Influence du vieillissement et de la scolarité sur la compréhension du discours : apport de l’imagerie optique

La compréhension du discours, et son évolution au cours du vieillissement, constitue un sujet d’une grande importance par sa complexité et sa place dans la préservation de la qualité de vie des aînés. Les objectifs de cette thèse étaient d’évaluer l’influence du vieillissement et du niveau de scolarité sur les capacités de compréhension du discours et sur l’activité cérébrale s’y rattachant. Pour ce faire, trois groupes (jeunes adultes ayant un niveau universitaire de scolarité, personnes âgées ayant un niveau universitaire de scolarité et personnes âgées ayant un niveau secondaire de scolarité) ont réalisé une tâche où ils devaient lire de courtes histoires, puis estimer la véracité d’une affirmation concernant cette histoire. Les capacités de compréhension correspondant aux traitements de trois niveaux du modèle de construction-intégration de Kintsch (la microstructure, la macrostructure et le modèle de situation) ont été évaluées. L’imagerie optique (NIRS) a permis d’estimer les variations d’oxyhémoglobine (HbO) et de déoxyhémoglobine (HbR) tout au long de la tâche. Les résultats ont démontré que les personnes âgées étaient aussi aptes que les plus jeunes pour rappeler la macrostructure (essentiel du texte), mais qu’ils avaient plus de difficulté à rappeler la microstructure (détails) et le modèle de situation (inférence et intégration) suite à la lecture de courts textes. Lors de la lecture, les participants plus âgés ont également montré une plus grande activité cérébrale dans le cortex préfrontal dorsolatéral gauche, ce qui pourrait être un mécanisme de compensation tel que décrit dans le modèle CRUNCH. Aucune différence significative n’a été observée lors de la comparaison des participants âgés ayant un niveau universitaire de scolarité et ceux ayant un niveau secondaire, tant au niveau des capacités de compréhension que de l’activité cérébrale s’y rattachant. Les deux groupes ont cependant des habitudes de vie stimulant la cognition, entre autres, de bonnes habitudes de lecture. Ainsi, ces habitudes semblent avoir une plus grande influence que l’éducation sur les performances en compréhension et sur l’activité cérébrale sous-jacente. Il se pourrait donc que l’éducation influence la cognition en promouvant des habitudes favorisant les activités cognitives, et que ce soit ces habitudes qui aient en bout ligne un réel impact sur le vieillissement cognitif.

Programme d’exercice en douceur basé sur le yoga Bali chez les personnes atteintes d’insuffisance cardiaque : les premiers pas.

L’insuffisance cardiaque (IC) est un problème d’importance grandissante lié à des perturbations des systèmes nerveux autonome, immunitaire, et cardiovasculaire. Ces perturbations contribuent à plusieurs symptômes physiques et psychologiques invalidants. La recherche faite jusqu’ici sur des programmes d’exercice basés sur le yoga a démontré des résultats préliminaires assez prometteurs en IC. Néanmoins, il reste des lacunes à combler dans la littérature face aux populations testées, à la combinaison des mesures physiques et psychologiques, au suivi du traitement à la maison et à la perception des symptômes au quotidien. Ce projet pilote a donc pour objectif de développer un programme d’exercice complémentaire basé sur le yoga adapté aux patients souffrant d’IC, d’en mesurer la faisabilité et l’acceptabilité en plus d’obtenir des données préliminaires quant à l’impact de cette intervention à réduire la symptomatologie physique et psychologique et d’améliorer la qualité de vie (QV) de ces patients. Les deux premiers participants recrutés dans le cadre de l’étude pilote font l’objet de ce mémoire. Ils ont pris part à huit séances hebdomadaires de yoga Bali, couplé de psychoéducation et méditation tous données à l’Institut de Cardiologie de Montréal par une instructrice certifiée dans la méthode BALI. L’élaboration des outils nécessaires au déroulement du programme, y compris le manuel d’enseignement et le DVD, la faisabilité d’une collaboration avec le personnel médical et évidement l’évaluation des effets du programme en soit sur les symptômes physiques et psychologique s sont parmi les sujets abordés. Les résultats, quoique préliminaires, semblent tendre vers une amélioration des corrélats physiologiques liés à l’insuffisance cardiaque, notamment l’activité du système nerveux autonome tel que témoigné par la variabilité de la fréquence cardiaque, et l’inflammation indiqué par le niveau de CRP sanguin.

« How to Teach Evidence-Based Clinical Practice 2002 » : Rapport de la semaine de formation

Rapport de la semaine de formation "How to teach Evidence-Based Clinical Practice 2002" tenue à McMaster University du 9 au 14 juin 2002. Le rapport présente le déroulement de la semaine, les apprentissages et les applications au travail.

Reported Job Satisfaction : What Does It Mean?

By reporting his satisfaction with his job or any other experience, an individual does not communicate the number of utils that he feels. Instead, he expresses his posterior preference over available alternatives conditional on acquired knowledge of the past. This new interpretation of reported job satisfaction restores the power of microeconomic theory without denying the essential role of discrepancies between one’s situation and available opportunities. Posterior human wealth discrepancies are found to be the best predictor of reported job satisfaction. Static models of relative utility and other subjective well-being assumptions are all unambiguously rejected by the data, as well as an \"economic\" model in which job satisfaction is a measure of posterior human wealth. The \"posterior choice\" model readily explains why so many people usually report themselves as happy or satisfied, why both younger and older age groups are insensitive to current earning discrepancies, and why the past weighs more heavily than the present and the future.

Sector-Specific Training and Mobility in Germany

This article studies mobility patterns of German workers in light of a model of sector-specific human capital. Furthermore, I employ and describe little-used data on continuous on-the-job training occurring after apprenticeships. Results are presented describing the incidence and duration of continuous training. Continuous training is quite common, despite the high incidence of apprenticeships which precedes this part of a worker's career. Most previous studies have only distinguished between firm-specific and general human capital, usually concluding that training was general. Inconsistent with those conclusions, I show that German men are more likely to find a job within the same sector if they have received continuous training in that sector. These results are similar to those obtained for young U.S. workers, and suggest that sector-specific capital is an important feature of very different labor markets. In addition, they suggest that the observed effect of training on mobility is sensible to the state of the business cycle, indicating a more complex interaction between supply and demand that most theoretical models allow for.

Wage Flexibility and Contract Structure in Germany

In this paper, we look at how labor market conditions at different points during the tenure of individuals with firms are correlated with current earnings. Using data on individuals from the German Socioeconomic Panel for the 1985-1994 period, we find that both the contemporaneous unemployment rate and prior values of the unemployment rate are significantly correlated with current earnings, contrary to results for the American labor market. Estimated elasticities vary between 9 and 15 percent for the elasticity of earnings with respect to current unemployment rates, and between 6 and 10 percent with respect to unemployment rates at the start of current firm tenure. Moreover, whereas local unemployment rates determine levels of earnings, national rates influence contemporaneous variations in earnings. We interpret this result as evidence that German unions do, in fact, bargain over wages and employment, but that models of individualistic contracts, such as the implicit contract model, may explain some of the observed wage drift and longer-term wage movements reasonably well. Furthermore, we explore the heterogeneity of contracts over a variety of worker and job characteristics. In particular, we find evidence that contracts differ across firm size and worker type. Workers of large firms are remarkably more insulated from the job market than workers for any other type of firm, indicating the importance of internal job markets.

Sector-Specific on-the-Job Training: Evidence from U.S. Data.

Using data from the National Longitudinal Survey of Youth (NLSY), we re-examine the effect of formal on-the-job training on mobility patterns of young American workers. By employing parametric duration models, we evaluate the economic impact of training on productive time with an employer. Confirming previous studies, we find a positive and statistically significant impact of formal on-the-job training on tenure with the employer providing the training. However, the expected net duration of the time spent in the training program is generally not significantly increased. We proceed to document and analyze intra-sectoral and cross-sectoral mobility patterns in order to infer whether training provides firm-specific, industry-specific, or general human capital. The econometric analysis rejects a sequential model of job separation in favor of a competing risks specification. We find significant evidence for the industry-specificity of training. The probability of sectoral mobility upon job separation decreases with training received in the current industry, whether with the last employer or previous employers, and employment attachment increases with on-the-job training. These results are robust to a number of variations on the base model.

Distortionary Taxation and Labor Supply: Evidence from Canada.

This paper examines empirically the effects of distortionary taxation on labor supply using a general equilibrium framework. The long-term relations predicted by the model are derived and tested using Canadian data between 1966 and 1993. While the cointegrating predictions of the model without taxation are rejected, the ones of the model with labor taxation are not. Persistent labor tax rate increases appear to play an important role in the observed downward trend in hours worked.

Altruism, Intergenerational Transfers of Time and Bequests

This paper uses a standard two-period overlapping generation model to examine the behavior of an economy where both intergenerational transfers of time and bequests are available. While bequests have been examined extensively, time transfers have received little or no attention in the literature. Assuming a log-linear utility function and a Cobb-Douglas production function, we derive an explicit solution for the dynamics and show that altruistic intergenerational time transfers can take place in presence of a binding non-negativity constraint on bequests. We also show that with either type of transfers capital is an increasing function of the intergenerational degree of altruism. However, while with time transfers the labor supply of the young increases with the degree of altruism, with bequests it may decrease

Why Have Aggregate Skilled Hours Become So Cyclical Since the Mid-1980's?

This paper documents and discusses a dramatic change in the cyclical behavior of aggregate hours worked by individuals with a college degree (skilled workers) since the mid-1980’s. Using the CPS outgoing rotation data set for the period 1979:1-2003:4, we find that the volatility of aggregate skilled hours relative to the volatility of GDP has nearly tripled since 1984. In contrast, the cyclical properties of unskilled hours have remained essentially unchanged. We evaluate the extent to which a simple supply/demand model for skilled and unskilled labor with capital-skill complementarity in production can help explain this stylized fact. Within this framework, we identify three effects which would lead to an increase in the relative volatility of skilled hours: (i) a reduction in the degree of capital-skill complementarity, (ii) a reduction in the absolute volatility of GDP (and unskilled hours), and (iii) an increase in the level of capital equipment relative to skilled labor. We provide empirical evidence in support of each of these effects. Our conclusion is that these three mechanisms can jointly explain about sixty percent of the observed increase in the relative volatility of skilled labor. The reduction in the degree of capital-skill complementarity contributes the most to this result.