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Search Results: 1 - 10 of 306914 matches for " Víctor Calderón "
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Análisis de Contaminantes en la Cuenca del Río Aconcagua en Chile: Evaluación de Riesgo Humano y Ambiental
Préndez,Margarita; Calderón,Víctor;
Información tecnológica , 2013, DOI: 10.4067/S0718-07642013000100002
Abstract: this paper presents a study and analysis of air pollutants in an area of permanent industrial and agricultural development in chile. the study considers the watershed of the aconcagua river including several cities of the provinces of valparaiso, quillota, san felipe and marga marga. the information obtained from monitoring networks of air quality that are regulated by the chilean health and environmental authorities, during the period 1998 to 2008, was used to develop a qualitative method to assess the risk of contamination to human health and vegetation. the method showed areas of high risk to vegetation and human life and other areas that should be declared as saturated zones. it was also demonstrated that it is necessary to establish primary and secondary standards, particularly for some trace elements considering the importance of the area as an exporter of agricultural products.
Análisis de Contaminantes en la Cuenca del Río Aconcagua en Chile: Evaluación de Riesgo Humano y Ambiental Analysis of Pollutants in the Watershed of the Aconcagua River in Chile: Evaluation of Human and Environmental Risks
Margarita Préndez,Víctor Calderón
Información Tecnológica , 2013,
Abstract: Se presenta un estudio y análisis de contaminantes del aire en una zona de sostenido desarrollo industrial y agrícola en Chile. El estudio comprende la cuenca del río Aconcagua incluyendo varias comunas de las provincias de Valparaíso, Quillota, San Felipe y Marga Marga. La información obtenida de las redes de monitoreo de calidad de aire reguladas por la autoridad ambiental y sanitaria, durante el período 1998 a 2008, se utilizó para elaborar un método de evaluación cualitativa del riesgo de la contaminación para la salud humana y la vegetación. El método evidenció zonas de alto riesgo para la vegetación y la vida humana y otras que debieran ser declaradas zonas saturadas. También mostró la necesidad de establecer normas primarias y secundarias, en particular para algunos elementos traza considerando la importancia de la zona como exportadora de productos agrícolas. This paper presents a study and analysis of air pollutants in an area of permanent industrial and agricultural development in Chile. The study considers the watershed of the Aconcagua river including several cities of the provinces of Valparaiso, Quillota, San Felipe and Marga Marga. The information obtained from monitoring networks of air quality that are regulated by the Chilean health and environmental authorities, during the period 1998 to 2008, was used to develop a qualitative method to assess the risk of contamination to human health and vegetation. The method showed areas of high risk to vegetation and human life and other areas that should be declared as saturated zones. It was also demonstrated that it is necessary to establish primary and secondary standards, particularly for some trace elements considering the importance of the area as an exporter of agricultural products.
Aporte de la hojarasca al ciclo biogeoquímico en plantaciones de Eucalyptus nitens, X Región, Chile
Schlatter,Juan E; Gerding,Víctor; Calderón,Sigrid;
Bosque (Valdivia) , 2006, DOI: 10.4067/S0717-92002006000200006
Abstract: the litterfall in eucalyptus nitens plantations, established on an andisol (close to fresia, x region, chile), were measured after canopy closure (4-7 years old), in an area under different fertilization treatments. at canopy closure annual litterfall was the highest (7-11 t ha-1), and becoming lower after it (5-6 t ha-1); the main quantity was measured in summer (45-60%). with the annual biomass the following amounts of nutrients return to the soil (kg ha-1 year-1): 20-50 n, 1-4 p, 5-40 k and 31-151 ca, respectively, depending on age and fertilizer treatment. the o horizon (litter layer) accumulated 6-10 t ha-1 dry matter at age 7 and the thinning and pruning, carried out at age 5-6, contributed with similar amounts of branches and bark. the litter layer accumulated 100-190 n, <15 p, 20-40 k and 140-230 ca kg ha-1, respectively. this biomass and nutrients constitute an important reservoir for the ecosystem and the sustainability of future rotations.
Aporte de la hojarasca al ciclo biogeoquímico en plantaciones de Eucalyptus nitens, X Región, Chile Litter contribution to biogeochemical cycle in Eucalyptus nitens plantations, X Region, Chile
Juan E Schlatter,Víctor Gerding,Sigrid Calderón
Bosque (Valdivia) , 2006,
Abstract: El presente trabajo evalúa el flujo de hojarasca en una plantación de Eucalyptus nitens establecida en un andisol (comuna de Fresia, X Región, Chile), en un área con diferentes tratamientos de fertilización, desde el cierre de copas hasta el inicio de la edad fustal (4-7 a os de edad). Al cierre de copas se alcanzó la máxima caída de hojarasca (7-11 t ha-1), siendo menor en los a os siguientes (5-6 t ha-1); la mayor proporción (45-60%) cayó en verano. Con esta biomasa regresaron al suelo 20-50 kg ha-1 a o-1 de N, 1-4 de P, 5-40 de K y 31-151 de Ca, según edad y el tratamiento aplicado. En el mantillo se acumularon a los 7 a os 6-10 t ha-1 de biomasa y la poda y el raleo (5-6 a os) adicionaron similares cantidades (ramas y corteza). En el mantillo se acumularon 90-100 kg ha-1 de N, < 15 de P, 20-40 de K y 140-230 de Ca. Esta biomasa y nutrientes constituyen una reserva muy importante para el ecosistema y la sustentabilidad del cultivo. The litterfall in Eucalyptus nitens plantations, established on an andisol (close to Fresia, X Region, Chile), were measured after canopy closure (4-7 years old), in an area under different fertilization treatments. At canopy closure annual litterfall was the highest (7-11 t ha-1), and becoming lower after it (5-6 t ha-1); the main quantity was measured in summer (45-60%). With the annual biomass the following amounts of nutrients return to the soil (kg ha-1 year-1): 20-50 N, 1-4 P, 5-40 K and 31-151 Ca, respectively, depending on age and fertilizer treatment. The O horizon (litter layer) accumulated 6-10 t ha-1 dry matter at age 7 and the thinning and pruning, carried out at age 5-6, contributed with similar amounts of branches and bark. The litter layer accumulated 100-190 N, <15 P, 20-40 K and 140-230 Ca kg ha-1, respectively. This biomass and nutrients constitute an important reservoir for the ecosystem and the sustainability of future rotations.
Análisis de Regresión Logística para datos Correlacionados utilizando tres procedimientos del sistema Estadístico SAS
Segura Correa,José Candelario; Solis Calderón,José de Jesús; Segura Correa,Víctor Manuel;
Revista Científica , 2006,
Abstract: the objective of this study was to compare the results of logistic regressions for correlated data obtained by using three procedures of the statistical analysis system package (sas). information from a cross sectional study on infectious bovine rhinotracheitis in yucatan state, mexico, was used; where the sampling unit was the herd and the unit of interest was the animal. data were analyzed by using the logistic, genmod and nlmixed procedures of the sas. the logistic model used included the risk factors: herd size (£75, 76-147, 148-261, 262-480 animals) and stage of life (growth, development and production). the odd ratios (or) and 95% confidence intervals (ci95) were obtained. also the or and ci95 for the risk factors were estimated using ordinary logistic regression as a reference. the ors for herd size £75, 76-147, 148-261 y 262-480 animals, using logistic, genmod and nlmixed procedures were: 0.34, 0.68, 0.62 and 1; 0.34, 0.63, 0.63 and 1; and 0.29, 0.62, 0.57 and 1, respectively; and for the animals in the stage of growth, development and production were: 0.12, 0.15 and 1; 0.15, 0.17 and 1; and 0.12, 0.14 and 1, respectively. the narrower ci95 were for the ors from the ordinary logistic regression and the widest for the or obtained using the nlmixed procedure. in conclusion, the three procedures adjusted for herd effect, being the most precise those of the nlmixed procedure.
Awareness, consecuencias de una experiencia estresante
LUENGO J,VíCTOR; ZAPATA P,CAROLA; DELFINO,ALEJANDRO; CALDERóN,JORGE; GONZáLEZ,MATíAS;
Revista médica de Chile , 2010, DOI: 10.4067/S0034-98872010000300016
Abstract: anesthesia awareness, or "unintended intra-operative awareness" occurs during general anesthesia, on the operating table, when a patient has not had enough general anesthetic or analgesic to prevent consciousness or waking up during surgery. according to international studies its global incidence ranges from 0.1 to 0.2%. its impact on people can be as severe as other traumatic experiences such as natural disasters, violent fights or sexual abuse. the prevalence of symptoms compatible with post traumatic stress disorder can be as high as 50%, after experiencing the awareness phenomenon. this paper reviews the main issues of the awareness phenomenon.
Detección de la expresión génica in vivo de Mycobacterium tuberculosis durante la tuberculosis pulmonar activa Mycobacterium tuberculosis in vivo-expressed genes detection during active pulmonary tuberculosis
Alejandra Otazo M,Ingrid Gutiérrez S,Víctor Acevedo F,Carlos Calderón A
Revista Chilena de Enfermedades Respiratorias , 2012,
Abstract: El estudio de la expresión génica de Mycobacterium tuberculosis ha involucrado la experimentación "in vitro ", "ex vivo " e "in vivo " (modelos animales), pero aún sin el éxito esperado. Proponemos que revelar los factores clave de la tuberculosis humana requiere investigar la expresión génica de M. tuberculosis dentro del ser humano ("in vivo "). Para ello, aislamos el mRNA total de M. tuberculosis, desde muestras clínicas respiratorias de pacientes con diagnóstico de tuberculosis pulmonar; posteriormente, sintetizamos el dscDNA y lo analizamos mediante RT-PCR cualitativo. Detectamos la expresión de la secuencia de inserción IS6110 y de los genes "housekeeping " 16SrRNA y sigA en M. tuberculosis creciendo in vivo (tuberculosis pulmonar) así como cultivado in vitro. La expresión de los genes mprA y mprB, que codifican el sistema de transducción de se ales MprAB, sólo se detectó en M. tuberculosis crecido in vitro. Con nuestros resultados damos el primer paso hacia la implementación de un método no invasivo para el estudio del transcriptoma de M. tuberculosis, dentro de su único hospedero natural, con el fin de analizar la regulación "in vivo" de los determinantes genéticos requeridos para su virulencia y patogénesis. Mycobacterium tuberculosis gene expression studies have involved "in vitro", "ex vivo" and "in vivo" experiments (animal models), but without the expected success. We propose that key features of human tuberculosis could be discovered by studying the M. tuberculosis gene expression within the human host. Therefore, we isolated totalM. tuberculosis mRNA from human clinical respiratory specimens of patients diagnosed with pulmonary tuberculosis; after this, we synthesized the dscDNA and tested it by qualitative RT-PCR assays. We detected the expression of IS6110 insertion sequence and of the "housekeeping" genes 16SrRNA andsigA in M. tuberculosis grown in vivo (pulmonary tuberculosis) as well as grown in vitro M. tuberculosis. mprA and mprB genes expression, which code the MprAB signal transduction system, were only detected in M. tuberculosis grown in vitro. Our results provide the first step towards a non invasive methodfor the study of the transcriptome of M. tuberculosis within its native host, to analyze "in vivo" regulation of the genetic determinants required for virulence and pathogenesis.
Awareness, consecuencias de una experiencia estresante Anesthesia awareness
VíCTOR LUENGO J,CAROLA ZAPATA P,ALEJANDRO DELFINO,JORGE CALDERóN
Revista médica de Chile , 2010,
Abstract: Anesthesia awareness, or "unintended intra-operative awareness" occurs during general anesthesia, on the operating table, when a patient has not had enough general anesthetic or analgesic to prevent consciousness or waking up during surgery. According to international studies its global incidence ranges from 0.1 to 0.2%. Its impact on people can be as severe as other traumatic experiences such as natural disasters, violent fights or sexual abuse. The prevalence of symptoms compatible with post traumatic stress disorder can be as high as 50%, after experiencing the awareness phenomenon. This paper reviews the main issues of the awareness phenomenon.
Cobertura de úlceras por presión trocantéricas con colgajo de tensor de fascia lata en V-Y
CALDERóN O,WILFREDO; OYARSE M,EDUARDO; OLIVARES G,CAROLINA; ROCO M,CTOR; LENIZ M,PATRICIO; CALDERóN M,DANIEL; NORAMBUENA B,HERNáN; DEICHLER V,FERNANDA;
Revista chilena de cirugía , 2009, DOI: 10.4067/S0718-40262009000500005
Abstract: background: trochanter pressure sores can be treated with random, myocutaneous, fasciocutaneous or free flaps. aim: to report the use of v-y and tensor fasciae latae flaps for the treatment of trochanteric pressure sores. material and methods: prospective study of 14 males and two females aged 24 to 64 years, with 17 sores. the surgical technique consisted in the design of a v shaped flap with irrigation in its superior base and lower vertex with one of its extremes in contact with the sore. a resection is made until a vital base is obtained, excising the prominent bone until a plane in which healthy tissue is seen. the flap is raised and rotated, covering the defect. a v-y primary closure without tensión is performed, leaving drainages that are withdrawn ten days later. results: the complications recorded were three serranas, which were treated using a closed system with external and internal negative pressure. two wound dehiscence episodes and two hematomas required a surgical correction. conclusions: this type of flap is other therapeutic alternative for pressure trochanteric sores.
Efecto de un sistema de enfriamiento a espacio abierto en la eficiencia productiva de novillos holstein durante el verano
Correa-Calderón,Abelardo; Yá?ez,Víctor; Verdugo,Francisco; Pérez,Adolfo; Avenda?o,Leonel; González,Víctor Manuel; Ponce,Francisco; Tarazón,Mario;
Interciencia , 2004,
Abstract: to evaluate the effects of an open space cooling system on weight gain, feed intake and respiration rate, 32 holstein steers (373kg) were randomly assigned in two treatments, a control group with shade only in the pen (n=16) and a second group with an open space cooling system (n=16). the open space cooling system consisted of a 2.4m diameter blade fan circulating 1416m3/min of air, with oscillation coverage of 90o. the amount of water discharged was 12l/min. the study was conducted for 90 days with a daily maximal temperature-humidity index (thi) of 84 to 90. there was no difference (p>0.05) in daily weight gain (1.34 ±0.05 vs 1.41 ±0.05kg/day) or feed intake (9.9 vs 10.5kg/day) for control and cooling groups, respectively. however, there was a tendency to increase the productive performance and to reduce the respiration rate (p<0.05) in steers under the cooling system as compared to control group (89 vs 104 breaths per minute), indicating an improvement in their comfort.
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