Bivariate gamma-geometric law and its induced Levy process

In this article we introduce a three-parameter extension of the bivariate exponential-geometric (BEG) law (Kozubowski and Panorska, 2005) [4]. We refer to this new distribution as the bivariate gamma-geometric (BGG) law. A bivariate random vector (X, N) follows the BGG law if N has geometric distribution and X may be represented (in law) as a sum of N independent and identically distributed gamma variables, where these variables are independent of N. Statistical properties such as moment generation and characteristic functions, moments and a variance-covariance matrix are provided. The marginal and conditional laws are also studied. We show that BBG distribution is infinitely divisible, just as the BEG model is. Further, we provide alternative representations for the BGG distribution and show that it enjoys a geometric stability property. Maximum likelihood estimation and inference are discussed and a reparametrization is proposed in order to obtain orthogonality of the parameters. We present an application to a real data set where our model provides a better fit than the BEG model. Our bivariate distribution induces a bivariate Levy process with correlated gamma and negative binomial processes, which extends the bivariate Levy motion proposed by Kozubowski et al. (2008) [6]. The marginals of our Levy motion are a mixture of gamma and negative binomial processes and we named it BMixGNB motion. Basic properties such as stochastic self-similarity and the covariance matrix of the process are presented. The bivariate distribution at fixed time of our BMixGNB process is also studied and some results are derived, including a discussion about maximum likelihood estimation and inference. (C) 2012 Elsevier Inc. All rights reserved.

The Young Mother and the Labor Market

Introduction - The Centro de Orientacao ao Adolescente of Campinas (Southeastern Brazil) maintains a program to qualify economically disadvantaged adolescent students aged 15 to 18 years to enter the labor market. Objective - To understand life projects of teenagers who became mothers while participating in the program, in the period from 2003 to 2008, aiming to find the place of professional life in their life trajectory before and after motherhood. Method - Eight young mothers were interviewed, and a qualitative methodology was applied to the analysis of the interviews. Results - The trajectories of study and work were discontinued or adapted due to motherhood. Four young mothers completed high school and none had entered university. Three did not return to work and the rest had diverse work experiences. The reported difficulties to enter the labor market were: inadequate instruments to support the children's care, low income, lack of work experience, presence of small children and little educational background. Final Considerations - Teenage motherhood did not indicate the exclusion of educational or work projects but indicated adjustments and the need for a family and social support network. It was noted the need for public policies targeted at the inclusion of youths in the labor market and at support services such as nurseries. Also, the need for a change in gender relations was demonstrated, with greater equality of rights as a precondition for the inclusion of women, especially those who are mothers, in the labor market.

Migrant labor and wear-out in manual sugarcane harvesting in Sao Paulo, Brazil

The scope of this paper is to describe the work of manual sugarcane harvesters, assessing the nutritional behavior and body composition between the beginning and the end of the harvest. A descriptive longitudinal study was made of harvesters in Piracicaba, Sao Paulo, Brazil, who answered a socio-demographic questionnaire and authorized measurement of Body Mass Index, Body Fat Percentage and Arm Muscle Circumference at three stages. Creatine kinase on the skeletal isoform, C-reactive protein and plasma urea were measured at the end of the harvest. Thirty male migrant harvesters with ages ranging from 18 to 44 from the Northeast (Ceara) were assessed over a nine-month period. The workers suffered significant body fat and weight loss in the first half of the harvest. Eighteen workers had abnormal levels of creatine kinase and four - out of 24 who had donated blood - had altered urea levels. Sugarcane harvesting work causes weight and body fat loss and gains in the lean body mass index, which suffers wear-out when working on consecutive harvests. It can also cause changes in biochemical markers of chronic systemic inflammation. Further studies will make it possible to comprehend the relationships between stress, wear-out, labor longevity and health in sugarcane harvesting.

Migrant labor and wear-out in manual sugarcane harvesting in São Paulo, Brazil

The scope of this paper is to describe the work of manual sugarcane harvesters, assessing the nutritional behavior and body composition between the beginning and the end of the harvest. A descriptive longitudinal study was made of harvesters in Piracicaba, São Paulo, Brazil, who answered a socio-demographic questionnaire and authorized measurement of Body Mass Index, Body Fat Percentage and Arm Muscle Circumference at three stages. Creatine kinase on the skeletal isoform, C-reactive protein and plasma urea were measured at the end of the harvest. Thirty male migrant harvesters with ages ranging from 18 to 44 from the Northeast (Ceará) were assessed over a nine-month period. The workers suffered significant body fat and weight loss in the first half of the harvest. Eighteen workers had abnormal levels of creatine kinase and four - out of 24 who had donated blood - had altered urea levels. Sugarcane harvesting work causes weight and body fat loss and gains in the lean body mass index, which suffers wear-out when working on consecutive harvests. It can also cause changes in biochemical markers of chronic systemic inflammation. Further studies will make it possible to comprehend the relationships between stress, wear-out, labor longevity and health in sugarcane harvesting.