Background: In 2008, the financial crisis led to the deterioration of the global economy. The financial industry suffered severe setbacks. On the one hand, regulators strengthened their supervision over financial institutions and raised capital requirements. On the other hand, publics’ confidence in financial institutions declined. At the same time, the fintech industry has rapidly developed during this decade, they use technology to make financial innovation and pose a threat to the traditional financial industry. Purpose: This paper aims to study the linkage between U.S. fintech and the traditional financial sector, trying to figure out which industry's stock price changes will affect the stock price changes in another industry. In particular, it also considers whether the global financial crisis will affect this relationship. Method: We first perform the Granger causality test under the VAR framework for several selected indices sequences, and then use the Toda Yamamoto version of Granger causality approach to verify the reliability of the above tests. Testing is divided into different time intervals in order to detect the impact of financial crisis on the relationship between time series. Conclusion: The empirical analysis results show that the correlation between the index in the long-term and short-term is inconsistent, and also shows that the correlation between the index will be affected by the financial crisis, or say, it will change as time varying.

A partir del estudio de la teoría Neobarroca de Severo Sarduy, puedo proponer que la novela Toda la luz del mediodía contiene, tanto en su temática como en su organización, rasgos afines al Neobarroco. Esta teoría resultó ser productiva como clave de lectura para esta novela, permitiendo interpretarla de un modo mucho más interesante.La simulación es una constante en la historia narrada. A partir de esta, la elipsis como desestabilización de una verdad cerrada; el trampantojo como forma de simulacro; la anamorfosis como encubrimiento; y el claroscuro como motivo transversal, son las perspectivas a partir de las que estructuraré mi estudio.

The indebtedness of Swedish households has more than doubled in the last ten decades despite the implementation of a mortgage ceiling and stricter amortization requirements. This study takes form to investigate how it is possible that debt related to housing is rising while new regulations against it has been set and how housing prices continues to increase when lending is supposed to be harder.This analysis estimates whether there are indications of an existing price bubble in the housing market of Stockholm. It is done by testing fundamental economic factors to the price index of housing in Stockholm, to see if they support the price development. If the analysis shows that housing prices cannot be predicted by the fundamental economic factors, it is possible that the price is a self-running series1 which could be an indicator of a price bubble. If fundamental factors that are being used as control variables seem to follow the same trend as the price development of the housing market, the speculation of price bubble will be rejected.

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第18400号 / 情博第515号 / 新制||情||91(附属図書館) / 31258 / 京都大学大学院情報学研究科数理工学専攻 / (主査)准教授 辻本 諭, 教授 中村 佳正, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

In this thesis we study various aspects of integrable methods in AdS3/CFT2 holog- raphy. These techniques come from exploiting special form of gauge compatible with asymptotic boundary conditions on the bulk fields in Chern Simons formulation of 3d gravity and higher spin theories. The integrable systems emerging are so called Toda field theories. The rigid structure of these theories allows us to learn more about certain gravitational solutions - multi centered solutions. One of the most interesting applications of the formalism developed is in the problem of black hole deconstruction and information paradox where we can read of the information about the temperature from the Toda field theory charges and. Aside of the gravitational applications we also study a vast generalization of the WZW to Toda field theory reduction and its connection to the Closed Toda systems. 1

Foreign direct investment flows are an important theme in the analysis of global capital flows. The study aims to analyse the effect a withdrawal of FDI has on the economy of Brazil. This is based on the sharp decrease FDI inflows have seen during 2020. The study is based on the theory of David Ricardo and microeconomic and macroeconomic FDI theories. A vector autoregressive model (VAR) was applied using the Toda andYamamoto methodology. The findings show that FDI inflows are positively affected by an increase in GDP and negatively affected by an increase in real average monthly wages. Furthermore, no effect of FDI on any of the considered variables could be determined. This can be attributed to the complexity of the Brazilian economy during the considered period of March 2012 – October 2021, as well as a possible omitted variable bias. This thesis is intended to serve as an avenue for further research on the effect FDI withdrawals have on the Brazilian economy.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第24038号 / 情博第794号 / 新制||情||134(附属図書館) / 京都大学大学院情報学研究科数理工学専攻 / (主査)准教授 辻本 諭, 教授 梅野 健, 教授 矢ヶ崎 一幸 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

<p>Solitons are solutions to a special class of nonlinear partial differential equations representing certain nonlinear systems. Solitons possess some very interesting transmission properties through nonlinear systems. In this thesis, we examine the properties of Toda solitons and Toda circuits. The time-frequency characteristics, time-bandwidth product, and energy of the single and composite solitons are studied. The response of the Toda circuit to both deterministic and stochastic inputs are analysed and examined via Volterra series and Runge-Kutta method. The application of the Toda solitons as a message carrier in a data communication system is then proposed. Both single user transmission and a multiplexing scheme exemplified by a two-user transmission scenario are considered. The bandwidth efficiency of the soliton communication system is studied and compared with other systems. The detection performance of the soliton communication system is studied and compared with traditional signalling schemes. Theoretical analysis and numerical results demonstrate that soliton system offers high bandwidth efficiency and high robustness against channel noise for amplitude detection due to the special properties of the soliton and the Toda circuit. The response of mismatched Toda circuit to input soliton is studied and the detection performance of soliton system with mismatched Toda circuit is also examined. It is shown that the slightly mismatched Toda circuit may not affect the detection performance of soliton system, while the mismatched Toda circuit with large mismatch coefficient may deteriorate the system performance seriously.</p> / Doctor of Philosophy (PhD)

Η παρούσα εργασία αφορά στη μελέτη Χαμιλτώνιων συστημάτων Ν μη γραμμικών ταλαντωτών, όπως είναι αυτό των Fermi Pasta και Ulam (FPU), με στόχο την βαθύτερη κατανόηση της δυναμικής των σχεδόν-περιοδικών τροχιών και του ρόλου των αντίστοιχων τόρων στο χώρο φάσεων, καθώς αυξάνουμε την ενέργεια Ε και τον αριθμό βαθμών ελευθερίας Ν του συστήματος. Το βασικό μας αποτέλεσμα είναι ότι υπάρχουν τόροι χαμηλής διάστασης, που προκύπτουν από τη συνέχεια των αντίστοιχων του γραμμικού συστήματος, οι οποίοι ευθύνονται για τις FPU επαναλήψεις και εμποδίζουν την ισοκατανομή της ενέργειας μεταξύ όλων των κανονικών τρόπων ταλάντωσης. Αναλύοντας ευστάθεια αυτών των τόρων, μπορέσαμε να δώσουμε μια πληρέστερη ερμηνεία στο Παράδοξο των FPU, συνδέοντας και συμπληρώνοντας έτσι δύο από τις επικρατέστερες ερμηνείες του εν λόγω φαινομένου. / The present work concerns the study of Hamiltonian systems of N nonlinear coupled oscillators, as it is the one by Fermi Pasta and Ulam (FPU), in order to understand the dynamics of quasi-periodic orbits and the role of their corresponding tori in phase space, as we increase the energy E and the number N of the degrees of freedom. Our fundamental result is that there exist tori of low dimension, that come from the continuation of the corresponding tori of the linear system, which are responsible for the FPU recurrences and prevent the system from equipartition of the energy among all normal modes. By investigating the stability of these tori, we achieved to provide a more complete explanation for the FPU paradox, connecting and supplementing in this way two of the most dominant approaches for this paradox.

Dans cette thèse, nous nous intéressons à plusieurs aspects des systèmes de racines des algèbres de Lie simples. Dans un premier temps, nous étudions les coordonnées des vecteurs propres des matrices de Cartan. Nous commençons par généraliser les travaux de physiciens qui ont montré que les masses des particules dans la théorie des champs de Toda affine sont égales aux coordonnées du vecteur propre de Perron -- Frobenius de la matrice de Cartan. Puis nous adoptons une approche différente, puisque nous utilisons des résultats de la théorie des singularités pour calculer les coordonnées des vecteurs propres de certains systèmes de racines. Dans un deuxième temps, en s'inspirant des idées de Givental, nous introduisons les matrices de Cartan q-déformées et étudions leur spectre et leurs vecteurs propres. Puis, nous proposons une q-déformation des équations de Toda et construisons des 1-solitons solutions en adaptant la méthode de Hirota, d'après les travaux de Hollowood. Enfin, notre intérêt se porte sur un ensemble de transformations agissant sur l'ensemble des bases ordonnées de racines comme le groupe de tresses. En particulier, nous étudions les bases distinguées, qui forment l'une des orbites de cette action, et des matrices que nous leur associons. / In this thesis, our goal is to study various aspects of root systems of simple Lie algebras. In the first part, we study the coordinates of the eigenvectors of the Cartan matrices. We start by generalizing the work of physicists who showed that the particle masses of the affine Toda field theory are equal to the coordinates of the Perron -- Frobenius eigenvector of the Cartan matrix. Then, we adopt another approach. Namely, using the ideas coming from the singularity theory, we compute the coordinates of the eigenvectors of some root systems. In the second part, inspired by Givental's ideas, we introduce q-deformations of Cartan matrices and we study their spectrum and their eigenvectors. Then, we propose a q-deformation of Toda's equations et compute 1-solitons solutions, using the Hirota's method and Hollowood's work. Finally, our interest is focused on a set of transformations which induce an action of the braid group on the set of ordered root basis. In particular, we study an orbit for this action, the set of distinguished basis and some associated matrices.