Predicting C-H/π\pi interactions with nonlocal density functional theory

We examine the performance of a recently developed nonlocal density functional in predicting a model noncovalent interaction, the weak bond between an aromatic $\pi$ system and an aliphatic C-H group. The new functional is a significant improvement over traditional density functionals, providing results which compare favorably to high-level quantum-chemistry techniques but at considerably lower computational cost. Interaction energies in several model C-H/$\pi$ systems are in generally good agreement with coupled-cluster calculations, though equilibrium distances are consistently overpredicted when using the revPBE functional for exchange. The new functional correctly predicts changes in energy upon addition of halogen substituents.Comment: 5 pages, 4 figure

“Writing a Name in the Sky”: Rancière, Cavell, and the Possibility of Egalitarian Inscription

Democratic theory is often portrayed as torn between two moments: that of disruption of rule, and the ordinary, ongoing institutionalization of politics. This dualism also marks contemporary democratic theory. In Jacques Rancière's theory of politics it takes the form of an emphasis on the ruptural qualities of the staging of novel democratic demands and the reconfiguration of the space of political argument. The reconfiguration of existing political imaginaries depends upon a moment of inscription, which remains underdeveloped in Rancière's work. Arguing that the possibility of inscription is indeed thematized in Rancière's more historical writings, but is often ignored by commentators, this article seeks to draw out the implications of a focus on inscription for democratic theory and practice. To flesh out this account, the article draws on Cavell's writings on exemplarity and the role of exemplars in fostering both critical reflection and the imagination of alternatives. The focus on such exemplars and an aversive, nonconformist ethos together facilitate a better understanding of what is required for such novel demands to be acknowledged and inscribed into democratic life.</jats:p

The masked demos: Associational anonymity and democratic practice

The increased use of anonymous digital platforms raises substantive concerns about accountability in digital spaces. However, contemporary evaluations of anonymity focus too narrowly on its protective function: its ability to protect a diversity of speakers and ideas. Drawing on two examples of anonymous political engagements – Publius’s writing of the Federalist Papers and college students’ use of the social media platform Yik Yak – we develop an account of anonymity’s associational function: the processes by which people generate and negotiate collective identities, discussions, and actions in wider publics. As we argue, anonymity’s associational function can (1) generate conditions under which individuals develop collective interests and identities to foster collective action, and (2) enable novel interactions between these individuals and communities and the larger publics of which they are part. We conclude with a discussion of how attention to associational anonymity can contribute to a more nuanced account of democracy in practice

Dynamic Measurements of Plastic Deformation in a Water-Filled Aluminum Tube in Response to Detonation of a Small Explosives Charge

Experiments have been conducted to benchmark computer code calculations for the dynamic interaction of explosions in water with structures. Aluminum cylinders with a length slightly more than twice their diameter were oriented vertically, sealed on the bottom by a thin plastic sheet, and filled with distilled water. An explosive charge suspended in the center of the tube plastically deformed but did not rupture the wall. Tube wall velocity, displacement, and strain were directly measured. The agreement among the three sets of dynamic data and the agreement of the terminal displacement measurements with the residual deformation were excellent