No abstract

para las trece áreas metropolitanas de Colombia, en este trabajo se examina la hipótesis de segmentación del mercado laboral urbano en cada año del período 2001-2006. Se encuentra evidencia de segmentación entre empresas formales grandes y el resto (segmentación intrarregional o de escala), y entre Bogotá y las demás áreas metropolitanas (segmentación interregional).

El impacto de la infraestructura en el crecimiento económico colombiano: un enfoque smithiano Resumen: En este trabajo se propone una nueva forma de calcular el acervo infraestructural, el cual se compone de todos los activos durables de uso público, ya sean construidos por agentes privados o estatales. De esta forma, las regresiones del crecimiento económico para Colombia arrojan que no se puede descartar la hipótesis de rendimientos constantes a escala en el capital empresarial (agregado del capital fijo y el capital humano) y en la infraestructura. Se estima, además, que la elasticidad producto de la infraestructura es significativamente mayor que la del capital empresarial. Una vez se controla por la acumulación de los factores productivos, los principales determinantes del crecimiento (y la productividad) son la diversificación del sector industrial manufacturero, la capacidad de compra de la población y la tasa de homicidios. El enfoque smithiano del desarrollo económico es compatible con estos hallazgos. Finalmente, la descomposición del crecimiento económico nacional sugiere que este ha sido predominantemente extensivo.

In this work the influence of the number of bilayers was studied on the mechanical, tribological and electrochemical properties of multilayer coatings [TiN / TiCrN]n as a function of the number of bilayers n = 1, 25 and 50, deposited by magnetron sputtering. By Xray diffraction (XRD), a cubic crystal structure centered on the faces (FCC) was determined for all coatings and an increase in the compressive stresses that were generated during the deposition process was found by perfilometry; Atomic force microscopy (AFM) determined that by increasing the number of bilayers, the roughness decreased, due to an increase in the density of the system. By nanoindentation it was found that the hardness (H) and the modulus of elasticity (E) increased as the number of bilayers did. By Pin on disk a decrease in the coefficient of friction was observed as the number of bilayers was increased, which was related to the increase in hardness and the reduction of roughness. The results of EIS and Tafel for the electrochemical properties, determined that the corrosion rate decreased due to the fact that a greater barrier to the passage of the electrolyte towards the substrate is promoted when the number of bilayers increases.

We conducted an observational study to determine the prevalence of Entamoeba spp., in samples collected in a waste water treatment plant that provides water for agricultural irrigation. Samples were collected weekly over a period of 10 weeks at representative contamination stages from within the treatment plant. Protozoan identification was performed via light microscopy and culture. PCR amplification of small subunit rRNA gene sequences of E. histolytica/dispar/moshkovskii was performed in culture positive samples. Light microscopy revealed the presence of Entamoeba spp., in 70% (14/20) of the raw waste water samples and in 80% (8/10) of the treated water samples. PCR amplification after culture at both 24 and 37°C revealed that 100% (29/29) of the raw waste water samples and 78.6% (11/14) of the treated waste water were positive for E. moshkovskii. We report the first isolation of E. moshkovskii in Colombia, confirmed by PCR. Recent reports of E. moshkovskii pathogenic potential suggest this finding could constitute a public health risk for people exposed to this water.