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Efficient Solvers and Anderson Acceleration for the Bingham Equations
Get PDFThis work studies two techniques utilized to solve the Bingham equations that model viscoplastic flow. An Uzawa-type iterative procedure is first analyzed and tested for poor convergence of velocity and stress. We apply Anderson acceleration (AA) to this method and show improved convergence rates for both velocity and stress. A solver utilizing regularization is introduced, and AA is also applied to display better convergence results. We propose a new method that combines these two solvers and applies Anderson acceleration
Motivations and Goals for Combatting COVID-19 Misinformation in Clinical Setting: A Case Study of Nursing Students.
Get PDFThe misinformation surrounding COVID-19 disrupted public health efforts to mitigate the virus. This study examined the motivations and goals of nursing students to combat COVID-19 misinformation within clinical settings. Medical professionals are best suited to combat health misinformation due to their expertise and lived experience, but they are not mandated but encouraged to address COVID-19 misinformation. Grounded in qualitative research methods and grounded theory, semi-structured interviews were conducted with nursing students who have had clinical practice after the start of the COVID-19 pandemic. Findings reveal that the key motivations and goals for addressing misinformation include the need to educate patients, safety, and building trust. Furthermore, the studies identify two types of Goals-Plans-Action (GPA) theory secondary goals: conversation management goal and personal resource goal that could influence motivation to engage in COVID-19 misinformation with patients. Responses indicate that participants motivation to engage in the conversation is negatively influenced due to time to talk about this issue with patients and avoiding conversations they feel will not end well. The findings highlight the need for health organizations and facilities to ensure continuous training and education of nurses on any rising health crisis to increase knowledge and confidence during conversations with patients, support and encourage nurses with the necessary resources that aid such conversations, and collaborate with policymakers to implement policies such as weapon-free zones in clinical environments
The Effects of Cigarette Smoke Extract on Osteoarthritis in a Primary Joint Tissue Explant Model
No full textOsteoarthritis (OA) is the most common degenerative joint disease in the world with an economic burden of nearly $140 billion annually. Factors identified to increase the risk of developing OA include age, obesity, sex, race, genetics, and previous joint injury. However, one risk factor that has been scarcely studied in OA etiology is cigarette smoking. While some studies have reported smoking to protect against OA, increasing evidence suggests that cigarette smoking results in more severe and painful OA, increases the rate of developing OA, and reduces the efficacy of pain medications and arthritis-targeting therapies. Despite this, the impact of cigarette smoking on OA disease progression remains controversial. This may be due to the lack of complexity utilized in current in vitro approaches, where culture models investigating the effects of cigarette smoking on OA do not adequately incorporate the cell and extracellular matrix (ECM) heterogeneity found in primary joint tissues.
To solve this problem, we employed a novel in vitro system using a combination of cartilage and synovium tissue explants with cigarette smoke extract (CSE) and OA-inducing inflammatory mediators, interleukin (IL)-1b and tumor necrosis factor (TNF)-a. With this model, we have for the first time, provided evidence on the negative effects that cigarette smoking has on OA-like characteristics in both cartilage and synovium at the cellular and tissue levels, as well as its effects on the communication and crosstalk between the two.
We found that under OA-like inflammation, CSE significantly increases the production of reactive oxygen species (ROS), alters the inflammatory secretory profile of the synovium, and magnifies the loss of ECM components in cartilage. Moreover, this model allowed for us to elucidate the involvement of cigarette smoke-induced advanced glycation end product (AGE) formation and the interaction with of AGEs with their receptor (RAGE). Our results suggest that CSE contains elevated levels of AGEs and their precursors, leading to accelerated AGE accumulation in cartilage with increased insoluble collagen and ROS production, both of which were able prevented by the addition of a potent AGE inhibitor, pyridoxamine (PM).
Altogether, we have shown that cigarette smoking can accelerate OA progression by altering synovial inflammation and increasing cartilage damage through the accumulation of AGEs and RAGE activation. By improving the breadth of knowledge regarding cigarette smoking and OA, this research may aid in the development of more effective pain relieving and/or disease modifying treatment options for OA patients who smoke
Hydrothermal Synthesis of Single-Crystal Magnetic Oxides
Get PDFMultifunctional materials are systems that have two or more properties of interest. Some of these features are polar axes, chirality, magnetic ions, triangular arrangements, and/or magnetically silent building blocks. Various combinations of these properties can result in chiral ferromagnetism, multiferroic magnetoelectric behavior, antiferromagnetism, and quantum spin liquids and spin ices. By tuning these structure-property relations, quantum computing, memory, and sensors may be created. Large single crystals allow for a better understanding of the magnetic behavior of these crystals since they can be oriented in a magnetic field. Inorganic single crystals have a wide range of applications but growing high-quality single crystals can be challenging. Some methods cannot solubilize refractory oxides, create crystals without defects, or produce large single crystals for good-quality magnetic data collection. However, the hydrothermal method can minimize or eliminate these issues due to the lower thermal energy within the system, therefore, hydrothermal synthesis was utilized to grow a range of magnetic materials. This has been demonstrated through analysis using various techniques such as powder X-ray diffraction, single-crystal X-ray diffraction, electron dispersive spectroscopy, infrared spectroscopy, and physical property measurements.
The first goal of this dissertation was to exploit the hydrothermal method to learn how to optimize various promising frustrated triangular arrangement systems such as half-delta, delta, and Kagome materials. There were some preliminary magnetic studies with Na2Co3(VO4)2(OD)2, K2Co3(VO4)2CO3, K2Co3(MoO4)3(OH)2, Co2(MoO4)(OH)2, and CsCo2(MoO4)2(OH) showing complex, and sometimes, ambiguous magnetic ordering. Therefore, fine-tuning hydrothermal conditions to grow larger crystals for oriented magnetic measurements and for neutron scattering studies was necessary. The MoO42- and VO43- ions served as magnetically silent building blocks while the magnetic TM ions were assembled in a triangular arrangement in relation to each other. The structures of various oxyanion building blocks such as phosphates, vanadates, arsenates, molybdates, and bismuthates are well-known and vast in literature, but there is limited descriptive and structural chemistry of antimonates.
Antimony, another magnetically silent element, led to a series of large single crystals of a known system that lacked anisotropic magnetization data. The second goal studied the magnetic interactions within the TMSb2O4 (TM = Mn, Co, Ni) system after the large growth of well-ordered single crystals. The relatively simple crystal structure displayed various magnetic pathways between TM2+ ions, including intrachain direct exchange, superexchange, and interchain superexchange. Within the TM–Sb–O system, two other structures also arose: TMSb2O6 and TM2Sb2O7. Exploring the Mn–Sb–O phase space resulted in new compounds and structure types: BiMnFe2O6-type MnSbO3, Mn5Sb2O10, Mn11Sb5O24, spinel-type Mn(Mn1.5Sb0.5)O4, and Wadsleyite-type (Mn1.5Sb0.5)MnO4.
The pyrochlore structure type was of particular interest as this type displays unusual magnetic and quantum material behavior when rare earth elements are used, therefore, rare earth ruthenates were pursued. The third goal focused on growing large single crystals of another magnetically interesting class of compounds, namely the pyrochlores with emphasis on heavy transition metal ion building blocks. For second-row elements, the orbital overlap and spin-orbit coupling are comparable in energy, so they have the potential to have fascinating magnetic and spectroscopic properties. Furthermore, ruthenium can exist in multiple oxidation states, so its reaction chemistry can be very extensive when combined with the lanthanides. Hydrothermal synthesis is particularly required for single crystal growth of lanthanide ruthenates since many of the starting materials are refractory and have only been grown by traditional solid-state synthesis as powders with site disorder and defects. In addition to pyrochlore (Ln2Ru2O7 where Ln= lanthanides) formation, this work also led to the growth of ruthenium lanthanide perovskites and other interesting structure types (LnRuO3, Ln2RuO5(OH), and Ln5Ru2O12) with minimal site disorder and defects. Complex magnetic interactions were demonstrated with magnetization data for Ln2Ru2O7 (Ln = Pr, Nd) and LnRuO3 (Ln = La, Pr, Nd).
This work has contributed significantly to advancing the understanding of these fascinating systems, but there is much more exploration and studies needed to gain insight into their structure-property relationships to reveal attractive multifunctional properties
Statistical Designs for Learning User Preference and Experience
Get PDFFor any organization, designing a new product or planning the features of a new service is a complex decision-making process which depends on understanding its users\u27 preferences and the experiences they have with prototypes of the new product or service. Design of experiments (DOE) offers a framework to aid in the modeling and collection of data to learn user preferences and experiences to facilitate this decision-making process. Questions such as ``which of our newly proposed products is preferred most by our customers and ``which version of our new service results in the highest monthly revenue can be readily addressed by carefully designing and analyzing an appropriate experiment. This dissertation focuses on the design of experiments for learning user preference and experience, and consists of four projects related to experimental design where product or service users are involved: (1) Bayesian sequential preference elicitation; (2) Batch sequential designs in Bayesian preference elicitation; (3) Approximate dynamic programming methods in Bayesian preference elicitation and (4) Collaborative design of controlled experiments in the presence of subject covariates. In (1), we introduce the framework of Bayesian sequential preference elicitation, which is the foundation for the developments in (2) and (3). In (2), we extend (1) to the case where multiple queries are selected at once. In (3), we investigate non-greedy approximate dynamic programming methods in the context of preference elicitation. Lastly, in (4) we propose methodology and algorithms for the experimental design of a certain A/B testing problem
Learning Through Online Participation: From Breakout Rooms to Discord
No full textFor software development teams, teamwork is an essential part of their day-to-day lives. However, due to the aftermath of the COVID-19 pandemic, more companies have allowed employees to have more hybrid and remote work options than before. As more companies are adopting hybrid and remote workstyles, we need to ensure that we are preparing the next batch of young software developers to conduct teamwork in remote and hybrid settings. In this dissertation, I address the tools students use for teamwork and how to improve their teamwork inside and outside of the classroom. I present my research on improving student experiences in online and hybrid courses that utilize breakout rooms. I discuss my recommendations for both instructors and students to improve the breakout room experience for everyone. Then, I present my work investigating the challenges students face and the communication and collaboration tools they use during their hybrid and remote semester-long development projects. Through this research, I learned that Discord is the tool of choice for communication during team projects. Additionally, I discuss the challenges we found students face during their group projects and how those compare to the challenges professional developers face during their hybrid and remote work experiences. Next, I present my findings on why students are using Discord as their main method of communication. I discuss the many communities students participate in and how students are using Discord to further their education. Finally, I present and discuss my findings on how Discord can be useful within the classroom to improve team communication during students\u27 capstone development projects
Serious Leisure, Passion, and Burnout
Get PDFThis study examined the relationships between aspects of serious leisure, dualistic passion, and burnout in the MBI-GS and BM. Serious leisure has been shown to improve leisure and general life outcomes, but little research considers how harmonious or obsessive leisure engagement affects these outcomes or has extended serious leisure benefits to the workplace. Overall, the study hypothesized that leisure seriousness, harmonious passion, and satisfaction with time spent in serious leisure will negatively correlate with burnout, and obsessive passion will degrade the benefits derived from serious leisure. 240 participants completed Gould\u27s Serious Leisure Inventory, the Passion Scale, the Maslach Burnout Inventory General Survey, and the Burnout Measure. Leisure seriousness negatively correlated with exhaustion in the MBI-GS (r = -.16) and burnout in the BM (r = -.20), and positively correlated with professional efficacy in the MBI-GS (r = .16). When dualistic passion is introduced, however, significant noise is introduced into these relationships. Higher levels of harmonious passion strengthen an otherwise non-significant negative correlation between leisure seriousness and cynicism, and unexpectedly, higher levels of obsessive passion strengthen the negative correlation between leisure seriousness and BM burnout. No other significant moderation effects were found
The Effect of Mobile Augmented Reality on the Self-Efficacy of Adults Learning English in the U.S.
Get PDFFor foreign-born adults living in the U.S., learning, speaking, and understanding English is essential to be able to work, access needed resources, facilitate healthcare, communicate with teachers at a child’s school, and build relationships and communicate with others within their communities. Yet, many of these individuals have limited English proficiency and are unable to speak and understand the language well. There are some opportunities to learn English in the U.S. as a foreign-born adult, but these avenues of learning are limited in the type of personalized, contextualized, and real-world language learning opportunities that are provided. There is a need to find opportunities for these adults to learn and practice English within their real-life, everyday situations outside of the classroom. Research indicates that mobile augmented reality (MAR) can enhance adult language learning through personalized, self-directed, situated, and authentic learning experiences. Past research has explored the use of MAR for language learning, but there is limited research on how foreign-born adults in the U.S. appropriate MAR to learn and practice English outside of the classroom and to what extent does this affect their self-efficacy. Exploring how foreign-born adults appropriate MAR to learn and practice English in the U.S. will help develop a richer understanding of what these adults value, the capabilities and implications of MAR for language learning, and to what situations are MAR tools applied outside of the classroom. For this research, I used a multi-case study approach to explore how seven adults from five different countries, who had been in the U.S. 7 years or less, appropriated Google Lens MAR for language tasks outside of the classroom and how this experience influenced their self-efficacy. The adults used Google Lens in four planned activities within different contexts, to include a restaurant and a museum, to learn and practice English. Thematic analysis was used to analyze the qualitative data resulting from each participant’s discourse during the activities, their journal writings, their drawings, and their post-interviews to identify and describe the patterns and themes that occurred. A pre-post self-efficacy survey was also used to provide a more comprehensive understanding of the data as it related to the study. Findings revealed that the adult learners who appropriated the Google Lens MAR in this study developed new approaches and ways of thinking about language learning outside of the classroom; engaged in active interaction with people and objects in their environment to meet personalized goals outside the classroom; connected their first language, interests, and culture with language meaning construction; and exhibited increased levels of English self-efficacy, MAR self-efficacy with intention to use in the future for language learning, and intrinsic motivation to learn English. Discussion of the findings include implications for teaching and learning for adults who are learning a new language in a new community in which they now live
Charge and Spin Transport in Nanowires with Spin-Orbit Coupling
Get PDFNanowires exhibiting Fermi-level pinning have strong radial electron confinement and thus can be modeled as a two-dimensional electron gas wrapped around the core. In III-V semiconductor structures, two forms of spin-orbit coupling are generated by breaking inversion symmetries in the crystal (Dresselhaus) and the overall structure of the nanowires (Rashba). The first goal of this thesis is to understand the single-particle energy spectrum in nanowires with variable cross sections and the quantum oscillations that can be driven in them by the application of a magnetic field parallel to the axis of the wire. To this end, the eigenfunctions and eigenvalues of the Hamiltonian are evaluated numerically in a finite difference method that allows the implementation of all the interactions acting in the system for the particular symmetry of a given wire. Then, using the single-particle energies and eigenfunctions, we investigate the NW transport properties under the action of electric fields or thermal gradients. In the linear regime, we discuss both a ballistic model and a diffusive approximation based on the Boltzmann transport equation to evaluate charge conductivity and the Seebeck coefficients in a nanowire with a circular cross-section. In the non-linear regime, quadratic in the electric field, spin-currents azimuthally polarized are created on account of the spin-orbit interaction. The dependence of these currents on the coupling constants of the spin-orbit interactions is studied
