3 resultados para Multiple Additive Regression Trees (MART)

em QSpace: Queen's University - Canada


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This work outlines the theoretical advantages of multivariate methods in biomechanical data, validates the proposed methods and outlines new clinical findings relating to knee osteoarthritis that were made possible by this approach. New techniques were based on existing multivariate approaches, Partial Least Squares (PLS) and Non-negative Matrix Factorization (NMF) and validated using existing data sets. The new techniques developed, PCA-PLS-LDA (Principal Component Analysis – Partial Least Squares – Linear Discriminant Analysis), PCA-PLS-MLR (Principal Component Analysis – Partial Least Squares –Multiple Linear Regression) and Waveform Similarity (based on NMF) were developed to address the challenging characteristics of biomechanical data, variability and correlation. As a result, these new structure-seeking technique revealed new clinical findings. The first new clinical finding relates to the relationship between pain, radiographic severity and mechanics. Simultaneous analysis of pain and radiographic severity outcomes, a first in biomechanics, revealed that the knee adduction moment’s relationship to radiographic features is mediated by pain in subjects with moderate osteoarthritis. The second clinical finding was quantifying the importance of neuromuscular patterns in brace effectiveness for patients with knee osteoarthritis. I found that brace effectiveness was more related to the patient’s unbraced neuromuscular patterns than it was to mechanics, and that these neuromuscular patterns were more complicated than simply increased overall muscle activity, as previously thought.

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Since 2008, more than 6000 Bhutanese refugees have been resettled in over 21 communities across Canada, with nearly 300 individuals residing in Ottawa. This resettling process is associated with physical and psychological stress, as individuals acclimatize to a new country. A lack of understanding of the impact of this transition exists. This study assessed the relationship between coping strategies and psychological well-being of Bhutanese refugees resettled in Ottawa. A cross sectional survey of a representative sample of Bhutanese adults (n = 110) was conducted between November and December 2015. Coping strategies and psychological well-being were measured using the Brief COPE and General Well-being (GWB) scales. The total GWB mean score of 69.04 ± 12.09 suggests that respondents were in moderate distress. GWB did not significantly differ by sex, marital status, religion, employment, part time or full time job, or length of stay in Canada. Using multiple linear regression, significant independent variables from univariate analysis with GWB (age, education, positive reframing, self-blame and venting) were modeled to determine the best predictors of general well-being (GWB, F (11, 96) = 3.61, p < .001, R² = 21.2%). Higher levels of education and positive reframing were associated with greater GWB scores while self-blame and ages 41-50 were inversely associated with general well-being. It was found that above 66% of the unemployed participants were from age groups 41 and above. This finding suggests that career guidance services and vocational training to address unemployment may benefit this community. Nurses can provide support and counselling to assist refugees to minimize the use of negative coping strategies like self-blame and venting and promote positive coping strategies. Further, collaboration between nurses, other interdisciplinary professionals and community organizations is necessary to address social determinants of health and enhance refugee psychological well-being.

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Purpose: Across Canada, undergraduate university students are one of the highest alcohol-consuming populations. Many students engage in hazardous drinking and are at risk for negative health and social consequences. Social Norms Theory suggests that students’ overestimation of drinking norms can result in an increase in their drinking behaviour. As of yet, none of the literature addresses the possible link between drinking norm (mis)perception and hazardous drinking in a Canadian undergraduate context. This is the first Canadian study to examine this potential association in first-year undergraduate students across multiple universities using gender as an effect modifier. Methods: Using data collected by the Caring Campus Project, for 2347 first-year students from three Canadian universities, I evaluated the prevalence of drinking norm misperceptions by site and gender. Using multiple-logistic regression models, I analyzed the relationship between misperceived drinking norms and hazardous drinking behaviours (assessed via AUDIT-C). Results: The proportion of students who overestimated drinking and binge drinking frequency norms varied by site and gender. There was a positive relationship between overestimated drinking/ binge drinking frequency norms and hazardous drinking, modified by gender. Controlling for living arrangement and site, the odds of female students being hazardous drinkers increased by a factor of 2.27 (CI: 1.73-2.99) when the drinking frequency norm was overestimated. A non-significant association was found for male students. Among female students, when living arrangement and site were controlled, the odds of being a hazardous drinker were 1.83 (0.84-3.95) and 2.69 (1.24-5.83) times greater when the drinking frequency norm was perceived at “2-4 times per month” and “2 or more times per week”, respectively. Among male students, when living arrangement, previous residence and site were controlled, the odds of being a hazardous drinker were 4.03 (2.62-6.19) and 8.54 (5.41-13.49) times greater when the binge drinking frequency norm was perceived at “2-4 times per month” and “2 or more times per week”, respectively. Conclusion: This novel study enhances the understanding of the association between (mis)perceived drinking norms and drinking behaviours in Canadian undergraduate students. The demonstrated importance of gender and site provides a strong impetus for Canadian universities to develop targeted alcohol reduction interventions.