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É bem conhecido que os intervalos proibidos de energia (gaps) de sólidos semicondutores e isolantes calculados resolvendo-se a equação de Kohn-Sham (KS) com alguma aproximação ao funcional de troca e correlação (XC) da teoria do funcional da densidade (density-functional theory, DFT) são geralmente muito pequenos quando comparados com os valores de gap obtidos experimentalmente. Estes erros, que podem atingir 100%, indicam uma falha nos funcionais de troca e correlação aproximados usados na DFT. Em particular, encontrou-se que o potencial XC, obtido através da derivada do funcional de energia XC, apresenta uma descontinuidade (xc ) quando um elétron extra é adicionado. Portanto, mesmo o gap KS exato não é idêntico ao gap verdadeiro, pois pode haver uma descontinuidade no funcional XC que tem de ser adicionado ao gap KS. Este trabalho propõe uma nova abordagem matemática para o cálculo da descontinuidade do funcional XC e a correção do gap. Inicialmente, as conseqüências desta nova abordagem foram estudadas para os 36 primeiros átomos da tabela periódica (do átomo de hidrogênio, H, ao átomo de criptônio, Kr), utilizando-se para isso os funcionais LDA, GGA e também funcionais híbridos, em combinação com diversos conjuntos de base. A partir da comparação entre valores da descontinuidade calculados teoricamente e resultados prévios da descontinuidade obtidos na literatura para os átomos de lítio (Li) e berílio (Be), foram escolhidos os melhores funcionais em combinação com as melhores bases. Num segundo passo, a nova metodologia para o cálculo da descontinuidade, com os melhores funcionais e bases eleitos, foi aplicada ao cálculo de fragmentos de poliacetileno. / It is well-known that the energy gaps of insulators and semiconductors calculated via the Kohn-Sham (KS) scheme with some approximation to the exchange-correlation (XC) functional of density-functional theory (DFT) are in general too small when compared to experimental gaps. These errors, which can be up to 100%, indicate a fault in the approximate exchange-correlation functionals currently available in DFT. Specifically, it was found that the XC potential, the functional derivative of the XC energy, shows a discontinuity (xc ) when an electron is added. Therefore, the exact KS gap is not identical to true gap, since there can be a discontinuity in the XC functional which should be added to KS gap. The present work proposes a new mathematical approach to the calculation of the discontinuity of the XC functional and the correction of the gap. In a first step, the consequences of this new approach were studied for the first 36 atoms of the periodic table (from Hydrogen, H, to Krypton, Kr), with the LDA and GGA functionals and also some hybrids, in combination with several kinds of basis set. From the comparison between calculated discontinuity values and previous results for the discontinuity reported in the literature for the Lithium (Li) and Beryllium (Be) atoms, the best functionals in combination with the best basis set were selected. In a second step, the new methodology with the best functionals/basis set was applied to the calculation of energy gaps of polyacetylene fragments.

Les ailes d’avion sont composées d’une part croissante de pièces composites. Afin de réduire les coûts de production et de certification des assemblages, une nouvelle architecture en caissons creux, en fabrication ‘one shot’, est proposée. Cette structure contient des liaisons en T entre des sections sandwichs. Le comportement et les modes de dégradation de cette structure sont méconnus. Une méthodologie multi-échelle est mise en place pour appréhender l’endommagement de la voilure et ainsi améliorer l’outil numérique de dimensionnement.Tout d’abord, des systèmes essai – éprouvette spécifiques sont conçus pour représenter les modes de sollicitation de la liaison dans la voilure. Une analyse fine des essais instrumentés permet d’appréhender les scénarios d’endommagement pour chaque mode. Les premiers stades sont principalement pilotés par le nid d’abeille (cisaillement, déchirement). Un modèle numérique 3D permet de représenter les premiers stades d’endommagement. Il est construit avec une représentation en coque du nid d’abeille intégrant les variabilités de la structure (collage, déformation de cellules). Egalement, une loi de comportement élasto-plastique endommageable des matériaux constitutifs de la voilure (plis unidirectionnels et tissés) est développée et implémentée pour les stratifiés multi-matériaux. Sur les bases de ce modèle, une modélisation simplifiée du comportement de la liaison est développée. Elle consiste à assembler des coques par des connecteurs avec des propriétés élasto-plastiques. La création d’un calcul prédictif de voilure intègre le modèle simplifié de comportement de la liaison. / Aircraft wings are composed of a growing composite part portion. To reduce production and assembly certification costs, a new hollow box architecture is proposed with a one shot manufacturing process. This structure includes T-connections between honeycomb sandwich panels. Mechanical behavior and degradation modes are unknown for this structure. A multiscale methodology is developed to deepen the wing damage knowledge and to improve the numerical sizing tool.Firstly, specimen-testing couples are designed to represent the loading modes of the T-connections. A detailed analysis of instrumented testing allows to understand the damage scenarios for each mode. The first damage stages are mainly driven by the honeycomb behavior (shear, tear). A 3D numerical model represents the first damage stages. It is built with a shell representation of the honeycomb which integrates the structure variability (bonding, deformation of cells). An elastic-plastic damage law (unidirectional and woven plies) is developed for the wing materials. Then, it is implemented for multi material laminate. Based on this model, a simplified modeling is realized for the connection behavior. It consists of assembling shells by connectors with elastic-plastic properties. Building a predictive wing simulation requires a simplified model integration of the T-bond behavior.

Recently there has been a renewed interest in formative measurement and its role in properly specified models. Formative measurement models are difficult to identify, and hence to estimate and test. Existing solutions to the identification problem are shown to not adequately represent the formative constructs of interest. We propose a new two-step approach to operationalize a formatively measured construct that allows a closely matched common factor equivalent to be included in any structural equation model. We provide an artificial example and an original empirical study of privacy to illustrate our approach. Detailed proofs are given in an appendix.

Green liquor dreg (GLD) is a residual product that could be a solution to the problem with acid rock drainage. More information about how this material reacts and is affected when in contact with acid rock drainage (ARD) is needed. Different acidic media was used to investigate trace element leaching and the possible spectral changes using FTIR. It was possible to detect changes between samples based on the exposure for different acidic conditions. Most peaks were found below 1 500 cm-1 which complicates the interpretation. For enabling the use of multivariate analysis the spectral data needed to be pre-treated and after this it was possible to see groupings and directions based on exposure. Different tendencies are seen for the trace elements, where some element leaching increased at lower pH and some elements decreased leaching at lower pH. This could partly be due to the formation of salts with low solubility such as gypsum and anglesite when leached with sulphuric acid.

The first measurement of the spin correlation strength in pairs of top quarks at √s=8 TeV is presented, using data collected using the ATLAS detector, corresponding to an integrated luminosity of 20.3 fb⁻¹. Dileptonically decaying tt^- events are selected with two high-pT leptons and at least two jets, one of which is required to be b-tagged. The azimuthal angle between the two charged leptons, Δφ, is used to measure the degree of spin correlation of top quark pairs. The extracted value of fSM, which is a measure of the spin-correlation strength, is fSM=1.20 ± 0.14. This is the most precise spin-correlation measurement to date. Using the Δφ distribution, a search for Supersymmetric top squarks is performed, with the assumption that the top squarks decay to a top quark and a neutralino. No excess of events is observed and top squarks with masses between the top quark mass and 191 GeV are excluded at 95% confidence level, extending previous limits.

The thesis focuses at the evolution of cryptocurrencies or more precisely at the competition process between them in expanding to broader usage. The first main goal of the work is to find out, whether Bitcoin, as the first and still most capitalized cryptocurrency, has an advantage of higher maturity than alternative cryptocurrencies. The second goal is to analyze whether the individual cryptocurrencies are perceived individually by market participants, which could grant the alternative cryptocurrencies an option to compete with Bitcoin by offering better features as safer technology or faster transaction. The analysis of volatility patterns in their exchange rates via various GARCH models suggests that Bitcoin still has advantage in higher maturity. The analysis of the correlation between various alternative cryptocurrencies and Bitcoin finds positive correlation and thus suggests that the cryptocurrencies are rather perceived together. JEL Classification G17, G19, E40, E41 Keywords cryptocurrencies, volatility, GARCH, money, correlation Author's e-mail 79828843@fsv.cuni.cz Supervisor's e-mail frantisek.cech@fsv.cuni.cz

Magister Scientiae - MSc / High-spin states in the oblate deformed odd-odd thallium nucleus ( ) 109 190 81 Tl have been investigated through the reaction 175Lu(20Ne, 5n)190Tl at a beam energy of 115 MeV. The gamma rays emitted from 190Tl nucleus were detected with Ge detectors using the AFRODITE array at iThemba LABS, South Africa. Gamma-gamma coincidence data were obtained and used to construct the level scheme. In this work, Directional Correlations from Oriented (DCO) state ratios and linear polarization anisotropies were measured in order to deduce spin and parity of energy levels in the decay scheme. It was possible to determine the spin and parity of two additional signature-partner bands which decay to the ground-state band. / South Africa