L’objectif principal de la thèse est : l’étude des fluctuations de fonctionnelles du spectre de grandes matrices aléatoires, la construction d’estimateurs consistants et l’étude de leurs performances, dans la situation où la dimension des observations est du même ordre que le nombre des observations disponibles. Il y aura deux grandes parties dans cette thèse. La première concerne la contribution méthodologique. Nous ferons l’étude des fluctuations pour les statistiques linéaires des valeurs propres du modèle ’information-plus-bruit’ pour des fonctionnelles analytiques, et étendrons ces résultats au cas des fonctionnelles non analytiques. Le procédé d’extension est fondé sur des méthodes d’interpolation avec des quantités gaussiennes. Ce procédé est appliqué aux grandes matrices de covariance empirique. L’autre grande partie sera consacrée à l’estimation des valeurs propres de la vraie covariance à partir d’une matrice de covariance empirique en grande dimension et l’étude de son comportement. Nous proposons un nouvel estimateur consistant et étudions ces fluctuations. En communications sans fil, cette procédure permet à un réseau secondaire d’établir la présence de ressources spectrales disponibles. / The principal objective of this thesis is : the study of the fluctuations of functionals of spectrum for large random matrices, the construction of consistent estimators and the study of their performances, in the situation where the dimension of observations is with the same order as the number of the available observations. There will be two parts in the report : the methodological contribution and the estimation in large-dimensional data. As to the methodological contribution, we will study the fluctuations for spectral linear statistics of the model ’information-plus-noise’ for analytic functionals, and the extension for non-analytic functionals. The extension is based on the interpolation between random variables and Gaussian terms. This method can be applied to empirical covariance matrices. Another part consists in the estimation of the eigenvalues of the real covariance from the empirical covariance for high dimensional data and the study of its performance. We propose a new consistent estimator and the fluctuation of the estimator will be studied . In wireless communications, this procedure permits a secondary network to ensure the presence of the available spectral resources.

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The sample are prepared by co-sintering the pure 3D ferromagnetic colossal magnetoresistance La0.7Sr0.3MnO3 (113) and the 2D spin-glass magnetic insulator La0.7Sr0.3MnO3¡ESrO (214) with an ordered 2D magnetic-insulator superstructure. Increase the magnetic scattering and collision probabilities of the carries on the interface of the two kinds of CMR materials. The LFMR is enhanced by the electron scattering between these two phases. (La0.7Sr1.3MnO4)x / ( La0.7Sr0.3MnO3)1-x composites with x=0.1¡B0.15¡B0.2¡B0.3¡B0.5 have been fabricated by sintering the mixture of the pure La0.7Sr0.3MnO3 (n=¡Û) and the La0.7Sr1.3MnO4(n=1) at 1400 for 24 hours. Part of the 113 phase reacted with 214 phase during the 1400¢J annealing process and formed the antiferromagnetic phase , La1-2ySr2+2yMn2O7 (327), with the unknown content, y. The £l-H curve shows the magnetic interaction between the interface grain numbers of the 113 and 327 affects the effect of the low field magnetoresistance effect.

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This thesis deals with the negative interrelationship between climate fluctuation and cattle ranching during the 1880s. The focus is on three large ranches that were used as case studies on the Texas Panhandle. These ranches were selected because of their size, longevity, and the number of primary documents that were available at the Panhandle Plains Museum and Archive in Canyon, Texas. The temporal focus is from 1880 to 1890. The primary documents that have been examined are letters from ranchers to the Capitol Syndicates that owned the ranch and the financial documents of each ranch. Scientific journals that examined grassland ecology, animal ecology, and climate were used in conjunction with the primary documents. The combination of these sources led to a nuanced reinterpretation of a cattle disaster from the 1880s. The disaster was a massive loss of stock through a series of extremely cold winters and a drought that lasted several years. In the wake of this disaster, through the use of technology, these ranches were able to recover and increase their stock numbers beyond what they were prior to the years dominated by stock losses and low cattle prices.

This thesis deals with the negative interrelationship between climate fluctuation and cattle ranching during the 1880s. The focus is on three large ranches that were used as case studies on the Texas Panhandle. These ranches were selected because of their size, longevity, and the number of primary documents that were available at the Panhandle Plains Museum and Archive in Canyon, Texas. The temporal focus is from 1880 to 1890. The primary documents that have been examined are letters from ranchers to the Capitol Syndicates that owned the ranch and the financial documents of each ranch. Scientific journals that examined grassland ecology, animal ecology, and climate were used in conjunction with the primary documents. The combination of these sources led to a nuanced reinterpretation of a cattle disaster from the 1880s. The disaster was a massive loss of stock through a series of extremely cold winters and a drought that lasted several years. In the wake of this disaster, through the use of technology, these ranches were able to recover and increase their stock numbers beyond what they were prior to the years dominated by stock losses and low cattle prices.

Dans les années 60 et avant, le marché international de l’aluminium était présenté comme un cas d’école en matière d’organisation oligopolistique des firmes. En effet, un petit nombre de grands groupes fortement intégrés (les 6 Majeurs) contrôlaient la quasi-totalité du secteur de l’aluminium, des opérations d’extraction de la bauxite, à la fabrication de produits finis à base d’aluminium, en passant par la production d’alumine et d’aluminium en lingots. A partir des années 70, ce monopole est de plus en plus contesté, notamment par des entreprises sur-liquides venues principalement des secteurs miniers et par des entreprises étatiques porteuses de motivations différentes. La création en décembre 1978 du contrat Aluminium au London Metal Exchange (LME) sonne le glas du monopole constitué par les 6 Majeurs. On passe alors d’un système de prix- producteurs, à un véritable système de prix de marché L’objectif de cette thèse est de vérifier, si le LME, bourse pionnière et marché de référence pour les métaux non-ferreux, remplit efficacement ses fonctions financières concernant l’aluminium : Information sur les prix et l’état du marché, protection contractuelle contre les risques de fluctuations des prix, stabilisation des cours. / In the 1960s and before, the international aluminium market has been hold up as a paradigm for oligopolistic company organisation. A small number of strongly integrated conglomerates (the six Majors) did indeed control virtually the entire aluminium sector, from bauxite extraction to alumin and aluminum bar production as well as the manufacturing of finished aluminium products. From the 1970s onwards, this monopoly has been more and more called into question, in particular by cash-fuelled mining corporations and state-owned companies driven by different motivations. When the London Metal Exchange (LME) introduced the Aluminium contract in December 1978, the days of the 6 Majors’ monopoly were counted. From there on, prices have been fixed by producers and the market. This thesis aims at determining whether the LME, a pioneering exchange and the prime market for non-iron metals, efficiently fulfils its financial functions concerning aluminium: information about prices and the market situation, legal protection against price fluctuation risks, price stabilization.

This dissertation includes two different groups of objects in macroeconomics and financial economics. In macroeconomics, the aggregate investment fluctuation and its relation to an individual firm's behavior have been extensively studied for the past three decades. Most studies on the interdependence behavior of firms' investment focus on the key issue of separating a firm's reaction to others' behavior from reaction to common shocks. However, few researchers have addressed the issue of isolating this endogenous effect from a statistical and econometrical approach. The first essay starts with a comprehensive review of the investment fluctuation and firms' interdependence behavior, followed by an econometric model of lumpy investments and an analysis of the binary choice behavior of firms'investments. The last part of the first essay investigates the unique characteristics of the Italian economy and discusses the economic policy implications of our research findings. We ask a similar question in the field of financial economics: Where does stock market volatility come from? The literature on the sources of such volatility is abundant. As a result of the availability of high-frequency financial data, attention has been increasingly directed at the modeling of intraday volatility of asset prices and returns. However, no empirical research of intraday volatility analysis has been applied at both a single stock level and industry level in the food industry. The second essay is aimed at filling this gap by modeling and testing intraday volatility of asset prices and returns. It starts with a modified High Frequency Multiplicative Components GARCH (Generalized Autoregressive Conditional Heteroscedasticity) model, which breaks daily volatility into three parts: daily volatility, deterministic intraday volatility, and stochastic intraday volatility. Then we apply this econometric model to a single firm as well as the whole food industry using the Trade and Quote Data and Center for Research in Security Prices data. This study finds that there is little connection between the intraday return and overnight return. There exists, however, strong evidence that the food recall announcements have negative impacts on asset returns of the associated publicly traded firms.

The diploma thesis focuses on the fluctuation of production workers specific establishment company Vodňanská poultry, a. s. The first part is devoted to explanation of the theoretical notions related to the topic - the most frequent causes, the methods of measurement or the costs associated with the departures of employees. Theoretical knowledges are in the next stage applicate for analysis and evaluation of the situation of the selected company. The final part contains suggestions for improving identified problems to reduce fluctuation.