Representaciones sobre los jóvenes colombianos en el programa de televisión La Sub 30

El presente trabajo da cuenta de las representaciones y expresiones que sobre los jóvenes colombianos se construyen y difunden a través de la telerevista La Sub 30, y que tienen como fundamento las intencionalidades de un discurso gubernamental que se gesta desde el Plan Nacional de Cultura y Convivencia del Ministerio de Cultura, a partir del año 2006. En el trabajo se analizan los sentidos que se configuran en el programa y que emergen como representaciones de los jóvenes: lo generacional, lo artístico y lo productivo. Se toma como objeto de estudio ocho emisiones de la telerevista La Sub 30, emitidos a comienzos del primer semestre de 2009. Se opta por una metodología cualitativa de enfoque hermenéutico orientada con aportes teóricos de Stuart Hall, Scott Lash, John Urry, Nikolas Rose y Norman Fairclough. El corpus de análisis está compuesto por fragmentos de discurso verbal de los directores programa, sus presentadores y los jóvenes invitados, los cuales dialogan y se discuten sobre los sentidos que subyacen en ellos. Los resultados se organizan en categorías que permiten evidenciar referentes que caracterizan las representaciones y expresiones de los jóvenes colombianos en la telerevista La Sub 30.

Density dependence and phenological mismatch: consequences for growth and survival of sub-arctic nesting Canada Geese

The extent to which species are plastic in the timing of their reproductive events relative to phenology suggests how climate change might affect their demography. An ecological mismatch between the timing of hatch for avian species and the peak availability in quality and quantity of forage for rapidly growing offspring might ultimately affect recruitment to the breeding population unless individuals can adjust the timing of breeding to adapt to changing phenology. We evaluated effects of goose density, hatch timing relative to forage plant phenology, and weather indices on annual growth of pre-fledging Canada geese (Branta canadensis) from 1993-2010 at Akimiski Island, Nunavut. We found effects of both density and hatch timing relative to forage plant phenology; the earlier that eggs hatched relative to forage plant phenology, the larger the mean gosling size near fledging. Goslings were smallest in years when hatch was latest relative to forage plant phenology, and when local abundance of breeding adults was highest. We found no evidence for a trend in relative hatch timing, but it was apparent that in early springs, Canada geese tended to hatch later relative to vegetation phenology, suggesting that geese were not always able to adjust the timing of nesting as rapidly as vegetation phenology was advanced. Analyses using forage biomass information revealed a positive relationship between gosling size and per capita biomass availability, suggesting a causal mechanism for the density effect. The effects of weather parameters explained additional variation in mean annual gosling size, although total June and July rainfall had a small additive effect on gosling size. Modelling of annual first-year survival probability using mean annual gosling size as an annual covariate revealed a positive relationship, suggesting that reduced gosling growth negatively impacts recruitment.

Use of fused airborne scanning laser altimetry and digital map data for urban flood modelling

Flood modelling of urban areas is still at an early stage, partly because until recently topographic data of sufficiently high resolution and accuracy have been lacking in urban areas. However, Digital Surface Models (DSMs) generated from airborne scanning laser altimetry (LiDAR) having sub-metre spatial resolution have now become available, and these are able to represent the complexities of urban topography. The paper describes the development of a LiDAR post-processor for urban flood modelling based on the fusion of LiDAR and digital map data. The map data are used in conjunction with LiDAR data to identify different object types in urban areas, though pattern recognition techniques are also employed. Post-processing produces a Digital Terrain Model (DTM) for use as model bathymetry, and also a friction parameter map for use in estimating spatially-distributed friction coefficients. In vegetated areas, friction is estimated from LiDAR-derived vegetation height, and (unlike most vegetation removal software) the method copes with short vegetation less than ~1m high, which may occupy a substantial fraction of even an urban floodplain. The DTM and friction parameter map may also be used to help to generate an unstructured mesh of a vegetated urban floodplain for use by a 2D finite element model. The mesh is decomposed to reflect floodplain features having different frictional properties to their surroundings, including urban features such as buildings and roads as well as taller vegetation features such as trees and hedges. This allows a more accurate estimation of local friction. The method produces a substantial node density due to the small dimensions of many urban features.