A Remark on Lorentz Violation at Finite Temperature

We investigate the radiatively induced Chern-Simons-like term in four-dimensional field theory at finite temperature. The Chern-Simons-like term is temperature dependent and breaks the Lorentz and CPT symmetries. We find that this term remains undetermined although it can be found unambiguously in different regularization schemes at finite temperature.Comment: To appear in JHEP, 8 pages, 1 eps figure, minor changes and references adde

Lorentz-CPT violation, radiative corrections and finite temperature

In this work we investigate the radiatively induced Chern-Simons-like terms in four-dimensions at zero and finite temperature. We use the approach of rationalizing the fermion propagator up to the leading order in the CPT-violating coupling $b_\mu$. In this approach, we have shown that although the coefficient of Chern-Simons term can be found unambiguously in different regularization schemes at zero or finite temperature, it remains undetermined. We observe a correspondence among results obtained at finite and zero temperature.Comment: To appear in JHEP, 10 pages, 1 eps figure, minor changes and references adde

Effects of motor imagery training of Parkinson's disease: a protocol for a randomized clinical trial

Background Gait disorders in individuals with Parkinson’s disease (PD) may be associated with alterations in the motor control system and aggravated by psychoemotional and cognitive issues. Therapeutic strategies aimed at self-perception and motor regulation seem to be promising. Motor imagery (MI) has been shown to be one of these strategies, but there is still no clear evidence of its applicability in this population. The aim of this trial is to determine the effects of motor-imagery training on the gait and electroencephalographic activity of individuals with PD. Methods/design The sample will consist of 40 individuals, aged between 45 and 75 years, in the mild and moderate phase of the disease, with the ability to generate voluntary mental images. They will be assessed for cognitive level, degree of physical disability, mental-image clarity, kinematic gait variables, electroencephalographic activity and mobility. Next, subjects will be randomly assigned to an experimental group (EG) and a control group (CG). The EG will perform motor imagery and gait, while the CG will only engage in gait exercises. Twelve training sessions will be conducted lasting up to 90 min each, three times a week, for 4 weeks. The subjects will be reassessed on the kinematic variables of gait, electroencephalographic activity and mobility at 1, 7 and 30 days after the final training session. Discussion The results may provide an important advance in neurological rehabilitation where an easy-access and low-cost intervention may help to improve gait, electroencephalographic activity and mobility in individuals with PD

Associação da prática de atividade física e do estado de saúde sobre a qualidade de vida de mulheres com fibromialgia

This study analyzed the association between physical activity, health status and life quality among women with fibromyalgia. Cross-sectional study based on the clinical information of 177 women (42.1 ± 8.6 years old) diagnosed with fibromyalgia and assisted in rheumatology clinics of the private sector of the Unified Health System (UHS) in the city of Maringá-PR, Brazil. The instruments were the International Physical Activity Questionnaire (IPAQ), the Fibromyalgia Impact Questionnaire (FIQ) and the WHOQOL-Bref. Data analysis was conducted through Mann-Whitney test, Spearman correlation and Structural Equation Analysis (p<0.05). Results showed positive correlations between physical activity and life quality domain. Health status showed negative correlation life quality domains. Structural Equation Analysis revealed days of walking per week showed positive association with life quality domains. Model 3 showed that the impact of fibromyalgia on the health status showed a moderate negative association with life quality domains. Based on the results obtained, the conclusion is that light physical activity, characterized as walking, represents a positive factor in the domains of quality of life in women with fibromyalgia and also, the impact of this disease on the health status of the patients is associated negatively areas of quality of life.301Este estudo analisou a associação entre atividade física, estado de saúde e qualidade de vida de mulheres com fibromialgia. Estudo transversal baseado na informação clínica de 177 mulheres (42,1 ± 8,6 anos) diagnosticadas com fibromialgia e auxiliadas em clínicas de reumatologia do setor privado do Sistema Único de Saúde (SUS) na cidade de Maringá-PR, Brasil. Os instrumentos utilizados foram o Questionário Internacional de Atividade Física (IPAQ), o Questionário de Impacto da Fibromialgia (FIQ) e o WHOQOL-Bref. A análise dos dados foi realizada através do teste de Mann-Whitney, correlação de Spearman e Análise de Equações Estruturais (p <0,05). Os resultados mostraram correlações positivas entre a atividade física e o domínio da qualidade de vida. O estado de saúde apresentou correlações negativas com a qualidade de vida. A Análise de Equação Estrutural revelou que os dias de caminhada por semana se associou positivamente com domínios de qualidade de vida. O modelo 3 mostrou que o impacto da fibromialgia no estado de saúde apresentou associação negativa e moderada com os domínios de qualidade de vida. Com base nos resultados obtidos, conclui-se que a atividade física leve, caracterizada pela caminhada, representa um fator positivo nos domínios da qualidade de vida em mulheres com fibromialgia e também, o impacto desta doença sobre o estado de saúde dos pacientes está associado negativamente domínios da qualidade de vida

Noncommutative massive Thirring model in three-dimensional spacetime

We evaluate the noncommutative Chern-Simons action induced by fermions interacting with an Abelian gauge field in a noncommutative massive Thirring model in (2+1)-dimensional spacetime. This calculation is performed in the Dirac and Majorana representations. We observe that in Majorana representation when $\theta$ goes to zero we do not have induced Chern-Simons term in the dimensional regularization scheme.Comment: Accepted to Phys. Rev. D; 9 pages, Revtex4, no figures, references added, minor improvements, Eq.31 correcte

Stationary solutions for the parity-even sector of the CPT-even and Lorentz-covariance-violating term of the standard model extension

In this work, we focus on some properties of the parity-even sector of the CPT-even electrodynamics of the standard model extension. We analyze how the six non-birefringent terms belonging to this sector modify the static and stationary classical solutions of the usual Maxwell theory. We observe that the parity-even terms do not couple the electric and magnetic sectors (at least in the stationary regime). The Green's method is used to obtain solutions for the field strengths E and B at first order in the Lorentz- covariance-violating parameters. Explicit solutions are attained for point-like and spatially extended sources, for which a dipolar expansion is achieved. Finally, it is presented an Earth-based experiment that can lead (in principle) to an upper bound on the anisotropic coefficients as stringent as $(\widetilde{\kappa}_{e-}) ^{ij}<2.9\times10^{-20}.$Comment: 8 pages, revtex style, revised published version, to appear in EPJC (2009

Consistency analysis of a nonbirefringent Lorentz-violating planar model

In this work analyze the physical consistency of a nonbirefringent Lorentz-violating planar model via the analysis of the pole structure of its Feynman propagators. The nonbirefringent planar model, obtained from the dimensional reduction of the CPT-even gauge sector of the standard model extension, is composed of a gauge and a scalar fields, being affected by Lorentz-violating (LIV) coefficients encoded in the symmetric tensor $\kappa_{\mu\nu}$. The propagator of the gauge field is explicitly evaluated and expressed in terms of linear independent symmetric tensors, presenting only one physical mode. The same holds for the scalar propagator. A consistency analysis is performed based on the poles of the propagators. The isotropic parity-even sector is stable, causal and unitary mode for $0\leq\kappa_{00}<1$. On the other hand, the anisotropic sector is stable and unitary but in general noncausal. Finally, it is shown that this planar model interacting with a $\lambda|\varphi|^{4}-$Higgs field supports compactlike vortex configurations.Comment: 11 pages, revtex style, final revised versio