Bianchi groups are conjugacy separable

We prove that non-uniform arithmetic lattices of $SL_2(\mathbb{C})$ and in particular the Bianchi groups are conjugacy separable. The proof based on recent deep results of Agol, Long, Reid and Minasyan.Comment: to appear in J. Pure and Applied Algebr

Measuring stellar differential rotation with high-precision space-borne photometry

We introduce a method of measuring a lower limit to the amplitude of surface differential rotation from high-precision, evenly sampled photometric time series. It is applied to main-sequence late-type stars whose optical flux modulation is dominated by starspots. An autocorrelation of the time series was used to select stars that allow an accurate determination of starspot rotation periods. A simple two-spot model was applied together with a Bayesian information criterion to preliminarily select intervals of the time series showing evidence of differential rotation with starspots of almost constant area. Finally, the significance of the differential rotation detection and a measurement of its amplitude and uncertainty were obtained by an a posteriori Bayesian analysis based on a Monte Carlo Markov Chain approach. We applied our method to the Sun and eight other stars for which previous spot modelling had been performed to compare our results with previous ones. We find that autocorrelation is a simple method for selecting stars with a coherent rotational signal that is a prerequisite for successfully measuring differential rotation through spot modelling. For a proper Monte Carlo Markov Chain analysis, it is necessary to take the strong correlations among different parameters that exist in spot modelling into account. For the planet-hosting star Kepler-30, we derive a lower limit to the relative amplitude of the differential rotation of \Delta P / P = 0.0523 \pm 0.0016. We confirm that the Sun as a star in the optical passband is not suitable for measuring differential rotation owing to the rapid evolution of its photospheric active regions. In general, our method performs well in comparison to more sophisticated and time-consuming approaches.Comment: Accepted to Astronomy and Astrophysics, 15 pages, 13 figures, 4 tables and an Appendi

Outras aplicações de óleos essenciais - pesquisas para uso em parasitologia veterinária.

o controle de parasitas de impacto em animais de produção é realizado por meio de antiparasitários comerciais, tais como carrapaticidas e vermífugos. Existem diferentes classes de drogas veterinárias que podem ser utilizadas, mas a maioria delas não possui a eficácia esperada em função da forte resistência que os parasitas desenvolveram. Dessa forma, os produtores se vêm obrigados a aumentar as doses recomendadas ou tratar os animais de forma mais intensa, o que pode acarretar em riscos de contaminação do ambiente e dos subprodutos dos animais, tais como carne e leite. Diante desse quadro, a pesquisa de novos princípios ativos de origem vegetal para o controle de parasitas tem sido realizada de forma intensa nos últimos anos. Os óleos essenciais têm demonstrado elevada atividade biológica em diferentes ensaios laboratoriais e possuem uma mistura de sustâncias que podem agir de forma sinérgica. Essa linha de pesquisa em parasitologia veterinária é bastante recente no Brasil e existem muitas informações que precisam ser esclarecidas

Práticas de controle da verminose em ovinos e caprinos.

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Concentrações de ácido indolbutírico na propagação do umezeiro por alporquia.

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Diarréia em bezerros leiteiros lactantes: a doença e o manejo em diferentes unidades da Embrapa.

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High coercivity induced by mechanical milling in cobalt ferrite powders

In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe2O4 treated by mechanical milling with different grinding balls. The cobalt ferrite nanoparticles were prepared using a simple hydrothermal method and annealed at 500oC. The non-milled sample presented coercivity of about 1.9 kOe, saturation magnetization of 69.5 emu/g, and a remanence ratio of 0.42. After milling, two samples attained coercivity of 4.2 and 4.1 kOe, and saturation magnetization of 67.0 and 71.4 emu/g respectively. The remanence ratio MR/MS for these samples increase to 0.49 and 0.51, respectively. To investigate the influence of the microstructure on the magnetic behavior of these samples, we used X-ray powder diffraction (XPD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The XPD analysis by the Williamson-Hall plot was used to estimate the average crystallite size and strain induced by mechanical milling in the samples

Efeito da vitamina C no ganho de peso e em parâmetros hematológicos de tambaqui.

O objetivo deste trabalho foi avaliar o efeito da suplementação dietária com ácido L-ascórbico (vitamina C) no ganho de peso e em parâmetros hematológicos de juvenis de tambaqui, Colossoma macropomum