysis of data to better understand the source physics and improve the modeling capabilities for different source regions

Segregation in Public Schools Through the Lens of Tiebout Theory: A case study of Oregon's open enrollment policy

In 2011 Oregon enacted a public education open enrollment policy that gives students and families the choice of what school to attend, regardless of district lines. Despite the lack of public information, this policy will sunset this school year unless it is further extended during legislative session. This paper attempts to discover possible negative externalities of the policy by analyzing segregation trends within Oregon and Washington for the years 2007-2017. We analyze how students sort themselves into isolated populations based on ethnic and socioeconomic factors by running an event study and multiple linear regressions. In summation, this research failed to identify a strong tie between open enrollment and segregation, but did conclude that sorting was occurring while schools also became more populated with students of low socioeconomic status. Therefore, if the policy succeeds in increasing efficiency and improves student and school outcomes, then legislators should consider extending the policy

High-efficiency, single-stage 7-kHz high-average-power ultrafast laser system

Includes bibliographical references (page 467).We demonstrate a simple and practical single-stage ultrafast laser amplifier system that operates at a repetition frequency from 1 to 10 kHz, with millijoule pulse energy and as much as 13 W of average power. The repetition rate can be adjusted continuously from 1 to 10 kHz by new all-solid-state pump laser technology. This is to our knowledge the highest average power ever obtained from a single-stage ultrafast laser amplifier system. This laser will significantly increase the average power and the repetition rate that is easily accessible for high-field experiments such as coherent x-ray generation or for laser-synchrotron studies

Nonlinear modes of clarinet-like musical instruments

The concept of nonlinear modes is applied in order to analyze the behavior of a model of woodwind reed instruments. Using a modal expansion of the impedance of the instrument, and by projecting the equation for the acoustic pressure on the normal modes of the air column, a system of second order ordinary differential equations is obtained. The equations are coupled through the nonlinear relation describing the volume flow of air through the reed channel in response to the pressure difference across the reed. The system is treated using an amplitude-phase formulation for nonlinear modes, where the frequency and damping functions, as well as the invariant manifolds in the phase space, are unknowns to be determined. The formulation gives, without explicit integration of the underlying ordinary differential equation, access to the transient, the limit cycle, its period and stability. The process is illustrated for a model reduced to three normal modes of the air column