Digital Commons Network^™

Planning Responses To Drinking Water System Emergencies, Jingyan Huang

Doctoral Dissertations

Despite extensive efforts to ensure clean and safe drinking water, drinking water contamination emergencies remain a persistent challenge in the United States. These events can result in widespread public health impacts, economic losses, and long-term environmental damage, particularly when triggered by hazardous chemical releases. Effective management of such crises requires a dual focus on both technical preparedness and human decision-making. This dissertation addresses these challenges through a two-part investigation that bridges pre-incident planning and post-incident response. It is guided by two core research objectives: (1) to evaluate commonly applied emergency countermeasures from both resilience and sustainability perspectives; and (2) to …

Psychological Factors Of Acting Talent And Success: You've Got "It", Lorelei Tierney Himlin

Doctoral Dissertations

The goal of an actor is to become invisible, bringing a character to life so convincingly that the audience forgets the actor exists outside the role. Different schools of acting often describe differing methods of portraying characters to this same general effect. To followers of the Meisner school, for example, “acting is behaving truthfully under imaginary circumstances” (Meisner et al., 1987). The “truthful” part involves creating a comprehensive mental model of a character’s imagined personality in order to fully embody that personality and extrapolate it to a situation. Then the actor uses a variety of acting techniques to think and …

Black Hole-Neutron Star Mergers: Numerical Relativity Studies Of Remnant Matter, Gravitational Waveforms, And Automated Simulation Workflows, Tia Kathleen Martineau

Doctoral Dissertations

Black hole–neutron star (BHNS) mergers are key sources for multimessenger astrophysics, offering insight into strong-field gravity and the behavior of matter at supranuclear densities. This dissertation presents three independent contributions to the study of BHNS systems using the Spectral Einstein Code (SpEC). First, a set of simulations spanning a range of mass ratios, black hole spins, and neutron star equations of state is used to map disruption thresholds and quantify remnant disk masses, unbound ejecta, and ejecta composition. These results are compared to predictions from remnant mass model FNH18, to assess its reliability in accurately predicting the resulting remnant masses …

Multi-Level Characterization And Testing Of Fatigue, Fracture And Creep Of The Ultra-High Strength Low-Alloy Steel Fabricated Via Laser Powder Bed Fusion, Nemanja Kljestan

Doctoral Dissertations

This dissertation presents a comprehensive experimental investigation of the mechanical behavior of an high-strength low-alloy (HSLA) steel fabricated via laser powder bed fusion (LPBF). The work focuses on fatigue strength, laser shock peening (LSP) effects, creep behavior, fatigue crack growth and fracture toughness. Fatigue strength was assessed using rotating bending tests, showing superior performance of LPBF specimens compared to as-cast materials due to the dual-variant martensitic microstructures. Laser shock peening enhanced fatigue life by inducing compressive residual stresses, delaying crack initiation and slowing crack propagation. Creep behavior was evaluated for different layer thicknesses, with thinner layers improving secondary creep resistance …

Simulations Of Perpendicular Electron Holes, James Patrick Mcclung

Doctoral Dissertations

Bernstein–Greene–Kruskal modes commonly manifest as electron holes and electrostatic solitary waves in space plasmas. These Debye-scale structures are nonlinear solutions to the steady-state Vlasov–Poisson system. Solutions in one dimension are highly tractable mathematically, observationally, and computationally, and are relatively well-understood. Higher-dimensional, magnetized plasmas are less amenable to study, however. Following a 20-year history of theoretical developments in two-dimensional BGK modes, this thesis presents the first high-resolution 2D and 3D simulations thereof. Stability conditions and phase-space dynamics are discovered and discussed. The simulated modes are ultimately compared to observed electron holes and modern width-amplitude relations. In addition, a significant portion of …

Missing Child Incidents Resulting In Death: Distinguishing Features Between False Allegations, Wander-Offs, And True Child Abductions, Madison N. Sundberg-Alley

Doctoral Dissertations

Children are reported missing in the United States for a multitude of reasons every year. Often, law enforcement is tasked with investigating these disappearances and recovering the missing child. In some instances, determining the reason why a child is missing can be challenging. This study focuses on three types of missing child episodes that result in fatality: child abduction homicides (CAH), false allegations of child disappearance (FACD), and wander-offs (WO). This exploratory analysis contributes to a gap in the literature by identifying some possible differences between case types that may assist police in determining the likely explanation for the disappearance. …

Analyzing Regions For The Study Of Localized Fluctuations In The Ground Magnetic Field For The Development Of A Global Risk-Assessment Forecast, Michael Kavanagh Coughlan

Doctoral Dissertations

The dynamic relationship between the solar wind and the Earth's magnetic field can produce rapid changes in the geomagnetic field measured on the ground ($dB_H/dt$). The fluctuations can be highly localized, with differences of up to 100s of nT/min in a small geographic area. The field of space weather is entering a more data-driven era, with enormous amounts of publicly available datasets from satellites and ground measurements. In this work modern machine learning techniques were employed to make forecasting risk-assessment predictions of large and localized $dB_H/dt$, and model explainability methods were employed to understand the non-linear connections being made. These …

Computational String Theory Using Machine Learning, Giorgi Butbaia

Doctoral Dissertations

Low-energy couplings of certain superstring theories are related to the masses of the particles. One of the most promising superstring theories is $\mathcal{N}=1$ supersymmetric $E_8\times E_8$ heterotic string theory. In a certain embedding of the standard model into $E_8\times E_8$ gauge group of the heterotic string, the particle spectrum consists of $(\mathbf{27})^3$, $(\overline{\mathbf{27}})^3$, $(\mathbf{1})^3$ and $\mathbf{1}\cdot \mathbf{27}\cdot\overline{\mathbf{27}}$ couplings. While the $(\overline{\mathbf{27}})^3$ couplings are quasi-topological, the $(\mathbf{27})^3$ explicitly depend on the Ricci-flat metric on Calabi-Yau.

In this dissertation, we explore recently developed techniques for calculating the normalized Yukawa couplings on various Calabi-Yau manifolds. In Chapter 2, we describe a novel architecture, …

Counting Kelp: Development And Assessment Of Modelling Approaches To Improve Understanding Of Kelp Bed Abundance And Resilience In The Gulf Of Maine, Constance N. Tyler

Doctoral Dissertations

Kelp habitats in the Gulf of Maine are threatened by rising ocean temperatures and marine invasions. The replacement of kelps with red turf macroalgae fundamentally alters these habitats and disrupts the ecosystem services they provide. Thorough assessment and monitoring of kelp habitats is needed for proper conservation of these habitats, but most long-term monitoring is performed using traditional survey methods that are restricted in the amount of space they can cover. Habitat modelling approaches are required to expand our knowledge of Gulf of Maine kelp habitats, and to better understand the interactions between kelp and red turf habitats across the …

Verifying Interchange Reconnection Models For Magnetic Switchbacks Using The Parker Solar Probe And Mms, Emily Owen Mcdougall

Doctoral Dissertations

Ever since their initial observation by the Ulysses probe, many models of magnetic switchbacks were put forth, but relatively little empirical evidence exists to verify these models, especially in terms of the ions that make up the accompanying plasma. I take energetic particle data from the Parker Solar Probe within switchbacks to provide experimental evidence to bolster the interchange reconnection driven models with particular interest in the interchange reconnection driven linear model. Statistical Analysis of switchbacks in the vicinity of CMEs, solar flares, and high-speed streams show properties consistent with the linear interchange reconnection model, and an analysis of switchbacks …

The Assessment Of Language, The Language Of Assessment: Understanding How Language Teachers Support Dynamic, Communicative Language Learning Through Assessment, Rebecca Kelley

Doctoral Dissertations

As language classrooms in K-12 schools in the United States seek to promote students’ proficiency in the language they teach and to prepare students for a multilingual world, the role of assessment in these classrooms is often overlooked. This study draws from theories of formative and dynamic assessment, as well as a socially-constructed view of language and language learning, in order to examine the way in which secondary language teachers plan for, elicit, interpret, and use evidence from classroom assessments in such a way that promotes and supports the language learning happening in the classroom. Through a series of three …

Fine Structure Of Magnetic Reconnection: Impact On Reconnection And Dissipation Rates, Steven Ver Bryck Heuer

Doctoral Dissertations

Magnetic reconnection is a fundamental process in magnetized plasmas where stored magnetic energy is converted to heat and kinetic energy. The objective of this thesis is to examine the role of small-scale structure of the reconnection region and the background plasma conditions on the rate that reconnection converts and dissipates magnetic energy. This is done using in situ data from NASA’s Magnetospheric Multiscale (MMS) mission and particle-in-cell (PIC) simulations of reconnection for different regimes. First, we introduce a new technique for measuring the reconnection rate and demonstrate its accuracy for the simplest regime of reconnection. Next, we show that it …

Resolving The Role Of Wave-Induced Pressure Gradients On The Movement Of Sediments In Nearshore Environments, Melissa Marry

Doctoral Dissertations

Characterizing the hydrodynamic forces responsible for the initiation of sediment motion is fundamental for improved understanding of large-scale sediment transport processes in nearshore environments. Traditional sediment transport models assume incipient sediment motion is only driven by the force applied by bed stress (Bagnold, 1966; Shields, 1936) while more recent work has shown that incipient motion is influenced by the forcing of the horizontal pressure gradient due to surface gravity waves (Foster et al., 2006; Frank et al., 2015; Sleath, 1999). Wave-induced vertical pressure gradients can also destabilize the sediment bed through the process of momentary liquefaction (Florence et al., 2022b; …

Technologies To Support Remote Work For Collaborative Groups, Alberta Ansah

Doctoral Dissertations

The nature of work continues to evolve, particularly in the aftermath of the COVID-19 pandemic. While a substantial number of employees have returned to traditional, in-person work environments, many continue to engage in remote or hybrid work arrangements. Online meetings are a significant aspect of remote work, and while there has been a significant increase in this area, there are still aspects of these meetings that are not fully understood. Existing research in this area has primarily focused on the development of tools to facilitate meeting execution and content management. In contrast, relatively few studies have explored the social dynamics …

Eastern Oyster, Crassostrea Virginica, Genomics In A Well-Mixed Estuarine System: Examining Population Structure, Viability, And Response To Stressors, Alyssa Strickland

Doctoral Dissertations

Eastern oysters, Crassostrea virginica, are foundational estuarine species that contribute to a variety of ecosystem services including water filtration, nutrient cycling, habitat creation, and shoreline protection. However, populations have declined due to disease, overharvesting, habitat loss, and climate change, especially in northern systems such as New Hampshire’s Great Bay Estuary (GBE), located in the Gulf of Maine, one of the world’s fastest warming waters. This dissertation uses genomic and transcriptomic approaches to understand the drivers of population structure, decline, and resilience in GBE oyster populations, aiming to aid restoration and aquaculture. Chapter 1 used low-coverage whole-genome sequencing to understand population …

Uncovering The Plant-Microbe-Permafrost Paradigm As It Relates To Soil Priming And Arctic Carbon Cycles, Sean Robert Schaefer

Doctoral Dissertations

Permafrost, or perennially frozen soil, covers approximately 25% of the northern hemisphere and contains over half of the world’s soil organic carbon stocks. Permafrost-affected regions are rapidly warming, resulting in ecosystem changes including permafrost thaw and a shift from sedge-dominated to shrub-dominated plant communities. As permafrost thaws, it releases previously unavailable compounds to plants and microorganisms. Plant root inputs can then stimulate the decomposition of thawed permafrost, increasing greenhouse gas emissions in a process called priming. Permafrost thaw increases the decomposition of previously frozen soil organic matter (SOM); however, the extent of decomposition is highly dependent on plants and their …

Temporal Variability In The Bulk Nutritional Quality Of Estuarine Plankton, Marley Gonsalves

Master's Theses and Capstones

The temporal variability of plankton is well documented, particularly in constantly changing tidal systems such as estuaries, but the extent to which this variability applies to plankton nutritional quality is less well known. As the base of the aquatic food web, variation in phytoplankton nutritional quality stands to constrain fishery production, particularly of filter-feeders. Here, community and nutritional data was collected from Great Bay, NH, a model estuary, over seasonal, tidal, and daily time scales to identify the range and variability of nutritional quality in plankton. Bulk spectrophotometric neutral lipid and protein measurements were compared to plankton community composition data …

Differentiated Learning In An Upper-Level Undergraduate Physics Theory Course, Christina Gurney

Master's Theses and Capstones

‘One-size-fits-all’ education aims to cater to the ‘average’ student, but the ‘average’ student does not exist. Students are individuals, each with a set of needs, abilities, preferences, and interests unique to them. A variety of instructional approaches should thus be used to differentiate students’ learning. This differentiation has been studied mostly for K-12. My study extends this research into an upper-level undergraduate physics theory course. For this phenomenographic pilot study, I interviewed ten students about the differentiated homework assignments in their upper-level undergraduate classical mechanics course at the University of New Hampshire. I performed an issue-focused analysis of the data, …

A Geoacoustic Bayesian Inversion For Large Calibrated Singlebeam Echosounder And Ground Truth Datasets, Andrew Paul Niedbla

Master's Theses and Capstones

This thesis describes the development of a geoacoustic inversion technique to estimate seafloor sediment characteristics that is designed for use with existing fisheries survey single beam echosounder (SBES) datasets. The geoacoustic inversion technique consists of a forward model and inversion algorithm. The forward model is a high frequency, physics-based, near normal incidence acoustic backscatter model enhanced with a density depth gradient model and geoacoustic sediment regressions. The inversion algorithm is a parallel tempered Markov-chain Monte Carlo Bayesian inversion. The geoacoustic inversion produces posterior probability distributions for mean grain size, density, porosity, sound speed, seafloor roughness characterization, and sediment volume scattering …

Geotechnical Site Characterization Of Offshore Soils From Free Fall Penetrometer Testing For The Application Of Offshore Systems, Emma J. Dennis

Master's Theses and Capstones

As the offshore industry has expanded, innovative anchor systems need to be designed to meet the unique geotechnical engineering constraints presented by offshore sediments, as well as address the constraints presented by offshore industries such as renewable energies or aquaculture systems. For the design and application of successful anchor systems, a thorough understanding of the geotechnics and behaviors of offshore sediments is a necessity. Thus, geotechnical site characterization for proposed infrastructure locations is a vital first step through methods such as sample collection, laboratory analysis, and in-situ testing. Currently, there are often high costs associated with establishing the required soil …

Laying The Foundation For A Tartary Buckwheat Breeding Program For The Northeast: Phenotypic Characterization Of Seedling Traits And Hybridization Techniques, Julia Oliveira Barreiro De Jesus

Master's Theses and Capstones

Tartary buckwheat (Fagopyrum tataricum) is an underutilized crop with the potential to address key challenges in modern agriculture, including food security in the context of climate change and growing resource scarcity. It is valued for its tolerance to abiotic stresses such as drought, cold, and marginal soils, making it a promising candidate for cultivation in the Northeastern United States, a region where average temperatures have risen by approximately 0.25 °C per decade since 1970. These climatic shifts have led to changes in snow-to-rain ratios, earlier phenological events, and increased intensity of precipitation events, particularly in spring, posing challenges for early …

Low-Temperature Performance Evaluation Of Additive Modified Asphalt Mixtures, Adeniran Oluwatobiloba Coker

Master's Theses and Capstones

The incorporation of additives in asphalt mixtures is an innovative method of improving the performance of asphalt pavement and promoting economic and environmental sustainability in asphalt pavement construction and maintenance. However, the long-term performance of various additive-modified mixtures under different climatic and traffic conditions, as well as the aging effect of additives, is still being studied. The various types of additives and processes for incorporating additives into asphalt mixtures significantly impact the performance of asphalt pavements modified with additives. This study focused on the low-temperature cracking performance of various additives, including rubber, plastic, and aramid fibers, incorporated into asphalt mixtures …

A Mixed-Methods Approach To Describe Typologies And Fiber Consumption Patterns Of Hispanic/Latino Adults Grouped Using Cluster Analysis, Nicholas Clarke

Master's Theses and Capstones

AbstractBackground: Hispanic/Latino adults in the United States experience disproportionate rates of obesity and diet-related chronic diseases yet remain underrepresented in obesity research. Traditional “one-size-fits-all” nutrition interventions have demonstrated limited effectiveness in this population, largely due to substantial heterogeneity in cultural, socioeconomic, and behavioral factors that influence dietary patterns. Objectives: The overarching goal of this project was to further characterize previously identified subgroups within the Hispanic/Latino population to provide a foundation for future tailored interventions that address the specific needs and preferences of these subpopulations. Specific aims were to: 1. Describe cluster typologies using a virtual nominal group technique (vNGT) with …

Toxin-Producing Cyanobacteria In Green Manure Microbiomes, Alyssa Nicole Daigle

Master's Theses and Capstones

The increasing reliance on inefficient synthetic fertilizers, which readily leach from soils and contribute to downstream pollution, underscores the urgent need for more sustainable nutrient sources, such as green manures (GMs). Floating aquatic plants like duckweeds are particularly promising candidates due to their natural abundance, rapid growth rates, and ability to efficiently uptake nutrients. However, the presence of toxin-producing cyanobacteria in duckweed microbiomes raises concerns about the potential for toxin accumulation, like microcystins (MCs), both in the GM biomass and in the edible crops to which it is applied. To evaluate the suitability and safety of duckweed-based GMs, we conducted …

“Lead”Ing Industrial Science: Studying Occupational Lead Poisoning In The Early 20th Century, Rebekah E. Dreyer-Rowe

Master's Theses and Capstones

Lead was essential to the creation and coalescence of industrial hygiene as a discipline in the United States from its early days in the 1910s through the 1930s when the first professional associations of industrial hygiene were formed. In the early years, Alice Hamilton was central to the burgeoning field, and her seminal study on lead poisoning in Illinois industries thrust both her and her methods into the spotlight. Industrial hygienists of her generation followed her methods and came away with similar conclusions: that occupational diseases were rampant in the US, even if few people were studying them. In the …

Assessing The Application Of Mobile Light Detection And Ranging In Complex Mixed Species Forest Inventory, Hunter Thomas Moore

Master's Theses and Capstones

Understanding forest dynamics relies on forest inventories that assess stand- and tree-level characteristics. Traditionally, this process involves field-based measurements of tree attributes such as diameter at breast height (DBH), height, form, and crown metrics. In recent years, the integration of remote sensing technologies, particularly Light Detection and Ranging (LiDAR), has expanded the spatial and temporal reach of forest inventories. LiDAR is an active remote sensing device that generates three-dimensional representations of forest environments and can be used to derive structural forest metrics. More recently, mobile LIDAR, also referred to as mobile laser scanning (MLS) has emerged as a flexible and …

Assessing Satellite-Derived Bathymetry Map Accuracy: A Comparison Of Manual And Algorithmic Icesat-2 Bathymetric Extraction Methods And The Impact Of Depth-Weighted Sampling, Andrea Granger

Master's Theses and Capstones

Satellite-derived bathymetry (SDB) provides a cost-effective and scalable approach for large area bathymetric mapping in remote, shallow nearshore environments, where conventional techniques such as ship-based sonar or airborne LiDAR bathymetry (ALB) are often costly and logistically difficult. Since its launch in September 2018, NASA’s ICESat-2 satellite has emerged as a valuable source of cost-effective training data for SDB mapping. However, ICESat-2 photon event (PE) data exhibits significant noise, and existing literature has yet to thoroughly investigate whether algorithmic denoising methods can achieve comparable performance to the traditional manual extraction approach. Furthermore, ICESat-2’s limited depth penetration results in shallow-biased PE data, …

Modeling Ungulate Population Parameters Across Human-Modified Landscapes, Sarah Richard

Master's Theses and Capstones

As human activity and development continue to alter natural landscapes, large ungulates are increasingly exposed to changing habitat structures, altered mortality risks, and climate-related stressors. These ecological shifts can influence their survival, behavior, and population dynamics. Understanding how such complex and evolving conditions shape demographic trends in these species is critical for effective management. In this thesis, I examined two ecologically and culturally important ungulate species, white-tailed deer (Odocoileus virginianus) and moose (Alces alces), across human-modified environments. Specifically, I analyzed how intrinsic factors, behavioral development, and landscape composition influence stage-specific mortality in deer neonates and population parameters in moose in …

Investigating The Offsets Between The Clumped Isotope Signatures Of Various Species Of Benthic Foraminifera, Ceara Hogan Yourell

Master's Theses and Capstones

For much of the last half century, the primary tool for reconstructing ancient ocean temperatures was the oxygen isotope paleothermometer. However, this method is fundamentally limited by its reliance on assumptions about the δ¹⁸O value of seawater, which introduces uncertainty into paleotemperature estimates. The clumped isotope paleothermometer (Δ47) offers a promising alternative by directly measuring the stochastic "clumping" of heavy isotopes (¹³C and ¹⁸O) within the carbonate lattice—a process governed solely by temperature and independent of seawater isotopic composition (Ghosh et al., 2006; Eiler, 2007). While Δ47 paleothermometry has been applied successfully in diverse contexts, including reconstructing extinct animal body …

Beech Bark Disease Agent Responses To Exogenous Application Of Tree Defense Inducing Phytohormones, Erin Reilly

Master's Theses and Capstones

Pathogens and insects face several barriers to successful infection and colonization of a host plant, including a range of physical and chemical defenses, some of which are inducible (modified or initiated by attack or infection). These interactions can be complex and are influenced by environmental conditions, tree physiological status, host age, and timing of attack. Non-native pathogens and insects can have an advantage against a plant’s evolved chemical defenses, but they are also subject to abiotic stressors and conditions. In North America, beech bark disease (BBD) is a disease complex where the beech (Fagus grandifolia) host is subject to concurrent …