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The participation of the partitioning protein para in the coordination of the bacterial cell cycle in Caulobacter crescentus
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Stephanie Puentes-Rodriguez, accepted the attached license on 2025-04-25 at 17:20.The student, Stephanie Puentes-Rodriguez, submitted this Dissertation for approval on 2025-04-25 at 17:27.This Dissertation was approved for publication on 2025-04-28 at 15:07.DSpace SAF Submission Ingestion Package generated from Vireo submission #21995 on 2025-10-19 at 18:11:04The maintenance of chromosome after the completion of each cell cycle is a process required for all life propagation. In the bacterium Caulobacter crescentus, chromosome replication initiates at the origin of replication ori, and segregation does not begin until the centromere-like region parS is replicated, coordinating the onset of both replication initiation and segregation. However, our understanding of this exquisite coordination remains limited. We use the model organism C. crescentus in this study due to its dimorphic life cycle that allows separation between its nascent and mature populations, which can then be utilized to study the initial stages of the cell cycle. In C. crescentus, the active segregation of the chromosome is mediated by the tripartite ParABS system. One of its components, the partitioning protein ParA, is an ATPase which forms dimers that bind DNA nonspecifically and are released from the chromosome upon ATP hydrolysis. In this bacterium, the segregation of parS involves steps such as: release from the polar anchoring protein PopZ, initial slow movement to mid-cell and then fast movement to the opposite cell pole through the partitioning protein ParA. In this thesis, we expand on roles for ParA beyond the active segregation of the chromosome. Our data revealed that disrupting the levels of ParA results in cells displaying multiple origins of replication (oriC) in a DnaA-ATP dependent manner. We found these aberrant rounds of replication are also observed when expressing ParA variants deficient in chromosome segregation. We also observed that ParA promoting the initiation of replication also affects cell length, albeit this connection suggests different ParA variants may impact these processes independently of each other. These data suggest that ParA’s ability to impact chromosome replication initiation is an indirect effect from altering the cell cycle, and the connection still needs to be elucidated. We have also observed that the separation of the ParB/parS complex from the cell pole is a highly regulated step that involves ParA’s competing attractions between PopZ and non-specific DNA binding. Interfering with this balance by favoring either PopZ interactions with ParA or DNA binding results in an inability of parS to separate from the cell pole and culminates in cell death. We showed that a ParA variant that localizes with PopZ blocks the ability to release the ParB/parS complex from the cell pole, resulting in cells with multiple ParB/parS loci trapped at the pole, and this accumulation of ParB/parS complexes is dependent on interactions between ParA and PopZ. Together, these data suggest that the initial steps in chromosome separation are tightly controlled. We have also investigated in more depth the interactions between ParA, the partitioning protein ParB, and PopZ to understand the behavior of these proteins that drive chromosome segregation and cell cycle progression. Using a previously established Escherichia coli system, we examined that the ParA gradient can be reconstituted in E. coli using a ParA-ATP monomer and a PopZ unable to interact with ParB, suggesting that ParA’s gradient localization depends on interactions with PopZ. These preliminary data were then observed in C. crescentus, using a strain with native ParA fluorescently tagged to visualize gradient formation, and noted that the ParA gradient may be triggered by overexpression of ParA. Lastly, we also observed that ParA variants that bind ParB or DNA stall the ParB/parS complexes in ΔpopZ cells, and this stalling results in cell death, highlighting the importance of the equilibrium of these proteins for cell cycle progression. Collectively, these preliminary data suggest that the interactions between ParA and PopZ drive ParA localization, although fundamental questions about ParA’s behavior in vivo require further study. Overall, our data provide new insights into the interconnected network required to progress the bacterial cell cycle. Our work reveals that ParA participates in processes upstream of centromere (parS) segregation, such as chromosome replication initiation and parS release from the polar anchoring. These data also shed light into the fundamental questions that remain to be answered about ParA’s behavior in vivo, such as its localization in C. crescentus, and the importance of furthering our understanding of universal processes in cell cycle progression
An epidemiologic approach to free-ranging wood duck (Aix sponsa) health assessment
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, John Winter, accepted the attached license on 2025-04-28 at 17:20.The student, John Winter, submitted this Thesis for approval on 2025-04-28 at 17:28.This Thesis was approved for publication on 2025-05-08 at 09:59.DSpace SAF Submission Ingestion Package generated from Vireo submission #22050 on 2025-10-19 at 18:11:08The wood duck (Aix sponsa) is a medium-sized perching duck and is one of the five most commonly harvested waterfowl species in the Mississippi Flyway. However, this species was threatened with extinction in the early 1900’s due to habitat loss combined with unregulated hunting practices and has only recovered with the help of extensive hunting limitations, habitat restoration, and the implementation of nationwide wood duck nest box installation programs. This study set out to perform a comprehensive health assessment for normal baseline characterization of wood duck health and identification of possible wood duck disease threats for the first time in the North American Mississippi Flyway. Physical examination, complete blood counts, plasma biochemistry, protein electrophoresis (capillary zone electrophoresis and agarose gel electrophoresis), and pathogen surveillance via PCR was performed on 253 free-ranging wood ducks over August and September of 2022-2024 in northeastern Illinois. The most common clinical abnormalities observed included: beak abrasions (n = 118, 48%), pododermatitis (n = 32, 13%), small defects (circular or irregular holes) in the interdigital webbing of the feet (n = 20, 8%), sinus arrhythmia on cardiac auscultation (n = 10, 4%), small abrasions/wounds on the face or head (n=9, 4%), auscultated pulmonary crackles (n = 8, 3%), and raised nodules on toes and feet webbing (n = 7, 3%). The four diagnosed pathogens via PCR included duck hepatitis B virus (n = 20, 12%), Riemerella anatipestifer (n = 87, 51.2%), an adenovirus previously isolated from a Pacific black duck (Anas superciliosa; n = 7, 3%, referred to in this study as PBDA1), and a novel adenovirus hereafter referred to as wood duck adenovirus 1 (WDA1; n = 4, 2%). A single individual with WDA1 was observed with an oral ulcer, but no other pathogens were associated with clinical lesions or bloodwork changes. Hemoparasites morphologically consistent with Haemoproteus spp. and Plasmodium spp. were commonly diagnosed (n = 98, 62.4%) with no associated clinical abnormalities. References ranges for complete blood counts, plasma biochemistry, plasma vitamin levels, capillary zone electrophoresis and agarose gel electrophoresis were created from 163 wood ducks. This study serves as an epidemiologic study template for future waterfowl health assessments and helps provide baseline information critical for success of future wood duck conservation medicine efforts
A proposed methodology for human operator modeling and development of a virtual operator model for control of a simulated compact track loader
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Orson Wang, accepted the attached license on 2025-05-07 at 10:48.The student, Orson Wang, submitted this Thesis for approval on 2025-05-07 at 10:55.This Thesis was approved for publication on 2025-05-08 at 17:42.DSpace SAF Submission Ingestion Package generated from Vireo submission #22053 on 2025-10-19 at 18:11:09A methodology for performing Human Operator Modeling (HOM) using a Caterpillar Model 299D3 XE Compact Track Loader (CTL) is presented. The proposed method uses task analysis techniques to decompose a material excavation and moving task into smaller, individual tasks presented in a task list. A method for verifying and refining the task list is presented, along with a procedure for identifying relevant human operator sensory information and analyzing human decision making in the context of CTL operation. This methodology involves interviewing experienced expert human operators and analyzing the expert operator's performance of a task. A potential interview format and question list and a sensor suite potentially suitable for capturing the human sensory information present at the operator position of a Caterpillar Model 299D3 XE CTL is proposed. A method for analyzing the data recorded of an expert operator and a method of quantifying the expert operator's performance are also presented. This methodology is then partially verified through the analysis of a non-expert human operator in simulation. The proposed sensor suite is emulated to the extent possible on a model CTL in Vortex Studio, a realistic construction equipment simulator. A modified test course is executed by a non-expert human operator in the simulation environment, and the recorded data is used to create a quantitative HOM. From this, a Virtual Operator Model (VOM) feedback controller simulating the performance of a human operator is developed. The VOM is implemented using a state machine to transition between individual tasks. Fuzzy Logic Control (FLC), is implemented for each task to control bucket tilt, arm lift, and throttle, with controller parameters calculated from the quantitative HOM data. The VOM controller is verified using the same test course performed by the human operator. The performance of the human operator is compared to that of the VOM controller in order to validate the HOM and VOM methodology for a simulation environment
Inferring communication pairs in end-to-end encrypted messaging applications
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Tala Aoun, accepted the attached license on 2025-04-29 at 01:11.The student, Tala Aoun, submitted this Thesis for approval on 2025-04-29 at 01:14.This Thesis was approved for publication on 2025-04-29 at 15:23.DSpace SAF Submission Ingestion Package generated from Vireo submission #22059 on 2025-10-19 at 18:11:12Modern messaging platforms have widely adopted end-to-end encryption to secure user communications. However, encryption alone does not prevent adversaries from leveraging traffic analysis techniques to leak information and communication patterns. This poses significant risks, particularly in environments where metadata surveillance is used to suppress dissent, track activists, or monitor sensitive exchanges, such as those between journalists and whistleblowers. In this study, we analyze the extent to which an attacker monitoring network traffic can accurately determine the identity of a target user’s communication partner based solely on the encrypted traffic. We construct a model of user behavior based on real-world messaging data from WhatsApp, simulating communication scenarios and mapping them to observable network traffic patterns. Our approach identifies key metadata features such as message timing, packet sizes, and delivery notifications that enable traffic correlation. Our findings provide actionable insights for enhancing privacy in encrypted messaging applications and highlight the need for stronger defenses against metadata-based surveillance
Hydrogel platform to investigate progression of drug-resistant glioblastoma
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Victoria Kriuchkovskaia, accepted the attached license on 2025-05-01 at 13:35.The student, Victoria Kriuchkovskaia, submitted this Dissertation for approval on 2025-05-02 at 09:13.This Dissertation was approved for publication on 2025-05-02 at 14:55.DSpace SAF Submission Ingestion Package generated from Vireo submission #22155 on 2025-10-19 at 18:11:29Acquired drug resistance in glioblastoma (GBM) presents a major clinical challenge and is a key contributor to its poor prognosis, with a median overall survival of less than 15 months. Current treatment strategies offer limited benefits to most patients, despite the use of an aggressive multi-modal treatment approach. The front-line chemotherapeutic agent, temozolomide (TMZ), fails to eradicate residual and highly invasive tumor cells following surgical resection and radiotherapy. While some patients initially respond positively to TMZ, GBM cells often develop resistance, leading to only a modest four-month increase in median overall survival with TMZ included in the treatment regimen. With no effective second-line therapy currently available, there is a pressing need for more clinically relevant in vitro GBM models that can elucidate the complex mechanisms underlying acquired TMZ resistance and inform the development of novel therapeutic interventions to combat this lethal malignancy. Indeed, many existing models for assessing drug response overlook the role of the extracellular matrix (ECM) and the broader tumor microenvironment (TME)—critical elements that contribute to the aggressive nature of GBM. Additionally, those that do consider these key factors often use supraphysiological drug concentrations, which can lead to misleading conclusions. Investigating how the standard-of-care treatment drives phenotypic and mechanistic changes in GBM progression within three-dimensional (3D) ECM models could uncover key insights for identifying novel therapeutic targets. This dissertation describes a bioengineering approach to develop increasingly sophisticated and physiologically relevant in vitro biomaterial models to systematically evaluate drug response in GBM. Herein, we report 3D engineered models of acquired TMZ resistance using two isogenically-matched GBM cell line pairs encapsulated in methacrylamide-functionalized gelatin (GelMA) hydrogels. We benchmark the responses of TMZ-resistant versus TMZ-sensitive cell lines within the GelMA-based ECM platform and further validate drug response at physiologically relevant TMZ concentrations. Our findings demonstrate changes in drug sensitivity, invasive capacity, and matrix-remodeling cytokine production resulting from acquired TMZ resistance. Additionally, this dissertation sheds light on the relationship between TMZ treatment and the go-or-grow plasticity of GBM cells. This platform lays the groundwork for future investigations into how key components of the GBM TME (e.g., vascular, stromal, immune, etc. niches) influence tumor response to therapeutic interventions. Although this platform primarily focuses on TMZ, it also examines other small-molecule therapeutic agents and discusses how the established model systems could be adapted to study alternative therapeutic modalities. By advancing our understanding of GBM progression following chemotherapy, this work proposes novel strategies to mitigate the devastating impact of GBM. Indeed, systematic evaluation of shifts in cellular response to front-line therapies has the potential to guide the development of more effective treatment strategies, and robust bioengineered 3D in vitro assays are uniquely positioned to probe the under-explored GBM TME in a systematic and accessible manner
One-way coupling of surface vibration and Kármán vortex street instability
No full textSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Derrick Wiberg, accepted the attached license on 2025-05-05 at 14:54.The student, Derrick Wiberg, submitted this Thesis for approval on 2025-05-05 at 15:09.This Thesis was approved for publication on 2025-05-07 at 09:14.DSpace SAF Submission Ingestion Package generated from Vireo submission #22214 on 2025-10-19 at 18:12:46An experimental study of the one-way coupling between a vibrating surface and the Kármán vortex street flow instability was conducted to identify criteria for effective flow control via fluid structure interaction. This investigation was motivated by the desire to inform the design of passive metamaterials for flow control wherein spectral scales of structural dynamics are matched with those of fluid instabilities. To that end, the interaction between the periodic vortex shedding in the wake of a cylinder and a surface vibrating at equivalent or near-equivalent frequencies of this flow instability was examined. Wind tunnel experiments at Reynolds numbers ranging from Re = 1.3 × 10^4 to Re = 3.7 × 10^4 were conducted to evaluate wall pressure and flow field characteristics in the wake of a circular cylinder located near a vibrating wall section. By actively controlling the surface vibration, the effects of the vibration frequency and amplitude on vortex shedding behavior were studied. Other parameters of interest to the fluid-structure coupling were also examined including the proximity of the vibrating surface to the cylinder and the freestream conditions. It was determined that through active excitation of the vibrating surface, the vortex shedding behavior could be biased to phase-lock with the surface motion. This phase-locking effect was facilitated by the proximity of the excitation frequency to the mean shedding frequency combined with high displacement amplitude to produce sufficient spectral power in relation to the baseline vortex shedding spectral power. Additionally, it was determined that physical proximity of the vibrating surface to the source of the instability (in this case, the underside of the cylinder), along with test conditions at lower Reynolds numbers resulted in greater phase-locking authority. The phase-locking phenomenon was found to be correlated to a subtle increase in overall circulation in the near-wake, suggesting a sustainment of circulation due to surface vibration. Phase locking was also accompanied by significant alterations to the dominant spatial modes of the resulting flow, as identified by proper orthogonal decomposition. These results obtained through active one-way coupling will provide a helpful basis for the design of passive two-way coupled materials for flow control of a variety of flow instabilities
Analyzing decomposition of diisopropyl methylphosphonate (DIMP) in high-explosive detonations using absorption spectropscopy and gas concentration measurements
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Kaitlyn McKenzie, accepted the attached license on 2025-05-08 at 09:32.The student, Kaitlyn McKenzie, submitted this Thesis for approval on 2025-05-08 at 09:44.This Thesis was approved for publication on 2025-05-09 at 11:25.DSpace SAF Submission Ingestion Package generated from Vireo submission #22267 on 2025-10-19 at 18:13:56A weapon of mass destruction (WMD) is defined as a device or weapon that contains an agent or toxic capable of causing death or serious injury through biological or chemical means. WMD threats are present both foreign and domestic. In particular, the use of highly toxic organophosphorus nerve agents is a significant concern for national security. In response to this threat, work is being done to develop methods for destroying nerve agents through the use of fireballs. Various chemicals are being developed to add to the explosive that create the fireball, with the aim of finding the most efficient way to neutralize the nerve agents. To quantify the effectiveness of the explosive and the chemical additives, techniques such as absorption spectroscopy are employed. This research focuses on the development of a secondary system, composed of gas sensors, to measure products formed from the detonation of a chemical nerve agent surrogate, Diisopropyl Methylphosphonate (DIMP). Gas concentration measurements of the products (CO2 and O2) can be used to verify the absorption measurements for the decomposition of DIMP. Absorption measurements of DIMP are obtained using rapid scanning, broadband absorption spectroscopy with measurements taken at approximately 2.3kHz, covering a wavenumber range of 925 – 1350 per scan. Spectra are collected both before and immediately after detonation to measure the changes in both the DIMP peak and its products peak. By comparing the absorption and gas concentration measurements, a high sensitivity of the gas concentration measurements was observed, which presents challenges of verifying the absorption measurements
Design and verification of a current source inverter
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Michael Stoens, accepted the attached license on 2025-05-08 at 22:40.The student, Michael Stoens, submitted this Thesis for approval on 2025-05-08 at 23:07.This Thesis was approved for publication on 2025-05-09 at 13:34.DSpace SAF Submission Ingestion Package generated from Vireo submission #22278 on 2025-10-19 at 18:13:59The rapid shift toward electrification in various industries necessitates significant advancements in the power density, reliability, and fault tolerance of electric drive systems. This research investigates inverter topologies for driving higher power density in electric motors, particularly slotless permanent magnet synchronous machines (PMSMs), which eliminate iron stator teeth to reduce weight. However, the reduced inductance in these machines introduces challenges for the inverters that drive them. These low inductance machines have rekindled interest in Current Source Inverters (CSIs), which are well-suited for driving such systems due to their inherent ability to maintain a constant input current. This study evaluates different inverter topologies with an emphasis on minimizing total harmonic distortion (THD) in their current waveforms, as well as their related power density and fault tolerance. Challenges associated with implementing a CSI are addressed, and a CSI is designed and tested to use as a benchmark for various inverter topologies
Examining the impact of targeted DEIB lessons on the sense of belonging in Black, male-identifying, special education high school students: Challenges, outcomes, and future directions
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Kelly Fishman, accepted the attached license on 2025-04-01 at 08:58.The student, Kelly Fishman, submitted this Dissertation for approval on 2025-04-01 at 09:04.This Dissertation was approved for publication on 2025-04-10 at 14:26.DSpace SAF Submission Ingestion Package generated from Vireo submission #21705 on 2025-10-19 at 18:17:55This mixed methods study investigates the impact of targeted Diversity, Equity, Inclusion, and Belonging (DEIB) lessons on the sense of belonging among Black, male-identifying, special education students in a Northeast Ohio suburban high school. Recognizing that these students often face compounded marginalization due to race, gender, and disability status, this research examines how DEIB initiatives, specifically through the Anti-Defamation League’s No Place for Hate program, influence their sense of inclusion and acceptance within the school environment. Utilizing pre- and post-intervention surveys, this study measures students' perceived belonging across various dimensions, including peer interactions, teacher support, and respect for identity differences. The findings reveal that while DEIB lessons fostered a generally positive school climate, Black, male-identifying, special education students reported lower levels of belonging compared to their peers. The results underscore the need for intersectional approaches in DEIB programming that address the unique challenges faced by students with overlapping marginalized identities. Implications for educational practice include more comprehensive teacher training, culturally responsive pedagogy, and expanded resources for inclusive classroom environments. Future research should explore longitudinal impacts of DEIB lessons on marginalized students’ educational outcomes, enhancing our understanding of how to create truly inclusive educational spaces
Examining educational outcomes: A mixed methods evaluation of farmer-to-farmer initiatives and innovation lab paired assignments in Malawi and Zambia
Get PDFSubmission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-10-19 without embargo termsThe student, Annette Donnelly, accepted the attached license on 2025-04-01 at 12:54.The student, Annette Donnelly, submitted this Dissertation for approval on 2025-04-01 at 13:06.This Dissertation was approved for publication on 2025-04-07 at 10:41.DSpace SAF Submission Ingestion Package generated from Vireo submission #21707 on 2025-10-19 at 18:17:56Sub-Saharan African (SSA) smallholder farmers, cultivating two hectares or less, face historically low adoption rates of modern agricultural practices, limiting their benefits from agricultural advances. While much has been written on SSA farmer adoption, proven education models remain scarce. This dissertation evaluates the effectiveness of unique Farmer-to-Farmer (F2F) volunteer assignment models developed during COVID-19 travel bans, where local volunteers were virtually paired with U.S. experts and USAID Feed the Future Innovation Labs in soybean and peanut. The study examines adoption and satisfaction under three F2F assignment types: (1) traditional U.S. volunteer assignments, (2) local volunteers paired with U.S. experts, and (3) local volunteers paired with Innovation Labs (IL). Adoption is measured through yield increases, farmer satisfaction, peer-to-peer training, and gender-related adoption differences. Using a convergent mixed-methods approach, the study evaluates 101 F2F assignments in Malawi and Zambia (2019–2023), integrating quantitative surveys with qualitative insights on learning, knowledge transfer, and yield improvements. The study is grounded in Rogers' Diffusion of Innovations, Freire’s Critical Pedagogy, and Bandura’s Social Cognitive Theory, the study explores participatory extension models and their role in adoption. Results indicate that all models improved farmer outcomes, though value chain sensitivity and high variability limited some statistical significance. IL-assisted assignments resulted in higher satisfaction, particularly in implementation confidence. However, climatic events and resource access (e.g., improved seed varieties) played a significant role in adoption outcomes. Cooperatives with higher percentages of female members had statistically significant higher yields. Despite this, there was disparity on how men and women viewed gender equity in sharing financial benefits from harvests. Many women stated that benefits were not shared. Time of instruction was also important, analysis suggests that 25 hours are optimum, before returns dissipate. Peer-to-peer dissemination of best practices, the cascade effect, increased with cooperative size, aligning with participatory learning models where social interaction empowers farmers and enhances engagement. Findings emphasize contextualized education, demonstrating that peer influence, dialogue, and observation enhance adoption and sustainability, regardless of assignment type, informing programmatic recommendations to strengthen F2F smallholder extension strategies in SSA