225 research outputs found

    La regulación económica de la distribución de energía eléctrica

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    La distribución eléctrica, en particular, es una de las actividades enmarcadas en el proceso de regulación en Colombia. Su intervención está justificada por los efectos sobre el bienestar social6 que genera su condición de monopolio natural, avalado en la existencia de economías de escala, economías de alcance, subaditividad de costos y barreras de entrada

    Density functional study of the magnetic properties of Bi4Mn clusters: Discrepancy between theory and experiment

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    We have performed collinear and noncollinear calculations on neutral Bi4Mn and collinear ones on ionized Bi4Mn with charges +1 and −1 to find out why theoretical calculations will not predict the magnetic state found in the experiment. We have used the density functional theory to find a fit between the theoretical prediction of the magnetic moment and the experimental value. Our calculations have consisted in a structural search of local energy minima, and the lowest energy magnetic state for each resulting isomer. The geometry optimization found three local minima whose fundamental state is the doublet spin state. These isomers could not be found in previous theoretical works, but they are higher in energy than the lowest-lying isomer by ≈1.75 eV. This magnetic state could help understand the experiment. Calculations of noncollinear magnetic states for the Bi4Mn do not lower the total magnetic moment. We conclude arguing how the three isomers with doublet state could actually be the ones measured in the experimentThis research has been done under the Projects No. MAT2009-08165 and No. INCITE08PXIB236052PR. One of the authors has been enjoying financial support from the Isabel Barreto programS

    Bone remodeling: A tissue-level process emerging from cell-level molecular algorithms

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    <div><p>The human skeleton undergoes constant remodeling throughout the lifetime. Processes occurring on microscopic and molecular scales degrade bone and replace it with new, fully functional tissue. Multiple bone remodeling events occur simultaneously, continuously and independently throughout the body, so that the entire skeleton is completely renewed about every ten years.Bone remodeling is performed by groups of cells called Bone Multicellular Units (BMU). BMUs consist of different cell types, some specialized in the resorption of old bone, others encharged with producing new bone to replace the former. These processes are tightly regulated so that the amount of new bone produced is in perfect equilibrium with that of old bone removed, thus maintaining bone microscopic structure.To date, many regulatory molecules involved in bone remodeling have been identified, but the precise mechanism of BMU operation remains to be fully elucidated. Given the complexity of the signaling pathways already known, one may question whether such complexity is an inherent requirement of the process or whether some subset of the multiple constituents could fulfill the essential role, leaving functional redundancy to serve an alternative safety role. We propose in this work a minimal model of BMU function that involves a limited number of signals able to account for fully functional BMU operation. Our main assumptions were i) at any given time, any cell within a BMU can select only one among a limited choice of decisions, i.e. divide, die, migrate or differentiate, ii) this decision is irreversibly determined by depletion of an appropriate internal inhibitor and iii) the dynamics of any such inhibitor are coupled to that of specific external mediators, such as hormones, cytokines, growth factors. It was thus shown that efficient BMU operation manifests as an emergent process, which results from the individual and collective decisions taken by cells within the BMU unit in the absence of any external planning.</p></div

    The minorities and minoritised cinematographies in the European cultural policy: the Danish alternative

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    El artículo expone la necesidad de acometer el modo en que la Unión Europea viene planteando su modelo de desarrollo cultural en la última década y de cara a un futuro próximo. Partiendo del análisis de los modelos culturales de masas imperantes en las democracias posmodernas, proponemos que las formas de cultura disidentes (minoritarias o minorizadas), precisamente por su condición refractaria al modelo estandarizado de cultura generado por la actual lógica político-económica comunitaria, constituyen una garantía para la posibilidad misma, tras la modernidad, de otra cultura en Europa. En este sentido, hemos ejemplarizado en la producción audiovisual danesa una alternativa a la errática política cultural de la Unión Europea: aunque procedente de un pequeño territorio y soportada por una lengua de implantación geográfica reducida, evidencia una significativa producción fílmica de calidad, cuyas señas inequívocas de identidad la erigen en hecho cultural reconocible e irrenunciable. En contraposición, se analizan algunos de los aspectos más ilustrativos del Plan Europa Creativa, cuyo carácter refractario a la diversidad cultural como modelo denunciamos abiertamente: entre otros, desaparecen los propósitos de planes anteriores con respecto a la VO y el multilingüismo, las pequeñas cinematografías dejan de ser interlocutoras válidas desde el punto de vista comunitario, etc.The purpose of this document is to analyze the European Union's approach to its cultural development model during the last decade and towards the future. Based on the analysis of mass cultural models, which dominate the post-modern democracies, we suggest that the dissident forms of culture (minorities or minoritised), precisely for their refractory condition towards the cultural standardized model and generated by the current political and economic logic, constitute a guarantee for the possibility, after modernity, of a different European culture. In this regard, we have exemplified an alternative to the European Union’s erratic cultural policy in the Danish audiovisual production: in spite of the modest dimension of its territory, supported by a national language with a limited geographic location, the facts show a high quality cinematographic production whose unmistakable hallmarks proclaim it as a recognizable cultural and undeniable fact. In contrast with the Danish case, some of the most significant European Digital Agenda issues are discussed and openly reported: among others, the disappearance of precedents purpose in relation to promote OV and multilingualism and the fact that the small cinemas are no longer interlocutors in policy-making from the Community's point of view

    Análisis de la configuración estratégica de las empresas del sector logístico portuario de la ciudad de Cartagena /

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    La globalización de la economía ha permitido un gran avance del comercio internacional durante las últimas décadas, ya que esta actividad brinda los servicios de distribución, canalización y venta de los bienes productivos en un país. En Colombia luego de la apertura económica y la firma de los distintos tratados de libre comercio, han surgido las condiciones necesarias para expandir la oferta de productos y la llegada de empresas extranjeras; estos factores a su vez han permitido que el ritmo de crecimiento comercial sea muy significativo para la economía nacional. Dentro de esta dinámica de integración comercial la actividad portuaria ha jugado un papel trascendental para integrar de manera competitiva estos elementos en la economía, es decir, la logística portuaria es una herramienta poderosa para aumentar los flujos de comercio entre economías, lo cual repercute directamente en la productividad, competitividad y desarrollo económico de los países. Según la CEPAL, en América Latina y el Caribe el volumen de carga movilizada en 2015, fue de 54 millones de Teus (Tráfico Marítimo de Contenedores), de las cuales, la participación de Colombia fue muy importante, con un total de 198 millones toneladas. Ahora bien, de este total, más del 90% del tráfico de carga se realizó en las zonas portuarias de la Región Caribe, con mayor participación el puerto de Ciénega (24,2%), el del Morrosquillo (23,2%), y el de Cartagena (19,0%) (ANDI, 2016).Incluye referencias bibliográficas (páginas 104-109

    Effects of applied pressure in ZnV2 O4 and evidences for a dimerized structure

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    The series of V spinels [A2+] V2 O4 (A = Cd, Mn, Zn, Mg) provides an opportunity to tune the V-V distance continuously, in the frustrated pyrochlore lattice of the spinel. This system has been shown to approach the metallic state when V-V distance is reduced. The proximity to the transition leads to a dimerized structure in ZnV2 O4 caused by lattice instabilities. A different manner to tune the V − V distance of this structure is to fix the A2+ cation (in our case, Zn) and apply pressure. We have analyzed the evolution of the electronic structure of the system in the dimerized state. Such structure prevents the system to present a metallic phase at moderate pressures. We have also calculated the transport properties in a semiclassical approach based on Boltzmann transport theory. Our results support the validity of this structural distortion by providing a nice fit with experimental measurementsThe authors thank the CESGA (Centro de Supercomputacion de Galicia) for the computing facilities and the Ministerio de Educación y Ciencia (MEC) for the financial support through the project MAT2009-08165. A.S.B. thanks MEC for an FPU grant. J.B. and M.P. acknowledge Deputación da Coruña and the Isabel Barreto program respectively for financial support. We are also thankful to the Xunta de Galicia for financial support through the project INCITE08PXIB236052PRS

    Graphic art, Philosophy and Bilingualism as a result of research at the Faculty of Fine Arts and Humanities

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    This book Graphic art, Philosophy and Bilingualism as a result of research at the Faculty of Fine Arts and Humanities is a bet that the school of fine arts and humanities has established in order to consolidate a scenario where the research studies from the faculty are shared. This initiative started two years ago, with the creation of the event of socialization of research studies conducted by the members of the programs. This space appeared with the necessity of knowing what all the disciplines are building, and the results have been potentially published in the sense of a book with different chapters. Each chapter reports the studies that have presented in each event, which has three publications currently. In this occasion, the book is written in English as an opportunity to spread research groups production widely. This edition includes three chapters from bilingualism, philosophy and visual arts disciplines. The first chapter seeks to report a research study based on a teaching implementation in two state schools in Pereira, Colombia. This intervention has been proposed by the use of bilingual pedagogies that are part of dynamic bilingual education such translanguaging, CLIL, among others. The study reports the results of the teaching practices and the impact in students bilingual process.CONTENIDO Prologue....................................................................................................................5 CHAPTER ONE On the Implementation of a Dynamic Bilingual Education Model in Pereira, Colombia / Sobre la Implementación de un Modelo Dinámico de Educación Bilingüe en Pereira, Colombia ..................................................................................9 CHAPTER TWO Pedagogical implications of relativism in Protagoras.............................................35 CHAPTER THREE 720 Graphic Memory / 720 Memoria Gráfica ..............................................................................................5

    Capacidad de innovación de proceso y desempeño innovador: efecto mediador de la capacidad de innovación de producto

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    Although in recent years, investment and the use of resources in R&amp;D by the private sector has increased, the number of innovative companies per se has dropped dramatically in Colombia. However, the studies that have been carried out to analyze this paradox, have only demonstrated the limited positive effects of process innovation capability (IC) on innovation performance (IP). Therefore, the aim of this paper is to determine the mediating effect of product IC on the relationship between process IC and IP, based on a sample of manufacturing firms. Structural equation modeling was used with the method of least squares and a bootstrap-percentile analysis was performed to check the existence of mediation. The results showed that there is a partial mediation. Therefore, the development of IC products is necessary in order to reflect process improvements in the products and to exploit them commercially, thus invigorating the performance.Pese a que en los últimos años ha crecido la inversión y la ejecución de recursos en I+D+i por parte del sector privado, el número de empresas que innova en sentido estricto se ha reducido considerablemente en Colombia. Sin embargo, los estudios que se han realizado en torno a esta paradoja, solo han logrado evidenciar las limitaciones del efecto positivo de la capacidad de innovación (CI) de proceso sobre el desempeño innovador (DI). Por ende, el objetivo del artículo es establecer el efecto mediador de la CI de producto en la relación entre CI de proceso y DI, en una muestra de empresas manufactureras. En cuanto a la metodología, se utilizaron ecuaciones estructurales por el método de mínimos cuadrados y se realizó el análisis bootstrap-percentil para corroborar la existencia de la mediación. En relación con los resultados, se encontró que existe una mediación parcial. Por lo tanto, el desarrollo de CI de productos es necesario para que las mejoras en los procesos se vean reflejadas en los productos y puedan ser explotadas comercialmente, de este modo se dinamizaría el DI

    Capacidad de innovación de proceso y desempeño innovador: efecto mediador de la capacidad de innovación de producto

    Get PDF
    Although in recent years, investment and the use of resources in R&D by the private sector has increased, the number of innovative companies per se has dropped dramatically in Colombia. However, the studies that have been carried out to analyze this paradox, have only demonstrated the limited positive effects of process innovation capability (IC) on innovation performance (IP). Therefore, the aim of this paper is to determine the mediating effect of product IC on the relationship between process IC and IP, based on a sample of manufacturing firms. Structural equation modeling was used with the method of least squares and a bootstrap-percentile analysis was performed to check the existence of mediation. The results showed that there is a partial mediation. Therefore, the development of IC products is necessary in order to reflect process improvements in the products and to exploit them commercially, thus invigorating the performancePese a que en los últimos años ha crecido la inversión y la ejecución de recursos en I+D+i por parte del sector privado, el número de empresas que innova en sentido estricto se ha reducido considerablemente en Colombia. Sin embargo, los estudios que se han realizado en torno a esta paradoja, solo han logrado evidenciar las limitaciones del efecto positivo de la capacidad de innovación (CI) de proceso sobre el desempeño innovador (DI). Por ende, el objetivo del artículo es establecer el efecto mediador de la CI de producto en la relación entre CI de proceso y DI, en una muestra de empresas manufactureras. En cuanto a la metodología, se utilizaron ecuaciones estructurales por el método de mínimos cuadrados y se realizó el análisis bootstrap-percentil para corroborar la existencia de la mediación. En relación con los resultados, se encontró que existe una mediación parcial. Por lo tanto, el desarrollo de CI de productos es necesario para que las mejoras en los procesos se vean reflejadas en los productos y puedan ser explotadas comercialmente, de este modo se dinamizaría el DI

    IMPLEMENTACIÓN EN FPGA DE UN CLASIFICADOR DE MOVIMIENTOS DE LA MANO USANDO SEÑALES EMG

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    Este trabajo presenta el diseño e implementación de un clasificador de señales electromiográficas (EMG) para tres movimientos de la mano: flexión, extensión y cierre, usando dos músculos del antebrazo, palmar largo y extensor común de los dedos. El desarrollo comprende dos bloques principales, el hardware para la adquisición y adecuación de la señales EMG analógicas y el sistema de procesamiento para la identificación y clasificación del movimiento realizado; el sistema completo fue implementado en hardware usando un kit de desarrollo DE2-70 que cuenta con un FPGA Cyclone II de Altera. Para la extracción de características se implementó la Transformada Rápida de Fourier (FFT), para cada canal, a la cual se le calcularon  técnicas de procesamiento  como la varianza y el promedio.. Finalmente, se establece un umbral de decisión para identificar el movimiento realizado. El tiempo de respuesta del sistema total fue de 17,7 us, obteniendo una tasa de identificación mayor al 87%.FPGA implementation of a hand motions classifier using EMG signalsAbstractThis paper presents the design and implementation of a hand motions classifier using electromyographic (EMG) signals. The classified motions are: wrist flexion, wrist extension and hand closure. The motions are classified using two forearm muscles: longus palmar and extensor digitorum. This work was implemented in two principal blocks: the acquisition and adequacy of the EMG signal, and the processing system for the identification and classification of the motion made. The processing system was implemented on hardware using a development kit with a Cyclone II FPGA from Altera. For the feature extraction the Fast Fourier Transform (FFT) is performed at each channel and some features like variance and mean are calculated. Finally, a threshold decision block is used to identify the motion. The system have a time response of 17,7 us, obtaining an identification rate higher than 87%.Keywords: EMG signals, FPGA, motion classifier, real time
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