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The backstory to “Swaying the Public”: a design chronicle of election forecast visualizations
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Historical and present-day influences of neighborhood context on fertility
No full text2025Infertility affects 10–15% of reproductive-aged couples in the U.S. Recent work suggests that neighborhood- and population-level factors are associated with fertility, indicating a role for the built and social environment in infertility prevention. Neighborhood context may increase risk of infertility through stress, limited access to societal resources, and exposure to environmental pollutants. Changes in neighborhood context can also limit residents’ access to financial stability and wealth accumulation. This dissertation examines historical and present-day influences of neighborhood context on fertility in the largest, most diverse preconception cohort in existence. This work focused on fecundability, a sensitive marker of fertility, defined as the per-cycle probability of conception. In Study 1, we estimated the association between historical mortgage lending discrimination (i.e., redlining) and fecundability. In Study 2, we evaluated associations between economic, racial, and racialized economic segregation with fecundability. In Study 3, we characterized county-level socioeconomic trajectories between 1930-2020 and estimated their association with fecundability. This work launches the first preconception cohort studies to evaluate neighborhood environments as a structural determinant, allowing research triangulation of complex ways that place-based inequities shape fertility (e.g., a historic racist practice, modern segregation, changes in socioeconomic characteristics over time). All these studies advance our understanding of disparities in infertility using linked geospatial data (e.g., historical maps, census population data). We recognize neighborhood context as the full spectrum of racial or ethnic, social, economic, and environmental features that characterize geographic regions. This dissertation is highly responsive to the call to action for consequential epidemiologic evidence from measures of structural racism and drivers of socio-environmental stressors in disadvantaged and privileged neighborhoods.2028-05-31T00:00:00
Synthetic epigenetic circuits to investigate robustness and adaptability of epigenetic inheritance in schizosaccharomyces pombe
No full text2025Chromatin-based epigenetic regulation globally governs cell expression states in eukaryotes, credited with robustly protecting cell-specific programming in development of multicellular organisms, but also involved in developmental disorders, cancer propagation, and adaptation. This potency inspires targeting or repurposing epigenetic elements for development of next generation cellular and molecular therapies. However, defining sufficiency for integral properties such as durable inheritance has remained elusive. What are the requirements for generating robust epigenetic inheritance? Functional motifs such as “read-write” positive feedback are common in chromatin systems, and their importance in epigenetic memory in natural systems is well documented. Using bottom-up approaches, minimal synthetic epigenetic systems with “read-write” have been shown to actively propagate chromatin states, but cannot overcome antagonistic forces. Epigenetic crosstalk, another common feature in natural systems, represents a plausible mechanism for reinforcing “read-write” propagation and conferring stable epigenetic inheritance. Here, we built synthetic crosstalk between distinct kinds of modifications (histone modifications and DNA modifications) in the fission yeast Schizosaccharomyces pombe. We established a non-native DNA modification, N6-methyladenine (m6A) and characterized a set of “writer” domains. We then coupled m6A to the native heterochromatic modification H3K9me using combinations of respective “read” and “write” domains, discovering engineering limitations in pombe heterochromatin systems. We constructed complete feedback circuits that rely on artificially introduced epigenetic crosstalk between the native H3K9me and the non-native m6A. We built and screened combinations of components to uncover properties that enable crosstalk-mediated inheritance. We discover key design choices such as cooperative binding, we find engineering limits on components compatible with native machinery, and ultimately discover regimes that enable epigenetic super-memory in cells for more than 50 generations, requiring strong crosstalk and high modification site frequency. Finally, we explore how crosstalk-mediated epigenetic memory manages against perturbations to the system.
In a second project, we considered how cells make adaptive epigenetic choices. Recent studies show heterochromatin-defining H3K9me can be redistributed to establish adaptive phenotypes. We developed a precision-engineered genetic approach to trigger heterochromatin misregulation on-demand in pombe. This enabled us to trace genome-scale RNA and H3K9me changes over time in long-term, continuous cultures. Adaptive H3K9me establishes over remarkably slow timescales relative to the initiating stress but ultimately leads to cells converging on an optimal adaptive solution. Upon stress removal, cells relax to new transcriptional and chromatin states, establishing memory primed for future adaptive epigenetic responses. Collectively, we identify the slow kinetics of epigenetic adaptation that allow cells to discover and heritably encode novel adaptive solutions, with implications for drug resistance and response to infection.2026-05-22T00:00:00
Journal of African Christian Biography: v. 9, no. 1: Booklet (WORD), print-ready
No full textThe full issue of Journal of African Christian Biography: v. 9, no. 1 is available at: https://hdl.handle.net/2144/4807
The influence of arousal on visuocortical processing in humans
No full text2024Vision plays a pivotal role in our everyday lives, shaping our perception and consequently influencing our behavior and actions. However, vision is far from static. There are a number of processes that dynamically influence how we see our environment from moment to moment, with one process being states of arousal. For example, driving on a freeway, our vision is likely quite different when we are drowsy compared to when we are alert. While animal studies have found arousal states to substantially modulate visual responses, our understanding of its effects on human vision remains limited. To shed light on arousal’s influence on human visual processing, this work comprised a series of pupillometry and functional magnetic resonance imaging (fMRI) experiments aimed to untangle the influence of cognitive and emotional arousal on contrast processing in human early visual cortex (V1-V3). The goal of the first two experiments was to explore the influence of cognitive arousal – arousal induced by cognitive factors such as effort, load and task difficulty – on visuocortical contrast response functions (CRFs). Experiment 1 (n = 24) was a pupillometry study with dual objectives: first, to assess the reliability of a cognitive arousal manipulation for subsequent use in the ensuing fMRI study, and second, to determine the optimal luminance range for monitoring pupillary changes associated with cognitive arousal. This groundwork set the stage for integrating pupillometry into the subsequent fMRI study to monitor changes in arousal states. To achieve this, the experiment assessed the reliability of a cognitive arousal manipulation using auditory arithmetic problems of varied difficulties (hard, easy) while investigating its interaction with luminance on pupil size. Consistent with previous studies, pupil size was reliably modulated by math difficulty, evoking larger pupils for hard difficulty problems. Furthermore, the results revealed that there are indeed luminance regimes more ideal in observing pupillary differences by cognitive arousal—with high luminance being the least ideal. In Experiment 2 (n = 20), fMRI was employed to investigate the influence of cognitive arousal on CRFs in V1-V3. BOLD responses were measured while observers viewed stimuli that parametrically varied in contrast. Concurrently, different cognitive arousal states were induced with observers solving auditory arithmetic problems categorized as easy (low cognitive arousal) or hard (high cognitive arousal). The findings revealed a surprisingly diverse pattern of modulatory effects among individuals: some individuals displayed enhanced gain of neural response with increased cognitive arousal, while others exhibited the opposite effect—a decrease in gain with increased cognitive arousal. Furthermore, individuals' BOLD modulation patterns correlated with arousal-induced changes in their pupil size. The subsequent two experiments explored the impact of emotional arousal on pupil responses and CRFs in early visual cortex. Experiment 3 was a pupillometry study focused on assessing how emotional arousal interact with luminance in modulating pupil size. In Experiment 3A, observers (n = 36) listened to and rated sound clips from the International Affective Digitized Sounds (IADS) of neutral (low emotional arousal) and negative (high emotional arousal) valence, while the background luminance of the screen cycled through a range of luminance levels. In Experiment 3B (n = 36) and 3C (n = 33), observers viewed and rated grayscale and colored images from the International Affective Pictures System (IAPS) of neutral and negative valence. The results indicated that emotional arousal interacted with luminance in modulating pupil size differently from cognitive arousal: the effects were smaller and occurred solely at much lower luminances. Critically, there was a sizable group of individuals who did not display any response to the IAPS and IADS stimuli, across all luminances. Then, Experiment 4 (n = 12) investigated how emotional arousal, using negative and neutral auditory IADS sound clips, modulated CRFs. Overall at the group-level, emotional arousal had minimal effect on CRFs across the visual cortex. However, individual-level analysis revealed a subset of observers displaying enhanced neural gain with arousal, which contrasted with the majority showing little-to-no effect. Further analysis examining pupil size-based CRFs and CRFs in the lateral geniculate nucleus (LGN) uncovered consistent and robust modulatory effects among observers. Notably, the modulatory effects varied between different CRF delineations (valence versus pupil size) and among distinct visual areas (LGN versus V1-V3). These results collectively shed light on how arousal, with its diverse forms and individual differences, selectively modulates contrast processing
The role of deficient mismatch repair system in Lynch syndrome and the increased risk of colorectal cancer
No full text2024Over the years, the prevalence of colorectal cancer has increased, most significantly among young individuals, with colorectal cancer currently being the third leading cancer diagnosis in the world (Nfonsam et al., 2022). While many of the causes of colorectal cancer are unclear, there are some hereditary conditions that have been shown to put individuals at an increased risk. Around 30% of all colorectal cancers are due to inherited syndromes, with 2-5% being the result of known conditions (Zhang et al., 2015). The most prevalent known hereditary condition predisposing individuals to develop colorectal cancer is what is known as Lynch syndrome. Initially, Lynch syndrome was termed hereditary non-polyposis colorectal cancer (HNPCC) in order to distinguish it from the second most common inherited cancer syndrome, familial adenomatous polyposis (FAP) (Zhang et al., 2015). The term Lynch syndrome is now considered a more specific diagnosis than HNPCC and the words are no longer used synonymously. Lynch syndrome predisposes individuals not only to colorectal cancer, but also to a wide range of other cancers including gynecologic, gastrointestinal, genitourinary cancers as well as cancers of other organs (Biller & Creedon et al., 2022). It has been found that approximately 3% of individuals diagnosed with colorectal cancer have Lynch syndrome (Biller & Syngal et al., 2019). Lynch syndrome is the result of germline mutations in DNA mismatch repair genes (Yurgelun & Hampel, 2018). Analysis of individuals and families with Lynch syndrome found that patients had defects specifically in chromosomes 2, 3 and 7 (Zhang et al., 2015). The significance of these chromosomes was later discovered as it was found these chromosomes contained the DNA mismatch repair genes, MSH1, MSH2, MSH6, PSM1, and PMS2 (Zhang et al. 2015. Specifically, chromosome 2 was found to contain the genes MSH2, MSH6, and PSM2, chromosome 3 contained the gene MLH1, and chromosome 7 contained the gene PMS2 (Zhang et al., 2015). In addition to the four MMR genes, it was also found that germline deletions in the non-MMR gene EPCAM (Epithelial-cell adhesion molecule) can also result in Lynch syndrome due to EPCAM’s location upstream from the MMR gene MSH2 (Biller & Creedon et al., 2022). A deficient MMR system often results in the phenotype microsatellite instability (MSI) which is a strong diagnostic indicator of Lynch syndrome. The connection between Lynch syndrome and defects in mismatch repair genes have had important implications in the diagnosis and treatment of Lynch syndrome associated colorectal cancer
Neural mechanisms of planning
No full text2024Planning is foundational to human cognition, enabling flexible, goal-directed behavior. This cognitive process is often altered in disorders such as schizophrenia and obsessive-compulsive disorder. Despite its relevance, the precise brain mechanisms underlying planning are poorly understood. A challenge in studying planning comes from the various levels of abstraction at which planning can occur. Here, I consider planning as the evaluation, selection, and preparation of future actions in anticipation of future needs. The aim of this dissertation is to resolve some of the gaps in our understanding of planning and its neurobiology. In motor planning, the execution of a precise action requires that the appropriate movement is performed at the correct time. Previous work has established the role of preparatory ramping activity in motor planning. Inspired by past work on memory, I asked whether variability in ramping dynamics among cortical neurons can provide information about the ‘what’ and ‘when’ of motor plans. By evaluating a publicly available dataset, I show that the variability of ramping speeds across neurons in the mouse frontal motor cortex reflects a pattern of heterogeneity that contributes to the population encoding of the ‘what’ and ‘when’ of motor plans. These findings draw parallels between the neural correlates of prospective actions and retrospective events. At a higher level of abstraction, planning can be performed using an internal model of how the world may change or react to our actions. Using this world model, actions can be evaluated based on their potential outcomes and the value of those outcomes. To study the mechanisms underlying model-based planning, I trained rats to perform a two-step decision-making task. Improvements in training standardization and automation allowed behavior to be monitored throughout the acquisition of this task, revealing two learning processes: an early phase where rats learn task statistics independently of rewards, and a later phase of rapid, goal-directed learning associated with model-based planning. This reveals how animals adapt their strategies over time to optimize performance. A core computation in model-based planning is the evaluation of actions using a learned world model. The neural circuit supporting this function is unknown. The retrosplenial cortex is a strong candidate region given its involvement in value-based decision making and spatial reasoning. Using a potent and selective chemogenetic strategy for inactivation, I tested whether the retrosplenial cortex is required for model-based planning in rats during the two-step task. Surprisingly, the inactivation of the retrosplenial cortex increased the degree to which rats' behavior shows evidence of model-based planning, while decreasing patterns of model-free, reward-seeking behavior. This result suggests that this brain region may mediate interactions between model-based and model-free control of behavior, providing a potential neural mechanism for this trade-off. In summary, the findings presented in this dissertation offer new insights into the neural mechanisms of planning. In particular, they highlight cortical contributions to planning across two spatial and temporal scales: the preparation of an imminent action seconds prior to its execution and the evaluation of alternative actions based on the outcomes they may produce multiple steps into the future
Beyond the great powers: how South American states are navigating US-China competition in the 21st century
No full text2025What explains smaller states’ approaches to great power competition? Why have states not aligned with the US and China? Drawing on three case studies in South America, this dissertation finds that states are pursuing one of three non-alignment patterns and argues that political elites’ ideas, interest group politics, and the construction of state identity drive these outcomes. Recent scholarship’s articulation of a hedging strategy for navigating great power competition is an important departure from a balancing-bandwagoning binary, but it draws almost exclusively from East and Southeast Asia. By expanding the geographical scope to Latin America, this dissertation uncovers new variation in states’ non-alignment patterns. The project theorizes two additional categories of non-alignment: diversification, in which states pursue parallel policies with both great powers and disclaim any role in competition, and concentration, in which they prioritize one great power and deploy critical rhetoric towards the other to cover continuing relations. Comparative case studies of Chile, Argentina, and Ecuador incorporate evidence from nearly 90 interviews with policymakers and interest groups leaders, policy documents, party platforms, and major newspapers to trace the policymaking process. The cases demonstrate that these patterns result from a complex domestic political process involving ideas, interests, and narratives. In addition to interest group politics, political elites are heavily influenced by the ideas they hold about the operating mechanisms of the international system – i.e. the degree to which it is a zero-sum game – and about the role of the rising power in that system, chiefly whether or not it constitutes a security threat. These factors are channeled through an overarching narrative about a state’s identity and positionality in the international system, which legitimizes certain patterns of non-alignment while foreclosing others. Overall, this project demonstrates that smaller states have an important role in the process and outcomes of great power competition, and that the structure of the international system is a permissive, but not determining, factor in how they design and implement their foreign policies
Latino music student perspectives on Hispanic Serving Institution initiatives at a Public Texas University
No full text2026Hispanic Serving Institutions (HSIs) are federally designated higher educational institutions. Institutions seeking HSI designation eligibility for federal funding must obtain 25% full time enrolled undergraduate Latino students. Even though research around HSIs is growing, music and arts programs at HSIs receive less research focus than STEM-related disciplines. A paucity of research exists on how arts initiatives at HSIs affect the lived experiences of Latino music students. In this qualitative research study, four volunteer participants provided responses in a series of interviews, journaling prompts, and a focus group. Data was collected over the course of 13 weeks. I examined collected data using Latina/o critical theory to identify the effects of HSI initiatives on the lived experiences of Latino music students. There were two guiding questions. 1. What are Latino music students’ perceptions of institutional “servingness” (Garcia, 2019) and the credibility (Little & Green, 2022) of Hispanic Serving Institutions? 2. In what ways, if any, do the participants in this study believe the policies and programs at their Hispanic Serving Institution impact their musical experiences as a music major? I focused on three categories of Latino ethnicity to represent a diversity of perspectives from within the Latino cultures. Participants had an initial meeting near the end of their fall semester to discuss the instructions for the journaling prompts and partake in the first interview. Throughout the spring semester, each participant responded digitally to prompts sent by the researcher. A second interview was held mid semester. Near the end of the spring semester, participants engaged in a focus group to discuss their experiences. Recorded data was transcribed and given to the participants to review. Data triangulation was achieved through journals, interviews, and a focus group. Transcriptions were then analyzed for underlying codes and themes. The findings of this study will contribute to the body of knowledge regarding Latino experiences in collegiate music education at HSIs. The underlying themes will provide context that can inform administrative decisions regarding HSI arts initiatives. Further research will be useful for further study in hopes of supporting Latino students towards degree attainment
Journal of African Christian Biography: v. 1, no. 2: Booklet, with cover (8.5 x 11 format), print-ready
No full textThe full issue of Journal of African Christian Biography: v. 1, no. 2 is available at: https://hdl.handle.net/2144/3566