Transient phenomena such as abrupt changes in wind direction occur frequently during the operation of wind farms. The wakes produced behind wind turbines are affected by these situations, modifying the impact on nearby turbines, both in... more
Transient phenomena such as abrupt changes in wind direction occur frequently during the operation of wind farms. The wakes produced behind wind turbines are affected by these situations, modifying the impact on nearby turbines, both in power output and life expectancy of the blades. In this work, a group of 4 turbines in a wind farm is analysed via Computational Fluid Dynamic (CFD) simulations during wind shifts. Large Eddy Simulations (LES) are carried out by means of the open-source software OpenFOAM, including the SOWFA libraries. Once the wakes reach a time average stationary solution the wind direction is modified by means of a pressure gradient forcing, imposing different change rates. An actuator disk with the ability to correct yaw misalignment is used to represent turbines. Besides, neutral Atmospheric Boundary Layer (ABL) flows are considered. Results show that for higher change rates the greatest impact on the downwind turbine is produced when turbines are no longer collinear with wind direction due to the wake curvature. Also, higher change rates produce a higher curvature modifying the impact on power output of downwind turbines. This study provides a deeper understanding of the cause of greater deficits in wind farm output.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
El siguiente estudio pretende mejorar el proceso de fertilizacion en cafe (coffea arabica L)y medir su impacto economico en la granja San Fernando ubicada en la Mesa de los Santos (Santander - Colombia), a partir de la caracterizacion de... more
El siguiente estudio pretende mejorar el proceso de fertilizacion en cafe (coffea arabica L)y medir su impacto economico en la granja San Fernando ubicada en la Mesa de los Santos (Santander - Colombia), a partir de la caracterizacion de sus lotes, el desarrollo de varios planes de nutricion, y la seleccion y aplicacion del que mas se ajuste a las necesidades, considerando todos los aspectos relacionados con dicha labor como lo son las variables climaticas, las caracteristicas fisicoquimicas del suelo, la edad de las plantaciones, el porcentaje de siembra y sombrio entre otros; con el fin de mejorar las condiciones fitosanitarias y productivas de las plantas de cafe, y a la vez mejorando la rentabilidad de la unidad productiva.
Research Interests: Humanities and Art
El presente trabajo de grado esta orientado a prestar un servicio de ingenieria mediante la solucion de una oportunidad de negocio, teniendo identificado la posibilidad de implementar un proyecto y obtener utilidades. Se trata de... more
El presente trabajo de grado esta orientado a prestar un servicio de ingenieria mediante la solucion de una oportunidad de negocio, teniendo identificado la posibilidad de implementar un proyecto y obtener utilidades. Se trata de describir, con precision, cual es el problema que tiene el cliente y cual es la solucion. Asi mismo se propone una solucion contextualizada, pertinente, que cumpla especificaciones, requerimientos y se enmarque en limitantes, que deje satisfechas las expectativas del cliente. Los proyectos se originan en la necesidad de dar solucion a problemas complejos. Por esto, en la vida profesional, y sobre todo en la ingenieria, el quehacer se ve enfrentado, todos los dias, a tener que resolver problemas. Los problemas no son iguales, es por esto se hace un acercamiento a la Industria del Plastico, mediante la clasificacion de maquinaria para plasticos, con especialidad en Inyectoras.
Research Interests: Philosophy and Humanities
Research Interests:
Research Interests:
Comparative studies designed to investigate the role of glutathione S-transferase (GST) activity on the enzyme catalyzed trapping of aflatoxin B1-8,9-epoxide (AFBO) with glutathione, and the relationship with aflatoxin B1 (AFB1)... more
Comparative studies designed to investigate the role of glutathione S-transferase (GST) activity on the enzyme catalyzed trapping of aflatoxin B1-8,9-epoxide (AFBO) with glutathione, and the relationship with aflatoxin B1 (AFB1) resistance have not been conducted in poultry. Hepatic cytosolic fractions of chickens, quail, turkeys and ducks were used to measure in vitro the enzymatic parameters maximal velocity (Vmax), Michaelis-Menten constant (Km) and intrinsic clearance (CLint) for GST activity. AFB1 used ranged from 2.0 to 157.5 µM and the AFB1-GSH produced was identified and quantitated by HPLC. Significant differences were found in GST Vmax values, being the highest in chickens, followed by quail, ducks and turkeys. The Km values were also significantly different, with chickens < ducks < turkeys < quail. Chickens had the higher CLint value in contrast to ducks. Differences by sex showed that duck females had a higher CLint value than the turkey and quail, whereas duck males had a CLint close to that of turkey. The ratio “AFBO production /AFB1-GSH production” follows the order duck>turkey>quail>chicken, in agreement with the known poultry sensitivity. The extremely high “AFB1 epoxidation activity/ GST activity” ratio observed in ducks might be the explanation for the development of hepatocellular carcinoma in this species.
Research Interests:
Research Interests:
A method was validated for the determination of ochratoxin A (OTA) in soluble and green coffee. Performance parameters evaluated included selectivity, accuracy, intermediate precision, linearity, limit of detection, limit of quantitation,... more
A method was validated for the determination of ochratoxin A (OTA) in soluble and green coffee. Performance parameters evaluated included selectivity, accuracy, intermediate precision, linearity, limit of detection, limit of quantitation, and ruggedness. The method was found to be selective for OTA in both matrices tested. Recovery rates from soluble coffee samples ranged from 73.5 to 91.2%, and from green coffee samples from 68.7 to 84.5%. The intermediate precision (RSDr) was between 9.1 and 9.4% for soluble coffee and between 14.3 and 15.5% for green coffee analysis. The linearity of the standard calibration curve (r(2)) was &lt;0.999 for OTA levels of 1.0-20.0 μg/kg in coffee samples. The limit of detection was determined to be 0.01 ng of OTA on column, while the limit of quantitation was found to be 0.03 ng on column. The limit of quantitation is equivalent to 0.6 μg/kg in soluble coffee samples and 0.3 μg/kg in green coffee samples. The results of the ruggedness trial showed two factors are critical for soluble coffee analysis: the extraction method, and the flow rate of the mobile phase. For green coffee analysis two critical factors detected were the extraction method and the storage temperature of the immunoaffinity column.Five samples of soluble coffee and 42 of green coffee were analysed using the validated method. All soluble coffee samples contained OTA at levels that ranged from 8.4 to 13.9 μg/kg. Six of the 42 green coffee samples analysed (14.3%) contained OTA at levels ranging from 0.9 to 19.4 μg/kg. The validated method can be used to monitor OTA levels in Colombian coffee for export or for local consumption.
Research Interests:
1. The Phase II in vitro metabolism of 3-methylindole (3MI) metabolites was investigated in pigs to determine the possible relationship between 3MI Phase II metabolism and 3MI accumulation in fat. Sulphation and glucuronidation of five of... more
1. The Phase II in vitro metabolism of 3-methylindole (3MI) metabolites was investigated in pigs to determine the possible relationship between 3MI Phase II metabolism and 3MI accumulation in fat. Sulphation and glucuronidation of five of the seven major metabolites found to be produced by porcine microsomes was investigated using porcine cytosol and microsomes, respectively. The possible formation of glutathione conjugates was also investigated using microsomally activated 3MI intermediate(s). 2. No sulphation or glucuronidation was observed for metabolites 3-hydroxy-3-methyloxindole, 3-methyloxindole, indole-3-carbinol or 2-aminoacetophenone; however, 5-hydroxy-3-methylindole (5-OH-3MI) was conjugated with both sulphate and glucuronic acid. 3. The enzyme responsible for sulphation of 5-OH-3MI was identified as the thermostable form of phenol-sulphotransferase (TS-PST) based on its susceptibility to TS-PST inhibitors and the correlation between sulphation of 5-OH-3MI and sulphation of the prototype substrate p-nitrophenol (r = 0.94, p &lt; 0.001). 4. A 3MI-glutathione adduct was identified in microsomal incubations containing 3MI and glutathione. 5. Sulphation of 5-OH-3MI was high in pigs with low levels of 3MI in fat. No relationship was observed between 3MI levels in fat and either glutathione transferase or glucuronidation activities in liver.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
<p class="p1">The art of coffee production under shade has been one of the most effective methods used by our ancestors in order to adapt the coffee trees to precarious conditions, where they would not otherwise produce... more
<p class="p1">The art of coffee production under shade has been one of the most effective methods used by our ancestors in order to adapt the coffee trees to precarious conditions, where they would not otherwise produce profitably due to the conditions of elevation, light, water availability, percentage of organic matter, temperature and other climatic and geographic factors. The objective of this study was to explain in a consistent and clear way the interaction of different effects generated in the soil, atmosphere and the crop, as a result of the use of the shaded coffee technique (<em>sombrío de café</em>) in coffee plantations. This provides tools that are applicable to the Colombian coffee growing industry, which can produce an improvement in the use of this technique, based on the zoning of the productive unit. This will generate an increase in the life and productivity of the crop.</p>
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Remodelacion de la manzana de AZCA. Convocatoria Octubre. Plan 1996. Proyecto fin de carrera. Universidad Politecnica de Madrid. Escuela Tecnica Superior de Arquitectura
Research Interests: Art and Arquitectura
Research Interests:
Profesor Gil. J. Gil (caricatura) Pag.1-2 * Notas Editoriales. Pag.3-4 * Estadistica Quirurgica General del Dr. Gil J. Gil (1907-1932). Pag.5-23 * Gil J. Gil Esquema biografico. Pag.24-27 * Tres Embarazos molares. Pag.28-30 * Variaciones... more
Profesor Gil. J. Gil (caricatura) Pag.1-2 * Notas Editoriales. Pag.3-4 * Estadistica Quirurgica General del Dr. Gil J. Gil (1907-1932). Pag.5-23 * Gil J. Gil Esquema biografico. Pag.24-27 * Tres Embarazos molares. Pag.28-30 * Variaciones Radiologicas del Bulvo Duodenal. Pag.31-34 * Una observacion. Pag.35 * Apuntes de la Pituitrina en la practica obstetricia. Pag.36-39 * Un centenario. Pag.40 * Aspecto cientifico en la educacion infantil. Pag.41-43 * El problema tuberculoso.Pag.44-46 * Cuerno del Pene. Pag.47-48
Research Interests:
Research Interests:
1. The individual and combined effects of T-2 toxin and 4,15-diacetoxyscirpenol (DAS) on laying hens were investigated in an experiment consisting of a 2 x 2 completely randomised factorial design with dietary concentrations of 0 and 2... more
1. The individual and combined effects of T-2 toxin and 4,15-diacetoxyscirpenol (DAS) on laying hens were investigated in an experiment consisting of a 2 x 2 completely randomised factorial design with dietary concentrations of 0 and 2 mg/kg T-2 toxin and 0 and 2 mg/kg DAS. 2. Individually, T-2 toxin and DAS induced oral lesions in half of the hens and decreased significantly egg production and food intake. 3. The effects of T-2 toxin and DAS were additive for reduced food consumption and incidence of oral lesions. However, a synergism for reduced egg production was observed during the last experimental period. 4. No effects on body weight were observed during this study. Mild changes in selected plasma enzymes activities and no change in liver malondialdehyde content were detected. 5. The combination of T-2 toxin and DAS was more toxic than the single mycotoxins, for some parameters, and therefore, may pose a greater economic threat to the poultry industry than either of the toxins individually.
Research Interests:
Research Interests:
Research Interests: Psychology and Humanities
Research Interests: Law and Political Science
El Proyecto de Estación de Transferencia Intermodal de los Andes, se sitúa en los planes de los gobiernos de Argentina y Chile para optimizar los flujos de carga entre los dos países a partir de la reactivación del Ferrocarril Trasandino... more
El Proyecto de Estación de Transferencia Intermodal de los Andes, se sitúa en los planes de los gobiernos de Argentina y Chile para optimizar los flujos de carga entre los dos países a partir de la reactivación del Ferrocarril Trasandino Central (FCTC) en complemento a las carreteras del Corredor Bioceánico Central, aumentando las posibilidades de abrir nuevos mercados del Asia Pacífico para el MERCOSUR y del Atlántico Norte para Chile, evitando los pasos del Canal de Panamá y del Estrecho de Magallanes. Como objetivo General este trabajo pretende llevar a cabo un proyecto de una Estación Intermodal de Transferencia Tren-Camión, que trabaje sólo con carga homologada de contenedores y ferrotage (transporte de camión sobre tren
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Cobalt increases the red cell mass in both man and animals by increasing the production of erythropoietin. Since meat-type chickens can develop pulmonary hypertension from increased erythropoiesis and polycythaemia, two trials were... more
Cobalt increases the red cell mass in both man and animals by increasing the production of erythropoietin. Since meat-type chickens can develop pulmonary hypertension from increased erythropoiesis and polycythaemia, two trials were conducted to investigate the role of cobalt on broiler chicken erythropoiesis and pulmonary hypertension. The results showed that feeding cobaltous chloride at 500 parts/10(6) to meat-type chickens from 1-day-old for 42 days significantly increased haemoglobin content and, to a lesser extent red blood cell count, and haematocrit. No effect was observed on mean corpuscular volume. Increased haemoglobin content was linearly correlated with pulmonary hypertension as measured by the right ventricle weight to total ventricle weight ratio (RV:TV). Levels of malondialdehyde in cardiac tissue were also correlated with the RV:TV ratio, suggesting that peroxidative damage may be related to ventricular hypertrophy. Chickens fed cobalt showed a significantly higher incidence of right ventricular hypertrophy and right ventricular failure and 18.3% developed ascites.
Research Interests: Microbiology, Medicine, Pulmonary Hypertension, Erythropoietin, Internal Medicine, and 12 moreAvian Pathology, Erythropoiesis, Veterinary Sciences, Muscle hypertrophy, Right Ventricle, Broiler, Ascites, Polycythaemia, Broiler Chicken, mean corpuscular volume, right ventricular hypertrophy, and ventricle
1. The individual and combined effects of T-2 toxin and 4,15-diacetoxyscirpenol (DAS) on laying hens were investigated in an experiment consisting of a 2 x 2 completely randomised factorial design with dietary concentrations of 0 and 2... more
1. The individual and combined effects of T-2 toxin and 4,15-diacetoxyscirpenol (DAS) on laying hens were investigated in an experiment consisting of a 2 x 2 completely randomised factorial design with dietary concentrations of 0 and 2 mg/kg T-2 toxin and 0 and 2 mg/kg DAS. 2. Individually, T-2 toxin and DAS induced oral lesions in half of the hens and decreased significantly egg production and food intake. 3. The effects of T-2 toxin and DAS were additive for reduced food consumption and incidence of oral lesions. However, a synergism for reduced egg production was observed during the last experimental period. 4. No effects on body weight were observed during this study. Mild changes in selected plasma enzymes activities and no change in liver malondialdehyde content were detected. 5. The combination of T-2 toxin and DAS was more toxic than the single mycotoxins, for some parameters, and therefore, may pose a greater economic threat to the poultry industry than either of the toxins individually.
Research Interests:
Fumonisins are the most recently discovered group of mycotoxins with important implications in animal health. Equine leucoencephalomalacia and porcine pulmonary edema are diseases observed for many years, but their etiology was unknown.... more
Fumonisins are the most recently discovered group of mycotoxins with important implications in animal health. Equine leucoencephalomalacia and porcine pulmonary edema are diseases observed for many years, but their etiology was unknown. These 2 syndromes were recently reproduced experimentally after administration of purified fumonisin B1 (FB1). The main target organs for the toxic actions of FB1 are the brain in horses and the lungs in the case of swine. However, severe liver damage in both species and pancreatic lesions in swine are also observed, especially when Fusarium moniliforme culture material (FCM) or naturally contaminated corn are used as the source of the fumonisins. Experimentally induced fumonisin toxicosis has been studied in poultry and cattle using FCM or naturally contaminated corn or corn screenings as the mycotoxin source. Results have shown a much lower sensitivity of these species to the toxic action of fumonisins when compared to horses and pigs. However, adverse effects on performance parameters of broiler chickens and turkey poults and on selected immune parameters of chickens and cattle were reported. In order to confirm these observations, toxicological studies using purified fumonisins are required. Studies to determine the interaction of fumonisin with other Fusarium toxins and other mycotoxins are also needed. No studies on the toxicokinetics of fumonisins have been reported. The toxicodynamics (mechanism of action) of fumonisins appears to be a blockage in the synthesis of sphingolipids and thus constitute a unique toxicological action among the known mycotoxins.(ABSTRACT TRUNCATED AT 250 WORDS)
Research Interests:
A study was conducted to establish the occurrence and levels of contamination of aflatoxin M1 (AFM1) in retail milk from Bogotá, Colombia. A total of 241 samples were analysed during 2004 and 2005. Samples were cleaned up by an... more
A study was conducted to establish the occurrence and levels of contamination of aflatoxin M1 (AFM1) in retail milk from Bogotá, Colombia. A total of 241 samples were analysed during 2004 and 2005. Samples were cleaned up by an immunoaffinity column and AFM1 was quantified by liquid chromatography with fluorescence detection. A total of 69.2 and 79.4% of the samples analysed during 2004 and 2005, respectively, were found to contain levels of AFM1 above 10 ng l. Levels of contamination ranged from 10.7 to 213.0 ng l in 2004, and from 10.6 to 288.9 ng l in 2005. Despite the high incidence of AFM1 found in the milk samples analysed, all samples complied with current local regulations, which allow AFM1 content in milk up to 400 ng l. However, due to the high incidence of AFM1 in milk found in the present study, it is recommended that a permanent surveillance programme be established for milk consumed in Bogotá in order to prevent milk lots containing levels above the regulatory level entering the food chain.