Digital Commons Network^™

Development And Testing The Predictability Of An Instrument Based On The Multi- Theory Model (Mtm) Of Health Behavior Change For Pre-Exposure Prophylaxis (Prep) Uptake Among People Of Color, Siddharth Raich

UNLV Theses, Dissertations, Professional Papers, and Capstones

HIV/AIDS continues to be a significant public health problem in the US and globally. In the US, it disproportionately affects people of color. In 2012, Pre-exposure Prophylaxis (PrEP) was approved by the FDA for HIV prevention. PrEP reduces the chances of acquiring HIV by 99% among people at high risk. However, PrEP uptake among people of color remains low. Therefore, this study aimed to develop and test the predictability of an instrument to describe the intent to initiate and sustain PrEP use among people of color. This research utilized an exploratory sequential mixed methods design based on the fourth-generation, multi-theory …

Removal Capabilities Of Zeolite And Zero Valent Iron With High-Level Waste Tank Radionuclides And Metals: Cesium, Strontium And Chromium, Colette R. Towles

UNLV Theses, Dissertations, Professional Papers, and Capstones

High level nuclear waste (HLW) has been disposed for temporary storage in underground steel tanks at the Department of Energy Nuclear sites. For example, at the Hanford Site, WA, and Savannah River Site (SRS), SC, HLW account for eighty-eight million gallons (Mgal) and 450 million Curies (MCi) of radioactivity. In the early nuclear activity at Hanford, the waste was discharged to single-shell steel tanks, and the lack of secondary containment allowed leaks, contaminating soil and groundwater. Despite tremendous efforts to stabilize the liquid waste at nuclear sites, treatment is complex, costly, and time-consuming; therefore, HLW may have to be stored …

Density-Driven Investigations Of Ruthenium Binary Compounds Rux2 (X = O, S, N), Melanie White

UNLV Theses, Dissertations, Professional Papers, and Capstones

Exploration and fine-tuning of the energy landscape of materials can be accessed by means of changes in material density, a key principle of high pressure research. Density-driven changes impact variations in oxidation states and coordination numbers for the element constituents of a compound. Pressure-induced modification of intrinsic density can promote the formation of new materials, variations in physical properties, and transformations in crystallographic symmetry. With this as our foundation, we focus on ruthenium binary compounds - altering the anion species to change electronegativity while probing pressure and temperature effects. This led us to the present study of ruthenium oxide RuO2, …

Uranium(Vi) & Thorium(Iv) Speciation In Organic Media Containing Organophosphorus & Diglycolamide Extractants, Joel Castillo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Developing sustainable green energy systems is a continually growing concern as the world is faced with urgent issues of climate change and global warming. Nuclear energy provides one of the most efficient solutions to supplying power to the electrical grid without causing more carbon pollution. There are nearly a hundred thousand metric tons of used nuclear fuel (UNF) stored on-site at decommissioned nuclear power plants for an indefinite period of time. Achieving a finalized closed fuel cycle is a crucial part in developing the nuclear energy necessary for combating the issues of pollution and greener energy. Understanding actinide speciation especially …

Mechanically Cost-Effective Approach For Bipedal Walking In Robots Using Instantaneous Collision Angle, Smit R. Patel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Humans, as bipedal locomotors, are effective at reducing the mechanical cost of transport (CoTmech) by adopting movement strategies and gaits that minimize energy expenditure for a given distance. By using different gaits at different speeds, leveraging their long spring-like tendons and muscle elasticity which store and release energy during movement, humans reduce the mechanical effort required for locomotion. Current locomotion solutions offered in bipedal robots, based on legacy walking and running gait models, are not great at energy efficiency unless walking at very low speeds. Additionally, the control system of robots, designed to ensure stability and adaptability, requires substantial resources, …

Nuclear Fuel Cycle Chemistry: A Density Functional Study, Eduardo Montoya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The nuclear fuel cycle aptly describes the life cycle of nuclear fuel sources such as uranium. From its early forms in naturally bearing ores, to its high-temperature sintering into a fuel pellet, the chemistry uranium experiences throughout the fuel cycle is diverse, driving many experimental efforts towards understanding its chemistry to both improve nuclear technologies and advance the safety and handling of nuclear materials. Computing techniques and methodologies can be used to supplement experimental research and are readily available to researchers interested in utilizing computing-based data to support experimental findings. Density functional theory (DFT) is commonly practiced, reliably predicting the …

Addressing Low Molecular Weight Chemical Peaking Events During Direct Potable Reuse By Granular And Biological Activated Carbon, Ceonie Washington

UNLV Theses, Dissertations, Professional Papers, and Capstones

Direct Potable Reuse (DPR) is an innovative solution designed to address water scarcity by treating wastewater to directly produce safe drinking water. As droughts and water shortages become more frequent, DPR offers a sustainable and localized water supply by incorporating advanced treatment processes. DPR systems typically rely on a combination of technologies such as ozone followed by biological activated carbon (O3/BAC), reverse osmosis (RO), and advanced oxidation processes (AOPs) to remove a wide range of contaminants. However, low molecular weight organic compounds (LMWCs), particularly volatile organic compounds, can sometimes pass through RO membranes and AOP systems.

California's DPR regulations currently …

Development Of Uranium Fluoride Microstructures, Harry Jang

UNLV Theses, Dissertations, Professional Papers, and Capstones

Uranium microstructured materials with controlled size and shape have found applications in several branches of the nuclear industry including as targets for medical isotopes production, fuels for nuclear reactors, standards for analytical measurements, and energy sources for space exploration. Morphological studies of actinide materials are also highly relevant to nuclear forensics-related work. Other potential applications include information storage, catalysis, sensors, and luminescent devices. Most studies on uranium microstructured materials have focused on binary oxides, nitrides, carbides, and fluorides, with the spherical shape being the dominant morphology. Prior to the work reported in this dissertation, aside from UF4 microspheres (ms) and …

Α-Quartz Plastic Strength Investigation Via Diffraction Experiments On Novaculite Using A D-Dia And Elastic Plastic Self-Consistent Interpretation, Denali Jivanjee Medina

UNLV Theses, Dissertations, Professional Papers, and Capstones

The plastic response of experimentally deformed quartz provides insight into the strength of ductile shear zones that has implications for tectonic, lithospheric, and ore deposit models. We present a suite of 15 uniaxial deformation experiments on Arkansas novaculite conducted in a DDIA apparatus with in-situ synchrotron x-rays. Experimental temperatures range from 25 C to 1334 C with pressures between 1.39 GPa and 3.1 GPa, and strain rates between 1x10-5 s-1 and 9x10-6 s-1. Macroscopic sample strain ranges from 3% to 24%. d-spacings from the (101), (110), (200), (201), and (112) lattice planes were measured, producing lattice strain up to ~5%. …

Investigation Ionic Polymer Metal Composite Capacitors Through Fabrication, Experimentation, And Modeling, Liya S. Napollion

UNLV Theses, Dissertations, Professional Papers, and Capstones

The increasing demand for greater energy storage capacity alongside the need to minimize the size of various devices, such as hybrid electric vehicles, medical devices, and pulsed power systems—has highlighted the necessity for advanced polymer film capacitors with high energy density. While traditional batteries and electronic devices have generally sufficed for many applications, their inherent size limitations hinder their ability to deliver the high levels of peak power required for certain demanding applications. This shortfall highlights the critical ongoing challenge within the energy storage sector to improve technology and more effectively meet these growing power requirements. Flexible Ionic Polymer Metal …

Control Of X-Delta Arm And Self-Leveling Robot Systems For Uav Applications, Prathibha Sobha

UNLV Theses, Dissertations, Professional Papers, and Capstones

The water droplet penetration test (WDPT) is an environmental assessment method for analyzing soil properties by measuring the penetration of water droplets into soil. This test provides insights into soil moisture retention and resilience, especially valuable in fire-prone or arid regions where soil recovery and erosion control are essential. Although this project does not conduct an actual WDPT, it investigates two key robotic systems designed to support such applications: an X-delta robot arm, which simulates precise droplet delivery patterns, and a self-leveling platform that ensures stability on uneven terrain, where the X-delta robot is mounted. Together, these systems examine the …

Fast Neutron & Gamma-Ray Scintillation And Broadband Photoluminescence From Gallium Nitride & Gallium Oxide: Developing Radiation-Hard Diagnostic Platforms, Daniel Jesus Valdes

UNLV Theses, Dissertations, Professional Papers, and Capstones

Integrated scintillation and electronics processing materials are of critical importance in environments exposed to high levels of radiation, such as nuclear fusion diagnostics and space missions. This dissertation focuses on the radiation detection capabilities of gallium oxide (Ga2O3) and gallium nitride (GaN), exploring their responses to fast neutrons and gamma rays. Using high-energy neutron beam facilities at Los Alamos Neutron Science Center (LANSCE) Flight Path 4FP60R, we exposed both Ga2O3 and GaN crystals to neutron irradiation spanning an energy spectrum ranging from 1 to 400 MeV. A Pi-Max 4 fast-gated Intensified CCD (ICCD) camera captured the transient scintillation responses for …

Addressing Inference Time Of Machine Learning Models In Embedded Systems, Samuel Black

UNLV Theses, Dissertations, Professional Papers, and Capstones

Embedded Systems are used for a wide range of specialized computing purposes including surveyal, safety, security, and quality of life. Many areas that embedded systems are used in require the use of machine learning models. Constraints can be placed on embedded systems. Timeliness of execution, user satisfaction, security, power, and resource limitations must be considered when designing for embedded systems. Neural networks excel at complex tasks that are otherwise intractable, but their relatively high computational cost poses a challenge for inclusion in embedded systems. Neural network architectures should be optimized to reduce the total number of operations performed while maintaining …

What Works When Working Together?: Cross-Sector Collaboration Barriers & Facilitators Of A Built Environment Health Impact Assessment In Southern Nevada, Maxim Gakh, Courtney Coughenour, Bertille Assoumou, Emily C. Strickler, Timothy J. Bungum, Jennifer R. Pharr, Pashtana Usufzy, Megan Mcdonough, Nicole Williams Bungum, Mindy Meacham

Environmental & Global Health Faculty Research

Purpose: Cross-sector collaboration can improve community health because decisions made across sectors influence health. Health Impact Assessments (HIAs) and other health-focused, cross-sector collaborations encounter challenges. This case study uses a completed HIA to explore factors impeding and supporting health-related cross-sectoral collaboration.

Methods: Semi-structured key informant interviews with 10 of 12 HIA working group participants were conducted and analysed using a content analysis approach.

Results: Analysis generated 48 codes across seven themes in three primary groups: HIA as a collaborative tool; logistical and systemic barriers; and benefits and logistical, interpersonal, and sectoral facilitators. Recognizing the importance of knowledge, analysis, and …

Invertebrate Functional Diversity Of Fossils From Arrow Canyon, Nevada, Nathaniel Valentine

Undergraduate Research Symposium Podium Presentations

Paleontology can be used to study how ecosystems evolve and respond to changes in the environment. Here we examine invertebrate fossils from the Pennsylvanian, a time period that ranged from 323.2 to 298.9 million years ago, which are preserved along the walls of Arrow Canyon (Nevada) in the Bird Spring Formation. We surveyed three sites within the canyon, and used data from the Paleobiology Database to create a list of taxa found on the canyon from this time interval. Although ecosystems have traditionally been studied using the composition of the ecosystem (the number of species), recent work has shown that …

Potential Cell Preservation In Mars-Relevant Clay Minerals, Hanford Gerille Gonzales, Leena M. Cycil, Elisabeth Hausrath

Undergraduate Research Symposium Posters

This study investigates the potential of Fe-nontronite, a clay mineral found on Mars, to preserve biological cells and retain biosignatures such as trace metals. The research explores the preservation potential of nontronite by reacting it with cells under the following conditions: 1) reacting cells with nontronite precursors at low temperature and 2) reacting cells with the already synthesized nontronite made at high temperature. Microbial species Shewanella oneidensis and Geobacter metallireducens, known for their relevance to iron-rich environments, were introduced in intact and lysed forms to assess their interactions with each condition of nontronite. Preliminary results from scanning electron microscopy (SEM) …

Autonomous Driving Trajectory Prediction, Carlos Funes

Undergraduate Research Symposium Lightning Talks

Autonomous driving is undoubtedly one of the world's most revolutionary technologies, opening the door to a more secure traffic environment. This innovation has led to vehicles being able to drive by themselves without the necessity of a person behind the wheel, as well as cruise control, lane-keeping assist, and automatic emergency braking. Unfortunately, there is still plenty of work before autonomous driving becomes more popular among drivers. While at UNLV as an undergraduate student/research assistant, one of my goals is to learn how these technologies work to bring ideas into the automotive industry by refining solutions to problems within these …

It's Not As Bad As You Think: Detecting Ai-Generated Voices, Yong Qin Xu

Undergraduate Research Symposium Lightning Talks

Advances in machine learning have opened up the world to a brand new frontier of fraudulent phone calls which the average person may not be in any way prepared for. From imitations of a loved one's voice to lifelike mimicry of human callers, telephone scams may become harder than ever to anticipate or prevent now that criminals have the help of AI on their side. This is why in my research paper, I aim to analyze and compare two existing methods of detecting the authenticity of human voice recordings in order to demonstrate and explain currently available technology that's capable …

Climate Change And Its Effects On Maternal Mental Health, Sara Cordero

Undergraduate Research Symposium Lightning Talks

Climate change refers to long-term shifts in temperatures and weather patterns primarily caused by human activities, which have facilitated more climate crises, such as floods, wildfires, hurricanes, etc. They tend to have the greatest effect on vulnerable populations, such as women and children. This study is aimed to view how climate change-related environmental stressors impact the mental health and well-being of mothers. A scoping literature review approach was used by analyzing scientific databases (i.e. APA-Psycinfo, Scopus, PRIMO) to find peer-reviewed papers that studied the effects of extreme weather events and climate change on maternal mental health. Results suggest that hurricanes, …

The Correlations Between Students' Academic Success And The Various Modes Of Attendance, Lewana-Nani Lebaron

Undergraduate Research Symposium Podium Presentations

The increased demands on students’ time and effort imposed by their academic and personal environments have prompted many to explore alternative avenues for attending classes. This study sought to determine the existence of a correlation between the different modes of classroom attendance and students’ academic success. The research detailed within this report examined the attendance of four undergraduate statistics classes with 111 participants. Students were incentivized to complete an attendance survey, indicating whether they attended in person, virtual live streaming, or viewed the recorded lecture at a later time. Students who did not respond to the survey or were absent …

A Simple And Low-Cost Method For Generating Short Laser Pulses, Daniel Fisher

Undergraduate Research Symposium Posters

A simple, portable method is described and demonstrated for generating short optical pulses (~ 1 μsec) from a continuous wave (CW) source using a rotating pinhole. A CW 633nm HeNe beam was focused onto a 225 μm diameter stainless steel pinhole, which was rotated up to 1000 Hz using an optical chopper wheel. The pulsed light was then focused onto a silicon photodetector and read by an oscilloscope. This novel setup aims to bridge the gap between pulsed laser performance and price for wide application in spectroscopy methods, industrial laser peening, and medical treatments. This will be the first publication …

Impact Of Young Biocrust On Dryland Surface Albedo, Rhynhardt Mudde, Rebekah Magness, Raul Roman, Nicole Pietrasiak

Undergraduate Research Symposium Posters

More than 40% of the Earth’s surface is covered by drylands. Due to limited availability of water, less surface area is covered by vascular plants. Instead, this space is occupied by microbial communities that exist in close contact with mineral soil, creating a living aggregate on the upper soil layer and are known collectively as biological soil crusts or “biocrusts”. Biocrusts play a vital role in ecosystem functioning in drylands specifically through their influence on hydrological processes (e.g., water retention, infiltration). However, the impact of biocrusts on evaporation is not well understood. Biocrusts have been reported to either increase or …

Assessing Ectomycorrhizal Advantage On Tree Species Within Differing Soil Materials In Spring Mountains, Nevada, Kirsten Soriano, Riley Jones, Daniel Thompson

Undergraduate Research Symposium Posters

Ectomycorrhizal fungi (ECM) form symbiotic relationships with their partner plant, creating root systems which allow for the exchange of nutrients among connected plants. The Spring Mountains National Recreation Area (NRA) in Southern Nevada is the study site for examining ECMs due to its diverse ecosystem with numerous inhabiting species. To assess the effects of ECMs on the tree composition, literature review was conducted to outline previous methods. Through data analysis and observations of the sample sites, it is concluded that ECMs are highly likely to have an effect on tree composition of the Spring Mountains NRA. The purpose of this …

Utilizing A Hybrid Apprach To Link Maternal And Neonatal Records, Vidhani S. Goel, Ana Reyes, Bertille Assoumou, Dodds P. Simangan, Farooq Abdulla, Megumi Akiyama, Deborah A. Kuhls, Kavita Batra

Undergraduate Research Symposium Posters

Linkage of independent datasets allows comprehensive and robust analysis. This study aims to utilize a hybrid strategy to link maternal records with neonatal data with an overarching goal of investigating correlates of adverse birth outcomes.

To link 126,757 records from Nevada Medicaid with 249,181 maternal records from Birth Registry, a hybrid linkage approach was utilized. Data normalization was first performed for the standardization of linkage keys. First, a deterministic approach was used to link these records using a unique identifier followed by a fuzzy or probabilistic algorithm using a set of block variables. These block variables included date of birth, …

Effects Of Fire Temperatures On Mojave Desert Native And Nonnative Seeds, Sophia Lorenzana, Lindsay Chiquoine

Undergraduate Research Symposium Posters

Large-scale wildfires have been historically rare in hot deserts like the Mojave, largely due to the scarcity or uneven distribution of native plant biomass as fuel. Thus, native plants in these regions are ill-adapted to withstand spreading wildfire, resulting in slow post-fire recovery. Here, I test the hypothesis that nonnative grasses respond better to heat cues than native plant species. Seeds from 3 invasive and 13 native plant species were collected from research sites located in the eastern Mojave Desert, near surrounding Clark County Flood Control District weather stations. Seeds were buried in an artificial substrate mimicking field soil conditions …

Characterizing The Mechanical And Visoelastic Properties Of Sodium Alginate, Vesper Evereux

Undergraduate Research Symposium Posters

A crucial part of tissue engineering lies in understanding and characterizing the mechanical and viscoelastic properties of various types of biomaterials. Understanding these properties allows better biomaterials to be produced with characteristics more similar to those of the human body and with better biocompatability. In this study, sodium alginate was chemically crosslinked with calcium chloride and subsequently tested for it's instantaneous Elastic Modulus, instantaneous Shear Modulus, and equivalent viscosity using indentation testing methods consisting of a stress-relaxation test and nonlinear curve-fitting analysis. Two and three millimeter indentation tests were performed using a low-cost and portable device built in-lab that resulted …

Detection Of Methane Leaks By The Use Of Mid-Range Infrared Camera, Jared Rosario, Oscar Salcido

Undergraduate Research Symposium Posters

Timely detection of methane leaks from natural gas infrastructure, like pipelines and valves, is essential for mitigating environmental and safety risks. This research focuses on using mid-wave infrared (MwIR) cameras on unmanned aerial systems (UAS) to detect leaks. By leveraging machine learning, the study aims to develop an efficient, real-time methane inspection system that operates directly on embedded processors on UAS platforms.

This project employs the FLIR G300a OGI camera for remote gas inspection, utilizing video preprocessing and optical flow to mask gas plumes in footage. The YOLOv8 deep learning model is used to detect gas pixels and segment the …

Biochar/Hydrochar Applications In Disinfection Byproduct Removal For Drinking Water, Ashleu Mussio Marquez, Donna Rouhani, Ismail Abdulraheem, Kers Ung-Watson, Ahmadreza Khatamgooya, Scarlet Nelson, Dr. Jaeyun Moon, Dr. Erica Marti

Undergraduate Research Symposium Posters

This project aims to investigate the process of disinfection byproduct (DBP) removal in drinking water, looking into the applications of biochar and hydrochar, which are low cost and environmentally sustainable adsorbents. These carbon-based adsorbents are derived from agricultural waste biomass, such as walnut shells. These adsorbents will be used to capture and remove contaminants in water, such as DBPs. DBPs are formed when chemical disinfectants react with organic and inorganic substances naturally present in water. The targeted DBPs for adsorption include trihalomethanes, haloacetic acids, haloacetonitriles, and nitrosamines. An example of high concentration DBP formation is during emergency chlorination, where excess …

Intersections Of Living And Machine Agencies: Art-Based Models Of Adaptive Conversation With The More-Than-Human World, Carlos Castellanos

Tradition Innovations in Arts, Design, and Media Higher Education

Today’s AI systems are not built to have reciprocal interplay with their environments and thus they demonstrate little interest in emergence, adaptation or developing mutually productive relationships with the natural world. Is a different kind of AI possible? How can artists contribute to its development? In this essay, I will discuss ways in which the arts might help guide us towards a new kind of AI, built upon adaptive conversation (i.e. shared construction of meaning) with nature. I will discuss how can work with AI while also challenging its prevailing ontology, and even suggest alternative ontologies and epistemologies. I will …

Shifting Employment And Perceptions Of Household Responsibilities During Early Stages Of The Covid-19 Pandemic In Nevada, Usa, Courtney Coughenour, Lung-Chang Chien, Brian Labus, Maxim Gakh, Pashtana Usufzy

School of Public Health Faculty Research

Background: Employment and household responsibility are critical health determinants. The COVID-19 pandemic altered the work and social landscapes in Nevada, USA through closures of workplaces and schools/childcare centers, changing patterns of employment, and household responsibilities. This study aimed to measure changes in employment status and perceived housework responsibilities among Nevada adults in December 2020, before widespread availability of COVID-19 vaccines in a pandemic-affected economy.

Methods: Using a cross-sectional telephone survey of 1,000 Nevada adults, this study compared respondent experiences and perceptions of employment and time spent on housework in December 2020 to pre-pandemic using multinominal logistic, proportional odds, and logistic …