Validation of Multimedia Models Assessing Exposure to PAHs—The SOLEX Study

Polluted soils have become a public health problem. While population exposure to soil pollutants is generally quantified using multimedia models, their estimations have not been validated, and studies that attempted to do so are scarce. The objective of the SOLEX study was to compare the predictions of pyrene exposure levels (converted into 1 hydroxypyrene) computed by several models with the results of urinary 1-hydropyrene (1-HOP) assays among 110 employees working at three sites polluted during their past use as manufactured gas plants. Four models were used: AERIS (Canada), CalTOX (California, USA), CLEA (UK), and HESP (The Netherlands). Three occupational exposure scenarios--with office, mixed, and outdoor workers--were constructed, based upon job activities during two measurement campaigns, one in winter and one in summer. The exposure levels estimated by the four models could differ markedly (from 7 up to 80 times) according to the exposure scenario. Also, the predominant exposure routes differed according to the model (direct soil ingestion for HESP and CalTOX, inhalation for AERIS, and dermal absorption for CLEA). The predictions of CalTOX are consistent with the 1-HOP measurements for all the scenarios. For HESP, the consistency is observed for the scenarios, office and mixed, for which the pyrene level in the soil is low. AERIS and CLEA yield results that are systematically above the 1-HOP measurements. This study confirms that validation of the models is crucial and points out to the need to proceed to assess components of the models that are the most influential using appropriate statistical analysis in combination with true field data.     

SEPARATION, WEAK EXOGENEITY, AND P-T DECOMPOSITION IN COINTEGRATED VAR SYSTEMS WITH COMMON FEATURES

The aim of this paper is to study the concept of separability in multiple nonstationary time series displaying both common stochastic trends and common stochastic cycles. When modeling the dynamics of multiple time series for a panel of several entities such as countries, sectors, firms, imposing some form of separability and commonalities is often required to restrict the dimension of the parameter space. For this purpose we introduce the concept of common feature separation and investigate the relationships between separation in cointegration and separation in serial correlation common features. Loosely speaking we investigate whether a set of time series can be partitioned into subsets such that there are serial correlation common features within the sub-groups only. The paper investigates three issues. First, it provides conditions for separating joint cointegrating vectors into marginal cointegrating vectors as well as separating joint short-term dynamics into marginal short-term dynamics. Second, conditions for making permanent-transitory decompositions based on marginal systems are given. Third, issues of weak exogeneity are considered. Likelihood ratio type tests for the different hypotheses under study are proposed. An empirical analysis of the link between economic fluctuations in the United States and Canada shows the practical relevance of the approach proposed in this paper.     

The Importance of Social Movements

This discussion was conducted with Professor Alain Touraine by Tim Jordan on 20 September in Paris. The discussion has been divided into headings that correspond to the areas of questions that were asked. The social context for the discussion is important in understanding Professor Touraine's comments because the discussion occurred 9 days after the World Trade Center and Pentagon attacks but before the bombing of Afghanistan began and with no chance of knowing what would follow.     

Gambling over the life course and treatment-seeking

The purpose of this study is to investigate change in gambling behaviours over the life course, and, correspondingly, the treatment-seeking behaviours of 86 people who met the criteria for at-risk (participants endorsing two to four items on the South Oaks Gambling Screen [SOGS]) and problem gamblers (participants endorsing five or more items on the SOGS) over the last five years. Data were obtained from informants during semi-structured interviews using Structured Clinical Interview for DSM-IV axis I and axis II disorders (SCID I and II), SOGS and treatment-seeking interviews. The results showed three groups of gambling behaviours over the life course. A first group started gambling early on and continued participating in recreational gambling until its participants were between 40 and 50 years of age, during which time they became problem gamblers. A second group transitioned from recreational gambling to problem gambling over a short period of time; its participants were aged between 40 and 50. Lastly, a third group which was exposed to gambling later on in life, mostly after retirement, developed gambling problems quickly. Psychopathology was prevalent in all groups, given that 98% suffered from a mental health problem during their life, and 62% within the last six months. Participants who made use of the services available mostly turned to medical and specialized mental services for brief periods, usually when in crisis. In terms of problem gambling, the results argue in favour of maintaining dedication toward treatment, especially in the presence of co-morbidity.     

Core Self‐Evaluations,Work–Family Conflict,and Burnout

This study investigated how core self‐evaluations relate to work–family (and family–work) conflict and burnout. Drawing from a sample of 289 police officers and civilian staff who were either married or living in a union as common‐law partners, this study advances an empirical integration of work–family and core self‐evaluations research. The results suggested that even when work, nonwork, and demographic variables are controlled for, positive core self‐evaluations (i.e., composite scale, self‐esteem, locus of control, emotional stability) are related to less work–family (and family–work) conflict. The associations between core self‐evaluations and burnout are partially mediated by work–family (and family–work) conflict. Finally, core self‐evaluations moderated the association between work–family conflict and burnout, but not the one between family–work conflict and burnout.     

A generalized linear model approach to seasonal aspects of wind speed modeling

The aim of the article is to identify the intraday seasonality in a wind speed time series. Following the traditional approach, the marginal probability law is Weibull and, consequently, we consider seasonal Weibull law. A new estimation and decision procedure to estimate the seasonal Weibull law intraday scale parameter is presented. We will also give statistical decision-making tools to discard or not the trend parameter and to validate the seasonal model.     

A fully nonparametric approach in survival models with explanatory variables

The most widely used model for multidimensional survival analysis is the Cox model. This model is semi-parametric, since its hazard function is the product of an unspecified baseline hazard, and a parametric functional form relating the hazard and the covariates. We consider a more flexible and fully nonparametric proportional hazards model, where the functional form of the covariates effect is left unspecified. In this model, estimation is based on the maximum likelihood method. Results obtained from a Monte-Carlo experiment and from real data are presented. Finally, the advantages and the limitations of the approacha are discussed.     

An Axiomatization of Cumulative Prospect Theory for Decision Under Risk

Cumulative prospect theory was introduced by Tversky and Kahneman so as to combine the empirical realism of their original prospect theory with the theoretical advantages of Quiggin's rank-dependent utility. Preference axiomatizations were provided in several papers. All those axiomatizations, however, only consider decision under uncertainty. No axiomatization has been provided as yet for decision under risk, i.e., the case in which given probabilities are transformed. Providing the latter is the purpose of this note. The resulting axiomatization is considerably simpler than that for uncertainty.