The identification of physical close galaxy pairs

A classification scheme for close pairs of galaxies is proposed. The scheme is motivated by the fact that the majority of apparent close pairs are in fact wide pairs in three-dimensional space. This is demonstrated by means of numerical simulations of random samples of binary galaxies and the scrutiny of the resulting projected and spatial separation distributions. Observational strategies for classifying close pairs according to the scheme are suggested. As a result, physical (i.e., bound and spatially) close pairs are identified.Comment: 16 pages, 5 figures, accepted for publication in The Astronomical Journal, added text corrections on proof

Simulation or cohort models? Continuous time simulation and discretized Markov models to estimate cost-effectiveness

The choice of model design for decision analytic models in cost-effectiveness analysis has been the subject of discussion. The current work addresses this issue by noting that, when time is to be explicitly modelled, we need to represent phenomena occurring in continuous time. Multistate models evaluated in continuous time might be used but closed form solutions of expected time in each state may not exist or may be difficult to obtain. Two approximations can then be used for costeffectiveness estimation: (1) simulation models, where continuous time estimates are obtained through Monte Carlo simulation, and (2) discretized models. This work draws recommendations on their use by showing that, when these alternative models can be applied, it is preferable to implement a cohort discretized model than a simulation model. Whilst the bias from the first can be minimized by reducing the cycle length, the second is inherently stochastic. Even though specialized literature advocates this framework, the current practice in economic evaluation is to define clinically meaningful cycle lengths for discretized models, disregarding potential biases.

Anisotropy and percolation threshold in a multifractal support

Recently a multifractal object, $Q_{mf}$, was proposed to study percolation properties in a multifractal support. The area and the number of neighbors of the blocks of $Q_{mf}$ show a non-trivial behavior. The value of the probability of occupation at the percolation threshold, $p_{c}$, is a function of $\rho$, a parameter of $Q_{mf}$ which is related to its anisotropy. We investigate the relation between $p_{c}$ and the average number of neighbors of the blocks as well as the anisotropy of $Q_{mf}$

Avaliação de cultivares de soja com relação à preferência a Bemisia tabaci Biótipo B (Hemiptera: Aleyrodidae) com chance de escolha a campo.

A mosca-branca está entre as várias pragas que atacam a cultura da soja. São insetos que sugam a seiva das plantas hospedeiras, tanto na fase jovem como na adulta, podendo causar danos diretos a planta, como seu enfraquecimento e o desenvolvimento de fumagina sobre as folhas, com reflexos na produtividade, e danos indiretos, devido à sua capacidade de transmitir viroses. Entre os vários métodos de controle, o uso de cultivares menos preferidas, pode ser uma ferramenta para o manejo sustentável desta praga. Assim este experimento foi realizado no município de Primavera do Leste, MT, com o objetivo de avaliar diferentes cultivares de soja com relação à preferência a mosca-branca Bemisia tabaci biótipo B em testes com chance de escolha a campo. O delineamento experimental foi de blocos ao acaso com quatro repetições. A parcela foi constituída de 12 linhas com 8m de comprimento. As cultivares (crescimento/ grupo de maturação) testadas foram: 1. TMG1188 RR (semideterminado/8.8), 2. NA8015 RR (indeterminado/8.3), 3. TMG1288 RR (determinado/8.8), 4. TMG133 RR (determinado/8.5), 5. TMG1176(determinado/7.6), 6. TMG127 RR (indeterminado/7.2), 7, TMG132 RR (determinado/8.5) e 8. P98Y11 (determinado/8.1). Avaliou-se o número de ninfas em 10 folíolos centrais do terço médio da planta de cada parcela aos, 35, 41, 50 e 62 dias após plantio. As cultivares P98Y11; TMG132 RR e TMG1176 RR foram às menos infestadas com ninfas de mosca-branca no período avaliado, com infestação 71% menor que as cultivares mais infestadas. A maior população de ninfas foi observada aos 41 dias após o plantio com um número médio de 214 ninfas por folíolo. A população de ninfas caiu para 97,3 ninfas/folíolo na 3ª avaliação e reduziu para 0,5 ninfas/folíolo aos 62 dias após o plantio em todas as cultivares avaliadas, quando foram finalizadas as avaliações

Mechanisms of Spontaneous Current Generation in an Inhomogeneous d-Wave Superconductor

A boundary between two d-wave superconductors or an s-wave and a d-wave superconductor generally breaks time-reversal symmetry and can generate spontaneous currents due to proximity effect. On the other hand, surfaces and interfaces in d-wave superconductors can produce localized current-carrying states by supporting the T-breaking combination of dominant and subdominant order parameters. We investigate spontaneous currents in the presence of both mechanisms and show that at low temperature, counter-intuitively, the subdominant coupling decreases the amplitude of the spontaneous current due to proximity effect. Superscreening of spontaneous currents is demonstrated to be present in any d-d (but not s-d) junction and surface with d+id' order parameter symmetry. We show that this supercreening is the result of contributions from the local magnetic moment of the condensate to the spontaneous current.Comment: 4 pages, 5 figures, RevTe

The low dimensional dynamical system approach in General Relativity: an example

In this paper we explore one of the most important features of the Galerkin method, which is to achieve high accuracy with a relatively modest computational effort, in the dynamics of Robinson-Trautman spacetimes.Comment: 7 pages, 5 figure