High field magnetotransport in composite conductors: the effective medium approximation revisited

The self consistent effective medium approximation (SEMA) is used to study three-dimensional random conducting composites under the influence of a strong magnetic field {\bf B}, in the case where all constituents exhibit isotropic response. Asymptotic analysis is used to obtain almost closed form results for the strong field magnetoresistance and Hall resistance in various types of two- and three-constituent isotropic mixtures for the entire range of compositions. Numerical solutions of the SEMA equations are also obtained, in some cases, and compared with those results. In two-constituent free-electron-metal/perfect-insulator mixtures, the magnetoresistance is asymptotically proportional to $|{\bf B}|$ at {\em all concentrations above the percolation threshold}. In three-constituent metal/insulator/superconductor mixtures a line of critical points is found, where the strong field magnetoresistance switches abruptly from saturating to non-saturating dependence on $|{\bf B}|$, at a certain value of the insulator-to-superconductor concentration ratio. This transition appears to be related to the phenomenon of anisotropic percolation.Comment: 16 pages, 3 figure

The Impact of Contaminated RR Lyrae/Globular Cluster Photometry on the Distance Scale

RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC2419, and NGC6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry.Comment: To appear in ApJ

Antidepressants and age

Antidepressants as a commodity have been remarkably little-studied by economists. This study shows in new data for 27 European countries that 8% of people (and 10% of those middle-aged) take antidepressants each year. The probability of antidepressant use is greatest among those who are middle-aged, female, unemployed, poorly educated, and divorced or separated. A hill-shaped age pattern is found. The adjusted probability of using antidepressants reaches a peak -- approximately doubling -- in people‟s late 40s. This finding is consistent with, and provides a new and independent form of corroboration of, recent claims in the research literature that human well-being follows a U-shape through life

International happiness

This paper describes the findings from a new, and intrinsically interdisciplinary, literature on happiness and human well-being. The paper focuses on international evidence. We report the patterns in modern data; we discuss what has been persuasively established and what has not; we suggest paths for future research. Looking ahead, our instinct is that this social-science research avenue will gradually merge with a related literature -- from the medical, epidemiological, and biological sciences -- on biomarkers and health. Nevertheless, we expect that intellectual convergence to happen slowly