2,712 research outputs found

    The value function of an asymptotic exit-time optimal control problem

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    We consider a class of exit--time control problems for nonlinear systems with a nonnegative vanishing Lagrangian. In general, the associated PDE may have multiple solutions, and known regularity and stability properties do not hold. In this paper we obtain such properties and a uniqueness result under some explicit sufficient conditions. We briefly investigate also the infinite horizon problem

    Leptospirose humana: estudo sorológico de 29 anos em São Paulo, Brasil

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    A retrospective study of 9,335 cases of human leptospirosis in the state of S√£o Paulo, Brazil, diagnosed between 1969 and 1997 showed that the disease is endemic throughout the state. Middle-aged adults, with a range of 20-39 years, were most frequently infected (32.40%). The mean annual incidence was 0.53 per 100,000 population and the disease was more frequent in males (87.0%). Cases occurred mainly in January to April each year. A peak was observed in 1991 and 1996 which rainfall average was 159.9 and 160.3, respectively. These data emphasize the potential public health importance of leptospirosis in the state of S√£o Paulo, Brazil.Estudo retrospectivo com 9.335 casos de leptospirose humana no Estado de S√£o Paulo, Brasil, diagnosticados entre 1969 e 1997 mostrou que a doen√ßa √© end√™mica no estado. Adultos com idade entre 20-39 anos foram os mais infectados (32,40%) sendo 87,0% dos casos do sexo masculino. A incid√™ncia anual m√©dia foi de 0,53 por uma popula√ß√£o de 100.000. Casos ocorreram principalmente em janeiro a abril de cada ano. O maior n√ļmero de casos foi observado em 1991 e 1996 com m√©dia pluviom√©trica de 159,9 e 160,3, respectivamente. Estes dados enfatizam a import√Ęncia da leptospirose na sa√ļde p√ļblica no Estado de S√£o Paulo, Brasil

    Avalia√ß√£o preliminar da influ√™ncia de barreira vegetal com sans√£o-do-campo (Mimosa caesalpiniaefolia Benth.) sobre a entomofauna em cultura de caf√© (Coffea arabica) org√Ęnico na regi√£o de Ivinhema, MS.

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    bitstream/item/68820/1/023-shimbori-avaliacao.pdfPublicado também no Cadernos de Agroecologia, v. 7, n. 2, 2012

    Proposta de novos procedimentos de identifica√ß√£o de horizonte A h√ļmico.

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    No processo de revis√£o do SiBCS, v√°rias tentativas para redefinir horizonte A h√ļmico foram feitas (NAIME; SANTOS, 2007a e 2007b). Com a publica√ß√£o da 2a edi√ß√£o do SiBCS foi inclu√≠do o procedimento que considera a m√©dia ponderada da argila e o teor de carbono multiplicado pela espessura do suborizonte (EMBRAPA SOLOS, 2006). Esta proposta para identifica√ß√£o de horizonte A h√ļmico fundamenta-se nos princ√≠pios b√°sicos desenvolvidos por Carvalho et al. (2007), com modifica√ß√£o no c√°lculo do carbono org√Ęnico, isto √©, considerando o valor m√©dio (m√©dia ponderada) e n√£o o somat√≥rio do carbono multiplicado pela espessura do horizonte correspondente como vem sendo utilizado. H√° tamb√©m altera√ß√£o na equa√ß√£o para estimar o valor m√≠nimo de carbono requerido para horizonte A h√ļmico em fun√ß√£o do teor de argila. Em ambos os casos, tanto a argila como o carbono org√Ęnico s√£o relacionados √† espessura do horizonte A.bitstream/item/66559/1/doc97-2007-proposta-novos-procedimentos.pd

    Survey of a wastewater treatment plant microfauna by image analysis

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    The microfauna present in the activated sludge of a wastewater treatment plant is mainly composed by bacteria, protozoa and metazoa. The protozoan species are quite sensitive to physical, chemical and operational processes making them, thus, precious indicators of the state of the plant. Several authors already established relationships between the predominance of certain species or group and some parameters of the plant, such as the biotic indices namely the Sludge Biotic Index. All the above-mentioned procedures demand the identification, classification and quantification of the different species. Normally this is done manually, which implies both time and expertise. In the present work a semi-automatic protozoan recognition procedure by means of image analysis is attempted. The program built for this purpose (ProtoRec v.3) was also used to study the evolution of the microfauna during transient operation times (stoppage and re-run). The results were rather satisfactory in terms of protozoa recognition and the survey of the transient phase allowed verifying the aging and degradation of the microfauna by means of the different predominant species

    Estudo por An√°lise de Imagem do Comportamento de uma Esta√ß√£o de Tratamento de Efluentes sob Condi√ß√Ķes Transientes

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    A microfauna presente numa esta√ß√£o de tratamento de efluentes por lamas activadas √© composta essencialmente por bact√©rias, protozo√°rios e metazo√°rios. Os protozo√°rios apresentam uma sensibilidade aos fen√≥menos f√≠sico-qu√≠micos e operacionais que os tornam indicadores do estado de funcionamento da esta√ß√£o. A literatura apresenta rela√ß√Ķes entre a abund√Ęncia de uma certa esp√©cie ou grupo e par√Ęmetros da esta√ß√£o. Uma outra possibilidade √© a qualifica√ß√£o do estado da ETAR atrav√©s de √≠ndices bi√≥ticos como o SBI. Todos estes procedimentos exigem uma identifica√ß√£o, classifica√ß√£o e quantifica√ß√£o das esp√©cies presentes. Geralmente isto √© feito manualmente, o que implica tempo e muitas vezes a presen√ßa de um t√©cnico especializado. Neste trabalho √© proposto um procedimento para reconhecimento semi-autom√°tico das esp√©cies de protozo√°rios por an√°lise de imagem. Este programa (ProtoRec v.2) foi em seguida utilizado para estudar a evolu√ß√£o da microfauna durante per√≠odos de transi√ß√£o (paragem e arranque da esta√ß√£o). Os resultados obtidos foram satisfat√≥rios em rela√ß√£o ao reconhecimento das esp√©cies pelo programa e o acompanhamento da esta√ß√£o permitiu-nos verificar a degrada√ß√£o e envelhecimento da lama e o aparecimento de protozo√°rios que evidenciam tal facto

    Survey of protozoa and metazoa populations in wastewater treatment plants by image analysis and discriminant analysis

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    The biota present in the activated sludge of a wastewater treatment plant are mainly composed of bacteria, Protozoa and Metazoa. The Protozoa and Metazoa species are important micro-organisms taking part in the ecosystem balance in wastewater treatment plants and are quite sensitive to physical, chemical and operational processes. Several authors have established relationships between the predominance of certain species or groups and some variables of the plant. Such analysis demands the identification and quantification of the different species, which requires skilled workers, specializing in zoology or protozoology, and is time-consuming. To overcome those problems, semi-automatic image analysis and discriminant analysis were carried out for the identification procedures. The overall results were very promising in terms of Protozoa and Metazoa group recognition and of survey of plant conditions. Copyright 2004 John Wiley & Sons, Ltd.Financial support for the co-operation between the Portuguese (Braga) and French (Nancy) teams was provided by the French Embassy in Portugal and ICCTI (Portugal). A. L. Amaral was supported by a PhD grant (PRAXIS XXI/BD/20325/99) of ‚ÄėFunda√ß√£o para a Ci√™ncia e Tecnologia‚Äô (Portugal). M. da Motta was supported by a grant of the National Council of Scientific and Technological Development of Brazil (CNPq)

    Study of protozoa population in wastewater treatment plants by image analysis

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    Protozoa are important micro-organisms taking part to the ecosystem balance in wastewater treatment plants. A procedure for their semi-automated identification and counting based on image analysis is proposed. The main difficulty is the segmentation of the protozoa as most of them are in contact with the sludge. The protozoa are characterized by the size of their silhouette (area and length) and three shape factors (elongation, circularity and eccentricity). The identification is performed after projecting the resulting 5D space into a 3D space of Principal Components. The rate of automated identification is actually higher than 50% for some of the species found commonly in activated sludge
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