Thèse (Ph. D.)--Université Laval, 2008. / Titre de l'écran-titre (visionné le 9 mai 2008). Bibliogr.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 129-1390).

Standard local control theory, which describes Ca²⁺ release during excitation-contraction coupling (ECC), assumes that all Ryanodine Receptor (RyR) complexes are equivalent. Recent data from our laboratory has called this assumption into question. Specifically, we have shown that RyR complexes in ventricular myocytes differ depending on their location within the cell. This, and other data, has led us to hypothesize that similar differences occur within the rat atrial cell. To test this hypothesis, we have triple-labeled enzymatically-isolated, fixed myocytes to examine the distribution and colocalization of RyR, calsequestrin (CSQ), voltage-gated Ca²⁺ channels (Cav1.2), sodium-calcium exchangers (NCX), and caveolin-3 (cav-3). All images were acquired on a wide-field microscope, deconvolved, and subject to extensive analysis, including a novel method of measuring statistical significance of the recorded colocalization values. Overall, eight surface RyR populations were identified, depending on its binding partners. One of these groups, in which RyR, Cav1.2, and NCX colocalize, may provide the structural basis for ‘eager’ sites of Ca²⁺ release in atria, while other groups were defined based on their association with cav-3, and are therefore highly likely to be under the influence of other signaling molecules located within caveolae. Importantly, although a small portion of the surface RyR in atria do colocalize with NCX alone, the majority are tightly linked to Cav1.2 alone or Cav1.2 and NCX together. Therefore, it appears likely that Cav1.2-mediated calcium-induced calcium release (CICR) is the primary method of initiating Ca²⁺ release from the SR during EC coupling. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

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Dans cette thèse nous avons travaillé sur deux systèmes prototypiques: en phase gazeuse et en phase condensée, pour suivre et quantifier l'énergie vibrationnelle dans des modes normaux après excitation vibrationnelle initiale.Pour la phase condensée, ce travail prend en compte l'immersion d'une molécule hôte: l'acide formique immergé dans une matrice d'argon et pour la phase gazeuse avec un cluster de (Cl ... N-Methyl Acétamide..Ar). Après la préparation des conditions initiales utilisant un échantillonnage semi-classique de Wigner, plusieurs trajectoires DFT-MD ont été exécutées pour analyser la relaxation vibrationnelle intra et intermoléculaire.Deux méthodes théoriques ont été utilisées pour suivre l'évolution avec le temps du nombre quantique vibrationnel: une nouvelle méthode basée sur l'étude des spectres d'état vibrationnels (VDOS) comparé avec une méthode plus traditionnelle basée sur l'étude de l'amplitude d'un mouvement spécifique de la molécule (c'est-à-dire distance ou angle). Dans la phase condensée, le rendement quantique du processus d'isomérisation de la molécule d'acide formique a été comparé aux données expérimentales. Nous avons montré que l'excitation vibrationnelle combinée de deux modes implique dans quelques cas l'isomérisation de la molécule d'acide formique. Cette excitation vibrationnelle initiale de l'acide formique a aussi un impact sur la matrice environnante: l'énergie initialement contenue dans l'AF est redistribuée à la matrice, ce qui mène à la déformation et la fonte (transition solide-liquide) de la matrice d'argon.En ce qui concerne la phase gazeuse, nous avons montré que l'excitation vibrationnelle de l'étirement du mouvement N-H du (Cl... NMA) implique la perte (évaporation) systématique de l'atome d'argon.Finalement, les deux modèles (phase gaz ou condensée) ont montré qu'après une excitation vibrationnelle initiale (n=1) d'un mode normal à t=0 de la dynamique, ce mode normal revient au cours de la dynamique dans son état fondamental (n=0). / In the thesis we have studied two prototypical systems in both condensed and gas phase,to follow and quantify the vibrational energy flow through normal modes after vibrational excitation.For the condensed phase, we considered a host Formic Acid immersedin an argon matrix, while for the gas phase we have studied the N-Methyl Acetamid... Cl.. Ar cluster. After the preparation of initial conditions using a semi-classical Wigner sampling, several DFT-MD trajectories have been performed to analyse the Intra/Inter vibrational energy relaxation. Two theoretical methods have been used to follow the evolution with time of the vibrational quantum numbers: a new method based on the study of vibrational density of states (VDOS)compared with a more traditional method based on the study of the amplitude of a specificmotion of the molecule (i.e. distance or angle). Both methods reveal similar results.In the condensed phase, the quantum yield of the trans/cis isomerisation process of theFormic Acid molecule has been compared to the experimental data. We have shown that thevibrational excitation of two combination modes involves in some cases the isomerisation ofthe Formic Acid molecule. This initial vibrational excitation of the Formic Acid has also animpact on the surrounding matrix: the energy initially contained into the FA is redistributedto the matrix leading to the deformation and the melting (solid-liquid transition) of theargon matrix.In the gas phase, we have shown that vibrational excitation of the N-H stretching motion ofthe (Cl...NMA) involves the systematic loss of the argon atom. Finally, the two models have shown that in both condensed or gas phase environment, after the vibrational excitation (n=1) of a normal modeat t=0 of the dynamics, this normal mode comes back in its ground state (n=0).

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Page 12 was not included in the thesis. / <p> This work extends the knowledge about the excited electronic states of thioformaldehyde. Survey work is reported over the wavelength region from 230 nm to 180 nm and four electronic transitions are identified. These are assigned as the 1Al(π,π*), 1B2(n,3s), 1Al(n,3py) and 1B2(n,3pz) systems.</p> <p> A vibrational and rotational analysis of the first two systems has been undertaken. The results of these analyses indicate that the molecule remains planar or nearly so in both the 1Al(π,π*) and the 1B2 (n,3s) transitions. This behaviour is contrasted to that of similar molecules which are known to be non-planar in these electronic states and reasons are offered for this observation. The substituted geometry for thioformaldehyde in the 1B2(n,3s) state has been calculated and provides insight into the changes which occur in the molecule on electronic excitation.</p> / Thesis / Doctor of Philosophy (PhD)

<p> Low-lying nuclear energy levels are analyzed in terms of certain parameters of the correlation between the level spacing and the excitation energy. The statistical properties of the estimates for the parameters arising from a constant nuclear temperature model are examined. Estimates are made for the parameters for the levels of Mn^56 inferred from capture gamma spectra.</p> / Thesis / Master of Science (MSc)