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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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Title: BLENDING OF POLY(LACTIC ACID) AND POLY(3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE) – THE EFFECT OF MALEATED PLA AS A REACTIVE COMPATIBILIZER AND BIODEGRADATION STUDY
Creator: Muangmala, Woranit
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Poly(lactic acid), PLA was blended with poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, based on a crossed mixture-factorial experimental design with three levels of factorial variable of the type of pre-produced maleated PLA, PLAgMA-type, used as the blend compatibilizer, and three components mixture variable which were the contents of PLA, PHBV, and PLAgMA, included in the polymer blends. The mixture model was based on the constrained level of the weight fraction of each mixture...
Show morePoly(lactic acid), PLA was blended with poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PHBV, based on a crossed mixture-factorial experimental design with three levels of factorial variable of the type of pre-produced maleated PLA, PLAgMA-type, used as the blend compatibilizer, and three components mixture variable which were the contents of PLA, PHBV, and PLAgMA, included in the polymer blends. The mixture model was based on the constrained level of the weight fraction of each mixture component as follows: 0.2 ≤ PHBV ≤ 0.7, 0.2 ≤ PLA ≤ 0.7, and 0.05 ≤ PLAgMA ≤ 0.15. The design of experiment yielded 16 runs of compatibilized blends, with 2 runs of non-compatibilized blend and 2 runs of neat polymers, PLA and PHBV, for comparison. The model of relationship between variables was derived based on the multiplication of a linear relationship of one factorial variable with a quadratic Scheffe model of the mixture ingredients. Multiple formulas of the blend compatibilizer, maleated PLA (PLA-g-MA), were pre-produced by a reactive melt blending method to functionalize maleic anhydride, MA, on the PLA backbone in a twin-screw co-rotating extruder. Dicumyl peroxide, DCP, was used as a free radical initiator in the reactive blending. The formulas were designed using response surface experimental design to determine the effect of the contents of MA and DCP on the amount of grafted MA, MA-grafting yield, and the molecular weight properties, Mn, Mw, IV, and dispersity of PLA-g-MA. The model regression indicated a significant effect of DCP with increasing DCP tending to reduce the MA-grafting yield, Mn, Mw, and IV, and increase the dispersity. The optimum point that maximized the desirability of these responses simultaneously was with the content of DCP = 0.1 wt. % and MA = 3.94 wt. % (PLA basis). Blending of PLA and PHBV clearly increased the crystalline fraction of the blends compared to neat PLA, which affects the barrier properties of the materials. Inclusion of PHBV at 25 wt. % in the non-compatiblilized blend and at 45 – 60 wt. % in compatibilized blends resulted in more than 60% reduction of water and O2 permeability compared to PLA. The compatibilized PLA/PHBV blend with PLA weight fraction of 0.45 achieved 300% increase in the tensile strength compared to the neat PHBV; this level of improvement was equivalent to the non-compatibilized blend containing PLA 75 wt. %. This was attributed to enhanced interfacial adhesion that was evidently supported by increased miscibility between the blend components in compatibilized blends which was exhibited through the shifting of Tg of PLA and the decrease of k constants based on the Gordon-Taylor equation of the compatibilized blends. The factorial-mixture model regression suggested the validity of the mixture variable of PLA, and PHBV in both tensile and barrier properties; the PLAgMA had a significant effect only on the tensile performance of the polymer blends. The overlapped contour plots as well as the desirability functions could be used to optimize the mixture of the PLA/PHBV blend components that provide desirable tensile and barrier properties. A biodegradation study was conducted on neat PLA, PHBV, non-compatibilized blend of 75:25 PLA/PHBV, and compatibilized blend of 65:15:20 PLA/PLA-g-MA/PHBV. PLA/PLA-g-MA/PHBV was the fastest to reach 100% mineralization, followed by PLA and PLA/PHBV samples, according to the CO2 evolution and % mineralization, whereas PHBV reached only 81% mineralization at the end of the test of 180 days. The facilitation of anhydride present in PLA-g-MA on the hydrolysis of PLA was a major cause of the fast biodegradation of PLA/PLA-g-MA/PHBV. A sharp increase in enthalpy of fusion, ΔHf, as well as a rapid reduction of the molecular weight of PLA/PLA-g-MA/PHBV compared to PLA and PLA/PHBV support the occurrence of an elevated rate of hydrolysis. The PHBV sample showed the biodegradation was barely affected by abiotic hydrolytic degradation as the thermal properties did not show any shifting of the melting transition and the ΔHf remained stable until 30 days of the test; the main mechanism was the enzymatic microbial degradation causing an erosion at the surface rather than affecting the bulk properties such as the molecular weight. The scanning electron micrographs also revealed the biodegradation of PHBV that initially occurred was from the surface and later showed the degradation of the crystalline structure. The PLA crystals formed during the biodegradation of PLA/PHBV and PLA/PLA-g-MA/PHBV samples could be seen from SEM photos.
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Title: LONGITUDINAL EXAMINATION OF FIRM-LEVEL SUPPLY CHAIN SUSTAINABILITY
Creator: Li, Ming
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Supply chain sustainability is a topic of immense importance for the press, political activists, managers, analysts, investors, shareholders, and stakeholders (e.g., local communities). One aspect of a firm’s sustainability concerns the actions taken by members of its supply chain, such as the use of child labor and the dumping of toxic emissions. While there have been several attempts in measuring firms’ sustainability as it pertains to their supply chains, these approaches suffer from...
Show moreSupply chain sustainability is a topic of immense importance for the press, political activists, managers, analysts, investors, shareholders, and stakeholders (e.g., local communities). One aspect of a firm’s sustainability concerns the actions taken by members of its supply chain, such as the use of child labor and the dumping of toxic emissions. While there have been several attempts in measuring firms’ sustainability as it pertains to their supply chains, these approaches suffer from numerous methodological weaknesses. This has limited our ability to answer important questions such as how firms’ sustainability performance as it pertains to their supply chain evolved over time, and what factors affect this evolution? This question constitutes my primary research interest and has motivated my three-essay dissertation that:Essay one: develops a new approach for measuring firm-level corporate social responsibility (CSR) and corporate social irresponsibility (CSI) supply chain practices using log-logistic item response theory models; Essay two: studies how firm-level CSR and CSI supply chain practices have evolved over time using piecewise latent growth curve models; and Essay three: examines the dynamic inter-relationships between firm-level CSR and CSI supply chain practices using dynamic panel models. To answer these questions, I use panel data from 2003 – 2018 for hundreds of publicly-traded manufacturers, wholesalers, and retailers from KLD, which I merge with financial data from COMPUSTAT, market concentration from US Census Bureau Economic Indicators, and Upstreamness measuring of the average distance from final use from American Economic Review. My results improve our theoretical understanding of how sustainable supply chain practices can be measured and how they evolve over time.
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Title: Fighting Zombies Together : A Longitudinal Experimental Test of Prejudice Reduction Through Media Exposure to Non-Human Villains
Creator: Yao, Xuejing
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Increasing the salience of shared human identity has been demonstrated as an effective mechanism to reduce interracial prejudice (e.g., Ellithorpe et al. 2018; Yao et al., 2022a). Previous research has found that watching racially diverse human heroes fighting against non-human villains increased the strength of viewers’ human identity, and their stronger human identity is in turn associated with more positive attitudes toward racial minority groups. This dissertation replicated Ellithorpe et...
Show moreIncreasing the salience of shared human identity has been demonstrated as an effective mechanism to reduce interracial prejudice (e.g., Ellithorpe et al. 2018; Yao et al., 2022a). Previous research has found that watching racially diverse human heroes fighting against non-human villains increased the strength of viewers’ human identity, and their stronger human identity is in turn associated with more positive attitudes toward racial minority groups. This dissertation replicated Ellithorpe et al.’s (2018) research through a longitudinal controlled experiment with three waves of stimuli exposure and a posttest. The longitudinal design also made it possible to test the chronic accessibility of the human identity. Overall, minimal support was found for the longitudinal mediation with the current data and the human identity showed relatively short salience. However, this set of findings provided important information about the property of the superordinate human identity. Implications of the current findings as well as directions for future research were discussed.
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Title: STUDYING ENGAGEMENT TO INFORM DESIGN OF CALCULUS 2 COMPUTATIONAL LABS
Creator: Krause, Andrew Joseph
Date: 2022
Collection: Electronic Theses & Dissertations
Description: This is a study of student engagement with computational labs in Calculus 2. The labs task students with using MATLAB to investigate contexts such as rocket science, disease modeling, and market economics forecasting by modifying and executing provided code, guided by questions that have students report the results of their simulations or observations of the model, as well as interpretive questions that ask them to make sense of their findings in the context of the realistic situation.Locally...
Show moreThis is a study of student engagement with computational labs in Calculus 2. The labs task students with using MATLAB to investigate contexts such as rocket science, disease modeling, and market economics forecasting by modifying and executing provided code, guided by questions that have students report the results of their simulations or observations of the model, as well as interpretive questions that ask them to make sense of their findings in the context of the realistic situation.Locally, the study is situated within an iterative design process with the goal of improving the labs and their implementation, meaning there are direct connections between the research and improvements to the written tasks or teaching practices. The goal of this dissertation, from a research perspective, is to examine student engagement to contribute to the development of theory about lab-type activities and the learning opportunities they facilitate. To accomplish both goals, this study follows a design-based research (DBR) methodology, which provides a structure to relate the local goal to inform practice to the broader research goal to develop theory that is useful broadly.The labs can be considered novel learning activities, with novel learning goals, in a novel teaching context. The labs were novel learning activities because they were the original product of the curriculum designers and they were still being substantially revised during the third year of the project, when this study took place. The learning goals were novel at the research site because they involved collaborative and higher-level objectives, a notable departure from the traditional emphasis on individual mastery of various rote calculation. The teaching context was novel because this research was conducted during the first time the labs were taught “at-scale”, meaning it was the first time the labs were being led by graduate students during recitations connected to a multi-section large-lecture. In this novel context, studying engagement provides a way to understand how the labs facilitate students’ attainment of those learning goals without attempting to measure students’ individual attainment of those learning goals. Students learn through engagement, so understanding how students engage with the labs is a way to understand how students are learning—if students are engaged in the mathematical practices the labs are intended to facilitate, then they are learning those mathematical practices.This study examined engagement through interviews, classroom observations, and a post-course survey. Students were observed collaborating productively by discussing their thinking, tinkering with code, and co-authoring solutions. Rarely were off-task behaviors observed. Some interview participants identified intrinsic learning goals and other students were invested in completing the labs simply because they were a required, graded assignment. Some students found the labs to be interesting, challenging, and useful, but the broader sentiment was a more negative reaction that was especially pronounced in the post-course survey data. These negative feelings, however, did not appear to disrupt students’ behavioral or cognitive engagement in the classroom, because students continued to put forward effort to complete the labs through the end of the semester, suggesting that negative emotional engagement does not necessarily lead to overall disengagement or undermine students’ motivation. In other words, even though some students might not be trying to learn how to use MATLAB to model Calculus 2 concepts, they learn some of those skills anyway because they have to do the things they are supposed to learn.
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Title: Wall-Crossing for Tilt Stability
Creator: Rekuski, Nicholas
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Recent techniques from Bridgeland Stability have given new, interesting results about stable vector bundles on surfaces. However, in higher dimensions the theory is substantially harder, so there has been significantly less progress in this case. In this thesis, we develop theory for a related notion—tilt stability— then apply this theory to stable vector bundles.In the first part of this thesis, we recall and further develop the theory of tilt stability. This development culminates in a wall...
Show moreRecent techniques from Bridgeland Stability have given new, interesting results about stable vector bundles on surfaces. However, in higher dimensions the theory is substantially harder, so there has been significantly less progress in this case. In this thesis, we develop theory for a related notion—tilt stability— then apply this theory to stable vector bundles.In the first part of this thesis, we recall and further develop the theory of tilt stability. This development culminates in a wall-crossing result for tilt stability.In the second part of this thesis, we apply our wall-crossing result to study stable vectorbundles. Our first application is a criterion for when the restriction of a slope stable bundle to an integral subvariety is still slope stable. Our second application is to the theory of Lazarsfeld-Mukai bundles. Specifically, we show the Lazarsfeld-Mukai bundle associated to a Gieseker stable bundle is slope stable, and that slope stability and slope semistability are equivalent for Lazarsfeld-Mukai bundles associated to ample line bundles.
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Title: SOCIAL MECHANISM OF SOCIAL SUPPORT PROVISION : A BEHAVIORAL STUDY OF ONLINE SUPPORT GROUPS
Creator: Lee, Sanguk
Date: 2022
Collection: Electronic Theses & Dissertations
Description: The popularity of Online Support Groups (OSGs) is ever increasing as OSGs enable people with (dis)similar health conditions to exchange social supports easily. Social support provision is a critical activity for individual well-being and community sustainability, yet the underlying social mechanism that promotes social support provision is underexplored. Employing social capital theory, the current study examines how brokerage and closure structures yield different forms of social capital...
Show moreThe popularity of Online Support Groups (OSGs) is ever increasing as OSGs enable people with (dis)similar health conditions to exchange social supports easily. Social support provision is a critical activity for individual well-being and community sustainability, yet the underlying social mechanism that promotes social support provision is underexplored. Employing social capital theory, the current study examines how brokerage and closure structures yield different forms of social capital such as non-redundant information and trust, which subsequently facilitate the diverse dimensions of informational and emotional support provisions, including quantity, quality, and timing. Methodologically, the study utilizes computational methods to collect online behavioral data from an online cancer community, measure network metrics and support provision behaviors, and capture the dynamic relationships between the network structure, social capital, and support provision behaviors. Results indicate that the brokerage structure and non-redundant information enhance the volume, uniqueness, and speed of information support provision. Although the closure structure and trust have a positive influence on the quality of emotional support, their overall impacts are limited in promoting information and emotional supports in the context of OSGs. The findings also indicate the importance of considering the dynamic development stage of OSGs in understanding the social mechanism of support provisions.
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Title: AGENTS OF SEE CHANGE : CATHOLIC WOMEN’S ORGANIZATIONS IN WEST GERMANY, 1945-1968
Creator: Brothers, Heather
Date: 2022
Collection: Electronic Theses & Dissertations
Description: ABSTRACTAGENTS OF SEE CHANGE: CATHOLIC WOMEN’S ORGANIZATIONS IN WEST GERMANY, 1945-1968ByHeather Brothers This dissertation examines Catholic women's organizations in West Germany from 1945 to 1968. Women in organizations like the Central Association of Catholic Women and Mothers’ Organizations (ZKFM) were important agents of change within both West German society and the Catholic Church. Despite being largely left out of scholarly discussions about the postwar period, West German Catholic...
Show moreABSTRACTAGENTS OF SEE CHANGE: CATHOLIC WOMEN’S ORGANIZATIONS IN WEST GERMANY, 1945-1968ByHeather Brothers This dissertation examines Catholic women's organizations in West Germany from 1945 to 1968. Women in organizations like the Central Association of Catholic Women and Mothers’ Organizations (ZKFM) were important agents of change within both West German society and the Catholic Church. Despite being largely left out of scholarly discussions about the postwar period, West German Catholic women and the knowledge they created fundamentally shaped the intellectual culture of the Catholic milieu during this era. The ZKFM, and other organizations like it, gave Catholic women a platform within the Church that both limited the scope of their ideas and actions, but also provided these women with networks and connections that empowered them to effectively challenge Catholic dogma and tradition and to intervene in West German debates about women’s role in family, society, and state. By studying the intellectual work of Catholic women and their organizational labor, I argue that we can better understand the relationship between women, the Church, and West German society. This dissertation explores how interactions between conceptions of gender and Catholic faith are integral to understanding both women’s place within the structures of Church and state and also how women worked to shape these structures to their own ends. Women in the ZKFM expressed a wide diversity of opinions, and the organization allowed and encouraged new interpretations on both faith and gender that helped to set the association’s agenda moving forward. While influenced by conservative Catholic tradition and a conservative West German state, the diversity within the ZKFM also emboldened members to explore feminist ideas and other progressive pursuits. When we look closely at ZKFM conferences, publications, benevolent activities, and public interventions, we can see that these women and their intellectual work played a significant role in shaping the landscape of postwar West Germany.
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Title: Plasma Based Methods for the Synthesis and Deposition of Nanoparticles
Creator: Ho, Alexander
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Nanoparticles exhibit tunable properties that offer the opportunity to improve existing technologies. Nanoparticles also possess emergent properties that are not shared by their bulk scale counterparts; this difference in properties allows for application of materials in devices and processes that were traditionally unsuitable. For semiconducting nanoparticles, the emergent and tunable properties hold promise for applications in solar cells, light emitting devices, sensors, catalysis, and a...
Show moreNanoparticles exhibit tunable properties that offer the opportunity to improve existing technologies. Nanoparticles also possess emergent properties that are not shared by their bulk scale counterparts; this difference in properties allows for application of materials in devices and processes that were traditionally unsuitable. For semiconducting nanoparticles, the emergent and tunable properties hold promise for applications in solar cells, light emitting devices, sensors, catalysis, and a variety of other spaces.Explored first was the syntheis of InN, GaN, and InGaN at low pressure. These materials possess properties suitable for high-power and high-frequency electronics applications. The materials also possess bandgaps that span from the IR to the UV allowing for the use in a host of optoelectronic applications. A low-pressure RF plasma reactor was used to dissociate precursor gases whose subsequent reactions formed the nanoparticles. Nanoparticles were then collected and characterized with a host of techniques. Experiments were conducted that demonstrated the synthesis of crystalline nanoparticles with narrow size distributions. It was shown that particle size and crystallinity could be controlled through modulation of residence time and RF power respectively. This method demonstrated the synthesis of luminescent InGaN nanoparticles without any subsequent surface modification or post-synthesis treatment. To eliminate the time and capital costs of vacuum equipment and processes an atmospheric pressure microplasma operated with ambient surroundings was investigated. With this method crystalline silicon nanoparticles were synthesized. OES and FTIR were used in conjunction to ascertain if particles were synthesized in an oxygen contaminated environment. Results of the experiments indicatethat particles were not exposed to oxygen in the reaction volume. Lastly an integrated atmospheric pressure synthesis reactor and aerosol jet printing process are described. Such a process would be useful for fabrication or prototyping of devices that require nanoaprticles. Combination of the reactor with a motorized stage and gantry allowed for deposition of nanoparticles with linewidths down to 100 microns. Methods to improve impaction efficiency were implemented and allowed for capture of sub-5 nm particles that exhibited luminescence at 680 nm. Also demonstrated was the control of synthesis parameters at the time of deposition to deposit particles with spatially varied properties.
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Title: EVALUATION OF DYNAMIC SPEED FEEDBACK SIGNS ON FREEWAY INTERCHANGE RAMPS
Creator: Mahmud, Md Shakir
Date: 2022
Collection: Electronic Theses & Dissertations
Description: Dynamic speed feedback signs (DSFS) are promising countermeasure to reduce curve speeds and subsequent lane departures at freeway interchange ramps, although their use in such contexts has been limited. Consequently, the impact of DSFS on driver performance at interchange ramps has remained unproven. To that end, research was performed to determine the effect of DSFS installed at freeway interchange ramps on measures of driver behavior, particularly vehicular speeds approaching and entering...
Show moreDynamic speed feedback signs (DSFS) are promising countermeasure to reduce curve speeds and subsequent lane departures at freeway interchange ramps, although their use in such contexts has been limited. Consequently, the impact of DSFS on driver performance at interchange ramps has remained unproven. To that end, research was performed to determine the effect of DSFS installed at freeway interchange ramps on measures of driver behavior, particularly vehicular speeds approaching and entering the ramp curve. To accomplish this objective, a series of field evaluations were conducted at six freeway interchange ramps possessing significant horizontal curvature. Several factors were tested during these evaluations, including: DSFS messaging strategy, positioning of the DSFS with respect to the start of the curve and side of the ramp, physical characteristics of the DSFS, radar detection range, interchange type, and temporal effects. Speed data were collected using one of these three techniques selected based on the site characteristics and types of data desired: 1) a series of high-definition video cameras, 2) handheld LIDAR, and 3) a speed-trailer. Several measures of effectiveness including speed at different locations, speed of drivers at different speed percentiles, and initial braking location were analyzed using appropriate regression techniques. Considering all phases of the field evaluation, it was concluded that DSFS are an effective countermeasure for reducing the speeds of vehicles approaching and entering horizontal curves on freeway exit ramps. The most critical aspect influencing the effectiveness of the DSFS as a speed reduction countermeasure was the longitudinal positioning of the sign relative to the ramp curve. Overall, the presence of a DSFS positioned near the start of the curve resulted in curve entry speeds that were, on average, 1.5 mph to 5.3 mph lower than without a DSFS present at the site. When the DSFS was present near the start of the curve, the lowest curve entry speeds were observed for cases where the feedback message activated when vehicles were within 250 to 400 ft of the start of the curve. Regarding DSFS lateral position, both the right-side-mounted and forward-mounted (i.e., ramp gore area) installations resulted in similar curve entry speeds. Furthermore, there were no discernable differences in curve entry speeds between 15-inch and 18-inch display panels, nor were speeds impacted by the inclusion of an advisory speed panel. In terms of feedback message, the most effective strategy was to display the measured speed alternating with a SLOW DOWN message. The effects on driver behavior associated with the DSFS were consistent between system interchanges and service interchanges, and across all vehicle types. The DSFS was equally effective irrespective of the mainline speed limit or ramp advisory speed. However, more pronounced speed reduction effects were observed for faster drivers (i.e., those within the highest quantiles) compared to the slower or average drivers. Furthermore, there was no evidence of temporal changes in driver behavior during the initial 14 months of operation of the permanent DSFS installation evaluated here. Finally, message activation did not show any significant effect on the speeds of mainline (i.e., non-exiting) vehicles. These findings were subsequently utilized towards the development of guidelines and recommendations for future use of DSFS at freeway interchange ramps.
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