77 research outputs found

    Estudo e elaboração de um conjunto de regras para sintonia de performance em aplicações de banco de dados

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    Este artigo tem por objetivo apresentar parte do estudo realizado sobre sintonia de performance de banco de dados que consiste em levantar e propor um conjunto de regras que melhore o desempenho de aplicações de banco de dados. São apresentadas algumas considerações sobre sintonia de performance e os aspectos de implementação de sistema de banco de dados que causam impacto no desempenho da aplicação. As regras estudadas referemse á arquitetura do sistema gerenciador de banco de dados ORACLE utilizado como estudo de caso e uma delas é analisada para ilustrar o problema. Além disso, é definido um conjunto de cenários que representam contextos específicos de aplicações reais e que serão utilizados para validar a aplicabilidade das regras propostas. O conjunto de regras será testado para o conjunto de cenários através de um protótipo de ferramenta de tuning baseada em conhecimento. Tal ferramenta deverá auxiliar o administrador de banco de dados no diagnóstico de problemas de performance.The purpose of this article is to present a part of a study on database performance which consists of a survey of tuning situations and propose of a set of rules to improve performance of database applications. Some considerations about tuning will be done and the aspects of database system that cause impact on application performance will be presented. The studied rules rely on the ORACLE database management system architecture that has been used as a case study. Furthermore, one of rules is detailed in order to ilustrate the problem. In addition, a set of database production scenarios is defined which represents specific applications contexts that will be used to validate the proposed rules. The development of a prototype relying on a knowledge based diagnosys tool is under way. It shall be able to help database administrators in the identification of performance problems.Eje: Ingeniería de software. Bases de datosRed de Universidades con Carreras en Informática (RedUNCI

    Estudo e elaboração de um conjunto de regras para sintonia de performance em aplicações de banco de dados

    Get PDF
    Este artigo tem por objetivo apresentar parte do estudo realizado sobre sintonia de performance de banco de dados que consiste em levantar e propor um conjunto de regras que melhore o desempenho de aplicações de banco de dados. São apresentadas algumas considerações sobre sintonia de performance e os aspectos de implementação de sistema de banco de dados que causam impacto no desempenho da aplicação. As regras estudadas referemse á arquitetura do sistema gerenciador de banco de dados ORACLE utilizado como estudo de caso e uma delas é analisada para ilustrar o problema. Além disso, é definido um conjunto de cenários que representam contextos específicos de aplicações reais e que serão utilizados para validar a aplicabilidade das regras propostas. O conjunto de regras será testado para o conjunto de cenários através de um protótipo de ferramenta de tuning baseada em conhecimento. Tal ferramenta deverá auxiliar o administrador de banco de dados no diagnóstico de problemas de performance.The purpose of this article is to present a part of a study on database performance which consists of a survey of tuning situations and propose of a set of rules to improve performance of database applications. Some considerations about tuning will be done and the aspects of database system that cause impact on application performance will be presented. The studied rules rely on the ORACLE database management system architecture that has been used as a case study. Furthermore, one of rules is detailed in order to ilustrate the problem. In addition, a set of database production scenarios is defined which represents specific applications contexts that will be used to validate the proposed rules. The development of a prototype relying on a knowledge based diagnosys tool is under way. It shall be able to help database administrators in the identification of performance problems.Eje: Ingeniería de software. Bases de datosRed de Universidades con Carreras en Informática (RedUNCI

    Occurrence of Magellanic Penguins along the Northeast Brazilian Coast during 2008 Austral Winter

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    During the austral winter of 2008, thousands of penguins traveled to low latitudes along the South Atlantic coast of South America. The atmospheric and oceanic conditions from April to July 2008 may account for the penguins' unusual geographic distribution. During that period, South Atlantic coastal waters were cooler; the wind anomalies had northward and onshore components; the ocean's coastal region presented northward currents that favored the penguins to travel toward lower latitudes. This anomalous climate regime resulted from extreme meteorological frontal systems that occurred mainly during June 2008. Three consecutive extreme midlatitude cyclones produced strong wind shear that resulted in the northward oceanic flow along the South American eastern shoreline favoring the penguins to be spotted in northern tropical waters

    Coastal Ocean Forecasting: science foundation and user benefits

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    The advancement of Coastal Ocean Forecasting Systems (COFS) requires the support of continuous scientific progress addressing: (a) the primary mechanisms driving coastal circulation; (b) methods to achieve fully integrated coastal systems (observations and models), that are dynamically embedded in larger scale systems; and (c) methods to adequately represent air-sea and biophysical interactions. Issues of downscaling, data assimilation, atmosphere-wave-ocean couplings and ecosystem dynamics in the coastal ocean are discussed. These science topics are fundamental for successful COFS, which are connected to evolving downstream applications, dictated by the socioeconomic needs of rapidly increasing coastal populations

    Global perspectives on observing ocean boundary current systems

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    Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations.Fil: Todd, Robert E.. Woods Hole Oceanographic Institution; Estados UnidosFil: Chavez, Francisco. Monterey Bay Aquarium Research Institute; Estados UnidosFil: Clayton, Sophie. Old Dominion University; Estados UnidosFil: Cravatte, Sophie E.. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Francia. Universite de Toulouse; FranciaFil: Goes, Marlos P.. University of Miami; Estados UnidosFil: Graco, Michelle I.. Instituto del Mar del Peru; PerúFil: Lin, Xiaopei. Ocean University of China; ChinaFil: Sprintall, Janet. University of California; Estados UnidosFil: Zilberman, Nathalie V.. University of California; Estados UnidosFil: Archer, Matthew. California Institute of Technology; Estados UnidosFil: Arístegui, Javier. Universidad de Las Palmas de Gran Canaria; EspañaFil: Balmaseda, Magdalena A.. European Centre for Medium-Range Weather Forecasts; Reino UnidoFil: Bane, John M.. University of North Carolina; Estados UnidosFil: Baringer, Molly O.. Atlantic Oceanographic and Meteorological Laboratory ; Estados UnidosFil: Barth, John A.. State University of Oregon; Estados UnidosFil: Beal, Lisa M.. University of Miami; Estados UnidosFil: Brandt, Peter. Geomar-Helmholtz Centre for Ocean Research Kiel; AlemaniaFil: Calil, Paulo H.. Universidade Federal do Rio Grande; BrasilFil: Campos, Edmo. Universidade de Sao Paulo; BrasilFil: Centurioni, Luca R.. University of California; Estados UnidosFil: Chidichimo, María Paz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Cirano, Mauro. Universidade Federal do Rio de Janeiro; BrasilFil: Cronin, Meghan F.. National Oceanic and Atmospheric Administration. Pacific Marine Environmental Laboratory; Estados UnidosFil: Curchitser, Enrique N.. Rutgers University; Estados UnidosFil: Davis, Russ E.. University of California; Estados UnidosFil: Dengler, Marcus. Geomar-Helmholtz Centre for Ocean Research Kiel; AlemaniaFil: DeYoung, Brad. Memorial University of Newfoundland; CanadáFil: Dong, Shenfu. University of Miami; Estados UnidosFil: Escribano, Ruben. Universidad de Concepción; ChileFil: Fassbender, Andrea J.. Monterey Bay Aquarium Research Institute; Estados Unido

    Significant genetic differentiation among populations of Anomalocardia brasiliana (Gmelin, 1791): A bivalve with planktonic larval dispersion

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    Four Brazilian populations of Anomalocardia brasiliana were tested for mutual genetic homogeneity, using data from 123 sequences of the mtDNA cytochrome oxidase c subunit I gene. A total of 36 haplotypes were identified, those shared being H3 (Canela Island, Prainha and Acupe) and both H5 and H9 (Prainha and Acupe). Haplotype diversity values were high, except for the Camurupim population, whereas nucleotide values were low in all the populations, except for that of Acupe. Only the Prainha population showed a deviation from neutrality and the SSD test did not reject the demographic expansion hypothesis. Fst values showed that the Prainha and Acupe populations represent a single stock, whereas in both the Canela Island and Camurupim stocks, population structures are different and independent. The observed structure at Canela Island may be due to the geographic distance between this population and the remainder. The Camurupim population does not share any haplotype with the remaining populations in northeastern Brazil. The apparent isolation could be due to the rocky barrier located facing the mouth of the Mamanguape River. The results highlight the importance of wide-scale studies to identify and conserve local genetic diversity, especially where migration is restricted

    Global perspectives on observing ocean boundary current systems

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    © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Todd, R. E., Chavez, F. P., Clayton, S., Cravatte, S., Goes, M., Greco, M., Ling, X., Sprintall, J., Zilberman, N., V., Archer, M., Aristegui, J., Balmaseda, M., Bane, J. M., Baringer, M. O., Barth, J. A., Beal, L. M., Brandt, P., Calil, P. H. R., Campos, E., Centurioni, L. R., Chidichimo, M. P., Cirano, M., Cronin, M. F., Curchitser, E. N., Davis, R. E., Dengler, M., deYoung, B., Dong, S., Escribano, R., Fassbender, A. J., Fawcett, S. E., Feng, M., Goni, G. J., Gray, A. R., Gutierrez, D., Hebert, D., Hummels, R., Ito, S., Krug, M., Lacan, F., Laurindo, L., Lazar, A., Lee, C. M., Lengaigne, M., Levine, N. M., Middleton, J., Montes, I., Muglia, M., Nagai, T., Palevsky, H., I., Palter, J. B., Phillips, H. E., Piola, A., Plueddemann, A. J., Qiu, B., Rodrigues, R. R., Roughan, M., Rudnick, D. L., Rykaczewski, R. R., Saraceno, M., Seim, H., Sen Gupta, A., Shannon, L., Sloyan, B. M., Sutton, A. J., Thompson, L., van der Plas, A. K., Volkov, D., Wilkin, J., Zhang, D., & Zhang, L. Global perspectives on observing ocean boundary current systems. Frontiers in Marine Science, 6, (2010); 423, doi: 10.3389/fmars.2019.00423.Ocean boundary current systems are key components of the climate system, are home to highly productive ecosystems, and have numerous societal impacts. Establishment of a global network of boundary current observing systems is a critical part of ongoing development of the Global Ocean Observing System. The characteristics of boundary current systems are reviewed, focusing on scientific and societal motivations for sustained observing. Techniques currently used to observe boundary current systems are reviewed, followed by a census of the current state of boundary current observing systems globally. The next steps in the development of boundary current observing systems are considered, leading to several specific recommendations.RT was supported by The Andrew W. Mellon Foundation Endowed Fund for Innovative Research at WHOI. FC was supported by the David and Lucile Packard Foundation. MGo was funded by NSF and NOAA/AOML. XL was funded by China’s National Key Research and Development Projects (2016YFA0601803), the National Natural Science Foundation of China (41490641, 41521091, and U1606402), and the Qingdao National Laboratory for Marine Science and Technology (2017ASKJ01). JS was supported by NOAA’s Global Ocean Monitoring and Observing Program (Award NA15OAR4320071). DZ was partially funded by the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) under NOAA Cooperative Agreement NA15OAR4320063. BS was supported by IMOS and CSIRO’s Decadal Climate Forecasting Project. We gratefully acknowledge the wide range of funding sources from many nations that have enabled the observations and analyses reviewed here

    Intraseasonal variability of the North Brazil Undercurrent forced by remote winds

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    Intraseasonal signals with periods of 2 to 3 weeks in near-surface alongshore current measurements are detected from four moorings (K1 - K4) deployed from 2000 to 2004 at the 11{degree sign}S section close to the Brazilian coast as part of the German CLIVAR Tropical Atlantic Variability Project. This section crosses the path of the North Brazil Undercurrent, the most powerful western boundary current in the South Atlantic Ocean. We investigate the origin of this intraseasonal variability of the North Brazil Undercurrentby relating the oceanic oscillation of the alongshore currents to its atmospheric counterpart, the meridional wind stress. On average, the results indicate a well-defined lagged (10 days) correlation (~0.6) structure between meridional wind stress and alongshore currents. The oceanic region with the highest cross-correlations is identified as a relatively narrow band along the Brazilian coast, from 22{degree sign}-36{degree sign}S and 40{degree sign}-50{degree sign}W, bounded in the north by an eastward change in coastline orientation. The cross-wavelet transform establishes the common power between the time series of meridional wind stress and alongshore currents, predominantly during austral winter and spring. These signals propagate equatorward with an alongshore speed of 285{plus minus}63 km day-1, consistent with Coastal Trapped Wave theory
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