Evolution of the Female Labour Force Participation Rate in Canada, 1976-1994: a Cohort Analysis

The participation rate of women aged 25-64 rose greatly in the 1970s and 1980s, but has stagnated in the 1990s. In principle, this development could reflect either the poor growth performance of the economy this decade or the completion of the integration of women into the labour force. In the fourth article of this symposium, Paul Beaudry and Thomas Lemieux use a cohort analysis to shed light on the explanation of this stagnation in female labour force participation. Using data from the Survey of Consumer Finances for the 1976-94 period, the authors track the participation rates over time of representative groups of women who entered the labour force at different points in time. They decompose a cohort’s participation rate into three effects: a macroeconomic effect common across cohorts linked to factors such as recessions and employment insurance generosity; an age or life-cycle effect; and a cohort-specific effect which shows the differences between cohorts for a given age and macroeconomic effect. The authors find that the cohort effects are likely the dominant factor in explaining the recent stagnation of female participation, just as it explained the large increases in the 1970s and 1980s. The recession of the early 1990s, which according to the authors reduced the female participation rate by 1 percentage point, merely amplified the stagnation phenomenon. As the cohort effects stabilize with the narrowing of the gap between male and female participation rates, the stagnation would have occurred, albeit later in the 1990s, even if more favourable macroeconomic conditions had prevailed. The authors conclude that there is still room for a 2-3 percentage point increase in the participation rate of women 25-64, but the magnitude of the increases of the 1970s and 1980s is not possible as the cohort effects that prevailed then no longer exist. The authors stress that their results are dependent on the amount of flexibility used to capture the cohort effect so that the age profile and its slope can trace both the rise and the flattening of the participation rate by age. They point out that over time participation behaviour of women 25-64 is converging toward that of men, namely, high and flat participation profiles to at least age 55. They also note that the much smaller increase in the female participation rate in the United States in the 1990s relative to the 1970s and 1980s despite the robust U.S. labour market supports their findings as the cohort effects were also levelling out south of the border.Canada, Labour Force Participation, Labor Force Participation, Participation Rate, Labour Force Participation Rate, Labor Force Participation Rate, Age Structure, Age, Sex, Gender, Aging, Ageing, Women

The spatio-temporal mapping of epileptic networks: Combination of EEG–fMRI and EEG source imaging

Simultaneous EEG–fMRI acquisitions in patients with epilepsy often reveal distributed patterns of Blood Oxygen Level Dependant (BOLD) change correlated with epileptiform discharges. We investigated if electrical source imaging (ESI) performed on the interictal epileptiform discharges (IED) acquired during fMRI acquisition could be used to study the dynamics of the networks identified by the BOLD effect, thereby avoiding the limitations of combining results from separate recordings. Nine selected patients (13 IED types identified) with focal epilepsy underwent EEG–fMRI. Statistical analysis was performed using SPM5 to create BOLD maps. ESI was performed on the IED recorded during fMRI acquisition using a realistic head model (SMAC) and a distributed linear inverse solution (LAURA). ESI could not be performed in one case. In 10/12 remaining studies, ESI at IED onset (ESIo) was anatomically close to one BOLD cluster. Interestingly, ESIo was closest to the positive BOLD cluster with maximal statistical significance in only 4/12 cases and closest to negative BOLD responses in 4/12 cases. Very small BOLD clusters could also have clinical relevance in some cases. ESI at later time frame (ESIp) showed propagation to remote sources co-localised with other BOLD clusters in half of cases. In concordant cases, the distance between maxima of ESI and the closest EEG–fMRI cluster was less than 33 mm, in agreement with previous studies. We conclude that simultaneous ESI and EEG–fMRI analysis may be able to distinguish areas of BOLD response related to initiation of IED from propagation areas. This combination provides new opportunities for investigating epileptic networks

Algorithme génétique spécifique à l'analyse de la susceptibilité à l'hypertension de la population du Saguenay-Lac-Saint-Jean

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Approches bio-informatiques appliquées aux technologies émergentes en génomique

Les études génétiques, telles que les études de liaison ou d’association, ont permis d’acquérir une plus grande connaissance sur l’étiologie de plusieurs maladies affectant les populations humaines. Même si une dizaine de milliers d’études génétiques ont été réalisées sur des centaines de maladies ou autres traits, une grande partie de leur héritabilité reste inexpliquée. Depuis une dizaine d’années, plusieurs percées dans le domaine de la génomique ont été réalisées. Par exemple, l’utilisation des micropuces d’hybridation génomique comparative à haute densité a permis de démontrer l’existence à grande échelle des variations et des polymorphismes en nombre de copies. Ces derniers sont maintenant détectables à l’aide de micropuce d’ADN ou du séquençage à haut débit. De plus, des études récentes utilisant le séquençage à haut débit ont permis de démontrer que la majorité des variations présentes dans l’exome d’un individu étaient rares ou même propres à cet individu. Ceci a permis la conception d’une nouvelle micropuce d’ADN permettant de déterminer rapidement et à faible coût le génotype de plusieurs milliers de variations rares pour un grand ensemble d’individus à la fois. Dans ce contexte, l’objectif général de cette thèse vise le développement de nouvelles méthodologies et de nouveaux outils bio-informatiques de haute performance permettant la détection, à de hauts critères de qualité, des variations en nombre de copies et des variations nucléotidiques rares dans le cadre d’études génétiques. Ces avancées permettront, à long terme, d’expliquer une plus grande partie de l’héritabilité manquante des traits complexes, poussant ainsi l’avancement des connaissances sur l’étiologie de ces derniers. Un algorithme permettant le partitionnement des polymorphismes en nombre de copies a donc été conçu, rendant possible l’utilisation de ces variations structurales dans le cadre d’étude de liaison génétique sur données familiales. Ensuite, une étude exploratoire a permis de caractériser les différents problèmes associés aux études génétiques utilisant des variations en nombre de copies rares sur des individus non reliés. Cette étude a été réalisée avec la collaboration du Wellcome Trust Centre for Human Genetics de l’University of Oxford. Par la suite, une comparaison de la performance des algorithmes de génotypage lors de leur utilisation avec une nouvelle micropuce d’ADN contenant une majorité de marqueurs rares a été réalisée. Finalement, un outil bio-informatique permettant de filtrer de façon efficace et rapide des données génétiques a été implémenté. Cet outil permet de générer des données de meilleure qualité, avec une meilleure reproductibilité des résultats, tout en diminuant les chances d’obtenir une fausse association.Genetic studies, such as linkage and association studies, have contributed greatly to a better understanding of the etiology of several diseases. Nonetheless, despite the tens of thousands of genetic studies performed to date, a large part of the heritability of diseases and traits remains unexplained. The last decade experienced unprecedented progress in genomics. For example, the use of microarrays for high-density comparative genomic hybridization has demonstrated the existence of large-scale copy number variations and polymorphisms. These are now detectable using DNA microarray or high-throughput sequencing. In addition, high-throughput sequencing has shown that the majority of variations in the exome are rare or unique to the individual. This has led to the design of a new type of DNA microarray that is enriched for rare variants that can be quickly and inexpensively genotyped in high throughput capacity. In this context, the general objective of this thesis is the development of methodological approaches and bioinformatics tools for the detection at the highest quality standards of copy number polymorphisms and rare single nucleotide variations. It is expected that by doing so, more of the missing heritability of complex traits can then be accounted for, contributing to the advancement of knowledge of the etiology of diseases. We have developed an algorithm for the partition of copy number polymorphisms, making it feasible to use these structural changes in genetic linkage studies with family data. We have also conducted an extensive study in collaboration with the Wellcome Trust Centre for Human Genetics of the University of Oxford to characterize rare copy number definition metrics and their impact on study results with unrelated individuals. We have conducted a thorough comparison of the performance of genotyping algorithms when used with a new DNA microarray composed of a majority of very rare genetic variants. Finally, we have developed a bioinformatics tool for the fast and efficient processing of genetic data to increase quality, reproducibility of results and to reduce spurious associations

Eating behaviors of non-obese individuals with and without familial history of obesity

The aim of the present study was to examine whether eating behaviours and their subscales are associated with familial history of obesity (FHO) in a cohort of 326 non-obese men and women. Anthropometric measurements, eating behaviours (Three-Factor Eating Questionnaire) and dietary intakes (FFQ) have been determined in a sample of 197 women and 129 men. A positive FHO (FHOþ) was defined as having at least one obese first-degree relative and a negative FHO (FHO2) as no obese first-degree relative. Men with FHOþ had higher scores of cognitive dietary restraint and flexible restraint than men with FHO2. In women, those with FHOþ had a higher score of disinhibition than women with FHO2. In both men and women, eating behaviours were not significantly associated with the number of obese family members. However, having an obese mother was associated with higher scores of cognitive dietary restraint, flexible restraint and rigid restraint in women. These findings demonstrate that eating behaviours of non-obese subjects are different according to the presence or absence of obese family members. More specifically, having an obese mother is associated with a higher dietary restraint score in women

Safety of Simultaneous Scalp or Intracranial EEG during MRI: A Review

Understanding the brain and its activity is one of the great challenges of modern science. Normal brain activity (cognitive processes, etc.) has been extensively studied using electroencephalography (EEG) since the 1930's, in the form of spontaneous fluctuations in rhythms, and patterns, and in a more experimentally-driven approach in the form of event-related potentials (ERPs) allowing us to relate scalp voltage waveforms to brain states and behavior. The use of EEG recorded during functional magnetic resonance imaging (EEG-fMRI) is a more recent development that has become an important tool in clinical neuroscience, for example for the study of epileptic activity. The purpose of this review is to explore the magnetic resonance imaging safety aspects specifically associated with the use of scalp EEG and other brain-implanted electrodes such as intracranial EEG electrodes when they are subjected to the MRI environment. We provide a theoretical overview of the mechanisms at play specifically associated with the presence of EEG equipment connected to the subject in the MR environment, and of the resulting health hazards. This is followed by a survey of the literature on the safety of scalp or invasive EEG-fMRI data acquisitions across field strengths, with emphasis on the practical implications for the safe application of the techniques; in particular, we attempt to summarize the findings in terms of acquisition protocols when possible