The study will be based on a qualitative method with a focus on describing seven preschool teachers' different perceptions of the forest as a learning environment for all age groups in preschool. Further in this work, we want to contribute knowledge about the forest's possibilities for gross motor development, learning and influence for all children in preschool. As the curriculum for preschool (Skolverket, 2018) writes, it is the preschool teachers' responsibility that the children are stimulated and challenged in their cognitive and motor development and that the children should feel participation and influence in education. Furthermore, the curriculum states that no child in preschool should be subjected to discrimination on the basis of age. The study used semi-structured interviews as a method and is based on a phenomenographic approach. The results showed differences between the preschool teachers' perceptions in preschools with outdoor education and traditional education, where the preschool teachers in preschools with outdoor education perceived the forest as only positive with unlimited possibilities related to the age of the group of children. They perceived that everything you can do inside can also be done outside with all children, while those with traditional pedagogy highlighted some limitations in the forest linked to the age of the group of children. The conclusion of the study shows that the preschool teachers are unanimous in their opinion that the forest is an educational environment. / Studien kommer att utgå från en kvalitativ metod med fokus på att beskriva sju förskollärares olika uppfattningar om skogen som en lärmiljö för alla åldersgrupper i förskolan. Vidare i detta arbete vill vi bidra med kunskap kring skogens möjligheter för den grovmotoriska utvecklingen, lärande och inflytande för alla barn i förskolan. Som läroplanen för förskolan (Skolverket, 2018) skriver är det förskollärarnas ansvar att barnen stimuleras och utmanas i sin kognitiva och motoriska utveckling samt att barnen ska känna delaktighet och inflytande i utbildningen. Vidare skriver läroplanen att inget barn i förskolan ska bli utsatt för diskriminering på grund av ålder. Studien använde halvstrukturerade intervjuer som metod och utgår ifrån en fenomenografisk ansats.  I resultatet visade sig skillnader mellan förskollärarnas uppfattningar på förskolorna med utomhuspedagogik och traditionell pedagogik där förskollärarna på förskolorna med utomhuspedagogik uppfattade skogen som enbart positiv med obegränsade möjligheter relaterat till barngruppens ålder. De uppfattade att allt man kan göra inne även kan göras ute med alla barn medan de med traditionell pedagogik belyste en del begränsningar i skogen kopplat till barngruppens ålder. Slutsatsen i studien visar att förskollärarna är eniga i sin uppfattning om att skogen är en lärorik miljö.

The objective of this research concerns identifying whether or not there is a relationship between oil price increases in a given quarter and the likelihood of a recession in the subsequent quarter. The data used is gathered from the St. Louis Fed's Fred II, the National Bureau of Economic Research, and the Energy Information Administration to generate modified variables. These variables are tested using a qualitative dependent variable, recession, in a binary choice model. The findings validated the assumption that oil prices do have a correlation with recessions, and that the relationship is a direct one. Based on the model, an increase in the price of oil will positively affect the likelihood of a "recession" outcome versus the alternative, "no recession". It is anticipated that the results will inspire future research into the causes and effects of oil price surges, as well as the determinants of economic contractions in the future based on policy decisions and economic decision-making practices in the present.

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付記する学位プログラム名: グローバル生存学大学院連携プログラム / 京都大学 / 新制・課程博士 / 博士(社会健康医学) / 甲第23823号 / 社医博第123号 / 新制||社医||12(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 川上 浩司, 教授 木村 剛, 教授 山本 洋介 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DFAM

<p>L^p is supposed to be L with a superscript lower case 'p.'</p> / <p>This thesis investigates a 1-dimensional Gross-Pitaevskii (GP) equation from the viewpoint of a system of Hamiltonian partial differential equations (PDEs). A theorem on Birkhoff normal forms is a particularly important goal of this study. The resulting system is a perturbed system of a completely resonant system, which we analyze, using several forms of perturbation theory.</p> <p>In chapter two, we study estimates 011 integrals of products of four Hermite functions, which represent coefficients of mode coupling, and play an important role in the proof of the Birkhoff normal form theorem. This is a basic problem, which has a close relationship with a problem of Besicovitch, namely the behavior of the L^p norms of L² -normalized Hermite functions.</p> <p>In chapter three we carefully reconsider the linear Schrodinger equation with a harmonic potential, and we introduce a family of Hilbert spaces for studying the GP equation, which generalize the traditional energy spaces in which one works. One unexpected fact is that these function spaces have a close relationship with the former works for the tempered distributions, in particular the N-representation theory due to B. Simon, and V. Bargmann's theory, which uncovers relationship between the tempered distributions and his function spaces through the so-called Segal-Bargmann transformation. In addition, our function spaces have a nice relationship with the Sobolev spaces. In this chapter, a few other questions regarding these function spaces are discussed.</p> <p>In chapter four the proof of the Birkhoff normal form theorem on spaces we have introduced are provided. The analysis is divided into two cases according to the regularity of the related function space. After proving the Birkhoff normal form theorem, we made an analysis of the impact of the perturbation on the main part of the GP system, which we remark is completel:y resonant.</p> / Doctor of Philosophy (PhD)

We consider a gas of indistinguishable bosons, confined to a ring of radius R, and interacting via a pair-wise cosine potential. This may be thought of as the quantized Hamiltonian Mean Field (HMF) model for bosons originally introduced by Chavanis as a generalization of Antoni and Ruffo’s classical model. This thesis contains three parts: In part one, the dynamics of a Bose-condensate are considered by studying a generalized Gross-Pitaevskii equation (GGPE). Quantum effects due to the quantum pressure are found to substantially alter the system’s dynamics, and can serve to inhibit a pathological instability for repulsive interactions. The non-commutativity of the large-N , long-time, and classical limits is discussed. In part two, we consider the GGPE studied above and seek static solutions. Exact solutions are identified by solving a non-linear eigenvalue problem which is closely related to the Mathieu equation. Stationary solutions are identified as solitary waves (or solitons) due to their small spatial extent and the system’s underlying Galilean invariance. Asymptotic series are developed to give an analytic solution to the non- linear eigenvalue problem, and these are then used to study the stability of the solitary wave mentioned above. In part three, the exact solutions outlined above are used to study quantum fluctuations of gapless excitations in the HMF model’s symmetry broken phase. It is found that this phase is destroyed at zero temperature by large quantum fluctuations. This demonstrates that mean-field theory is not exact, and can in fact be qualitatively wrong, for long-range interacting quantum systems, in contrast to conventional wisdom. / Thesis / Doctor of Philosophy (PhD) / The Hamiltonian Mean Field (HMF) model was initially proposed as a simplified description of self-gravitating systems. Its simplicity shortens calculations and makes the underlying physics more transparent. This has made the HMF model a key tool in the study of systems with long-range interactions. In this thesis we study a quantum extension of the HMF model. The goal is to understand how quantum effects can modify the behaviour of a system with long-range interactions. We focus on how the model relaxes to equilibrium, the existence of special “solitary waves”, and whether quantum fluctuations can prevent a second order (quantum) phase transition from occurring at zero temperature.

Investigamos o sistema formado por dois condensados aprisionados em estados hiperfinos diferentes do Rubídio, num potencial em forma de charuto, ou seja, num sistema físico real e quase-unidimensional. É investigada a dependência das soluções das equações de Gross-Pitaevski com a separação entre as armadilhas, bem como com o parâmetro de acoplamento de Josephson, para três valores diferentes do número total de átomos aprisionados. Para alguns conjuntos de parâmetros constatamos a existência de estados metaestáveis. O observável que escolhemos para caracterizar tal sistema físico foi a separação média entre os pacotes, pois os dois ramos de soluções encontramos correspondem a soluções mais juntas ou mais separadas espacialmente. / We study the system formed by two coupled condensates of different Rubidium hyperfine states trapped in a cigar shaped potential, that is, a real quasi one-dimensional system. The dependency of the solution of the Gross-Pitaevski equations is investigated as a function of trap displacement and Josephson coupling parameter for three different values of the total trapped atoms number. For some sets of parameters we report the existence of metastable states. The observable we chose to characterize this system was the mean separation between the packages, because we found two branches which correspond to closer or more separated solutions.

Dans cette thèse, nous étudions différents aspects mathématiques et numériques des équations de Gross-Pitaevskii et de Schrödinger non linéaire. Nous commençons (chapitre 1) par introduire différents modèles à partir des systèmes physiques que sont les condensats de Bose-Einstein et les impulsions lumineuses dans les fibres optiques. Cette modélisation conduit aux équations aux dérivées partielles stochastiques suivantes : l'équation de Gross-Pitaevskii stochastique et l'équation de Schrödinger non linéaire avec dispersion aléatoire. Ensuite, dans le second chapitre, nous nous intéressons au problème de l'existence et l'unicité d'une solution de ces équations. On montre notamment que le problème de Cauchy a une solution pour l'équation de Gross-Pitaevskii stochastique avec rotation grâce à la construction de la solution associée au problème. Nous abordons ensuite dans le troisième chapitre le problème du calcul des états stationnaires pour l'équation de Gross-Pitaevskii. Nous développons une méthode pseudo-spectrale de discrétisation du Continuous Normalized Gradient Flow, associée à une résolution itérative préconditionnée des sous-espaces de Krylov. Le quatrième chapitre concerne l'étude de schémas pseudo-spectraux pour la dynamique de l'équation de Gross-Pitaevskii et de Schrödinger non linéaire. On procède à une étude numérique de ces schémas (schéma de splitting de Lie et de Strang, ainsi qu'un schéma de relaxation). De plus, on analyse le schéma de Lie dans le cadre de l'équation de Schrödinger non linéaire avec dispersion aléatoire. Finalement, nous présentons, dans le cinquième chapitre, une boîte à outils Matlab (GPELab) développée dans le but de fournir les méthodes numériques que nous avons étudiées / The aim of this Thesis is to study various mathematical and numerical aspects related to the Gross-Pitaevskii and nonlinear Schrödinger equations. We begin (chapter 1) by introducing a few models starting from the physics of Bose-Einstein condensates and optical fibers. This naturally leads to introducing a stochastic Gross-Pitaevskii equation and a nonlinear Schrödinger equation with random dispersion. Next, in the second chapter, we analyze the existence and uniqueness problem for these two equations. We prove that the Cauchy problem admits a solution for the stochastic Gross-Pitaevskii equation with a rotational term by constructing the solution associated with the linear. The third chapter is concerned with the computation of stationary states for the Gross-Pitaevskii equation. We develop a pseudo-spectral approximation scheme for the Continuous Normalized Gradient Flow formulation, combined with preconditioned Krylov subspace methods. This original approach leads to the robust and efficient computation of ground states for fast rotations and strong nonlinearities. In the fourth chapter, we consider some pseudo-spectral schemes for computing the dynamics of the Gross-Pitaevskii and nonlinear Schrödinger equations. These schemes (the Lie's and Strang's splitting schemes and the relaxation scheme) are numerically studied. Moreover, we proceed to a rigorous numerical analysis of the Lie scheme for the associated stochastic PDEs. Finally, we present in the fifth chapter a Matlab toolbox (called GPELab) that provides computational solutions based on the schemes previously introduced in the Thesis

In dieser Arbeit werden Gross-Neveu Modelle mit einer endlichen Anzahl von Fermiontypen auf einem zweidimensionalen Euklidischen Raumzeitgitter betrachtet. Modelle dieses Typs sind asymptotisch frei und invariant unter einer chiralen Symmetrie. Aufgrund dieser Gemeinsamkeiten mit QCD sind sie sehr gut geeignet als Testumgebungen für Fermionwirkungen die in großangelegten Gitter-QCD-Rechnungen benutzt werden. Das Schrödinger Funktional für die Gross-Neveu Modelle wird definiert für Wilson und Ginsparg-Wilson Fermionen. In 1-Schleifenstörungstheorie wird seine Renormierbarkeit gezeigt. Die Vier-Fermionwechselwirkungen der Gross-Neveu Modelle habe dimensionslose Kopplungskonstanten in zwei Dimensionen. Die Symmetrieeigenschaften der Vier-Fermionwechselwirkungen und deren Beziehungen untereinander werden diskutiert. Im Fall von Wilson Fermionen ist die chirale Symmetrie explizit gebrochen und zusätzliche Terme müssen in die Wirkung aufgenommen werden. Die chirale Symmetrie wird durch das Einstellen der nackten Masse und einer der Kopplungen bis auf Cut-off-Effekte wiederhergestellt. Die kritische Masse und die symmetriewiederherstellende Kopplung werden bis zur zweiten Ordnung in Gitterstörungstheorie berechnet. Dieses Resultat wird in der 1-Schleifenberechnung der renormierten Kopplungen und der zugehörigen Betafunktionen benutzt. Die renormierten Kopplungen werden definiert mit Hilfe von geeignete Rand-Rand-Korrelatoren. Die Rechnung reproduziert die bekannten führenden Koeffizienten der Betafunktionen. Eine der Kopplungen hat eine verschwindende Betafunktion. Die Rechnung wird mit dem vor kurzem vorgeschlagenen Schrödinger Funktional mit exakter chiraler Symmetrie, also Ginsparg Wilson Fermionen, wiederholt. Es werden die gleichen Divergenzen gefunden, wie im Fall von Wilson Fermionen. Unter Benutzung des regularisierungsabhängigen, endlichen Teils der renormierten Kopplungen werden die Verhältnisse der Lambda-Parameter bestimmt. / Gross-Neveu type models with a finite number of fermion flavours are studied on a two-dimensional Euclidean space-time lattice. The models are asymptotically free and are invariant under a chiral symmetry. These similarities to QCD make them perfect benchmark systems for fermion actions used in large scale lattice QCD computations. The Schrödinger functional for the Gross-Neveu models is defined for both, Wilson and Ginsparg-Wilson fermions, and shown to be renormalisable in 1-loop lattice perturbation theory. In two dimensions four fermion interactions of the Gross-Neveu models have dimensionless coupling constants. The symmetry properties of the four fermion interaction terms and the relations among them are discussed. For Wilson fermions chiral symmetry is explicitly broken and additional terms must be included in the action. Chiral symmetry is restored up to cut-off effects by tuning the bare mass and one of the couplings. The critical mass and the symmetry restoring coupling are computed to second order in lattice perturbation theory. This result is used in the 1-loop computation of the renormalised couplings and the associated beta-functions. The renormalised couplings are defined in terms of suitable boundary-to-boundary correlation functions. In the computation the known first order coefficients of the beta-functions are reproduced. One of the couplings is found to have a vanishing beta-function. The calculation is repeated for the recently proposed Schrödinger functional with exact chiral symmetry, i.e. Ginsparg-Wilson fermions. The renormalisation pattern is found to be the same as in the Wilson case. Using the regularisation dependent finite part of the renormalised couplings, the ratio of the Lambda-parameters is computed.