Weighted Hardy spaces for the unit disc: approximation properties

In this paper we study basic properties of the weighted Hardy space for the unit disc with the weight function satisfying Muckenhoupt's (Aq) condition, and study related approximation problems (expansion, moment and interpolation) with respect to two incomplete systems of holomorphic functions in this space.

La Mayor dotación de capital humano y sus problemas de adaptación en el mercado de trabajo español, 1986-2005

Desde 1975 y sobre todo a partir de su incorporación a la Unión Europea en 1986, los cambios que se han producido en la estructura económica y productiva española han favorecido la convergencia de la mayoría de sus indicadores económicos con los de los países de la Unión. Sin embargo, no ha habido el mismo éxito por lo que se refiere al mercado de trabajo. Esta comunicación es, por una parte, el resultado de mi trabajo de investigación sobre la evolución de la educación superior y el mercado de trabajo en España durante las últimas cuatro décadas del último siglo y, por otra parte, el punto de partida de un estudio más profundo sobre las diferencias regionales en la correspondencia entre la oferta y la demanda de trabajo cualificado en España y en Europa. El objetivo de esta comunicación es comparar la evolución de los niveles educativos y de los principales indicadores del mercado de trabajo en España y en otros países europeos (Alemania, Francia, Grecia, Italia, Portugal y Reino Unido) desde 1986, año de incorporación de España a la Unión Europea, hasta la actualidad, para determinar los factores o mecanismos que influyen en el mercado de trabajo cualificado español y su difícil convergencia con los de otros países europeos.

Norm inequalities in multidimensional Lorentz spaces

In this paper we obtain necessary and sufficient conditions for double trigonometric series to belong to generalized Lorentz spaces, not symmetric in general. Estimates for the norms are given in terms of coefficients.

Variational inequalities in Hilbert spaces with measures and optimal stopping problems

We study the existence theory for parabolic variational inequalities in weighted L2 spaces with respect to excessive measures associated with a transition semigroup. We characterize the value function of optimal stopping problems for finite and infinite dimensional diffusions as a generalized solution of such a variational inequality. The weighted L2 setting allows us to cover some singular cases, such as optimal stopping for stochastic equations with degenerate diffusion coeficient. As an application of the theory, we consider the pricing of American-style contingent claims. Among others, we treat the cases of assets with stochastic volatility and with path-dependent payoffs.

Pareto-improving optimal capital and labor taxes

We show a standard model where the optimal tax reform is to cut labor taxes and leave capital taxes very high in the short and medium run. Only in the very long run would capital taxes be zero. Our model is a version of Chamley??s, with heterogeneous agents, without lump sum transfers, an upper bound on capital taxes, and a focus on Pareto improving plans. For our calibration labor taxes should be low for the first ten to twenty years, while capital taxes should be at their maximum. This policy ensures that all agents benefit from the tax reform and that capital grows quickly after when the reform begins. Therefore, the long run optimal tax mix is the opposite from the short and medium run tax mix. The initial labor tax cut is financed by deficits that lead to a positive long run level of government debt, reversing the standard prediction that government accumulates savings in models with optimal capital taxes. If labor supply is somewhat elastic benefits from tax reform are high and they can be shifted entirely to capitalists or workers by varying the length of the transition. With inelastic labor supply there is an increasing part of the equilibrium frontier, this means that the scope for benefitting the workers is limited and the total benefits from reforming taxes are much lower.

Label Space Reduction in All-Optical Label Switchiing Networks

Report for the scientific sojourn at the Department of Information Technology (INTEC) at the Ghent University, Belgium, from january to june 2007. All-Optical Label Swapping (AOLS) forms a key technology towards the implementation of All-Optical Packet Switching nodes (AOPS) for the future optical Internet. The capital expenditures of the deployment of AOLS increases with the size of the label spaces (i.e. the number of used labels), since a special optical device is needed for each recognized label on every node. Label space sizes are affected by the wayin which demands are routed. For instance, while shortest-path routing leads to the usage of fewer labels but high link utilization, minimum interference routing leads to the opposite. This project studies and proposes All-Optical Label Stacking (AOLStack), which is an extension of the AOLS architecture. AOLStack aims at reducing label spaces while easing the compromise with link utilization. In this project, an Integer Lineal Program is proposed with the objective of analyzing the softening of the aforementioned trade-off due to AOLStack. Furthermore, a heuristic aiming at finding good solutions in polynomial-time is proposed as well. Simulation results show that AOLStack either a) reduces the label spaces with a low increase in the link utilization or, similarly, b) uses better the residual bandwidth to decrease the number of labels even more.

On the boundedness on inhomogeneous Lipschitz spaces of fractional integrals, singular integrals and hypersingular integrals associated to non-doubling measures on metric spaces

In this paper we prove T1 type necessary and sufficient conditions for the boundedness on inhomogeneous Lipschitz spaces of fractional integrals and singular integrals defined on a measure metric space whose measure satisfies a n-dimensional growth. We also show that hypersingular integrals are bounded on these spaces.

Homotopy exponents for large H-Spaces

We show that H-spaces with finitely generated cohomology, as an algebra or as an algebra over the Steenrod algebra, have homotopy exponents at all primes. This provides a positive answer to a question of Stanley.

Predicting trabecular bone microdamage initiation and accumulation using a non-linear perfect damage model

Studies evaluating the mechanical behavior of the trabecular microstructure play an important role in our understanding of pathologies such as osteoporosis, and in increasing our understanding of bone fracture and bone adaptation. Understanding of such behavior in bone is important for predicting and providing early treatment of fractures. The objective of this study is to present a numerical model for studying the initiation and accumulation of trabecular bone microdamage in both the pre- and post-yield regions. A sub-region of human vertebral trabecular bone was analyzed using a uniformly loaded anatomically accurate microstructural three-dimensional finite element model. The evolution of trabecular bone microdamage was governed using a non-linear, modulus reduction, perfect damage approach derived from a generalized plasticity stress-strain law. The model introduced in this paper establishes a history of microdamage evolution in both the pre- and post-yield regions

Net spaces and boundedness of integral operators

In this paper we introduce new functional spaces which we call the net spaces. Using their properties, the necessary and sufficient conditions for the integral operators to be of strong or weak-type are obtained. The estimates of the norm of the convolution operator in weighted Lebesgue spaces are presented.

Convolution inequalities in Lorentz spaces

In this paper we study boundedness of the convolution operator in different Lorentz spaces. In particular, we obtain the limit case of the Young-O'Neil inequality in the classical Lorentz spaces. We also investigate the convolution operator in the weighted Lorentz spaces. Finally, norm inequalities for the potential operator are presented.

Entrepreneurial intention, cognitive social capital and culture: empirical anaylisis for Spain and Taiwan

The main purpose of this paper is building a research model to integrate the socioeconomic concept of social capital within intentional models of new firm creation. Nevertheless, some researchers have found cultural differences between countries and regions to have an effect on economic development. Therefore, a second objective of this study is exploring whether those cultural differences affect entrepreneurial cognitions. Research design and methodology: Two samples of last year university students from Spain and Taiwan are studied through an Entrepreneurial Intention Questionnaire (EIQ). Structural equation models (Partial Least Squares) are used to test the hypotheses. The possible existence of differences between both sub-samples is also empirically explored through a multigroup analysis. Main outcomes and results: The proposed model explains 54.5% of the variance in entrepreneurial intention. Besides, there are some significant differences between both subsamples that could be attributed to cultural diversity. Conclusions: This paper has shown the relevance of cognitive social capital in shaping individuals’ entrepreneurial intentions across different countries. Furthermore, it suggests that national culture could be shaping entrepreneurial perceptions, but not cognitive social capital. Therefore, both cognitive social capital and culture (made up essentially of values and beliefs), may act together to reinforce the entrepreneurial intention.

Portabilidad del capital humano y asimilación de los inmigrantes. Evidencia para España

La literatura sobre asimilación de los inmigrantes ha destacado la portabilidad imperfecta del capital humano acumulado por éstos en su país de origen (Chiswick, 1978; Friedberg, 2000). Ello explicaría la escasa asimilación en el momento de llegar al nuevo país, así como la gran brecha salarial inicial. Recientemente, una serie de trabajos (Chiswick y Miller, 2007 o Green, Kler y Leeves, 2007, entre otros) han abordado este tema desde la perspectiva de la sobreeducación. Enmarcado en esta literatura, el presente trabajo analiza la portabilidad del capital humano de los inmigrantes al mercado de trabajo español en función de su origen geográfico. Asimismo, trata de contrastar para el caso español las regularidades empíricas más destacables de dichos trabajos. Los resultados obtenidos señalan un distinto grado de transferibilidad del capital humano según origen geográfico, siendo superior la del capital humano acumulado en países de elevado desarrollo o de cultura e idioma próximos y menor la del procedente de países en desarrollo y culturas distantes. La evidencia es relativamente dispar para ambos componentes del capital humano: mientras que ello es especialmente claro para los estudios, resulta menos evidente para la experiencia. Se confirma, asimismo, para el caso español que los inmigrantes padecen una mayor sobreeducación, tanto en incidencia como en intensidad, y que ello implica una mayor penalización salarial relativa, con resultados siempre peores para inmigrantes del segundo grupo de países. A medida que los inmigrantes prolongan su estancia en España existe un proceso de asimilación, excepto para asiáticos y en algunas especificaciones tampoco para los procedentes del África subsahariana, si bien la velocidad de asimilación es notablemente lenta.

Una propuesta de evaluación de las externalidades de capital humano en la empresa

Empleando la encuesta de estructura salarial se plantea una propuesta de estimación de externalidades de capital humano intraempresa que permite relajar las restricciones introducidas por las especificaciones que la literatura empírica existente ha usado. En concreto, la metodología propuesta evalúa las externalidades de capital humano aprovechando al máximo la variabilidad en la muestra, al permitir que todos los coeficientes de las ecuaciones estimadas varíen con el nivel de capital humano del establecimiento, relajando la hipótesis implícita de linealidad entre el efecto de externalidad y el nivel educativo de los individuos.