Hedonic pricing methods and GIS (Geographic Information Systems) were used to evaluate relationships between sale price of single family homes and landscape fragmentation and natural land cover. Spatial regression analyses found that sale prices increase as landscapes become less fragmented and the amount of natural land cover around a home increases. The projected growth in population and employment in the Richmond, Virginia region and subsequent increases in land development and landscape fragmentation presents a challenge to sustaining intact healthy ecosystems in the Richmond region. Spatial regression analyses helped illuminate how land cover patterns influence sale prices and landscape patterns that are economically and ecologically advantageous.

The first part of this dissertation examines the impact of financial development on different countries holdings of U.S securities. The difference between the US weight in the global market capitalization and the US weight in developed and developing countries is tested through a panel data analysis. We find that most countries tend to overweight their US debt portfolio which is strongly related to their financial market development. When holdings of US debts and equity are low, financial market development is high; in developing countries, holding less US equity in their portfolio causes country to get better financial development. In developed countries there is no causation effect; a simple negative relation between financial development and countries holding of US securities is observed and countries tend to hold relatively less US securities through years. The second part of this dissertation examines whether economic conditions, affect carve-outs frequency and returns. This paper investigates the effect of expansion and recession, and industry sectors on carve out issued in the US over 1982 to 2009. We find that the number of carve-outs is higher in expansion than recession. However, the cumulative abnormal returns are higher during recession which is explained by the higher adverse selection during this period. Further, we find that the difference of abnormal returns between expansion and recession is significant and we also observe that high-tech or non-high-tech industries that undertake carve-out have positive higher abnormal return during recession. Therefore, within a same industry sector, carve-out abnormal returns are impacted by the economy cycle. However difference of abnormal returns between industry sector, high-tech and non-high-tech industries, is not significant.

O objetivo deste trabalho é comparar as estruturas de vizinhanças espaciais ou matrizes de pesos espaciais da classe de modelos autorregressivos e de médias móveis espaço-temporais (STARMA). O modelo STARMA é empregado para descrever dados de séries temporais espacialmente localizados, ele é caracterizado pela dependência linear defasada tanto no espaço quanto no tempo. Foram realizadas simulações utilizando vários modelos de covariância espaço-temporal para comparar diferentes estruturas de construção da matriz de pesos espaciais com a finalidade de identificar a melhor matriz. As matrizes espaciais com pesos exponenciais apresentaram os melhores desempenhos de ajuste dos modelos STAR; e mostram uma estabilidade em relação à medida de ajuste. Por fim para ilustração, será ajustado um modelo STARMA para um conjunto de dados mensais do índice FIPEZAP de preço imobiliário de venda para apartamentos de dois dormitórios de seis cidades metropolitanas de São Paulo. / The objective of this work is to compare spatial neighborhoods structures, or the same as spatial weights matrices of the class of space-time autoregressive and moving average models STARMA. The STARMA model is used to describe spatially localized time series datas, it is characterized by the linear dependence lagged both in space and time. Simulations were performed using several space-time covariance models to compare different structures of construction of the weight matrix with the purpose of identifying the best matrix. The spatial matrices with exponential weights presented the best adjustment performances of the STAR models ans showed a stability in relation to the adjustment measure. Finally, for illustration, a STARMA model will be adjusted for a set of monthly data of the FIPEZAP real estate price index for two bedroom apartments in six metropolitan cities of São Paulo.

A modelagem de processos espaço-temporais é de suma importância para dados climatológicos, visto que o clima sofre influência temporal e espacial. A classe de modelos STARMA, autorregressivo e de médias móveis espaço-temporal, adequa-se a esses processos, porém, não há, na literatura, um estudo sobre o melhor método para quantificar a dependência espacial, e não é sabido se há uma diferença entre os métodos para esses modelos. Logo, neste trabalho, é realizado um estudo de simulações do modelo STAR, utilizando-se diferentes formas para obter os pesos espaciais. Após concluir as simulações é realizado o ajuste de um modelo STARIMA para um conjunto de dados de médias mensais de temperaturas mínimas diárias coletadas em uma mesorregião localizada no Oeste do Estado do Paraná. Este trabalho é separado em dois artigos e ambos são realizados utilizando-se o programa R. O primeiro é o estudo de simulações, chegando-se à conclusão de que o método para determinar a dependência espacial interfere no resultado da modelagem e depende da região em estudo. No segundo artigo, conclui-se que o inverso da distância é a melhor opção para a matriz de pesos e um modelo STARIMA sazonal tem o melhor ajuste para o conjunto de dados em questão. / Process modeling spatio-temporal is of great importance for climatological data, once that the climate undergoes spatial and temporal influence. The class of models STARMA, autoregressive models and spatio-temporal moving averages, are suitable to the these processes, however, for these models, there is not a study about the best method to quantify the spatial dependence, and/or it is not known whether there is a difference between the methods for these models. In this thesis, a study simulations of the STAR model using different forms for the spatial weights is performed. After the simulation procedure, the STARIMA model is fitted to the real dataset of monthly mean daily minimum temperatures collected in a mesoregion located to the west of the state of Paraná. This thesis is separated into two papers and both are performed using the statistical software R. The first one is the simulation study that concludes that the method for determining the spatial dependence interferes with results of the modeling and depends on the region under study. In the second paper, it is concluded that the inverse distance is the best option for the weight matrix and a seasonal STARIMA model has the best fit for the data set.

O objetivo deste trabalho é comparar as estruturas de vizinhanças espaciais ou matrizes de pesos espaciais da classe de modelos autorregressivos e de médias móveis espaço-temporais (STARMA). O modelo STARMA é empregado para descrever dados de séries temporais espacialmente localizados, ele é caracterizado pela dependência linear defasada tanto no espaço quanto no tempo. Foram realizadas simulações utilizando vários modelos de covariância espaço-temporal para comparar diferentes estruturas de construção da matriz de pesos espaciais com a finalidade de identificar a melhor matriz. As matrizes espaciais com pesos exponenciais apresentaram os melhores desempenhos de ajuste dos modelos STAR; e mostram uma estabilidade em relação à medida de ajuste. Por fim para ilustração, será ajustado um modelo STARMA para um conjunto de dados mensais do índice FIPEZAP de preço imobiliário de venda para apartamentos de dois dormitórios de seis cidades metropolitanas de São Paulo. / The objective of this work is to compare spatial neighborhoods structures, or the same as spatial weights matrices of the class of space-time autoregressive and moving average models STARMA. The STARMA model is used to describe spatially localized time series datas, it is characterized by the linear dependence lagged both in space and time. Simulations were performed using several space-time covariance models to compare different structures of construction of the weight matrix with the purpose of identifying the best matrix. The spatial matrices with exponential weights presented the best adjustment performances of the STAR models ans showed a stability in relation to the adjustment measure. Finally, for illustration, a STARMA model will be adjusted for a set of monthly data of the FIPEZAP real estate price index for two bedroom apartments in six metropolitan cities of São Paulo.

This thesis is a representation of my contribution to the paper of the same name I co-author with Dr. Wasilkowski. It deals with linear problems defined on γ-weighted normed spaces of functions with infinitely many variables. In particular, I describe methods and discuss results for ε-truncation and ε-superposition methods. I show through these results that the ε-truncation and ε-superposition dimensions are small under modest error demand ε. These positive results are derived for product weights and the so-called anchored decomposition.

Disturbances such as fire and grazing can degrade landscapes, but they can also rejuvenate them. I evaluated: 1) the practicality of strategically timed (fall), high intensity browsing of sagebrush (Artemisia tridentata ssp. tridentata, ssp. wyomingensis) by cattle; 2) the foraging behavior and body weights of cattle with varying levels of experience browsing sagebrush; and 3) the ensuing responses of grasses, forbs, and sagebrush to cattle grazing. In spatially and temporally replicated trials from 2007 to 2009, fall grazing by cattle reduced the abundance of sagebrush and promoted production of grasses and forbs. The cattle used in these trials were challenged to learn to eat sagebrush in the unfamiliar circumstance of confinement in small pastures. Throughout the trials from 2007 to 2009, pregnant cows with calves (2007), bred yearling heifers (2008), and first-calf heifer/calf pairs (2009) supplemented with protein and energy – to mitigate the effects of terpenes in big sagebrush – learned to select sagebrush as a significant portion of their diet. In virtually every case, experienced animals consistently used more sagebrush and lost less weight, or actually gained more weight, than naive animals in 2008 and 2009. My research suggests grazing by cattle during fall can be effective, biologically and economically, and can lead to habitat renovation and resilience. Moreover, grazing can create locally adapted systems in ways that landscape manipulations with chemical and mechanical treatments and prescribed fire cannot. These “technological fixes” are increasingly impractical due to environmental concerns, the high costs of fossil fuels, and the need to repeat outcome-based treatments rather than incorporating process-based approaches into managing landscapes. Rather than attempting to convert sagebrush steppe landscapes to grass at extravagant costs, as we have done historically, we must now consider ways to create locally adapted herds of livestock and complementary management practices to ensure long-term health of sagebrush steppe. As many ranchers already feed hay to cows during winter, using sagebrush steppe vegetation as an additional forage resource would allow ranchers to feed roughly half the hay, which would greatly reduce winter feed costs. In addition to financial savings in hay, the secondary benefits from improving sagebrush steppe condition and productivity would result in habitat improvements for both livestock and wildlife.

Abstract not available

The thesis presents the results of our research on symmetry for some semilinear elliptic problems and on existence of solution for quasilinear problems involving singularities. The text is composed of two parts, each of which begins with a specific introduction. The first part is devoted to symmetry and symmetry-breaking results. We study a class of partial differential equations involving radial weights on balls, annuli or $R^N$ --where these weights are unbounded--. We show in particular that on unbounded domains, focusing on symmetric functions permits to recover compactness, which implies existence of solutions. Then, we stress the fact that symmetry-breaking occurs on bounded domains, depending both on the weights and on the nonlinearity of the equation. We also show that for the considered class of problems, the multibumps-solution phenomenon appears on the annulus as well as on the ball. The second part of the thesis is devoted to partial and ordinary differential equations with singularities. Using concentration-compactness tools, we show that a rather large class of functionals is lower semi-continuous, leading to the existence of a ground state solution. We also focus on the unicity of solutions for such a class of problems.

The thesis provides answers, in one case partial and in the other final, to two conjectures in the area of weighted inequalities for Singular Integral Operators. We study the mapping properties of these operators in weighted Lebesgue spaces with weight w. The novelty of this thesis resides in proving sharp dependence of the operator norm on the Muckenhoupt constant associated to the weigth w for a rich class of Singular Integral operators. The thesis also addresses the end point case p=1, providing counterexamples for the dyadic and continuous settings.