Immigrants Responsiveness to Labor Market Conditions

Using data from the Spanish Labor Force Survey (Encuesta de Población Activa) from 1999 through 2004, we explore the role of regional employment opportunities in explaining the increasing immigrant flows of recent years despite the limited internal mobility on the part of natives. Subsequently, we investigate the policy question of whether immigration has helped reduced unemployment rate disparities across Spanish regions by attracting immigrant flows to regions offering better employment opportunities. Our results indicate that immigrants choose to reside in regions with larger employment rates and where their probability of finding a job is higher. In particular, and despite some differences depending on their origin, immigrants appear generally more responsive than their native counterparts to a higher likelihood of informal, self, or indefinite employment. More importantly, insofar the vast majority of immigrants locate in regions characterized by higher employment rates, immigration contributes to greasing the wheels of the Spanish labor market by narrowing regional unemployment rate disparities.

A comprehensive method for the elastic calculation of the two-point wheel-rail contact

This work shows the method developed to solve the wheel-rail contact problem via a look-up table with a three-dimensional elastic model. This method enables introduction of the two contact point effect on vehicle movement using three-dimensional analysis of surfaces including the influence of the angle of attack. This work presents several dynamic simulations and studies the impact that the introduction of the two contact points on three dimensions has on wear indexes and derailment risk against traditional bidimensional analysis. Furthermore, it studies advantages and disadvantages of using a look-up table against an on-line resolution of the problem.

Unlike Physical Exercise, Modified Environment Increases the Lifespan of SOD1(G93A) Mice However Both Conditions Induce Cellular Changes

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Viability Conditions for a Compartmentalized Protometabolic System: A Semi-Empirical Approach

In this work we attempt to find out the extent to which realistic prebiotic compartments, such as fatty acid vesicles, would constrain the chemical network dynamics that could have sustained a minimal form of metabolism. We combine experimental and simulation results to establish the conditions under which a reaction network with a catalytically closed organization (more specifically, an (M, R)-system) would overcome the potential problem of self-suffocation that arises from the limited accessibility of nutrients to its internal reaction domain. The relationship between the permeability of the membrane, the lifetime of the key catalysts and their efficiency (reaction rate enhancement) turns out to be critical. In particular, we show how permeability values constrain the characteristic time scale of the bounded protometabolic processes. From this concrete and illustrative example we finally extend the discussion to a wider evolutionary context.