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The dark universe: the interplay of cosmological moduli, axions, and the MSSM
Get PDFIn this work, we introduce two effective field theories which parameterize a light modulus field interacting both with the MSSM (MSSM) and with the MSSM combined with an additional supersymmetric DFSZ axion (PQMSSM). All two-body decays of the modulus are cataloged and connected to explicit string scenarios, with all model-independent decay widths calculated incorporating mixing and phase-space effects for the first time. Dark matter and dark radiation production are studied in both models for a subset of string scenarios, with comments provided on expectations for the remaining scenarios. Quite generally, we find that many string scenarios with a modulus-driven early matter dominated period overproduce dark matter and/or dark radiation. The overproduction of dark matter may be remedied with a sufficiently large modulus mass, however various consistency conditions show that most scenarios are incompatible with weak-scale supersymmetry and with a DFSZ-type axion, at least without additional model-building. We also study statistical properties of the Peccei-Quinn scale and the derived value of the SUSY -term in the string landscape. Here, we find the predicted value of is in the cosmological sweet-spot for axion dark matter, while the predicted higgsino masses are slightly above current LHC bounds. Additionally, we study the predicted nature of viable dark matter candidates in explicit inflationary scenarios in string theory, finding a WIMP in K\"{a}hler inflation and open string axions in fibre inflation to be natural dark matter candidates
Mechanical performance of post-tensioned residential foundation slabs using expansive BCSA cements
No full textRecent research in concrete materials and structural behavior has focused on alternative cements to increase sustainability as cement manufacturing is a leading producer of CO2 emissions. One promising alternative is calcium sulfoaluminate (CSA) cements. While expansive Type K CSA additives have been used for shrinkage compensating concrete for many years and rapid setting, belitic CSA (BCSA) has found widespread use in pavement repair and precast applications, there has been little research comprehensively analyzing the behavior of CSA cements with both expansive and rapid setting properties.
This research focuses on characterizing the performance of an expansive, rapid setting BCSA cement. This novel cement could be used for post-tensioned slab on grade design that would reducing shrinkage and mitigate prestress losses, resisting the high flexural stresses that result from expansive soil subsurface movements. This can improve the long-term durability and life cycle of these slabs and reduce the magnitude of prestressing forces required for these slabs to resist subsurface movements. Mix designs were developed to provide sufficient workability and working time while achieving sufficient strength at an early age for post- tensioning on the same day, at 6-8 hours after casting. Material properties including elastic modulus, modulus of rupture, restrained and unrestrained expansion, and creep were measured with small scale specimens to establish material properties, and a comparable expansive, non- rapid-setting Type K cement mix was subject to the same tests for comparison. Additional testing was conducted to provide guidance on field curing and retardation procedures. Finally, large-scale post- tensioned slabs were cast with both mixes alongside a conventional portland cement slab, to assess field performance against predictions from measured properties.
Measured mechanical properties show higher strength than those of the conventional portland cement mix design. Considerable strength increases are observed with the expansive BCSA cement as time of wet curing increases, however subsequent drying can reduce these gains. High sensitivity to temperature was observed, requiring greater attention to retardation admixture dosages. Measured values for long-term prestress losses indicate considerably reduced creep and shrinkage behavior, further offset by concrete expansion. Existing ACI 423 models for creep and shrinkage differed greatly from measured values but yielded more accurate estimates with relatively simple adjustment. The large- scale expansive BCSA slab showed agreement with property characterization, exhibiting lower creep and shrinkage than either the Type K or conventional portland cement concrete slabs
Boundary breaking: how principals impact student engagement
Get PDFThe purpose of this study was to understand the impact site principles have on student engagement in the classroom through a sitewide art integration program with the outcome of increased knowledge in content areas. Researching the use of a sitewide art integration program at a Midwest high school, case study methodology was applied to administrator and teacher interviews using annual state test scores to triangulate for authenticity and impact. Six themes were identified from the interviews to have an impact on student engagement and increased content knowledge due to the art initiative. Those six themes were gathering teacher buy-in, the role of the administration, lack of enthusiasm, the impact of A Plus professional development, enhanced school climate and culture, the faculty demonstrated growth through A Plus, and student outcomes.
The results of the study indicated that principals do impact student engagement in the classroom with the outcome of deeper knowledge of content matter. Four areas for future research developed based on study findings. Because the faculty at the school of study was all white, a study with a diverse faculty and school would add to the literature of principal leadership affecting student engagement in the classroom. Future study is necessary to examine how an intentional leadership theory can have a greater or lesser impact on a sitewide art initiative with an outcome of increased student engagement and deeper learning of content matter. A disconnect was uncovered between the teachers’ perception of the climate of the school and the administrators’ perception of the climate of the school related to the art initiative; therefore, further study could clarify this dissonance. Finally, students who had excellent ability on the end of year state tests had a lower performance outcome after the art initiative. This could be due to some teachers’ lack of enthusiasm for the art initiative. Thus, additional research is warranted.
Transport of Nanoparticles in Porous Media by Numerical Simulations
No full textThis thesis focuses on three primary topics related to the movement of fluid and nanoparticles (NPs) in porous media. While prediction of local fluid velocities within porous media are significant, conducting experiments to measure them can be exceedingly difficult. Therefore, this work aimed to develop methods to predict velocity distributions in porous media. The lattice Boltzmann method was applied to solve for the fluid velocity fields through different media, such as sphere packings, scaffolds, sandstones, carbonates, and synthetic silica. The one-sample Kolmogorov-Smirnov (KS) goodness-of-fit statistical tests were utilized to examine whether the velocity distributions in different porous media followed any known distribution types, whereas the two-sample KS goodness-of-fit tests were used to determine if the velocity and pore-size distributions are statistically similar. Simulation results indicated that the velocity magnitude and pore volume in a porous medium follow the same distribution for all the examined porous media with continuous pore size distributions. In addition, velocity magnitude distributions in scaffolds and sphere packings with random configurations could be predicted by a single Weibull distribution model within statistical accuracy.
The hydrodynamic dispersivity of nanoparticles (NPs) is a significant parameter in determining their mobility, and our study sought to investigate this parameter using the Lagrangian approach, as opposed to the Eulerian approach that has been commonly employed in previous studies. The lattice Boltzmann method (LBM) was employed to simulate flow in porous media, and Lagrangian particle tracking (LPT) was used to track the movement of individual dispersing particles without considering the particle-particle interactions. In other words, the movement of particles was a consequence of both the molecular diffusion of the particles themselves and the convection of the surrounding fluid. It was found that the hydrodynamic dispersion coefficient linearly depended on the effective Lagrangian Peclet number, based on a length scale that took the molecular diffusion effects as well as the convection effects into account; and this relationship held for different porous media. More importantly, this linear equation was simpler and more precise than the one formed by using the Eulerian Peclet number with a fixed length scale. This result confirmed that Lagrangian length and time scales were appropriate for modeling particle dispersion.
The mobility of NPs in porous media is significantly impacted by their tendency to aggregate since large aggregates may induce some problems such as pore clogging or blocking and reduce the mobility of NPs. Thus, a new model, Lagrangian Particle Tracking based on the force balance approach (LPT/FB), was built to simulate the aggregation process and to predict the morphology of aggregates when particles move in porous media. It relied on Newton’s second law of motion and took interaction forces among particles into account. Aggregation kinetics and fractal dimension results from the computational model for Cerium oxide (CeO2) particles, suspended in potassium chloride (KCl) solutions with different concentrations, were verified against experimental results. The model was then employed to investigate the effects of ionic strength, pore velocity, and particle size on the aggregation of CeO2 particles together with their fractal dimension and asphericity when they moved in randomly packed spheres. The electrolyte concentration was found to be the most important factor impacting the aggregation process and the aggregate structure. It was followed by the pore velocity, which considerably influenced the aggregation kinetics and fractal dimensions, especially in the diffusion-limited regime. The primary particle size had a minor effect on the aggregation kinetics but created a noticeable change in the fractal dimension of reaction-limited aggregates
The Impact of Hydrogen Blending on Emissions and Performance of a Natural Aspirated Engine
Get PDFThere has been a significant focus on developing alternative fuels and energy sources in order to mitigate the adverse effects of fossil fuel combustion on the environment. Among promising options, hydrogen stands out owing to its high energy density and clean combustion characteristics. The use of hydrogen in internal combustion engines, particularly in four-stroke engines, has been extensively studied. However, research on hydrogen combustion in two-stroke engines is limited, even though these engines are widely used in various industries, including the oil and gas sector. This study aims to report novel test results highlighting the exhaust emissions and performance of a large-bore internal combustion reciprocating two-stroke engine fueled with hydrogen-natural gas mixtures, that is the AJAX DPC-81. Natural gas-hydrogen mixtures with different hydrogen concentrations are examined with various engine loads and equivalence ratios. The emission concentrations of nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), unburned methane (CH4), and volatile organic compounds (VOCs) are measured with corresponding mentioned parameters. Indicated thermal efficiency is computed to expose the combustion performance of the engine. Results found in this study can be adopted for engines that have a similar combustion system to that of the AJAX DPC-81. It is found that emissions are reduced significantly with increasing hydrogen concentration and engine load. The maximum reduction in NOx, CO, CO2, CH4, and VOCs emissions are approximately 90%, 33% 13%, 33%, and 55% respectively at 40% volumetric H2 concentration. Overall, indicated thermal efficiency increases steadily with hydrogen volume fraction in the fuel mixture. At 75% load and 40% volumetric H2 concentration, the engine achieves the highest efficiency of approximately 33%. The optimal operating condition for the AJAX DPC-81 is also determined to be at 60% load with 40% H2 concentration and 60% bypass valve position combined
Connecting diversity indices, ecosystem processes, and language use to better understand and manage freshwater systems
Get PDFRivers and streams are among the world’s most threatened ecosystems despite the importance of freshwater to human society. Rivers have been dammed, dried, and moved for human needs and consumption. They have experienced a dramatic loss of biodiversity, particularly in response to human population growth and climate change. Understanding the drivers of ecological community change is vital to mitigate threats to water scarcity and biodiversity. In my dissertation, I explore how elements of climate change, river drying, and dam management alter river biodiversity. By quantifying how aquatic assemblages change in response to multiple stressors, my work highlights ways to better manage river ecosystems in a future that will be increasingly defined by changes in climate and water use. Further, the development of effective management strategies depends on effective communication of research findings. Therefore, I also analyze language use describing dry river systems, and provide universal definitions. Combined, my research addresses multiple threats to freshwater diversity across space and over time in complementary ways to allow for better river management and protection.
Rivers and streams that sometimes cease to flow (non-perennial streams) are the most common form of flowing waterways on the planet. In the past 20 years, research on these systems has increased exponentially across multiple disciplines. Despite the need to connect research across scientific fields to better understand these dynamic systems, a consensus on terminology has not been reached, making meta-analyses, syntheses, management, and policy difficult. Published in 2020, my first chapter quantitatively explored 12 frequently used names for non-perennial streams over time and suggest universal terms and definitions. I found no consensus for a single name in any scientific field, but found substantial research overlap when exploring research topics across terms. I also found significant thematic overlap in definitions across papers from various fields of study, indicating redundancy across many terms. Finally, I suggest universal definitions for three specific terms to better facilitate effective communication across research fields, the public, and policy makers.
As climate change alters physical environments, understanding changes in community structure is essential for effective management and species conservation. While species diversity has historically been the focus of community studies, research demonstrates the value of using functional and phylogenetic diversity. Functional traits describe differences in ecological roles among species and phylogenetic diversity captures the evolutionary relatedness among species. For my second chapter, published in 2023, I explored changes in fish community composition in streams across Oklahoma over a 42 year time frame to see how shifts in the physical environment alter functional and phylogenetic diversity. I found that historical diversity influenced how communities changed over time. That is, historically less diverse communities changed in a different way than historically more diverse communities did. Changes in functional richness demonstrated the importance of environmental conditions while phylogenetic diversity trends showed no clear trend of community structure. Both types of diversity, however, were significantly correlated to annual changes in maximum temperature. Overall, I found that community assembly has changed over time, although specific changes were related to the historical diversity of the community.
Though aquatic ecologists have long recognized the importance of flow variation in flowing rivers, these variations do not represent the full conditions biological communities may experience in streams that seasonally dry, known as non-perennial streams. For non-perennial stream communities, equally important to flow variation are the drying and wetting regimes, or the characteristics of drying and wetting events. Drying and wetting can act as disturbances on these systems, and the timing, duration, frequency, magnitude, and rate of drying and wetting could have varying effects on riverine communities. My third chapter connected drying and wetting characteristics with patterns of macroinvertebrate, soft-bodied algal, and diatom assemblages. I found the amount of flow duration prior to sampling was correlated with macroinvertebrate and soft-bodied algal assemblage structures, though I found no drying or wetting characteristics predicted richness of these two assemblages. Diatom richness and structure, however, were heavily influenced by the date of drying. Thus, I found no single characteristic that explained structure or richness across every assemblage, highlighting the need for multiple ecological and hydrological benchmarks to meet management goals. Given the increasing prevalence of non-perennial freshwater ecosystems, understanding how various drying events influence stream communities is important to understanding these dynamic systems.
Humans have a long history of controlling water flow, particularly through the construction of dams. Dams vary in size, purpose, and management strategy, which combined can significantly change the temperature, flow, and physical structure of downstream waters. Southeastern Oklahoma provides a unique opportunity to compare management strategies across rivers of similar ecological and evolutionary histories. Three out of four major rivers in southeastern Oklahoma are dammed; each dam is managed for a different purpose and the presence of a fourth, unimpounded river provides a unique opportunity to understand how management alters ecological communities. In my last chapter, I used field surveys to sample sites above and below dams, as well as sites along a fourth unimpounded river. I found significant biological differences among the four rivers, but smaller differences among site types across the rivers, regardless of dam presence or management type. While biologic metrics did not show differences among site types, ordinations with full assemblage data did indicate some effect of dams on assemblage composition. We found biological metric and assemblage differences in this study were correlated to both local and watershed environmental variables. The higher elevation regions between these four watersheds may lead to biogeographic barriers, isolating the assemblages within each river. In addition, the strong aerial dispersal ability of many of the common taxa we found may allow for dispersal longitudinally along the rivers, damping the influence of dams on differences between communities upstream and downstream of the impoundment. The nuances within the results of our data highlight the importance of site-specific studies to fully understand how anthropogenic activities alter riverine ecosystems. As demands for freshwater continue to grow, clearly understanding how dam management strategies alter river communities will allow for clearer policies to protect these ecosystems.
Taken together, my dissertation broadly examines the impacts humans have on freshwater systems. Understanding the effects of multiple stressors on these diverse ecosystems and sharing common language is crucial to understanding how to properly manage them. My research highlights how rivers have responded to environmental alterations, which, via climate change, are only expected to continue and increase in magnitude and will provide novel ways to manage these diverse, dynamic, and threatened systems
Love, Loss, and Memory: An Analytic and Hermeneutic Discussion of Clara Schumann’s Drei Romanzen, Op. 21
Get PDFOne of Clara Wieck-Schumann’s last compositions, Drei Romanzen, Op. 21 is a set of three romances composed in 1853. The analysis which follows discusses the three romances of Op. 21 through the lens of large-scale ternary form and hermeneutic implications. This thesis begins with analytical discussions of each romance, discussing form, harmonic and phrase structure, and key motivic elements. After my discussion of the individual pieces, I will look at the set as a whole through the lens of large-scale ternary form and the pastoral as an expressive genre which situates their structures, topical, and intertextual hermeneutics.
Following my analysis, I discuss how the topical references to the pastoral, coupled with themes written by Robert Schumann, evoke a sense of retrospectivity and idealization of the past. The ways in which these references are paired with recurring melodic motifs indicates continual return to a memory. Considering Wieck-Schumann’s diary entry about feelings of sadness while visiting Robert Schumann in the sanitarium on the day she wrote the first romance, I also interpret elements of Op. 21 as representing her sadness. The interpretation of these elements, combined with introversive and extroversive signifiers culminates in a narrative of lingering romance with Robert Schumann and his works
Leading Through Constraints: Investigating the Effects of Leader Constraint Framing on Creative Processes and Performance
Get PDFAn emerging body of research suggests constraints can either hinder or facilitate creativity and innovation in organizations depending on a variety of factors, including how the constraints are perceived by those engaged in creative work. When perceived as a source of creative challenge or opportunity, for example, constraints can motivate creative engagement and subsequently enhance creative performance. Despite the importance of perceptions like these, research examining the variables likely to influence perceptions of constraints is scarce. In fact, although leaders are often responsible for identifying and communicating constraints to those engaged in creative work, little research has examined communication strategies leaders might use to shape perceptions of constraints in a manner that drives creative engagement and performance. In this experimental study, we examined how a leader’s use of two constraint framing strategies—convergent and divergent—might differentially influence performance on three creative processes—problem definition, idea generation, and idea evaluation. Additionally, we examined whether the effects of these framing strategies are contingent on participants’ creative self-efficacy and the timing in which constraints are introduced throughout the creative process. The findings provide evidence for divergent constraint framing as an effective strategy by which leaders can promote engagement in creative processes and enhance creative performance, particularly when constraints are introduced during early stages of a creative effort. The theoretical and practical implications of these findings for organizational leaders are also discussed
Development and application of high throughput hydrogen deuterium exchange mass spectrometry for characterizing protein interactions in complex biological samples
No full textProtein interactions (e.g., protein-protein interactions and protein-ligand interactions) play an important role in regulating the numerous biological processes that dictate cellular activity. The characterization of protein interactions in their native, complex biological environments (e.g., cell lysate and human plasma) is essential for understanding protein function in real physiological processes. However, the extremely complex nature of biological protein samples impedes the characterization of protein interactions by traditional biophysical methods. Hydrogen–deuterium exchange coupled with mass spectrometry (HDX-MS) has been a powerful technique for characterizing protein interactions over the past 20 years. However, this technique has yet to be adapted to directly characterize protein interactions in real biological samples. This dissertation focuses on the development and application of a high-throughput HDX-MS platform to characterize protein interactions in complex biological samples (e.g., cell lysate and human serum).
The implementation of short LC gradients in the traditional HDX-MS workflow has been necessary to limit back exchange. These short gradients limit separation efficiency and hinder high throughput HDX-MS analysis of protein interactions in complex biological samples. We first evaluated and optimized subzero-temperature ultra-high-pressure liquid chromatography (UPLC) separation conditions for long gradient separation to boost separation power for the HDX-MS analysis of complex protein samples such as E. coli cell lysate digest while limiting back exchange. We found that, compared to the short gradient separation (e.g., 15 minutes), about 3-fold more deuterated peptides could be characterized using long gradient separation (e.g., 90 minutes). Interestingly, we found that peptides eluted at the end of the long gradient maintained high levels of deuterium incorporation due to the peptide-column interactions. Overall, under the optimized conditions, our subzero-temperature long gradient UPLC-HDX-MS platform is capable of characterizing thousands of peptides from hundreds of proteins in a single HDX-MS analysis with limited back-exchange.
To further reduce the complexity of the complex biological samples, we improved our platform by integrating protein thermal depletion (PTD) to reduce protein complexity in cell lysates with our subzero-temperature UPLC-HDX-MS platform (PTD-HDX-MS). PTD allows the removal of the untargeted protein in the cell lysate with lower thermal stability upon exposure to heat while the targeted protein with higher thermal stability remains in solution. We used bovine carbonic anhydrase II (CaII) and its inhibitor acetazolamide (AZM) spiked into E. coli cell lysate as a model system to evaluate the feasibility of our PTD-HDX-MS platform for the characterization of protein-ligand interaction in complex samples. We demonstrated that PTD is an easy and universal strategy to reduce overall sample complexity for HDX-MS analysis. For the first time, we successfully elucidated the interaction site between AZM and CaII in E. coli cell lysate using high-throughput HDX-MS analysis. Our results highlight the great promise of the PTD-HDX-MS platform for the identification of ligand targets and the characterization of protein–ligand interactions in highly complex biological samples such as cell lysates.
With our optimized HDX-MS platform, we mapped the antibody–antigen epitopes with four fully human monoclonal antibodies (mAbs) specific to anthrax protective antigen (PA). Epitope-mapping of mAbs to PA is particularly important because it can help develop novel therapeutics against anthrax. We examined the epitopes for 4 mAbs that were known to have differential neutralizing abilities. We discovered diverse binding mechanisms for these 4 mAbs and, notably, found that a high neutralizing mAb, p6C01, strongly bound to domain three on a helix region on PA. We also identified a secondary epitope for p6C01 that may lead to inhibition of furin cleavage of PA after p6C01 binding. This study demonstrated that the unique epitope for p6C01 results in its highly neutralizing activity. This is the first report of this distinct binding mechanism for a highly neutralizing fully human antibody specific to anthrax protective antigen. These novel epitopes associated with high neutralization activity will facilitate the understanding of the elicited human humoral immune response following AVA vaccination. Overall, characterization of the interaction between vaccine-elicited antibodies and antigens is important for understanding the fundamentals of how a vaccine works, and epitope mapping is especially essential for the development of effective therapeutics. Our high-throughput HDX-MS platform has proven to be capable of discovering novel epitopes relevant to human immune response.
Different population demographics may demonstrate varying levels of immunity after vaccination due to the diversity in expression of vaccine-elicited polyclonal antibodies (pAbs). Therefore, epitope-mapping of vaccine-elicited pAbs is essential for a better understanding of vaccine-induced immune protection. However, due to high sample complexity and the unpredictable binding properties of pAbs, very few techniques can be applied for conformational epitope-mapping of pAbs directly in patient serum. We applied our PTD platform discussed previously to remove unbound antigens to increase the sensitivity for characterization of pAbs-induced epitopes using HDX-MS. We successfully characterized the epitopes induced by vaccine-elicited pAbs in isolated serum antibodies from human donors vaccinated with AVA against PA using PTD-HDX-MS. Overall, our results demonstrate the great potential of the implementation of PTD-HDX-MS for conformational epitope-mapping of pAbs in human-vaccine elicited samples
Born to hula
Get PDFThe thesis represents a body of poems accumulated in response to the COVID-19 pandemic as it continues to spread and the poet's subsequent ruminations in confinement. Born to Hula is a collection of poems exploring the mundane weight of living, confused locality, and its fatigue, the confines of American society and their expressions in dislocation. The impulse of the thesis aims at an exploration of space, the degradation of potential futures, and considerations of the past in honest relief. These poems aim at locating and losing against the threats and follow-throughs in American society. Diners, thought of in these poems as the lighthouses between a slack bed and a hard road, act throughout the collection as a centering place, an oasis of grease and no-eye-contact refills. Born to Hula uses these fixtures as relief against ongoing structures and construction, the unchangeable churning of progress and those left behind. The central motifs of the collection are divided between the local and the dreamscape. These patterns enter on explorations of the area of Edmond and the diners stuck between. The dreamscapes found here act as personal explorations of potential futures lost and the narrowed possibilities of escape against such loss... Together, this thesis serves to illustrate the lost home of the insomniac daydreamers sparsely populating vast plains, and the coping mechanisms reached for in diners and on blank pages