Self-Dual Model Coupled to Bosons

In this paper we investigated the dynamics, at the quantum level, of the self-dual field minimally coupled to bosons. In this investigation we use the Dirac bracket quantization procedure to quantize the model. Also, the relativistic invariance is tested in connection with the elastic boson-boson scattering amplitudes.Comment: 9 pages, no figures, Latex, minor correctio

Cosmology in the Universe with distance dependent Lorentz-violating bakground

We consider a cosmological setup with the inflaton field in the presence of a redshift dependent Lorentz-violating time-like background to address the inflationary regime and other phases of the Universe. We also show that the regime of dark energy at large distances (low redshifts) is essentially dominated by the presence of the Lorentz-violating background.Comment: 8 pages, no figure, Latex, to appear in AHE

Lorentz-violating dimension-five operator contribution to the black body radiation

We investigate the thermodynamics of a photon gas in an effective field theory model that describes Lorentz violations through dimension-five operators and Horava-Lifshitz theory. We explore the electrodynamics of the model which includes higher order derivatives in the Lagrangian that can modify the dispersion relation for the propagation of the photons. We shall focus on the deformed black body radiation spectrum and modified Stefan-Boltzmann law to address the allowed bounds on the Lorentz-violating parameter.Comment: 8 pages, 6 figures. Version published in PL

On the dual equivalence between self-dual and Maxwell-Chern-Simons models with Lorentz symmetry breaking

In this paper, we use gauge embedding procedure and master action approach to establish the equivalence between the self-dual and Maxwell-Chern-Simons models with Lorentz symmetry breaking. As a result, new kinds of Lorentz-breaking terms arise.Comment: 14 pages, minor corrections, version accepted to Physical Review

Person localization using sensor information fusion

Nowadays the incredible grow of mobile devices market led to the need for location-aware applications. However, sometimes person location is di cult to obtain, since most of these devices only have a GPS (Global Positioning System) chip to retrieve location. In order to sup- press this limitation and to provide location everywhere (even where a structured environment doesn't exist) a wearable inertial navigation sys- tem is proposed, which is a convenient way to track people in situations where other localization systems fail. The system combines pedestrian dead reckoning with GPS, using widely available, low-cost and low-power hardware components. The system innovation is the information fusion and the use of probabilistic methods to learn persons gait behavior to correct, in real-time, the drift errors given by the sensors.This work is part-funded by ERDF - European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT Fundao para a Cincia e a Tecnologia (Portuguese Foundation for Science and Technology) within project FCOMP-01-0124-FEDER- 028980 (PTDC/EEI-SII/1386/2012). Ricardo also acknowledge FCT for the support of his work through the PhD grant (SFRH/DB/70248/2010)

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

Vascular trauma: a five year review

O presente trabalho pretende avaliar a casuística dos traumatismos vasculares agudos admitidos no Serviço de Cirurgia Vascular dos Hospitais da Universidade de Coimbra (HUC) durante o período de 5 anos, compreendido entre Julho de 2004 e Junho de 2009. Foram avaliados 97 doentes, sendo a principal causa de traumatismo as lesões iatrogénicas, seguida dos acidentes de viação. No grupo de doentes não relacionados com procedimentos coronários percutâneos verificou-se que no membro superior as artérias umeral e radial foram as mais afectadas, enquanto no membro inferior foram as artérias femoral superficial e poplítea. A isquémia aguda foi a principal forma de apresentação. Relativamente ao tratamento deste grupo de doentes, a RATT (ressecção e anastomose topo-topo) e o enxerto foram os mais utlizados no membro superior, enquanto a trombectomia e o bypass foram as técnicas mais aplicadas a nível do membro inferior. Não houve mortalidade mas a morbilidade foi elevada, predominando as lesões neurológicas nos traumatismos do membro superior, e a amputação nos do membro inferior. Os resultados deste trabalho foram concordantes com o que está publicado na literatura em que se demonstra um aumento progressivo dos traumatismos de origem iatrogénica

On the coupling of the self-dual field to dynamical U(1) Matter and its dual theory

We consider an arbitrary U(1) charged matter non-minimally coupled to the self-dual field in $d=2+1$. The coupling includes a linear and a rather general quadratic term in the self-dual field. By using both a Lagragian gauge embedding and a master action approaches we derive the dual Maxwell Chern-Simons type model and show the classical equivalence between the two theories. At quantum level the master action approach in general requires the addition of an awkward extra term to the Maxwell Chern-Simons type theory. Only in the case of a linear coupling in the self-dual field the extra term can be dropped and we are able to establish the quantum equivalence of gauge invariant correlation functions in both theories.Comment: two citations and references corrected, 13 page

A rare cause of portal hypertension: case report

Apresenta-se caso clínico de doente com quadro de hipertensão portal pela presença de fístula artério-venosa entre a artéria gastroduodenal e a veia porta. Indivíduo do sexo masculino, de 77 anos, previamente saudável, com ascite volumosa de instalação recente. Hemorragia digestiva alta por rotura de varizes esofágicas. TAC abdominal revelando acentuada dilatação da veia porta (30 mm), envolvida em fístula artério-venosa com origem na artéria gastroduodenal; fígado sem estigmas de hepatopatia crónica e sem nódulos; ascite volumosa. Procedeu-se à laparotomia com drenagem de ascite, isolamento e laqueação do trajecto fístuloso entre a artéria gastroduodenal e a veia porta. Sem complicações intra-operatórias. Ao 18º dia, após regressão da ascite, teve alta medicado com diurético