Intrinsic structure of two-phonon states in the interacting boson model

A general study of excitations up to two-phonon states is carried out using the intrinsic-state formalism of the Interacting Boson Model (IBM). Spectra and transitions for the different dynamical symmetries are analyzed and the correspondence with states in the laboratory frame is established. The influence of multi-phonon states is discussed. The approach is useful in problems where the complexity of the IBM spectrum renders the analysis in the laboratory frame difficult.Comment: 22 pages, TeX (ReVTeX). 7 eps figures. Submitted to Nucl. Phys.

Photonic chip interconnects and integrated polarization management for coherent communication

En este trabajo se han expuesto diversas aportaciones originales, entre las que cabe destacar el desarrollo de redes de difracción eficientes para el acoplo chip-fibra, el diseño de rotadores de polarización integrados de grandes tolerancias a errores de fabricación o el diseño de un receptor para comunicaciones coherentes basadas en multiplexación por polarización que no requiere de rotadores ni de separadores de polarización

Testing the Unification Model for AGN in the Infrared: are the obscuring tori of Type 1 and 2 Seyferts different?

We present new mid-infrared (MIR) imaging data for three Type-1 Seyfert galaxies obtained with T-ReCS on the Gemini-South Telescope at subarcsecond resolution. Our aim is to enlarge the sample studied in a previous work to compare the properties of Type-1 and Type-2 Seyfert tori using clumpy torus models and a Bayesian approach to fit the infrared nuclear spectral energy distributions (SEDs). Thus, the sample considered here comprises 7 Type-1, 11 Type-2, and 3 intermediate-type Seyferts. The unresolved IR emission of the Seyfert 1 galaxies can be reproduced by a combination of dust heated by the central engine and direct AGN emission, while for the Seyfert 2 nuclei only dust emission is considered. These dusty tori have physical sizes smaller than 6 pc radius, as derived from our fits. Unification schemes of AGN account for a variety of observational differences in terms of viewing geometry. However, we find evidence that strong unification may not hold, and that the immediate dusty surroundings of Type-1 and Type-2 Seyfert nuclei are intrinsically different. The Type-2 tori studied here are broader, have more clumps, and these clumps have lower optical depths than those of Type-1 tori. The larger the covering factor of the torus, the smaller the probability of having direct view of the AGN, and vice-versa. In our sample, Seyfert 2 tori have larger covering factors and smaller escape probabilities than those of Seyfert 1. All the previous differences are significant according to the Kullback-Leibler divergence. Thus, on the basis of the results presented here, the classification of a Seyfert galaxy as a Type-1 or Type-2 depends more on the intrinsic properties of the torus rather than on its mere inclination towards us, in contradiction with the simplest unification model.Comment: 21 pages, 14 figures, Appendix including supplementary figures. Accepted by Ap

Spin-orbit induced mixed-spin ground state in RRNiO3_3 perovskites probed by XAS: new insight into the metal to insulator transition

We report on a Ni L$_{2,3}$ edges x-ray absorption spectroscopy (XAS) study in $R$NiO$_3$ perovskites. These compounds exhibit a metal to insulator ($MI$) transition as temperature decreases. The L$_{3}$ edge presents a clear splitting in the insulating state, associated to a less hybridized ground state. Using charge transfer multiplet calculations, we establish the importance of the crystal field and 3d spin-orbit coupling to create a mixed-spin ground state. We explain the $MI$ transition in $R$NiO$_3$ perovskites in terms of modifications in the Ni$^{3+}$ crystal field splitting that induces a spin transition from an essentially low-spin (LS) to a mixed-spin state.Comment: 4 pages, 4 figures, accepted as PRB - Rapid Comm. Dez. 200

The Infrared Nuclear Emission of Seyfert Galaxies on Parsec Scales: Testing the Clumpy Torus models

We present subarcsecond resolution mid-infrared (mid-IR) photometry in the wavelength range from 8 to 20 micron of eighteen Seyfert galaxies, reporting high spatial resolution nuclear fluxes for the entire sample. We construct spectral energy distributions (SEDs) that the AGN dominates adding near-IR measurements from the literature at similar angular resolution. The IR SEDs of intermediate-type Seyferts are flatter and present higher 10 to 18 micron ratios than those of Seyfert 2. We fit the individual SEDs with clumpy torus models using the in-house-developed BayesClumpy tool. The models reproduce the high spatial resolution measurements. Regardless of the Seyfert type, even with high spatial resolution data, near- to mid-IR SED fitting poorly constrains the radial extent of the torus. For the Seyfert 2, we find that edge-on geometries are more probable than face-on views, with a number of clouds along equatorial rays of N = 5-15. The 10 micron silicate feature is generally modeled in shallow absorption. For the intermediate-type Seyferts, N and the inclination angle of the torus are lower than those of the Seyfert 2 nuclei, with the silicate feature appearing in weak emission or absent. The columns of material responsible for the X-ray absorption are larger than those inferred from the model fits for most of the galaxies, which is consistent with X-ray absorbing gas being located within the dust sublimation radius whereas the mid-IR flux arises from an area farther from the accretion disc. The fits yield both the bolometric luminosity of the intrinsic AGN and the torus integrated luminosity, from which we derive the reprocessing efficiency of the torus. In the models, the outer radial extent of the torus scales with the AGN luminosity, and we find the tori to be confined to scales less than 5 pc.Comment: 26 pages, 8 figures, 9 tables. Accepted for publication in Ap

Resultados en recambios de cotilo mediante la técnica de Sloof: nuestra experiencia

Objetivos: osteolisis es un importante problema para el cirujano en los recambios de cotilo. Hoy en día existen múltiples técnicas para intentar subsanar este defecto. Una de ellas es la Técnica de Sloof. Hemos querido mostrar nuestros resultados con esta técnica. Material y métodos: Se revisaron 20 pacientes entre 1999 y octubre 2003 clasificados con la escala de Paprosky intervenidos con esta técnica. Se valoraron resultados en cuanto a mejoría del dolor, funcionalidad, actividad y consolidación radiológica, usando para ello las escalas de Harris. Resultados: La mayoría de los pacientes obtuvieron una mejoría significativa del dolor y una función suficiente como para realizar su vida de forma independiente, consiguiéndose la incorporación del injerto en todos los casos.Aim: The osteolysis of the pelvis is an important problem for the surgeon associated with acetabular revision. Nowadays there are many techniques which try to solve such a defect. One of them is the Sloof’s technique. We have shown our results using this technique. Materials and Methods: Study of 20 patients from 1999 to October 2003 who were treated with this technique. Results related to pain-free, functionality, activity and radiology consolidation, have been valued using Harris scale. Results: Most of patients got a significant pain diminution and a function enough to achieve their lives in a self- sufficiency way. We have obtained the graft incorporation in all the cases

A general approach for robust integrated polarization rotators

Integrated polarization rotators suffer from very high sensitivity to fabrication errors. A polarization rotator scheme that substantially increases fabrication tolerances is proposed. In the proposed scheme, two tunable polarization phase shifters are used to connect three rotator waveguide sections. By means of properly setting the polarization phase shifters, fabrication errors are compensated and perfect polarization rotation is achieved. Analytical conditions are shown that determine the maximum deviation that can be corrected with the proposed scheme. A design example is discussed, where the thermo-optic effect is used to provide the required tunable polarization phase shifting. Calculated 40dB extinction ratio is shown in presence of fabrication errors that would yield a 4dB extinction ratio in the conventional approach. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.The authors want to aknowledge Universidad de Málaga alaga, Campus de Excelencia Internacional Andalucia Tech for their support

Colorless devices and reception techniques for polarization multiplexed communications

Future optical networks call for flexible, high performance and low cost coherent optical receivers. We present here several advances towards such receivers, including integrated optical couplers with ultra-broad bandwidth, as well as novel reception techniques and architectures that will enable high performance coherent reception without filtering and polarization splitting elements.Universidad de Málaga - Campus de Excelencia Internacional Andalucía Tech. Spanish Ministry of Science under project TEC2013-46917-C2-1-