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Search Results: 1 - 10 of 384979 matches for " C. Román-Cascón "
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Evening transitions of the atmospheric boundary layer: characterization, case studies and WRF simulations
M. Sastre, C. Yagüe, C. Román-Cascón, G. Maqueda, F. Salamanca,S. Viana
Advances in Science and Research (ASR) , 2012, DOI: 10.5194/asr-8-39-2012
Abstract: Micrometeorological observations from two months (July–August 2009) at the CIBA site (Northern Spanish plateau) have been used to evaluate the evolution of atmospheric stability and turbulence parameters along the evening transition to a Nocturnal Boundary Layer. Turbulent Kinetic Energy thresholds have been established to distinguish between diverse case studies. Three different types of transitions are found, whose distinctive characteristics are shown. Simulations with the Weather Research and Forecasting-Advanced Research WRF (WRF-ARW) mesoscale model of selected transitions, using three different PBL parameterizations, have been carried out for comparison with observed data. Depending on the atmospheric conditions, different PBL schemes appear to be advantageous over others in forecasting the transitions.
Observations and WRF simulations of fog events at the Spanish Northern Plateau
C. Román-Cascón, C. Yagüe, M. Sastre, G. Maqueda, F. Salamanca,S. Viana
Advances in Science and Research (ASR) , 2012, DOI: 10.5194/asr-8-11-2012
Abstract: The prediction of fogs is one of the processes not well reproduced by the Numerical Weather Prediction (NWP) models. In particular, the role of turbulence in the formation or dissipation of fogs is one of the physical processed not well understood, and therefore, not well parameterized by the NWP models. Observational analysis of three different periods with fogs at the Spanish Northern Plateau has been carried out. These periods have also been simulated with the Weather Research and Forecasting (WRF) numerical model and their results have been compared to observations. The study includes a comparison of the skill of different planetary boundary layer (PBL) parameterizations, surface layer schemes and a test of the gravitational settling of clouds/fogs droplets option. A statistical analysis of this comparison has been evaluated in order to study differences between the periods and between the various parameterizations used. The model results for each PBL parameterization were different, depending on the studied period, due to differences in the features of each fog. This fact made it difficult to obtain generalized conclusions, but allowed us to determine which parameterization performed better for each case. In general, judging from the models results of liquid water content (LWC), none of the PBL schemes were able to correctly simulate the fogs, being Mellor-Yamada Nakanishi and Niino (MYNN) 2.5 level PBL scheme the best one in most of the cases. This conclusion is also supported by the root mean square error (RMSE) calculated for different meteorological variables.
IDENTIDADES EN JUEGO. PRáCTICAS LúDICAS EN JóVENES MAPUCHE | IDENTITIES AT STAKE. LUDIC PRACTICES IN MAPUCHE YOUNGSTERS
Aldo Román Césaro
ágora para la Educación Física y el Deporte , 2010,
Abstract: RESUMEN.- El presente artículo es una síntesis de una investigación realizada como tesis de Maestría en Educación Corporal, Universidad Nacional de La Plata, Argentina.El trabajo localizó su área de estudio en el juego y la identidad, delimitando el problema de indagación a la relación que se establece entre las prácticas lúdicas y los procesos de identificación cultural. El enfoque específico se detuvo en las "identificaciones lúdicas" en jóvenes de ascendencia mapuche, observados a través del recorrido de diferentes espacios de interacción.Los referentes empíricos con quienes tracé el trabajo de campo se ubican en diferentes poblados del Noreste de la provincia de Chubut, Argentina.Sostengo que la identidad cultural demanda una compleja elaboración subjetiva, en una red de discursos y prácticas contradictorias, opuestas y conflictivas entre el pasado y lo emergente. Algunas de las preguntas que me surgieron en este sentido fueron: qué influencias tuvieron los hechos del pasado en la materialización de ciertas prácticas lúdicas actuales? Muestran estas relaciones conflictos identitarios? Si esto es posible cómo se produce entonces la relación entre los juegos, la tradición y los cambios que permiten reconfigurar la identidad cultural? Por ende, qué factores han permitido los procesos de adaptación y transformación lúdica? Qué rol cumplen los jóvenes en esta dinámica? Algunas de estas respuestas podrán encontrarse a lo largo de este artículo. ABSTRACT.- The article is a synopsis of a research carried out within the masters' degree in Corporal Education, University Nacional de La Plata, Argentina.The aim of the study was about the relationship between games and identity. The concrete research problem was the relationships between the playful practices of Mapuche children and the process of cultural identification. Observations took place in different scenarios of interaction. The empiric fieldwork of this study was located in different communities of the northeast of Chubut, Argentina.My argument is that cultural identity demands a complex system of discourses and contradictory and conflicting practices between the past and the emergent. Some of the questions that appeared to us were: How the past materialized in their present playful practices? How is the relationship between games, tradition and the changes that can reshape the cultural identity? Do the relations between past and present materialize in identity conflicts? What factors have permitted the adaption process and playful transformation? Finally, what role do the children play in these d
Riesgos asociados con las radiaciones ionizantes
Cascón,Adriana;
Revista argentina de cardiolog?-a , 2009,
Abstract: medical use of ionizing radiations implies certain risks which are widely balanced by their diagnostic and therapeutic benefits. nevertheless, knowledge about these risks and how to diagnose and prevent them minimizes their disadvantages and optimizes the quality and safety of the method. this article describes the aspects related to skin dose (nonstochastic effects), the importance of dose limit, the physiopathology of biological damage and, finally, the prevention measures.
Riesgos asociados con las radiaciones ionizantes
Adriana Cascón
Revista Argentina de Cardiología , 2009,
Abstract: El uso médico de las radiaciones ionizantes implica ciertos riesgos, aunque están ampliamente compensados por sus beneficios diagnósticos y terapéuticos. No obstante, el conocimiento de esos riesgos, así como su diagnóstico y prevención, minimiza sus inconvenientes y optimiza la calidad y la seguridad de su empleo. En este artículo se discuten aspectos vinculados con la relación dosis-respuesta en la piel (efectos determinísticos), la importancia del límite de la dosis, la fisiopatología del da o biológico y, por último, con las medidas de prevención.REV ARGENT CARDIOL 2009;77:123-128.
Neurological manifestations of malaria
Román, Gustavo C.;Senanayake, Nimal;
Arquivos de Neuro-Psiquiatria , 1992, DOI: 10.1590/S0004-282X1992000100002
Abstract: the involvement of the nervous system in malaria is reviewed in this paper. cerebral malaria, the acute encephalopathy which complicates exclusively the infection by plasmodium falciparum commonly affects children and adolescents in hyperendemic areas. plugging of cerebral capillaries and venules by clumped, parasitized red cells causing sludging in the capillary circulation is one hypothesis to explain its pathogenesis. the other is a humoral hypothesis which proposes nonspecific, immune-mediated, inflammatory responses with release of vasoactive substances capable of producing endothelial damage and alterations of permeability. cerebral malaria has a mortality rate up to 50%, and also a considerable longterm morbidity, particularly in children. hypoglycemia, largely in patients treated with quinine, may complicate the cerebral symptomatology. other central nervous manifestations of malaria include intracranial hemorrhage, cerebral arterial occlusion, and transient extrapyramidal and neuropsychiiatric manifestations. a self-limiting, isolated cerebellar ataxia, presumably caused by immunological mechanisms, in patients recovering from falciparum malaria has been recognized in sri lanka. malaria is a common cause of febrile seizures in the tropics, and it also contributes to the development of epilepsy in later life. several reports of spinal cord and peripheral nerve involvement are also available. a transient muscle paralysis resembling periodic paralysis during febrile episodes of malaria has been described in some patients. the pathogenesis of these neurological manifestations remains unexplored, but offers excellent perspectives for research at a clinical as well as experimental level.
Alimentación y reproducción de Creagrutus brevipinnis (Pisces: Characidae) en Alto Cauca, Colombia
Román-Valencia,César;
Revista de Biología Tropical , 1998,
Abstract: stomach contents and reproduction were studied in characid fish (c. brevipinnis)collected in the vieja river basin, alto cauca, colombia (july 1995 and december 1996); the temperature in the region was 21.7 °c (18.70-24.40 °c), ph was neutral and water oxygen content high (8 ppm); c . brevipinnis is nonmigratory and sympatric with other 30 fish species; the fish is insectivorous and specializes on diptera (simuliidae) and ephemeroptera; being a third level predator in the trophic web; it feeds from 06:00-18:00 hr ; the results indicate seasonal variation in feeding activity (f= 19.04 p< 0.0001) and a negative correlation between stomach weight and voracity indexes; in the reproductive season food in take is low; the ovaries mature primarily between may and january ; fecundity is low (613 oocytes) and the eggs are of small (diameter 0.6254 mm) ; the sex ratio is 1:1 (x2= 2.56 p< 0.1 df = 1) and the mean size at maturity is 4.0 cm (standard length).
Tres nuevas especies de Bryconamericus (Ostariophysi: Characidae) de Colombia y diagnóstico del género
Román-Valencia,César;
Revista de Biología Tropical , 2000,
Abstract: three new fish species are described: bryconamericus dahli from the basins of the patia and mira rivers; b. ichoensis from chaparraido creek, the upper atrato river basin, and b. galvisi from upper putumayo river. bryconamericus dahli can be distinguished from other bryconamericus species by body depth and the larger head. b. dahli is similar to b. caucanus, but can be distinguished by the number of anal fin rays, head width and maxilla. bryconamericus ichoensis can be distinguished by its small size, absence of a spot on the caudal peduncle, and generally 27 to 30 anal fin rays. b. ichoensis may be closely related to b. multiradiatus, but can be distinguished by the number of unbranched rays in the dorsal, pectoral and pelvic fins, the number of predorsal scales, body depth, etc. bryconamericus galvisi, can be distinguished from other species of bryconamericus by its single peduncle spot, high branched anal fin ray, the lateral line scales count, and elongated body. this species is similar to b. caucanus and can be distinguished by the number of teeth on the maxilla and by the number of vertebrae. the genus bryconamericus is a natural and valid group, which is related to hemibrycon. moreover the knodus and eretmobrycon are synonym of bryconamericus.
Ecología trófica y reproductiva de Trichomycterus caliense y Astroblepus cyclopus (Pisces: Siluriformes) en el río Quindio, Alto Cauca, Colombia
Román-Valencia,César;
Revista de Biología Tropical , 2001,
Abstract: the trophic and reproductive ecology of catfish (trichomycterus caliense and astroblepus cyclopus) was studied in the quindio river upper basin, alto cauca, colombia. the ph was neutral, water oxygen content high (8.4 ppm) and temperature in the habitats was 18.63°c; both species are nonmigratory and sympatric with four other fish species. the ovaries mature primarily between may and september in t. caliense; between december and may in a. cyclopus. the mean size at maturity is 8.3 cm (standard length) in t. caliense and 6.0 cm (standard length) in a. cyclopus; the sex ratio is 1:1 in t. caliense (x=3.4, p>0.05) and in a. cyclopus (x2=1.44, p>0.1); the fecundity is low (191 and 113 oocytes respectively) and the eggs are small (1.5 and 2.39 mm respectively). the fishes are insectivorous and specialize in coleoptera, diptera and trichoptera; spearman rank correlation coefficients (rs=0.464) indicated that there are differences (t= 2.5148, p<0.01) between their diets; both taxa did not agree with the expected trophic habits for sympatric species that are morphologically similar and related in the same trophic level.
Alimentación y reproducción de Creagrutus brevipinnis (Pisces: Characidae) en Alto Cauca, Colombia
César Román-Valencia
Revista de Biología Tropical , 1998,
Abstract: Contenido estomacal y aspectos reproductivos fueron estudiados en un pez caracido (C. brevipinnis) de el Alto Cauca (Julio 1995 a diciembre de 1996). La temperatura promedio en la región fue de 21° C, pH alrededor de la neutralidad; oxígeno disuelto alto (8 ppm); es una especie no migratoria. El pez es predominantemente insectívora y especializado (Diptera: Simuliidae ; Ephemeroptera), siendo ubicado en el tercer nivel de la red trófica. La actividad alimentaria registró diferencias altamente significativas entre la época lluviosa y la seca de la región (F=19.04 ; P< 0.0001). El comportamiento alimentario se realizó en el sustrato entre las 6:00 hr y las 18:00 hr. Se observó correlación negativa entre el peso del estómago y el índice de voracidad. La especie en la época de reproducción consumió poco alimento. El desarrollo máximo de las gónadas se registró entre mayo y junio. La fecundidad fue baja ( promedio 613 ovocitos) y el ovocito fue peque o (promedio 0.6254 mm). La proporción entre sexos fue de 1:1 (x2= 2.56 P<0.1 gl=1) y el tama o promedio de madurez para la población estudiada fue de 4.0 cm de longitud estándar. Es simpátrica con 30 especies de peces, siendo La Sabaleta Brycon henni y C. brevipinnis las más abundantes. Stomach contents and reproduction were studied in characid fish (C. brevipinnis)collected in the Vieja River Basin, Alto Cauca, Colombia (July 1995 and December 1996); the temperature in the region was 21.7 °C (18.70-24.40 °C), pH was neutral and water oxygen content high (8 ppm); C . brevipinnis is nonmigratory and sympatric with other 30 fish species; The fish is insectivorous and specializes on Diptera (Simuliidae) and Ephemeroptera; being a third level predator in the trophic web; it feeds from 06:00-18:00 hr ; the results indicate seasonal variation in feeding activity (F= 19.04 P< 0.0001) and a negative correlation between stomach weight and voracity indexes; in the reproductive season food in take is low; the ovaries mature primarily between May and January ; fecundity is low (613 oocytes) and the eggs are of small (diameter 0.6254 mm) ; the sex ratio is 1:1 (X2= 2.56 P< 0.1 df = 1) and the mean size at maturity is 4.0 cm (standard length).
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