Atom interferometers and gyroscopes are highly sensitive atom-optical devices which are capable to measure inertial, gravitational, electric, and magnetic fields and to sense rotations. Theoretically, the signal-to-noise ratio of atomic gyroscopes is about a hundred billion times more than that of their optical counterparts for the same particle flux and the enclosed area. Ultra cold atoms from a Bose-Einstein condensate (BEC) can easily be controlled and coherently manipulated on small chips by laser pulses. Atom-optical devices will therefore play a significant role in fundamental research, precision measurements, and navigation systems. In BEC-based atom interferometers, a BEC in a trap is split by using laser pulses, the split clouds are allowed to evolve, they are reflected, and then recombined by laser pulses to observe interference. The split clouds accumulate spatial phase because of the trap and the nonlinearity caused by atom-atom interactions. A velocity mismatch due to reflection laser pulses also introduces a phase gradient across each cloud. These factors contribute to spatial relative phase between the clouds at recombination, causing the loss of contrast of the interference fringes. The main objective of this dissertation is to study the dynamics of a split condensate in atom Michelson interferometers, investigate the effect of trap frequencies, nonlinearity, and the velocity mismatch on the contrast, and to obtain the best theoretical limit of performance in terms of the experimental parameters: trap frequencies, number of atoms, and the velocity imparted to the clouds by the splitting laser pulses.

In this thesis, we numerically investigate quantum turbulence in trapped atomic Bose-Einstein condensates (BECs). We first discuss the appropriate qualitative characterization of turbulence in these systems, showing the limitation of analogies with classical hydrodynamics and turbulence in large superfluid Helium experiments. Due to their lack of available length scales, our investigated systems can only fit the ultraquantum (or Vinen) type of quantum turbulence. Secondly, we propose experimentally feasible schemes for more controlled investigations of turbulence making use of dynamical instability of multicharged vortices as an onset for complex vortex dynamics. In two dimensions, our suggested scheme allows control over vortex polarization in the harmonically trapped system. This setup is then used to study how turbulence decays in such a scenario, through the phenomenological modeling of a vortex-number rate equation. As a consequence, we were able to identify that vortex annihilation in these trapped systems happens through a four-vortex process. For three dimensions, we have first provided a study on the decay of a quadruply-charged vortex, also in a harmonically trapped BEC. Having this setting as a comparison point, we propose a quasi-isotropic turbulent system, starting from a phase-imprinted initial state of two doubly-charged, anti-parallel vortices. The vortex turbulence arisen from such configuration was shown to agree with the Vinen turbulent regime, after we characterized specific features of its decay, such as the energy spectrum [E(k) ∼ k1] and the time evolution of the vortex-line density [L(t) ∼ t1]. Although these features have been frequently verified in the context of superfluid Helium turbulence, here this identification was for the first time done for realistic, trapped atomic BECs. / Nesta tese, investigamos numericamente a turbulência quântica em condensados de Bose- Einstein (BECs) aprisionados. Discutimos, inicialmente, a caracterização qualitativa apropriada para estes sistemas, mostrando a limitação de analogias tipicamente feitas com hidrodinâmica clássica e turbulência em grandes sistemas com Hélio superfluido. Devido às suas limitadas escalas espaciais, os sistemas investigados somente podem exibir o tipo de turbulência conhecida como ultra-quântica (ou de Vinen). Em seguida, propomos sistemas experimentalmente factíveis que permitem investigações mais controladas da turbulência, fazendo uso da instabilidade dinâmica de vórtices multi-carregados como ponto de partida para geração de dinâmicas complexas. Em duas dimensões, nossa proposta permite controle sobre a polarização de vórtices em sistemas aprisionados em potencial harmônico. Este arranjo é então utilizado no estudo do decaimento da turbulência nesse contexto, através de um modelo fenomenológico para equação que descreve a taxa de variação do número de vórtices. Como consequência, pudemos verificar que a aniquilação de vórtices dá-se através de um processo que envolve quatro vórtices. Em três dimensões, apresentamos um estudo do decaimento de um vórtice de carga topológica quatro, também em potencial harmônico. Mantendo em mente esse sistema a título de comparação, propomos um cenário turbulento, quase-isotrópico, partindo de um estado inicial formado por dois vórtices duplamente carregados, mas orientados anti-paralelamente. Verificamos que a turbulência decorrente desse arranjo coincide com a regime de Vinen analisando características do seu decaimento, especificamente obtendo o espectro de energia [E(k) ∼ k1] e evolução temporal da densidade de linhas de vórtices [L(t) ∼ t1]. Apesar de que essas características são comumente encontradas no contexto de Hélio superfluido, apresentamos pela primeira vez essa identificação no cenário realístico de BEC aprisionados.

No presente trabalho, estudamos a possibilidade de se produzir um Condensado de Bose-Einstein em um estado excitado de um potencial confinante. Vimos que, com um campo externo oscilante, é possível transferir átomos do estado fundamental para um estado excitado qualquer. Se esse campo oscilar próximo da freqüência de transição entre os dois modos, é possível aproximar esse sistema para um de dois níveis. Analisando numericamente a evolução temporal das populações de cada nível, vimos que há oscilações de população do tipo Rabi. Estas oscilações variam de acordo com a forma espacial, a intensidade e com a dessintonia do campo aplicado. Vimos, também, que há a formação de franjas do tipo Ramsey, ao aplicarmos um campo oscilatório com dois pulsos separados. Além disso, definindo um parâmetro de ordem como sendo a diferença entre a média temporal da população de cada estado, é possível caracterizar um tipo de transição de fase no condensado. Estudamos como a forma do campo externo interfere na transição de fase, caracterizada pelo parâmetro de ordem. Obtemos também, um valor crítico do campo no qual ocorre essa transição. / In this work, we have studied the possibility of producing a Bose-Einstein Condensate in an excited state of a confining potential. We have seen that, with a oscillatory external field, it is possible to transfer atoms from the ground state to any excited state. If this field oscillates near the transition frequency between the two modes, it is possible to approximate that system to a two-level system. Analyzing numerically the temporal evolution of population of each level, we have seen there are Rabi-like oscillations of population. This oscillations vary according to the spacial shape, the intensity and the detuning of the applied field. We have also seen there is a Ramsey-like fringes formation, if we apply an oscillatory field with separate two pulses. Moreover, defining an order parameter as being a difference between the population time average of each level, it is possible to characterize a kind of phase transition in the condensate. We have studied how the shape of the external field interferes in the phase transition, characterized by the order parameter. We have also obtained a critical value for the field in which that transition occurs.

No presente trabalho, estudamos a possibilidade de se produzir um Condensado de Bose-Einstein em um estado excitado de um potencial confinante. Vimos que, com um campo externo oscilante, é possível transferir átomos do estado fundamental para um estado excitado qualquer. Se esse campo oscilar próximo da freqüência de transição entre os dois modos, é possível aproximar esse sistema para um de dois níveis. Analisando numericamente a evolução temporal das populações de cada nível, vimos que há oscilações de população do tipo Rabi. Estas oscilações variam de acordo com a forma espacial, a intensidade e com a dessintonia do campo aplicado. Vimos, também, que há a formação de franjas do tipo Ramsey, ao aplicarmos um campo oscilatório com dois pulsos separados. Além disso, definindo um parâmetro de ordem como sendo a diferença entre a média temporal da população de cada estado, é possível caracterizar um tipo de transição de fase no condensado. Estudamos como a forma do campo externo interfere na transição de fase, caracterizada pelo parâmetro de ordem. Obtemos também, um valor crítico do campo no qual ocorre essa transição. / In this work, we have studied the possibility of producing a Bose-Einstein Condensate in an excited state of a confining potential. We have seen that, with a oscillatory external field, it is possible to transfer atoms from the ground state to any excited state. If this field oscillates near the transition frequency between the two modes, it is possible to approximate that system to a two-level system. Analyzing numerically the temporal evolution of population of each level, we have seen there are Rabi-like oscillations of population. This oscillations vary according to the spacial shape, the intensity and the detuning of the applied field. We have also seen there is a Ramsey-like fringes formation, if we apply an oscillatory field with separate two pulses. Moreover, defining an order parameter as being a difference between the population time average of each level, it is possible to characterize a kind of phase transition in the condensate. We have studied how the shape of the external field interferes in the phase transition, characterized by the order parameter. We have also obtained a critical value for the field in which that transition occurs.

Considerable ongoing risk of condenser in-leakage exists at Otahuhu B (OTB) Power Station. The condenser cooling water used at OTB station is corrosive brackish water with exceedingly high sodium and chloride concentrations. Significant signs of corrosion inside the condenser have been found recently. In the event of condenser in-leakage, the salt contaminants in the cooling water will directly enter the Heat Recovery Steam Generator (HRSG) with the potential for significant and costly damage resulting in a long plant outage. A dynamic mathematical model was developed in the thesis to analyse the consequences of condenser in-leakage at OTB station. The analysis results show that the tolerance of the condenser to any leakage of cooling water is almost zero. Because the existing condensate monitoring system is not designed to detect contamination in this time frame, a new fast response system is required to detect condenser in-leakage immediately. A new dedicated fast response condensate monitoring system has been engineered and installed at OTB station as a part of the project scope. The new system dramatically reduces the response time to condenser in-leakage events. Critical instruments utilise multiple redundancy schemes to enhance the availability and reliability of the system. In addition, action level voting, timing, and alarming has been automated to assist operators in making correct decisions. The new condensate monitoring system is presently fully functional. The project has successfully achieved the objective of controlling the risk of condenser in-leakage events and minimising damage and negative effects on the plant.

This thesis presents theoretical investigations of triplet superfluidity (triplet superconductivity) in quasi-one-dimensional organic conductors and ultra-cold Fermi gases. Triplet superfluidity is different from its s-wave singlet counterpart since the order parameter is a complex vector and the interaction between fermions is in general anisotropic. Because of these distinctions, triplet superfluids have different physical properties in comparison to the s-wave case. The author discusses in this thesis the interplay between triplet superconductivity and spin density waves in quasi-one-dimensional organic conductors, and proposes a coexistence region of the two orders. Within the coexistence region, the interaction between the two order parameters acquires a vector structure, and induces an anomalous magnetic field effect. Furthermore, the author analyzes the matter-wave interference between two p-wave Fermi condensates, and proposes a polarization effect. For a single harmonically trapped p-wave Fermi condensate, the author also shows that the expansion upon release from the trap can be anisotropic, which reflects the anisotropy of the p-wave interaction.

Condensate blockage negatively impacts large natural gas condensate reservoirs all over the world; examples include Arun Field in Indonesia, Karachaganak Field in Kazakhstan, Cupiagua Field in Colombia,Shtokmanovskoye Field in Russian Barents Sea, and North Field in Qatar. The main focus of this thesis is to evaluate condensate blockage problems in the North Field, Qatar, and then propose solutions to increase well productivity in these gas condensate wells. The first step of the study involved gathering North Field reservoir data from previously published papers. A commercial simulator was then used to carry out numerical reservoir simulation of fluid flow in the North Field. Once an accurate model was obtained, the following three solutions to increasing productivity in the North Field are presented; namely wettability alteration, horizontal wells, and reduced Non Darcy flow. Results of this study show that wettability alteration can increase well productivity in the North Field by adding significant value to a single well. Horizontal wells can successfully increase well productivity in the North Field because they have a smaller pressure drawdown (compared to vertical wells). Horizontal wells delay condensate formation, and increase the well productivity index by reducing condensate blockage in the near wellbore region. Non Darcy flow effects were found to be negligible in multilateral wells due to a decrease in fluid velocity. Therefore, drilling multilateral wells decreases gas velocity around the wellbore, decreases Non Darcy flow effects to a negligible level, and increases well productivity in the North Field.

Exercise has become a vital component of the therapy regimen prescribed to cystic fibrosis (CF) patients due to its systemic benefits, such as increased sputum expectoration, attenuation of the expected 2-3% annual decline in pulmonary function, and extended life expectancy. However, exercise still is not viewed as being as beneficial as pharmacological treatments by many CF patients and can be intimidating. My aims in this study were two-fold; first, to determine the ideal exercise intensity for individuals with CF; and second, to determine if exercise at this ideal intensity could provide improvements in ion regulation in the lungs, which was measured using exhaled breath condensate (EBC) collection and nasal potential difference (NPD), that were comparable to one of their standard pharmacological therapies, albuterol. I hypothesized that with moderate intensity exercise, Na⁺ absorption would decrease from baseline due to Na⁺ channel inhibition, rather than increase or remain unchanged, as was expected with albuterol, and cause an even greater increase Cl- secretion compared to albuterol due to activation of both CF-dependent and independent Cl- efflux with exercise. CF (n=14) and healthy (n=16) subjects completed three visits, a baseline screening and two treatment visits. I collected EBC at baseline, 30- and 60-minutes post-albuterol administration on one visit, and at baseline and during three separate 15 min exercise bouts at low, moderate and high intensity on the other visit. Following the EBC collection, NPD was performed at 30- and 80-minutes post albuterol or following moderate and high intensity exercise. We also measured spirometry and diffusing capacity of the lungs for nitric oxide (DLNO) during each visit at the various time points. In CF subjects, moderate intensity exercise resulted in greater improvements in DLNO (39 ± 29vs.15 ± 22% change from baseline, exercise vs. albuterol respectively), similar levels of bronchodilation compared to 60-minutes post-albuterol administration, no change in Na⁺ absorption, and a four-fold increase in Cl- secretion. Our results suggest that moderate intensity exercise is the best dose for CF patients, and can provide comparable changes as its pharmacological counterpart albuterol, when compared over a short term duration.

Lorsque l'impulsion longitudinale des partons contenus dans un hadron ultra-relativiste diminue, on observe un accroissement de leur densité. Quand la densité approche une valeur d'ordre $1/\alpha_s$, elle n'augmente plus, elle sature. Ces effets de haute densité semblent être correctement décrits par la théorie effective du "Color Glass Condensate". Du point de vue expérimental, le LHC est le meilleur outil jamais disponible pour atteindre la phase saturée de la matière hadronique. Pour cette raison, la physique de la saturation est une branche très active de la QCD dans les années passées et à venir car la théorie et les expériences peuvent être comparées. En premier lieu, je discute de la phénoménologie des collisions proton-plomb qui ont eu lieu à l'hiver 2013 et dont les données sont sur le point d'être disponibles. Je calcule la section efficace pour la production de deux gluons qui est l'observable la plus simple pour trouver des preuves quantitatives de la saturation dans le régime cinématique du LHC. Je traite également la limite des états finaux fortement corrélés à grandes impulsions transverses et, par la même occasion, généralise la distribution de partons au régime dense. Le second sujet principal est l'évolution quantique des spectres de gluons et de quarks dans les collisions noyau-noyau, ayant à l'esprit son caractère universel. Ce résultat est déjà connu pour les gluons et je détaille ici le calcul avec attention. Pour les quarks, l'universalité n'a toujours pas été prouvée mais je dérive une formule de récursion intermédiaire entre l'ordre dominant et l'ordre sous-dominant qui constitue une étape cruciale dans l'extraction de l'évolution quantique. Enfin, je présente brievement un travail indépendant de théorie des groupes. Je détaille une méthode personnelle permettant de calculer des traces impliquant un nombre arbritraire de générateurs, une situation souvent rencontrée dans les calculs de QCD.

Considerable ongoing risk of condenser in-leakage exists at Otahuhu B (OTB) Power Station. The condenser cooling water used at OTB station is corrosive brackish water with exceedingly high sodium and chloride concentrations. Significant signs of corrosion inside the condenser have been found recently. In the event of condenser in-leakage, the salt contaminants in the cooling water will directly enter the Heat Recovery Steam Generator (HRSG) with the potential for significant and costly damage resulting in a long plant outage. A dynamic mathematical model was developed in the thesis to analyse the consequences of condenser in-leakage at OTB station. The analysis results show that the tolerance of the condenser to any leakage of cooling water is almost zero. Because the existing condensate monitoring system is not designed to detect contamination in this time frame, a new fast response system is required to detect condenser in-leakage immediately. A new dedicated fast response condensate monitoring system has been engineered and installed at OTB station as a part of the project scope. The new system dramatically reduces the response time to condenser in-leakage events. Critical instruments utilise multiple redundancy schemes to enhance the availability and reliability of the system. In addition, action level voting, timing, and alarming has been automated to assist operators in making correct decisions. The new condensate monitoring system is presently fully functional. The project has successfully achieved the objective of controlling the risk of condenser in-leakage events and minimising damage and negative effects on the plant.