The value of the dipole moment ,μ, of NH in the A³π state was found to be 1.31 ± .03 Debye. This value was determined from data on the Stark effect measured from spectrograms of the A³π- X³Σ-, 3360 Å, band taken on a 3.4 meter grating spectrograph in third order giving a resolution of about 100,000. The theory of the Stark effect in molecules was taken from papers by W. G. Penny5 and Van Vleck and Hill9 . The magnitude of the electric field was determined from the Stark splitting of the hydrogen line Hβ according to the theory given in The Theory of Atomic Spectra6 . In the near future I should be able to complete work on the c’π→a’Δ, 3240 Å, band and give the values of the dipole moments for states c and a as well. Thus it will be possible to determine how the dipole moment changes with electronic configuration. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The suitability of using a Nal crystal as a fast coincidence gamma ray detector was investigated using the multichannel "fast-slow" delayed coincidence method to obtain prompt time resolution curves with a Na²² gamma ray source at Nal temperatures of 170, 185, 200°K. A comparison of the time resolution curve obtained using two NE 102 plastic scintillators (FWHM: 640 psec) with that using a cooled Nal scintillator and a NE 102 scintillator (FWHM: 680-psee) showed that Nal is a satisfactory fast coincidence gamma ray detector at 185°K. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The nuclear magnetic moment μ, and the nuclear electrostatic quadrupole moment Q, were determined from the optical hyperfine structures of Bi. The magnetic moment was calculated for 8 configurations and 14 levels. The quadrupole moment was calculated for 4 configurations and 6 levels. The values of μ that were obtained from one-electron spectra showed good agreement with more precise resonance measurements. The agreement for Q was not quite so good. Good measurements were made for the 5d⁹ 6p configuration, but there is no readily available theory from which to calculate Q for this configuration. The light source used in this investigation was a "condensed" electrodeless discharge, and the spectrograms were taken on a 9.1 metre concave grating spectrograph. Q was found to be -.5(1) barns. Using values of μ that employed information from one-electron spectra, μ was found to be 4.1(1) nuclear magnetons. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Cette thèse traite du problème de la localisation et de l’estimation du mouvement de rotation dans le contexte de l’analyse d’images sphériques. Plus précisément, le but de ce manuscrit est le développement d’algorithmes génériques d’estimation de la rotation 3D entre les images issues de caméras monoculaires conventionnelles et non-conventionnelles (catadioptrique, fisheye, ... ). Les contributions principales de la thèse reposent sur l’exploitation de la riche information d’intensité lumineuse dans l’image, notamment omnidirectionnelle, pour accomplir l’estimation des rotations 3D, y compris les larges. Une première contribution de la thèse est la proposition d’une nouvelle représentation de l’intensité lumineuse de l’image sous forme d’un objet 3D de topologie sphérique. Le calcul de coefficients de la transformée en harmoniques sphériques directement à partir du maillage de l’objet, est accompagné de la décomposition SVD, permettant d’estimer la rotation qui lie les deux images. La deuxième contribution de la thèse est une solution analytique d’estimation de la rotation reposant sur une stratégie dense et indirecte de capture de l’intensité lumineuse de l’image, par le biais de moments photométriques sphériques. Le formalisme théorique établi vise à définir une modélisation analytique de la matrice d’interaction relative aux moments photométriques. En utilisant les propriétés de cette solution, nous proposons trois approches de l’estimation de la rotation 3Dentre deux images sphériques. L’étude de performances menée montrent que nos approches permettant d’estimer efficacement la rotation 3Dde l’image sphérique. Pour finir, plusieurs scénarios d’expérimentations sont proposés et effectués. Ces derniers incluent les environnements intérieurs et extérieurs. / This thesis deals with the problem of location and motion estimation in the context of spherical image analysis. More specifically, the purpose of this manuscript is the development of generic algorithms for estimating 3D rotation between images captured by conventional and non-conventional (catadioptric, fisheye, ...) monocular camera. The main contributions of the thesis are based on the exploitation of the rich intensity information available in the image, notably omnidirectional, to accomplish the estimation of the 3D rotation, including the large ones. A first contribution is to propose a new representation for image intensity as a 3D object of spherical topology. The coefficients of the spherical harmonics transform computation, directly from the object mesh, is accompanied by the SVD decomposition, allowing to estimate the rotation which links the two images. The second contribution of the thesis is a closed form solution for estimating the rotation based on a dense and indirect strategy of perceiving the image intensity, which may be achieved by spherical photometric moments. The established theoretical formalism opts to define an analytical modeling of the interaction matrix relative to the photometric moments. Using the properties of this solution, we propose three approaches to estimate the 3D rotation between two spherical images. The conducted performance study show that our approaches allow to efficiently determine 3D rotation of the spherical image. Finally, several experimental scenarios are proposed and evaluated. This included the indoor and outdoor environments.

Steady and unsteady force and moment experiments were conducted in the Virginia Tech Stability wind tunnel using the Dynamic Plunge-Pitch-Roll (DyPPiR) model mount to perform rapid time-dependent,high-excursion maneuvers. The experiments were performed for a DARPA2 submarine model using three widely spaced 2-force-component loadcells and three tri-axial accelerometers to extract the aerodynamic loads. The DARPA2 model was tested with different body configurations in two different test sections. The body configurations for both the steady and unsteady experiments were the bare body hull, body with sail, body with stern appendages, and body with sail and stern appendages. Tests were done using trips on the bow and sail and with no trips. The bare hull configuration with no trips was the only body configuration tested in the six-foot-square test section with solid walls. All body configurations were tested in the six-foot-square test section with slotted walls that were used to reduce the blockage effects produced by the DyPPiR and model. The steady experiments were performed over a range of angles of attack and roll positions. Data were acquired through the series of angles the body encountered during the unsteady testing (-26° < ± <+26° ). The data for the tripped bare hull gave symmetric results while the data acquired for the bare hull with no trips did not. In the unsteady experiments the model was pitched in ramp maneuvers about the 1/4 chord location of the sail from 0° to -25° and from +25° to 0° in 0.3 seconds. Sine wave maneuvers at 3 Hz were also performed, plunging the model up and down with an amplitude of ±0.375 inches. The steady data agreed within uncertainties with previous data that were limited to the David Taylor Research Center (DTRC). There was a higher level of confidence in the steady data taken with trips due to the symmetry of the data. Effects of the sail and/or stern appendages were studied using the steady and unsteady data, but no quantitative value could be calculated due to the uncertainties. The unsteady data were modeled with a quasi-steady time-lag model, and all the unsteady data were found to lead the quasi-steady data. The unsteady data did have oscillations, but the overall aerodynamic trend was still present. The uncertainties were too large to discuss effects of any appendages, however. / Master of Science

No description available.

Cette étude est consacrée à l'analyse des propriétés électrostatiques et structurales des protéines diffractant à haute résolution. Les travaux se déclinent en deux aspects principaux qui sont, d'une part, l'analyse d'un point de vue fondamental des propriétés dérivées de leur distribution de charge des structures des protéines, et, d'autre part, l'application pratique des méthodes de la cristallographie haute résolution des macromolécules à deux enzymes.Grâce à une analyse structurale et électrostatique de la protéine PfluDING, le mode de fixation du phosphate a été mis en évidence à deux pH différents. En particulier, cette étude a permis de démontrer la présence d'une liaison hydrogène diffuse assurant un mode de fixation identique quelque soit le pH. La seconde enzyme étudiée est la protéine DFPase, capable de dégrader les organophosphorés. La structure de la DFPase obtenue par diffraction X haute résolution et la structure affinée contre des données neutroniques ont été comparées. L'analyse pointe les différences d'interprétation des deux modèles, et permet de proposer un nouveau mécanisme d'action.Les aspects plus fondamentaux de cette étude portent sur les éléments de structure secondaire des protéines : leurs propriétés électrostatiques en termes de moments électriques (moments dipolaires et quadripolaires des hélices et des feuillets), et le réseau des interactions (dont les liaisons H) assurant la cohésion des hélices ont été analysés. Il a été démontré comment certaines interactions entre liaisons peptidiques au sein d'hélices, classiquement représentées comme des liaisons hydrogène, devaient être considérés comme des contacts purement électrostatiques / This study is about the electrostatic and structural properties of proteins diffracting at high X-ray resolution. Two different aspects are tackled which are 1) the analysis of properties derived from their charge distribution, parting from a fundamental point of view and 2) the application of methods used in high resolution macromolecular crystallography to two enzymes of major interest.After the analysis of the structure and electrostatic properties of PfluDING protein, the binding mode of a phosphate ion, located in the active site, was elucidated at two different pH values. Particularly, this study demonstrates that a diffuse hydrogen bond assures the protonation state of the phosphate ion, which is thus identical at each pH value. The second enzyme studied is the proteine DFPase which is capable of hydrolysing nerve agents. A high resolution X-ray structure and a medium resolution neutron structure where compared. The analysis points out the differences between the two models and a new catalytic mechanism could be proposed.The more fundamental aspects of this study are about the secondary structural elements of proteins: their electrostatic properties in terms of electrostatic moments (dipole and quadrupole moments of helices and sheets) as well as the hydrogen bond network assuring the cohesion of helices have been analyzed. It has been shown that certain interactions between peptide units within helices, represented usually as hydrogen bonds, should actually be considered as pure electrostatic contacts

Les appareils orthodontiques appliquent une force prolongée sur les dents, conduisant au mouvement dentaire provoqué, à l'aide d'arcs insérés à l'intérieur d'attaches. Le déplacement dentaire résulte de la biomécanique mais également des réponses biologiques des tissus de soutien. Notre problématique porte sur les efforts mécaniques présents à l'intérieur des attaches orthodontiques, lors de l'insertion d'un fil à mémoire de forme. Nous souhaitons quantifier les forces et moments à l'échelle d'une arcade dentaire en trois dimensions. Notre travail présente un protocole alliant expérimentation et modélisation numérique. Cette méthodologie innovante permet de mettre en évidence les forces et moments appliqués lors de la première phase d'un traitement orthodontique à l'insertion d'un arc nickel-titane de diamètre 0,356 mm (0 .014 inch) dans des gorges de diamètre 0,457x0,635 mm (0.018x0.025) sur une arcade maxillaire, obtenue après segmentation d'une imagerie tridimensionnelle d'un patient. Cette première étape ouvre les portes vers une individualisation des traitements orthodontiques par l'application des efforts mécaniques nécessaires sans être délétères. / Prolonged forces are applied on the teeth by orthodontie deviees, using arch wires inserted into brackets, leading to the orthodontie teeth movements. This displacement is the result of biomechanics but also the biological responses of the surrounding periodontal tissues. Our aim is to quantify the forces and moments applied on the orthodontie brackets, during the insertion of a shape memory alloy, at the scale of a three-dimensional dental arch. Our work presents a protocol combining experimentation and numerical modelling. This innovative methodology enables measuring the forces and moments applied during the first stage of an orthodontie treatment, when a 0.014-inch nickel-titanium arch wire is inserted into a maxillary arch. This first step will help in the definition of individualized treatments, applying the necessarymechanical forces without being iatrogenic.

Um modelo matemático foi desenvolvido, para avaliar o perfil Compton produzido por diferentes distribuições de momento do elétron. Estas distribuições de momento são avaliadas a partir das funções de onda dos elétrons orbitais. Perfis Compton para cinco elementos (Pb POT. 82 , W POT. 74 , Ag POT. 47, Cu POT. 29 e Al POT. 13) e para três ângulos de espalhamento (30º ,15º , 10º) foram calculados usando funções hidrogenóides e Hartree-Fock relativísticas. Experimentalmente usando um de 662 Kev de energia mediu-se, com um detetor GeLi, o perfil Compton desses elementos nas condições geométricas acima, observando-se boa concordância com as distribuições de momento relativístico, calculadas por Biggs, Mendelsohn e Mann. Este acordo, entretanto só foi conseguido quanto utilizamos as correções propostas for Ribberford, que permitem associar o conceito de perfil Compton para qualquer ângulo de espalhamento. Isto mostra que é possível associar univocamente o perfil Compton às distribuições de momento para qualquer ângulo de espalhamento ao contrário do que tradicionalmente se aceitava (apenas 180º). O modelo matemático foi estendido para cálculos de perfis Compton com feixes incidentes e emergentes polarizados. / .

Um modelo matemático foi desenvolvido, para avaliar o perfil Compton produzido por diferentes distribuições de momento do elétron. Estas distribuições de momento são avaliadas a partir das funções de onda dos elétrons orbitais. Perfis Compton para cinco elementos (Pb POT. 82 , W POT. 74 , Ag POT. 47, Cu POT. 29 e Al POT. 13) e para três ângulos de espalhamento (30º ,15º , 10º) foram calculados usando funções hidrogenóides e Hartree-Fock relativísticas. Experimentalmente usando um de 662 Kev de energia mediu-se, com um detetor GeLi, o perfil Compton desses elementos nas condições geométricas acima, observando-se boa concordância com as distribuições de momento relativístico, calculadas por Biggs, Mendelsohn e Mann. Este acordo, entretanto só foi conseguido quanto utilizamos as correções propostas for Ribberford, que permitem associar o conceito de perfil Compton para qualquer ângulo de espalhamento. Isto mostra que é possível associar univocamente o perfil Compton às distribuições de momento para qualquer ângulo de espalhamento ao contrário do que tradicionalmente se aceitava (apenas 180º). O modelo matemático foi estendido para cálculos de perfis Compton com feixes incidentes e emergentes polarizados. / .