Search results for "divergence"
showing 10 items of 257 documents
Hierarchy and dynamics of trace distance correlations
2013
We define and analyze measures of correlations for bipartite states based on trace distance. For Bell diagonal states of two qubits, in addition to the known expression for quantum correlations using this metric, we provide analytic expressions for the classical and total correlations. The ensuing hierarchy of correlations based on trace distance is compared to the ones based on relative entropy and Hilbert-Schmidt norm. Although some common features can be found, the trace distance measure is shown to differentiate from the others in that the closest uncorrelated state to a given bipartite quantum state is not given by the product of the marginals, and further, the total correlations are s…
Dynamics of geometric and entropic quantifiers of correlations in open quantum systems
2012
We extend the Hilbert-Schmidt (square norm) distance, previously used to define the geometric quantum discord, to define also geometric quantifiers of total and classical correlations. We then compare the dynamics of geometric and entropic quantifiers of the different kinds of correlations in a non-Markovian open two-qubit system under local dephasing. We find that qualitative differences occur only for quantum discords. This is taken to imply that geometric and entropic discords are not, in general, equivalent in describing the dynamics of quantum correlations. We then show that also geometric and entropic quantifiers of total correlations present qualitative disagreements in the state spa…
On Green's function for spherically symmetric problems of transfer of polarized radiation
2005
Analytic expressions for Green's function describing the process of transfer of polarized radiation in homogeneous isotropic infinite medium in case of spherical symmetry and nonconservative scattering are obtained. Spherical eigenfunctions of the homogeneous transfer equation are not used, due to their strong divergence; instead, direct transformation from plane-parallel to spherical symmetry is carried out, leading to convergent solutions. The possible existence of generalized eigenfunctions of homogeneous transfer equation is accounted for.
Vorticity Determines the Force on Bodies Immersed in Active Fluids
2021
When immersed into a fluid of active Brownian particles, passive bodies might start to undergo linear or angular directed motion depending on their shape. Here we exploit the divergence theorem to relate the forces responsible for this motion to the density and current induced by--but far away from--the body. In general, the force is composed of two contributions: due to the strength of the dipolar field component and due to particles leaving the boundary, generating a non-vanishing vorticity of the polarization. We derive and numerically corroborate results for periodic systems, which are fundamentally different from unbounded systems with forces that scale with the area of the system. We …
Crumpling of a stiff tethered membrane.
2003
first-principles numerical simulation model for crumpling of a stiff tethered membrane is introduced. In our model membranes, wrinkles, ridge formation, ridge collapse, as well as the initiation of stiffness divergence, are observed. The ratio of the amplitude and wave length of the wrinkles, and the scaling exponent of the stiffness divergence, are consistent with both theory and experiment. We observe that close to the stiffness divergence there appears a crossover beyond which the elastic behavior of a tethered membrane becomes similar to that of dry granular media. This suggests that ridge formation in membranes and force-chain network formation in granular packings are different manife…
A Divergence-Free High-Resolution Code for MHD
2001
We describe a 2.5D numerical code to solve the equations of ideal magnetohydrodynamics (MHD). The numerical code, based on high-resolution shock-capturing (HRSC) techniques, solves the equations written in conservation form and computes the numerical fluxes using a linearized Riemann solver. A special procedure is used to force the conservation of magnetic flux along the time.
Sobre la renovada necesidad de la Educación para la Ciudadanía en el sistema educativo español actual.
2021
Detectamos una renovada necesidad de la Educación para la Ciudadanía en el sistema educativo español actual, cuyo objetivo sea la formación de los alumnos como votantes críticos y el desarrollo de identificaciones cívicas reflexivas. Puesto que las propuestas de ciudadanía disponibles se encuentran en los diferentes programas políticos, realizamos una lectura detenida de los presentados por los quince partidos candidatos a la presidencia en las últimas elecciones generales, utilizando la técnica del análisis del contenido. Optamos por un sistema de categorías de análisis emergente, que permiten agrupar en distintos planos las medidas propuestas, analizando y comparando la coincidencia o div…
Effect of population patchiness and migration rates on the adaptation and divergence of vesicular stomatitis virus quasispecies populations
1999
The effect of migration among different isolated virus quasispecies populations on their adaptation and diversity was analysed through experimental evolution. Anin vitrocell system was employed to simulate migration of vesicular stomatitis virus between isolated homogeneous host cell populations. The results clearly demonstrated a positive correlation between the migration rate and the magnitude of the mean fitness reached by the virus quasispecies populations. The results also showed, although less clearly, that fitness differences among quasispecies decreased with the magnitude of migration. These results are in close agreement with predictions of standard population genetics theory. Thes…
Preliminary insights into the molecular barcoding data of Turraea socotrana (Meliaceae) from Socotra (Yemen)
2020
The relationship of two geographically and ecologically separated populations of Turraea socotrana Styles and F. White (Meliaceae), a vulnerable and scattered shrub from the island of Socotra (Yemen), was explored using preliminary molecular data. The nuclear ribosomal ITS region was used to screen the level of genetic divergence of T. socotrana from ecologically distant localities in comparison to a few other species of Turraea and closely related genera. The individuals from the inland (Diksam) differed from the western coastal ones (Ma’alah) by vegetative characters and by the rbcL gene. This may be due to the fact that the population from Ma’alah grows on lithosoil slopes directly expos…
Resentimiento y verdad. Sobre la réplica de Améry a Nietzsche
2004
En su Genealogía de la moral, Nietzsche situó el resentimiento del débil en la base de la moralización de los valores originales del fuerte -entre ellos, la crueldad inherente a la afirmación de la vidaque transformó éstos en negativos. A esta idea del resentimiento como un mecanismo esencialmentedistorsionador se opone Jean Améry, víctima de la violencia nazi, en Más alZa de la culpa y la expiación (1966), donde reivindica su resentimiento hacia los verdugos y sus cómplices como un instrumento de verdad para exigirles el reconocimiento de su crimen y la negación de su condición de verdugos. El objetivo del artículo es reconstruir la trama conceptual en que se articula la divergencia entre …