Estudio de viabilidad de la central hidroeléctrica de Plazakola

[ES]El objeto del presente estudio de viabilidad es estudiar la eficiencia y productividad de la Central Hidroeléctrica de Plazakola aportando diversas alternativas posibles que puedan ser técnica y económicamente viables. Para cada una de las soluciones propuestas se analizará la producción de energía así como el presupuesto estimado de las obras y equipos necesarios, comparándose entre ellas y determinando la solución óptima, que será desarrollada en el anteproyecto.

Generación de energía eléctrica por combustión de biomasa forestal mediante ciclo rankine. Central de 2MW

[ES]Este proyecto se centra en el estudio y diseño de una central de generación de energía eléctrica por medio de biomasa forestal. La motivación para la realización de este proyecto reside en la gran importancia que en los últimos años están tomando las energías renovables. El Calentamiento Global es un hecho que durante los últimos años ha llevado a la investigación y desarrollo de las energías alternativas, que frenan o contribuyen al ralentizamiento de este fenómeno. Por su parte la implantación de una planta como la que se estudia a continuación, no solo ayudaría a la reducción de emisiones netas de CO2 a la atmósfera, sino que también tendría numerosas ventajas como son la creación de empleo, la limpieza de bosques, lo que ayuda a la prevención de incendios y plagas, y proporcionaría una independencia energética. Los pasos que se van a seguir en el proyecto son los siguientes:  Explicar el alcance y los objetivos del proyecto. Desarrollar las posibles alternativas que existen para la valorización de la biomasa forestal, incluyendo un resumen de las ventajas y desventajas que cada una presenta. Informe detallado de la alternativa seleccionada, la combustión, que incluye la explicación del proceso en la planta desde que el residuo sale del bosque, hasta la obtención de la energía eléctrica. Análisis económico y rentabilidad de la planta. Realizar el cronograma del proyecto. Por último se realizará un análisis de los posibles riesgos.

Diet and condition of American Alligators (Alligator mississippiensis)in three central Florida lakes

Understanding the diet of crocodilians is important because diet affects condition, behavior, growth, and reproduction. By examining the diet of crocodilians, valuable knowledge is gained about predator-prey interactions and prey utilization among habitats. In this study, I examined the diet and condition of adult American alligators (Alligator mississippiensis) in three central Florida lakes, Griffin, Apopka, and Woodruff. Two hundred adult alligators were captured and lavaged from March through October 2001, from April through October 2002, and from April through August 2003. Alligators ate a variety of vertebrate and invertebrate prey, but vertebrates were more abundant and fish dominated alligator diets in the lakes. Species composition of fish varied among the lakes. The majority of the diet of alligators from Lakes Apopka and Woodruff was fish, 90% and 84% respectively. Lake Apopka alligators consumed a significantly (P = 0.006) higher proportion of fish in their diet. Fish were 54% of the diet of Lake Griffin alligators and the infrequent occurrence of reptiles, mammals, birds, and amphibians often resulted in a large biomass. Differences in alligator diets among lakes may be due to differences in sample size (higher numbers of samples from Lake Griffin), prey availability, habitat, prey vulnerability, or prey size. Alligator condition (Fulton’s Condition Factor, K) was significantly (P < 0.001) different among the lakes. Alligators from Lake Apopka had the highest condition, followed by those from Lake Griffin, and alligators from Lake Woodruff had the lowest condition. Composition of fish along with diversity and equitability of fish in alligator diets may have contributed to differences in condition among lakes. Condition was probably also due to factors other than diet such as alligator hunting behavior, alligator density, or year-round optimal temperature that prolongs feeding. The observed diet and condition differences probably reflect both habitat differences and prey availability in these three lakes.

Some central limit theorems for doubly restricted partitions

Let P_{K, L}(N) be the number of unordered partitions of a positive integer N into K or fewer positive integer parts, each part not exceeding L. A distribution of the form

Ʃ/N≤x P_K,L(N)

is considered first. For any fixed K, this distribution approaches a piecewise polynomial function as L increases to infinity. As both K and L approach infinity, this distribution is asymptotically normal. These results are proved by studying the convergence of the characteristic function.

The main result is the asymptotic behavior of P_K,K(N) itself, for certain large K and N. This is obtained by studying a contour integral of the generating function taken along the unit circle. The bulk of the estimate comes from integrating along a small arc near the point 1. Diophantine approximation is used to show that the integral along the rest of the circle is much smaller.

Structural capital, innovation capability, and company performance in technology-based colombian firms

[EN] In today s economy, innovation is considered to be one of the main driving forces behind business competitiveness, if not the most relevant one. Traditionally, the study of innovation has been addressed from different perspectives. Recently, literature on knowledge management and intellectual capital has provided new insights. Considering this, the aim of this paper is to analyze the impact of different organizational conditions i.e. structural capital on innovation capability and innovation performance, from an intellectual capital (IC) perspective. As regards innovation capability, two dimensions are considered: new idea generation and innovation project management. The population subject to study is made up of technology-based Colombian firms. In order to gather information about the relevant variables involved in the research, a questionnaire was designed and addressed to the CEOs of the companies making up the target population. The sample analyzed is made up of 69 companies and is large enough to carry out a statistical study based on structural equation modelling (partial least squares approach) using PLS-Graph software (Chin and Frye, 2003). The results obtained show that structural capital explains to a great extent both the effectiveness of the new idea generation process and of innovation project management. However, the influence of each specific organizational component making up structural capital (organizational design, organizational culture, hiring and professional development policies, innovation strategy, technological capital, and external structure) varies. Moreover, successful innovation project management is the only innovation capability dimension that exerts a significant impact on company performance.

Home range and habitat use by Kemp's Ridley turtles in West-Central Florida

The Kemp's ridley turtle (Lepidochelys kempii) is an endangered species whose recovery depends in part on the identification and protection of required habitats. We used radio and sonic telemetry on subadult Kemp's ridley turtles to investigate home-range size and habitat use in the coastal waters of west-central Florida from 1994 to 1996. We tracked 9 turtles during May-August up to 70 days after release and fou.ld they occupied 5-30 km2 foraging ranges. Compositional analyses indicated that turtles used rock outcroppings in their foraging ranges at a significantly higher proportion than expected. based on availability within the study area. Additionally. turtles used live bottom (e.g .• sessile invertebrates) and green macroalgae habitats significantly more than seagrass habitat. Similar studies are needed through'mt the Kemp's ridley turtles' range to investigate regional and stage-specific differences in habitat use. which can then be used to conserve important foraging areas.

How central are clients in sexual networks created by commercial sex?

Sex workers are traditionally considered important vectors of transmission of sexually transmitted infections (STI). The role of clients is commonly overlooked, partially due to the lack of evidence on clients' position in the sexual network created by commercial sex. Contrasting the diffusion importance of sex workers and their clients in the map of their sexual encounters in two Web-mediated communities, we find that from diffusion perspective, clients are as important as sex workers. Their diffusion importance is closely linked to the geography of the sexual encounters: as a result of different movement patterns, travelling clients shorten network distances between distant network neighborhoods and thus facilitate contagion among them more than sex workers, and find themselves more often in the core of the network by which they could contribute to the persistence of STIs in the community. These findings position clients into the set of the key actors and highlight the role of human mobility in the transmission of STIs in commercial sexual networks.

Company financial performance: Does board size matter? Case of the EUROSTOXX50 index

[EN] This study analyzes the relationship between board size and economic-financial performance in a sample of European firms that constitute the EUROSTOXX50 Index. Based on previous literature, resource dependency and agency theories, and considering regulation developed by the OECD and European Union on the normative of corporate governance for each country in the sample, the authors propose the hypotheses of both positive linear and quadratic relationships between the researched parameters. Using ROA as a benchmark of financial performance and the number of members of the board as measurement of the board size, two OLS estimations are performed. To confirm the robustness of the results the empirical study is tested with two other similar financial ratios, ROE and Tobin s Q. Due to the absence of significant results, an additional factor, firm size, is employed in order to check if it affects firm performance. Delving further into the nature of this relationship, it is revealed that there exists a strong and negative relation between firm size and financial performance. Consequently, it can be asseverated that the generic recommendation one size fits all cannot be applied in this case; which conforms to the Recommendations of the European Union that dissuade using generic models for all countries.

Etnografía y alimentación entre los Toba-Nachilamole#ek y wichí-Lhuku’tas del Chaco Central (Argentina), Cap. 1, 2 y 3.

Se reproducen tres capítulos relacionados con la ictiología del libro de Pastor Arenas, gracias a su gentileza.

Catéteres venosos centrales de larga duración y sus complicaciones. Reservorio venoso subcutáneo versus catéter central de inserción periférica : revisión bibliográfica.

Introducción: Los catéteres venosos centrales (CVC) de larga duración representan una alternativa para muchos pacientes receptores de tratamientos intravenosos prolongados y agresivos. Dentro de estos, es frecuente el uso de los reservorios venosos subcutáneos (RVS) y de los catéteres centrales de inserción periférica (PICC). En ambos, a pesar de sus numerosas ventajas, pueden surgir complicaciones que comprometan el funcionamiento del dispositivo y provocar la necesidad de retirarlo. Estas, además, pueden poner en peligro el bienestar e incluso la vida del paciente. Objetivos: Analizar las complicaciones asociadas a la implantación y uso de RVS y PICC. Metodología: Se realizó una búsqueda bibliográfica en las bases de datos: Scopus, ScienceDirect, Dialnet plus, ProQuest, OvidSP, SciELO, Cuiden y Elsevier. Resultados: Se seleccionaron seis estudios realizados sobre pacientes portadores de RVS y cinco sobre los PICC. En ellos se analizaron las complicaciones surgidas y los motivos de retirada de los dispositivos por complicaciones asociadas. Conclusiones: Los PICC presentan una morbilidad y una tasa de retirada por complicaciones mayor que los RVS. Las infecciones, obstrucciones y trombosis son las complicaciones con mayor prevalencia en ambos dispositivos junto con las extracciones accidentales en el caso de los PICC. Además, representan los motivos más habituales de retirada del CVC por alguna complicación. Las complicaciones pueden estar influenciadas por distintos factores, entre otros, los cuidados y mantenimiento que se realicen del dispositivo. Idioma: Español.

PICC vs Catéter central insertado en vena subclavia en pacientes críticos

[Es]Introducción: actualmente, en servicios como UCIs, quirófanos y Urgencias cada vez es más común el empleo de CVCS y PICC. Ambos están asociados a graves complicaciones como CLABSI, TVP, EP, arritmia, etc. Dado que la enfermería juega un papel importante tanto en la inserción de estos dispositivos, como en el mantenimiento y prevención de las adversidades, es necesario poseer los conocimientos y habilidades adecuados para su afrontamiento. Objetivo y metodología: determinar cuál de los dos supone menor riesgo de complicaciones en pacientes críticos mediante la evidencia científica y utilizando la EBE. Para ello se ha realizado una revisión bibliográfica de estudios encontrados en bases de datos como Pubmed, Cochrane y Cinhal mediante la combinación de términos MeSH y palabras clave con operadores booleanos. Resultados y discusión: se han incluido en total 13 publicaciones (6 RS, 4 estudios de cohorte, 1 ECA y 2 GPC), de las cuales 3 poseen calidad alta, 3 media y 5 baja. Tanto los PICC como los CVCS implican diversas complicaciones, divididas en infecciosas, trombo-embolicas y mecánicas/otras. Existe insuficiente evidencia científica y gran heterogeneidad entre los artículos, lo que dificulta su extrapolación. Conclusiones: en pacientes críticos los PICC poseen mayor riesgo de TVP, los CVCS de complicaciones mecánicas, y ambos presentan tasas similares de CLABSI. Es importante escoger de forma individualizada el catéter a implantar, estimando los riesgos-beneficios de cada uno. Los cuidados preventivos son fundamentales en la reducción de estas contingencias. Son necesarios más estudios prospectivos comparativos.

Traçadores isotópicos (Pb) e concentrações de metais em sedimentos superficiais: ferramentas na caracterização da poluição no setor oeste da baía de Sepetiba-RJ (SE do Brasil)

Este estudo teve como objetivo principal utilizar os teores de elementos-traço e análise isotópica de Pb (204Pb,206Pb,207Pb,208Pb) como ferramentas na caracterização da poluição da Baía de Sepetiba-RJ. As coletas de sedimento superficiais de fundo foram realizadas em três campanhas, em novembro de 2010, no setor oeste da Baía de Sepetiba RJ. A malha amostral é composta por 66 amostras (BSEP 001 a BSEP 066) coletadas com busca-fundo Van Veen. O pré-processamento das amostras ocorreu no Laboratório Geológico de Preparação de Amostras do Departamento de Geologia da Universidade do Estado do Rio de Janeiro. A digestão parcial das amostras de sedimento (< 0.072 mm) para obtenção do teor parcial dos elementos-traço (Ag, As, Cd, Co, Cr, Cu, Li, Mn, Ni, Pb, Sr, U, Zn) e de isótopo de Pb (lixiviação) foi executada no Laboratório de Geoquímica Analítica do Instituto de Geociências da UNICAMP e a leitura foi executada através do ICP-MS. Já as análises das concentrações totais dos elementos-traço (inclusive, Hg) e de isótopos de Pb (dissolução total) foram realizadas no laboratório ACTLABS (Ontário-Canadá) através do ICP Varian Vista. As leituras isotópicas foram feitas somente nas amostras que apresentaram concentrações parciais de Pb, acima de 0,5 g/g, totalizando 21 estações. Pôde-se constatar a existência de um enriquecimento de elementos-traço no setor oeste da Baía de Sepetiba. As médias dos teores totais de Ag (0,4 g/g), Cd (0,76 g/g), Cu (62,59 g/g), Li (43,29 g/g), Ni (16,65 g/g), Pb (20,08 g/g), Sr (389,64 g/g) e Zn (184,82 g/g) excederam os limites recomendados ou valores naturais. Isto pode ser reflexo da influência antrópica na região, principalmente relacionada à atividade de dragagem e à permanência dos resíduos de minério da desativada companhia de minério Ingá, na Ilha da Madeira. Os mapas de distribuição da concentração dos metais-traço destacaram a presença de vários sítios de deposição ao longo do setor oeste da baía de Sepetiba, com destaque para a região entre a porção centro oeste da Ilha de Itacuruça e o continente; Saco da Marambaia e Ponta da Pombeba; e porção oeste da Ponta da Marambaia. As razões isotópicas 206Pb/207Pb da área estudada variaram entre 1,163 a 1,259 para dissolução total e 1,1749-1,1877 para técnica de lixiviação, valores considerados como assinaturas de sedimentos pós-industriais ou comparados à assinatura de gasolina. Ainda sobre a técnica de lixiviação, destaca-se que os sedimentos superficiais do setor oeste (206Pb/207Pb: 1,1789) da baía de Sepetiba apresentaram uma assinatura uniforme e menos radiogênica do que setor leste (206Pb/207Pb: 1,2373 e 1,2110) desta baía. Através da assinatura isotópica de Pb encontrada nesta região é possível destacar a pouca contribuição das águas oceânicas para esse sistema, entretanto, a circulação interna intensa das águas da baía permite a homogeneização destas. O emprego destes tipos de ferramentas no monitoramento ambiental da área mostrou-se bastante eficiente, sendo importante a continuidade desta abordagem de pesquisa a fim de auxiliar na implementação de um plano de manejo local.

Las competencias docentes del profesor de la Facultad de Filosofía de la Universidad Central del Ecuador y su incidencia en la calidad educativa

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