SHAREOK Repository
Not a member yet
49261 research outputs found
Sort by
Fundamental Studies of ParDE Toxin-Antitoxin Systems for Their Potential to Impact Bacterial Cell Growth
Full text linkThe rise of antimicrobial-resistant bacteria, coupled with a shortage of new antibiotics, has threatened treatment of infections as well as modern medical procedures. To counteract with this burgeoning issue, targeting bacterial toxin-antitoxin (TA) systems, which engage in controlling bacterial cell growth under stress conditions, e.g., antibiotics treatment, presents a promising strategy for developing novel antimicrobial agents to combat resistance. TA systems are widely distributed in prokaryotes and the operon is composed of a small bicistronic locus encoding antitoxin and toxin genes. In the case of type II ParDE TA systems, the ParE toxin protein selectively inhibits DNA gyrase, an essential type II bacterial topoisomerase, by stabilizing gyrase-mediated DNA cleavage complex, leading to double strand DNA break. The toxicity of ParE protein can be neutralized by its co-encoded cognate ParD antitoxin protein through direct protein-protein interaction. The work presented in this dissertation aim to provides deeper insights to understand the structural properties of the ParDE TA systems and the impact on bacterial cell growth and resulting influence on mutation driven from ParE-mediated gyrase inhibition. Chapter II of this work focuses on the impact of VcParE toxins induced expression in the native host, Vibrio cholerae (Vc). The results showed that strong expression of VcParE toxins caused cell death, likely arising from extensive DNA break generated by inhibition of gyrase, and overwhelming the repair machinery. However, lower levels of ParE expression could be tolerated, and the induced DNA breaks was able to be repaired, permitting cell survival. As it is known that this type of repair can be error-prone, the result confirmed increases in mutation frequency after lower induction of VcParE toxins. Importantly, however, this did not correlate with decreasing antibiotics susceptibility. Overall these results indicate that VcParE toxins are potent inhibitors of DNA gyrase in bacterial cells, and that damage generated by gyrase inhibition do not lead to increase in antibiotic resistance. Chapter III of this work explore the feasibility to obtain purified ParE toxins following reported methods and developed an optimized purification approach. We tried various expression and purification strategies, including denaturation-refolding of the ParDE complex, in vitro protein synthesis, bulky fusion protein expression and co-transformation with gyrase, to overcome ParE toxicity and obtain sufficient protein for future characterization. Our result showed that co-transformation with gyrase was effective to lessen VcParE1 toxicity and the purified VcParE1 proved to be active in the inhibition of gyrase-mediated supercoiling assay. The approach developed in this chapter enables us to obtain quantitive VcParE1 for future structural studies to further elucidate the structure of ParE-gyrase complex. Chapter IV of this work investigates the intrinsic degradation of the PaParD1 antitoxin, analyzing factors influencing its stability. Our result indicated that the degradation of PaParD1 is affected by temperature, pH value, and concentration, with maximal degradation observed at physiological pH and temperature. Higher concentrations of PaParD1 also increased degradation rate. We also established the effect of ionic strength on PaParD1 dimerization and degradation, with increased degradation rate as the ratio of monomeric PaParD1 increased. While initial hypothesis suggested a glutamine-mediated cleavage mechanism, mutagenesis experiments revealed no direct role for glutamine in PaParD1 degradation. To further identify protein speices appearing in the PaParD1 degradation process, Mass spectrometry was used and identified unexpectedly co-purifying DnaK chaperone which potentially modulate PaParD1 stability. In aggregate, Chapter IV provides optimal conditions for PaParD1 stability for in vitro storage, and propose a dynamic PaParD1 dimerization in varied ionic strength, offering a foundation for future research on TA system regulation. Overall, the study of this dissertation advanced the understanding of ParDE TA systems and their potential for antimicrobial development. ParE toxins were shown to strongly inhibit DNA gyrase, causing DNA damage and cell death, though lower level of expression increased mutation frequency but did not accumulate to become antibiotic resistance. Additionally, the approach of co-transformation with gyrase developed in this dissertation is able to produce decent quantity of active VcParE1, enabling future structural studies for the ParE-gyrase complex. Lastly, investigation of the intrinsic stability of the PaParD1 revealed core conditions affecting its degradation, including temperature, pH, concentration, and ionic strength. The co-purifying DnaK chaperone is also identified and may function in modulating PaParD1 stability. Taken together, the research in this dissertation extend the understanding of ParDE TA system, from the structural to functional properties, providing a foundation for future studies on their regulatory mechanisms as well as potential application in antimicrobial development
Designing for Resilience and Adaptive Capabilities: Public Libraries as Therapeutic and Inclusive Learning Environments for Refugees in New Country
Full text linkFinancial support was provided by the University of Oklahoma Libraries' Open Access Fund.This study explores the transformative role of public libraries in supporting refugee resilience through inclusive learning environments. Going beyond their traditional functions, public libraries facilitate refugees’ economic, cognitive, socio-cultural, and political integration. A systematic review of 36 peer-reviewed articles reveals how libraries serve as culturally responsive spaces with inclusive layouts and tailored resources, positioning them as vital hubs for health equity, socio-economic mobility, and psychosocial support. The study identifies persistent challenges – such as limited accessibility, insufficient funding, and lack of staff training – constraining libraries’ capacity to address refugee-specific needs. This research proposes a conceptual design model that positions libraries as therapeutic and inclusive environments. The model offers actionable guidance for policymakers, designers, and practitioners seeking to enhance refugee integration through targeted programs, services, and spatial interventions. Public libraries can play a pivotal role in promoting refugee well-being and fostering long-term community resilience by embedding inclusive design principles.Ye
THREE CONTEMPORARY WORKS FOR FLUTE BY COLOMBIAN COMPOSERS
Full text linkAbstract As a Colombian flutist, I, along with many colleagues, have observed that silver flute studies in Colombia are predominantly shaped by a foreign perspective, with a strong emphasis on European repertoire. This influence comes from the deep-rooted impact of European traditions on conservatory education, heavily informing the curriculum in terms of techniques, schools of thought, and repertoire. Ironically, as more Colombian musicians have had the opportunity to study abroad, a renewed interest in exploring and embracing our national identity has emerged. This shift is evident in the growing inclusion of Colombian music within the curriculum, such as chamber ensembles and select pieces written by local composers.With this trend, there has been a rise of interest among Colombian composers writing for wind instruments, including the flute, in a variety of formats and styles that draw on Colombian folk music. Despite this growing body of work, flute teaching in Colombia remains largely focused on international repertoire, leaving little room for the exploration of these valuable contributions from local composers. In an academic setting that increasingly values innovation and cultural integration, it is essential for Colombian flutists to turn their attention to these compositions. Doing so not only broadens the scope of flute literature but also strengthens the connection to our national musical heritage. Thus, this document seeks to highlight three contemporary flute compositions from the past fifteen years written by Colombian composers that incorporate elements of Colombian folk music: Rubén Darío Gómez Prada’s Ecuentros from Tríptico para flauta y banda (2012), Carolina Noguera’s Chirimías Metálicas (2009), and Juan Guillermo Villarreal Solar’s Curengue (2020). These three works, presented in different formats, offer variety for performance settings and provide flute teachers and performers with new, culturally relevant material. By doing so, this research aims to serve flute educators and performers by introducing underexplored repertoire. I will also provide an overview of compositions for flute by Colombian composers from the latter half of the twentieth century, focusing on works that incorporate elements of Colombian folk music. In addition, I will contextualize the selected composers' backgrounds and offer a brief analysis of each piece, focusing on Colombian musical elements and flute technicalities. Furthermore, I will argue for the inclusion of these works into the current flute curriculum in Colombian music institutions. To support further exploration of this repertoire, I will also include an appendix cataloging additional flute compositions by Colombian composers from the twenty-first century. This catalogue will go beyond solely Colombian musical elements, providing readers with a more extensive selection of flute repertoire reflecting a diverse creative output of Colombian composers and encouraging greater integration of these works into both educational and professional settings
The Effect of Virtual Processor Configurations on the Bounds Check Bypass Attack
Full text linkCompanies are employing virtual machines (VMs) as a cost-efficient solution for maintaining legacy operating systems (OSs) that are compatible with their software ecosystem. However, legacy OSs often lack mitigations for modern microarchitectural threats, such as speculative execution attacks (SEAs). This thesis focuses on the bounds check bypass attack, a type of SEA, and examines how processor configurations, the complexity of data structures used to architect the attack, and the attack execution time influence the attack's accuracy in virtualized environments. Experiments were conducted across four VM configurations with 8, 16, 24, and 32 virtual central processing units (vCPUs), using implementations in C and C++ with different data structures used in the attack's architecture. The results show a direct relationship between the number of vCPUs and attack accuracy. The VM with 32 vCPUs consistently achieved the highest attack accuracy, exceeding 90%, highlighting that increased processor availability reduces timing interference from context switching and shared cache contention. Additionally, the study found that longer execution times, often introduced by memory overhead or various types of system noise (e.g., context switching), decrease attack accuracy by increasing the likelihood of cache pollution before performing cache timing analysis, a key step in the attack. These results suggest that implementation simplicity, reduced memory overhead, and increased vCPU counts improve the attack's reliability. This research provides a framework for understanding how hardware resource allocation and system noise influence the bounds check bypass attack while highlighting opportunities for developing mitigations in modern and legacy systems
Back to the land of exclusion: a history of lesbian separatism, community, and trans marginalization in the United States, 1970s-2020s
Full text linkModern feminist and queer scholars often dismiss lesbian separatism as an antiquated,essentialist practice that serves little purpose for feminists today. Due to the exclusionary nature of the movement, it is easy to understand why. Many individuals and organizations associated with lesbian separatism display anti-queer and anti-trans identity tendencies that receive justified criticism from today’s inclusionary perspectives. However, lesbian separatist and feminist communities were prolific in the 1970s and 80s, and they provided crucial space for self- discovery and consciousness-raising. Not only were lesbians creating collectively owned urban businesses, such as coffee shops, bookstores, and record labels, but they also represented a contingent of the back-to-the-land movement, attempting to create rural utopias in places like northwest Arkansas. Those who have written about lesbian separatism often have ties to the movement itself, and they rarely dedicate much analysis to the issues of gender identity within these spaces. Additionally, the scholarly work analyzing this movement does not often extend its analysis beyond the 1980s. Although lesbian separatism was arguably at its height in the 1970s and early 1980s, many organizations and ideologies associated with the movement remained prevalent in the 1990s and 2000s. This period is when we begin to see an increase in discourse about transgender individuals’ roles within the movement. Much of the criticism aimed at lesbian separatists comes from internet users in the form of blogs or social media posts. While some article-length essays that analyze trans-exclusionary practices within lesbian organizations have been written, this thesis will bridge the gap between the scholarly work of authors like Dana R. Shugar, Bonnie J. Morris, and others who have documented the history of lesbian separatism with the more recent developments and critiques of the movement. My work argues that while separatism provided crucial space for lesbian women to better understand their identities and escape societal pressures, issues of race, class, and gender identity caused conflict in many separatist communities that ultimately led to their diminishment in size and scope
Adapting flow cytometry for studying immune tradeoffs in wild bats
No full textUnderstanding the differences in the immune systems of wildlife is critical for assessing the impacts of ecological stressors and zoonotic disease risk as many animals differ in the ways they mitigate infection while managing ecological challenges. However, our understanding of immune dynamics in wild species remains limited due to the challenges involved in measuring cellular immune function such as cold chain maintenance and a lack of species-specific reagents. This study adapts flow cytometry methods, which have been traditionally confined to laboratory settings, by optimizing protocols to enable immune profiling with small blood volumes and extended sample holding times to facilitate the study of cellular immunity in wildlife. We then applied these methods to a field research setting in rural Oklahoma to analyze trends in immune function in a migratory Mexican free-tailed bat (Tadarida brasiliensis) colony using a single-cell RNA sequencing–confirmed antibody panel (CD3 T-cells, CD79a B-cells, MCHII macrophages, and CD11b neutrophils) developed by a study in Egyptian fruit bats (Rousettus aegyptiacus). We first sought to compare flow cytometry with traditional white blood cell counts from blood smears, to demonstrate how flow cytometry could offer greater precision in immune cell identification. Then, through seasonal sampling, we identified trade-offs not only between innate and adaptive immune responses, but also within the innate and adaptive arms, revealing how energetic stressors like migration and reproduction influence specific immune cell strategies. Specifically, we found that, similarly to other animals, innate immunity dominates immediately following migration, while adaptive immunity becomes more prominent during non-energetically demanding life stages. More interestingly however, we found that within the innate arm of the immune system macrophage activity peaks just after migrating bats arrive in Oklahoma, as does T-cell abundance within the adaptive arm, while neutrophil activity peaks during the pup-rearing season, and B-cell activity peaks as pups become more self reliant. This suggests that within the innate and adaptive systems, cellular activity shows seasonal fluctuations that could better inform the strategy of reliance on innate immunity during energetically demanding life stages in bats, as well as strategies of adaptive cell use during less energetically stressful periods. Understanding these inter-system immune dynamics is crucial for understanding and predicting disease risk, particularly in light of the zoonotic potential of many bat-borne pathogens. These findings provide valuable insights into the immune ecology of bats and lay the groundwork for expanding the application of flow cytometry in wildlife immunology
Latino voice and politics: How Spanish accent affects first-generation Latinos' evaluations of political candidates.
No full textThis thesis examines how Spanish-accented English influences political candidate evaluations among first-generation Latino voters in the United States. Drawing from Ethnolinguistic Identity Theory, this experimental study exposed participants (N = 605) to audio recordings of fictional political candidates speaking with either a Spanish accent or Standard American English. Results show that first-generation Latino voters rated Spanish-accented candidates significantly more likable than Standard American English accented candidates, particularly among liberal voters and those who perceive Spanish as having high ethnolinguistic vitality. However, Spanish-accented candidates were rated lower on competence and goodwill, and no difference emerged in trustworthiness, revealing a divide between affective and evaluative judgements. While political ideology and vitality perceptions moderated the accent effect, self-perceived ethnic identity strength did not. These findings underscore the nuanced role of linguistic cues in political communication and highlight how accent functions as a cultural signal than can shape voter impressions in both expected and unexpected ways
THE DEVELOPMENT OF TWENTY-FIRST CENTURY ACCESSIBILITY TECHNOLOGY FOR TRUMPETERS WITH RIGHT-HAND INJURIES AND DISABILITIES: A CASE STUDY
No full textThis document chronicles the development of twenty-first century accessibility technology for trumpeters with disabilities and injuries through a case study; in particular, the study focuses on disabilities or injuries of the right hand. Though injuries and disabilities of the right hand are less frequently reported amongst trumpeters than other instrumental musicians, they can be exceedingly devastating to a trumpeter as the right hand is responsible for the operation of the piston valves when playing the modern trumpet. The case study is centered on the experiences of Greg Wing, a professional trumpeter and retired collegiate trumpet professor, and Peter Pickett, trumpeter, engineer, and entrepreneur. Together, the two pioneered the creation and development of the WingMaster, a unique and novel device combining motors, electronic components, and 3D-printed parts to operate the piston valves of the instrument with minimal effort or input from the musician. The practical uses for the device could transcend a wide variety of hand injuries or disabilities. Thus, an opportunity exists to preserve this knowledge for future engineers to improve upon, teachers to use with their students, and musicians to aid in the creation of their art
STUDYING A MORE EFFICIENT AND COST-EFFECTIVE GEOTHERMAL SYSTEM: ENHANCING HORIZONTAL GEOTHERMAL SYSTEM WITH WATER FLUX PROVIDED BY SEPTIC WASTEWATER
No full textIt is well documented and understood that consumption of energy is always increasing worldwide as the population grows. According to the U.S. Energy Information Administration [EIA] in 2023 the electricity sales to the four end user sectors, transportation / industrial / residential / commercial, residential consumed 38% of it. Residential also consumed 23% of natural gas, 3% of petroleum, and 15% of renewable energy of the four end user sectors. In 2020 US homes consumption of energy, on average, 52% was used for space heating and air conditioning (HVAC). Since most of the residential energy is consumed for HVAC, it has the potential to produce the largest energy savings by using a more efficient system. A heat pump (HP) is more efficient at conditioning a space than the more commonly used types, direct expansion, electric resistant, and natural gas. Unfortunately for heat pumps, they lose their efficiency advantage when operated outside of their ideal temperatures, between 40⁰ F and below 80⁰ F. That’s why geothermal water source heat pump systems are more efficient, their typical operation is around 67⁰ F. The problem with geothermal systems compared to traditional units is the greater increase in installation costs. Of the two most common systems, vertical ground and horizontal ground, vertical is the most efficient but has the highest installation cost and takes the most specialized equipment to install. So, the dilemma is, how can we make the horizontal ground geothermal system more efficient and affordable at the same time. By solving this problem, we can give more opportunities to save on the consumption of energy and cost of better technologies. A proposed solution is to combine horizontal geothermal and septic systems together. The footprint of the geothermal field would be installed under the septic lateral field in a layered configuration. This way the geothermal will benefit from the wastewater of the septic in increasing thermal conductivity, heat flux of the soil, making the geothermal more efficient. Also, the construction cost for the combined systems will be lower than if they were built separately. The paper includes a study of the proof of concept using modeling software Dymola and known soil characteristics of Shawnee, OK showing the increase of soil thermal conductivity, heat flux of the system. The difference of normal soil conditions vs saturated soil conditions will be researched for this paper. Efficiency, cost comparisons, and life cycle analysis will be shown against several commonly used systems. The common systems are air source HP, horizontal geothermal HP, and vertical geothermal HP. Through our study, we have found the coefficient of performance (COP) of each system to be different. The improved COP of the horizontal geothermal HP system resulted in higher energy savings. The life cycle cost analysis shows that it takes 4 - 9 years for return on investment. Final remarks and future research for this combined system will also be discussed