3,815 research outputs found

    Dynamical spacetimes and gravitational radiation in a Fully Constrained Formulation

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    This contribution summarizes the recent work carried out to analyze the behavior of the hyperbolic sector of the Fully Constrained Formulation (FCF) derived in Bonazzola et al. 2004. The numerical experiments presented here allows one to be confident in the performances of the upgraded version of CoCoNuT's code by replacing the Conformally Flat Condition (CFC) approximation of the Einstein equations by the FCF.Comment: 4 pages, 7 figures. Accepted for publication in Journal of Physics: Conference Series, Proceedings of the 8th Edoardo Amaldi Conference on Gravitational Wave

    The Effect of Zonally Asymmetric Ozone Heating on the Northern Hemisphere Winter Polar Stratosphere

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    [1] Previous modeling studies have found significant differences in winter extratropical stratospheric temperatures depending on the presence or absence of zonally asymmetric ozone heating (ZAOH), yet the physical mechanism causing these differences has not been fully explained. The present study describes the effect of ZAOH on the dynamics of the Northern Hemisphere extratropical stratosphere using an ensemble of free-running atmospheric general circulation model simulations over the 1 December - 31 March period. We find that the simulations including ZAOH produce a significantly warmer and weaker stratospheric polar vortex in mid-February due to more frequent major stratospheric sudden warmings compared to the simulations using only zonal mean ozone heating. This is due to regions of enhanced Eliassen-Palm flux convergence found in the region between 40°N–70°N latitude and 10–0.05 hPa. These results are consistent with changes in the propagation of planetary waves in the presence of ZAOH predicted by an ozone-modified refractive index

    Inference of mixed information in Formal Concept Analysis

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    Negative information can be considered twofold: by means of a negation operator or by capturing the absence of information. In this second approach, a new framework have to be developed: from the syntax to the semantics, including the management of such generalized knowledge representation. In this work we traverse all these issues in the framework of formal concept analysis, introducing a new set of inference rules to manage mixed (positive and negative) attributes.TIN2014-59471-P of the Science and Innovation Ministry of Spain, co-funded by the European Regional Development Fund (ERDF). UNIVERSIDAD DE MÁLAGA. Campus de Excelencia Internacional Andalucía Tech

    Octahedral tilting, monoclinic phase and the phase diagram of PZT

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    Anelastic and dielectric spectroscopy measurements on PZT close to the morphotropic (MPB) and antiferroelectric boundaries provide new insight in some controversial aspects of its phase diagram. No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, in agreement with recent structural studies supporting a coexistence of the two phases over a broad composition range x < 0.5, with the fraction of M increasing toward the MPB. It is also discussed why the observed maximum of elastic compliance appears to be due to a rotational instability of the polarisation and therefore cannot be explained by extrinsic softening from finely twinned R phase alone, but indicates the presence also of M phase, not necessarily homogeneous. A new diffuse transition is found within the ferroelectric phase near x ~ 0.1, at a temperature T_IT higher than the well established boundary T_T to the phase with tilted octahedra. It is proposed that around T_IT the octahedra start rotating in a disordered manner and finally become ordered below T_T. In this interpretation, the onset temperature for octahedral tilting monotonically increases up to the antiferroelectric transition of PbZrO3, and the depression of T_T(x) below x = 0.18 would be a consequence of the partial relieve of the mismatch between the cation radii with the initial stage of tilting below T_IT.Comment: submitted to J. Phys.: Condens. Matte

    Chiral Superconducting Membranes

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    We develop the dynamics of the chiral superconducting membranes (with null current) in an alternative geometric approach either making a Lagrangian description and a Hamiltonian point of view. Besides of this, we show the equivalence of the resulting descriptions to the one known Dirac-Nambu-Goto (DNG) case. Integrability for chiral string model is obtained using a proposed light-cone gauge. In a similar way, domain walls are integrated by means of a simple ansatz. We compare the results with recently works appeared in the literature.Comment: Latex file, 17 pages, no figures. Improved version, typos corrected, Comments and references adde

    Strichartz Estimates for the Vibrating Plate Equation

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    We study the dispersive properties of the linear vibrating plate (LVP) equation. Splitting it into two Schr\"odinger-type equations we show its close relation with the Schr\"odinger equation. Then, the homogeneous Sobolev spaces appear to be the natural setting to show Strichartz-type estimates for the LVP equation. By showing a Kato-Ponce inequality for homogeneous Sobolev spaces we prove the well-posedness of the Cauchy problem for the LVP equation with time-dependent potentials. Finally, we exhibit the sharpness of our results. This is achieved by finding a suitable solution for the stationary homogeneous vibrating plate equation.Comment: 18 pages, 4 figures, some misprints correcte

    Exploración artroscópica de la articulación del codo del perro : diagnóstico del proceso coronoides medial fragmentado (FCP)

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    En los últimos años, la artroscopia se ha convertido en una técnica de gran utilidad en el diagnóstico de las diferentes lesiones osteo- condrales del perro. En este trabajo explicamos el uso de la técnica artroscópica en la exploración de la articulación del codo; al mismo tiempo describimos el instrumental necesario. Durante un periodo de un año, hemos realizado 8 artroscopias diagnósticas en 8 perros (8 codos operados) con síntomas de cojera por lesiones a nivel de la articulacíóndel codo, diagnosticando 6 casos de FCP (proceso coronoides medial fragmentado). En todos los casos, la artrotomía confirmó los hallazgos artroscópicos. Además, con este estudio queremos demostrar la eficacia de la técnica artroscópica en el diagnóstico, no sólo del FCP, sino de su importancia en la evaluación de los cambios inflamatorios de la membrana sinovial (sinovitis)y del cartílago articular, lesiones estas últimas que no somos capaces de evaluar con otras técnicas diagnósticas como la radiología, la tomografía axial computerizada e incluso con la artrotomía convencional.During the last years, arthroscopy has become a very important method for the diagnosis of osteochondrallesions in the dogo In this study, we describe the technique and all the equipment necessary to perform an exploratory arthroscopy in the elbow joint. During the last year, we have performed 8 arthroscopic explorations in 8 dogs (8 elbows) with foreleg lameness localised to the elbow joint. 6 cases of FCP (fragmented medial coronoid process) were diagnosed. All the cases were confirmed by arthrotomy. In this study we want to probe how good arthroscopy is in the diagnosis of the FCP. Besides this, arthroscopy is a very usefull technique during the evaluation of the synovial embrane (synovitis) and the cartilage lesions, we have to say that we are not able to diagnose this type of lesions with other conventional techniques like radiology, axial tomography or arthrotomy
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