10,533 research outputs found

    On the nature of some SGRs and AXPs as rotation-powered neutron stars

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    We investigate the possibility that some SGRs/AXPs could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, LX/E˙rotL_X/\dot{E}_{\rm rot}, with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for LXL_X computed in the soft (2--10~keV) X-ray band. We compute the range of NS masses for which LX/E˙rot<1L_X/\dot{E}_{\rm rot}<1. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to LX/E˙rot>1L_X/\dot{E}_{\rm rot}>1 in two of them. We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2--10~keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give additional support to our results of a natural explanation of these sources in terms of ordinary pulsars. Including the hard X-ray emission observed in three sources of the group of potential rotation-powered NSs, this number of sources with LX/E˙rot<1L_X/\dot{E}_{\rm rot}<1 becomes seven. It remains open to verification 1) the accuracy of the estimated distances and 2) the possible contribution of the associated supernova remnants to the hard X-ray emission.Comment: 11 pages, 14 figures, to appear in A&

    Concentração da solução de injeção e frequência de fertirrigação em latossolo amarelo.

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    A concentração da solução de injeção tem sido pouco considerada na fertirrigação. Entretanto ela pode influenciar o estado salino do solo, com risco de aumentos instantâneos da salinidade, que pode com o tempo afetar as características químicas do solo, além de induzir problemas de entupimentos nos dutos de condução de água para as plantas. O trabalho objetivou definir o binômio concentração da solução de injeção e frequência de fertirrigação, isto é, definir a concentração da solução de injeção mais adequada para duas frequências de fertirrigação para a bananeira Grand Naine. O experimento foi realizado em solo de textura argilosa de Tabuleiro Costeiro com um delineamento experimental em blocos casualizados, em esquema fatorial 3 x 2 sendo três concentrações da solução de injeção (3, 10 e 15 g/L) x duas frequências de fertirrigação (3 e 7 dias). Foram avaliadas variáveis de crescimento e produção da bananeira e a condutividade elétrica do extrato de saturação (CEes) na zona radicular durante o ciclo da cultura. Os resultados mostraram que a faixa de concentração da solução injetora utilizada não acarretou elevação na CEes do solo suficiente para causar problemas de salinidade no mesmo ao longo do ciclo da bananeira. As diferentes concentrações e frequências de aplicação da solução injetora não tiveram efeito sobre a produtividade da cultivar estudada

    Phytoplankton biomass and zooplankton abundance on the south coast of Portugal (Sagres), with special reference to spawning of Loligo vulgaris

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    The importance of the south-west coast of Portugal as a spawning ground for the long-finned squid, Loligo vulgaris, was investigated between May 1993 and May 1994 at a site 3 Km East of Sagres. Hydrographic (temperature and salinity) observations were registered in situ and water samples were collected for laboratory determinations of chlorophyll a. Zooplankton was sampled with a 500 mm plankton net during 10mn trawls. Hydrographic and biological information was related to the occurrence of L. vulgaris egg masses at the site. The values of water temperature ranged from 13.0º C in January to 19.2º C in July, and the salinity varied between 35.3o/oo in May of 1993 and 38.0 o/oo, in November, December and March. The highest values for phytoplankton biomass were recorded in September and May, whereas the maximum zooplankton abundance was recorded between July and September. The most important zooplankton groups included cladocerans, copepods, crustacean larvae, fish eggs and appendicularians. We have concluded that the highest values for zooplankton abundance were recorded when the greater number of egg masses of L. vulgaris were observed

    Aminoácidos como recuperadores de plantas de milho intoxicadas por nicosulfuron.

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    Vertebroplastia percutânea por fractura osteoporótica

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    A Vertebroplastia Percutânea é uma técnica minimamente invasiva relativamente recente, que tem reconhecidas vantagens e aplicações em fracturas compressivas dos corpos vertebrais. Basicamente, consiste na injecção de um Cimento Acrílico no interior do corpo vertebral, e desse modo, minimizar e estabilizar fracturas compressivas dos corpos vertebrais, que são frequentemente de etiologia osteoporótica. Fortemente indicada no tratamento de fracturas incapacitantes, possui como complicação principal o extravasamento do Cimento. Este artigo pretende abordar a técnica, expondo suas indicações, vantagens e complicações mais frequentes. Esta permite reduzir a elevada taxa de morbilidade e impacto económico-social associado à Osteoporose.Percutaneous vertebroplasty is a relatively new minimally invasive technique, which has recognized advantages and applications in vertebral compression fracture. Basically consists of injecting acrylic cement inside the vertebral body, minimizing and stabilizing the compression fractures of vertebral bodies, which are often osteoporotic etiology. Strongly indicated for the treatment of debilitating fractures, has as major complication of cement leakage. This article intends to explain the technique, with their main indications, advantages and complications. This technique allows reducing the high rate of morbidity and socio-economic impact associated with Osteoporosis

    Coulomb and quantum oscillator problems in conical spaces with arbitrary dimensions

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    The Schr\"odinger equations for the Coulomb and the Harmonic oscillator potentials are solved in the cosmic-string conical space-time. The spherical harmonics with angular deficit are introduced. The algebraic construction of the harmonic oscillator eigenfunctions is performed through the introduction of non-local ladder operators. By exploiting the hidden symmetry of the two-dimensional harmonic oscillator the eigenvalues for the angular momentum operators in three dimensions are reproduced. A generalization for N-dimensions is performed for both Coulomb and harmonic oscillator problems in angular deficit space-times. It is thus established the connection among the states and energies of both problems in these topologically non-trivial space-times.Comment: 15 page
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