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Item Characterizing Ventricular Anatomy and Developing Electrical Recording Systems for the Study of Ventricular Arrhythmias(2023-06) Brigham, ReneeVentricular arrhythmias are serious cardiac conditions that if left untreated, can result in sudden cardiac death. While patient outcomes have improved with the use of anti-arrhythmic drugs and implantable cardioverter defibrillators (ICDs), significant challenges still remain for improving patients’ quality of life and freedom from arrhythmia recurrences. Over the last few decades, catheter ablations have become established, reliable procedures for the termination and sometimes curative elimination of cardiac arrhythmias. Nevertheless, it is important for both physicians and medical device designers to critically understand the broad ranges of cardiac anatomies for this ever-growing patient population. Human cardiac ventricular anatomy is significantly more complex than depicted in anatomical educational materials. Additionally, there is a need for studies of the role of ventricular anatomy in the electrical activity recorded in clinical mapping and ablation procedures. Through isolated heart studies, both formalin-fixed and reanimations on the Visible Heart® apparatus, the ventricular anatomy and its effects on electrophysiology are studied and described. This work advances physician understanding of ventricular anatomy, both endocardial and epicardial, as it relates to ventricular mapping and ablation procedures. This in turn can lead to improvements in procedural outcomes and overall patient care for those with ventricular arrhythmias. Understanding the complexity of the ventricular anatomy and electrophysiology is essential to designing, improving, and utilizing the tools needed for successful ventricular mapping and ablation procedures.Item Perturbation theory in extended systems: Sharp nonlocal center manifolds and weakly quenched planar fronts(2024-05) Cannon, OliviaWe give novel perturbative results in two spatially extended contexts. First, we proveexistence of sharp center manifolds for spatially extended nonlocal systems with exponentially localized convolution kernels. Technically, the use of C0-based spaces allows for optimal regularity of the center manifold in a certain set of coordinates, as well as allowing for a simpler cutoff argument for existence of the manifold. As an application, we prove a sharp Lyapunov-Center theorem for a class of nonlocal systems. Second, we prove existence of fronts in a quenched planar Allen-Cahn equation, in the scaling regime where a weak inhomogeneity in the bistable region and the speed of the quenching line are of the same order. We find that the inhomogeneity and quenching speed induce a contact angle of the front, and describe its dependence on both parameters. Analysis relies on a farfield core decomposition made possible by Fredholm properties of the linearized operator at the stationary front in exponentially weighted spaces.Item Reading the record of ultrahigh-pressure terrane exhumation preserved in meters-scale shear zones of the Western Gneiss Region, Norway(2022-07) Blatchford, HannahThe occurrence of large (>10,000 km2) (ultra)high-pressure (UHP) metamorphic terranes in eroded mountain belts indicates that significant tracts of continental crust can be subducted to and returned from mantle depths. Despite the recognition of UHP terranes in many orogens, the relationship between the pressure-temperature-time (P-T-t) exhumation path primarily from eclogites and deformation (d) within large UHP terranes is incompletely understood. Compared with outcrop-scale structures in UHP terranes, terrane-bounding structures inform exhumation models, receive more research focus, and tend to be extensively overprinted by the last increment of finite strain. This produces a disconnect between proposed exhumation mechanisms, the P-T-t history derived from eclogites, and the response of the terrane interior to subduction and exhumation. This thesis therefore focuses on eclogite-bearing high-strain zones within the Western Gneiss Region (WGR) of Norway, a large and exceptionally well-exposed UHP terrane. Accessory phase (titanite and rutile) petrochronology, trace-element thermobarometry, and (micro)structural characterization of WGR shear zones deepens our understanding of titanite as a deformation petrochonometer, yields detailed P-T-t-d histories from single outcrops, and highlights the variability of exhumation mechanisms recorded across the terrane. Titanite is a promising accessory phase for dating and describing the metamorphic environment of ductile deformation if the relationships between (re)crystallization, Pb loss, and trace element concentrations can be characterized. To that end, titanite grains affected by a strain gradient preserved in a mylonitized, syn-kinematic pegmatite dike were analyzed to compare their U-Pb dates with the timing of dike crystallization and deformation (U-Pb zircon age). Zr-in-titanite temperatures indicate crystallization below Tc estimates for Pb volume diffusion, and Ti-in-quartz thermometry indicates mylonitization at T <600℃. Titanite yielded a lower intercept date of 387.2 ± 7.7 Ma (MSWD = 2.2) compared to zircon crystallization at 396.0 ± 7.9 Ma (MSWD = 1.0), and titanite kernel average misorientation maps show a correlation between younger single-grain dates and greater lattice distortion. Pb in titanite is impacted by mylonitization at these temperatures (<600℃), but the resultant U-Pb dates do not correspond to the timing of deformation; rather, deformation-induced fast pathways generated during deformation subsequently lower Tc for Pb. Despite the difficulty in using titanite to directly date crystal-plastic deformation, trace and rare-earth element concentrations in titanite provide reliable information on temperature, co-(re)crystallizing phases, and sources of common Pb at the time of (re)crystallization. Samples yielding nondispersed lower-intercept dates were investigated using REE pattern shape coefficients and Zr concentrations to identify two generations of titanite formed along the WGR exhumation path: one during eclogite partial melting and another, ~10 myr younger, during the onset of constrictional deformation. This approach explains the locally variable U-Pb titanite dates reported in the WGR and highlights the power of trace and rare earth elements to identify geologically significant (re)crystallization events in seemingly uncomplicated U-Pb datasets. Titanite and rutile petrochronology applied to samples of shear zone-hosted retrogressed eclogite across the WGR offers insight into the conditions under which eclogite was retrogressed during exhumation-related deformation. In Nordfjord and Sørøyane UHP domains, rutile and quartz thermobarometry preserve a lower-temperature/higher-pressure history than in the Nordøyane UHP domain and in HP rocks from Roan to the north. Titanite in the latter two areas records higher temperatures than the Nordfjord and Sørøyane domains, pointing to a period of high-temperature reequilibration not experienced in the two southernmost UHP domains. Exhumation histories have the potential to vary systematically across large UHP terranes.Item Essays on International Trade and Development(2024-07) Zhang, EntianThis dissertation consists of three chapters discussing the role of trade in development, as well as how development can facilitate trade. The first chapter studies the impact of financial frictions on firms' sourcing decisions of intermediate inputs. I set up a general equilibrium Baumol-Tobin inventory management model where heterogeneous firms pay for inputs before production and are subject to borrowing limits. The model implies that financial frictions restrict the sizes of orders made by the firms and distort the sourcing decisions by inducing firms to source from countries where they can make small and frequent orders. I then use Chinese firm-level data to validate the model. I find that (i) when sourcing a same product from a same country, more financially constrained firms make smaller orders; (ii) the import orders from neighboring countries (regions) of China are smaller and more frequent comparing to those from other countries, and firms tend to source from neighboring countries (regions) when financially constrained. The model is parameterized to match key features of the Chinese firm-level data. I find that financial reforms aimed at improving firms' access to external finance and policies that reduce the fixed costs of importing can mitigate the distortion in order sizes and sourcing decisions, thereby increase the gains from trade. The second chapter investigates how labor market frictions influenced total factor productivity (TFP) growth under a trade framework. By developing a model incorporating Schumpeterian growth theory and internal migration dynamics, the paper quantifies the impact of China's migration costs. These costs were initially high in 2000 but declined thereafter. From 2000 to 2005 alone, reducing migration costs enabled over 20 million workers to relocate from western to eastern China. The calibrated model illustrates that this migration, facilitated by lower migration costs, accounted for 52\% of the rise in China's TFP growth during this period. The third chapter investigates the impact of the US-China trade tension on trade relocation and explores the role of country-sector characteristics in facilitating the relocation of US imports. Specifically, we examine the interaction between a country's financial development and the financial dependence of an sector. Our findings indicate that countries with stronger financial development tend to gain a larger market share when China exits sectors characterized by high financial dependence for investment and working capitals. Moreover, we observe that the effect of this interaction is more pronounced when the country already possesses a significant initial market share in the sector, reflecting comparative advantages. As a result, financial frictions play a crucial role in shaping the relocation of US imports and can lead to reduced gains from trade for countries with less developed financial systems.Item Influence of identity on human well-being benefits of blue space(2024-07) Wick, MollyBlue spaces, or the publicly accessible environments around and within oceans, estuaries, rivers, streams, and other waterbodies, provide benefits to human well-being. Cultural ecosystem services (CES) are a leading framework for understanding and assessing these benefits. CES are defined as services produced through the interaction of humans and nature that give rise to intangible benefits to human well-being. Sociodemographics and other forms of social and personal identity influence CES benefits, which are inequitably distributed to diverse populations. Environmental decision-making about blue space has the potential to help reduce or possibly exacerbate these inequities. Assessment of CES may help inform equitable environmental decision-making, but this application of CES assessment is challenged by a limited understanding of the complex ways that benefits of and barriers to CES are influenced by personal and social identity in diverse and multi-cultural communities. This dissertation addresses this gap by exploring the question of how benefits of and barriers to CES associated with blue space are associated with individual identity, defined as an individual’s personal characteristics and social group affiliations. We adopted a community-engaged, mixed methods approach in a case study of blue space CES in a Great Lakes coastal multi-cultural community. The study area included the communities of Duluth, Minnesota and Superior Wisconsin, and the entire reservation of an Ojibwe Tribal Nation. The study area is located within ceded territory in which the Ojibwe retain treaty rights to traditional lifeways. A community advisory group and an Indigenous advisory group helped develop, deploy, and analyze results of this study. We conducted a qualitative and quantitative survey of 532 study area residents, followed by thematic analysis of qualitative interviews with a subset of participants to assess multiple dimensions of CES. In this dissertation, we first address the process of navigating university openness in research policy and Indigenous data sovereignty (Chapter 1). We found that existing university open research policies do not account for the unique case of university research partnership with a sovereign tribal nation and need to be revised to fully support and facilitate research partnerships among universities and Indigenous communities. Survey (Chapter 2) and interview (Chapter 3) results demonstrated that social and personal identity fundamentally structure the experiences of blue space CES by individuals. Gender, age, life stage, ethnicity, income level, and health status, among others, influenced participants’ experiences of blue space. Highlighting the inherently relational nature of CES, our results showed that both benefits of and barriers to CES are emergent properties that arise from an individual’s perception of themselves relative to blue space. Challenging existing simplistic CES conceptual models, our results reveal the complex ways that identity informs the individuals’ perceptions about themselves relative to the environment over the course of life to give rise to, or to prevent, emergent wellbeing benefits associated with blue space. Our results demonstrate the importance of engaging and incorporating the perspectives of historically underrepresented and marginalized communities in blue space research and decision-making processes to advance the equity of CES benefit distribution, especially Indigenous organizations and tribal nations, due to the unique relationships Indigenous communities have with blue space.Item Essays on International Trade, Growth, and Development(2024-07) Zeng, SimengThis dissertation consists of three chapters focusing on the role of international trade in growth and development. The first chapter surveys the literature on trade and development, using China as a case study. The chapter begins with an introduction to two widely used micro-level datasets that are crucial for studying the Chinese economy. Using these datasets, I explore and summarize aggregate patterns in China's export growth, complementing existing literature with empirical evidence. Next, I review the broader literature on how international trade fosters economic development and growth. The chapter concludes by examining a unique aspect of China's trade structure: processing trade. This exploration discusses the characteristics of processing trade and analyzes its potential benefits and implications for China's economic development. The second chapter explores a specific channel through which international trade impacts growth: high-skill immigration and its relationship to multinational enterprise (MNE) talent offshoring. This topic is particularly relevant in the context of ongoing debates about immigration policy, especially in the United States. When countries tighten immigration policies, firms face challenges in hiring foreign high-skilled workers due to increased visa sponsorship costs or cap restrictions. In response, firms can adopt an alternative strategy: establishing foreign affiliates and engaging researchers overseas, rather than hiring expensive domestic labor. To analyze this phenomenon and its implications for growth, this chapter develops a dynamic model integrating international trade, MNE activities, innovation processes, and immigration dynamics. A critical assumption is that MNEs can segment their innovation process and deploy researchers to foreign affiliates. Calibrated to U.S. aggregate data on trade and MNE activities, the results show that existing immigration restrictions explain 47.8 percent of observed MNE talent offshoring. The chapter further shows that eliminating these restrictions could benefit the overall economy through more efficient process innovation and higher product innovation, leading to gains in total productivity and aggregate welfare. The third chapter focuses on developing countries and examines how resource mis- allocation influences firms’ technology investment decisions and impacts trade gains. While economists and policymakers widely view international trade as one of the fundamental drivers of economic development, developing economies often face barriers that prevent them from fully exploiting its benefits. One such barrier is the misallocation of production factors, typically stemming from policy distortions such as preferential access to land and capital, selective taxes and subsidies, and various industrial policies. This chapter conducts a quantitative study to assess how resource misallocation affects firms’ exporting and technology upgrading decisions, and consequently, the gains from trade and productivity growth. The study constructs a two-country Melitz model with firm-specific distortions, extending the work of Bai et al. 2024 by introducing research and development (R&D) investment choices. This extension is particularly relevant given the surge in R&D expenditure and growing emphasis on innovation in many developing economies, including China. A quantitative assessment using Chinese manufacturing data reveals that allowing firms to upgrade technology further reduces welfare gains from trade in this second-best environment. This is because misallocation distorts firms’ R&D decisions, therefore trade liberalization encourages the growth of less productive but subsidized firms. This drives up costs for more productive yet taxed firms, resulting in a further reduction of trade gains. Even with additional R&D subsidies aimed at correcting distortions in innovation decisions, results remain unchanged. The chapter also addresses the optimal sequencing of policy reforms in developing countries and underscores the importance of structural reforms to maximize trade gains in these economies.Item A multi-faceted evaluation of a reintroduced waterfowl species: Migration ecology, ecotoxicology, and population genetics of trumpeter swans in the Midwest(2024-06) Wolfson, DavidTrumpeter swans (Cygnus buccinator), the largest waterfowl species in North America, were widespread throughout much of the continent prior to European colonization. Due to unregulated market hunting, trumpeter swans were nearly extirpated, and reached an estimated low of ~70 individuals in the lower 48 U.S. states during the 1930s. The creation of new protected areas coupled with management efforts allowed trumpeter swan abundance to recover, and they were successfully reintroduced to the western Great Lakes region in the late 20th century to re-establish the Interior Population (IP). However, a general lack of information about IP trumpeter swan ecology has hindered conservation decision-making. I partnered with agency biologists from seven U.S states and one Canadian province to gather information on IP trumpeter swan annual movements and migration patterns, the prevalence of lead (Pb) in free roaming swans, and the genetic makeup of trumpeter swan populations in North America. Before addressing the previously mentioned aspects of trumpeter swan ecology, in Chapter 1, I provide a review of piecewise regression, a flexible type of breakpoint analysis. I provide an overview of piecewise regression and then describe six case-studies, using piecewise regression on a variety of datasets that include a range of species, data types, ecological responses, statistical signals, and timeframes. In Chapter 2, I use the methodology described in Chapter 1 (i.e., piecewise regression) to quantify annual movements and migration patterns in IP trumpeter swans. We (multiple state agency biologists and other collaborators) deployed 133 GPS-GSM transmitters on trumpeter swans across the current IP breeding range (i.e., the greater Midwest) during 2019–2022. Individual tracking data revealed that IP trumpeter swans are partial migrants, with a continuum of strategies each year, from local movements to long-distance migration. Much of the variability in movement patterns was related to factors tied to natural history demands (e.g., breeding status) and response to environmental conditions (e.g., through associations with breeding latitude). In Chapter 3, I present a baseline assessment of the prevalence of lead in all trumpeter swans associated with the dissertation and an additional flock in Nebraska. I estimated blood lead concentration for 119 IP trumpeter swans and detected lead in all individuals. However, 91% of swans had blood lead levels in the ‘background’ range (not considered to produce negative physiological effects), 7.5% of swans had blood lead levels in the ‘sub-clinical’ range, and only 1.5% of swans had blood lead levels in the ‘clinical’ or ‘severe’ range of lead toxicity. Finally, in Chapter 4 I present a comparative assessment of the genetics of trumpeter swans in North America. I collected 150 genetic samples from IP trumpeter swans captured during 2019–2022 and also obtained 79 reference samples from the other two North American trumpeter swan populations. These samples provide evidence that all three populations are genetically distinct and that the High Plains flock of the IP has lower genetic diversity compared to the other groups, likely a result of smaller population size, relative geographic isolation, and potential founder effects.Item Organizational Environmental Sustainability in Asian Countries: Assessment and Nomological Network(2022-06) Wang, YileiThis dissertation recognizes that organizations and their employees are vital for addressing climate change and promoting environmental sustainability. It presents a comprehensive examination of organizations’ environmental sustainability performance for far and southeastern Asian organizations, focusing on actions (i.e., what organizations do). Five studies are presented which adopt an initiative-based approach to assess organizational environmental performance, develop NLP methods to content analyze environmental sustainability initiatives, and validate the assessment by examining its nomological network. The first study utilized natural language processing (NLP) and machine learning (ML) to facilitate the human coding process in the content-analysis of environmental sustainability initiatives. Study two implemented a human-machine hybrid approach to quantify organizations’ environmental performance by content analyzing their initiatives reported in their 2018 corporate social responsibility (CSR) reports. Environmental performance of 859 Asian organizations were compared across eleven major Asian countries/regions (China Mainland, Hong Kong, Indonesia, Japan, Malaysia, Philippines, Singapore, South Korea, Taiwan, Thailand, and Vietnam). An exploratory factor analysis was conducted to examine the factor structure of company environmental performance in this region, which suggested a bi-factor structure with a general factor and three group factors. Study three examined and demonstrated the convergent and discriminant validities of companies’ initiative-based environmental performance with third-party Environment, Social, and Governance (ESG) ratings. Study four investigated the relationship between top management (CEO and board of directors) characteristics and organizations’ environmental performance. Finally, study five analyzed the relationships between organization environmental performance and financial performance. Together, these studies constitute the first in depth, psychologically informed, and quantitatively sophisticated investigations of pro-environmental organizational actions in Asia. The findings stand to inform the literature of organizational environmental sustainability in general, and in Asian organizations in particular.Item Synthesis of benzophosphole oxides and carbene generation through [3+2] cyclization and preparation of monomers for RAFT and ATRP polymerization(2024-07) Wang, RuiqinThis dissertation consists of four main chapters. Chapter I is a brief review of several types of [3+2] cycloaddition reactions and their relationships to the studies described in Chapter 2 and 3.Chapter II discusses the phosphole oxide study stemming from an attempt to generate carbene using the well-studied hexadehydro-Diels-Alder (HDDA) reaction. For this project, trialkynylphosphine, dialkynylphosphine and alkynylphosphine have been synthesized and evaluated as trapping agents in HDDA reactions to synthesize phosphole oxides with different functional groups through a net [3+2] cycloaddition process. Factors that may influence the outcomes of this type of reactions, such as solvent systems, the sizes of alkynylphosphine terminal groups, the sizes of the HDDA benzyne precursor terminal groups, and participation of water, have been studied. Chapter III is a detailed discussion of reactions between alkynylpyridine derivatives and allenes. A recent study of alkynylpyridine derivatives reacting with activated alkynes showed that allenes are promising substrates that may also react with allenes in a similar fashion. Allenes with various levels of activation and substitution patterns have been attempted to study their relative reactivity for the [3+2] carbene generation. The mechanisms which account for different reaction outcomes have been closely examined. Some of the alkynes that are the tautomers of the allenes tested have been used to compare their relative reactivity under the same reaction conditions. Due to the analogous structural features of isocyanates and isothiocyanates, similar reactions have also been attempted with these substrates and the same carbene generation processes have been observed for these experiments as well. The substrate scope may help future researchers explore the possibilities of three-component reactions as well as trapping the carbene intermediate. Chapter IV covers the topic of synthesizing structurally interesting monomers as future polymer building blocks. These monomers derived from a lactone acid, which was prepared through the Diels-Alder reaction between itaconic anhydride and furfuryl alcohol. Different moieties have been incorporated into the said lactone acid to prepare these monomers for both reversible addition fragmentation chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP).Item DMSO-Free Cryopreservation of Therapeutic Cells by Agarose Hydrogel Encapsulation(2023-07) Wang, MianIn recent decades, the rapid advancement of cell therapy and regenerative medicine has generated an urgent need for efficient and safe cell/tissue cryopreservation techniques on both laboratory and industrial scales. The current use of dimethyl sulfoxide (DMSO) as a cryoprotective agent (CPA) presents toxicity concerns, prompting the development of alternative methods. The primary objective of this research is to develop a novel cryopreservation method for therapeutic cells using hydrogel encapsulation, which aims to minimize cryoinjuries while eliminating the need for toxic penetrating CPAs such as DMSO. The dissertation consists of three main parts. In the first part, molecular changes associated with warming injury in cryopreserved human white blood cells (WBCs) were analyzed. It was observed that slow warming led to irreversible dehydration of cell membrane lipids and denaturation of cellular proteins. Also, WBCs were found to be very susceptible to kinetic processes during warming, including eutectic crystallization/melting, devitrification, and ice recrystallization. The second part focuses on the development of an encapsulation cryopreservation method using the combination of agarose hydrogel and trehalose as an alternative to membrane-permeable CPAs. A comprehensive analysis of the kinetic and thermodynamic changes within the agarose-trehalose hydrogel during freeze/thaw was conducted. The combination of agarose and hydrogel was found to reduce ice phase volume with a less ordered structure, eliminate eutectic crystallization and melting, and inhibit ice recrystallization during warming. The third part of the dissertation involves the validation of the DMSO-free hydrogel encapsulation method for the cryopreservation of natural killer (NK) cells. High post-thaw cell viability was achieved, while decreased viability with compromised cytotoxicity was observed after cells were extracted from the hydrogel. Ongoing efforts are focused on optimizing the cell extraction process from the hydrogel.Item Sentenced to Struggle? How Policy Barriers Impact the Mental Health of People with Criminal Records & Their Children(2024-07) Berry, KaitlynNearly one third of all US adults have some form of a criminal record, placing them and their families at heightened risk for poor mental health. In addition to mental health challenges, people with criminal records face substantial barriers to accessing employment, public benefits, public housing, and other aspects of daily life. Many of these barriers are legally mandated by policies known as the collateral consequences of criminal conviction. Despite the well-established link between criminal history and poor mental health and the abundant literature on these policy barriers, prior research has not investigated the role that collateral consequence policies play in shaping the mental health of this population. Using linked data from large social science surveys and state policy databases, I investigate the association between living in a state with more severe collateral consequence policies and mental health among (1) parents with criminal records, (2) adolescents whose fathers have criminal records, and (3) adults with criminal records. Contrary to my primary hypothesis, I do not find evidence linking overall collateral consequence policy severity to poor mental health among adults with criminal records or among their adolescent children. However, I find weak evidence that policies within specific domains—including access to criminal records, drivers’ license privileges, and employment—may be associated with worse mental health. Additionally, subgroup analyses show that living in states with high barriers may be detrimental for mental health among non-Hispanic Black people and women with criminal records specifically. One interpretation of these findings is that the mental health consequences of actual interactions with the criminal legal system (e.g., arrests, incarcerations) are too ingrained to be modified by subsequent downstream policies. Thus, efforts to improve mental health among families impacted by criminal records should focus upstream on reducing initial criminal legal system contact.Item 3D Bioprinting of Complex Cellular Alignment through Pre-aligned Anisotropic Microtissues(2023-07) Vogt, CalebThe gastroesophageal junction, where the esophagus empties into the stomach, is a unique structure in the body that presents a challenge to current tissue engineering processes. In addition to the common requirements of vascularization, innervation, and precise positioning of multiple types of cells, the muscular structure itself is highly complex in its alignment of smooth muscle bundles. Although much progress has been made in engineering the alignment of muscle cells in single directions, reconstituting structures of the complexity found in the gastroesophageal junction has not been demonstrated. This work provides a review of the gastroesophageal junction from the tissue-engineering perspective and presents a novel 3D bioprinting technique that could one day address this muscle alignment issue.Item Can Young Children Control Their Creativity? Examining the Role of Executive Function in Modifying Children’s Creative Processes(2022-07) Vaisarova, JulieClaims that creativity declines after early childhood often imply that the development of executive function (EF) skills, which underlie goal-directed thought, is antithetical to creativity. Research with adults suggests that top-down regulation can both constrain idea-generation and support aspects of creativity, such as generating ideas strategically and evaluating their quality. Asking adults to “be creative” during a divergent thinking (idea-generation) task strengthens the link between creativity of ideas and executive skills, suggesting that adults use these skills to modify their ideation (Nusbaum et al., 2014). Whether EF functions similarly in children’s creative processes, however, remains unclear. This project investigated whether young children use EF to modify their idea-generation when asked to “be creative.” 148 typically developing 5- to 6-year-olds (most of them White, non-Hispanic, and from high-income homes) participated in a video call with a researcher. During this call they completed behavioral tasks to assess verbal skills and EF, as well as the Alternate Uses Task (AUT) – a divergent thinking task in which they generated uses for objects. In the AUT, children were randomly asked to either come up with “as many ideas as you can” or come up with “ideas that are creative.” The effect of these instructions on children’s creativity depended on EF; children with relatively high EF scores generated more creative ideas when asked to “be creative,” but this effect was not seen in children with lower EF scores. Instructions did not affect the number of ideas generated (fluency), regardless of EF. Rather, EF showed a small negative effect on fluency after controlling for age, surgency, and verbal skills. The results suggest that 5- to 6-year-olds from a Western, relatively high-income population tend to approach idea-generation tasks in a relatively spontaneous, bottom-up way but can also use their EF skills to modify their ideational process according to task goals. How exactly children use their EF skills to modify their ideation remains a question for future research.Item Innovative Autonomy. Transformed Subjectivities In Austrian Short Fiction And Radio Plays(2024-05) Treber, BjornThis thesis focuses on modern short fiction that demonstrates a linguistic and narrative “governance of subjectivities”, i.e. that problematizes individual autonomy on a diegetic level. By showing the interconnections between historical and subjective crises in the plot, this dissertation will also make the historical transformations in literary forms of autonomy apparent – forms which have been progressing towards an “endgame” of the traditional sense of autonomy in the course of the 20th century, in turn leading to a new narrative mode of governance and a new practice of literary autonomy which is interrelational, intersubjective, intermedial, intertextual, and - in relation to the authors depicted- politically committed. In order to demonstrate this, particular attention is paid to three key motifs: the play, the face, and the mirror as they are manifested in literature from the First to the Second Austrian Republic, spanning the period from the 1920s to the 1970s. The chosen short-fiction works show that autonomy is inevitably at stake, either explicitly or in subtext. Through a close reading of the texts and analysis of the three key motifs, I plea for a more refined historical genealogical understanding of this notion within a relational theoretical framework. It attempts to re-conceptualize the basic underlying individual paradigm of literary autonomy through the lens of modern short fiction, including radio plays.Item Development of Electrochemical Sensors through Molecular Design and Sensor Modifications(2022-06) Troudt, BlairThis dissertation focuses on three main research topics. One is the design and improvement of aqueous reference electrodes for long-term stability (Ch. 2-4). The second is the design of novel fluorous phase ion-transfer voltametric sensors (Ch. 5-6) and the third is the study and synthesis of a suitable probe for aldehydes to be self-assembled onto graphene-based electrochemical sensors (Ch. 7-8). Recently, the development of stable working electrodes for long-term electrochemical analysis has taken great strides. However, the improvement of references electrodes has not kept up. Commonly used, commercially available reference electrodes such as double-junction electrodes are not suitable for long term measurements as they must be refilled often. While glass-frit based reference electrodes have lower flow, they suffer from irregularities in their potential due to ionic strength changes, stirring, and contamination. To alleviate all these problems associated with these aforementioned aqueous reference electrodes, an Ag-AgCl capillary-based reference electrode was developed. Utilizing a capillary-based salt bridge provides a stable interface for electrochemical measurements, while also decreasing the volumetric flow of these electrodes to about 100 nL/h. The larger diameter of the capillary in comparison to glass frit pores eliminates the issues associated with charge screening as well. These characteristics not only reduces greatly the need to refill capillary-based reference electrodes, making them ideal for long-term measurement, but they also are ideal for use in low-volume samples where previously only quasi-reference electrodes could be used. The exploration of ion-transfer voltammetry using a fluorous phase is of great interest as a possible technique to detect and measure the presence of perfluorinated contaminants in many types of aqueous samples, including both environmental and biological. Two strategies for their detection through ion-transfer voltammetry with a fluorous phase are discussed, including thin-film ion transfer voltammetry and three phase electrodes. Thin-film electrodes typically rely on a conductive polymer to act as an ion-to-electron transducer which is then coated in a thin polymer membrane. While these electrodes have only been fabricated with organic membranes, here the goal is to modify these with thin fluorous membrane. Synthesis of a suitable highly fluorophilic monomer, 3-[tris-[2-(perfluorohexyl)ethyl]silyl]thiophene, which will be compatible with a fluorous membrane is described. Alternatively, three-phase electrodes could provide a strategy for the detection of perfluorinated contaminants. These electrodes rely on a three-phase boundary between two immiscible solutions and the working electrode to measure the transfer of ions from at the liquid-liquid interface. Again, these electrodes have only been reported using an aqueous/organic interface. Here the analysis of different three phase electrode set ups for use with a fluorous phase is presented, including a paper-based set up, a pencil graphite set up, and a gelled organic platinum mesh set up. Three phase electrodes require a redox active species in the hydrophobic phase. So, a suitable, more fluorophilic compound, (3-perfluorooctylpropanoyl)ferrocene, was synthesized and used in fluorous three phase electrodes to demonstrate the transfer of perfluorinated ions at the aqueous/fluorous interface. Lastly, the development of a probe for the detection of aldehydes with graphene-based electrochemical sensors is described. A direct comparison of the kinetics via NMR spectroscopy of two commonly used aldehyde derivatizing agents, phenyl hydrazine and O-phenylhydroxylamine, is presented. This work shows that phenylhydrazine reacts, on average, 71 times faster with aldehydes than does O-phenylhydroxylamine, indicating that development of a hydrazine derivative for aldehyde sensing purposes is preferred. The synthesis of 4-hexadecylphenylhydrazine is described as well as its successful self-assembly onto graphene from a solution of tetrahydrofuran resulting in a good fit with Langmuir adsorption theory (LogK=3.93) and indicating a concentration of 1.05 mM is needed for a 90% coverage monolayer.Item Machine Learning in Conjunction with Molecular Simulations for Nanoporous Materials Discovery(2022-07) Sun, YangzeshengChemical storage and separation are critical in solving various energy and environmental problems in the real world, and nanoporous materials are believed to be promising candidates for these applications. The synergy among experiments, computer simulations, and machine learning opens up possibilities to revolutionize nanoporous materials discovery, where new materials can be designed dramatically faster with a fraction of the cost. This dissertation research develops a series of machine learning methods based on high-throughput molecular simulation data for nanoporous materials discovery. First, a brief background on molecular simulations, machine learning, and their application in nanoporous materials discovery is introduced. Then, Chapter 2 develops a machine learning model, named SorbNet, on the optimization of the desorptive drying process. SorbNet is trained using loss function based on statistical mechanics principles of Monte Carlo simulations. The prediction given by SorbNet is used to perform the design of the drying process of alkanediols in zeolites. The capability of transfer learning of a pre-trained SorbNet model is also demonstrated. Chapter 3 extends the research in Chapter 2 to much more complex separation processes and develops SorbNetX, a physics-informed model for mixture adsorption. SorbNetX originates from the ideal-mixture adsorption model in statistical mechanics, and by incorporating the principles of adsorption equilibria, SorbNetX accurately predicts the adsorption of a 8-component mixture using only unary, binary, and ternary data. Next, Chapter 4 employs meta-learning to the joint optimization in material space and state space for vehicular hydrogen storage. The meta-learning model, SorbMetaML, gives higher accuracy and improved generalization compared to fitting a model separately to each material and identifies the optimal hydrogen storage conditions for a variety of nanoporous materials including zeolites, metal--organic frameworks, and hyper-cross-linked polymers. Finally, Chapter 5 analyzes and predicts the adsorption in nanoporous materials at a crystal structure level. This chapter introduces the concept of spatially-resolved loading surface of nanoporous materials and develops the SorbIIT model as the first data-driven method to generate a continuous spatially-resolved loading surface.Item Experimental studies of ammonia-hydrogen diffusion flames for kinetic model development(2022-07) Thomas, DanielThe motivation for the work presented in this dissertation is the need to better understand the kinetics of ammonia combustion, and in particular that of ammonia-hydrogen fuel blends. Ammonia has been the subject of growing interest as a carbon-free fuel for storing renewable energy. The combustion of ammonia presents challenges in flame stability and emissions of unburned ammonia and nitrogen oxides. The limitations of current kinetic mechanisms for ammonia combustion are evident in the discrepancies between predictions and measured levels of nitrogen oxides across a wide range of flame conditions. A primary goal for this work was to provide in-flame and exhaust species measurements to extend database available for kinetic mechanism validation to non-premixed flames, for which little data exists. Two canonical non-premixed flames were studied in this work: (1) the counterflow diffusion flame, which can be modeled as a quasi one-dimensional system, and (2) the co-flowing diffusion flame, which can be modelled as an axi-symmetric two-dimensional system. Laser-induced fluorescence (LIF) was used to obtain non-invasive measurements of species in the flames studied. Saturated planar LIF was used for species profiles of nitric oxide (NO), imidogen (NH) and hydroxide radicals (OH). The saturated NO and OH profiles were calibrated by laser absorption, measured by fluorescence intensity in a bi-directional configuration. Saturated LIF NH profiles were calibrated via the OH absorption measurements. NH₂ radicals were also measured by planar LIF, and chemiluminescence used to obtain profiles of the exicited states OH* and NH₂*. For the co-flow flame, exhaust nitrogen oxide levels, including nitrogen dioxide (NO₂) and nitrous oxide (N₂O), were measured with a Fourier Transform Infrared (FTIR) spectrometer. In addition, extinction strain rates of the counterflow flame were measured for low hydrogen content fuel. Species and extinction measurements from this work were used to evaluate existing kinetic mechanisms for ammonia combustion, and to update a recently-published mechanism by Shrestha and coworkers. The updated kinetic model showed significant improvement in predicting the experimental results, and better performance than the selected existing mechanisms. The updated kinetic model also performed well when validated with published data from premixed ammonia-hydrogen flames. However, remaining discrepancies between predictions of NH and NO and the experimental results in this work indicate the need for additional work in understanding amine radical (NHᵢ) reactions and NO formation in ammonia flames.Item Stochastic Curtailment: A New Approach to Improve Efficiency in Computerized Adaptive Tests(2024-05) Tai, Ming HimStochastic curtailment (SC) is a statistical procedure that was originally developed to enhance the efficiency of clinical trials. It has been applied to psychological testing, but to sequential mastery testing only (Finkelman, 2008, 2010). This study adapted the method to detect low-precision examinees (i.e., examinees whose final standard error of measurement (FSEM) at the end of a full-length test could not reach the pre-specified SEM termination level) in measurement computerized adaptive tests (CATs). Using central limit approximations, the study developed a method to estimate the distribution of test information at maximum test length and the corresponding FSEM. The study also developed a hypothesis testing procedure to implement SC. Using monte-carlo simulations, the study found that (1) the FSEM estimation procedure performed well in the middle range of ? values but less so at extreme ? values; (2) the SC procedure had good predictive accuracy, with excellent performance on positive predictive values and good performance on true positive rates and false positive rates; (3) the reduction in test length was substantial. Overall, the study showed that SC is a promising procedure to identify low-precision examinees and enhance efficiency in measurement CATs. A guide on implementing SC is provided.Item Bi/ology: Biologism, Masculinity and Pedagogy in Bi+ Theory and Activism(2024) Shackelford, LukeThrough a combination of queer/trans philosophical methods, rhetorical history, and modified grounded theory, this project seeks to contribute to both the Rhetoric of Health and Medicine and Writing Pedagogy in the analysis of Bisexuality and bisexual masculinity in historical and digital communities. First, the project establishes a conceptual argument that bisexuality in medical rhetoric functions as both a foundational nexus for western medical taxonomy, and a threat to the conceptual boundaries in that same taxonomy, centering on the destabilizing effect of bisexual men on concepts of gender and sexuality. By challenging the bio/logics associated with stable categories, yet still expressing partial legibility as a category itself, bisexuality provides a useful conceptual lens to study processes like medicalization of identity categories, and the interaction between expert and public medical rhetorics. Then, the project looks at the function of bisexuality and masculinity in activist rhetoric and community pedagogy. By analyzing three historical activists as paradigm cases through archival materials and oral historic interviews, the study finds bisexual men articulate their masculinity as a form of pedagogy. In promoting radical inclusivity, utilizing irreverent humor, and agonistic divestment from neoliberal identity politics, bisexual men involve themselves in community through sexual health activism, conference and archive organizing, social work, and state policy implementation. In doing so, bisexual men knowingly or unknowingly respond to the public spread of medical bio/logics, shifting the conversation away from trace logics of identity and to community engagement and support. Finally, this project moves to grounded theorycrafting in studying the conversations of contemporary digital communities founded by and for bi+ masc folk. By incorporating existing scholarship and the paradigm cases alongside in-vivo coding and abstraction, my research ensures these communities remain anonymous–however, they still provide valuable insights into the way bisexual men continue to move alongside, with, or against bio/logical discourse. By tackling interpersonal and ethical considerations of polyamory, intra-community misogyny, gender expression, and considerations of self-mastery, this project finds that these bisexual men value nuance, fair treatment, and utilizing their desire to erode the binary of masculinity and femininity, even while they may often resort to hegemonic tropes of masculinity in their self-understanding. In the interest of developing pedagogical interventions to connect these values to political solidarity, this project finally proposes ways to orient academic and public pedagogy around such values. This project ends with a theoretical speculation on the nature of bisexual community, and the possibility that bisexual politics necessitates the metaphorical death of such communities.Item Identifying Efficacious Therapies for High Glycolysis Metastatic Castration-Resistant Prostate Cancer(2024-07) Su, Mei-ChiMetastatic castration-resistant prostate cancer (mCRPC) remains a deadly disease due to a lack of efficacious treatments. The reprogramming of cancer metabolism toward elevated glycolysis is a hallmark of mCRPC. However, the current drug discovery on finding drugs efficiently inhibiting high glycolysis tumor growth is challenging due to metabolic plasticity. Our goal is to identify therapeutics specifically associated with high glycolysis while reducing the risk of weakened efficacy from metabolism plasticity. We established a computational framework to identify new pharmacological agents for mCRPC with heightened glycolysis activity under a tumor microenvironment, followed by in vitro validation. Using our established computational tool, OncoPredict, the likelihood of drug responses was imputed to approximately 2300 agents in each mCRPC tumor from two large clinical patient studies. Drugs predicted to have high sensitivity, either strongly correlated with glycolysis scores or with both glycolysis and oxidative phosphorylation (OXPHOS) scores, were selected. In total, ten drug candidates were finalized. Ivermectin, CNF2024, and P276-00 were chosen for subsequent in vitro validation based on the highest measured dose-response curve AUC associated with glycolysis/OXPHOS in pan-cancer cell lines. By decreasing the input glucose level in culture media to mimic the mCRPC tumor microenvironments, we induced a high-glycolysis condition in PC3 cells and validated the projected better tumor inhibition of all three drugs under this condition (p < 0.0001 for all drugs) after 48 hours of treatment. For biomarker discovery, ivermectin and P276-00 were predicted to be more sensitive to mCRPC tumors with low androgen receptor activities combined with high glycolysis activities (AR(low)Gly(high)). In addition, we integrated a protein-protein interaction network and topological methods to identify drug response predictive biomarkers and prognostic factors for patients with mCRPC. EEF1B2 and CCNA2 were identified as drug response predictive biomarkers for ivermectin and CNF2024, respectively, and prognostic factors for patients with mCRPC. Additionally, DLGAP5, KIF11, and CDK1 were identified as drug response predictive biomarkers for P276-00 and prognostic factors for patients with mCRPC. In conclusion, this study offers new efficacious therapeutics beyond traditional androgen deprivation therapies by precisely targeting mCRPC with high glycolysis.