Masters Theses

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Using Near-Surface Geophysical Tools to Map Giant Sequoia Roots
Gupta, Anya (Virginia Tech, 2026-06-26)
Giant sequoias are the largest trees by mass on the planet, and some of their oldest living members were saplings at the end of the Bronze Age. Beyond their role as indispensable natural wonders, sequoias have shown resilience to intense drought, disease, and fire over long temporal scales. The critical zone (CZ) beneath them is essential to the long term survival of the sequoia, yet the subsurface remains poorly constrained. We utilize near-surface geophysical methods to overcome this knowledge gap in Yosemite's Mariposa Grove of Giant Sequoias, using seismic refraction and ground-penetrating radar (GPR) to characterize soil, saprolite, fractured bedrock, and root distribution with depth. Seismic imaging reveals the structure of soil and weathered bedrock, while GPR can resolve finer-scale features like roots and fractures. This study provides the first three-dimensional characterization of subsurface structures beneath a mature giant sequoia, revealing laterally extensive and persistent features consistent with roots growing beyond the traditionally cited ~1 meter rooting depth. Our findings suggest that giant sequoia roots are visible in two distinct morphological expressions: as shallow, woody roots not extending deeper than ~1.3 m, and as root clusters extending to at least ~4.8 m deep. We interpret these clusters as regions of high volume, thin, opportunistic, feeder roots that are able to grow into bedrock fractures to access water and nutrients, suggesting that giant sequoia rooting systems may interact with deeper components of the CZ than previously documented. This knowledge could provide a framework for developing strategies to support sequoia resilience under intensifying drought conditions, and highlights the role that GPR and seismic refraction can play in protected ecosystems where root exhumation or deep coring is not possible.
Highlighting the Operational Differences and Strengths of Traditional Schlieren and Self-Aligned Focusing Schlieren Through the Imaging of Test Articles in Hypersonic Flow
Hunt, Gavin Daniel (Virginia Tech, 2026-06-26)
In the past, one of the only ways fluid flow could be visually imaged was using traditional schlieren. While this system is sensitive and can produce detailed imagery, it has several limitations. It typically takes up a large amount of room in test cells, and images all of the fluid moving between its two collimating lenses. This means that all of the turbulent air outside of the core flow can contaminate the image. In addition, contaminants and defects such as chips on the optical access windows themselves can make it harder to image flow, as they are fully in focus. A novel optical technique, self-aligned focusing schlieren (SAFS), was designed in 2021 by NASA Langley to address these issues. It utilizes polarization, a camera lens, and a reflective background to focus only on a thin optical plane inside of the test chamber and filtering out ambient light, allowing for only the desired area of the flow to be imaged. The windows of the test chamber as well as undesired flow are out of focus, resulting in a cleaner image. The purpose of this thesis was to implement SAFS at Virginia Tech, and use it to image boundary layers and shocks on test articles in Mach 6 flow at the Virginia Tech Hypersonic Wind Tunnel. The resulting imagery was then qualitatively compared to that of traditional schlieren. In order to help future SAFS researchers, best practices and setup considerations not previously covered in other SAFS papers are also discussed. It was found that SAFS is able to clearly image fluid phenomena near the test articles, and filter out the defects and contaminants on the optical access windows.
AI and Deepfakes: The Future of Political Campaigns in the United States
Williams, Emaryi Nycole (Virginia Tech, 2026-06-09)
This paper examines how individuals engage with and view the acceptability of artificial intelligence (AI), focusing on how partisanship and disclosure affect acceptability within the context of political campaigns in the U.S. This manuscript is guided by the Persuasion Knowledge Model, Motivated Reasoning, Social Identity Theory, and Cognitive Dissonance. A 2x2 factorial experiment was conducted to test the significance of both partisanship and disclosure. The experiment also tested how AI sentiment, AI knowledge, and AI skepticism all interact to impact acceptability. Results indicated that disclosure had no significance in acceptability. Further, there was no significant relationship between partisanship and disclosure on acceptability. However, the results found a significant relationship between partisanship and the acceptability of AI usage despite skepticism. The results also showed that conservative participants were more willing to vote for a copartisan candidate and accept the use of AI to a greater extent than liberal and moderate participants were for their partisan candidate, even though they perceived themselves to be less knowledgeable about AI than liberal and moderate participants. This study contributes to the theoretical understanding of political message processing in the context of AI use and offers implications for communication strategies.
"It All Goes Back to the Roots": Identity Affirmation and Career Transformation for Black American Undergraduates in Agriculture During a Short-Term Study Abroad Program in Senegal, West Africa
McLean, Nia (Virginia Tech, 2026-06-26)
Globalization has transformed agricultural systems worldwide, heightening the need for globally competent professionals equipped to address transnational food, environmental, and economic challenges. In addition to the demand for global competence, there is a need for diverse perspectives and increased representation of marginalized groups within the United States' agricultural industry. As agricultural education evolves to meet these demands, study abroad programs have become a popular tool for promoting cross-cultural awareness and career readiness. However, Black American students remain historically underrepresented in both agriculture and study abroad participation, and limited scholarship has examined their experiences in agricultural study abroad contexts, particularly in culturally resonant destinations such as Senegal. This case study addresses that gap by exploring the narratives of Black American undergraduates who participated in a short-term agricultural study abroad program in Senegal. Guided by Transformative Learning Theory and Diasporic Consciousness, the study examines how students experience dissonance, construct identity, and reinterpret career aspirations through international engagement. Findings illuminate how study abroad experiences in sites of ancestral and cultural significance contribute to shifts in self-understanding, professional purpose, and agricultural belonging. This work contributes to the broader literature on Black American participation in agricultural education and underscores the role of short-term study abroad programs in fostering identity affirmation and supporting pathways toward meaningful engagement in the agricultural workforce.
Minority Stress, Dyadic Coping, and Relationship Functioning among Interracially Partnered Q+ Individuals
Mahoney, Erin Elizabeth (Virginia Tech, 2026-06-26)
Interracial partnering occurs at higher rates among sexual minorities with 28% of men and 20% of women in same-sex marriages being intermarried compared to 16% of men and women in opposite-sex marriages (Barroso and Fry, 2021). Interracial couples report greater likelihood of discrimination, higher perceived stress, and lower overall health in comparison to monoracial couples (Pittman et al., 2023). Within the Q+ community, interracially partnered individuals experience multiple minority stressors due to each partner's intersecting identities (Cao et al., 2017; Cyrus, 2017; Jeong and Horne, 2009). Informed by the Temporal Intersectional Minority Stress model (Rivas-Koehl et al., 2023), resources like social support and coping can buffer the negative effects of minority stressors on an individual's health and well-being. The current study employed dyadic coping which was expected to minimize or buffer the negative impact of sexual minority stress on health and well-being outcomes (Bodenmann et al., 2005; Bodenmann et al., 2016). The present study evaluated associations among dyadic coping, sexual identity dissatisfaction, and discrimination. Data come from a subsample of 228 interracially partnered Q+ individuals from the National Couples Health and Time Study. Findings demonstrate a direct association between dyadic coping and relationship functioning but lack support for dyadic coping as a moderator of minority stress and relationship functioning. Future research should examine the implications of a direct association between dyadic coping and relationship functioning for this population.
Natural history and Augmentative Biological Control of the Invasive Box Tree Moth, Cydalima perspectalis, in the U.S
Rivera, David J. (Virginia Tech, 2026-06-12)
Cydalima perspectalis (Walker, 1859) (Lepidoptera: Crambidae), commonly referred to as the box tree moth (BTM), is an invasive pest threatening boxwoods (Buxus spp.) in the U.S. Native to east Asia, BTM has spread throughout Europe and the Middle East over the last 18 years and was first detected in North America in 2018. A lack of predators in its invaded range and the availability of food resources has given rise to high BTM populations, resulting in high defoliation rates. The purpose of this research was to document the phenology of BTM and the presence of beneficial arthropods of boxwoods in western New York, where BTM was first detected in the U.S. Additionally, lacewing immatures were assessed as a potential commercial biological control agent for the management of BTM. Monitoring of BTM for three years revealed two in-field generations in western New York. The first peak of activity occurred during July (summer), and the second peak was recorded during September (fall). Beneficial arthropods present on or near boxwoods were not associated with the presence of BTM larvae. The commercialized biological control agent, Chrysoperla rufilabris, was tested under quarantine laboratory conditions against BTM 1st, 2nd instars, and eggs. Chrysoperla rufilabris feed upon BTM larvae and eggs and had >60% predation by the 6th hour of exposure to prey. Targeting eggs and 1st instars using C.rufilabris can provide the best window of control due to the number of prey that can be consumed by a single lacewing larva. Currently, in western New York, the established population of BTM has been documented to have two in-field generations with not a clear relationship between beneficial arthropods collected near BTM-infested boxwoods and the presence of BTM larvae. The biological agent Chrysoperla rufilabris has the capability to prey upon BTM eggs and larvae in laboratory conditions, but further research under field conditions is necessary for implementation against BTM.
FuzzPower: Leveraging the Power of Fuzzing to Uncover the Extremes of Processor Power
Katerov, Samuel (Virginia Tech, 2026-05-07)
Power is a first-class design consideration for all modern hardware, impacting everything from performance to thermal management and system longevity. Accurate identification of peak power consumption scenarios is crucial for power delivery network design and thermal validation. However, as hardware designs scale to billions of transistors at modern single-nanometer process nodes, manually identifying, constrained-random simulation, or exhaustive exploration of the operational conditions that lead to these power peaks becomes intractable. Human engineers have no hope of divining extreme test sequences, and conventional verification techniques struggle to provide sufficient coverage to reliably trigger worst-case power events. Simulations potentially require days per scenario, hindering rapid design iteration and comprehensive analysis. Furthermore, the inability to uncover true extremes forces designers to employ unnecessarily large guard bands, leaving performance on the table and systems vulnerable to power viruses. These limitations create a critical gap in pre-silicon power validation, especially for complex designs. This paper introduces an open-source, fast, and scalable approach to identify extreme (both high and low) power consumption scenarios in hardware designs by repurposing techniques from hardware fuzzing to create a power-aware hardware fuzzer. Instead of performing a detailed power simulation for every test case, we observe that the size of the execution trace files generated during fuzzing correlates with circuit-switching activity and, consequently, with dynamic power. By analyzing trace file size variations across a large set of stimuli generated using power as a feedback mechanism for mutational test case generation, our method efficiently uncovers test sequences that induce power extremes. We build a power-aware hardware fuzzer that uses fuzzing and execution trace file size to evaluate multiple peripherals and processor cores. Our implementation identifies test cases that, on average, increase maximum dynamic power by 44%, decrease minimum dynamic power by 14%, and increase overall range by 13.6x compared with traditional dynamic power estimation methods.
Receptive Vocabulary in Early Childhood: The Roles of Infant Attention, Toddler Effortful Control, and Working Memory
de la Rosa, Isabela M. (Virginia Tech, 2026-04-06)
Early childhood is marked by rapid communicative and linguistic growth, and early language skills are indicators of later linguistic ability and developmental outcomes, including academic achievement and self-regulation. Identifying early developmental factors that support language development is therefore critical. The present longitudinal study examined the indirect relation between infant attention and later receptive vocabulary and whether temperamental effortful control moderates the mediating role of working memory. Participants were 410 children from a community sample drawn from a larger longitudinal study. At 10-months, infants’ EEG-related attention and behavioral attention were assessed during baseline video. At 24-months, mothers completed the ECBQ to assess effortful control. At 36-months, working memory was measured using behavioral and parent-report indicators. At 48-months, receptive vocabulary was assessed using a standardized measure, the PPVT. Separate moderated mediation models using 10,000 bootstrap samples yielded nonsignificant results for both EEG-related and behavioral attention predicting receptive vocabulary at 48-months. Given these findings, exploratory analyses focused on behavioral attention during a glove puppet task at 10-months and receptive vocabulary at 36-months. The index of moderated mediation was significant, suggesting the indirect association between infant behavioral attention and receptive vocabulary via working memory varied as a function of effortful control. These findings suggest that certain child-level factors may play a critical role in individual differences in language outcomes, particularly given the well-established links between language and cognition.
Beyond Gated Communities: Rethinking Growth in Santo Amaro
de Lima Weba, Lais (Virginia Tech, 2026-06-25)
Beyond Gated Communities: Rethinking Growth in Santo Amaro Santo Amaro do Maranhão is at a turning point. Once a remote village dependent on subsistence agriculture, fishing, and artisanal craft, the town now faces rapid tourism driven growth and housing development. New roads and bridges have opened access that was impossible until recent years, bringing both opportunity and pressure. The town faces a central question: how can it accommodate growth while maintaining community cohesion, protecting its fragile natural environment, and sustaining the livelihoods and cultural practices that define it? Current patterns of development threaten both human and ecological systems. Without careful guidance, neighborhoods may fragment, public services may be strained, and the landscapes that attract visitors and sustain local life risk permanent change. Historically, Santo Amaro was difficult to reach. Until the 1960s, travel to the town was only possible on foot, by horse, or by boat. In 1994, the town gained electricity, its first hospital, a bank, and grocery stores, marking the beginning of modern infrastructure. The completion of the MA 402 highway in 2001 made the town accessible to travelers, prompting locals to adapt to early tourism by adding basic facilities for visitors. Nearly two decades later, the MA 320 highway and the bridge over the Alegre River, completed in 2018 and 2019, fully connected Santo Amaro to the regional network. Unlike Barreirinhas, which is larger and already heavily developed, or Atins, which is remote and primarily accessible by boat, Santo Amaro is only five minutes from Lençóis Maranhenses National Park. This proximity has made it a focal point for investment and the fastest growing portal town, experiencing a scale of tourism the community has never seen.Tourism has become central to the local economy. Santo Amaro has roughly 14,000 residents, yet during peak season up to 4,000 visitors may arrive daily. Tourism accounts for around 87% of income, largely through lodging, services, and the sale of arts and crafts rooted in African and Indigenous heritage. While economic growth is welcomed, it has brought visible social and spatial pressures. Developers often prioritize gated communities and speculative land acquisition, with little regard for affordability, integration, or local needs. The Terra Ville Residences project, for example, attempted to build within the park's buffer zone and faced legal and environmental scrutiny before construction was halted. Other developments extend further into sensitive areas, isolating new residents and creating a visible divide between long-term inhabitants and newcomers. This divide is evident in the town's urban fabric. Residents remain concentrated around the main plaza, markets, and public services, while gated developments occupy the outskirts. Streets originally designed for pedestrian use are increasingly used by vehicles, producing noise, congestion, and reducing public space. Measures such as a parking area at the town entrance with credentialed transport into the plaza help manage tourist flows, but the spatial separation between locals and newcomers remains. The current pattern of growth underscores the need for development strategies that integrate new construction into the existing urban fabric rather than allowing isolated, fragmented expansion that undermines social cohesion. Santo Amaro's environment further complicates growth. The town sits at the edge of dunes, rivers, and tropical forests. The climate is stable, with temperatures ranging from the low seventies to the upper eighties, and rainfall defining the seasons. Flooding along riverbanks and proximity to Lençóis Maranhenses National Park require careful attention to zoning and environmental regulations. Unplanned growth in these sensitive areas risks ecological degradation, threatening both biodiversity and the natural systems that sustain tourism and local livelihoods. Addressing these challenges requires situating development within Santo Amaro's social, economic, and environmental context. Researching case studies such as eco-villages, eco-lodging and eco-houses, provides an unique guideline moving forward. Centralized mixed-use development offers the opportunity to connect residents, artisans, and visitors while minimizing ecological impact. Following frameworks such as the COTE Top Ten allows a holistic evaluation of energy use, materials, water management, and community benefit. Locating housing and communal spaces within the town, rather than on isolated plots, encourages pedestrian circulation, supports local business, and strengthens social interaction. Integrating residences with public amenities reinforces cultural and economic connections between locals and visitors. Understanding Santo Amaro's trajectory is essential. The town's transformation from a subsistence village to a tourism hub illustrates the pressures of rapid economic and social change. Reconciling development with environmental stewardship and social cohesion requires acknowledging historical evolution, current urban patterns, natural conditions, and vernacular knowledge. Development that is sensitive to these factors has the potential to strengthen the town's landscape, economy, and cultural identity rather than eroding the systems on which it relies. In this context, planning for an eco village that serves both local artisans and visitors emerges as a response to Santo Amaro's unique pressures. By concentrating housing and communal programs at the edge of the main plaza, the project aligns with the urban fabric, reinforces pedestrian circulation, and integrates with the town's social and economic life. The design supports local livelihoods and artisanal practices, creating spaces for workshops, markets, and cultural exchange while providing housing suited to both living and working needs. This model demonstrates that tourism-driven development can coexist with environmental stewardship, social inclusion, and cultural continuity. Sustainable planning provides a framework for managing tourism and housing growth while preserving the integrity of the community, its natural systems, and cultural heritage. Examining historical development, current pressures, and ecological conditions, and learning from vernacular practices and international examples, can offer Santo Amaro a path to growth that supports both residents and visitors while safeguarding the environmental and cultural assets that make it unique.
Methodological Effects on Neutral Detergent Fiber Disappearance and Degradation Kinetics in In Situ and Bag Based In Vitro Systems
Ghimire, Prashant (Virginia Tech, 2026-06-25)
Neutral detergent fiber (NDF) is a major component of dairy cattle diets, and its degradation characteristics influence rumen function, feed intake, and milk production. The nutritive value of NDF depends on the rate and extent of ruminal degradation, which are commonly estimated using in situ and in vitro techniques. However, estimates obtained from these methods can be influenced by methodological factors associated with sample preparation, incubation, and post-incubation handling. The objective of this thesis was to evaluate the effects of methodological factors on neutral detergent fiber disappearance (NDFD) and degradation kinetics in bag based in situ and in vitro systems. Chapter 2 evaluated the effects of grinding method (1-mm cutter mill vs. cyclone mill), bag preparation (acetone-rinsed vs. untreated), and washing procedures (no wash, hand wash, and machine wash) on in situ NDFD and degradation kinetics. In the absence of ruminal incubation, cyclone-milled samples showed greater NDFD than cutter-milled samples (10.0 vs. 2.8%; P < 0.01), with the greatest disappearance observed under machine washing (up to 16.4% NDFD. During early ruminal incubation (<12 h), NDF disappearance did not differ from zero for no-wash and hand-wash treatments but was greater than zero under machine washing, including at 0 h (P < 0.05). Methodological factors also affected degradation kinetics, with differences observed in lag time and uNDF, and interactions between grinding and washing influencing the estimated degradation profile. Chapter 3 evaluated in vitro NDFD between closed flask-based system and open bag-based Daisy incubator system. Forage samples were incubated in buffered rumen fluid for up to 240 h, and NDFD was used to estimate degradation kinetics. NDFD at time 0 was not different from zero in the flask system but was greater than zero in the open system, particularly under machine washing (14% NDFD; P < 0.01). The open system had greater fractional degradation rates (kd; ~0.08 vs. 0.04 h⁻¹) and lower uNDF (42% vs. 58%) compared with the flask system. Overall, the results from this thesis demonstrate that estimates of NDFD and degradation kinetics are influenced not only by forage characteristics but also by methodological factors. Early NDF disappearance observed in bag-based systems is not consistent with the expected biology of fiber degradation and is more likely associated with physical loss of particles. These findings highlight the importance of methodological standardization and careful interpretation of NDF degradation data to ensure that estimates more accurately reflect biological processes.
The Civic Life of Stadiums: A Case for RFK
Kollias, Kristopher Charles (Virginia Tech, 2026-06-25)
Stadiums have always been at the center of urban life, representing a monumental expression of civic pride, cultural identity, and leisure. From the Roman Colosseum to SoFi Stadium, they embody the collective identity of a society and serve as a reflection of the technology of their time. Yet, in the 21st century, particularly in American society, we face a crisis of identity. Money, viewership, and corporate sponsorship have become the driving force in stadium design, resulting in isolated mega-structures that sit empty most of the year. The scale, cost, and singular programming of these independent monuments disconnect them from the city they are meant to serve. In Washington, D.C., this tension is particularly pronounced. The Robert F. Kennedy Memorial Stadium (RFK) currently lies empty and decrepit, but new ownership behind the Washington Commanders has decided to tear down this outdated structure and rebuild a new state-of-the-art facility for the team within the district. The change in proximity from Landover, Maryland to Eastern D.C. brings with it several unexpected challenges for the franchise that must be addressed. Visitors to these sites pay far less attention to how the space is designed than the sport itself, which is understandable, but the building's form, presence within the city, and relationship to transit centers translates to urban identity. The Commanders must focus on this new-found relationship to the city both culturally and architecturally in hopes of fusing with the existing urban fabric. Monday, September 29th, 2025, was the final D.C. City Council meeting to approve the stadium redevelopment plan. This approval included major provisions such as the financial breakdown of contributed taxpayer dollars, totaling $1.1 Billion. Although these funds are earmarked for infrastructure and transportation improvements in the surrounding areas, there are designations like parking that are vital to the project's success. The citizens whose tax dollars are funding one-third of this stadium development deserve to reap the benefits more than a minute portion of the year. This thesis offers a real-time response to issues that directly affect all citizens of Washington, D.C., not just those that plan to benefit from site improvements. Stadiums are not simply sporting venues; they are macro-representations of regional populations expressed and broadcasted to millions weekly. There is a desperate need to re-conceive the stadium not as a self-contained object but as woven into the city's historical, cultural, and ecological networks. This thesis proposes a new typology of stadium architecture operating as an urban system rather than a stand-alone, corporate megastructure. Using the redevelopment of the RFK Memorial campus as a case study, this project demonstrates how to integrate sustainability, public space, mobility, and recreation into a performative architecture that serves both game-day operations and everyday civic life.
Wherever We Are God Is
Jones, Shaina P. (Virginia Tech, 2021-06-25)
Wherever We Are God Is, is a poetry collection that centers the coming-of-age of one and many Black femme speakers, mapping methods of becoming onto Harlem and other urban landscapes as starting points, havens, heavens, or places to recall. Time happens and unhappens, the dead rise and un- rise. This collection is autobiographical in that it documents family histories, things passed down, interrogates queerness, and does intentional naming work on behalf of the voices and experiences documented.
Anatomical and Species-Specific Variation in Acoustic Attenuation of Skin for Focused Ultrasound Applications
Edwards, Samuel Ryland (Virginia Tech, 2026-06-24)
Therapeutic focused ultrasound relies on precise delivery of acoustic energy to a focal zone for noninvasive tumor ablation and cavitation-based tissue destruction. To reach therapeutic targets, ultrasound must propagate through overlying tissues, including skin, where reflection at interfaces and frequency-dependent attenuation reduce the pressure amplitude delivered to the focus. This variability in acoustic transmission can alter focal pressure thresholds and contribute to inconsistent therapeutic outcomes. Despite increasing use of large animal models in translational focused ultrasound research, there remains limited understanding of how acoustic properties of skin vary across anatomical locations and species. The objective of this study was to quantify regional and interspecies differences in acoustic attenuation and impedance of skin. We hypothesized that distal limb regions, which exhibit greater structural density and thickness, would demonstrate higher attenuation than truncal regions within species, and that attenuation profiles would differ between pigs and horses. Full-thickness skin samples were collected from the ventral abdomen, thorax, bilateral lateral femoral regions, and distal limb (dorsal metacarpus) of pigs and horses immediately post-mortem. Subcutaneous fat was removed, and sample mass and geometry were measured prior to acoustic characterization. Measurements were performed at frequencies ranging from 1.25 to 3.25 MHz in 0.5 MHz increments. Time-of-flight measurements relative to a water-only control were used to calculate speed of sound, and tissue density was determined from mass and geometry to calculate acoustic impedance. Frequency-domain analysis was used to identify dominant spectral peaks, and attenuation (dB/cm) was calculated with correction for transmission coefficients at the water–tissue interface. Attenuation increased significantly with frequency (p < 0.0001), with an approximate slope of ~2 dB/cm per MHz across all samples. Equine skin exhibited significantly greater attenuation than porcine skin (4.04 ± 0.18 vs. 1.98 ± 0.18 dB/cm, p < 0.0001), corresponding to approximately a twofold increase across all conditions. Within species, attenuation varied significantly by anatomical location (p < 0.0001), with distal limb and proximal limb regions demonstrating the highest attenuation and truncal regions the lowest. A significant species × location interaction (p < 0.0001) indicated that regional attenuation patterns differed between species. Although median total acoustic loss through individual samples remained below 1 dB, higher-loss samples, particularly in equine limb regions, reduced transmitted pressure to as low as ~57%, demonstrating the potential for clinically meaningful prefocal energy loss. In contrast, porcine samples maintained pressure transmission above ~80% across all conditions. These findings demonstrate that both anatomical location and species significantly influence acoustic transmission through skin, with attenuation driven not only by thickness and density but also by intrinsic structural properties of the tissue. These results have important implications for focused ultrasound treatment planning, suggesting that species- and location-specific compensation strategies may be required to ensure consistent energy delivery and reliable therapeutic outcomes.
Embodied Hydrodynamic Reservoir Computing for Underwater Obstacle Localization
Wichiramala, Ken Kanate (Virginia Tech, 2026-06-24)
In underwater environments, fluid–structure interactions can provide detailed information about the surroundings. However, exploiting these hydrodynamic responses as a contactless sensing mechanism for obstacle localization remains challenging. Existing approaches often require complicated sensors or data processing methods to operate reliably in underwater environments. This study presents the design and performance evaluation of three embodied soft panels, inspired by the physiology and sensory setup of a fish's body. We demonstrate that embodied intelligence can be achieved by using a framework called physical reservoir computing (PRC), which utilizes the physical body dynamics as a computational resource. Herein, the 3D-printed panels with embedded sensing networks were designed for the pur pose of extracting their body-state information for embodied computation. The nonlinear autoregressive moving average (NARMA) task was used to evaluate their computational per formance. We show that under appropriate physical reservoir dynamics, the panels exhibited greater capability to emulate nonlinear dynamical systems and function as physical reservoir computers. Furthermore, we also show that the panels had enough computational power to estimate the position of a nearby obstacle based on variations in their body dynamics. Our results suggest that the panels can serve as potential frameworks for intelligent swimmers capable of perceiving their environments through the self-sensing mechanism and estimating relevant information.
An Exploratory Study of the Relationship between Minimum Foot Clearance and Real-World Trips
Castleberry, Asa Barrons (Virginia Tech, 2026-06-24)
Falls, frequently caused by trips during walking, are a leading source of injury and injury-related death among older adults, yet the biomechanical factors underlying real-world trip risk remain unclear. Minimum foot clearance (MFC), defined as the minimum vertical distance between the foot and ground during mid-swing, has been widely used as a surrogate indicator of trip risk; however, empirical evidence directly linking MFC to real-world trips is limited and inconsistent. Prior studies have relied on retrospective or survey-based measures and have not accounted for physical activity level, which may influence exposure to trip hazards. The purpose of this study was to examine the relationship between laboratory-based MFC measures and prospectively recorded real-world trips among community-dwelling older adults while accounting for activity level. A secondary analysis was conducted on 30 older adults who wore wrist-worn voice recorders and inertial measurement units for three weeks. Participants then completed laboratory walking trials to quantify MFC measures. Contrary to hypotheses, trippers (defined as those who tripped during real-world monitoring) did not exhibit lower or more variable MFC; instead, they demonstrated significantly lower variability. MFC measures were not associated with trip counts, while prior fall history was the strongest predictor with an inverse relationship to the MFC measures. These findings suggest MFC alone may not adequately capture real-world trip risk, which likely depends on behavioral, environmental, and perceptual factors.
Validation of Phase Modulated Pulse Compression and Investigation of Passive Multistatic Reception for Software-Defined SuperDARN
Pitzl, Allison (Virginia Tech, 2026-06-24)
In March 2024, the Blackstone SuperDARN radar was upgraded to operate using software-defined radios (SDRs), enabling flexible transmit waveform generation. This thesis validates the operation of Pcodescan, a phase-coded pulse compression mode using Barker codes, on the upgraded system. Experiments conducted in September 2025 and March 2026 characterized all available Barker code lengths and identified a sign error in the phase offset compensation of the USRP server baseband generation code, which caused erroneous velocity measurements across pulse modes used with the phase-coded waveform. The software issue was corrected and validated with a subsequent experiment in which all modes produced correct velocity measurements. Additionally, this thesis investigates the feasibility of passive multistatic SuperDARN reception using low-cost SDR hardware. A phase-coded radar identification scheme (PcodeID) was developed and demonstrated in a laboratory setting, but fundamental limitations led to the conclusion that a frequency-division approach is more appropriate. Hardware requirements and a proposed implementation are outlined, and the work was presented at the 2026 HamSCI Workshop.
Evaluation of Vegetation Characteristics from a Drone-Based Lidar Point Cloud for Estimating Floodplain Depth-Dependent Roughness
Michaelson, Nathan Daniel (Virginia Tech, 2026-06-24)
Roughness is an important variable for estimating flow and creating hydrodynamic models, but it is one of the most uncertain parameters. This parameter is the measure of friction or drag that slows the flow of water, often affected by vegetation, sediments, flow depth, and channel form. Roughness changes with different depths of flow, as increasing water height overcomes the drag forces from the bed; this concept is called depth-dependent, or relative, roughness. Equations calculating vegetative roughness from plant height and certain biomechanical properties have been developed in flume experiments. Further research testing these equations in the field, using remotely sensed data, is necessary. The current study proposes a method to calculate roughness across a site for a range of flow depths and across the channel and floodplain for Stroubles Creek at the Stream Research, Education, and Management (StREAM) Lab. Certain roughness equations were conditionally calculated based on water elevation, vegetation height, ground elevation, and location within a grid of discretized pixels. An equation was developed relating vegetation hanging into the channel onto the surface of water and roughness. Manning's n, the friction parameter, was calculated for each pixel, and a weighted average roughness value for these pixels was calculated using inverse distance weighting for the range of flows analyzed at each research bridge on site. These roughness calculations were then validated with values that were measured from in-situ velocity sensors, located at Bridges 1 and 2 at the site. This process was then applied to the entire site, resulting in a 10-cm resolution roughness raster for a range of water depths. Roughness did not strictly increase or decrease with depth; instead, roughness values had distinct trends that could be related to the spacing and type of vegetation or the location of water across the landscape. Manning's n values ranged from 0.021 to 0.033 at Bridge 1 and 0.021 to 0.034 at Bridge 2. These results were applied to hydrodynamic models for two flow events and compared to previously calibrated single roughness values for the channel and floodplain. These models found relatively low error at an RMSE of 0.061 m for the relative roughness and 0.041 m for the static roughness for one event, and an RMSE of 0.130 m and 0.122 m for the relative and static roughness approaches, respectively. Flow depths were taken from the hydrodynamic model and used to recalculate roughness, and models were run again; this method resulted in an RMSE of 0.055 m and 0.107 m when compared to measured events. Field data from groundwater wells and velocity sensors that the modeled flow depths were compared to were limited. Further work to overcome the limitations of this study would include applying this process to other sites, collecting concurrent datasets, analyzing the effects of canopy changes to roughness, or applying alternative roughness equations. Despite these limitations, this method of determining roughness allows for continual calculations of roughness through different seasons and flow events from drone flights, providing insights into the changes in roughness across these scales. Furthermore, these roughness estimates, which do not require calibration, result in directly calculated values that are comparable to calibrated values in the application of a hydrodynamic model.
Local Dynamics of Molecules in a Molecular Ionic Composite Electrolyte
Alam, Khandker Jubayer (Virginia Tech, 2026-06-23)
At the molecular level, thermal energy causes molecules to move randomly, including rotational motion. These rotational dynamics are measured by using the rotational correlation time (τ_c). Rotational correlation time describes the average timescale over which a molecule changes its orientation by about one radian through random thermal motion. Nuclear Magnetic Resonance (NMR) is sensitive to the rotational motion of molecules on the picosecond to nanosecond time scale, depending on the magnet's external magnetic field strength. The average root-mean square displacement of molecules during this rotational motion is on the Å scale. Rotational correlation time provides insight into the local environment of molecules, where longer correlation times suggest stronger local associations or restricted motion. These molecular-level insights can guide the design of next-generation ionic liquids (ILs) for electrochemical devices such as batteries. This thesis provides a framework for directly measuring τ_c of molecules such as ionic liquids on the picosecond timescale using NMR relaxation techniques. This thesis provides a framework for directly measuring the τ_c of molecules such as ionic liquids on the picosecond timescale using NMR relaxation techniques. It investigates changes in the rotational correlation time (τ_c) of cations and anions in the presence of fixed anionic groups on the rigid-rod polymer, compared to the ionic liquid state. It is hypothesized that the fixed anion on the rigid-rod polymer will alter the local dynamics of both cations and anions compared to their behavior in the ionic liquid state. In addition, this study helps evaluate how strongly the cations of the ionic liquid are associated with the fixed anionic groups on the rigid-rod polymer.
Experimental Tests of Wide Aspect Ratio Cross Laminated Timber – Steel Diaphragms for Hybrid Building Applications
Thomas, Della (Virginia Tech, 2026-06-23)
The purpose of this investigation is to identify the behavior of wide aspect ratio, cross-laminated timber (CLT) diaphragms, with steel gravity members, designed to meet the code requirements given in the 2021 Special Design Provisions for Wind and Seismic (SDPWS) (American Wood Council, 2020). To do so, three configurations with varied inter-panel connections were tested. To identify the impact of different inter-panel fasteners, metal surface splines with nails and screws were evaluated. The metal surface spline along the beam lines was then removed to test the use of the panel-beam connection as the inter-panel connection. Testing revealed an excess in strength capacity with the ASD design strength exceeded by a factor of 4.5-6 across all configurations compared to the required overstrength of 2.8. Due to the large overstrength, the diaphragm can be expected to remain elastic at design forces. Across the ASD design range, the configuration that included metal surface splines with screws had the highest stiffness followed closely by the configuration that relied on the panel-beam connection alone. The metal surface spline configuration with screws had a stiffness double that of the configuration with nails. The three deflection methods included in the investigation were able to more closely predict the diaphragm displacement when the fastener type included was limited to nails. When screws were introduced to the calculation, the deflections had larger overpredictions.
In Vitro Treatment of Equine Peripheral Blood Mononuclear Cells with Lactate, Heat, and Lipopolysaccharide
Mogge, Keely Claire-Anne (Virginia Tech, 2026-06-23)
Peripheral blood mononuclear cells (PBMCs) play a central role in immune regulation and mediating inflammation through pro- and anti-inflammatory cytokine secretion in response to physiological stressors such as exercise. Isolated PBMCs provide a controlled in vitro model to investigate exercise-induced byproducts independent of confounding systemic variables. We examined whether heat and lactate are additive or synergistic for cytokine gene expression in PBMCs. Fresh PBMC isolates were treated with lactate (0, 2, 4, or 20 mM) or lipopolysaccharide (LPS; E. coli 026:B6, 5 ug/mL final concentration) as a positive control for 1 or 4 hours at 37 °C. Heat exposure experiments incubated cells at 37 °C or 42 °C for 20 minutes or 1 hour, with additional trials combining heat and lactate. Following treatment, RNA or protein was isolated for the quantification of IL-1β, IL-6, IL-8, IL-10, and TNF-α gene expression, which was quantified using RT-qPCR, and activation of NF-κB and ERK 1/2 was assessed by Western blot. Lactate had a main effect (P ≤ 0.05), with the greatest expression of pro-inflammatory TNF-ɑ, IL-1β, and IL-8, following incubation with 20 mM lactate; the same concentration reduced expression of anti-inflammatory IL-6 and IL-10. Lactate had no effect on pS536-NF-κB, pS276-NF-κB, or pERK1/2, whereas LPS significantly increased them. RT-qPCR experiments showed that LPS signaling is 50-300 fold more potent than lactate as a PBMC stimulant. Lactate pre-treatment at 20 mM did not affect subsequent LPS-driven cytokine gene expression (P ≥ 0.05), indicating that physiological concentrations of lactate following exhaustive exercise do not seem to prime horses for a bacterial infection.

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