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Gracias a La Nacionalización De Los Hidrocarburos: a Critical Analysis of Bolivia’s Transition to Compressed Natural Gas

Description: This paper critically analyzes the implementation of compressed natural gas and the ways in which it creates discourse in urban Bolivia. The rapidly developing nation is keen on making ubiquitous use of compressed natural gas a reality by issuing subsidies, citing increased mobility, savings, and environmental stewardship as the primary motives. Currently, eight out of every 10 public vehicles in Bolivia are powered by compressed natural gas. Through semi-structured interviews, questionnaires and secondary data collection, this paper elucidates the transitional process of building a natural gas-based transport network through discursive governance. This work draws on the critical discourse analysis literature to dissect disaggregated modal preference data, government documents, and news articles collected in Santa Cruz, Latin America's second fastest growing city. Moreover, this paper identifies and examines the ways in which the counter-discourse impacts the transformation of the country’s energy matrix. Results show that Bolivian automobile owners are reluctant to convert their automobiles, despite reduced transportation costs, stating that minimal compressed natural gas infrastructure exists outside of urban areas, and the conversion damages their vehicles’ motor. Additionally, the research reveals that automobile owners are currently the main beneficiaries, though respondents who do not posses an automobile speak more favorably of natural gas. Finally, this research illustrates that the compressed natural gas-oriented policies encourage personal automobile use that continues to drive socio-spatial segregation of Santa Cruz’s residents. Thus, the compressed natural gas discourse helps shape the urban landscape by persuading the public to consume domestically extracted and manufactured natural gas.
Date: May 2015
Creator: McCollum, Jerl Levi

Pastoral Livelihoods and Household Water Management in the Central Argentine Andes

Description: Pastoralists tend to occupy highlands and drylands lands with uncertain climates and are experienced at coping with climatic variability and drought. Increasingly, however, the speed with which climate patterns are changing has become an issue of concern. This study examines household water management strategies of pastoralists in western Argentina. In this semi-arid region, pastoralists rely primarily on streams and springs fed by snow and glacier melt from the Andes, and have developed various strategies to meet their water needs. They also deal with myriad challenges posed by climate, economic, and socio-cultural change and work vigorously to maintain their herds – a combination of cattle, goats, and sheep – in this water scarce region. The goal of this study is to understand: 1) different household water management strategies; 2) the ways pastoral livelihoods are changing in response to changes in water supply; and 3) the socio-economic changes that affect pastoral livelihoods. Information from interviews, household surveys, and participant observations reveals that climate fluctuation impacts water supplies and use, herd size, and expenses made on tanks, technology, and infrastructure for the storage and transport of water, food for animals, and subsistence crops. Understanding the micro-scale, water practices of pastoral households provides insight into the ways rural populations in semi-arid and arid environments respond to changes in climate and meet their water needs. Moreover, these findings can contribute to scholarship on traditional and local knowledge and resource management systems, and may potentially inspire the development of adaptive management solutions.
Date: May 2015
Creator: Parker, Julie

Structure, Composition, and Regeneration of Cross Timbers Forest Fragments in Different Land Use Contexts

Description: Throughout its current range, the Cross Timbers forest ecosystem is vulnerable to land-use change. In this study, we examined the surrounding land use matrix on the vegetation structure, composition and regeneration of six Cross Timbers forest fragments in Denton County, Texas (north of the Dallas-Fort Worth metroplex). Two fragments adjacent to agricultural land, two to residential neighborhoods, and two formally protected forest sites were selected. In summer 2015, five 100 m2 plots were randomly established in each fragment at least 200 meters from the edge. In each plot, all live and dead trees ≥ 3 cm diameter were identified and their height and diameter at breast height (DBH at 1.3 m aboveground) measured. Evidence of dumping (presence of trash) was recorded as an index of human frequentation. Differences in vegetation structure among the forest fragments were found. Most notably, fragments adjacent to agriculture contained 25% to 50% fewer trees per hectare than all other sites (Kruskal-Wallis, p < 0.02), especially trees <10 cm DBH. However, residential fragments had fewer trees that were ≥15 cm DBH compared to the other fragments, indicating that these are the youngest of the forest patches surveyed. Trash was observed in 60% of plots surveyed at residential forest sites, showing high levels of human frequentation compared to the protected and agricultural forest sites. Agricultural sites contained the lowest number of recorded tree species and were most similar to each other, sharing 91% of species. These findings indicate that surrounding land use affects forest structure and composition, consequently affecting valuable ecosystem services including wildlife habitat, aesthetics and recreation.
Date: May 2015
Creator: Dunn, Ingrid

Zooarchaeology and Biogeography of Freshwater Mussels in the Leon River During the Late Holocene

Description: The Leon River, a small-medium river in central Texas, is highly impacted by multiple impoundments, enrichment from agricultural runoff, and decreased dissolved oxygen levels. This degraded river contains sixteen unionid species, two of which are both endemic to the region and candidates for the federal endangered species listing (Quadrula houstonensis and Truncilla macrodon). While there is a short historical record for this river basin and a recent modern survey completed in 2011, zooarchaeological data adds evidence for conservation efforts by increasing the time depth of data available and providing another conservation baseline. Zooarchaeological data for the Leon River is available from the two Late Holocene archaeological sites: 41HM61 and the Belton Lake Assemblages. Data generated from these assemblages describe the prehistoric freshwater mussel community of the Leon River in terms of taxonomic composition and structure. By comparing this zooarchaeological data to the data generated by the longitudinal modern survey of the Leon River, long term changes within the freshwater mussel community can be detected. A conceptual model is constructed to evaluate how robusticity, identifiability, and life history ecology affect unionid taxonomic abundances in zooarchaeological data. This conceptual model functions as an interpretive tool for zooarchaeologists to evaluate forms of equifinality in zooarchaeological assemblages. This thesis determines differences between the late Holocene and modern freshwater community of the Leon River, explores how different alternative mechanisms influence zooarchaeological data, and exemplifies of how zooarchaeological data can be used for conservation biology.
Date: May 2015
Creator: Popejoy, Traci Glyn

Dismantling the Psychiatric Ghetto: Evaluating a Blended-Clinic Approach to Supportive Housing in Houston, Texas

Description: Locational decisions based on stigma and low funding have handicapped the efficiency of community based mental healthcare in the United States since 1963. However, the pattern of services in the 21st century American South remains largely unknown. This thesis addresses this gap in knowledge by using a mixed methodology including location allocation, descriptive statistics, and qualitative site visits to explore the geography of community clinics offering both physical and mental health services. The City of Houston has proposed using these facilities to anchor new supportive housing, but introducing more fixed costs to a mismatched system could create more problems than solutions. The findings of this study suggest the presence of an unnecessary concentration of services in the central city and a spatial mismatch between accessible clinics and the poor, sick people in need. Furthermore, this research reveals a new suburban pattern of vulnerability, calling into question long-held assumptions about the vulnerability of the inner city. Building supportive housing around existing community clinics, especially in the central city, may further concentrate vulnerable people thereby contributing to intensifying patterns of service-seeking drift and the continued traumatization of mentally ill homeless persons in Houston.
Date: December 2014
Creator: Lester, Katherine Ann

Effects of Non-homogeneous Population Distribution on Smoothed Maps Produced Using Kernel Density Estimation Methods

Description: Understanding spatial perspectives on the spread and incidence of a disease is invaluable for public health planning and intervention. Choropleth maps are commonly used to provide an abstraction of disease risk across geographic space. These maps are derived from aggregated population counts that are known to be affected by the small numbers problem. Kernel density estimation methods account for this problem by producing risk estimates that are based on aggregations of approximately equal population sizes. However, the process of aggregation often combines data from areas with non-uniform spatial and population characteristics. This thesis presents a new method to aggregate space in ways that are sensitive to their underlying risk factors. Such maps will enable better public health practice and intervention by enhancing our ability to understand the spatial processes that result in disparate health outcomes.
Date: December 2014
Creator: Jones, Jesse Jack

Resource Intensification of Small Game Use at Goodman Point, Southwestern Colorado

Description: This analysis of faunal remains from eleven archaeological sites in the northern San Juan region, extensively occupied by the Ancestral Pueblo people until they leave the region by AD 1300, explores the effects of resource intensification of small wild and domestic resources leading up to this regional depopulation. By examining multiple lines of evidence, in addition to faunal abundance, causal factors are identified to address changes in abundances through time. In particular, age- and sex-based mortality are examined for lagomorphs (jackrabbits and cottontails) and domesticated turkey, respectively, to test hypotheses generated using the prey and patch choice models. Analyses of these resources follow a systematic paleontology which provides explicit identifications made of five sites from a large study area, Goodman Point Pueblo Unit. These data are integrated with those from large village sites from the encompassing central Mesa Verde region. The results of both analyses help clarify why the Ancestral Pueblo people left southwestern Colorado. During the final twenty-year occupation period, the results of this study support a shift from reliance on turkey husbandry to intense exploitation of locally available garden resources (i.e. cottontails).
Date: December 2014
Creator: Ellyson, Laura Jean

Assessment of Post-earthquake Building Damage Using High-resolution Satellite Images and LiDAR Data - a Case Study From Port-au-prince, Haiti

Description: When an earthquake happens, one of the most important tasks of disaster managers is to conduct damage assessment; this is mostly done from remotely sensed data. This study presents a new method for building detection and damage assessment using high-resolution satellite images and LiDAR data from Port-au-Prince, Haiti. A graph-cut method is used for building detection due to its advantages compared to traditional methods such as the Hough transform. Results of two methods are compared to understand how much our proposed technique is effective. Afterwards, sensitivity analysis is performed to show the effect of image resolution on the efficiency of our method. Results are in four groups. First: based on two criteria for sensitivity analysis, completeness and correctness, the more efficient method is graph-cut, and the final building mask layer is used for damage assessment. Next, building damage assessment is done using change detection technique from two images from period of before and after the earthquake. Third, to integrate LiDAR data and damage assessment, we showed there is a strong relationship between terrain roughness variables that are calculated using digital surface models. Finally, open street map and normalized digital surface model are used to detect possible road blockages. Results of detecting road blockages showed positive values of normalized digital surface model on the road centerline can represent blockages if we exclude other objects such as cars.
Date: August 2014
Creator: Koohikamali, Mehrdad

Identifying Cultural and Non-cultural Factors Affecting Litter Patterns in Hickory Creek, Texas

Description: Plastic deposition in hydrological systems is a pervasive problem at all geographic scales from loci of pollution to global ocean circulation. Much attention has been devoted to plastic deposition in marine contexts, but little is known about inputs of plastics into local hydrological systems, such as streams. Any attempt to prevent plastic litter must confront people’s behaviors, so archaeological concepts are used to distinguish between various cultural inputs (e.g., littering) and non-cultural forces (e.g., stream transport) that affect litter patterns on the landscape. Litter surveys along Hickory Creek in Denton, TX, are used to assess these factors.
Date: August 2014
Creator: Carpenter, Evan S.

Retail Change and Light Rail: an Exploration of Business Location Changes Accompanying Commuter Rail Development in Denton County, Texas

Description: Within the past few decades, commuter rail routes in several major metropolitan areas have been implemented to provide an alternative to automobile transportation. Urban planners in these cities are looking to commuter rail to mitigate congestion and pollution. However, research on the impacts of commuter rail development on the surrounding retail landscape is still needed. In metropolitan Dallas-Fort Worth, the Denton County Transportation Authority recently opened its new A-Train light rail service linking suburban Denton and downtown Dallas. This thesis examines urban changes that occurred in the years before and after the A-Train line's 2011 opening, with a focus on restaurant and retail development in the vicinity of the A-Train stations in Denton County. This analysis evaluates changes in retail density and type, the population surrounding stations, and municipal initiatives that shape the retail landscape of station vicinities. This was done by gathering field data, retailer listings, population data, and conducting interviews with local businesses and city planners. The findings suggest that A-train stations have had a differential impact on the surrounding landscape, depending on the existing retail landscape, the types of retailers present, and the current state of municipal infrastructure that promotes accessibility. Overall, results suggest that urban planners play a vital role in harnessing the potential of commuter rail to promote nearby retail growth.
Date: August 2014
Creator: Yarbrough, Trevor S.

Effects of Vegetation Structure and Canopy Exposure on Small-scale Variation in Atmospheric Deposition Inputs to a Mixed Conifer Forest in California

Description: Data on rates of atmospheric deposition is limited in many montane ecosystems, where high spatial variability in meteorological, topographic, and vegetation factors contributes to elevated atmospheric inputs and to the creation of deposition hotspots. Addressing the ecological consequences of increasing deposition in these areas will require a better understanding of surface controls influencing atmospheric deposition rates at both large and small-scales. The overarching objective of this thesis research was to understand the influence of vegetation structure and canopy exposure on small-scale patterns of atmospheric sulfate, nitrate, and chloride deposition inputs to a conifer forest in the Santa Cruz Mountains, California. Throughfall ion fluxes (i.e., ions delivered in water that pass from the forest canopy to the forest floor), bulk deposition (i.e., primarily wet deposition), and rainfall data were collected during the rainy period from October 2012 to May 2013. Throughfall SO42-, Cl-, and NO3- fluxes were measured beneath eight clusters of Douglas fir (Pseudotsuga menziesii) trees (three trees per cluster) differing in tree size (i.e., diameter at breast height; DBH) and canopy exposure. In each cluster, a throughfall collector was placed 1-meter from the bole of an individual tree, for a total of 24 individual collectors. The position of each throughfall collector was recorded with a Trimble® GPS. In addition, tree height, tree diameter, and leaf area index, were measured for all trees. LiDAR data were obtained from GeoEarthScope’s Northern California Airborne LiDAR project and used to model the elevation (DEM), canopy surface height (DSM), tree height (CHM), slope, and curvature of the canopy surface across the entire study area. Over the rainy season, total throughfall flux of SO42--S, a conservative tracer of total deposition (wet + dry + fog), to Douglas fir clusters ranged from 1.44 - 3.84 kg S ha-1 wet season-1, while dry and fog deposition ranged ...
Date: May 2014
Creator: Griffith, Kereen

Importance and Spatial Distribution of Phytophthora Ramorum Host Species in a Coast Redwood Forest

Description: Phytophthora ramorum, an exotic forest pathogen known as ‘sudden oak death’ (SOD), has received considerable attention in recent years because of its effects on vegetation structure, composition, and fire disturbance regimes in western U.S. coastal forests. This research examines differences in the importance (e.g., density, dominance, and frequency) and distribution of five host species of P. ramorum–– Umbellularia californica (California bay laurel), Quercus agrifolia (coast live oak), Pseudotsuga menziesii (Douglas fir), Sequoia sempervirens (Coast redwood), and Arbutus menziesii (Madrone)––in Soquel, California. A stratified random sampling design was used to select 66 plots surrounding a managed forest edge in Soquel Demonstration State Forest. Vegetation measurements were conducted in summer 2013. In each plot, all trees ≥3 cm diameter at breast height (DBH) were identified to species, counted, and DBH, height, and canopy position measured. Leaf area index (LAI) of bay laurel was measured to quantify the amount of leaves available for pathogen dispersal with a LiCOR 2200 Plant Canopy Analyzer. In addition, morning (9:00 am) and afternoon (1:00 pm) photosynthetically active radiation (PAR) were quantified using a quantum light sensor. This paper examines the influence of environmental variables, including distance to edge, aspect, slope, and light availability on host species spatial patterns in Soquel, CA. Studying P. ramorum host pattern and importance among managed forest edges is critical for determining hotspots most susceptible to infection and spread, thus relevant for implementing control measures.
Date: May 2014
Creator: Gray, Alicia E.

Contribution of Hurricane Ike Storm Surge Sedimentation to Long-term Aggradation of Coastal Marshes in Southeastern Texas and Southwestern Louisiana

Description: Coastal marshes and wetlands are vital natural resources that offer habitats for plants and animals, serve as ecological filtration for soil and water pollutants, and act as protection for coastlines. Fishing, both commercial and sport, has a large economic impact in the study area – the Gulf Coast between Galveston Bay, TX and Oak Grove, LA. The objective of this research was to determine the contribution of Hurricane Ike storm surge sedimentation to long-term marsh aggradation in Texas and Louisiana coastal marshes. The research hypothesized that Hurricane Ike’s storm surge deposit would be equal to decades and possibly even a century’s worth of the average annual non-storm sedimentation. A quantitative field study was performed. The storm surge deposit was examined in a series of 15 transects covering approximately 180 km east of Hurricane Ike’s landfall. Nine of the 15 transects were re-surveyed a year after the initial measurement to assess preservation of the deposit. The results demonstrate that Hurricane Ike contributed between 10 to 135 years’ worth of sediment to coastal marshes along the coasts of Texas and Louisiana, and the sediment deposits have been preserved for over two years.
Date: August 2013
Creator: Denlinger, Emily E.

Examining the Role of Latitude and Differential Insolation in Asymmetrical Valley Development

Description: Valley development through erosional processes typically tends to create symmetrical valleys. Over time, water cuts through the substrate to create valleys, gorges, and canyons for which the sides are the valley are evenly sloped. However, there are anomalies to this process. Asymmetrical valleys have been well-documented even in areas of uniform substrate or little tectonic uplift. One proposed explanation for the asymmetry of these valleys is differential insolation. This may lead to different microclimates from one slope to another which alter the rate and extent of erosion. Since the differences in received insolation vary with latitude (especially in streams that flow along an east/west axis), it follows that the degree of asymmetry should also vary with latitude if differential insolation is a primary driving factor in the development of these valleys. To evaluate if insolation plays a role in the development of asymmetrical valleys, this study examines variability in asymmetry across 447 valleys in nine study areas located at different latitudes. The degree of asymmetry for each valley was measured by using 30 meter resolution digital elevation models (DEMs) to determine the slope angle of each side of the valley. Asymmetry was measured by computing a ratio of the average slope angle for each side of the valley (larger value divided by smaller). If the resulting value is one, the valley is deemed symmetrical. As the value increases, the degree of asymmetry increases. This investigation found that contrary to expectations, valleys at lower latitudes tend to have a higher degree of asymmetry than those at higher latitudes, which suggests that differential insolation does not play a major role in the development of these valleys. Instead, this study found that high altitudes and low latitudes are more frequently associated with a higher degree of asymmetry. These unexpected findings open the door ...
Date: August 2013
Creator: Curran, Lorna L.

Finding Terroir in Southwest Iowa

Description: Terroir combines the physical landscape of the vineyard with the grapevines and the methods and techniques used to produce wine from the grapes. This study used a GIS to identify the characteristics of the physical landscape in Pottawattamie, Mills, Montgomery, Fremont, and Page counties in southwestern Iowa. The components were combined in the GIS using a weighted linear index to identify areas suitable for vineyard development and to identify the general characteristics of the area. Vineyard owners were interviewed to help determine the weighting system to use in the GIS and to determine their perceptions of how the physical landscape impacts their vineyards, as well as to determine what grape varieties they plant in their vineyards and their decisions on making wine from these grapes. This information was collected to identify whether the vineyard owners had developed a sense of place for their vineyards and how this sense might aid them in the development of a terroir for their wines. The resulting perceptions about the individual wineries were then considered in conjunction with the results from the GIS modeling to understand how the physical landscape influences the concepts of sense of place and terroir in southwest Iowa. The physical landscape of southwest Iowa was fairly uniform, as were the grape varietals planted in the vineyards. This created a measure of similarity among the wineries, while individuality between wineries was then created by the wine-makers as they used different techniques to produce wine from the grapes. This allows each winery to develop a sense of place, yet be part of a larger sense of place that encompasses multiple wineries within the area.
Date: August 2013
Creator: Deines, Dory

Neural Tube Defect, Heart Defect, Oral Cleft and Their Geospatial Associations with Supermarket and Convenience Stores in the City of Dallas, Texas

Description: Birth defects are the leading cause of infant death in the United States. Research has linked poor maternal micronutrient intake to birth defects including neural tube defects, heart defects, and oral clefts. After investigating spatial patterns of these birth defects in the City of Dallas and the neighborhood characteristics within clusters, geospatial access to supermarkets and convenience stores measured by proximity and concentrations are examined as environmental risk factors for nutrition-related birth defects. Spatial clusters of all three nutrition-related birth defects exist in the City of Dallas. Cluster for NTD occurs in vulnerable places with lower income and high minority population specifically Hispanics with no supermarkets. Cluster for heart defects mostly occurs in high income and predominantly white neighborhoods with many supermarkets. Clusters of oral clefts mostly occurs in middle-class income with relatively high minority populations with many convenience stores. For the entire study area, geographical access to supermarkets that include healthy foods are shown to be spatially reachable from most of mothers of infants with nutrition-related birth defects as well as convenience stores that typically include the majority of unhealthy processed foods with very few nutrients. Thus, not only easy geographical access to healthy food vendors but to convenience stores with low quality produces is observed at the same time.
Date: August 2013
Creator: Miyakado, Haruna

A Quantitative Assessment of Site Formation at the Dmanisi Archaeological Site, Republic of Georgia

Description: The focus of this thesis was to gather and analyze micromorphological and petrographic data on soils at the archaeological site of Dmanisi in order to better understand the extent to which the deposition and alteration of the sediments has affected the preservation of artifacts and faunal remains. A major goal of this research was to test hypothesis related to why bone material is discovered in some strata and not in others. This research focuses on the application of micromorphology (supplemented with other methods) to the soils through the use of petrographic analysis of thin sections and scanning electron microscopy. These techniques complement previous field analyses by providing a quantitative assessment of individual strata through point counting and chemical mapping. The results of this research support the hypothesis that the sediments are predominantly mafic ashes, while showing that there is very little soil development in the strata. This suggests quick episodic burial in a relatively dry climate, confirming the hypothesis for a short time sequence in the strata. Additionally, differential weathering probably did not play a significant role in the differential abundance of bone remains among the strata at Dmanisi.
Date: August 2013
Creator: Crislip, Peter S.

Site Formation Processes and Bone Preservation Along the Trinity River Basin, North Central Texas

Description: This thesis presents the results of geoarchaeological investigations of several archaeological sites along the Elm Fork of the Trinity River in north central Texas. Archaeological data recorded from mitigation excavations in Denton and Cooke counties were analyzed to understand the geologic impacts on faunal preservation resulting from site formation processes. The faunal assemblages are highly fragmented, even in settings known for good preservation. A combined approach using geoarchaeological and taphonomic techniques was implemented to examine how fragmentation, evidence of soil weathering, and differential preservation were impacted by differing geologic conditions throughout the river basin. Intrasite and intersite results of the sites show that a great deal of variability of faunal preservation is present at difference scales of analysis.
Date: August 2013
Creator: Colvin, Jessica

Spatial Mismatch Between Hiv Infection and Access to Hiv Service Facilities in Texas

Description: Since 2004, the number of people living with HIV (PLWH) has steadily increased by about 5% and currently, the number in Texas is about 86,000. Though the National HIV/AIDS Strategic Plan seeks to ensure “unfettered access to quality healthcare”, barriers to access still exist especially among minority populations. This study examines the relationship between HIV infection rates and the geographic location of HIV service centers with a focus on 4 counties: namely, Dallas, Denton, Harris and Tarrant. The goal is to show whether there is a spatial mismatch between HIV rates and service providers. Are service facilities located in zip codes where they are most needed? Using the vulnerability framework and the Inverse Care Law (ICL), we address the research question using demographic variables (race/ethnicity, sex, poverty, education attainment) and HIV data. Our results show that extreme vulnerable zip codes have high HIV rates and closest proximity to HIV service providers.
Date: August 2013
Creator: Aggrey Korsah, Emmanuel

Assessing the Role of Smaller Format Retailers on the Food Desert Landscape in Dallas, Texas

Description: Many policy and business decisions regarding food deserts in the U.S. are based on the United States Department of Agriculture (USDA) definition of a food desert. This definition only includes large/national chain grocery retailers, based on the assumption that these major retailers are the only affordable sources of food contributing to balanced diets. As alternative distribution channels, including smaller stores, start to include groceries in their product offering, the need to consider the role of other businesses in the food retailing environment should be addressed. This thesis assesses the role of smaller format grocery retailers (small local grocers, convenience stores, gas stations, dollar stores, and drug stores) in shaping the food desert landscape in Dallas, Texas. The analysis evaluates the products offered in these stores, and then identifies the difference these stores make when included in the USDA analysis. This was done by collecting in-store data to determine the variety of products offered, the affordability of those products, and the overall healthfulness of the store. In addition, the gaps in supply and demand were identified in the USDA-defined food deserts in order to identify the impact any smaller format retailer may have. The findings suggest that, overall, smaller format retailers do offer a variety of products needed for a balanced diet. However, the products in these stores are mostly not affordable, and most stores offer more unhealthy foods, than unhealthy. Overall, results suggest dollar stores may play a role in alleviating the impact of food deserts.
Date: May 2013
Creator: Regan, Amanda D.

Automated Treetop Detection and Tree Crown Identification Using Discrete-return Lidar Data

Description: Accurate estimates of tree and forest biomass are essential for a wide range of applications. Automated treetop detection and tree crown discrimination using LiDAR data can greatly facilitate forest biomass estimation. Previous work has focused on homogenous or single-species forests, while few studies have focused on mixed forests. In this study, a new method for treetop detection is proposed in which the treetop is the cluster center of selected points rather than the highest point. Based on treetop detection, tree crowns are discriminated through comparison of three-dimensional shape signatures. The methods are first tested using simulated LiDAR point clouds for trees, and then applied to real LiDAR data from the Soquel Demonstration State Forest, California, USA. Results from both simulated and real LiDAR data show that the proposed method has great potential for effective detection of treetops and discrimination of tree crowns.
Date: May 2013
Creator: Liu, Haijian

Geoarchaeological Analysis of Two New Test Pits at the Dmanisi Site, Republic of Georgia

Description: This thesis presents the results of geoarchaeological investigations conducted at two new test pits, M11 and M12, at the paleoanthropological site of Dmanisi during the 2012 field season. This research is important for understanding the site formation processes occurring along the north-south axis of the Dmanisi site and how that affects the chronostratigraphic sequence and interpretation of archaeological materials here. With these excavations we can build a stronger interpretation for how broader areas of this site formed and changed both geologically and archaeologically. The geologic results of this study indicate that changes in sediment deposition and development episodes can affect interpretations of how long these sediments accumulated, how likely bones are to preserve, as well as how secondary gravel deposition can influence several archaeological interpretations. The archaeological results suggest that there could have been changes in occupation intensity between the stratum A and B phases although different rates of sediment deposition and surface stability could affect such artifact accumulations. In addition, during the stratum B phase there appears to be little change in artifact procurement behaviors and reduction characteristics by these hominins. The overall results of this research indicate that geologic factors should be addressed and cautions should be taken prior to making interpretations about archaeological assemblages.
Date: May 2013
Creator: Zack, Winston S.

Spatio-temporal Variation of Nitrate Levels in Groundwater in Texas, 1970 to 2010

Description: This study looks at spatial variation of groundwater nitrate in Texas and its fluctuations at 10 year increments using data from the Texas Water Development Board. While groundwater nitrate increased in the Ogallala and Seymour aquifers across the time period, the overall rate in Texas appears to be declining as time progresses. However, the available data is limited. Findings show that a much more targeted, knowledge based strategy for sampling would not only reduce the cost of water quality analysis but also reduce the risk of error in these analyses by providing a more realistic picture of the spatial variation of problem contaminants, thereby giving decision-makers a clearer picture on how best to handle the reduction and elimination of problem contaminants.
Date: December 2012
Creator: Rice, Susan C.

Geography of HIV Infection Among Adults Aged 50 Years and Older in Texas From 1999-2009

Description: Twenty four percent of all HIV infections in the United States occur among adults aged 50 and older (mature adults), yet little is understood of the dynamics of HIV infection among this group in Texas. Data from 1999 to 2009 examined the relationship between HIV spatial and temporal patterns affecting socio-economic and demographic variables including poverty, gender, race/ethnicity and mode of exposure. Results revealed highest HIV infection rates among White homosexual men, Black males engaged in IV-drug use, Black female heterosexuals and minorities in poverty. Concentrations of HIV infection among mature adults were located primarily in urban centers of Houston and Dallas and indicated increasing HIV infection rates from 1999 to 2009. These results will assist future allocation of resources by zip code in urban areas for this understudied population.
Date: August 2012
Creator: Hedrich, Mara Nicole