Call number: LD2668 .T4 1985 B34 / Master of Science

L’industrie n’a de cesse de rechercher de nouveaux polymères qui associent plusieurs caractéristiques et propriétés dans un même matériau. Cela permet, en plus d’avoir la propriété initialement souhaitée, d’avoir la possibilité de l’adapter à plusieurs besoins. C’est ainsi que les polymères intelligents sont apparus. Ainsi, ceux-ci sont capables de modifier leurs propriétés de manière importante suite à la modification même relativement faible d’un paramètre extérieur. Cette « petite » modification est appelée stimulus. On retrouve des polymères intelligents dans grand nombre d’applications depuis l’électronique, le biomédical, etc. L’un des grands avantages des polymères est que l’on peut utiliser différents monomères durant leur synthèse pour modifier et rajouter des propriétés au polymère initial. Toutefois, fabriquer un polymère avec au moins deux monomères ne signifie pas toujours que les propriétés obtenues seront la somme ou la demi-somme des propriétés des homopolymères correspondants. Combiner deux polymères intelligents pour créer un copolymère n’implique pas que lecopolymère ainsi créé aura les mêmes propriétés que les deux polymères dont il est issu. Ainsi, les réponses aux deux stimuli ne seront pas nécessairement indépendantes. Déterminer comment on peut associer les monomères ensemble pour comprendre les mécanismes moléculaires qui permettent d’obtenir les propriétés voulues est ce qui importe pour créer de nouvelles applications pour de tels polymères. Cela passe par l’utilisation d’un stimulus contrôle qui va modifier les propriétés du polymère et va agir sur la réponse à un autre stimulus. Dans le cadre de cette thèse, des réactions au dioxyde de carbone ou des réactions photochimiques seront testées pour déterminer si elles ont un impact sur la solubilité, laquelle dépend de la température, de polymères d’intérêt. Il est à noter que la réponse à un stimulus doit être réversible pour pouvoir contrôler efficacement ses propriétés de façon réversible. Si des études à propos de polymères « multi stimuli répondants » sont communes, des études sur la compréhension des mécanismes qui permettent de prédire les propriétés sont rares. Cela permettra d’améliorer grandement notre capacité à concevoir de nouveaux matériaux polymères toujours plus innovants. Parmi les polymères thermosensibles, l’étude dans cette thèse a porté sur trois polymères particulièrement communs et dont les propriétés thermosensibles sont bien connues et utilisées depuis déjà plusieurs dizaines d’années. Il s’agit du poly N-isopropylacrylamide (PNIPAM), du polyméthacrylate de N,N-diméthylaminoéthyle (PDMAEMA) et du polyméthacrylate de N,N-diéthylaminoéthyle (PDEAEMA). Nous avons investigué des systèmes ayant une structure ou architecture bien contrôlée, dans laquelle sont incorporées des unités comonomères sensibles à un stimulus autre que la température. Comprendre comment on peut modifier la solubilité de ces polymères dans l’eau (qui dépend de la température.) est un besoin fondamental pour pouvoir améliorer la conception de futurs polymères dont le contrôle à distance de cette propriété sera amélioré. Cela est d’autant plus important que les applications pratiques de ce type de polymère exploitent généralement cette thermosensibilité. Plus précisément, nous avons eu pour but d’étudier et de comprendre comment une réaction photochimique (isomérisation ou dimérisation réversible) ou la réaction avec le dioxyde de carbone (CO[indice inférieur]2) d’un certain nombre d’unités comonomères peut modifier la thermosensibilité des polymères en solution aqueuse. Dans un premier temps, des unités azobenzène sont insérées régulièrement dans la chaine principale du PNIPAM (chapitre 3). Notre étude a révélé qu’avec cette architecture, la photoisomérisation a peu d’effet sur la température de transition de phase du PNIPAM en raison de la formation de micelles « fleurs », mais qu’elle contrôle l’ouverture du noyau de micelle de façon réversible. Dans l’étude qui suivait (chapitre 4), nous avons démontré que la photodimérisation réversible entre deux unités de coumarine, placées aux bouts de chaine du PNIPAM, permet de convertir le polymère entre les formes linéaire et macrocyclique, et que ce changement topologique de la structure impose un effet réversible sur la température de transition de phase du PNIPAM. En ce qui concerne le contrôle de la thermosensibilité par le CO[indice inférieur]2, une étude quantitative a d’abord été réalisée (chapitre 5), établissant la relation entre le degré de protonation des groupements d’amine tertiaire dans le PDMAEMA et sa température de transition de phase. À partir de cette compréhension sur l’effet qu’une réponse au CO[indice inférieur]2 peut avoir sur la thermosensibilité, nous avons démontré une application des nanogel d’un copolymère à blocs pour la capture du CO[indice inférieur]2 dans l’eau et la libération subséquente du gaz à une température basse (chapitre 6). Pour améliorer la conception de nouveaux polymères, il est nécessaire d’améliorer notre capacité à contrôler à distance leur thermosensibilité en solution. Ainsi, il nous faut déterminer si les réactions, qui ont été déclenchées à distance grâce au dioxyde de carbone ou la lumière, ont permis de modifier les propriétés recherchées. Si tel a été le cas, il est alors nécessaire de vérifier jusqu’à quel point il est possible de modifier la thermosensibilité de cette manière.

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An attempt was made in this study to eliminate the body rocking behavior of a twenty-three-year-old totally blind male, individual, presently classified as moderately retarded. Consequences were placed upon, rocking behavior in seven experimental phases, employing time-out from a positively reinforcing stimulus as a punisher. More specifically, apparatus were designed in such a manner that rocking would result in elimination of the auditory and visual portion of a television, and in a later phase, the auditory portion of a transistor radio.

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Four college student subjects were trained to match graphic figures (A stimuli) to other figures (B stimuli), and then to match the B figures to numerals (C stimuli). Then in a test of application subjects answered simple math problems, presented as novel sample stimuli, by selecting one of the A figures, presented as comparisons. The application test was an analog for the academic task of answering math problems with newly learned Spanish number names. Three subjects performed accurately in the application test, which required the emergence of CA equivalence. All subjects demonstrated equivalence in test sessions after the application test. The study examined whether accuracy, fluency (rate of correct responding), practice, or stability of original relations performance corresponded to test accuracy. Accuracy, fluency, practice and stability corresponded to test accuracy for two subjects. Fluency corresponded to test accuracy for one subject, and stability corresponded to test accuracy for another subject.

Amodal completion enables animals (birds, mammals, but also fish) to perceive partly occluded objects as whole. Most of the studies focusing on the occlusion phenomenon were carried out in a laboratory and were based on either operant conditioning or filial imprinting techniques. This study concentrates on behavior of untrained animals in their natural habitat. Pairwise preferential experiments were used to reveal responses of tits (the great tit, Parus major; the blue tit, Cyanistes caeruleus; the marsh tit, Poecile palustris) to two dummies placed near an experimental and an alternative feeder. The dummies used were the complete dummy of a sparrowhawk and a pigeon, and partly occluded (the lower or upper torso hidden in shrubs) and amputated (only lower or upper torso on the perch) models of sparrowhawks - 15 combinations altogether. The tits considered all variants of torsos to be predators. The great tit and the blue tit perceived the model with occluded lower torso as more dangerous than the one with amputated lower torso. Such discrimination between these torsos requires the ability of amodal completion. The great tit also confirms this ability as it regarded the complete sparrowhawk and the model with occluded lower torso as equally dangerous. In the remaining cases, the number of arrivals...

The purpose of this study was to test the hypothesis that Dieters would have less variation between their pre and post prandial ratings than Non-dieters. We compared 159 female college students’ hunger and satiety ratings before and after their consumption of a 420 calorie portion of Entemann’s Butter French Crumb Cake and a 9oz cup of water. Dieter status was assigned by questionnaire responses to Lowes’ Diet and Weight History Questionnaire (Lowe, Kissileff, 2005) yielding 96 Dieters and 63 Non-dieters. Methods: The primary assumption was that of our 159 participants, the 96 Dieters, because of their lack of familiarity in using hunger and satiation as a behavioral strategy to initiate or stop eating, would demonstrate less of a difference between their fasted and fed ratings than the 63 Non-dieters. We studied whether the participants’ BMI was a factor associated with their hunger and satiety ratings and whether their ‘restraint’ level was correlated with their status as a Dieter or Non-dieter and BMI by group and the number of times participants lost weight [a component of the Early Family Eating Behavior construct. Analyses by diet group status, Restraint level and BMI were performed for the difference in hunger to fullness ratings, Race, SES, Early Family Eating Behavior and for Taste, both Prop {bitter taste} sweet taste and the sweetness of coke. Two constructs, one focused on hunger utilization and one focused on Compensation assessed the 159 participants’ implementation of these concepts. Results: Contrary to expectation, all 159 female college participants rated their fed scores higher than their fasted scores on the Visual Analogue Scale [VAS] question that asked “How Physically Full Do You Feel”. This yielded a significant result with a t of -12.0558 and a p-value of 0.000. We found that there were no significant hunger and fullness rating differences between the Dieters and Non-dieters in this study. BMI varied by group [t of 5.2467 and a p of 0.000] with a [mean of 26.72343 ± .605001] for the 96 dieters compared with a [mean BMI of 22.8090 ±.437262] for the 63 Non-dieters and this was a significant finding. The Dieters’ Restraint scores were higher [mean of 11.14583 ±- .4125177] than the Non-dieters Restraint scores [mean of 6.047619 ± .5016249] and this was a significant finding [t of 7.8499 and a p-value of 0.000]. This finding illustrated the Dieters’ engagement in ‘Restrained Diet Behavior’ and was statistically significant. There were significant differences between the Dieters and Non-dieters in their Early Family Eating Behavior Construct scores (with a mean of 3.052083 ± 1.45363 for the Dieters) and for the Non-dieters, a mean of (1.555556 ± .9466031) and a [t of 7.8619 and a p-value of 0.0000] for the differences between the two groups. A Multiple Regression with Compensation as the dependent variable and Restraint, BMI and group as the independent variables was a significant finding for the use of compensation behaviors as measured by the compensation construct and differential use by the two groups [t of -1.97 and p-value of 0.000]. A Multiple Regression with BMI scores as the dependent variable and group, Restraint, Hunger for the Next meal, Sweet taste ratings, Compensator scores, Early family Eating Behaviors, Diet to Avoid Gaining Weight and ‘I wish I weighed less’ as the independent variables showed significance for the EFEB construct [t of 6.18 p-value of 0.00] and ‘I wish I weighed less’ [t of 3.44 and p-value of 0.0001]. BMI was significantly associated with our participants’ class in college [f of 25.03 and p-value of 0.000] their current Age [f of 14.94 and p-value of 0.0002] and BMI was significant for the number of times our participants lost weight, a dichotomous component on the Early Family Eating Behavior Construct where a score of three weight loss attempts or more scored a 1 and two or fewer weight loss attempts was scored a 0 [f of 16.93 and a p-value of 0.0001]. Implications: It was an important finding that a healthy BMI was achieved and maintained by 101 of the 159 {50 were Dieters and 51 were Non-dieters} students in our study. We also found that eating behavior on the college campus today included a focus on ‘watching what they ate in order not to gain weight’ (Nichter, Ritenbaugh, Nichter, Vuckovic, Aicken, 1995) as well as dieting and non-dieting behaviors. Dieting, historically, was believed to be equivalent to Restrained Eating by Polivy and Herman (Herman, Polivy, 1975; Lowe, Foster, Kerzhnerman, Swain, Wadden, 2001 p254)) but there is now debate as to whether Dieting and Restrained Dieting do not reflect the same eating behaviors in those Non-obese, with BMI’s below 30 (Lowe, Doshi, Katteran, Feig, 2013, p1). It is a positive outcome, we believe, that the 63 {Non-dieters} do not to ‘diet’ for weight loss, but our results also indicate that an educational intervention teaching the utilization of hunger and satiety sensations to those ‘chronically dieting’ (46) students with BMI’s outside the normal range is still necessary on the University campus.

This study investigated the acquisition of food by hand-reared coyotes, Canis latrans, of different social rank in a familiar area with and without novel objects (safe and potentially unsafe conditions). The first objective was to test the hypothesis that dominant animals are more hesitant than subordinates in approaching food in the presence of a novel stimulus. The results were that dominant pups usually were the first to feed in the absence of novel stimulus, and subordinate pups were the first to feed when novel objects were present.