68,894 research outputs found
Propuesta de rediseño hidráulico a nivel de prefactibilidad del sistema de abastecimiento de agua potable en el municipio de El Rosario departamento de Carazo
La presente monografía es una investigación que tiene por objetivo proponer un rediseño hidráulico a nivel a prefactibilidad en el sistema de abastecimiento de agua potable, para mejorar las condiciones y calidad de vida a la población del municipio de El Rosario.
Normas técnicas para el diseño de abastecimiento y potabilización de agua potable (NTON 09 003-99), donde se obtuvieron los parámetros de diseño de sistemas de abastecimiento de agua potable e Instituciones gubernamentales como: Alcaldía de El Rosario, Ministerio de Salud (MINSA), Ministerio de Educación (MINED), y la Empresa Nacional de Acueductos y Alcantarillados (ENACAL
Ecological-transaction model approach of adolescents’ parental maltreatment and peer-bullying: the moderating role of bullying at the classroom
INTRODUCTION: The present study examined the ecological-transactional model delineated by Cicchetti and Lynch (1993) and the nature of the association between adolescents’ parental maltreatment and victimization and bullying at school. METHOD: Multivariate multilevel regression analyses were conducted on a sample of 2.852 adolescents between the ages of 12 and 17 from 25 secondary schools. Data was nested across 133 classrooms. Classrooms level variables and individual variables in relationship to parental maltreatment, behavioural disorders, sex, and bullying and victimization were included in the analysis. RESULTS: Results indicated that adolescents who reported suffering violence at home, showed more vulnerability to becoming victims of bullying at school, with the relationship being moderated by the level of bullying in the classroom. It was also examined the role of behavioural disorders and a relation between these factors was found amongst the bullies but not the victims. DISCUSSION AND CONCLUSION: This study uses the systemic perspective of ecological-transactional model on child maltreatment to show the importance between the school and home microsystems in the perpetuation of victimization. The results imply that what children experience at home might cause emotional and behavioural differences in varying classroom climates at school. Therefore, understanding the interactions between systems’ transaction of socialisation mechanisms might contribute for effective anti-bullying programs
Academic achievement in public higher education quality – A study on the effects of teachers’ commitment, teaching and evaluation methodologies in Nursing and Management degrees students.
The huge development of science and technology and the political, social and economic changes that characterize post-modern societies, demand from education systems a quality formation for all citizens. The great challenge of the XXI century in education is not only to ensure the acquisition of a range of varied and current competencies, but also to guarantee the quality of learning.
Therefore, the quality of education is a major concern to governments, politicians, academics and researchers and has been an issue widely discussed in scientific meetings and studied in several education research programs in different countries in the Western world. The results of research on education quality show a positive correlation between students’ academic performance and education quality. However, we must go further, it is necessary to research quality indicators, to understand how students perceive education quality. In order to achieve these goals, we developed an exploratory study with students from different higher education institutions in Portugal. Data sampling consists in students of different courses of higher education in Alentejo (Portugal). Data collection was conducted through a survey questionnaire. This work presents the analysis of students’ representations of quality, in Nursing and Management degrees in the University of Évora and in Beja Polytechnic Institute, under three dimensions: teacher’s commitment, teaching methodology and evaluation methodologies, as to relate the influence of these variables with the academic success of students
Neural Network Based Min-Max Predictive Control. Application to a Heat Exchanger
IFAC Adaptation and Learning in Control and Signal Processing. Cemobbio-Como. Italy. 2001Min-max model predictive controllers (MMMPC) have been proposed for the control of linear plants subject to bounded uncertainties. The implementation of MMMPC suffers a large computational burden due to the numerical optimization problem that has to be solved at every sampling time. This fact severely limits the class of processes in which this control is suitable. In this paper the use of a Neural Network (NN) to approximate the solution of the min-max problem is proposed. The number of inputs of the NN is determined by the order and time delay of the model together with the control horizon. For large time delays the number of inputs can be prohibitive. A modification to the basic formulation is proposed in order to avoid this later problem. Simulation and experimental results are given using a heat exchanger
The changing spatial distribution of economic activity across U.S. counties.
This paper studies the recent trends in the spatial distribution of economic activity in the United States. Using county-level employment data for 13 sector -which cover the entire economy- we apply semi-parametric techniques to estimate how agglometarion and congestion effects have changed between 1972 and 1992. Non-service sectors are found to be spreading out and moving away from centers of high economic activity to areas 20 to 60 kilometers away; service sectors, on the contrary, are increasingly concentrating in areas of high economic activity by attracting jobs from the surrounding 20 kilometers.Economic geography; Spatial externalities; U.S. counties;
RATES OF RETURN TO PRIVATE AGRICULTURAL EXTENSION: EVIDENCE FROM TWO FARM MANAGEMENT CENTERS IN EL SALVADOR
This paper evaluates the economic and the financial viability of implementing private farm management centers (FMC) in El Salvador. In doing so, an ex ante cost-benefit analysis is performed. The results of this analysis suggest that a combination of better farm prices (paid and received), reallocation of resources, and crop diversification that would be promoted by a FMC can lead to an increase in farm level profits that is sufficient to cover the operation of the center and to still generate net gains in household income.Farm Management,
Quintais agroflorestais como estratégia de sustentabilidade ecológica e econômica.
Resumo: Um estudo preliminar no contexto sócio-histórico do Assentamento Fazenda Pirituba, na região de Itapeva-SP, evidenciou que os quintais agroflorestais (QAs), são alternativas criadas autonomamente pelos agricultores familiares assentados na busca da reprodução social das famílias (alimentação e acesso ao mercado através do PAA). O estudo dos QAs, na medida em que os resgata da invisibilidade, poderá qualificar seu desenho e manejo, além de subsidiar políticas públicas para assentamentos rurais
Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.
Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and
Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants
Freezing of Nonlinear Bloch Oscillations in the Generalized Discrete Nonlinear Schrodinger Equation
The dynamics in a nonlinear Schrodinger chain in an homogeneous electric
field is studied. We show that discrete translational invariant
integrability-breaking terms can freeze the Bloch nonlinear oscillations and
introduce new faster frequencies in their dynamics. These phenomena are studied
by direct numerical integration and through an adiabatic approximation. The
adiabatic approximation allows a description in terms of an effective potential
that greatly clarifies the phenomenon.Comment: LaTeX, 7 pages, 6 figures. Improved version to appear in Phys. Rev.
A dinâmica do desenvolvimento da agroecologia no Brasil e na América Latina.
Resumo: A agroecologia é fonte de inspiração para a construção de sistemas agroalimentares ecológicos, a partir de 2003, foi fortalecida através de políticas públicas. O objetivo do artigo é o de apresentar as características, os elementos históricos determinantes da dinâmica de desenvolvimento da agroecologia no Brasil e em alguns países da América Latina, bem como suas diferentes facetas e o estado atual de sua estruturação. A metodologia utilizada é fruto de uma revisão bibliográfica, análise compreensiva de natureza sociológica e agronômica de um conjunto de estudos de casos. A agroecologia é atualmente legitimada pelo movimento social, redes científicas e técnicas, num cenário de tensão permanente e, de coexistência com a agricultura denominada de convencional ou produtivista
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