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Journal of African Christian Biography: v. 8, no. 2: Separate cover file (PDF), print-ready
No full textThe full issue of Journal of African Christian Biography: v. 8, no. 2 is available at: https://hdl.handle.net/2144/4608
Sequence learning and experience-driven modifications create sparse predictive representations of visual information in mouse primary visual cortex
No full text2024Vision is a widely studied aspect of brain function, and a great deal of research has uncovered the principles by which the cortical hierarchy converts spatiotemporal light patterns into unique neural representations that are the basis of our ability to perceive objects in the visual scene. More recently, primary visual areas have been used to study common principles of cortical function that are shared with other brain regions. Predictive coding is an influential theory of cortical function that might explain some properties of extra classical receptive fields in the visual system but has not been experimentally verified in a general sense. Particularly absent is an understanding of how evoked neural activity modifies cortical circuits to form predictive representations. The visual cortex is highly plastic and can encode spatiotemporal relationships, making it a useful model system to test how experience modifies cortical circuits to encode memories that include temporal information, and how these modification affect the processing of subsequent sensory inputs and are used to make predictions. We begin with a review of visual neuroscience with a particular focus on what is known about the architecture and function of the mouse visual system. We discuss the anatomical circuits that convert light into neural activity and how it this filtered, processed, and refined in the early visual system. This includes a discussion of the coding strategies employed by the retina, properties of thalamic relay cells, and an overview of neocortical circuitry. This section concludes with a review of visual cortical plasticity. Next, we review the theoretical and conceptual framework that underlies predictive processing theories of cortical function. We compare several predictive coding models and discuss implementation details proposed by these theories with respect to the neocortical circuit. We then conduct a review of previous experimental work aimed at testing the extent to which cortical dynamics can be understood as predictive processing. This includes computational studies of visual cortical responses, mismatch negativity, sensorimotor mismatch signals, and recent discoveries of prediction error cells in the visual and auditory systems. We then present our original research investigating predictive and temporal processing in the mouse primary visual cortex (V1). We conducted two-photon calcium imaging in layer 2/3 of the mouse V1 while animals were exposed to visual sequences over several days. We analyzed thousands of cells in search of prediction error responses and characterized how visual experience and expectation change temporally coordinated activity in visually responsive cells. Consistent with predictive coding models, we find that neural activity during following the omission of a predicted element is elevated at the time of expected visual transitions in a trained but not naïve animals. Substituting an unexpected stimulus, however, did not generate significant prediction error responses. Using linear decoders, we show that training has little effect on the ability to accurately decode stimulus identity or time within an experiment despite finding that evoked response dynamics are significantly modified over training. We also show that individual cells’ peak firing times span the temporal duration of both active visual stimulation and interstimulus gray periods. Finally, we show that low-dimensional representations of neural activity become more selective for individual elements of the trained sequence while population level responses become sparser and decorrelated, consistent with the efficient coding hypothesis
Characterization of tuberculosis-affiliated immune correlates of protection in an immunocompetent susceptible mouse model
No full text2024Roughly 25% of the global population is estimated to harbor a latent tuberculosis infection at any given time. For reasons currently largely unknown, 10% of primary lesions caused by this infection reactivate and progress to the contagious form of post-primary pulmonary tuberculosis (pppTB). pppTB causes 1.5 million deaths annually, making it second to COVID-19 for most-lethal by volume disease in recent years. Humans are the only known reservoir of infection, making complete eradication a possibility. The BCG tuberculosis vaccine is administered to 100 million children annually, but does not confer lifelong immunity, rather it prevents progression from primary infection to pppTB. We aimed to investigate lesional immune cell population differences in BCG–vaccinated Kramnik mice, which faithfully recapitulate human-like pppTB pathogenesis. We found that low-titer vaccination is more similar to not being vaccinated at all than it is to adequately high-dosage vaccination via multiplex fluorescent immunohistochemistry to characterize myeloid and lymphocyte subpopulations within pulmonary lesions
Journal of African Christian Biography: v. 1, no. 6: Booklet, no cover (A4 format), print-ready
No full textThe full issue of Journal of African Christian Biography: v. 1, no. 6 is available at: https://hdl.handle.net/2144/3566
Pedagogical creativity: a multiple case study of concert band director practices
No full text2025With this multiple-case study, I investigated how instrumental music educators apply pedagogical creativity within the context of traditional wind band education. Utilizing the theoretical framework of Abramo and Reynolds (2015), which defines pedagogical creativity through four core traits—structured improvisation, ambiguity tolerance, metaphorical thinking, and fluid teacher identity, I explored how these characteristics manifest in the lived experiences and instructional practices of three exemplary concert band directors. Through in-depth interviews, classroom observations, and thematic analysis, I analyzed how these educators balance the tension between product-oriented ensemble traditions and more responsive, student-centered pedagogical approaches. Findings reveal that pedagogical creativity manifests through intentional flexibility, student empowerment, and emotionally safe learning environments. Participants, Lyla, Ella, and Austin, demonstrated how their deep pedagogical content knowledge enabled them to scaffold instruction while fostering student agency and expressive musicality. Their practices reflect a shift away from rigid, director-centric rehearsal models toward more collaborative and relational artistry, where technical mastery serves broader educational and humanistic aims. This study contributes to a growing discourse on reimagining ensemble teaching by positioning pedagogical creativity as a transformative force in music education. Rather than aligning instruction solely with traditional performance outcomes, participants intentionally employed student-centered deviations—what I described as constructive misalignments—to challenge normative expectations and reframe learning around deeper engagement, emotional growth, and shared meaning-making. These deliberate strategies prioritized musical exploration, student autonomy, and a culture of care
The osteogenic effects of zirconia and titanium surfaces on human osteoblasts
No full text2025The search for optimal implant materials that ensure rapid osseointegration, long-term stability, and biocompatibility remains a central focus in both dental and orthopedic research. Titanium has long been regarded as the gold standard for implant material; however, zirconia-based materials have emerged as promising alternatives, offering advantages such as superior esthetics, excellent biocompatibility, and favorable mechanical properties. This study investigates the biological responses of normal human osteoblasts cultured on titanium and zirconia surfaces, focusing on key cellular events including attachment, proliferation, alkaline phosphatase (ALP) activity, and osteocalcin expression over a 21-day period. Quantitative analysis revealed that zirconia surfaces supported equal or superior early-stage cellular responses compared to titanium, particularly in attachment efficiency and proliferation rates. While both titanium and zirconia promoted significantly elevation of ALP activity relative to controls, titanium surfaces showed marginally higher late-stage osteocalcin expression. These findings highlight the potential of zirconia-based materials to serve as effective alternatives to titanium in implant applications, particularly in cases where esthetics and early osseointegration are critical. Moreover, the study emphasizes the need for further optimization of zirconia surfaces—through modifications such as nanostructuring and biofunctionalization—to enhance late-stage osteogenic outcomes. This work contributes to a better understanding of material-specific effects on osteoblast behavior and provides valuable insights for the design of next-generation implant materials with improved biological and clinical performance
Study of altered metabolism in cancer by high content SRS microscopy
No full text2025Altered metabolism represents an Achilles' heel of cancer, offering opportunities for advanced diagnosis and treatment. However, studying cancer metabolism at the single-cell level remains challenging. Current methods are either destructive and provide only bulk analysis, like mass spectrometry, or require fluorescent labeling that can perturb metabolic processes. Recently developed high-content, high-resolution SRS microscopy enables single-cell metabolic analysis and I successfully applied this approach to identify and target metabolic pathways in cancer therapy contexts.In the first project, I applied high-content SRS imaging to study metabolic changes in ovarian cancer cells surviving the CAR-T challenge. CAR-T therapy shows promise in liquid tumors but faces significant challenges in solid tumors like ovarian cancer. I used drug interventions to improve CAR-T cytotoxicity based on the identified metabolic alterations. In the second project, I used isotope-probed SRS imaging to visualize fatty acid distribution differences between wild-type ovarian cancer cells and those resistant to platinum treatment. I examined subcellular localization at lipid droplets and ER membrane levels to identify the affected cellular components. I then followed up with tissue-level analysis of triglyceride changes in cellular regions of xenograft models treated with fatty acid inhibitors combined with platinum therapy. The third project demonstrates the development of high-content SRS histology that provides both morphological information like conventional histology and detailed chemical information at the cellular level in breast cancer tissues, with potential applications to other cancer types.
Together, the work in my dissertation shows that advanced SRS imaging can reveal metabolic reprogramming during cancer therapy and identifies specific metabolic vulnerabilities that can be targeted to improve treatment efficacy. The methodological advances developed here enable studying metabolism-based therapeutic strategies across multiple cancer types and treatment approaches.2027-09-02T00:00:00
Evaluation of printing orientation, layer thickness and auxilary cross-arch bar in 3-dimensional dental printing on the trueness and precision of full arch polymeric fixed dental prostheses
No full text2025OBJECTIVES: Evaluate the accuracy (Trueness and Precision) of 3D-printed full-arch fixed
dental prostheses by examining the effects of different printing angulations, layer thicknesses, and the inclusion of a horizontal cross-arch bar. MATERIALS AND METHODS: Two 3D-printed dental resin materials for full-arch fixed dental prostheses were used in this study; Lucitone Digital IPN™ and OnX Tough 2. A standardized CAD design generated in Dental CAD 3.1 Rijeka software was exported as an STL file and served as the reference model. A total of 104 specimens were printed with
Carbon M2 printer at varying angulations (0°, 40°, and 70°), layer thicknesses (25 µm and 50 µm), with or without a horizontal cross-arch bar, and were post-processed following the manufacture recommendations. Specimens were analyzed using Geomagic Control X software, where they were superimposed onto the reference STL via best-fit alignment for 3D inspection analysis at a tolerance level of 50 µm. Trueness was assessed by calculating root mean square (RMS) and standard deviation (SD) values, while precision was
determined by measuring absolute linear deviations (mm) in pairwise comparisons within each group to evaluate reproducibility. RMS, SD and linear deviation data were analyzed using multivariate least square mean linear regression in JMP Pro 18 software to identify statistically significant effects (⍺ = 0.05). Microstructural analysis was conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to
examine surface morphology and elemental composition. Moreover, ash burnout testing
was employed to quantify the inorganic filler content and evaluate the residual mass of each material. RESULTS: The RMS and SD values varied among resin materials, with OnX Tough 2consistently showing lowest deviation values, and the highest accuracy in term of trueness across all tested variables. Overall, for both materials printing at a lower angulation (0°) resulted in superior trueness compared to 40° and 70° angulations. OnX Tough 2, exhibited improved trueness when printed at 50 µm layer thickness and without a cross-arch bar. In
contrast, for Lucitone Digital IPN™ the most accurate outcomes were achieved at 25 µm
layer thickness and with the addition of a horizontal cross-arch bar. No statistically significant differences in precision were evident across study variables: angulation, layer thickness and the presence of a cross-arch bar. IPN is an unfilled resin, primarily composed of an organic polymer matrix, whereas OnX is a filled resin with a complex composite formulation of silica and ytterbium-based inorganic reinforcements. CONCLUSION: OnX Tough 2 resin demonstrated superior trueness and precision compared to Lucitone Digital IPN™, as evidenced by lower RMS, SD, and absolute linear deviation values across all study groups. Printing at 0° angulation resulted in the highest levels of
both trueness and precision. The effects of layer thickness and the presence of a horizontal
cross-arch bar were found to be material-dependent, with filled resins such as OnX Tough
2 being more sensitive to these parameters. The most favorable combination for achieving
optimal accuracy with OnX was identified as 0° angulation, 50 µm layer thickness, and
without a cross-arch bar
Journal of African Christian Biography: v. 8, no. 1: Booklet, no cover (A4), print-ready
No full textThe full issue of Journal of African Christian Biography: v. 8, no. 1 is available at: https://hdl.handle.net/2144/4547
Essays on experiential alchemy: transforming negative consumption experiences into positive utility across the consumption journey
No full text2026If to err is human, then to be human is to have negative experiences. Yet, humans tend to over-focus on negative experiences, holding onto them as if they are precious treasures. As Emily Dickinson put it, “[we] measure every grief [we] meet with narrow, probing, eyes.” However, while negative consumption experiences are inevitable, how we shape and view them, both prospectively and retrospectively, is not. Thaler (1985) describes humans as “pleasure machines,” acting in ways which attempt to maximize their enjoyment, and minimize their psychological pain. However, in this dissertation, I contend that human beings can also be thought of as “regret machines,” in this conception consumers are often hyper-focused on both the avoidance of negative feelings while simultaneously having a hard time letting go of negative experiences. In these essays I explore three strategies that consumers can use in order unsaddle themselves from the burdens of negative feelings and transform their negative experiences into ones that provide them with positive utility. In my first essay, I examine a strategy that consumers can use at the pre-purchase stage of consumption to downplay negative feelings that would result from having to consume something that conflicts with their identity. My second essay explores a post-purchase strategy for “experiential alchemy” that consumers naturally utilize to alleviate the negative feelings from having incurred sunk costs. Finally, my third essay focuses on post-consumption regret and a powerful intervention which not only helps consumers cope with negative experiences, but also makes them more likely to reengage with brands over and above industry standard responses to service failures (e.g., refunds, apologies)