Do edge effects influence wildlife distributions in a small game reserve in South Africa?
Lyall A. Blanché*1 and Victoria J. Bennett1
1Department of Environmental Science, Texas Christian University, Fort Worth, TX 76129 USA
Physical boundaries in the landscape can influence the abundance and distribution of species through edges effects, which are characterized as a behavioral response to features or boundaries, creating an area of avoidance known as edge habitat. The implication is a reduction in the amount of available habitat for an individual and/or its population. Studies have shown that anthropogenic features, such as roads and fences, can cause edge effects. Thus, should we be considering the consequences of anthropogenic edge effects when managing wildlife populations in game reserves? To address this, we used Global Positioning System point locations collected from 2004-2020 on cheetah, elephant, leopard, and lion in Amakhala Game Reserve, a 66 km2 fenced reserve in the Eastern Cape of South Africa. This reserve is bordered by a national highway and bisected by a public road. We used regression analysis to determine any relationship between the proportion of locations within 5 m increments and 1) the national highway, 2) public road, 3) boundary fence, 4) a river on the reserve, and 5) control sections of the reserve. Our analysis revealed a significant positive correlation between elephant locations and distance from the national highway, with elephants avoiding a 600 m wide section of the reserve next to the highway. Our study highlights the importance of identifying potential edge effects to better inform the management of small reserves.

Globally, floods are the most common natural disasters, imposing stress on communities through infrastructure damage, financial costs, public health, and environmental damage. Serving as a major threat to the city of Houston, Texas (TX), this metropolitan area has an extensive flooding history. This project aims to develop a flood risk map for the White Oak Bayou Watershed, found in the North-East region of Houston. Using existing literature, the flood risk susceptibility for this study is based on seven factors: elevation, slope, flow accumulation, hydrologic classifications of soil, land use, rainfall, and distance to river networks. Using methods from existing literature, each individual factor was classified into 5 risk levels, based on their characteristics that make an area more prone to flooding. By using the weighted overlay analysis tool, the individual factors were weighted based on their contribution to overall flooding. The results show majority of the watershed is classified as medium risk, including areas of high and low flooding vulnerability. The high risk areas surround the river networks and increase risk towards the watershed’s discharge point, located in close proximity to the downtown area of Houston.

Urbanization imposes threats to the quantity and quality of stormwater, driving communities to identify water management strategies that aid in sustainable development. As demand for urbanization increases, green infrastructure (GI) practices can be implemented as mitigation strategies, allowing for sustainable growth in communities with limited harm to water resources. This project will model the Village Creek (VC) watershed, a semi-urban watershed in north-central Texas, using the Soil Water Assessment Tool (SWAT) to estimate the effects of GI on water quantity and quality. Topographic, land cover, and soil data along with historical water quality and climate data drove the model, then GI designs influenced the transport of streamflow, bacteria, sediments, and nutrients. We expect the results to quantify changes in water quantity and quality from GI implementation and highlight the effectiveness of GI for the watershed. This research provides VCLA watershed managers and stakeholders information on environmentally sound and sustainable watershed protection planning.

The Louisiana coast is prone to power tropical storm systems, known as hurricanes, which commonly cause significant damage to the environment and financial infrastructure in coastal states, such as Louisiana. Using landsat data acquired from the USGS, determining land cover degradation from seasonal low-pressure storms that span different decades can be made possible. This GIS-based study also takes into account elevation models (DEMs) to provide an accurate portrayal of how coastal vegetation influences the impact of these storms, as well as how storm intensity influences the morphology of coastlines.

Hawaii’s most active volcano, Kilauea, poses many threats to the surrounding infrastructure of the Big Island. Surface deformation from eruptions and underground magma tunnels have produced a growing lava lake within the Eastern Rift Zone, located on the Southeast tip of the island, since 2018. Using remote sensing techniques and GIS, I will use recent data collected from Kilauea’s eruptions and Halema’uma’u lava lake to create a volcanic hazards map of the region. A volcanic hazards map gives us insight to where the safest place are to inhabit on the surface of the island.

There are many major geologic units that outcrop in various regions of the Dallas-Fort Worth metroplex. A major unit that will be discussed in the current study is the Eagleford Shale. Previous studies have generated geologic maps that illustrate where this unit crops-out within the study region. The goal of this study is to create a modern geologic hazard zonation map of the Dallas-Fort Worth metroplex focusing on areas where the Eagleford crops-out. On this map, I will include the spatial distribution of discovered Eagleford outcrop locations and will integrate photographs that illustrate the stratigraphy of this formations using GIS.
Subsequently, I will use the map to calculate the area of all Eagleford surficial deposits within the study region. This shale is a mudrock that is primarily made up of soft-sediments and clays and can pose a geological hazard where it reaches the surface due to shrinking and swelling. This can cause major foundation issues to infrastructure that is built on this unit. Therefore, this map can be used for the purpose of taking precautionary measures when planning the construction of new buildings and road networks within the Dallas-Fort Worth metroplex.

The Lower Cenomanian Maness Shale is an argillaceous mudrock that occurs between the Buda Limestone and Woodbine Sandstone in the East Texas Field, and was originally placed within the Washita Group based on its biostratigraphy. It regionally extends throughout the East Texas Basin in tandem with the overlying Woodbine Group and displays considerable thickness and facies variations. The Maness interval is significant because previous studies indicate that it may be a hydrocarbon source rock.
Although this mudrock has been studied for several decades, the sediment source of the Maness remains in question. Prior studies have indicated that the sediment comprising the Maness could have come from multiple sources, one of them being the southern side of the Sabine Uplift. In the current study, I will correlate well logs through the south side of the Sabine Uplift from Polk and Tyler counties through Rusk county. I will then generate an isopach map of the study area and will compare thickness trends to those shown on the composite isopach map constructed by English (2020). Lastly, I will examine a core from Tyler or Polk counties that could potentially reveal clastic sandstones occurring within the Maness. The findings will be used to test my hypothesis that the Maness Shale is sourced from the southern portion of the Sabine Uplift.

Hardness, defined as resistance to surface deformation, is an intrinsic property of all materials including sedimentary rocks. The variables responsible for a sedimentary rock’s hardness are not completely understood. By understanding which variables control hardness, we may gain a better understanding of related rock strength. Rock strength, defined as a rock’s resistance to plastic deformation under loading, is an important parameter for many industries such as mining, civil engineering, and hydrocarbon exploration.
Numerous tests such as triaxial tests or uniaxial tests are used to quantify rock strength, but are often expensive, time consuming, or require substantial investment in laboratory setup. To circumvent these issues, other devices have been employed to determine rock strength. For example, the Proceq Equotip Bambino micro-rebound hammer (Bambino) has been used for decades to test the hardness of materials such as concrete, steel, and ceramics. These hardness values have been used to determine material strength. Selected studies on rocks empirically correlate between Bambino-derived hardness value (called Leeb hardness) and uniaxial compressive strength (UCS). However, significant scatter in the data suggest that certain intrinsic (e.g., density, bulk mineralogy, etc.) or extrinsic factors (e.g., sample volume, surface the sample rests on) need to be considered for a better correlation.
In this study, I examined the relations between Leeb hardness and UCS values, while examining lithologic variations and other properties such as bulk mineralogy, water loss, volume, density, and effective porosity. I found that bulk mineralogy, density, effective porosity, and water content correlated with a sample’s mechanical hardness. Also, a sample’s UCS is related to its density, effective porosity, and mechanical hardness. Ultimately, these data validated previous studies and shed new insight on the controlling properties of a rock’s hardness and strength.

The Kittanning coal seams run underneath West Virginia, southeast Ohio, and southwestern Pennsylvania. It is part of a sequence that underlies the Freeport and Pittsburgh coals. All three seams are of Pennsylvanian Age. Of the seams in the Northern Appalachian Basin, the Kittanning has the among the largest extents. For that reason, it will most likely be the greatest influencer on population patterns. Since the early 1800s, the people of the region mined and used coal to produce their energy. As such, it is the goal of this research is to determine the spatial relationship between the economic coal sources and population centers.

Landslides may be caused naturally or triggered by human activities and have enormous societal and economic impacts. Detecting and mapping landslides through the generation of landslide susceptibility maps (LSM) and understanding the factors that trigger these processes will be helpful in land use planning and risk assessments. Moreover, it will also assist landslide mitigation efforts by controlling anthropogenic-led processes that induce landslides. This study deals with the analysis to identify slow-moving landslides in Travis County, Texas. It combines geographic information systems(GIS) and remote sensing datasets and techniques to generate an LSM of the study area and identify ground displacements. Remote sensing data provide key information about the topography and land uses, combined with controlling factors for a landslide occurrence such as slope, geology/soil and geological structures, and vegetation/land uses to perform an empirical approximation to map and assess landslide susceptibility. Once the susceptible areas are identified, analysis for ground displacement is applied using a Synthetic Aperture Radar Interferometric (InSAR) technique referred to as the Small Baseline Subset (SBAS) and field-based multitemporal Real-Time Kinematic (RTK) GPS measurements.

The Ouachita Trough is a basin that formed along a passive margin on the southern border of Laurentia caused by the Precambrian–Cambrian rifting of Rodinia and the opening of the Iapetus Ocean. The collision of Laurentia and Gondwana and the closing of the Iapetus Ocean thrust sediments from the Ouachita Trough onto the southern portion of the North American craton to form the Ouachita Mountains. The Ouachita Trough transitioned from a sediment-starved basin into an area of rapid sediment accumulation during the Mississippian. The Stanley Group, of interest in this study, was deposited prior to the collision of the encroaching Gondwana continent to the south. Although there have been many previous studies aiming to determine the provenance history of the Stanley Group, the results are inconclusive. In this study, nine samples from turbidite deposits of the Stanley Group were processed using both U-Pb age dating and core rim analysis. Laurentia and Gondwana have similar aged terranes that are difficult to differentiate. Using core rim analysis allowed us to date both the age of the core and rim of individual zircon grains. We were then able to correlate zircon grains of similar ages to their sources. By analyzing a large area of the Ouachita Mountains, this study shows that the Stanley Group consists of sediments sourced from both Laurentia and Gondwana terranes to the south.

The Urban Heat Island (UHI) effect is characterized by the differential heating of densely populated urban areas in comparison to surrounding areas. Increased temperatures caused by buildings and other man-made infrastructure have a wide range of human and ecological impacts. One emerging methodology to combat UHI effects is the implementation of urban green spaces and trees. Trees can provide two main functions that aid in cooling; shade from the sun provided by the canopy and cooling through the process of evapotranspiration. This project aims to identify which species of tree best suits the ecoregion of Fort Worth, how much feasible green space Fort Worth can provide, and project the cooling the green spaces could provide if they are planted with trees.

The use of Interferometric Synthetic Aperture Radar (InSAR) to analyze the deformation of the Earth's surface has become an increasingly important tool for monitoring earthquakes, volcanic activity, landslides, and land subsidence. This process works by calculating the phase differences of radar signals reflected from the Earth's surface over a period of time. If the land has uplifted or subsided, the phase of the two radar signals will interfere. The image this phase difference produces is known as an interferogram, which shows the ground-surface displacement of the target area across the two time periods. This technique has been used extensively to survey Mexico City, which has been an area of concern since the beginning of the 20th century due to its dramatic rate of ground subsidence.

Nanomaterials are the new technologies reforming industrial activities. They are used to improve energy efficiency and storage, to cheaply store and process information in every internet server and personal computer, to facilitate bio-imaging and drug delivery, and in environmental remediation. These materials’ nanometric dimension, 1/100000 the width of a human hair, allows them to have novel characteristics such as strength, electrical resistivity, and conductivity, and optical absorption compared to the same materials in bigger sizes. Due to their widespread and incorporation into consumer products, it is important to understand their interactions with other elements in the environment. I used flow experiments, to understand the effects of the core and terminal groups chemistries of 3 sets of nanomaterials on their interaction with ferrihydrite, a very common and reactive mineral in the environment. The nanomaterials used in this study, namely Graphene Quantum Dot (GQD), PAMAM G4-OH, and PAMAM G3.5-COOH, have comparable sizes, 6nm, 4.5 nm, and 3.5 nm, respectively. When the experiments were conducted under acidic and circumneutral pH, the quantities of GQD and PAMAM G4-OH sorbed were equivalent and less than the quantity of PAMAM G3.5-COOH sorbed. In my presentation, I will go over the quantities and kinetics results from the interactions of the 3 sets of nanomaterials onto ferrihydrite over environmentally significant pH values (range 3-10).

Land surface temperature is a major factor used in the assessment and understanding of several processes including global climate, hydrological, geo-/biophysical, urban land use/land cover (Avdan and Jovanovska, 2016). Since the Soviet Union launched the world's first artificial satellite, Sputnik 1, in 1957 there have been about 8,900 satellites from more than 40 countries launched in space that have opened possibilities to understand the earth using remote sensing. Specifically, LANDSAT 8’s thermal infrared sensor Band 10 data has been successfully used to map land surface temperature. The specific algorithm used to derive land surface temperature from LANDSAT 8’s thermal infrared sensor Band 10 showed standard deviations of 2.4°C and 2.7°C on the first trial and second trial respectively (Avdan and Jovanovska, 2016). In my project, I used land surface temperature in addition to secondary data (geologic features, volcanoes, faults, change in cities' extents) to locate and deduce the potential geothermal plays in Rwanda. I also compared the potential geothermal plays obtained using remote sensing to those obtained using ground measurements to assess how accurate remote sensing tools are in determining geothermal plays.

Mount Rainier is a stratovolcano within the Cascade Arc situated southeast of the cities of Seattle and Tacoma. This region of Washington has undergone substantial population growth while being situated in the shadow of a large stratovolcano. Historically lahar flows, volcanoclastic debris flows, from the volcano have reached as far as Tacoma and could still pose a risk to Seattle and other smaller communities. Seismicity and annual precipitation are large contributors into predicting an eruption event as well as eruption severity. Using ArcGIS Pro and implementing various types of data including historic lahar deposit extent, population growth, seismic activity, and other contributions that can peer into a future volcanic eruption, it can be possible to assess the volcanic hazard Mount Rainier poses on nearby communities.

Treatment of complex conditions, such as cancer, has been substantially advanced by a field of molecular therapeutics. However, many of these therapies are limited by the dose toxicity and lack the predictive power of tomography-guided approaches. Nanomaterial platforms can address these drawbacks, safely delivering therapeutics, concomitantly imaging their delivery pathways, and presenting sites for targeting agent attachment. Graphene quantum dots (GQDs) possess physical properties that are critical for biomedical applications, including small size (3-5 nm), high quantum yield, low cytotoxicity, and pH-dependent fluorescence emission. Thus, our work utilizes nitrogen-doped GQDs as a basis for targeted image-guided cancer therapy. GQDs serve as an emissive platform for covalent attachment of a targeting agent (hyaluronic acid (HA) targeted to the CD44 receptors on several cancer cell types) and oxidative stress-based cancer therapeutic (ferrocene (Fc)). The synthesized multifunctional formulation is characterized and its efficacy evaluated in vitro. Elemental mapping indicates that the purified from reactants synthetic product has an average iron content of 0.64 atomic percent, suggesting the successful attachment of the therapeutic, while FFT analysis of TEM images confirms the crystalline structure of the GQDs. Although GQDs alone yield no cytotoxicity as quantified via the MTT assay up to the maximum imaging concentrations of 1 mg/mL, the Fc-HA-GQD formulation exhibits a higher cytotoxic response in the cancer cells (HeLa) targeted by the HA as opposed to healthy ones (HEK-293) that do not overexpress CD44, suggesting cancer-selective targeted treatment. As Fc induces oxidative stress that is less mitigated in cancer cells, we expect it to also contribute to the observed cancer-selective treatment response. As a result, we propose Fc-HA-GQD formulation as a multifunctional targeted delivery, imaging, and cancer-specific treatment agent further to be studied in vivo.

Fluorescence has proved itself to be a useful tool in a wide variety of fields, ranging from environmental sensing to biomedical diagnostics. In this study, we propose to utilize a fluorescence-based technique called Surface Plasmon Coupled Emission (SPCE) to monitor molecular binding and to detect low concentrations of physiological markers (e.g. biomarkers present in the human body as a result of a disease). SPCE is characterized by directional emission that allows for a superior sensitivity and selectivity for detection. The development of an SPCE-based detection platform will allow for simple, fast and sensitive detection in a compact configuration that can be relatively easily implemented in the field or in primary care offices. Surface plasmon induced fluorescence at the interface of a thin metal layer (e.g. 50 nm of silver or gold) and a dielectric (e.g. glass) allows for highly enhanced excitation of fluorophores deposited on top of the metal film and very efficient detection due to the directional nature of this emission. As a result, we expect highly improved detection sensitivity compared to other fluorescence detection methods or other surface detection methods such as surface plasmon attenuated reflection (SPR).

Tryptophan is one of the few amino acids that is intrinsically photoluminescent. This is because its side chain consists of indole. Indole’s photoluminescence has both fluorescence (emits for nanoseconds) and phosphorescence (emits for microseconds). Fluorescence emission comes from a singlet to singlet transition, while phosphorescence from a forbidden triplet to singlet transition. Taking advantage of tryptophan’s intrinsic emission, we can use it as a label-free probe for protein dynamics. For some of these dynamics, such as myosin binding to actin, the fluorescence lifetime of nanoseconds is too fast to monitor changes. The phosphorescence lifetime is much better suited to monitor these changes of large biomolecule interactions. Before any binding studies are developed, we have characterized the basic properties of indole’s phosphorescent properties. We began by embedding indole (as well as 5 – bromoindole) in a polymer matrix (PVA) to immobilize and thus increase the phosphorescence at room temperature. We discovered that using a longer wavelength of excitation (405 nm instead of 290 nm) we excite directly from the singlet state to the triplet state of indole, a typically forbidden process. This populates the triplet state without any transitions to the singlet state. This allows the polarization of phosphorescence emission to be preserved, and anisotropy measurements can be used to monitor biomolecular processes.

Driving through the disk of the Milky Way galaxy resides a gaseous stream that is associated with the Magellanic Clouds galaxies called the Leading Arm. The Milky Way will capture this stream of gas torn from the Magellanic Clouds to supply our galaxy with material to make future stars and planets. We study this gas cloud using Hubble Space Telescope observations to determine the complex's physical properties, such as the motion, temperature, ionization fraction, density, and total mass of the gas. With this observational data, we run computer simulations created with the Cloudy software to constrain these properties better. Measured ionization ratios and column densities from the Hubble observations act as inputs for our models. Studying these properties will better depict the processes that affect the stream of gas falling onto our galaxy's disk.

The first stars in the Universe, Pop III stars, formed out of the primordial hydrogen and helium sometime during the first billion years of cosmic time. Their formation ended the Cosmic Dark Ages. Despite their critical role in kick starting the formation of all “heavy” elements, including the carbon in our bodies and the oxygen we breathe, we do not know how massive these first stars were, and when and how the era of the first stars ended. While Pop III stars are too faint for a direct detection, their deaths are potentially visible by James Webb Space Telescope (JWST): a subset of Pop III stars end their lives as Pair Instability Supernova (PISN), explosions in which the entire star blows itself apart [and fling], flinging “heavy” elements into the Universe. However, what will the detection, or non-detection of a PISN tell us about the nature of the first stars? To answer this question, we need to fully explore the range of mass distribution of Population III stars to determine the physics which governed Cosmic Dawn. We present results from a new model which treats the distribution of Population III masses as free parameters. In this work, we attempt to determine whether the masses of the first stars can be constrained given various possible observational results from JWST.

The debate surrounding the fundamental mechanisms behind the antibacterial action of ZnO has led to increased interest in the impact of surface interactions on this behavior. In this regard, the impact of the different polar vs. non-polar surfaces of the anisotropic wurtzite ZnO crystal lattice are of particular interest. For this purpose, we developed a hydrothermal growth method that allows us to produce microscale ZnO crystals of tunable morphology with varying relative abundances of surfaces with desired polarities. The micron scale of the obtained crystals is critical to avoid internalization by bacteria as a means to isolate effects related to surface interactions. Simultaneously, at this scale, the high surface-to-volume ratio leads surface interactions to dominate, resulting in surface and near-surface defect states to become highly influential on this behavior. Photoluminescence is a powerful, non-destructive tool for characterizing the electronic structure of a material allowing us to observe the nature of the defect states present in our samples. Photoluminescence measurements were made over a range of temperatures for both predominantly polar and non-polar morphologies. Results of these investigations have allowed us to describe the electronic structure of these microcrystals. We show that both the nature and density of surface defects states are significantly impacted by the relative abundance of polar and non-polar surfaces.

Graphene quantum dots (GQDs) are unique derivatives of graphene that show promise in multiple biomedical applications as biosensors, bioimaging agents, and drug/gene delivery vehicles. Their ease in functionalization, biocompatibility, and intrinsic fluorescence enable those modalities. However, GQDs lack deep tissue magnetic resonance imaging (MRI) capabilities desirable for diagnostics. Considering that the drawbacks of MRI contrast agent toxicity are still poorly addressed, we develop novel Mn2+ or Gd3+ doped nitrogen-containing graphene quantum dots (NGQDs) to equip the GQDs with MRI capabilities and at the same time render contrast agents biocompatible. Water-soluble biocompatible Mn-NGQDs and Gd-NGQDs synthesized via single-step microwave-assisted scalable hydrothermal reaction enable dual MRI and fluorescence modalities. These quasi-spherical 3.9-6.6 nm average-sized structures possess highly crystalline graphitic lattice structure with 0.24 and 0.53 atomic % for Mn2+ and Gd3+ doping. This structure ensures high in vitro biocompatibility of up to 1.3 mg ml-1 and 1.5 mg ml-1 for Mn-NGQDs and Gd-NGQDs, respectively, and effective internalization in HEK-293 cells traced by intrinsic NGQD fluorescence. As MRI contrast agents with considerably low Gd and Mn content, Mn-NGQDs exhibit substantial transverse/longitudinal relaxivity (r 2/r 1) ratios of 11.190, showing potential as dual-mode longitudinal or transverse relaxation time (T 1 or T 2) contrast agents, while Gd-NGQDs possess r 2/r 1 of 1.148 with high r 1 of 9.546 mM-1 s-1 compared to commercial contrast agents, suggesting their potential as T1 contrast agents. Compared to other nanoplatforms, these novel Mn2+ and Gd3+ doped NGQDs not only provide scalable biocompatible alternatives as T1/T2 and T1 contrast agents but also enable in vitro intrinsic fluorescence imaging.

Star clusters have been incredibly useful tools for studying the history of the Milky Way because they allow us to determine relative ages based on their chemical abundances. However, most stars are not in clusters, and current methods used to determine ages for individual stars produce substantial uncertainties. A new age method enabled by the precise photometry data of the NASA Kepler satellite is asteroseismology. Asteroseismology allows us to probe the internal structure of stars that are affected by age and composition. This research aims to calibrate the relationships between age, chemical abundances, and asteroseismology by analyzing data of stars in star clusters, which provide an independent measure of the stars' ages. This project aims to expand upon the currently used age and chemical abundance range and triple the number of open star clusters used to calibrate the asteroseismic age-mass-chemical abundance relation. We have combined asteroseismology data for stars in clusters within the Kepler 2 campaign fields with uniformly determined follow-up spectroscopic abundances from observations from the MMT.

Micro- and nano-scale ZnO particles are known to inhibit the growth of bacteria. Though this phenomenon has been vigorously studied, the fundamental mechanisms driving this action remain unknown. Mechanisms proposed by other studies include: the production of reactive oxide species, release of zinc ions, damage to the cell wall due to interactions with ZnO surfaces, and the inhibition of enzymes. ZnO surface defects serve as reaction sites for the processes driving these bactericidal interactions. Additionally, through MIC assays, we found antibacterial action of microparticles to be comparable to that of nanoscale particles. This confirms that antibacterial action of ZnO is rooted in surface-surface interactions between bacteria and ZnO. Therefore, our studies focus on ZnO surface charge dynamics and surface defects using surface photovoltage methods. Surface photovoltage experiments were performed on commercial grade ZnO nanoparticles and hydrothermally grown ZnO microcrystals in conjunction with antibacterial assays to elucidate the surface and near-surface charge dynamics associated with antibacterial processes of the ZnO surfaces.