A 3-form Gauge Potential in 5D in connection with a Possible Dark Sector of 4D-Electrodynamics

We here propose a 5-dimensional {\bf Abelian gauge} model based on the mixing between a $U(1)$ potential and an Abelian 3-form field by means of a topological mass term. An extended covariant derivative is introduced to minimally couple a Dirac field to the $U(1)$ potential, while this same covariant derivative non-minimally couples the 3-form field to the charged fermion. A number of properties are discussed in 5D; in particular, the appearance of a topological fermionic current. A 4-dimensional reduced version of the model is investigated and, { \bf in addition to the $U(1)$ electric- and magnetic-sort of fields,} there emerges an extra set of electric- and magnetic-like fields which contribute a negative pressure and may be identified as a possible fraction of dark energy. The role of the topological fermionic current is also contemplated upon dimensional reduction from 5D to 4D. Other issues we present in 4 space-time dimensions are the emergence {\bf of a pseudo-scalar massive particle,} an extra massive neutral gauge boson,{\bf which we interpret as a kind of paraphoton}, and the calculation of spin- and velocity-dependent interparticle potentials associated to the exchange of the intermediate bosonic fields of the model.Comment: -- 30 pages -- L. P. R. Ospedal appears as a new co-author; modifications by inclusion of the gravitational sector and the attainment of a spin- and velocity-dependent potential as an application have been worked out in this Revised Versio

Duration of Atrial Fibrillation Episodes and Implications for the Thromboembolic Risk

Introdução: A fibrilhação auricular é uma arritmia comum e com risco tromboembólico bem documentado, estando definidas nas recomendações internacionais indicações referentes ao uso de anticoagulantes orais. Existem, contudo, lacunas de informação nomeadamente no que se refere à duração dos episódios de fibrilhação auricular e sua relação com o risco de tromboembolismo. Esta questão tem particular interesse em doentes com dispositivos electrónicos cardíacos implantados com documentação contínua da duração de episódios de taquidisritmias auriculares, que são frequentemente curtos e assintomáticos. Material e Métodos: Foi feita uma análise crítica da evidência disponível sobre a relação da duração dos episódios de FA paroxística e a ocorrência de eventos embólicos, com base numa pesquisa na base de dados bibliográfica PubMed. Resultados: Foram selecionados oito artigos com abordagens diferentes no estudo deste tema; sete com recurso a monitorização cardíaca com dispositivos electrónicos cardíacos implantados (pacemakers, cardioversores-desfibilhadores implantáveis e ressincronizadores cardíacos) e um com base em registo de Holter. Metade destas publicações, correspondendo globalmente às maiores amostragens, aborda a questão do ponto de vista do somatório diário de episódios de fibrilhação auricular (carga diária) e não da duração de cada episódio. O risco tromboembólico aumenta gradualmente com a carga arrítmica, tendo sido demonstrado um aumento significativo do risco quando esta ultrapassa os cinco minutos num dia. Discussão: A formação de um trombo intracavitário, e consequente potencial embólico, é um processo dinâmico que resulta da interacção de várias condicionantes anatómicas e funcionais. O risco individual dependerá da interacção destes factores. A associação entre fenómenos embólicos e curtos períodos de fibrilhação auricular é inequívoca, apesar do mecanismo não ser óbvio, tendo em conta a discrepância frequentemente observada entre os períodos de fibrilhação auricular e os eventos clínicos. Conclusões: O risco de eventos tromboembólicos aumenta significativamente mesmo para períodos curtos de fibrilhação auricular (≥ cinco minutos de fibrilhação auricular em um dia), apesar da relação causa-efeito não estar definida. A decisão final sobre o recurso à anticoagulação oral deve basear-se na avaliação clínica individualizada

Satisfação com as práticas de gestão de recursos humanos e intenção de turn over num hotel de cinco estrelas: o papel mediador da perceção de suporte organizacional

Employees’ satisfaction with human resources management (HRM) practices has been envisaged as a solid predictor of turnover; nonetheless, how these practices may influence employee’s behavior is still an unclear process. There are suggestions that HRM practices may be distal determinants of turnover, as their effects may be mediated by more proximal variables such as perceived organizational support. This study empirically tested a model of research arising from these theoretical suggestions in a five-star hotel. The data collected from the survey of 152 workers were subjected to structural equation analyses. The results showed that the theoretical model had a strong fit to the data, giving empirical support to the prediction that satisfaction with HRM practices reduces turnover intentions, by increasing perceived organizational support. The importance of these results is discussed and interpreted from the point of view of strategic gains associated to the quality of HRM practices for the management of voluntary turnover.info:eu-repo/semantics/publishedVersio

Control of quantum transverse correlations on a four-photon system

Control of spatial quantum correlations in bi-photons is one of the fundamental principles of Quantum Imaging. Up to now, experiments have been restricted to controlling the state of a single bi-photon, by using linear optical elements. In this work we demonstrate experimental control of quantum correlations in a four-photon state comprised of two pairs of photons. Our scheme is based on a high-efficiency parametric downconversion source coupled to a double slit by a variable linear optical setup, in order to obtain spatially encoded qubits. Both entangled and separable pairs have been obtained, by altering experimental parameters. We show how the correlations influence both the interference and diffraction on the double slit.Comment: 14 pages, 6 figure

Coleta de forrageiras nativas na Ilha de Marajó, Pará.

bitstream/item/57580/1/CPATU-PA122.pd

Noncommutative Metafluid Dynamics

In this paper we define a noncommutative (NC) Metafluid Dynamics \cite{Marmanis}. We applied the Dirac's quantization to the Metafluid Dynamics on NC spaces. First class constraints were found which are the same obtained in \cite{BJP}. The gauge covariant quantization of the non-linear equations of fields on noncommutative spaces were studied. We have found the extended Hamiltonian which leads to equations of motion in the gauge covariant form. In addition, we show that a particular transformation \cite{Djemai} on the usual classical phase space (CPS) leads to the same results as of the $\star$-deformation with $\nu=0$. Besides, we will shown that an additional term is introduced into the dissipative force due the NC geometry. This is an interesting feature due to the NC nature induced into model.Comment: 11 page

Feeding behaviour of broiler chickens: a review on the biomechanical characteristics

Feed related costs are the main drivers of profitability of commercial poultry farms, and good nutrition is mainly responsible for the exceptional growth rate responses of current poultry species. So far, most research on the poultry feeding behaviour addresses the productivity indices and birds' physiological responses, but few studies have considered the biomechanical characteristics involved in this process. This paper aims to review biomechanical issues related to feed behaviour of domestic chickens to address some issues related to the feed used in commercial broiler chicken production, considering feed particle size, physical form and the impact of feeders during feeding. It is believed that the biomechanical evaluation might suggest a new way for feed processing to meet the natural feeding behaviour of the birds

Supersymmetrization of the Radiation Damping

We construct a supersymmetrized version of the model to the radiation damping \cite{03} introduced by the present authors \cite{ACWF}. We dicuss its symmetries and the corresponding conserved Noether charges. It is shown this supersymmetric version provides a supersymmetric generalization of the Galilei algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action can be splited into dynamically independent external and internal sectors.Comment: 9 page

Ponseti Method: Does Age at the Beginning of Treatment Make a Difference?

The Ponseti method is reportedly effective for treating clubfoot in children up to 9 years of age. However, whether age at the beginning of treatment influences the rate of successful correction and the rate of relapse is unknown. We therefore retrospectively reviewed 68 consecutive children with 102 idiopathic clubfeet treated by the Ponseti technique in four Portuguese hospitals. We followed patients a minimum of 30 months (mean, 41.4 months; range, 30–61 months). The patients were divided into two groups according to their age at the beginning of treatment; Group I was younger than 6 months and Group II was older than 6 months. All feet(100%) were initially corrected and no feet required extensive surgery regardless of age at the beginning of treatment. There were no differences between Groups I and II in the number of casts, tenotomies, success in terms of rate of initial correction, rate of recurrence, and rate of tibialis anterior transference. The rate of the Ponseti method in avoiding extensive surgery was 100% in Groups I and II; relapses occurred in 8% of the feet in younger and older children. Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence

G-Jsim: A GUI tool for wireless sensor networks simulation under J-Sim

“Copyright © [2008] IEEE. Reprinted from 12th Annual IEEE International Symposium on Consumer Electronics (ISCE 2008). ISBN:978-1-4244-2422-1. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”A Wireless Sensor Network is composed of up to thousands of smart sensing nodes with processing unit and memory, sensing unit and wireless communication capabilities. Wireless Sensor Networks application spans from the military applications into almost every field we can think of. Several simulation tools are readily available, among them the J-Sim, a java-based simulator with growing interest by research and network developers alike. We propose to enhance J-Sim functionality with a Guided User Interface for Wireless Sensor Networks that dramatically increases the user-friendliness of the simulator. Also, we provide a free download web page for everyone to benefit