Raúl Díaz

It is often assumed that daytime patterns of ecosystem carbon assimilation are mostly driven by direct physiological responses to exogenous environmental cues. Under limited environmental variability, little variation in carbon assimilation should thus be expected unless endogenous plant controls on carbon assimilation, which regulate photosynthesis in time, are active. We evaluated this assumption with eddy flux data, and we selected periods when net ecosystem exchange was decoupled from environmental variability in seven sites from highly contrasting biomes across a 74° latitudinal gradient over a total of 36 site-years. Under relatively constant conditions of light, temperature, and other environmental factors, significant diurnal NEE oscillations were observed at six sites, where daily NEE variation was between 20% and 90% of that under variable environmental conditions. These results are consistent with fluctuations driven by the circadian clock and other endogenous processes. Our results open a promising avenue of research for a more complete understanding of ecosystem fluxes that integrates from cellular to ecosystem processes. © 2012 Blackwell Publishing Ltd.

El presente artículo da cuenta de las actitudes hacia los inmigrantes entre los estudiantes de educación secundaria de edades comprendidas entre 12 y 13 años en Extremadura, España. Los datos proceden de una investigación financiada por el Gobierno Regional de Extremadura y en ellos se muestran ¿mediante análisis de contenido y utilización de citas textuales¿ los componentes estructurales que alimentan las actitudes positivas y/o negativas hacia la inmigración y los inmigrantes por parte de los adolescentes extremeños, en la medida en que son plenamente representativos en cuanto a actitudes y valores del conjunto nacional. El análisis nos permite establecer un modelo actitudinal frente a la inmigración que deberá ser probado en futuras investigaciones

The distinctive security features of the Spanish electronic national identity card, known as Documento Nacional de Identidad electrónico, allow us to propose the usage of this cryptographic smart card in an authentication framework that can be used during the registration and login phases of internet services where the validation of the user’s age and real identity are key elements, as it is the case for example of the so-called social networks. Using this mechanism with NFC-capable devices, the identity and age of the potential user can be determined, allowing or denying the access to the service based on that information.