925 resultados para Riemann Sphere
Resumo:
La autora analiza el desplazamiento, en dos niveles, realizado por el protagonista de esta novela de Proaño Arandi. El primero, un recorrido en el espacio físico, consiste en el regreso al Quito colonial, el segundo, un viaje simbólico, tiene que ver con la búsqueda –y recuperación– de la propia identidad a través de la reconstrucción de la memoria, tanto en sus aspectos colectivos como en aquellos que atañen directamente al personaje. Para que este ejercicio de recuperación del pasado pueda realizarse, Quito se presenta ante el lector como una ciudad dividida entre el sector moderno y el Centro Histórico, la ciudad real se manifiesta como algo totalmente lejano de la ciudad ideal, esto es, como el testimonio vivo de su fracaso y, en consecuencia, del fracaso del proyecto modernizador. La lucha de los individuos por un espacio al cual pertenecer se convierte en un asunto vital dentro de la esfera urbana: estar en un lugar equivale a hallarse a salvo del infierno. Ahí está la motivación que anima los esfuerzos del protagonista creado por Proaño Arandi. La pérdida de la memoria desemboca, indefectiblemente, en la pérdida del espacio –real y simbólico– que los seres humanos necesitamos para construir identidad.
Resumo:
Este artículo analiza la concepción del derecho a la tutela judicial efectiva como derecho fundamental, para lo cual parte de sus notas configuradoras básicas. Al efecto, se estudian sus implicaciones desde el ámbito constitucional y del Código Orgánico de la Función Judicial, como sus líneas directrices en la doctrina y en la jurisprudencia del Tribunal Constitucional español (órgano que ha estudiado ampliamente el tema), para luego determinar cómo se ha considerado el ámbito del derecho por los tribunales ecuatorianos.
Resumo:
En esta presentación abordaré tres asuntos, fundamentalmente. la primera cuestión a la que quisiera referirme es la de por qué dar cuenta, que en ocasiones puede considerarse obvia pero no lo es tanto, el segundo punto enfocará los contenidos respecto a los cuales quien ejerce una función jurisdiccional debe dar cuenta, finalmente, abordaré el asunto de la trascendencia o relevancia que socialmente alcanzan el cumplir y el incumplir con esta responsabilidad. Una puntualización aclaratoria: cuando me refiero a quienes ejercen función jurisdiccional, incluyo en ello tanto a jueces como a fiscales. Aunque en esta reunión se enfoca específicamente el caso de los jueces, dado que los integrantes del Ministerio Público también ejercen función jurisdiccional –especialmente en el caso de aquellos países donde se ha introducido el proceso penal reformado–, el abordaje del tema que propongo también los comprende.
Resumo:
La política de desarrollo tecnológico y derivada de esta, el papel que se pretende asignar a la universidad, se sustenta en un conjunto de ideas e interpretaciones erradas sobre la articulación entre ciencia, investigación y aplicaciones tecnológicas; ideas que han ido adquiriendo, aun en el medio académico, el estatus de sabiduría convencional de tal manera que, aceptadas como verdades, tienden a legitimar la acción de las instituciones y agencias gubernamentales. Este artículo analiza la propensión de ver a la universidad como la fuente de conocimiento e información directamente aplicable para la producción de bienes y servicios comerciales y cuestiona la perspectiva de considerar a la universidad simplemente como un agente de la esfera económica. El trabajo sostiene que el papel de la investigación universitaria consiste básicamente en un insumo para la enseñanza y que el bien público que provee la universidad es la creación de un sentido nacional de cultura, una forma de identidad y cohesión social.
Resumo:
France is known for being a champion of individual rights as well as for its overt hostility to any form of group rights. Linguistic pluralism in the public sphere is rejected for fear of babelization and Balkanization of the country. Over recent decades the Conseil Constitutionnel (CC) has, together with the Conseil d’État, remained arguably the strongest defender of this Jacobin ideal in France. In this article, I will discuss the role of France’s restrictive language policy through the prism of the CC’s jurisprudence. Overall, I will argue that the CC made reference to the (Jacobin) state-nation concept, a concept that is discussed in the first part of the paper, in order to fight the revival of regional languages in France over recent decades. The clause making French the official language in 1992 was functional to this policy. The intriguing aspect is that in France the CC managed to standardise France’s policy vis-à-vis regional and minority languages through its jurisprudence; an issue discussed in the second part of the paper. But in those regions with a stronger tradition of identity, particularly in the French overseas territories, the third part of the paper argues, normative reality has increasingly become under pressure. Therefore, a discrepancy between the ‘law in courts’ and the compliance with these decisions (‘law in action’) has been emerging over recent years. Amid some signs of opening of France to minorities, this contradiction delineates a trend that might well continue in future.
Resumo:
In this paper a cell by cell anisotropic adaptive mesh technique is added to an existing staggered mesh Lagrange plus remap finite element ALE code for the solution of the Euler equations. The quadrilateral finite elements may be subdivided isotropically or anisotropically and a hierarchical data structure is employed. An efficient computational method is proposed, which only solves on the finest level of resolution that exists for each part of the domain with disjoint or hanging nodes being used at resolution transitions. The Lagrangian, equipotential mesh relaxation and advection (solution remapping) steps are generalised so that they may be applied on the dynamic mesh. It is shown that for a radial Sod problem and a two-dimensional Riemann problem the anisotropic adaptive mesh method runs over eight times faster.
Resumo:
The shallow water equations are solved using a mesh of polygons on the sphere, which adapts infrequently to the predicted future solution. Infrequent mesh adaptation reduces the cost of adaptation and load-balancing and will thus allow for more accurate mapping on adaptation. We simulate the growth of a barotropically unstable jet adapting the mesh every 12 h. Using an adaptation criterion based largely on the gradient of the vorticity leads to a mesh with around 20 per cent of the cells of a uniform mesh that gives equivalent results. This is a similar proportion to previous studies of the same test case with mesh adaptation every 1–20 min. The prediction of the mesh density involves solving the shallow water equations on a coarse mesh in advance of the locally refined mesh in order to estimate where features requiring higher resolution will grow, decay or move to. The adaptation criterion consists of two parts: that resolved on the coarse mesh, and that which is not resolved and so is passively advected on the coarse mesh. This combination leads to a balance between resolving features controlled by the large-scale dynamics and maintaining fine-scale features.
Resumo:
We investigate the ability of an applied electric field to convert the morphology of a diblock-copolymer thin film from a monolayer of spherical domains embedded in the matrix to cylindrical domains that penetrate through the matrix. As expected, the applied field increases the relative stability of cylindrical domains, while simultaneously reducing the energy barrier that impedes the transition to cylinders. The effectiveness of the field is enhanced by a large dielectric contrast between the two block-copolymer components, particularly when the low-dielectric contrast component forms the matrix. Furthermore, the energy barrier is minimized by selecting sphere-forming diblock copolymers that are as compositionally symmetric as possible. Our calculations, which are the most quantitatively reliable to date, are performed using a numerically precise spectral algorithm based on self-consistent-field theory supplemented with an exact treatment for linear dielectric materials.
Resumo:
The radar scattering properties of realistic aggregate snowflakes have been calculated using the Rayleigh-Gans theory. We find that the effect of the snowflake geometry on the scattering may be described in terms of a single universal function, which depends only on the overall shape of the aggregate and not the geometry or size of the pristine ice crystals which compose the flake. This function is well approximated by a simple analytic expression at small sizes; for larger snowflakes we fit a curve to Our numerical data. We then demonstrate how this allows a characteristic snowflake radius to be derived from dual wavelength radar measurements without knowledge of the pristine crystal size or habit, while at the same time showing that this detail is crucial to using such data to estimate ice water content. We also show that the 'effective radius'. characterizing the ratio of particle volume to projected area, cannot be inferred from dual wavelength radar data for aggregates. Finally, we consider the errors involved in approximating snowflakes by 'air-ice spheres', and show that for small enough aggregates the predicted dual wavelength ratio typically agrees to within a few percent, provided some care is taken in choosing the radius of the sphere and the dielectric constant of the air-ice mixture; at larger sizes the radar becomes more sensitive to particle shape, and the errors associated with the sphere model are found to increase accordingly.
Resumo:
The SCoTLASS problem-principal component analysis modified so that the components satisfy the Least Absolute Shrinkage and Selection Operator (LASSO) constraint-is reformulated as a dynamical system on the unit sphere. The LASSO inequality constraint is tackled by exterior penalty function. A globally convergent algorithm is developed based on the projected gradient approach. The algorithm is illustrated numerically and discussed on a well-known data set. (c) 2004 Elsevier B.V. All rights reserved.
Resumo:
The length and time scales accessible to optical tweezers make them an ideal tool for the examination of colloidal systems. Embedded high-refractive-index tracer particles in an index-matched hard sphere suspension provide 'handles' within the system to investigate the mechanical behaviour. Passive observations of the motion of a single probe particle give information about the linear response behaviour of the system, which can be linked to the macroscopic frequency-dependent viscous and elastic moduli of the suspension. Separate 'dragging' experiments allow observation of a sample's nonlinear response to an applied stress on a particle-by particle basis. Optical force measurements have given new data about the dynamics of phase transitions and particle interactions; an example in this study is the transition from liquid-like to solid-like behaviour, and the emergence of a yield stress and other effects attributable to nearest-neighbour caging effects. The forces needed to break such cages and the frequency of these cage breaking events are investigated in detail for systems close to the glass transition.
Resumo:
We study the elliptic sine-Gordon equation in the quarter plane using a spectral transform approach. We determine the Riemann-Hilbert problem associated with well-posed boundary value problems in this domain and use it to derive a formal representation of the solution. Our analysis is based on a generalization of the usual inverse scattering transform recently introduced by Fokas for studying linear elliptic problems.
Resumo:
A new spectral method for solving initial boundary value problems for linear and integrable nonlinear partial differential equations in two independent variables is applied to the nonlinear Schrödinger equation and to its linearized version in the domain {x≥l(t), t≥0}. We show that there exist two cases: (a) if l″(t)<0, then the solution of the linear or nonlinear equations can be obtained by solving the respective scalar or matrix Riemann-Hilbert problem, which is defined on a time-dependent contour; (b) if l″(t)>0, then the Riemann-Hilbert problem is replaced by a respective scalar or matrix problem on a time-independent domain. In both cases, the solution is expressed in a spectrally decomposed form.
Resumo:
Recent coordinated observations of interplanetary scintillation (IPS) from the EISCAT, MERLIN, and STELab, and stereoscopic white-light imaging from the two heliospheric imagers (HIs) onboard the twin STEREO spacecraft are significant to continuously track the propagation and evolution of solar eruptions throughout interplanetary space. In order to obtain a better understanding of the observational signatures in these two remote-sensing techniques, the magnetohydrodynamics of the macro-scale interplanetary disturbance and the radio-wave scattering of the micro-scale electron-density fluctuation are coupled and investigated using a newly constructed multi-scale numerical model. This model is then applied to a case of an interplanetary shock propagation within the ecliptic plane. The shock could be nearly invisible to an HI, once entering the Thomson-scattering sphere of the HI. The asymmetry in the optical images between the western and eastern HIs suggests the shock propagation off the Sun–Earth line. Meanwhile, an IPS signal, strongly dependent on the local electron density, is insensitive to the density cavity far downstream of the shock front. When this cavity (or the shock nose) is cut through by an IPS ray-path, a single speed component at the flank (or the nose) of the shock can be recorded; when an IPS ray-path penetrates the sheath between the shock nose and this cavity, two speed components at the sheath and flank can be detected. Moreover, once a shock front touches an IPS ray-path, the derived position and speed at the irregularity source of this IPS signal, together with an assumption of a radial and constant propagation of the shock, can be used to estimate the later appearance of the shock front in the elongation of the HI field of view. The results of synthetic measurements from forward modelling are helpful in inferring the in-situ properties of coronal mass ejection from real observational data via an inverse approach.