Physical Sciences and Mathematics Commons^™

The Paleoecology Of High-Elevation Bison In The Greater Yellowstone Ecosystem And Implications For Modern Bison Conservation, Darian Bouvier

Electronic Theses and Dissertations

The national mammal of the United States, the American Bison (Bison bison) was once nearly extinct. Populations have recovered to the degree that thousands roam the Great Plains today. Due to their large numbers and body size, this species has an oversized impact on the ecological communities where it lives and is considered a keystone herbivore in modern North American grasslands. This study explores the detailed, seasonally resolved, paleoecology of seven bison from the Greater Yellowstone Ecosystem during the Late Holocene through stable isotope analyses and species niche modeling. Isotopic analyses of δ¹³C, δ¹⁵N, …

Optimization Of Quantum Circuits Using Spin Bus Multiqubit Gates For Quantum Dots, Miguel Gonzalo Rodriguez

Open Access Theses & Dissertations

The current conventional method for designing quantum circuits is to employ a number of single- and two-qubit gates, which often necessitate a lengthy sequence, imposing severe constraints on quantum coherence and quantum circuit complexity. Coupling multiple spin qubits to a common spin chain can result in a generically multiqubit gate. It is demonstrated that the multiqubit gate can substantially reduce the depth of quantum circuits and establish multiqubit entanglement considerably more quickly.

Variations In Copper Form Exposure Differentially Modulate Zea Mays (Corn) Physiological Responses, Carolina Valdes Bracamontes

Open Access Theses & Dissertations

In the present study, Zea mays seedlings grown under nano Cu(OH)2 (nCu), bulk Cu(OH)2 (bCu), and ionic CuSO4 (iCu) compound exposure were harvested after six days. The nutritional profile was determined to be significantly disrupted in the roots by 1000 ppm bCu treatment, resulting in a 58.7% reduction in potassium compared to the control. In the shoots, a significant decrease of manganese was observed for 10 and 1000 ppm iCu treatments with 55.7% and 64.2% reductions, respectively. The overall protein content and catalase (CAT) enzymatic activity, however, remained unaffected in either roots or shoots, while an absence of polyphenol oxidase …

An Unmanned Surface Vehicle: Autonomous Sensor Integration System For Bathymetric Surveys, Fernando Sotelo Torres

Open Access Theses & Dissertations

Unmanned Surface Vehicles (USVs) have been applied to earth sciences, with only a few studies conducted in water environments, as these systems provide autonomous measurement capabilities and transferability to other environmental settings. In this thesis, a reliable, yet economical, USV has been developed for bathymetric surveying of lakes. The system combines an autonomous navigation framework, environmental sensors and a multibeam echosounder to collect submerged topography, temperature, windspeed and monitor the vehicle status during prescribed path planning missions.

The main objective of this study is to provide a methodological framework to build a USV, with independent decision-making, efficient control, and long-range …

Exposure Of Candyland Red Tomatoes (¬Solanum Lycopersicum L.) To Various Metal Oxide Nanomaterials: Full Life Cycle And Assessment Of Fruit Quality, Jesus Manuel Cantu

Open Access Theses & Dissertations

The use of nanotechnology in agriculture has attained high interest to enhance crop production due to their unique properties. Moreover, metal oxide nanomaterials can potentially supplement nutrients, enhance plant growth, and crop production. When investigating fruits' nutritional quality, carbohydrates and phytonutrients (bioactive compounds) play important roles. Therefore, it is important to understand how nanomaterials will affect the quality of tomato fruits. In this dissertation, various metal oxides were synthesized and applied to Candyland Red tomato seedlings to assess the plant growth and tomato production. In the first investigation, Candyland Red tomatoes (Solanum lycopersicum) were exposed to synthesized pristine CuO and …

Water Sourcing Strategies Of Desert Vegetation In Varying Soil Textures With Vegetation Competition: A Stable Isotope Analysis, Martha Elizabeth Gardea

Open Access Theses & Dissertations

Recent studies have suggested an ecohydrological separation of water exists in the northern Chihuahuan Desert, where vegetation types, rainfall regimes, and location in the terrain seem to determine the type of water (e.g. isotopically depleted or enriched in 18O and 2H) plants are able to source and use throughout their growing cycle. That work found evidence of creosote (Larrea tridentata) and mesquite (Prosopis glandulosa) using tightly bound soil water at both a site on an ephemeral channel and a site in higher elevated flat area because the isotopic signature of plant water at the beginning of the study did not …

Synthesis, Characterization, And Reactivity Studies Of Highly Reduced Early-Metal Complexes Supported By Imidazolin-2-Iminato Ligands, Maria Alejandra Gomez Torres

Open Access Theses & Dissertations

Our group has shown that reduction of titanium complexes supported by the sterically encumbering N-donor ligands 1,3â??bis(Dipp)imidazolinâ??2â??iminato (ImDippNâ??) and ketimine guanidinate (ketGuan = [(tBuC=N)C(NDipp)2]-) gives access to electron rich platforms featuring a metal coordinated, reduced, dearomatized arene substituent, which act as an electronic reservoir capable of facilitating multi-electron transfer chemistry driven by the rearomatization driving force. For instance, the arene-masked Ti(II) synthon (DippketGuan)(η6-ImDippN)Ti (Dipp = 2,6-iPr2C6H3) (TiDipp) is a versatile and potent one- and two-electron reductant capable of distinctive late-metal type reactivity such as transfer hydrogenation and catalytic olefin hydrogenation. Interestingly, TiDipp can mediate the reversible cleavage of thiophene and, …

Chihuahuan Desert Rock Pool Community Assemblages: Patterns Of Taxonomic Diversity, Joseph Lee Mcdaniel

Open Access Theses & Dissertations

As climate change continues to become more prevalent, increasing temperatures and altering precipitation patterns will disrupt the environmental balance of ecosystems and spark the imminent threat of a 6th mass extinction event. Many researchers believe this has already begun, as losses for numerous taxonomic clades have been well documented; however, the loss of invertebrates is still unknown and may be much more severe than those of other animal clades. A significant factor contributing to the shortfall of invertebrate biodiversity loss is rooted in the lack of understanding of the diversity and distribution of these animals. There is still much to …

Pressure-Induced Phase Transition And Electronic Structure Changes In Equiatomic Fev, Homero Reyes Pulido

Open Access Theses & Dissertations

Classical molecular dynamics methods can accurately describe a broad set of many-atomssystems. Although more economical, the results given by this framework lack the precision capable of density functional theory (DFT). Therefore, the structural stability of the B2 phase of a body-centered-cubic iron-vanadium (FeV) alloy using DFT on the electronic structure level is analyzed to verify and further explain classical results obtained by our group in this same alloy. Using Quantum Espresso and Phonopy for the computational simulations, the plotted band structure, electronic density of states (eDOS), phonon dispersions, charge density, and Fermi surfaces for various compressed unit cells are presented. …

A Computationally Efficient Wald Test In M-Estimation, Denisse Urenda Castañeda

Open Access Theses & Dissertations

Under the maximum likelihood framework, three asymptotic overall tests have been well developed in generalized linear models (GLM) for testing the single null hypothesis H0 : θ = θ0, namely, the Wald test, Likelihood Ratio Test (LRT) and Score test also known as the Lagrange Multiplier test (LM). Modified versions of Wald, LR and LM tests can also be found for testing the significance of a portion of the parameter θ, i.e., if θ = (θ T 1 , θ T 2 ) T it is of interest to test H0 : θ2 = 0. However, with the constant increase …

Biological Interaction Of Mn-Based Nanomaterials With Capsicum Annuum L. Under Salinity Stress, Yuqing Ye

Open Access Theses & Dissertations

The foliar application of nanomaterials as a method to overcome abiotic stress is relatively new compared to their use as fertilizers or pesticides in agricultural practice. It is also vital to understand the interface between leaf and nanomaterials, as nanomaterials might translocate into crop edible tissues, thus, causing potential toxicity in living beings during food consumption. In this dissertation, salt-stressed Capsicum annuum L was exposed to manganese (Mn) -based nanomaterials (Mn2O3 nanoparticles (MnNPs) and graphene quantum dots doped with Mn (GQD-Mn)) at different stages (seed germination and full life cycle). The dissertation focuses on investigating the mechanism of how Mn-based …

Effects Of Excessive Soil Phosphorus Accumulation On Loblolly Pine (Pinus Taeda L.) Seedlings, Hannah C. Bays

Electronic Theses and Dissertations

Many landowners in East Texas apply poultry litter to pastures as a source of nitrogen (N) for forage crops. After many years of repeated poultry litter application, soils can accumulate extremely high extractable phosphorus (P) concentrations, sometimes over 1000 mg kg^-1 of plant available P. Landowners report the conversion of these pastures to loblolly pine (Pinus taeda L.) plantations is often problematic, with poor seedling survival and abnormal tree growth. This study was conducted to assess the effects of excessive soil phosphorus on loblolly pine seedlings. An outdoor pot study was conducted using bare root seedlings and triple …

Deep Learning For Detecting Trees In The Urban Environment From Lidar, Julian R. Rice

Master's Theses

Cataloguing and classifying trees in the urban environment is a crucial step in urban and environmental planning. However, manual collection and maintenance of this data is expensive and time-consuming. Algorithmic approaches that rely on remote sensing data have been developed for tree detection in forests, though they generally struggle in the more varied urban environment. This work proposes a novel method for the detection of trees in the urban environment that applies deep learning to remote sensing data. Specifically, we train a PointNet-based neural network to predict tree locations directly from LIDAR data augmented with multi-spectral imaging. We compare this …

A Climate Of Confessionalization: Famine And Difference In The Late Ottoman Empire, Matthew Ghazarian

Environmental Science and Policy: Faculty Publications

After the 1877–78 Russo-Ottoman War, the Ottoman Empire saw the rise of ethnic and sectarian clashes in Anatolia, the Balkans, and elsewhere, and the task of explaining that rise remains unfinished. Many have examined the intellectual formations of ethnic and sectarian solidarities after 1878, but the availability of new ideas cannot alone account for their widespread uptake. Why after 1878 did ordinary people respond more to calls upon ethnic and sectarian solidarity? Drawing on sources surrounding the 1879 famine in the Ottoman East, this article steps away from imperial metropoles to examine overlapping environmental, financial, and technological disjunctures. Adopting the …

Design And Fabrication Of An Apparatus For Tao High-Resolution Laser Spectroscopy, Timothy Chung

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this study, an apparatus for the high-resolution laser spectroscopy of molecules is designed and constructed. The apparatus is used to identify TaO transitions, but may be used for any other molecular species in the future. It will also later be used for experiments such as quantum logic spectroscopy, which are enabled by attachable chambers that can be supplied with molecules from the apparatus. Several considerations are made to improve the quality and longevity of the apparatus such as regulating the rovibrational states of the produced molecules, optimizing the linewidth of the ionization lasers, reducing noise from sources such as …

Directed Acyclic Graph-Based Neural Networks For Tunable Low-Power Computer Vision, Abhinav Goel, Caleb Tung, Nick Eliopoulos, Xiao Hu, George K. Thiruvathukal, James C. Davis, Yung-Hisang Lu

Computer Science: Faculty Publications and Other Works

Processing visual data on mobile devices has many applications, e.g., emergency response and tracking. State-of-the-art computer vision techniques rely on large Deep Neural Networks (DNNs) that are usually too power-hungry to be deployed on resource-constrained edge devices. Many techniques improve DNN efficiency of DNNs by compromising accuracy. However, the accuracy and efficiency of these techniques cannot be adapted for diverse edge applications with different hardware constraints and accuracy requirements. This paper demonstrates that a recent, efficient tree-based DNN architecture, called the hierarchical DNN, can be converted into a Directed Acyclic Graph-based (DAG) architecture to provide tunable accuracy-efficiency tradeoff options. We …

Interrogation Of Social Justice Contexts In Mathematical Modeling: The Use Of Simulations Of Practice In The Mathematical Preparation Of Teachers, Cynthia Oropesa Anhalt, Ricardo Cortez, Brynja Kohler, Will Tidwell

Mathematics and Statistics Faculty Publications

Research in prospective teachers’ development of mathematical modeling knowledge for teaching is gaining momentum. The Mathematics of Doing, Understanding, Learning, and Educating for Secondary Students [MODULE(S2)]* project developed a curriculum in modeling for teacher education that includes simulations of practice, in which prospective teachers reflect on and plan a discussion around student thinking, their models, and the contextualization of their results. We present an analysis of prospective teachers’ modeling work on the decreasing area of Indigenous reservation land in the U.S., and a simulation of practice which explores different methods for finding the area of land in connection to …

Using Teacher Noticing And Video-Mediated Professional Learning To Develop Preservice Teachers’ Knowledge For Teaching The Derivative, Alfred M. Limbere

Theses, Dissertations and Culminating Projects

This study investigated how problem-solving videos can be used in video-mediated professional learning to support secondary preservice mathematics teachers (PMTs) in developing teacher knowledge for noticing student thinking in the context of the derivative concept in calculus. A model of the trajectory of PMTs’ noticing was constructed as six PMTs viewed and analyzed videos of students’ problem solving. At the same time, the nature of video-mediated interactions that were found to be productive in supporting this knowledge development was examined. A design experiment was used as the research methodology. Data was collected from video recordings of eight semi-structured teaching episodes …

Solving The Challenges Of Concept Drift In Data Stream Classification., Hanqing Hu

Electronic Theses and Dissertations

The rise of network connected devices and applications leads to a significant increase in the volume of data that are continuously generated overtime time, called data streams. In real world applications, storing the entirety of a data stream for analyzing later is often not practical, due to the data stream’s potentially infinite volume. Data stream mining techniques and frameworks are therefore created to analyze streaming data as they arrive. However, compared to traditional data mining techniques, challenges unique to data stream mining also emerge, due to the high arrival rate of data streams and their dynamic nature. In this dissertation, …

Search For A Dark Leptophilic Scalar Produced In Association With Taupair In Electron-Positron Annihilation At Center-Of-Mass Energies Near 10.58 Gev., Diptaparna Biswas

Electronic Theses and Dissertations

Dark matter is believed to be a form of matter which seemingly accounts for approximately 85% of the matter in the universe and about 27% of its total mass–energy density. It doesn't participate in electromagnetic interaction, i.e. doesn't interact with light. Consequently, we cannot see it using optical or radio telescope and hence the name dark matter. However, it participates in gravitational interaction, and we hypothesize its existence based on a variety of astrophysical observations, including gravitational effects, that cannot be explained by the accepted theories of gravity unless we account for more matter than can be perceived through electromagnetic …

Evaluation Of Factors That Contribute To Injury To Quizalofop-Resistant Rice From Quizalofop Applied Postemergence, Navdeep Godara

Graduate Theses and Dissertations

Quizalofop-resistant rice technology allows for over-the-top applications of quizalofop, an acetyl-coenzyme A carboxylase-inhibiting herbicide. However, quizalofop caused significant injury to quizalofop-resistant rice in some Arkansas fields during the first year of commercialization. Experiments evaluated the effect of early-season soil moisture and nitrogen availability; pre-exposure to low rates of glyphosate and imazethapyr; planting date; and environmental conditions including, soil moisture content, air temperature, and light intensity on quizalofop-resistant rice tolerance to quizalofop applications. All experiments assessed sequential quizalofop applications made to 2-leaf followed by 5-leaf stage of rice. Sequential quizalofop applications alone and with surface irrigation or nitrogen application at the …

A Cross-Scale Nexus: Microbial Functional Genes In Tandem With Molecular-Level Nitrogen Fluxes And Implications For Field-Scale Biogeochemical Processes, Srusti Maddala

Graduate Theses and Dissertations

Nitrogen (N) biogeochemical cycling entails close networking between soil nutrients, plant species and resulting microbial communities, and abiotic factors such as temperature, moisture, and pH. To better understand transformations of N in soil microsites, which are known to be rich in N-cycling behavior, the microdialysis technique was employed to generate in situ data on temporal alterations of N during wetting-drying conditions in both the field and laboratory. The objectives were to 1) determine the lifespan of the microdialysis technique in field conditions, 2) evaluate the ability of the method to yield N fluxes that would be differential between the two …

The Mangrove Walks: An Econometric Analysis Of Climate Migration Drivers From Coastal Bangladesh And Their Geopolitical Impacts, Kendall Scott Byers

Graduate Theses and Dissertations

Coastal Bangladesh is subject to extreme climate change forces upon poor, rural populations. The aim of this thesis is to determine the strength of environmental drivers of migration and discern whether planned or catastrophic migration predominates in the polder areas of Bangladesh. I use regression analysis on a 1,025 household, 2016 IRRI/IWMI analysis of Polder 28/1, 28/2, and 30 within Satkhira district to determine factor correlations with migration. Progressive salinization is the strongest environmental driver, while flooding decreases migration through trapping household capital investment. Religion has the greatest correlation with migration. Hindus migrate less frequently, but do so with more …

Scheduling, Complexity, And Solution Methods For Space Robot On-Orbit Servicing, Susan E. Sorenson

Graduate Theses and Dissertations

This research proposes problems, models, and solutions for the scheduling of space robot on-orbit servicing. We present the Multi-Orbit Routing and Scheduling of Refuellable On-Orbit Servicing Space Robots problem which considers on-orbit servicing across multiple orbits with moving tasks and moving refuelling depots. We formulate a mixed integer linear program model to optimize the routing and scheduling of robot servicers to accomplish on-orbit servicing tasks. We develop and demonstrate flexible algorithms for the creation of the model parameters and associated data sets. Our first algorithm creates the network arcs using orbital mechanics. We have also created a novel way to …

Hiding In Plain Sight: Accounting For Rate Heterogeneity In Trait Evolution Models, James Boyko

Graduate Theses and Dissertations

Within the last four decades, phylogenetic comparative methods have become the defacto method of analysis for comparative biologists. The availability of high-quality comparative datasets has been matched by an explosion of possible phylogenetic models. In large part, the efforts to increase the realism of phylogenetic comparative methods has been successful as evidenced by their widespread use. To this extensive literature, my contributions are modest. I have focused my dissertation work on two main themes. First, most phenotypic evolution is not independent of other phenotypes. Changes in a particular character may influence changes in another and modeling these characters in isolation …

Hierarchically Structured Photoelectrodes Via Atomic Layer Deposition, Justin Rowan Reed Demoulpied

Graduate Theses and Dissertations

In the search for a sustainable method to meet increasing energy needs, solar energy emerges as an underutilized, plentiful resource. Solar intermittency and requirements for transportation necessitate storing solar energy in the form of chemical bonds via artificial photosynthesis. Photoelectrochemical (PEC) water splitting generates hydrogen fuel from solar energy and water. A semiconducting material that successfully meets the complex requirements for building an industrially scalable PEC device has yet to emerge. This is leading to a reevaluation of materials previously overlooked within PEC research, mainly materials with limitations such as minimal charge carrier mobility and propensity to corrosion under illumination …

"Design For Co-Design" In A Computer Science Curriculum Research-Practice Partnership, Victor R. Lee, Jody Clarke-Midura, Jessica F. Shumway, Mimi Recker

Publications

This paper reports on a study of the dynamics of a Research-Practice Partnership (RPP) oriented around design, specifically the co-design model. The RPP is focused on supporting elementary school computer science (CS) instruction by involving paraprofessional educators and teachers in curricular co-design. A problem of practice addressed is that few elementary educators have backgrounds in teaching CS and have limited available instructional time and budget for CS. The co-design strategy entailed highlighting CS concepts in the mathematics curriculum during classroom instruction and designing computer lab lessons that explored related ideas through programming. Analyses focused on tensions within RPP interaction dynamics …

Using Student Teaching Evaluations To Assess The Efficacy Of A Robert Noyce Teaching Scholarship In Preparing Candidates For Culturally-Responsive Practices, Teresa J. Bixby, Lauren Landando

Chemistry Department Faculty Articles

The goal of the NSF Robert Noyce Teaching Scholarship is to attract and support highly qualified STEM majors to become secondary-education teachers that are prepared to teach in high-needs schools. At Lewis University program activities targeted 1) teaching diverse learners, 2) inquiry and active-learning pedagogies, and 3) strengthening content knowledge. When the climate in education changed nationally mid-grant, activities to explicitly address culturally-relevant practices were developed. Since this emphasis was not directly addressed in the grant evaluation, here the use of student teaching evaluations as a tool to assess preparation in culturally-relevant practices is explored. Although some distinctions between Noyce …

Competition Between Halogen And Chalcogen Bonding And Their Role In Probing Organic Transformations, Andrew Peloquin

All Dissertations

Halogen bonding, the attractive interaction of an electrophilic region on a halogen atom with a nucleophilic region on another atom or molecule, provides a highly directional tool in forming solid-state motifs. This interaction, along with the related chalcogen bonding interactions, forms powerful synthons, which, when combined with other typical intermolecular attractions such as hydrogen bonding, allow for the design of supramolecular structures and inputs to crystal engineering. This dissertation research serves two primary purposes: (1) to catalog halogen and chalcogen bonding interactions with various donor molecules and (2) to utilize these interactions to probe interesting organic transformations.

In order to …

Development Of A Reverse Engineered, Parameterized, And Structurally Validated Computational Model To Identify Design Parameters That Influence American Football Faceguard Performance, William Ferriell

All Dissertations

Traumatic brain injury (TBI) continues to have the greatest incidence among athletes participating in American football. The headgear design research community has focused on developing accurate computational and experimental analysis techniques to better assess the ability of headgear technology to attenuate impacts and protect athletes from TBI. Despite efforts to innovate the headgear system, minimal progress has been made to innovate the faceguard. Although the faceguard is not the primary component of the headgear system that contributes to impact attenuation, faceguard performance metrics, such as weight, structural stiffness, and visual field occlusions, have been linked to athlete safety. To improve …