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QUANTITATIVE DISSECTION OF MOLECULAR DRIVING FORCES IN MEMBRANE PROTEIN FOLDING
Get PDFThesis (Ph.D.)--Michigan State University. Chemistry - Doctor of Philosophy, 2025Burials of ionizable residues inside hydrophobic core are unfavorable in general due to the high desolvation cost of transferring them from water to lipid bilayer. Nevertheless, these residues can form ion-pairs and play vital roles in cellular functions including proton/electron transfer, catalysis, and receptor activation. Proteins in thermophilic microbes maintain their fold and activity in extreme environments like volcanoes, ocean ridges and hot springs with high temperatures (80\u2013110 \ub0C). Previous studies suggested that thermophilic proteins achieve thermostability via an increased number of salt-bridges between ionizable residues compared to their mesophilic homologs. Thus, studies regarding the ionizable residues and thermostability of thermophilic proteins are essential for the fundamental understanding of protein stability, function, and engineering. While related studies have mostly concerned water-soluble proteins, these topics received less attention in membrane proteins. In my dissertation, I aim to bridge the knowledge gaps using the universally conserved rhomboid protease family as a model. I focused on addressing the following two questions: 1) What is the energetic consequence of burying ionizable residue pairs in the core of membrane protein? 2) What is the origin of the thermostability of membrane proteins in thermophilic organisms? In the first question, I found that bearing ionizable residues inside membrane protein induces destabilization of membrane protein kinetically and thermodynamically. Double mutant cycle analysis suggests paired internal ionizable residues form favorable interaction in micelle and bicelle environments. In the second question, my results demonstrate that the delipidated thermophilic rhomboids lose their stability and are fully inactivated at temperatures below their optimal growth conditions compared to mesophilic rhomboid. These results suggest lipids play critical roles in buried ionizable pairs and thermostability in membrane protein folding.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Essays in Empirical Industrial Organization
Get PDFThesis (Ph.D.)--Michigan State University. Economics - Doctor of Philosophy, 2025Chapter 1: Steering Consumers\u2019 Learning: Evidence from Stockout Substitutions in Curbside Pickup Items ordered for curbside pickup sometimes go out of stock, obliging the store to choose substitutes on consumers\u2019 behalf. Using novel data from a supermarket chain, I show these \u201cstockout substitutions\u201d influence consumers\u2019 future purchases through the mechanism of learning. This presents the store with the following opportunity to increase its future profits: if the store selects substitutes from profitable brands that consumers have never tried before, some consumers will learn that they like the brands of their substitutes and purchase these brands\u2019 products in the future. However, consumers are less likely to accept such substitutes than they are to accept substitutes from brands they have previously purchased. To quantify the trade-off between steering consumers\u2019 learning and maximizing the probability of substitutes' acceptance, I estimate a learning-based model of differentiated products demand. Although steering consumers\u2019 learning proves an unprofitable strategy, the store can still increase profits---and consumer welfare---by individualizing substitutions according to consumers\u2019 past purchases and demographics.Chapter 2: Demand Estimation When Consumers\u2019 Preferences Vary over TimeThis paper shows that workhorse demand systems fail to reproduce important substitution patterns when individual consumers\u2019 preferences vary over time. This failure is rooted in the independence of preferred alternatives (IPA) properties of conditional and mixed logit, which restrict the relationship between consumers\u2019 purchases and their preferences among unpurchased goods. To assess the empirical relevance of the IPA properties, I employ novel data from stockout substitutions in curbside pickup. For the two product categories that I study, I document substitution patterns that are inconsistent with the IPA property of conditional logit. As for mixed logit, its IPA property proves consistent with the substitution patterns in one of the two product categories. To quantify the benefits of relaxing the IPA property of mixed logit, I compare the model\u2019s goodness of fit with that of mixed probit (which does not display an IPA property). In keeping with the descriptive evidence, the results of this comparison vary by product category.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
SYNTHESIS OF LIQUID LIGNIN POLYOL DESIGNED FOR FLEXIBLE POLYURETHANE FOAMS
Get PDFThesis (Ph.D.)--Michigan State University. Chemical Engineering - Doctor of Philosophy, 2025Over the years, there has been a growing need for sustainable alternatives to replace petroleum-based polyols in the formulation of flexible polyurethane (PU) foams. Lignin, being the second most abundant natural polymer after cellulose, possesses various hydroxyl functionalities, making it a good polyol replacement. However, the incorporation of lignin in polyurethane flexible foams has been hampered by lignin\u2019s rigid structure, high hydroxyl value, poor solubility in co-polyols, and low reactivity towards isocyanate. Therefore, it is important to overcome these limitations to fully harness lignin\u2019s potential in flexible polyurethane foam applications. This study presents various modification strategies to synthesize liquid lignin polyols suitable for flexible PU formulations. Lignin was first oxyalkylated using varying molar ratios of propylene carbonate (PC) (4, 5, and 10 equivalents (eq)), and the resulting liquid lignin polyols were directly incorporated into flexible PU foam formulations. While the inclusion of lignin polyols increased the biobased carbon content of the foams, excessive residual PC adversely affected key mechanical properties such as tensile strength, tear resistance, and compression force deflection (CFD). Fourier-transform infrared (FTIR) spectroscopy indicated that unreacted PC interfered with microphase separation, weakening intermolecular interactions and reducing the overall strength of the lignin-based foams. A lignin-to-PC molar ratio of 1:5 was identified as optimal, providing a balance between processability and thermomechanical performance. Next, various co-polyols were used to further minimize PC loading in the lignin oxyalkylation reaction from 5 to 2eq. The results indicated that high ethylene oxide (EO)-based polyols showed the best compatibility with lignin oxyalkylation reaction and promoted lignin\u2019s phenolic hydroxyl group\u2019s reactivity with PC, while propylene oxide (PO)-based and bio-based polyols (such as castor oil, soy polyols, and cardanol-based polyols) showed poor compatibility, resulting in a solid\u2013liquid two-phase mixture during the reaction. Partial least squares (PLS) modeling (R2Y = 86%, Q2Y = 67%, using two components and cross-validation) revealed a strong positive correlation between the co-polyol\u2019s EO content and compatibility, and a strong negative correlation between compatibility and the co-polyol\u2019s average molecular weight. Following optimization of the oxyalkylation reaction, a flexible PU foam incorporating 20% lignin polyol in place of petroleum-based polyols demonstrated enhanced mechanical properties and met industry standards for automotive seating. Additionally, a foam formulation with 50% total polyol replacement, comprising 20% lignin polyol and 30% soy polyol, met all performance criteria except elongation at break, while showing improved CFD compared to commercial counterparts. Finally, high-performance novel lignin-based polycarbonate polyols were prepared via a two-step process involving oxyalkylation of lignin with propylene carbonate, followed by transesterification with dimethyl carbonate. The resulting polycarbonate lignin polyols exhibited hydroxyl values (111\u2013179 mg KOH/g) and viscosities (11,660\u201325,950 mPa.s) suitable for flexible PU foam formulations. In-depth Nuclear Magnetic Resonance (NMR) analysis confirmed the grafting of long polyether chains onto lignin during the oxyalkylation step and the introduction of multiple carbonate linkages at the end of the transesterification step. Foams were formulated by replacing up to 40% of petroleum-based polyols with synthesized polycarbonate lignin polyols. Additionally, flexible PU foams were prepared by replacing 60% of conventional polyol with a combination of synthesized lignin polyol and soy polyol. Formulated foams demonstrated superior mechanical properties, including enhanced tensile strength, and load-bearing properties, compared to petroleum-based foams. Additionally, the foams exhibited improved thermal stability, shock absorption, and biodegradability.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
SMALL MOLECULE 20S PROTEASOME ACTIVATION : A TARGETED PROTEIN DEGRADATION PATHWAY FOR NEURODEGENERATION THERAPEUTICS.
Get PDFThesis (Ph.D.)--Michigan State University. Chemistry - Doctor of Philosophy, 2025The ubiquitin-proteasome system (UPS) represents a critical pathway in maintaining cellular proteostasis by regulating protein degradation. Dysregulation in this system is implicated in neurodegenerative diseases, where the accumulation of misfolded proteins exacerbates proteotoxic stress. This dissertation investigates small-molecule activators of the 20S proteasome, leveraging its unique capacity to degrade intrinsically disordered proteins (IDPs) independent of ubiquitination. Through systematically exploring the structural and biochemical dynamics of proteasomal activation, the work delineates the therapeutic potential of targeting the 20S proteasome for neurodegenerative conditions.Initial studies characterized the interplay between protein aggregation, oxidative stress, and proteostasis disruption in diseases like Parkinson's and Alzheimer\u2019s. A focus was placed on \u3b1-synuclein (\u3b1-syn), an IDP whose aggregation is central to Parkinson's pathology. Chapter Two describes the design, synthesis, and biological evaluation of third-generation chlorpromazine analogs, highlighting their efficacy in promoting 20S proteasome-mediated degradation of \u3b1-syn aggregates. Structure-activity relationships (SARs) were established, demonstrating the importance of specific substitutions in enhancing selectivity and minimizing off-target effects. Subsequent investigations in Chapter Three assessed these compounds in cellular models of oxidative stress. The results revealed that 20S proteasome activators mitigate oxidative damage by selectively degrading carbonylated proteins while preserving mitochondrial function. Chapter Four extends this work by introducing a novel piperazinone-based scaffold for 20S proteasome activators. These studies underscore the therapeutic promise of modulating proteasomal activity, providing a framework for future drug development to restore proteostasis and combat neurodegenerative diseases. This dissertation advances our understanding of proteasomal regulation and offers a compelling strategy to address the molecular underpinnings of protein misfolding disorders. The findings pave the way for developing clinically viable interventions targeting proteostasis networks, with significant implications for treating age-related neurodegenerative diseases.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
EXPLORING RELATIONSHIPS BETWEEN TEMPORAL PROCESSING DEFICITS AND PSYCHOSIS USING THE PEAK INTERVAL TASK
Get PDFThesis (Ph.D.)--Michigan State University. Psychology - Doctor of Philosophy, 2025Persons with schizophrenia commonly report distortions in their subjective experience of time. Mirroring these subjective experiences are findings that persons with schizophrenia are both less accurate, and precise, in detecting time in the range of seconds to minutes (interval timing). However, the mechanisms which give rise to these deficits in interval timing remain unknown as previous studies have relied on paradigms which do not allow us to easily dissect the influence of timing processes from memory, and decision making, on task performance. In addition, these studies have typically depended on samples who are taking antipsychotic medications making it difficult to determine whether deficits in interval timing are related to psychosis specifically or the consequences of antipsychotic medication. To address these concerns, I developed an online peak interval task. The peak interval task is a gold standard paradigm in which participants are instructed to learn, and reproduce, an unknown duration of time; analysis of trial-by-trial reproductions of this duration allows for the relative influence of internal clock, memory, and decision-making processes on temporal processing to be teased apart. In a series of studies, I tested the validity of this newly developed task and then tested the extent to which temporal processing deficits could predict psychosis-risk status in a non-clinical sample. In Experiment 1, 524 undergraduate students completed an online peak interval task in which they were asked to learn, and reproduce, two durations of time (6s and 20s) over multiple trials. Performance on this task was compared to that of 14 rats completing an analogous task. Data from humans broadly aligned with the general principles of interval timing, attesting to the validity of the paradigm. While the general pattern of performance was similar in rats and humans, there were some quantitative differences: the human sample was more accurate and precise than the rodents. This improved performance was related to a greater influence of memory and decision-making processes on performance. In Experiment 2, I recruited 61 individuals who were classified as at-risk for psychosis, had no formal psychotic disorder, and were not taking antipsychotic medications. The peak interval performance of these individuals was compared against 90 randomly selected controls. Timing accuracy and precision in reproducing the 6s duration predicted risk-group membership. Additionally, timing accuracy in reproducing the 6s duration explained significant variance in the presence of positive, and negative, schizotypal traits across the sample. These findings suggest that disruptions in temporal processing may be a risk marker for schizophrenia which may help illuminate illness mechanisms.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
EMPATHY ACROSS IDEOLOGICAL DIFFERENCE : A TRANSCRANIAL MAGNETIC STIMULATION STUDY OF THE RIGHT DORSOLATERAL PREFRONTAL CORTEX
No full textThesis (Ph.D.)--Michigan State University. Social Work - Doctor of Philosophy, 2025Despite being a resource-rich global power, the U.S. continues to grapple with deeply entrenched social issues, many exacerbated by deregulated, profit-driven media. Consolidation of media ownership and emotionally exploitative content has prioritized engagement over truth, fostering ideological echo chambers, moral outrage, and polarization. As identity increasingly fuses with ideology, these dynamics threaten collective problem-solving capacity, echoing Marcuse\u2019s (1964) warnings about the psychological impact of late capitalism. This dissertation introduces a transdisciplinary model of empathy, synthesizing existing theories and neural correlates, and reframing empathy as a perceptual process rather than a static trait or transient state with the aim of increasing the translational potential of empathy research. Using a quasi-experimental, sham-controlled design, this study investigates how low-frequency rTMS to the right dorsolateral prefrontal cortex (DLPFC) affects empathy-related behavior across ideological divides. While the right DLPFC is implicated in emotion regulation and executive function, its precise role remains contested, with inhibition linked to both improvements and impairments in social-emotional processing. Procedures: Participants (N = 37) completed trait empathy, ideology, acrimony, and wellness surveys before a 60-minute lab session. In lab, they received low-frequency (1 Hz) rTMS to either the right DLPFC (experimental) or vertex (sham), determined via alternating assignment. Before and after stimulation (600 pulses), participants completed a Stroop task and wellness survey. They then viewed a video simulation involving a person in need\u2014later revealed to have an opposing ideological stance\u2014and decided whether or not to help. Post-simulation measures included state empathy and acrimony. Results: There were no statistically significant group differences between experimental (n = 19) and sham (n = 18) conditions in change in willingness to help, state empathy, or acrimony. However, a moderate effect size (Cohen\u2019s d = .30) emerged for Stroop performance, with only the sham group showing expected post-stimulation improvements\u2014suggesting potential disruption of response inhibition in the experimental group. Similarly, a non-significant trend (Cohen\u2019s d = .49) showed decreasing acrimony in the sham group and a slight increase in the experimental group. These preliminary effects warrant further exploration. The strongest finding was that ideological difference significantly decreased willingness to help across all participants (Wilcoxon p < .001, r = \u2013.69), regardless of condition. Despite this decline, most participants still ultimately chose to help, suggesting some resilience to ideological bias in prosocial behavior. No significant differences were found on the basis of material security or trait empathy. However, trait empathy differed significantly by gender (Kruskal-Wallis p < .001, \u3b52 = .35), with higher scores among NB/trans*/another gender and female participants compared to males. Participants who selected \u201cgender\u201d as their core social issue also reported significantly higher trait empathy than those who selected \u201crace\u201d (p = .006, r = .65). No significant differences were found between moral vs. nonmoral motive groups across measures of empathy or helping behavior. A notable limitation was a statistically significant imbalance in handedness between groups (Fisher\u2019s Exact p = .043), which may have influenced results due to lateralization differences in DLPFC function. Conclusions: Ideological difference substantially reduced willingness to help, suggesting that polarization may influence everyday interpersonal interactions, not just political behavior. While no significant effects were observed from rTMS, emerging trends suggest right DLPFC inhibition may affect social-cognitive control and emotional reactivity. Future studies should explore lateralization and refine methodology to account for handedness and sample size limitations. This study highlights the need for interdisciplinary approaches to understanding empathy and for interventions that mitigate ideological division in both civic and interpersonal domains.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Tendering the Body
Get PDFThesis (Ph.D.)--Michigan State University. Curriculum, Instruction, and Teacher Education - Doctor of Philosophy, 2025This hybrid-genre manuscript is a critical creative examination of my own meditations with, of, and on my queer, ill body alongside teaching and teacher education. Throughout this manuscript, I posit and explore questions like: During a time where all people, but especially queer people, chronically ill and disabled people, and people of color are experiencing new waves of violence perpetrated against their bodies, their rights, and their bodily rights, how are we prioritizing care, caretaking, and connection? How are we finding and making tenderness for ourselves and one another? Academics, poets, and artists Ross Gay and Shayla Lawson asked a similar set of questions at a not dissimilar time, following the 2016 presidential election in the United States of America: what is tenderness? What does it take to make it (through/with) in America today? (London, Gay, & Lawson, 2019). Gay and Lawson came to The Tenderness Project because they observed a scarcity of writing both from and on softness and tenderness. Similarly, I have observed a scarcity around our own tendering of bodies in and around education spaces. Through research creation via essay and poetry and playwriting, I situate my relationship with tendering [and the lack thereof] with myself, my loved ones, my fellow artists and researchers and teachers, and my students. I ask us to return to the roots of tender\u2014to stretch, to hold forth (Rosado, 2018; Brewer, 2025a). I share my experiences with tendering, which poet and academic Michelle Brittan Rosado compares to poetry, identifying both as a celebration of the in-between. Through my engagement in research creation, a process of making and remaking my relationship with tendering, I seek to cultivate an invitation to (re)imagine (education) spaces where we don\u2019t need to leave ourselves at the door, to (re)imagine tendering interactions and tender offerings.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
PARENTAL STRATEGY FLEXIBILITY IN TODDLER FRUSTRATION CONTEXTS : GENDER DIFFERENCES AND OTHER CORRELATES
Get PDFThesis (M.S.)--Michigan State University. Human Development and Family Studies - Master of Science, 2025Emotional regulation skills are a critical piece of socioemotional development and are related to a host of positive life outcomes. However, boys face additional societal pressures to suppress or mask emotions, which can lead to emotional dysregulation and externalizing behaviors like aggression. Both emotional dysregulation and externalizing behaviors are linked to larger concerns, such as intimate partner violence. Despite extensive research on parental regulation strategies, a key piece of the development of emotion regulation, little is known about whether or how the strategies parents use to help manage their children\u2019s emotions vary by gender, especially in toddlerhood.This study explores the strategies that mothers and fathers use to help their toddlers manage their emotions and whether these strategies differ based on perceived child gender. The goals were to identify the types and frequencies of strategies used, if some strategies were used more frequently than others, and if so, which ones, and if gender differences in parental strategy use can be observed as early as toddlerhood. Participants included 166 primarily white, highly educated parents (83 mother-father pairs) and 112 mother-toddler pairs, who were videotaped and observed during a frustrating wait task. The results revealed that both mothers and fathers predominantly used Distraction to help their toddlers cope with frustration, accounting for 38% (SD = 0.28) of mothers' and 37% (SD = 0.16) of fathers' regulatory attempts. No significant differences in strategy use were found based on child gender (p = > .05). Although minor differences were observed, they were nonsignificant and of negligible effect size. These findings suggest that parental emotion regulation strategies are consistent across child gender in toddlerhood. However, gendered emotional norms may emerge later as children enter peer environments. Future research should explore how these strategies evolve as children grow, particularly during adolescence when boys may face more intense social pressures.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
CONDITIONS IN BLACK ASH STANDS AT VARYING STAGES OF EAB INVASION : VEGETATION, RADIAL GROWTH, AND CERAMBYCIDAE
Get PDFThesis (M.S.)--Michigan State University. Entomology - Master of Science, 2025This thesis, presented in four chapters, focuses on differences in forest vegetation, black ash (Fraxinus nigra) dendroecology across 24 black ash stands, and longhorn beetle (Coleoptera: Cerambycidae) species assemblages across eight stands, representing different stages of the emerald ash borer (EAB) (Agrilus planipennis Fairmaire) invasion referred to as: Post-, Mid-, and Pre-Invasion stands. Chapter one consists of a comprehensive assessment of forest vegetation across EAB Invasion Strata. Post-Invasion stands in the Lower Peninsula and eastern Upper Peninsula have experienced extensive overstory black ash mortality and Mid-Invasion stands have experienced some black ash mortality, while black ash in Pre-Invasion stands were predominately healthy. Black ash recruits (trees DBH 2.5-10 cm) in Post-Invasion stands exhibited high rates of mortality, and many recruits in Post- and Mid-Invasion stands were infested with EAB larvae. Chapter two focuses on the dendroecology of black ash overstory trees and recruits in 24 stands. Age of black ash recruits also varied but one recruit was 98 years old. In Post-Invasion stands, increases in annual ring width following overstory black ash mortality indicated release of black ash recruits. Chapter three examines cerambycid beetle species assemblages in eight black ash stands in Michigan\u2019s Upper Peninsula, in stands representing Mid and Pre-Invasion conditions. We recorded 43 new county records for 22 species of cerambycids and captured two species not previously reported from the Upper Peninsula. Finally, chapter four presents results from a 15-year common garden study in which survival and EAB infestations were tracked for four North American ash species: black ash, blue ash (Fraxinus quadrangulata), green ash (Fraxinus pennsylvanica), and white ash (Fraxinus americana), along with two Asian ash species: Chinese ash (Fraxinus chinensis) and Manchurian ash (Fraxinus mandshurica).Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
Iwasawa lambda Invariants, Massey products, and Pseudo-null Modules
No full textThesis (Ph.D.)--Michigan State University. Mathematics - Doctor of Philosophy, 2025The first chapter of this thesis serves as an introduction. The remaining two chapters each focus on different topics, all related to the theme of Iwasawa theory. These chapters are adapted from two separate papers, yet they form a coherent whole in the following sense.The second chapter studies the relation between Iwasawa -invariants and Massey products. For imaginary quadratic fields, Gold\u2019s criterion provides a connection between the Iwasawa -invariant of the cyclotomic -extension and cup products. Sands used this criterion to construct infinitely many imaginary quadratic fields with . Massey products can be viewed as a higher-order generalization of cup products. In Chapter 2, we generalize Gold\u2019s criterion by establishing a connection between the Iwasawa -invariant and Massey products. This generalization also recovers results of McCallum and Sharifi.In the third chapter, we study quotients of pseudo-null module. Let be an Iwasawa algebra and be a pseudo-null -module. Take a regular element in . We prove a criterion for determining when the quotient module is again pseudo-null over . This result provides a useful tool for reducing questions over -extensions to those over -extensions.Though the topics of two chapters seems unrelated, they all are motivated by studying the Gold's criterion. There are two main directions in which Gold\u2019s criterion can be generalized. The first is by replacing cup products with Massey products\u2014this is the focus of Chapter 2. The second is by considering -ramified -extensions instead of the classical cyclotomic -extensions. By the joint papers of Matt Stokes and the author, we find that the -ramified -extensions of CM field behaves similarly to the cyclotomic -extension of totally real field. For cyclotomic -extension of totally real fields, Greenberg conjectured that the Iwasawa module formed by the inverse limit of class group is a pseudo-null module. Hence, we need to consider the structure of pseudo-null module to better understand -ramified -extensions. We summarize the properties of -ramified -extensions before Chapter 3 to motivate the work done in Chapter 3. The summary is a reproduction of the joint research work by Matt Stokes and the author.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references