oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 193 )

2018 ( 293 )

2017 ( 293 )

2016 ( 406 )

Custom range...

Search Results: 1 - 10 of 230117 matches for " MARIO CéSAR; ARCILA "
All listed articles are free for downloading (OA Articles)
Page 1 /230117
Display every page Item
SELECCIóN DE UN MODELO CóPULA PARA EL AJUSTE DE DATOS BIVARIADOS DEPENDIENTES
LOPERA,CARLOS MARIO; JARAMILLO,MARIO CéSAR; ARCILA,LUIS DAVID;
DYNA , 2009,
Abstract: modeling problems involving bivariate dependent data is very important in many areas, such as finance, actuary, reliability and survival analysis. in the literature, some copula models have been widely used to modelling dependent multivariate distributions, among which stands out the archimedean copula class. this paper presents a methodology to select from some archimedean copula models the one that fits the best to a dependent dataset, using goodness-of-fit plots, q-q plots and cramér-von mises goodness-of-fit test. we illustrated the methodology using simulated data and data from insurance claims. the results showed that the data insurance fits to a bivariate model based on the so called frank's copula with lognormal marginals.
SELECCIóN DE UN MODELO CóPULA PARA EL AJUSTE DE DATOS BIVARIADOS DEPENDIENTES
CARLOS MARIO LOPERA,MARIO CéSAR JARAMILLO,LUIS DAVID ARCILA
DYNA , 2009,
Abstract: El modelamiento en problemas que involucran datos bivariados dependientes es muyimportante en diversas áreas del conocimiento, tales como: finanzas, actuaría, confiabilidad y análisis de supervivencia. En la literatura, se conocen algunos modelos cópula que han sido ampliamente utilizados para modelar distribuciones multivariadas dependientes, entre los cuales se destaca la clase de cópulas Arquimedianas. En este artículo, se presenta una metodología para seleccionar entre algunos modelos cópula Arquimedianos el que mejor se ajusta a un conjunto de datos dependientes, utilizando gráficos de bondad de ajuste, gráficos cuantil cuantil (Q-Q plot) y la prueba analítica de bondad de ajuste de Cramér-von Mises. Se realizó una aplicación de la metodología con datos simulados y utilizando datos de siniestros en pólizas de seguro. Los resultados mostraron que los datos de seguros se ajustan a un modelo bivariado basado en la cópula Frank con marginales lognormales.
Medio ambiente fetal Fetal environment
César Bernardo Ospina Arcila
Iatreia , 1996,
Abstract: Con base en el artículo clásico "Monte Everest in utero" se hace un análisis de la situación que afronta el feto con respecto a la disponibilidad de oxígeno; para una mejor comprensión del sufrimiento fetal se revisan los siguientes conceptos: presión barométrica, presión parcial del oxígeno atmosférico, presión parcial del oxígeno inspirado, presión barométrica intranasal, ecuación del gas alveolar y difusión de gases a través de la membrana alvéolo capilar. Based on the classical paper by Eastman "Mount Everest in utero" an analysis is made of the situation faced by the fetus with respect to the availability of oxygen; for a better under. standing of fetal distress the following concepts are reviewed: barometric pressure, partial pressure of atmosferic oxygen, partial pressure of inspired oxygen, barometric intranasal pressure, alveolar gas equation and gas diffusion through alveolo-capilar membrane.
Variación morfológica de los peces Hemibrycon boquiae y Hemibrycon rafaelense (Characiformes: Characidae) en el Río Cauca, Colombia
Román-Valencia,César; Arcila-Mesa,Dahiana K; Hurtado T,Hernando;
Revista de Biología Tropical , 2009,
Abstract: morphological variation in populations of hemibrycon boquiae and h. rafaelense from rio cauca, colombia. we analyzed the variation in morphological and osteological characteristics of hemibrycon boquiae and hemibrycon rafaelense in the cauca river. the multivariate analysis determined populations of h. boquiae in nine streams: boquier, honda, las aguilas, do?a juana, villa paola, portachuelo, the snake, aimes and ramirez, and populations of h. rafaelense in four streams: canceles, clara, san rafael and san jose. there were morphometric differences among populations of h. boquiae (n= 277) and h. rafaelense (n= 121). nevertheless, there were significant meristic discrepancies among populations of both species: number of scales between lateral line and anal fin, and number of scales between lateral line and pelvic fin. the absence of bilateral symmetry was observed in the number of maxillary teeth in h. boquiae. the cluster analysis distance for osteological characters, including the number of predorsal scales, separated h. boquiae and h. rafaelense in two defined groups. rev. biol. trop. 57 (3): 541-556. epub 2009 september 30.
Five new species of Hemibrycon (Characiformes: Characidae) from the Río Magdalena basin, Colombia
Román-Valencia,César; Arcila-Mesa,Dahiana K;
Revista de Biología Tropical , 2010,
Abstract: five new fish species of the genus hemibrycon are described from the río magdalena basin, colombia, using morphometric, meristic and osteological characters. hemibrycon paez (n=40) differs in number of lateral line scales (39 to 42 vs. 43 to 54), by the number of scales between lateral line and anal-fin origin (6 to 7 vs. 4 to 5) and between lateral line and dorsal-fin origin (6 to 7 vs. 8); h. quindos (n=66) distinguished from its congeners by one autopomorphy: males with cartilaginous protuberance, rounded on the anal fin ray branched, along all rays (vs. cartilaginous protuberance not present on anal-fin rays in males), by the maxilla without a fold on its anterior end (vs. maxilla with folding only at posterior end), by the number of pored scales in the lateral line (35 to 40 vs. 40 to 46); h. raqueliae (n=117) distinguished by a widened first tooth on the maxilla with the remaining teeth decreasing sharply in size (vs. first tooth of maxilla slender, remaining teeth gradually diminishing), by the first maxilla tooth pentacuspid and wider than the others (vs. first tooth on maxilla unicuspid or tricuspid and of same size as the others); h. virolinica (n=34) distinguished by the posterior end of the extrascapular spine surpassing the postemporal (vs. posterior end of extrascapular not exceeding postemporal spine), by having the posterior end of the first proximal pteryigiophores of dorsal fin of the same size as the anterior edge (vs. the posterior end of the first proximal pteryigiophores of dorsal fin more elongated than the anterior edge); and h. yacopiae (n=78) is distinguished by the following autopomorphic characters: first laterosensorial infraorbitals canal in contact with the posterior end of antorbital (vs. laterosensorial canal not reaching posterior end of antorbital), by the tip of the supraoccipital spine widened (vs. supraoccipital spine acute), by the posterior end of ectopterygoids failing to come in contact with the quadrate bone (vs. in contact
Five new species of Hemibrycon (Characiformes: Characidae) from the Río Magdalena basin, Colombia
César Román-Valencia,Dahiana K Arcila-Mesa
Revista de Biología Tropical , 2010,
Abstract: Five new fish species of the genus Hemibrycon are described from the Río Magdalena basin, Colombia, using morphometric, meristic and osteological characters. Hemibrycon paez (n=40) differs in number of lateral line scales (39 to 42 vs. 43 to 54), by the number of scales between lateral line and anal-fin origin (6 to 7 vs. 4 to 5) and between lateral line and dorsal-fin origin (6 to 7 vs. 8); H. quindos (n=66) distinguished from its congeners by one autopomorphy: Males with cartilaginous protuberance, rounded on the anal fin ray branched, along all rays (vs. cartilaginous protuberance not present on anal-fin rays in males), by the maxilla without a fold on its anterior end (vs. maxilla with folding only at posterior end), by the number of pored scales in the lateral line (35 to 40 vs. 40 to 46); H. raqueliae (n=117) distinguished by a widened first tooth on the maxilla with the remaining teeth decreasing sharply in size (vs. first tooth of maxilla slender, remaining teeth gradually diminishing), by the first maxilla tooth pentacuspid and wider than the others (vs. first tooth on maxilla unicuspid or tricuspid and of same size as the others); H. virolinica (n=34) distinguished by the posterior end of the extrascapular spine surpassing the postemporal (vs. posterior end of extrascapular not exceeding postemporal spine), by having the posterior end of the first proximal pteryigiophores of dorsal fin of the same size as the anterior edge (vs. the posterior end of the first proximal pteryigiophores of dorsal fin more elongated than the anterior edge); and H. yacopiae (n=78) is distinguished by the following autopomorphic characters: first laterosensorial infraorbitals canal in contact with the posterior end of antorbital (vs. laterosensorial canal not reaching posterior end of antorbital), by the tip of the supraoccipital spine widened (vs. supraoccipital spine acute), by the posterior end of ectopterygoids failing to come in contact with the quadrate bone (vs. in contact); by the posterior edge of palatine more widened than the anterior edge of ectopterygoids (vs. posterior edge of the palatine approximately the same size, except for H. paez). Rev. Biol. Trop. 58 (1): 339-356. Epub 2010 March 01. Cinco nuevas especies son descritas para la cuenca del Río Magdalena, Colombia, con base en caracteres morfométricos, merísticos y osteológicos. Hemibrycon paez se distingue por el número de escamas en la línea lateral (39 a 42 vs. 43 a 54), entre la línea lateral y el origen de la aleta anal (6 a 7 vs. 4 a 5), y entre la línea lateral y el origen de la aleta dorsal
Variación morfológica de los peces Hemibrycon boquiae y Hemibrycon rafaelense (Characiformes: Characidae) en el Río Cauca, Colombia
César Román-Valencia,Dahiana K Arcila-Mesa,Hernando Hurtado T
Revista de Biología Tropical , 2009,
Abstract: Analizamos la variación morfológica y osteológica en Hemibrycon boquiae y H. rafaelense en la cuenca del río Cauca. Los análisis multivariados determinan poblaciones de H. boquiae en las quebradas: Boquiae, Honda, Las águilas, Do a Juana, Villa Paola, Portachuelo, La Víbora, Aimes y Ramírez y poblaciones de H. rafaelense en las quebradas: Canceles, La Clara, San Rafael y San José. No hay diferencias en la morfometría entre las poblaciones de H. boquiae y H. rafaelense. Se presentan discrepancias merísticas significativas para las poblaciones de H. boquiae (n= 277) y H. rafaelense (n= 121) en: número de escamas entre la línea lateral y la aleta anal, y número de escamas entre la línea lateral y la aleta pélvica. La distancia de similaridad del análisis de agrupamiento ("cluster") para los caracteres osteológicos, al igual que el número de escamas predorsales, apoyan la existencia de dos grupos discretos que corresponden a H. boquiae y H. rafaelense. Morphological variation in populations of Hemibrycon boquiae and H. rafaelense from Rio Cauca, Colombia. We analyzed the variation in morphological and osteological characteristics of Hemibrycon boquiae and Hemibrycon rafaelense in the Cauca River. The multivariate analysis determined populations of H. boquiae in nine streams: Boquier, Honda, Las Aguilas, Do a Juana, Villa Paola, Portachuelo, The Snake, Aimes and Ramirez, and populations of H. rafaelense in four streams: Canceles, Clara, San Rafael and San Jose. There were morphometric differences among populations of H. boquiae (n= 277) and H. rafaelense (n= 121). Nevertheless, there were significant meristic discrepancies among populations of both species: number of scales between lateral line and anal fin, and number of scales between lateral line and pelvic fin. The absence of bilateral symmetry was observed in the number of maxillary teeth in H. boquiae. The cluster analysis distance for osteological characters, including the number of predorsal scales, separated H. boquiae and H. rafaelense in two defined groups. Rev. Biol. Trop. 57 (3): 541-556. Epub 2009 September 30.
Disparidades económicas sobre unidades territoriales menores: análisis de convergencia
Luis César Herrero Prieto,Víctor Fernando Figueroa Arcila,José ángel Sanz Lara
Investigaciones Regionales , 2010,
Abstract: El objetivo fundamental de este trabajo es analizar la aplicabilidad de los modelos de convergencia económica en unidades territoriales menores y sobre la base de la estimación de indicadores sintéticos de desarrollo. Para tal efecto, se postula la aplicación de modelos de regresión espacial a partir de un índice compuesto de desarrollo con desagregación municipal y construido mediante técnicas de análisis multivariante. La aplicación de esta metodología se realiza sobre una región prototipo, el sistema municipal de la Comunidad Autónoma de Castilla y León durante el periodo 1981-2001, con el fin de mostrar también la evolución de las disparidades territoriales en este ámbito.
Efectos de la instalación de un gasoducto sobre algunas propiedades del suelo superficial y la cobertura vegetal en el NE de Chubut
Kowaljow,Esteban; Rostagno,César Mario;
Ciencia del suelo , 2008,
Abstract: in this work we describe the impact of a gas-pipeline installation and the replacing of the material removed in part of the clear-cutting, on some physical and chemical properties of the soils and vegetation in three ecological sites of northeastern chubut. in these sites we identified four different areas: area 1, clear-cut strip, where the traffic of heavy machinery was intense; area 2, clear-cut strip, with soil and vegetation replaced; and other two areas in the undisturbed adjacent steppe: mounds associated to shrubs and mound interspaces. the highest bulk densities were recorded in area 1 and in the mound interspaces (1.43 mg m-3). the penetrometer resistance was significantly higher in the areas 1 and 2, recording values higher than 1 mpa. the infiltration rate was much higher in the mound (261 mm h-1) than in the other areas. the infiltration rate of area 2 (85 mm h-1) was higher than that of area 1 (35 mm h-1) and the mound interspaces (50 mm h-1). total nitrogen and organic carbon content in soils of the areas 1 and 2 were similar to those of the mound interspaces and significantly lower than those of the mound, except in the area 2 of one ecological site. clear-cut and topsoil removal, and the subsequent traffic of heavy machinery caused by underground gas-pipeline installation produced a strong impact on the physical properties of these soils. the main limitation in the highly disturbed soils was the decrease in the infiltration rate, mainly due to high compaction and low porosity. this may in part explain the slow vegetation cover recovery in the area 1. the replacement of the stripped sediment and vegetation on the disturbed strip did not improve the recovery of the vegetation cover. it was mainly due to the low quality of the sediments extracted from the pipeline ditch.
Emission of some rare gases at the Los Azufres, Mexico, geothermal reservoir
Mario César Suárez Arriaga
Geofísica internacional , 2002,
Abstract: The chemistry of fluids in the Los Azufres, Mexico geothermal field originated from volcanic processes and is controlled by temperatures at depth, mineral solubility, pH values and mineral equilibrium. Vapor phase at this reservoir has an heterogeneous composition. It shows a wide range of non condensible gases (NCG) concentration, which ranges between 1% and 9% of total gas weight in the steam phase. NCG are routinely measured in this reservoir and typically contain CO2 , H2S, NH3 , CH4 , O2 , H2 , He, N2 and Ar; although there are also Ne, Kr and Xe, but these gases are not registered. Carbon dioxide is the major constituent found in the field, representing between 70% and 99% of total NCG weight. The highest CO2 content is found in shallow wells with high steam quality. H2S is the second most important gas, varying between 0.2% and 13% in the total weight. Simultaneously to fluid extraction, significant amounts of cold liquid and air are injected into the reservoir, modifying its natural geochemistry. Total gas concentration found in some wells are increased because of the extra amount of atmospheric N2 and Ar injected. The molar quotient N2 /Ar has been falling with time reaching in some cases the same value as in the atmosphere. Both gases are pushing the NCG changing their natural spatial distribution. The thermodynamic effect of reinjection has been beneficial for the energy production and longevity of this geothermal field. Rare gases such as He and Ar measured in this field show a low, but general trend to increase when the corresponding wells are subjected to continuous production, with few unusual exceptions. Apparently, such increment is proportional to the amount of fluid extracted and to the time of extraction. But, in other cases, the dependence of both gases on production is not clear. In this paper the observed evolution and spatial distribution of NCG and of those two rare gases at the Los Azufres geothermal field are reported for the period 1981 1999.
Page 1 /230117
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.