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Terahertz Spin Pumping In Antiferromagnetic Crystals And Films, Gregory Fritjofson

Graduate Thesis and Dissertation post-2024

Antiferromagnetic spintronics is a budding field, promising applications for next generation computing and telecommunication, due to the inherent stability and terahertz frequency magnetic dynamics which antiferromagnets (AFMs) possess. However, due to the infancy and uniqueness of the field, AFM spin dynamics have yet to be studied to their full extent in the terahertz range. To this end, we describe a custom magnetometry system with continuous frequency operation from 60 GHz to 1.5 THz, complete quasi-optical polarization control, peak magnetic field of 9 T, temperature control from 5-300 K, and three-axis sample rotation. We provide initial results from uniaxial AFM MnF2 …

Sub-Cycle Nonlinear Optics In Solids, Dipendra Khatri

Graduate Thesis and Dissertation post-2024

The rapid advancement of digital electronics and telecommunication systems necessitates processing information at increasingly higher speeds. However, modern semiconductor technology faces fundamental physical limitations in transistor miniaturization and clock frequency due to quantum mechanical constraints. To overcome these barriers, ultrafast optoelectronics, leveraging light-matter interactions, offers a promising alternative. Light, as the fastest carrier of information, enables signal processing at frequencies far beyond conventional semiconductor technology. Advancements in laser technology have enabled stable and reliable ultrashort light pulse sources, lasting only a few femtoseconds at optical wavelengths. When utilized for signal processing, they could enable clock frequencies over 1000 times higher …

Ab Initio Studies Of Electrochemical Processes: Insights Into Co2 Reduction And Hydrogen Evolution Reactions, Theodoros Panagiotakopoulos

Graduate Thesis and Dissertation post-2024

The urgent need to reduce greenhouse gas emissions has spurred intense interest in sustainable technologies that enable both carbon dioxide (CO2) utilization and hydrogen production. This thesis explores these challenges through a combination of electrochemical simulations, surface science, and experimental validation. Central to the study is the electrochemical CO2 reduction reaction (CO2RR), which offers a promising route for converting CO2 into fuels and chemicals using renewable electricity. We begin by addressing the limitations of traditional modeling approaches for electrochemical systems. A hybrid explicit-implicit solvation model (SOLHYBRID) and an electrode potential control algorithm (TPOT) were developed to simulate the electrochemical interface …

Optical And Tunneling Spectroscopy Of Single-Layer Van Der Waals Materials On Metals And Probe Tip Engineering Of High Resolution Stm And Afm For Imaging Of Molecules On Silicon Surfaces, Stephanie Lough

Graduate Thesis and Dissertation post-2024

This research investigates the electronic, structural, and ferroic properties of two-dimensional (2D) materials, focusing on transition metal dichalcogenides (TMDs) and metal thio- and selenophosphates (MTPs). Using scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), Raman spectroscopy, and photoluminescence spectroscopy (PL), this work explores how dimensional confinement, substrate interactions, and thickness-dependent effects influence material behavior. Advancements in STM probe fabrication for high-resolution molecular imaging are also presented, with implications for nanoelectronics and quantum materials.

The first study examines monolayer MoS₂ on metallic substrates (gold and graphite). Raman spectroscopy revealed substrate-induced strain and charge transfer in MoS₂ on Au. STM …

The Influence Of Regolith Properties And Environmental Conditions On Plume Surface Interactions, Brandon Dotson

Graduate Thesis and Dissertation post-2024

When landing or launching spacecraft, the impingement of rocket exhaust can cause significant surface erosion on planetary bodies, resulting in high-velocity ejecta, formation of dust and debris clouds, or even cratering. With humans returning to the Moon, and future missions to the surface of Mars, understanding and mitigating rocket plume effects is essential for the protection of personnel and equipment. To better understand the influence of surface properties and environmental conditions on plume induced erosion rates, this study leverages a series of geotechnical measurements and small-scale plume experiments in atmosphere, cold temperatures, and reduced ambient pressures using regolith simulants. This …

Investigations And Simulations: A Data-Driven Approach To Exoplanet Characterization, Kathleen J. Mcintyre

Graduate Thesis and Dissertation post-2024

High-precision infrared photometry is fundamental to the field of exoplanet science, enabling direct measurements of planetary thermal emission, atmospheric composition, and energy redistribution. The stability and sensitivity achieved by instruments aboard the Spitzer Space Telescope provides a catalog of hundreds of transiting exoplanets with measurements of flux variations to the level of tens of parts per million. This legacy contextualizes and complements recent and upcoming high-resolution spectroscopic observations. In this work I apply multiple analysis techniques to all available Spitzer observations of three hot Jupiters to determine how much we can still learn from archival data and what best practices …

Neural Network Accelerated Retrieval Of Clear Brown Dwarf Atmospheres, Peter T. Braunschweig

Graduate Thesis and Dissertation post-2024

In the era of the James Webb Space Telescope, there is a pressing need for atmospheric retrievals to be fast, accurate, and physically motivated. The computational cost of self-consistent atmosphere models has thus far made them unfeasible for use in retrieval. Machine learning techniques have greatly accelerated computational tasks in a variety of fields, and have been applied to retrieval before. However, previous application to brown dwarfs has focused on inferring parameters from spectra tailored to the resolution and wavelength range of a specific instrument.

We train a neural network on cloud-free model atmospheres computed self-consistently with PICASO, and use …

Optomechanical Interactions And Dynamics In Nanoparticle Systems, Sohila Abdelhafiz

Graduate Thesis and Dissertation post-2024

This dissertation investigates the coupling between optical forces and the dynamics of nanoparticle systems. Using theoretical models, simulations and experiments, we explore how light mediates interactions between nanoparticles leading to optical binding, nonreciprocal forces, and collective behavior in colloidal suspensions.

We first examine the dynamics and interactions of particles under illumination due to complex electromagnetic forces. Of particular interest are interparticle forces between particles with specific optical properties such as those satisfying the Kerker scattering conditions. We demonstrate the wavelength-dependent dynamics of such Kerker dimers and establish conditions required for their stable longitudinal binding. We also describe a one-way non-reciprocal …

Spectral Properties Of Disjoint Unions Of Open Intervals Via Unitary Groups Of Local Translations, Bryan Ducasse

Graduate Thesis and Dissertation post-2024

The connection between spectral properties and tiling properties of domains can be explored by mimicking an early approach of Fuglede. This approach focuses on self-adjoint extensions of differential operators and associated strongly continuous, one-parameter unitary groups. We take this approach in this thesis, determining an explicit formula for such a unitary group and use this to create new connections between spectral and tiling properties of a domain. Dutkay and Jorgensen showed it is enough to consider the case when the domain is a disjoint union of open intervals, so we restrict the scope of this thesis to this case as …

The Nested Dirichlet Process And Applications To Nonparametric Bayesian Inference, Evan C. Donald

Graduate Thesis and Dissertation post-2024

This body of research focuses on Bayesian nonparametric inference, in regards to an array of S-valued random variables. These random variables are assumed to take values in a complete and separable metric space and further have a particular symmetry property, row exchangeability.

The Nested Dirichlet Process is a particularly apt model for inference in such circumstances. However, calculating posterior distributions in this framework is exceedingly difficult, and become exponentially more complicated as sample size increases.

This research explores the method of using sequential imputation to calculate posterior distributions, providing a rigorous proof of the method’s suitability that had been missing …

Numerical Solutions For Deterministic And Stochastic Partial Differential Equations And Effective Integral Evaluation, Guanqian Wang

Graduate Thesis and Dissertation post-2024

This thesis explores advancements in numerical methods, focusing on their applications to some classes of PDEs, Stochastic PDEs (SPDEs), and integral evaluations. The first part of this proposal provides algorithms for computing the mean curvature flow, including cases with topological changes. We propose energy-penalized and multilevel minimization algorithms. Benchmark problems with random initial conditions reveal that small changes in interaction length led to different solution patterns under topological changes. Our methods demonstrate robustness and efficiency, even with poor initial guesses, making them suitable for a wide range of scenarios.

The second part of this proposal introduces a new approach for …

Positivity And Invariance: From Radial Basis Functions To Graph Signal Spaces, Seok-Young Chung

Graduate Thesis and Dissertation post-2024

This dissertation investigates the positivity problem and zero localization of special functions or integral transforms, with particular emphasis on their implications in analysis, approximation theory, and signal processing. The first half centers on the characterization of positive definite radial functions via Hankel transforms involving Bessel functions. Motivated by classical results such as Bochner's theorem and Schoenberg’s work, we examine analytic conditions under which these transforms remain nonnegative, thereby ensuring the positive definiteness of radial basis functions (RBFs). We then explore the transition beyond positivity by focusing on the reality of zeros in Hankel (or Fourier) transforms. This leads to two …

Viability For Locally Monotone Evolution Inclusions And Lower Semicontinuous Solutions Of Halmilton-Jacobi-Bellman Equations In Infinite Dimensions, Jichao Jiang

Graduate Thesis and Dissertation post-2024

In this thesis we first study the necessary and sufficient conditions for differential inclusion driven by locally monotone operator in the sense of Liu and Röckner [J. Funct. Anal., 259 (2010), pp. 2902-2922]. The main result of our work provides a necessary and sufficient condition for a set K being viable, that is, a solution of the differential inclusion stay inside of the set K through out the time interval. We then examine the path-dependent Hamilton-Jacobi-Bellman equations (path-dependent HJB equations) associated to the optimal control problem with states controlled by evolution inclusions. With our results on viability, we …

Self Advection Of A Thin Vortex Filament In Incompressible Fluid, Gayathri Krishnan

Graduate Thesis and Dissertation post-2024

This thesis explores the self advection of a thin vortex filament in an incompressible fluid. The effect of slipping motion on the filament caused by viscosity is investigated. This problem is addressed by working with three models developed for this purpose.

The Da Rios-Betchov equations are obtained from the expression for the velocity of the vortex filament under the assumptions of local induction approximation. They describe the evolution of the intrinsic geometric quantities, namely, curvature and torsion of the filament. The invariants associated with these equations are deduced. The linear instability of the vortex filament motion obtained by Betchov is …

Advanced Subspace Estimation Techniques For Statistical Analysis And Machine Learning, Kang Li

Graduate Thesis and Dissertation post-2024

The rapid expansion of data volume and complexity across diverse domains has underscored the need for robust and efficient techniques capable of extracting meaningful information from high-dimensional datasets. Subspace estimation—identifying the underlying low-dimensional structures within high-dimensional data—has emerged as a cornerstone method in modern data analysis and machine learning. This dissertation aims to advance both the theoretical and practical aspects of subspace estimation problems.

In the first part, we investigate Fréchet central subspace estimation, a critical component of sufficient dimension reduction (SDR) challenges. Traditional SDR methods often fall short when dealing with non-Euclidean responses. To address this, we propose a …

Carleman Linearization Of Dynamical Systems, And Graph Inverse And Wiener Filtering, Cong Zheng

Graduate Thesis and Dissertation post-2024

Carleman linearization is a mainstream approach for transforming finite-dimensional nonlinear dynamical systems into infinite-dimensional linear systems. It provides accurate approximations of the original nonlinear system over larger regions around the equilibrium for longer time horizons, surpassing the capabilities of conventional first-order linearization. In Chapter 1, we derive explicit error bounds for the finite-section approximation, demonstrating its exponential convergence concerning the finite-section order. We illustrate that for a specific class of nonlinear systems, exponential convergence can be achieved across the entire time horizon, extending to infinity. These results hold significant practical utility, as the proposed error bounds can be used to …

How To Join Teams: Individual Factors That Influence An Incoming Team Member’S Understanding Of The Team’S Shared Mental Models, Madeline Filippi

Graduate Thesis and Dissertation post-2024

This study examined the effect of various individual differences on accuracy of incoming team members’ learning the team’s task and team shared mental models by leveraging literature on shared mental models and team member replacement. The four individual differences (openness to experience, perspective taking, social curiosity and trait negative affect) were hypothesized to positively impact the incoming team member’s ability to understand the team’s shared mental models through the theoretical mechanism of cue identification. Participants were asked to imagine they were entering a student organization executive team and based on characteristics (responsibilities, preferences, attitudes) of the team members in the …

The Benefit Of Benefits: The Role Of Fringe Job Benefits On The Recruitment Of Deskless Workers, Hannah A. Crandell

Graduate Thesis and Dissertation post-2024

Research indicates that the advertisement of fringe job benefits are related to positive job seeker perceptions of the organization and job pursuit intentions. Drawing from Conservation of Resources Theory, I investigate how different types of fringe benefits related to people’s motivations to obtain, enhance, or retain resources differentially attract them to an organization. The study also examines the role of financial well-being as a moderator of fringe benefits and anticipated organizational support. Further, I assess the relationship between fringe benefits and job pursuit intentions through the serial mechanisms of anticipated organizational support and organizational attractiveness. Findings suggest that fringe benefits …

Motion Extrapolation And Motion Dynamics: Are The Motion Dynamics Of Friction Utilized During Motion Extrapolation To Inform Time-To-Contact Estimations?, Genna Telschow

Graduate Thesis and Dissertation post-2024

Cognitive processing delays should cause us to respond too late when making time-to-contact estimations. According to the theory of constructivism, the brain accounts for these delays by supplementing sensory information with higher level cognitive information to create an accurate motion percept. Across the attention, memory, and motion extrapolation literatures there is evidence supporting the use of higher-level information, like motion dynamics, to supplement our visual input. Specifically, previous research suggests we may account for friction’s constraints on motion when interacting with dynamic stimuli. The current research utilizes features that represent friction as both a stopping agent and a motion catalyst …

Older Adult Centered Robot Assessment: Usability, Social Presence, And Acceptance. Building Towards A Better Robot., Jordan Sasser

Graduate Thesis and Dissertation post-2024

This dissertation investigated factors influencing older adults' perceptions of Misty, a voice-enabled social robot designed for caregiving interactions. Three sequential studies explored how voice characteristics (pitch and speech rate), robot persona (personable vs. robotic), and task guidance (Misty guiding through timed up and go and four stage balance task) influenced usability, social presence, acceptance, and perceptions of medical assistant competence. Study 1 employed thematic and quantitative usability analyses, identifying that lower-pitched, moderately paced voices optimized user satisfaction, while repetitive activation phrases ("Hey Misty") significantly reduced usability. Study 2 examined how persona framing (personable vs. robotic) influenced perceptions of social presence …

The Impact Of Virtual Backgrounds In Video-Mediated Selection And The Role Of Candidate Qualifications, Mira Gruber

Graduate Thesis and Dissertation post-2024

Videoconferencing allows users to manage their self-presentation through virtual backgrounds that mask their immediate physical environment. Prior research suggests that backgrounds depicting professional home spaces (e.g., bookshelves) elicit more favorable impressions than those that depict personal home spaces (e.g., bedrooms). Expectancy Violations Theory (EVT) provides a framework for understanding such effects. The present dissertation applied EVT to video-mediated selection interviews, that have become increasingly popular since the COVID-19 pandemic. Given the strict expectations for professionalism in interviews, virtual backgrounds that deviate from such expectations may negatively impact hiring decisions. Consequently, this work examined the impact of two virtual background types, …

Going Green: Testing An Ambient Nature Work Environment As An Employee Energy Charger, Nina D. Steigerwald

Graduate Thesis and Dissertation post-2024

Amidst rising levels of employee burnout, research on recovery from work stress has been on the rise. Organizational scholars examining predictors of recovery have almost exclusively relied on the Effort-Recovery Model (Meijman & Mulder, 1998), positing the absence of work demands as a prerequisite for resource restoration. Departing from this perspective and envisioning recovery akin to recharging a battery, the Nature Charger Model was proposed. It suggests that employee energy rejuvenation can occur even in the presence of demands. Specifically, drawing from alternative frameworks (Kaplan & Kaplan’s 1989 Attention Restoration Theory; Brosschot et al.’s 2018 Generalized Unsafety Theory of Stress), …

Retirement Adjustment: Subjective And Social Well-Being Of Retirees In Response To The Preretirement Work-Nonwork Interface, Yeeun Choi

Graduate Thesis and Dissertation post-2024

Retirement represents a significant life transition that profoundly impacts one’s subjective and social well-being. Drawing on the life course perspective, this study investigated retirement adjustment by analyzing the longitudinal patterns of well-being and the predictors influencing these trajectories. Using a mixed-methods approach, this study combined 16 years of longitudinal data from the Health and Retirement Study (HRS) (n_A = 1,470, n_B = 1,422) with qualitative narratives from retirees (n = 30) to provide a comprehensive understanding of the retirement adjustment process. The growth mixture model (GMM) analysis identified four distinct patterns in retirees' life satisfaction trajectories …

The Dual Dynamics Of Succession: Unveiling The Interplay Among The Former Leader, The New Leader, And Followers' Implicit Theories Of Leadership On Subsequent Leader Evaluations, Emily Hill

Graduate Thesis and Dissertation post-2024

Leader succession is the planned or unplanned change in formal leadership at an organization. Ample research has investigated the effects of leader succession at higher levels of leadership on team and organizational performance, yet little is known about the effects of leadership changes at lower levels of management on followers’ reactions to their new leader. Drawing on cognitive appraisal theory (Lazarus & Folkman, 1984) and contrast effect theory (Markman & McMullen, 2003), this dissertation empirically tested a model in which the congruence of followers’ implicit theories of leadership with characteristics of the new leader were expected to influence three leader-related …

The Relationship Between Adverse Childhood Experiences And Child Maltreatment Potential With Racial And Ethnic Considerations, Madison V. Verdone

Graduate Thesis and Dissertation post-2024

Referrals to Child Protective Services in the United States rise each year at a rate that is disproportionate to population growth (U.S. Department of Health and Human Services, 2022). The content of such reports includes instances of abuse, neglect, and/or suspicion of other types of violence against children. As such, it is clear that children are increasingly exposed to adverse experiences that impact their development. Understanding factors that may contribute to children’s exposure to adverse experiences may assist in breaking the cycle of intergenerational transmission. Thus, this study examined the relationships among parents’ adverse childhood experiences (ACEs), emotion dysregulation, and …

Parents’ Adverse Childhood Experiences And Young Children’S Behavior Problems: Examining Protective Moderating And Mediating Factors, Kaitlyn M. Daleandro

Graduate Thesis and Dissertation post-2024

Adverse childhood experiences (ACEs) are childhood exposures to abuse, neglect, and household dysfunction. ACEs have been linked to a cumulative negative impact on later adult physical and psychological well-being. Parents who carry ACEs often have difficulties in parenting, which have, in turn, been linked to young children’s internalizing and externalizing behavior problems. Nonetheless, some parents who carry ACEs develop positive parenting strategies. Very little is known about how such outcomes occur. A growing area of research concerns protective and compensatory experiences (PACEs) that buffer against the negative consequences of ACEs. PACEs may improve deficits in cognitive, emotional, and neurobiological systems …

Sexual And Gender Minority Identity Acceptance And The Role Of Florida Legislation Perception On Medical Disclosure And Risky Health Behaviors, Aubrianna L. Stuckey

Graduate Thesis and Dissertation post-2024

Recently, across the United States, efforts have been made to remove protective legislation and resources surrounding the sexual gender minority (SGM) community (Woodford et al., 2018). Given how quickly Florida’s HB 1557 legislation was passed and the corresponding, ongoing attempts to expand the bills, there is limited research exploring the role of legislative change on SGM communities. Newer literature indicates that discriminatory laws or bills have impacted the mental health of the SGM community, especially among SGM adolescent and young adults ; however, research exploring the role legislation has on SGM individual’s physical health, requires further investigation(American Psychological Association, 2023; …

Burnout In The Workplace- Organizational Influences On Counselor Burnout, Serene Hasan

Graduate Thesis and Dissertation post-2024

This study is a two-part manuscript dissertation that examined the impact of the six organizational influencers of burnout: Workload, Control, Reward, Community, Fairness, and Values on mental health counselors’ (MHCs) burnout, using Maslach’s three subscales of burnout: Emotional Exhaustion, Depersonalization, and Personal Accomplishment. Additionally, Work Setting and Age were assessed for their influence on MHC burnout, when the six organizational influencers were accounted for. The focus on this topic is crucial as burnout has a detrimental effect on counselors, clients, and organizations. The growing population in need of support surpasses the amount of MHCs that our nation has to offer. …

Quality Of Service Robots And Organizational Citizenship Behaviors: The Mediating Roles Of State Empathy And Perceived Organizational Support/Obstruction, Adam D. Jacobs

Graduate Thesis and Dissertation post-2024

Research on service robots is currently more conceptual than it is empirical. This thesis leverages resource allocation and social exchange theories to explain how employees choose to expend their resources depending on the functioning of the service robot. I propose that service robot quality (defined here as an employee’s perception of the usefulness and ease of use of a service robot) is an important consideration for organizations that adopt service robots, and hypothesize that employee state empathy and support (or obstruction) from their organization links service robot quality to employee organizational citizenship behaviors. The study consisted of 166 participants from …

An Involuntary Motive Of Voluntary Behavior: An Investigation Of The Causes And The Consequences Of Citizenship Pressure, Junyoung Hong

Graduate Thesis and Dissertation post-2024

This dissertation investigates citizenship pressure, defined as an individual’s perception of pressure to perform organizational citizenship behavior (OCB), by examining its conceptual boundaries, antecedents, behavioral outcomes, and underlying mechanisms. Study 1 used an item-sorting task with undergraduate participants to assess whether citizenship pressure is empirically distinct from related constructs such as OCB norms and workaholism. Substantial conceptual overlap prompted refinement of the construct and its measurement. Study 2 surveyed employees to examine how supervisor and coworker OCB demands, along with personality traits (conscientiousness and agreeableness), predict citizenship pressure at the between-person level. Although personality traits showed no direct effects, they …