Local and nonlocal parallel heat transport in general magnetic fields

A novel approach that enables the study of parallel transport in magnetized plasmas is presented. The method applies to general magnetic fields with local or nonlocal parallel closures. Temperature flattening in magnetic islands is accurately computed. For a wave number $k$, the fattening time scales as $\chi_{\parallel} \tau \sim k^{-\alpha}$ where $\chi$ is the parallel diffusivity, and $\alpha=1$ ($\alpha=2$) for non-local (local) transport. The fractal structure of the devil staircase temperature radial profile in weakly chaotic fields is resolved. In fully chaotic fields, the temperature exhibits self-similar evolution of the form $T=(\chi_{\parallel} t)^{-\gamma/2} L \left[ (\chi_{\parallel} t)^{-\gamma/2} \delta \psi \right]$, where $\delta \psi$ is a radial coordinate. In the local case, $f$ is Gaussian and the scaling is sub-diffusive, $\gamma=1/2$. In the non-local case, $f$ decays algebraically, $L (\eta) \sim \eta^{-3}$, and the scaling is diffusive, $\gamma=1$

Local and Regional Food Aid Procurement: An Assessment of Experience in Africa and Elements of Good Donor Practice

This Policy Synthesis is a summary of a longer report that discusses the procurement of food aid within the country or region where it is needed. Referred to as local and regional procurement – LRP – this practice has become a major element in multilateral food aid response over the past decade1. The paper examines the relevance and the rationale for using LRP, reviews the efficiency of World Food Program (WFP) LRP activities in Africa relative to inkind food aid and to prices in the markets in which it occurs, and proposes a classification of risks in LRP. It then discusses a range of potential LRP modalities, and proposes a framework of guiding principles, information systems, and operational procedures for responsible and effective LRP. Finally, the paper briefly discusses the implications of this research for expansion of U.S. government (USG) authority to engage in LRP.Crop Production/Industries, Farm Management,

Isabelita

https://digitalcommons.library.umaine.edu/mmb-ps/3487/thumbnail.jp

Generalized hydrodynamics of a dilute finite-sized particles suspension: Dynamic viscosity

We present a mesoscopic hydrodynamic description of the dynamics of colloidal suspensions. We consider the system as a gas of Brownian particles suspended in a Newtonian heat bath subjected to stationary non-equilibrium conditions imposed by a velocity field. Using results already obtained in previous studies in the field by means of a generalized Fokker-Planck equation, we obtain a set of coupled differential equations for the local diffusion current and the evolution of the total stress tensor. We find that the dynamic shear viscosity of the system contains contributions arising from the finite size of the particles.Comment: To appear in Physical Review

Children’s improvement of a motor response during backward falls through the implementation of a safe fall program

The World Health Organization has warned that, in children, the second cause of death from unintentional injuries are falls. The objective of this study was to analyze the motor response of primary schoolchildren when a backwards fall occurs. These analyses occurred before and after interventions of the Safe Fall program, which aims to teach safe and protected ways of backward falling. A quasi-experimental research design was used, with a sample of 122 Spanish (Sevillian) schoolchildren in the 10–12 age bracket. The INFOSECA ad-hoc observation scale was used for data collection: this scale registers 5 essential physical reactions throughout the process of a safe and protected backwards fall. After that, a number of descriptive, correlational and contrast statistics were applied. The value used in the McNemar test to establish statistical significance was p < 0.05. Results showed that over 85% of students had developed the competence to correctly perform all five physical motions that allow for a safer backward fall. The teaching of safe and protected techniques for falling backwards in child population in Primary Education is possible through the implementation of the Safe Fall program in Physical Education classes, which can help making falls safer, diminishing the risk and severity of the injuries they cause