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Title: Statistical Methods for Single Cell Gene Expression : Differential Expression, Curve Estimation and Graphical Modelling
Creator: Saha, Satabdi
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation elucidates a set of statistical methods developed for analysis of single cellgene expression datasets. Gene expression profiling of single cells has led to unprecedented progress in understanding normal physiology, disease progression and developmental pro- cesses. However, despite many improvements in high throughput sequencing, various tech- nical factors including cell-cycle heterogeneity, library size differences, amplification bias, and low RNA capture per cell lead to...
Show moreThis dissertation elucidates a set of statistical methods developed for analysis of single cellgene expression datasets. Gene expression profiling of single cells has led to unprecedented progress in understanding normal physiology, disease progression and developmental pro- cesses. However, despite many improvements in high throughput sequencing, various tech- nical factors including cell-cycle heterogeneity, library size differences, amplification bias, and low RNA capture per cell lead to high noise in scRNA-seq experiments. A primary characteristic of these datasets is the presence of high number of zeroes which represents the undetectable level of expression for a transcript. Statistical methods capable of modelling novel single cell experiments are developed and new estimation strategies are proposed and validated using simulated and real data experiments. In Chapter 1, the motivation and underlying philosophies of single cell gene expression is reviewed. Methods for analysis of dose response experiments and gene co-expression networks are reviewed and novel statistical hypothesis to be investigated using single cell experiments are discussed. In Chapter 2, I analyze a unique in vivo dose response hepatic scRNAseq dataset con- sisting of 9 dose groups with 3 biological replicates for 11 distinct liver cell types for greater than 100K cells. A Hurdle model for multiple group data is proposed, which models the bimodality of single cell gene expression within multiple groups. Based on the model assumptions, I derive a fit for purpose Bayesian test for simultaneously testing the differences in mean gene expression and zero proportions for multiple dose groups. For comparison the counterpart likelihood-ratio test for differential expression that incorporates testing for both components is also derived. This chapter was originally published in [1]. In Chapter 3, dose response curve estimation for single cell experiments is studied. Cur- rent protocols for genomic dose response modelling are only capable of modelling bulk and microarray datasets. A semiparametric regression model for joint dose response curve estimation for multiple cell-types while accounting for confounding covariates is proposed. A novel, scalable and efficient optimization algorithm using the MM phi- losophy is proposed for the estimation of both monotone and non-monotone curves. Two relevant tests of hypothesis are discussed and the proposed methods are validated using several simulated datasets. In Chapter 4, co-expression network estimation is studied using graph signal processing. A kernelized signed graph learning approach is developed for learning single cell gene co-expression networks, based on the assumption of smoothness of gene expressions over activating edges. Performance is assessed using real human and mouse embryonic datasets. This chapter was originally published in [2].
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Title: Assessment of Operational and Safety Impacts of Various Traffic Control Devices
Creator: Megat Johari, Megat Usamah Bin
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Fatal crashes have been increasing, both in Michigan and across the United States, despite continuing improvements in roadway design, vehicle safety, and other areas. Various factors may have contributed to this trend, including increased in-vehicle distractions, higher speed limits, legalization of marijuana, and other factors. Studies have suggested that driver error is a critical reason associated with more than 90 percent of all traffic crashes. Driver behavior can be improved by several...
Show moreFatal crashes have been increasing, both in Michigan and across the United States, despite continuing improvements in roadway design, vehicle safety, and other areas. Various factors may have contributed to this trend, including increased in-vehicle distractions, higher speed limits, legalization of marijuana, and other factors. Studies have suggested that driver error is a critical reason associated with more than 90 percent of all traffic crashes. Driver behavior can be improved by several engineering strategies, such as the use of better and more efficient traffic control devices, such as signs, signals, and pavement markings. To that end, this research assesses the operational and safety impacts of a series of traffic control devices.The use of dynamic message signs (DMS) as a medium to display safety messages to drivers has become popular among transportation agencies. Despite their widespread use, evaluations as to the resultant impacts on traffic crashes have been very limited. This study addresses this gap in the extant literature and assesses the relationship between traffic crashes and the frequency with which various types of safety messages are displayed. A series of count models are estimated to examine total, speeding-related, and nighttime crashes based upon historical messaging data while controlling for other site-specific factors. Ultimately the results provide important insights regarding messaging strategies for transportation agencies. This research also evaluates driver response to advisory speed signs. Posted speed limit signs are used to inform drivers of the legal maximum allowable speed. In contrast, advisory speed signs provide recommendations to drivers as to safe travel speeds at specific roadway locations. Various studies have investigated the safety impacts of speed limit changes, particularly on high-speed rural highways. One area of particular concern on such roadways is the approach to exit ramps that require substantive speed reductions, such as loop ramps. To date, there has been limited research examining the safety impact of the differential between the mainline speed limit and the lower exit ramp advisory speeds. This study addresses this gap through the estimation of a series of safety performance functions. The findings from this study show the safety of these locations is related to speed differential, as well as other factors such as the length of the upstream deceleration lane. These factors should be considered when considering speed limit policy impacts in the vicinity of full and partial cloverleaf interchanges.Lastly, this study assesses the use of dynamic speed feedback sign (DSFS) as a means to reduce vehicle speeds in speed transition zones, where speeds are reduced as drivers enter rural communities. DSFS have been evaluated in several settings, including high-speed exit ramps and horizontal curves. However, research is limited as to the effectiveness of this sign for other purposes, such as these high-speed transition areas. This is particularly important as the limits on some of these roadways have recently been increased, making speed control a particular concern. This study addresses this gap through a before-and-after evaluation of DSFS at five different sites in northern Michigan. A series of speed models were estimated, which provide insights on the effectiveness of DSFS.
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Title: AN EXAMINATION OF EMPATHY AND SOCIAL OUTCOMES FOR INDIVIDUALS WITH INTELLECTUAL AND DEVELOPMENTAL DISABILITIES
Creator: Josol, Cynde Katherine
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Empathy is generally described as a multidimensional construct, consisting of cognitive and affective components. Researchers demonstrate that a better ability to understand and express empathy toward others is associated with positive social outcomes such as strong communication skills and meaningful social relationships. For individuals with intellectual and developmental disabilities (IDD), the understanding and expression of empathy and its various components can be challenging. However,...
Show moreEmpathy is generally described as a multidimensional construct, consisting of cognitive and affective components. Researchers demonstrate that a better ability to understand and express empathy toward others is associated with positive social outcomes such as strong communication skills and meaningful social relationships. For individuals with intellectual and developmental disabilities (IDD), the understanding and expression of empathy and its various components can be challenging. However, different etiologies can elucidate various strengths and weaknesses related to empathy. Given empathy’s critical role in various social domains and potential differences in empathy skills and social outcomes across different IDD groups, the purpose of this dissertation is to expand the current literature on empathy for three distinct and unique IDD groups to better inform current and future interventions.This dissertation consists of three independent, but related manuscripts presented in journal submission format. The first study was a systematic literature review of 169 studies conducted to identify the current research on empathy skills and social outcomes for individuals with autism spectrum disorder (ASD), Williams syndrome (WS), and Down syndrome (DS). Overall, the results of the systematic literature review indicate that individuals with ASD experience poorer empathy skills and these deficits relate to poor social skills. Further, there is a lack of research on empathy for other IDD conditions (e.g., WS and DS) and in relation to other social domains (e.g., social skills). As such, the second study examined the specific relationship of empathy and social skills for individuals with ASD, WS, and DS and examined for differences across groups and compared to a typically developing (TD) control group. The final sample (N = 120) included 30 students diagnosed with ASD (mean age = 10.73 years) and their caregivers, 30 students diagnosed with WS (mean age = 12.07 years) and their caregivers, 30 students with DS (mean age = 11.53 years) and their caregivers, and 30 TD students (mean age = 10.90 years) and their caregivers. Results demonstrate that, according to parent reports, students with ASD present with lower empathy skills compared to students with WS and DS and to students without disabilities. Differences between groups were also demonstrated regarding the relationship between empathy skills and social skills. More specifically, for students with WS, lower empathy skills were not significantly correlated with social motivation. The results of Chapter 3 highlight that differences in empathy and social skills should be accounted for in empathy-related interventions and underscore the importance of developing etiology-specific interventions. In response to the importance of developing interventions that account for the student’s disability, the third manuscript was written to guide special educators in addressing empathy skills for students with ASD. When assessing empathy skills, it is crucial that special educators obtain accounts from multiple informants including parent- and teacher-reports. The use of multiple sources will provide both a general picture of a student’s empathy skills along with information for specific areas of concern. Other general considerations for empathy assessment and intervention include incorporating elements of cognitive and affective empathy during assessment, adopting a developmental framework to guide both short term and long-term goals, and identifying additional social skills deficits to target prior to or during the empathy intervention, if applicable.
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Title: EXAMINING THE IMPACT OF SHAREHOLDER ACTIVISM ON THE TARGETED FIRMS’ TEMPORAL ORIENTATION AND RESOURCE DECISIONS
Creator: Lee, Jennifer
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Prior research on shareholder activism has expanded our knowledge on how activism affects firms, especially with respect to the types and magnitudes of activist-impelled changes. However, it remains unanswered how deeply activist intervention morphs the targeted firms and how long such changes persist. Focusing on the firm temporal orientation, I develop theory on how activism influences the targeted firm’s time horizon, both when attacked by activists and when activists leave the firm. I...
Show morePrior research on shareholder activism has expanded our knowledge on how activism affects firms, especially with respect to the types and magnitudes of activist-impelled changes. However, it remains unanswered how deeply activist intervention morphs the targeted firms and how long such changes persist. Focusing on the firm temporal orientation, I develop theory on how activism influences the targeted firm’s time horizon, both when attacked by activists and when activists leave the firm. I open the dissertation by reviewing the rapidly evolving research in shareholder activism. In my first empirical study, I examine how activist intervention shortens the targeted firm’s time horizon, and how the degree of shortening is contingent on the relative motivation and capability of activist investors vis-à-vis managers. In the second study, I propose that targeted firms shift their course of strategy once activist investors leave the firm, specifically by increasing their resource-consuming investments. Yet, because of the inherent temporal tradeoff such investments present, I posit that the degree of shift is likely affected by leader attributes and situational factors. Specifically, I argue that the CEOs who are high in their future temporal focus and who have a high level of prospective wealth will increase their resource-consuming investments to a greater degree. In addition to testing hypotheses, the empirical data revealed an unexpected insight into the time horizon changes in non-targeted firms. With my dissertation, I aim to contribute to streams of research on shareholder activism, firm temporal orientation, and corporate governance.
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Title: EVALUATION OF DRIVER RESPONSE TO SAFETY MESSAGES ON DYNAMIC MESSAGE SIGNS
Creator: Megat Johari, Nusayba Binti
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Between 2010 and 2020, many transportation agencies began displaying safety messages and crash facts to the traveling public using roadside dynamic message signs (DMS). The content of these messages varies from annual crash and fatality statistics to more detailed messages regarding specific driving behaviors or risk factors. Despite the widespread use of DMS for safety messaging purposes, evaluations of potential impacts on driver behavior and resultant impacts on traffic safety have been...
Show moreBetween 2010 and 2020, many transportation agencies began displaying safety messages and crash facts to the traveling public using roadside dynamic message signs (DMS). The content of these messages varies from annual crash and fatality statistics to more detailed messages regarding specific driving behaviors or risk factors. Despite the widespread use of DMS for safety messaging purposes, evaluations of potential impacts on driver behavior and resultant impacts on traffic safety have been limited. This research addresses this gap through a series of investigations to determine the degree to which the use of DMS for safety messages impacts various aspects of driver behavior. Driver behavior was examined in response to different DMS messages while considering critical contextual factors, such as the type of messages displayed, traffic flow conditions, and roadway geometric characteristics. The first set of field evaluations examined driver behavior as vehicles approached in-service emergency and MDOT service vehicles parked on the roadway shoulder in consideration of the state’s move-over law. Compliance was measured in terms of speed reduction and lane selection and comparisons were made based upon a series of targeted messages displayed on upstream DMS. Logistic regression models were estimated to assess driver compliance with the law while considering important contextual factors, such as the type of vehicle on the shoulder and the message displayed on the DMS. The results indicate that drivers were more likely to move over or reduce their speeds when a police car was parked on the shoulder as compared to a transportation agency pickup truck. In general, the type of message displayed had minimal impact on driver behavior. The one exception showed that drivers were less likely to exceed the speed limit when targeted move over messages were shown as compared to standard travel time messages. For all message types, both speed and lane compliance were improved if the roadside vehicle was a police car. The second study examined cell phone use rates in consideration of enforcement activities that were conducted in conjunction with the display of targeted safety messages on roadside DMS. The results showed that cell phone use rates were lower during and, particularly, after the enforcement activities were conducted. Use rates were also found to vary based on age, gender, and race, allowing for the identification of target groups for public awareness and outreach campaigns. Cell phone use rates were also lower at freeway exit ramps compared to signalized and stop-controlled surface street intersections. Furthermore, cell phone-specific safety messages were associated with lower use rates than other message types.Ultimately, the findings largely reinforce federal guidance on the use of DMS for secondary purposes, which include displaying road safety messages. As a stand-alone measure, DMS provide marginal impacts on driver behavior. Such messaging strategies are likely to be more effective when used as a part of active safety campaigns with a limited duration as compared to more frequent and continuous display of generic message types. The outcome of the field investigations also shows that combining targeted messaging with the presence of enforcement results in the most substantive improvements in driver behavior.
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Title: FIELD AND EXPERIMENTAL STUDIES FIND VARIATION IN LEVELS OF LARVAL LAKE STURGEON PREDATION IS ASSOCIATED WITH BEHAVIOR AND ENVIRONMENTAL CONDITIONS
Creator: Riedy, Joseph Jerry
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Species are vulnerable to predation during early in life stages, especially those who provide little or no parental care. Predation risk is further elevated during periods of migration when individuals are exposed to a greater abundance and diversity of predators. Levels of predation during migration are often variable and can be heavily influenced by environmental conditions and changes in behavior. It is important to understand how these factors influence predation rates of threatened and...
Show moreSpecies are vulnerable to predation during early in life stages, especially those who provide little or no parental care. Predation risk is further elevated during periods of migration when individuals are exposed to a greater abundance and diversity of predators. Levels of predation during migration are often variable and can be heavily influenced by environmental conditions and changes in behavior. It is important to understand how these factors influence predation rates of threatened and endangered species. Lake sturgeon are an imperiled species native to the Great Lakes, Mississippi River, and Hudson Bay drainages that undergo a downstream from spawning grounds to nursery habitat at the beginning of the larval stage. This migration begins at night and larvae are exposed to several known predator species as they migrate the length of the spawning river in event. In this dissertation, I examine influences of ecological factors and behavior on levels of predation during the downstream migration. In Chapters 1 and 2, I used mesocosm experiments to determine the effects of night light level, rearing temperature, and prey abundance on survival during migration. Survival is highest during the environmental conditions present early in the season: new moon light levels, colder rearing conditions, and when prey abundance is high. In Chapters 3 and 4, I returned to the mesocosms to examine the survival implications of the behavioral responses to alarm cues during the larval stage. Lake sturgeon larvae exposed to a predator species odor and lake sturgeon alarm cue have higher survival rates when later exposed to the predator species. Additionally, lake sturgeon can use alarm cues from unrelated allopatric and sympatric species as kairomones similarly to conspecific alarm cues. In Chapter 5, I collected lake sturgeon larvae and predator diets from a natural lake sturgeon spawning stream to estimate nightly mortality rates, identify the predatory species that consumed, and determine the environmental factors that influence lake sturgeon mortality in a wild population. Survival rates varied greatly, but on average, approximately one third of lake sturgeon larvae survived the section of the river sampled. Additionally, roughly one third of all potential predator diets sampled contained lake sturgeon. Similar to previous chapters, light level and the abundance of prey had the greatest influence on the survival rates of lake sturgeon and the probability of detecting lake sturgeon in the diets of potential predators. Results indicate the timing of lake sturgeon spawning influences larval survival by determining the ecological conditions present during offspring development and downstream migration. Work presented here identifies the factors with the strongest influence on larval lake sturgeon survival. Though variation in larval lake sturgeon mortality is high, managers may begin to use these factors to forecast larval lake sturgeon survival rates in populations. It will be important to monitor changes to these ecological variables, such as fluctuations in co-distributed fish and invertebrate populations, and variation in water temperatures during development, because these factors have strong and predictable influences lake sturgeon recruitment rates.
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Title: THE EFFECT OF SALES TAXES ON LOCATION DECISIONS AND CAPITAL MARKET OUTCOMES : EVIDENCE FROM WAYFAIR
Creator: Shaw, Joanna
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This study examines how investors, analysts, and firms respond to changes in sales tax obligations for e-commerce firms. Previous research finds that e-retailers have a competitive advantage over their brick-and-mortar counterparts due to their ability to avoid collecting sales taxes. Using the Supreme Court of the United States (The Court) decision in South Dakota v. Wayfair, Inc., 585 U.S.__ (2011) (Wayfair) as a setting, I examine investor and analyst reactions to, and corporate location...
Show moreThis study examines how investors, analysts, and firms respond to changes in sales tax obligations for e-commerce firms. Previous research finds that e-retailers have a competitive advantage over their brick-and-mortar counterparts due to their ability to avoid collecting sales taxes. Using the Supreme Court of the United States (The Court) decision in South Dakota v. Wayfair, Inc., 585 U.S.__ (2011) (Wayfair) as a setting, I examine investor and analyst reactions to, and corporate location decisions following, the broadening of state nexus rules for interstate commerce. I find that investors and analysts responded negatively to the announcement that The Court would hear the Wayfair case and to the release of the ruling, as evidenced by negative mean cumulative abnormal returns and downward revenue forecast revisions, respectively. These results are consistent with capital market participants perceiving increased sales tax obligations as being detrimental to e-commerce firms. Next, I investigate how e-commerce firms respond to increased sales tax obligations by examining their location decision-making in the wake of Wayfair. I find that e-commerce firms are more likely to establish locations in new states with sales taxes after Wayfair. In cross-sectional analysis, I find that my results are primarily driven by retail, wholesale, and service firms. I also find evidence that e-commerce firms are more likely to establish locations in states with high populations after Wayfair.
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Title: BUSINESS RESPONSES TO SUPPLY CHAIN DYNAMICS : IMPLICATIONS FOR SOURCING AND PUBLIC POLICY
Creator: Yan, Zhenzhen
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation studies drivers and consequences of firms' policy decisions from a supply chain perspective. Policy decisions can be both internal and external to the firms and carry substantial implications for firms’ performance outcomes. Both internal and external aspects of policy engagement are critical since they help further disciplinary understanding of not only how policy decisions influence the performance of products firms manufacture, but also the fact that firms can reshape...
Show moreThis dissertation studies drivers and consequences of firms' policy decisions from a supply chain perspective. Policy decisions can be both internal and external to the firms and carry substantial implications for firms’ performance outcomes. Both internal and external aspects of policy engagement are critical since they help further disciplinary understanding of not only how policy decisions influence the performance of products firms manufacture, but also the fact that firms can reshape their environmental conditions through adopting policy decisions to engage with regulators and impact their own business practices. Specifically, I investigate firms' sourcing policies and their product performance implications – an internal policy set by firms. Within the context of external policy engagement, my research investigates firms' policy responses to external conditions, such as climate change public policies.The first essay focuses on manufacturing localization, an internal policy set by automakers to relocate manufacturing activities closer to their target market. I apply a causal estimation method to 23-year panel data of the automotive industry complied from diverse data sources including Wards, National Highway and Traffic Safety Authority (NHTSA) recall data to investigate the quality implications of manufacturing localization. The results show an immediate quality decline for localized vehicles, indicated by an increase of 68.203% in the number of recalls (equivalent to 0.552 more recall campaigns) and an increase of customer complaints by 56.831% (equivalent to 9.997 more complaints) in the three years after the manufacturing localization. The increased number of recalls can lead to an extra expense of $2.76 million for a localized vehicle based on conservative estimations. A cautionary note is thus issued for automakers to adjust their planned budgets to account for warranty claims before the localization. This study provides guidance for firms considering the relocation of their manufacturing activities and for regulators that seek to reduce vehicle recalls. The second and third essays of my dissertation investigate firms’ engagement in influencing climate change policies (EICCP), which refers to firms’ strategic actions to influence climate change policymaking processes, aiming at reshaping policies or promoting policy changes in favor of their interests. In the second essay, I conceptualize EICCP and propose a taxonomy for EICCP strategies considering firms’ perceptions of external conditions and internal resources. I also create measures for EICCP to empirically validate this taxonomy by performing text analytics with machine-learning techniques on firms’ self-disclosure in CDP Climate Change data. Building on the second essay, I undertake a large-scale empirical analysis to investigate antecedents of EICCP in the third essay. Specifically, I examine the regulatory risks associated with climate change and firms’ supply network complexity as critical and interrelated factors for firms’ EICCP. The latter two essays contribute to the growing literature on climate change and firm responses. Overall, my thesis responds to the call for policy-related studies in the supply chain field and provides insights for policy decision-makers.
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Title: Evaluation of Operational and Safety Impacts of Part-Time Use of The Inside Shoulder
Creator: Cai, Qiuqi
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The Michigan Department of Transportation (MDOT) introduced its first application of dynamic part-time shoulder use (D-PTSU) on the US-23 corridor in November 2017 to mitigate recurring congestion. This project referred to as the Flex route involved widening the left shoulder, which now serves as a temporary travel lane during between M-14 and M-36 during periods of heavy congestion. As the application of D-PTSU is relatively novel in the United States, especially the use of the left shoulder...
Show moreThe Michigan Department of Transportation (MDOT) introduced its first application of dynamic part-time shoulder use (D-PTSU) on the US-23 corridor in November 2017 to mitigate recurring congestion. This project referred to as the Flex route involved widening the left shoulder, which now serves as a temporary travel lane during between M-14 and M-36 during periods of heavy congestion. As the application of D-PTSU is relatively novel in the United States, especially the use of the left shoulder, this study evaluates the operational and safety performance of the US-23 Flex route and provides guidance for future implementation of similar facilities in Michigan and elsewhere. The evaluation assessed various metrics, including average travel time, travel time reliability, driver compliance, and incident clearance times. The findings show that operations of the US-23 Flex route have improved significantly, especially in the southbound direction. While the northbound direction also showed better performance after the Flex lane opened in general, some of the prior congestion has shifted to the end of the Flex route in the northbound direction due to a bottleneck that was introduced at the end terminal. Fortunately, this problem is expected to be alleviated by the planned extension of the Flex lane to I-96 in 2024. The operational analyses also showed improved operations when special events occurred, such as football games and holidays. Incident clearance times largely decreased after the Flex route was opened. Part-time shoulder running also provided an additional travel lane during peak periods, such as University of Michigan home football games, reducing such non-recurrent congestion. Crash data were compared for a period of five years (i.e., 2012 to 2016) before the construction of the Flex route, and two years (i.e., 2018 and 2019) after its completion. After considering increases in traffic volume, crashes were reduced by 17 percent when considering all times of day, including 34 percent in the southbound direction. During the peak operational periods, reductions of approximately 50 percent were experienced in the southbound direction. In contrast, total crashes were comparable in the northbound direction and actually increased by approximately 24 percent during the peak traffic periods. However, much of this increase is attributable to the lane drop that occurs at the northern terminus of the Flex route. The planned extension to I-96 should remedy the existing safety issues.
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Title: A SEPARATION : WATERWAYS, LOGISTICS, AND THE MAKING OF THE USSR’S NORTHEAST ASIAN BORDERLANDS, 1920S-1940S
Creator: ZHANG, LIAO
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation examines the socioeconomic transformation of the middle and lower Amur River Basin in the first half of the 20th century. Through the lenses of social, spatial, and biographical history, this project addresses the following questions: how the Amur River Basin, once a coherent geographic unit, was socioeconomically carved up along national lines; and how the left bank of the middle Amur River became an inward-looking Soviet borderland that resembled many other Soviet...
Show moreThis dissertation examines the socioeconomic transformation of the middle and lower Amur River Basin in the first half of the 20th century. Through the lenses of social, spatial, and biographical history, this project addresses the following questions: how the Amur River Basin, once a coherent geographic unit, was socioeconomically carved up along national lines; and how the left bank of the middle Amur River became an inward-looking Soviet borderland that resembled many other Soviet heartlands. I discuss this process, by which the Amur River became a hardened, highly politicized international border, through reconstructing biographies of five middle Amur River-centered, interconnected social and economic institutions: an inland shipping company, a cohort of hydrological scientists and engineers, a trans-border brewery, the local establishment of the Soviet customs service, and the state agency for social welfare. This dissertation reveals that the history of everyday socioeconomic institutions was central to understanding the Soviet state and local communities’ participation in distinctively transforming the built environment, the mode of logistics, supply chains, and consequently the human-environment relationship of the left bank in the name of realizing local and All-Union economic self-sufficiency. Underlying the state-led pursuit of socioeconomic self-sufficiency is the Soviet Union’s fascination with legibility in statecraft and socioeconomic reorientation, substantiating the socialist regime’s very modern nature.
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Title: Analyzing Synergistic Effects of Combined Aging Environments on Polymer Degradation : Micro-mechanical Modeling of Loss of Performance
Creator: Mohammadi, Hamid
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Materials’ properties play a crucial role in the selection of processes or design for manufacturingsystem components. These components should have high resistance to multiple stress factors such as mechanical and environmental stresses in which the component is being used. For this reason, engineers should analyze all possible scenarios and try to model for combined environment conditions before introducing a product to the market.Polymers are specific materials with significantly high...
Show moreMaterials’ properties play a crucial role in the selection of processes or design for manufacturingsystem components. These components should have high resistance to multiple stress factors such as mechanical and environmental stresses in which the component is being used. For this reason, engineers should analyze all possible scenarios and try to model for combined environment conditions before introducing a product to the market.Polymers are specific materials with significantly high durability and resilience due to theirloosely cross-linked polymer matrix made by long interconnected polymer chains. Due to these excellent properties, they are among the most frequently used materials in load-transfer applications in adhesives, joints, sealing, bumpers, coatings, and protection shields. Due to the increasing use of composite materials in the industry, polymers’ usage, especially in polymeric adhesive, drastically increased. Since polymeric adhesives are used to join dissimilar material interfaces. However, degradation of polymeric adhesives is a menace to joints.Degradation or aging defined as the loss of properties due to environmental condition. Agingis an irreversible process that changes the network topology of the material. Polymeric adhesives are susceptible to degradation which makes them a critical part with extreme sensitivity to temperature, moisture, and sunlight. Degradation-induced failure occurs due to damage accumulated from mechanical sources and the loss of properties due to aging which cause a premature failure in system. Therefore, reliability of a system can be greatly compromised due to this degradation induced failure. Consequently, polymeric adhesives are a significant challenge for design reliability of multi-material systems. Reliable theoretical models to predict the degradation-induced failure in polymeric adhesives can substantially reduce the cost and enhance the reliability of adhesive bonding.Current approach in Original Equipment Manufacturers (OEM) companies is to use experimentalapproaches to predict the failure. However, laboratory conditions omit many factors that are present in real-time and might not paint a clear picture of the mechanisms of failure. Most importantly, the time and cost needed for these tests are substantially high. To this end, developing a comprehensive software that would be able to model the real-time conditions of aging seems of great value.This dissertation objective is to provide micro-mechanical constitutive models that would beable to model damage accumulation in polymers and polymeric adhesives during combined aging environments. These constitutive models provide the necessary modules to build a platform for creating a Finite Element Method (FEM) based model for a 3D modeling of polymers in combined environmental aging condition under mechanical stresses. To this end, the project followed four main steps namely, (I) performing accelerated aging tests, (II) analyzing the tests result to understand the underlying aging phenomena, (III) developing degradation model, (IV) validating the proposed model versus the experimental data. After successfully finishing these steps, the necessary modules to start creating an FEM platform would be ready which should be the next step for this project.To go in further detail, this project successfully delivered five major tasks that has been definedas the necessary steps for developing the platform. These steps are as follows, (I) providing a model for thermo-oxidative aging of polymers, (II) understanding the effects of decay functions on modeling properties of aging, (III) developing a model for a combined thermo- and photo-oxidative aging, (IV) developing a model that can successfully consider accumulated damage during combined aging, (V) developing a model for cyclic environmental conditions. All of these models are the first ones in the literature that being developed which suggests great novelty and value that this work can bring to the industry. The model proposed in this work can significantly enhance the design process by allowing pre-selection of materials and product geometries with respect to the expected mechanical and environmental loading. Such process will allow agile design evaluation.
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Title: NETWORK-WIDE CHARGING INFRASTRUCTURE PLANNING AND MARKET SHARE ANALYSIS FOR ELECTRIC VEHICLES
Creator: Kavianipour, Mohammadreza
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Electric vehicles (EVs) are widely considered a sustainable substitution to conventional vehicles to mitigate fossil fuel dependence and reduce tail-pipe emissions. However, limited ranges, long charging times, and lack of charging infrastructure have hindered EV’s market acceptance. This calls for more investments in building charging stations and advancing battery and charging technologies to obviate issues associated with EVs and increase their market share and improve sustainability. This...
Show moreElectric vehicles (EVs) are widely considered a sustainable substitution to conventional vehicles to mitigate fossil fuel dependence and reduce tail-pipe emissions. However, limited ranges, long charging times, and lack of charging infrastructure have hindered EV’s market acceptance. This calls for more investments in building charging stations and advancing battery and charging technologies to obviate issues associated with EVs and increase their market share and improve sustainability. This study introduces modeling frameworks to optimize fast-charging infrastructure locations at the network level to address the challenges associated with EVs. Furthermore, it investigates the required charging investments for the current and future EV market shares, technology advancements, and seasonal demand variations. First, this study seeks an optimal configuration for plug-in electric vehicle charging infrastructure that supports their long-distance intercity trips at the network level. A mathematical optimization model is proposed which minimizes the total system cost and considers the range anxiety, multiple refueling, maximum capacity, charging delay, and detour time. This study considers the impacts of charging station locations on the traffic assignment problem with a mixed fleet of electric and conventional vehicles considering a user equilibrium framework. This study fills existing gaps in the literature by capturing realistic patterns of travel demand and considering flow-dependent charging delays at charging stations in intercity networks. Then, the study focuses on Michigan and its future needs to support the intercity trips of EVs across the state in two target years of 2020 and 2030, considering monthly traffic demand and battery performance variations, as well as different battery sizes and charger technologies, the main contributing factors in defining the infrastructure needs of EV users, particularly in states with adverse weather conditions. This study incorporates the developed intercity model to suggest the optimal locations of EV fast chargers to be implemented in Michigan. Next, this study introduces an integrated framework for urban fast-charging infrastructure to address the range anxiety issue in urban networks. Unlike intercity trips that start with fully charged batteries, urban trips might start with any state of charge because of home/work chargers' unavailability, being part of a trip chain, and forgetting to charge overnight. A mesoscopic simulation tool is incorporated to generate trip trajectories, and a state-of-the-art tool is developed to simulate charging behavior based on various trip attributes for these trajectories. The resulting temporal charging demand is the key element in finding the optimum charging infrastructure. The solution quality and significant superiority in the computational efficiency of the decomposition approach are confirmed in comparison with the implicit enumeration approach. Finally, this study generates forecasting models to estimate the number of chargers and charging stations to support the EV charging demand for urban areas. These models provide macro-level estimates of the required infrastructure investment in urban areas, which can be easily implemented by policy-makers and city planners. This study incorporates data obtained from applying a disaggregate optimization-based charger placement model, for multiple case studies to generate the required data to calibrate the macro-level models, in the state of Michigan.
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Title: THREE ESSAYS ON RISK MANAGEMENT AND IRRIGATION WATER DEMAND IN AGRICULTURE
Creator: Lu, Pin
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Both extensive (share of insured acres in total insurable acres) and intensive (coverage level choice) margin participation rates in the U.S. crop insurance program have increased due to generous subsidies. On a national scale, this program has been well rated to satisfy the actuarial fairness requirement by USDA Risk Management Agency. However, sizeable spatial heterogeneity remains across the Great Plains and Corn Belt regions. If subsidies were to be reduced in the future because of...
Show moreBoth extensive (share of insured acres in total insurable acres) and intensive (coverage level choice) margin participation rates in the U.S. crop insurance program have increased due to generous subsidies. On a national scale, this program has been well rated to satisfy the actuarial fairness requirement by USDA Risk Management Agency. However, sizeable spatial heterogeneity remains across the Great Plains and Corn Belt regions. If subsidies were to be reduced in the future because of financial constraints, such heterogeneity might be detrimental to the sustainability of the crop insurance program. A central theme of this dissertation is to investigate how farmers make participation decisions when risk factors exist. In a separate but related line of work, this dissertation also explores the irrigation water usage in the Great Lakes region because farmers' irrigation behavior reflects their risk preferences and impacts their incentives for enrolling in the program. The dissertation consists of three essays on farmers' decisions regarding premium mispricing, basis risk, and irrigation water usage. The first essay proposes a novel resampling procedure to estimate farm-level actuarially fair premiums. The resampling procedure mainly contains two parts: (i) semi-parametric quantile regression; and (ii) rejection method. Many previous studies explore whether county-level mispricing exists based on the historical loss ratio records. However, we can identify farm-level mispricing by imputing actuarially fair premiums based on historical yield records, consistent with theory. We find that farmers with lower land quality cropland paid fewer premiums than they should, but a contrary case happens for farmers with higher land quality cropland. Empirical evidence shows farmers may be more concerned about mispricing than subsidy transfer. Regression results support a conclusion that such farm-level mispricing deters farmers’ crop insurance demand. Our analysis sheds light on the policy-making that: (i) mispricing may be a substitution of subsidy so mitigating mispricing can maintain high participation while saving subsidies; and (ii) imputation of premiums based on historical yield records can apply. The second essay focuses on the impact of basis risk on participation rates in the U.S. crop insurance program. In recent years, basis risk has been increasingly recognized as an essential driver for deterring insurance uptake. Most research concentrates on index insurance contracts; however, few investigate the effect of mismatch between cash and futures markets on farmers’ insurance decisions. We first build a conceptual model to show farmers’ acreage response to basis risk within the expected utility framework. Next, we apply the Fractional Probit with Control Function for the empirical analysis and find that the effects of basis risk on participation rates are significantly negative for nearly all insurance contracts. Our analysis implies that: (i) to remove basis risk, revision for revenue contract may be considered; (ii) subsidy structure may be adjusted to be consistent with the underlying basis risk. The third essay investigates irrigation water usage in the Great Lakes region. Although the water conservation policy was implemented, there has been an upward trend in irrigation water demand from 2003 to 2018, including irrigated acres and total water usage. We employ firm-level irrigation data to examine what factors impact farmers' response to irrigation water usage. We find that: (i) price elasticities vary significantly according to model specifications and water costs; (ii) demand at both extensive (irrigated acres) and intensive (water application per acre) margins is input price inelastic; and (iii) price elasticities are homogeneous across crops but heterogeneous across states. For the policy-making, if there is a 10% tax on irrigation water cost, total water usage decreases by about 4% for corn and soybean, respectively.
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Title: An exploration of selected relationships between insufficient and poor-quality sleep and dietary intake
Creator: Du, Chen
Date: 2022
Collection: Electronic Theses & Dissertations
Description: One in three adults in the U.S. and globally suffers from insufficient sleep and/or poor sleep quality, which are associated with poor health outcomes, including all top 10 leading causes of death. Sleep affects health outcomes, in part, by directly and indirectly influencing undesirable dietary behaviors, which, in this work, is defined as frequent consumption of foods that are inconsistent with health. For example, insufficient sleep leads to more frequent consumption of sweets, a direct...
Show moreOne in three adults in the U.S. and globally suffers from insufficient sleep and/or poor sleep quality, which are associated with poor health outcomes, including all top 10 leading causes of death. Sleep affects health outcomes, in part, by directly and indirectly influencing undesirable dietary behaviors, which, in this work, is defined as frequent consumption of foods that are inconsistent with health. For example, insufficient sleep leads to more frequent consumption of sweets, a direct effect, and stress negatively influences sleep where insufficient and poor-quality sleep can lead to unhealthy dietary behaviors, and indirect effect. Additionally, sleep influences taste measures, such as sweet taste preference; therefore, sleep may also alter dietary intake through changes in taste preference. Singular relationships between sleep, stress, taste measures, and undesirable dietary behaviors and dietary intake have been investigated; however, more complex relationships between these measures have yet to be explored. Therefore, the overall objective of this research was to explore relationships between sleep and undesirable dietary behaviors in a more holistic manner. This was achieved by investigating the role of sleep in the relationship between stress and dietary behavior as well its influence on taste measures and dietary intake relationships.Chapter 2 characterizes and compares health behaviors of higher education students from seven different countries during the COVID-19 pandemic and investigates the effects of changes in sleep duration and quality on dietary risk, alcohol misuse, physical activity, and sitting time. A total of 2,254 students completed the study. Health behaviors were consistent across countries, and students from all countries reported poor sleep quality. Additionally, students who experienced a decline in sleep quality during the COVID-19 pandemic had higher dietary risk scores than students who did not experience a change in sleep quality (p=0.001). Improved sleep quality was associated with less sitting time (p=0.010). The chapter reveals the pressing concern of poor sleep quality that students in higher education were experiencing, and worsened sleep quality was associated with more frequent engagement in unhealthy dietary behaviors. Therefore, addressing poor sleep quality among higher education student is urgent. After investigating how changes in sleep predicted dietary risk, alcohol misuse, physical activity, and sitting time, chapter 3 considers mental health measures and explores more complex relationships between stress, sleep, resilience, undesirable dietary behaviors, and alcohol misuse. This study investigates whether sleep duration and quality mediated and resilience moderated the relationships between stress and undesirable dietary behaviors and the relationship between stress and alcohol misuse. A total of 2,254 students from seven countries completed the study. Results indicated sleep quality, but not sleep duration, mediated the relationship between perceived stress and undesirable dietary behaviors as well as the relationship between perceived stress and alcohol misuse. Further, increased resilience reduced the strength of the relationship between perceived stress and undesirable dietary behaviors but not alcohol misuse. Therefore, chapter 3 demonstrates that students in higher education are likely to benefit from sleep education and resilience trainings, especially during a stressful period. Chapter 4 presents two studies, one methodological and one experimental. The methodological study examined whether a standardized tool used in evaluating sweet taste preference could be used in determining salt taste preference, and the experimental study used the new tool to investigate the effects of sleep curtailment on salt taste measures and explored the relationship between salt taste measures and dietary intake under the habitual and the curtailed sleep conditions. A total of 59 participants completed the study and slept one curtailed night (33% sleep duration reduction) and one habitual night in random order wearing a single-channel electroencephalograph (EEG). Results illustrated the adapted forced-choice paired-comparison tracking test can serve as a valid tool for determining salt taste preference. No changes in salt taste function (slopes of intensity ratings: p=0.844) and hedonic measures (slopes of liking ratings: p=0.074; preferred NaCl concentrations: p=0.092) were observed after a night of curtailed sleep compared to habitual sleep (study 2). However, the slope of liking was associated with energy-corrected Na intake only under the habitual sleep condition (p<0.001). These results suggest that the adapted forced-choice paired-comparison tracking test can be adopted as a tool to assess salt taste preference, and sleep should be accounted for when performing taste studies. In summary, the work presented in this dissertation explores the relationship between sleep and dietary intake in a complex manner. The results reveal 1) poor sleep quality among higher education students is a pressing concern, especially during the COVID-19 pandemic; 2) decline in sleep quality is associated with higher dietary risk, and improvement in sleep quality is associated with less sitting time; 3) sleep quality, but not sleep duration, mediated the relationship between perceived stress and undesirable dietary behaviors and the relationship between perceived stress and alcohol misuse; 4) acute sleep curtailment does not affect salt taste function or hedonic measures; 5) the slope of salt taste liking was associated with energy-corrected Na intake only under the habitual sleep condition. Overall, the work demonstrates the importance of improving sleep, which could reduce dietary risks, alcohol misuse, and sitting time, and the significance of accounting for sleep in taste studies.
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Title: PATTERN AND PROCESS OF TREE REGENERATION AND RECRUITMENT IN MANAGED NORTHERN HARDWOOD FORESTS
Creator: Henry, Catherine Rose
Date: 2022
Collection: Electronic Theses & Dissertations
Description: For managed forests which rely on natural tree regeneration for canopy recruitment, abundance and composition of tree regeneration portend future forest structure and diversity. For northern hardwood forests, a geographically widespread forest type in North America, typical single-tree selection (STS) management relies on natural regeneration to promote new cohorts of canopy trees. Harvesting dispersed, select trees every 15 – 20 years, STS generates low light levels intended to promote sugar...
Show moreFor managed forests which rely on natural tree regeneration for canopy recruitment, abundance and composition of tree regeneration portend future forest structure and diversity. For northern hardwood forests, a geographically widespread forest type in North America, typical single-tree selection (STS) management relies on natural regeneration to promote new cohorts of canopy trees. Harvesting dispersed, select trees every 15 – 20 years, STS generates low light levels intended to promote sugar maple (Acer saccharum) and other shade-tolerant tree species in an uneven-aged system. However, following 60 + years of STS implementation in the Great Lakes region, concerning regeneration trends have emerged, namely low densities of sugar maple and low tree species diversity. Additionally, few studies have analyzed age structure under this system to assess its past efficacy in generating uneven-aged forests. The research presented here characterizes regeneration and recruitment outcomes of STS, analyzing data from a uniquely detailed and geographically widespread research project of 141 northern hardwood stands across northern Michigan. Given the silvicultural focus on regenerating sugar maple, the first two chapters focus on management outcomes for this key species. First, a flexible Bayesian hierarchical model offers insight on patterns of sugar maple regeneration for key size classes as a function of plot and stand level predictors. Our results indicate that sugar maple regeneration is sparse to absent, particularly for size classes actively browsed by deer and recently escaped from the deer browsing zone. The second analysis characterizes age structure for a subset of 51 stands, drawing on 1499 sugar maple trees > 5 cm diameter sampled via basal discs from recently harvested stumps; this analysis provides insight to past patterns of recruitment and establishment. The results suggest little evidence of sugar maple seedling regeneration and canopy ingrowth over the past 60 + years of STS management; instead, stands have highly suppressed saplings plus aging poletimber and sawtimber classes, which are at or quickly approaching economic maturity. Given declines in sugar maple dominance as evidenced by the first two research analyses, the third analysis assesses stand-level tree species diversity and individual species abundance as a function of landscape predictors and size class to shed light on projected future canopy composition. On average, there are approximately three effective common species for seedlings, saplings, and canopy stems at the stand level, and species less desirable for management are occupying growing space in the sapling layer. Together, these results indicate that STS has been unsuccessful in regenerating or recruiting sugar maple over the past 60 + years, and stands are characterized by a paucity of tree species. Our results support several potential alternative management strategies, including decreasing basal area via more intense harvests, prohibiting deer browsing via natural browsing barriers, or introducing greater diversity of tree species via direct seeding or planting. These results should be considered to improve current management of northern hardwood forests in the Great Lakes region.
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Title: ENGINEERING STUDIES IN ADVANCED PLA MATERIALS – STEREOCHEMISTRY, STEREOCOMPLEXATION, AND THERMAL RECYCLING OF PLA
Creator: Alhaj, Mohammed A.
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Polylactide (PLA) polymers are the world’s foremost 100% biobased resin with both composting and recycling end-of-life options in harmony with Ellen MacArthur Foundation “Circularity Model.” It is commercially manufactured by converting lactic acid to lactide, which is then polymerized to PLA. These molecules present unique and intriguing stereochemistry that dictate manufacturing, performance properties, and processability. However, it is seldom discussed and not well understood in the role...
Show morePolylactide (PLA) polymers are the world’s foremost 100% biobased resin with both composting and recycling end-of-life options in harmony with Ellen MacArthur Foundation “Circularity Model.” It is commercially manufactured by converting lactic acid to lactide, which is then polymerized to PLA. These molecules present unique and intriguing stereochemistry that dictate manufacturing, performance properties, and processability. However, it is seldom discussed and not well understood in the role stereochemistry can play and impact product performance and use. In the current work, we critically review and discuss the stereochemical implications for PLA through studies on different PLA compositions.To-date, it is unclear the origin of D-content present in commercial grade PLA, although it is assumed to originate from D-lactide. In this work, we validate that manufacture of lactide monomer from (L)- lactic acid predominantly results in a mixture of L and meso (DL), not L- and D- lactide. Optical rotation and 1H NMR studies are used to elucidate this stereochemistry. Copolymers of L-lactide and meso-lactide and copolymers of L-lactide and D-lactide are synthesized via bulk polymerization at various compositions. The optical rotation, tacticity, crystallinity, and thermal properties of synthesized copolymers are characterized. The optical rotation of poly(meso-lactide) has also been reported for the first time in this text. Differential scanning calorimetry (DSC) and 1H NMR studies confirm that PLA transitions from a predominantly isotactic, semi-crystalline polymer to a predominantly atactic, amorphous polymer when one copolymerizes greater than 10% meso-lactide with L-lactide. The stereochemical composition, mechanical and rheological properties of commercial grade PLA are measured to elucidate the effect of stereochemistry on the tensile and rheological behavior of PLA. We conclude this section with studies on PLA stereochemistry and its influence on immune cellular response. Hydrolytic degradation of semi-crystalline and amorphous PLA is analyzed via molecular weight characterization and lactic acid abundance. Semi-crystalline and amorphous PLA are then studied as potential carriers for glycolytic inhibitors. The stereochemistry of PLA and its implication on performance properties are further explored in studies on stereocomplex PLA. A pilot-scale continuous manufacturing process of stereocomplex PLA is developed and optimized by melt-blending a 1:1 blend of high molecular weight poly(L-lactide) (PLLA) and high molecular weight poly(D-lactide) (PDLA) in a co-rotating twin screw extruder. Stereocomplexation is first characterized via DSC at different temperatures and times. The optimal reaction temperature and reaction time are found and used to process >95% stereocomplex PLA conversion (melting peak temperature Tpm = 240°C). Stereocomplex PLA is used as an additive to produce 70% PLLA/30% stereocomplex PLA composites. The crystallinity, thermal properties, and tensile properties of composites are then characterized. A study on stereocomplex PLA and its effect on the crystallization kinetics of PLLA is conducted. 5% stereocomplex PLA is blended with 95% PLLA to analyze its use as a nucleating agent. The final section discusses a pilot-scale end-of-life method for PLA via thermal recycling. This study continues previous studies on PLA thermodepolymerization by scaling up the reversible reaction in a pilot-scale batch reactor. PLA is run at various temperatures and times to elucidate the processing conditions that yield the highest lactide conversion. The chemical purity, optical purity, lactide yield and stereoisomeric composition of the final lactide product are characterized by DSC, optical rotation, mass balance, and 1H NMR, respectively.
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Title: A Longitudinal Analysis of Black Women's Experiences with a Domestic Violence Housing First (DVHF) Intervention
Creator: Ayeni, Oluwafunmilayo Oyesola
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Black women are at an increased risk for intimate partner violence (IPV). The complex interrelationships among housing instability, risk, and severity of abuse among IPV survivors has been established in the research literature, particularly for Black women who are often standing at the intersection of poverty, race, and gender, which results in having fewer financial resources and options for affordable housing. A promising innovation that is gaining national popularity is the Domestic...
Show moreBlack women are at an increased risk for intimate partner violence (IPV). The complex interrelationships among housing instability, risk, and severity of abuse among IPV survivors has been established in the research literature, particularly for Black women who are often standing at the intersection of poverty, race, and gender, which results in having fewer financial resources and options for affordable housing. A promising innovation that is gaining national popularity is the Domestic Violence Housing First (DVHF) model, which involves providing survivor-driven mobile advocacy and flexible funding to meet the immediate housing needs of survivors. While preliminary evidence suggests the beneficial impacts of DVHF on improving survivors’ safety, housing stability, and well-being, there is little research that rigorously evaluates the impact of DVHF on the outcomes of Black survivors. To address this gap, the current study examined the long-term impact of the DVHF model on the safety, housing stability, and depressive symptoms of 61 homeless or unstably housed Black survivors who had recently sought DV services from one of five agencies located in the Pacific Northwest region of the United States. Results indicate that those who received the DVHF model experienced less revictimization compared to those who received services as usual. These findings are promising and have useful implications for Black survivors, DV agencies, policy makers instituting relevant laws, and grant-making institutions funding survivor-related programs/services.
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Title: Characterizing and Quantifying the Relationship between Triacylglycerol and Membrane Lipids during Nitrogen Deprivation and Resupply in Chlamydomonas using Isotopic Labeling
Creator: Young, Danielle Yvonne
Date: 2022
Collection: Electronic Theses & Dissertations
Description: As concerns about energy security and climate change have increased, microalgae have emerged as a promising feedstock for biofuel production. Microalgal oils have also recently gained popularity as nutraceutical supplements, such as serving as a source of omega-3 fatty acids. If microalgal oil content is to be tailored to a favorable composition for biofuel or nutritional purposes, the major biochemical pathways contributing to oil synthesis must be characterized. Chlamydomonas reinhardtii...
Show moreAs concerns about energy security and climate change have increased, microalgae have emerged as a promising feedstock for biofuel production. Microalgal oils have also recently gained popularity as nutraceutical supplements, such as serving as a source of omega-3 fatty acids. If microalgal oil content is to be tailored to a favorable composition for biofuel or nutritional purposes, the major biochemical pathways contributing to oil synthesis must be characterized. Chlamydomonas reinhardtii was chosen as a model microalga for this work because it has served as a model system for several areas of biology for well over fifty years, and thus has many resources and tools available for its study. Several environmental stresses are known to induce oil accumulation in microalgae, and deprivation of nitrogen was chosen in this study as it is the most widely-used, is easily applied, and induces very strong accumulation of neutral oil. This dissertation describes my research findings on the biochemical relationship between membrane glycerolipids and triacylglycerol (TAG) in C. reinhardtii during nitrogen deprivation and resupply. It includes the results of my work to elucidate the flow of fatty acids during TAG synthesis and the fate of fatty acids during TAG breakdown. It also includes my analysis of the biochemical mechanisms by which membrane glycerolipids are converted into TAG as well as which lipid moieties are converted into TAG. Time course experiments and isotopic labeling were the methods used in these analyses to trace the flow of carbon between biomolecules. An overview of acyl editing is also provided in this dissertation, as it is an important component of the TAG synthesis pathway in plants that is under-explored in microalgae. Finally, the dissertation concludes with future directions and experiments that would help address the outstanding questions that remain in C. reinhardtii lipid biochemistry.
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Title: ESSAYS IN LABOR ECONOMICS
Creator: Datta, Priyankar
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This dissertation contains three chapters that study the impact of a labor market policy onnursing home staffing and patient outcomes, the impact of parental divorce on long-term market outcomes, and the impact of a change in housing wealth on children’s schooling decisions. Chapter one examines the effect of paid sick leave mandates on nursing home outcomes, with a focus on low-paid nursing staff. I use the synthetic control group method and traditional difference-in-differences models along...
Show moreThis dissertation contains three chapters that study the impact of a labor market policy onnursing home staffing and patient outcomes, the impact of parental divorce on long-term market outcomes, and the impact of a change in housing wealth on children’s schooling decisions. Chapter one examines the effect of paid sick leave mandates on nursing home outcomes, with a focus on low-paid nursing staff. I use the synthetic control group method and traditional difference-in-differences models along with Nursing Home Compare data and Vital Statistics microdata to estimate the causal effect of paid sick leave mandates on nursing home outcomes. I find significant increases in part-time nursing assistant staffing and resident health and safety improvements. Nursing homes in areas with sick pay mandates also show reductions in the elderly mortality rate. Nursing assistant hours per resident day increase by 2.3 percent driven by a 12 percent increase in the hours for part-time workers, and there are no significant reductions in hours of full-time nursing assistants. I find improvements along multiple measures of patient health and safety. My calculations show that sick pay mandates helped prevent at least 4000 nursing home deaths per year among the elderly. Chapter two explores the importance of divorce in explaining the gender gap in children’s long-term educational outcomes. I find large differences in the gender gap between divorced and non-divorced families. Boys perform much worse in divorced families. I use a sibling fixed effects model to find that boys in divorced families have a lower likelihood of graduating high school and attending college relative to their sisters. My results show that boys’ likelihood of graduating high school declines by 6.4 percentage points if their parents are divorced before they turn 13, and their chances of attending college decline by 12.2 percentage points if they are a teenager at the time of divorce. I find that parents’ divorce is unrelated to the gender gap in achievement scores. My event study models show a drop in boys’ achievement scores relative to girls around the time of divorce. Chapter three examines the effect of housing wealth changes on private school enrolment. I use data from The National Longitudinal Survey of Youth’s child supplement to examine the relationship between housing wealth and private school enrolment. I use a multinomial logit model and find that self-reported housing price changes increase the likelihood that respondents switch from private to public school. Heterogeneity analyses reveal that house price increases have a positive relationship between switching from private to public school across income, gender, race, and religion. Finally, a rise in house prices increases the likelihood that a child moves from public school to private school when transitioning from middle school to private school.
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Title: Moral Intuition Prominence in Narratives Shapes Audience Attention and Affective Dispositions
Creator: Baldwin, Joshua Aaron
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The affective disposition theory (ADT) of drama suggests that moral judgments of a narrative character’s actions are a key determinant of character and story appeal. Specifically, approbation of behaviors prompts positive character dispositions and subsequent story liking. The modified affective disposition model (MADM; Tamborini, Grizzard et al., 2021) attempts to expand ADT by (a) explicating mechanisms that influence how dispositions are formed in morally complex storylines, (b)...
Show moreThe affective disposition theory (ADT) of drama suggests that moral judgments of a narrative character’s actions are a key determinant of character and story appeal. Specifically, approbation of behaviors prompts positive character dispositions and subsequent story liking. The modified affective disposition model (MADM; Tamborini, Grizzard et al., 2021) attempts to expand ADT by (a) explicating mechanisms that influence how dispositions are formed in morally complex storylines, (b) identifying factors that moderate these mechanisms, and (c) describing the mental processes that underlie them. ADT argues that narrative audiences are constantly monitoring the morality of a character’s behavior (Zillmann, 2000), and disposition formation is shaped by these moral appraisals. The theory suggests that people like characters that behave morally and dislike those that do not, but it gives little detail about how people make moral appraisals. The MADM builds on recent research indicating that moral appraisals are strongly influenced by character behaviors upholding or violating those moral intuitions most salient in the minds of audience members. In doing so, MADM attempts to explicate the mechanisms that increase or decrease the salience of competing intuitions in morally complex stories (i.e., stories wherein two or more moral intuitions are in conflict such that a character must violate one intuition to uphold another). According to the MADM, the salience of different moral intuitions in audience members is shaped by narrative exemplars that vary the prominence of different moral intuitions in the narrative. Specifically, it suggests that when storylines are morally complex, the level of a competing intuition’s prominence in content will strengthen the intuition’s salience in the minds of audience members and the attention that audiences give to intuition-related information. The influence of this prominence on the salience of and attention to different intuitions by audience members is predicted to moderate the disposition process and shape both (a) whether positive or negative dispositions are formed, and (b) whether dispositions are formed intuitively or deliberatively. This dissertation tests these proposed expansions using a 2 X 2 experiment that manipulates the prominence of two conflicting moral intuitions in content (i.e., dominantly vs. overridingly prominent) and whether a character upholds the prominent intuition (i.e., upholds vs. violates).The study results reveal two important findings. The first finding suggests that the comparative prominence of conflicting intuitions in content can influence the level of salience in the minds of audiences, which in turn strengthens or weakens the effect of observing a moral/immoral behavior on approbation. Higher prominence of the superordinate intuition weakens the strength of the subordinate intuition’s salience, which then weakens its ability to moderate the effect of upholding the superordinate intuition on approbation. The second finding suggests that different levels of comparative prominence (dominant versus overriding) can alter whether affect disposition (i.e., character liking) is formed intuitively or deliberatively. When the prominence of a superordinate intuition is dominant, disposition formation is intuitive. By comparison, when the prominence of a superordinate intuition is overriding, disposition formation is deliberative. The theoretical and social implications of these findings are discussed.
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