Digital Commons Network^™

Modeling Solar Wind In The Inner Heliosphere With Quantified Uncertainties, Dinesha Vasanta Hegde

Dissertations

The solar wind (SW) is a vital component of space weather (SWx), providing a background for solar transients such as coronal mass ejections, stream interaction regions, and energetic particles propagating toward Earth. Accurate prediction of SWx events requires a precise description and thorough understanding of physical processes occurring in the ambient SW plasma. This dissertation investigates the effect of uncertainty associated with solar photospheric boundary conditions (BCs) on magnetohydrodynamic (MHD) simulations of the SW in the inner heliosphere. For this purpose, I perform ensemble simulations of the three-dimensional SW flow using an empirically-driven MHD heliosphere model implemented in the Multi-Scale …

Shattering The Glass Ceiling, Navigating The Glass Cliffs: A Case Study Of Andrea Luxton As The First Woman President Of Andrews University (2016-2023), Maureen Sakshi Pakalahati

Dissertations

Problems

Research shows glass ceilings are thicker in faith-based institutions heavily governed by traditional beliefs and dominated by men. Research also shows singlism is on the rise in churches. There is limited research on the lived experiences of single, never married woman who reached the presidency (shattering the glass ceiling) in a faith-based institution. Leadership pundits predict a “great resignation”, which is an era of high presidential turnover, due to mounting challenges in the higher education presidency. Great resignation is a gender-neutral phenomenon, but women presidents are subject to stern criticism and penalties, leading to more disproportionate resignations. Furthermore, the …

Church Ministers' Perceptions On Burnout And How It Shapes Their Leadership Practices., Jason Young

Dissertations

This qualitative phenomenological study explored how large church ministry leaders experienced burnout and how that burnout shaped their leadership practices. The study was motivated by a research gap concerning the lived experiences of ministers in large churches. Framed by the job demands-resources theory and the conservation of resources theory, the study sought to understand how the demands of ministry leadership and the availability of personal and organizational resources influenced the experience of burnout. The research employed a qualitative phenomenological design, utilizing semi-structured interviews. A purposive and snowball sampling approach was used to recruit 13 large US church ministry leaders. The …

The Inequitable Access: Black And Latinx Students In Ap Courses, Jean C. Woolcock

Dissertations

This study posits that in American high schools, the preparation of Black and Latinx students, starting from the freshman year, can be effective in helping to increase their participation in Advanced Placement (AP) courses. Structural inequities, in how schools are resourced, affect the ways in which Black and Latinx students are denied equal opportunities. On the contrary, members of their peers do obtain this kind of preparation. As a framework, Critical Race Theory (CRT) contends that race, the law, and power are deeply ingrained in maintaining established bastions of wealth and dominance. Gaps in opportunity and achievement spill over into …

Educator Perspectives Of High School Long-Term English Learners, Martin Gutierrez Jr.

Dissertations

This qualitative study was twofold. The study began by exploring how educators perceive students who are Long Term English Learners (LTELs) and then moved to an autoethnographic examination of the researcher’s own secondary school experiences as an LTEL. The research reviewed teacher and administrator perceptions by focusing on three high school teachers who taught Long Term English Learners during the study period to understand the reclassification process. The researcher interviewed a district-level administrator to understand institutional policies and procedures that determine LTEL student identification and reclassification processes. The researcher presented their autoethnographic narrative to explore how holistic measures support multilingual …

Bilingual Latinx Adolescents Experiences In A Predominantly White Institution: A Mixed Method Study, Danieli Marie Mercado Ramos

Dissertations

Extent scholarship has provided insight into how Latinx adolescents actively experience exclusion. These adolescents are often the targets of microaggressions tied to their language (Gonzalez et al., 2018), ethnicity, race, and intersecting identities--such as being bilingual Latinx students--which serve as reminders that they do not belong. However, little is known about Spanish-English bilingual Latinx adolescents and how their heritage language plays a role in predominantly white spaces and institutions. This convergent parallel mixed methods study explored how Spanish-English bilingual Latinx students in the Midwest described their experiences in a predominantly white institution (PWI). A total of 42 Spanish-English bilingual Latinx …

Evolution Of Bacteria: The Subsequent Relationships Between Different Species And Their Hosts, Helen Appleberry

Dissertations

To explore the relationship between two recently identified bacterial species (S. anginosus and S. urinae), three aims were designed. First, niche ranges were identified via two metagenome databases. Different niche ranges were identified between the two groups. S. urinae was more specific to the urogenital tract. S. anginosus appeared to be present across human anatomical niches. Secondly, specific genes to the S. urinae group were identified. This gives insight into the genomic and phenotypic differences previously identified. Thirdly, a temporal study was created to view S. urinae in female urine over 8 weeks. This showed stability in the urinary microbiome …

Analyzing The Population Structure Of The Rhizobia Associated With Astragalus Lentiginosus, Joshua Adam Melnick

Dissertations

Legumes are an incredibly diverse and agriculturally important family of plants. They have a special relationship with symbiotic bacteria known as rhizobia which fix nitrogen into ammonia within nodules on their roots. Astragalus is the largest plant genus on Earth, and the species Astragalus lentiginosus is extraordinarily diverse, consisting of approximately 40 varieties. However, the rhizobia of A. lentiginosus have never been studied. In this study, root nodules were extracted from 17 varieties of A. lentiginosus to obtain rhizobial strains and metagenomes. A. lentiginosus primarily associates with rhizobia from the genera Mesorhizobium and Allomesorhizobium. There was little evidence of horizontal …

Exploring The Ecological Relevance Of Biotic And Abiotic Stressors In Structuring Legume Microbial Communities, Cian Dotson

Dissertations

Heavy metal hyperaccumulation is prevalent throughout plant evolution, particularly in the legume family (Fabaceae), and acts as a presumed chemical defense against herbivory. However, heavy metal hyperaccumulation can have non-target impacts on other biological interactors including plant-microbe interactions. This information is important given the interest in utilizing hyperaccumulating plants for phytoremediation of anthropogenically contaminated soils. Here we employ a greenhouse experiment manipulating selenium level along with 16S rRNA gene amplicon sequencing methods to explore the effect of selenium on the prokaryotic microbiome of the selenium hyperaccumulator Astragalus crotalariae and non-accumulator Astragalus lentiginosus var. borreganus. Regardless of hyperaccumulator status, both plant …

Deciphering The Source Of Escherichia Coli In Urinary Tract Infections: A Comparative Metagenomic Analysis Of The Female Urogenital Microbiome, Alexis Annabel Avalos

Dissertations

In 2019, there was a 140.19% increase in deaths due to urinary tract infections (UTIs) compared to 1990, worldwide. One of the common uropathogens known to associate with UTIs in females is Escherichia coli. The prevailing belief is that E. coli in the bladder originates in the rectum, passing its way from the perineal, to the vagina, and finally into the bladder. Known as the Fecal-Perineal-Urethral (FPU) hypothesis, this “origin story” has been supported by several studies that have relied on genotyping or serotyping isolates collected from the bladder and rectum. Most notably, culturing isolates from samples has been central …

Selecting For Lysis In A Temperate Phage Population, Haley Atkins

Dissertations

The ongoing evolutionary arms race between bacteria and bacteriophages (phages) is a prime example of Red Queen hypothesis, where continuous adaptation drives survival. This study focuses on Escherichia coli-infecting temperate phages, which dominate natural environments and contribute to bacterial resistance mechanisms. Despite their prevalence, temperate phages are less suited for phage therapy due to their lysogenic life cycle, where they integrate into bacterial genomes instead of lysing the host. In contrast, obligately lytic phages, which directly lyse bacterial cells, are ideal for therapeutic use but occur less frequently in nature. This research aims to select for lytic behavior in temperate …

Reconceptualizing Christian Nationalism, Robert Stevenson

Dissertations

This thesis sets out to critically engage with existing research on Christian nationalism. It argues that current research suffers from a methodological focus that is too broad, and theoretical grounding that is too imprecise, both of which prevent researchers from grasping the full scope and intent of Christian nationalism, as imagined by Christian nationalists themselves. Drawing on data collected from X accounts (formerly Twitter) of Christian nationalist users, Christian nationalist podcasts, and Christian nationalist books, it employs qualitative content analysis, mapped to Bourdieusian field theory to provide a structured approach for the understanding complex data involving multiple spheres of power, …

Refining Cross-Population Polygenic Risk Scores Across Diverse Populations, Mansi Patel

Dissertations

Large biobanks containing whole genome sequences connected to the deidentified electronic health records of hundreds of thousands of individuals are increasingly available to researchers. This has facilitated the development of polygenic risk scores (PRS), which use machine learning to predict risk of disease and other phenotypes from millions of genetic variants. Due to Eurocentricity of available genetic data, PRS have primarily been trained in populations of European descent. Differences in allele frequencies, effect sizes, and linkage disequilibrium patterns between populations can limit the transferability of PRS across different populations. Given that most data are from European genetic ancestry populations, we …

The Impact Of Lactobacillus Supplementation On Gut Microbiome Composition And Phage Induction In Mice, Kimia Boreiri

Dissertations

The mammalian gastrointestinal (GI) tract harbors a dense and dynamic community of microbes known as the gut microbiota, which plays vital roles in digestion, immunity, and overall health. Among these, probiotic bacteria such as Lactobacillus strains have garnered attention for their ability to influence microbial community structure and host physiology. This study investigated the effects of five Lactobacillus strains, Lactobacillus casei R1A482, Lactobacillus casei O3, Lactobacillus rhamnosus GG, Lactobacillus gasseri ATCC 33323, and Lactobacillus paragasseri UMB1065, on the gut microbiome of Swiss Webster mice over a six-week feeding period. To reduce stress, mice were fed Lactobacillus strains using gelatin pellets …

Decoding The Origins Of Infection: A Machine Learning Framework, Nirupama G. Shanbhag

Dissertations

Many infections can be attributed to a specific microorganism. For example, while there can be many causes of urinary tract infections (UTIs), such as the bacterial species Klebsiella pneumoniae or Enterococcus sp., the most widespread cause for UTIs is uropathogenic Escherichia coli. Generally, diseases or infections that are the result of a single pathogenic organism are more easily understood. Other diseases, such as irritable bowel disease (IBD), cannot be attributed to one member in the community; rather, it is a result of dysbiosis of the microbial community (microbiota) of the gastrointestinal tract, a combination of an overgrowth of problematic members …

What Makes A Teacher A Teacher: A Philosophical Approach Aligned With Plato, Sojung Kim Hinterkopf

Dissertations

This thesis investigates how contemporary U.S. educational accountability policies—namely No Child Left Behind (NCLB) and Race to the Top (RttT)—redefine the role of teachers through a compliance-oriented lens. Moving beyond logistical and emotional impacts, this study applies Plato’s Allegory of the Cave as a philosophical framework to uncover the intellectual and ethical constraints imposed on educators. Through qualitative document analysis of federal policy texts, three metaphorical themes—shackles, shadows, and enlightenment—emerged to represent how teachers are bound by data-driven mandates, compelled to perform surface-level success, and yet still retain the potential to guide students toward deeper intellectual engagement. The findings reveal …

Role Of Coronavirus Envelope Protein On Infectivity, Garrett E. Zaagman

Dissertations

Coronaviruses infect a wide range of hosts and have caused recent human pandemics. While much has been learned, gaps remain in understanding viral assembly and egress, particularly the role of the envelope (E) protein in specific infectivity. To study this, recombinant MHV viruses were created with E gene deletions and HiBiT-tagged spike (S) proteins to monitor virion release. In mouse cells, MHV∆E S-HiBiT secreted less spike and fewer infectious particles, indicating reduced specific infectivity. Comparisons between human HeLa-CEACAM and mouse DBT cells showed species-specific support for virus production. TMED10, a host membrane protein, was tested as a potential E-interacting partner …

Anti-Inflamatory Mechansim Of Bacillus Subtilis Derirved Exopolysaccharide, Adrian Taylor Ibarra

Dissertations

Exopolysaccharides (EPS) secreted by the commensal bacterium Bacillus subtilis exhibit potent anti-inflammatory properties, yet the underlying molecular mechanisms remain incompletely understood. We hypothesized that EPS reprograms antigen-presenting cells toward a tolerogenic state by modulating TLR4–MyD88 signaling. To test this, we began using a chemically defined, high-yield EPS production and purification protocol that largely eliminates protein and DNA contaminants, thus improving functional reproducibility across experiments using this new method. In vitro, EPS engaged TLR4 on murine dendritic cells (DC2.4) without inducing classical NF-κB activation, seen by LPS stimulation. Rather, EPS treatment upregulated inhibitory molecules, PD-L1 and PD-L2 while leaving activation markers, …

Investigating The Mechanism Of Resistance To Ido1 Enzyme Inhibitor Treatment In Human Glioblastoma, Kyla Shivakumar Hatton

Dissertations

Glioblastoma (GBM) is the most common and most aggressive form of adult cancer in the central nervous system, with GBM accounting for the majority of all malignant brain tumors. GBM is currently considered to be an incurable form of cancer, with over 14,000 patients diagnosed in the United States last year. Given the success of immunotherapy for treating other types of cancer, our group has investigated the possibility of therapeutically neutralizing immunosuppressive indoleamine 2,3 dioxygenase 1 (IDO1) in patients with GBM. Canonically, IDO1 is an immunosuppressive cytoplasmic enzyme that catalyzes the first step in metabolizing L-tryptophan into L-kynurenine (ie. ↓L-Trp→↑L-Kyn). …

Developing Chemically Defined Serum-Free Medium For Leukemic Blast And Stem Cell Expansion, Carmen Eva Finley

Dissertations

The relapse and chemotherapy resistance are the major challenges of acute myeloid leukemia (AML) treatment, driven by a rare population of leukemia stem cells (LSCs). LSCs are unique types of cells which evade standard chemotherapies and can regenerate AML post-treatment. Targeting LSC therapy remains limited, in part due to the lack of reliable in vitro AML culture systems to grow LSCs for drug discovery. This study aimed to engineer a chemically defined, serum-free 2D in vitro culture condition that supports either the expansion of leukemic blasts (LBs) or primary human LSCs by optimizing current protocols for hematopoietic stem cells (HSCs) …

Investigating Whether Txnrd2 Is A Therapeutic Target Against Triple Negative Breast Cancer Using African American-Derived Models, Keacha Chang

Dissertations

Despite similar breast cancer incidence rates, African American (AA) women experience a 40% higher mortality rate compared to Caucasian American (CA) women. This disparity is multifactorial and particularly pronounced in the Chicago area. AA women are twice as likely to be diagnosed with triple-negative breast cancer (TNBC), often at a younger age and with more aggressive disease. TNBC is a heterogeneous subtype lacking targeted therapies and is associated with the poorest prognosis among breast cancer types. Therefore, there is an urgent need for novel therapeutic strategies for TNBC, especially those tailored to AA patients. The thioredoxin pathway is essential for …

Examining Secretory Pathways In Inflammasome Activated Innate Immune Cells, Alejandra Castellanos Urquidez

Dissertations

Innate immune cells serve as the first line of defense by detecting pathogens through pathogen- and damage-associated molecular patterns (PAMPs and DAMPs). Recognition of PAMPs triggers the synthesis and secretion of pro-inflammatory proteins, with the inflammasome playing a key role in the secretion of interleukin-1β (IL-1β), a crucial part of the innate immune response. Upon inflammasome activation, the release of signal-peptide lacking cytoplasmic proteins such as IL-1β occurs through non-classical pathways known as unconventional protein secretion (UCPS), which vary depending on the cell type and stimulus which helps tailor the extent of pro-inflammatory protein secretion. Broadly, UCPS cargoes are released …

Capturing Diverse Adolescents’ Social Contexts: The Development Of An Ethnic-Racial Microaffirmations Scale For Peer Interactions, Maria Radulescu

Dissertations

The development of a strong and positive sense of ethnic-racial identity (ERI) has been identified as an asset for ethnically and racially marginalized adolescents. Peer interactions during the adolescent years can support ERI development. In particular, a subtle micro-level form of peer support—microaffirmations—may be protective for ERI processes. However, the field of microaffirmations is very small, and there is no scale that captures adolescents’ experiences of ethnic-racial microaffirmations from their peers. The current study developed an ethnic-racial peer microaffirmations scale based on extant literature and feedback from 4 focus groups with 22 sophomore high school students. Findings indicated that 5 …

“What’S Happening In The Gulf Of Maine?”: Middle School Students’ Engagement In Climate Science Through Data Visual Representation And Reflections, Grace Ocular

Dissertations

This study examined how middle school students engaged with science concepts while working with data visualizations during a field trip learning experience. Fifty-one teams of 2–4 students from 35 schools participating in the LabVenture program were video- and audio-recorded. Students completed two activities: one using a frequency table of marine species illustrating threats to Maine’s lobster population, and another using maps depicting changes in Gulf of Maine sea surface temperature. After each activity, students annotated the visualization, discussed their claims, and recorded short reflections. Transcripts were coded for science-related talk, and annotations and gestures were also analyzed. Findings indicate that …

The Bacterial Sensing Nuclear-Oligomerization Domain 2 Receptor In The Brain: Location And Potential Function, Julia Smyth

Dissertations

Nucleotide-binding oligomerization domain-2 (NOD2) is a cytosolic receptor, activated by bacterial peptides that initiates innate immune responses through nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and Caspase-1 pathways. While the role of NOD2 in inflammation outside the central nervous system (CNS) is well-established, especially in the gastrointestinal system, its expression and function in the brain remain poorly defined. Previous genetic studies suggest a link between NOD2 and neurological and psychiatric conditions, including stroke, Parkinson’s disease, and schizophrenia. However, information regarding NOD2 expression, localization, and function in the CNS is limited. In this work, we investigated NOD2 expression, localization, and regulation …

Evaluation Of Bacteriophage Infection Of Enterococcus Faecalis In A Monolayer, Alexandria Osborn

Dissertations

Enterococcus faecalis is one of the first colonizers of the human gastrointestinal tract, and it plays a role in the intestinal immune development at the very early stages of life. However, it is also an opportunistic pathogen, capable of translocating across the mucosal barrier to cause systemic infections. E. faecalis is also linked to infections including endocarditis, recurrent urinary tract infections (rUTIs), bacteremia, wound infections, meningitis, root canal infections, intra-abdominal and pelvic infections, and septicemia. Persistent enterococcal opportunistic infections have been associated with the production of virulence factors and sharing of antibiotic resistance genes, thus making E. faecalis difficult to …

Keep It In Your Pants: How Sexual Regulation Becomes Identity Regulation, Madelyn Shoemaker

Dissertations

White Evangelicalism has been studied quantitatively for many years; however, this article examines in-depth interviews with ex-congregants of a specific church located in Chicago. Building from Orit Avasai’s framework of “doing religion,” I argue that due to a high saturation of isolation, sexual regulation and patriarchal power, this specific church’s script of religious performance claims master status in individual identity building, leading to adverse effects in adulthood. Much of the rhetoric utilized to justify the intense regulation of identity mirrors that of the New Right movement of the 1980’s, as well as modern political discourse. This study will assist in …

"I'M Not Having Fun Anymore": A Qualitative Analysis Of Gender And Harassment In Bars And Clubs, Phoebe Marie Jackson

Dissertations

Sexual harassment, while often spoken about in hushed tones or ignored altogether, happens frequently and often loudly. 66 percent of women who have experienced sexual harassment report that the harassment took place in a public space, such as work, school, or on the street (Kearl, 2018). Harassment is not discreet, but rather normalized, and those who experience it are expected to brush it off or take it in their stride. However, such harassment and subsequent dehumanization has a deteriorating effect on the mental well-being of those affected (Graham et. al., 2016). This study aims to hone in on the effect …

Effects Of Nitrogen, Phosphorus And The Fungicide Azoxystrobin Additions On Larval And Post-Metamorphic Fitness Of American Toads (Anaxyrus Americanus), Michael Vosburgh

Dissertations

Since European settlement, vast areas of U.S. land have been modified by humans. In the Midwest, an estimated 99% of native grasslands have been replaced by agriculture and urban development. Such alternations have replaced native habitat, redefined hydrology and introduced a wide array of chemicals into aquatic ecosystems. Modern agricultural practices utilize fertilizers and pesticides to maximize crop production. These chemicals frequently runoff into surrounding waters, potentially effecting aquatic organisms. One group of organism thought to be susceptible to agricultural contaminants are amphibians. Amphibians are vulnerable to pollution due, in part, to their permeable skin and biphasic life history. Global …

Systematic Review Examining How Black Youth In The United States Cope With Stressful And Traumatic Experiences, Marcus Aaron Flax

Dissertations

Coping is an important behavioral skillset that youth use to emotionally regulate after experiencing stress or trauma. Research has repeatedly highlighted the stressors that Black youth experience, often finding that Black youth face higher levels of stress and trauma than their White peers. However, there has been a lack of research in understanding how Black youth cope with these higher levels of stress. This systematic review includes 72 studies (N = 16,205 participants) examining the frequency and effectiveness of coping strategies used by Black youth in response to a trauma or stressor, along with the associations between utilized coping strategies …