18,367 research outputs found

    Proof of a generalized Geroch conjecture for the hyperbolic Ernst equation

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    We enunciate and prove here a generalization of Geroch's famous conjecture concerning analytic solutions of the elliptic Ernst equation. Our generalization is stated for solutions of the hyperbolic Ernst equation that are not necessarily analytic, although it can be formulated also for solutions of the elliptic Ernst equation that are nowhere axis-accessible.Comment: 75 pages (plus optional table of contents). Sign errors in elliptic case equations (1A.13), (1A.15) and (1A.25) are corrected. Not relevant to proof contained in pape

    Better Team Hitches For South Dakota

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    South Dakota has 160,000 less horses now than it had seven years ago. This has resulted in an increasing demand for more definite information in regard to multiple hitches and how to make them. To some it might seem unnecessary to explain in detail the methods of constructing these different hitches and the importance of proper hitches on different farm implements because of the fact that farmers have worked horses for the past forty years and will continue to work them indefinitely. Nevertheless, it seems that many men today work horses to a great disadvantage because they, seemingly, have no better method

    Carbon nanotubes immersed in superfluid helium: the Impact of quantum confinement on wetting and capillary action

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    7 págs.; 5 figs.; 1 tab. ; Associated content mp4 video: http://pubs.acs.org/doi/suppl/10.1021/acs.jpclett.6b02414A recent experimental study [Ohba, Sci. Rep. 2016, 6, 28992] of gas adsorption on single-walled carbon nanotubes at temperatures between 2 and 5 K reported a quenched propagation of helium through carbon nanotubes with diameters below 7 Å despite the small kinetic diameter of helium atoms. After assessing the performance of a potential model for the He−nanotube interaction via ab initio calculations with density functional theorybased symmetry adapted perturbation theory, we apply orbital-free helium density functional theory to show that the counterintuitive experimental result is a consequence of the exceptionally high zeropoint energy of helium and its tendency to form spatially separated layers of helium upon adsorption at the lowest temperatures. Helium filling factors are derived for a series of carbon nanotubes and compared to the available experimental data. © 2016 American Chemical SocietyThis work has been supported by the COST Action CM1405 “Molecules in Motion (MOLIM)”. M.P.d.L.-C. gratefully acknowledges support from MINECO (Spain) under Grant MAT2016-75354-P and thanks the CTI (CSIC) and CESGA supercomputer facilities (Spain) for the resources provided.Peer reviewe
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