Enforcement of Labor Regulation and Informality

Enforcement of labor regulations in the formal sector may drive workers to informality because they increase the costs of formal labor. But better compliance with mandated benefits makes it attractive to be a formal employee. We show that, in locations with frequent inspections workers pay for mandated benefits by receiving lower wages. Wage rigidity prevents downward adjustment at the bottom of the wage distribution. As a result, lower paid formal sector jobs become attractive to some informal workers, inducing them to want to move to the formal sector.labor regulation, informality

Bursts in discontinuous Aeolian saltation

Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of discontinuous flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the fluid threshold Shields number $\theta_c$. The time delay between each burst decreases on average with the increase of the Shields number until sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain discontinuous flux even below the fluid threshold

Friedmann cosmology with decaying vacuum density

Among the several proposals to solve the incompatibility between the observed small value of the cosmological constant and the huge value obtained by quantum field theories, we can find the idea of a decaying vacuum energy density, leading from high values at early times of universe evolution to the small value observed nowadays. In this paper we consider a variation law for the vacuum density recently proposed by Schutzhold on the basis of quantum field estimations in the curved, expanding background, characterized by a vacuum density proportional to the Hubble parameter. We show that, in the context of an isotropic and homogeneous, spatially flat model, the corresponding solutions retain the well established features of the standard cosmology, and, in addition, are in accordance with the observed cosmological parameters. Our scenario presents an initial phase dominated by radiation, followed by a dust era long enough to permit structure formation, and by an epoch dominated by the cosmological term, which tends asymptotically to a de Sitter universe. Taking the matter density equals to half of the vacuum energy density, as suggested by observation, we obtain a universe age given by Ht = 1.1, and a decelerating parameter equals to -1/2.Comment: Accepted for publication in General Relativity and Gravitatio

Bandlimited approximations to the truncated Gaussian and applications

In this paper we extend the theory of optimal approximations of functions $f: \R \to \R$ in the $L^1(\R)$-metric by entire functions of prescribed exponential type (bandlimited functions). We solve this problem for the truncated and the odd Gaussians using explicit integral representations and fine properties of truncated theta functions obtained via the maximum principle for the heat operator. As applications, we recover most of the previously known examples in the literature and further extend the class of truncated and odd functions for which this extremal problem can be solved, by integration on the free parameter and the use of tempered distribution arguments. This is the counterpart of the work \cite{CLV}, where the case of even functions is treated.Comment: to appear in Const. Appro

Obtaining pressure versus concentration phase diagrams in spin systems from Monte Carlo simulations

We propose an efficient procedure for determining phase diagrams of systems that are described by spin models. It consists of combining cluster algorithms with the method proposed by Sauerwein and de Oliveira where the grand canonical potential is obtained directly from the Monte Carlo simulation, without the necessity of performing numerical integrations. The cluster algorithm presented in this paper eliminates metastability in first order phase transitions allowing us to locate precisely the first-order transitions lines. We also produce a different technique for calculating the thermodynamic limit of quantities such as the magnetization whose infinite volume limit is not straightforward in first order phase transitions. As an application, we study the Andelman model for Langmuir monolayers made of chiral molecules that is equivalent to the Blume-Emery-Griffiths spin-1 model. We have obtained the phase diagrams in the case where the intermolecular forces favor interactions between enantiomers of the same type (homochiral interactions). In particular, we have determined diagrams in the surface pressure versus concentration plane which are more relevant from the experimental point of view and less usual in numerical studies

Globalization and inequality in Latin America

We survey the recent literature studying the effects of globalization on inequality in Latin America. Our focus is on research emerging from the late 2000s onward, with an emphasis on empirical work considering new mechanisms, studying new dimensions of inequality, and developing new methodologies to capture the many facets of globalization’s relationship to inequality. After summarizing both design-based and quantitative work in this area, we propose directions for future work. Our overarching recommendation is that researchers develop unifying frameworks to help synthesize the results of individual studies that focus on distinct aspects of globalization’s relationship to inequality

A Godel-Friedman cosmology?

Based on the mathematical similarity between the Friedman open metric and Godel's metric in the case of nearby distances, we investigate a new scenario for the Universe's evolution, where the present Friedman universe originates from a primordial Godel universe by a phase transition during which the cosmological constant vanishes. Using Hubble's constant and the present matter density as input, we show that the radius and density of the primordial Godel universe are close, in order of magnitude, to the present values, and that the time of expansion coincides with the age of the Universe in the standard Friedman model. In addition, the conservation of angular momentum provides, in this context, a possible origin for the rotation of galaxies, leading to a relation between the masses and spins corroborated by observational data.Comment: Extended version, accepted for publication in Physical Review

Trade Reform and Regional Dynamics: Evidence From 25 Years of Brazilian Matched Employer-Employee Data

We empirically study the dynamics of labor market adjustment following the Brazilian trade reform of the 1990s. We use variation in industry-specific tariff cuts interacted with initial regional industry mix to measure trade-induced local labor demand shocks, and then examine regional and individual labor market responses to those one-time shocks over two decades. Contrary to conventional wisdom, we do not find that the impact of local shocks is dissipated over time through wage-equalizing migration. Instead, we find steadily growing effects of local shocks on regional formal sector wages and employment for 20 years. This finding can be rationalized in a simple equilibrium model with two complementary factors of production, labor and industry-specific factors such as capital, that adjust slowly and imperfectly to shocks. Next, we document rich margins of adjustment induced by the trade reform at the regional and individual level. Workers initially employed in harder hit regions face continuously deteriorating formal labor market outcomes relative to workers employed in less affected regions, and this gap persists even 20 years after the beginning of trade liberalization. Negative local trade shocks induce workers to shift out of the formal tradable sector and into the formal nontradable sector. Non-employment strongly increases in harder-hit regions in the medium run, but in the longer run, non-employed workers eventually find re-employment in the informal sector. Working age population does not react to these local shocks, but formal sector net migration does, consistent with the relative decline of the formal sector and growth of the informal sector in adversely affected regions

Spontaneous emergence of spatial patterns ina a predator-prey model

We present studies for an individual based model of three interacting populations whose individuals are mobile in a 2D-lattice. We focus on the pattern formation in the spatial distributions of the populations. Also relevant is the relationship between pattern formation and features of the populations' time series. Our model displays travelling waves solutions, clustering and uniform distributions, all related to the parameters values. We also observed that the regeneration rate, the parameter associated to the primary level of trophic chain, the plants, regulated the presence of predators, as well as the type of spatial configuration.Comment: 17 pages and 15 figure