En esta tesis se han mostrado los conceptos fundamentales de la metodología multinivel, y se han desarrollado los enfoques frecuentista y bayesiano para el análisis de los modelos multinivel logísticos de 2 niveles. Se ha realizado un estudio comparativo entre un método de análisis que no tiene en cuenta la estructura jerárquica de los datos y los métodos multinivel para el análisis de los factores de riesgo de las sibilancias recurrentes en lactantes. Se han comparado los enfoques frecuentista y bayesiano tanto para el análisis de los modelos multinivel de 2 niveles completamente aleatorios, con intercepto y pendiente aleatoria, como para los modelos de 2 niveles con intercepto aleatorio y variables explicativas del primer nivel y del segundo nivel. El resultado obtenido es que los modelos multinivel mejoran la precisión de las estimaciones de los parámetros respecto a los modelos que no tienen en cuenta la estructura jerárquica de los datos / This thesis shows the fundamental concepts of the multilevel methodology, and the frequentist and bayesian approaches for multilevel models for binary responses. A comparative study between a method of analysis which does not consider the hierarchical structure of the data and two multilevel methods when applied to study of wheezing and its risk factors in the first year of life. A bayesian and frequentist methods were compared for fitting a two-level random slope model, with random intercept and random slope, and for a random intercept model with a two level explanatory variables. The results show that the multilevel models improve estimations accuracy of parameters regarding models which do not consider the hierarchical structure of the data.

Increasing salinity is a worldwide problem, but the knowledge on how salt enters the roots of plants remains largely unknown. Non-selective cation channels (NSCCs) have been suggested to be the major pathway for the entry of sodium ions (Na+) in several species. The hypothesis tested in this research is that PQ loop (PQL) proteins could form NSCCs, mediate some of the Na+ influx into the root and contribute to ion accumulation and the inhibition of growth in saline conditions. This is based on previous preliminary evidence indicating similarities in the properties of NSCC currents and currents mediated by PQL proteins, such as the inhibition of an inward cation current mediated by PQL proteins by high external calcium and pH acidification. PQL family members belonging to clade one in Arabidopsis and barley were characterized using a reverse genetics approach, electrophysiology and high-throughput phenotyping. Expression of AtPQL1a and HvPQL1 in HEK293 cells increased Na+ and K+ inward currents in whole cell membranes. However, when GFP-tagged PQL proteins were transiently overexpressed in tobacco leaf cells, the proteins appeared to localize to intracellular membrane structures. Based on q-RT-PCR, the levels of mRNA of AtPQL1a, AtPQL1b and AtPQL1c is higher in salt stressed plants compared to control plants in the shoot tissue, while the mRNA levels in the root tissue did not change in response to stress. Salt stress responses of lines with altered expression of AtPQL1a, AtPQL1b and AtPQL1c were examined using RGB and chlorophyll fluorescence imaging of plants growing in soil in a controlled environment chamber. Decreases in the levels of expression of AtPQL1a, AtPQL1b and AtPQL1c resulted in larger rosettes, when measured seven days after salt stress imposition. Interestingly, overexpression of AtPQL1a also resulted in plants having larger rosettes in salt stress conditions. Differences between the mutants and the wild-type plants were not observed at earlier stages, suggesting that PQLs might be involved in long-term responses to salt stress. These results contribute towards a better understanding of the role of PQLs in salinity tolerance and provide new targets for crop improvement.

Background: Despite a longstanding debate regarding personal choice towards death and dying, MAiD was legalized in Canada on June 17th, 2016. Since its integration into the healthcare system, there has been a dearth of literature surrounding providers’ experience with the procedure. Healthcare providers are uniquely positioned within the context of the MAiD experience. Aim: To explore the experiences of health care providers (nurses and physicians) caring for patients undergoing MAiD as well as to explore the relationships between the concepts, Moral Distress (MD), Professional Quality of Life (Burnout (BU), Secondary Traumatic Stress (STS) and Compassion Satisfaction (CS)), and Intent to Turnover (TO). Design: This explorative and descriptive cross-sectional study consisted of a self-reported survey that uses both scale items and open-ended questions. Setting/ Participants: The target population included all nurses and physicians who were active members of a targeted Regional MAiD Network practicing within a designated geographical location within Canada. Results: N=38 Questionnaires completed. The averages of our measured constructs include Moral Distress (Composite) x= 2.9 (SD 2.03), Moral Distress (Frequency): x= 1,18 (SD .102), Moral Distress (Intensity): x= 1.61 (SD .28) Burnout: x= 2.08 (SD 0.5), Secondary Traumatic Stress x= 2.22 (SD 0.48), Compassion Satisfaction x= 4.18 (SD 0.43) and Turnover Intent: x= 2.22 (SD 0.77). Significant positive correlations were found between inter-scale constructs of Moral Distress (Composite, Frequency, and Intensity), Moral Distress, Burnout, and Secondary Traumatic Stress, and between Burnout and Turnover Intent. Significant negative correlations were also found between Professional Quality of life Inter-Scale constructs of Compassion Satisfaction and Burnout as well as between Compassion Satisfaction and Turnover Intent. Conclusion: MAiD providers in our study expressed feelings of their work being “rewarding” and “deeply satisfying”, further reflective in their below-average rates of Moral Distress, Burnout, Secondary Traumatic Stress, Turnover Intent, and higher-than-average rates of Compassion Satisfaction. Although the procedure remains controversial, these participants expressed enjoying their work. These reported positive aspects of their roles persisted despite the challenges the COVID-19 pandemic presented.

This study involves investigating the impacts of ignoring nested data structure in Rasch/1PL item response theory (IRT) model via a two-level and three-level hierarchical generalized linear model (HGLM). Currently, Rasch/IRT models are frequently used in educational and psychometric researches for data obtained from multistage cluster samplings, which are more likely to violate the assumption of independent observations of examinees required by Rasch/IRT models. The violation of the assumption of independent observation, however, is ignored in the current standard practices which apply the standard Rasch/IRT for the large scale testing data. A simulation study (Study Two) was conducted to address this issue of the effects of ignoring nested data structure in Rasch/IRT models under various conditions, following a simulation study (Study One) to compare the performances of three methods, such as Penalized Quasi-Likelihood (PQL), Laplace approximation, and Adaptive Gaussian Quadrature (AGQ), commonly used in HGLM in terms of accuracy and efficiency in estimating parameters. As expected, PQL tended to produce seriously biased item difficulty estimates and ability variance estimates whereas almost unbiased for Laplace or AGQ for both 2-level and 3-level analysis. As for the root mean squared errors (RMSE), three methods performed without substantive differences for item difficulty estimates and ability variance estimates in both 2-level and 3-level analysis, except for level-2 ability variance estimates in 3-level analysis. Generally, Laplace and AGQ performed similarly well in terms of bias and RMSE of parameter estimates; however, Laplace exhibited a much lower convergence rate than that of AGQ in 3-level analyses. The results from AGQ, which produced the most accurate and stable results among three computational methods, demonstrated that the theoretical standard errors (SE), i.e., asymptotic information-based SEs, were underestimated by at most 34% when 2-level analyses were used for the data generated from 3-level model, implying that the Type I error rate would be inflated when the nested data structures are ignored in Rasch/IRT models. The underestimated theoretical standard errors were substantively more severe as the true ability variance increased or the number of students within schools increased regardless of test length or the number of schools. / Ph. D.