3,148 research outputs found

    A Reappraisal of the Ascending Systems in Man, with Emphasis on the Medial Lemniscus

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    This volume of "Advances in Anatomy, Embryology and Cell Biology" is based on material assembled by Dr. Jaap H.R. Schoen who was one of the few neuroanatomists to apply the Nauta method to human material. Gaining insight in the consequences of longitudinal damage to the human spinal cord is necessary before reimplantation of the avulsed rootlets or an autologous transplant can be performed in man

    The Jang equation reduction of the spacetime positive energy theorem in dimensions less than eight

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    We extend the Jang equation proof of the positive energy theorem due to R. Schoen and S.-T. Yau from dimension n=3n=3 to dimensions 3n<83 \leq n <8. This requires us to address several technical difficulties that are not present when n=3n=3. The regularity and decay assumptions for the initial data sets to which our argument applies are weaker than those of R. Schoen and S.-T. Yau. In recent joint work with L.-H. Huang, D. Lee, and R. Schoen we have given a different proof of the full positive mass theorem in dimensions 3n<83 \leq n < 8. We pointed out that this theorem can alternatively be derived from our density argument and the positive energy theorem of the present paper.Comment: All comments welcome! Final version to appear in Comm. Math. Phy

    Mean-field density functional theory of ananoconfined classical, three-dimensional Heisenberg fluid. I. The role of molecularanchoring

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    This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 144, 194704 (2016) and may be found at https://doi.org/10.1063/1.4949330.In this work, we employ classical density functional theory (DFT) to investigate for the first time equilibrium properties of a Heisenberg fluid confined to nanoscopic slit pores of variable width. Within DFT pair correlations are treated at modified mean-field level. We consider three types of walls: hard ones, where the fluid-wall potential becomes infinite upon molecular contact but vanishes otherwise, and hard walls with superimposed short-range attraction with and without explicit orientation dependence. To model the distance dependence of the attractions, we employ a Yukawa potential. The orientation dependence is realized through anchoring of molecules at the substrates, i.e., an energetic discrimination of specific molecular orientations. If the walls are hard or attractive without specific anchoring, the results are “quasi-bulk”-like in that they can be linked to a confinement-induced reduction of the bulk mean field. In these cases, the precise nature of the walls is completely irrelevant at coexistence. Only for specific anchoring nontrivial features arise, because then the fluid-wall interaction potential affects the orientation distribution function in a nontrivial way and thus appears explicitly in the Euler-Lagrange equations to be solved for minima of the grand potential of coexisting phases.DFG, 65143814, GRK 1524: Self-Assembled Soft-Matter Nanostructures at Interface

    Positive mass theorem for the Paneitz-Branson operator

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    We prove that under suitable assumptions, the constant term in the Green function of the Paneitz-Branson operator on a compact Riemannian manifold (M,g)(M,g) is positive unless (M,g)(M,g) is conformally diffeomophic to the standard sphere. The proof is inspired by the positive mass theorem on spin manifolds by Ammann-Humbert.Comment: 7 page

    Bartenders Know Best: An In-Depth Analysis of the Impact of Tourism on Local Barbadian Culture

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    The purpose of my thesis is, through my own field research, to analyze the impact of tourism on local Barbadian culture. Caribbean tourism draws strong criticisms from anthropologists due to the region’s geographical location and environmental landscape, its history of colonialism, and the economic vulnerabilities that result from the wealth discrepancy between the local people and the tourists that vacation there. On the very small and densely populated island of Barbados, nearly every person is impacted by tourism. The focus of my ethnography is the cultural exchanges between guests and hosts, most specifically bartenders. A bar harbors many important elements of the Caribbean tourism literature; neocolonialism, service versus servitude, and authenticity and genuineness. Bartenders arguably have the most intimate and in-depth interactions with tourists, and their encounters with tourists are extremely representative of many issues surrounding Caribbean tourism, providing a good way to explore the impacts of tourism on local culture in a very micro setting. I use my knowledge of the culture and my first-hand interviews with bartenders to draw my own conclusions about the role of tourism in Barbados, how the locals feel about it, and whether it is as detrimental to social life as the literature suggests

    Kalanchoë blossfeldiana, a new host for Sonchus yellow net virus

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    The agent causing chlorotic spots in Kalanchoë blossfeldiana `Isabella¿ was investigated. A virus isolated from this naturally infected kalanchoë was mechanically transmissible to several indicator plants. Observation of suspension preparations in the electron microscope revealed rhabdovirus-like particles. On the basis of symptoms on indicator plants, serology, electron microscopy, molecular characterisation and back inoculation to K. blossfeldiana 'Isabella', the causal agent was identified as an isolate of Sonchus yellow net virus (SYNV). This is the first report of an ornamental plant species naturally infected by SYNV

    Black Holes with Zero Mass

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    We consider the spacetimes corresponding to static Global Monopoles with interior boundaries corresponding to a Black Hole Horizon and analyze the behavior of the appropriate ADM mass as a function of the horizon radius r_H. We find that for small enough r_H, this mass is negative as in the case of the regular global monopoles, but that for large enough r_H the mass becomes positive encountering an intermediate value for which we have a Black Hole with zero ADM mass.Comment: 10 pages, 2 ps figures, REVTeX, some minor change

    Disorder-induced pseudodiffusive transport in graphene nanoribbons.

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    We study the transition from ballistic to diffusive and localized transport in graphene nanoribbons in the presence of binary disorder, which can be generated by chemical adsorbates or substitutional doping. We show that the interplay between the induced average doping (arising from the nonzero average of the disorder) and impurity scattering modifies the traditional picture of phase-coherent transport. Close to the Dirac point, intrinsic evanescent modes produced by the impurities dominate transport at short lengths giving rise to a regime analogous to pseudodiffusive transport in clean graphene, but without the requirement of heavily doped contacts. This intrinsic pseudodiffusive regime precedes the traditional ballistic, diffusive, and localized regimes. The last two regimes exhibit a strongly modified effective number of propagating modes and a mean free path which becomes anomalously large close to the Dirac point

    Advanced composite applications for sub-micron biologically derived microstructures

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    A major thrust of advanced material development is in the area of self-assembled ultra-fine particulate based composites (micro-composites). The application of biologically derived, self-assembled microstructures to form advanced composite materials is discussed. Hollow 0.5 micron diameter cylindrical shaped microcylinders self-assemble from diacetylenic lipids. These microstructures have a multiplicity of potential applications in the material sciences. Exploratory development is proceeding in application areas such as controlled release for drug delivery, wound repair, and biofouling as well as composites for electronic and magnetic applications, and high power microwave cathodes
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