On transport in quantum Hall systems with constrictions

Motivated by recent experimental findings, we study transport in a simple phenomenological model of a quantum Hall edge system with a gate-voltage controlled constriction lowering the local filling factor. The current backscattered from the constriction is seen to arise from the matching of the properties of the edge-current excitations in the constriction ($\nu_{2}$) and bulk ($\nu_{1}$) regions. We develop a hydrodynamic theory for bosonic edge modes inspired by this model, finding that a competition between two tunneling process, related by a quasiparticle-quasihole symmetry, determines the fate of the low-bias transmission conductance. In this way, we find satisfactory explanations for many recent puzzling experimental results.Comment: 4 pages, 4 figure

Impact damage of composite plates

A simple model to study low velocity transverse impact of thin plates made of fiber-reinforced composite material, in particular T300/5208 graphite-epoxy was discussed. This model predicts the coefficient of restitution, which is a measure of the energy absorbed by the target during an impact event. The model is constructed on the assumption that the plate is inextensible in the fiber direction and that the material is incompressible in the z-direction. Such a plate essentially deforms by shear, hence this model neglects bending deformations of the plate. The coefficient of restitution is predicted to increase with large interlaminar shear strength and low transverse shear modulus of the laminate. Predictions are compared with the test results of impacted circular and rectangular clamped plates. Experimentally measured values of the coefficient of restitution are found to agree with the predicted values within a reasonable error

Integrating Stakeholder Input into Water Policy Development and Analysis

Agricultural water use is becoming an issue in much of the South due to population growth. Results of projects evaluating the impacts of conservation strategies aimed at reallocating or extending the life of water supplies are being met with great skepticism by stakeholder groups. In order to gain acceptance of results, it is essential that stakeholder groups be involved from the beginning in the identification of potential water conservation strategies and be kept informed throughout the project. The objective of this paper is to review previous attempts at involving stakeholders and the methodology currently being employed in the Ogallala Aquifer Project.conservation, Ogallala Aquifer, stakeholder, water policy, Agribusiness, Agricultural and Food Policy, Consumer/Household Economics, Q250, Q280,

Reducing Irrigation Water Demand with Cotton Production in West Texas

Due to declining water availability from the Ogallala Aquifer and increasing pumping costs, irrigation management options for cotton are analyzed. The study concludes that supplemental irrigation while meeting crop ET requirements is the most profitable option. Switching from corn to cotton production may reduce irrigation water demand in the region.Ogallala Aquifer, irrigated cotton, irrigation efficiency, water response function, input use optimization, ET, Texas Panhandle, Crop Production/Industries, Resource /Energy Economics and Policy,

EVALUATING THE IMPACT OF INTEGRATED PEST MANAGEMENT ON AGRICULTURE AND THE ENVIRONMENT IN THE TEXAS PANHANDLE

Agricultural producers in the Texas High Plains are facing the worst comparative economic conditions since 1913. Under these circumstances it is desirable to evaluate which programs are beneficial to agricultural producers and which ones are not. The concept of Integrated Pest Management was introduced to the Texas High Plains in 1976 and since then many IPM practices have been adopted for the four major crops; corn, cotton, sorghum, and wheat. The reduction in production cost is used as a measure of economic benefit and contingent valuation is used to estimate the value of the environmental benefits. The IPM practices, which have been adopted, reduce the production cost by more than $173 million per year. In addition the practices reduce environmental cost, as estimated by contingent valuation, by more than$99 million per year. The total value of the economic and environmental benefits accruing to the Texas High Plains exceeds $272 million per year.Crop Production/Industries,

Increase in soil organic carbon by agricultural intensification in northern China

Acknowledgements. This research was supported by National Natural Science Foundation of China (no. 31370527 and 31261140367) and the National Science and Technology Support Program of China (no. 2012BAD14B01-2). The authors gratefully thank the Huantai Agricultural Station for providing of the Soil Fertility Survey data. We also thank Zheng Liang from China Agricultural University for the soil sampling and analysis in 2011. Thanks are extended to Jessica Bellarby for helpful discussion and suggestions.Peer reviewedPublisher PD