Dark energy with non-adiabatic sound speed: initial conditions and detectability

Assuming that the universe contains a dark energy fluid with a constant linear equation of state and a constant sound speed, we study the prospects of detecting dark energy perturbations using CMB data from Planck, cross-correlated with galaxy distribution maps from a survey like LSST. We update previous estimates by carrying a full exploration of the mock data likelihood for key fiducial models. We find that it will only be possible to exclude values of the sound speed very close to zero, while Planck data alone is not powerful enough for achieving any detection, even with lensing extraction. We also discuss the issue of initial conditions for dark energy perturbations in the radiation and matter epochs, generalizing the usual adiabatic conditions to include the sound speed effect. However, for most purposes, the existence of attractor solutions renders the perturbation evolution nearly independent of these initial conditions.Comment: 16 pages, 2 figures, version accepted in JCA

Utilización de fases de Anderson Rh(III)-hexamolibdato soportadas en γ-A2O3 como catalizadores para la eliminación de NO3- y NO2- en aguas

Se realizó la preparación de un catalizador empleando una fase de Anderson Rh(III)-hexamolibdato (RhMo6) y otro convencional obtenido por impregnación sucesiva de sales de ambos metales (RhMo), ambos soportados en γ-Al2O3. La caracterización de la fase pura y de los catalizadores se realizó utilizando DRX, Microscopía-SEM-EDS y Espectroscopía vibracional Raman Microprobe, con las cuales se observó la conservación de la fase cuando es soportada. La interacción heteropolianión-soporte se analizó mediante Reducción a Temperatura Programada. Este estudio permitió comprobar un efecto sinérgico entre el Rh y Mo, a través del cual la reducibilidad del Mo se vio promovida por la presencia del metal noble. Ambos catalizadores fueron empleados en la reacción de hidrogenación de NO3- a N2. Con el catalizador conteniendo la fase de Anderson (RhMo6/(G)) se logró la eliminación prácticamente total de NO3-, con una selectividad a N2 superior al 98%. Cuando la reacción se llevó a cabo en presencia de CO2, la actividad del catalizador RhMo6/(G) disminuyó, pero se logró que la selectividad del intermediario NO2- fuera cero y la selectividad hacia N2 aumentara hasta un 99.75%.Two Rh-Mo catalysts were prepared: one using a Rh(III)-hexamolibdate Anderson phase (RhMo6) and the other through conventional successive impregnation of both metal salts (RhMo). Both catalysts were supported on γ-Al2O3. Characterization of the pure phase and of the catalysts was performed using XRD, SEM-EDS-Microscopy and Raman Microprobe Vibrational Spectroscopy, which allowed observing the preservation of the phase structure when it was supported. The heteropolyanion-support interaction was analyzed by Temperature-programmed reduction. This study allowed us to check a synergic effect between Rh and Mo, through which Mo reducibility was promoted by the presence of the noble metal. Both catalysts were used in the NO3- to N2 hydrogenation reaction. With the catalyst containing the Anderson phase (RhMo6/(G)) the virtual elimination of NO3- was achieved, with a selectivity towards N2 higher than 98%. When the reaction was conducted in the presence of CO2, its activity decreased, but the selectivity towards NO2- was almost zero and the selectivity towards N2 increased to 99.75%

Five New Transits of the Super-Neptune HD 149026

We present new photometry of HD 149026 spanning five transits of its "super-Neptune" planet. In combination with previous data, we improve upon the determination of the planet-to-star radius ratio: R_p/R_star = 0.0491^{+0.0018}_{-0.0005}. We find the planetary radius to be 0.71 +/- 0.05 R_Jup, in accordance with previous theoretical models invoking a high metal abundance for the planet. The limiting error is the uncertainty in the stellar radius. Although we find agreement among four different ways of estimating the stellar radius, the uncertainty remains at 7%. We also present a refined transit ephemeris and a constraint on the orbital eccentricity and argument of pericenter, e cos(omega) = -0.0014 +/- 0.0012, based on the measured interval between primary and secondary transits.Comment: To appear in ApJ [19 pages

Gypsum-DL: an open-source program for preparing small-molecule libraries for structure-based virtual screening

Computational techniques such as structure-based virtual screening require carefully prepared 3D models of potential small-molecule ligands. Though powerful, existing commercial programs for virtual-library preparation have restrictive and/or expensive licenses. Freely available alternatives, though often effective, do not fully account for all possible ionization, tautomeric, and ring-conformational variants. We here present Gypsum-DL, a free, robust open-source program that addresses these challenges. As input, Gypsum-DL accepts virtual compound libraries in SMILES or flat SDF formats. For each molecule in the virtual library, it enumerates appropriate ionization, tautomeric, chiral, cis/trans isomeric, and ring-conformational forms. As output, Gypsum-DL produces an SDF file containing each molecular form, with 3D coordinates assigned. To demonstrate its utility, we processed 1558 molecules taken from the NCI Diversity Set VI and 56,608 molecules taken from a Distributed Drug Discovery (D3) combinatorial virtual library. We also used 4463 high-quality protein-ligand complexes from the PDBBind database to show that Gypsum-DL processing can improve virtual-screening pose prediction. Gypsum-DL is available free of charge under the terms of the Apache License, Version 2.0

Estudio del efecto del soporte en la eliminación de NO3-en aguas empleando catalizadores a base de Rh(III)-hexamolibdato

Se estudió la eliminación catalítica de NO3- en agua empleando catalizadores basados en heteropolioxometalatos de estructura tipo Anderson (RhMo6). Como soportes se utilizaron γ-Al2O3(G), un precursor de alúmina Al(OH)3 calcinado a 550°C (B), α-Al2O3(A) y SiO2(S). Todos los catalizadores fueron activos en la eliminación de NO3-. El orden de actividad decreciente fue el siguiente: RhMo6/G > RhMo6/S > RhMo6/A > RhMo6/B. Las diferencias observadas pueden ser asignadas a las diferentes características texturales entre los soportes. La interacción heteropolianión/soporte produce una superficie activa, en la que existe un efecto sinérgico entre los dos metales que favorece la actividad catalítica. Con respecto a la selectividad a N2 en todos los catalizadores soportados sobre alúminas con distintas características fue superior al 90%. Para el catalizador soportado sobre SiO2 la selectividad fue baja (64%). La menor selectividad a N2 puede deberse a que la SiO2 se comporta como intercambiador catiónico no favoreciendo la impregnación de un polianión como (RhMo6)

Wormholes as Basis for the Hilbert Space in Lorentzian Gravity

We carry out to completion the quantization of a Friedmann-Robertson-Walker model provided with a conformal scalar field, and of a Kantowski-Sachs spacetime minimally coupled to a massless scalar field. We prove that the Hilbert space determined by the reality conditions that correspond to Lorentzian gravity admits a basis of wormhole wave functions. This result implies that the vector space spanned by the quantum wormholes can be equipped with an unique inner product by demanding an adequate set of Lorentzian reality conditions, and that the Hilbert space of wormholes obtained in this way can be identified with the whole Hilbert space of physical states for Lorentzian gravity. In particular, all the normalizable quantum states can then be interpreted as superpositions of wormholes. For each of the models considered here, we finally show that the physical Hilbert space is separable by constructing a discrete orthonormal basis of wormhole solutions.Comment: 23 pages (Latex), Preprint IMAFF-RC-04-94, CGPG-94/5-