Detailed study of the spatial correlations of day-to-day ionospheric TEC variations on a global scale was performed for four 30-day-long periods in 2004 (January, March/April, June/July, September/October) using observations from more than 1000 ground-based GPS receivers. In order to obtain the spatial correlations, initially, the day-to-day variability was calculated by first mapping the observed slant TEC values for each 5-minute GPS ground receiver-satellite pair to the vertical and then differencing it with its corresponding value from the previous day. This resulted in more than 150 million values of day-to-day change in TEC (delta TEC). Next, statistics were performed on the delta TEC values. The study indicates strong correlationsbetween geomagnetic conjugate points, and these correlations are larger at low latitudes than at middle latitudes. Typical correlation lengths, defined as the angular separation at which the correlation coefficient drops to 0.7, were found to be larger at middle latitudes than at low latitudes. The correlation lengths are larger during daytime than during nighttime. The results indicate that the spatial correlation is largely independent of season. These spatial correlations are important for understanding the physical mechanisms that cause ionospheric weather variability and are also relevant to data assimilation. In an effort to better understand the effects of neutral wind and electric field on the TEC variability, a physics-based numerical Ionosphere/Plasmasphere Model (IPM) was used. The model solves the transport equations for the six ions, O+, NO+, O2+, N2+, H+, and He+, on convecting flux tubes that realistically follow the geomagnetic field. Two of the inputs required by the IPM are the thermospheric neutral wind and the low-latitude electric field, which can be given by existing empirical model or externally specified by the user. To study the relative importance of the neutral wind and the electric field for the TEC variations, these two model inputs were externally modified and the resulting variations in TEC were compared. Neutral wind and electric field modifications were introduced at three different local times in order to investigate the effect of different start times of the imposed perturbations on TEC. This study focused on modeled low- and middlelatitude TEC variations in the afternoon and post-sunset at three different longitude sectors for medium solar activity and low geomagnetic activity. The largest changes in TEC were found predominantly in the equatorial anomaly, and a significant longitudinal dependence was observed. The results indicate that the perturbation effect on the TEC at 2100 LT varied nonlinearly with the elapsed time after the imposed neutral wind and electric field perturbations. An important outcome of this study is that daytime neutral wind and/or electric field modifications will lead to essentially identical TEC changes in the 2100 local time sector.

Dans un milieu désordonné, une onde peut être localisée exponentiellement par des effets d'interférence. Ce phénomène de localisation d'Anderson conduit notamment à une annulation de la conductance d'un fluide quantique unidimensionnel. Des travaux théoriques ont cependant montré que l'application d'un champ électrique pouvait réduire, voire supprimer, cette localisation. Nous étudions ici l'effet d'une force sur la localisation d'une onde quantique de matière dans un système unidimensionnel. En lien direct avec les expériences d'atomes ultrafroids, qui permettent d'observer la localisation d'Anderson d'un paquet d'onde en étalement, ou bien l'effet du désordre sur le transport entre deux réservoirs, nous nous intéressons à deux systèmes : la diffusion et la transmission d'une particule. Afin d'étudier la transmission à travers un guide, nous étendons un formalisme de matrices de transfert à la présence d'une force, éventuellement inhomogène. Deux approches analytiques complémentaires nous permettent d'étendre les résultats au cas d'un désordre de tavelures tel que celui utilisé dans les expériences d'atomes ultrafroids. Nous montrons que la force peut être entièrement prise en compte à l'aide d'une renormalisation de la longueur du guide par un libre parcours moyen local de la particule. Pour un désordre blanc, la force conduit alors une localisation plus faible, algébrique, tandis qu'une délocalisation apparaît pour un désordre corrélé. Nous nous intéressons ensuite à la diffusion d'une particule, à l'aide d'une approche numérique. Nous mettons en évidence une délocalisation de la position à grande force sous la forme d'une croissance temporelle algébrique, dont l'exposant augmente avec la force. Nous montrons de plus que la localisation est systématiquement détruite dans un désordre corrélé. / A wave can be exponentially localized in a disordered medium, due to interference effects. This Anderson localization phenomenon leads to a cancellation of the conductance of a quantum fluid in 1D. However, theoretical works pointed out that an electric field may reduce or cancel this localization. We study here the effect of a force on the localization of a 1D quantum matter wave. Since both Anderson localization of an expanding wave packet and the effect of disorder on the transport between two reservoirs have been studied in ultracold atom experiments, we focus on two systems, namely the diffusion, or the transmission, of a particle.In order to calculate the transmission, we generalize a transfer matrix formalism to the presence of a, possibly inhomogeneous, force. The case of a speckle disorder as used in ultracold atom experiments is dealt with using two other analytical approaches. Our main is result is that the force can be entirely taken into account by renormalising the length with a local mean free path of the particle. For white-noise disorder, the force leads to a weaker, algebraic localization, whereas full delocalization appears for a correlated disorder. We then focus on the diffusion of a particle, using a numerical approach. A transition of delocalization of the particle for strong forces is shed into light through a power law increase of its position, whose exponent increases with the force. Moreover, we show that localization is systematically destroyed in a correlated disorder.

L'objet de cette thèse est l'étude théorique et expérimentale de gaz de Bose à une dimension (1D), confinés à la surface d'une micro-structure. Une part importante du travail de thèse a été la modification du montage expérimental: le système laser a été remplacé, et l'installation d'un nouvel objectif de grande ouverture numérique (0.4) a nécessité le changement du dessin de la puce ainsi que l'adaptation du système à vide. Nous avons étudié les corrélations du second ordre dans l'espace des impulsions, en appliquant une méthode qui nous permet d'enregistrer en une seule image la distribution en vitesses complète de notre gaz. Nos données explorent les différents régimes du gaz à faibles interactions, du gaz de Bose idéal au quasi-condensat. Ces mesures ont montré le phénomène de groupement bosonique dans les deux phases, tandis que le quasi-condensat comporte des corrélations négatives en dehors de la diagonale. Ces anti-corrélations sont une signature de l'absence d'ordre à longue portée en 1D. Les mesures sont en bon accord avec des calculs analytiques ainsi que des simulations numériques de type Monte Carlo Quantique. Ensuite, l'objet d'un second projet est l'étude du refroidissement de gaz 1D. Comme nos échantillons occupent seulement l'état fondamental du piège transverse, il n'est pas possible de sélectionner les atomes les plus énergiques pour évaporer le gaz de façon habituelle. Une méthode alternative, qui repose sur la perte non-sélective d'atomes, a été proposée et mise en pratique expérimentalement par des collègues. Leurs résultats sont compatibles avec des observations faites sur notre montage, très semblable au leur. Tout d'abord, nous avons aussi obtenu des température d'environ 10% de l'énergie de l'état fondamental transverse. Deuxièmement, des simulations champ classique ont montré la robustesse de l'état hors d'équilibre généré par de telles pertes: les différents modes perdent en effet de l'énergie à des taux différents. Ceci est en accord avec l'observation expérimentale suivante: selon la méthode de thermométrie utilisée, chacune explorant des excitations d'énergies différentes, les températures mesurées sont différentes. Enfin, nous relions cet état non-thermique à la nature intégrable du système considéré. / We present experimental and theoretical results on ultracold one-dimensional (1D) Bose gases, trapped at the surface of a micro-structure. A large part of the doctoral work was dedicated to the upgrade of the experimental apparatus: the laser system was replaced and the installation of a new imaging objective of high numerical aperture (0.4) required the modification of the atom chip design and the vacuum system. We then probed second-order correlations in momentum space, using a focussing method which allows us to record the velocity distribution of our gas in a single shot. Our data span the weakly-interacting regime of the 1D Bose gas, going from the ideal Bose gas regime to the quasi-condensate. These measurements revealed bunching in both phases, while in the quasi-condensate off-diagonal negative correlations, a the signature of the absence of long-range order in 1D, were revealed. These experimental results agree well with analytical calculations and exact Quantum Monte Carlo simulations. A second project focussed on the cooling of such 1D gases. Since the samples lie in the ground state of the transverse trap, energy selection to carry out usual evaporative cooling is not possible. An alternative cooling scheme, based on non-selective removal of particles, was proposed and demonstrated by colleagues. These findings are compatible with observations on our setup, similar to theirs. Firstly, we also reached temperatures as low as 10% of the transverse gap in earlier experiments. Secondly, with classical field simulations we demonstrate the robustness of the non-thermal arising from these losses: different modes indeed lose energy at different rates. This agrees with the following observation: depending on the thermometry we use, each probing excitations of different energies, the measured temperatures are different, beyond experimental uncertainty. Finally, we relate this non-thermal state to the integrable nature of the 1D Bose gas.

In this paper we formulate a nonlocal density functional theory of inhomogeneous water. We model a water molecule as a couple of oppositely charged sites. The negatively charged sites interact with each other through the Lennard–Jones potential (steric and dispersion interactions), square-well potential (short-range specific interactions due to electron charge transfer), and Coulomb potential, whereas the positively charged sites interact with all types of sites by applying the Coulomb potential only. Taking into account the nonlocal packing effects via the fundamental measure theory, dispersion and specific interactions in the mean-field approximation, and electrostatic interactions at the many-body level through the random phase approximation, we describe the liquid–vapour interface. We demonstrate that our model without explicit account of the association of water molecules due to hydrogen bonding and with explicit account of the electrostatic interactions at the many-body level is able to describe the liquid–vapour coexistence curve and the surface tension at the ambient pressures and temperatures. We obtain very good agreement with available in the literature MD simulation results for density profile of liquid–vapour interface at ambient state parameters. The formulated theory can be used as a theoretical background for describing of the capillary phenomena, occurring in micro- and mesoporous materials.

Covariant density functional theory (CDFT) is one of the modern theoretical tools for the description of finite nuclei and neutron stars. Its performance is defined by underlying covariant energy density functionals (CEDFs) which depend on a number of parameters. Several investigations within the CDFT framework using the relativistic Hartree-Bogoliubov (RHB) approach are discussed in this dissertation. Statistical errors in ground state observables and single-particle properties of spherical even-even nuclei and their propagation to the limits of nuclear landscape have been investigated in the covariant energy density functionals with nonlinear density dependency. The parametric correlations are studied in different classes of CEDFs; the elimination of these correlations reduces the number of independent parameters to five or six without affecting the performance of CEDFs on a global scale. Moreover, this study reveals the need to include information on deformed nuclei for the improvement of fitting protocols. A new technique for incorporating deformed nuclei data into the fitting protocol is described. Different CEDFs are optimized using this approach, resulting in a significant improvement in the nuclear mass description. A systematic investigation of the ground state and fission properties of even-even actinides and superheavy nuclei with proton numbers Z = 90 - 120 located between the two-proton and two-neutron drip lines has been performed. These results provide a necessary theoretical input for the modeling of the nuclear astrophysical rapid neutron capture process (r-process) taking place in the mergers of neutron stars. The state-of-the-art CEDFs, namely, DD-PC1, DD-ME2, NL3*, and PC-PK1, are employed in this study. Theoretical systematic uncertainties in the physical observables and their evolution as a function of proton and neutron numbers have been quantified and their major sources have been identified. The extension of the nuclear landscape to hyperheavy nuclei is investigated. The transition from ellipsoidal-like nuclear shapes to toroidal shapes is crucial for the potential expansion of the nuclear landscape to hyperheavy nuclei. The physical reasons for the stability of toroidal nuclei in the Z ~ 134 region are discussed.

No description available.

Bakgrund: Agility är en egenskap som är avgörande för tennisspelares prestation. Det är således en egenskap som regelbundet bör tränas och utvärderas. Till detta projekt presenteras ett nyutvecklat och tennisspecifikt test som kan användas för att utvärdera tennisspelares reaktiva agilityförmåga.  Syftet med studien var att utvärdera testets reliabilitet och validitet för att fastställa dess övergripande kvalitet. Ett andra syfte var att undersöka vilka fysiska egenskaper som korrelerade med prestationen på agilitytestet. Metod: Deltagare till studien var 18 tennisspelare (9 flickor och 9 pojkar; ålder 14.5 ± 1.5) med erfarenhet av matchspel på regional samt nationell nivå. Under ett testtillfälle på deltagarnas respektive tennisklubb genomfördes kroppsmätningar, fysiska tester samt agilitytester med en reaktiv komponent (RAG: reactive agility) och utan en reaktiv komponent (CODS: change of direction speed). Resultaten visade på en hög absolut reliabilitet (CV%: 2.69–4.28%) samt hög relativ reliabilitet (ICC:0.802–0.943). Fysiska egenskaper som korrelerade med agilityförmåga var spänst, sprintsnabbhet samt reaktiv styrka. Konklusion: Slutsatsen som kan dras är att det nyutvecklade tennisspecifika agilitytestet är ett reliabelt test som tennisspelare kan använda för att utvärdera sin agilityförmåga men där validiteten inte gick att uttala sig om i några mätbara termer och mer forskning är nödvändig. / Background: Agility is an important ability in tennis and should be trained and evaluated on a regular basis. In this project a newly developed tennis specific reactive agility test is presented.  Aim: The aim of the study was to evaluate the reliability and validity of the agility test. A second aim was to analyze correlations between agility performance and physical abilities. Method: The sample consisted of 18 tennis players (9 males and 9 females; age 14.5 ± 1.5) who competed at regional and national level. The variables comprised body dimensions, sprint speed, jump height measures, single leg balance, change of direction speed (CODS) and reactive agility (RAG).  Results: The results showed a high absolute reliability (CV%: 2.69–4.28%) and high relative reliability (ICC:0.802–0.943). Physical abilities that correlated with agility performance was jump height, sprint speed and reactive strength.  Conclusion: The conclusion is that the newly developed reactive agility test is reliable and can be used by tennis players to evaluate agility. The test´s validity is not possible to determine, and more studies are needed.

Simultaneous two-point three-component four-sensor hot-wire velocity measurements taken in three flows of aeroacoustic interest are here analyzed. The analyses provide information on the turbulence structure of the flows as it would be encountered by hypothetical noise producing blades passing through the flows. Two-point measurements taken in the first flow, a lifting wake from a rectangular NACA 0012 half wing, are used to calculate space-time correlation functions and 'pointwise' wave number frequency spectra. Two upwash spectra, calculated for locations in the region of the wake that is roughly homogenous in the spanwise direction, are direct estimates of the full wave number frequency spectra at their locations. As such, they are used to perform aeroacoustic calculations, and the results are compared to results achieved using the von Kármán isotropic spectrum. Amiet's approximation, where the wave number frequency spectra can be represented by the correlation length scales is found to hold reasonably well for the measured spectra. The two-point measurements in the second flow, a vortex/blade-tip interaction, are analyzed to provide information useful to researchers of blade-wake interaction noise produced by helicopter rotors. Space-time correlation functions and wave number frequency spectra are calculated for five cuts through the region of interaction. The correlation functions provide information concerning the turbulence length scales found in the interaction region. The spectra are compared to the von Kármán isotropic spectrum and found to be greatly different. However, the spectra do bear some resemblance to spectra calculated in the spanwise homogenous region of the lifting wake. The two-point measurements taken in the third flow, the wake from a fan cascade, are analyzed to provide information of use to modelers of broadband noise produced through rotor wake/stator interactions. In particular, space-time correlation functions are calculated for a grid of two-point measurements, which allows the estimation of the turbulence structure as seen by a passing stator blade. Space-time correlation functions and wave number frequency spectra are calculated for various stator configurations. The implications of engine operating speed and stator configuration for broadband noise production are discussed. <i> [Vita removed March 2, 2012. GMc]</i> / Master of Science

We consider the finite two-dimensional Ising model on a lattice with periodic boundaryconditions. Kaufman determined the spectrum of the transfer matrix on the finite,periodic lattice, and her derivation was a simplification of Onsager's famous result onsolving the two-dimensional Ising model. We derive and rework Kaufman's resultsby applying representation theory, which give us a more direct approach to computethe spectrum of the transfer matrix. We determine formulas for the spin correlationfunction that depend on the matrix elements of the induced rotation associated withthe spin operator. The representation of the spin matrix elements is obtained byconsidering the spin operator as an intertwining map. We wrap the lattice aroundthe cylinder taking the semi-infinite volume limit. We control the scaling limit of themulti-spin Ising correlations on the cylinder as the temperature approaches the criticaltemperature from below in terms of a Bugrij-Lisovyy conjecture for the spin matrixelements on the finite, periodic lattice. Finally, we compute the matrix representationof the spin operator for temperatures below the critical temperature in the infinite-volume limit in the pure state defined by plus boundary conditions.

L'objectif de cette thèse est d'étudier le problème de la modélisation des changements de régime dans les modèles a corrélations conditionnelles dynamiques en nous intéressant plus particulièrement a l'approche Markov-switching. A la différence de l'approche standard basée sur le modèle à chaîne de Markov caché (HMM) de base, nous utilisons des extensions du modèle HMM provenant des modèles graphiques probabilistes. Cette discipline a en effet proposé de nombreuses dérivations du modèle de base permettant de modéliser des structures complexes. Cette thèse se situe donc a l'interface de deux disciplines: l'économétrie financière et les modèles graphiques probabilistes.Le premier essai présente un modèle construit a partir d'une structure hiérarchique cachée markovienne qui permet de définir différents niveaux de granularité pour les régimes. Il peut être vu comme un cas particulier du modèle RSDC (Regime Switching for Dynamic Correlations). Basé sur le HMM hiérarchique, notre modèle permet de capter des nuances de régimes qui sont ignorées par l'approche Markov-Switching classique.La seconde contribution propose une version Markov-switching du modèle DCC construite a partir du modèle HMM factorise. Alors que l'approche Markov-switching classique suppose que les tous les éléments de la matrice de corrélation suivent la même dynamique, notre modèle permet à tous les éléments de la matrice de corrélation d'avoir leur propre dynamique de saut. Markov-switching. A la différence de l'approche standard basée sur le modèle à chaîne de Markov caché (HMM) de base, nous utilisons des extensions du modèle HMM provenant des modèles graphiques probabilistes. Cette discipline a en effet propose de nombreuses dérivations du modèle de base permettant de modéliser des structures complexes. Cette thèse se situe donc a l'interface de deux disciplines: l'économétrie financière et les modèles graphiques probabilistes.Le premier essai présente un modèle construit a partir d'une structure hiérarchique cachée markovienne qui permet de définir différents niveaux de granularité pour les régimes. Il peut ^etre vu commeun cas particulier du modele RSDC (Regime Switching for Dynamic Correlations). Base sur le HMMhierarchique, notre modele permet de capter des nuances de regimes qui sont ignorees par l'approcheMarkov-Switching classique.La seconde contribution propose une version Markov-switching du modele DCC construite a partir dumodele HMM factorise. Alors que l'approche Markov-switching classique suppose que les tous les elementsde la matrice de correlation suivent la m^eme dynamique, notre modele permet a tous les elements de lamatrice de correlation d'avoir leur propre dynamique de saut.Dans la derniere contribution, nous proposons un modele DCC construit a partir d'un arbre dedecision. L'objectif de cet arbre est de relier le niveau des volatilites individuelles avec le niveau descorrelations. Pour cela, nous utilisons un arbre de decision Markovien cache, qui est une extension de HMM. / The objective of this thesis is to study the modelling of change in regime in the dynamic conditional correlation models. We focus particularly on the Markov-switching approach. Unlike the standard approach based on the Hidden Markov Model (HMM), we use extensions of HMM coming from probabilistic graphical models theory. This discipline has in fact proposed many derivations of the basic model to model complex structures. Thus, this thesis can be view at the interface of twodisciplines: financial econometrics and probabilistic graphical models.The first essay presents a model constructed from a hierarchical hidden Markov which allows to increase the granularity of the regimes. It can be seen as a special case of RSDC model (Regime Switching for Dynamic Correlations). Based on the hierarchical HMM, our model can capture nuances of regimes that are ignored by the classical Markov-Switching approach.The second contribution proposes a Markov-switching version of the DCC model that is built from the factorial HMM. While the classical Markov-switching approach assumes that all elements of the correlation matrix follow the same switching dynamic, our model allows all elements of the correlation matrix to have their own switching dynamic.In the final contribution, we propose a model DCC constructed based on a decision tree. The objective of this tree is to link the level of volatility with the level of individual correlations. For this, we use a hidden Markov decision tree, which is an extension of HMM.