Interference phenomena, chiral bosons and Lorentz invariance

We have studied the theory of gauged chiral bosons and proposed a general theory, a master action, that encompasses different kinds of gauge field couplings in chiral bosonized theories with first-class chiral constraints. We have fused opposite chiral aspects of this master action using the soldering formalism and applied the final action to several well known models. The Lorentz rotation permitted us to fix conditions on the parameters of this general theory in order to preserve the relativistic invariance. We also have established some conditions on the arbitrary parameter concerned in a chiral Schwinger model with a generalized constraint, investigating both covariance and Lorentz invariance. The results obtained supplements the one that shows the soldering formalism as a new method of mass generation.Comment: 11 pages, RevTex(twocolumn). Final version to appear in Physiscal Review

On the consistency of the Horava Theory

With the goal of giving evidence for the theoretical consistency of the Horava Theory, we perform a Hamiltonian analysis on a classical model suitable for analyzing its effective dynamics at large distances. The model is the lowest-order truncation of the Horava Theory with the detailed-balance condition. We consider the pure gravitational theory without matter sources. The model has the same potential term of general relativity, but the kinetic term is modified by the inclusion of an arbitrary coupling constant lambda. Since this constant breaks the general covariance under space-time diffeomorphisms, it is believed that arbitrary values of lambda deviate the model from general relativity. We show that this model is not a deviation at all, instead it is completely equivalent to general relativity in a particular partial gauge fixing for it. In doing this, we clarify the role of a second-class constraint of the model.Comment: The wording has been revised in general, specially in abstract, introduction and conclusions. No changes in results. Version published in IJMP

Integraçao reduzida para problemas advectivos-difusivos escalares discretizados pela formulaçao Supg com operador de captura de descontinuidade

Este trabalho apresenta una técnica de controle das oscilaçoes esgúrias que podein surgir quando as integrais provenientes da discretizaçao de problemas escalares advectivos-difusivos em regime permanente pela formulaçao SUPG com operador de captura de descontinuidades, sao avaliadas utilizamdo-se um ponto de quadratura de Gauss. Os termos de correçao saoo obtidos a partir do princípio variacional de Hu-Washizu. Diversos exeinplos numéricos sao apresentados de forma a validar a técnica proposta. REDUCED INTEGRATION FOR STEADY ADVECTIVE-DIFFUSIVE PROBLEMS DISCRETIZED BY THE SUPG FORMULATION WITH DISCONTINUITY-CAPTURING SUMMARY This worlk presents a technique to control thee spurious oscillations that may appear when the integrals arising from the discretization of scalar steady-state advective-diffusive problems by the SUPG formulation with discontinuity-capturing are evaluated usiilg one-point Gaussian quadrature. Tlie correction terms are clerived froin a Hu-Wasl-iizu variational formulation. Severa1 numerical esamples a.re slzown, validating the proposed technique.Peer Reviewe

c-Src inhibition improves cardiovascular function but not remodeling or fibrosis in Ang II-induced hypertension

c-Src plays an important role in angiotensin II (Ang II) signaling. Whether this member of the Src family kinases is involved in the development of Ang II–induced hypertension and associated cardiovascular damage in vivo remains unknown. Here, we studied Ang II–infused (400 ng/kg/min) mice in which c-Src was partially deleted (c-Src+/−) and in wild-type (WT, c-Src+/+) mice treated with a c-Src inhibitor (CGP077675; 25 mg/kg/d). Ang II increased blood pressure and induced endothelial dysfunction in WT mice, responses that were ameliorated in c-Src+/− and CGP077675-treated mice. Vascular wall thickness and cross-sectional area were similarly increased by Ang II in WT and c-Src+/− mice. CGP077675 further increased cross-sectional area in hypertensive mice. Cardiac dysfunction (ejection fraction and fractional shortening) in Ang II–infused WT mice was normalized in c-Src+/− mice. Increased oxidative stress (plasma thiobarbituric acid–reactive substances, hydrogen peroxide, and vascular superoxide generation) in Ang II–infused WT mice was attenuated in c-Src–deficient and CGP077675-treated mice. Hyperactivation of vascular c-Src, ERK1/2 (extracellular signal–regulated kinase 1/2), and JNK (c-Jun N-terminal kinase) in hypertensive mice was normalized in CGP077675-treated and c-Src+/− mice. Vascular fibronectin was increased by Ang II in all groups and further augmented by CGP077675. Cardiac fibrosis and inflammation induced by Ang II were amplified in c-Src+/− and CGP-treated mice. Our data indicate that although c-Src downregulation attenuates development of hypertension, improves endothelial and cardiac function, reduces oxidative stress, and normalizes vascular signaling, it has little beneficial effect on fibrosis. These findings suggest a divergent role for c-Src in Ang II–dependent hypertension, where c-Src may be more important in regulating redox-sensitive cardiac and vascular function than fibrosis and remodeling

The shape of jamming arches in two-dimensional deposits of granular materials

We present experimental results on the shape of arches that block the outlet of a two dimensional silo. For a range of outlet sizes, we measure some properties of the arches such as the number of particles involved, the span, the aspect ratio, and the angles between mutually stabilizing particles. These measurements shed light on the role of frictional tangential forces in arching. In addition, we find that arches tend to adopt an aspect ratio (the quotient between height and half the span) close to one, suggesting an isotropic load. The comparison of the experimental results with data from numerical models of the arches formed in the bulk of a granular column reveals the similarities of both, as well as some limitations in the few existing models.Comment: 8 pages; submitted to Physical Review

Self-motility of an active particle induced by correlations in the surrounding solution

Current models of phoretic transport rely on molecular forces creating a "diffuse" particle-fluid interface. We investigate theoretically an alternative mechanism, in which a diffuse interface emerges solely due to a non-vanishing correlation length of the surrounding solution. This mechanism can drive self-motility of a chemically active particle. Numerical estimates indicate that the velocity can reach micrometers per second. The predicted phenomenology includes a bilinear dependence of the velocity on the activity and a possible double velocity reversal upon varying the correlation length.Comment: 6 pages, 2 figures, and 22 pages of supplemental material. To be published as Phys. Rev. Let

Nursing student attitudes towards older people: validity and reliability of the Italian version of the Kogan Attitudes towards Older People scale

Aim. This paper reports a study testing the validity and reliability of the Italian version of the Kogan Attitude towards Older People scale. Background. Nursing students’ attitudes towards older people can affect their preference for working with them. One of the most common instruments used to assess these attitudes is the Kogan Attitude towards Older People scale. Previous validation studies performed on college students internationally have demonstrated good reliability and validity. The psychometric properties of the Italian version have not yet been tested. Design. A cross-sectional, descriptive study. Method. The study was conducted from March–June 2010 with a convenience sample of nursing students attending two Italian universities. Reliability was evaluated using internal consistency and item-to-total correlation. Content and construct validity were evaluated using a content validity index and principal factor analysis. Results. A total of 1637 nursing students participated in the study. Two factors were extracted from the factor analysis: prejudice describing a negative disposition and appreciation indicating a favourable feeling and opinion towards older people. Conclusion. The Kogan Attitude towards Older People scale applied to Italian nursing students exhibited good internal consistency. The two-dimensional construct of the scale was congruent with some, but not all, results of previous studies due to methodological differences among the studies. Based on the study findings, the scale can be recommended for future research studies in Italy including use as pre/post-test measurement associated with nursing education programmes