770 research outputs found

    Sub-terahertz, microwaves and high energy emissions during the December 6, 2006 flare, at 18:40 UT

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    The presence of a solar burst spectral component with flux density increasing with frequency in the sub-terahertz range, spectrally separated from the well-known microwave spectral component, bring new possibilities to explore the flaring physical processes, both observational and theoretical. The solar event of 6 December 2006, starting at about 18:30 UT, exhibited a particularly well-defined double spectral structure, with the sub-THz spectral component detected at 212 and 405 GHz by SST and microwaves (1-18 GHz) observed by the Owens Valley Solar Array (OVSA). Emissions obtained by instruments in satellites are discussed with emphasis to ultra-violet (UV) obtained by the Transition Region And Coronal Explorer (TRACE), soft X-rays from the Geostationary Operational Environmental Satellites (GOES) and X- and gamma-rays from the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The sub-THz impulsive component had its closer temporal counterpart only in the higher energy X- and gamma-rays ranges. The spatial positions of the centers of emission at 212 GHz for the first flux enhancement were clearly displaced by more than one arc-minute from positions at the following phases. The observed sub-THz fluxes and burst source plasma parameters were found difficult to be reconciled to a purely thermal emission component. We discuss possible mechanisms to explain the double spectral components at microwaves and in the THz ranges.Comment: Accepted version for publication in Solar Physic

    Gemini Observations of Disks and Jets in Young Stellar Objects and in Active Galaxies

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    We present first results from the Near-infrared Integral Field Spectrograph (NIFS) located at Gemini North. For the active galaxies Cygnus A and Perseus A we observe rotationally-supported accretion disks and adduce the existence of massive central black holes and estimate their masses. In Cygnus A we also see remarkable high-excitation ionization cones dominated by photoionization from the central engine. In the T-Tauri stars HV Tau C and DG Tau we see highly-collimated bipolar outflows in the [Fe II] 1.644 micron line, surrounded by a slower molecular bipolar outflow seen in the H_2 lines, in accordance with the model advocated by Pyo et al. (2002).Comment: Invited paper presented at the 5th Stromlo Symposium. 9 pages, 7 figures. Accepted for publication in Astrophysics & Space Scienc

    Plantio direto, adubação verde e suplementação com esterco de aves na produção orgânica de berinjela.

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    Sob manejo orgânico, foram avaliados, em Seropédica, RJ, os sistemas de plantio direto da berinjela(Solanum melongena) nas palhadas de Crotalaria juncea (crotalária), Pennisetum glaucum (milheto, cv. BRS 1501)e vegetação espontânea (pousio), em comparação com o plantio convencional (aração e gradagem ou enxada rotativa). Simultaneamente, foram avaliados três tipos de cultivo: berinjela em monocultura, em consórcio com crotalária e em consórcio com caupi (Vigna unguiculata, cv. Mauá). Não houve diferença entre os sistemas de plantio direto e convencional quanto à produção comercial da berinjela. A palhada da crotalária foi mais eficiente que a do milheto e do pousio para cobertura morta do solo e conseqüentemente o controle de plantas espontâneas foi maior. O cultivo simultâneo com as leguminosas não acarretou redução da produtividade da berinjela.Em um segundo estudo, foram comparados plantio direto (palhadas de crotalária e da vegetação espontânea) e plantio convencional, combinados com doses crescentes de cama de aviário (0, 100, 200 e 400 kg ha-1 de N)aplicada em cobertura. Em termos de aporte de biomassa, a crotalária foi novamente superior à vegetação espontânea.A berinjela respondeu à adubação orgânica, com produtividade máxima de 50,6 t ha-1 , correspondendo à maior dose empregada, contra 36,9 t ha-1 referentes ao controle

    Should health care professionals encourage living kidney donation?

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    Living kidney donation provides a promising opportunity in situations where the scarcity of cadaveric kidneys is widely acknowledged. While many patients and their relatives are willing to accept its benefits, others are concerned about living kidney programs; they appear to feel pressured into accepting living kidney transplantations as the only proper option for them. As we studied the attitudes and views of patients and their relatives, we considered just how actively health care professionals should encourage living donation. We argue that active interference in peoples’ personal lives is justified - if not obligatory. First, we address the ambiguous ideals of non-directivity and value neutrality in counselling. We describe the main pitfalls implied in these concepts, and conclude that these concepts cannot account for the complex reality of living donation and transplantation. We depict what is required instead as truthful information and context-relative counselling. We then consider professional interference into personal belief systems. We argue that individual convictions are not necessarily strong, stable, or deep. They may be flawed in many ways. In order to justify interference in peoples’ personal lives, it is crucial to understand the structure of these convictions. Evidence suggests that both patients and their relatives have attitudes towards living kidney donation that are often open to change and, accordingly, can be influenced. We show how ethical theories can account for this reality and can help us to discern between justified and unjustified interference. We refer to Stephen Toulmin’s model of the structure of logical argument, the Rawlsian model of reflective equilibrium, and Thomas Nagel’s representation of the particularistic position

    Low Complexity Regularization of Linear Inverse Problems

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    Inverse problems and regularization theory is a central theme in contemporary signal processing, where the goal is to reconstruct an unknown signal from partial indirect, and possibly noisy, measurements of it. A now standard method for recovering the unknown signal is to solve a convex optimization problem that enforces some prior knowledge about its structure. This has proved efficient in many problems routinely encountered in imaging sciences, statistics and machine learning. This chapter delivers a review of recent advances in the field where the regularization prior promotes solutions conforming to some notion of simplicity/low-complexity. These priors encompass as popular examples sparsity and group sparsity (to capture the compressibility of natural signals and images), total variation and analysis sparsity (to promote piecewise regularity), and low-rank (as natural extension of sparsity to matrix-valued data). Our aim is to provide a unified treatment of all these regularizations under a single umbrella, namely the theory of partial smoothness. This framework is very general and accommodates all low-complexity regularizers just mentioned, as well as many others. Partial smoothness turns out to be the canonical way to encode low-dimensional models that can be linear spaces or more general smooth manifolds. This review is intended to serve as a one stop shop toward the understanding of the theoretical properties of the so-regularized solutions. It covers a large spectrum including: (i) recovery guarantees and stability to noise, both in terms of 2\ell^2-stability and model (manifold) identification; (ii) sensitivity analysis to perturbations of the parameters involved (in particular the observations), with applications to unbiased risk estimation ; (iii) convergence properties of the forward-backward proximal splitting scheme, that is particularly well suited to solve the corresponding large-scale regularized optimization problem

    Human Rights and the Pink Tide in Latin America : Which Rights Matter?

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    Latin America witnessed the election of ‘new Left’ governments in the early 21 st century that, in different ways, sought to open a debate about alternatives to paradigms of neoliberal development. What has this meant for the way that human rights are understood and for patterns of human rights compliance? Using qualitative and quantitative evidence, this article discusses how human rights are imagined and the compliance records of new Left governments through the lens of the three ‘generations’ of human rights — political and civil, social and economic, and cultural and environmental rights. The authors draw in particular on evidence from Andean countries and the Southern Cone. While basic civil and individual liberties are still far from guaranteed, especially in the Andean region, new Left countries show better overall performances in relation to socio-economic rights compared to the past and to other Latin American countries. All new Left governments also demonstrate an increasing interest in ‘third generation’ (cultural and environmental) rights, though this is especially marked in the Andean Left. The authors discuss the tensions around interpretations and categories of human rights, reflect on the stagnation of first generation rights and note the difficulties associated with translating second and third generation rights into policy

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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