Unemployment history and frictional wage dispersion in search models of the labor market

This thesis studies the inability of search models to match both observed labor market flows and the empirical wage distribution. I show that a known feature of the labor market, that unemployment hurts workers' wages, has an important effect on workers' search behavior, and explains why we observe that similar workers are paid different wages. The first chapter reviews the relevant literature. I begin by describing the findings in Hornstein, Krusell and Violante (2011) that baseline search models struggle to generate significant wage dispersion, the so-called frictional wage dispersion puzzle. Further, search models face a trade-off between matching the cross-sectional wage distribution and matching the cyclical volatility of unemployment and vacancies. The chapter reviews the unemployment volatility puzzle and explains this trade-off. Given that the thesis introduces the loss of human capital during unemployment, the chapter ends with a review of the related empirical literature. Chapter 2 studies wage dispersion among identical workers in a random matching search model in which workers lose human capital during unemployment. Wage dispersion increases, as workers accept lower wages to avoid long unemployment spells. I show that the model is an important improvement over baseline search models. The model with unemployment history explains between a third and half of the observed residual wage dispersion. In Chapter 3 I add on-the-job search to the model with unemployment history. Workers accept lower wages because they keep the option of searching for better paying jobs. Wage dispersion increases significantly. The model accounts for all of the residual wage dispersion. The model also generates substantial wage dispersion even for high values of non-market time. The chapter thus addresses the trade-off between explaining frictional wage dispersion and the cyclical behavior of unemployment

Wage inequality: A structural decomposition

The objective of this paper is to study why some workers are paid more than others. To do so we construct and quantitatively assess an equilibrium search model with on-the-job search, general human capital accumulation and two sided heterogeneity. In the model workers differ in abilities and firms differ in their productivities. The model generates a simple (log) wage variance decomposition that is used to measure the importance of firm and worker productivity differentials, frictional wage dispersion and workers' sorting dynamics. We calibrate the model using a sample of young workers from the UK. We show that heterogeneity among firms generates great deal of wage inequality. Among low skilled workers job ladder effects are small, most of the impact of experience on wages is due to learning-by-doing. High skilled workers are much more mobile. Job ladder effects have sizeable impact

A pivotal role for interleuking-4 in Atorvastatin-associated neuroprotection in rat brain.

noInflammatory changes, characterized by an increase in pro-inflammatory cytokine production and up-regulation of the corresponding signaling pathways, have been described in the brains of aged rats and rats treated with the potent immune modulatory molecule lipopolysaccharide (LPS). These changes have been coupled with a deficit in long-term potentiation (LTP) in hippocampus. The evidence suggests that anti-inflammatory agents, which attenuate the LPS-induced and age-associated increase in hippocampal interleukin-1ß (IL-1ß) concentration, lead to restoration of LTP. Here we report that atorvastatin, a member of the family of agents that act as inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, exerts powerful anti-inflammatory effects in brain and that these effects are mediated by IL-4 and independent of its cholesterol-lowering actions. Treatment of rats with atorvastatin increased IL-4 concentration in hippocampal tissue prepared from LPS-treated and aged rats and abrogated the age-related and LPS-induced increases in pro-inflammatory cytokines, interferon-¿ (IFN¿) and IL-1ß, and the accompanying deficit in LTP. The effect of atorvastatin on the LPS-induced increases in IFN¿ and IL-1ß was absent in tissue prepared from IL-4¿/¿ mice. The increase in IL-1ß in LPS-treated and aged rats is associated with increased microglial activation, assessed by analysis of major histocompatibility complex II expression, and the evidence suggests that IFN¿ may trigger this activation. We propose that the primary effect of atorvastatin is to increase IL-4, which antagonizes the effects of IFN¿, the associated increase in microglial activation, and the subsequent cascade of events

An exploratory multivariate statistical analysis to assess urban diversity

Understanding diversity in complex urban systems is fundamental in facing current and future sustainability challenges. In this article, we apply an exploratory multivariate statistical analysis (i.e., Principal Component Analysis (PCA) and Multiple Factor Analysis (MFA)) to an urban system’s abstraction of the city’s functioning. Specifically, we relate the environmental, economical, and social characters of the city in a multivariate system of indicators by collecting measurements of those variables at the district scale. Statistical methods are applied to reduce the dimensionality of the multivariate dataset, such that, hidden relationships between the districts of the city are exposed. The methodology has been mainly designed to display diversity, being understood as differentiated attributes of the districts in their dimensionally-reduced description, and to measure it with Euclidean distances. Differentiated characters and distinctive functions of districts are identifiable in the exploratory analysis of a case study of Barcelona (Spain). The distances allow for the identification of clustered districts, as well as those that are separated, exemplifying dissimilarity. Moreover, the temporal dependency of the dataset reveals information about the district’s differentiation or homogenization trends between 2003 and 2015