The effect of geometry on charge confinement in three dimensions

We show that, in contrast to the flat case, the Maxwell theory is not confining in the background of the three dimensional BTZ black-hole (covering space). We also study the effect of the curvature on screening behavior of Maxwell-Chern-Simons model in this space-time.Comment: 8 pages. To be published in Europhysics Letter

Gravitational Geometric Phase in the Presence of Torsion

We investigate the relativistic and non-relativistic quantum dynamics of a neutral spin-1/2 particle submitted an external electromagnetic field in the presence of a cosmic dislocation. We analyze the explicit contribution of the torsion in the geometric phase acquired in the dynamic of this neutral spinorial particle. We discuss the influence of the torsion in the relativistic geometric phase. Using the Foldy-Wouthuysen approximation, the non-relativistic quantum dynamics are studied and the influence of the torsion in the Aharonov-Casher and He-McKellar-Wilkens effects are discussed.Comment: 14 pages, no figur

Spacetime Defects: von K\'arm\'an vortex street like configurations

A special arrangement of spinning strings with dislocations similar to a von K\'arm\'an vortex street is studied. We numerically solve the geodesic equations for the special case of a test particle moving along twoinfinite rows of pure dislocations and also discuss the case of pure spinning defects.Comment: 9 pages, 2figures, CQG in pres

Falsifying Tree Level String Motivated Bouncing Cosmologies

The string effective action at tree level contains, in its bosonic sector, the Einstein-Hilbert term, the dilaton, and the axion, besides scalar and gauge fields coming from the Ramond-Ramond sector. The reduction to four dimensions brings to scene moduli fields. We generalize this effective action by introducing two arbitrary parameters, $\omega$ and $m$, connected with the dilaton and axion couplings. In this way, more general frameworks can be analyzed. Regular solutions with a bounce can be obtained for a range of (negative) values of the parameter $\omega$ which, however, exclude the pure string configuration ($\omega = - 1$). We study the evolution of scalar perturbations in such cosmological scenarios. The predicted primordial power spectrum decreases with the wavenumber with spectral index $n_s=-2$, in contradiction with the results of the $WMAP$. Hence, all such effective string motivated cosmological bouncing models seem to be ruled out, at least at the tree level approximation.Comment: Latex file, 19 pages, 3 figures in eps forma

Desempenho de progênies de açaizeiros provenientes de duas procedências avaliadas pelo gráfico de caixa.

Um importante componente da dieta alimentar dos habitantes ribeirinhos e nas cidades do Amapá e Pará é o açaí, havendo também o interesse em outras regiões e países. São, portanto, importantes as pesquisas visando seleção de materiais superiores para suprir a crescente demanda de consumo. No presente estudo foram comparadas, no campo experimental de Mazagão, da Embrapa Amapá, 75 progênies da região do município do Afuá, PA com 100 progênies da região leste da ilha de Marajó, PA. O experimento foi instalado em blocos ao acaso com duas repetições, sendo avaliados os caracteres: quantidade de estipes adultas, quantidade de estipes jovens, quantidade de rebentos, altura de planta adulta, altura de planta jovem, circunferência do estipe mais velho, circunferência média das estipes jovens, número de cachos, comprimento do entrenó e quantidade de folhas. Os resultados indicaram desempenhos diferentes entre as procedências para todos os caracteres avaliados. As procedências oriundas do Afuá apresentaram valores superiores às do Marajó, excetuando-se apenas a quantidade de rebentos. O número de folhas foi o único caráter que não apresentou diferenças. Foram observados valores nos extremos dos gráficos de caixa que apresentam progênies com potencial para serem selecionadas. O gráfico de caixa demonstrou ser um instrumento eficiente para distinguir as duas procedências

The Dynamic Universe: Realizing the Potential of Classical Time Domain and Multimessenger Astrophysics

In parallel with the multi-messenger revolution, major advances in time-domain astronomy across multiple science disciplines relevant to astrophysics are becoming more urgent to address. Aside from electromagnetic observations of gravitational wave events and explosive counterparts, there are a number of “classical” astrophysical areas that require new thinking for proper exploration in the time domain. How NASA, NSF, ESA, and ESO consider the 2020 USA Decadal Survey within the astronomy community, as well as the worldwide call to support and expand time domain and multi-messenger astrophysics, it is crucial that all areas of astrophysics, including stellar, galactic, Solar System, and exoplanetary science participate in the discussion, and that it not be made into an exclusive preserve of cosmological, high-energy, explosive and transient science. Time domain astronomy is used to explore many aspects of astrophysics–particularly concerning ground- and space-based mission science goals of exploring how the Universe works, understanding how did we get here, and are we alone. Time domain studies are already built into the core operations of many currently operating and future space telescopes (e.g., Roman, PLATO) as well as current and planned large areal ground-based surveys (e.g., Rubin). Time-domain observations designed for one scientific purpose, also lead to great discoveries in many other science areas. The recent advent of user-friendly hardware, software, observational approaches, and online data infrastructure has also helped make time domain observations especially suitable and appealing for citizen science projects. We provide a review of the current state of TDAMM alerts and observational protocols, revealing a wide array of software and applications, much of which is incompatible. Any conversation regarding TDAMM astrophysics should include all aspects of the field, including those aspects seen as classical applications

A experiência dos Serviços de Urologia: litíase urinária

Os autores fazem uma descrição da experiência do Serviço, na cirurgia da litíase dos últimos 10 anos, e destacam o actual arsenal cirúrgico disponível