Papers by juan carlos barrera segura
INGENIERÍA Y COMPETITIVIDAD, 2011
Se analizaron las teleconexiones lineales entre el fenómeno ENOS y los caudales mensuales del Río... more Se analizaron las teleconexiones lineales entre el fenómeno ENOS y los caudales mensuales del Río Cauca (Valle del Cauca-Colombia), utilizando dos técnicas estadísticas multivariadas: el análisis de funciones ortogonales empíricas (FOES) y el análisis de correlación canónica (ACC). Se ajustaron modelos ARMAX, para predecir los caudales, utilizando las primeras componentes principales y coeficientes canónicos de las variables macroclimáticas, como variables auxiliares en los modelos de caudal; obteniéndose mejoras en la predicción. Lo anterior indica que las variables macroclimáticas aportaron información adicional. El FPE (error final de predicción) se redujo en un 9.44% en promedio, usando la primera componente principal de las variables macroclimáticas como variable auxiliar. Mientras, el FPE se redujo en un 13.35% en promedio, usando el primer coeficiente canónico de las variables macroclimáticas como variable auxiliar. Los modelos presentaron buen ajuste, por lo que pueden ser u...
Universitas Médica, 2013
El feocromocitoma es un tumor originario del tejido cromafin, cuya sintomatología está relacionad... more El feocromocitoma es un tumor originario del tejido cromafin, cuya sintomatología está relacionada con el exceso de catecolaminas. La incidencia en la población general es de 1-8 casos/millón. Presentamos el caso de una mujer de 52 años de edad con feocromocitoma maligno. Es la primera vez que se realiza en el Hospital San Rafael de Tunja una adrenalectomía por vía laparoscópica.
Ciencia y Sociedad, 2011
En el presente documento se ha optado por abordar al proceso de trabajo desde dos ópticas o ejes ... more En el presente documento se ha optado por abordar al proceso de trabajo desde dos ópticas o ejes principales a saber: la dominación y la violencia. Íntimamente ligados como un dueto para el sometimiento laboral. El enfoque usado es siempre critico, con el objeto de ampliar el que se tiene de manera ordinaria al abordarlo, alejándose de posturas de corte economicista y managerial. Se hace una recuperación teórica de acercamientos críticos, alejados de la ortodoxia, se incluye en este trabajo la reflexión, cuyo desarrollo permite afirmar por una parte que los dos ejes mencionados, están presentes en el fenómeno organizacional. Por la otra, que su efecto laboral y social es importante, por lo que deben ser considerados en estudios futuros.
HortScience, 1995
The effects of stage of microspore development, cold pretreatment, and growth regulators on the e... more The effects of stage of microspore development, cold pretreatment, and growth regulators on the embryogenic response of anthers from service tree (Sorbus domestica L.) are reported. Callus proliferation required the presence of growth regulators in the culture medium, best results being obtained with combinations of auxins and BA. Microspore embryogenesis was only induced when anthers containing tetrads or uninucleate pollen were cultured on BA-supplemented media containing IBA or IAA. A cold pretreatment before anther culture elicited a significant decrease in callus formation and inhibited embryogenesis. Chemical names used: benzyladenine (BA), indole-3-butyric acid (IBA), indole-3-acetic acid (IAA).
HortScience, 1997
A protocol for in vitro propagation in yellow passionfruit (Passiflora edulis F. flavicarpa Deg) ... more A protocol for in vitro propagation in yellow passionfruit (Passiflora edulis F. flavicarpa Deg) has been developed. Shoot apices from aseptically grown seedlings were used as initial explants. Multiple shoot formation was obtained by placing the explants on solidified Murashige and Skoog medium containing BA. Regenerated shoots were rooted on media without growth regulators. Following conventional procedures, plantlets were transferred to soil with more than 90% success. Chemical name used: N-(phenylmethyl)-lH-purin-6-amine (BA).
HortScience, 2010
Successful propagation of Nerium oleander L. (oleander) was achieved by in vitro methods. Shoot c... more Successful propagation of Nerium oleander L. (oleander) was achieved by in vitro methods. Shoot cultures were initiated from seedlings of wild-growing plants and from shoot apices of adult plants belonging to the commercial cultivars Splendens Giganteum, Revanche, and Alsace. Axillary shoot breaking from shoot tips excised from these cultures required the presence of either 6-benzylaminopurine (BA) or thidiazuron (TDZ). The higher number of axillary shoots from juvenile material was obtained by culturing shoot tips from BA-pretreated material derived from seedlings on a modified Schenk and Hildebrandt medium (SHM) supplemented with BA or TDZ (average of 3.9 shoots per explant with a mean length of 10.4 mm) and when the media were supplemented with 8.8 μM TDZ (average of 3.5 shoots per explant with a mean length of 7.3 mm) or 4.4 μM BA (average of 3.3 shoots per explant with a mean length of 12.3 mm). Among cultivars, cv. Revanche showed best shoot proliferation rates, especially whe...
Journal of the American Society for Horticultural Science, 1992
A protocol for in vitro propagation in flowering ash (Fraxinus ornus L.) has been developed. Shoo... more A protocol for in vitro propagation in flowering ash (Fraxinus ornus L.) has been developed. Shoot apices or nodal segments from aseptically grown seedings or shoot apices from adult trees were used as initial explants. Highest shoot multiplication rates were obtained when the explants were cultured for 30 days in liquid Rugini induction medium supplemented with BA followed by 30 days on solidified Rugini multiplication medium without growth regulators. Regenerated shoots were rooted on Heller medium containing auxins alone or in combination with BA. Rooting percentages up to 71% (juvenile material) or 50% (adult material) were obtained in the presence of NAA and BA, and were not improved by treating the basal end of the shoots with concentrated NAA solutions. Following conventional procedures, regenerated plants were transferred to soil with more than 80% success. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (BA); 1-naphthaleneacetic acid (NAA).
Mathematical biosciences, Jan 4, 2018
The moment of intervention is a key question in harvest programmes and is currently generating an... more The moment of intervention is a key question in harvest programmes and is currently generating an increasing interest. However, little is known about its effect on the population stability. This lack of knowledge is greater in the case of global stability, which is always desirable as it allows to predict the fate of populations regardless of the initial size. Here we use a discrete-time equation to model the dynamics of populations harvested at any time during the reproductive season. We study the effect of the time of intervention on the global stability of populations governed by the Ricker model, which is one of the most relevant models in discrete-time population dynamics. We prove that harvest timing never has a negative effect on the global stability of these populations, extending recent results in the literature. We also study the effect of delayed harvesting on the constancy stability of the controlled populations.
PLOS ONE, 2017
Adaptive limiter control (ALC) and adaptive threshold harvesting (ATH) are two related control me... more Adaptive limiter control (ALC) and adaptive threshold harvesting (ATH) are two related control methods that have been shown to stabilize fluctuating populations. Large variations in population abundance can threaten the constancy and the persistence stability of ecological populations, which may impede the success and efficiency of managing natural resources. Here, we consider population models that include biological mechanisms characteristic for causing extinctions on the one hand and pest outbreaks on the other hand. These models include Allee effects and the impact of natural enemies (as is typical of forest defoliating insects). We study the impacts of noise and different levels of biological parameters in three extinction and two outbreak scenarios. Our results show that ALC and ATH have an effect on extinction and outbreak risks only for sufficiently large control intensities. Moreover, there is a clear disparity between the two control methods: in the extinction scenarios, ALC can be effective and ATH can be counterproductive, whereas in the outbreak scenarios the situation is reversed, with ATH being effective and ALC being potentially counterproductive.
Agora U.S.B., 2012
La investigación “Estado de los derechos fundamentales de las personas privadas de l a l i b e r ... more La investigación “Estado de los derechos fundamentales de las personas privadas de l a l i b e r t a d e n l o s e s t a b l e c imi e n t o spenitenciarios y carcelarios de Medellín” se ocupó de definir el contexto histórico y actual de los establecimientos de privación de la libertad en el municipio de Medellín. De a c u e r d o c o n e l l o s e d e s c r i b e n l o s establecimientos que han existido en el municipio y los que actualmente existen para la privación de la libertad de miembros de la Policía Nacional, el Ejército Nacional y civiles adultos hombres y mujeres. Como unamanera de evidenciar que la privación de la libertad es discriminada en diversos tipos de establecimientos y que aquellos que se c o n s t r u y e r o n c o m o l a s o l u c i ó n a grandísimos problemas penitenciarios y carcelarios simplemente entran a hacer parte del problema.
Heterodoxos Reformadores Y Marginados En La Antiguedad Clasica 1991 Isbn 84 7405 660 8 Pags 107 136, 1991
Acompanar En La Fragilidad Relatos De Profesionales De La Salud 2010 Isbn 978 84 285 3620 2 Pags 355 367, 2010
Riesgos De Inundacion Y Regimen Urbanistico Del Suelo Recopilacion De Ponencias De Las Jornadas Sobre Riesgos De Inundacion Y Regimen Urbanistico Del Suelo Celebradas En El Salon De Actos Del Colegio De Ingenieros De Caminos Los Dias 3 Y 4 De Noviembre De 1999 2000 Pags 301 314, 2000
Historia De La Filosofia Antigua 1997 Isbn 84 8164 154 5 Pags 201 216, 1997
Acompanar En La Fragilidad Relatos De Profesionales De La Salud 2010 Isbn 978 84 285 3620 2 Pags 179 190, 2010
Revista Geografica De America Central, 1992
Tierras De Leon Revista De La Diputacion Provincial, 1961
Ejercito De Tierra Espanol, 2006
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Papers by juan carlos barrera segura