Saltar navegación e ir al contenido principal
Biblioteca digital de Bogotá
Logo BibloRed
Cargando contenido
¿Qué estás buscando?
  • Escribe palabras clave como el título de un contenido, un autor o un tema que te interese.

  • Búsqueda avanzada

Seleccionar

Contenidos y Experiencias Digitales

Filtrar

Formatos de Contenido
Tipo de colección
Género
Idioma
Derechos de uso

Selecciona contenidos según las condiciones legales para su uso y distribución.

Estás filtrando por

Cargando contenido

Se encontraron 8967 resultados en recursos

Imagen de apoyo de  Urban Residual Space in Latin America: Reframing the Role of Public Space in Colombia

Urban Residual Space in Latin America: Reframing the Role of Public Space in Colombia

Por: Luz Mery Rodelo Torres | Fecha: 2020

Abstract: The metropolises of the global south are often considered out of rules as a distinct urban “species” while cities of the global north are commonly recognized for their development, organization, and operation. The duality that arises in Latin American cities is between the advancement of its infrastructure and the provision of goods and services. This duality is physically manifested in urban space, as well as the increase of spatial segregation and social inequality. Fragments, patches, archipelagos, and countless denominations that narrow the “disorder” of these cities contrast with the good practices they develop to increase the quality of life of their inhabitants. Life in public space is one of the interrelationships that occur in cities, but in some spaces in Latin American cities are considered fragments and uncertain spaces of the city without defined uses due to the characteristics of some of these spaces. These spaces, specifically in Colombian cities, commonly divide the large areas of poverty with the few areas of wealth, providing greater inequality and socio-spatial segregation. Considering Latin America as the most violent and inequitable region in the world explains why the research of recent decades in these cities has focused on understanding the causes and finding answers to minimize poverty, and inequality. These phenomena will not find the full answers in architecture nor urbanism; however, actions from these two disciplines are required to materialize opportunities for all the cities. Thus, the purpose of the research, based on literature review, methodological terms, and collection of information is reframing the role of public space as a potential for articulation with the deficit of public space and as a tool of urban development.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

Urban Residual Space in Latin America: Reframing the Role of Public Space in Colombia

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  Physician’s Allocation Preferences under Scarcity and Uncertainty

Physician’s Allocation Preferences under Scarcity and Uncertainty

Por: Amalia; Atehortua Rodríguez Valencia | Fecha: 2021

Abstract: Physicians are no strangers to situations where they have to decide with resource restrictions and uncertainty on the relative needs of future beneficiaries of the scarce resources. We propose a lab experiment to understand if such an environment affects physicians' resource allocation decisions and how. When there are incentives to overtreat, we find that a patient tended by a constrained physician under uncertainty obtains higher benefits and receives allocations closer to her optimum than patients from physicians with no constraints or deciding under uncertainty alone. In addition, we observe a redistribution of resources when physicians decide with resource restrictions and uncertainty. In particular, when resources are scarce, physicians tend to allocate the limited services to patients with higher benefits in the absence of medical services, a higher capacity to benefit from the resources, the scantiest need for service units, and the lowest benefits at the optimum. Finally, we find that constraints, with or without complete information on patient characteristics, lead selfish physicians to approximate what is best for the patient. Resumen: Los médicos no son ajenos a situaciones en las que tienen que decidir bajo escasez de recursos e incertidumbre sobre las necesidades relativas de los futuros beneficiarios de servicios de salud. Proponemos un experimento de laboratorio para entender sí, y cómo, este entorno afecta a las decisiones de asignación de recursos de los médicos. Cuando hay incentivos para la sobre provisión de servicios médicos, encontramos que los pacientes atendidos por médicos que enfrenta restricciones e incertidumbre obtienen mayores beneficios en salud y reciben servicios de salud más cercanos a su óptimo, en comparación con los pacientes vistos por médicos sin restricciones o que deciden sólo bajo incertidumbre. Además, observamos una redistribución de recursos cuando los médicos deciden bajo restricciones e incertidumbre. En particular, cuando los recursos son escasos, los médicos tienden a asignar servicios de salud a los pacientes con mayores beneficios en ausencia de servicios médicos, con mayor capacidad para beneficiarse de servicios adicionales, con menores necesidades de tratamiento médico y con menores beneficios en el óptimo. Por último, encontramos que las restricciones, con o sin información completa sobre las características del paciente, llevan a los médicos egoístas a aproximarse a lo que es mejor para el paciente.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros
  • Economía

Compartir este contenido

Physician’s Allocation Preferences under Scarcity and Uncertainty

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  Venereal Transmission of Vesicular Stomatitis Virus by Culicoides sonorensis Midges = Transmisión venérea del virus de la estomatitis vesicular por los jejenes Culicoides
sonorensis

Venereal Transmission of Vesicular Stomatitis Virus by Culicoides sonorensis Midges = Transmisión venérea del virus de la estomatitis vesicular por los jejenes Culicoides sonorensis

Por: Paula Camila; Londoño-Renteria Rozo López | Fecha: 2020

Abstract: Culicoides sonorensis biting midges are well-known agricultural pests and transmission vectors of arboviruses such as vesicular stomatitis virus (VSV). The epidemiology of VSV is complex and encompasses a broad range of vertebrate hosts, multiple routes of transmission, and diverse vector species. In temperate regions, viruses can overwinter in the absence of infected animals through unknown mechanisms, to reoccur the next year. Non-conventional routes for VSV vector transmission may help explain viral maintenance in midge populations during inter-epidemic periods and times of adverse conditions for bite transmission. In this study, we examined whether VSV could be transmitted venereally between male and female midges. Our results showed that VSV-infected females could venereally transmit virus to uninfected naïve males at a rate as high as 76.3% (RT-qPCR), 31.6% (virus isolation) during the third gonotrophic cycle. Additionally, VSV-infected males could venereally transmit virus to uninfected naïve females at a rate as high as 76.6% (RTqPCR), 49.2% (virus isolation). Immunofluorescent staining of micro-dissected reproductive organs, immunochemical staining of midge histological sections, examination of internal reproductive organ morphology, and observations of mating behaviors were used to determine relevant anatomical sites for virus location and to hypothesize the potential mechanism for VSV transmission in C. sonorensis midges through copulation. Resumen: Los Culicoides son plagas agrícolas bien conocidas y vectores de transmisión de arbovirus como el virus de la estomatitis vesicular (VSV). La epidemiología de VSV es compleja y abarca una amplia gama de hospedadores vertebrados, múltiples rutas de transmisión y diversas especies de vectores. En las regiones templadas, los virus pueden invernar en ausencia de animales infectados a través de mecanismos desconocidos, para volver a ocurrir el próximo año. Las rutas no convencionales para la transmisión del VSV pueden ayudar a explicar el mantenimiento viral en las poblaciones de vectores durante los períodos interepidémicos y los momentos de condiciones adversas para la transmisión por picadura. En este estudio, examinamos si VSV podría transmitirse de forma venérea entre Culicoides machos y hembras. Nuestros resultados mostraron que las hembras infectadas con VSV podían transmitir el virus de forma venérea a machos no infectados a una tasas tan altas como 76,3% (RT-qPCR) o 31,6% (aislamiento del virus) durante el tercer ciclo gonotrófico. Además, los machos infectados con VSV podrían transmitir el virus a hembras no infectadas a tasas entre 76,6% (RT-qPCR) y 49,2% (aislamiento del virus). Adicionalmente se utilizaron tinción inmunofluorescente de órganos reproductores micro-disecados, tinción inmunoquímica de secciones histológicas de Culicoides para examinar la morfología de órganos reproductores y se hicieron observaciones de los comportamientos de apareamiento para determinar los sitios anatómicos relevantes para la ubicación del virus y para formular hipótesis sobre el mecanismo potencial de transmisión del VSV en C. sonorensis a través de la cópula.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

Venereal Transmission of Vesicular Stomatitis Virus by Culicoides sonorensis Midges = Transmisión venérea del virus de la estomatitis vesicular por los jejenes Culicoides sonorensis

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  The First Painted Image of America in Europe: A Detail from Pinturicchio’s Resurrection in the Sala dei Misteri

The First Painted Image of America in Europe: A Detail from Pinturicchio’s Resurrection in the Sala dei Misteri

Por: Andrés Hernando Rubiano Velandia | Fecha: 2021

Abstract: The article analyses the Resurrection of Christ, a fresco commissioned from Pinturicchio by Pope Alexander VI in 1492 as part of his project to renovate the Borgia Apartments in the Vatican. The analysis focuses on a detail of the painting: the figures of what seems to be a group of indigenous warriors located at the centre of the fresco. The main purpose of the paper is to identify the iconographic meaning and sources of this particular image. The central claim is that Pinturicchio used specific scenes from Christopher Columbus’s Diario to create, biased by a misconception of the New World, the first painted image of America in Europe.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

The First Painted Image of America in Europe: A Detail from Pinturicchio’s Resurrection in the Sala dei Misteri

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  ¿Quiénes son los anglohablantes nonativos? Un Análisis Crítico del Discurso de libros de texto ELT de distribución global

¿Quiénes son los anglohablantes nonativos? Un Análisis Crítico del Discurso de libros de texto ELT de distribución global

Por: Zulma Xiomara; Atienza Cerezo Rueda García | Fecha: 2020

Abstract: As the demand for English language skills among non-native speakers globally has grown steadily so too has the number of ‘global textbooks’ for ELT aimed at a world market. Concurrently, critical perspectives of the expansion of English have begun to challenge the view that native speaker contexts ‘own’ English. Based on the aforementioned, and on reflective approaches to culture, our objective is to analyze critically the representations of speakers of English as a second or foreign language offered by two global ELT textbooks, to discuss the issues of essentialization and reproduction of stereotypes about the “nonnative” speakers of English and their sociocultural characteristics in the constructed image. To achieve this purpose, we apply a methodology based on a sociocognitive approach to Critical Discourse Analysis (CDA) (Van Dijk, 2013), the concept of sociocultural knowledge as stated by the Common European Framework of Reference for Languages (CEFR), and critical perspectives of culture according to Holliday, Kullman, and Hyde (2004). Our findings indicate that, though the books include ‘non-native’ speakers in an attempt to address multiculturalism, their representation is generic, portraying a reified image of their sociocultural traits and presenting diversity mostly through national labels.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

¿Quiénes son los anglohablantes nonativos? Un Análisis Crítico del Discurso de libros de texto ELT de distribución global

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  First tracking of declining Caspian terns Hydroprogne caspia breeding in the Baltic Sea reveals high migratory dispersion and disjunct annual ranges as obstacles to effective  conservation

First tracking of declining Caspian terns Hydroprogne caspia breeding in the Baltic Sea reveals high migratory dispersion and disjunct annual ranges as obstacles to effective conservation

Por: Cristina; Lötberg Rueda Uribe | Fecha: 2021

Abstract: The conservation of migratory species poses significant challenges that may be countered by detailed knowledge about the sites used by migrants throughout the annual cycle. We present the rst GPS-tracking data on the migration of declining Caspian terns Hydroprogne caspia breeding in the Baltic Sea. For 39 Caspian terns from colonies along a latitudinal gradient from 57 to 65°N, we identified key migratory routes, stopovers and wintering areas. In autumn these seabirds migrated using coastal and freshwater stopovers along six routes to reach their wintering areas across the Sahel, the Nile River Basin and the southern Iberian Peninsula. In spring, adults returned to the breeding grounds in the Baltic using a time optimizing strategy by reducing time at stopover by 78%, whereas most subadults remained sedentary and some performed only partial return migrations. Of the stopover sites used in both seasons, 58% are protected and have a reported management plan. Conservation strategies in wintering areas, stopover sites that are not protected or had not been previously recognized, and the inclusion of the species in important migratory yways across Europe and Africa will be important to prevent further population declines of a species that depends on aquatic habitats.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

First tracking of declining Caspian terns Hydroprogne caspia breeding in the Baltic Sea reveals high migratory dispersion and disjunct annual ranges as obstacles to effective conservation

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  Interplay of Fluorescence and Phosphorescence in Organic Biluminescent Emitters

Interplay of Fluorescence and Phosphorescence in Organic Biluminescent Emitters

Por: Caterin Yojana; Kleine Salas Redondo | Fecha: 2017

Abstract: Biluminescent organic emitters show simultaneous fluorescence and phosphorescence at room temperature. So far, the optimization of the room-temperature phosphorescence in these materials has drawn the attention of research. However, the continuous-wave operation of these emitters will consequently turn them into systems with vastly imbalanced singlet and triplet populations, which is due to the respective excited-state lifetimes. This study reports on the exciton dynamics of the biluminophore NPB (N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1-biphenyl)-4,4-diamine). In the extreme case, the singlet and triplet exciton lifetimes stretch from 3 ns to 300 ms, respectively. Through sample engineering and oxygen quenching experiments, the triplet exciton density can be controlled over several orders of magnitude, allowing us to study exciton interactions between singlet and triplet manifolds. The results show that singlet−triplet annihilation reduces the overall biluminescence efficiency already at moderate excitation levels. Additionally, the presented system represents an illustrative role model to study excitonic effects in organic materials.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

Interplay of Fluorescence and Phosphorescence in Organic Biluminescent Emitters

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  Simultaneous fluorescence and phosphorescence from organic molecules

Simultaneous fluorescence and phosphorescence from organic molecules

Por: Caterin Yojana; Reineke Salas Redondo | Fecha: 2015

Diluting organic molecules in a polymer matrix material suppresses non-radiative behavior, leading to biluminescence, wherein light is emitted efficiently from both singlet and triplet states. In summary, biluminescence has developed into a thoroughly optimized and unique emissive system. Among the characteristics obtained through this system, the most significant is the ability of biluminophores to offer direct access to the radiative states of both spin manifolds (singlets and triplets) in organic molecules without the requirement for special or complex material combinations. As a result, an exciton is given the chance to re-emit its energy, regardless of its initial state. In future work, we intend to increase the toolset of organic biluminophores by screening materials to determine the structure-property relationships behind persistent phosphorescence, and to identify molecular building blocks that are suitable for the development of future materials. In addition, we will intensify our exploration of biluminescence for future applications (e.g., sensing).
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

Simultaneous fluorescence and phosphorescence from organic molecules

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  Life cycle assessment of perovskite on silicon tandem PV modules at industrial scale

Life cycle assessment of perovskite on silicon tandem PV modules at industrial scale

Por: Caterin Yojana; Blanco Salas Redondo | Fecha: 2020

Abstract: For the first time a comprehensive life cycle assessment (LCA) is reported of a large-area perovskite/Si tandem photovoltaic (PV) module of about 2 m², with an assumed power conversion efficiency of 30%, 30 years lifetime and an annual degradation of 0.5%, manufactured in a 1 GW production plant. By means of the LCA method, we calculate the contribution to the International Reference Life Cycle Data System (ILCD) impact categories associated with a perovskite/Si tandem PV system compared with a passivated emitter and rear cell (PERC) used as reference. We consider a functional unit of 1 kWh of generated direct current electrical energy from the tandem module over its lifetime. It was found that the most significant environmental hotspots are the silicon wafer production and the balance of system (BOS), especially the mounting system, inverter and electric installation. Overall, the impact contributions to the environment caused by the perovskite sub-module are below 1% throughout all the ILCD categories in focus: climate change, freshwater ecotoxicity, water resource depletion and human toxicity. Even the contribution of lead to human toxicity is just about 0.01%. For all the impacts assessed, the perovskite/Si tandem shows a decrease of between 17-20% of the contributions to each impact category compared to the PERC-module based reference PV system, if the Si bottom sub-module has an initial cell efficiency of at least 22% with 1% cell-to-module (CTM) loss, and the perovskite top sub-module has a minimum initial cell efficiency of 18% with at most 5% CTM loss and a transmittance near IR region larger than 80%. The key result found in this work is the relevance of the performance and reliability of the PV system to achieve lower environmental impacts. A comparison between optimistic, realistic, and pessimistic scenarios was performed to investigate this matter: in the worst-case scenario, the environmental impact of the PV tandem system would have a general 50% increase throughout all ILCD impact categories against the realistic case, whereas in the optimistic one, the results suggest a reduction of 46% to the global impact contributions, compared to the realistic scenario.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

Life cycle assessment of perovskite on silicon tandem PV modules at industrial scale

Copia el enlace o compártelo en redes sociales

Imagen de apoyo de  Transistores basados en nanotubos de carbono

Transistores basados en nanotubos de carbono

Por: Caterin Yojana; Villa Ramírez Salas Redondo | Fecha: 2009

Resumen: Las aplicaciones de la electrónica exigen mayor eficiencia de los dispositivos electrónicos que se utilizan hoy en día. Entre los aspectos mas importantes esta el área ocupada por un circuito: Se busca que los dispositivos electrónicos ocupen el menor espacio posible. La tecnología que se utiliza hoy en día para fabricar dispositivos semiconductores está llegando a un punto limite, donde cada vez es mas difícil obtener reducción en el tamaño sin afectar otras características del dispositivo. La nanoelectrónica está evolucionando a un punto donde se hace posible la construcción de dispositivos semiconductores que presenten mejores características que los fabricados en la actualidad. Este documento muestra una revisión bibliográfica sobre nanotecnología, con el fin de presentar una propuesta de investigación para implementar transistores basados en nanotubos de carbono. Este trabajo está en su fase inicial, se espera que a finales del 2009 se tenga una metodología de implementación de transistores utilizando nanotecnología.
Fuente: Biblioteca Virtual Banco de la República Formatos de contenido: Artículos
  • Temas:
  • Otros

Compartir este contenido

Transistores basados en nanotubos de carbono

Copia el enlace o compártelo en redes sociales

Selecciona las Colecciones en las que vas a añadir el contenido

Para consultar los contenidos añadidos busca la opción Tus colecciones en el menú principal o en Mi perfil.

Mis colecciones

Cargando colecciones

¿Deseas limpiar los términos de la búsqueda avanzada?

Vas a limpiar los términos que has aplicado hasta el momento para poder rehacer tu búsqueda.

Selecciona las Colecciones en las que vas a añadir el contenido

Para consultar los contenidos añadidos busca la opción Tus colecciones en el menú principal o en Mi perfil.

Mis colecciones

Cargando colecciones