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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 … more
Date: May 2013
Creator: Liu, Haijian
Item Type: Refine your search to only Thesis or Dissertation
open access

A Comparative Analysis of Diseases Associated with Mining and Non-Mining Communities: A Case Study of Obusai and Asankrangwa, Ghana

Description: Disease prevalence varies with geographic location. This research pursues a medical geographic perspective and examines the spatial variations in disease patterns between Obuasi, a gold mining town and Asankrangwa, a non gold mining town in Ghana, West Africa. Political ecology/economy and the human ecology frameworks are used to explain the prevalence of diseases. Mining alters the environment and allows disease causing pathogens and vectors to survive more freely than in other similar environ… more
Date: August 2005
Creator: Reddy, Sumanth G.
Item Type: Refine your search to only Thesis or Dissertation
open access

Comparison of IKONOS Derived Vegetation Index and LiDAR Derived Canopy Height Model for Grassland Management.

Description: Forest encroachment is understood to be the main reason for prairie grassland decline across the United States. In Texas and Oklahoma, juniper has been highlighted as particularly opportunistic. This study assesses the usefulness of three remote sensing techniques to aid in locating the areas of juniper encroachment for the LBJ Grasslands in Decatur, Texas. An object based classification was performed in eCognition and final accuracy assessments placed the overall accuracy at 94%, a significant… more
Date: December 2009
Creator: Parker, Gary
Item Type: Refine your search to only Thesis or Dissertation
open access

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 … more
Date: August 2013
Creator: Denlinger, Emily E.
Item Type: Refine your search to only Thesis or Dissertation
open access

County Level Population Estimation Using Knowledge-Based Image Classification and Regression Models

Description: This paper presents methods and results of county-level population estimation using Landsat Thematic Mapper (TM) images of Denton County and Collin County in Texas. Landsat TM images acquired in March 2000 were classified into residential and non-residential classes using maximum likelihood classification and knowledge-based classification methods. Accuracy assessment results from the classified image produced using knowledge-based classification and traditional supervised classification (maxim… more
Date: August 2010
Creator: Nepali, Anjeev
Item Type: Refine your search to only Thesis or Dissertation
open access

Decoding the Formation of a Retail Giant: the Evolving Geography of Costco’s Store Network

Description: Although Costco operates over 580 warehouse stores throughout North America, their location strategy remains relatively unexamined in the economic geography literature. A cursory examination of Costco’s network makes it clear that the firm chooses to locate primarily in the suburbs of major cities, where income levels are somewhat higher than the national average. However, what is not clear is the extent to which other demographic and geographic factors adequately account for Costco’s store loc… more
Date: December 2015
Creator: Testa, Peter
Item Type: Refine your search to only Thesis or Dissertation
open access

The Descriptive Paleontology and Applied Ichthyoarchaeology of the Ponsipa Fauna

Description: The archaeology of the Northern Rio Grande region of New Mexico has recently received an increased amount scholarly attention. In particular, understanding past trends in demographics, agricultural productivity, violence, and social networks have been primary goals of archaeological research. Understanding patterns in animal exploitation has, however, received far less attention due to a small yet growing regional zooarchaeological database. Through the identification of animal remains from a s… more
Date: May 2015
Creator: Dombrosky, Jonathan
Item Type: Refine your search to only Thesis or Dissertation
open access

Determining the Suitability of Functional Landscapes and Wildlife Corridors Utilizing Conservation GIS Methods in Denton County, Texas.

Description: Denton County's unique cultural and natural landscape has undergone dramatic transformations during the past two centuries due to agricultural, urban and suburban processes which accelerated the loss and removal of native habitat and wildlife. This research sought out to identify the remaining natural areas which retain their natural features and support wildlife. Research methodology included fundamental principles of Conservation Planning, Geographical Information Systems, and Habitat Evaluat… more
Date: August 2007
Creator: Sales, Joshua
Item Type: Refine your search to only Thesis or Dissertation
open access

Developing a Wildlife Tracking Extension for ArcGIS

Description: Wildlife tracking is an essential task to gain better understanding of the migration pattern and use of space of the wildlife. Advances in computer technology and global positioning systems (GPS) have lowered costs, reduced processing time, and improved accuracy for tracking wild animals. In this thesis, a wildlife tracking extension is developed for ArcGIS 9.x, which allows biologists and ecologists to effectively track, visualize and analyze the movement patterns of wild animals. The extensio… more
Date: May 2009
Creator: Chen, Cai
Item Type: Refine your search to only Thesis or Dissertation
open access

Differential use of space: An analysis of the Aubrey Clovis site.

Description: The Aubrey Clovis site is one of the oldest late-Pleistocene sites in North America, dated to ~11,550 B.P., and contains two camps with a range of lithic debitage, numerous hearths, and excellent faunal preservation. Couched in rules of classification, a series of artifact distributions are analyzed with qualitative and quantitative techniques, including maps produced in a geographic information system (GIS) and tests of artifact associations using correlation statistics. Theoretical and meth… more
Date: August 2005
Creator: Witt, Benjamin A.
Item Type: Refine your search to only Thesis or Dissertation
open access

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… more
Date: December 2014
Creator: Lester, Katherine Ann
Item Type: Refine your search to only Thesis or Dissertation

Distribution and Probable Sources of Nitrate in the Seymour Aquifer, North Central Texas, USA

Description: This study utilized GIS and statistical methods to map the spatial variability of nitrate and related groundwater constituents in 30 counties above the Seymour Aquifer, analyze temporal patterns of nitrate pollution, identify probable sources of pollution, and recommend water development strategies to minimize exposure to nitrate and reduce future aquifer contamination. Nitrate concentrations in excess of 44 mg/L (US EPA limit) were commonly observed in the Seymour Aquifer region, especially i… more
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Date: May 2001
Creator: Hillin, Clifford K.
Item Type: Refine your search to only Thesis or Dissertation
open access

The Effects of Attendance at a Senior Center on the Quality of Life and Well Being of Grandparents Rearing Grandchildren.

Description: The purpose of this study was to determine the effects of attendance at a senior center on the well being and quality of life of grandparents that were rearing grandchildren. Using convenience sampling, grandparents (N=130) who were rearing grandchildren were given a self administered demographic data survey along with an attendance at a senior center questionnaire, the Quality of Life Scale, the Well Being Scale by Liang, the UCLA Loneliness Scale, the Caregiver Burden Scale, and the Role Sa… more
Date: December 2009
Creator: Rhynes, LaTrica Q.
Item Type: Refine your search to only Thesis or Dissertation
open access

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 popul… more
Date: December 2014
Creator: Jones, Jesse Jack
Item Type: Refine your search to only Thesis or Dissertation
open access

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 thesi… more
Date: May 2014
Creator: Griffith, Kereen
Item Type: Refine your search to only Thesis or Dissertation
open access

Efficiency of Nitrate and Phosphorus Removal in a Working Rain Garden

Description: Rain gardens are low impact developments designed to mitigate a suite of issues associated with urban stormwater runoff. The site for this study was a Denton City rain garden at the Denton Waste Water Treatment Plant. Nitrogen and phosphorus removal was examined in light of two overflow events comprised of partially treated wastewater from an upslope anaerobic digester pond. Nitrate removal efficiency was examined across differing dry spell intervals of 5, 8, and 12 d, displaying a moderate neg… more
Date: August 2015
Creator: Strong, Patrick
Item Type: Refine your search to only Thesis or Dissertation
open access

An environmental justice assessment of the light rail expansion in Denton County, Texas.

Description: This study analyzes the proposed passenger rail line expansion along US Interstate Highway 35 in Denton County, Texas. A multi-dimensional approach was used to investigate potential environmental justice (EJ) consequences from the expansion of the transportation corridor. This study used empirical and historical evidence to identify and prioritize sites for potential EJ concerns. Citizen participation in the decision making process was also evaluated. The findings of this research suggest that … more
Date: August 2007
Creator: Moynihan, Colleen T.
Item Type: Refine your search to only Thesis or Dissertation
open access

Estimating Buruli Ulcer Prevalence in Southwestern Ghana

Description: Mycobacterium ulcerans is sweeping across sub-Saharan Africa, but little is known about the mode of transmission and its natural reservoirs. Since the only effective treatment is excision of the infection and surrounding tissue, early diagnosis and treatment is the only way to reduce the havoc associated with Buruli ulcer. Using data from a national case search survey conducted in Ghana during 2000 and suspected risk factors this study tests the hypothesized factors and probes the challenges of… more
Date: August 2007
Creator: Denton, Curtis James
Item Type: Refine your search to only Thesis or Dissertation
open access

Evaluating Sea-Level Rise Hazards on Coastal Archaeological Sites, Trinity Bay, Texas

Description: This study uses the predictive modeling program Sea-Levels Affecting Marshes Model (SLAMM) to evaluate sea-level rise hazards, such as erosion and inundation, on coastal archaeological sites with a vertical rise of sea level of .98 meters from 2006 to 2100. In total 177 archaeological site locations were collected and georeferenced over GIS outputs maps of wetlands, erosion presence, surface elevation, and accretion. Wetlands data can provide useful information about characteristics of the wetl… more
Date: May 2018
Creator: Elliott, Patrick
Item Type: Refine your search to only Thesis or Dissertation
open access

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 diff… more
Date: August 2013
Creator: Curran, Lorna L.
Item Type: Refine your search to only Thesis or Dissertation
open access

Exceedance Frequency Analysis of Urban Stormwater Quality and Its Relation to Land Use Change, Denton, Texas

Description: Urbanization causes various environmental issues including water pollution, air pollution, and solid waste. Urbanization of watersheds has a profound influence on the quality of stormwater runoff. The quality of stormwater runoff is highly associated with land use. This study analyzed the exceedance frequency of stormwater quality in five watersheds of Denton over eleven years and also analyzed the relationship between stormwater quality and land use/cover of each watershed. The results showed … more
Date: August 2015
Creator: Shrestha, Manjul
Item Type: Refine your search to only Thesis or Dissertation
open access

The Expansion of a Retail Chain: An Analysis of Wal-Mart Locations in the United States

Description: Retail geography is an expanding field that is becoming increasingly important within academia, the business environment, and the national and global economy. The focus of this study is to provide insight and additional understanding of the site selection processes employed by Wal-Mart in the United States. The research studies Wal-Mart from a national perspective and investigates the patterns of retail store expansion across the United States from 1990 to 2005. The study employs the use of a c… more
Date: May 2011
Creator: Ostrander, Anthony P.
Item Type: Refine your search to only Thesis or Dissertation
open access

An Exploration of the Ground Water Quality of the Trinity Aquifer Using Multivariate Statistical Techniques

Description: The ground water quality of the Trinity Aquifer for wells sampled between 2000 and 2009 was examined using multivariate and spatial statistical techniques. A Kruskal-Wallis test revealed that all of the water quality parameters with the exception of nitrate vary with land use. A Spearman’s rho analysis illustrates that every water quality parameter with the exception of silica correlated with well depth. Factor analysis identified four factors contributable to hydrochemical processes, electr… more
Date: August 2011
Creator: Holland, Jennifer M.
Item Type: Refine your search to only Thesis or Dissertation
open access

FACET Simulation in the Imataca Forest Reserve, Venezuela: Permanent Plot Data and Spatial Analysis

Description: Tree diameter data from 29 years of observations in six permanent plots was used to calculate the growth rate parameter of the FACET gap model for 39 species in the Imataca forests in Venezuela. The compound topographic index was used as a measure of differential soil water conditions and was calculated using geographic information systems. Growth rate values and topographic conditions typical of hill and valley were input to FACET to simulate dynamics at the species level and by ecological and… more
Date: May 2006
Creator: Figuera, Dilcia
Item Type: Refine your search to only Thesis or Dissertation
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