The blood-brain barrier (BBB) is composed of brain microvascular endothelial cells (BMECs), pericytes, and astrocytic endfeet, which regulate the transport of molecules into and out of the brain. BMECs possess intrinsic barrier properties that limit the passage of approximately 98% of small molecules into the brain in healthy individuals. However, in some brain diseases, the BBB undergoes structural and functional alterations, which can contribute to disease progression. In this study, we aimed to investigate the BBB by exploring the effects of endothelial cell stretching and the optimal dimensionality of stretching to enhance endothelium barrier tightness in Chapter 2. Subsequently, we developed an endothelium gradient stretching device to further examine the stretching effect in Chapter 3. Additionally, we investigated the promotion of endothelium tightness through the use of electrospun fibers, wherein we controlled the pore size. Based on these findings, we designed and fabricated an organ chip model that incorporates mechanical stretching, microfluidic techniques, electrospun fibers, and hydrogel extracellular matrix (ECM). The results of permeability testing demonstrated that this chip significantly improved the tightness of microvascular selective transport ability and has the potential to be used in drug sorting for central nervous system (CNS) diseases.

The efficacy of a machine learning technique is domain dependent. Some machine learning techniques work very well for certain domains but are ill-suited for other domains. One area that is of real-world concern is the flexibility with which machine learning techniques can adapt to dynamic domains. Currently, there are no known reports of any system that can learn dynamic domains, short of starting over (i.e., re-running the program). Starting over is neither time nor cost efficient for real-world production environments. This dissertation studied a method, referred to as Experience Based Learning (EBL), that attempts to deal with conditions related to learning dynamic domains. EBL is an extension of Instance Based Learning methods. The hypothesis of the study related to this research was that the EBL method would automatically adjust to domain changes and still provide classification accuracy similar to methods that require starting over. To test this hypothesis, twelve widely studied machine learning datasets were used. A dynamic domain was simulated by presenting these datasets in an uninterrupted cycle of train, test, and retrain. The order of the twelve datasets and the order of records within each dataset were randomized to control for order biases in each of ten runs. …

The current study is the first repeated-measures design exploring the impact of child-centered play therapy (CCPT), an evidence-based child psychotherapy intervention, on autistic children's social-emotional assets, and emotional and behavioral problems across four times during intervention based on teacher reports. Participants consisted of 19 autistic children recruited from two Title-1 elementary schools in the southwest United States who were aged between 5 years and 8.25 years (M = 6.22, SD = .91), presented with varied levels of cognitive functioning and speech and language abilities. Over 60% of participants were identified by their parents as children of color. Results indicated participants' increased time in CCPT predicted statistically significant improvement in social-emotional assets measured by Social-Emotional Assets and Resilience Scales-Teacher (SEARS-T) total score with a large effect size. Results also indicated participants' increased time in CCPT predicted a statistically significant reduction in emotional and behavioral problems of irritability, social withdrawal, and hyperactivity/ noncompliance, measured by Aberrant Behavior Checklist-Second Edition (ABC- 2), with large effect sizes. Findings of this study revealed substantive changes in social-emotional assets as early as 8 CCPT sessions, and reduction of emotional and behavioral concerns as early as 12 CCPT sessions. Clinical significance, implications for practice, and limitations of …

In this study, high-fidelity conjugate heat transfer simulations are used to model a micro-channel heat exchanger (MCHE) in a crossflow to study its thermal-hydraulic performance. This study considers three different microchannels (internal flow) geometries (circular, triangular, and square) with louver-shaped fins. The local flow field showed a strong coupling between the microchannel flow, solid domain, and crossflow. The flow separation and wake regions formed near MCHE resulted in a large variation in the velocity field and temperature in the crossflow. The wake region had a significant spanwise variation due to its interaction with fins, which also causes variations in the thermal boundary layer. The heat conduction in the solid structure provided a non-uniform temperature field with a higher temperature near the microchannel and a slightly lower temperature near the surface exposed to the crossflow. The microchannel flow analysis showed that the internal geometry affects the pressure drop, which is highest for the triangular MCHE and lowest for the circular MCHE. However, the microchannel flow temperature change was relatively similar for all microchannels. Results showed that for the same volume of the microchannel, the circular shape microchannel has a higher performance index value than the triangular and square shapes. This study …

Research identifies male athletes as a subpopulation at risk for developing eating disorders and disordered eating (ED/DE). Petrie and Greenleaf's sociocultural model proposes that various correlates contribute to the etiology of ED/DE in athletes. Among the correlates, body satisfaction has been identified as a direct precursor to ED/DE symptomatology in male and female athletes. Recent research has noted self-compassion's utility in alleviating the outcomes of poor body image and ED/DE through several pathways. However, researchers have yet to examine self-compassion in relation to body satisfaction and ED/DE in male athletes or the temporal relationship between these variables. This study longitudinally examined the direct and indirect effects of self-compassion on body satisfaction and ED/DE symptomatology in a mixed-sport sample of 452 male collegiate athletes by testing the cross-lagged, temporal relationships among self-compassion, body satisfaction, and ED/DE symptomatology across a four-month time frame. Time 1 self-compassion was neither directly related to Time 2 body satisfaction (β = 0.02, p = .755), nor indirectly to Time 2 ED/DE (β = -0.002, 95% BCaCI [-0.028, 0.014]) when controlling for Time 1 scores. Recent research supports my finding and suggests that the effects of self-compassion on body satisfaction and ED/DE symptomatology may be dependent on …

Small-scale fracture behavior of four model alloy systems were investigated in the order of increasing microstructural complexity, namely: (i) a Ni-based Bulk Metallic Glass (Ni-BMG) with an isotropic amorphous microstructure; (ii) a single-phase high entropy alloy, HfTaTiVZr, with body centered cubic (BCC) microstructure; (iii) a dual-phase high entropy alloy, AlCoCrFeNi2.1, with eutectic FCC (L12) -BCC (B2) microstructure; and (iv) a Medium-Mn steel with hierarchical microstructure. The micro-mechanical response of these model alloys was investigated using nano-indentation, micro-pillar compression, and micro-cantilever bending. The relaxed Ni-BMG showed 6% higher hardness, 22% higher yield strength, and 26% higher bending strength compared to its as-cast counterpart. Both the as-cast and corresponding relaxed BMGs showed stable notch opening and blunting during micro-cantilever bending tests rather than unstable crack propagation. However, pronounced notch weakening was observed for both the structural states, with the bending strength lower by ~ 25% for the notched samples compared to the un-notched samples. Deformation behavior of HfTaTiVZr was evaluated by micropillar compression and micro-cantilever bending as a function of two different grain orientations, namely [101] and [111]. The [111] oriented micropillars demonstrated higher strength and strain hardening rate compared to [101] oriented micropillars. The [111] oriented micropillars showed transformation induced plasticity …

This research study examined the implementation of an extended reality (XR) lab on a community college campus to facilitate student and faculty access to immersive learning resources. The study, conducted during one skills day, involved 46 students and was designed to understand if integrating immersive VR into emergency medical technician (EMT) education could enhance learner confidence and motivation, develop problem-solving and analytical thinking skills, and thus connecting the classroom learning with real-world application. The majority of participants reported increased motivation and engagement, alongside improvements in learning outcomes like knowledge retention and skill development. Applying the unified theory of acceptance and use of technology (UTAUT) model revealed performance expectancy, effort expectancy, social influence, and facilitating conditions as key determinants of VR adoption in EMT education. While no significant overall performance enhancement was observed, VR training showed potential to boost motivation, confidence, and specific performance aspects. Furthermore, student perceptions towards VR in EMT education were largely positive, thereby suggesting its utility in immersive scenario training, skill acquisition in a risk-free environment, enhancing learner engagement, and real-world situational preparedness. VR demonstrated promise as a transformative tool in EMT education, necessitating further research to fully exploit its potential in diverse learning environments.

The present study provides an example of implementing the difference in differences (DD) estimator for a two-group, pretest-posttest design with K-12 educational intervention data. The goal is to explore the basis for causal inference via Rubin's potential outcomes framework. The DD method is introduced to educational researchers, as it is seldom implemented in educational research. DD analytic methods' mathematical formulae and assumptions are explored to understand the opportunity and the challenges of using the DD estimator for causal inference in educational research. For this example, the teacher intervention effect is estimated with multi-cohort student outcome data. First, the DD method is used to detect the average treatment effect (ATE) with linear regression as a baseline model. Second, the analysis is repeated using linear regression with cluster robust standard errors. Finally, a linear mixed effects analysis is provided with a random intercept model. Resulting standard errors, parameter estimates, and inferential statistics are compared among these three analyses to explore the best holistic analytic method for this context.

Metallic Glasses are multi-component alloys with disordered atomic structures and unique and attractive properties such as ultra-high strength, soft magnetism, and excellent corrosion/wear resistance. In addition, they may be thermoplastically processed in the supercooled liquid region to desired shapes across multiple length-scales. Recently developed metallic glasses based on noble metals (such as Pt and Pd) are highly active in catalytic reactions such as hydrogen oxidation, oxygen reduction, and degradation of organic chemicals for environmental remediation. However, there is a limited understanding of the underlying electrochemical mechanisms and surface characteristics of catalytically active metallic glasses. Here, we demonstrate the influence of alloy chemistry and the associated electronic structure on the activity of a systematic series of Pt42.5−xPdxCu27Ni9.5P21 bulk metallic glasses (BMGs) with x = 0 to 42.5 at%. The activity and electrochemically active surface area as a function of composition are in the form of volcano plots, with a peak around an equal proportion of Pt and Pd. These amorphous alloys showed more than two times the hydrogen oxidation reactivity compared to pure Pt. This high activity was attributed to their lower electron work function and higher binding energy of Pt core level that reduced charge-transfer resistance and improved electrocatalytic activity …

Ambient lighting has emerged as a key atmospheric factor influencing how consumers process environmental cues and their behaviors. However, surprisingly little research has examined how people think and feel in the dark (lower than 15 lux). This is particularly relevant given that consumers routinely work, pay bills, relax, consume and make purchases in settings with little or no light. My dissertation addresses this gap by examining how consumers regulate their goals and process information when the light is off, and how that impacts their decision making in three substantive domains: risk-taking behavior, decision quality, and persuasion. In Essay 1, I propose darkness enables risk-taking behavior, and this effect happens through the calmness and relaxation induced in the dark. One caveat is that the decisions have to be made in a familiar setting. The effect was reflected in participants' decisions to invest in riskier yet lucrative stocks, to gamble with the riskier choice, to eat at a foreign restaurant, and to choose a supplement that has potential side effects in a field experiment and three lab experiments (pre-registered). In Essay 2, I propose that when the light is off, consumers are indeed induced to adopt an effortful processing mode. Across four …

Coaches' knowledge, attitudes, and beliefs about mental health – the construct of mental health literacy (MHL) – affects teams' mental health (MH) climates and the early detection, referral, and treatment of athletes' MH concerns. Thus, assessing collegiate coaches' MHL, and the factors related to its presence, is critical. Using the Mental Health Literacy Scale, I surveyed 1,571 NCAA coaches (Mage = 37.5 years, SD = 11.8; 51.4% cisgender female; 85.9% White) regarding their MHL and related demographic and MH-experience factors, including their belief regarding MH and sport performance. Overall, 99.9% of the coaches believed that athletes' MH affected their sport performances. Through hierarchical regression analyses, I found that coaches' exposure to MH treatment, their perceived helpfulness of MH treatment, their gender (i.e., woman), number of years coaching (i.e., fewer years), and NCAA Division in which they currently coach (i.e., DIII) were related significantly to their MHL, explaining 15.5% of variance. Coaches' race/ethnicity was not related to MHL. These findings provide insight on hiring and educating coaches, and hiring appropriately trained and licensed MH and sport psychology professionals. Specifically, coach education should be focused and practical: signs and symptoms of common MH concerns disorders; the ubiquity of MH concerns among athletes; …

The American democracy is experiencing strain from the erosion of democratic norms and its political, judicial, social, and economic institutions. In short, the American democracy shows signs of democratic deconsolidation. Community colleges are higher education institutions that help consolidate the U.S. democracy by representing democratic values such as equality and opportunity. The purpose of my study was to explore how selected community college presidents understand and articulate the responsibility of their institutions to prepare students for a meaningful role in the American democracy. Qualitative narrative inquiry methods, including in-depth semistructured interviews and document analysis, were used to collect data for the study. Three primary themes emerged from the data that addressed the purpose of this study: 1) community college philosophy: blueprint for a vision, 2) consolidating local democracies, and 3) citizens as students, students as citizens. These three themes supported further interpretation of the data that was organized under these headings, 1) the community college democratic mission, 2) community colleges help deepen democracy, and 3) the role of community colleges in the American democracy: public goods, private goods. In summary, my research found that first, my participants believed that community colleges have a responsibility to the American democracy and this …

Child-centered play therapy (CCPT) is an empirically endorsed approach for children facing specific clinical concerns and life circumstances alike. The majority of research to date has accrued data about clients from secondary sources, such as adult report and observation. The purpose of this study was to explore children's perceptions of participating in CCPT by implementing a developmentally accessible interview medium, allowing children to share their experiences directly. Ten children between the ages of 4 and 7 who had completed at least eight sessions of CCPT were invited to create a drawing and respond to an interview protocol with their counselor. Data sources included the picture produced, a transcript of the interview between the child and counselor, and observation notes of the interview process. Using a phenomenological approach, three themes were identified to describe children's awareness and experience of the intervention: expressions of relationship, experiences in the playroom, and reluctance to engage in counselor-directed activity. The first two themes reflect children's report of the intervention and the third represents reactions to the research activity. Findings from this study support conclusions that children are aware of relationship between themselves and their counselor and recognize the uniquely unstructured features of play therapy and …

Extant research suggests communication styles (CS) such as constructive communication (CC) to be associated positively with relationship satisfaction (RS) and negatively with mental health (MH) whereas self-demand / partner withdraw (SD/PW) communication is associated negatively with RS and positively with MH. Research also suggests child abuse (CA) to be associated with poorer CS, lower RS, and poorer MH. Further, RS has been differentially associated with MH and CS in adult intimate relationships. However, no study has examined these associations simultaneously. The current study aimed to (1) assess these associations in IPV-exposed women and (2) assess differences between those with and without a history of CA. Data (n = 412; Mage = 36.77, SD = 12.54) come from a larger data collection project (N = 676). I hypothesized that: (1) higher CC and RS would be associated with lower severity of MH symptoms; (2) higher SD/PW and lower RS would be associated with higher severity of MH symptoms; (3) women with a history of CA will report less CC, lower RS, and higher severity of MH symptoms; and (4) women with a history of CA will report more SD/PW, lower RS, and higher severity of MH symptoms. Results did not support …

The age-cutoff regression discontinuity design (RDD) has emerged as one of the most rigorous quasi-experimental approaches to determining program effects of prekindergarten on literacy and numeracy outcomes for children at kindergarten entry. However, few pre-K meta-analyses have focused attention on validity threats. The current random-effects meta-regression tests the moderating effects of prominent threats to validity, selection bias and sensitivity, on impact estimates generated from age-cutoff regression discontinuity studies from large-scale programs. Results from averaging dependent standardized mean difference effects suggested small positive moderating effects of total attrition and robust 3-month bandwidths on reading effects, but not on math. However, these results were not statistically significant. In contrast, results generated from robust variance estimation yielded a small statistically significant association between total attrition and math effects. These mixed results may warrant further research on prekindergarten evaluation methodology, evaluation estimation methods, and the totality of evidence used to inform policy.

The original FlexiChain and its descendants are a revolutionary distributed ledger technology (DLT) for cyber-physical systems (CPS) and their embedded systems (ES). FlexiChain, a DLT implementation, uses cryptography, distributed ledgers, peer-to-peer communications, scalable networks, and consensus. FlexiChain facilitates data structure agreements. This thesis offers a Block Directed Acyclic Graph (BDAG) architecture to link blocks to their forerunners to speed up validation. These data blocks are securely linked. This dissertation introduces Proof of Rapid Authentication, a novel consensus algorithm. This innovative method uses a distributed file to safely store a unique identifier (UID) based on node attributes to verify two blocks faster. This study also addresses CPS hardware security. A system of interconnected, user-unique identifiers allows each block's history to be monitored. This maintains each transaction and the validators who checked the block to ensure trustworthiness and honesty. We constructed a digital version that stays in sync with the distributed ledger as all nodes are linked by a NodeChain. The ledger is distributed without compromising node autonomy. Moreover, FlexiChain Layer 0 distributed ledger is also introduced and can connect and validate Layer 1 blockchains. This project produced a DAG-based blockchain integration platform with hardware security. The results illustrate a practical technique …

The historical success of friction stir welding (FSW) on materials such as aluminum and magnesium alloys is associated with the absence of melting and solidification during the solid-state process. However, commercial adoption of FSW on steels and other non-ferrous high-strength, high-temperature materials such as nickel-base and titanium-base alloys is limited due to the high costs associated with the process. In this dissertation, the feasibility of using an FSW approach to fabricate certain structural components made of nitrogen containing austenitic stainless steels that go into the vacuum vessel and magnetic systems of tokamak devices was demonstrated. The FSW weldments possessed superior application-specific mechanical and functional properties when compared to fusion weldments reported in the technical literature. However, as stated earlier, the industrial adoption of FSW on high temperature materials such as the ferrous alloys used in the present study is greatly limited due to the high costs associated with the process. The cost is mainly dictated by the high temperature FSW tools used to accomplish the weldments. Commercially available high temperature FSW tools are exorbitantly priced and often have short lifetimes. To overcome the high-cost barrier, we have explored the use of integrated computational materials engineering (ICME) combined with experimental prototyping …

As a political disturbance and social movement, the Cultural Revolution hugely impacted the development of Chinese piano art. The piano went through many stages throughout this ten-year period. This dissertation examines the suppression and later expansion of piano music in China during the Cultural Revolution, along with the historical motivations and forces that shaped each stage of its development. The study is supported by historical documents and relevant literature. This dissertation includes an analysis of the roles that piano music played during this era and the piano's relationship with the Cultural Revolution's modernizing goals. The analysis focuses on the musical characteristics of three piano pieces from this period and explores the instrument's historical importance, to better understand how Chinese piano music maintained a careful balance between its value as a tool for socio-political propaganda and its transformation under the burden of political pressure and creative limitations. Additionally, this dissertation examines playing techniques in these works that define a distinctly Chinese piano style that is enormously popular today. To complement the dissertation, these piano pieces were performed during the dissertation recital.

This dissertation investigates computational models and methods to improve collaboration skills among students. The study targets pair programming, a popular collaborative learning practice in computer science education. This research led to the first machine learning models capable of detecting micromanagement, exclusive language, and other types of collaborative talk during pair programming. The investigation of computational models led to a novel method for adapting pretrained language models by first training them with a multi-task learning objective. I performed computational linguistic analysis of the types of interactions commonly seen in pair programming and obtained computationally tractable features to classify collaborative talk. In addition, I evaluated a novel metric utilized in evaluating the models in this dissertation. This metric is applicable in the areas of affective systems, formative feedback systems and the broader field of computer science. Lastly, I present a computational method, CollabAssist, for providing real-time feedback to improve collaboration. The empirical evaluation of CollabAssist demonstrated a statistically significant reduction in micromanagement during pair programming. Overall, this dissertation contributes to the development of better collaborative learning practices and facilitates greater student learning gains thereby improving students' computer science skills.

The anti-S2 peptides, the stabilizer and destabilizer, were designed to target myosin sub-fragment 2 (S2) in muscle. When the peptides are coupled to a heart-targeting molecule, they can reach the cardiomyocytes and interfere with cardiac muscle contraction. Monoclonal antibodies, MF20 and MF30, are also known to interact with light meromyosin and S2 respectively. The MF30 antibody compared to anti-S2 peptides and the MF20 antibody is used as a control to test the central hypothesis that: Both the anti-S2 peptides and antibodies bind to myosin S2 with high affinity, compete with MyBPC, and possibly interact with titin, in which case the anti-S2 peptides have further impact on myosin helicity and reach the heart with the aid of tannic acid to modulate cardiomyocytes' contraction in live mice. In this research, the effects of anti-S2 peptides and antibodies on myosin S2 were studied at the molecular and tissue levels. The anti-myosin binding mechanism to whole myosin was determined based on total internal reflectance fluorescence spectroscopy (TIRFS), and a modified cuvette was utilized to accommodate this experiment. The binding graphs indicated the cooperative binding of the peptides and antibodies with high affinity to myosin. Anti-myosin peptides and antibodies competition with Myosin Binding Protein C …

The purpose of this dissertation is to examine the relationship of Andrew Johnson to the South and the effect of that relationship on presidential reconstruction. It is not meant to be a complete retelling of the story of reconstruction, rather it is an attempt to determine how Johnson affected southern ideas of reconstruction and, equally important, how southerners influenced Johnson.

The research presented in the dissertation deals with the synthesis, characterization, photophysical, electrochemical, and pump probe studies of porphyrin-fullerene based donor-acceptor conjugates. The first chapter provides insights into the introduction of the thesis, which explains the events that occur in natural photosynthesis and the mimicking process of an artificial photosynthesis based on natural photosynthesis, works done in covalently and non-covalently linked donor acceptor systems, and the penetration of the literature related to the long-lived charge-separated states donor-acceptor conjugates. The second chapter details the physical methods employed to monitor the various photochemical processes in the donor-acceptor moiety. The third chapter focusses on designing and synthesizing a platinum porphyrin-fullerene dyad used for long-lived charged-separated state. The formation of a high-energy, long-lived radical ion pair by electron transfer from the triplet excited state is orchestrated in the dyad. The porphyrin ring is modified with three triphenylamine which act as secondary electron donors. The spin state of the electrons leading to the formation of long-lived charge-separated state is demonstrated by time-resolved optical and EPR spectroscopy. The fourth chapter studies metal ligand axial coordination. Two porphyrins were self-assembled via metal-ligand axial coordination of phenyl imidazole functionalized fulleropyrrolidine. A 1:2 complex formation with ImC60 was observed …

In this dissertation, we address the problem of vagueness in traditional legal contracts by presenting novel methodologies that aid in the paradigm shift from traditional legal contracts to smart contracts. We discuss key enabling technologies that assist in converting the traditional natural language legal contract, which is full of vague words, phrases, and sentences to the blockchain-based precise smart contract, including metrics evaluation during our conversion experiment. To address the challenge of this contract-transformation process, we propose four novel proof-of-concept approaches that take vagueness and different possible interpretations into significant consideration, where we experiment with popular vendors' existing vague legal contracts. We show through experiments that our proposed methodologies are able to study the degree of vagueness in every interpretation and demonstrate which vendor's translated-smart contract can be more accurate, optimized, and have a lesser degree of vagueness. We also incorporated the method of fuzzy logic inside the blockchain-based smart contract, to successfully model the semantics of linguistic expressions. Our experiments and results show that the smart contract with the higher degrees of truth can be very complex technically but more accurate at the same time. By using fuzzy logic inside a smart contract, it becomes easier to solve the …

In the US, rural Native American communities (RNACs) experience excess morbidity in mental health disorders and mortality from opioid use disorder (OUD). This study used mixed methods to evaluate and analyze the primary data from 76 healthcare providers (HPs) from 24 states across the US (physicians = 7%), to identify HP knowledge and training regarding available prevention, treatment, and recovery (PTR) programs in treating OUD, assessment and management skills, and networking and collaboration capacity among the RNACs they serve. The HP completed the Opioid Survey for Health Care Providers online. A majority of HPs reported a need for knowledge and training regarding OUD treatments (92%). Less than half of the HPs provide intensive outpatient treatment; 40% contracted out for medication assisted treatment/medications for opioid use disorder (MAT/MOUD) services. Recovery support was low at 33% for adults and 38% for youth. HPs reported use of Narcan to be effective in reversing overdose (87%). Qualitative responses supported survey findings and described barriers, including lack of resources, inadequate staffing, insufficient funding, lack of training and OUD knowledge, stigma, and lack of tribal involvement and support. The study findings indicate HPs' need for information and training about OUD and networking and collaboration of healthcare …