Environmental and Occupational Health Sciences Institute
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Diversity-valuing behavior: an investigation of self-observer convergence and uniqueness
No full textDiversity-valuing behavior (DVB), which refers to individual behavior that can bolster demographic balance in workplaces so that it reflects their community (e.g., hiring and promoting underrepresented workers, sharing job information with underrepresented workers), has been rated only by observers (e.g., coworkers, supervisors) thus far. It is important to note that any rater can be biased, but such biases of raters have not been discussed much yet when using observers to examine DVB. Thus, the purpose of this thesis is to examine the extent of the convergence and divergence between multisource ratings. In this thesis, I reviewed various biases of self-raters and observers which suggested the DVB ratings may involve subjective perceptions based on their demographic characteristics. In contrast to previous findings, on one hand, the results of this study showed that the levels of DVB engagement were not statistically different between predominant (i.e., men, Whites) and underrepresented (i.e., non-men, non-Whites) workers. On the other hand, there was not only a moderate convergence between self-raters and observers, but I also found evidence of divergence between the two types of raters. To be specific, both types of observers (i.e., supervisors, coworkers) tended to rate the DVB degree of focal employees higher than self-raters. The differences between self-and observer ratings became larger when focal employees and observers are of different genders or races.M.S.Includes bibliographical reference
Singling out: the effects of targeted training on creativity
No full textDiversity researchers have long examined the outcomes of diversity practices. However, the both positive and negative outcomes from diversity practices have not been thoroughly explained. Therefore, drawing from threat rigidity theory and the unintended consequences of diversity framework (Leslie, 2019), this study proposes that “target” employees will experience an increase in the salience of their stigmatized identity, which sparks countervailing effects of exposure to targeted training through competing mechanisms. On one hand, targeted training can spark stereotype threat and, thus, affective rumination, that can compromise creativity. On the other hand, stereotype threat can boost problem-solving pondering that can increase creativity. It is also expected that the case for diversity (business vs fairness) will influence the likelihood of experiencing stereotype threat. Based on multimethod experimental and survey design, I consistently find that targeted training is positively associated with stereotype threat. Furthermore, I find that targeted training impacts creative process engagement for racial/ethnic minority employees. Additionally, results support a mediating effect of this relationship by stereotype threat and rumination. Finally, results support a moderating effect of case for diversity in the relationship between targeted training and stereotype threat. Limitations and implications for diversity research and organizations are discussed.M.S.Includes bibliographical reference
My sweet sibling and I
No full textThe focus of this capstone project is to create a resource for siblings of individuals with Congenital Hyperinsulinism [HI], a rare genetic disorder that affects 1 in 25,000 babies annually and can result in hypoglycemia leading to seizures, brain damage, and even death. While those with HI face significant challenges, their siblings also experience unique difficulties such as emotional distress, adjustment problems, and taking on caregiver responsibilities. These challenges may be partly attributed to a lack of communication and understanding about HI within the family structure. This resource aims to help families navigate the complexities of HI, including providing support to siblings who may be struggling with their emotions. A group of 17 participants were provided with the storyline and asked to complete a corresponding Qualtrics survey to obtain feedback on the content. There was a 59% response rate, in which the majority of the respondents agreed the content was satisfactory in demystifying and educating siblings on the condition. The results indicated that the book met the project's stated goals, and we believe it will be a beneficial tool for families seeking to foster healthy relationships between children with HI and their siblings.M.S.Includes bibliographical reference
Essays in international macroeconomics
No full textThis dissertation is composed of three chapters that study topics in the fields of international macroeconomics and international finance. Chapter 1 studies how news about future Total Factor Productivity (TFP) impacts the investment channel and, in turn, affects the susceptibility to financial crises such as Sudden Stop episodes. A Sudden Stop episode is a crisis stemming from a rapid and severe reduction in economic capital inflows. The study employs a small open economy model with capital accumulation and a representative agent borrowing against an occasionally binding collateral constraint to explore the influence of persistent news shocks on financial stability and optimal policy response. It shows that news shocks increase the probability of Sudden Stops and require an active and substantial policy rate intervention. In a similar framework of endogenous Sudden Stop crises triggered by occasionally binding borrowing constraints, chapter 2 examines policy interventions available in a two-sector small open economy. It distinguishes between the taxes on household debt policy that targets the borrowing activity in the economy and a tradable revenue policy that allocates resources across the two sectors, consistent with an exchange rate policy. It shows that optimal policy when only a single policy tool is available is a tax before and a subsidy during the crisis. Furthermore, the tradable revenue policy over a borrowing-targeted policy provides higher welfare gains. Lastly, chapter 3 investigates the role of financial frictions on technological adoption and macroeconomic implications. It develops a model with heterogeneous producers, different productivity and wealth levels, and studies the implications of financial development on technology adoption rates. This chapter emphasizes how the inclusion of the intermediate technology helps replicate key features observed in micro-level data and provides positive effects of intermediate technology on macroeconomic variables such as consumption, output, and TFP. Overall, this dissertation uses theoretical and empirical approaches to provide essential policy implications for policymakers in emerging and developing economies. The findings contribute to the ongoing discussion on how financing opportunities play a role through investment and technological adoption channels to cause financial instability and subsequent policy implementations.Ph.D.Includes bibliographical reference
Safety and efficiency for high-dimensional robots: integrating learning, planning and control
No full textIn this thesis, I tackle two pivotal challenges in robotics: enhancing safety control via regions of attraction (RoA) estimation and boosting the computational efficiency of motion planning for robots with complex dynamics. The first segment of my work contributes to a novel approach named MORALS (Morse graph-aided discovery of Regions of Attraction in a learned Latent Space). By employing autoencoding neural networks in tandem with Morse Graphs, MORALS adeptly maps the dynamics of controlled systems into a learned latent space. This allows for the efficient and effective estimation of attractors and their RoAs, markedly improving data efficiency in estimating RoAs for complex systems without relying on analytical models. My contribution to MORALS centered on developing and training a data-driven controller for a 67-dimensional humanoid robot, integrating a novel contrastive loss component. This addition crucially underscored the importance—or lack thereof—of labeled data in our approach.
The thesis's second portion is a collaboration focused on refining the computational efficiency of motion planning through a novel, decoupled strategy that marries system-specific learned controllers with an innovative data structure termed the "Roadmap with Gaps." My role involved training offline controllers for quadrotors using the Soft Actor-Critic (SAC) algorithm enhanced with Hindsight Experience Replay (HER) and devising comparison strategies leveraging Deep Reinforcement Learning (DRL). This hybrid structure facilitates efficient planning by connecting local regions through the application of learned control policies, while a tree sampling-based motion planner dynamically adjusts to gaps and obstacles. Tested across various benchmarks, including physics-based vehicular models and quadrotors, this approach demonstrated marked improvements in planning efficiency and enhanced robustness in the face of environmental uncertainties.
Collectively, this thesis contributes to the field of robotics by providing methodologies that enhance both the safety of control systems through data-efficient RoA estimation and the efficiency of motion planning in environments with complex dynamics. Integrating Morse Graphs with learned latent spaces and the innovative use of learned controllers within a motion planning framework represent significant steps in developing autonomous robotic systems capable of navigating and operating safely and efficiently in high-dimensional and dynamically challenging environments.M.S.Includes bibliographical reference
The orphan G protein-coupled receptor, GPR161, regulates adult neurogenesis and human development through Protein Kinase A
No full textThe orphan GPCR, GPR161, is expressed in nearly every organ and every cell type within mammalian organisms. Its status as an orphan receptor, lacking a known ligand which targets the receptor, has made investigation of the signaling pathways it activates problematic. However, GPR161’s unique ability, among GPCRs, to bind the master cellular kinase, Protein Kinase A (PKA) could underlie its role in multiple molecular signaling pathways. Furthermore, Gpr161 has been demonstrated to control neural stem cell proliferation and differentiation motivating further investigation of GPR161’s downstream signaling targets and pathways.
Gpr161 is expressed in neurogenic zones in the adult mouse including the hippocampus. In neurospheres derived from the mouse hippocampus genetic manipulation of Gpr161 expression levels affect adult neural stem cell (aNSC) proliferation and apoptosis. Our data demonstrates Gpr161 expression levels in aNSC affect aNSC production of RA. Molecular signaling through Gpr161 is linked to the retinoic acid (RA) signaling pathway through phosphorylation of the retinoic acid receptor α (RARα). RARα phosphorylation is decreased and increased in Gpr161 knockdown and overexpression, respectively. We discover that the effects of Gpr161 are not mediated through canonical RA signaling but through an alternative transcription factor. These data suggest the hypothesis that Gpr161 signaling contributes to the regulation of RA synthesis and the regulation of RA pathway target genes.
Next, this dissertation investigated a novel human mutation in GPR161 resulting in clinical diagnoses, consistent with ciliopathies and fetal lethality. The mutation was mapped and discovered to result in an amino acid change in GPR161’s third intracellular loop (ICL3). Bioinformatic analysis revealed this mutation affects GPR161 interaction with and molecular signaling through PKA. Expression of the GPR161 mutation in IMCD3 resulted in the formation of ciliopathies reminiscent of the symptoms observed in human patients with the mutation. The GPR161 mutation also resulted in cAMP level increases and increased PKA-mediated inhibition of the Shh signaling pathway. Taken together, these results suggest GPR161 interaction with PKA plays an essential role in mammalian cellular signaling and human disease.Ph.D.Includes bibliographical reference
Risk analysis of unit trains versus manifest trains for transporting hazardous materials
No full textFreight trains provide a safe and efficient way of transporting substantial amount of hazardous material (hazmat) across extensive distances. While the likelihood of hazmat release incidents during train transport is low, the potential consequences remain substantial. The type of train, whether unit or manifest, plays a crucial role in influencing the risk associated with hazmat transportation. Unit trains primarily face risks on mainlines and during terminal operations, while manifest trains encounter additional risks during switching activities in classification yards. Drawing on existing literature and leveraging diverse data sources, this dissertation conducts a comprehensive analysis of the risks associated with railroad hazmat transportation, focusing specifically on flammable liquids. This analysis accounts for various factors including train type, train length, arrangement of hazmat cars within the train, speed, yard type, yard switching methods, traffic exposure, and other operational variables.
The framework of the risk analysis encompasses several key components:1) A derailment-cause-specific model that estimates the probability of train-type-specific derailments based on U.S. railroad derailment data spanning from 1996 to 2018; 2) Utilization of a truncated geometric statistical model and a physics-informed time-stepping algorithm to estimate derailment severity (i.e., the number of cars derailed). The physics-informed model serves as a validation to complement the probabilistic model; 3) Development of a position-dependent tank car derailment and release probability model, which considers the point of derailment, derailment severity, tank car placement, and safety design of tank cars; 4) Estimation of the probability distribution for the total number of tank cars releasing contents, achieved through a Poisson Binomial distribution model utilizing the position-based tank car release probabilities; 5) Calculation of the estimated amount released by combining the number of tank cars releasing contents with the amount released per individual tank car; 6) Determination of expected casualties resulting from derailments.
The proposed probabilistic model is applied to a case study of typical train configurations, along with an extended study incorporating regulatory considerations and practical guidelines.Ph.D.Includes bibliographical reference
Studying two photon exchange with ep and μp elastic scattering in the MUSE experiment
No full textThis thesis presents an analysis of Two-Photon Exchange (TPE) for elastic ep and μp scattering at ±115 MeV/c and ±160 MeV/c. The cross-section ratios σe+p/σe−p and σμ+p/σμ−p are used to study the experimental TPE contributions and are compared to theory. The data analysed were taken by the MUon proton Scattering Experiment (MUSE) during the Summer 2023 run time. MUSE aims to shed light at the proton radius puzzle (PRP) by simultaneously measuring ep and μp cross-sections. The determination of the proton form factor and subsequently the proton radius has relied on theoretical TPE corrections, as the correction has not been measured in previous radius experiments.Ph.D.Includes bibliographical reference
Communal coping and relational turbulence between emerging adult children and their surviving parent after the experience of parental/partner death
No full textOne of the most challenging transitions families face is the death of a parent/partner. The death of a parent/partner disrupts the surviving parent and child’s life and contributes to a wide array of stressors that can significantly impact relationship functioning for the surviving dyad. Relational turbulence theory argues that when dyads are faced with transitions in their relationships these transitions have the potential to create changes in roles and routines. In turn, these circumstances amplify questions about relational involvement, disrupt or alter interdependence patterns, polarize communication, and allow for relational turbulence. The stressors parents and emerging adult children experience after parental/partner death are ripe for the experience of relational turbulence. Although parental/partner death marks an extraordinarily challenging time for the surviving dyad, there is also potential for parents and children to work together to adjust to the death and enact coping behaviors. This notion is reflected in the extended theoretical model of communal coping which illustrates how dyads and small groups enact coping strategies to navigate stressors. Given this logic, this dissertation advances 13 hypotheses and 18 research questions to explore the interplay between relational turbulence and communal coping in the relationship between surviving parents and emerging adult children after parental/partner death. Forty-five parent/emerging-adult child dyads completed a series of six weekly surveys, with scales measuring stress, mental health, relationship characteristics, relationship functioning, communicative interactions, communal coping, and relational turbulence, and open-ended questions soliciting narrative responses about their uncertainty, interdependence, and coping. The qualitative responses were analyzed with a thematic analysis, a phronetic iterative approach to qualitative data analysis, and a thematic co-occurrence analysis. Results revealed four sources of relational uncertainty, four themes of interdependence, and five themes associated with coping behaviors. Furthermore, results of a thematic co-occurrence analysis revealed nine patterns between and across experiences of relational uncertainty themes for parents and children, three patterns between and across interdependence themes for parents and children, ten patterns between and across communal coping themes for parents and children, and ten patterns across experiences of uncertainty, interdependence, and coping themes for parents and children. The quantitative survey responses were analyzed with hierarchical linear modeling to create multilevel models to assess hypotheses. In particular, actor effects, partner effects, and longitudinal effects were assessed with two-level models. Results provided mixed support for the proposed hypotheses and revealed the presence of some partner effects with regard to research questions. The dissertation concludes with a discussion of theoretical and practical limitations for the qualitative and quantitative results, implications of the qualitative and quantitative results when considered in tandem, and a discussion of strengths, limitations, and directions for future research.Ph.D.Includes bibliographical reference