The chloride current-voltage characteristics of the membrane of sartorius fibers from Xenopus laevis were studied using a three microelectrode voltage clamp system. In fibers with normal resting potentials (-70 to -90 mV) and in fibers depolarized in 115 mM KC1 (resting potential -20 mV) the direction and degree of steady state rectification depended on extracellular pH. In alkaline solutions (pH 8.4) the current rectified outwards; with large hyperpolarizations the current recorded in normally polarized fibers was sometimes seen to diminish as the voltage was made extremely negative (the current-voltage relation exhibited a negative slope). In the depolarizing region (in depolarized fibers) the slope of the I-V relation became constant (limiting conductance) in alkaline solutions. In acid solutions (pH 5.4) the current rectified inwards with hyperpolarization and reached a limiting value with depolarization. Chloride currents decay ('inactivate') following changes of membrane potential from the resting potential (for both polarized and depolarized fibers). The kinetics of current relaxation exhibited voltage-dependent time constants depending on the size of the voltage step with a sensitivity of about -1.5 msec/mV but were independent of absolute membrane potential and external pH. Inactivation of chloride conductance was studied in two-pulse (conditioning (v₁) and test (V₂), pulses) voltage clamp experiments. In variable experiments the dependence of the initial current at the onset of was sigmoidally related to (inactivation relation). The slope of the inactivation relation was twice as steep in acid as in alkaline solutions, but was independent of the resting potential. In variable V₂ experiments, the current-voltage relation was linear over a wide voltage range and for different values of V₁, the instantaneous I-V relations converged in the outward current region; they also had zero-current potentials that became increasingly negative with respect to the holding potential as V₁ was made negative. Instantaneous chloride currents and the kinetics of current relaxation were found to depend on initial conditions when the membrane potential was changed under non-stationary conditions. The inactivation and recovery of initial current had similar timecourses as did the prolongation and recovery of the time constants. Initial currents recovered from conditioning with an exponential or sigmoid timecourse. Relaxation time constants exhibited a similar recovery pattern. The decline of initial current was initially exponentially dependent on the duration of conditioning. The time constant increased sigmoidally, or exponentially as the duration of conditioning increased. Using the data from variable conditioning step and variable test step experiments a manifold (or state space representation) was constructed that enables much of the current-voltage behavior of the chloride permeation system to be predicted. Currents recorded in voltage clamp experiments can be visualized as time-dependent flows along trajectories that are determined by the voltage. The rectification of the steady state and instantaneous current-voltage relations are related to the dispersion of the trajectories. The dependence of time constants of current transients can also be accounted for by the manifold. The results are examined in light of models for channel behavior. The instantaneous I-V characteristics exhibit some properties of channels of the electrodiffusion type. The steady state current-voltage relations are qualitatively similar to those of a model incorporating a particle within the chloride channel that either blocks or unblocks it depending on the extracellular pH. The dependence of relaxation kinetics on the size of the voltage step and on initial conditions suggest the participation of a molecule acting in a catalytic role controlling the relaxation of current transients. / Science, Faculty of / Mathematics, Department of / Unknown

Covering relaxation algorithms were first developed by Granot et al for solving positive 0-1 polynomial programming (PP) problems which maximize a linear objective function in 0-1 variables subject to a set of polynomial inequalities containing only positive coefficients ["Covering Relaxation for Positive 0-1 Polynomial Programs", Management Science, Vol. 25, (1979)]. The covering relaxation approach appears to cope successfully with the non-linearity of the PP problem and is able to solve modest size (40 variables and 40 constraints) sparse PP problems. This thesis develops a more sophisticated covering relaxation method which accelerates the performance of this approach, especially when solving PP problems with many terms in a constraint. Both the original covering relaxation algorithm and the newly introduced accelerated algorithm are cutting plane algorithms in which the relaxed problem is the set covering problem and the cutting planes are linear covering constraints. In contrast with other cutting plane methods in integer programming, the accelerated covering relaxation algorithm developed in this thesis does not solve the relaxed problem to optimality after the introduction of the cutting plane constraints. Rather, the augmented relaxed problem is first solved approximately and only if the approximate solution is feasible to the PP problem is the relaxed problem solved to optimality. The promise of this approach stems from the excellent performance of approximate procedures for solving integer programming problems. Indeed, the extensive computational experiments that were performed show that the accelerated algorithm has reduced both the number of set covering problems to be solved and the overall time required to solve a PP problem. The improvements are particularly significant for PP problems with many terms in a constraint. / Science, Faculty of / Computer Science, Department of / Graduate

The frequency dependence and temperature dependence of the complex dielectric constant of water is of great interest. The temperature dependence of the physical properties of water given in the literature, specific heat, thermal conductivity, electric conductivity, pH, etc. are compared to the a. c. (microwave) and d. c. conductivity of water with a variety of concentration of different substances such as HC1, NaCl, HaS04, etc. When each of these properties is plotted versus inverse absolute temperature, it can be seen that each sample shows "transition temperatures". In this work, Slater's perturbation equations for a resonant microwave cavity were used to analyze the experimental results for the microwave data.

No description available.

Une alimentation sous-optimale est un facteur de risque dans le développement de conditions médicales chroniques. Malgré cela, peu de Québécois rencontrent les recommandations en matière de saine alimentation. Depuis les dernières années, on note une transition vers l'approche non restrictive en saine alimentation, qui promeut l'adoption de saines habitudes alimentaires sans mettre l'accent sur le contrôle du poids, afin de favoriser des comportements alimentaires positifs. Ainsi, il est important d'identifier des déterminants de la saine alimentation qui sont compatibles avec l'approche non restrictive, afin de mieux cibler les interventions dans ce contexte. Les activités de relaxation, telles que le yoga et la méditation, sont une avenue intéressante à explorer, car elles mettent l'accent sur l'écoute du corps et la pleine conscience. Ce mémoire présente un portrait de la littérature scientifique sur les liens entre la pratique d'activités de relaxation, la qualité alimentaire, les comportements alimentaires et leur régulation. L'article qu'il contient rapporte les résultats d'une étude d'association effectuée auprès d'adultes québécois dans le cadre du projet de recherche PRÉDISE. Il révèle que les personnes pratiquant des activités de relaxation ont une meilleure qualité alimentaire, de meilleures compétences en alimentation intuitive, plus précisément au niveau de la sous-échelle « Congruence entre les besoins du corps et les apports alimentaires », et régulent leurs comportements alimentaires de façon plus autodéterminée que celles qui n'en pratiquent pas. Le modèle de médiation exploratoire qui y est présenté soulève également la possibilité que ces différences, au niveau des comportements alimentaires et de leur régulation, expliquent l'avantage observé en termes de qualité alimentaire. Ainsi, les travaux présentés dans ce mémoire identifient la pratique d'activités de relaxation comme un déterminant potentiel de la saine alimentation. Ils permettent également une meilleure compréhension des liens entre ce type de pratique et la qualité alimentaire, en soulignant l'importance de considérer les compétences en alimentation intuitive et le type de régulation des comportements alimentaires dans cette association. / Sub-optimal diet quality is a risk factor in the development of chronic health conditions. Despite this, few Quebecers meet healthy eating recommendations. In recent years, a transition towards the non-diet approach, which encourages healthy eating from a weight-inclusive lens to foster positive eating behaviours, has taken place. Therefore, it is important to identify determinants of healthy eating that are compatible with the non-diet approach to better focus interventions. In this context, mind-body practices, such as yoga and meditation, which emphasize body awareness and mindfulness, are an interesting avenue to explore. This Master's thesis presents a review of the current scientific evidence pertaining to the links between mind-body practice engagement, diet quality, eating behaviours and regulation of eating behaviours. The included article describes the results of a study conducted as part of the PRÉDISE research project, among a sample of adults living in the province of Quebec. Its results show that individuals who engage in mind-body practices (practitioners), have a better diet quality, better intuitive eating skills in terms of the "Body-Food Choice Congruence" subscale, and a more self-determined style of eating behaviour regulation than those who do not engage in these practices (non-practitioners). It also includes an exploratory mediation model which raises the possibility that these differences in terms of intuitive eating and eating behaviour regulation styles could explain the differences observed in terms of diet quality. Therefore, the work presented as part of this thesis identifies mind-body practice engagement as a potential determinant of healthy eating and allows for an increased understanding of the relationship between mind-body practice engagement and diet quality, by highlighting the importance of considering intuitive eating and eating behaviour regulation styles in this association.

No description available.

Peyronie's disease (PD) affects the tunica albuginea of the penis with a formation of dense and fibrous plaques. The plaques can cause a variety of symptoms in the patient such as pain during erection, erectile dysfunction, and penile disfigurement. There are many treatment options available, though none without disadvantages. Quantification of the material properties of the tunica tissue can inform potentially improved treatments. In this study tunica tissue (n=5) from donors were tested biaxially along the circumferential and longitudinal directions to a specified load magnitude and maintained at a fixed displacement for 30 minutes to allow for stress relaxation. The loading and relaxation were then repeated for a second time. Stiffness, Young's Modulus, strain at inflection point between the toe region and linear region on the stress-strain curve, as well as percent stress relaxation after 30 minutes were compared between anatomic directions and ramp number. Only stiffness and percent relaxation showed a statistically significant difference between ramps 1 and 2, regardless of direction (p = 0.012). The results from this study report the baseline data of the biaxial mechanical properties of the tunica albuginea to be used for future comparisons to the properties of PD and graft tissue. / Master of Science / Peyronie’s disease (PD) affects a layer of tissue in the penis known as the tunica albuginea. Dense and fibrous plaques form on this layer which can cause pain during erection, erectile dysfunction, and penile disfigurement. There are many treatment options available, though none without disadvantages. In this study tunica tissues from donors were tested in order to find the material properties of the tissue to improve treatments. The tissue samples were pulled in tension in two directions simultaneously to a specified load magnitude and then held at a fixed displacement for 30 minutes. This protocol was then repeated a second time. The material properties of the tissue were compared between the anatomic directions of the tissue was well as protocol number. The results from this study report the baseline data of the biaxial mechanical properties of the tunica albuginea to be used for future comparisons to the properties of PD and graft tissue.

This study investigated the effects of enhanced perception of control on adherence to a worksite relaxation program. The design was a 2 x 2 between subjects manipulation in which desire for control was an individual difference measure and condition was an experimenter assigned treatment. Subjects were randomly assigned to either Perceived Control (PC) condition or a Standard Program (SP) format. The perception of control manipulation was operationalized as the opportunity for important choices in the program. It was hypothesized that subjects in the perceived control condition would adhere significantly better than those in the standard program condition. An interaction between motivation for control and condition was predicted such that subjects high in desire for control would adhere best in the PC condition, and the converse would hold for those low in motivation for control. Sixty university staff and faculty who volunteered for a relaxation training program were offered an orientation and three training sessions, and were given the opportunity of attending four practice sessions. Dependent measures of adherence included attendance and self-monitoring of home relaxation practice. Dependent variables of secondary interest included pre-post measures of anxiety, physical symptoms and perception of control over health. Analysis of the adherence measures demonstrated a significant effect of condition on attendance at training sessions only, p < .0045, accounted for by the great number of drop-outs in the SP condition. There were no significant differences between conditions on other adherence measures. There was no statistically significant effect of condition on dropping out, per se. A ceiling effect on attendance by those subjects who continued in the program obscured any other differences. There was no evidence of an interaction between condition and desire for control on adherence. / Master of Science

The present study compared live versus taped and self relaxation training conditions under high and low expectancy conditions. Anxious college students (N = 54) were stratified according to scores on the screening instrument employed (S-R Inventory of General Trait Anxiousness) and randomly assigned to one of six training/expectancy conditions for two relaxation sessions: live-high, taped-high, self-high, live-low, taped-low, or self-low. Physiological measures of anxiety included heart rate, spontaneous skin fluctuation responses, and finger pulse volume amplitude. The Anxiety Differential was used to assess self report of anxiety. Finally, within-session relaxation ratings were elicited to evaluate differences between live and taped training conditions. Results indicated that subjects in the high expectancy condition showed a significantly greater decrease in heart rate and spontaneous skin fluctuation responses than low expectancy subjects, but no differences were found with the self report measure of anxiety. There were no differences due to type of training (live, taped, self). Within-session relaxation ratings indicated increased relaxation across sessions, but no differences across type of training. Results were discussed in terms of the multidimensionality of the anxiety construct and. the role of expectancy factors in progressive muscle relaxation procedures. / M.S.

Une alimentation sous-optimale est un facteur de risque dans le développement de conditions médicales chroniques. Malgré cela, peu de Québécois rencontrent les recommandations en matière de saine alimentation. Depuis les dernières années, on note une transition vers l'approche non restrictive en saine alimentation, qui promeut l'adoption de saines habitudes alimentaires sans mettre l'accent sur le contrôle du poids, afin de favoriser des comportements alimentaires positifs. Ainsi, il est important d'identifier des déterminants de la saine alimentation qui sont compatibles avec l'approche non restrictive, afin de mieux cibler les interventions dans ce contexte. Les activités de relaxation, telles que le yoga et la méditation, sont une avenue intéressante à explorer, car elles mettent l'accent sur l'écoute du corps et la pleine conscience. Ce mémoire présente un portrait de la littérature scientifique sur les liens entre la pratique d'activités de relaxation, la qualité alimentaire, les comportements alimentaires et leur régulation. L'article qu'il contient rapporte les résultats d'une étude d'association effectuée auprès d'adultes québécois dans le cadre du projet de recherche PRÉDISE. Il révèle que les personnes pratiquant des activités de relaxation ont une meilleure qualité alimentaire, de meilleures compétences en alimentation intuitive, plus précisément au niveau de la sous-échelle « Congruence entre les besoins du corps et les apports alimentaires », et régulent leurs comportements alimentaires de façon plus autodéterminée que celles qui n'en pratiquent pas. Le modèle de médiation exploratoire qui y est présenté soulève également la possibilité que ces différences, au niveau des comportements alimentaires et de leur régulation, expliquent l'avantage observé en termes de qualité alimentaire. Ainsi, les travaux présentés dans ce mémoire identifient la pratique d'activités de relaxation comme un déterminant potentiel de la saine alimentation. Ils permettent également une meilleure compréhension des liens entre ce type de pratique et la qualité alimentaire, en soulignant l'importance de considérer les compétences en alimentation intuitive et le type de régulation des comportements alimentaires dans cette association. / Sub-optimal diet quality is a risk factor in the development of chronic health conditions. Despite this, few Quebecers meet healthy eating recommendations. In recent years, a transition towards the non-diet approach, which encourages healthy eating from a weight-inclusive lens to foster positive eating behaviours, has taken place. Therefore, it is important to identify determinants of healthy eating that are compatible with the non-diet approach to better focus interventions. In this context, mind-body practices, such as yoga and meditation, which emphasize body awareness and mindfulness, are an interesting avenue to explore. This Master's thesis presents a review of the current scientific evidence pertaining to the links between mind-body practice engagement, diet quality, eating behaviours and regulation of eating behaviours. The included article describes the results of a study conducted as part of the PRÉDISE research project, among a sample of adults living in the province of Quebec. Its results show that individuals who engage in mind-body practices (practitioners), have a better diet quality, better intuitive eating skills in terms of the "Body-Food Choice Congruence" subscale, and a more self-determined style of eating behaviour regulation than those who do not engage in these practices (non-practitioners). It also includes an exploratory mediation model which raises the possibility that these differences in terms of intuitive eating and eating behaviour regulation styles could explain the differences observed in terms of diet quality. Therefore, the work presented as part of this thesis identifies mind-body practice engagement as a potential determinant of healthy eating and allows for an increased understanding of the relationship between mind-body practice engagement and diet quality, by highlighting the importance of considering intuitive eating and eating behaviour regulation styles in this association.