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Investigation of Laser Based Flow Diagnostics with Metastable Argon
No full textThe overarching motivation of this work is the development of seedless, non-intrusive, laser-based diagnostics for supersonic airflow in wind tunnels. To advance this goal, this dissertation fo-cuses on three-photon excitation in a research-grade argon beam within a tabletop vacuum system, which offers a controlled environment for testing and refining the approach. The chosen excitation scheme drives argon atoms to the 3d[5/2]₃ state using a pulsed Ti:Sapphire laser system, enabling time-of-flight (ToF) measurements on atoms that subsequently undergo a multi-step decay to the metastable 4s[3/2]₂ state. Although full realization of this excitation scheme was hindered by technical challenges, including instability in the Ti:Sapphire oscillator and limitations of the ag-ing Nd:YAG pump laser, significant progress was made in beam characterization and diagnostic development. In particular, Doppler shift measurements were conducted using an 811.754 nm de-tection laser to extract the average velocity of an RF-induced metastable argon beam, yielding a value of approximately 440 m/s. Complementary ToF measurements were performed by pulsing a 801.699 nm quench laser with an acousto-optic modulator (AOM) to depopulate the metastable state; the temporal delay between the quench pulse and observed fluorescence dip provided a secondary estimate of the beam velocity yielding an average velocity of approximately 468 m/s. The number density of metastable argon in the atomic beam used for these measurements was com- pared to the number density of argon in a Mach 6 wind tunnel, indicating that if even a small
fraction of argon can be driven to the metastable state, detection in wind tunnels is viable. These measurements were instrumental in optimizing the detection geometry, estimating the characteristic velocities of the atomic beam, and establishing feasibility for implementation in wind tunnels. A Ti:Sapphire amplifier was also designed and constructed to overcome power limitations in the nonlinear excitation scheme. While a gain of 1.3 was achieved at low input energies, gain saturation at higher energies limited the amplifier’s utility for three-photon excitation. Nevertheless, the diagnostics and amplifier performance data developed in this work provide a strong foundation for future iterations of the experiment
The Impacts of Physical (In)Activity on Endothelial Function
No full textExercise and physical activity are known to have beneficial effects on endothelial function and vascular health. Sedentary behavior and physical inactivity, however, have been shown to be related to poor endothelial function and vascular health. The overall purpose of this dissertation was to further elucidate the physiological links between physical (in)activity and vascular health. In the first study, 12 active, young (18-40 yr) individuals and 12 active, old (55+ yr) individuals were recruited. Participants underwent 5 days of removal of exercise, and had their endothelial function assessed via flow-mediated dilation (FMD) during their normal, habitual exercise state (EX) and during 3 and 5 days of removal of exercise (NOEX). While removal of exercise reduced FMD in both groups in the brachial (%) (Old: EX: 7.20 ± 0.60; NOEX: 5.45 ± 0.91; Young: EX: 5.97 ± 1.14; NOEX: 6.90 ± 0.93; p=0.035) and popliteal (Old: EX: 6.64 ± 0.70; NOEX: 4.84 ± 0.83; Young: EX: 7.39 ± 0.73; NOEX: 6.08 ± 0.58; p=0.014) arteries, the older adults did not have greater reductions in FMD compared to younger adults(p\u3e0.05). To further examine the effects of short-term physical inactivity on endothelial function, the second study employed a systematic review of the literature encompassing all published studies examining the effects of short-term inactivity or removal of exercise interventions on endothelial function. A search was made on two databases (PubMed and Web of Science) for studies employing interventions that reduced physical activity, with variables of interest including FMD, endothelin-1, nitric oxide, contrast-enhanced ultrasound, near-infrared spectroscopy, laser doppler flowmetry, capillary microscopy, and retinal imaging. Several forms of physical inactivity intervention (reduction in daily physical activity/steps, detraining/removal of exercise, bed rest, and immobilization) were included. In healthy individuals, all examined forms of inactivity impaired measures of endothelial function such as decreasing percent FMD or decreasing skin blood flow. While the exact time for participants to demonstrate these impairments is not clear, significant decreases may occur as early as 5 days following reduction of activity, with longer and more severe interventions more consistently demonstrating decreases in endothelial function. The final study of this dissertation determined associations between objectively measured physical activity (steps/day, minutes of moderate-vigorous intensity physical activity, or daily minutes of sedentary time) and endothelial function as assessed by FMD. Additionally, this study examined if reallocating time spent in sedentary behavior with time spent in moderate to vigorous physical activity and light intensity physical activity is associated with a more favorable FMD. Fifty-six healthy, active participants were recruited and had daily physical activity assessed via an Actigraph accelerometer for 7 days. Following 7 days of accelerometer use, participants had both brachial and popliteal artery FMD measured. Multiple regression reduced subset models explained 47% of the variance in popliteal artery %FMD using the variables brachial artery baseline diameter, popliteal artery baseline diameter, daily steps, and race/ethnicity. A significant correlation was determined between popliteal artery %FMD and average daily steps. Multiple regression reduced subset models explained 61% of the variance in brachial artery %FMD using the variables sex, VO2 peak, sedentary time, MVPA time, race/ethnicity, education status, and smoking status. A significant correlation was determined between brachial artery %FMD and sedentary time (R2 = 0.61, p\u3c 0.01), and a trend towards a significant correlation determined between brachial artery %FMD and MVPA (R2 = 0.61, p=0.09). Additionally, isotemporal regression analysis determined that replacing 30 minutes of sedentary time per day with 30 minutes of light intensity physical activity was associated with a 0.80% improvement in brachial artery %FMD. Replacing sedentary time with 30 minutes of moderate-to-vigorous intensity physical activity per day was associated with a 1.12% improvement in brachial artery %FMD, although neither demonstrated an association with popliteal artery %FMD. In this population, these results indicate that changes in brachial artery %FMD may be more related to physical activity intensity, while popliteal artery %FMD changes may be more related to daily steps
Development of Flexible Lactate-Specific Molecularly Imprinted Polymers Based on Laser-Induced Graphene Electrochemical Biosensors for Disease Diagnosis
No full textLactate is a critical biomarker linked to conditions such as sepsis, ischemia, cancer, and heart failure. Current lactate detection methods remain invasive, costly, and unsuitable for real-time, continuous monitoring. This study presents the development of a flexible, non-enzymatic electrochemical biosensor based on laser-induced graphene (LIG) electrodes modified with gold nanoparticles (AuNPs) and molecularly imprinted polymers (MIPs) for highly selective and sensitive lactate measurement. The integration of AuNPs enhanced surface conductivity and provided nanoscale heterogeneity, facilitating superior signal amplification. The optimized LIG/AuNP/MIP sensor achieved an extensive dynamic detection range from 0.1 μM to 1000 μM, with an outstanding detection limit of 0.033 μM and a strong linear correlation (R² = 0.9556). The biosensor exhibited excellent selectivity against common interferents such as glucose, uric acid, ascorbic acid, and potassium ions. Stability studies demonstrated robust performance after prolonged storage at 4 °C, with regeneration enabled via CTAB treatment. Validation using artificial saliva yielded recovery rates between 102% and 113%, confirming accuracy in complex biological matrices. Mechanical tests further confirmed exceptional flexibility, with ~98% signal retention after mechanical twisting, supporting its application in wearable technologies. Compared to conventional enzymatic and non-enzymatic platforms, the LIG/AuNP/MIP biosensor offers enhanced sensitivity, stability, and durability. These findings establish a strong foundation for the future development of integrated, non-invasive, continuous lactate monitoring devices suitable for athletic performance tracking, critical care diagnostics, and personalized health management
Intersecting Realities and Evolving Landscapes: Mapping Generative AI within the Framework of Digital Rhetoric
No full textThe increased usage of [Generative] AI technologies (GenAI) in the 21st century has called into the question the rhetorical agency of these digital things. [Gen]AI has historically been framed within a Heideggerian “readiness-to-hand” dynamic in which it has been unilaterally conceived as a tool to be used by humans. This dissertation proposes that the GenAI assemblage is capable of being a co-actor in rhetorical spaces. To provide evidence for this stance This dissertation utilizes Actor Network Theory to map the actants within a GenAI assemblage. In doing so it allows for an understanding of the stakeholders (both human and non-human) who play a part in bringing forth the assemblage. The map conceived from this research depicts the symmetry inherent within the assemblage: Showing both people and things playing a role into bringing GenAI technologies into the world. In addition, media archeology is also deployed.
The use of media archeology is used to display how people over several epochs of time have attuned to the idea and manifestation of Artificial Others (mythological, mechanical, computational, and digital including [Gen]AI). The inclusion of this portion of the research is geared toward displaying the shift in attunement from Artificial Others as “present-at-hand” ideas and things to acting and influencing the Burkean Parlor. The findings from this section include discovering commonalities of thought creating lines within a rhizome: A rhizome of attunement to the concept, creation, and deployment of things that act in rhetorical spaces as well as in the world.
The conclusion drawn from this research is that contemporary GenAI technologies still generally remain within a “present-at-hand” dynamic, but that they have also begun to influence rhetoric from within the Burkean Parlor as co-actors. This dissertation finds value in its mapping of the GenAI assemblage, the contour lines of said map via attunement to Artificial Others, and as evidence of a shift from Artificial Others as subjects of discussion within the Burkean Parlor to co-actors aiding in discussions within it now
The Influence of Monsoon Variability on the Circulation of the Near-Surface Indian Ocean and the Depth-Integrated Chlorophyll
No full textThe Indian Ocean experiences a strong semiannual reversal of monsoon winds, which determines the weather and climate of Asia, including freshwater fluxes between the atmosphere, land, and ocean. Studies and model projections suggest that the timing and intensity of the seasonal monsoon have already started to change, with more dramatic changes likely in the future. However, the impact of these changes on the Indian Ocean circulation system, including the inter-basin salt/freshwater transport between the Bay of Bengal and the Arabian Sea, remains unclear. To better understand how monsoon variability affects Indian Ocean circulation patterns, a Regional Ocean Modeling System simulation of the Indian Ocean has been developed, incorporating riverine freshwater fluxes. The model focuses on five possible monsoon scenarios: early arrival of monsoon, late arrival of monsoon, strong monsoon, weak monsoon, and normal monsoon. The results show that the most prominent changes occur when the timing of the monsoon shifts, rather than its intensity. The net annual westward transport of the monsoon current south of Sri Lanka increases when the monsoon arrives early and decreases significantly during a late monsoon. Understanding how boundary currents respond to shifts in monsoon timing and strength is crucial for predicting future changes in marine productivity, as these currents regulate upwelling intensity and nutrient advection. To assess how marine productivity has already been affected in this region, Biogeochemical-Argo data from 2013 to 2022, comprising over 9,000 individual profiles, were used to examine regional patterns and trends in depth-integrated chlorophyll and stratification. Unlike satellites, which are limited to surface measurements and affected by clouds and turbidity, Biogeochemical-Argo data provide cloud-independent chlorophyll profiles from the surface to a depth of 2000 meters. The analysis reveals that water column stratification is increasing most rapidly in the western Bay of Bengal. Depth-integrated chlorophyll concentrations are increasing across large areas of the Bay of Bengal and the western Arabian Sea. Climate modes show a weak negative correlation with depth-integrated chlorophyll in the northeastern Bay of Bengal. The results suggest that depth-integrated chlorophyll is not strongly or consistently correlated with stratification, indicating that projected increases in stratification due to ocean warming may not necessarily drive concurrent reductions in primary production
Examining Access, Outcomes, and the Experiences of Black Women: Improving Racial Equity in Adult Drug Treatment Court
No full textBlack women face compounded systemic barriers in the criminal legal system because of oppression and erasure of their racial and gendered identities. Although Adult Drug Treatment Courts (DTCs) are designed to divert individuals with substance use disorders from incarceration with the alternative of therapeutic intervention, Black women, compared to their Black male and White female counterparts, remain underrepresented and experience less favorable outcomes despite their increased presence in the criminal legal system due to drug related offenses. Using an intersectional Black Feminist framework, the current study critically examines the processes and structural barriers that contribute to Black women’s limited access and success in DTCs. The following study is conducted in two phases: Phase one consists of two process reviews of two Adult DTCs in the Southwest along with descriptive analyses that detain the enrollment and outcome data for Black women in each court. Phase two explores the lived experiences of former and current Black women participants from four different DTCs through a focus group and an interview. The use of a focus group and an interview centers Black women’s experiences to highlight their narratives that are typically overlooked in DTC effectiveness literature
Findings demonstrate structural inequalities, often influenced by implicit bias, eligibility criteria, and inadequate considerations of Black women’s unique needs, in referral decisions and court processes that impact the enrollment and successful completion of Black women in DTC. Qualitative findings reveal themes of unmet needs, culturally incompetent care, and institutional marginalization. This research contributes to the understanding of racial and gender disparities in DTC processes, and provides recommendations for culturally competent, gender responsive practices. By centering Black women’s narratives, this study aims to inform policy and practice that improve equity and inclusion in DTC to reduce recidivism and support long-term recovery
Unraveling Nonperturbative QCD with Transverse Momentum Hadronic Structures
No full textThe main purpose of this thesis is to investigate the theoretical foundations of the factorization theorems that involve transverse quark and gluon momentum distributions, and to better understand the interface between foundational questions and phenomenological applications. Many of these applications involve using transverse parton momentum dependent (TMD) correlation functions as tools for probing the complex nonperturbative structures of the hadrons.
We first introduce the concepts of collinear and TMD factorization in a toy-model theory and, by leveraging the comparative simplicity of such a model, we test the range of validity and limitations of the factorization approach. At the same time, we introduce the conventional approaches that are adopted for the phenomenological extractions of the TMD distributions, and catalog the advantages and disadvantages.
Following the general theoretical framework of factorization, we then develop a different approach to TMD phenomenology that is able to systematically integrate the perturbative and nonperturbative information in parametrizations of TMD distributions, while being completely consistent with their operator definitions and the predictions of QCD, including their nontrivial evolution. The name Hadron Structure Oriented approach, or HSO, is coined in order to emphasize the central role of the nonperturbative nature of QCD and its relation to the partonic structure of hadrons.
Finally, we provide a first phenomenological implementation of the HSO approach by extracting TMD distributions relying on low-to-moderate energy Drell-Yan data. The quality and robustness of the results are then compared against higher energy processes like high-Q2 Z0 boson production. Our analysis demonstrates the feasibility of this novel approach and points the way toward the improvements it can achieve in future applications
Learning Regulatory DNA-Sequence Code of Epigenetic Events Using Deep Neural Networks
No full textEpigenetic events, such as DNA methylation and histone modifications, arise from a complex interplay among genomic sequence, chromatin-remodeling factors, and environmental cues. These regulatory mechanisms can induce changes in gene expression without altering the underlying DNA sequence, playing critical roles in development, disease, and cellular differentiation. Among these events, DNA methylation is frequently profiled using bisulfite sequencing (e.g., whole-genome bisulfite sequencing [WGBS], reduced representation bisulfite sequencing [RRBS]). However, predictive modeling of epigenetic states—including methylation patterns and regulatory variant effects—remains challenging due to data sparsity, label noise, and limited uncertainty estimation in current deep learning approaches. This dissertation addresses these issues by introducing a suite of data-centric and uncertainty-aware deep learning frameworks. First, I conduct a systematic evaluation to quantify how data quality, sample size, and label noise affect model performance. Second, I propose a transfer learning method to impute sparse methylation profiles to improve data quality. Third, I develop a Monte Carlo dropout–based pipeline that quantifies uncertainty for non-coding genetic variant effect predictions, aiding in the prioritization of potentially regulatory variants in tissue-specific contexts. Collectively, these contributions advance scalable, interpretable, and reliable computational approaches for epigenomic data analysis, paving the way for improved understanding and practical utilization of epigenetic events in developmental and disease settings
Efficacy of Stress Acclimation Techniques in Coastal Wetland Plants (Spartina alterniflora and S. patens): Implications for Restoration and Nursery Production
No full textThe implementation of coastal nature-based features, created wetlands, and wetland restoration has increased globally over recent years. Many of these projects have been successful in meeting their goals, however, when projects fail, it is often attributed to mortality of transplanted vegetation. Transplant mortality may be due to inappropriate timing, poor site selection, or abiotic stressors associated with transplant shock. Science-backed guidelines have been well established in many coastal regions regarding site specifications and species selection, but nursery practices for reducing transplant shock remain inconsistent. In this study, we tested a combination of four salinity acclimation treatments and two inundation acclimation treatments on nursery-grown Spartina alterniflora and S. patens plugs. We measured a suite of plant functional traits to determine tradeoffs in plant response with a focus on traits associated with plant marketability, indicators of stress acclimation, and desired traits for restoration goals. A subset of plants was transplanted to a restoration site for analysis of their survival in situ. Exposure to salinity and inundation resulted in traits associated with both marketability and restoration goals (e.g., increased stem height, reduced dead to live stem ratio, and increased biomass), as well as evidence of acclimation to field stressors. However, trait differences did not translate to differences in field performance as survival and expansion of transplanted individuals showed no difference between acclimation treatments. The future of coastal wetland creation and restoration will require plant material that is produced using a science-based approach to ensure plants are robust, long-lived, and marketable to achieve the needs to restoration and nursery practitioners alike
Examining How Self-Regulated Learning Professional Development Affects Teacher SRL Knowledge, Beliefs, and Practices
No full textSelf-regulated learning (SRL) strategies promote valuable student learning outcomes including academic achievement and lifelong learning (EU Council, 2002). Teachers have an opportunity to cultivate student SRL development within their classrooms (Azevedo et al., 2008). While teachers believe in the benefits associated with SRL promotion (Spruce & Bol, 2014), their positive attitudes are not often supported by adequate knowledge of SRL strategies. This leads to a lack of self-efficacy for developing SRL instruction in classrooms (Dignath & Büttner, 2018; Zimmerman et al., 1996). SRL-based professional development (PD) interventions have demonstrated their effectiveness for increasing teacher SRL instruction and implementation (Cleary et al., 2022). A mixed-method research design with a qualitative emphasis was employed to understand the influence of SRL PDs on teacher beliefs, knowledge, and practice of SRL. Ten in-service teachers from an elementary school in Southern California participated in an SRL workshop and rated their SRL beliefs. From the initial group, teachers with the lowest and highest scores on the questionnaire were selected for an 8-week in-class SRL training intervention. During this period, they implemented SRL strategies specifically tailored to their individualized classroom needs to develop student SRL. Pre- and post-intervention interviews, weekly classroom observations, artifacts, and questionnaire data were analyzed to understand how teacher attitudes, understanding, and implementation of SRL changed over the course of the intervention. The findings showed that positive beliefs regarding student agency of learning processes increased noticeably from pre- to post-treatment. Teacher SRL knowledge expanded considerably, and teachers were able to successfully incorporate sixteen implicit and explicit SRL strategies from all three phases of Zimmerman and Moylan’s (2009) model into their instruction. Emerging themes suggest a close link between SRL and autonomy, and connections between SRL and socioemotional learning. The findings further indicate that SRL is contextual, and instruction of SRL may differ depending on varying influencing factors at teacher, student, and school levels. Longitudinal studies that follow teacher participants over the course of several school years could reveal how teachers independently apply SRL without constant expert presence, or with sustained expert support