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Imagen de apoyo de  Approximal caries: Prevalence and progression rate in Young Danish adults and an innovative non-operative approach for lesions around the EDJ

Approximal caries: Prevalence and progression rate in Young Danish adults and an innovative non-operative approach for lesions around the EDJ

Por: Stefania Martignon | Fecha: 01/01/2005

A literature review disclosed that even under very strict caries preventive control, in young Swedish people many initial approximal lesions slowly progress. A study was performed to investigate if the same trend could be seen in young Danish adults. In 1996 a group of Danish military conscripts were investigated clinically and radiographically. Based on the radiographs, one lesion with radiolucency up to one third in the dentine was randomly selected from each conscript.Contact was established with these former conscripts in 2002 and radiographs taken around 2002 were used to investigate the state of the selected lesions in terms of regression, stabilization or progression. It was observed that about 60% of the selected lesions had progressed during the 5 to 6 year period. Therefore there was a need to look for other preventive measures than those traditionally used in a Danish context, such as instructions in flossing and local application of fluoride. Looking through the literature, it was realized that sealing of occlusal lesions was highly effective but this procedure was not used on approximal surfaces.The next step was to investigate if it was technically possible to seal approximal lesions and if so what material should be used. A laboratory study was conducted in which 6 dental materials were compared in relation to: their handling, presence at the surface of the lesion, and ability to penetrate into a lesion. Based on that study Gluma One Bond® (Heraeus Kulzer) was selected to be used in further studies. The final step was an 18-month clinical investigation to evaluate the effect of sealing approximal lesions. About 80 young adults from Denmark and Colombia participated in this investigation; each had at least 2 initial approximal lesions.One lesion was selected for sealing; the other one acted as control. Baseline radiographs were taken by means of special equipment so new radiographs could be taken in the same position after 18 months. The sealing procedure was performed in accordance with the guideline designed in the laboratory study. The patient was instructed to floss all sealed and non-sealed approximal lesions. Radiographs were used to assess caries progression in the test and control lesions in three ways: by comparing baseline with final scoring of the lesions on the individual conventional radiographs, by reading the conventional radiographs as pairs and finally using subtraction radiography of digitized images.The examiner was blind to lesion type (test or control) for all comparisons and also blind to whether radiographs were baseline or follow up in the case of examinations of the single radiographs and paired comparison. Repeat assessment of the radiographs was conducted on 20% of the radiographs and the subtraction images. For the paired comparison of radiographs and subtraction radiography assessment significantly more control lesions progressed (47.2%; 85%) than test lesions (22.2%; 43%) (P-values<0.05). For the independent examination of the radiographs a similar pattern was seen but the difference between the two groups was not statistically significant (P=0.06).In conclusion, many approximal lesions seemed to progress on young adults irrespective of the preventive regime they were advised to take. This study has developed and investigated a technique for sealing early approximal lesions which seems to be more effective at preventing lesion progression than conventional interventions such as brushing and flossing. There is a need however, for defining more precisely criteria at selecting lesions to be sealed; for developing better materials in terms of better penetration skill and that they stay there, and for clinical investigations which evaluate the long term effect of sealing the approximal lesions.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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  • Medicina

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Approximal caries: Prevalence and progression rate in Young Danish adults and an innovative non-operative approach for lesions around the EDJ

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Imagen de apoyo de  Public Policy and the new regulatory framework on Electronic Government Procurement in Colombia = Política Pública y nuevo marco regulatorio sobre contratación pública electrónica en Colombia

Public Policy and the new regulatory framework on Electronic Government Procurement in Colombia = Política Pública y nuevo marco regulatorio sobre contratación pública electrónica en Colombia

Por: Roberto Laguado Giraldo | Fecha: 01/01/2005

La contratación pública es la actividad a través de la cual grandes cantidades de recursos públicos son utilizados por entidades de esa misma naturaleza para comprar y adquirir bienes y servicios del sector privado. Cuando a esta actividad se le incorpora el uso de tecnologías de la información y la comunicación se genera el concepto de contratación publica electrónica, en inglés e-government procurement que a su vez tiene como sigla eGP. El presente documento describe el proceso de elaboración de política pública y regulación en material de eGP en Colombia.Subraya que sólo hasta hoy en día el sistema de contratación publica colombiano logró incorporar los dos pilares que la CNUDMI ha propuesto como bases legales para el eGP: 1. Reglas sobre publicación de información sobre procesos de contratación y, 2. Reglas sobre Equivalencia Funcional de documentos electrónicos expedidos con ocasión de la actividad contractual. Por Equivalencia funcional se debe entender el principio según el cual los documentos electrónicos reciben la misma validez y fuerza vinculante que los documentos expedidos en sopote papel.Esta investigación enfatiza que antes del 8 de julio de 2005, la regulación de Contratación Publica electrónica carecía del pilar de equivalencia funcional y que tal circunstancia hacia nugatoria la posibilidad de usar Tecnologías de Información en las labores de la Administración Publica. El documento explica cómo gracias a la expedición de la Ley 962 de 2005, el pilar faltante de equivalencia funcional fue establecido, ya que esta norma incorporó este principio para el general funcionamiento de la administración y sus procedimientos administrativos. Antes de exponer sus conclusiones, el autor sugiere su propia interpretación de la Ley 962/2005.Las fuentes que han servido de insumos para la elaboración del documento han sido documentos oficiales del gobierno colombiano así como regulación local, igualmente, legislación y reportes de organizaciones internaciones, libros y artículos en la materia. Este documento llega a la conclusión de que con la Ley 962/2005 las interpretaciones que existían en materia de contratación pública electrónica deben cambiarse al punto de que se acepte el uso de TI para el efecto de generar eGP en Colombia.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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Public Policy and the new regulatory framework on Electronic Government Procurement in Colombia = Política Pública y nuevo marco regulatorio sobre contratación pública electrónica en Colombia

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Imagen de apoyo de  When titles do not become loans: property rights and slums upgrading in Bogota, Colombia

When titles do not become loans: property rights and slums upgrading in Bogota, Colombia

Por: Alexander Niño Ruiz | Fecha: 01/01/2006

Contrary to the conventional orthodoxy of the World Bank, lack of formalized or secured property rights is not the main reason why titles do not become loans in Colombia. My research shows that the institutional barriers that prevent poor people from leveraging their assets are rooted in the Colombian constitution, and in the lack of private financial institutions willing to lend to the poor. Low and middle income populations cannot use their houses as collateral to obtain loans aimed to finance business because the Colombian constitution mandates families to secure a share of their assets as Family Wealth. As a result, families have to protect their estate from being impounded by lenders. When the law allows the use of the house as collateral— for financing the purchase, improvement or enlargement of housing — there are few formal financial institutions lending to the poor. Despite of the importance of this for land-titling programs, it passed unnoticed by the World Bank, who approved a US$100 million loan for the Bogotá Urban Service Project in 2003. This thesis reveals the assumptions made by the Bank regarding the importance of property formalization as a mechanism to create massive equity out of the improved real estate in the informal sector. It contrasts the Bank’s assumptions with the actual process of upgrading in Bogotá. Leveraging poor people’s assets would be critical to the well-functioning of upgrading program, but these policies should rely on a mechanism other than the willingness of formal institutions to lend to the poor.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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When titles do not become loans: property rights and slums upgrading in Bogota, Colombia

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Imagen de apoyo de  La estrategia crush con futuros de ganado: oportunidades de trading para productores = The cattle crush strategy: trading opportunities for cattle producers

La estrategia crush con futuros de ganado: oportunidades de trading para productores = The cattle crush strategy: trading opportunities for cattle producers

Por: Nicolás Acevedo Vélez | Fecha: 01/01/2006

Resumen:En este estudio se muestra que es posible para un productor de ganado de carne en EE.UU obtener utilidades adicionales cuando estrategias de operación en el mercado financiero de futuros de Chicago son utilizadas (i.e. la estrategia “cattle crush”). No obstante, los costos de transacción presentes reduce la probabilidad de obtener utilidades mediante la estrategia de análisis técnico. También se muestra que el nivel de ganancia derivado del uso del “cattle crush” está relacionado con el ciclo ganadero en el cual se realice la operación. Cuando el “cattle crush” se utiliza como alternativa para cubrir riesgo, se reduce considerablemente la volatilidad de los retornos de la operación.Este trabajo utiliza precios diarios desde 1995 a 2006 de los contratos a futuro de maíz, ganado flaco y ganado gordo con el fin de tener una muestra suficientemente robusta que permita elaborar conclusiones significativas. El “cattle crush” se construyó utilizado dos diferentes combinaciones de ciclo productivo de ganado (ambos de 170 días), pero que comienzan en fechas distintas: abril y octubre. Adicionalmente, dos escenarios fueron analizados usando el “cattle crush” diferencial: uno en el cual esta estrategia fue usada como estrategia de cobertura antes del inicio de las operaciones (estrategia especulativa) y, el otro, en el cual la estrategia de cobertura se llevó a cabo una vez se inició la actividad productiva.Abstract:This research shows that it is possible for U.S. cattle feeders to obtain additional profits if a consistent technical strategy for trading is applied to the cattle crush spread. However, when trading costs are introduced, the likelihood of obtaining profit from trading the crush reduces considerably. It also shows that the level of gains from the cattle crush is related to the month the cattle are marketed. When the crush is used as a hedging strategy it decreases the profit from the feeding operation and reduces the volatility of those returns, helping producers to transfer part of the price risk associated with their production.To provide evidence of these findings, this study utilizes daily prices for 1995 to 2006 of the futures contracts of corn, feeder and live cattle to construct the daily cattle crush spread for two different combinations of futures contracts traded in the Chicago Board of Trade and Chicago Mercantile Exchange. These contract combinations suppose that cattle are fed in feedlots for 170 days before being marketed in April and in October. Two different scenarios are also evaluated using the cattle crush spread: one in which the crush is employed as a pre-placement hedging tool and another in which the crush is used as a post-placement hedging method.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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La estrategia crush con futuros de ganado: oportunidades de trading para productores = The cattle crush strategy: trading opportunities for cattle producers

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Imagen de apoyo de  Twin Cities in Amazonian Transnational Borders, an Appropriate Cross Border Approach for Squatter Settlements on flood prone lands located on border’s fringe: The Case Study of Leticia and Tabatinga

Twin Cities in Amazonian Transnational Borders, an Appropriate Cross Border Approach for Squatter Settlements on flood prone lands located on border’s fringe: The Case Study of Leticia and Tabatinga

Por: Erik Vergel Tovar | Fecha: 01/01/2006

The thesis focuses the topic of squatter settlements located along borders in twin cities on the Amazon context. The study claims that Twin Cities are integrated by informality, in this case by squatter settlements along borders. In addition to the integration, these squatter settlements are transforming the border from a limit towards a social spatial construction of their territory. Based on that, the study looks for a cross border approach which can be developed by local governments of twin cities in order to manage squatter settlements along borders as a shared and common problem. In order to develop the research, the study has been done in the case of Leticia (Colombia) and Tabatinga (Brazil) twin cities in the Amazon. The thesis is focused in a natural space which has been the border between these twin cities the San Antonio ravine. Along this “natural” limit between Colombia and Brazil has been taken place an occupation of squatter settlements that has transformed the international limit into an “informal” urban space.The thesis developed two approaches in order to study the mentioned case of squatter settlements located along borders in twin cities. First, the study developed a bottom up approach analysing socioeconomic and physical characteristics of squatter settlements inhabitants and comparing both squatter settlements based on fieldwork findings. The comparative study looks for symmetric and asymmetric issues between both squatter settlements which are a key output towards a cross border approach between the twin cities based on needs and characteristics of squatter settlements inhabitants in the Amazon context. On the other hand, the study developed a review of urban policies of Colombia and Brazil looking for aspects that can be taking into account for local government of Leticia and Tabatinga in their local policies for managing squatter settlements on flood prone lands located on the border’s fringe.In addition, the study made a review of the current frontiers policies of both countries in order to find key elements that can used by local government for developing a cross border cooperation for managing squatter settlements in a cooperation and integration framework.Finally, the study looks for a short and long term appropriate approach for managing these two squatter settlements located along the border between the Leticia and Tabatinga twin cities. The recommendations for both terms can be useful input for future housing policies, and urban planning and management instruments in the twin cities based on Amazon characteristics. Moreover, the research methodology developed in the study can be an appropriate research procedure for further urban studies in Leticia and Tabatinga twin cities, especially on squatter settlements along border’s fringe.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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Twin Cities in Amazonian Transnational Borders, an Appropriate Cross Border Approach for Squatter Settlements on flood prone lands located on border’s fringe: The Case Study of Leticia and Tabatinga

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Imagen de apoyo de  Valuing children at school: Case Study of two primary school classrooms in a West London school = Valorando a los niños en el colegio: estudio de caso en dos salones de clase de una escuela primaria en Londres

Valuing children at school: Case Study of two primary school classrooms in a West London school = Valorando a los niños en el colegio: estudio de caso en dos salones de clase de una escuela primaria en Londres

Por: Luz Adriana Chávez Villegas | Fecha: 01/01/2006

The study will be based on an anthropological view of learning in which the central idea is to find out how people become to be who they are. On that account, it will be interested in the social influences of the environment people are settled in, as well as the individual’s agency in their process of making sense of their experience. The discovery of the common practices individuals execute at a particular setting –as it is the school- will be one of the aims of this study that is to contribute to the revelation of the social relations structured within the community. Studying deeper these social relations structured in practice (Lave & Wegner, 1991) and in the material dispositions, will bring us to an understanding of how people are valued in the specific situations inside a particular society.On that account, I am concerned with the idea of what it means to be a child and how children come, in particular contexts, like educational institutions, to be valued in historically specific ways. Taking two primary school classrooms in a West London school as my case study, I analyse how value is created as the outcome of socially structured processes of interaction between teachers and children and between children themselves. Comparing and contrasting the teachers’ ideas of what makes children valued at school, I describe how the structuring influence exerted by the teachers in the classroom infringe on the formation of friendship relations among the children. 
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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Valuing children at school: Case Study of two primary school classrooms in a West London school = Valorando a los niños en el colegio: estudio de caso en dos salones de clase de una escuela primaria en Londres

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Imagen de apoyo de  Impact of the pump systems availability in the plant maintenance: model development

Impact of the pump systems availability in the plant maintenance: model development

Por: Juan José Hernández Bello | Fecha: 01/01/2006

The present work aims to describe and analyse the influence of the reliability and maintainability of the pump systems on the overall plant availability. The study was developed into an aliphatic solvent plant situated in Colombia and owned by the state company Ecopetrol S.A. This plant is composed of six pump systems, each one of them with parallel redundancy, working in series. The first step during the process was the identification of the dominant failure modes for these pump systems according to historical maintenance information collected during the last nine years and recorded in the CMMS of the company.For these dominant failure modes a Weibull analysis was carried out in order to determine the main parameters of the failure probability distribution function and, in this way, to build a mathematical model useful for predictions of future failures. Additionally, a maintainability model was developed based on the current repair process capability of the work shop employed by the company.By employing reliability block diagrams the reliability dependencies between components, items, units, and systems were taking into account. A general model for the whole plant unit was built and several simulations were performed using Monte Carlo techniques. The simulation results were helpful to identify the more sensitive elements for the overall plant availability and suggest some maintenance and operational actions in order to reduce plant downtime and maintenance costs.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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Impact of the pump systems availability in the plant maintenance: model development

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Imagen de apoyo de  La philosophie tragique chez Clément Rosset. Un regard sur le réel / La filosofía trágica en Clément Rosset. Una mirada sobre lo real

La philosophie tragique chez Clément Rosset. Un regard sur le réel / La filosofía trágica en Clément Rosset. Una mirada sobre lo real

Por: Olga Del Pilar López Betancur | Fecha: 01/01/2007

La philosophie tragique a eu comme lieu de naissance la pensée nietzschéenne. L’intention de Nietzsche fut d’extraire le terme du tragique du contexte du théâtre pour construire avec lui une réflexion au service de la vie. Notre intention dans cet ouvrage est de comprendre comment la pensée de Rosset suit celle de Nietzsche et à quel moment elle s’éloigne pour écrire sa propre version de la philosophie tragique. Sur ce point nous tentons de répondre : quel est l’apport de Rosset à la lignée de la philosophie tragique? Ou bien quel est l’avantage de suivre une philosophie tragique sans tomber dans la simplicité de l’optimisme? On peut voir que ces questions lient complètement la philosophie et l’éthique et invitent à échapper au sens amer et fataliste qu’habituellement on concède au terme du tragique pour l’ouvrir à la célébration la vie. Enfin, on insiste sur la question : Rosset est-il vraiment un continuateur de Nietzsche et parvient-il à resémantiser le terme de philosophie tragique pour l’enrichir et l’amplifier, pour le singulariser avec sa propre réflexion? La filosofía trágica tuvo como lugar de nacimiento el pensamiento nietzscheano. La intención de Nietzsche fue extraer el término trágico del contexto del teatro para construir con él un pensamiento al servicio de la vida. Nuestra intención en esta obra es comprender como la reflexión de Rosset sigue a esa de Nietzsche y en qué momento ella se aleja para escribir su propia versión de la filosofía trágica. Sobre ese punto, nosotros intentamos responder: ¿cuál es el aporte de Clément Rosset a la línea de la filosofía trágica? O bien ¿cuál es la ventaja de seguir una filosofía trágica sin caer en la simplicidad del optimismo? Se puede ver que estas preguntas ligan completamente la filosofía a la ética e invitan a escapar al sentido amargo y fatalista que habitualmente uno concede al término trágico, para más bien abrirlo a la celebración de la vida. En fin, se insiste sobre la pregunta: ¿Es Rosset verdaderamente un continuador de Nietzsche y logra él resemantizar el término de filosofía trágica para enriquecerlo y ampliarlo, para singularizarlo con su propio pensamiento?
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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La philosophie tragique chez Clément Rosset. Un regard sur le réel / La filosofía trágica en Clément Rosset. Una mirada sobre lo real

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Imagen de apoyo de  The Nature of Science: What to teach and how to teach it. Basic Principles for Curriculum Development

The Nature of Science: What to teach and how to teach it. Basic Principles for Curriculum Development

Por: Alicia del Pilar Medina Salazar | Fecha: 01/01/2007

One of the principal goals of science education is that students develop an understanding of the nature of science (NOS), which is considered to be a key element in the achievement of scientific literacy. The capacity to learn, know and use science and technology to cope with the challenges of everyday life has become a commonly desired outcome of science education. Through the teaching of the NOS it is believed that our children will become better citizens, more conscious of their role within their community and environment. Ultimately, the goal is to safeguard our world for future generations. (Martin et al., 2000; W. F. McComas & Olson, 1998).How to properly and accurately address the NOS teaching in classroom practice has been the subject of diverse and intense debates (Bell, Abd-El-Khalick, Lederman, McComas, & Matthews, 2001). The disputes revolve around different aspects of NOS teaching and learning and each brings various issues into play. Educators need a more practical way of thinking about NOS when developing their curriculums. In my thesis work I provide a survey of the contemporary debates about the NOS and science education improvement. After reviewing the literature, I developed a set of curriculum design principles that I call the Basic Principles for Curriculum Development (BPCD).These, I propose, should be taken into account when developing science curricula that effectively addresses primary NOS principles. I want to emphasize that rather than pretending to use these curricular principles as the ultimate tool for science instruction, the BPCD should be used in combination with other curriculum development ideas and pedagogical strategies.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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Imagen de apoyo de  Fields of deformation: tracing critical boundaries in architectural practice = Campos de deformación: trazando márgenes críticos en la práctica de la arquitectura

Fields of deformation: tracing critical boundaries in architectural practice = Campos de deformación: trazando márgenes críticos en la práctica de la arquitectura

Por: Lina Fawcett V. | Fecha: 01/01/2007

If architecture has succeeded the natural impulse of evolution and demonstrated its everchanging creative power, urbanism has challenged its operationality by revealing a logic that surpasses any established concepts within the field. New urbanisms today are understood by weakening public life, changing the nature of the streets and modifying the human scale. Furthermore, the emergent post-urban life appears unmanageable due to conditions never diagnosed before: edge cities, peripheries, nodality and disarticulation seem problematic to conceptualize.What is it about the challenge of architecture capable to deploy a logic that drives urban design with a certain direction? Architecture can expand its potential design approaches through the investigation of its own rationality in order to find new sources that intersect emerging urban landscapes. The façade performs as a critical surface that articulates urban affects and provides a positive understanding of the street-grid as a persistent and flexible planning instrument along time. If the plan is not sufficient anymore, by securing its spatial hierarchies the building skin becomes significant to a contemporary discussion where architecture gains an instrument to overcome the difference.The dialogue amongst architectural design process is not reducible to a fixed set of values but to opening up its own disciplinary boundaries. It intends to rethink these borders in new terms utilizing few notions and examples that have proven as techniques of formal stability within architecture, as opposed to the diffuse and complex transformational processes of the city. Paradoxically, it is inside architecture where non-static surfaces of composition open the field to creative processes, since they are by nature given to experimentation.
Fuente: Biblioteca Virtual Banco de la República Tipo de contenido: Tesis
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Fields of deformation: tracing critical boundaries in architectural practice = Campos de deformación: trazando márgenes críticos en la práctica de la arquitectura

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