1,219 research outputs found

    Primera época del SPM

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    Habiéndose concluido la primera época del programa de movimientos propios estelares en base a galaxias (SPM), desarrollado en su aspecto observacional en El Leóncito, se presenta un análisis de los campos fotografiados, placas empleadas y detalles de interés general. Se esboza, además, lo proyectado para la segunda época.Asociación Argentina de Astronomí

    Current practices in managing acutely disturbed patients at three hospitals in Rio de Janeiro-Brazil: a prevalence study

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    The medical management of aggressive and violent behaviour is a critical situation for which there is little evidence. In order to prepare for a randomised trial, due to start in the psychiatric emergency rooms of Rio de Janeiro in 2001, a survey of current practice was necessary. A seven day survey of pharmacological management of aggressive people with psychosis in the emergency rooms of all four public psychiatric hospitals in Rio de Janeiro, Brazil. In one hospital data were not available. Of the 764 people with psychosis attending these ERs, 74 were given IM medication for rapid tranquillisation (9.7%, 2.1/week/100,000). A haloperidol-promethazine mix (with or without other drugs) was used for the majority of patients (83%). The haloperidol-promethazine mix, given intramuscularly for rapid tranquilization, is prevalent in Rio, where it is considered both safe and efficient. However, scientific evaluation of all pharmacological approaches to rapid tranquilization of psychotic people is inadequate or incomplete and a randomized trial of IM haloperidol-promethazine is overdue

    A new viable region of the inert doublet model

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    The inert doublet model, a minimal extension of the Standard Model by a second Higgs doublet, is one of the simplest and most attractive scenarios that can explain the dark matter. In this paper, we demonstrate the existence of a new viable region of the inert doublet model featuring dark matter masses between Mw and about 160 GeV. Along this previously overlooked region of the parameter space, the correct relic density is obtained thanks to cancellations between different diagrams contributing to dark matter annihilation into gauge bosons (W+W- and ZZ). First, we explain how these cancellations come about and show several examples illustrating the effect of the parameters of the model on the cancellations themselves and on the predicted relic density. Then, we perform a full scan of the new viable region and analyze it in detail by projecting it onto several two-dimensional planes. Finally, the prospects for the direct and the indirect detection of inert Higgs dark matter within this new viable region are studied. We find that present direct detection bounds already rule out a fraction of the new parameter space and that future direct detection experiments, such as Xenon100, will easily probe the remaining part in its entirety.Comment: 27 pages, 16 figure

    Vacuum Annealed Cu contacts for graphene electronics

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    We present transfer-length-method measurements of the contact resistance between Cu and graphene, and a method to significantly reduce the contact resistance by vacuum annealing. Even in samples with heavily contaminated contacts, the contacts display very low contact resistance post annealing. Due to the common use of Cu, and it's low chemical reactivity with graphene, thermal annealing will be important for future graphene devices requiring non-perturbing contacts with low contact resistance.Comment: 8 pages, 3 figure

    Scalar Multiplet Dark Matter

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    We perform a systematic study of the phenomenology associated to models where the dark matter consists in the neutral component of a scalar SU(2)_L n-uplet, up to n=7. If one includes only the pure gauge induced annihilation cross-sections it is known that such particles provide good dark matter candidates, leading to the observed dark matter relic abundance for a particular value of their mass around the TeV scale. We show that these values actually become ranges of values -which we determine- if one takes into account the annihilations induced by the various scalar couplings appearing in these models. This leads to predictions for both direct and indirect detection signatures as a function of the dark matter mass within these ranges. Both can be largely enhanced by the quartic coupling contributions. We also explain how, if one adds right-handed neutrinos to the scalar doublet case, the results of this analysis allow to have altogether a viable dark matter candidate, successful generation of neutrino masses, and leptogenesis in a particularly minimal way with all new physics at the TeV scale.Comment: 43 pages, 20 figure

    Dibaryon Spectroscopy

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    The AdS/CFT correspondence relates dibaryons in superconformal gauge theories to holomorphic curves in Kaehler-Einstein surfaces. The degree of the holomorphic curves is proportional to the gauge theory conformal dimension of the dibaryons. Moreover, the number of holomorphic curves should match, in an appropriately defined sense, the number of dibaryons. Using AdS/CFT backgrounds built from the generalized conifolds of Gubser, Shatashvili, and Nekrasov (1999), we show that the gauge theory prediction for the dimension of dibaryonic operators does indeed match the degree of the corresponding holomorphic curves. For AdS/CFT backgrounds built from cones over del Pezzo surfaces, we are able to match the degree of the curves to the conformal dimension of dibaryons for the n'th del Pezzo surface, n=1,2,...,6. Also, for the del Pezzos and the A_k type generalized conifolds, for the dibaryons of smallest conformal dimension, we are able to match the number of holomorphic curves with the number of possible dibaryon operators from gauge theory.Comment: 30 pages, 6 figures, corrected refs; v3 typos correcte

    Duality cascades and duality walls

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    We recast the phenomenon of duality cascades in terms of the Cartan matrix associated to the quiver gauge theories appearing in the cascade. In this language, Seiberg dualities for the different gauge factors correspond to Weyl reflections. We argue that the UV behavior of different duality cascades depends markedly on whether the Cartan matrix is affine ADE or not. In particular, we find examples of duality cascades that can't be continued after a finite energy scale, reaching a "duality wall", in terminology due to M. Strassler. For these duality cascades, we suggest the existence of a UV completion in terms of a little string theory.Comment: harvmac, 24 pages, 4 figures. v2: references added. v3: reference adde

    Decoherence and entanglement degradation of a qubit-qutrit system in non-inertial frames

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    We study the effect of decoherence on a qubit-qutrit system under the influence of global, local and multilocal decoherence in non-inertial frames. We show that the entanglement sudden death can be avoided in non-inertial frames in the presence of amplitude damping, depolarizing and phase damping channels. However, degradation of entanglement is seen due to Unruh effect. It is shown that for lower level of decoherence, the depolarizing channel degrades the entanglement more heavily as compared to the amplitude damping and phase damping channels. However, for higher values of decoherence parameters, amplitude damping channel heavily degrades the entanglement of the hybrid system. Further more, no ESD is seen for any value of Rob's acceleration.Comment: 16 pages, 5 .eps figures, 1 table; Quantum Information Processing, published online, 5 July, 201

    Potential Impacts on Accessibility and Consumer Surplus of Improvements of the European Railway System

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    AbstractIt is widely accepted that “transport infrastructure endowment influences competiveness of a Region; the provision of investment in transport infrastructure entails positive effects on productivity and growth, even if on the other side, heavy infrastructures (as railway lines) could affect negatively on the environment” (5th Cohesion Report, 2010). This article aims to explore the potential impact of improvements of the passenger rail network in order to evaluate how these could potentially increase accessibility and consumer surplus in EU regions; it summarizes the results of the model simulations carried out with a combination of the TRANSTOOLS rail network and the assignment module of Traffic Analyst.Three different scenarios have been tested by changing speeds on the whole network. The post-processing analysis has been carried out with utilities developed in Matlab, while the results for each zone (at NUTS3 level) have also been reported in easy-to-read ArcGIS maps. The outcomes provide insight into how the demand for passenger rail transport would react and where the highest benefits and costs, in terms of accessibility and consumer surplus gains, can be expected. This information, in turn, can be useful for the prioritization of investment needs and the identification of parts of the rail passenger market where new demand may be generated
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