53,475 research outputs found

    De Branges spaces and Krein's theory of entire operators

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    This work presents a contemporary treatment of Krein's entire operators with deficiency indices (1,1)(1,1) and de Branges' Hilbert spaces of entire functions. Each of these theories played a central role in the research of both renown mathematicians. Remarkably, entire operators and de Branges spaces are intimately connected and the interplay between them has had an impact in both spectral theory and the theory of functions. This work exhibits the interrelation between Krein's and de Branges' theories by means of a functional model and discusses recent developments, giving illustrations of the main objects and applications to the spectral theory of difference and differential operators.Comment: 37 pages, no figures. The abstract was extended. Typographical errors were corrected. The bibliography style was change

    Avaliação de acesso, uso e manejo de água para consumo humano no Semiárido brasileiro.

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    Esse estudo avaliou a sustentabilidade do Programa Cisternas, quanto à sua implementação no semiárido nordestino, nas seguintes dimensões: a) cobertura do programa, b) localização, c) percepção quanto aos efeitos do programa sobre as condições de vida dos beneficiários; e d) condições e capacidade de manutenção das cisternas construídas. As informações sobre a avaliação são resultantes de entrevistas realizadas junto a 1.866 famílias beneficiárias. A condição de propriedade do domicílio, localização, acabamento, tipo de cobertura, tipo e forma de escoamento do banheiro, trabalho e indicadores de rendimento, permitiram afirmar que a população beneficiária do Programa Cisternas detém o perfil das famílias carentes da região. Outros resultados são: 98,76 % das famílias consideraram a cisterna muito importante e que houve melhoria na qualidade de vida (92,71 %), apesar de não ter influenciado sua renda (49,95 %). No entanto, poucos domicílios (± 21%), utilizam apenas a cisterna como forma de abastecimento para uso doméstico. Os demais utilizam, também, águas provenientes de outras fontes como açudes, barragens ou lagoas (30,92 %) e cacimba/ nascente (12,81 %). Quanto ao treinamento recebido para o uso e manejo correto das cisternas, 89,82 % dos entrevistados o consideraram adequado

    Determinação da qualidade da água armazenada em cisternas por meio de parâmetros físicos, químicos e microbiológicos.

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    Este trabalho avaliou a qualidade da água para o consumo humano, armazenada em cisternas localizadas em 63 comunidades rurais pertencentes a 46 (quarenta e seis) municípios de nove Estados da região semiárida. Foram realizadas análises físicas, químicas e microbiológicas em 777 amostras de água abrangendo mananciais, cisternas e reservatórios caseiros. A partir dos resultados das análises físicas e químicas foi elaborado o Índice de Uso da Água Doméstica (IUD) para monitorar a qualidade da água das cisternas e identificar a sua procedência. O IUD foi calculado a partir dos valores médios dos dados obtidos com o auxílio do software Statistical Analysis System, utilizando o procedimento Factor. A análise do componente principal agrupou o conjunto de variáveis pré-selecionadas em quatro indicadores: salinidade, alcalinidade, poluição da água e saúde da água. Como resultado há agregação de 48 pontos amostrados com IUD elevado, 48 com IUD alto, 63 com IUD médio e 618 com IUD baixo, significando que a maioria das cisternas apresenta água de boa qualidade. Observou-se que a maioria das cisternas (97,18 %) está localizada em territórios onde predominam as águas superficiais do tipo bicarbonatadas e cloretadas, sódicas e mistas. Dessa forma, ao se detectar estas características físicas e químicas nas águas armazenadas nas cisternas, pode-se concluir que a mesma não é proveniente de captação de água de chuva e sim de outras fontes alternativas de abastecimento. Foi constatada a ausência de coliformes totais em 79,15 % das amostras e ausência de Escherichia coli em 94,08 %, O que resulta em água de boa qualidade

    Population dynamics of Penaeus indicus at Sofala Bank, Mozambique: a preliminary study

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    Length-based methods are used to estimate growth and mortalities of Penaeus indicus at Sofala Bank in Mozambique. This Penaeid shrimp is one of the most important species in the fishery as it constitutes 45% of the catches and has a great influence in their trend. First estimates of growth parameters for this species in Mozambique are presented and a comparison of the derived mortalities with the previous estimates is made

    Comparison of solar radio and EUV synoptic limb charts during the present solar maximum

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    The present solar cycle is particular in many aspects: it had a delayed rising phase, it is the weakest of the last 100 years, and it presents two peaks separated by more than one year. To understand the impact of these characteristics on the solar chromosphere and coronal dynamics, images from a wide wavelength range are needed. In this work we use the 17~GHz radio continuum, formed in the upper chromosphere and the EUV lines 304 and 171~{\AA}, that come from the transition region (He II) and the corona (Fe IX, X), respectively. We analyze daily images at 304 and 171~{\AA} obtained by the Atmospheric Imaging Assembly (AIA). The 17~GHz maps were obtained by the Nobeyama Radioheliograph (NoRH). To construct synoptic limb charts, we calculated the mean emission of delimited limb areas with 100" wide and angular separation of 55^\circ. At the equatorial region, the results show an hemispheric asymmetry of the solar activity. The northern hemisphere dominance is coincident with the first sunspot number peak, whereas the second peak occurs concurrently with the increase in the activity at the south. The polar emission reflects the presence of coronal holes at both EUV wavelengths, moreover, the 17~GHz polar brightenings can be associated with the coronal holes. Until 2013, both EUV coronal holes and radio polar brightenings were more predominant at the south pole. Since then they have not been apparent in the north, but thus appear in the beginning of 2015 in the south as observed in the synoptic charts. This work strengthens the association between coronal holes and the 17~GHz polar brightenings as it is evident in the synoptic limb charts, in agreement with previous case study papers. The enhancement of the radio brightness in coronal holes is explained by the presence of bright patches closely associated with the presence of intense unipolar magnetic fields.Comment: 6 pages, 5 figures. Acccepted for publication in Astronomy & Astrophysic

    Astrophysical and Cosmological Information from Large-scale sub-mm Surveys of Extragalactic Sources

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    We present a quantitative analysis of the astrophysical and cosmological information that can be extracted from the many important wide-area, shallow surveys that will be carried out in the next few years. Our calculations combine the predictions of the physical model by Granato et al. (2004) for the formation and evolution of spheroidal galaxies with up-to-date phenomenological models for the evolution of starburst and normal late-type galaxies and of radio sources. We compute the expected number counts and the redshift distributions of these source populations separately and then focus on proto-spheroidal galaxies. For the latter objects we predict the counts and redshift distributions of strongly lensed sources at 250, 350, 500, and 850 micron, the angular correlation function of sources detected in the surveys considered, the angular power spectra due to clustering of sources below the detection limit in Herschel and Planck surveys. An optimal survey for selecting strongly lensed proto-spheroidal galaxies is described, and it is shown how they can be easily distinguished from the other source populations. We also discuss the detectability of the imprints of the 1-halo and 2-halo regimes on angular correlation functions and clustering power spectra, as well as the constraints on cosmological parameters that can be obtained from the determinations of these quantities. The novel data relevant to derive the first sub-millimeter estimates of the local luminosity functions of starburst and late-type galaxies, and the constraints on the properties of rare source populations, such as blazars, are also briefly described.Comment: 16 pages, 10 figures. Accepted for publication on MNRA
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