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Under approval voting, every voter may vote for any number of canditates. To model approval voting, we let a political spectrum be the set of all possible political positions, and let each voter have a subset of the spectrum that they approve, called an approval region. The fraction of all voters who approve the most popular position is the agreement proportion for the society. We consider voting in societies whose political spectrum is modeled by $d$-dimensional space ($\mathbb{R}^d$) with approval regions defined by axis-parallel boxes. For such societies, we first consider a Tur&#aacute;n-type problem, attempting to find the maximum agreement between pairs of voters for a society with a given level of overall agreement. We prove a lower bound on this maximum agreement and find in the literature a proof that the lower bound is optimal. By this result we find that for sufficiently large $n$, any $n$-voter box society in $\mathbb{R}^d$ where at least $\alpha\binom{n}{2}$ pairs of voters agree on some position must have a position contained in $\beta n$ approval regions, where $\alpha = 1-(1-\beta)^2/d$. We also consider an extension of this problem involving projections of approval regions to axes. Finally we consider the question of $(k,m)$-agreeable box societies, where a society is said to be $(k, m)$-agreeable if among every $m$ voters, some $k$ approve a common position. In the $m = 2k - 1$ case, we use methods from graph theory to prove that the agreement proportion is at least $(2d)^{-1}$ for any integer $k \ge 2.$

Onchocerciasis is a blindness-causing disease caused by a nematode called Onchocerca volvulus that is transmitted by Simulium blackflies. The disease is a major epidemiological problem among rural communities living in close proximity to rivers in some population in Sub-Saharan Africa. Recent studies identified Ghana to be a treat of recrudescence of onchocerciasis in neighboring countries. This thesis applies spatial models, predicts, and assesses population at risk of onchocerciasis in Ghana. It also evaluates the disease endemicity in Burundi in order to test the models applied in Ghana. Onchocerciasis prevalence data spanning a period of 2004 (Ghana) and 1985-1992 (Burundi) were integrated together with biophysical variables in a GIS. Next, modeling of the spatial risk of onchocerciasis was based on the principal component analysis (PCA) regression models. The final predictive spatial models represent the risk of the disease. The spatial models showed potential biogeographic zones and epidemiological patterns of onchocerciasis in relation to village settlements that are at risk. Also, the risk of onchocerciasis increased with the proximity to the rivers. The estimated population at risk in Ghana in 2010 was 5,211,808 people (or 21.36% of the total population) and 235,032 people in Burundi (or 2.8% of the total population). Findings from this study can help in the effective design of preventive control measures of the risk of recrudescence of the disease and safeguard the achievements of the OCP and APOC programs.

O Brasil é um dos principais países agrícolas do mundo e um dos únicos com possibilidade de expansão expressiva de sua área em produção e da produtividade. Entretanto, a contínua necessidade de incrementos da produção leva à ocupação de áreas menos aptas para a agricultura, com potencial aumento da degradação do solo pela erosão. Neste contexto, a conservação do solo é uma variável importante e está, em parte, relacionada ao conceito de aptidão agrícola. Modelos de predição da erosão são ferramentas importantes no planejamento agrícola, entretanto, em muitas situações carecem valores de referência de tolerância. Como alternativa aos valores de referência o objetivo deste trabalho foi desenvolver espacialmente o conceito de tempo de vida da agricultura (TVA) para o território brasileiro, além de aplicá-lo em situações possíveis para o planejamento do uso da terra. A metodologia partiu da adequação de base de dados de acesso aberto dos parâmetros da equação de TVA. Para tanto, foram executadas regressões, equações de pedotransferência e cálculos com a Equação Universal de Perda de Solo (USLE). A aplicação do conceito TVA para i) bacias hidrográficas, por meio da mediana dos valores TVA; ii) biomas, o Brasil é signatário do acordo com o Convenção sobre Diversidade Biológica da Organização das Nações Unidas (CDB), considerando a conservação do solo uma variável na localização de novas Unidades de Conservação (UC), buscou-se identificar as áreas de menor tempo de vida potencial da agricultura (pTVA) como alvos prioritários para a criação de novas UC; iii) expansão da agricultura, buscou identificar as características das áreas de fronteira agrícola e de não fronteira em relação ao seu pTVA. Os principais resultados foram: i) é possível estimar parâmetros do solo por meio de regressões, captando entre 36% (argila) a 60% (matéria orgânica) da variância total; ii) a combinação de uso agrícola intenso e solos pouco profundos resultam em tempo de vida da agricultura menores, notadamente nos estados de Santa Catarina, Rio de Janeiro, Paraná e Minas Gerais e no bioma Mata Atlântica.; iii) o bioma Amazônia e os estados do Mato Grosso do Sul e Bahia mostraram-se as regiões de maior tempo de vida; iv) na análise por subbacias, a que se encontra em melhor condição é a bacia Amazônica; v) a determinação de áreas prioritárias para a conservação foi possível e resultou em seis mapas com áreas mais sensíveis, geralmente associações de relevo ondulado e solos rasos; vi) a análise da relação com a agricultura mostrou que em áreas consolidadas não houve diferença entre os valores totais e aquele das áreas ocupadas com agricultura. Já em áreas de expansão houve tendência de escolha de áreas com tempo de vida da agricultura potencial mais alto, ou seja, com menor risco de erosão. Este fenômeno é esperado pela teoria de ajuste territorial da agricultura (agricultural adjustment). / Brazil is one of the main agricultural countries in the world and one of the only ones with the significant possibility expansion its agricultural area and productivity. The continuing need for the production increments leads to the occupation of less suitable areas for agriculture, with potentially increased soil degradation by erosion. In this context, soil conservation is an important variable and is partly related to the concept of land suitability. Erosion prediction models are important tools in agricultural planning, however, in many situations require reference tolerance values. As an alternative to reference values the aim of this study was to develop spatially the concept of Agricultural Lifetime (TVA) for the Brazilian territory, and apply it to situations possible for planning land use. The methodology was based on the adaptation of the public databases of the parameters of the TVA equation. Thus, we executed regressions, pedotransfer equations and calculations with Equation Universal Soil Loss (USLE). Applying the TVA concept to i) watershed analysis, through the median TVA values, ii) biomes analysis, Brazil is a signatory of the Convention on Biological Diversity of the United Nations (CDB) agreement, the given to conservation of soil a variable in locating new Conservation Units (UC), we sought to identify areas of lower potential agricultural lifetime (pTVA) as priority targets for creating new UC´s iii) expansion of agriculture analysis, was to identify the characteristics of agricultural frontier areas and not frontier in relation of pTVA. The main results were: i) it is possible to estimate soil parameters through regression, capturing between 36% (clay) and 60% (organic matter) of the total variance; ii) the combination of intense agricultural land use and shallow deep soils result in TVA lower, especially in the states of Minas Gerais, Santa Catarina, Rio de Janeiro e Paraná and in the Mata Atlântica biome; iii) the Amazon region and Bahia and Mato Grosso do Sul states showed up places with longer life; iv) the analysis by subbasins, which are in the best conditions are the basins of the eastern Atlantic and Amazon; v) the determination of priority areas for conservation was possible and resulted in six maps with more sensitive areas, generally associations wavy relief and shallow soils deep; vi) the analysis of the relation with agriculture in consolidated areas showed that there was no difference between the totals and that the areas occupied by agriculture, already in frontier areas tended to choose pTVA areas higher, with less risk of erosion. This phenomenon is expected by the theory of agricultural adjustment.

Propõe-se um método de construção arquitetural de espaços virtuais, baseado na sobreposição de diversos modos de pensar o espaço e no uso de estruturas da mnemotécnica. Para essa tarefa, faz-se, inicialmente, uma análise crítica do estado da arte em dois campos disciplinares recorrentemente envolvidos na construção de tais ambientes: Interface Usuário-Computador e Realidade Virtual. Em seguida apresenta-se a maneira de se sobrepor diversos modos de pensar o espaço em Arquitetura, a qual constitui o terceiro campo disciplinar desse estudo, explicitado através da introdução e da análise de diferentes exemplos de concepções arquitetônicas pertencentes ao âmbito virtual. Definido como pertencente à mente, o espaço virtual é concebido através de métodos arquitetônicos, acrescidos do uso da Mnemônica, que é a arte e a técnica de se desenvolver e fortalecer a memória. O processo de memorização torna-se central no processo de construção do contexto virtual. Introduzido através de exemplos na história e de recentes aplicações artísticas em realidade virtual, a tese propõe a inclusão da mnemotécnica para a estruturação espacial arquitetônica no virtual / A method is proposed for the architectural construction of virtual spaces based on the overlaying of diverse ways of thinking about space and by using structures of mnemotechniques. In order to achieve this task, a critical review is first carried out of two disciplines which are regularly involved in the construction of this kind of spatiality: Human-Computer Interface, and Virtual Reality. Architecture, as a third and central discipline, presents its method of overlaying diverse ways of thinking space, made explicit through the introduction and analysis of different examples of architectural construction in the virtual realm. Defined as belonging to the mind, the virtual space is conceived through architectural methods by adding the use of Mnemonics, which is the art and technique of developing and making stronger the memory. The memorization process itself becomes central in the process of constructing the virtual context. Introducing examples in history and recent art applications in virtual reality, the thesis proposes the introduction of mnemotechniques for the architectural spatial structuring of the virtual

O Brasil é um dos principais países agrícolas do mundo e um dos únicos com possibilidade de expansão expressiva de sua área em produção e da produtividade. Entretanto, a contínua necessidade de incrementos da produção leva à ocupação de áreas menos aptas para a agricultura, com potencial aumento da degradação do solo pela erosão. Neste contexto, a conservação do solo é uma variável importante e está, em parte, relacionada ao conceito de aptidão agrícola. Modelos de predição da erosão são ferramentas importantes no planejamento agrícola, entretanto, em muitas situações carecem valores de referência de tolerância. Como alternativa aos valores de referência o objetivo deste trabalho foi desenvolver espacialmente o conceito de tempo de vida da agricultura (TVA) para o território brasileiro, além de aplicá-lo em situações possíveis para o planejamento do uso da terra. A metodologia partiu da adequação de base de dados de acesso aberto dos parâmetros da equação de TVA. Para tanto, foram executadas regressões, equações de pedotransferência e cálculos com a Equação Universal de Perda de Solo (USLE). A aplicação do conceito TVA para i) bacias hidrográficas, por meio da mediana dos valores TVA; ii) biomas, o Brasil é signatário do acordo com o Convenção sobre Diversidade Biológica da Organização das Nações Unidas (CDB), considerando a conservação do solo uma variável na localização de novas Unidades de Conservação (UC), buscou-se identificar as áreas de menor tempo de vida potencial da agricultura (pTVA) como alvos prioritários para a criação de novas UC; iii) expansão da agricultura, buscou identificar as características das áreas de fronteira agrícola e de não fronteira em relação ao seu pTVA. Os principais resultados foram: i) é possível estimar parâmetros do solo por meio de regressões, captando entre 36% (argila) a 60% (matéria orgânica) da variância total; ii) a combinação de uso agrícola intenso e solos pouco profundos resultam em tempo de vida da agricultura menores, notadamente nos estados de Santa Catarina, Rio de Janeiro, Paraná e Minas Gerais e no bioma Mata Atlântica.; iii) o bioma Amazônia e os estados do Mato Grosso do Sul e Bahia mostraram-se as regiões de maior tempo de vida; iv) na análise por subbacias, a que se encontra em melhor condição é a bacia Amazônica; v) a determinação de áreas prioritárias para a conservação foi possível e resultou em seis mapas com áreas mais sensíveis, geralmente associações de relevo ondulado e solos rasos; vi) a análise da relação com a agricultura mostrou que em áreas consolidadas não houve diferença entre os valores totais e aquele das áreas ocupadas com agricultura. Já em áreas de expansão houve tendência de escolha de áreas com tempo de vida da agricultura potencial mais alto, ou seja, com menor risco de erosão. Este fenômeno é esperado pela teoria de ajuste territorial da agricultura (agricultural adjustment). / Brazil is one of the main agricultural countries in the world and one of the only ones with the significant possibility expansion its agricultural area and productivity. The continuing need for the production increments leads to the occupation of less suitable areas for agriculture, with potentially increased soil degradation by erosion. In this context, soil conservation is an important variable and is partly related to the concept of land suitability. Erosion prediction models are important tools in agricultural planning, however, in many situations require reference tolerance values. As an alternative to reference values the aim of this study was to develop spatially the concept of Agricultural Lifetime (TVA) for the Brazilian territory, and apply it to situations possible for planning land use. The methodology was based on the adaptation of the public databases of the parameters of the TVA equation. Thus, we executed regressions, pedotransfer equations and calculations with Equation Universal Soil Loss (USLE). Applying the TVA concept to i) watershed analysis, through the median TVA values, ii) biomes analysis, Brazil is a signatory of the Convention on Biological Diversity of the United Nations (CDB) agreement, the given to conservation of soil a variable in locating new Conservation Units (UC), we sought to identify areas of lower potential agricultural lifetime (pTVA) as priority targets for creating new UC´s iii) expansion of agriculture analysis, was to identify the characteristics of agricultural frontier areas and not frontier in relation of pTVA. The main results were: i) it is possible to estimate soil parameters through regression, capturing between 36% (clay) and 60% (organic matter) of the total variance; ii) the combination of intense agricultural land use and shallow deep soils result in TVA lower, especially in the states of Minas Gerais, Santa Catarina, Rio de Janeiro e Paraná and in the Mata Atlântica biome; iii) the Amazon region and Bahia and Mato Grosso do Sul states showed up places with longer life; iv) the analysis by subbasins, which are in the best conditions are the basins of the eastern Atlantic and Amazon; v) the determination of priority areas for conservation was possible and resulted in six maps with more sensitive areas, generally associations wavy relief and shallow soils deep; vi) the analysis of the relation with agriculture in consolidated areas showed that there was no difference between the totals and that the areas occupied by agriculture, already in frontier areas tended to choose pTVA areas higher, with less risk of erosion. This phenomenon is expected by the theory of agricultural adjustment.

Individual-level models are a class of complex statistical models, often fitted within a Bayesian Markov chain Monte Carlo framework, that have been effectively used to model the spread of infectious diseases. The ability of these models to incorporate individual-level covariate information allows them to be highly flexible, and to account for such characteristics as population heterogeneity. However, these models can be subject to inherent uncertainties often found in infectious disease data. As well, their complex nature can lead to a significant computational expense when fitting these models to epidemic data, particularly for large populations. An individual-level model that incorporates a latent grouping structure into the modeling procedure, based on some heterogeneous population characteristics, is investigated. The dependence of this latent conditional individual-level model on a discrete latent grouping variable alleviates the need for explicit, although possibly unreliable, covariate information. A simulation study is used to assess the posterior predictive ability of this model, in comparison to individual-level models that utilize the full covariate information, or that assume population homogeneity. These models are also applied to data from the 2001 UK foot-and-mouth disease epidemic. When attempting to compare complex models fitted within the Bayesian framework, the identification of appropriate model selection tools would be beneficial. The use of deviance information criterion (DIC) as model comparison tool, particularly for the latent conditional individual-level models, is investigated. A simulation study is used to compare five variants of the DIC, and the ability of each DIC variant to select the true model is determined. Finally, an investigation into methods to reduce the computational burden associated with individual-level models is carried out, based on an individual-level model that also incorporates population heterogeneity through a discrete grouping variable. A simulation study is used to determine the effect of reducing the overall population size by aggregating the data into spatial clusters. Reparameterized individual-level models, accounting for the aggregation effect, are fitted to the aggregated data. The effect of data aggregation on the ability of two reparameterized individual-level models to identify a covariate effect, as well as on the computational expense of the model fitting procedure, is explored.

<p>Pro-urban bias in policy is often seen as a common phenomenon in the developing world. Empirical reality though is much more varied. Many governments actively support agricultural producers and rural citizens, even at early stages of development. In addition, the binary distinction between urban and rural bias in policy aggregates over important sub-national variation in the distributive impact of government policies. This dissertation extends the research frontier by analyzing the political roots underlying spatial bias in policy using new theoretical and empirical approaches. First, this dissertation develops a theory that identifies conditions under which politicians will institute pro-urban or pro-rural policies, by considering the threat of a rural insurgency. Second, I argue that elections in rural majority societies can empower citizens in the rural periphery. Competitive elections and high rural turnout induce governments to supply favorable policies to the rural sector as a whole and salient regions in particular. To test the effect of the threat of rural violence, I use new cross-national data on net taxation in the agricultural sector. Data on fiscal transfers and the sub-national effects of agricultural pricing policies in Indonesian districts provide additional evidence for the first hypothesis. To test the effect of elections on urban bias, I exploit a natural experiment from the Indonesian context. Last, I analyze the proliferation of districts in Indonesia from 2001 to 2009, with important implications for future fiscal transfers, and show the process is largely driven by local elite competition within and between districts.</p> / Dissertation

Propõe-se um método de construção arquitetural de espaços virtuais, baseado na sobreposição de diversos modos de pensar o espaço e no uso de estruturas da mnemotécnica. Para essa tarefa, faz-se, inicialmente, uma análise crítica do estado da arte em dois campos disciplinares recorrentemente envolvidos na construção de tais ambientes: Interface Usuário-Computador e Realidade Virtual. Em seguida apresenta-se a maneira de se sobrepor diversos modos de pensar o espaço em Arquitetura, a qual constitui o terceiro campo disciplinar desse estudo, explicitado através da introdução e da análise de diferentes exemplos de concepções arquitetônicas pertencentes ao âmbito virtual. Definido como pertencente à mente, o espaço virtual é concebido através de métodos arquitetônicos, acrescidos do uso da Mnemônica, que é a arte e a técnica de se desenvolver e fortalecer a memória. O processo de memorização torna-se central no processo de construção do contexto virtual. Introduzido através de exemplos na história e de recentes aplicações artísticas em realidade virtual, a tese propõe a inclusão da mnemotécnica para a estruturação espacial arquitetônica no virtual / A method is proposed for the architectural construction of virtual spaces based on the overlaying of diverse ways of thinking about space and by using structures of mnemotechniques. In order to achieve this task, a critical review is first carried out of two disciplines which are regularly involved in the construction of this kind of spatiality: Human-Computer Interface, and Virtual Reality. Architecture, as a third and central discipline, presents its method of overlaying diverse ways of thinking space, made explicit through the introduction and analysis of different examples of architectural construction in the virtual realm. Defined as belonging to the mind, the virtual space is conceived through architectural methods by adding the use of Mnemonics, which is the art and technique of developing and making stronger the memory. The memorization process itself becomes central in the process of constructing the virtual context. Introducing examples in history and recent art applications in virtual reality, the thesis proposes the introduction of mnemotechniques for the architectural spatial structuring of the virtual

Augmented reality is a field of technology in which the real world is overlaid with additional information from a computer generated display. Enhancements to augmented reality technology presently support limited mobility which is expected to increase in the future to provide much greater real world functionality. This work reports on a set of experiments that investigate performance in search and rescue navigating tasks using augmented reality. Augmentation consisted of a spatially and temporally registered map of a maze that was overlaid onto a real world maze. Participants were required to traverse the maze, answer spatially oriented questions in the maze, acquire a target object, and exit. Pre and post hoc questionnaires were administered. Time and accuracy data from one hundred twenty participants were collected across six treatments. The between subject treatments, which had an equal number of male and female participants, were a control condition with only a compass, a control condition with a paper map available prior to maze traversal and four experimental conditions consisting of combinations of egocentric and exocentric maps, and a continuously on and on demand map display. Data collected from each participant consisted of time to traverse the maze, percent of the maze covered, estimations of euclidian distance and direction, estimations of cardinal direction, and spatial recall. Data was also collected via pre and post hoc questionnaires. Results indicate that best performance with respect to time was in the control condition with a map. The small size of the maze could have facilitated this result through route memorization. Augmented reality can offer enhancement to performance as navigational tasks become more complex and saturate working memory. Augmented reality showed best performance in accuracy by facilitating participants' coverage of the maze. Exocentric maps generally exhibited better performance than egocentric maps. On demand displays also generally resulted in better performance than continuously on displays. Gender differences also were evident with males exhibiting better performance than females. Participants reporting an initial tendency to not rotate maps exhibited better performance than those reporting a tendency to rotate maps. Enhancements being made to augmented reality and related technologies will result in more features, improved form factor for users, and improved performance in the future. Guidelines provided in this work seek to ensure augmented reality systems continue to progress in enhancing performance