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Ground-based Light Curve Follow-up Validation observations of TESS object of interest TOI 5907.01
Get PDF“The TESS mission, standing for the Transiting Exoplanet Survey Satellite, is a NASA guided mission that looks for potential exoplanets using the transit method. When the satellite sees a potential exoplanet, it does not immediately validate the presence of an exoplanet, instead turning it into one of TESS Objects of Interests (TOIs) and letting researchers conduct ground-based follow-up validations to confirm. Our research was conducted on TESS Object of Interest 5907.01. The goal was to investigate and confirm if a transit had occurred. Additionally, we wanted to confirm if our results matched the expected duration, depth, and transit start and end times predicted by TESS. Our initial results show that a very faint transit occurred. Additional work suggests that TOI 5907.01 likely is an exoplanet.
FROM ‘HYBRID’ TOWARDS ‘FULL’ AUTHORITARIANISM? REGIME TRANSITIONS IN TURKEY AFTER 2011
Get PDFWith the erosion of liberal principles especially after the third electoral victory of AKP in 2011, Turkey evolved into a competitive authoritarian regime during the snap elections in 2015. After the failed coup attempt in 2016, AKP further intensified the regime’s evolution toward authoritarianism with the imposition of a two-year-long state of emergency and the establishment of an executive presidential system. This dissertation examines political polarization, international conditions, and the rise of personalism to understand the factors that resulted in Turkey’s shift to an authoritarian regime to better comprehend the sources of authoritarian stability and resilience
Cell Assembly Formation and Retrieval in a Biologically Constrained CA3 Network
Get PDFWhen we reminisce about our past, the evoked memory typically consists of specifics including where and when an event occurred, what happened, and how we felt about it. Our brain remembers these multi-faceted experiences by co-activating groups of neurons, so-called cell assemblies. A leading neuroscience theory posits that hippocampal area Cornu Ammonis 3 (CA3) binds together details to form an episodic memory via auto-association (cell assembly formation), and the memory is later recalled through pattern completion (cell assembly retrieval). However, the exact mechanisms of how circuits of diverse neurons communicating via spikes and complex synaptic signals implement these processes are still unknown. To address this open problem, I created a full-scale spiking neural network (SNN) simulation of the mouse CA3 that integrated data-driven properties from the Hippocampome.org open-access knowledge base. I first simulated the SNN without prolonged stimulation to investigate the network dynamics before memory storage. The resultant network activity was stable and rhythmic in the beta band (12-30 Hz), consistent with empirical evidence when awake mice are not performing a memory task. Building on this work, I demonstrated the SNN was capable of robust auto-association and pattern completion via cell assemblies. The assemblies could successfully and systematically retrieve patterns from heavily incomplete or corrupted cue presentations. A broad range of assembly sizes, consistent with theory and experiments in rodents and humans, supported strong auto-association and pattern completion. The CA3 SNN performance was robust with respect to partial overlap of assemblies through shared cells, substantially enhancing memory capacity. These results provided computational evidence that the specific biological properties of the CA3 circuit produce an effective neural substrate for associative learning in the mammalian brain. Furthermore, previous studies highlighted the importance of acetylcholine as a neuromodulator in memory formation and retrieval. Therefore, I assessed the dynamics of acetylcholine in the medial septum, the major source of cholinergic modulation for the hippocampal formation, in mice foraging for food in an open environment. Machine learning classification of the movement of mice revealed four distinct behaviors of exploratory running and walking, grooming, and rearing. Linear regression further demonstrated an increase of cholinergic activity in the MS during rearing, when a mouse scans its surroundings on its hindlimbs from an elevated perspective, suggesting a role in encoding information for spatial memories. Taken together, the results of this thesis demonstrate the capability of a biologically realistic SNN of the mouse CA3 to encode and retrieve memories, as well as the utility of deep learning in uncovering correlations between neuromodulation and behavior. These advances afford the community complementary and synergistic opportunities to better understand episodic memory in future studies
Essays on the Economic History of Media
Get PDFThis dissertation explores the causes and consequences of changes in “media,” broadly construed, using causal inference techniques. The first chapter examines the political effects of Confederate monuments in the southern United States, establishing their concrete influence on voting behavior. The second chapter explores the effect of the Black Death pandemic on the adoption of the Gutenberg printing press in 15th century Europe, documenting that market size affects the adoption of capital-intensive forms of production. The third paper investigates the influence of vernacular language Bibles on the explosion of non-Latin printing, demonstrating the power of books to shape language. Chapter one, currently revise & resubmit at Explorations in Economic History, explores the contemporaneous effects of Confederate monuments in the Post-Reconstruction South. I first combine monument, election, and census data to create a panel dataset of monument dedications in former confederate counties between 1878–1912. Then, using a generalized difference-in-differences design, I measure the effect of monument dedications on voting behavior and demographic outcomes. I find that monuments caused increases in Democratic Party vote share, decreases in voter turnout, and decreases in Black population share. I also find varying effects based on the era of monument dedication, the intensity of monument-building, and monument characteristics. Finally, I show that Black out-migration does not explain monuments’ political effects, supporting my argument that monuments influenced the beliefs of the local population. The results have implications for current debates over Confederate monuments in the United States. Chapter two, co-authored with Noel Johnson and Andrew Thomas, leverages plausibly exogenous variation in mortality from the Black Death (1347–52) across European cities to estimate the causal impact of market size on early print adoption. Using the universe of data from the Universal Short Title Catalogue we create a database linking early European printed material to historical city populations. We find that cities whose populations were more heavily impacted by the Black Death were less likely to be early adopters of the press and printed fewer unique book editions. We also provide evidence that beyond own-city mortality there were also spatial spillovers from the Black Death shock. Chapter three explores the impact of vernacular Bible translations on printed language diversity in early modern Europe. Also using data from the Universal Short Title Catalogue, I construct a panel dataset of vernacular Bible printings in European cities from 1450–1650. I then use a generalized difference-in-differences design to assess their effect on the rise of non-Latin printing. I find that vernacular Bibles are associated with increases in vernacular printing on the intensive margin and the ratio of vernacular to Latin output. Increases in vernacular printing are stronger for local vernacular languages than foreign ones, and the findings are robust to data quality tests. The results have implications for our understanding of the rise and standardization of vernacular languages
Social Cognitive Development and Children’s Engagement in Dance: A Mixed Methods Study
No full textThis work is embargoed by the author and will not be publicly available until May 2029.Effects of childhood participation in the arts on social, emotional, and cognitive development has long been of interest to psychological scientists, theorists, artist, philosophers, neuroscientists, and the lay public. Across the three manuscripts, this dissertation looks at the ways in which the embodied and performing arts of theatre and dance are, or are not, connected to a variety of social cognitive skills. The first manuscript reviews and critiques the current state of the literature on children’s engagement across all art forms and their development of critical social, cognitive, and emotional abilities. Connections between childhood participation in the embodied arts, theatre and dance, has received much less attention than other art forms. The ways in which connections between psychological phenomena and children’s art participation have been studied are also limited. More longitudinal and mixed methods studies are needed to fully understand connections children’s development of social, cognitive, and emotional skills and engagement in the arts. The second and third manuscript address these understudied art forms and methodological limitations of the past research and employ mixed methods to examine children’s longitudinal participation in theatre and dance. The second manuscript uses mixed methods to longitudinally examines children’s development of 21st century skills (creativity, problem solving, initiative, communication, and collaboration), as they progress through theatre class programming. The third manuscript quasi-experimentally examines the connections between children’s participation in dance and the development of the critical social cognitive skill, theory of mind, over one academic year. Mixed methods designs are highlighted throughout as an advantageous methodology to examine connections between psychological and artistic phenomena.2029-05-1
BEYOND LINGUISTIC VARIATIONS: TRANSLINGUAL IDENTITIES AND AUDIENCE AWARENESS IN WRITING CONTEXTS
No full textThis work is embargoed by the author and will not be publicly available until May 2029.Despite language in translingual students’ writing being one of many constitutive elements, linguistic variations in their writing have received overwhelming scholarly attention, often overshadowing such fundamental aspects of writing as identity, agency, discourse, or rhetoric. This research is driven by the desire to shift the language-centric conversation of translingual students’ writing to a holistic, ecological approach that views their written communication as a collaborative, meaning-making process with their audiences. The paradigm shift pursued in this study entails two renewed conceptual affordances of translingualism: understanding translingual rhetorical behavior as kairotic inventions and theorizing translingual identity as a verb, inspired by the translingual author’s and three translingual student participants' narratives of their lived experiences of (re)constructing discursive identities across cultural and linguistic boundaries. Centered on the actions and effects of translingual rhetorical behavior, the study places translingual students’ identities at the nexus of culture, language, and rhetoric and theorizes that translingual identity acts like a verb with four key dynamic characteristics: relationality, permeability, agentivity, and performativity. The following question guided the data collection and analysis of the research: How do translingual identities interact with students’ audience awareness in their writing?Based on a case-study method, the research occurred in six stages, collecting three large sets of data from three undergraduate students with diverse cultural and linguistic backgrounds. The data includes eighteen individual interview transcripts, writing samples of various modalities in personal, professional, and academic contexts, and six Zoom-recorded Thinking Aloud Protocols. Through the grounded theory-based coding complemented by the author’s analytical memo writing, the study offers the theoretical and pedagogical significance of appreciating and understanding translingual students’ writing beyond linguistic variations. The findings suggest that translingual students’ interaction with audiences exhibits a dynamic spectrum of context-responsive relational to transactional audience awareness. Furthermore, by complicating the interconnectedness of translingual identities and audience awareness, the study constructs a model that theorizes the dynamic, idiosyncratic, and complex interplay of relationality, permeability, agentivity, and performativity in audience awareness across four categories: culturally and linguistically affiliated audiences, online community audiences, non-academic audiences in print-based forms, and audiences in classrooms. The model presents a nuanced understanding of how translingual students engage with their audiences in various contexts and provides compelling evidence for the importance of enriching students’ writing experience in classrooms, regardless of their language background, by leveraging the sociality of genres and visibilizing non-teacher audiences in their writing.2029-05-1
AI-Augmented Games for Experiential Learning in Emergency Management
Get PDFUtility directors are responsible for ensuring uninterrupted critical services such as power and water, responding to disruptions, recovering normal operations, and make critical decisions during the evacuation phase if necessary. However, they face numerous challenges regarding situational awareness surrounding events such as natural disasters. Key challenges faced by utility personnel involve timely resource allocation and trade-off decisions given limited resources, and comprehending the interdependencies between systems to fully grasp crisis impacts. Despite the availability of computational models designed to enhance infrastructures restoration and evacuation procedures, their adoption in practice has remained limited.
To address this gap, this thesis proposes an innovative approach integrating computational models with serious games allowing for training utility mangers, data collection, and evaluating their strategies through a feedback learning environment. It introduces two distinct games, including Go-Repair for infrastructures restoration and Go-Rescue for flood evacuation decisions. These simulation-based games offer a platform for experiential learning, enabling managers to develop decision-making skills in realistic scenarios during both evacuation and infrastructure restoration phases. This ultimately leads to improved disaster response and mitigation. Utility managers from Arlington County, Virginia, are recruited to assess the effectiveness of these games in improving training outcomes, understanding human decision-making processes throughout the event lifecycle, and creating an interactive learning platform with iterative feedback
Project 3: Bias in Large Language Models (LLMs) for Kidney Transplant Publications
Get PDFObjective: The main objectives of this study are (1) to conduct a comprehensive comparison of the capabilities and limitations in supporting the peer review process of three common LLMs –Llama3, GPT-3.5, and Mistral– and (2) to rank the fairness of the LLMs based on detection of affiliation bias in generated acceptance rates.This project included two student researchers who wish to remain anonymous
Plasma Impedance Tomography
No full textThis work is embargoed by the author and will not be publicly available until May 2026.This dissertation derives the plasma complete electrode model (PCEM), a numerical method for predicting the self- and -mutual impedances of dipoles in a plasma. The PCEM is then used as a forward operator in plasma impedance tomography (PIT), a new method developed in this dissertation, to form cross-sectional images of electron density in plasma. The PCEM extends the analytic work of Balmain from the 1960s on the impedance of dipoles in cold, fluid, magnetized plasma. Balmain’s result was limited to simple dipole geometry such as cylinders and to homogenous plasma. The PCEM assumes the same plasma permittivity derived by Balmain, but uses the finite element method to solve Poisson’s equation numerically. Consequently, the PCEM can be applied to arbitrarily shaped antennas and inhomogeneous plasma. The PCEM has good agreement with both Balmain’s analytic model and experimental data collected in the U.S. Naval Research Laboratory Space Physics Simulation Chamber with a cylindrical dipole impedance probe. During comparisons with experimental data, the PCEM also revealed connections between some features in the impedance spectrum and the plasma sheath around the dipole. To compute tomographic images of plasma density, this dissertation derives the Jacobian of the PCEM. This Jacobian solves a linearized version of the inverse problem associated with the PCEM, predicting plasma density from impedance probe measurements. In the cases studied in this dissertation, the Jacobian is a rank-deficient wide matrix and regularized using truncated singular value decomposition (TSVD). TSVD gives useful insight into the pixel point-spread-functions in the reconstructed image as well as estimates of signal-to-noise ratio based on the magnitudes of the non-zero singular values. This work derives a computationally efficiently method to compute the Jacobian for unmagnetized plasma. A more computationally expensive perturbation method estimates the Jacobian under arbitrary plasma conditions. This dissertation applies PIT to numerical studies of 8- and 12- dipole arrays. Three metrics, signal-to-noise ratio, resolution, and distortion, quantify the performance improvements of the 12-dipole array over the 8-dipole array as well as the impact to performance of rotating the dipoles so they are orthogonal to the imaging plane. Finally, these tools are used to investigate the frequency dependence of PIT, where it is shown that, for a given array and noise floor, and an assumption of an unmagnetized, homogenous background plasma, the array performs better below the plasma frequency.2026-05-1
Design and Characterization of Temporally Controlled Release Hydrogel System Towards Controlling Cellular Response
Get PDFExtracellular matrix (ECM) is a highly complex environment that is composed of both structural and nonstructural components that can influence various biological activities, such as differentiation and proliferation. Given the importance of ECM in biological activities, it is critical to recapitulate its dynamic nature in both in vitro and in vivo environments for various applications from tissue engineering to organ-on-chip models. Hydrogel systems have emerged as potential methods to mimic the ECM due to its tunable mechanical properties and composition. However, hydrogel systems without specific modifications like a controlled release system are unable to replicate the temporal distribution of cytokines found in the native ECM environment. A potential solution is DNA nanotechnology, which allows for the creation of nanostructures that are highly programmable, actuatable with various stimuli, and orthogonal modification with multiplexing of biomolecules. Therefore, we utilized DNA nanotechnology tools, such as multiplex design and toehold-mediated strand displacement reaction, to design a highly tunable control release system with temporal precision and incorporated them within a gelatin-based hydrogel system to fabricate a dynamic hydrogel environment that can be used towards controlling cellular behavior. To achieve this objective, we designed a multi- way DNA nanostructure that was able to be multiplexed up to three different cargos and examined its potential to be used as a temporally controlled release system in both solution and in hydrogel systems. Furthermore, we studied the sequence design rules for toehold- mediated strand displacement reaction and modelled the release properties (quantity and rate) to enable us to further finetune the release profile of the system. Finally, we carried out the proof-of-concept study using our DNA controlled release system modified with biomolecules (TNF-⍺ or IFN-⍺) and it was incorporated within a gelatin methacrylate hydrogel system. Jurkat-Dual cells, a dual reporter gene cell line, were used to examine if this novel dynamic hydrogel system was able to stimulate them. Overall, this work paves the way to the development of novel tissue engineering scaffolds that use DNA nanotechnology to precisely control the temporal release of biomolecules, such as growth factors, cytokines, and chemokines, to further mimic the native ECM environment