12,901 research outputs found
Changes in Human Capital and Wage Inequality in Mexico
Over the last two decades Mexico has witnessed a significant increase in wage inequality, typically attributed to the increase in relative demand for skilled labor. Over this period the educational achievements and their distribution across the labor force have also changed substantially. In this paper we analyze the impact of changes in human capital on wage inequality in Mexico. We focus our analysis on decomposing (1) the level of inequality in any given year and (2) change in inequality over time, into observable (e.g. age, education, occupation, etc.) and unobservable differences across workers. The main findings of this paper are: unobservable factors (within group inequality) account for most of the inequality in any given year. Among the observable factors human capital emerges as the most important variables in explaining the level of, and changes in, inequality
Changes in Human Capital and Wage Inequality in Mexico
Over the last two decades Mexico has witnessed a significant increase in wage inequality, typically attributed to the increase in relative demand for skilled labor. Over this period the educational achievements and their distribution across the labor force have also changed substantially. In this paper we analyze the impact of changes in human capital on wage inequality in Mexico. We focus our analysis on decomposing (1) the level of inequality in any given year and (2) change in inequality over time, into observable (e.g. age, education, occupation, etc.) and unobservable differences across workers. The main findings of this paper are: unobservable factors (within group inequality) account for most of the inequality in any given year. Among the observable factors human capital emerges as the most important variables in explaining the level of, and changes in, inequality
Slow dynamics in the 3--D gonihedric model
We study dynamical aspects of three--dimensional gonihedric spins by using
Monte--Carlo methods. The interest of this family of models (parametrized by
one self-avoidance parameter ) lies in their capability to show
remarkably slow dynamics and seemingly glassy behaviour below a certain
temperature without the need of introducing disorder of any kind. We
consider first a hamiltonian that takes into account only a four--spin term
(), where a first order phase transition is well established. By
studying the relaxation properties at low temperatures we confirm that the
model exhibits two distinct regimes. For , with long lived
metastability and a supercooled phase, the approach to equilibrium is well
described by a stretched exponential. For the dynamics appears to be
logarithmic. We provide an accurate determination of . We also determine
the evolution of particularly long lived configurations. Next, we consider the
case , where the plaquette term is absent and the gonihedric action
consists in a ferromagnetic Ising with fine-tuned next-to-nearest neighbour
interactions. This model exhibits a second order phase transition. The
consideration of the relaxation time for configurations in the cold phase
reveals the presence of slow dynamics and glassy behaviour for any .
Type II aging features are exhibited by this model.Comment: 13 pages, 12 figure
Lepton Flavour Violation in Unified Models with U(1)-Family Symmetries
Lepton flavour non-conserving processes are examined in the context of
unified models with U(1)-family symmetries which reproduce successfully the
low-energy hierarchy of the fermion mass spectrum and the Kobayashi - Maskawa
mixing. These models usually imply mixing effects in the supersymmetric scalar
sector. We construct the fermion and scalar mass matrices in two viable models,
and calculate the mixing effects on the , and
rare decays. The relevant constraints on the sparticle
mass spectrum as well as the role of various MSSM parameters are discussed.Comment: 14 pages, 1 figure included in the ps file, uses epsfig.st
Generalized Additive Modelling of Mixed Distribution Markov Models with Application to Melbourne's Rainfall.
We consider modelling time series using a generalized additive model with first- order Markov structure and mixed transition density having a discrete component at zero and a continuous component with positive sample space. Such models have application, for example, in modelling daily occurrence and intensity of rainfall, and in modelling the number and size of insurance claims. We show how these methods extend the usual sinusoidal seasonal assumption in standard chain- dependent models by assuming a general smooth pattern of occurrence and intensity over time. These models can be fitted using standard statistical software. The methods of Grunwald and Jones (1998) can be used to combine these separate occurrence and intensity models into a single model for amount. We use 36 years of rainfall data from Melbourne, Australia, as a vehicle of illustration, and use the models to investigate the effect of the El Nino phenomenon on Melbourne's rainfall.Time Series ; Econometric Models ; Mixed Distribution Markov Models
Loop transfer matrix and gonihedric loop diffusion
We study a class of statistical systems which simulate 3D gonihedric system
on euclidean lattice. We have found the exact partition function of the
3D-model and the corresponding critical indices analysing the transfer matrix
which describes the propagation of loops on a lattice. The
connection between 3D gonihedric system and 2D-Ising model is clearly seen.Comment: 14 pages, Late
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Oxygen isotope composition of the primitive Achondrites
Primitive achondrites provide a record of the earliest stages of asteroidal melting. A detailed study of their oxygen isotope variation shows that these meteorites retain significant levels of primary oxygen isotope heterogeneity
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