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Characterizing the Molecular and Cellular Changes of Senescent Cells Induced by Diverse Stressors in 2D and 3D Microenvironments
No full textAging is a risk factor for myriad diseases and is often associated with the accumulation of senescent cells. Cellular senescence, a process of irreversible cell cycle arrest, is associated with various changes in cellular morphology and function. While senescence will occur naturally in a time-dependent manner, it can be prematurely induced by various extrinsic and intrinsic factors. Most senescence studies model cell behavior in two-dimensional (2D) microenvironments; however, these models are not physiologically relevant. In this study, the effects of naturally occurring reactive oxygen species (ROS) hydrogen peroxide (H2O2) and commonly used chemotherapy drugs, doxorubicin and palbociclib, on cellular senescence are modeled and compared in 2D and 3D replicas of skin tissue using human foreskin fibroblasts (HFF). This study shows that senescence associated cellular changes are not only stressor-dependent, but also environment dependent
Inbreds & Cannibals & Savages, Oh My!: A Genre Analysis of Appalachian Atrocities
No full textThis thesis is an analysis of the representation of the Appalachian region in horror films. It examines the representations of the region in films such as The Hills Have Eyes, The Texas Chainsaw Massacre and Jug Face, and the representations of the inhabitants of Appalachia in films such as We Are What We Are. The analysis is conducted through a rhetorical analysis of the genre’s most core elements, such as the substance of the movie, the situational and stylistic, and the sensory aspects of the movies
Causal Attribution Tendencies of Early Childhood Practitioners and the Efficacy of Attribution Retraining
No full textEarly childhood practitioners frequently attempt to identify the cause of outcomes experienced by their learners. This is sometimes referred to as causal attribution. Causal attribution may be affected by prior success and failure of a learner, the amount of effort exerted by the learner, the ability level of the learner, and knowledge of any disability associated with the learner, all of which can be considered controllable or uncontrollable, stable or unstable, and internal or external (Weiner, 1986; Woodcock & Vialle, 2011). As practitioners attribute cause to outcomes, they start to develop attributional tendencies; these tendencies, along with the cues and public behaviors associated with these attributional tendencies, may have an impact on future outcomes of learners (Graham, 2020; Toevali & Kikas, 2016). It is important that practitioners develop adaptive attributional tendencies in which cause is attributed to controllable and unstable variables. One potential teaching approach for developing adaptive attributional tendencies is attribution retraining (Haynes et al, 2011; Wilson & Linville, 1982; 1985).
This dissertation is a foundational dissertation that will examine multiple aspects of attribution, addressing several gaps in the extant literature including attributional tendencies of early childhood practitioners, attribution retraining for early childhood practitioners, and the thoughts and beliefs on attribution of early childhood practitioners. The study included a quantitative randomized control pre-test/post-test study that examined the efficacy of attribution retraining on a sample of early childhood practitioners and a qualitative thematic analysis that used semi-structured interviews to explore the thoughts and beliefs of early childhood practitioners regarding attribution of success and failure. Results from the quantitative portion of the study were inconclusive but did suggest that attribution retraining could potentially be effective in the future. Results from the qualitative portion of the study showed early childhood practitioners emphasize social-emotional learning and support, and the importance of family and family collaboration, when attributing cause to success and failure. This study established a foundation for future attribution and attribution retraining research with early childhood practitioners and parents of young children.
Results are expanded on and discussed, then the implications for future research and practice are given. Future research should continue to explore attributional tendencies of early childhood practitioners and attribution retraining as a teaching tool for educating early childhood practitioners, as well as family members of young learners. Future research should include qualitative methodologies and mixed methodologies in order to capture more complete information about early childhood practitioners, and family members
Predicting High School Students\u27 Stem Career Choice Through Supervised Machine Learning Algorithms and Chi-Square Analysis
No full textThe dearth of STEM students in the United States is a growing concern for policymakers and educators alike. With the increasing reliance on technology in the global economy, a STEM trained workforce is essential for the United States to remain competitive. However, the number of students majoring in STEM disciplines and pursuing STEM careers is not keeping pace with the demand for these skilled workers. As a result, understanding the characteristics that contribute to students\u27 confidence in science and their desire to pursue professions in science remains a national priority. This research investigated the factors influencing the choice of STEM careers among high school graduates. To achieve this, the study analyzed data from 520 high school graduates, using machine learning models and chi-square analysis to predict their propensity for choosing STEM careers. This study evaluated the performance of four machine learning models—Logistic Regression, K-Nearest Neighbors (KNN), Decision Tree, and Neural Network—across various metrics, including accuracy, precision, recall, and F1 Score, to determine their effectiveness in classification tasks. The Logistic Regression model has a performance with an accuracy of 83.65%, precision of 88.83%, and recall of 84.12%. This indicates a slight preference for precision over recall. On the other hand, the K-Nearest Neighbors (KNN) model shows better accuracy (87.5%) and recall (93.6%), but with a slightly lower precision (86.7%). This suggests that the KNN model is effective in identifying relevant instances but with some compromises in precision. This study also explored the impact of socioeconomic status (SES), ethnicity, and access to Advanced Placement (AP) courses on the career choices of students in STEM fields. It found that gender did not significantly affect these decisions, but disparities in SES, ethnicity, and educational opportunities played a critical role. The study recommended that educational stakeholders work together to address these disparities by providing supportive measures and equitable resource allocation to promote a more inclusive and diverse STEM workforce
Algorithms for Certain Computational Mathematics Problems
No full textThis dissertation presents algorithms and explores diverse aspects of number theory, cryptographic systems, and partition theory. In Chapter Two, attention is focused on enhancing the security of the extended Rabin cryptosystem by incorporating multiple prime numbers into the encryption process, thereby increasing the complexity of decryption and fortifying resilience against quantum computing threats. Additionally, experimental results corroborate the efficacy of proposed algorithms, aligning closely with existing decryption methods while offering enhanced versatility.
Chapter Three presents a detailed exploration of sums of powers of arithmetic progressions, offering simplified formulas and algorithms for efficient computation, leveraging Stirling and Eulerian numbers. A comparison with existing methods underscores the computational efficiency of the proposed approaches.
In Chapter Four, properties and algorithms related to Ramanujan-type cubic equations are elucidated, showcasing a comprehensive computational methodology and its application through examples and cubic Shevelev sums.
Chapter Five extends the understanding of Leonardo sequences and second-order non-homogeneous recursive sequences, unveiling novel identities and combinatorial results. These findings are applied to investigate series representations, enriching the discourse on number theory.
Lastly, Chapter Six investigates the representation of positive odd integers as the sum of arithmetic progressions, building upon historical and contemporary works to provide theorems and efficient algorithms for computing such representations. This dissertation contributes to diverse areas within mathematics, cryptography, and computational methods, promising new avenues for exploration and application
Investigative Research on Design Parameters and Criticality Models for Microreactors
No full textWith increased energy demand and the desire to reduce reliance on fossil fuels, nuclear power will need to play a prominent role in achieving carbon-free energy independence. Large nuclear reactors are necessary to meet this objective. However, they are expensive and take a long time to build. For remote locations (e.g., military bases) and smaller communities, large nuclear reactors would not be feasible or cost effective. Small reactors (microreactors) can fill this necessary gap. These reactors would be factory-built, delivered quickly, and operated with high intrinsic levels of safety. With microreactors still in conceptual and testing states, there is a large need to study how these reactors produce consistent energy in a much smaller package.
The objective of this research is to develop design parameters and criticality models for a reactor core that can be used in a microreactor, which would self-regulate based on automatic control functions. This research investigates parameters and constraints for the reactor design, including a reactor core fueled with TRISO fuel, different cooling methods, and graphite moderators. Sensitivity studies are conducted on temperature, fuel depletion, and criticality control methods, and an enrichment of 20% U-235 will be used as the primary source of heat. A core achieving a critical state with temperatures ranging from room temperature to 1200K is considered. Feedback mechanisms are also investigated, including inherently safe fuel design and control rod manipulation
The Effect of Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex on Muscle Fatigue Resistance
No full textTranscranial direct current stimulation (tDCS) delivered to the dorsolateral prefrontal cortex (DLPFC) can increase endurance time in lower body cycling tasks. The purpose was to examine the effect of DLPFC-tDCS on the time to task failure (TTF) of a fatiguing contraction performed by hand muscles. The study used a double-blind, randomized, SHAM-controlled, crossover design. Participants completed two experimental sessions on separate days with a washout between sessions. All facets of the experiments were identical except the stimulation condition (DLPFC-tDCS or SHAM) that was given concurrent with the fatiguing contraction. The fatiguing contraction involved gripping a manipulandum with the index finger and thumb using a precision grip and matching an isometric target equal to 15% of the maximum voluntary contraction (MVC) for as long as possible until task failure. The main findings were that TTF and fatigue index did not differ between the DLPFC-tDCS and SHAM conditions. Furthermore, there was no significant differences during the fatiguing contractions in the rates of increase of electromyographic (EMG), force error, or standard deviation (SD) of force between the DLPFC-tDCS and SHAM conditions. Overall, the results indicate that application of DLPFC-tDCS does not reduce the rate of muscle fatigue development in the current task conditions
“Everyone’s Favorite Dead Girl”: Historical Crime Fiction and Postwar Policing in James Ellroy’s \u3cem\u3eThe Black Dahlia\u3c/em\u3e
No full textThis thesis argues for the importance of crime fiction as a major literary genre with global reach. Taken as a whole, crime fiction acts as a vehicle for exploring macro-level questions of social structures, political-economic processes and power relations. Within that genre, I claim that James Ellroy is a key figure who writes at the intersection of the historical novel and literary noir. As the first work in his L.A. Quartet (1987-1992), The Black Dahlia fictionalizes the investigation of the city’s most famous unsolved homicide—the gruesome murder and mutilation of Elizabeth Short. The novel, however, uses the investigation as a pretext for depicting the historical context of postwar American society, offering readers an opportunity to view past crimes as the prehistory of the present. In the novel, L.A. is portrayed as a site of terminal dysfunction and social inequality that provides the space for critical reflection, particularly on the systemic nature of policing and gendered violence. Ellroy’s historical crime novel, I argue, critiques postwar American society through its representation of the everyday nature of violence and marginalization in this chapter of the city’s development. These depictions of policing and gendered violence show readers that power structures are socially constructed and historically contingent rather than transhistorical, immutable truths
Boron-Doped Diamond as a Resilient Electrode Material in Molten Salts
No full textMolten salt chemistry has a range of applications within nuclear technology, including for the Molten Salt Reactors (MSRs) and pyroprocessing to recover valuable actinides for energy and national security needs. However, the high-temperature, corrosive nature of molten salts makes them particularly challenging to deploy on an industrial scale and study in benchtop measurements. Material accountability and corrosion monitoring of MSR fuels are essential components to the successful deployment of MSRs, and electroanalytical techniques like cyclic voltammetry (CV) and spectroelectrochemistry (SEC) can provide a wealth of information to describe salt systems in situ. To perform such measurements, it is imperative to have materials that can withstand the harsh environment of molten chloride and fluoride salts. It is hypothesized that boron-doped diamond (BDD), a well-studied, ‘designer’ electrode material, can serve as a resilient working electrode in molten salt systems given its previous applications to other harsh environments.
To better understand the use of BDD in molten salts, it was first studied in aqueous systems using CV to determine the impact of crystal structure, morphology, and carbon hybridization (e.g., sp2 or sp3) on the electrochemical response. Potassium ferricyanide, hexaammineruthenium(III) chloride, europium trichloride, and uranyl nitrate were all evaluated using CV on the two distinct sides of free-standing BDD to find that there is, in fact, a difference between large and small-grain structures of polycrystalline diamond. Values for formal potential (Eo), peak separation (DEp), diffusion coefficients (D), and heterogeneous electron transfer rate constants (k) were compared for each side of the BDD to quantify the quality of each response. Then, a novel optically transparent electrode (OTE) design from free-standing BDD was applied to SEC measurements of aqueous potassium ferricyanide to determine Eo and D. Following successful measurements, this OTE could be a resilient design applicable for actinide species in molten salt systems to help characterize MSR fuels.
Then, BDD was exposed to chloride (NaCl-KC) and fluoride (FLiNaK) molten salts under various conditions for extended periods to determine if it would survive under the most extreme environments (i.e., exposed to air, in inert atmosphere, using non-purified salts, using thermally dried salts, etc.). The material was then evaluated using scanning electron microscopy (SEM), profilometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) to determine changes to the surface structure and chemistry after exposure. There was virtually no change to the material after exposure except in the case of chloride salt that was not dried and was exposed to air where etching was seen in some regions of the crystal structures. However, when aqueous CV was performed on the samples to determine changes to the electrochemical performance, there was very little change, including for the corroded sample.
Finally, BDD was used to perform CV on Eu3+/2+ and U4+/3+ redox couples in chloride salts using various BDD electrode geometries. Successful measurements of Eu were performed using free-standing BDD and thin-film BDD in LiCl-KCl, and U was evaluated with thin-film BDD in LiCl-KCl and MgCl2-NaCl electrolytes. The impact of BDD crystal structure with the differing electrode geometries for Eu and changing electrolyte cation side for U were significant and produced an interesting set of results that opened doors for a wide range of future studies. Ultimately, BDD successfully performed measurements of f-block species relevant to MSR fuels and should be further explored under various conditions and optimized electrode designs
The Effects of Nicotine on Growth, Surface Marker Expression, and Osteogenic Capacity of Stem Cells from Human Exfoliated Deciduous Teeth (SHED) and Dental Pulp Stem Cells (DPSC)
No full textBackground: The gaining popularity of electronic nicotine delivery systems (ENDS) and inhaling aerosols (“vaping”) among young people have exposed them to unprecedented amounts of nicotine. Fourth generation ENDS manufacturers attract the adolescent demographic with a smooth vaping experience with enticing flavors such as “Piña Colada” or “Peppermint Blast.” Components of e-liquids in cartridges of ENDS combine protonated nicotine, also referred as nicotine salts, with flavors in a propylene glycol or vegetable glycerin solvent. Unregulated, high amounts of nicotine in ENDS products have been associated with increased levels of nicotine in the circulating blood of users with an average concentration of about 30ng/mL. Little is known on the effects of protonated nicotine on oral health, specifically on stem cells from human exfoliated deciduous teeth (SHED) and dental pulp stem cells (DPSC), and its implications on the repair and regeneration processes for the soft and hard tissues.
Objectives: The aim of this study is to evaluate the effects of nicotine on SHED and DPSC cell growth, surface marker expression, and osteogenic differentiation capacity.
Methods: Isolated SHED cells and DPSC cells were seeded in separate T-75 flasks with culture medium treated with 0ng/mL, 30ng/mL, and 300ng/mL of concentrated protonated nicotine. Population doublings were recorded over several passages once confluency was reached. The antigen surface marker expressions of SHED and DPSC sample populations were analyzed using flow cytometry. SHED and DPSC cell populations were cultured in osteogenic induction media, then after 7 days, collected for RNA Isolation and RT-qPCR gene expression of runt-related transcription factor 2 (RUNX2), secreted phosphoprotein 1 (SPP1), and bone gammacarboxyglutamate protein (BGLAP).
Results: Population doublings showed significant decrease in growth rate of both 30ng/mL and 300ng/mL nicotine treated SHED and DPSC cell populations compared to the untreated controls. Cell surface marker expression of nicotine treated SHEDs and DPSCs were consistent with the typical presentation of human mesenchymal stem cells (MSC). Analysis of cell populations from 0ng/mL, 30ng/mL and 300ng/mL nicotinic concentrations cultured in osteoblast inducing media using qPCR revealed no changes in RUNX2, SPP1 and BGLAP gene expression compared to undifferentiated controls.
Conclusion: Nicotine exhibits an adverse effect on the proliferation rate of SHEDs and DPSCs but shows no effect on their stem cell marker expression and osteogenic differentiation capacity