Smectic and columnar ordering in length-polydisperse fluids of parallel hard cylinders

We apply a recently proposed density functional for mixtures of parallel hard cylinders, based on Rosenfeld's fundamental measure theory, to study the effect of length-polydispersity on the relative stability between the smectic and columnar liquid crystal phases.To this purpose we derive from this functional an expression for the direct correlation function and use it to perform a bifurcation analysis. We compare the results with those obtained with a second and a third virial approximation of this function. All three approximations lead to the same conclusion: there is a terminal polydispersity beyond which the smectic phase is less stable than the columnar phase. This result is in agreement with previous Monte Carlo simulations conducted on a freely rotating length-polydisperse hard spherocylinder fluid, although the theories always overestimate the terminal polydispersity because the nematic-columnar phase transition is first order and exhibits a wide coexistence gap. Both, the fundamental-measure functional and the third virial approximation, predict a metastable nematic-nematic demixing. Conversely, according to second virial approximation this demixing might be stable at high values of the polydispersity, something that is observed neither in simulations nor in experiments. The results of the fundamental-measure functional are quantitatively superior to those obtained from the other two approximations. Thus this functional provides a promising route to map out the full phase diagram of this system.Comment: 7 pages, 2 figure

The Role of Social Perspective-Taking in Developing Students\u27 Leadership Capacities

This study examined relationships between social perspective-taking (SPT) and the individual, group, and societal domains of socially responsible leadership. SPT is a higher-order cognitive skill linked to moral development and social coordination, but never empirically connected to leadership development. Analyses determined SPT has a strong direct effect on group-level leadership values and an indirect effect on societallevel leadership values. Results offer critical new insights into directionality in the social change model

Mapping the business systems of 61 major economies: a taxonomy and implications for varieties of capitalism and business systems research

Efforts to build a universal theory of the world’s business systems require empirical grounding in an understanding of the variety that need explaining. To support such theorizing, we analyzed the institutional structures of 61 major economies, accounting for 93.5% of 2013 world GDP at purchasing power parity. We found nine main types of business systems: Highly Coordinated, Coordinated Market, Liberal Market, European Peripheral, Advanced Emerging, Advanced City, Arab Oil-Based, Emerging, and Socialist Economies. Our findings illustrate the need to go beyond the Varieties of Capitalism and Business Systems frameworks; provide empirical support for the CME versus LME dichotomy for part of the OECD; identify some of the business systems proposed recently as sub-types of larger clusters; indicate that institutional diversity may increase with development level; and cast doubt on the notions of state-led and family-led capitalism as types of business systems. Our discussion further suggests numerous avenues for theory development and empirical research

Orbital current mode in elliptical quantum dots

An orbital current mode peculiar to deformed quantum dots is theoretically investigated; first by using a simple model that allows to interpret analytically its main characteristics, and second, by numerically solving the microscopic equations of time evolution after an initial perturbation within the time-dependent local-spin-density approximation. Results for different deformations and sizes are shown.Comment: 4 REVTEX pages, 4 PDF figures, accepted in PRB:R