Cultura organizacional en estructuras en red : el caso de la mina Uchucchacua

La miner?a es el principal rubro de exportaciones del pa?s, siendo un sector con altas ventajas competitivas considerando los inmensos recursos mineros existentes. En el caso de la plata, nuestro pa?ses el primer productor y la mina Uchucchacua es una de las principales productoras en el mundo. Paradojicamente, el sector minero atraviesa por un momento cr?tico en nuestro pa?s, caracterizado por los conflictos sociales que giran en torno de una supuesta falta de aporte al desarrollo, contaminaci?n del medioambiente, desconocimiento de las costumbres de las comunidades campesinas e incumplimiento de la normatividad vigente. En este especial entorno, las empresas mineras buscan adoptar estrategias que incrementen sus vol?menes de producci?n y reduzcan sus costos, a efecto de aprovechar el alto precio que registran los minerales met?licos.Considerando el contexto descrito, se propone un modelo te?rico nuevo que comprenda la influencia de la cultura organizacional en la administraci?n estrat?gica, con un enfoque que considere la estructura organizacional en red aplicado al sector minero

Modifiable risk factors for RA: prevention, better than cure?

Objective. To perform a meta-synthesis of the evidence for modifiable lifestyle risk factors for inflammatory polyarthritis (IP) and RA

Genome-wide association analysis of dementia and its clinical endophenotypes reveal novel loci associated with Alzheimer's disease and three causality networks: The GR@ACE project

INTRODUCTION: Large variability among Alzheimer's disease (AD) cases might impact genetic discoveries and complicate dissection of underlying biological pathways. METHODS: Genome Research at Fundacio ACE (GR@ACE) is a genome-wide study of dementia and its clinical endophenotypes, defined based on AD's clinical certainty and vascular burden. We assessed the impact of known AD loci across endophenotypes to generate loci categories. We incorporated gene coexpression data and conducted pathway analysis per category. Finally, to evaluate the effect of heterogeneity in genetic studies, GR@ACE series were meta-analyzed with additional genome-wide association study data sets. RESULTS: We classified known AD loci into three categories, which might reflect the disease clinical heterogeneity. Vascular processes were only detected as a causal mechanism in probable AD. The meta-analysis strategy revealed the ANKRD31-rs4704171 and NDUFAF6-rs10098778 and confirmed SCIMP-rs7225151 and CD33-rs3865444. DISCUSSION: The regulation of vasculature is a prominent causal component of probable AD. GR@ACE meta-analysis revealed novel AD genetic signals, strongly driven by the presence of clinical heterogeneity in the AD series

Umbrales de acci?n para el control qu?mico de la mosca del chile dulce Neosilba sp. (Diptera: Lonchaeidae)

Tesis (M. Sc) -- CATIE, Turrialba (Costa Rica), 1989El estudio se realiz? en el Centro Agron?mico Tropical de Investigaci?n y Ense?anza (CATIE), Turrialba, Costa Rica. En el cultivo de chile dulce (Capsicum annuum L.) se evaluaron cinco tratamientos: tres umbrales de acci?n, la aplicaci?n semanal del insecticida acefato y un testigo absoluto (sin aplicaci?n de acefato) para el manejo de la mosca del chile dulce, Neosilba sp. Se contaron los frutos ca?dos y se midi? el efecto que tuvieron los tratamientos sobre el rendimiento de chile dulce de primera, segunda y tercera clase. El menor promedio de frutos ca?dos fue de 0,304, que corresponde a las 16 aplicaciones semanales de acefato el mayor promedio de frutos ca?dos fue de 1.066, que corresponde al tratamiento sin aplicaci?n de acefato. Con las aplicaciones de acefato basadas en los umbrales de acci?n se redujo el n?mero de frutos ca?dos, comparado con el tratamiento sin aplicaci?n de acefato. Asimismo, cuando se compar? el testigo y los umbrales de acci?n con la aplicaci?n semanal de acefato, ?ste redujo significativamente el n?mero de frutos ca?dos. No existieron diferencias de rendimientos de frutos de primera y segunda clase, ni ganancia econ?mica para los tratamientos. Por lo tanto, en funci?n del rendimiento de chile dulce de primera y segunda clase y de los costos del manejo de Neosilba sp, parece no ser conveniente aplicar plaguicidas en el control de la mosca del chile

Evaluation of a generalized regression artificial neural network for extending cadmium’s working calibration range in graphite furnace atomic absorption spectrometry

Evaluation of a generalized regression artificial neural network for extending cadmium’s working calibration range in graphite furnace atomic absorption spectrometry. (Hernández C., Edwin A.; Rivas E., Francklin I., Ávila G., Rita M.) Abstract Abstract A generalized regression artificial neural network (GRANN) was developed and evaluated for modeling cadmium's nonlinear calibration curve in order to extend its upper concentration limit from 4.0 mg L ¯¹ up to 22.0 mg L ¯¹. This type of neural network presents important advantages over the more popular backpropagation counterpart which are worth exploiting in analytical applications, namely, (1) a smaller number of variables have to be optimized, with the subsequent reduction in ''development hassle''; and, (2) shorter development times, thanks to the fact that the adjustment of the weights (the artificial synapses) is a non-iterative, one-pass process. A backpropagation artificial neural network (BPANN), a second-order polynomial, and some less frequently employed polynomial and exponential functions (e.g., Gaussian, Lorentzian, and Boltzmann), were also evaluated for comparison purposes. The quality of the fit of the various models, assessed by calculating the root mean square of the percentage deviations, was as follows: GRANN > Boltzmann > second-order polynomial > BPANN > Gauss > Lorentz. The accuracy and precision of the models were further estimated through the determination of cadmium in the certified reference material ''Trace Metals in Drinking Water'' (High Purity Standards, Lot No. 490915), which has a cadmium certified concentration (12.00 ± 0.06 mg L¯¹) that lies in the nonlinear regime of the calibration curve. Only the models generated by the GRANN and BPANN accurately predicted the concentrations of a series of solutions, prepared by serial dilution of the CRM, with cadmium concentrations below and above the maximum linear calibration limit (4.0 mg L¯¹). Extension of the working range by using the proposed methodology represents an attractive alternative from the analytical point of view, since it results in less specimen manipulation and consequently reduced contamination risks without compromising either the accuracy or the precision of the analyses. The implementation of artificial neural networks also helps to reduce the trialand-error task of looking for the right mathematical model from among the many possibilities currently available in the various scientific and statistic software packages. Artículo publicado en: Anal Bioanal Chem (2005) 381: 788-794 DOI 10.1007/[email protected]@[email protected] monográfic

Aportes para el an?lisis de ecosistemas fluviales: una visi?n desde ambientes ribere?os

P?g. 109-127En este documento se muestran los alcances y las reflexiones obtenidas durante el curso ?Ecolog?a y manejo de ecosistemas: lecciones desde ambientes Ribere?os?, desarrollado en la Universidad del Tolima en septiembre de 2006. El curso cont? con la participaci?n de varios estudiantes de la Maestr?a en Ciencias Biol?gicas y de la Maestr?a en Planificaci?n y manejo de cuencas hidrogr?ficas de la Universidad del Tolima. Se pretende dar una visi?n de los elementos b?sicos para el an?lisis de ecosistemas ribere?os utilizando como herramienta las discusiones realizadas en el curso, los an?lisis de los resultados de proyectos llevados a cabo por el Grupo de Investigaci?n en Zoolog?a (612) y la revisi?n de literatura cient?fica pertinente. La propuesta pretende, adem?s, reflejar la necesidad de reconocer la importancia de zonas de amortiguaci?n en la interfaz suelo-agua en un ecosistema de gran relevancia no solo para estudios de biodiversidad sino tambi?n de restauraci?n ecol?gica en ambientes dulciacu?colas de Colombia.Abstract This document summarizes discussions from the workshop on ?Ecology and Ecosystem Management: lessons from Riparian Environments? held at the Faculty of Sciences, University of Tolima (Ibagu?, Colombia) on September 2006. A diverse group of several master students (Biological sciences and Planning and management of basins), natural resource managers, and university professors convened to discuss the functional role of riparian/ stream-river zones. The main objective of this reflection document is to shown the basic elements for the riparian ecosystem analyses helped with the discussions during the course, results from research projects carried out by Grupo de Investigaci?n en Zoolog?a (GIZ) and the revision of current and pertinent scientific literature. Beside, in this proposal we pretend to project riparian zones as a key component for future biodiversity and ecological restoration studies, on freshwater ecosystems along Colombia country