El concepto de serie num??rica : un estudio a trav??s del modelo de Pirie y Kieren centrado en el mecanimo 'folding back'

Resumen basado en el de la publicaci??n

Relaci??n del feed-back positivo y el miedo a fallar sobre la motivaci??n intr??nseca

Resumen basado en el de la publicaci??n

The empire strikes back: Die Postkoloniale Indische Literatur von Aussen Nach Innen

The article, which is divided into five sections, the Indian-born author of German language attempts to illustrate/illuminate the particular hurdles to determining this subject as a genre. The works discussed by male and female authors vary tremndously one from another both in theme and in style. Among them are novels and stories in traditional narrative style by Naipaul, Ghosh, Lahiri… primarily grouped by major themes of immigration. At the same time that authors such as Rushdie, Roy, Tharoor... have been endeavoring to expand the vocabulary and conventions of the English language and to further modern narrative technique. Not only is the complex Indian subcontinent and its positive and negative realities portrayed and redefined, but as a parallel occurrence, rave stories and pop novels are being written by Rushdie and Kureishi. One must note here that English is not the mother tongue of any of these writers. The English language is used as an instrument of literary and artistic expression. This essay also expounds on examples of how “Indian Writing in English” differentiates itself clearly from “The Indian Romanticism” of European literature. The postcolonial writers point an admonishing finger to the wounds of India and they ruthlessly mock the inhumane regimes of Mrs. Thatcher and of Mr. Bush. One segment is devoted to the bizarre portrayal of love, gender and sex relations that makes the reading of the books in question vexing.

'Back into the american continuity of crust and mantle'': da cidade inscrita à cidade em escrita

No contexto norte-americano, falar da noção de cidade implica olhar para além das complexas redes sociais, económicas, políticas e culturais que se interligam em espaços mais ou menos urbanizados. É necessário considerar o facto de que na América a cidade assenta no princípio da Cidade erguida na Colina e esta dimensão mítica e simbólica que inspira os colonos recém-chegados a Nova Inglaterra é perpetuada nas gerações seguintes, refletindo-se igualmente no panorama literário norte-americano.

An agenda for the European Council: feasible steps to bring the eurozone back from the precipice. CEPS Policy Brief No. 274, 20 June 2012

In the run-up to the emergency European Council meeting at the end of June, Stefano Micossi outlines in this Policy Brief the main elements of a realistic and yet incisive policy package, capable of reassuring financial markets and a bewildered public opinion. It is more than Germany has been willing to accept so far but much less than many of the demands it will confront at the Council meeting. More importantly, it only requires a minimum of additional disbursements by the member states, while strengthening risk-sharing for sovereign and banking risks.

A collocation method for high frequency scattering by convex polygons

We consider the problem of scattering of a time-harmonic acoustic incident plane wave by a sound soft convex polygon. For standard boundary or finite element methods, with a piecewise polynomial approximation space, the computational cost required to achieve a prescribed level of accuracy grows linearly with respect to the frequency of the incident wave. Recently Chandler–Wilde and Langdon proposed a novel Galerkin boundary element method for this problem for which, by incorporating the products of plane wave basis functions with piecewise polynomials supported on a graded mesh into the approximation space, they were able to demonstrate that the number of degrees of freedom required to achieve a prescribed level of accuracy grows only logarithmically with respect to the frequency. Here we propose a related collocation method, using the same approximation space, for which we demonstrate via numerical experiments a convergence rate identical to that achieved with the Galerkin scheme, but with a substantially reduced computational cost.

Efficient evaluation of highly oscillatory acoustic scattering surface integrals

We consider the approximation of some highly oscillatory weakly singular surface integrals, arising from boundary integral methods with smooth global basis functions for solving problems of high frequency acoustic scattering by three-dimensional convex obstacles, described globally in spherical coordinates. As the frequency of the incident wave increases, the performance of standard quadrature schemes deteriorates. Naive application of asymptotic schemes also fails due to the weak singularity. We propose here a new scheme based on a combination of an asymptotic approach and exact treatment of singularities in an appropriate coordinate system. For the case of a spherical scatterer we demonstrate via error analysis and numerical results that, provided the observation point is sufficiently far from the shadow boundary, a high level of accuracy can be achieved with a minimal computational cost.

A Galerkin boundary element method for high frequency scattering by convex polygons

In this paper we consider the problem of time-harmonic acoustic scattering in two dimensions by convex polygons. Standard boundary or finite element methods for acoustic scattering problems have a computational cost that grows at least linearly as a function of the frequency of the incident wave. Here we present a novel Galerkin boundary element method, which uses an approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh, with smaller elements closer to the corners of the polygon. We prove that the best approximation from the approximation space requires a number of degrees of freedom to achieve a prescribed level of accuracy that grows only logarithmically as a function of the frequency. Numerical results demonstrate the same logarithmic dependence on the frequency for the Galerkin method solution. Our boundary element method is a discretization of a well-known second kind combined-layer-potential integral equation. We provide a proof that this equation and its adjoint are well-posed and equivalent to the boundary value problem in a Sobolev space setting for general Lipschitz domains.

Water wave scattering by finite arrays of circular structures

The scattering of small amplitude water waves by a finite array of locally axisymmetric structures is considered. Regions of varying quiescent depth are included and their axisymmetric nature, together with a mild-slope approximation, permits an adaptation of well-known interaction theory which ultimately reduces the problem to a simple numerical calculation. Numerical results are given and effects due to regions of varying depth on wave loading and free-surface elevation are presented.