Many communities around the country had already been dealing with the problems of increasing and concentrated foreclosures for several years. Thus, the evidence of the social costs of foreclosures will guide policy makers in deciding what policies should be put in many communities that foreclosures have plagued. The objective of this research is to quantify the price-depressing foreclosure effects on existing home sale prices as one of the major social costs for communities. The first methodological goal is to simultaneously quantify the magnitude of the direct and the spillover effects of foreclosures on existing home prices. The second methodological goal is to provide usefulness concerning spatial econometric models in measuring the impact of foreclosures on housing prices. This study was estimated with traditional hedonic and spatial hedonic models specified during two different housing cycles in Phoenix, Arizona, during a strong housing market when prices were up (2005) and a down housing market with falling prices (2008). It has been shown that foreclosures have negative effects on existing home prices in the neighborhood, depending on housing types and cycles. However, the OLS models do not correct for spatial autocorrelation problems and endogeneity that exist in a cross section of house prices and would overestimate absolute values of the coefficients. As alternatives, the maximum likelihood spatial lag or error model controls for spatial autocorrelation but still causes computation obstacles for large data sets and problems of heteroskedasticity in error terms. Thus, the preferred specification is a generalized method of moments (GMM) approach which requires weaker assumptions than the maximum likelihood application and has flexible form to large datasets. As a joint analysis, the most appropriate specification is the general spatial two-stage least-squares (GMM_2SLS) method with HAC (the spatial heteroskedasticity and autocorrelation consistent) variance estimator. These findings provide further evidence that OLS estimates of a coefficient on a foreclosure indicator tend to overstate the direct or indirect foreclosure discount, ignoring spatial effects such as spatial dependence and endogeneity. With regard to the spillover effect of nearby foreclosures on home prices, both foreclosures of single family homes and condos are statistically significant and negatively impact each type of home sale prices. However, the cumulative effects of neighborhood foreclosures are much greater with nonlinear effects in a housing bust year than a housing boom year. Therefore, this study on price-depressing effects of foreclosures emphasizes the importance of the pre-foreclosure step as the beginning of following foreclosure processes, depending on housing types and housing market cycles.

This dissertation analyzes the optimal mix of direct and indirect taxes in an economy with multiple tax collecting authorities when both the taxes are subject to evasion and to what extent the tax compliance behavior of individuals in the United States are persistent and spatially dependent. Essay I derives and provides an intuitive interpretation of: (i) impact of the changes in the government instruments on tax evasion by firms, the expected prices they charge, and the expected tax rates they face; (ii) a generalized version of Ramsey rule for optimal commodity taxation which accounts for income tax evasion from either or both the tax authorities; (iii) generalized formulae for the optimal income tax rate for each of the tax authorities; and (iv) the tradeoff between optimal tax rates and audit probabilities for each of the tax authorities. It also re-examines controversies surrounding the uniform income taxes and the differentiated commodity taxes, and investigates how income tax evasion affects the progressivity of the income tax rates. It concludes that whether or not tax evasion calls for reductions in the optimal income tax rates hinges on how tax evasion and the associated concealment costs vary across individual taxpayers. Essay II introduces the twin issues of spatiality and persistence in the individual income tax evasion. While the issue of persistence arises through accumulated learning over time, spatiality arises for several reasons. Some these include the exchange of information between taxpayers; the social norm of tax compliance: an individual would comply if everybody in the society complies and vice versa; individuals faced with dynamic stochastic decision problems that pose immense computational challenges may simply look to others to infer satisfactory policies and interpersonal dependence works through learning by imitating rather than learning by doing. State-level annual per return evasion of individual income tax and related data were used to examine the above hypotheses and found supports for both of them in the individual income tax evasion in the United States.

Dub reggae is widely regarded as an early form of the remix. Dub artists modify previously recorded reggae songs by manipulating a song's individual tracks with a mixing board and layering them in aural effects such as reverb and echo. These effects are fundamentally spatial in quality, giving the listener an impression of vast open space. This paper is an analysis of the techniques utilized in dub's construction of sonic space as well as an investigation of the cultural meaning of those spaces. My analysis utilizes Josh Kun's theories about "audiotopias" (temporary aural spaces created through music) in order to study how sonic spaces create "new maps" that allow an individual to analyze their current social predicament. These "new maps," therefore, engender a "remapping" of reality, a reconstitutive process that parallels dub's emphasis on modification and alteration. This paper also argues that dub's audiotopias are implicitly natural, although they are constructed through modern recording technologies such as the echo chamber and the reverb unit. A final chapter applies these analytical techniques to one of dub's most popular musical offspring, hip hop.

This thesis examines the role of human capital in the growth and convergence of the Iberian countries. Using a newly computed series for human capital at the NUTS III level for the Portuguese regions, the comparison between Portugal and Spain suggests a positive role for human capital proxied by the average years of schooling in both Iberian countries regional growth, which supports the hypothesis that higher levels of education improved the regions‟ ability to adopt new technology; although the levels of education indicate that secondary schooling is important for technology adoption in Portugal, but not in Spain, and its effect is higher than that of tertiary education. Using Exploratory Spatial Data Analysis (ESDA), two convergence clubs are identified within the Iberia Peninsula (Core and Periphery), but convergence occurs mainly in the Periphery group and education plays a positive and significant role only in the Core club.

The current rice varieties grown by Australian farmers are susceptible to low temperature events particularly during the reproductive stage of plant development. The best management practices of sowing within the recommended time period and maintaining deep water (20–25 cm) through the microspore development stage only offer limited protection. There is a need to develop more cold tolerant varieties and to do so requires the development of low-temperature screening capacity for the NSW rice breeding program. This study looked at the requirements of adapting a controlled-temperature glasshouse facility to enable screening for tolerance to low temperatures during the reproductive stage of rice development. The investigations were grouped into two areas; 1) the physical aspects of the low temperature facility including the location of plants within the facility and within the tubs used to grow the plants and whether these can influence the reliability of the screening and 2) the biological effects of nitrogen (N) concentration in the plant at panicle initiation (PI) and plant susceptibility to low temperatures, and whether growth stage of the plant relative to PI at the start of low temperature treatment influenced floret sterility. A series of nine experiments were conducted at the Deniliquin Agricultural Research and Advisory Station glasshouse facility using up to five rice varieties selected for their divergence in low-temperature tolerance. One other experiment was conducted in a different facility. The modified glasshouse facility in Deniliquin was effective in providing the targeted screening environment of 27°C day and 13°C night temperature regime. There was however a smaller than expected effect of the low temperature exposure in some of the experiments with sterility following low temperature ranging from 9.9% to 27.7%. There was also a higher than expected level of sterility in the controls (i.e. not exposed to low temperature) with sterility levels up to 58% recorded in one experiment. The causes of these overall effects are not known. Notwithstanding these overall effects there were a number of findings that are important for developing a reliable screening facility. The spatial arrangement of the plants within the low temperature facility effected the level of sterility highlighting the need for experimental design to consider spatial variation. The existence of edge effects was identified within the tubs used to maintain permanent water on the potted plants whereby the outer plants in the tubs were less damaged by the low-temperature treatment. The overall N level in the leaf tissue was low even at the equivalent rate of 250 kg N ha-1 and there was only a very modest and inconsistent response in N concentration at PI to N application rates ranging from 0 to 250 kg ha-1. However, the method of growing the plants in pots and of nitrogen fertiliser application did not alter the N concentration. The concentration was the same when N was added either, on the same day as permanent water application, or three days prior to permanent water application. Also restricting the direction of water movement through the pots and therefore the soil within the pots did not alter the amount of N in the plants at PI. The low plant N concentrations were consistent across two glasshouses in which soil from the same source was used suggesting a soil limitation. A soil test identified that the soil phosphorus (P) was at a level at which plants have responded to P application under field conditions, and the loamy texture of the soil had an associated low cation exchange capacity in comparison to medium to heavy clay soil types commonly associated with rice growing. These factors may have reduced the N retention and uptake and, in part, explain the low injury from the low temperature exposures. In the variety Millin, there was no significant effect of timing of the exposure on sterility until it commenced 12 to 15 days after PI. This is a significant finding for a breeding program that must expose lines of unknown phenological development. It means that even though there are small differences in the rates of development, there is no large effect of this on sterility. However, this response was not seen in the other varieties tested and thus requires further validation. It was difficult to induce repeatable levels of floret sterility in this series of experiments most likely due to the low N concentrations in part due to the properties of the soil used to grow the plants. This highlights the importance of standardising all cultural aspects in order to provide uniform and repeatable screening information. The spatial effects highlight importance of experimental design for effective exposure to low temperature treatments, incorporation of the capacity for spatial analysis in the statistical design, the use of standard variety checks for floret sterility after low temperature treatment, and the determination of N concentration in plant tissue prior to exposure.

This thesis presents an examination of the importance of Small and Medium Enterprises (SMEs) for economic growth and examines how sensitive employment in SMEs is to business cycle fluctuations in Brazil. The thesis uses different empirical techniques to investigate the role of SMEs in the Brazilian regional economic growth, using a panel dataset from 1980 to 2004 for 508 Brazilian micro-regions. It first uses standard panel data estimators (OLS, LSDV, system and first differenced GMM) to analyse the (augmented) Solow growth model encompassing the importance of the relative size of the SME sector measured by the share of the SME employment in total formal employment and the level of human capital in SMEs measured by the average years of schooling of SME employees. The results show that the size of the SME sector is not significantly important for regional economic growth, but that human capital embodied in SMEs is more important in this process.

Les réacteurs nucléaires à neutrons rapides sont une solution à long terme pour la production d’énergie car ils valorisent le Plutonium et peuvent utiliser tout le stock de d’Uranium appauvri. Les contraintes actuelles en termes de sûreté requièrent néanmoins des innovations pour favoriser un comportement naturel du cœur lors de transitoires incidentels en augmentant le temps de grâce et la marge à la fusion. Les innovations apportées aux cœurs (hauteur réduite, cœur hétérogène, puissance volumique limitée) induisent un accroissement de la taille des réacteurs. Cette évolution a des conséquences de sûreté essentiellement positives comme la réduction de l’effet de vidange mais d’autres comme la déformation de la nappe de puissance méritent attention. Cette thèse a permis de mieux appréhender ces spécificités au travers du calcul et de l’analyse des harmoniques du flux puis des matrices de fission. Ces études, en soutien au cœur d’ASTRID, ont permis de conforter les options de conception. / The need for energy is a matter of growing concern in the world today, in relation to global climate change. Nuclear energy is of interest because it does not produce greenhouse gases, and it is able to generate a substantial amount of energy at a given time. However, it needs fissile material to operate. Fuel economy is then a sine qua none condition for the development of this energy. Sodium Fast Reactors are a solution for the future of nuclear energy. These reactors are indeed able to use much less Uranium for the same amount of energy released. However, the safety constraints in accordance with todays standards (“forgiving behavior”) require new core designs, which are highly heterogeneous axially and rather flat. Finally, this evolution in reactor design (reduced power density and limited axial height) implies a significant increase in the reactor diameter. It has consequences from both an economic (Pu inventory, vessel size) and operational (power shape stabilization during irradiation) point of view. The understanding of this phenomena is the topic of this PhD.

nÃo hà / This paper aims to estimate a residential water demand function for the city of Fortaleza (CearÃ), considering the potential impact of the spatial effects on water consumption. The analysis is developed from the investigation of presence of spatial autocorrelation in residential water consumption. For this, the tools of exploratory spatial data analysis (ESDA) were utilized. Subsequently, specific tests are performed to determine the sources of spatial autocorrelation, i.e., if the autocorrelation is caused by the spatial distribution of water consumption or by effects not modeled. Identified the sources of spatial autocorrelation, four water demand functions were estimated, which had as explanatory variables the average price, the difference, income, number of residents and the number of rooms, under different specifications. At first, we estimated a model without special effects; in the second, we estimated the specification of the spatial error model (SEM), which incorporates the spatial autocorrelation in the form of autocorrelation in the error terms; in the third, we estimated the spatial autoregressive model (SAR), where the spatial autocorrelation is incorporated through the spatial lag of the dependent variable; and finally, we estimated the spatial model autoregressive moving average (SARMA), which is the union of the two previous models. The results show that spatial autocorrelation exists in two forms (error and lag), indicating that the SARMA model is the most indicated to model the residential water demand in the city of Fortaleza, in contrast to suggested by Chang et al.(2010), House-Peters et al. (2010), Franczyk e Chang (2008), Ramachandran e Johnston (2011), which used the SEM model. It is concluded that it is important to consider the possibility of spatial effects in the estimation of a residential water demand function, once that not incorporate spatial effects in the analysis underestimate the effect of the variables average price and number of residents on residential water demand, while overestimating the effect of the variables income and number of rooms. / Esta dissertaÃÃo tem como objetivo estimar uma funÃÃo de demanda residencial por Ãgua para a cidade de Fortaleza (CearÃ), considerando o provÃvel impacto do efeito espacial no consumo de Ãgua. A anÃlise se desenvolve a partir da investigaÃÃo a respeito da presenÃa de autocorrelaÃÃo espacial no consumo residencial de Ãgua. Para tal, foram utilizadas as tÃcnicas de anÃlise exploratÃria espacial de dados (ESDA). Posteriormente, sÃo realizados testes especÃficos para determinar as fontes da autocorrelaÃÃo espacial, ou seja, identificar se a autocorrelaÃÃo à causada pela distribuiÃÃo espacial do consumo de Ãgua ou pelos efeitos nÃo modelados. Identificadas as fontes de autocorrelaÃÃo espacial, foram estimadas quatro funÃÃes de demanda de Ãgua, que tinham como variÃveis explicativas o preÃo mÃdio, a diferenÃa, a renda, o nÃmero de residentes e o nÃmero de cÃmodos, sob diferentes especificaÃÃes. Na primeira, utilizou-se um modelo sem efeitos espaciais; na segunda, utilizou-se a especificaÃÃo do modelo de erros espaciais (SEM), que incorpora a autocorrelaÃÃo espacial na forma de autocorrelaÃÃo nos termos de erro; na terceira, utilizou-se o modelo espacial autorregressivo (SAR), onde a autocorrelaÃÃo espacial à incorporada atravÃs da defasagem espacial da variÃvel dependente; e por Ãltimo, utilizou-se o modelo espacial autorregressivo de mÃdias mÃveis (SARMA), que à a uniÃo dos dois modelos anteriores. Os resultados mostram que existe autocorrelaÃÃo espacial nas duas formas (erro e defasagem), indicando que o modelo SARMA à o mais adequado para modelar a demanda residencial por Ãgua na cidade de Fortaleza, ao contrÃrio do proposto por Chang et al. (2010), House-Peters et al. (2010), Franczyk e Chang (2008), Ramachandran e Johnston (2011), que utilizaram o modelo SEM. Conclui-se, portanto, que à importante levar em consideraÃÃo a possibilidade de efeitos espaciais na estimaÃÃo de uma funÃÃo de demanda residencial por Ãgua, na medida que a nÃo incorporaÃÃo dos efeitos espaciais subestima o efeito das variÃveis preÃo mÃdio e nÃmero de residentes sobre a quantidade consumida de Ãgua, enquanto superestima o efeito das variÃveis renda e nÃmero de cÃmodos.

Dans cette thèse, nous analysons les performances des réseaux de communication à l'aide d’approches issues de la théorie des jeux. Cette thèse se présente en deux parties. La première partie étudie la performance des réseaux ad-hoc, cellulaires et de transport en tenant compte d’effets spatiaux. La deuxième partie adresse des problématiques économiques dans les réseaux de communications, liées à la réglementation de la «neutralité du réseau». Ici, nous étudions la concurrence des prix ainsi que des mécanismes de partage des revenus entre fournisseurs de services réseau.Dans la première partie, nous utilisons des modèles de jeu d’accès canal (MAC) et jeu de brouillage pour étudier les performances d'un réseau mobile ad hoc (MANET), et de jeux de routage afin d'étudier les performances d'un réseau de transport. Dans les réseaux cellulaires, nous étudions l'effet de la réduction de la densité spatiale des stations de base sur la quantité de rayonnement au corps humain (réseau vert).Les considérations géométriques jouent un rôle important dans les performances des réseaux sans fils. Par exemple, la position des nœuds affecte le niveau des interférences. Dans les MANETS, la mobilité des nœuds conduit à une observation différente du niveau d’interférences provenant de leurs voisins, et aussi due à la nature décentralisée du réseau, les utilisateurs peuvent adopter un comportement égoïste dans le partage des ressources. Afin de modéliser les propriétés géométriques du réseau ainsi que le comportement égoïste des utilisateurs, nous utilisons la géométrie stochastique et la théorie des jeux. Notre travail a développé un mécanisme de tarification et a montré qu’en définissant un prix approprié, tous les utilisateurs pouvaient être amenés à recevoir une part équitable des ressources conduisant à un optimal global des performances du réseau. Nous considérons aussi une configuration antagoniste où certain nœuds tendent à dégrader les performances du réseau en brouillant les communications des autres nœuds du réseau. Dans la deuxième partie de la thèse, nous étudions des aspects économiques dans les réseaux communication. Les représentants de plusieurs fournisseurs d'accès Internet (ISP) ont exprimé leur souhait de voir un changement important dans les politiques de tarification de l'Internet. En particulier, ils aimeraient voir les fournisseurs de contenu (CP) payer pour l'utilisation du réseau, compte tenu de la grande quantité de ressources qu'ils utilisent. Ce qui serait une violation flagrante du «principe de neutralité des réseaux» qui a caractérisé le développement de l'Internet filaire. La thèse a étudiée la possibilité de l’introduction d’un régulateur facilitant les interactions monétaires entre les ISP et les CP dans un régime non neutre. En utilisant des outils issus de la théorie des jeux et de la conception de mécanismes, nous avons développé deux mécanismes de négociation décidant des paiements entre les ISPs et CPs. Nous montrons que si les joueurs négocient avant de fixer les prix d’accès des utilisateurs finaux, ceci conduit à un équilibre favorable où tous les joueurs ressortent gagnant. Nous considérons également le cas où certains CPs établissent des contrats d’exclusivités avec les ISP afin d’obtenir des traitements préférentiels et en étudions l’impact sur les fournisseurs d’accès et les utilisateurs finaux. Avec la croissance du commerce de l’internet, la régulation des interactions monétaires entre différents fournisseurs de services est inévitable. Notre travail fournit des lignes directrices importantes sur la façon dont l'Internet doit être réglementé de telle sorte que les intérêts des utilisateurs finaux sont protégés / In this thesis we analyze the performance of communication networks using game theoretic approaches. The thesis is in two parts. The first part studies the performance of Ad hoc, cellular and transportation networks taking into consideration spatial effects. The second part studies economic issues in the communication networks related to the `net neutrality' regulations. Here we study price competition and revenue sharing mechanisms between the network service providers.In the first part, we use Medium Access Control (MAC) game and Jamming game models to study the performance of a Mobile Ad hoc NETwork (MANET), and routing games to study the performance of a transportation network. In the cellular networks, we study the effect of reducing the spatial density of base stations on the amount of radiation to human body (green networking). Geometric aspects play an important role in the performance of wireless networks. For example, node locations affect the amount of interference. In MANETs, the mobility results in users experiencing different amount of interference from their neighbors, and also due to decentralized nature of the network the users can be selfish in sharing the resources. To model the geometrical properties of the network and selfish behavior of the users we used stochastic geometry and game theory. Our work developed a pricing mechanism and showed that with an `appropriate' price all the users can be made to get a fair share of the resources resulting in global optimal network performance. We also considered an adversarial setting where some of the nodes aim to degrade the performance of the network by jamming other nodes’ transmissions.In the second part of the thesis, we study economics aspects in communication networks. Representatives of several Internet access providers (ISPs) have expressed their wish to see a substantial change in the Internet pricing policies. In particular, they would like to see content providers (CPs) pay for use of the network, given the large amount of resources they use. This would be in clear violation of the ``net neutrality'' principle that had characterized the development of the wireline Internet. The thesis explored possibility of a regulator facilitating monetary interactions between the ISPs and CPs in a nonneutral regime. Using tools from game theory and mechanism design we developed two bargaining mechanisms to decide payments between the ISPs and CPs. We showed that if the players bargain before they set the access prices for end users, it results in a favorable equilibrium where every player benefits. We also considered the case where some of CPs make exclusive contracts with the ISPs to get preferential treatment and studied its impact on both the service providers and the end users.As the Internet commerce grows, regulation of the monetary interaction between various service providers is unavoidable. Our work provides important policy guidelines on how the Internet should be regulated such that the end users' interests are protected

abstract: A major challenge in health-related policy and program evaluation research is attributing underlying causal relationships where complicated processes may exist in natural or quasi-experimental settings. Spatial interaction and heterogeneity between units at individual or group levels can violate both components of the Stable-Unit-Treatment-Value-Assumption (SUTVA) that are core to the counterfactual framework, making treatment effects difficult to assess. New approaches are needed in health studies to develop spatially dynamic causal modeling methods to both derive insights from data that are sensitive to spatial differences and dependencies, and also be able to rely on a more robust, dynamic technical infrastructure needed for decision-making. To address this gap with a focus on causal applications theoretically, methodologically and technologically, I (1) develop a theoretical spatial framework (within single-level panel econometric methodology) that extends existing theories and methods of causal inference, which tend to ignore spatial dynamics; (2) demonstrate how this spatial framework can be applied in empirical research; and (3) implement a new spatial infrastructure framework that integrates and manages the required data for health systems evaluation. The new spatially explicit counterfactual framework considers how spatial effects impact treatment choice, treatment variation, and treatment effects. To illustrate this new methodological framework, I first replicate a classic quasi-experimental study that evaluates the effect of drinking age policy on mortality in the United States from 1970 to 1984, and further extend it with a spatial perspective. In another example, I evaluate food access dynamics in Chicago from 2007 to 2014 by implementing advanced spatial analytics that better account for the complex patterns of food access, and quasi-experimental research design to distill the impact of the Great Recession on the foodscape. Inference interpretation is sensitive to both research design framing and underlying processes that drive geographically distributed relationships. Finally, I advance a new Spatial Data Science Infrastructure to integrate and manage data in dynamic, open environments for public health systems research and decision- making. I demonstrate an infrastructure prototype in a final case study, developed in collaboration with health department officials and community organizations. / Dissertation/Thesis / Doctoral Dissertation Geography 2017