Boson-boson effective nonrelativistic potential for higher-derivative electromagnetic theories in D dimensions

The problem of computing the effective nonrelativistic potential $U_{D}$ for the interaction of charged scalar bosons within the context of D-dimensional electromagnetism with a cutoff, is reduced to quadratures. It is shown that $U_3$ cannot bind a pair of identical charged scalar bosons; nevertheless, numerical calculations indicate that boson-boson bound states do exist in the framework of three-dimensional higher-derivative electromagnetism augmented by a topological Chern-Simons term.Comment: 6 page

Is it Physically Sound to Add a Topologically Massive Term to Three-Dimensional Massive Electromagnetic or Gravitational Models ?

The addition of a topologically massive term to an admittedly non-unitary three-dimensional massive model, be it an electromagnetic system or a gravitational one, does not cure its non-unitarity. What about the enlargement of avowedly unitary massive models by way of a topologically massive term? The electromagnetic models remain unitary after the topological augmentation but, surprisingly enough, the gravitational ones have their unitarity spoiled. Here we analyze these issues and present the explanation why unitary massive gravitational models, unlike unitary massive electromagnetic ones, cannot coexist from the viewpoint of unitarity with topologically massive terms. We also discuss the novel features of the three-term effective field models that are gauge-invariant

Unavoidable Conflict Between Massive Gravity Models and Massive Topological Terms

Massive gravity models in 2+1 dimensions, such as those obtained by adding to Einstein's gravity the usual Fierz-Pauli, or the more complicated Ricci scalar squared ($R^2$), terms, are tree level unitary. Interesting enough these seemingly harmless systems have their unitarity spoiled when they are augmented by a Chern-Simons term. Furthermore, if the massive topological term is added to $R + R_{\mu\nu}^2$ gravity, or to $R + R_{\mu\nu}^2 + R^2$ gravity (higher-derivative gravity), which are nonunitary at the tree level, the resulting models remain nonunitary. Therefore, unlike the common belief, as well as the claims in the literature, the coexistence between three-dimensional massive gravity models and massive topological terms is conflicting.Comment: 13 pages, no figure

O vício de não incorporação da cláusula contratual nos contratos de adesão

Dissertação de mestrado em Direito dos Contratos e da EmpresaOs deveres de informação assumem-se como um fator essencial de proteção, no âmbito dos contratos de adesão, mas as consequências da sua violação não se mostram claras, dada a ambiguidade da expressão utilizada no artigo 8º do D.L. nº 446/85, de 25 de Outubro. Procurase, neste estudo, encontrar a consequência para a referida violação, tendo em conta os objetivos da lei. Procede-se à análise do controlo da incorporação das cláusulas, controlo, este, onde se incluem os deveres de informação. Estudam-se os princípios subjacentes ao mesmo, apurandose o seu objetivo e verificando-se como devem ser aplicados os deveres de informação. Desta analise resulta que o controlo da incorporação deve permanecer separado do controlo do conteúdo, que os deveres de informação estão enquadrados pelo princípio da transparência, que, por sua vez, é expressão do princípio da boa fé; e que o objetivo destes deveres é permitir que a parte que se limita a aderir, possa, por um lado, ponderar, de modo devidamente informado, se deve concluir o contrato ou não e, por outro lado, esteja devidamente preparada para a execução do contrato. Com isto em mente faz-se o estudo das diferentes possibilidades, apreciando-se as vantagens e desvantagens das mesmas e a sua adequação ao regime legal. Da comparação das diferentes possibilidades é possível concluir qual o regime a que está sujeita a sanção da violação dos deveres de informação, em termos de quem pode invocar a sanção, o respetivo prazo, a possibilidade de sanação e a possibilidade de conhecimento oficioso. Daqui também resulta a resposta ao problema que se pôs inicialmente, ou seja, qual é o vício que resulta da violação dos deveres de informação. Não se conclui sem antes de referir qual o efeito, no contrato, da não incorporação da cláusula afetada.The information requirements are an essential factor of protection, regarding standard contracts and unfair contract terms, but the consequences of their violation are not clear, considering the ambiguity of the expression used in article 8º of the D.L. nº 446/85, of October 25th. Here we try to ascertain the consequence of that violation, bearing in mind the goals of the law. We analyze the incorporation control of the contract terms, in which are included the information requirements. We study its underlying principles, finding its goal and describing how the information requirements should be observed. From this analysis we find that the incorporation control should remain separated from the content control, that the information requirements are under the principle of transparency, which, itself, is an expression of the principle of good faith; and that the goal of these requirements is to allow the party, that is restricted to the option of accepting or not the contract, on one hand, to consider, with enough information, should he accept the contract or not, and, on the other hand, to be prepared for the execution of the contract. Keeping this in mind, we do the study of the different possibilities, considering their advantages and disadvantages, and their suitability to the law. From the comparison of the different possibilities it is possible to ascertain which regime regulates the sanction resulting from the non-compliance of information requirements; defining who can argue the non-compliance, its deadline, possibility of ratification and the possibility of being assessed on the court´s own motion. From this it is possible to answer our initial problem, that is, which sanction is the consequence of non-compliance regarding the information requirements. Finally, we study the consequences, on the contract, of the non-incorporation of the contractual term

Assessment of e-government maturity in Portuguese municipalities using regression and clustering approaches

In order to evaluate the development of websites of the 308 Por- tuguese municipalities in this work it was performed an analysis using regression models and clustering techniques. That analysis allowed recognizing a group of socioeconomic variables that are significant to characterize homogenous groups of municipalities in what concerns e-government maturity

Perspectiva social del e-learning en la universidad

En la actual sociedad del conocimiento, los progresos en ciencia y tecnología conviven con una amplia problemática social que es necesario abordar para analizar los problemas relacionados con la educación. En los últimos años, la presencia del Estado ha disminuido en todos los ámbitos. El modelo estadounidense de privatización y comercialización ha creado nuevas realidades, como la necesidad de los países ricos de controlar, entre otras cosas, los servicios, el conocimiento y las nuevas tecnologías. En este contexto, y ante la creciente comercialización de la educación como servicio, incluso desde los organismos internacionales, los países en desarrollo necesitan más que nunca acceder a instituciones de educación superior y de investigación que les permitan avanzar hacia un desarrollo sostenible. Asistimos a un proceso de elitización en el que la educación deja de ser un bien público y pasa a convertirse en un bien privado, lo que se refleja en los sistemas educativos de distintos países. Son varios los procesos de reforma de los sistemas educativos de países en desarrollo que tienen como objetivo facilitar el acceso al conocimiento. Muchas de las medidas que deben aplicarse pasan por la utilización de las nuevas tecnologías y el intercambio de conocimientos mediante una cooperación internacional que se aleje de la comercialización y permita el acceso de todas las personas a la sociedad del conocimiento