Whereas no prior contribution has focused on the case of a medium-sized city in a developing country, such as Mexico, to explore how urban structure and its expansion has affected the spatial distribution of employment, three distinct, but related papers were developed, which combine urban economics literature and spatial sciences techniques to fill this gap and provide new evidence. The first paper, entitled "Spatial Distribution of Employment in Hermosillo, 1999 and 2004" identifies where employment subcenters are. Testing the presence of spatial effects, it concludes that an incipient process of employment suburbanization has taken place; however, the city still exhibits a monocentric structure. As a complement, a second paper, "Employment Density in Hermosillo, 1999-2004: A Spatial Econometric Approach of Local Parameters" tests if the Central Business District (CBD), despite suburbanization, maintains the traditional attributes of attracting activities and influencing the organization of employment around it. The CBD is still attractive, but its influence varies across space and economic sector, conclusions that were masked by global estimations. Thirdly, a study was essential to uncover how important is the urban structure and the suburbanization of jobs in explaining the dispersion resulting of households and workplaces (commuting). The paper entitled "Commuting in a Developing City: The Case of Ciudad Obregon, Mexico" examines this issue. To take advantage of the commuting information available, the study area was switched. In general, the results are consistent with those suggested by urban economics; moreover, the inclusion of workplace characteristics was a novelty to model commuting behavior and proves that space matters. Additionally, new evidence was provided to the field of spatial science through the applications of techniques able to expose the spatial effects associated with the distribution of employment, more specifically, the Exploratory Spatial Data Analysis(ESDA), Geographically Weighted Regression (GWR) with spatial effects, as well as the generalized multilevel hierarchical linear model (GMHL) were used. The new findings produced for this dissertation provide a more comprehensive understanding of urban dynamics and could help to improve the planning process. It is hoped that this dissertation will contribute to that development as well as stimulate further research.

A dieta é considerada um dos fatores que mais influencia o comportamento espacial dos primatas. Muitas pesquisas que abordam essa relação apresentam similaridades nos seus delineamentos, mas não existe uma metodologia padrão comum. Para compreender melhor a relação entre dieta e padrões espaciais dos primatas, é preciso investigar o efeito de alguns problemas metodológicos. No presente estudo, descrevemos quatro:o problema da descontinuidade do registro, que é o efeito da dependência temporal sobre registros distribuídos desigualmente ao longo do tempo; o problema de filtragem, que descreve a dificuldade para isolar o efeito da variável independente, dieta; o problema do fracionamento, que alerta sobre os perigos de transportar conclusões a grande escala com dados de pequena escala; e o problema da linearidade fechada, que discute a validade das medidas de superfície quando o tempo registrado é muito curto. Desenvolvemos uma metodologia para controlar esses problemas. A metodologia foi aplicada com registros da dieta e localizações de um grupo de Sapajus nigritus do Parque Estadual Carlos Botelho, São Paulo, coletados em dois períodos, 2007-2008 e 2009-2010. Também utilizamos um delineamento mais convencional e comparamos os resultados obtidos com ambas asmetodologias. Os resultados foram similares com ambos os delineamentos, mas em alguns aspectosa metodologia nova teve melhor desempenho. A dieta foi analisada utilizando as categorias alimentos agregados e dispersos. Essa classificação tem sido criticada pela amplitude das suas categorias, mas no presente estudo foi sensível a mudanças nos padrões espaciais de Sapajus. Os resultados não foram conclusivos com períodos grandes descontínuos, mas foram visíveis com períodos curtos e contínuos. Com o aumento de consumo de itens dispersos diminuiu a distância diária percorrida e o espaço foi utilizado de forma mais uniforme. As maiores áreas foram observadas com períodos de consumo misto. Os padrões espaciais desses primatas foram bem descritos com base na energia obtida e os custos do deslocamento / Diet is considered one of the most influential factors on primates spatial patterns. Many studies that have addressed this relationship present methodological similarities, but there is no common standard methodology. In order to better understand the relationship between diet and spatial patterns of primates we need to investigate the effect of some methodological problems. In thisstudy we describe four of these problems: the problem of the discontinuous data, that is, the effect of autocorrelation when observations are distributed unevenly over time; the filtering problem, that describes the difficulties to isolate the effect of the independent variable, in this case, the diet; the partialness problem, that calls our attention to the risk of making large scale conclusions based on small scale data; and the problem of fenced linearity, that discusses the validity of area estimations, when time sampling is too small. We developed a methodology to control these problems and tested it on the data collected for one group of Sapajus nigritus in Carlos Botelhos State Park, São Paulo (Brazil), during two periods, 2007-2008 and 2009-2010. We also used a more conventional methodology to compare results. Although the results obtained using both methodologies were similar, in some cases, the new one performed better. Diet was analyzed byusing the categories patchy and dispersed food items. This dichotomous classification has been criticized because of the broadness of its categories, but in the present study it was sensitive to changes in Sapajus spatial patterns. Results were inconclusive when analyzing data from large discontinuous periods, but some conclusions were obtained when considering data from short continuous periods: daily path length decreased and the use of space was more uniform with the increase of dispersed items on the diet. The largest ranging areas were observed when the diet was mixed. Spatial patterns of these primates can be explained in terms of energy obtained and travel costs

A dieta é considerada um dos fatores que mais influencia o comportamento espacial dos primatas. Muitas pesquisas que abordam essa relação apresentam similaridades nos seus delineamentos, mas não existe uma metodologia padrão comum. Para compreender melhor a relação entre dieta e padrões espaciais dos primatas, é preciso investigar o efeito de alguns problemas metodológicos. No presente estudo, descrevemos quatro:o problema da descontinuidade do registro, que é o efeito da dependência temporal sobre registros distribuídos desigualmente ao longo do tempo; o problema de filtragem, que descreve a dificuldade para isolar o efeito da variável independente, dieta; o problema do fracionamento, que alerta sobre os perigos de transportar conclusões a grande escala com dados de pequena escala; e o problema da linearidade fechada, que discute a validade das medidas de superfície quando o tempo registrado é muito curto. Desenvolvemos uma metodologia para controlar esses problemas. A metodologia foi aplicada com registros da dieta e localizações de um grupo de Sapajus nigritus do Parque Estadual Carlos Botelho, São Paulo, coletados em dois períodos, 2007-2008 e 2009-2010. Também utilizamos um delineamento mais convencional e comparamos os resultados obtidos com ambas asmetodologias. Os resultados foram similares com ambos os delineamentos, mas em alguns aspectosa metodologia nova teve melhor desempenho. A dieta foi analisada utilizando as categorias alimentos agregados e dispersos. Essa classificação tem sido criticada pela amplitude das suas categorias, mas no presente estudo foi sensível a mudanças nos padrões espaciais de Sapajus. Os resultados não foram conclusivos com períodos grandes descontínuos, mas foram visíveis com períodos curtos e contínuos. Com o aumento de consumo de itens dispersos diminuiu a distância diária percorrida e o espaço foi utilizado de forma mais uniforme. As maiores áreas foram observadas com períodos de consumo misto. Os padrões espaciais desses primatas foram bem descritos com base na energia obtida e os custos do deslocamento / Diet is considered one of the most influential factors on primates spatial patterns. Many studies that have addressed this relationship present methodological similarities, but there is no common standard methodology. In order to better understand the relationship between diet and spatial patterns of primates we need to investigate the effect of some methodological problems. In thisstudy we describe four of these problems: the problem of the discontinuous data, that is, the effect of autocorrelation when observations are distributed unevenly over time; the filtering problem, that describes the difficulties to isolate the effect of the independent variable, in this case, the diet; the partialness problem, that calls our attention to the risk of making large scale conclusions based on small scale data; and the problem of fenced linearity, that discusses the validity of area estimations, when time sampling is too small. We developed a methodology to control these problems and tested it on the data collected for one group of Sapajus nigritus in Carlos Botelhos State Park, São Paulo (Brazil), during two periods, 2007-2008 and 2009-2010. We also used a more conventional methodology to compare results. Although the results obtained using both methodologies were similar, in some cases, the new one performed better. Diet was analyzed byusing the categories patchy and dispersed food items. This dichotomous classification has been criticized because of the broadness of its categories, but in the present study it was sensitive to changes in Sapajus spatial patterns. Results were inconclusive when analyzing data from large discontinuous periods, but some conclusions were obtained when considering data from short continuous periods: daily path length decreased and the use of space was more uniform with the increase of dispersed items on the diet. The largest ranging areas were observed when the diet was mixed. Spatial patterns of these primates can be explained in terms of energy obtained and travel costs

Plant spatial patterns have been studied to gain insight into plant interactions such as competition and facilitation (positive plant interactions). The stress gradient hypothesis predicts that as environmental stress increases facilitation dominates, while competition dominates in less stressful conditions. Beneficial plants (nurses) can create favorable abiotic conditions for subanopy plants. Additionally, palatable herbaceous species growing under nurse shrub canopies benefit from physical protection. I investigated spatial associations between Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and three native grasses (Poa secunda, Elymus elymoides, and Pseudoroegneria spicata) across a rainfall gradient in the Great Basin, USA. I also explored the effect of grazing on grass-shrub spatial associations. I hypothesized that positive shrub-grass spatial associations would become more frequent at lower rainfall levels; I further hypothesized that 1) at intermediate levels of stress, positive grass-shrub spatial associations would dominate and 2) at extreme levels of stress, positive grass-shrub spatial associations and interactions would no longer dominate. At high moisture stress, the addition of grazing stress may limit the nurse’s ability to provide to benefits to subcanopy plants. Cover of P. secunda was greater in shrub canopy microsites than interspaces at low to moderate levels of rainfall. Cover and density of E. elymoides were greater in sagebrush canopies over most rainfall levels. Elymus elymoides and P. spicata were taller and narrower in basal width and less likely to be grazed in canopy versus interspace microsites. I next investigated the effects of grazing intensity over a rainfall gradient and found a significant interaction of rainfall and microsite on P. secunda cover. Poa secunda formed positive interactions with A. tridentata at lower rainfall levels, regardless of grazing intensity. Its cover was significantly greater in interspaces at high rainfall compared to low rainfall sites. Elymus elymoides density was greater in canopy vs. interspace microsites, regardless of rainfall level or grazing intensity. Plant spatial associations can indicate which nurse microsites are favorable to plant growth and may improve seeding or planting success during ecological restoration. My results suggest that exploiting sagebrush canopy microsites for restoration of native perennial grasses would improve plant establishment, growth or survival particularly in drier areas.

This study combines Optical Plankton Counter data on zooplankton abundance and Acoustic Doppler Current Profiler data on water currents to test hypotheses about spatial zooplankton distributions near a major point of land affecting local wind and water current patterns. Data were collected by repeatedly sampling a 2 km linear transect in the South Arm of Lake Opeongo, Ontario, Canada during July, 2008. Moving Split Window techniques were used to identify breakpoints in both zooplankton biomass concentration and a measure of water turbulence, and confirmed an effect of the topographic feature on local zooplankton distributions. Using additional data collected in 2001 and 2003, zooplankton abundance distributions were also tested under three wind speed ranges predicted from physical principles to correspond to varying stability of the water column. Significant differences were found in the variability and patch sizes of the distributions, indicating the importance of wind speeds on zooplankton patchiness.

This study combines Optical Plankton Counter data on zooplankton abundance and Acoustic Doppler Current Profiler data on water currents to test hypotheses about spatial zooplankton distributions near a major point of land affecting local wind and water current patterns. Data were collected by repeatedly sampling a 2 km linear transect in the South Arm of Lake Opeongo, Ontario, Canada during July, 2008. Moving Split Window techniques were used to identify breakpoints in both zooplankton biomass concentration and a measure of water turbulence, and confirmed an effect of the topographic feature on local zooplankton distributions. Using additional data collected in 2001 and 2003, zooplankton abundance distributions were also tested under three wind speed ranges predicted from physical principles to correspond to varying stability of the water column. Significant differences were found in the variability and patch sizes of the distributions, indicating the importance of wind speeds on zooplankton patchiness.

This research examines the associations between landscape spatial patterns of urban forests, health-related quality of life (HRQOL), and obesity (captured by body mass index, BMI) among Hispanic children living in Houston's inner city neighborhoods. One hundred 4th and 5th grade children and their mothers were recruited from five elementary schools. Children's BMI values were calculated from objectively measured height and weight. Children were surveyed about their environmental perceptions, physical activity, and socio-demographic factors. In addition, both the children and their mothers completed the PedsQL survey to measure the children's HRQOL. Using high-resolution Digital Orthophoto Quarter Quadrangle (DOQQ) aerial photo imagery, landscape spatial patterns of urban forests were measured by Geographic Information Systems (GIS) and remote sensing. FRAGSTATS was used to compute various landscape indices for areas within a half-mile and a quarter-mile from each child's home, using both airline and network distances. Multiple regression models were used to predict the children's BMI and HRQOL. Four groups of independent variables were examined: landscape indices, socio-demographic variables, physical activity, and environmental perceptions and satisfaction (factor variables). Separate models were estimated using the GIS variables captured at different spatial extents including a half-mile and quarter-mile airline buffer, and a half-mile and quarter-mile network buffer. This research showed that several landscape indices were significantly correlated with the children's BMI and HRQOL. Well-connected landscape spatial patterns and more tree patches (disaggregated landscape patterns) in a half-mile airline buffer from the subjects' homes were negatively associated with the children's BMI. Less fragmented landscape spatial conditions and larger areas of urban forests and tree patches showed positive associations with the children's HRQOL. This research adds to the current multi-disciplinary area of research on environment-health relationships, by investigating the roles of urban greeneries and linking their spatial structure to children's obesity and quality of life.

Acropora cervicornis was once one of the dominant reef building corals of the Caribbean, Florida Keys, and Dry Tortugas (DRTO), but since the 1970’s populations have been decimated throughout their geographic range. Recently, a repopulation was documented through detailed benthic surveys conducted by the U.S. Geological Survey at three locations (Pulaski Shoal, East Key, and Loggerhead Key) within DRTO. Benthic surveys using the U.S Geological Survey’s Along-Track Reef Imaging System (ATRIS) revealed hundreds of previously undocumented colonies. These discoveries have provided a unique data-set, allowing a comparison between the historical (1883, 1976) and contemporary distributions (2009, 2011) of A. cervicornis. Kernel density estimates were used to analyze shifts in high density areas and non-parametric multivariate analysis of variance tests were used to analyze differences between years in location and extent of the distribution. The results from the KDEs indicated high density areas have shifted among year’s at all three study areas. The comparison of the location and extent of the historical and modern A. cervicornis distributions revealed similarities and differences among years that varied among the study areas. This information is important to the management of this species because it provides vital information on the extent and location of the current distribution relative to historical levels. This study also provides documentation of the population dynamics and ecosystem changes over large time scales within the DRTO region. The above mentioned dataset was also used in a second study to quantify 1) variations in density among factors such as location (study area), suitable habitat type, and water depth, 2) overall spatial population patterns, and 3) spatial patterns in A. cervicornis density. Results indicated population structure was significantly clustered (P = 0.001) at Pulaski Shoal and Loggerhead Key with areas containing hotspots or significantly higher density (P < 0.05). Although significant hotspots existed, density did not significantly differ among suitable habitat types. Compared to all other factors, water depth had the largest effect on the variation in mean density of A. cervicornis. These findings are vital to understanding the recovery of this species in terms of current habitat and depth associations.

Spatial segregation among life cycle stages has been observed in many stage-structured species, including species of the flour beetle Tribolium. Patterns have been observed both in homogeneous and heterogeneous environments. We investigate density dependent dispersal of life cycle stages as a mechanism responsible for this separation. By means of mathematical analysis and numerical simulations, we explore this hypothesis using stage-structured, integrodifference equation (IDE) models that incorporate density dependent dispersal kernels.In Chapter 2 we develop a bifurcation theory approach to the existence and stability of (non-extinction) equilibria for a general class of structured integrodifference equation models on finite spatial domains with density dependent kernels. We show that a continuum of such equilibria bifurcates from the extinction equilibrium when it loses stability as the net reproductive number n increases through 1. We give several examples to illustrate the theory.In Chapter 3 we investigate mechanisms that can lead to spatial patterns in two dimensional Juvenile-Adult IDE models. The bifurcation theory shows that such patterns do not arise for n near 1. For larger values of n we show, via numerical simulation, that density dependent dispersal can lead to the segregation of life cycle stages in the sense that each stage peaks in a different spatial location.Finally, in Chapter 4, we construct spatial models to describe the population dynamics of T. castaneum, T. confusum and T. brevicornis and use them to assess density dependent dispersal mechanisms that are able to explain spatial patterns that have been observed in these species.

Thesis (M.S.)--Miami University, Dept. of Botany, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], iv, 109 p. Includes bibliographical references (p. 36).