Digital Commons Network^™

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 …

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 …

Multiscale And Multi-Model Studies Of Metal Plasticity, Luo Li

Mechanical Engineering ETDs

Plastic deformation is the process in which the material deforms permanently due to external effects. Twinning and slip are two main mechanisms of plastic deformation in metallic materials. The prominent mechanism of plastic deformation in metals that have FCC crystal structures is slip or gliding movement of dislocations, which is mainly focused on here. In the current study, frameworks for investigating plasticity phenomena of metals at different scales ranging from microscale to macroscale are demonstrated. Specifically, the macroscale modeling of plastic response of metallic materials induced by indentations are emulated by nonlinear FEA simulations. Simulation results of macroscale modeling are …

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 …

A Systematic Approach To The Characterization Of Liquid-Vapor Coexistence In Platinum, Meghan K. Lentz

Physics & Astronomy ETDs

Platinum is a material standard used in high pressure and shock compression experiments at Sandia National Laboratories. During experiments, materials are subjected to a very large range of thermodynamic conditions, during which materials regularly enter the liquid-vapor coexistence region. Despite its status as a standard, the region around the liquid-vapor critical point is poorly understood for platinum, with reported critical temperatures spanning approximately 7000 K. In this dissertation we conduct density functional theory based molecular dynamics (DFTMD) simulations for platinum for a range of temperatures and densities near liquid-vapor coexistence. The phase diagram for platinum is refined near the critical …

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 …

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 …

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 …

Improving Infiltration Model Performance In Arid And Urban Regions, Samuel Stephen Coulter

Civil Engineering ETDs

Flooding in arid regions is infrequent but damaging and limited historical data makes flood modeling an important tool for flood infrastructure design. This study improves flood modeling guidance by using plot-scale tests to determine the impact of slope, compaction, gravel mulch and landscape fabric on infiltration and runoff rates in sandy soil types. This data will be used as guidance for the linear and constant model. The performance of this model was compared with the curve number model for a hypothetical 100-year design storm. Results showed that gravel mulch increased infiltration rates by 66% and reduced erosion on steep and …

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 …

Secured Through Stone: The Power, Monuments, And Memory Of Thyra Danmarkarbót And The Jelling Dynasty, Jacquelyn Truitt

History ETDs

Sometime in the mid-tenth century on the Jutland peninsula of Denmark, the Viking Age Queen Thyra (d. ca. 958/9) passed away and the epithet Danmarkarbót—Denmark’s Adornment—was skillfully carved onto her memorial runestone. Yet Thyra’s story has been clouded by few and unreliable textual sources, by differing assessments of her familial background that have emerged from those sources, and by misrepresentations of the material culture relating to her. This thesis explores Thyra and her place within the Viking Age Jelling dynasty through textual and material evidence and considers how the construction of both medieval and modern memory work and memorialization …

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 …

College Football Or Abortion Education? An Examination Of The University Of Arizona’S 1974 Stadium Bonds Bill, Emma Masterson

History ETDs

In 1974 the University of Arizona renovated their football stadium through a bonds bill passed by the state legislature. The renovations allowed the university to increase the stadium’s capacity by 17,000 seats. While in the state house, an Arizona Congressman attached a rider to the bonds bill banning the university’s medical school from performing abortions in most circumstances, effectively barring the university from teaching the medical students how to perform the procedure as well. This thesis seeks to position the University of Arizona football stadium renovations and abortion ban within the larger histories of American higher education and Arizona. This …

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 …

Minimal Error Functions On Irregular Subsets Of The Real Line, Robert Michael Dukes

Mathematics & Statistics ETDs

Chebyshev Polynomials, those that minimize the maximal error on a compact set, are one of the most practical tools for approximating smooth functions. The classical results are on the set [-1, 1]; in this paper, we extend to more complicated subsets of the real line. We demonstrate some classical results and then take the result from [2] on regular Parreau-Widom Sets and extend it to semi-regular sets, defined as sets whose regular part is closed. We introduce the Regularity Coefficient as a series formed by evaluating the Green’s Function at irregular points. This new machinery is applied to the lower …

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 …

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 …

Nitrogen Addition Additively Boosts Climate-Driven Salsola Tragus (Russian Thistle) Invasion Into Southwestern Usa Grasslands, Melissa A. Bacigalupa

Biology ETDs

Effective management of invasive, non-native plants requires understanding key drivers of invasion, including nitrogen enrichment from atmospheric deposition and agriculture. Long-term studies are essential for capturing complex invasion dynamics yet remain uncommon. We used 22 years of observations and 14 years of nitrogen experiments to examine invasion by Salsola tragus (Russian thistle) into three semi-arid grasslands of central New Mexico. Invasion patterns varied, with rapid expansion in Chihuahuan Desert grassland and the Desert-Plains ecotone but stability in Plains grassland. Under ambient nitrogen, precipitation most strongly correlated with Russian thistle biomass and high native grass biomass was associated with Russian thistle …

The Nature Of Anthropogenically Driven River Drying: Spatiotemporal Causes And Consequences, Eliza Inez Gilbert

Biology ETDs

Streambed drying naturally occurs in over 60% of rivers and streams worldwide. Climate change and human regulation of surface and groundwater have increased drying in naturally intermittent systems and caused perennial systems to transition to intermittency, impacting water security, water quality, and biodiversity. To understand human-induced drying dynamics, we used 12 years of daily drying data along a 154-km regulated reach of the Rio Grande. We conceptualized river drying as a regime analogous to the natural flow regime paradigm and quantified drying magnitude, rate of change, and duration. Although linear models predicting drying magnitude and rate of change were uninterpretable, …

Explore Toolkit, Kimberly Page, Janet Page Reeves, Ivan De La Rosa, Marie Alice Scott, Christina Phillips, Maria Sanchez, Andrew Gorvetzian, Joe Albright, Cynthia Killough, Randall Benalli

Epidemiology, Biostatistics, and Preventive Medicine

Welcome to the Exploring Health Beliefs for Community Engagement and Diversity in Clinical Trials (EXPLORE) Toolkit, a resource designed to support researchers and frontline workers addressing substance use in the Borderlands. The EXPLORE Toolkit was designed by an interdisciplinary team of epidemiologists, social workers, anthropologists, and public health professionals to enhance the engagement of underrepresented communities in substance use clinical trials. Utilizing a strength-based approach, the toolkit addresses equity, stigma, and participation barriers, promoting culturally sensitive and community-centered research practices. This toolkit is an ideal tool for clinical trials researchers and community health workers who are interested in learning more …

Does Reliance On Kin Erode With Market Integration? A Social Network Perspective, Ruizhe Liu

Anthropology ETDs

Kinship has long shaped human societies. Yet globalization and market integration (MI) are reshaping social structures. This dissertation investigates how kinship-based networks persist, adapt, or erode amid rapid socioeconomic change. It draws on ethnographic and social network data from 229 Mosuo households in southwest China, a matrilineal society experiencing increasing MI, to examine shifts in everyday cooperation.

The first study analyzes fixed name-generator data and finds a general decline in kin support as MI increases, though with considerable variation. The second study uses count models to explore unbounded support networks, showing that kin ties remain central in reproductive contexts, while …

A Study Of Machine Learning Techniques In Solving Biochemical And Chemical Problems, Kenneth Micheal Plackowski

Chemistry and Chemical Biology ETDs

Data-driven approaches to solving problems in biology and chemistry require utilization of reliable techniques and machine learning algorithms are the modern reliable approach. This work presents three problems that involve use of supervised learning techniques when classification is the goal and unsupervised learning techniques when global data representation is the goal.

In the first problem, we demonstrate the use of unsupervised clustering techniques, self-organizing maps and K-means, to ascertain analyte detection capabilities of carbon nitride dots. In the second problem, we add scalability features to a functional group classification model applied to infrared data and evaluate its ability to inform …

Everyday Life In The U.S.: An Intersectional Approach To A North Korean Refugee Woman’S Identities, And Experiences, Lyounghee Kim

Communication ETDs

This dissertation examines everyday experiences of a North Korean refugee woman in the U.S., centering her narratives as sites of critique, resistance, and meaning-making. Grounded in Critical Refugee Studies, Asian American Studies, and Critical Intercultural Communication and framed by intersectionality, it explores how interlocking structures of power shape and are shaped by her life. Rather than focusing solely on trauma or assimilation, this study highlights her digital storytelling, faith, and mutual aid practices as acts of survival, dignity, and moral agency. Using a qualitative, narrative inquiry approach grounded in critical reflexivity, it thematically analyzes her stories to reveal how she …

Analyzing Environmental Health: Air Pollution And Human Health Using Geospatial Data Science, Yanhong Huang

Geography ETDs

Air pollution from industrial emissions and wildfire smoke poses growing threats to public health. This dissertation employs geospatial data science to examine these challenges through three interrelated studies. The first study investigates the relationship between maternal residential exposure to industrial pollutants and low birth weight, identifying five chemicals as significant risk factors. The second study assesses the impact of industrial air pollution on lung and bronchus cancer survival, finding that exposure to 1,1,1-trichloroethane and cobalt is associated with reduced survival. The third study explores disparities in wildfire smoke PM_2.5 exposure and its association with asthma exacerbations. Results show disparities …