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Historical Evolution of the Trophic and Limnological Relationships in the Itaipu Reservoir:Top-Down and Bottom-Up Effects upon Fish Production

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Advances in Bioscience and Biotechnology 2015年第6期6卷 390-407页

作者： Rinaldo antonio Ribeiro Filho Miguel Petrere Junior angelo antonio agostinho Simone Friderigi Benassi Julia Myriam de Almeida Pereira Edson Kiyoshi Okada Curso de Engenharia de Pesca Universidade Estadual Paulista(Unesp)RegistroBrazil Programa de Pos Graduacao em Diversidade Bilogica e Conservacao Universidade Federal de Sao Carlos(UFSCar)SorocabaBrazil Programa de Pos Graduacao em Sustentabilidade em Ecossistemas Marinhos e Costeiros UNISANTASantosBrazil Departamento de Biologia Nucleo de Pesquisas em LimnologiaIctiologia e AquiculturaUniversidade Estadual de MaringaParanaBrazil Divisao de Reservatorio(MARR.CD) Itaipu BinacionalFoz do IguaçuBrazil

Many experimental studies have contributed to the development of the theory of trophic chains in lacustrine habitats. They have revealed the important role played by fish, a subject that has been mostly ignored by limnological studies for the past few decades. Most of these studies were developed in Europe and in the United States. The general applicability of this theory has not yet been tested in subtropical and tropical habitats. In spite of controversies, the bottom-up: top-down trophic cascade hypotheses are the most adopted conceptual models. In this context, we examined if these hypotheses may be corroborated by data from the subtropical Itaipu Reservoir. A negative effect was verified between water transparency and total suspended solids. The detritivorous fish exerted a controlling effect on chlorophyll-a concentrations. Bottom-up effects were detected in four trophic levels, and top-down was detected in just one trophic level. The limnological variates influenced the chlorophyll-a concentration, which indicated that the lnTKN plus the effect of the quarter and the reservoir zone (and their interaction) were important.

关键词： Reservoir Trophic Cascade Top-Down Bottom-Up Limnology Biotic Community

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Pesticide Contamination in Land Reform Settlements in Brazil： Empirical Evidences from Caiaponia, Goias State

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Journal of Environmental Science and Engineering(A) 2013年第3期2卷 197-202页

作者： Alcido Elenor Wander Cleyzer Adrian da Cunha agostinho Dirceu Didonet Brazilian Agricultural Research Corporation (Embrapa) Santo Antonio de Goias Goias 75375000 Brazil Department of Postgraduate Program in Agribusiness Federal University of Goias Goiania Goias 74001970 Brazil Department of Postgraduate Program in Regional Development Faculdades Alves Faria (ALFA) Goiania Goias 74445190Brazil

Brazil is the largest consumer of pesticides worldwide. Public health studies in Brazil show that inadequate use of pesticides increases the incidence of accidents and contamination of poor rural communities. This study sought to identify factors that determine the occurrence of problems with pesticides in a typical Brazilian land reform settlement. The study was carried out in Caiaponia, Goias state. In the empirical analysis, the econometric model pro bit was used. The dependent variable was the existence of health problems in the family setting that are caused by pesticides. The independent variables were the family size; the attendance to any church, whether Catholic or Protestant; if farmers received any technical assistance; the current health condition of the family, and if there are exacerbated erosion problems on the farm. Data from 28 farmers were collected through a structured questionnaire. Among the main findings, larger families have a higher probability of accidents involving pesticides. The current healthy conditions of family and the problems of soiled gradation in the farm imply are duction in the likelihood of contamination with pesticides. These two results indicate that rural households that have good health condition and have experienced environmental degradation on their farm have higher environmental awareness.

关键词： Pesticide use environmental awareness health issues.

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Comparative Study of Slope Soils Analysis by Using Limit Equilibrium and Finite Element Methods

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International Journal of Geosciences 2022年第12期13卷 1089-1102页

作者： Kempena Adolphe Watha Ndoudy Noël Obami Ondon Harmel Mbilou Urbain Gampio antonio Olimpio Gonçalves Rafael Guardado Lacaba Boudzoumou Florent Department of Geology Faculty of Sciences and Techniques Marien Ngouabi University Brazzaville Republic of Congo Mechanical Energy and Engineering Laboratory Higher National Polytechnic School Marien Ngouabi University Brazzaville Republic of Congo Department of Geology Faculty of Sciences Agostinho Neto University Luanda Angola Department of Geology Faculty of Mines and Geology Higher Institute of Mines and Metallurgy Moa Cuba

The slope soil analysis remains a corporate concern in construction activities. Because of its significance, the evaluation of slope soil stability has called widespread attention to several researchers all over the world. Many methods have been technologically advanced to evaluate the stability of slopes soils founded on distinct expectations and circumstances. Every method has specific benefits and limits. This work makes a comparison among safety factors and slip surfaces of slopes soils based on using Limit Equilibrium and Finite Element methods. Therefore, SLIDE 6.0 and PLAXIS 8.0 software were used for Limit Equilibrium and Finite Element methods, respectively. The computations of safety factors were performed for diverse shapes of slopes including different types of soils. Failure surfaces and values of safety factors obtained were compared for both methods used. It was noticed that the safety factors obtained from Limit Equilibrium methods were larger than of which is obtained by the finite element code. Moreover, an important change is noticed between the slip surfaces obtained by using both approaches.

关键词： Slopes Soils Slip Surface Limit Equilibrium Finite Element Factor of Safety

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