VTechWorks
VTechWorks provides global access to Virginia Tech scholarship, including journal articles, books, theses, dissertations, conference papers, slide presentations, technical reports, working papers, administrative documents, videos, images, and more by faculty, students, and staff. Faculty can deposit items to VTechWorks from Elements, including journal articles covered by the University open access policy. Email vtechworks@vt.edu for help.
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Virginia Tech's open access policy enables researchers to deposit the accepted version of scholarly articles with no embargo.
Theses and Dissertations
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More than 50 freely available and openly licensed textbooks are among our most downloaded items.
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Recent Submissions
Targeted Modulation of Immune Signaling Pathways in Systemic Lupus Erythematosus
Montano, Hilary (Virginia Tech, 2026-11-10)
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by hyperactive B cell activity leading to production of autoantibodies and aberrant cytokine signaling. In this dissertation, we focused on improving our understanding of the role of protein signaling pathways in SLE. We modified disease by targeting the adenosine receptor and through germline deletion of targeting the NIK protein. For our adenosine receptor studies, we utilized NZB/W F1 female lupus mice. As these mice develop clinical manifestations of lupus at about 23 weeks-of-age, we injected the mice with an Adenosine 2A Receptor (A2AR) agonist and an Adenosine 2B Receptor (A2BR) antagonist from 21-weeks-of-age to 34-weeks-of-age to determine if modification of the adenosine receptor subtypes would decrease disease severity. Overall, we found that the A2BR antagonist (ADO-5024) was able to improve various disease-associated parameters in these mice, including prolonging survival, while decreasing proteinuria, C3 renal deposition, autoantibody production, and inflammatory cytokine secretion, to be comparable to the standard treatment, dexamethasone. On the other hand, the A2AR agonist, ADO-6001, failed to reduce lupus disease. Treatment with the A2AR agonist, ADO-6001 resulted in disease parameters that were not significantly different from our negative controls. Significantly, ADO-5024 resulted in reduced plasma cell abundance and autoantibody production, demonstrating an important autoimmune role for this signaling pathway.
Using MRL/lpr lupus mice, we targeted the map3k14 gene. We found that Map3k14 deletion on the MRL/lpr background identified contrasting roles for the gene encoding for NIK in systemic immunity vs tissue inflammation. NIK is the master regulator for the non-canonical NF-B pathway which is responsible for many immunoregulatory roles. Although map3k14 KO mice rapidly deteriorated compared to their wild type and heterozygous counterparts, autoantibodies were reduced along with type 2 conventional dendritic cells (cDC2), T helper cells and their subsets, and cytokines like CCL2 and IL-5. However, there was a significant increase of C3, IgG, and SiglecF deposition into the renal tissue leading to elevated proteinuria and reduced renal function. The findings presented in this dissertation will provide a foundation to further examine the role of NIK in immune specific cell populations as NIK may have differential roles on immune cell function. Understanding cell specific pathways regarding NIK function may lead to development of more selective therapeutics for the treatment of SLE.
Antimicrobial Resistance in Livestock Systems: Resistome Ecology, Bacterial Genomics, and Antimicrobial Stewardship
Odur, Ivan Oluk (Virginia Tech, 2026-11-10)
Antimicrobial resistance (AMR) is a complex One Health challenge shaped by interactions among microorganisms, food-producing animals, agricultural environments, and antimicrobial use practices. Livestock systems can serve as reservoirs of antimicrobial-resistant bacteria and antimicrobial resistance genes (ARGs), yet the ecological factors shaping these reservoirs, the bacterial hosts carrying resistance determinants, and the human practices influencing antimicrobial use remain incompletely understood. This dissertation examines AMR across livestock systems through complementary ecological, genomic, environmental, and behavioral approaches. Chapters 2 through 5 characterize: (1) resistome ecology in sheep and goat fecal microbiomes, (2) phenotypic and genomic characteristics of Escherichia coli from small ruminants and their relationship to E. coli from other host sources, (3) antimicrobial use knowledge, attitudes, practices, and stewardship among small ruminant farmers and veterinarians, and (4) antimicrobial resistance and genomic diversity among airborne Staphylococcus associated with swine and dairy environments.
Chapter 2 characterized fecal microbiomes and resistomes of 46 sheep and goats originating from 16 farms using shotgun metagenomic sequencing. Twenty-eight antimicrobial resistance classes were identified, with tetracycline and β-lactam resistance determinants comprising the largest proportions of the resistome and blaTEM, tetQ, and tetW among the most abundant genes. ARG richness, Shannon diversity, and resistome composition did not differ significantly between sheep- and goat-associated farm-level groups. However, ecological resistome risk differed significantly among farms, whereas human health resistome risk showed weaker farm-level variation. Animal species had no detectable effect after accounting for farm structure. Analysis of ARGs and mobile genetic elements further identified extensive genomic co-occurrence between resistance-associated and mobility-associated annotations, particularly those related to transfer. These findings highlight the importance of farm-level ecological factors and mobile genetic context when evaluating AMR reservoirs in understudied small ruminant production systems.
Chapter 3 examined phenotypic antimicrobial resistance and genomic characteristics of 27 E. coli isolates recovered from sheep and goats. Resistance was observed to multiple antimicrobial classes, and 29.6% of isolates exhibited multidrug-resistant phenotypes. Whole-genome sequencing revealed substantial genomic diversity, including 20 multilocus sequence types among 26 typeable isolates, and identified combinations of antimicrobial resistance, metal- and biocide-resistance, virulence, and mobile genetic element-associated determinants. Notable isolates included a LEE-negative Shiga toxin-producing E. coli carrying stx2, subAB, iha, lpfA-O113, and tellurite-resistance determinants, as well as isolates carrying ColV-like virulence-associated features. The 27 study isolates were further compared with 56 quality-selected publicly available E. coli genomes from cattle, swine, poultry, and human sources, producing an 83-genome comparative dataset. AMR determinant richness and composition differed among host groups, with sheep- and goat-associated isolates generally carrying fewer ARGs than cattle-, swine-, and human-associated isolates. These findings demonstrate that small ruminants harbor genetically diverse E. coli, including strains carrying combinations of resistance, virulence, stress-response, and potentially mobile determinants relevant to One Health surveillance.
Chapter 4 evaluated antimicrobial-use practices, AMR knowledge, perceptions, and stewardship behaviors among small ruminant farmers and veterinarians in Virginia. Forty-eight farmers and eight veterinarians completed the respective surveys. Both groups generally demonstrated strong awareness of AMR and support for responsible antimicrobial use; however, important gaps remained between knowledge and practice. Although most farmers reported maintaining a valid veterinarian-client-patient relationship, veterinary consultation before administering antibiotics was not always routine, and greater livestock-raising experience was associated with substantially lower odds of routine veterinary consultation. Additional gaps included inconsistent record-keeping and limited application of withdrawal period knowledge. Veterinarians demonstrated high stewardship and regulatory awareness but identified practical barriers to optimal antimicrobial use, including producer engagement, economic constraints, and limitations in diagnostic infrastructure. These findings suggest that stewardship challenges in small ruminant systems are shaped not only by knowledge but also by behavioral, experiential, and structural factors, emphasizing the importance of strengthening active veterinarian-producer relationships.
Chapter 5 characterized antimicrobial resistance, stress-resistance determinants, and plasmid-associated genomic features among airborne Staphylococcus cohnii and Staphylococcus haemolyticus recovered from swine- and dairy-associated environments. Whole-genome analyses included 108 bioaerosol S. cohnii and 12 bioaerosol S. haemolyticus isolates together with phylogenetically related publicly available genomes. Among S. cohnii, ARG richness and composition were broadly similar between bioaerosol and selected public genomes, whereas the disinfectant-associated determinant qacG and cadmium-resistance determinant cadD were strongly enriched among bioaerosol genomes. In contrast, ARG composition differed substantially between bioaerosol and public S. haemolyticus genomes, with several resistance determinants enriched in each dataset. The stress-resistance determinant qacG was also enriched among bioaerosol S. haemolyticus, and plasmid-replicon composition differed between datasets. Same-contig associations among plasmid replicons, ARGs, and stress-resistance determinants further identified genomic contexts consistent with potential physical linkage, although these associations do not demonstrate horizontal transfer. These findings extend livestock bioaerosol AMR research from gene detection to viable bacterial hosts and highlight non-aureus Staphylococcus as potential reservoirs of resistance- and stress-associated determinants in agricultural environments.
The Art of Diminishing: Poetic Geometry and Generative Proportion in Tiered Temple of Kathmandu Valley
Ayer, Yusna (Virginia Tech, 2026-11-10)
Architecture is often understood through its cultural, historical, and symbolic meanings, yet the physical forms through which these meanings are expressed are governed by systems of geometry, proportion, and order. In the architecture of the Kathmandu Valley, the tiered temple represents a distinctive synthesis of cultural tradition and formal organization. While these temples have been studied through their history, symbolism, religious significance, structural behavior and spatial organization, the geometric relationships that generate and organize their vertical form remain less explicitly understood.
The complex appearance of tiered temples suggests an underlying order in the relationship between the plinth, walls, cella, and successive roof tiers. These relationships are not necessarily defined by a single fixed dimension or universally documented rule, but may instead emerge through proportional relationships, recurring geometric conditions, and transformations of form. Understanding these relationships raises the question: can the geometry of tiered temples reveal a systematic logic through which their architectural form was established and transformed?
This research investigates the geometry and proportional relationships of selected tiered temples of the Kathmandu Valley through observation, photographic measurement, digital reconstruction, and parametric modeling. By examining the relationship between width, height, tier progression, roof slopes, datum conditions, and the proportions of the temple's major components, the research seeks to identify recurring geometric relationships within the vertical composition of these structures. A Grasshopper-based parametric model is further used to reconstruct and manipulate these relationships, allowing the observed geometric conditions to be explored through controlled transformations of the temple form.
Rather than reducing traditional architecture to a fixed mathematical formula, this research approaches geometry as a means of understanding how architectural form may carry, preserve, and transform knowledge across time. The study seeks to re-discover the underlying order within the visual complexity of Kathmandu Valley's tiered temples and to demonstrate how the study of geometry can provide a bridge between cultural tradition, architectural form, and contemporary methods of digital exploration.
Optimizing Spectrum Sharing: Models and Algorithms for Coexistence
Jai, Naru (Virginia Tech, 2026-11-09)
Advancing Long Duration Energy Storage: A Multiphysics Approach to Control, CFD and Grid Integration
Ashraf, Muhammad Mubashar (Virginia Tech, 2026-11-09)
Thermal energy is one of the most important resources in our daily lives with applications across nearly every sector including energy, processing industries, and electricity generation. As technology advances, using thermal energy effectively becomes increasingly important to avoid environmental impacts, reduce the high cost of handling, and limit energy waste across industrial sectors. Also the emerging technologies offer promising ways to tackle these challenges. Thermal energy storage (TES) is one such advancement. It stores excess heat and can act as an intermediary for the load balancing problems caused by the intermittency of renewable energy resources. Energy storage is generally categorized as short duration (< 10 h), long duration (> 10 h and < 200 h), and seasonal storage (> 200 h). This research broadly studies long duration energy storage (LDES) systems, since advances in these systems can play a critical role in enabling high-penetration renewable power systems and ensuring reliable grid operation over multi-hour to seasonal timescales. Particle-based LDES is one of several key technologies that can be integrated with existing thermal power systems and that offers a low cost of storage, among other benefits. This research contributes to the advancement of these systems by (1) implementing controls in pumped-thermal energy storage (PTES) and electro-thermal energy storage (ETES), which provides a road map for control systems; (2) developing and applying a computational fluid dynamics (CFD) model to investigate the thermal performance of a key component, a novel counterflow particle fluidized bed heat exchanger (PFB-HX), with validation against experimental results; and (3) investigating the grid integration opportunities of LDES systems. The first study develops a two-layered control strategy that dynamically adjusts the critical parameters in the system. The controls are first implemented in the PTES system and then, with the relevant information carried over, translated to the control of the ETES system. In this two-layered scheme, the first layer is the main controller that provides the control signals for all operations in the LDES system, while the second layer regulates the particle flow rate in the solar receiver for the hybrid PTES system and in the PFB-HX for the ETES system to achieve a consistent temperature and power output. The study clarifies the role and importance of consistent power output, along with its impact on system parameters such as round-trip efficiency, and identifies the control parameters that contribute to the commercial scale development of the ETES system. The second study investigates the thermal performance of the PFB-HX under counterflow conditions. Because the PFB-HX plays an important role in the overall efficiency and cost of the system, this study validates the computational model against experimental results and examines the sensitivity of the drag and heat transfer models and their effect on PFB-HX performance. The result is a road map for setting up the computational strategy used to study PFB-HXs, one that balances the accuracy of the results against computational time at full scale while offering key insights into the flow physics inside the fluidized bed during operation. The third study investigates the grid integration of LDES systems, highlighting the key challenges and devising a strategy for integration through the study of key performance parameters. Across all three thrusts, this research develops the methodologies and tools needed for continued work on LDES systems while contributing to the literature by answering several key questions. Collectively, this work advances control methodologies, deepens the understanding of particle-scale thermal dynamics, and clarifies the system-level benefits of LDES. The findings provide actionable guidance for the design and operation of next-generation PTES and ETES facilities, supporting the transition to a resilient, decarbonized power grid.