Population age structure and private consumption in Spain

In this paper we study the effect of population age distribution upon private consumption expenditure in Spain from 1964 to 1997 using aggregate data. We obtain four main results. First, changes in the population pyramid have substantial effects upon the behaviour of private consumption. Second, the pattern of the coefficients of the demographic variables is not consistent with the simplest version of the life cycle hypothesis. Third, we estimate the impact of the demographic transition upon consumption and find positive values associated with episodes in which the shares of groups of individuals with expenditure levels higher (lower) than the mean increased (decreased). Fourth, the results are robust to alternative specifications for the population age distribution.

Consumption and portfolio rules whit stochastic hyperbolic discounting

We extend the classic Merton (1969, 1971) problem that investigates the joint consumption-savings and portfolio-selection problem under capital risk by assuming sophisticated but time-inconsistent agents. We introduce stochastic hyperbolic preferences as in Harris and Laibson (2013) and find closed-form solutions for Merton's optimal consumption and portfolio selection problem in continuous time. We find that the portfolio rule remains identical to the time-consistent solution with power utility and no borrowing constraints. However,the marginal propensity to consume out of wealth is unambiguously greater than the time-consistent, exponential case and,importantly, it is also more responsive to changes in risk. These results suggest that hyperbolic discounting with sophisticated agents offers promise for contributing to explaining important aspects of asset market data.

Development of catalytic methane reforming systems integrating hydrogen selective PdCu membrane modules

En la presente tesis doctoral se ha estudiado la integración del proceso de producción de hidrógeno con su purificación mediante el empleo de membranas selectivas de hidrógeno. La producción de hidrógeno se realiza empleando catalizadores no convencionales de níquel soportado sobre magnesia y alúmina en un reactor catalítico. Se analiza la actividad de los catalizadores y la producción de hidrógeno mediante distintos procesos con metano como son la oxidación parcial catalítica (OPC), OPC húmeda y reformadoLa purificación de hidrógeno se realiza en un módulo provisto de una membrana selectiva de hidrógeno de PdCu depositado en un soporte poroso cerámico. Una vez optimizada su preparación mediante deposición no electrolítica se caracterizan. Para ello se determina su permeabilidad a distintas temperaturas y realizando ciclos térmicos en atmósferas inerte y de hidrógeno, que puede fragilizar el metal. Una vez preparados los catalizadores y las membranas se integran los dos sistemas y se determinan los parámetros de operación óptimos como la presión de la línea de alimentación y el caudal de gas de arrastre en el módulo de membrana. Ambos parámetros se optimizan para lograr la máxima recuperación de hidrógeno en el módulo de membrana. Por últimos se realizan ensayos completos de producción y purificación, que permiten observar el rendimiento del sistema y también el efecto que los compuestos de la mezcla compleja alimentada a las membranas tienen en su comportamiento. Para concluir la integración de procesos se realizan ensayos añadiendo azufre de forma que el sistema sea más similar al proceso real. Esto permite también analizar el efecto del azufre tanto en los catalizadores como en las membranas.

Cheese consumption and prevalence of overweight and obesity in a Basque adult population: a crosssectional study

[EN] Studies have reported a negative association between dairy product consumption and weight status. However, not as much research has focused on cheese; therefore, the aim of this study was to study the association between cheese intake and overweight and obesity in a representative Basque adult population. A food frequency questionnaire (FFQ) was obtained from a random sample of 1081 adults (530 males and 551 females, 17–96 years old). Cheese consumption data were expressed as g/1000 kcal/day. The prevalence of overweight/obesity was higher in men (55.1%) than in women (35.4%) (p50.001). Participants with low or moderate intake of fresh and processed cheese demonstrated a higher prevalence of excess weight, compared with those with higher consumption. The confounding variables selected in multivariate analysis were occupational status and age in both genders; and place of residence in men. In conclusion, negative associations were found between consumption of some types of cheese and overweight and obesity in this population.

Reutilización de escoria negra de acería como soporte en biofiltros para la eliminación de H2S del biogás.

[EN]Due to the limitations associated with fossil fuels it is necessary to promote energy sources that are renewable as well as eco-friendly, such as biogas generated in anaerobic digesters. The biogas, composed principally of methane and CO2, is the result of the biodegradation of organic matter under anaerobic conditions. Its use as fuel is limited by the presence of minority compounds such as hydrogen sulphide (H2S); therefore, its pre-treatment is necessary. Currently there are various technologies for the removal of H2S from a gas stream, but most of them are based on physic-chemical treatments which have a number of drawbacks as reactive consumption, generation of secondary flows, etc. Biofiltration has been used as an efficient and low cost alternative to conventional purification processes, and excellent results for the degradation of H2S have been obtained. However process can be limited due to the progressive ageing of the support material, along with the loss of nutrients and other specific characteristics necessary for the good development of biomass. The purpose of this project is to develop a mixed support consisting of a mixture of an organic material and an inorganic support for its application in the removal of the H2S from biogas. This support material helps to optimize the characteristics of the bed and extend its lifespan. The development of such material will contribute to the implementation of biofiltration for treating biogas from anaerobic digesters for its use as biofuel. The inorganic material used is electric arc furnace (EAF) black slag, a by-product generated in large quantities in the production of steel in the Basque Country. Although traditionally the slag has been used in civil engineering, its physicochemical characteristics make it suitable for reuse as a filter medium in biofiltration. The main conclusion drawn from the experimental results is that EAF black slag is a suitable co-packing material in organic biofilters treating H2S-polluted gaseous streams. High pollutant removal rates have been achieved during the whole experimental period. The removal capacity recorded in biofilters with less inorganic material was higher than in those with higher slag portion. Nevertheless, all the biofilters have shown a satisfactory response even at high inlet loads (48 g·m-3·h-1), where the RE has not decreased over 82%.