Technology diffusion and its effects on social inequalities

We develop a dynamic general-equilibrium framework in which growth is driven by skill-biased technology diffusion. The model incorporates leisure–labor decisions and human capital accumulation through education. We are able to reproduce the trends in income inequality and labor and skills supplies observed in the United States between 1969 and 1996. The paper also provides an explanation for why more individuals invest in human capital when the investment premium is going down, and why the skill-premium goes up when the skills supply is increasing.

Changes in the storage and sink of carbon dioxide in subsurface atmospheres controlled by climate-driven processes: the case of the Ojo Guareña karst system

A comprehensive environmental monitoring program was conducted in the Ojo Guareña cave system (Spain), one of the longest cave systems in Europe, to assess the magnitude of the spatiotemporal changes in carbon dioxide gas (CO2) in the cave–soil–atmosphere profile. The key climate-driven processes involved in gas exchange, primarily gas diffusion and cave ventilation due to advective forces, were characterized. The spatial distributions of both processes were described through measurements of CO2 and its carbon isotopic signal (δ13C[CO2]) from exterior, soil and cave air samples analyzed by cavity ring-down spectroscopy (CRDS). The trigger mechanisms of air advection (temperature or air density differences or barometric imbalances) were controlled by continuous logging systems. Radon monitoring was also used to characterize the changing airflow that results in a predictable seasonal or daily pattern of CO2 concentrations and its carbon isotopic signal. Large daily oscillations of CO2 levels, ranging from 680 to 1900 ppm day−1 on average, were registered during the daily oscillations of the exterior air temperature around the cave air temperature. These daily variations in CO2 concentration were unobservable once the outside air temperature was continuously below the cave temperature and a prevailing advective-renewal of cave air was established, such that the daily-averaged concentrations of CO2 reached minimum values close to atmospheric background. The daily pulses of CO2 and other tracer gases such as radon (222Rn) were smoothed in the inner cave locations, where fluctuation of both gases was primarily correlated with medium-term changes in air pressure. A pooled analysis of these data provided evidence that atmospheric air that is inhaled into dynamically ventilated caves can then return to the lower troposphere as CO2-rich cave air.

Las TIC al servicio del conocimiento avanzado multilingüe: la Biblioteca Digital Plurilingüe del Mediterráneo-IVITRA

Este estudio analiza la importancia de las TIC al servicio de las bibliotecas en general y, en concreto, el potencial de las bibliotecas digitales. En este trabajo se reflexiona sobre la importancia de las bibliotecas digitales no sólo como repositorios de contenidos, sino también como centros de creación de conocimiento. Se reflexiona sobre la importancia de la constitución de bibliotecas digitales especializadas en áreas culturales relacionadas y sobre el hecho de que sean multilingües, a fin de preservar los contenidos en sus lenguas originales, al tiempo que debe trabajarse con la traducción multilingüe (de y a muchas lenguas) como herramienta fundamental para la mejora de la difusión y conocimiento del patrimonio que se contiene en tales bibliotecas. En este sentido se explican las características de la Biblioteca Digital Plurilingüe del Mediterráneo-IVITRA.

Procedure for calculating the chloride diffusion coefficient and surface concentration from a profile having a maximum beyond the concrete surface

Chlorides induce local corrosion in the steel reinforcements when reaching the bar surface. The measurement of the rate of ingress of these ions, is made by mathematically fitting the so called “error function equation” into the chloride concentration profile, obtaining so the diffusion coefficient and the chloride concentration at the concrete surface. However, the chloride profiles do not always follow Fick’s law by having the maximum concentration at the concrete surface, but often the profile shows a maximum concentration more in the interior, which indicates a different composition and performance of the most external concrete layer with respect to the internal zones. The paper presents a procedure prepared during the time of the RILEM TC 178-TMC: “Testing and modeling chloride penetration in concrete”, which suggests neglecting the external layer where the chloride concentration increases and using the maximum as an “apparent” surface concentration, called C max and to fit the error function equation into the decreasing concentration profile towards the interior. The prediction of evolution should be made also from the maximum.