948 research outputs found
Genetic Variants of Duffy and Hemoglobin S Genes in an Afrodescendent Population from Columbia
Malaria is an endemic disease in a large part of Colombia, and the city of Buenaventura reports one of the highest malaria infection rates. Some genetic variants confer resistance to malaria, such as the heterozygote for hemoglobin S (HbS) and the homozygous variant FYBES/FYBES of the Duffy gene. The aim of this work was the molecular characterization of these genes in an afrodescendent population from the urban area of Buenaventura. A total of 819 individuals from a stratified random sampling in each of the 12 communities of this city were analysed. Molecular analysis was performed using PCR-RFLP, and data analysis was performed using the Arlequin 3.5, SPSS 20 and R 3.4.1 programs. Frequencies of 3.1% and 72.2% were obtained for the S and FYBES alleles, respectively, and the values were 6.1% and 55% to AS and FYBES/FYBES genotypes respectively. The highest proportion of these resistance genotype (genotypic combination AA*FYBES/FYBES) were showed for the group of 13 to 27 years with (8.2%) and the communities 1 and 3 (18% and 10.3%, respectively). Therefore, it would be pertinent to consider these communities and age groups when performing epidemiological studies and preventive and health care campaigns on malaria in the urban areas of the city of Buenaventura
Estudio retrospectivo sobre el comportamiento reproductivo utilizando inseminación artificial vs monta natural en dos fincas ganaderas del pacifico de Nicaragua, 2015 -2016
El presente trabajo fue realizado en la finca La Estrella, ubicada en el municipio de
Tisma, departamento de Masaya y en la finca El Pilar, ubicada en Villa El Carmen
municipio de Managua, ambas fincas ganaderas semi intensivas de la región del
pacÃfico de Nicaragua. El objetivo general fue evaluar la eficiencia reproductiva de la
inseminación artificial (IA) vs monta natural (MN), mediante el comportamiento de los
principales Ãndices reproductivos en dos fincas ganaderas semi intensivas de la región
del pacifico de Nicaragua, las variables evaluadas fueron intervalo parto concepción
(IPC), intervalo parto-parto (IPP) y tasa de preñez (TP) encontrándose los siguientes
resultados: en la finca La Estrella se obtuvo un IPC promedio de 122 dÃas y en la finca
El Pilar se obtuvo un promedio de 341 dÃas para los años 2015-2016, el promedio del
IPP en la finca la estrella fue de 396.5 dÃas y en la finca El Pilar de 613 dÃas, la tasa de
preñez en la finca La Estrella fue de 75% y 60% en la finca El Pilar, de tal forma que
al comparar los Ãndices reproductivos, resultó con mayor eficiencia la finca La Estrella
utilizando monta natural. La finca El Pilar al parecer fue más afectada por los la sequÃa
y por la falta de manejo adecuado de los animales, ambiente y personal técnico
Modelo de Dos Zonas para lechos fijos con información asistida por CFD
En este trabajo se presenta un modelo matemático para la representación de la transferencia de calor en lechos Fjos denominado Modelo de Dos Zonas, en el cual se divide al lecho en una zona adyacente a la pared del tubo y una zona central. Se desarrolla una metodologÃa para la determinación apropiada de los parámetros propios del modelo mediante la utilización de ±luidodinámica Computacional. En esta etapa del estudio se determina el ²ujo de calor sobre la pared de tubo, con el Fn de obtener uno de los parámetros del modelo: el coeFciente de transferencia de calor sobre la pared. Poseriormente, se correlacionará con las condiciones geométricas y operativas del lecho. La C±D reemplaza, de esta forma, a la realización de experiencias especÃFcas y se utiliza como herramienta para la generación de información de alta precisión.Se analiza el caso de un sólido de baja conductividad, lo que corresponde por analogÃa al caso de transferencia de materia equivalente y se utilizan condiciones operativas correspondientes al proceso de reformado de gas natural con vapor de agua. El software utilizado es el programa ±luent 6.2.16 (Computational ±luid Dynamics Software) y la malla para el cálculo se genera mediante el programa Gambit 2.2.30. Se presentan resultados obtenidos para lechos rellenos con partÃculas esféricas y se comparan los resultados obtenidos con información existente en bibliografÃa.A Two-Zone Mathematical model for heat transfer in Fxed beds (Two Zones Model) is proposed in this work. According to the model, the bed is divided in two zones: the Frst region -adjacent to the wall- plays an important role in the heat transfer process and the second one -the bulk zone- allows the heat to be transported from and to the center of the tube. An appropriate methodology for the estimation of the model parameters, based on the application of Computational ±luid-Dynamics, is developed here.SpeciFcally, the total heat ²ux at the tube wall is calculated with the aim of evaluating the heat transfer coefFcient at the wall, hw. This coefFcient could be later correlated with geometrical and operating conditions in the bed. The C±D technique used, in this way, replaces well the information based on experimental work, and constitutes a useful tool for obtaining precise information dealing with the bed behavior.In this work, the case of low-conductivity solid particles, which is strictly the analogous case of mass transfer process, is dealt with. Operation conditions of steam reforming of natural gas were adopted in calculations. The software used for C±D is ±luent 6.2.16 (Computational ±luid Dynamics Software) assisted in the mesh generation by the use of the software Gambit 2.2.30.Results obtained for spherical particle beds are presented and compared with previous contributions reported in the literature.Fil: Zambon, Mariana Teresa. Universidad Nacional del Comahue. Facultad de IngenierÃa. Departamento de QuÃmica; ArgentinaFil: Barreto, Guillermo Fernando. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Mazza, German Delfor. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de IngenierÃa. Departamento de QuÃmica; Argentin
In vitro Behavior of Enterotoxigenic Escherichia coli in Increasing Copper Concentrations.
Cupric sulfate is widely used as growth promoter for swine productions, in spite of its ecological risks. The aim of this paper was to study the in vitro behavior of Enterotoxigenic Escherichia coli in increasing concentrations of copper. To achieve that, two reference strains: A-1 (O149: K91: K88ac) and E68-I (O141: K85: K88ab), were used with other four strains isolated from herds with colibacillosis. The reference strains were grown in Mueller-Hinton agar, according to the concentration gradient technique with weekly increasing values, from 5 to 50 mg/mL of CuSO4. The experiment lasted three weeks. Though in the initial contacts two wild strains were the best adapted, at the end all developed high tolerance to the metal. For A-1, it may be determined by the formation of biofilm, which, apart from the said resistance, is an important factor of virulence in infectious bacterial processes. The results observed are another element to add to the dangers of using these salts as growth promoters in swine productions
Evaluation of heat transfer parameters in packed beds with cocurrent downflow of liquid and gas
The results of an experimental investigation on heat transfer from a packed bed with cocurrent gas-liquid downflow to the wall are presented and analyzed in this contribution. The measurements cover the range of operating variables corresponding to the so-called trickle regime in beds presenting aspect ratios (tube to particle diameter ratio) from 4.67 to 34.26. Water and air were employed as model fluids. The heat transfer process was first analyzed by means of a two-dimensional pseudohomogeneous plug-flow model with two parameters, the effective radial thermal conductivity (ker) and the wall heat transfer coefficient (hw). ker is well correlated with liquid and gas Reynolds numbers and particle diameter, except for the lowest experimental aspect ratio (4.67). Instead, a meaningful correlation of hw stands only for aspect ratios larger than 15. These results are analyzed and the evidence points out to sustain the hypothesis that the model fails at low aspect ratios because an apparent contact resistance (1/hw) can no longer accommodate the effects of significant fluid by passing and finite size of the near-wall region. The experimental set of data were also used to develop a correlation for the overall heat transfer coefficient (ht), which can be employed satisfactorily to predict heat transfer rates in the whole range of variables here investigated. © 2001 Elsevier Science Ltd. All rights reserved.Fil: Mariani, Nestor Javier. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de IngenierÃa. Departamento de IngenierÃa QuÃmica; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Martinez, Osvaldo Miguel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina. Universidad de Buenos Aires. Facultad de IngenierÃa. Departamento de IngenierÃa QuÃmica; ArgentinaFil: Barreto, Guillermo Fernando. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentina. Universidad de Buenos Aires. Facultad de IngenierÃa. Departamento de IngenierÃa QuÃmica; Argentin
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