Global debt : the impact on our lives.

Explica las causas y consecuencias de la deuda en los países en desarrollo y cómo su futuro está, de forma inextricable, vinculada a las políticas del mundo desarrollado. También, se evalúan los efectos profundamente destructivos del problema tanto para los países como para los individuos y, plantea posibles soluciones a largo plazo. Los hechos y debates expuestos desde diferentes puntos de vista muestran la complejidad del tema pero ayudan al lector a formarse una opinión personal al respecto.

Racism : the impact on our lives.

Por todo el mundo, la gente se enfrenta al prejuicio, al abuso y a la persecución por tener una cultura, un idioma y un modo de vida diferentes que les señala como miembros de un grupo étnico particular. Se investiga la historia del odio racista y se estudian las experiencias actuales de los inmigrantes, refugiados, solicitantes de asilo y miembros de minorías étnicas que son blanco del racismo, así como, el surgimiento de organizaciones neofascistas. Por último, se pregunta qué puede hacerse para curar estas divisiones en la sociedad.

Ontological beliefs and their impact on teaching elementary geometry. 'Creencias ontológicas y su impacto en la enseñanza de la geometría elemental'.

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Sensitivity of large-scale atmospheric analyses to humidity observations and its impact on the global water cycle and tropical and extratropical weather systems in ERA40

Reanalysis data obtained from data assimilation are increasingly used for diagnostic studies of the general circulation of the atmosphere, for the validation of modelling experiments and for estimating energy and water fluxes between the Earth surface and the atmosphere. Because fluxes are not specifically observed, but determined by the data assimilation system, they are not only influenced by the utilized observations but also by model physics and dynamics and by the assimilation method. In order to better understand the relative importance of humidity observations for the determination of the hydrological cycle, in this paper we describe an assimilation experiment using the ERA40 reanalysis system where all humidity data have been excluded from the observational data base. The surprising result is that the model, driven by the time evolution of wind, temperature and surface pressure, is able to almost completely reconstitute the large-scale hydrological cycle of the control assimilation without the use of any humidity data. In addition, analysis of the individual weather systems in the extratropics and tropics using an objective feature tracking analysis indicates that the humidity data have very little impact on these systems. We include a discussion of these results and possible consequences for the way moisture information is assimilated, as well as the potential consequences for the design of observing systems for climate monitoring. It is further suggested, with support from a simple assimilation study with another model, that model physics and dynamics play a decisive role for the hydrological cycle, stressing the need to better understand these aspects of model parametrization. .

Does speciation impact on Cu uptake by, and toxicity to, the earthworm Eisenia fetida?

Eisenia fetida were exposed to different concentrations (0.009, 0.049 and 0. 125 mg L-1) of Cu in an aqueous medium. Cu speciation was manipulated through the addition of different concentrations (0. 15, 0.35 and 50 mg L-1) of EDTA. Cu speciation (as labile and non-labile pools) was determined using Differential Pulse Anodic Stripping Voltammetry. Labile Cu includes free Cu ions together with weak inorganic Cu complexes and a small fraction of easily dissociable organic complexes. Metal uptake and earthworm mortality increased with total Cu concentration in the EDTA free solutions. In the presence of EDTA both metal uptake and mortality decreased. These experiments demonstrate that Cu speciation governs uptake and consequent toxicity of Cu to E. fetida. (c) 2007 Elsevier Masson SAS. All rights reserved.