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Future Weather Trends + Infrastructure
No full textClimate data and observations show that Minnesota is experiencing consistent changes in weather patterns. This report explores how projections of future weather trends may exacerbate conditions, including but not limited to drought, elevated temperatures and flooding for the design and evaluation of infrastructure and buildings constructed by the state of Minnesota and local governments. In addition, the report assesses the potential of future weather events to weaken existing systems creating the need for intervention to maintain and increase the amount and quality of food and wood production, reduce fire risk on forested land, maintain and enhance water quality, and maintain and enhance natural habitats. Because the relationships between infrastructure, future weather trends and the human-natural systems of agriculture, water, forests, and built environments are complicated, the research team developed a framework to analyze the Social, Ecological and Technological (SETs) relationships within each system, creating a common “language” to analyze potential interactions between multiple complex systems (Chapters 3 and 4). This approach is crucial for decision makers to be effective at mitigating costs and avoiding maladaptation or making things worse from some resilience strategies.Institute on the Environment (IonE); Center for Sustainable Building Research (CSBR); University of Minnesota Climate Adaptation Partnership (MCAP). (2025). Future Weather Trends + Infrastructure. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278842
Exploring physical therapy clinicians’ perception and experiences of the barriers and facilitators to implementing the American Heart Association physical activity and exercise recommendations for stroke survivors in the United States of America
No full textUniversity of Minnesota M.S. thesis. 2025. Major: Kinesiology. Advisor: Emily Kringle. 1 computer file (PDF); vi, 82 pages.Background: Regular physical activity reduces recurrent stroke risk, yet survivors rarely meet the American Heart Association (AHA) Physical Activity and Exercise Recommendations. Uptake depends heavily on physical therapists (PTs) and physical therapy assistants (PTAs), whose perspectives on implementing these guidelines remain underexplored. This study aimed to explore PTs’ and PTAs’ experiences, perceived barriers and facilitators, and gather their suggestions for improving adherence to the AHA recommendations during stroke rehabilitation.
Methods: Guided by a constructivist paradigm and the Theoretical Domains Framework (TDF), this qualitative study recruited ten purposively sampled early, mid, and experienced career PTs and PTAs from acute care, inpatient, outpatient, home health, and skilled-nursing settings who completed semi-structured Zoom videoconference interviews. Reflexive thematic analysis was used to generate themes and map them to TDF domains.
Results: Five interrelated themes aligned with key TDF domains. Therapists identified several systems-level constraints that hindered consistent use of guidelines, including short treatment sessions, strict productivity targets, limited equipment, and restrictive insurance policies. Although therapists had limited recall of specific AHA guideline parameters, they utilized professional reasoning to incorporate core recommendations into functional tasks and everyday activities. Patient-related barriers, such as fear of falls or recurrent strokes, fatigue, and low health literacy, further complicated adherence, especially when language differences were a factor. Therapists noted that effective interdisciplinary teamwork, active family involvement, and creative, interest-based physical activity strategies helped them overcome many of these challenges. They advocated for concise, multilingual patient resources, competency-based professional training and motivational techniques, stroke-specific community support groups, and policy reforms that tie reimbursement to functional outcomes rather than the number of treatment minutes.
Conclusions: To enhance guideline adherence, a dual approach is necessary. This involves leveraging therapists’ tacit clinical reasoning while simultaneously strengthening explicit guideline knowledge through competency-based training and concise, user-friendly multilingual patient materials. Additionally, policy reforms that link reimbursement to functional outcomes and provide adequate funding for therapy time and equipment are essential. By addressing these multilevel determinants, we can improve implementation fidelity and ultimately enhance outcomes for stroke survivors.Badu, Amos. (2025). Exploring physical therapy clinicians’ perception and experiences of the barriers and facilitators to implementing the American Heart Association physical activity and exercise recommendations for stroke survivors in the United States of America. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278735
Too soon to conclude: curtailed information gathering marks delusions but not specific delusions across psychosis patients and community participants
No full textUniversity of Minnesota M.A. thesis. 2025. Major: Psychology. Advisor: Angus MacDonald III. 1 computer file (PDF); iv. 26 pages.Background: Effective decision-making requires resolving the explore–exploit tradeoff, in which individuals use probabilistic reasoning to determine when to shift from information gathering to reward-seeking. Psychosis has been linked to idiosyncratic evidence gathering and reduced tolerance for uncertainty, yet the contributions of specific psychotic symptoms remain unclear. Although jumping to conclusions (JTC) has been associated with psychosis, the unique relationship between delusions and reduced evidence gathering, transdiagnostically and above other symptom domains, is less well understood. Additionally, the predictive utility of alternative measures of delusionality in this context has not been systematically examined.
Methods: A mixed sample of patients with psychosis (n=48) and community participants (n=70) completed a variant of the classic Beads Task, assessing evidence gathering and belief updating. Delusionality was measured via clinician-rated global severity, summed delusion item totals, and dimensional severity across subtypes. Mixed-effects linear models examined associations between these measures and task performance while controlling for other symptom domains and cognitive functioning and tested the relative predictive utility of delusion measurement approaches.
Results: Performance related to the meso-level of symptom specificity. That is, global delusion severity significantly predicted both reduced evidence gathering and diminished belief updating, however no delusion subtype was more closely related. At the same time, other symptom domains did not show the relationship. Furthermore, while controlling for intelligence improved model fit, delusions remained a significant predictor of evidence gathering, while belief updating was more strongly associated with intelligence.
Conclusion: Reduced information gathering and a hastier exit from an information gathering (exploration) mode were linearly and specifically related to global delusion severity. Reduced belief updating followed a similar pattern, though may reflect general cognitive ability to a greater extent. Global delusion severity may be the most appropriate to measuring delusionality in evidence-gathering studies.McCain, Christopher. (2025). Too soon to conclude: curtailed information gathering marks delusions but not specific delusions across psychosis patients and community participants. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/277988
Quantifying iron-redox variations in silicate liquids responsible for the magmatic oxygen fugacity diversity of Mars
No full textUniversity of Minnesota Ph.D. dissertation. October 2025. Major: Earth Sciences. Advisor: Marc Hirschmann. 1 computer file (PDF); ix, 112 pages.This thesis explores how the wide range of oxygen fugacities recorded in martian igneous lithologies were generated by placing quantitative constraints on the iron-redox systematics of martian magmas. Superliquidus experiments on silicate mixtures matching those of martian magmas were leveraged to quantify how oxygen fugacity (fO2) variations are related to changes in magmatic Fe3+/FeT ratio. The experiments presented here were conducted in vertical gas-mixing furnace, aerodynamic-laser-levitation furnace, and ½ in. piston cylinder apparatuses at temperatures ranging from 1250–2100 °C, pressures ranging from 100 kPa–3 GPa, and fO2s ranging from 4.54 logfO2 units below to 7.16 logfO2 units above the quartz-fayalite-magnetite redox buffer (QFM-4.54 to QFM+7.16). The Fe3+/FeT ratio of all glasses were measured using a combination of Mössbauer spectroscopy, colorimetric wet chemistry, and Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy (standardized by measurements of glass with Fe3+/FeT determined by Mössbauer spectroscopy). These measurements were combined with those from comparable studies on martian magma compositions. From these experiments, stepwise regression was used to construct models relating Fe3+/FeT to fO2, temperature, pressure, and composition to then apply for calculating the mass transfer required to generate fO2 variations observed from oxybarometry of shergottites, fO2 variations that occur from temperature variations during cooling, and fO2 variations that occur during magmatic decompression. In addition, the agreement between silicate glass Fe3+/FeT determined by Mössbauer spectroscopy and colorimetric wet chemistry techniques was validated, addressing a longstanding discussion comparing the techniques’ precision and accuracy. In addition, an experimental design for investigating the temperature-dependent redox behaviors of silicate liquids over a range 850 °C, combining vertical gas-mixing furnace experiments with aerodynamic-laser-levitation furnace experiments, is presented for the first time.Aithala, Sanath. (2025). Quantifying iron-redox variations in silicate liquids responsible for the magmatic oxygen fugacity diversity of Mars. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278777
A first-principles study of ferroelectricity via symmetry-mode couplings
No full textUniversity of Minnesota Ph.D. dissertation. July 2025. Major: Chemical Engineering. Advisors: Turan Birol, Paul Dauenhauer. 1 computer file (PDF); xxiv, 145 pages.Polarization—the net dipole moment per unit volume—is the fundamental response of insulating materials to an external electric field. Ferroelectrics are a unique class of insulators capable of sustaining spontaneous polarization even in the absence of an applied field. Since their discovery nearly a century ago, our understanding of ferroelectrics has rapidly advanced, driving significant technological innovations. However, recent findings suggest that ferroelectricity still harbors unexplored phenomena with the potential to revolutionize future applications. In this dissertation, I present the core body of research conducted during my graduate studies, beginning with first-principles simulations of polarization switching in ferroelectrics using density functional theory, combined with group theory and the Landau-Ginzburg-Devonshire theory. I then explore an emerging application of ferroelectric-supported catalysis. Specifically, I present a method to examine how polarization switching modulates adsorption and reaction processes in dynamic catalysis. Next, I investigate the competitive coupling between octahedral rotations and polarization in perovskites, which can give rise to antiferroelectric behavior. Finally, I introduce the concept of "hybrid-triggered" ferroelectricity, arising from unconventional phonon couplings. This discovery gives rise to the concept of higher-order dynamical charges, which may provide a key mechanism underlying the mitigation of one of the most significant barriers to the technological deployment of ferroelectrics: the depolarization field in the thin-film limit.Jung, Seongjoo. (2025). A first-principles study of ferroelectricity via symmetry-mode couplings. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278206
Untangling spatial, environmental, and genetic drivers of foliar endophyte community assembly
No full textUniversity of Minnesota Ph.D. dissertation. October 2025. Major: Ecology, Evolution and Behavior. Advisor: David Moeller. 1 computer file (PDF); xi, 118 pages.Plants and their microbiomes form integrated systems where the boundaries between host and microbe are often blurred. Foliar fungal endophytes—fungi living asymptomatically inside healthy leaves—colonize virtually all terrestrial plants and can profoundly influence host performance through effects on stress tolerance, pathogen resistance, and resource acquisition. Despite their ubiquity and ecological importance, we lack fundamental understanding of what determines which fungi colonize which plants. The central challenge is that multiple processes simultaneously shape communities—dispersal moves microbes across landscapes, environmental conditions filter which taxa can persist, and host plants selectively permit or exclude colonizers based on their traits—but these processes operate at different spatial scales and interact in complex ways that are rarely studied together, particularly in natural field environments.
Understanding microbial community assembly requires disentangling processes that operate hierarchically across biological scales. Regional dispersal patterns determine which taxa are present in a landscape, local environmental conditions filter this regional species pool, and host plants impose a final filter through their genetic makeup and expressed traits. However, testing this framework is challenging because spatial and environmental variation are often confounded, environmental conditions can alter host trait expression, and the specific plant traits mediating host genetic effects remain largely mysterious. While agricultural systems have provided valuable mechanistic insights, wild plant populations remain critically understudied, particularly through experimental approaches that can establish causation rather than correlation. I address these challenges through a novel ecological genetics approach that combines observational surveys with experimental manipulations of host origin and genotype in wild populations. Working with Clarkia xantiana, a wild annual wildflower native to California's Sierra Nevada foothills, I progressively narrow spatial scale while increasing experimental control.
In Chapter I, I surveyed endophyte communities across 50 sites spanning 100 kilometers to quantify how community structure is associated with geographic distance, environmental factors, and host identity. I separated out these often-confounded factors by repeatedly co-sampling three herbaceous plant species across a topographically complex landscape where space and environment are largely decoupled. Our study reveals that community composition shows strong associations with spatial distance, while alpha diversity varies in relation to environmental gradients differently across host species. Within sites, host species harbor largely distinct communities, yet the specific taxa associated with each host vary inconsistently across locations. This chapter establishes that different assembly processes may affect different axes of community variation and that the strength of host associations is scale-dependent.
In Chapter II, I implement a fully reciprocal transplant experiment across four sites, growing plants from four genetically differentiated source populations at all four sites in a factorial design. Despite clear fitness variation among populations, I find that site effects overwhelm source population influences on endophyte communities. Local environmental filtering and the available microbial species pool appear far more important than host population genetics, even though populations differ in traits potentially relevant to microbe interactions. This reveals that while host species identity matters, naturally occurring intraspecific genetic variation has minimal detectable effects under realistic field conditions.
In Chapter III, I take an experimental ecological genetic approach, manipulating host genotype within a single site using recombinant inbred lines that segregate for leaf anthocyanin content. By creating genetic variation in this target trait that exceeds what is found in natural populations, I test mechanistic hypotheses about trait-mediated assembly. Growing 48 genetic lines under factorial water and fungicide treatments, I find that anthocyanin content strongly predicts both community diversity and composition, with high-anthocyanin plants supporting greater diversity while excluding potentially pathogenic taxa that dominate low-anthocyanin plants. This work demonstrates that host chemical traits can mechanistically filter fungal colonization, revealing that while naturally occurring population-level variation may be insufficient to structure communities (Chapter II), experimental manipulation of genetic variation exposes underlying trait-based mechanisms. This establishes that secondary metabolite variation represents a fundamental organizing principle in foliar microbiome assembly, with implications for understanding how plant chemical diversity shapes microbial communities and how these interactions might evolve or be manipulated.
Taken together, this work establishes a hierarchical framework where regional dispersal patterns, local environmental filtering, and host chemical traits interact across scales to shape microbial community assembly in natural ecosystems. By revealing which processes operate at which scales and identifying specific mechanisms of host filtering through experimental manipulation in wild plant populations—an approach rarely applied to research on foliar endophytes—this dissertation provides a conceptual foundation for understanding the community assembly frameworks that shape plant microbiomes.Mueller, Taz. (2025). Untangling spatial, environmental, and genetic drivers of foliar endophyte community assembly. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278794
Active vision for efficient 3D reconstruction and rendering
No full textUniversity of Minnesota Ph.D. dissertation. June 2025. Major: Computer Science. Advisor: Nikolaos Papanikolopoulos. 1 computer file (PDF); ix, 95 pages.Active vision (AV) has been in the spotlight of robotics research due to its emergence in numerous applications, including urban surveillance, agriculture, and biomedicine just to list a few. Two major AV problems that gained popularity are the 3D reconstruction and scene rendering of targeted environments using different views of 2D images. While collecting and processing a large number of arbitrarily taken 2D images may become an arduous process in several practical settings, an efficient solution is to seek the optimal placement of available cameras in the 3D space so as to obtain the necessary visual information from fewer yet more informative images to effectively reconstruct or render environments of interest. In the first chapter, we introduce the problems of view planning (VP) and scene rendering, and the open challenges that this thesis addresses. The second chapter aims to alleviate the reliance on a pre-defined mesh model of the environment, which is a common assumption in existing model-based VP approaches. To that end, this chapter presents an efficient and realistic VP pipeline, which aims to optimize the viewpoints of cameras and hence the quality of the 3D reconstruction of a field of row crops without need for a given mesh model. The goal of the third chapter is to cope with the challenge of existing environmental noise that is not explicitly accounted for in existing VP approaches. To that end, a novel geometric-based reconstruction quality function is introduced for VP, that accounts for the existing noise of the environment, without requiring its closed-form expression. With no analytic expression of the objective function, this chapter presents an adaptive Bayesian optimization framework for accurate 3D reconstruction in the presence of environmental noise. The fourth chapter aims (i) to overcome the errors induced by certain geometric proxies in geometric-based VP approaches arising from e.g. non-informative and insufficient geometric cues, and (ii) to identify optimal VP solutions with adaptivity to similar yet unknown environments without need for re-training/re-optimization. This chapter presents an alternative VP framework that considers a reconstruction quality-based optimization formulation. The fifth chapter focuses on the 3D scene rendering task, relying on the so-termed Gaussian splatting (GS) models that provide outstanding visual quality along with computational efficiency. It proposes an active image selection framework to assist GS models aiming to address the limitations of existing passive GS approaches. Specifically, these approaches rely on either (i) densely collected views that introduce redundancy and increase processing and computational costs, or (ii) sparse-view settings that may result in reduced scene coverage and limited expressiveness of the 3D scene representation.Bacharis, Athanasios. (2025). Active vision for efficient 3D reconstruction and rendering. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278059
Are there sex-specific differences in obesity treatment outcomes in the pediatric population?
No full textUniversity of Minnesota Ph.D. dissertation. July 2025. Major: Biomedical Engineering. Advisor: Hubert Lim. 1 computer file (PDF); ix, 145 pages.Our sensory perceptions play a fundamental role in guiding behavior, relying on a series of intricate processes. These include decoding the physical properties of stimuli—such as light intensity and sound pressure—into meaningful features for object recognition. This transformation involves both bottom-up processing (driven by signals from peripheral sensors to central neural circuits) and top-down modulation (in which attention and prior knowledge shape perceptual interpretation). For those suffering from sensory loss, electrical stimulation through auditory and visual prosthetics can be used to restore sensory abilities. In addition, sub-perceptual electrical microstimulation can be used to modulate top-down behavioral and attentional processes. This thesis explores both applications of electrical stimulation, with the vision that future prosthetic technologies could potentially integrate sense restoration with concurrent engagement of attentional neural mechanisms to further improve sensory perception. Our work in the sensory restoration field centers on addressing the challenges faced by currently available auditory prosthetics. For users of the cochlear implant, for example, perception of music and speech recognition in noisy environments remain challenging. Motivated to overcome these limitations, we focus our efforts on development of an auditory nerve implant that bypasses the cochlea entirely and stimulates auditory nerve fibers directly. Intraneural stimulation offers many advantages over traditional cochlear implant stimulation but introduces new challenges such as the complex spatial organization of frequency regions within the auditory nerve. Our work utilizes electrophysiological studies to explore the variance of this tonotopic organization and demonstrates methods to reduce current spread and provide precise frequency targeting during stimulation. We also present studies in a large animal model (rhesus macaque) to test the feasibility and efficacy of an auditory nerve implant prototype currently being developed for human use. To further explore top-down attentional and behavioral processes, we investigate how microstimulation of the visual cortex can enhance perception of visual stimuli. Our work shows the ability of subtle, low amplitude microstimulation to significantly improve detection of a visual stimulus during a challenging behavioral task. The implications of these findings are that microstimulation could be used to improve visual perception of relevant stimuli in situations involving high noise or significant distractors. Combining this form of microstimulation with sensory restoration technologies could lead to improved performance in future prosthetic devices.Sondh, Inderbir. (2025). Are there sex-specific differences in obesity treatment outcomes in the pediatric population?. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278087
Black studies in the news: a content analysis of the New York Times’ coverage of collegiate Black Studies between 1968-1999
No full textUniversity of Minnesota M.A. thesis. July 2025. Major: Organizational Leadership, Policy, and Development. Advisor: Karen Miksch. 1 computer file (PDF); vii, 142 pages.This thesis analyzes The New York Times' coverage of collegiate Black studies between 1968 and 1999, examining how mainstream media framed the field's history, roles and goals. Employing a critical content analysis and drawing on theories of managing minority difference, this project investigates how media portrayals aligned with institutional strategies to conform Black studies to the expectations of traditional disciplines. Findings reveal a consistent emphasis on conflict and mainstreaming, often presenting internal disagreements as self-inflicted and detrimental. The coverage frequently positioned Black Studies as a response to student protest, which is framed as baggage to be overcome. While acknowledging Black studies' contributions to academia, the Times often positioned this role as incompatible with the goals of fostering material racial justice and involving community members in knowledge creation. This analysis illuminates how journalistic framing influenced public perception, shaping the field's trajectory towards academic legitimization at the expense of its more radical origins and community-oriented aims, and highlighting the ongoing tension between scholarly pursuit and social transformation.Oertel, Jacob. (2025). Black studies in the news: a content analysis of the New York Times’ coverage of collegiate Black Studies between 1968-1999. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/277995
Machine learning methods for reconstructing spatially resolved transcriptomes
No full textUniversity of Minnesota Ph.D. dissertation. August 2025. Major: Computer Science. Advisor: Rui Kuang. 1 computer file (PDF); xi, 107 pages.Dissecting the molecular, cellular, and spatial heterogeneity of tissues is critical to characterize how cells of different types function and communicate with each other underlying the spatial context, which eventually advances the understanding of phenotypic variations within tissues under various conditions. Recent advances in spatial transcriptomics technologies have enabled the profiling of spatially resolved maps of the whole transcriptome from intact tissues, revolutionizing transcriptomics studies and providing unique insights into biomedical research, particularly in developmental biology, neuroscience, immunology, and cancer biology. However, missing signals in spatial transcriptomics data due to technical limitations pose unprecedented challenges to their downstream analyses, and prohibitive costs associated with spatial transcriptomics technologies further hinder their practical implementation in large-scale clinical studies. To overcome these issues, my dissertation research seeks to develop computational methods to reconstruct spatially resolved transcriptomics based on either different modalities of spatial transcriptomics data or conventional transcriptomics data to provide high-quality and cost-effective alternatives. Chapter 3 presents our work on reconstructing spatially resolved transcriptomics from existing incomplete spatial transcriptomics data. We propose a graph-guided neural tensor decomposition method coupled with spatial and functional relations in spatial and PPI graphs (GNTD) to model nonlinearity in spatial transcriptomics. Comprehensive benchmarking indicates GNTD clearly outperforms baseline methods for spatially resolved transcriptomics imputation, and extensive comparisons between GNTD and baseline methods show our method excels in several important downstream analyses, such as spatial domain detection, spatially variable gene identification, spatial trajectories inference, and spatially co-expressed gene clustering. Chapter 4 focuses on reconstructing spatially resolved transcriptomics from tissue staining images. We introduce an adaptive spatial graph neural network (asGNN), which utilizes adaptive spatial graphs to better capture spatial relations embedded in tissue morphology through smoothing-based variational optimization, accurately predicting spatial gene expressions. Comparisons with state-of-the-art methods reveal that the predicted spatial expressions of marker genes from asGNN are highly correlated with their ground truth in the matched spatial transcriptomics data. Furthermore, the spatial graphs obtained from asGNN precisely delineate spatial domains in the tissues without the need for additional clustering analyses. Chapter 5 presents our recent work on reconstructing 3D spatially resolved transcriptomics from transcriptome tomography. We propose a collapsed tensor decomposition model (CTFacTomo) with reconstructed expression tensor regularized by spatial and functional relations while the collapsed tensor matching with the expression matrix along given spatial axes. Quantitative comparison on simulations from existing 3D spatial transcriptomics data and qualitative comparison on tomo-seq data demonstrate that CTFacTomo better restores the expression signals and characterizes 3D spatial patterns with focused regions.Song, Tianci. (2025). Machine learning methods for reconstructing spatially resolved transcriptomes. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/278088