Constraints from TcT_c and the isotope effect for MgB2_2

With the constraint that $T_c = 39$ K, as observed for MgB$_2$, we use the Eliashberg equations to compute possible allowed values of the isotope coefficient, $\beta$. We find that while the observed value $\beta= 0.32$ can be obtained in principle, it is difficult to reconcile a recently calculated spectral function with such a low observed value

Phylogeny, Ecology, And Heart Position In Snakes

The cardiovascular system of all animals is affected by gravitational pressure gradients, the intensity of which varies according to organismic features, behavior, and habitat occupied. A previous nonphylogenetic analysis of heart position in snakes-which often assume vertical postures-found the heart located 15%-25% of total body length from the head in terrestrial and arboreal species but 25%-45% in aquatic species. It was hypothesized that a more anterior heart in arboreal species served to reduce the hydrostatic blood pressure when these animals adopt vertical postures during climbing, whereas an anterior heart position would not be needed in aquatic habitats, where the effects of gravity are less pronounced. We analyzed a new data set of 155 species from five major families of Alethinophidia (one of the two major branches of snakes, the other being blind snakes, Scolecophidia) using both conventional and phylogenetically based statistical methods. General linear models regressing log10 snout-heart position on log10 snout-vent length (SVL), as well as dummy variables coding for habitat and/or clade, were compared using likelihood ratio tests and the Akaike Information Criterion. Heart distance to the tip of the snout scaled isometrically with SVL. In all instances, phylogenetic models that incorporated transformation of the branch lengths under an Ornstein-Uhlenbeck model of evolution (to mimic stabilizing selection) better fit the data as compared with their nonphylogenetic counterparts. The bestfit model predicting snake heart position included aspects of both habitat and clade and indicated that arboreal snakes in our study tend to have hearts placed more posteriorly, opposite the trend identified in previous studies. Phylogenetic signal in relative heart position was apparent both within and among clades. 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Brown in Black and White—Then and Now

The U.S. Supreme Court\u27s decision in the Brown v. Board of Education case was used as a point of reference to elaborate on the often divergent realities in education and sport for Black and White Americans. The impetus to integrate sport and the movement to integrate educational institutions in America were two separate yet often paralleled phenomena. It is typically argued that efforts to integrate educational institutions were about ensuring equitable access and opportunity. Less so, due to moral principles, integration in sports was more about winning and generating revenue. Still today, race-related divergences are reflected in education and sport. The intent of this article is to reflect on America\u27s education and sport histories (then) and highlight some present-day realities (now) as associated with the social construct of race, particularly for Black male students and athletes. © 2008 Sage Publications