14,164 research outputs found

    Holographic Dark Energy from Fluid/Gravity Duality Constraint by Cosmological Observations

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    In this paper, we obtain a holographic model of dark energy using the fluid/gravity duality. This model will be dual to a higher dimensional Schwarzschild black hole, and we would use fluid/gravity duality to relate to the parameters of this black hole to such a cosmological model. We will also analyze the thermodynamics of such a solution, and discuss the stability model. Finally, we use cosmological data to constraint the parametric space of this dark energy model. Thus, we will use observational data to perform cosmography for this holographic model based on fluid/gravity duality.Comment: 20 pages, 5 figures. accepted in Phys. Dark Uni

    Nonlocal Teleparallel Cosmology

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    Even though it is not possible to differentiate General Relativity from Teleparallel Gravity using classical experiments, it could be possible to discriminate between them by quantum gravitational effects. These effects have motivated the introduction of nonlocal deformations of General Relativity, and similar effects are also expected to occur in Teleparallel Gravity. Here, we study nonlocal deformations of Teleparallel Gravity along with its cosmological solutions. We observe that Nonlocal Teleparallel Gravity (like nonlocal General Relativity) is consistent with the present cosmological data obtained by SNe Ia + BAO + CC + H0H_0 observations. Along this track, future experiments probing nonlocal effects could be used to test whether General Relativity or Teleparallel Gravity give the most consistent picture of gravitational interaction.Comment: Accepted for publication in EPJC. Some small changes and references adde

    La serie estratigráfica de Navalperal. Serie tipo del Mesozoico Prebético en la región de Orcera-Siles (Provincia de Jaén)

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    In the Orcera-Siles area the type series is established for the Mesozoic of the Prebetic Realm, by describing the lithofacies and biofacies present in the different levels. It comprises terms from the Liassic up to the Senonian. Several lacunas are pointed out

    Girls in IT: How to develop talent and leverage support

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    The objectives of this panel are to inform the audience about national and regional initiatives developed by the National Center for Women & Information Technology (NCWIT) to reach out to middle and high school girls; learn from promising experiences in which the panelists have been directly involved; and discuss venues to scale and sustain efforts to increase women\u27s participation in technology careers. Panelists will describe their particular experiences, and discuss ways to utilize the Aspirations in Computing program to increase enrollment and retention of females in computing. A minimum of 30 minutes will be set aside for question and answer

    Medipix3 Demonstration and understanding of near ideal detector performance for 60 & 80 keV electrons

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    In our article we report first quantitative measurements of imaging performance for the current generation of hybrid pixel detector, Medipix3, as direct electron detector. Utilising beam energies of 60 & 80 keV, measurements of modulation transfer function (MTF) and detective quantum efficiency (DQE) have revealed that, in single pixel mode (SPM), energy threshold values can be chosen to maximize either the MTF or DQE, obtaining values near to, or even exceeding, those for an ideal detector. We have demonstrated that the Medipix3 charge summing mode (CSM) can deliver simultaneous, near ideal values of both MTF and DQE. To understand direct detection performance further we have characterized the detector response to single electron events, building an empirical model which can predict detector MTF and DQE performance based on energy threshold. Exemplifying our findings we demonstrate the Medipix3 imaging performance, recording a fully exposed electron diffraction pattern at 24-bit depth and images in SPM and CSM modes. Taken together our findings highlight that for transmission electron microscopy performed at low energies (energies <100 keV) thick hybrid pixel detectors provide an advantageous and alternative architecture for direct electron imagin

    Effects of counterion fluctuations in a polyelectrolyte brush

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    We investigate the effect of counterion fluctuations in a single polyelectrolyte brush in the absence of added salt by systematically expanding the counterion free energy about Poisson-Boltzmann mean field theory. We find that for strongly charged brushes, there is a collapse regime in which the brush height decreases with increasing charge on the polyelectrolyte chains. The transition to this collapsed regime is similar to the liquid-gas transition, which has a first-order line terminating at a critical point. We find that for monovalent counterions the transition is discontinuous in theta solvent, while for multivalent counterions the transition is generally continuous. For collapsed brushes, the brush height is not independent of grafting density as it is for osmotic brushes, but scales linear with it.Comment: 9 pages, 9 figure
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