The implementation of game elements has quintessentially uplifted the overall experience of applications in various domains and thereby expanding the customer base. This process is called gamification which has now been introduced in many domains. The purpose of the study is to understand gamification and how its impact would be if it is deployed in a financial savings application. The gamified elements are implemented based on a gamification framework called the Octalysis framework1. This Octalysis framework is a human-centric gamification framework which serves as a template to implement the required gamified elements. Based on a pre-study of financial applications and the Octalysis framework, two distinct prototypes (Version A and Version B) of the same mobile app concept were developed where the difference is the presence of gamified elements in one prototype. The evaluation is based on analyzing the impact the gamified elements have caused on the usability and the emotional engagement of the financial savings application. The participants are provided to interact with both prototypes and interviews are conducted to evaluate the emotional engagement and the usability of both the prototypes of the financial savings application. The study shows an increase in emotional engagement corresponding to the gamified elements whereas the usability more or less remained the same, indicating a deeper investigation of the gamified elements with regards to usability is required.

No description available.

Le but de cette recherche est d’obtenir une meilleure compréhension de l’incidence des symptômes reliés au trouble bipolaire sur l’efficacité personnelle et collective dans un contexte d’équipe pour améliorer l’intégration des employés avec ce trouble en milieu de travail. Les données utilisées sont de type primaire. Elles ont été recueillies auprès de 483 participants à l’aide d’un questionnaire. Des analyses structurelles ont ensuite permis de mettre à l’épreuve les cinq hypothèses proposées. Les résultats obtenus illustrent que l’impact des symptômes bipolaires sur le sentiment d’efficacité personnelle et collective serait à la fois indirect et direct. Effectivement, la présence de symptômes bipolaires est susceptible d’augmenter les risques de vivre des conflits interpersonnels et de percevoir de la stigmatisation au travail. La présence de ces deux stresseurs sociaux peut influencer négativement le sentiment d’efficacité personnelle et collective de l’individu. La présence de symptômes bipolaires semble influencer négativement le sentiment d’efficacité personnelle et collective. La contribution empirique de ce mémoire est de mettre en lumière la corrélation entre les symptômes du trouble bipolaire et l’augmentation des conflits interpersonnels et de la stigmatisation internalisée en milieu professionnel. De plus, ce mémoire met en évidence l’impact négatif que peut avoir l’augmentation des conflits et de la stigmatisation internalisée sur l’efficacité personnelle et collective. Sur le plan pratique, ces conclusions fournissent des bases solides pour orienter les politiques et les pratiques en milieu professionnel. Elles suggèrent la nécessité de développer des environnements de travail plus sensibles et inclusifs pour les individus affectés par le trouble bipolaire. Ces résultats incitent également à la mise en place de mesures visant à réduire les conflits interpersonnels et à atténuer la stigmatisation pour promouvoir un meilleur fonctionnement au sein des équipes. / The goal of this research is to obtain a better understanding of the impact of symptoms related to bipolar disorder on personal and collective effectiveness in a team context to improve the integration of employees with this disorder in the workplace. The data used is of primary type. They were collected from 483 participants using a questionnaire. Primary and structural analyzes then made it possible to test the five proposed hypotheses. The results obtained illustrate that the impact of bipolar symptoms on the feeling of personal and collective efficacy is both indirect and direct. Indeed, the presence of bipolar symptoms seems to increase the risks of experiencing interpersonal conflicts and perceiving stigma at work. The presence of bipolar symptoms seems to also influence the feeling of personal and collective efficacy negatively. The empirical contribution of this thesis is to highlight the correlation between bipolar disorder symptoms and the increase in interpersonal conflicts and perceived stigmatization in the professional environment. Furthermore, this thesis demonstrates the negative impact that heightened conflicts and perceived stigmatization can have on personal and collective effectiveness. Practically speaking, these findings provide a solid foundation for guiding policies and practices in the professional sphere. They suggest the necessity of developing more sensitive and inclusive work environments for individuals affected by bipolar disorder. Moreover, these results advocate for implementing measures aimed at reducing interpersonal conflicts and mitigating stigmatization to promote better team functioning.

This thesis explores the impact of two behavioural finance concepts, social psychology and psychology, on household financial decisions. Under social psychology, I investigate whether the variety and intensity of social engagement enhances stock market participation. With regard to psychology, I examine two behavioural biases. First, I investigate whether mental accounting influences portfolio choice in three asset classes and whether financial advice and housing tenure increase (decrease) the effects of mental accounts on portfolio choice. Second, I examine whether households’ self-reported housing wealth are anchored on published house price indices and whether anchoring bias is mediated by market information, mortgage refinancing decisions and social factors. The main contributions and findings in the three studies are as follows. First, although there is an elaborate body of research concerning the relationship between social engagement mechanisms and portfolio choice, most studies investigate specific mechanisms in isolation. Using three waves in the British Household Panel Survey (BHPS), I bring together five social engagement measures in one model and show that socially engaged individuals are more likely to participate in the stock market. Consistent with Granovetter’s (1973) theory of social networks I find that a weak tie (measured by social group involvement) has a positive effect on stock market participation whereas a strong tie (measured by talking to neighbours) has no effect. More trusting individuals are more likely to participate in the stock market, as are those who identify with a political party. In contrast, the degree to which religion is important appears to have little impact. These results are robust using different specifications. Overall, the results of this study demonstrate that the likelihood of stock market participation increases with the variety and intensity of social engagement. Second, despite the established theoretical underpinnings of mental accounting in behavioural portfolio theory (BPT) and recent extensions, not much is known about their implications in real life situations. I use a recent UK household survey, the Wealth and Assets Survey (WAS), which has comprehensive information about financial assets to investigate whether there are differences in the ownership and portfolio share of three asset classes among individuals who exhibit no mental account, a single mental account and multiple mental accounts, and the conditional influences of financial advice, housing, cognitive ability, time preference and risk tolerance. Overall I find that mental accounting together with financial advice and housing tenure explain variations in both the probability of ownership and portfolio share in the three asset classes. Households that exhibit a single mental account have low share of investments in, and are less likely to own, a risky asset when compared to those that exhibit no mental account or exhibit multiple mental accounts. I also find that, when compared to having no mental account, exhibiting a single mental account or multiple mental accounts increases both the probability and investment share in a fairly safe asset but decreases portfolio share in safe assets. In addition, among those that exhibit a single mental or multiple mental accounts, financial advice decreases portfolio share in risky assets and fairly safe assets and increases portfolio share in safe assets. Housing tenure increases both the probability and portfolio share in risky assets, decreases portfolio share in fairly safe assets and increases portfolio share in safe assets. These results are consistent using multi-equation regressions, sub-samples, reparametrised variables and poisson regressions. Finally, as little is known about how households derive the self-reported house prices estimates that are commonly used to determine housing wealth, the third study examines whether households are anchored on published house price indices. The key conjecture is that, while assessing the values of their homes, homeowners place more weight on house price news at the expense of property characteristics and other market information. I find support for this hypothesis using sixteen waves of the BHPS, multiple methods, and both regional and national house price indices. I conclude that changes in self-reported housing wealth are anchored on changes in published house price indices. Specifically, ownership through a mortgage and greater financial expectations increase anchoring effects while mortgage refinancing decreases the effects. Moreover, use of money raised from refinancing for home investment, as opposed to other consumption purposes, has a positive association with change in self-reported house value and both uses reduce anchoring bias. In addition, I find that computer use increases anchoring bias and, among social engagement mechanisms, religiosity reduces anchoring while other measures have no effect. These results are robust to internal instrumental variables, national aggregate house prices, alternative indices and sub-samples.

Les facteurs de risque de troubles musculo-squelettiques(TMS) tels que les facteurs physiques, organisationnels et psychosociaux sont un défi commun pour les industries de l'assemblage automobile qui entrainent des effets indésirables sur le système et les humains. L’ergonomie a déjà été intégrée dans les systèmes de production de ces industries pour la prise en charge de la prévention des TMS. La question est de savoir si l'approche ergonomique actuelle des industries automobiles, sur la base de normes à l'entreprise et des méthodes d'observation, peut fournir une connaissance partagée des facteurs ergonomiques pour les divers intervenants et pour faciliter l'amélioration des conditions de travail. Cette étude aborde la problématique du positionnement des différents méthodes d'évaluation (utilisées par les différents intervenants) et compare les résultats et apports de chaque méthode d'évaluation. Cette thèse propose que la procédure actuelle d'évaluation des risques de TMS ne favorise pas une connaissance partagée entre les intervenants dans les industries automobiles. On constate que les évaluations par auto-questionnaire (opérateurs) sont significativement différentes de celles issues des méthodes d'observation (ergonome) et des mesures directes (analyse biomécanique). Cependant, les opinions et jugements des opérateurs concernant les facteurs ergonomiques sont importants pour faciliter la réussite d'une approche ergonomique. Un entretien structuré et systématisé, basé sur des données objectives (Video-observations ou de mesure directe) liées aux activités et stratégies des opérateurs, pourrait être une procédure appropriée pour faire progresser l'ergonomie des situations de travail. Enfin, la connaissance tirée de cette thèse souligne que la variabilité des tâches dans l’industrie automobile nécessite une approche ergonomique qui partage les connaissances des risques entre les intervenants. Dans cette approche, les attitudes et les comportements des opérateurs sont pris en compte dans les projets d’amélioration continue. De plus, la participation des intervenants devrait être intégrée afin d'améliorer la prise en compte de l'ergonomie dans la production. Une synthèse de cette thèse en Français a été fournie dans l’annexe première. / Musculoskeletal risk factors such as physical, organizational and psychosocial factors are a common challenge for the automotive assembly industries and result in adverse human and system effects. Ergonomics has already been integrated inthe production systems of such factories to eliminate work related musculoskeletal disorders (WR-MSDs). The issue is whether the current ergonomic approach of car industries, based on corporate standards and observational methods, can provide a shared knowledge of ergonomic factors for various stakeholders and facilitate ergonomic improvement. This study focuses on the positioning of the different assessment methods (used by various stakeholders), agreement between their results in evaluation of physical risk factors and the influence of intervention and improvement following ergonomic assessment. This thesis proposes that the current procedure of risk factor assessment can not provide ashared knowledge and representation of risks between stakeholders in manufacturing industries. It was found that the operators’ assessments of risk factors (self-reported questionnaire) were significantly different from those assessed by observational methods (ergonomist) and direct measurement. However, the operators’ opinions and judgments of ergonomic factors of a job are of particular importance to the success of an ergonomic approach. A structured interview based on objective data (video-observation or direct measurement) linked the activities and strategies of atrisk operators might be an appropriate procedure to advance ergonomics.The knowledge gained from this study emphasizes that the variable nature of tasks in manufacturing industries needs an ergonomic approach which shares knowledge and representation of risks between stakeholders. In such an approach, attitudes and behaviors of operators are taken into consideration in developing new intervention processes, organizational and technical remedies. Moreover, involvement of stakeholders should be integrated and this should result in improving production ergonomics.

Ce travail présente un dispositif de surveillance épidémiologique novateur en santé environnementale fondée sur des évènements de santé déclarée, au plus près de la nature des plaintes exprimées par les populations : des symptômes et une dégradation de la qualité de vie. Ce dispositif est proposé à partir d’une réflexion conceptuelle reposant sur une revue de la littérature sur les théories psychométriques et le modèle transactionnel du stress et d’une application de terrain portant sur la population (n=1 495) riveraine du site industriel chimique de Salindres (Gard). Ces travaux permettent de vérifier les principales propriétés métriques d’indicateurs de santé déclarée mesurés, par les instruments MOS SF-36 et SCL-90-R, dans le cadre d’une population exposée à une pollution environnementale. Ils vérifient également l’adéquation et la sensibilité de ces indicateurs pour étudier les facteurs de risque environnementaux qui se réfèrent aux représentations cognitives des risques, comme la perception sensoriels des stimuli émis par les sites industriels. Ils montrent, en outre, que la disponibilité de références nationales portant sur la mesure de ces indicateurs leur confère un critère de qualité essentiel d’interprétation des résultats. Ces travaux apportent enfin des éléments d’appréciation de l’acceptabilité de la mesure des indicateurs de santé déclarée dans la population, des recommandations sur la communication pour la mise en œuvre d’un tel dispositif et des pistes de réflexion pour la gestion. / This work presents an innovative epidemiological surveillance system in environmental health based on self-reported health indicators, closer to the complaints of the local population leaving around a source of environmental pollution: symptoms and loss of the quality of life. This approach is built up from a conceptual framework based on the psychometric theory and the transactional model of stress. A field application of this approach was carried out the population neighboring (n=1 495) the chemical industrial area of Salindres, Gard. This study verifies that self-reported health indicators measured with MOS SF-36 and SCL-90-R can be used to study populations exposed to multifactorial environmental risks. This study confirms that these indicators are relevant and sensitive when applied to environmental risk factors referring to the cognitive representations of risks, such as the sensorial perception of stimuli emitted by the industries. This work shows, besides, that the availability of national references for these indicators confers interpretability to these indicators, an essential quality criterion. This work discusses qualitatively the acceptability of measuring indicators of self-reported health in the population, proposes recommendations on communication for the setting of that kind of approach, and opens up avenues on management orientations.

Alors que la question du vieillissement de la population dans les pays d’Afrique subsaharienne ne semble pas être particulièrement préoccupante pour l’instant, les conditions de vie des personnes âgées s’imposent graduellement comme un enjeu majeur de prise en charge sociale au regard de la croissance rapide de leur effectif. Les systèmes formels de retraite, d'assurance maladie et de protection sociale destinés aux personnes âgées vivant dans la plupart de ces pays demeurent quasiment inexistants, malgré la ratification et l’adoption de plusieurs conventions et recommandations internationales visant l’amélioration de leurs conditions de vie. Compte tenu de ces faiblesses, la famille est très souvent présentée comme la principale source de soutien des personnes âgées dans le besoin à travers leurs arrangements résidentiels, notamment la cohabitation avec d’autres personnes (conjoint, enfants adultes ou autres parentés), mais aussi par le biais des transferts financiers ou matériels qu’elles reçoivent en provenance de la famille qui vit en dehors de leur ménage. L’objectif principal de la présente thèse est de contribuer aux connaissances actuelles sur les conditions de vie et de santé des personnes âgées en examinant leurs modes de cohabitation, les transferts de ressources qu’elles pourraient recevoir du réseau familial externe au ménage, les liens entre ces deux formes de soutien et leurs corrélations avec l’état de santé des personnes âgées vivant en contexte d’Afrique subsaharienne (le Sénégal). Afin d’atteindre cet objectif, trois articles scientifiques empiriques ont été rédigés en utilisant d’une part les données des trois derniers recensements de la population du Sénégal (1988, 2002 et 2013) et d’autre part, la deuxième Enquête Pauvreté et Structure Familiale au Sénégal réalisée en 2011. Le premier article propose un portrait des arrangements résidentiels des personnes âgées notamment les situations où elles vivent avec/sans leur conjoint et/ou leurs enfants adultes selon le sexe et examine leur évolution à travers le temps. Les résultats suggèrent que la réalité du vieillissement est très différente pour les hommes et pour les femmes. Les hommes sont plus susceptibles de vivre accompagnés par leur conjointe et au moins un enfant adulte tandis que les femmes âgées sont beaucoup plus susceptibles de vivre sans conjoint mais avec un enfant adulte pour des raisons de veuvage, de séparation ou de divorce. En revanche, vivre seul tout comme vivre à la fois sans conjoint et sans autre adulte demeure un mode de cohabitation très marginal chez les personnes âgées au Sénégal, quel que soit leur sexe. Par ailleurs, les résultats ont aussi permis de constater qu’au fil des récentes décennies, il n’y a pas eu de changements majeurs dans les modes de cohabitation des personnes âgées, bien qu’on note des prémices d’une augmentation de la proportion des hommes qui vivent seuls ou sans conjoint ni adulte notamment chez les générations plus récentes. Le second article vise à améliorer notre compréhension des mécanismes de soutien familial dans le contexte des pays en développement en examinant dans quelle mesure les modes de cohabitation des personnes âgées sont associées à la réception de transferts financiers ou matériels provenant de la famille qui vit en dehors de leur ménage. Les résultats mettent en évidence un avantage net des femmes à recevoir des transferts familiaux nets positifs par rapport aux hommes pour certains arrangements résidentiels. Il ressort également que le fait de vivre sans mari ni enfant adulte augmente significativement la probabilité pour les femmes âgées de recevoir un soutien de la part de membres de la famille non-cohabitants, comparativement à celles qui vivent à la fois avec un conjoint et un enfant adulte plus jeune. Toutefois, ces différences ne se sont pas révélées significatives chez les hommes âgés. Dans le cadre du troisième article de la thèse, nous avons examiné dans quelle mesure la composition du ménage des personnes âgées et les transferts qu’elles reçoivent de la famille hors ménage sont associés à leur état de santé. L’utilisation d’une stratégie analytique prenant en compte des potentiels biais d’endogénéité a permis de constater que les femmes âgées qui vivent sans conjoint et sans adulte ont une probabilité plus élevée de déclarer une moins bonne santé que celles qui vivent avec l’un ou l’autre, ou les deux. En revanche, les différences en matière de santé perçue selon les types d’arrangements résidentiels ne se sont pas révélées significatives chez les hommes. Par ailleurs, il existe un désavantage en matière de perception de la santé chez les femmes qui n’ont pas reçu de transferts de la famille hors ménage, mais chez les hommes le rôle de ces transferts reste mitigé. Globalement, les résultats de cette thèse suggèrent que les gouvernements devraient tenir compte des arrangements résidentiels des personnes âgées et du soutien du réseau familial externe à leur ménage afin d'optimiser l'impact des politiques et des interventions sur leur santé. / While the issue of population aging in sub-Saharan African countries does not seem to be of particular concern at present, the living arrangements of the older people are gradually becoming a major social issue given the rapid growth of their numbers. Generalized formal pension, health insurance and social protection systems for the older people living in most of these countries remain almost non-existent, despite the ratification and adoption of several international conventions and recommendations aiming to improve their living conditions. Given these limitations, the family is most often presented as the main source of support for older people in need through their living arrangements, including cohabitation with others (spouse, adult children, or other relatives), but also through the financial or material transfers received from family living outside their household. The main objective of this thesis is to contribute to the current knowledge on the living and health conditions of the older people, by examining their living arrangements, the resource transfers they might receive from the family network outside their household, the links between these two forms of support and their correlations with the health status of older people living in a sub-Saharan African context (Senegal). To achieve this objective, three empirical scientific articles were written using data from the last three population censuses in Senegal (1988, 2002, and 2013) and from the second Poverty and Family Structure Survey in Senegal conducted in 2010-2011. The first article presents a description of the residential arrangements of older people, especially situations where they live with their spouse and/or adult children, according to gender, and examines their evolution over time. The results suggest that the reality of aging is very different for men and women. Men are more likely to live accompanied by their spouse and at least one adult child, while older women are much more likely to live without a spouse but with an adult child due to widowhood, separation, or divorce. On the other hand, living alone as well as living without a spouse and without another adult remains a very unusual for both older men and women in Senegal. The results also show that over recent decades, there have been no major changes in other cohabitation patterns among the older adults, although there are signs of an increase in the proportion of men living alone or without a spouse or adult, especially among the more recent generations. The second paper aims to improve our understanding of family support mechanisms in the context of developing countries by examining the extent to which older people's living arrangements are associated with the receipt of financial or material transfers from family living outside their household. The results show a net advantage of women over men in terms of receiving positive net family transfers for some residential arrangements. It also shows that living without a husband or adult child significantly increases the likelihood that older women will receive support from non-cohabiting family members, compared to those living with both a spouse and a younger adult child. This pattern, however, was not significant for older men. In the third article of the thesis, which examines the extent to which older adults' household composition and the transfers they receive from non-household family are associated with their health status, it was found that older women who live without a spouse or other adult have a higher likelihood of reporting poorer health than those who live with one or both. In contrast, differences in self-rated health by type of living arrangement were not found to be significant for men. In addition, there was a disadvantage in self-rated health for women who did not receive non-household family transfers, while for men the role of such support was less clear. Overall, the results of this thesis suggest that governments should take into account older adults' living arrangements and non-household family support in order to optimize the impact of policies and interventions on their health status.

Diverses études s’accordent sur le fait que les immigrants, notamment dans les premiers moments succédant leur arrivée, sont en meilleure santé que les natifs, ce que l’on appelle l’« effet de sélection de l’immigrant en bonne santé » (ESIBS). Toutefois, cet effet tend à se dissiper avec la durée de résidence dans le pays d’accueil. Dans la perspective de vérifier si ce fait est toujours avéré au Canada, l’objectif principal de l’étude est de documenter l’évolution de l’ESIBS au cours des 20 dernières années. En outre, nous analysons l’évolution du rôle de la durée de résidence dans la dissipation de l’ESIBS, et en particulier nous cherchons à savoir si cette dissipation s’observe toujours et dans quelle mesure. Pour atteindre notre objectif, nous appuyons nos analyses sur les données issues de tous les passages de l’Enquête sur la santé dans les collectivités canadiennes (ESCC) de 2001 à 2018 (au nombre de 8), excepté celle de 2011-2012 pour laquelle les données sont indisponibles. Pour mesurer la santé des individus, nous nous en remettons principalement à la variable de la santé perçue ou auto-déclarée de l’ESCC. L’analyse descriptive, dans un premier temps, met en lumière le rôle de la durée de résidence sur la santé perçue en croisant cette variable avec une série de variables sociodémographiques, en particulier l’âge, le sexe, l’ethnicité et le revenu. Une analyse multivariée, basée sur le modèle complémentaire log-log (ou cloglog), permet d’étudier de manière plus approfondie les relations entre la variable (dépendante) de santé perçue et ces variables indépendantes. Comme résultats principaux, nous observons que l’ESIBS s’est maintenu tout au long de la période étudiée, de même que l’effet négatif sur la santé de la durée de résidence écoulée. Il semble même que l’ESIBS se soit accentué avec le temps, particulièrement pour les immigrants récents (i.e., durée de résidence < 10 ans). Cette amélioration s’observe plus particulièrement chez les femmes immigrantes récentes en 2018, probablement à cause d’un effet de sélection accru dans ces cohortes d’immigrantes. L’amélioration de la santé perçue des immigrants est également statistiquement significative, mais n’est pas aussi prononcée que pour les immigrantes. Hormis l’état matrimonial et la province de résidence pour lesquels l’effet n’était pas très important dans nos modèles, les autres variables conjuguées avec la durée de résidence permettent d’approfondir notre compréhension de l’ESIBS et de ses relations multivariées avec ses principaux déterminants mesurables. Fait notoire, l’ESIBS se manifeste presqu’exclusivement dans les groupes socioéconomiques les moins avantagés, et pratiquement pas dans les groupes avantagés, indiquant qu’un revenu élevé peut avoir le rôle d’un effet protecteur de la santé, chez les natifs comme chez les immigrants. / Various studies agree that immigrants, especially in the first moments after arrival, are healthier than the native-born, the so-called “healthy immigrant effect” (HIE). However, this effect tends to dissipate with the length of residence in the host country. In order to verify whether this fact is still true in Canada, the main objective of the study is to document the evolution of the HIE over the last 20 years. In addition, we analyze the changing role of residence time in the dissipation of HIE, and in particular whether and to what extent this dissipation is still observed. To achieve our objective, we base our analyses on data from all the Canadian Community Health Survey (CCHS) rounds from 2001 to 2018 (8 in number), except for 2011-2012 for which data are unavailable. To measure the health of individuals, we rely primarily on the perceived or self-reported health variable of the CCHS. The descriptive analysis first highlights the role of length of residence on perceived health by cross-tabulating this variable with a series of socio-demographic variables, in particular age, gender, ethnicity and income. A multivariate analysis based on the complementary log-log (or cloglog) model, allows us to further investigate the relationships between the (dependent self-reported health variable and these independent variables. As main results we observe that the HIE has been maintained throughout the study period, as well as the negative effect of the length of residence on health. It even seems that the HIE has increased over time, especially for recent immigrants (i.e., length of residence <10 years). This improvement is particularly observed among recent immigrant women in 2018, probably due to an increased selection effect in these immigrant cohorts. The improvement in the self-reported health of immigrants is also statistically significant but is not as pronounced as for female immigrants. Apart from marital status and province of residence, for which the effect was not very significant in our models, the other variables combined with length of residence provide further insight into the HIE and its multivariate relationships with its main measurable determinants. Notably, HIE occurs almost exclusively in the lowest socio-economic groups, and almost not in the highest, indicating that high income may act as a protective effect on health, both for natives and immigrants.

Background: Knee osteoarthritis is a degenerative disease characterized by damaged joint tissues (e.g., cartilage) that leads to joint pain, and reduced mobility and quality of life. Various factors are involved in disease progression, including biomechanical, patient-reported outcome and mobility measures. This thesis provides important longitudinal data on the role of these factors in disease progression, and the trajectory of biomechanical factors in persons with knee osteoarthritis. Objectives: (1) Determine the extent to which changes over 2.5 years in knee cartilage thickness and volume in persons with knee osteoarthritis were predicted by the knee adduction and flexion moment peaks, and knee adduction moment impulse and loading frequency. (2) Determine the extent to which changes over 2 years in walking and stair-climbing mobility in women with knee osteoarthritis were predicted by quadriceps strength and power, pain and self-efficacy. (3) Estimate the relative and absolute test-retest reliabilities of biomechanical risk factors for knee osteoarthritis progression. Methods: Data were collected at 3-month intervals during a longitudinal (3-year), observational study of persons with clinical knee osteoarthritis (n=64). Magnetic resonance imaging of the study knee was acquired at the first and last assessments, and used to determine cartilage thickness and volume. Accelerometry and dynamometry data were acquired every 3 months, and used to determine knee loading frequency and knee muscle strength and power, respectively. Walking and stair-climbing mobility, as well as pain and self-efficacy data, were also collected every 3 months. Gait analyses were performed every 6 months, and used to calculate lower-extremity kinematics and kinetics. Results: (1) The knee adduction moment peak and impulse each interacted with body mass index to predict loss of medial tibial cartilage volume over 2.5 years. These interactions suggested that larger joint loads in those with a higher body mass index were associated with greater loss of cartilage volume. (2) In women, lower baseline self-efficacy predicted decreased walking and stair ascent performances over 2 years. Higher baseline pain intensity/frequency also predicted decreased walking performance. Quadriceps strength and power each interacted with self-efficacy to predict worsening stair ascent times. These interactions suggested that the impact of lesser quadriceps strength and power on worsening stair ascent performance was more important among women with lower self-efficacy. (3) Relative reliabilities were high for the knee adduction moment peak and impulse, quadriceps strength and power, and body mass index (i.e., intraclass correlation coefficients >0.80). Absolute reliabilities were high for quadriceps strength and body mass index (standard errors of measurement <15% of the mean). Data supported the use of interventions effective in reducing the knee adduction moment and body mass index, and increasing quadriceps strength, in persons with knee osteoarthritis. Conclusion: Findings from this thesis suggest that biomechanical factors play a modest independent role in the progression of knee osteoarthritis. However, in the presence of other circumstances (e.g., obesity, low self-efficacy, high pain intensity/frequency), biomechanical factors can vastly worsen the disease. Strategies aiming to curb structural progression and improve clinical outcomes in knee osteoarthritis should target biomechanical and clinical outcomes simultaneously. / Thesis / Doctor of Philosophy (PhD) / Knee osteoarthritis is a multifactorial disease whose progression involves worsening joint structure, symptoms, and mobility. Various factors are linked to the progression of this disease, including biomechanical, patient-reported outcome and mobility measures. This thesis provides important information on how these factors, separately and collectively, are involved in worsening disease over time, as well as benchmarks that are useful to clinicians and researchers in interpreting results from interventional or longitudinal research. First, we examined how different elements of knee loading were associated with changes in knee cartilage quantity over time in persons with knee osteoarthritis. Second, we examined how different elements of knee muscle capacity and patient-reported outcomes were related to changes in mobility over time in persons with knee osteoarthritis. Third, we examined the stability over time of various biomechanical risk factors for the progression of knee osteoarthritis. Novel results from this thesis showed that: (1) larger knee loads predicted cartilage loss over 2.5 years in obese individuals with knee osteoarthritis but not in persons of normal weight or overweight; (2) among women with knee osteoarthritis with lower self-efficacy (or confidence), lesser knee muscle capacity (strength, power) was an important predictor of declining stair-climbing performance over 2 years; and (3) clinical interventions that can positively alter knee biomechanics include weight loss, knee muscle strengthening, as well as specific knee surgery and alterations during walking to reduce knee loads. Interventions for knee osteoarthritis should target biomechanical and clinical outcomes simultaneously.

This study compared the immunogenicity of inactivated SARS-CoV-2 vaccines between people living with HIV (PLWH) and HIV-negative individuals. We recruited 120 PLWH and 53 HIV-negative individuals aged 18-59 years who had received an inactivated SARS-CoV-2 vaccine in two Chinese cities between April and June 2021. Blood samples were tested for immunogenicity of the inactivated SARS-CoV-2 vaccines. The prevalence and severity of adverse events associated with SARS-CoV-2 vaccines were similar between PLWH and HIV-negative individuals. The seropositivity of neutralizing activity against authentic SARS-CoV-2, of the total amount of antibody (total antibody) and of S-IgG were 71.3%, 81.9%, and 92.6%, respectively, among fully vaccinated PLWH. Among all participants, PLWH had lower neutralizing activity, total antibody, S-IgG, and T-cell-specific immune response levels, compared to HIV-negative individuals, after controlling for types of vaccine, time interval between first and second dose, time after receiving the second dose, and sociodemographic factors. PLWH with a longer interval since HIV diagnosis, who received their second dose 15-28 days prior to study commencement, and who had an interval of ≥21 days between first and second dose had higher neutralizing activity levels. The immunogenicity of the inactivated SARS-CoV-2 vaccines was lower among PLWH as compared to HIV-negative individuals. Vaccination guideline specific for PLWH should be developed.