Statistical Theory of Spin Relaxation and Diffusion in Solids

A comprehensive theoretical description is given for the spin relaxation and diffusion in solids. The formulation is made in a general statistical-mechanical way. The method of the nonequilibrium statistical operator (NSO) developed by D. N. Zubarev is employed to analyze a relaxation dynamics of a spin subsystem. Perturbation of this subsystem in solids may produce a nonequilibrium state which is then relaxed to an equilibrium state due to the interaction between the particles or with a thermal bath (lattice). The generalized kinetic equations were derived previously for a system weakly coupled to a thermal bath to elucidate the nature of transport and relaxation processes. In this paper, these results are used to describe the relaxation and diffusion of nuclear spins in solids. The aim is to formulate a successive and coherent microscopic description of the nuclear magnetic relaxation and diffusion in solids. The nuclear spin-lattice relaxation is considered and the Gorter relation is derived. As an example, a theory of spin diffusion of the nuclear magnetic moment in dilute alloys (like Cu-Mn) is developed. It is shown that due to the dipolar interaction between host nuclear spins and impurity spins, a nonuniform distribution in the host nuclear spin system will occur and consequently the macroscopic relaxation time will be strongly determined by the spin diffusion. The explicit expressions for the relaxation time in certain physically relevant cases are given.Comment: 41 pages, 119 Refs. Corrected typos, added reference

NOAA Science Advisory Board, Review of National Center for Environmental Prediction Ocean Modeling

In response to a request from the National Oceanic & Atmospheric Administration (NOAA) National Weather Service, an Ocean Model Review Panel (ORMP) was commissioned by the NOAA Science Advisory Board (SAB), to address the following two-part Charge

Differential impacts of public health insurance expansions at the local level

Health insurance, Labor markets, Unemployment, Medicaid, SCHIP, I1, H7,

Worker preferences, sorting and aggregate patterns of health insurance coverage

To assess the performance of the employment-based health insurance system, it is necessary to understand how well workers sort into jobs that offer their desired mix of cash wages relative to benefits. However, few studies directly measure the extent of sorting. We quantify the prevalence of mismatches between workers’ preferences and firms’ insurance offerings by considering two types of mismatch: (1) workers who appear to desire coverage through their employer, but work for firms that do not offer coverage, and; (2) workers who appear not to desire coverage through their employer, but work for firms that offer coverage. Most workers (79.6%) enjoy labor market matches that appear consistent with their preferences. The remaining 20.4% of workers appear to be mismatched. For most of these mismatches, the primary consequence is lower wages than would be earned if individuals were better matched in the labor market. However, a minority of the identified mismatches appear to be “involuntarily uninsured” workers who would gain insurance if they were to find a better match. Extrapolating from the analysis sample, these involuntarily uninsured workers and their uninsured dependents may represent up to one in six uninsured individuals in the United States. Copyright Springer Science+Business Media, LLC 2006Health insurance, Employment, Labour market, Sorting, Un insurance,

Geography matters: state-level variation in children's oral health care access and oral health status

ObjectivesTo ascertain differences across states in children's oral health care access and oral health status and the factors that contribute to those differences.Study designObservational study using cross-sectional surveys.MethodsUsing the 2007 National Survey of Children's Health, we examined state variation in parents' report of children's oral health care access (absence of a preventive dental visit) and oral health status. We assessed the unadjusted prevalences of these outcomes, then adjusted with child-, family-, and neighbourhood-level variables using logistic regression; these results are presented directly and graphically. Using multilevel analysis, we then calculated the degree to which child-, family-, and community-level variables explained state variation. Finally, we quantified the influence of state-level variables on state variation.ResultsUnadjusted rates of no preventive dental care ranged 9.0-26.8% (mean 17.5%), with little impact of adjusting (10.3-26.7%). Almost 9% of the population had fair/poor oral health; unadjusted range 4.1-14.5%. Adjusting analyses affected fair/poor oral health more than access (5.7-10.7%). Child, family and community factors explained ∼¼ of the state variation in no preventive visit and ∼½ of fair/poor oral health. State-level factors further contributed to explaining up to a third of residual state variation.ConclusionGeography matters: where a child lives has a large impact on his or her access to oral health care and oral health status, even after adjusting for child, family, community, and state variables. As state-level variation persists, other factors and richer data are needed to clarify the variation and drive changes for more egalitarian and overall improved oral health