1,983 research outputs found

    Cross-correlation of the CMB and radio galaxies in real, harmonic and wavelet spaces: detection of the integrated Sachs-Wolfe effect and dark energy constraints

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    We report the first detection of the ISW effect in wavelet space, at scales in the sky around 7 degrees with a significance of around 3.3 sigma, by cross-correlating the WMAP first-year data and the NRAO VLA Sky Survey (NVSS). In addition, we present a detailed comparison among the capabilities of three different techniques for two different objectives: to detect the ISW and to put constraints in the nature of the dark energy. The three studied techniques are: the cross-angular power spectrum (CAPS, harmonic space), the correlation function (CCF, real space) and the covariance of the Spherical Mexican Hat Wavelet (SMHW) coefficients (CSMHW, wavelet space). We prove that the CSMHW is expected to provide a higher detection of the ISW effect for a certain scale. This prediction has been corroborated by the analysis of the data. The SMHW analysis shows that the cross-correlation signal is caused neither by systematic effects nor foreground contamination. However, by taking into account the information encoded in all the multipoles/scales/angles, the CAPS provides slightly better constraints than the SMHW in the cosmological parameters that define the nature of the dark energy. The limits provided by the CCF are wider than for the other two methods. Two different cases have been studied: 1) a flat Lambda-CDM universe and 2) a flat universe with an equation of state parameter different from -1. In the first case, the CAPS provides (for a bias value of b = 1.6) 0.59 < Lambda density < 0.84 (at 1 sigma CL). Moreover, the CAPS rejects the range Lambda density < 0.1 at 3.5 sigma, which is the highest detection of the dark energy reported up to date. In the second case, the CAPS gives 0.50 < dark energy density < 0.82 and -1.16 < w < 0.43 (at 1 sigma CL).Comment: 12 pages, 7 figures, accepted for publication in MNRAS. Analysis redone. Changes in the estimation of the cosmological parametres. Additional comparison between wavelets and more standard technique

    The CIB-lensing bispectrum: impact on primordial non-Gaussianity and detectability for the Planck mission

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    We characterize the cosmic infrared background (CIB)-lensing bispectrum which is one of the contributions to the three-point functions of cosmic microwave background (CMB) maps in harmonic space. We show that the CIB-lensing bispectrum has a considerable strength and that it can be detected with high significance in the Planck high-frequency maps. We also present forecasts of the contamination on different shapes of the primordial non-Gaussianity fnl parameter produced by the CIB-lensing bispectrum and by the extragalactic point sources bispectrum in the Planck high-resolution CMB anisotropy maps. The local, equilateral and orthogonal shapes are considered for ‘raw' single-frequency (i.e. without applying any component separation technique) and foreground-reduced Planck temperature maps. The CIB-lensing correlation seems to mainly affect orthogonal shapes of the bispectrum - with Δfnl(ort)=21\Delta f_{\rm nl}^{\rm (ort)} =-21 and −88 for the 143 and 217 GHz bands, respectively - while point sources mostly impact equilateral shapes, with Δfnl(eq)=160,54\Delta f_{\rm nl}^{\rm (eq)} =160, 54 and 60 at 100, 143 and 217 GHz. However, the results indicate that these contaminants do not induce any relevant bias on Planck fnl estimates when foreground-reduced maps are considered: using SEVEM for the component separation, we obtain Δfnl(ort)=10.5\Delta f_{\rm nl}^{\rm (ort)} =10.5 due to the CIB-lensing and Δfnl(eq)=30.4\Delta f_{\rm nl}^{\rm (eq)}=30.4 due to point sources, corresponding to 0.3σ and 0.45σ in terms of the Planck 2013 fnl uncertainty. The component separation technique is, in fact, able to partially clean the extragalactic source contamination and the bias is reduced for all the shapes. We have further developed single- and multiple-frequency estimators based on the Komatsu, Spergel & Wandelt formalism that can be implemented to efficiently detect this signa

    The angular power spectra of polarized Galactic synchrotron

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    We derive the angular power spectra of intensity and polarization of Galactic synchrotron emission in the range 36 < l < 10^3 from the Parkes survey mapping the southern Galactic plane at 2.4 GHz. The polarization spectra of both electric and magnetic parity up to l \simeq 10^3 are approximated very well by power laws with slope coefficients \simeq 1.4, quite different from the CMB spectra. We show that no problem should arise from Galactic synchrotron for measurements of CMB polarization in the cosmological window.Comment: 15 pages with 6 eps figures. Accepted for publication in New Astronom

    Down-Hole Heat Exchangers: Modelling of a Low-Enthalpy Geothermal System for District Heating

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    In order to face the growing energy demands, renewable energy sources can provide an alternative to fossil fuels. Thus, low-enthalpy geothermal plants may play a fundamental role in those areas—such as the Province of Viterbo—where shallow groundwater basins occur and conventional geothermal plants cannot be developed. This may lead to being fuelled by locally available sources. The aim of the present paper is to exploit the heat coming from a low-enthalpy geothermal system. The experimental plant consists in a down-hole heat exchanger for civil purposes and can supply thermal needs by district heating. An implementation in MATLAB environment is provided in order to develop a mathematical model. As a consequence, the amount of withdrawable heat can be successfully calculated

    Inundaciones urbanas

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    Urban waters

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    Urban Waters systems generally include both water supply & sanitation facilities (WSS). Sanitation refers to domestic and industrial sewage collecting and treatment; it does not include urban stormwater or solid waste management systems. Urban water form components of a sustainable urban environment and the use of the integrated water resource management (IWRM) concepts are needed for planning, implementation and maintenance of urban infrastructure. In urban environment, IWRM is referred to specifically as Integrated Urban Water Management (IUWM). In this paper urban development and its relations with urban waters in Brazil are assessed. Management of Water Resources in Brazil is developed by basins and the administration is Federal or from the state. This article assess the alternatives of water management in the city and the basin in the Brazilian institutional environment.As águas urbanas geralmente incluem abastecimento de água e saneamento. Nessa perspectiva, saneamento envolve a coleta de tratamento de efluentes domésticos e industriais, não inclui drenagem urbana, gestão dos resíduos sólidos, porque ainda perdura uma visão desatualizada da gestão das águas urbanas da cidade. Águas urbanas envolvem componentes que permitem o desenvolvimento ambiental sustentável e utilizam os conceitos da gestão integrada dos recursos hídricos (GIRH), necessários para planejamento, implementação e manutenção da infra-estrutura da cidade. Nesse contexto, ficam denominados Gestão Integrada das Águas Urbanas. Neste artigo, analisam-se o desenvolvimento urbano e suas relações com as águas urbanas no Brasil. A gestão dos recursos hídricos no Brasil é realizada por bacias hidrográficas, e o domínio é federal ou estadual. Examinam-se as possibilidades de gestão da água na cidade e na bacia hidrográfica no contexto institucional brasileiro

    The Role of the NRF2 Pathway in Maintaining and Improving Cognitive Function

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    Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a redox-sensitive transcription factor that binds to the antioxidant response element consensus sequence, decreasing reactive oxygen species and regulating the transcription of a wide array of genes, including antioxidant and detoxifying enzymes, regulating genes involved in mitochondrial function and biogenesis. Moreover, NRF2 has been shown to directly regulate the expression of anti-inflammatory mediators reducing the expression of pro-inflammatory cytokines. In recent years, attention has turned to the role NRF2 plays in the brain in different diseases such Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and others. This review focused on the evidence, derived in vitro, in vivo and from clinical trials, supporting a role for NRF2 activation in maintaining and improving cognitive function and how its activation can be used to elicit neuroprotection and lead to cognitive enhancement. The review also brings a critical discussion concerning the possible prophylactic and/or therapeutic use of NRF2 activators in treating cognitive impairment-related conditions

    Simulação hidrológica de rios com grandes planícies de inundação.

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    Conhecer o comportamento hidrológico de um rio permite investigar diversas questões ecológicas relacionadas. Além de descrever o comportamento hidrológico, é importante poder prevê-lo frente a cenários futuros, e modelos matemáticos têm sido largamente utilizados com essa finalidade. A simulação do escoamento em rios tem sido realizada principalmente com modelos unidimensionais acoplados ou não com células de armazenamento de água na planície. Para o caso de rios com grandes planícies de inundação, o extravasamento de água do canal para a planície e a propagação da inundação na planície governam a passagem da onda de cheia. Caso o interesse do estudo seja representar esses processos, métodos tradicionais não são adequados e uma abordagem recente tem sido proposta baseada no acoplamento de um modelo unidimensional para simular o escoamento na calha principal e um modelo tipo raster para simular o escoamento bidimensional na planície. Este artigo discute as dificuldades e desafios para a modelagem de rios com grandes planícies de inundação e as vantagens e limitações das diferentes abordagens empregadas. É apresentado um sistema de simulação desenvolvido com esse propósito, com resultados da aplicação ao Pantanal como exemplo
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