Academic Paths,Ageing and the Living Conditions of Students in the Late 20th Century*

Le monde étudiant est profondément marqué par la diversité des tra‐jectoires individuelles, qui sont souvent très éloignées d'un déroule‐ment linéaire des études. Les conséquences sur l'âge des étudiants sont majeures, et la condition étudiante ne peut plus être définie comme une expérience strictement juvénile. Or, entre 20 et 30 ans, l'âge engendre des impératifs différentiels sur le plan des conditions et des modes de vie qui ne sont pas toujours compatibles avec la condition étudiante classique. Cette étude des parcours et de la situation financière des étudiants des universités québécoises de langue françhise et anglaise montre comment s'opère la déconnexion entre jeunesse et condition étudiante, et comment cette déconnexion influe sur la différenciation des conditions de vie et de financement des études. Student life is profoundly marked by the diversity of individual trajectories, which are in stark contrast with the linear path traditionally taken by students. The impact on the age of the student population is significant: indeed, student life can no longer be qualified as strictly for the young. Between the ages of 20 and 30 years, different imperatives come into play in terms of living conditions and lifestyle. These imperatives are not always compatible with the conditions of classic student life. This study of the academic paths and the financial situation of Quebec university students shows how the disconnection between student condition and youth occurs and how this disconnection impacts the differentiation of student's living conditions and modes of financing university studies.     

Are the <Emphasis Type="Italic">Generations and Gender Surveys</Emphasis> Well Suited for Studying Same-Sex Couples?

Different studies of same-sex couples based on the Generations and Gender Survey (GSS) have been published in recent years. However, in this survey, people in gay and lesbian couples are not identified via a direct question but by comparing two separate variables: the sex of the respondent and that of the partner. But the identification of same-sex couples by comparing the sex of both partners is very unreliable. The few sex-coding errors of one of the partners in heterosexual couples generate a very high proportion of “false” same-sex couples among all couples considered to be of the same sex. The aim of this paper is to demonstrate the problematic nature of the indicator in order to avoid inappropriate use of GGS data (and other surveys more generally) and to discuss the reliability of analyses of same-sex couples made with these data.     

Contrast function estimation for the drift parameter of ergodic jump diffusion process

In this paper, we consider an ergodic diffusion process with jumps whose drift coefficient depends on an unknown parameter. We suppose that the process is discretely observed. We introduce an estimator based on a contrast function, which is efficient without requiring any conditions on the rate at which the step discretization goes to zero, and where we allow the observed process to have nonsummable jumps. This extends earlier results where the condition on the step discretization was needed and where the process was supposed to have summable jumps. In general situations, our contrast function is not explicit and one has to resort to some approximation. In the case of a finite jump activity, we propose explicit approximations of the contrast function such that the efficient estimation of the drift parameter is feasible. This extends the results obtained by Kessler in the case of continuous processes.     

On sequential Monte Carlo sampling methods for Bayesian filtering

In this article, we present an overview of methods for sequential simulation from posterior distributions. These methods are of particular interest in Bayesian filtering for discrete time dynamic models that are typically nonlinear and non-Gaussian. A general importance sampling framework is developed that unifies many of the methods which have been proposed over the last few decades in several different scientific disciplines. Novel extensions to the existing methods are also proposed. We show in particular how to incorporate local linearisation methods similar to those which have previously been employed in the deterministic filtering literature; these lead to very effective importance distributions. Furthermore we describe a method which uses Rao-Blackwellisation in order to take advantage of the analytic structure present in some important classes of state-space models. In a final section we develop algorithms for prediction, smoothing and evaluation of the likelihood in dynamic models.     

Policy convergence under approval and plurality voting: the role of policy commitment

Proponents of Approval Voting argue that this electoral rule leads to more centrist outcomes compared to Plurality Voting. This claim has been substantiated by scholarly work using spatial models of political competition. We revisit this issue in the context of a model of political competition in which (1) candidates are policy-motivated; (2) candidacy decisions are endogenous; and (3) candidates can credibly commit to implementing any policy. Under these assumptions we find the opposite to be true – Plurality Voting yields convergence to the median voter’s ideal policy but Approval Voting may not. We argue that this result is driven by the differential incentives for candidate entry under the two voting rules. Our results suggest that whether Approval Voting yields more centrist outcomes vis-á-vis Plurality Voting depends on the possibility of policy commitment on the part of the candidates. In an election held under PV each citizen is given one vote he can cast for one (and only one) candidate, and the candidate who gets the most votes wins the election.     

Effects of Tai Chi exercises on self-efficacy and psychological health

This review offers an update of the psychological effects of Tai Chi Chuan (TC) among different populations. A computerized literature research from 1990 to June 2006 was carried out. Studies were selected when they assessed the mental and psychological effects of TC practice among various populations. Data from 14 studies for a total of 829 subjects, age range from 12 to 96 years, were considered here. There were eight randomized controlled trials and six quasi-experimental or case control studies in this review. The intensity of TC varied from 30 min twice a week over a 5-week period to 1 h every day over an 8-week period. TC was characterized as a kind of light-to-moderate exercise and was found to enhance overall psychological well-being and to improve self-efficacy and mood. TC benefits appeared to be more tangible for adults and healthy older adults or those becoming frail. However, TC did not appear to be more efficient than exercises of the same intensity. Extensive and qualitative studies are needed to quantify the effects of the volume of practice, expert modeling, gender differences, and the age-related learning process on efficacy cognitions and mood in clinical and nonclinical contexts.     

Treatment for Juveniles Who Sexually Offend in a Southwestern State

A 25-item questionnaire was mailed to sex offender treatment providers from counties with 60 or more reported juvenile sex offenders in a Southwestern state to determine the most effective treatment for juvenile sex offenders. Results indicated that cognitive behavioral therapy was the most successful reported approach to treatment with an average success rate of 87%. The most commonly used approach was cognitive behavioral therapy with relapse prevention. The most common sexual offense was indecency with a child involving sexual contact, contrary to studies that found that in the Probation Commission data, aggravated sexual offense was the most common. These results have ramifications for state policies on treatment for juvenile sex offenders.     

An avian urban morphotype: how the city environment shapes great tit morphology at different life stages

Urban Ecosystems - Urbanization is a worldwide phenomenon associated with tremendous modifications of natural habitats. Understanding how city dwelling species are affected by those changes is...     

Inefficient Job Destructions and Training with Hold‐up

This paper develops an equilibrium search model with endogenous job destructions and where firms decide at the time of job entry how much to invest in match‐specific human capital. We first show that job destruction and training investment decisions are strongly complementary. It is possible that there are no firings at equilibrium. Further, training investments are confronted to a hold‐up problem making the decentralized equilibrium always inefficient. We show therefore that both training subsidies and firing taxes must be implemented to bring back efficiency.