Weibull and generalised exponential overdispersion models with an application to ozone air pollution

We consider the problem of estimating the mean and variance of the time between occurrences of an event of interest (inter-occurrences times) where some forms of dependence between two consecutive time intervals are allowed. Two basic density functions are taken into account. They are the Weibull and the generalised exponential density functions. In order to capture the dependence between two consecutive inter-occurrences times, we assume that either the shape and/or the scale parameters of the two density functions are given by auto-regressive models. The expressions for the mean and variance of the inter-occurrences times are presented. The models are applied to the ozone data from two regions of Mexico City. The estimation of the parameters is performed using a Bayesian point of view via Markov chain Monte Carlo (MCMC) methods.     

Longitudinal Poisson modeling: an application for CD4 counting in HIV-infected patients

In this paper, we present different “frailty” models to analyze longitudinal data in the presence of covariates. These models incorporate the extra-Poisson variability and the possible correlation among the repeated counting data for each individual. Assuming a CD4 counting data set in HIV-infected patients, we develop a hierarchical Bayesian analysis considering the different proposed models and using Markov Chain Monte Carlo methods. We also discuss some Bayesian discrimination aspects for the choice of the best model.     

It Ought to Be a Crime: Criminalizing Human Rights Violations

In this article we propose that distinctions between human rights violations and violations of humanitarian law are substantively groundless. Human beings are entitled to live their lives with dignity and security, entitled to their freedoms. There remain, however, practical problems: human rights law and humanitarian law are distinct traditions with their own separate venues for judicatory review. They are also different in the popular imagination. We suggest ways that these distinctions can be dissolved.     

Rethinking Historical Reproductive Change: Insights from Longitudinal Data for a Spanish Town

A set of linked reproductive histories taken from the Spanish town of Aranjuez between 1871 and 1950 is used to address key issues regarding reproductive change during the demographic transition. These include the role of child survival as a stimulus for reproductive change, the use of stopping and/or spacing strategies to achieve reproductive goals, and the timing of change. Straightforward demographic measures are used and robust results are achieved. Initial strategies of fertility limitation are shown to exist but are inefficient, are mostly visible during the latter part of the reproductive period, are designed mostly to protect families from the effects of increases in child survival, and are based almost entirely on stopping behavior. As mortality decline accelerates, strategies become much more efficient, are visible at the outset of married life, include spacing behavior, and eventually lead to important declines in completed family size. The results of this study have implications for our understanding of the demographic transition both in historical Europe and in other regions of the world.     

The random intrinsic fast initial response of one-sided CUSUM charts

This article analyses the performance of a one-sided cumulative sum (CUSUM) chart that is initialized using a random starting point following the natural or intrinsic probability distribution of the CUSUM statistic. By definition, this probability distribution remains stable as the chart is used. The probability that the chart starts at zero according to this intrinsic distribution is always smaller than one, which confers on the chart a fast initial response feature. The article provides a fast and accurate algorithm to compute the in-control and out-of-control average run lengths and run-length probability distributions for one-sided CUSUM charts initialized using this random intrinsic fast initial response (RIFIR) scheme. The algorithm also computes the intrinsic distribution of the CUSUM statistic and random samples extracted from this distribution. Most importantly, no matter how the chart was initialized, if no level shifts and no alarms have occurred before time τ?>?0, the distribution of the run length remaining after τ is provided by this algorithm very accurately, provided that τ is not too small.     

Developing a Family Risk Assessment Tool in Adolescent Offenders: An Exploratory Study

The quality of family relations it is a relevant risk or protective factor in the adolescent criminal involvement, being the interplay between family and adolescent individual features, fundamental issues in the understanding of the adolescent risk and strengths assessment. This study aims to contribute to the validation of the Structured Interview of Family Assessment Risk (SIFAR) tool for the adolescent offenders’ family, based in nine family living items as risk factors and four protective factors. In an exploratory design, the structural consistency of SIFAR was analyzed using Cronbach’s alpha, mean inter-item correlation and exploratory factor analysis over risk items, because of the protective items dichotomous scale. The participants were a sample of 130 male adolescent delinquents detained in Portuguese facilities of the Directorate-general of Social Rehabilitation and Imprisonment, and their parents, paired analyzed. The SIFAR presents a structured professional judgment design for adolescent offender’s family protective and risk assessment. A reliability value of .75 was obtained for the risk items education, employment, housing/transport, legal problems, social dissonance, poverty, social net, social security and parenting, and an .79 was registered to the protective items family involvement, high discipline, low physical punishment and low parental stress. The risk items revealed a two-factor structure (social-economics and social conformity factors) explaining 48.15 % of the total variance. Results show the potential usefulness of SIFAR in the assessment the family protective and risk factors of adolescent offenders, presenting adequate structural reliability and construct validity. However further investigation it is necessary to the validation process of this tool.     

Parents’ education as a determinant of educational childcare time

We analyze the relationship between parents’ education and the time devoted to childcare activities, with a focus on activities aimed at increasing the child’s human capital. We use the sample of opposite-sex couples with children under age 18, from Spain (2002) and the UK (2000), included in the Multinational Time Use Study. By estimating a seemingly unrelated regressions tobit model, we find that mothers’ education is associated with an increase in the time devoted to educational childcare by fathers in both Spain and the UK, while it is associated with an increase in the time devoted to educational childcare by mothers in Spain. We also find that fathers’ education has no effect on the time devoted to educational childcare time by either parent. It seems that what really matters in determining the time devoted to educational childcare at the couple level is the educational level of the mother.     

Obesity and excess mortality among the elderly in the United States and Mexico

Increasing levels of obesity could compromise future gains in life expectancy in low-and high-income countries. Although excess mortality associated with obesity and, more generally, higher levels of body mass index (BMI) have been investigated in the United States, there is little research about the impact of obesity on mortality in Latin American countries, where very the rapid rate of growth of prevalence of obesity and overweight occur jointly with poor socioeconomic conditions. The aim of this article is to assess the magnitude of excess mortality due to obesity and overweight in Mexico and the United States. For this purpose, we take advantage of two comparable data sets: the Health and Retirement Study 2000 and 2004 for the United States, and the Mexican Health and Aging Study 2001 and 2003 for Mexico. We find higher excess mortality risks among obese and overweight individuals aged 60 and older in Mexico than in the United States. Yet, when analyzing excess mortality among different socioeconomic strata, we observe greater gaps by education in the United States than in Mexico. We also find that although the probability of experiencing obesity-related chronic diseases among individuals with high BMI is larger for the U. S. elderly, the relative risk of dying conditional on experiencing these diseases is higher in Mexico.     

Total training load may explain similar strength gains and muscle hypertrophy seen in aged rats submitted to resistance training and anabolic steroids

This study aimed to quantify training parameters and analyze the morphological response of aged muscles submitted to resistance training and anabolic steroids. Aged Wistar rats were divided into groups: C – initial control; CF – final control; CAS – control with anabolic steroid, RT – resistance training, and RTA – resistance training with anabolic steroid. Maximum carried load, absolute and relative loads increased significantly in RT and RTA. RTA demonstrated greater relative load than RT. Average total volume, total climbing volume, relative total volume, relative total climbing volume, and mean climbing volume were similar between groups RT and RTA. For soleus, CAS, RT, and RTA enlarged cross-sectional area of type I fibers and nuclear ratio. As for type II fibers, RTA was higher than C and CF. For plantaris, RT and RTA showed significant increases in myofibers type I compared to C and CF. For type II fibers, RTA showed a significant increase compared to C and CF. Regarding the nuclear ratio, RT and RTA showed a higher ratio than C, CF, and CAS. Our results demonstrated that both RT and RTA were not different among the analyzed morphological parameters. This fact can be explained by the absence of differences found in the training variables analyzed.