University of Tennessee Institute of Agriculture
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Kinship, Diet, and Ecosystem Services of Insectivorous Bats
No full textThis dissertation explores the genetic, behavioral, and dietary development of the Mexican free-tailed bat (Tadarida brasiliensis), and the diet of insectivorous bats more broadly. The first chapter examines maternal behavior and the potential role of kinship in non-parental nursing. Using microsatellite and single nucleotide polymorphism genetic markers to assess relatedness between nursing females and pups, I show that while most nursing occurs between mothers and their offspring, a notable proportion of non-parental nursing may involve other genetically related individuals. This suggests that kin selection may be involved in the evolution of nursing behavior in this species, and that their sociality is likely more complex than we realize. The second chapter focuses on the development of the juvenile diet during the critical transition from milk to independent foraging. Molecular analysis of the juvenile diet using next generation sequencing shows that juvenile bats initially consume a broader range of arthropod prey than adults, with dietary composition shifting as juveniles age. Notably, juvenile males exhibit greater dietary diversity than juvenile females, suggesting possible sex-based differences in behavior or resource use. These bats likely experience a two-week learning curve upon fledging before approaching an adult-like diet. The third chapter examines the occurrence of pest and beneficial insects in bat diets across the globe and looks for patterns of consumption by geography, habitat type, and bat feeding guild. The presence and variety of both pest and beneficial insect taxa in the majority of bat diets raises many opportunities for deepening our understanding of the ecological importance of bats in human-dominated landscapes. Together, these studies fill in population-level gaps in the natural history of Mexican free-tailed bats and contribute insights ranging from behavioral to community ecology
Distributed and Approximate Quantum Circuits for Noise Resilience and Security
No full textQuantum computing promises to solve complex computational problems that classical computers struggle to solve efficiently. Quantum arithmetic circuits serve as essential building blocks among the quantum circuits necessary to implement quantum algorithms like quantum approximate optimization, Harrow–Hassidim–Lloyd (HHL), and quantum cryptanalysis. However, the Noisy Intermediate Scale Quantum (NISQ) era quantum computers that are available today face significant challenges like noise, decoherence, and low quantum gate fidelity. They have limited qubits and connectivity, restricting the complexity and scalability of quantum circuits. Attackers can utilize these issues to introduce critical vulnerabilities, such as crosstalk, stuck at 0/1 attacks, and errors in state preparation and quantum gates to deduce quantum states or potentially inject faults. This work focuses on resolving these challenges for quantum arithmetic circuits using alternate computing paradigms, such as distributed quantum computing and approximate computing, to create scalable quantum arithmetic circuits suitable for both NISQ and Fault Tolerant Quantum (FTQ) machines. This work presents distributed quantum arithmetic based on the Residue Number System (RNS), which distributes quantum addition or multiplication across multiple quantum modulo circuits, allowing for parallel execution over multiple jobs or quantum computers. RNS-based Distributed Quantum Addition (DQA) and multiplication offer multiple advantages like lower overall depth and scalability beyond the existing qubit capacity. To enable RNS based distributed quantum arithmetic, this work proposes: i) a quantum carry-lookahead modulo (2n - 1) adder that operates with logarithmic complexity, in contrast to existing solutions that have linear complexity; ii) quantum modulo (2n + 1) adders; and iii) a quantum modulo (2n + 1) multiplier. We also find DQA superior than non-distributed addition against noise and crosstalk attacks on ion-trap qubits. We then present five Approximate Quantum Adders (AQA) possessing constant depth, that demonstrate superior noise resilience compared to linear depth-based quantum full adders. Three of these AQA also demonstrate attack resilience against state preparation, gate and crosstalk attacks, although the exact adders fare better against the stuck at 0/1 attacks. In conclusion, this work lays the foundation for utilizing alternative computing paradigms to develop higher resilience against noise and attacks in quantum circuits
Image-based Localization in Dark and Turbid Underwater Environments
No full textThis dissertation explores robust localization methods for autonomous underwater vehicles in dark and turbid underwater environments. This dissertation addresses poor visibility, suspended particles, and limited features, which hinder real-time visual perception and localization. It aims to develop innovative techniques that can enhance image quality, estimate motion blur parameters accurately, and improve camera pose estimation, ensuring reliable underwater navigation.
The primary aspects this dissertation considers and the main contributions are as follows.
Underwater Image Restoration and Enhancement: A dual transmittance estimation-based method integrating boundary constraints and local contrast estimation with adaptive ambient light estimation and color correction, is proposed. In addition, a transformer-based feature fusion framework is designed by combining physical model-estimated transmission parameters, which can enhance the visual quality and robustness of underwater images.
Motion Blur Parameter Estimation: A cepstrum morphological feature-based method is developed for estimating motion blur parameters, combining frequency-domain feature extraction and least squares ellipse fitting. This approach can accurately estimate blur angle and scale parameters, improving the performance when handling small-scale blurs typical in underwater imaging.
Transformer-Based Image Enhancement Guided by Physical Blur Estimation: An improved transformer-based image enhancement framework that performs physical blur estimation via Wiener filtering is developed. The explicit incorporation of the point spread function-related information enables precise restoration of image structures and details, outperforming conventional image enhancement techniques.
Monocular Camera Pose Estimation: A monocular pose estimation method based on a parallel perspective error model is developed. This model utilizes a line segment error propagation model to enhance the stability and accuracy of pose estimation, achieving high performance in both simulated and real-world underwater scenarios.
Experiments confirm that the proposed image restoration and enhancement methods outperform existing techniques in subjective visual effects and objective quality metrics. The motion blur estimation method demonstrates high effectiveness in small-scale blur scenarios, and the proposed pose estimation method can improve the localization accuracy of underwater robots. The research findings have significant application potential in underwater robot navigation, environmental monitoring, and underwater exploration. Future research could focus on optimizing computational efficiency, extending the application scenario types, and exploring more efficient sensor fusion strategies
Chemical tools for the independent interrogation of isopentenyl and dimethylallyl pyrophosphate metabolism
No full textIsopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) are the central, five-carbon precursors, to all isoprenoids. Despite their significance, exogenous, independent delivery of IPP and DMAPP to cells is not possible as the negatively charged pyrophosphate renders these molecules membrane impermeant. In this dissertation, we present a chemical strategy for the isomer-specific delivery of IPP and DMAPP using self-immolative, ester-protected (SIE-IPP and SIE-DMAPP) analogs. These analogs mask the negative charge of the β-phosphate of IPP and DMAPP allowing passive diffusion of the protected analogues across membranes. Once inside the cell general esterase activity initiates cleavage of the SIEs, resulting in release of IPP and DMAPP. Using these analogs, we demonstrate effective intracellular delivery in U-87MG human glioblastoma cells, where SIE-IPP or SIE-DMAPP rescues growth during statin-induced inhibition of isoprenoid biosynthesis. We extend this approach to the Gram-positive bacterium Bacillus subtilis, where SIE-IPP and SIE-DMAPP similarly restore growth under inhibition of isoprenoid biosynthesis. Furthermore, we demonstrate that side products generated during the intracellular cleavage of the analogs are biologically inert compared to the released IPP and DMAPP, confirming that both rescue and toxicity arise specifically from the released isomers. We then extend this strategy to directly track isoprenoid biosynthesis by synthesizing a stable isotope-labeled analog of DMAPP (¹³C₃-SIE-DMAPP) to monitor its incorporation into native isoprenoids. Using this probe, we demonstrate that DMAPP-specific incorporation into menaquinone-7 (MK-7) depends on isopentenyl pyrophosphate isomerase (IPPI) activity, and that the ability of B. subtilis to grow solely with IPP or DMAPP is determined by IPPI expression. Finally, we apply ¹³C₃-SIE-DMAPP to reveal the spatial compartmentalization of isoprenoid biosynthesis during sporulation in B. subtilis, highlighting distinct isoprenoid biosynthesis between the mother cell and the endospore. Collectively, this work establishes a versatile chemical toolkit for the isomer-specific delivery and isotopic labeling of IPP and DMAPP in living cells. The creation of SIE-IPP and SIE-DMAPP facilitates the investigation of isomer-specific isoprenoid metabolism in native biological contexts, opening new avenues for exploring prenyl metabolism, terpene biosynthesis, and the regulatory mechanisms that control cellular isoprenoid homeostasis
Exploring the Performance and Applications of a Novel Refueling and Waste Management Strategy in LEU- and Thorium-fueled Molten Salt Reactors
No full textInterest in advanced, Generation IV nuclear reactors for commercial electricity production has increased in recent years as the U.S. and many nations around the world seek to transition to clean, carbon-free electricity generation. In particular, liquid-fueled Molten Salt Reactors (MSRs) were selected by the Generation IV International Forum (GIF) as one of the six most promising advanced reactor designs for potential development. Innovative fuel cycles for liquid-fueled MSRs hold promise in solving current challenges in nuclear energy, such as used fuel minimization and management and radionuclide production for medicine and industry. In this work, a novel fuel cycle concept for liquid-fueled MSRs operating with low enriched uranium (LEU) and thorium-based fuels is studied in detail in a small, 400 MWt, thermal spectrum MSR model. The safety and overall performance of this fuel cycle with LEU and thorium fuels will be investigated, in addition to fuel cycle applications such as radionuclide production for nuclear diagnostic procedures and innovative targeted radionuclide therapies for cancer
Understanding Acute Responses in Ex-vivo Brain Tissue Using Microfluidic Technology
No full textAlzheimer’s disease (AD) is a progressive and irreversible neurodegenerative disease that is pathologically defined by the accumulation of amyloid plaques and neurofibrillary tangles. A few of the common symptoms of AD include memory loss, confusion of time and places, changes in mood or behavior, among other things. These symptoms are due to a breakdown of synaptic connections between damaged neurons beginning in brain regions like the entorhinal cortex (EC).
The suprachiasmatic nucleus (SCN) is also thought to be affected by AD pathology as disrupted sleep is another common symptom of AD. In this work, we investigated the response of these two brain regions after being exposed to AD associated peptides, amyloid-beta (Ab) and tau.
We have demonstrated that within the first 12 hours of exogenous peptide exposure, both the EC and SCN exhibits cell death and Ab, specifically, increases lactate dehydrogenase (LDH) release. To further expand on this research and answer more specific questions about changes in tissue due to peptide exposure we developed a novel microfluidic device. We demonstrated that Ab and tau can induce an increase in intracellular calcium similar to potassium chloride depolarization. Additionally, we have shown that Ab:tau stimulation leads to cell death, specifically microglial cells, within the EC. Upon targeting the ryanodine receptor with dantrolene to block the release of calcium from intracellular calcium stores, increases in fluorescence intensity due to intracellular calcium changes are still observed. However, we observed more healthy cells in the EC and SCN tissue stimulated with Ab and tau in the presence of dantrolene as well as a reduction in LDH released. For the first time, dynamic response to exogenous Ab and tau exposure via real-time changes in intracellular calcium concentrations has been shown. The results presented here elucidate changes in the brain that occur with the onset of AD before cognitive symptoms may occur
Cultural Perspectives on Research Compliance: Exploring International Masters Students from Confucian-Heritage Cultures Conducting Research in the United States
No full textAbstract
Now more than ever, we are becoming a globally internationalized society. Each year, many international students, particularly those from Confucian heritage countries such as China, Korea, and Taiwan, travel to the United States (U.S.) to pursue a graduate degree that requires research. These CHC sojourners face several challenges, as they must navigate new academic requirements for performing research and writing academic papers. Additionally, they have the challenge of learning and applying the specific rules and regulations that explicitly govern the use of live animals for research.
Currently, there is limited research addressing the adjustment of CHC international students in the U.S., and even less exploring those who perform graduate research with animals. The literature reviewed and data collected offer deeper insights into the intercultural experiences of CHC master’s students during their transition into animal research with non-USDA-covered animals while in the U.S. Five CHC sojourners were interviewed using a qualitative phenomenological approach. The data analysis revealed that CHC sojourners encounter multiple challenges while performing research in master’s programs in the U.S., including linguistic and cultural barriers; difficulty with research rules comprehension and training; and a lack of mentorship. This study can be useful across multiple disciplines in higher education, including education, research, and healthcare. This research topic is an important area of study as it identifies the gaps in the current literature and the findings may inform future practice, policy, and research regarding the experiences and needs of CHC graduate students and serve to promote recognition of the above challenges for not only the study participants (CHC students), but as well as Asian sojourners in general, while conducting any research
Confronting the Pedestrian Safety Crisis: Exploring Injury Severity and Underlying Mechanisms
No full textIn this dissertation, I examine the sharp rise in pedestrian fatalities in the United States and globally. In the U.S., pedestrian deaths increased by over 80% between 2009 and 2022. I investigate how factors such as roadway design, trip purposes, socio-economic conditions, and vehicle design trends have contributed to this increase. I also introduce a new method for understanding how pedestrians perceive safety in low-income South Asian cities, which carry a significant share of the global pedestrian fatality burden.
I use Tennessee as the primary case study due to its nearly threefold increase in pedestrian fatalities since 2009, closely reflecting national trends. My goal is to identify how road, vehicle, and pedestrian characteristics influence the likelihood of fatal outcomes in crashes. I take a mixed-methods approach across three main chapters using state police crash data. In the first chapter, I analyze the relationship between roadway design and fatal pedestrian outcomes. In the second, I explore spatial and socio-economic disparities, supported by crash narratives processed with artificial intelligence (AI). In the third, I assess how vehicle characteristics—specifically height, weight, and age—interact with posted speed limits to influence injury severity. I also include a perception-based survey from Kathmandu, Nepal, to understand how pedestrians in low-income urban areas perceive safety in the absence of reliable crash data.
My findings show that fatal pedestrian crashes are more likely on high-speed urban arterials, in non-intersection areas, and where pedestrian infrastructure is lacking. Risk has grown in suburban areas, especially for people walking for essential needs. A key insight is that urbanizing suburban spaces have shifted walking behavior faster than infrastructure has adapted. While larger vehicles increase injury odds at low speeds, changes in the vehicle fleet alone do not fully explain the rise in fatalities.
Survey responses from South Asia highlight the importance of basic infrastructure in shaping pedestrians’ sense of safety, especially along multilane or narrow roads.
I conclude that rising fatalities are linked to high-speed roads, evolving built environments, and socio-demographic vulnerabilities. While long-term progress depends on vehicle design and walking behavior, immediate improvements require speed management and baseline infrastructure
Bending the Blueprint: Constricted Migration Effects on Nuclear Architecture in Cancerous and Non-Cancerous Cells
No full textMetastatic cancer cells must be able to deform their nuclei exerting large amounts of forces on it and its contents as they traverse throughout the body to reach a secondary site of proliferation. The forces put on the nucleus during the migration through tight constrictions are enough to alter the 3D genome structure of the cells. But we still do not fully understand what causes these alterations, if the 3D genome could play a role in migration capability, or if all cells experience the same effects and consequences from constricted migrations. The work in this dissertation aims to answer four main questions: what happens to the 3D genome structure as cells pass through constrictions? What, if any, 3D genome profiles can be selected for better constricted migration? What are the similarities and differences between cancerous and non-cancerous cells that experience constricted migration? And lastly, when do changes arise during sequential constricted migrations? Chapter I addresses what happens to the nucleus morphology and 3D genome structures of A375 melanoma cells after they pass through 10 rounds of migration. Chapter IV later focuses within that time frame to determine when the changes to nuclear morphology and 3D genome structures first arise. Chapter II aims to answer the questions of selection vs induction for why some cancer cells within a tumor have better capabilities to be successful at constricted migration. Chapter III then explores how constricted migration is experienced and potentially recovered from in innately migratory, non-cancerous fibroblasts. This chapter details some similarities and more differences between these fibroblasts and our previous cancer data. Overall, these findings suggest that the 3D genome of cancer and non-cancerous cells plays a role in migration efficiency and can be initially selected for or forced to change to become highly migratory, but only in cancerous cells
The Influence of Membrane Lipids and Novel EphA2 Ligands on EphA2 Structure and Function
No full textReceptor tyrosine kinase (RTK) signaling plays a critical role in human development and maintaining homeostasis. When these proteins are overexpressed and/or misregulated they often act as drivers for oncogenic phenotypes. While much is known about the structure and signaling outcomes of these receptors, there lacks an understanding of the factors that regulate their structural dynamics that are associated with a non-diseased versus a diseased state. It is further unknown how these structural dynamics coincide with cellular outcomes or activities. Here we develop SiMPull-POP to quantitatively capture the structural dynamics of the RTK EphA2 and characterize the factors that regulate these dynamics. Furthermore, we investigate the activity of EphA2-interacting partners as a function of the factors regulating EphA2’s structural changes. We find that cholesterol content inhibits oncogenic assembly and activation of EphA2 and this is mediated by homeostasis of the cAMP/PKA signaling axis (Chapter I). We further characterized how other RTKs, such as IGFR1, physically interact with EphA2 to inhibit ligand-induced EphA2 assembly (Chapter II). Lastly, we investigated how EphA2 is able to elicit differential assembly states and activation modes in response to novel EphA2 ligands (Chapter III). These findings add to the knowledge of the relationship between protein structure and function, which is vital to designing future therapeutics