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Search Results: 1 - 10 of 338372 matches for " Iván F. Benavides-Martínez "
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EFECTO DEL GRADIENTE ALTITUDINAL SOBRE ASPECTOS AUTOECOLóGICOS DE ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) EN EL PáRAMO EL INFIERNILLO (NARI?O-COLOMBIA)
Benavides-Martínez,Iván F.; Burbano-Martínez,Diana L.; Urbano-Apráez,Sandra M.; Solarte-Cruz,María E.;
Actualidades Biológicas , 2007,
Abstract: some autoecological features of espeletia pycnophylla ssp. angelensis cuatrec. such as its demographic structure, population density, spatial pattern of dispersion, production of reproductive structures, adult morphometry and survivorship, were studied in an altitudinal gradient on a dry paramo of nari?o (colombia). hypothesis proposed by other authors about a linear effect caused by the elevation on these variables were completely rejected. the elevation induces an ecoclinal effect on population density, and this density correlates negatively with both production of reproductive structures and adult sizes. these results elucidate an unequivocal effect of density-dependence phenomena on population fitness. the intermediate zone of the altitudinal gradient exhibits a high population density, but on the other hand show reduced corporal adult sizes, minimal production of reproductive structures and the probability of juveniles reaching advanced ages is low. evidently, this intermediate elevation can have favorable ecological conditions for the seedling establishment, wich increments population densities at long term. we propose that other author's generalizations about the influence of elevation on the autoecology of these plants are limited, because the particular life and disturbance stories of paramos and the spatial, ecological and genetic isolating are explicative factors impossible to take away from the context. the demographic structure of the population fitted the logarithmic model, revealing its early regeneration state from the last fire event on 2003 and the similarity of the survivorship curves among every elevation, probed a high demographic stability.
EFECTO DEL GRADIENTE ALTITUDINAL SOBRE ASPECTOS AUTOECOLóGICOS DE ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) EN EL PáRAMO EL INFIERNILLO (NARI O-COLOMBIA) THE EFFECT OF THE ALTITUDINAL GRADIENT ON AUTOECOLOGICAL FEATURES OF ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) IN THE PARAMO 'EL INFIERNILLO' (NARI O-COLOMBIA)
Iván F. Benavides-Martínez,Diana L. Burbano-Martínez,Sandra M. Urbano-Apráez,María E. Solarte-Cruz
Actualidades Biológicas , 2007,
Abstract: Se estudió el efecto de la elevación sobre algunos aspectos autoecológicos de la especie Espeletia pycnophylla ssp. angelensis Cuatrec. (Asteraceae), tales como su estructura demográfica, densidad poblacional, patrón de distribución espacial, producción de estructuras reproductivas, morfometría de adultos y supervivencia, en un páramo seco del departamento de Nari o (Colombia). Las hipótesis propuestas por otros autores acerca del efecto lineal que la elevación produce sobre estas variables, fueron completamente rechazadas. La elevación induce un efecto coenoclínico sobre la densidad poblacional y ésta a su vez, se correlaciona negativamente con la producción de estructuras reproductivas y el tama o de los adultos, evidenciándose un efecto inequívoco del fenómeno de la densodependencia sobre el potencial biótico de la población. En la zona intermedia del gradiente, la densidad poblacional es máxima, pero los tama os corporales son reducidos, la producción de estructuras reproductivas es mínima y la probabilidad de que un juvenil alcance edades avanzadas es baja. Evidentemente, esta elevación intermedia estaría presentando condiciones ecológicas favorables para el establecimiento y supervivencia de plántulas, lo que a largo plazo conlleva a un aumento de la densidad poblacional. Se propone que las generalizaciones de otros autores acerca de la influencia de la elevación sobre la autoecología de estas plantas son inverosímiles y limitadas, ya que la historia particular de vida y disturbio del páramo y los aislamientos espaciales, ecológicos y genéticos, son factores explicativos que no pueden aislarse del contexto. Paralelamente, la población se ajustó al modelo demográfico logarítmico, revelando su temprano estado de regeneración frente a la última quema ocurrida en el 2003, y la similitud de las curvas de supervivencia entre todas las elevaciones, probó una alta estabilidad demográfica. Some autoecological features of Espeletia pycnophylla ssp. angelensis Cuatrec. such as its demographic structure, population density, spatial pattern of dispersion, production of reproductive structures, adult morphometry and survivorship, were studied in an altitudinal gradient on a dry paramo of Nari o (Colombia). Hypothesis proposed by other authors about a linear effect caused by the elevation on these variables were completely rejected. The elevation induces an ecoclinal effect on population density, and this density correlates negatively with both production of reproductive structures and adult sizes. These results elucidate an unequivocal effect of density-dependen
Pompilidae (Hymenoptera) de algunos municipios del centro y sur de Tamaulipas, México
HORTA-VEGA, Jorge Víctor;GARCíA-GUTIéRREZ, Mauricio Emanuel;BENAVIDES-MARTíNEZ, Martha Isabel;CORREA-SANDOVAL, Alfonso;
Acta zoológica mexicana , 2009,
Abstract: one hundred and two species and thirty two genera of the four subfamilies of pompilidae wasps, collected at localities of eight municipalities of tamaulipas, méxico were recorded. twenty one species of these are new records for the country meanwhile 88 species are new records for the state of tamaulipas. the most abundant species were aporus notabilis notabilis y episyron conterminus posterus. thirty three species are neotropical. the results suggest that others species will be present in this region of the country and therefore more studies must be necesary to make in order to know the richness of this group of wasps.
Detection and interpretation of cyclic patterns in coals from Los Cuervos Formation, Venezuela
Martínez S,Manuel; Garbán,Grony; Benavides,Alfonso; Escobar N,Marcos; Esteves,Iván;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2005,
Abstract: a total of 21 coal samples, belonging to los cuervos formation, were taken in villa páez, táchira state, venezuela, with the aim of establishing vertical variations in their geochemical parameters. the samples were subject to immediate (moisture, volatile matter, fixed carbon and ash), elemental (c, h, n, s) and petrographic analysis. it was found a significant correlation between sulfur and ash content in coals, with width of beds, and their location in each lithofacies (spearman correlation coefficient > 0.80): those in which coals are sporadic, the beds are thin, high in sulfur and ash. on the contrary, in lithofacies with abundant coal seams, these are of great thickness, clean (s < 0.7%) and ash low (< 6%). cyclostratigraphic analysis of the sequence allowed the identification of a cycle of 72 m wavelength, and other two cycles of higher frequency but lower power, of wavelength of 11 and 5 m. these values are in agreement with milankovitch?s cycles of short excentricity (123 ky) and orbital precession (18 ky). lithofacies and geochemical changes in coals match with the main cycle of 72 m.
Polimorfismos del gen del receptor de vitamina D y riesgo de fractura de cadera en la mujer adulta mayor de la Región del Bío Bío
Quevedo L,Iván; Martínez B,Milka; Castillo N,Marcelo; Rivera F,Nancy;
Revista médica de Chile , 2008, DOI: 10.4067/S0034-98872008000400008
Abstract: background: osteoporotic hip fractures are devastating events in older women. there is a genetic modulation of bone phenotypic parameters including bone density (bmd) and bone fragility fractures. vitamin d receptor (vdr) gene polymorphisms explain a small part of the genetic influence on bmd, whereas their effect on fractures remains uncertain. aim: to examine the contributions of vdr genotypes to the susceptibility to hip fracture in elderly chilean women. patients and methods: we recruited 126 women (67 with fractures and 59 without) from bio-bio region, chile, aged 65 to 94 years. genotyping for bsm-l, apa-1, taq-1 and fok-1 vdr polymorphisms was performed using polymerase chain reaction methods. all hip fractures were confirmed by x-ray. results: the alíele frequencies were 0.49 for b, 0.57 for a, 0.60 for t and 0.65 for f in the bsm-l, apa-1, taq-1 and fok-1 polymorphisms respectively. the prevalence of these vdr gene polymorphisms in women with fractures were 16% bb, 69% bb, 15% bb for bsm-l; 30% aa, 46% aa, 14% aa for apa-1; 17% tt, 34 tt, 8% tt for taq-1 and 43%ff, 41% ff, 16% ff for fok-1. all vdr genotype frequencies did not differ from hardy- weinberg expectations. alíele or genotype frequencies did not differ between women with or without fractures. these results did not change when analysis was adjusted by age weight, height or gynecologic history. conclusions: the genotype frequencies of the vdr polymorphisms are in accordance with the frequencies of other hispanic and caucasian populations. our results suggest that vdr polymorphisms are not associated with the risk of hip fracture in older women of this region of southern chile
Polimorfismos del gen del receptor de vitamina D y riesgo de fractura de cadera en la mujer adulta mayor de la Región del Bío Bío Vitamin D receptor gene polymorphisms and risk of hip fracture in Chilean elderly women
Iván Quevedo L,Milka Martínez B,Marcelo Castillo N,Nancy Rivera F
Revista médica de Chile , 2008,
Abstract: Background: Osteoporotic hip fractures are devastating events in older women. There is a genetic modulation of bone phenotypic parameters including bone density (BMD) and bone fragility fractures. Vitamin D receptor (VDR) gene polymorphisms explain a small part of the genetic influence on BMD, whereas their effect on fractures remains uncertain. Aim: To examine the contributions of VDR genotypes to the susceptibility to hip fracture in elderly Chilean women. Patients and methods: We recruited 126 women (67 with fractures and 59 without) from Bio-Bio Region, Chile, aged 65 to 94 years. Genotyping for Bsm-l, Apa-1, Taq-1 and Fok-1 VDR polymorphisms was performed using polymerase chain reaction methods. All hip fractures were confirmed by X-ray. Results: The alíele frequencies were 0.49 for B, 0.57 for A, 0.60 for T and 0.65 for F in the Bsm-l, Apa-1, Taq-1 and Fok-1 polymorphisms respectively. The prevalence of these VDR gene polymorphisms in women with fractures were 16% BB, 69% Bb, 15% bb for Bsm-l; 30% AA, 46% Aa, 14% aa for Apa-1; 17% TT, 34 Tt, 8% tt for Taq-1 and 43%FF, 41% Ff, 16% ff for Fok-1. All VDR genotype frequencies did not differ from Hardy- Weinberg expectations. Alíele or genotype frequencies did not differ between women with or without fractures. These results did not change when analysis was adjusted by age weight, height or gynecologic history. Conclusions: The genotype frequencies of the VDR polymorphisms are in accordance with the frequencies of other Hispanic and Caucasian populations. Our results suggest that VDR polymorphisms are not associated with the risk of hip fracture in older women of this Region of Southern Chile
Test de estimulación intraarterial selectiva con calcio en el diagnóstico de localización de insulinomas: Casos clínicos
Martínez O,Darío; Silva Q,Guillermo; Solís O,Iván; Toloza H,Jorge; Benavides C,Carlos; Hamilton S,James; Osorio G,Fernando; I?iguez V,Germán; Soto I,Néstor;
Revista médica de Chile , 2004, DOI: 10.4067/S0034-98872004000100011
Abstract: insulinoma is the most common neuroendocrine tumor. its clinical manifestations are frequently confounded with neuropsychiatric symptoms, and definitive diagnosis can be delayed for a long time. these tumors are usually small, of less than 2 cm. thus, their preoperative localization is difficult. we report two patients with a clinical diagnosis of insulinoma, in whom the preoperative imaging study was negative. both fulfilled diagnostic criteria, with high serum insulin levels in the presence of a blood glucose of less than 45 mg/dl. the imaging study, including abdominal computed tomography and pancreatic endoscopic ultrasonography did not disclose the location of the tumor. a pancreatic angiography with selective stimulation with intra arterial calcium and venous sampling for insulin measurements, was performed in both patients. this test allowed the exact localization of the tumors and their successful excision. a review of other localization diagnostic tests is done (rev méd chile 2004; 132: 71-5).
‘Si tu non delinquiris’. Conflictividad en torno a la esclavitud en la Barcelona tardomedieval
Armenteros Martínez, Iván
Anuario de Estudios Medievales , 2008,
Abstract: This article considers the phenomenon of slavery as a conflict which confronts the individuals’ deprivation of liberty to their desire to achieve it, and treats the life experience of the slave and the freedperson from the moment of capture to that of death. The life of the slave, as well as that of the freedperson, is affected by various circumstances that provoke diverse problems affecting them directly or indirectly. Slaves suffer not only the conflict of the absence of liberty; they must also confront the acquisition of a new culture in a continual process of social adaptation that, ironically, reaches its critical point upon the entry into free society. During this journey, which oscillates between the poles of integration and rejection, individuals enslaved and subsequently emancipated can complete a process of positive adaptation, construct an alternative identity with which to bear their situation, or express their rejection through the assumption of clearly conflictive behaviors and attitudes. El fenómeno de la esclavitud puede considerarse como un conflicto en que el individuo debe hacer frente a la privación de libertad en oposición al anhelo de alcanzarla. El presente artículo recorre, desde este punto de vista, la experiencia vital del esclavo y del liberto desde su captura hasta su muerte. La vida del esclavo, pero también la del liberto, se encuentran comprometidas por una serie de circunstancias que provocan diversas problemáticas en las que los esclavos pueden verse involucrados directa e indirectamente. El esclavo no solo sufre el conflicto de la ausencia de la libertad, sino que debe superar también la aprehensión de una nueva cultura en un proceso continuo de adaptación social que, contradictoriamente, alcanza un punto crítico al ingresar en la sociedad libre. En este camino, que oscila entre los polos de la integración y el rechazo, el individuo esclavizado y posteriormente liberado puede culminar un proceso de adaptación positiva, construir una identidad alternativa con la que sobrellevar su situación, o expresar su rechazo mediante la asunción de conductas y actitudes claramente conflictivas.
Descenso ponderal y calidad de vida mediante la cirugía de Bypass gástrico con y sin anillo de calibración
AWAD F,WILLIAM; GARAY M,ALVARO; MARTíNEZ B,CRISTIAN; O?ATE M,VíCTOR; TURU K,IVáN; YARMUCH G,JULIO;
Revista chilena de cirugía , 2008, DOI: 10.4067/S0718-40262008000100005
Abstract: background: in gastric bypass, the diameter of gastrojejunal anastomosis may increase with time. it is not clear if a higher weight reduction can be achieved if a ring is added to the pouch. aim: to compare the results of gastric bypass with and without the addition of a ring. material and methods: prospective study of patients subjected to gastric bypass using capella and fobi technique. in a group of 244 patients (201 women), operated in one surgical center, a 6 cm ring was attached around the gastric pouch. in 194 patients (163 women) operated in other two centers, the ring was not used. patients were followed for 36 months. excess weight loss (ewl) and quality of life using baros ii score were evaluated in both groups. results: ewl at 24 months were 80.8 + 17 and 69.6 + 19% in groups with and without ring, respectively (p < 0.05). the figures at 36 months were 81+16 and 71.9 + 14%, respectively (p <0.05). strictures of thegastrojejunal anastomosis were observed in 12 patients without ring (6.1%) and in 2 patients with ring (0.8%). patients with ring had higher rates of disphagia. quality of life scores were similar in both groups. conclusions: patients with banded bypass had a higher weight loss but a higher frequency of disphagia. patients without band had a higher frequency of gastrojejunal anastomosis strictures
Rese a de "La locura ecocida. Ecosofía psicoanalítica" de Tamayo, Luis
Germán Iván Martínez
Convergencia , 2011,
Abstract:
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