Digital Commons Network^™

Derivation Of Adjoint Based Error Estimates For Nonlinear Ordinary Differential Equations With Application To Multistage Sir Models With Demographics, Daniel Alcala

Mathematics & Statistics ETDs

Ordinary Differential Equations (ODEs) are central to the mathematical modeling of various real-world phenomena, from mechanical systems governed by Newton’s laws to epidemic dynamics described by SIR-type ODEs. Since many ODEs do not admit closed-form analytic solutions, we approximate them numerically (e.g., with Euler’s, Runge–Kutta, or other such methods). This raises the key question: How accurate are these numerical solutions? In particular, reliably estimating the error in some quantity of interest (QoI) at time T without having an exact solution is of great scientific interest.

The first main contribution of this thesis is the development and analysis of adjoint-based error …

Toward Simulating 2d Cell Surfaces In A Disk, Myriam Allred

Mathematics & Statistics ETDs

Certain evolution models of cell surfaces (treated in two-dimensions) involve the solution of the Helmholtz equation with jump conditions enforced on an immersed closed curve. This thesis presents a sparse, modal spectral method for solving such Helmholtz problems. The solution is required to be continuous across the curve, but with a jump discontinuity in the normal derivative proportional to the planar curvature. The method relies on classical Fourier-Chebyshev basis functions, with the application of modal Chebyshev integration matrices to achieve sparse, banded approximations of the Helmholtz equation. The method achieves spectral convergence, despite the inherent low regularity of the relevant …

Assessing The Ecological Drivers And Consequences Of Partial Migration In Hudson River Striped Bass Over Three Decades, Caitlin Egan Zimmer

Biology ETDs

Climate change and shifts in human land use have caused extensive impacts to the connectivity, structure, and resilience of aquatic populations. Partial migration (PM), where only some individuals from a population migrate while the rest remain resident, can mitigate population-level responses to environmental stressors. However, little is known of the underlying mechanisms promoting variation in migration and whether these shift over time. In the Hudson River Estuary, striped bass (Morone saxatilis) are known to exhibit anadromous PM behavior. Here, I measured carbon isotopes (δ¹³C) of essential amino acids in striped bass scales to determine variation in …

The Island Biogeography Of Mangrove-Dwelling Vertebrates: Isolation, Specialisation, And Extinction, Jian Xiong David Tan

Biology ETDs

Mangroves are highly dynamic ecosystems that are widely distributed across the coastlines of the tropics and subtropics. Despite their low plant diversity, mangroves host a disproportionately high number of terrestrial vertebrate taxa. However, mangrove specialists — taxa that only occur in mangrove habitats — exhibit a global distribution that is incongruous with the broader background distribution patterns of mangrove-associated fauna, exhibiting higher diversity in Australia and Southeast Asia. This dissertation therefore aims to assess how the diversity and distribution of mangrove specialist fauna may have been shaped by the historical biogeography of mangroves, and the effects of mangrove specialisation on …

Plant Reproductive Strategies Shift In Response To Restoration Using Beaver Dam Analogs, Laurel F. Martinez

Biology ETDs

As riparian communities become increasingly degraded, restoration treatments are being implemented in streams to recover ecosystem functions. In the Jemez Mountains, beaver dam analogs (BDAs) are used to restore degraded streams by connecting the floodplain and increasing the extent of anoxic soil conditions. These environmental disturbances are expected to alter how riparian plants recruit, particularly their allocation to seed-based and vegetative regeneration strategies. We investigated whether BDAs and associated changes in soil water filled pore space (WFPS) affected riparian plant recruitment. We investigated the number of flowering stems as a proxy for seed-based regeneration and rhizome length and mass as …

Ecoimmunology Of Dirty Physella Acuta Snails, Kevin Arthur Mcquirk

Biology ETDs

Research on Physella acuta, an invasive freshwater snail, reveals insights into its parasitology, fitness, and molecular biology. Morphological and molecular analyses revealed two distinct mitogenomic lineages, local (B) and invasive (A) strains of native P. acuta, both having comparable trematode infection rates, suggesting that the low infection rates observed from A in invaded regions result from "enemy release" rather than immune incompatibility. Fitness assessments showed that while lineages A and B performed similarly under laboratory conditions, rewilding experiments revealed significantly higher fitness in lineage A. Transcriptomic profiling supported these differences, with A snails showing greater immune-related gene expression and …

A Data-Driven Approach To Time Series Forecasting And Clustering Of U.S. Regional Drug Overdose Mortality, Koshali Hamy Muthunama Gonnage

Mathematics & Statistics ETDs

The increasing rate of drug overdose deaths in the United States poses a critical public health challenge, particularly due to the surge in synthetic opioids and other high-risk substances. This study presents a data-driven framework that integrates time series forecasting and clustering techniques. Monthly mortality data for five key drug types: cocaine, fentanyl, heroin, methamphetamine, and oxycodone were analyzed using four time series forecasting models: ARIMA, ETS, TBATS, and NNAR. These models were evaluated using standard accuracy metrics RMSE, MAPE, and MAE to assess predictive performance. Signal decomposition approach based on Singular Value Decomposition and subspace modeling was employed to …

• Social Media Use Among Undergraduate Women: Associations With Body Image, Disordered Eating, And Well-Being, Kirsten P. Peterson

Psychology ETDs

Though prior research has identified a range of negative impacts associated with social networking site/app (SNS) use, these effects vary and are often attributed to specific aspects of SNSs rather than time spent on them. The current study examined relations between SNS use and various psychological outcomes (i.e., body appreciation, body dissatisfaction, eating pathology, depression, and self-esteem) and how these may differ by platform, proportion of image-based content, image subjects, and passive (relative to active) use. Worse outcomes were anticipated for individuals who primarily used appearance-focused platforms and those with greater exposure to image-based content, self or celebrity images, and …

Cultural Risk And Protective Factors Associated With Sexual Assault Among Hispanic And Non-Hispanic White Women, Daisy Ramos

Psychology ETDs

There is a paucity of research on sexual assault among Hispanic college women. Existing studies indicate that Hispanic college women report similar mental health sequelae as non-Hispanic White women following a sexual assault; thus, factors that protect or increase their risk is an area worthy of further investigation. Latino cultural values, such as familism, may serve as a protective factor for sexual assault among Hispanic college women, while acculturation with mainstream culture may function as a risk factor. This study examined whether ethnicity moderated the effects of cultural protective and risk factors on sexual assault experiences among Hispanic and non-Hispanic …

Using Triple Oxygen Isotopes To Investigate Water Usage In Desert Ecosystems, Cloe V. Knutson

Earth and Planetary Sciences ETDs

In arid environments, maintaining water balance can be more critical for survival than obtaining food. As droughts intensify, understanding how animals manage body water is essential. Triple oxygen isotope analysis provides a novel way to trace water sources in animals, distinguishing contributions from free water, food-derived oxygen, and atmospheric O₂. We developed an equilibration method using CO₂–H₂O oxygen exchange and measured δ^’18O and Δ^’17O values via tunable infrared laser direct spectroscopy (TILDAS). Validated against traditional fluorination methods, this technique enables streamlined analysis of whole blood and plant samples. Applied to …

Modeling Mars Chaos Terrains As Fracture Mosaics, Aidan C. Buie

Earth and Planetary Sciences ETDs

Chaos terrain exists on several planetary bodies but most notably on Mars. With 30 different named terrains and hundreds of chaotic or ”chaos-like” terrains, they are one of the most prominent and visible features on the planet. Chaos terrains have many visible similarities to each other: they all are comprised of polygonal blocks separated by fractures or channels. These blocks vary from angular to rounded and from flat plateaus to small hills, and the fractures vary from flat floored to ”v” shaped. Often, a single chaos will contain all of these morphologies. Most of the 30 named chaoses on Mars …

Interdependence And Place In Mescalero Homelands, 1660-1865, Joseph A. Ukockis

History ETDs

This dissertation examines strategic relationships that Mescalero Apaches made among themselves and with non-Mescalero communities from 1660 to 1865. It references Mescalero place names in piecing together pertinent stories across their vast ancestral homelands, demonstrating regional continuities in social, political, and economic dynamics over two centuries. It argues that bonds of interdependence, rather than armed resistance, were critical in maintaining autonomy and the ability to move freely, conduct effective diplomacy to protect claims to homelands, access resources in times of scarcity, and form key alliances that presented possibilities for resistance to colonial domination. Central to these dynamics were Mescalero and …

An Analysis Of Employment Patterns And Career Decisions Among Dental Hygienists: In A Transforming Healthcare Landscape, Shirley Calderon Jamarck

Dental Hygiene ETDs

The purpose of this study was to identify the factors contributing to dental hygienists’ consideration of changing careers, retiring early, or feeling burned out. A 26-question survey was emailed to members of the American Dental Hygienists’ Association, with 742 responses meeting inclusion criteria. Participants evaluated aspects of their careers, including job satisfaction, wages and benefits, personal growth, work-related stress, burnout, work-life balance, and retirement plans. Results revealed that one-third of respondents planned to leave the profession, citing burnout, physical strain, and limited career growth as reasons. High correlations were found between job satisfaction and feeling valued, professional accomplishment, and growth …

Lifestyle Factors Contributing To Occupational Heat-Related Acute Kidney Injury, Jonathan Specht, Fabiano Amorim, Flavio De Castro Magalhaes, Zachary Mckenna, Zachary Schlader

Health, Exercise, and Sports Sciences ETDs

Workers worldwide are at risk for acute kidney injury due to hyperthermia and dehydration as a consequence of exertional heat stress. Limited research has explored the impact which lifestyle agents such as beverages, recreational drugs, and medications have on core temperature, hydration, and risk of acute kidney injury during physical work in the heat. To address this research gap, we explored the impact of three agents frequently used by construction workers on thermoregulation and markers of risk of acute kidney injury. First, we investigated the effect which ibuprofen ingestion has prior to one hour of running in the heat on …

Addressing Head Injuries In High School Football: An Assessment Of Best Practices And Challenges In The Area Of Concussions As Held By New Mexico Activities Association High School Varsity Football Head Coaches And Athletic Directors, Alonzo Maestas

Health, Exercise, and Sports Sciences ETDs

Youth sports participation in the United States offers children and adolescents opportunities for physical activity, skill development, social interaction, and personal achievement. However, with sports comes the risk of injury, including concussions. Concussions can have serious long-term consequences such as chronic traumatic encephalopathy (CTE). In response to the risks of concussions, New Mexico enacted a concussion law, NM Stat 22-13-31. In addition to this law, the New Mexico Activities Association (NMAA) and National Federation of High School Associations (NFHS) have also given guidance on how to manage concussions.

However, there is a gap in the literature concerning concussion education, best …

Deaf Black Youth's Narratives About Identity And Education, Dominic A. Harrison

Language, Literacy, and Sociocultural Studies ETDs

This study is significant in exploring the different ways in which Deaf Black youth construct their identities through the use of narrative inquiry. Educators of Deaf youth should acknowledge how the identity journeys of Deaf Black youth are often affected by the school and home communities. This research employed narrative inquiry to understand how Deaf Black youth construct their identities as Black Deaf individuals. Using Critical Race Theory (CRT) as a theoretical framework with the guidance of Intersectionality and Dis/ability Critical Race Theory (DisCrit) lenses, the study specifically examined four Deaf Black youth’s narratives to highlight how they construct and …

Spanish Language Arts Guerreras Y Guerreros: Narratives Of Figured Worlds On Pedagogy, Lucha, E Identidad, Mishelle L. Jurado

Language, Literacy, and Sociocultural Studies ETDs

This dissertation explores how Spanish Language Arts (SpanLA) teachers in dual language high school programs construct and narrate their identities through pedagogical choices. Using critical narrative inquiry and the theoretical lens of figured worlds (Holland et al., 1998), the study centers the lived experiences of bilingual educators who resist deficit perspectives and reimagine their classrooms as spaces of cultural affirmation, linguistic justice, and transformative pedagogy. Data sources include semi-structured interviews, teacher-selected artifacts, and focus groups. Findings reveal that SpanLA educators enact linguistically and culturally nourishing pedagogies, rooted in ancestral memory, critical consciousness, and a commitment to student agency. These educators …

Making The Macc: Communities Of Practice And Cultural Citizenship In Austin, Texas, Cassie Lynn Smith

Anthropology ETDs

Meaningful community engagement is a challenge for local governments without a thorough understanding of constituents’ histories and their relationship with City government. This dissertation investigates the City of Austin’s (COA) Emma S. Barrientos Mexican American Cultural Center (MACC) in Austin, Texas, to understand how this culture and arts institution engages with and is influenced by its patrons. This study analyzes the role of the MACC’s community of practice (Lave and Wenger 1991)—an evolving group of educators, activists, artists, and COA staff—in shaping public policy and educational programming as well as creating places of belonging for marginalized people in the city. …

“…Stay On It…”/A Theory///“Illumination Happens”//, Lara E. Goldmann

Art & Art History ETDs

“…stay on it…”/a theory///“illumination happens”// is a critical engagement with the work of contemporary Black artists Arthur Jafa and Adam Pendleton, explored through the lens of the Black radical tradition. Bridging aesthetics, politics, and history, the dissertation investigates how their visual, sonic, and conceptual practices articulate Black life, insurgency, and imagination.

Drawing on theorists such as Fred Moten, Sylvia Wynter, Hortense Spillers, Frantz Fanon, and Cedric Robinson, the study constructs a framework that considers Blackness as an ontological, social, and aesthetic force. It examines how Jafa and Pendleton unsettle dominant epistemologies, staging acts of refusal and creation that resonate within …

Microneedle-Based Lc-Ms/Ms Profiling Of Dermal Interstitial Fluid Reveals Early Lipid Dysregulation Contributing To Painful Neuropathy In Prediabetic And Type 2 Diabetic Rats, Srinivasa Rao Gadam

Biomedical Sciences ETDs

Painful diabetic neuropathy (PDN), a complication of type 1 and type 2 diabetes, also occurs in obesity and prediabetes, with dyslipidemia as a modifiable risk factor. The distal-to-proximal neuropathy pattern and length-dependent intraepidermal nerve fiber loss suggest peripheral contributions. We hypothesized that elevated neurotoxic lipid intermediates—diacylglycerols (DAG), free fatty acids (FFA), and acylcarnitines (CARs)—in the dermal interstitial fluid (ISF) drive metabolism-associated hyperalgesia in prediabetic and diabetic rats. Using a microneedle array (MIA) with LC-MS/MS, we profiled ISF and serum lipids from high-fat diet (HFD) and HFD + streptozotocin (STZ) rat models alongside Hargreaves testing. ISF lipid changes appeared earlier (weeks …

Exploration, Expansion, And Optimization Of Bacteriophage Virus-Like Particle Vaccines, Andzoa N. Jamus

Biomedical Sciences ETDs

Bacteriophage virus-like particles are highly immunogenic, self-assembling platforms used for various vaccines. This work shows efforts to explore new vaccine candidates against Chlamydia trachomatis, targeting proteins that play critical roles in attachment and entry into the host cell, as well as in pathogenesis and bacteria proliferation. This work also shows the optimization of previously identified candidates, by investigating how altering routes of immunization can change the antibody profiles elicited, both systemically and locally. Finally, this work shows the establishment of various Chlamydia infection models in an effort to expand the ways in which vaccine efficacy can be investigated, particularly …

Immune Regulation In Fungal Airway Inflammation And Host Defense, Ruoning Wang

Biomedical Sciences ETDs

Asthma is a chronic inflammatory disease of the lungs characterized by complex pathophysiological mechanisms and diverse endotypes, primarily categorized as T helper type 2 cell (Th2)-high and Th2-low asthma. Despite significant advances in understanding asthma pathogenesis, the mechanisms governing the pulmonary immune system’s response to external challenges have not been fully understood. To address these gaps, this comprehensive project was designed to investigate the interplay between fungal infections and specific CD4⁺ T cell populations in asthma. Our findings suggest that fungal infections can contribute to neutrophilic asthma by promoting the migration of platelet-myeloid aggregates into the lungs. We also …

Localization Of Alpha Power Deficits In First Episode Psychosis, Crystal A. Garcia, Juan Bustillo

Biomedical Sciences ETDs

The purpose of this study was to determine where in the brain there may be a difference in brain activity in patients during their first episode of psychosis (FEP) compared to healthy controls (HCs) while performing an auditory oddball task. Time-frequency analysis allows for spectral decomposition where the signal measured by magnetoencephalography (MEG) is used to characterize changes in neural oscillations and their synchronization over time and region. Previous EEG studies report reduced alpha (8-12Hz, 70-160ms) power but most studies focused on patients with chronic schizophrenia and with limited source localization.

A Mutational Analysis Of Thatisin: How Single Point Mutations Impact The Biosynthetic Process Of A Group 16 Graspetide, John F. Boynton Jr

Chemistry and Chemical Biology ETDs

Abstract:

Graspetides are a family of Ribosomally synthesized and Post-translationally modified Peptide (RiPP) natural products named for their ATP Grasp Macrocyclases. We identified several Graspetide Biosynthetic Gene Clusters containing common double glycine cleavage motifs and attempted characterization of the mature Graspetides. One of the resulting peptides, Thatisin, has a topology with two interlocking macrolactones installed by a single ATP Grasp Ligase named ThtC. Here we use single and double point mutations to observe the impact or variation on the installation of these macrocycles. Alanine scan mutagenesis is used to assess leader peptide residues in the precursor peptide ThtA to determine …

Understanding The Metallic And Oxide Phases In Platinum-Based Bimetallic Heterogeneous Catalysts After High-Temperature Oxidation, Stephen John Porter Jr

Nanoscience and Microsystems ETDs

Platinum (Pt) and palladium (Pd) are critical components in diesel emission control systems, enabling the conversion of harmful pollutants under demanding conditions. However, Pt’s effectiveness is hindered by sintering under high-temperature oxidizing environments. This dissertation investigates how Pt and Pd evolve under oxidizing conditions at 800°C, highlighting their distinct thermodynamic behaviors and interactions. Using TEM, EDS, EELS, XRF, XRD, and EXAFS, we show that Pd suppresses Pt sintering by reducing the volatility of PtO₂, leading to the formation of stable particles. Both Pt and Pd are present in metallic and oxide states, forming biphasic 'Janus' particles with conjoined metal and …

Phase Nanoscopy With Correlated Frequency Combs, Xiaobing Zhu

Optical Science and Engineering ETDs

In this dissertation a sensing method applying to any physical quantity that modifies optical phase is developed. Two pulses are produced inside a synchronously pumped Optical Parametric Oscillator, generating two identical, undistinguishable frequency combs. The physical quantity to be measured applies a small phase shift/round trip to one of the pulses, resulting in a frequency shift of the corresponding comb. The latter frequency is measured as a beat by interfering the two combs on a detector. A world record resolution, close to the quantum limit, of 0.033 nanoradian (corresponding to 0.006 fm in displacement) is achieved. A detailed analysis of …

Advancing Diamond Quantum Sensors: Isotropic Flux Concentrators And Phase Noise Mitigation, Maziar Saleh Ziabari

Optical Science and Engineering ETDs

Two methods for improving the sensitivity of nitrogen vacancy quantum sensors in diamond are explored. First, by passively concentrating the magnetic flux, three orthogonally oriented ferrite truncated cone pairs amplify the field isotropically by 19 times, allowing measurement of Earth's field without a bias field and increasing sensitivity. Through thorough analysis, modeling and tuning a novel 3-dimensional flux concentrator system, we achieve a fractional standard deviation of less than 1% anisotropy and quantify minimal deadzones and ambient temperature-limited variations below 40 nT/hour. Second, we characterize, model and calculate phase noise in NV experiments, which in NV sensors is effectively indistinguishable …

Predicting Leakage From Nuclear Material Containers At Los Alamos National Laboratory Through Drop Testing, Leak Testing, Finite Element Analysis And Digital Image Correlation, Jude M. Oka, Yu-Lin Shen, Osman Anderoglu, Pankaj Kumar, Rajendra Vaidya

Mechanical Engineering ETDs

Los Alamos National Laboratory (LANL) relies on containment vessels to safely manage special nuclear material. These containers are subject to rigorous testing—such as drop, fire, and water ingress testing—to ensure integrity under adverse conditions. While elastomer-based seals are well studied, metal-to-metal sealing mechanisms remain under investigation, particularly under dynamic loading. This research focuses on the relationship between container mating surfaces and impact loading through drop testing. Finite Element Analysis (FEA) models were developed and validated using Digital Image Correlation (DIC) to measure strain during impact. Drop tests at varying heights showed strong correlation between FEA and DIC results, confirming the …

Networked Systems: Synchronization, Decomposition And Transient Dynamics, Amirhossein Nazerian

Mechanical Engineering ETDs

This dissertation investigates synchronization, transient dynamics, control, and signal amplification in networked dynamical systems. First, it examines complete and cluster synchronization, including cases with large parametric mismatches, in both natural (e.g., brain networks, fireflies) and technological systems (e.g., power grids, robotics). Second, it studies transient dynamics in consensus processes, designing synchronization strategies that link reactivity, contraction theory, and Lyapunov exponents. Third, it addresses the computational limits of Model Predictive Control (MPC) for large networks by introducing an algebraic decomposition method that enables parallel online computation of smaller subproblems, enhancing MPC performance under hardware constraints. Finally, it analyzes the structural role …

Instability Analysis In Cylindrical Thin Film–Compliant Core Structures: Numerical Simulations And Effects Of Inelastic Deformation, Md Al Rifat Anan

Mechanical Engineering ETDs

When a thin film bonded to a thick compliant substrate is subject to in-plane compression, wrinkles can develop if the critical state for instability is reached. In various applications the film/substrate system may also take the form of cylindrical fibers, where an axial compressive loading can trigger axisymmetric wrinkles. A straightforward computational approach to simulate such wrinkling behavior is needed for material design, to either prevent wrinkling or to exploit its benefits for flexible device applications. In this work a comprehensive numerical study is undertaken by employing the finite element method. The embedded imperfection approach used previously for planar structures …