A microscopic formulation of dynamical spin injection in ferromagnetic-nonmagnetic heterostructures

We develop a microscopic formulation of dynamical spin injection in heterostructure comprising nonmagnetic metals in contact with ferromagnets. The spin pumping current is expressed in terms of Green's function of the nonmagnetic metal attached to the ferromagnet where a precessing magnetization is induced. The formulation allows for the inclusion of spin-orbit coupling and disorder. The Green's functions involved in the expression for the current are expressed in real-space lattice coordinates and can thus be efficiently computed using recursive methods.Comment: 18 pages, 6 figure

Langmuir dark solitons in dense ultrarelativistic electron-positron gravito-plasma in pulsar magnetosphere

Nonlinear propagation of electrostatic modes in ultrarelativistic dense elelectron-positron gravito-plasma at the polar cap region of pulsar magnetosphere is considered. A nonlinear Schr\"{o}dinger equation is obtained from the reductive perturbation method which predicts the existence of Langmuir dark solitons. Relevance of the propagating dark solitons to the pulsar radio emission is discussed.Comment: 6 pages, 7 figures. Accepted for publication in Astrophysics and Space Science. arXiv admin note: text overlap with arXiv:astro-ph/9808047 by other authors without attributio

Does Farm Size and Specialization Matter for Productive Efficiency? Results from Kansas

In this article, we used bootstrap data envelopment analysis techniques to examine technical and scale efficiency scores for a balanced panel of 564 farms in Kansas for the period 1993–2007. The production technology is estimated under three different assumptions of returns to scale and the results are compared. Technical and scale efficiency is disaggregated by farm size and specialization. Our results suggest that farms are both scale and technically inefficient. On average, technical efficiency has deteriorated over the sample period. Technical efficiency varies directly by farm size and the differences are significant. Differences across farm specializations are not significant.bootstrap, data envelopment analysis, efficiency, farms, Farm Management, Production Economics, D24, Q12,

LABOR PRODUCTIVITY GROWTH AND CONVERGENCE IN THE KANSAS FARM SECTOR: A TRIPARTITE DECOMPOSITION USING THE DEA APPROACH

The objective of this paper is to analyze sources of labor productivity growth in the Kansas farm sector over the period 1993-2006 for a sample of 668 farms. The nonparametric production frontier method is used to decompose labor productivity growth into three components: (1) technological catch-up, (2) technological change, and (3) capital deepening. Kernel estimation methods are used to analyze the evolution of the entire distribution of labor productivity in the sample period. We find that labor productivity is primarily driven by capital deepening. On average, capital deepening is the main source of convergence in productivity and technical change is a source of divergence. We find little evidence of technological catch-up. The impact of the three components of labor productivity varies by farm size.labor productivity, growth, technological catch-up, technological change, capital deepening, Labor and Human Capital,

Methane-Carbon Dioxide: Conversions to Syngas and Hydrocarbons

This monograph describes the new innovation that has recently been developed for the CH4-CO2 conversions process. Optimization of CO2 reforming of methane to synthesis gas with the help of experimental design, empirical modeling and ANN modeling are developed for CORM in presence of oxygen. An overview on dynamic equilibrium analysis has shown that an increase of sweep factors induced more significant enhancement hydrogen permeation than permselective area. The NiO/CeO2 catalyst showed potential as catalyst for the CORM. The application of a hybrid catalytic DBD plasma reactor has the potential for the co-generation of C2+ hydrocarbons and synthesis gases from methane and carbon dioxide. Carbon dioxide as co-feed has important effects on the carbon suppression. It can be concluded that three factors, i.e. CH4/CO2 feed ratio, total feed flow rate, and discharge voltage, in the DBD plasma reactor system have significant effects on the reactor performance. The hybrid catalytic DBD plasma reactor is more suitable for CO2 OCM process than the conventional catalytic reactor over CaO-MnO/CeO2 catalyst. Further innovation and improvement of current research on CH4 and CO2 are required to increase conversion and selectivity and to commercialize the process