Phase diagram and dependence of the critical temperature T_c on the pressure for Tl_{0.5}Pb_{0.5}Sr_2Ca_{1-x}Y_xCu_2)_7

Using a mean-field BCS-like approach on the bidimensional extended Hubbard Hamiltonian we calculate the superconducting transition temperature Tc as a function of the hole content nh, for the d-wave and extended-s wave gap symmetries. To describe the pressure effect on Tc we assume it induces a change in the magnitude V of the attractive superconductor potential. This assumption yields an explanation for the intrinsic term, and together with the well known change in nh, we set the critical temperature as Tc=Tc(nh(P),V(P)). With this we obtain a general expansion of Tc in terms of the pressure P and the hole content nh. We apply this expansion to the Tl_{0.5}Pb_{0.5}Sr_2Ca_{1-x}Y_xCu_2)_7 system

Extended 2d generalized dilaton gravity theories

We show that an anomaly-free description of matter in (1+1) dimensions requires a deformation of the 2d relativity principle, which introduces a non-trivial center in the 2d Poincare algebra. Then we work out the reduced phase-space of the anomaly-free 2d relativistic particle, in order to show that it lives in a noncommutative 2d Minkowski space. Moreover, we build a Gaussian wave packet to show that a Planck length is well-defined in two dimensions. In order to provide a gravitational interpretation for this noncommutativity, we propose to extend the usual 2d generalized dilaton gravity models by a specific Maxwell component, which gauges the extra symmetry associated with the center of the 2d Poincare algebra. In addition, we show that this extension is a high energy correction to the unextended dilaton theories that can affect the topology of space-time. Further, we couple a test particle to the general extended dilaton models with the purpose of showing that they predict a noncommutativity in curved space-time, which is locally described by a Moyal star product in the low energy limit. We also conjecture a probable generalization of this result, which provides a strong evidence that the noncommutativity is described by a certain star product which is not of the Moyal type at high energies. Finally, we prove that the extended dilaton theories can be formulated as Poisson-Sigma models based on a nonlinear deformation of the extended Poincare algebra.Comment: 21 pages, IOP LaTeX2e preprint classfile, Improved discussions, Minor corrections, More didactic, More self-contained, New results concerning noncommutativity in curved space-time, Accepted for publication in Classical and Quantum Gravity on 02 Jul 200

One name, several (wo)men: reflections on Virginia Woolf's Orlando: a biography

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Letras/Inglês e Literatura Correspondente.This study discusses queer theory as regards the portrayal of Orlando in Virginia Woolf's novel, Orlando: A Biography. The character is first analyzed in light of the intersections between gender, race, class, and nation, and subsequently in terms of the poetic persona, understood from both liberal and radical perspectives. The findings show that the character can be understood to destabilize gender fixity in the construction of a poetic persona, which confirms the tentative hypothesis. Findings also show that there is a conflict in the novel as it presents at the same time a transgressive text and a normatizing subtext, a conflict that must be criticized for its implications in cultural studies regarding queer theories, gender studies, and emancipatory politics. Este estudo discute teoria queer na caracterização de Orlando no romance de Virginia Woolf, Orlando: A Biography. O personagem é analisado primeiramente em relação às intersecções entre gênero, raça, classe e nação, e na seqüência em termos de persona poética, entendida tanto de uma perspectiva liberal quanto radical. Os resultados do estudo mostram que o personagem desestabiliza a fixidez de gênero na construção da persona poética, o que confirma a hipótese inicial do estudo. Os resultados também mostram que existe um conflito no romance por este conter ao mesmo tempo um texto transgressivo e um subtexto normatizante, conflito este que deve ser criticado por suas implicações nos estudos culturais de teorias queer, estudos de gênero e políticas emancipatórias

Brazil’s Achievements and Challenges

Wirtschaftslage; Soziale Lage; Wirkungsanalyse; Brasilien

Crossover behavior for complex order parameter in high-Tc superconductors

A number of recent experiments have suggested the presence of either real or complex components in the gap symmetry of high-$T_c$ superconductors (HTSC). In this paper we introduce a novel approach to study the competition of such complex order parameter mixtures by varying the position of the two-body attractive potential in a two dimensional extended Hubbard Hamiltonian. We show that this procedure explain a number of experimental results and on the theoretical side, it may be related with certain HTSC microscopic models like the spin fluctuation theory. Following current trends we concentrate on the study of $d_{x^2-y^2}$ order parameter with a component of the type $d_{xy}$ or a s-wave like $s_{x^2+y^2}$ and $s_{xy}$ symmetry. We show that the position of the optimal s-component peak changes with the position parameter $b$ while the d-component occurs always in the optimally region around hole content $\rho \approx 0.39$.Comment: 6 pages in RevTex, 5 figs. in epsi, accepted in the Physica

Fiscal responsibility legislation and fiscal adjustment : the case of Brazilian local governments

This paper discusses trends in fiscal adjustment in Brazil since the 1990s, with particular emphasis on the strengthening of institutions for fiscal policymaking, and its effect on local government finances and their ability to invest in infrastructure building and upgrading. Although fiscal adjustment, which is ongoing, has taken a toll on the government's ability to finance much-needed infrastructure investment, it is not the only culprit. A lack of budget flexibility, against a backdrop of increasing downward rigidities in current spending, also constrains the government's ability to invest. The paper argues that regulatory uncertainty in many sectors, particularly water and sanitation, in which the municipalities play a leading role, has discouraged private sector investment and that the financing of infrastructure building and upgrading goes beyond the municipal level of government. Higher-level jurisdictions are responsible for financing investment in energy and transport infrastructure, for example.Public Sector Economics&Finance,Municipal Financial Management,Urban Economics,Public&Municipal Finance,Public Sector Management and Reform

The extended Hubbard model applied to phase diagram and the pressure effects in \Bi superconductors

We use the two dimensional extended Hubbard Hamiltonian with the position of the attractive potential as a variable parameter with a BCS type approach to study the interplay between the superconductor transition temperature $T_c$ and hole content for high temperature superconductors. This novel method gives some insight on the range and intensity of the Cooper pair interaction and why different compounds have different values for their measured coherence lengths and it describes well the experimental results of the superconducting phase diagram $T_c \times n$. The calculations may also be used to study the effect of the applied pressure with the assumption that it increases the attractive potential which is accompanied by an increase in the superconductor gap. In this way we obtain a microscopic interpretation for the intrinsic term and a general expansion for $T_c$ in terms of the pressure which reproduces well the experimental measurements on the \Bi superconductors.Comment: 11 pags in RevTex, 5 fi2s. in eps, accepted in Braz. J. of Physic