Frustrated multiband superconductivity

We show that a clean multiband superconductor may display one or several phase transitions with increasing temperature from or to frustrated configurations of the relative phases of the superconducting order parameters. These transitions may occur when more than two bands are involved in the formation of the superconducting phase and when the number of repulsive interband interactions is odd. These transitions are signalled by slope changes in the temperature dependence of the superconducting gaps.Comment: 5 pages, 3 figure

Coherent States Expectation Values as Semiclassical Trajectories

We study the time evolution of the expectation value of the anharmonic oscillator coordinate in a coherent state as a toy model for understanding the semiclassical solutions in quantum field theory. By using the deformation quantization techniques, we show that the coherent state expectation value can be expanded in powers of $\hbar$ such that the zeroth-order term is a classical solution while the first-order correction is given as a phase-space Laplacian acting on the classical solution. This is then compared to the effective action solution for the one-dimensional \f^4 perturbative quantum field theory. We find an agreement up to the order \l\hbar, where \l is the coupling constant, while at the order \l^2 \hbar there is a disagreement. Hence the coherent state expectation values define an alternative semiclassical dynamics to that of the effective action. The coherent state semiclassical trajectories are exactly computable and they can coincide with the effective action trajectories in the case of two-dimensional integrable field theories.Comment: 20 pages, no figure

A Simple Realization of the Inverse Seesaw Mechanism

Differently from the canonical seesaw mechanism, which is grounded in grand unified theories, the inverse seesaw mechanism lacks a special framework that realizes it naturally. In this work we advocate that the 3-3-1 model with right-handed neutrinos has such an appropriate framework to accommodate the inverse seesaw mechanism. We also provide an explanation for the smallness of the $\mu$ parameter and estimate the branching ratio for the rare lepton flavor violation process $\mu \rightarrow e\gamma$.Comment: About 14pages, no figures, basis corrected, to appear at the PR

Upper Critical Field in a Spin-Charge Separated Superconductor

It is demonstrated that the spatial decay of the pair propagator in a Luttinger liquid with spin charge separation contains a logarithmic correction relative to the free fermi gas result in a finite interval between the spin and charge thermal lengths. It is argued that similar effects can be expected in higher dimensional systems with spin charge separation and that the temperature dependence of the upper critical field $H_{c2}$ curve is a probe of this effect.Comment: 3 pages, postscript file (compressed and uuencoded

Environmental behavior: A comparative study between Brazilian and Portuguese students

Although undergraduate students have great access to environmental information, it does not mean that an environmental behavior is being developed. With the use of a scale applied to 1035 university students from Brazil and Portugal, it was examined how the environmental behavior of these students is structured. Using multivariate statistical techniques, it was verified that there is a similarity in the environmental behavior of both groups, with environmental beliefs being manifested by an opposition to the anthropocentric view. The environmental attitudes have the concerns related to the environment as their predecessor. These concerns influence the option to control economic growth, which is reinforced by the ecocentric point of view of the respondents and is manifested by the perspective of a decrease in production and in consumption as well as the promotion of welfare. Although there is a tendency, the option for green consumption is not fully accomplished.Jovens universitários têm acesso crescente às informações ambientais, mas isso não significa que haja o desenvolvimento de um comportamento em prol do meio ambiente. Com a utilização de uma escala aplicada em 1035 estudantes universitários do Brasil e de Portugal, foi averiguado como ocorre a estruturação e manifestação do comportamento ambiental desses estudantes. Utilizando técnicas estatísticas multivariadas, verificou-se uma similaridade no comportamento ambiental de ambos os grupos, com as crenças ambientais se manifestando por uma oposição à visão antropocêntrica. As atitudes ambientais têm como antecedentes as preocupações relacionadas ao meio ambiente. Essas preocupações influem na opção pelo controle do crescimento econômico, perspectiva reforçada pela tendência mais ecocêntrica dos entrevistados e que está pautada por uma diminuição da produção, do consumo e promoção do bem-estar. Verificou-se também que a opção pelo consumo verde ainda não se realiza totalmente, embora seja verificada uma tendência favorável.Los estudiantes universitarios tienen cada vez más acceso a la información ambiental, pero eso no significa que haga el desarrollo de un comportamiento compatible. Con una escala aplicada en 1035 estudiantes universitarios de Brasil y Portugal, se examinó cómo está estructurado el comportamiento ambiental de estos estudiantes. Con el uso de técnicas estadísticas multivariantes, fue verificada una similitud en el comportamiento ambiental de los dos grupos, con las creencias ambientales si manifestando por una oposición a la visión antropocéntrica. Las actitudes ambientales tienen como antecedentes las preocupaciones relacionadas con el medio ambiente. Estas preocupaciones influyen en la opción para el control del crecimiento económico, reforzada por una tendencia ecocéntrica y se caracteriza por una perspectiva de disminución de la producción y del consumo además de la promoción del bienestar. También sí verificó que la opción por el consumo verde no se realiza plenamente, aunque se verifica una tendencia favorable.(undefined

Estiolamento in vitro: uma alternativa para a produção de mudas micropropagadas de antúrio.

bitstream/item/55489/1/CIT11005.pd

Thin-shell wormholes in d-dimensional general relativity: Solutions, properties, and stability

We construct thin-shell electrically charged wormholes in d-dimensional general relativity with a cosmological constant. The wormholes constructed can have different throat geometries, namely, spherical, planar and hyperbolic. Unlike the spherical geometry, the planar and hyperbolic geometries allow for different topologies and in addition can be interpreted as higher-dimensional domain walls or branes connecting two universes. In the construction we use the cut-and-paste procedure by joining together two identical vacuum spacetime solutions. Properties such as the null energy condition and geodesics are studied. A linear stability analysis around the static solutions is carried out. A general result for stability is obtained from which previous results are recovered.Comment: 16 pages, 1 figur

Exchange interaction effects in the thermodynamic properties of quantum dots

We study electron-electron interaction effects in the thermodynamic properties of quantum-dot systems. We obtain the direct and exchange contributions to the specific heat C_v in the self-consistent Hartree-Fock approximation at finite temperatures. An exchange-induced phase transition is observed and the transition temperature is shown to be inversely proportional to the size of the system. The exchange contribution to C_v dominates over the direct and kinetic contributions in the intermediate regime of interaction strength (r_s ~ 1). Furthermore, the electron-electron interaction modifies both the amplitude and the period of magnetic field induced oscillations in C_v.Comment: 4 pages, 4 figures; To appear in Phys. Rev.