421 research outputs found

    Exportación de sedimentos desde cuencas hidrográficas de la vertiente oriental del golfo de Urabá: influencias climáticas y antrópicas

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    En este artículo se analizaron series de tiempo mensuales de precipitación (mm), caudal (m3/s) y exportación de sedimentos (kton/día) en cuencas de la vertienteoriental del golfo de Urabá. Se analizó la dinámica de la exportación de sedimentos, la relación caudal - exportación y caudal - precipitación. Se infirió el papel de fenómenos atmosféricos estacionales y multianuales (El Niño - Oscilación Sureña, ENOS),y factores antrópicos. Se encontraron variabilidades intra - anuales significativas (ANOVA: p<0.001) consistentes con las oscilaciones de la Zona de Convergencia Intertropical. Correlaciones de Pearson mostraron relaciones directas y significativas (p<0.001). El ENOS no presentó influencia sobre la precipitación. Con aerofotografías se analizó el efecto antrópico en los municipios de Apartadó (1961 - 2005) y Chigorodó (1961 - 2007), y se encontró pérdida de cobertura boscosa del 90%. Las figuras de doble masa reflejaron, al cambiar la pendiente positivamente, a mediados de los 90, que la tasa de exportación de sedimentos fue mayor por metro cúbico de caudal, sugiriendo que hay un efecto antrópico

    Educational inequality trends in mortality due to pneumonia in Colombia, 1998-2015

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    We aimed to explore the existence and trends of social inequalities related to pneumonia mortality in Colombian adults using education as a proxy of socioeconomic status. We obtained death certificates due to pneumonia and population data from Departamento Administrativo Nacional de Estadística for 1998-2015. Educational level data were gathered from microdata of the Colombian Demography Health Surveys. Annual trends in Age Standardized Mortality Rates by sex and educational level were quantified by calculating the Estimated Annual Percentage Change (EAPC). We estimated Rate Ratios (RR) by using Poisson regressionmodels, comparing mortality of educational groups with mortality in the highest education group. We estimated the Relative Index of Inequality (RII) to assess changes in disparities, regressing mortality on the mid-point of the cumulative distribution of education, thereby considering the size of each educational group. All analyses were conducted in SAS®V.9.2. For adults 25+ years, the risk of dying was significantly higher among lower educated. The RRs depict increased risks of dying comparing lower and highest education level, and this tendency was stronger in woman than in men [RRprimary=2.34 (2.32-2.36), RRsecondary=1.77 (1.75-1.78) vs. RRprimary=1.83(1.81-1.85), RR secondary=1.51 (1.50-1.53)]. According to age groups, young adults (25-44 years) showed the largest inequality in terms of educational level; RRs for pneumonia mortality regarding to the tertiary educated groups show increased mortality in the lower and secondary educated, and these differences decreased with ages. RII in pneumonia mortality among adult men was 2.01 (95%CI 2.00-2.03) and in women 2.46 (95%CI 2.43-2.48). The RII was greatest at young ages, for both sexes. Time trends showed steadily significant increases for RII in both men and women (EAPCmen=3.8; EAPCwomen=2.6). Pneumonia mortality rates in adults evidenced a clear age-dependency, with lowest rates for young and much higher rates for senior adults. All estimated mortality rates were higher in men than in women

    Verificación de identidad en la educación virtual mediante análisis biométrico basado en la dinámica del tecleo

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    Virtual education has become one of the tools most widely used by students at all educational levels, not just because of its convenience and flexibility, but also because it can expand educational coverage. All these benefits also bring along multiple issues in terms of security and reliability in the evaluation the of student’s knowledge because traditional identity verification strategies, such as the combination of username and password, do not guarantee that the student enrolled in the course really takes the exam. Therefore, a system with a different type of verification strategy should be designed to differentiate valid users from impostors. This study proposes a new verification system based on distances computed among Gaussian Mixture Models created with different writing task. The proposed approach is evaluated in two different modalities namely intrusive verification and non-intrusive verification. The intrusive mode provides a false positive rate of around 16 %, while the non-intrusive mode provides a false positive rate of 12 % In addition, the proposed strategy for non-intrusive verification is compared to a work previously reported in the literature and the results show that our approach reduces the equal error rate in about 24.3 %. The implemented strategy does not need additional hardware; only the computer keyboard is required to complete the user verification, which makes the system attractive, flexible, and practical for virtual education platforms.La educación virtual se ha convertido en una de las herramientas más utilizadas por los estudiantes en todos los niveles educativos, no solo por la comodidad y la flexibilidad, sino también por la posibilidad de ampliar la cobertura educativa en una población. Todos estos beneficios traen consigo múltiples problemas de seguridad y confiabilidad a la hora de evaluar el proceso de aprendizaje del estudiante, ya que las estrategias tradicionales de verificación de identidad, como la combinación de nombre de usuario y contraseña, no garantizan que el estudiante matriculado en el curso realmente realice el examen. Por lo tanto, es necesario diseñar un sistema con otro tipo de estrategia de verificación para diferenciar un usuario válido de un impostor. Este estudio propone un nuevo método de verificación, basado en el cálculo de distancias entre los modelos de mezclas gaussianas creados con diferentes tareas de escritura. El enfoque propuesto es evaluado en dos modalidades diferentes llamadas verificación intrusiva y verificación no intrusiva. El modo intrusivo proporciona una tasa de falsos positivos de 16 %, mientras el modo no intrusivo provee una tasa de falsos positivos de 12 %. Además, la estrategia propuesta para verificación no intrusiva es comparada con un trabajo previamente reportado en la literatura y los resultados muestran que nuestro enfoque reduce la tasa de error en aproximadamente un 24.3 %. La estrategia implementada no necesita hardware adicional, solo es requerido el teclado del computador para realizar la verificación, lo que hace que el sistema sea atractivo y flexible para ser usado en plataformas de educación virtual

    INFLUENCE OF ENVIRONMENTAL FACTORS IN THE ATMOSPHERIC CORROSION OF COPPER IN THE PRESENCE OF PROPIONIC ACID

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    Exportación de sedimentos desde cuencas hidrográficas de la vertiente oriental del golfo de Urabá: influencias climáticas y antrópicas

    Get PDF
    En este artículo se analizaron series de tiempo mensuales de precipitación (mm), caudal (m3/s) y exportación de sedimentos (kton/día) en cuencas de la vertienteoriental del golfo de Urabá. Se analizó la dinámica de la exportación de sedimentos, la relación caudal - exportación y caudal - precipitación. Se infirió el papel de fenómenos atmosféricos estacionales y multianuales (El Niño - Oscilación Sureña, ENOS),y factores antrópicos. Se encontraron variabilidades intra - anuales significativas (ANOVA: p<0.001) consistentes con las oscilaciones de la Zona de Convergencia Intertropical. Correlaciones de Pearson mostraron relaciones directas y significativas (p<0.001). El ENOS no presentó influencia sobre la precipitación. Con aerofotografías se analizó el efecto antrópico en los municipios de Apartadó (1961 - 2005) y Chigorodó (1961 - 2007), y se encontró pérdida de cobertura boscosa del 90%. Las figuras de doble masa reflejaron, al cambiar la pendiente positivamente, a mediados de los 90, que la tasa de exportación de sedimentos fue mayor por metro cúbico de caudal, sugiriendo que hay un efecto antrópico

    Eco-Sustainable housing development for vulnerable population

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    El trabajo consiste en el montaje de un módulo habitacional ecosostenible para sectores vulnerables (en el caso de este proyecto: Fundación “Kyrios”, centro de restauración), fabricado en plástico y tetrapack reciclado, proveniente de residuos en procesos de empaque de diferentes empresas; con instalación de sistemas ecoeficientes (panel fotovoltaico, y colector solar) para suplir demandas energéticas eléctrica y térmica respectivamente. Se realizan pruebas de resistencia mecánica, conductividad térmica, acústica y permeabilidad del material de construcción que garantizan las condiciones de habitabilidad adecuadas. Abstract The project consists of the installation of an environmentally sustainable housing module (In this project, for the “Kyrios” Foundation, Rehabilitation Center): the module was built with waste plastic materials discarded from industrial packaging processes. Different sustainable systems were installed (photovoltaic system, solar collector) to satisfy electricity and thermal energy demands. In order to satisfy the conditions of housing, different tests were performed on the construction material such as mechanical resistance, thermal and acoustic conductivity and permeability

    Coastal subsidence increases vulnerability to sea level rise over twenty first century in Cartagena, Caribbean Colombia

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    Cartagena is subsiding at a higher rate compared to that of global climate-driven sea level rise. We investigate the relative sea level rise (RSLR) and the influence of vertical land movements in Cartagena through the integration of different datasets, including tide gauge records, GPS geodetic subsidence data, and Interferometric Synthetic Aperture Radar (InSAR) observations of vertical motions. Results reveal a long-term rate (\u3e 60 years) of RSLR of 5.98 ± 0.01 mm/yr. The last two decades exhibited an even greater rate of RSLR of 7.02 ± 0.06 mm/yr. GPS subsidence rates range between − 5.71 ± 2.18 and − 2.85 ± 0.84 mm/yr. InSAR data for the 2014–2020 period show cumulative subsidence rates of up to 72.3 mm. We find that geologically induced vertical motions represent 41% of the observed changes in RSLR and that subsidence poses a major threat to Cartagena’s preservation. The geodetic subsidence rates found would imply a further additional RSLR of 83 mm by 2050 and 225 mm by 2100. The Colombian government should plan for the future and serve as an example to similar cities across the Caribbean

    Coastal subsidence increases vulnerability to sea level rise over twenty first century in Cartagena, Caribbean Colombia

    Get PDF
    Cartagena is subsiding at a higher rate compared to that of global climate-driven sea level rise. We investigate the relative sea level rise (RSLR) and the influence of vertical land movements in Cartagena through the integration of different datasets, including tide gauge records, GPS geodetic subsidence data, and Interferometric Synthetic Aperture Radar (InSAR) observations of vertical motions. Results reveal a long-term rate (\u3e 60 years) of RSLR of 5.98 ± 0.01 mm/yr. The last two decades exhibited an even greater rate of RSLR of 7.02 ± 0.06 mm/yr. GPS subsidence rates range between − 5.71 ± 2.18 and − 2.85 ± 0.84 mm/yr. InSAR data for the 2014–2020 period show cumulative subsidence rates of up to 72.3 mm. We find that geologically induced vertical motions represent 41% of the observed changes in RSLR and that subsidence poses a major threat to Cartagena’s preservation. The geodetic subsidence rates found would imply a further additional RSLR of 83 mm by 2050 and 225 mm by 2100. The Colombian government should plan for the future and serve as an example to similar cities across the Caribbean
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