MSU Libraries Digital Repository (Michigan State University)
Not a member yet
106711 research outputs found
Sort by
Synaptic and membrane properties of distinct neuronal populations driving motivated behaviors
No full textThesis (Ph.D.)--Michigan State University. Molecular, Cellular, and Integrative Physiology \u2013 Doctor of Philosophy, 2025Mood disorders, such as major depressive disorder (MDD), are highly prevalent and have a complex multifactorial etiology, with stress vulnerability emerging as a major risk factor. The prevalence of MDD is almost twice as high in women as in men, but the biological basis of this sex difference remains unclear. Additionally, roughly half of MDD patients do not fully respond to existing treatments, underscoring the need to identify cellular and molecular mechanisms to guide novel therapeutic strategies. Both stress and MDD are associated with abnormalities in the brain\u2019s reward circuitry, suggesting distinct neural circuits may contribute to symptom heterogeneity. This dissertation investigated two distinct mechanisms that may underlie its pathophysiology: the role of androgen receptors, ion channels, and hormones in the ventral hippocampus-nucleus accumbens (vHPC-NAc) circuit, and the role of oxytocin neurons in social circuits.The vHPC-NAc circuit has been implicated in stress-induced anhedonia in male mice. Our lab previously found that female mice have increased basal vHPC-NAc intrinsic excitability compared to males that directly drives susceptibility to anhedonia. Moreover, vHPC-NAc circuit excitability is reduced by adult testosterone, but the mechanisms by which androgen receptors (AR) regulate this excitability remained unknown. Using whole cell slice electrophysiology, I found AR activation by non-aromatizing androgens in vHPC-NAc neurons reduces circuit excitability, which may contribute to the sex differences in MDD. Translating Ribosome Affinity Purification sequencing (TRAP-seq) revealed AR-dependent regulation of multiple ion channels and signaling pathways which drive sex-specific behaviors and vulnerability to stress. I found that sex differences in vHPC-NAc neuronal excitability may be driven by androgen-dependent alterations in the function or expression of calcium and/or potassium channels such as L-type calcium channels. In a related line of experiments, I characterized oxytocin neurons in circuits underlying social behaviors. Chronic social defeat stress induces MDD-like behaviors including increased social vigilance and decreased social interaction. Oxytocin (OT) is a key modulator of social behaviors, and both the bed nucleus of the stria terminalis (BNST) and paraventricular nucleus (PVN) of the hypothalamus are important coordinators of social behavior and anxiety. Previous work found BNST oxytocin neurons are more sensitive to social defeat stress in females than males and blocking oxytocin synthesis prevents stress-induced social changes. Using whole cell slice electrophysiology in oxytocinCre-GFP mice, I found BNSTOT and PVNOT neurons share similar electrophysiological and morphological properties, although no sex differences were found. These data suggest sex-specific behaviors may be due to circuit-level differences in oxytocin receptor distribution and connectivity. Together, this work demonstrates how hormones and neuropeptides shape stress- and reward-related circuits, providing insight into mechanisms underlying mood disorders and identifying potential targets for novel therapeutic strategies.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
HETEROATOM DIRECTED IRIDIUM METAL CATALYZED C\u2013H BORYLATION AND GREEN ENERGY EFFICIENT SYNTHESIS OF DIBORONDIOLATES
No full textThesis (Ph.D.)--Michigan State University. Chemistry - Doctor of Philosophy, 2025Contemporary methods for transforming C\u2013H bonds into C\u2013B bonds often rely on transition metal catalysis, that significant advantages over traditional methods. These include the utilization of inexpensive and widely available hydrocarbon precursors, minimized production of hazardous waste, and more direct access to pharmaceutically relevant compounds. Although most transition metal-catalyzed C\u2013H borylation efforts have concentrated on modifying sp2-hybridized C\u2013H bonds in aromatic and heteroaromatic systems, the present study investigates the selective transformation of sp3 C\u2013H bonds.Borylation on sp3 C\u2013H bonds have been shown by using directing groups, either by generating them in situ with help of catalyst or coordinating them at the catalyst by opening a vacant site. Replacing one of the triboryl Bpin group at the iridium center by silyl group in-situ allowed to direct CHB on nearby sp3 C\u2013H bond. The use of a heterogeneous catalyst system featuring a monodentate ligand formed a 14-electron catalyst system, allowing the substrate to coordinate with the catalyst. However, the ligand involved required extensive steps for synthesis. In this study, we report on the use of amides as directing groups for CHB on sp3 C\u2013H bonds. Homogenous bidentate ligands were synthesized using commercially available reagents to create a 14-electron iridium catalyst system that permits regioselective CHB on amides. Diborondiolates are the preferred reagents for iridium-catalyzed C\u2013H borylation, with commercially available pinacolborane being the most common choice. Many other diborondiolates are not available commercially, so a user-friendly procedure for preparing these reagents would benefit both academia and industry. We developed a green, simple, and energy-efficient method as an alternative to previous procedures for synthesizing diborondiolates. Achieving ortho-selective C\u2013H borylation (CHB) poses a significant challenge, as it must overcome the inherent steric preferences that typically dictate site selectivity in these reactions. Our group previously developed a strategy enabling highly ortho-selective CHB of anilines using a compact diboron reagent, B2eg2 (eg = ethylene glycol). However, the resulting boronic esters were unstable and required transesterification with pinacol to isolate usable products. This limitation was addressed by examining how the size of the diboron reagent influences both reactivity and product stability. While smaller borylating agents preserve ortho-selectivity, bulkier counterparts yield more stable boronic esters. Among those tested, B2bg2 (bg = 1,2-butanediol) offers an optimal compromise between regioselectivity, reactivity, and product stability. The first example of C\u2013H borylation (CHB) on aliphatic C\u2013H bonds within amidine frameworks is developed using an iridium-based catalyst. The resulting products can be isolated either as boronic esters or as air-stable bifluoroborate salts. Remarkably, selective C(sp3)\u2013H borylation is achieved even in the presence of sterically accessible C(sp2)\u2013H. The method demonstrates high selectivity for both primary and secondary C(sp3)\u2013H bonds adjacent to the nitrogen atom.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
\u201cLEADERSHIP IS SOCIAL JUSTICE\u201d : A QUALITATIVE STUDY OF SOCIAL JUSTICE-ORIENTED LEADERSHIP COURSES
No full textThesis (Ph.D.)--Michigan State University. Higher, Adult, and Lifelong Education - Doctor of Philosophy, 2025Addressing social inequalities and injustice is a critical and ongoing pursuit that remains a significant challenge in society as of 2025, prompting a call to arms in leadership education to develop social justice-oriented leaders; however, although many leadership educators believe in this call to action, they remain uncertain about what and how to incorporate social justice elements in their respective curricula. To address this gap, the following research question guided the study: What factors determine how instructors design and facilitate social justice-oriented leadership courses? I used the nine elements of the diversity inclusivity model (Nelson Laird, 2010) to identify the key concepts and variables relevant to the study. After interviewing 14 instructors who taught socially just leadership courses, numerous themes emerged under four major categories: beliefs and values, attributes, knowledge, and skills. The findings suggested participants believed leadership is social justice work; subsequently, the instructors designed and facilitated their courses using current theories and best practices to support learning. Based on the findings, I developed a new exploratory conceptual map to represent and highlight how leadership instructors are the driving force for creating these social justice-oriented leadership courses.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Wearing Wellness : A Comparative Analysis of Continuous Glucose Monitor Narratives in a Self-Surveilling Wellness Culture
Get PDFThesis (M.A.)--Michigan State University. Rhetoric and Writing \u2013 Master of Arts, 2025Building from established work on wearable rhetorics and wellness culture (Brady, 2024; Derkatch, 2022; Elman, 2018; Gouge & Jones, 2016; J. Jones et al., 2017; Lawrence, 2023; Shew, 2020, 2022, 2023), this project examines marketing narratives surrounding the emergence of over-the-counter continuous glucose monitors (OTC CGMs) in the United States (Abbott, 2024; U.S. Food and Drug Administration, 2024). I explore how audiences and kairotic moments impact health and wellness narratives around continuous glucose monitors (CGMs) by engaging with the following research questions: (1) How does the introduction of OTC CGMs shape Type 1 Diabetic (T1D) and non-Type 1 Diabetic (non-T1D) CGM narratives? (2) What are the affordances and implications of the narratives told to each audience group? (3) What can this case tell us about the current state of health and wellness culture in the United States? To conduct my study, I use a modified conventional content analysis framework (Hsieh & Shannon, 2005) informed by Tracy\u2019s (2020) iterative content analysis and inductive coding methods to identify emerging themes across six CGM websites made up of two audience groups. Overall, blood glucose is positioned as an emergent health indicator, and CGM narratives have shifted toward wellness as a primary factor for CGM adoption in both audience groups. I identify four discursive pillars of CGM narratives, including interface, agency, experience, and outcomes, which offer a lens to examine the narratives of wearable technologies. Ultimately, this case illustrates how narratives shape our understanding of technologies and communicate the current culture\u2019s values and concerns surrounding health and wellness.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
SIGNALS IN THE STREAM : USING TELEMETRY TO UNRAVEL THE INFLUENCE OF CURRENTS, GEOMORPHOLOGY, AND PREDATOR CUES ON SEA LAMPREY MIGRATION
Get PDFThesis (Ph.D.)--Michigan State University. Fisheries and Wildlife - Doctor of Philosophy, 2025The spawning migration is a critical life stage for many fishes, demanding effective navigation, energy management, and risk avoidance strategies. This is particularly challenging for non-homing, semelparous species like the sea lamprey (Petromyzon marinus), which undertakes extensive riverine migrations fueled solely by endogenous energy reserves while facing novel predation threats. Understanding the behavioral mechanisms underlying this migration extends beyond the increasing our knowledge of the movement ecology and animal behavior. It is crucial for both controlling invasive populations in the Laurentian Great Lakes and conserving native populations elsewhere. This dissertation integrates fine scale acoustic telemetry, computational fluid dynamics (CFD) modeling, and field-based experimental manipulations to investigate how migrating sea lampreys respond to key environmental signals\u2014hydrogeomorphology, hydrodynamic currents, and chemical risk cues\u2014within a natural river system.First, we demonstrate that sea lampreys utilize persistent geomorphological features for navigation. Tracking revealed that migrants consistently follow river thalwegs (deepest channels), swimming near the substrate. This behavior conferred a mean energetic saving of 5.8% compared to near-surface swimming and likely enhances safety from shoreline predators. We propose a novel navigation mechanism, hydrostatic pressure-guided rheotaxis, facilitates this efficient and potentially safer movement strategy. Second, we provide field-based validation of energy optimization theory by examining swim tactics in varying currents. Sea lampreys adjusted their swim speed to maintain a relatively constant ground speed (mean 0.92 body lengths s-1), consistent with minimizing the cost of transport according to exponential models. Minor decreases in speed in deeper water suggest potential trade-offs with perceived risk. Third, we investigated responses to predation risk using conspecific alarm cues. Exposure induced structured changes in movement consistent with odor-guided rheotaxis, including a localized intensive search phase (reduced speed, increased tortuosity). Critically, when navigating the risk cue, lampreys prioritized immediate avoidance of the odor plume, splitting paths around the source, rather than selecting routes through deeper, putatively safer, habitat. Collectively, these studies reveal that sea lamprey migration is guided by a sophisticated integration of environmental signals, resulting in predictable, context-dependent movement patterns. This research enhances our mechanistic understanding of migration ecology and provides actionable insights for management and conservation, informing the placement of control or passage devices and the application of behavioral manipulation strategies by highlighting the importance of river morphology, flow dynamics, and sensory cue interpretation.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Insights Into Great Lakes Basin Water Resources Through Field Data And Hydrologic Model Integration
Get PDFThesis (Ph.D.)--Michigan State University. Earth and Environmental Sciences \u2013 Doctor of Philosophy, 2025The Laurentian Great Lakes are the largest system of connected surface water lakes in the world. Fresh surface and groundwater totaling approximately 27,000 km3 stored within the Great Lake Basin are a critical resource for the region and the rest of North America. However, anthropogenic contaminants, invasive species, increasing water use demands and a changing climate threaten these water resources in the Great Lakes Basin. To mitigate these threats, a better understanding of the processes controlling water resources, and hydrologic modeling frameworks capable of simulating past, current and future conditions are required. This dissertation seeks to apply both of these methods to study water quality and groundwater-surface water interactions within the state of Michigan region. Two primary research questions are addressed in this dissertation. First, what are the landscape and hydrologic factors which control stream nutrient concentrations? This question is addressed in Chapter 2 through the analysis of regional scale repeated synoptic stream chemistry sampling data and statistical analysis. Second, how are groundwater dynamics linked to Great Lakes lake levels, either indirectly through regional climate or directly through boundary condition effects? This topic is investigated in Chapters 3 and 4 using a coupled, process-based surface and groundwater model. Results from Chapter 2 suggest that landscape characteristics are a powerful predictor of stream chemistry early in the year during snowmelt, but that the landscape becomes decoupled from stream chemistry as the seasons progress. Relationships between streamflow and water chemistry during the spring and summer high flow events indicate distinct water chemistry patterns despite similar flow conditions when compared to baseflow. Chapter 3 investigates how groundwater storage changed during a period of extreme lake level variations. Simulations of surface hydrology and groundwater elevations from 2000-2023 using the Landscape Hydrology Model indicate that groundwater elevations increased along with lake elevations between 2013-2020, but that the onset of these storage increases lagged the onset of lake level changes by 2-4 years. In Chapter 4, this model is applied to investigate how coastal wetland connectivity to surface and groundwater changes as lake and groundwater elevations fluctuate. Modeling analysis suggests that rising groundwater elevations between 2000-2023 increased the amount of connected coastal wetland area by 18% when compared to estimates of surface water connectivity change alone. Finally, Chapter 5 provides a summary and proposes a method for more closely integrating field data collection and hydrologic models to groundwater nutrient transport through the use of a model-experiment framework.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Proton-Capture Cross-Section Measurements for the Astrophysical Gamma Process : From Stable to Radioactive Ion Beams
Get PDFThesis (Ph.D.)--Michigan State University. Physics - Doctor of Philosophy, 2025One of the key questions in nuclear astrophysics is understanding how elements heavier than iron are forged in the stars. Heavy element nucleosynthesis is primarily governed by the slow and rapid neutron capture processes. However, a relatively small group of naturally occurring, neutron-deficient isotopes, known as p nuclei, cannot be formed by either of those processes. These ~30 nuclei are believed to be synthesized in the \u3b3 process, where preexisting r- and s-process seeds are "burned" through a sequence of photodisintegration reactions. The astrophysical sites where such conditions occur have been a subject of controversy for more than 60 years, and is currently believed that the \u3b3 process can take place in the O/Ne layers of core collapse supernovae, and in thermonuclear supernovae. Reproducing solar p-nuclei abundances through nuclear reaction networks requires input on a large number of mostly radioactive isotopes. However, as experimental cross sections of \u3b3-process reactions are very limited, and almost entirely unknown for radioactive nuclei, the related reaction rates are based on Hauser-Feshbach (HF) theoretical calculations and therefore carry large uncertainties. Therefore, it is crucial to develop techniques to accurately measure these reactions within the astrophysically relevant Gamow window with radioactive beams. The SuN group at the Facility for Rare Isotope Beams (FRIB) has been developing such a program for the past decade. This thesis focuses on implementing a technique to measure reaction cross sections in inverse kinematics with a radioactive beam. Specifically, this work presents data analysis from the proof-of-principle stable beam experiment for the 82Kr(p,\u3b3)83Rb reaction, along with the measurement of the 73As(p,\u3b3)74Se reaction in our first radioactive beam experiment. The latter reaction is particularly significant for the final abundance of the lightest p nucleus, 74Se, since the inverse reaction 74Se(\u3b3,p)73As is one of the primary destruction mechanisms of 74Se. The experiments were conducted at FRIB at Michigan State University using the ReA facility. The 82Kr and 73As beams were directed onto a hydrogen gas cell located in the center of the Summing NaI(Tl) (SuN) detector and the obtained spectra were analyzed using the \u3b3-summing technique. In addition to the total cross section measurements, this thesis also presents the development of an analysis technique to extract statistical properties of the compound nucleus (nuclear level density and -ray strength function) through a series of simulations. This approach enables the extraction of an experimentally constrained cross section across the entire Gamow window of the \u3b3 process. Finally, the experimentally constrained reaction rate for the 73As(p,\u3b3)74Se reaction is used in Monte Carlo one-zone network simulations of the \u3b3 process to explore its impact on the production of the 74Se.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Enhancing Link Prediction on Graphs : A Multifaceted Approach
Get PDFThesis (Ph.D.)--Michigan State University. Computer Science - Doctor of Philosophy, 2025Graphs are a common way of representing real-world structured data. A graph is composed of nodes connected with one another via edges (i.e., "links"), where a link models how such nodes are related to one another. Due to the prevalence of graph-structured data, machine learning on graph data has become very popular.Link prediction, which attempts to predict unseen links in a graph, is a fundamental task on graphs. Link prediction has a multitude of real-world applications, including in recommender systems, knowledge graphs, and biology. In recent years, a flurry of methods have been introduced that make use of graph neural networks (GNNs) for this task. However, we find that multiple limitations impede our ability to create effective link prediction models that can perform in real-world settings. First, we find that the current method of evaluating link prediction models is both unrealistic and too easy, resulting in inflated model performance that doesn't reflect real-world performance. Second, we observe that current methods are limited in their ability to model various patterns in link formation. This poses a challenge in real-world datasets where links can form for a number of reasons. Third, efficiency is an important concern in link prediction, as effective models are often expensive to run. Lastly, we find that link prediction models on knowledge graphs suffer from degree bias, where poor representations are learnt for lower-degree nodes, leading to subpar performance. In this thesis, we first uncover the root cause of these fundamental limitations. I will then introduce our attempts to combat these problems, through the design of new evaluation strategies and new model design. Through the introduction of these new approaches, we help promote better use of link prediction in more realistic scenarios that can occur in the wild.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
ESTIMATING THE ACCURACY OF TEAM MENTAL MODELS THROUGH TRANSITION-PHASE INFORMATION-SHARING : A NEURAL GRAPH MATCHING APPROACH
No full textThesis (Ph.D.)--Michigan State University. Psychology - Doctor of Philosophy, 2025Team mental models (TMMs) are the representations of shared cognition within a group, driving team coordination based on their shared understanding of critical information. TMM accuracy is traditionally operationalized as the structural similarity between the TMM and an expert's mental model across a fixed set of task-relevant concepts. However, this approach to TMM accuracy does not capture information accuracy, as teams may discuss topics outside the scope of the expert\u2019s mental model. The present dissertation introduces a new methodology for extracting TMMs from team transition phases and evaluating their accuracy against a referent model. Semantic meaning is extracted from team communications using the DeBERTa neural transformer architecture, which is then represented as a topic network through Exploratory Graph Analysis (EGA). Finally, this team topic network is compared for similarity to a referent network based on node-level and tie-level properties through a technique called neural graph matching, which leverages a graph neural network (GNN) to compare networks that differ in size and content. The present study used this technique to derive each team's TMM focus (i.e., the proportion of on-task to off-task knowledge in the team discussion) and TMM completeness (i.e., the extent to which all topics in the referent network are represented in the team's network). Results from the neural graph matching positively correlated with expert judgments, presenting initial evidence of the technique's validity. TMM focus showed generally null relationships with performance. Teams showed improved performance on tasks where they achieved higher TMM completeness (within-team) compared to their average completeness over all tasks. Unexpectedly, teams lower in average completeness demonstrated an improved trajectory in performance over time compared to teams with higher average completeness. Finally, the moderating role of the rate of change for TMM completeness within a transition phase yielded null results. Overall, these results suggest that TMM information accuracy has a dynamic relationship with performance, as teams monitor and adapt their strategies over time to achieve high performance. Further, this dissertation presents initial validity evidence for a new technique to estimate the information accuracy of TMMs. These new methods provide a foundation for measuring information accuracy in TMMs, and can clarify the mechanisms driving the dynamic cycle between team transition and action phases.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Essays on Agricultural Land Use : Tradeoffs, Information, and Incentives in Precision Agriculture and Wind Energy
Get PDFThesis (Ph.D.)--Michigan State University. Agricultural, Food and Resource Economics - Doctor of Philosophy, 2025Agricultural land plays a critical role not only in food production, but also in advancing environmental sustainability and renewable energy goals. Given these diverse functions, landowners face complex decisions that require balancing agricultural productivity with environmental objectives. Their decisions can be shaped by the quality of information guiding expected returns and varying policy and market incentives. This dissertation investigates how agricultural landowners make land use and management decisions when faced with tradeoffs, imperfect information, and differing incentives. The first chapter examines the tradeoff that landowners\u2019 face between farming and conservation. It focuses on estimating the opportunity cost of precision conservation, a practice that converts low-yielding areas into conservation area while minimizing foregone revenue. Using fine-scale yield maps from Michigan corn and soybean fields from 2020 to 2024, we calculate the opportunity costs of foregone yields, yield effects on adjacent cropland, and input cost savings. Assuming a 10-year conservation period under a corn-soybean rotation, results show that precision conservation improves profitability in 19 of 29 fields, with an average annualized profit increase of 235/ac higher than that of precision conservation, with differences ranging from 349/acre higher. The second chapter evaluates how different sources of information affect the profitability of variable rate nitrogen (VRN) application. Utilizing 17 field-years data from 13 Midwest fields during 2021-2023, it compares VRN prescriptions based on remotely-sensed early-season vegetative vigor (NDVI) and historical yield maps. Applying linear regression and spatial discontinuity analysis, the study finds a heterogeneous treatment effect, with profitability gains from NDVI compared to yield history prescriptions ranging from 350 ha-1. NDVI-based prescriptions were more profitable when weather conditions diverged from historical trends and remained stable throughout the season (e.g., 2021), while yield history outperformed when early-season signals failed to persist and conditions ultimately reverted to historical norms (e.g., 2023). These results highlight the value of adapting nitrogen management to seasonal weather conditions by combining long-term yield patterns with real-time crop vigor signals. The third chapter examines the effects of two overlapping policy interventions on wind energy development in Michigan: the revision of Public Act 116, which eased land-use restrictions on preserved farmland, and the Wind Energy Resource Zone designation under Public Act 295, which supported infrastructure development in areas with high wind potential. Employing a difference-in-differences framework, the analysis spans townships and cities in Michigan, Minnesota, and Wisconsin from 2000 to 2023. The findings indicate that the PA116 revision had no statistically significant effect, whereas the Wind Zone designation led to an additional 90 megawatts (MW) of installed electrical generation capacity. These results underscore the varying effectiveness of land-use policies. Because the farmland preservation program offered limited economic incentives to begin with, loosening its restrictions had minimal impact. In contrast, the proactive designation of Wind Zones with clear development signals and coordinated infrastructure planning significantly accelerated wind turbine deployment in Michigan.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references