Labor Unions and the Distribution of Wages and Employment in South Africa

Labor unions are an important economic and political force in South Africa. Inequality in wage rates is among the largest in the world in South Africa, with African and white workers receiving wages that differ by a factor of five. The complex role of unions in closing and creating this wage gap is assessed in this paper. Union membership among Africa male workers is shown to be associated in 1993 with their receiving wages that are 145 percent higher than comparable nonunion workers in the bottom decile of the wage distribution, and 19 percent higher in the top decile of the wage distribution. Quantile regression estimates also indicate the returns to observed productive characteristics of workers, such as education and experience, are larger for nonunion than union workers. If the large union relative wage effect were reduced in half, we estimate employment of African youth, age 16-29, would increase by two percentage points, and their labor force participation rate would also increase substantially.Labor Unions, Wages and Employment, South Africa

Wage Premia for Education and Location, By Gender and Race in South Africa

Despite the lower quality of education provided Africans compared with whites in South Africa, the percentage wage gains associated with additional years of primary, secondary, and higher education are substantially larger for Africans than for whites in 1993, and they increase for both race groups at higher levels of education. The lower quantity (or political quotas) of education received by Africans than whites is a simple explanation for the wage structure documented in this paper. The other two racial groups, colored (mixed races) and Indians, occupy intermediate positions between whites and Africans in terms of both the quantity of education received and wage returns to those levels of education. As barriers to employment by race are dismantled in South Africa, wage differences between races are likely to diminish, while wage differences within race groups may well widen. Quantitative expansion of educational opportunities for nonwhites at the secondary and higher education levels seems to be overdue

Monte Carlo simulation of uncoupled continuous-time random walks yielding a stochastic solution of the space-time fractional diffusion equation

We present a numerical method for the Monte Carlo simulation of uncoupled continuous-time random walks with a Levy alpha-stable distribution of jumps in space and a Mittag-Leffler distribution of waiting times, and apply it to the stochastic solution of the Cauchy problem for a partial differential equation with fractional derivatives both in space and in time. The one-parameter Mittag-Leffler function is the natural survival probability leading to time-fractional diffusion equations. Transformation methods for Mittag-Leffler random variables were found later than the well-known transformation method by Chambers, Mallows, and Stuck for Levy alpha-stable random variables and so far have not received as much attention; nor have they been used together with the latter in spite of their mathematical relationship due to the geometric stability of the Mittag-Leffler distribution. Combining the two methods, we obtain an accurate approximation of space- and time-fractional diffusion processes almost as easy and fast to compute as for standard diffusion processes.Comment: 7 pages, 5 figures, 1 table. Presented at the Conference on Computing in Economics and Finance in Montreal, 14-16 June 2007; at the conference "Modelling anomalous diffusion and relaxation" in Jerusalem, 23-28 March 2008; et

Velocity and energy distributions in microcanonical ensembles of hard spheres

In a microcanonical ensemble (constant $NVE$, hard reflecting walls) and in a molecular dynamics ensemble (constant $NVE\mathbf{PG}$, periodic boundary conditions) with a number $N$ of smooth elastic hard spheres in a $d$-dimensional volume $V$ having a total energy $E$, a total momentum $\mathbf{P}$, and an overall center of mass position $\mathbf{G}$, the individual velocity components, velocity moduli, and energies have transformed beta distributions with different arguments and shape parameters depending on $d$, $N$, $E$, the boundary conditions, and possible symmetries in the initial conditions. This can be shown marginalizing the joint distribution of individual energies, which is a symmetric Dirichlet distribution. In the thermodynamic limit the beta distributions converge to gamma distributions with different arguments and shape or scale parameters, corresponding respectively to the Gaussian, i.e., Maxwell-Boltzmann, Maxwell, and Boltzmann or Boltzmann-Gibbs distribution. These analytical results agree with molecular dynamics and Monte Carlo simulations with different numbers of hard disks or spheres and hard reflecting walls or periodic boundary conditions. The agreement is perfect with our Monte Carlo algorithm, which acts only on velocities independently of positions with the collision versor sampled uniformly on a unit half sphere in $d$ dimensions, while slight deviations appear with our molecular dynamics simulations for the smallest values of $N$.Comment: 11 pages, 3 figure

Análise transcriptômica de pedúnculos de caju (Anacardium occidentale L.) durante o desenvolvimento em genótipos apresentando cores e firmezas diferentes.

Tese (Doutorado em Bioquímica Vegetal) Programa de Pós Graduação em Bioquímica - Universidade Federal do Ceará, Fortaleza, 2020. Orientador: Dr. José Hélio Cost

Autoimmunity Overlaps Primary Biliary Cirrhosis: a Not Straightforward Diagnosis

info:eu-repo/semantics/publishedVersio

Síndrome Hemolítico Urémico Atípico en Cuidados Intensivos: Caso Clínico de un Adulto

info:eu-repo/semantics/publishedVersio

Discovery of a Luminous Quasar in the Nearby Universe

In the course of the Pico dos Dias survey (PDS), we identified the stellar like object PDS456 at coordinates alpha = 17h 28m 19.796s, delta = -14deg 15' 55.87'' (epoch 2000), with a relatively nearby (z = 0.184) and bright (B = 14.69) quasar. Its position at Galactic coordinates l_II = 10.4deg, b_II = +11.2deg, near the bulge of the Galaxy, may explain why it was not detected before. The optical spectrum of PDS456 is typical of a luminous quasar, showing a broad (FWHM ~ 4000 km/s) H_\beta line, very intense FeII lines and a weak [OIII]\lambda5007 line. PDS456 is associated to the infrared source IRAS 17254-1413 with a 60 \mum infrared luminosity L_{60} = 3.8 x 10^{45} erg/s. The relatively flat slopes in the infrared (\alpha(25,60) = -0.33 and \alpha(12,25) = -0.78) and a flat power index in the optical (F_{\nu} \propto \nu^{-0.72}) may indicate a low dust content. A good match between the position of PDS456 and the position of the X-ray source RXS J172819.3-141600 implies an X-ray luminosity L_x = 2.8 x 10^{44} erg/s. The good correlation between the strength of the emission lines in the optical and the X-ray luminosity, as well as the steep optical to X-ray index estimated (\alpha_{ox} = -1.64) suggest that PDS456 is radio quiet. A radio survey previously performed in this region yields an upper limit for radio power at ~ 5 GHz of ~ 2.6 x 10^{30} erg/s/Hz. We estimate the Galactic reddening in this line-of-sight to be A_B \simeq 2.0, implying an absolute magnitude M_B = -26.7 (using H_0 = 75 km s^{-1} Mpc^{-1} and q_0 = 0). In the optical, PDS456 is therefore 1.3 times more luminous than 3C 273 and the most luminous quasar in the nearby (z \leq 0.3) Universe.Comment: 12 pages, LaTeX (aasms4.sty) + 3 figures; accepted for publication in the Astrophysical Journal Letter