Forged videos of swapped faces, so-called deepfakes, have gained a  lot  of  attention in recent years. Methods for automated detection of this type of manipulation are also seeing rapid progress in their development. The purpose of this thesis work is to evaluate the possibility and effectiveness of using deep embeddings from facial recognition networks as base for detection of such deepfakes. In addition, the thesis aims to answer whether or not the identity embeddings contain information that can be used for detection while analyzed over time and if it is suitable to include information about the person's head pose in this analysis. To answer these questions, three classifiers are created with the intent to answer one question each. Their performances are compared with each other and it is shown that identity embeddings are suitable as a basis for deepfake detection. Temporal analysis of the embeddings also seem effective, at least for deepfake methods that only work on a frame-by-frame basis. Including information about head poses in the videos is shown to not improve a classifier like this.

Risks associated with fluctuating exchange rates affect investment cost and investor profitability. Approximately 50% of firms in emerging markets have significant exposure to fluctuating exchange rates. Grounded in principal-agent theory (PAT), the purpose of this case study was to explore hedging strategies to mitigate risks of fluctuating exchange rates. The population comprised a census sampling of 12 bank hedgers (risk managers and controllers) in Dar es Salaam in Tanzania, East Africa. Data collection involved semistructured interviews, casual observations of the work environment, and analysis of reports including risk management, internal control, and compliance policies. Data were analyzed by coding and grouping narrative segments and significant statements into themes of participants' experience in hedging exchange rate risks. Method triangulation and member checking were used to increase the trustworthiness of interpretations. Four themes emerged directly related to the PAT conceptual framework: training and skills development, management of hedging strategies and contracts, corporate governance, and benefits to management and the organization through effective compensation programs. A focus on training and skill development helped develop appropriate exchange rate hedging strategies and corporate governance improved compliance with laws, regulations, and policies. The benefits of effective hedging strategies include a reduction in cost and increase in profitability. The findings may help improve the soundness of professional hedging practices, which will increase the stability of the Tanzanian banking system.

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In this thesis, we study how sovereign credit default swaps are able to measure systemic risk as well as how they can be used to construct optimal portfolios to minimize risk. We define the clustering coefficient as a proxy for systemic risk and design an optimization problem with the goal of minimizing the mean absolute deviation of the clustering coefficient on a group of nine European countries. Additionally, we define a metric we call the diversity score that measures the diversification of any given portfolio. We solve this problem for a baseline set of parameters, then spend the remainder of the thesis modifying these parameters to investigate how the optimal solution and diversity score are impacted.

No / Purpose To document the magnitude of any learning effect for short-wavelength automated perimetry (SWAP) in patients with either ocular hypertension (OHT) or open-angle glaucoma (OAG) who are experienced in standard automated perimetry (SAP). Participants Thirty-five patients (22 with OHT and 13 with OAG) who had previously undergone at least 3 threshold SAP visual field examinations with the Humphrey Field Analyzer (HFA; Carl Zeiss Meditech Inc., Dublin, CA), and 9 patients with OHT who had not previously undertaken any form of perimetry. Methods Each patient attended for SWAP on 5 occasions, each separated by 1 week. At each visit, both eyes were examined using Program 24-2 of the HFA; the right eye was always examined before the left eye. Main Outcome Measures (1) Change over the 5 examinations, in each eye, of the visual field indices Mean Deviation (MD), Short-term Fluctuation (SF), Pattern Standard Deviation (PSD), and Corrected Pattern Standard Deviation. (2) Change in each eye between Visits 1 and 5 in proportionate Mean Sensitivity (pMS) for the central annulus of stimulus locations compared with that for the peripheral annulus thereby determining the influence of stimulus eccentricity on any alteration in sensitivity. (3) Change between Visits 1 and 5 in the number and magnitude of the Pattern Deviation (PD) probability levels associated with any alteration in sensitivity. Results The MD, SF, and PSD each improved over the 5 examinations (each at P<0.001). The improvement in pMS between Visits 1 and 5 was greater for the peripheral annulus than for the central annulus by approximately twofold for the patients with OAG. Considerable variation was present between patients, within and between groups, in the number of locations exhibiting an improving sensitivity between Visits 1 and 5 by 1 or more PD probability levels. Conclusions Care should be taken to ensure that, during the initial examinations, apparent field loss with SWAP in patients exhibiting a normal field by SAP is not the result of inexperience in SWAP. Apparently deeper or wider field loss in the initial examinations with SWAP compared with that exhibited by SAP in OAG also may arise from inexperience in SWAP.

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In the thesis we perform analysis of systemic risk in the financial and energy sector in Europe. As the econometric tool for estimating dependencies across the subjects we employ factor copula model with GAS dynamics of Oh & Patton (2013b). We apply this model to daily CDS spreads. Based on the estimated results we perform Monte Carlo simulations in order to obtain future values of CDS spreads and measure probability of systemic events. We conclude that substantially higher systemic risk is present within the financial sector. We also find that the most systemic companies from both sectors come from Spain. JEL Classification C53, C55, C58, G17 Keywords Credit Default Swap, Energy Sector, Factor Copula, Financial Sector, Generalized Autore- gressive Score Model, Systemic Risk Author's e-mail matej.nevrla@gmail.com Supervisor's e-mail barunik@fsv.cuni.cz

Cette thèse s’intéresse à la gestion du risque climatique par l’utilisation des produits dérivés climatiques. Les travaux réalisés dans le cadre de cette thèse sont une contribution aux aspects statistiques, économétriques et financiers de la modélisation et de l'évaluation des produits dérivés climatiques. Un intérêt particulier a été accordé au contexte marocain aussi bien au niveau du volet qualitatif que quantitatif. En plus des développements théoriques que nous avons apportés (tests statistiques pour vérifier l’impact du climat sur l’économie, amélioration d’un modèle de prévision de la température moyenne quotidienne, confirmation du choix de la température moyenne, au lieu des températures extrêmes, comme sous-jacent pour les contrats basés sur la température, etc.), nous avons proposé des cas de gestion entre opérateurs économiques marocains exerçant des activités sensibles à l’aléa climatique avec des profils de risque différents en leur apportant des solutions de couverture basées sur l’utilisation de produits dérivés climatiques. / This thesis focuses on the weather risk management by using weather derivatives. The work done in this thesis is a contribution to statistics, econometric and financial aspects of the modeling and the evaluation of weather derivatives. Particular attention was paid to the Moroccan context both in a qualitative point of view. In additionto theoretical developments that we have made (statistical tests to verify the impact of weather conditions on the economy, improvement of a model to forecast daily average temperatures, confirming the choice of the average temperature instead of extreme temperatures as the preferred under lying for contracts based on temperature, etc.), we also proposed case studies with Moroccan economic actors carrying out their weather sensitive activities and having different risk profiles and we provide them hedging solutions based on the use of weather derivatives.

Die vorliegende Dissertation besteht aus drei Kapiteln über die Investmentfonds. Das erste Kapitel befasst sich mit der Rolle der Fondsmanager in der Bilanzverschönerung. Auf Basis der Analyse der Karrierewege von amerikanischen Fondsmanagern werden signifikante zusammenwirkende Manager-Fixed-Effects identifiziert, die nach der Kontrolle der endogenen Matching-Probleme immer noch robust sind. Die geschätzten Manager-Fixed-Effects haben signifikante Einflüsse auf die Out-of-Sample-Vorhersagen. Außerdem wird festgestellt, dass die Verriegelungen der Investmentfonds, die von gemeinsamen Managern verwaltet wurden, wichtige Kanäle für die Bilanzverschönerung verursachen. Das zweite Kapitel beschäftigt sich mit den Investmentstrategien der Fonds im Hinblick auf die Nutzung von Credit Default Swaps (CDS). Die Zuordnung der CDS-Positionen der Investmentfonds zu ihrem Bestandportfolio bietet eine neue Methodik zur Identifizierung der CDS-Strategien und kompensiert somit die Analysen der existierenden Literatur auf der Makroebene. Die Ergebnisse zeigen, dass die Anreize zur Risikoreduzierung die Spekulationsanreize dominieren, insbesondere, wenn die Kreditexposition durch ungedeckte Leerverkäufe der CDS-Verträge erhöht wird. Die erfahrenen Fondsmanager tendieren dazu, mehr Kreditrisiko in Kauf zu nehmen, während es für die Fondsmanagerinnen wahrscheinlicher als für ihre männlichen Kollegen ist, gegen das bestehende Risiko abzusichern. Der letzte Teil nimmt die Pleite von Lehman Brothers unter die Lupe, um sich mit der daraus resultierenden unerwarteten Schließung der CDS-Positionen als einem natürlichen Experiment auseinanderzusetzten. Diese Studie dient zur Untersuchung der Risiko- und Leistungsimplikationen der CDS-Investments der Fonds. Die Investmentfonds besitzen bei ihren CDS-Transaktionen im Durchschnitt einen beachtlichen Teil Extremrisiko. Während die CDS-Nutzer von guten Gesamtmarktlagen profitieren, erleiden sie unter Verlusten bei geclusterten Ausfällen. / This dissertation comprises of three chapters on mutual funds. The first chapter establishes the role of managers in the deceptive practice of window dressing. Employing comprehensive career history of U.S. mutual fund managers, I find strong jointly significant manager fixed effects, which are robust after addressing endogenous matching concerns. The estimated manager fixed effects are significant in making out-of-sample predictions. Further I establish that mutual fund interlocks through common managers are important channels that spread window dressing. The second chapter studies the investment strategies of mutual funds regarding their use of credit default swaps (CDS). Matches between mutual funds’ CDS positions and their underlying portfolio in the holdings facilitate a new approach in identifying CDS strategies that complements the “macro” level analyses in the existing literature. I find risk reducing incentives are dominated by speculative incentives, especially those to increase credit exposure via naked short CDS contracts. Experienced fund managers tend to take on more credit risk, while female managers are more likely to hedge comparing with their male peers. The third chapter employs the collapse of Lehman Brothers and the resulting sudden closures of CDS positions as a natural experiment to examine the risk and performance implications of mutual funds’ CDS investments. Funds on average load up on a significant amount of tail risk by trading CDS. While CDS users benefit when market conditions are favorable, they suffer during periods of clustered defaults.

L’acquisition de paramètres physiques tels que la température, la pression, le couple et la vitesse est nécessaire aux systèmes aéronautiques critiques afin d’atteindre et d’assurer les performances requises de disponibilité et de sécurité de fonctionnement. L’acquisition de ces paramètres physiques nécessite donc la mise en oeuvre de technologies et de techniques hautement éprouvées pouvant supporter les conditions de fonctionnement sévères.L'objectif des travaux présentés dans ce mémoire est de proposer une nouvelle architecture de chaîne d'acquisition de grandeurs physiques pour être intégrée à un système aéronautique critique. Le but de cette architecture est d'améliorer l'intégrité des données mesurées tout en maintenant leur disponibilité et le niveau de sûreté de fonctionnement propre aux systèmes aéronautiques de haute criticité. La solution se déploie sous la forme d'une amélioration de la tolérance aux défauts de la chaîne de traitement du signal issu du capteur. Pour ce faire, nous intégrons des fonctions supplémentaires, dont le modèle mathématique de la chaîne d'acquisition, rendant ainsi le système plus intelligent.Dans le cadre de nos travaux de recherche, nous nous appuyons sur les spécifications techniques d'un projet industriel typique des systèmes aéronautiques critiques, qui est le coeur de notre thématique principale. / The acquisition of physical parameters as such as temperature, pressure, torque, and speed are necessary to flight critical systems in order to reach and ensure safety and availability required. Consequently, it requires implementing high technologies and techniques which are able to work in rugged environments.The aim of our work is to design a new architecture for sensor acquisition systems in order to be integrated onto a flight critical system. The goal of the architecture is to ensure data integrity, system's availability and safety relative to airborne critical systems. The solution adds the fault tolerance ability to the signal conditioning. Consequently, we implement additional functionalities, as such as mathematical model of the signal conditioning, in order to make the acquisition system more intelligent.Our research work is partially based on technical specifications from SYRENA project, which is a typical example of flight critical systems, which is the main thematic of our purpose.