Capital humano y desigualdad en España: 1985-1996

En el período 1985-1996 la desigualdad de la renta en España se redujo de forma notable, en claro contraste con lo sucedido en otros países avanzados. En este trabajo se profundiza en el impacto que sobre esta reducción en la desigualdad ha ejercido la redistribución del stock de capital humano, uno de los factores que aparecen como más relevantes para explicar tanto la distribución de la renta como sus modificaciones. Las conclusiones obtenidas sugieren que aproximadamente un tercio de la reducción en la desigualdad que se ha producido entre los dos años extremos contemplados (1985 frente a 1996) se debe al comportamiento del capital humano. Otros factores tales como el tamaño de la familia o la participación de ambos cónyuges en el mercado de trabajo, han actuado en el mismo sentido. Finalmente, un elevado porcentaje de mejora en la distribución permanece por explicar y deberá ser objeto de investigaciones futuras.

North-South convergence and the allocation of CO2 emissions

We postulate a two-region world, comprised of North (calibrated after the US) and South(calibrated after China). Our optimization results show the compatibility of the following threedesiderata:(1) Global CO2 emissions follow a conservative path that leads to the stabilizationof concentrations at 450 ppm.(2) North and South converge to a path of sustained growth at 1% per year (28.2%per generation) in 2075.(3) During the transition to the steady state, North also grows at 1% per year whileSouth s rates of growth are markedly higher.The transition paths require a drastic reduction of the share of emissions allocated to North,large investments in knowledge, both in North and South, as well as very large investments ineducation in South. Surprisingly, in order to sustain North s utility growth rate, some output mustbe transferred from South to North during the transition.Although undoubtedly subject to many caveats, our results support a degree of optimism byproviding prima facie evidence of the possibility of tackling climate change in a way that is fairboth across generations and across regions while allowing for positive rates of humandevelopment.

Maximum likelihood Linear Programming Data Fusion for Speaker Recognition

Biometric system performance can be improved by means of data fusion. Several kinds of information can be fused in order to obtain a more accurate classification (identification or verification) of an input sample. In this paper we present a method for computing the weights in a weighted sum fusion for score combinations, by means of a likelihood model. The maximum likelihood estimation is set as a linear programming problem. The scores are derived from a GMM classifier working on a different feature extractor. Our experimental results assesed the robustness of the system in front a changes on time (different sessions) and robustness in front a change of microphone. The improvements obtained were significantly better (error bars of two standard deviations) than a uniform weighted sum or a uniform weighted product or the best single classifier. The proposed method scales computationaly with the number of scores to be fussioned as the simplex method for linear programming.

Comiat al professor Lluis A. Santaló

Article de comiat al matemàtic gironí Lluís Antoni Santaló i Sors, que va morir a Buenos Aires el 22 de novembre de 2001