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Optimizing for Commercial Solar Profitability in Washington DC: A Geospatial-Economic Analysis
Get PDFThis research examined the optimization of commercial solar development in Washington, D.C., through an integrated analysis of geographic-dependent federal incentives and financial returns. Using ArcGIS Pro 3.3 and Monte Carlo simulation techniques, the study combined geospatial modeling of solar radiation potential with stochastic economic analysis to identify optimal project locations and quantify investment returns. The research analyzed the impact of the Inflation Reduction Act's Investment Tax Credit (ITC) bonus adders, which could elevate federal incentives from 30% to 60% in qualifying census tracts, alongside Washington D.C.'s Solar Renewable Energy Credit (SREC) market. Geospatial analysis revealed that 44.8% of the city's census tracts qualified for ITC bonus incentives, with Ward 8 containing the highest concentration of eligible locations. A 5,000-iteration Monte Carlo simulation demonstrated robust project economics, with 80% of scenarios yielding equity IRRs between 32% and 58%. While federal incentives significantly impacted project economics, the research found that local SREC markets drove greater value than ITC benefits. This analysis provided actionable insights for developers and policymakers working to expand commercial solar capacity in urban environments while managing regulatory and market uncertainties
Comparing Automated and Manual Bat Call Identification: Impacts on Bat Activity
Get PDFAcoustic monitoring is a vital tool for assessing bat activity and distribution, but the choice of call identification method can significantly influence results. This study evaluates the effects of three identification methods—automated identification without any filtering, automated identification with a Maximum-Likelihood-Estimate (MLE) filter of 0.85, and manual vetting—on bat call counts from the Midwest Bat Hub's 2022 volunteer monitoring program dataset. Using generalized linear mixed models, we analyzed species-specific activity for 12 bat species commonly observed in the Midwest. We employed generalized linear mixed models with random effects to account for spatial and temporal variability, emphasizing the need for appropriate model structures tailored to the characteristics of each species' data. Our findings reveal that identification method influenced call counts for four species. For gray bats (Myotis grisescens), only manual vetting resulted in statistically significant reductions in call counts, highlighting the potential overestimation of activity by automated methods. For little brown bats (Myotis lucifugus) and Indiana bats (Myotis sodalis), both the MLE filter and manual vetting significantly reduced call counts, suggesting that these methods are necessary to address potential false positives. For tri-colored bats (Perimyotis subflavus), the MLE filter yielded the largest reduction in call counts, though manual vetting also produced significant decreases. These results underscore the importance of species-specific data processing in acoustic monitoring. In the Midwest, prioritizing manual vetting for Myotis species and the tricolored bat is recommended to enhance the accuracy of activity estimates. If resources are limited, focusing manual vetting efforts on these taxa can optimize accuracy while balancing workload
DIGNIFIED DECARBONIZATION: ENSURING FOSSIL FUEL WORKERS THRIVE IN AMERICA’S GREEN FUTURE
Get PDFMany factors threaten a successful transition to a decarbonized American society, with one of the most enduring being a resonant rebuke of climate policy by many fossil fuel workers and their surrounding communities. These groups, often subconsciously, may cloak their economic anxieties as climate denialism or apathy, resisting attempts by climate policy advocates to reengineer the economy for fear of being left behind. Reframing climate policy as chiefly a worker-focused economic policy through a broad and progressive just transition policy platform can address the root cause of such determined
political opposition while capacitating clean energy industries to pilfer highly sought skilled labor from competing fossil fuel employers. Additionally, targeted protections for fossil fuel workers, from relocation and education assistance to compensation gap guarantees, strengthen the existing wafer-thin social safety net for vulnerable workers seeking, but still hesitant, to transition.
Reflecting the multifaceted nature of a just transition, this analysis has multiple objectives. First, it identifies structural economic issues that undermine broad bipartisan political support for decisive climate action in the US among fossil fuel workers and fossil fuel-producing communities. Secondly, it explores and clarifies frameworks to address those structural issues and how they can be implemented, with broad political support from a unified coalition of Americans, including the labor movement. This study and the proposed Dignified Decarbonization Act it inspires offer practical and evidence-based guidance for climate policy advocates, policymakers, labor unions, and clean energy and infrastructure employers as they navigate the green transition
Patterns and predictors of less healthy beverage consumption during infancy and early childhood
Get PDFBeverages constitute a significant portion of the infant and young child’s daily caloric intake and vary widely in their healthfulness. This research focuses on two critical exposures or environments from birth to age five years that may impact beverage intake: breastfeeding and care outside of the home in early care and education (ECE) settings. In the first study, I examine longitudinal associations between breastfeeding and consumption of juice and sugar-sweetened beverages (SSBs) from birth to age one year within the Nurture study, a birth cohort from the Southeastern US comprised of 666 mother-child dyads. During any given month, breastfed infants had a 37% lower incidence rate of weekly juice consumption and a 57% lower incidence rate of weekly SSB consumption, compared to infants who were not breastfed. In the second study, I characterize beverage consumption in ECE between 2008 – 2020 among 4,457 children in 846 facilities across multiple US regions. In this study, children younger than two years had the following probabilities of consuming each beverage, respectively: 95.2% any milk, 49.2% water, 42.1% 100% juice, and 10.1% SSBs. These children consumed a mean daily 4.9 oz. milk, 2.7 oz. water, 2.2 oz. 100% juice, and 2.7 oz. SSBs. Children ages two to five years had a 96.2% probability of consuming any milk, 7.6% water, 7.9% 100% juice, and 5.6% SSBs. They consumed a mean daily 6.7 oz. milk, 3.3 oz. water, 4.0 oz. 100% juice, and 4.5 oz. SSBs. In the final study, I project shifts in dietary intake and food costs that would result from replacing 100% fruit juice in ECE with whole fruit, under a variety of plausible replacement scenarios. Across all scenarios, children’s daily calories decreased between 8.2 – 27.3 kcals, sugar decreased between 3.4 – 5.6 grams, and fiber increased between 0.5 – 1.3 grams. Replacing juice with whole fruit in ECE will likely increase per-child daily food costs between $0.44 – 0.49. Findings from these studies expand our understanding of early life correlates of beverage consumption and provide policy-relevant data to inform public health interventions to improve young children’s beverage consumption
ENHANCE STUDENT MOTIVATION TO REDUCE ATTRITION
Get PDFDefense Language Institute Foreign Language Center (DLIFLC) faced high student attrition, with approximately 20% of its military students disenrolled annually from 2012 to 2024. The study used ecological systems theory as the theoretical framework to identify and organize factors contributing to student attrition. The study investigated how motivation, student–teacher relationships, peer relationships, the learning environment, and learning strategies contributed to military language learner attrition at DLIFLC. This study employed a mixed-methods approach, collecting qualitative data through semi-structured interviews with military students, civilian faculty members, and military language instructors. Pre-existing data were analyzed to explore how peer relationships, student–teacher relationships, and the learning environment affected learner motivation, and how motivation and learning strategies contributed to military language learner attrition at DLIFLC. Four key findings were identified. Students described their motivation for learning as multifaceted and primarily positively influenced by intrinsic motivation, extrinsic motivation, academic goals, academic achievement, personal growth, student–teacher relationships, peer relationships, and the learning environment. Students’ motivation fluctuated throughout the course. Although quantitative data from the Motivated Strategies for Learning Questionnaire did not show a significant relationship between motivation and student learning outcomes, qualitative data indicated that students’ motivation levels significantly affected their successful completion of the language program. Interviews revealed substantial influences of both positive and negative learning environments on student motivation, commitment, and learning outcomes. Students who used a broader range of strategies across multiple categories and implemented them consistently and effectively achieved higher learning outcomes and program completion
ESSAYS ON THE ECONOMICS OF BANK DEPOSITS
Get PDFThese essays study bank deposits and their implications for bank behavior and monetary policy. Chapter one examines, theoretically and empirically, the impact of deposits on banks’ balance-sheet composition. I propose a novel mechanism where a bank’s wholesale borrowing constraint determines the effect of deposits on the bank. Unconstrained banks treat deposits and wholesale funding as substitutes. However, deposits relax the wholesale borrowing constraint because deposits are effectively subordinate to wholesale debt. Thus for constrained banks, deposits and wholesale funding can be complements. For such banks, an increase in deposits enables them to borrow more aggressively from wholesale creditors and hence issue more loans. Empirically, using the cross-sectional variation in deposit fluctuations driven by monetary policy rate changes, I estimate the causal effect of deposits on banks’ balance-sheet composition. The empirical evidence supports the model predictions.
Chapter two examines empirically banks’ risk-taking incentives during periods of low interest rates. Banks have deposit franchises that allow them to charge a markup on customers’ deposits. Whited, Y. Wu, and Xiao (2021) suggest that when interest rates are low, markups and therefore bank profits are squeezed. This profit reduction, combined with limited liability, can induce banks to bear greater risks. This study examines how the zero-lower-bound period changed the markups, bank profitability, and risk-taking behavior, and identifies a causal relation. The evidence reveals that a combination of heavy reliance on deposit markets and low capitalization prior to the zero-lower-bound period leads to additional risk-taking by banks.
In chapter three, we study the effect of e-money on monetary policy transmission. Case studies of e-money regulations point to complementarity of e-money issuers with banks, implying that the development of e-money could deepen financial intermediation and strengthen monetary policy transmission. Exploring panel data, this paper finds that e-money development has accompanied stronger monetary policy transmission and growth in bank deposits and credits. Evidence is more pronounced in countries where e-money development takes off in a context of limited financial inclusion. This paper highlights the potential benefits of e-money development in strengthening monetary policy transmission, especially in countries with limited financial inclusion
Adaptive Planning for Robot Teams: Deep Reinforcement Learning in Dynamic Environments
Get PDFThe primary focus of this research is to study the use of deep reinforcement learning with Graph Neural Networks (GNN) for Multi-Agent Path Finding (MAPF) applications. In this study, the real-world environment is mapped to a topological graph with dynamic edge weights. Various solutions to this problem exist, providing both sub-optimal and optimal solutions. However, a majority of these methods become computationally expensive as the number of nodes and agents increases. Some of these solutions exceed human-level performance in complex tasks but are specific to a chosen environment. The objective of MAPF problems is to minimize a collective cost and reach a final goal. In this study, we propose a novel agent network formulation using graph neural networks that is independent of the number of agents in the environment and the graph topology. This makes the network capable of
generalizing to various dynamic situations. Deep Q-learning is used to train this central multi-agent network, which is then tested on various dynamic graphs. We compare the results and computation time of our solution with a mixed-integer program framework aimed at solving a similar problem
CUBA’S DIGITAL REVOLUTION: THE IMPACT OF INTERNET ACCESS ON CIVIL SOCIETY IN CUBA
Get PDFThis dissertation questions to what extent and why does the introduction and diffusion of internet usage by civil societies in authoritarian countries lead to collective action in the pursuit of political liberalization. Does the internet offer repressed citizens an arena to network? Does that online networking ultimately lead to action offline? This dissertation applies these questions to Cuba, where access to the internet was extremely limited prior to 2014. The ability to get online, especially in Havana, grew rapidly thereafter.
This dissertation is built around longform interviews with 32 subjects. 22 subjects are younger Cubans, between the ages of 20 and 40, active on the internet in the years between 2014 and 2023. Ten of these subjects were interviewed on multiple occasions, first in the years immediately following the arrival of the internet, and then again in the 2020s. An additional nine interviews were conducted with members of civil society communities active in the 1990s that explicitly pursued liberalization. By considering these subjects’ experiences in an era prior to internet access, I attempt to bolster argumentation connecting digital tools to civil society activization in modern day Cuba.
This dissertation finds that the introduction and diffusion of the internet in Cuba played a critical role in enabling acute moments of collective action to promote political liberalization. Cubans suddenly had an arena for civil society that did not exist in an offline capacity. Initially, that opportunity was mostly exercised for social ends. But these communities held a latent power hidden in the thick, overlapping networks of young Cubans who shared interests and trust. These networks emerged as arenas for debate and regime criticism. That debate, having emerged online, resulted in offline action. However, this dissertation also finds that this collective action did not succeed in producing either regime liberalization or democratization. Whereas the internet has the capacity to spark intense, spontaneous moments of civil protest, these moments have proved difficult to sustain, instead affording the regime an opportunity to react and suppress
TEMPORAL CHANGES IN HIV AND HCV PREVENTION AND HARM REDUCTION EFFORTS AMONG PEOPLE WHO INJECT DRUGS IN BALTIMORE, MARYLAND
No full textBackground: The opioid epidemic and the COVID-19 pandemic induced structural and social changes that may jeopardize efforts to eliminate HIV and HCV infection. This dissertation examines temporal changes in HIV and HCV prevention and harm reduction efforts as well as HIV and HCV seroincidence among people who inject drugs (PWID), both before and during the opioid epidemic, and assesses changes in the use of medications for opioid use disorder (MOUD) and support services among PWID before and during the COVID-19 pandemic.
Methods: This multi-method study was conducted among community-recruited PWID in Baltimore, Maryland that were enrolled in the AIDS Linked to the IntraVenous Experience (ALIVE) cohort study. Temporal trends in combination HIV and HCV prevention efforts and seroincidence were examined between January 1988 to December 2019 using semi-annual ALIVE survey visit data collected from 5,506 participants. Qualitative data from the Covid Health And Network Group Experience Study (CHANGES) nested within the ALIVE cohort, which included data from 28 in-depth interviews conducted between July 2021 and February 2022 with PWID, explored how structural and social changes due to the COVID-19 pandemic influenced individual-level experiences with MOUD and support service utilization. Finally, temporal changes in engagement in treatment with MOUD and support services were examined before versus during the COVID-19 pandemic using an interrupted-time series approach among 780 PWID in the ALIVE study between December 2015 to November 2022.
Results: Before the COVID-19 pandemic, we observed substantial increases in the combination HIV and HCV prevention efforts, including increases in methadone use from 14% in 1993 to 44% in 2019, but gaps in service coverage still remained in 2019. Between 1988-1992 and 2017-2019, there was a 97% reduction in HIV seroincidence. While HCV seroincidence also initially declined, HCV seroincidence in 2017-2019 was similar to levels in 1988-1992 after adjustment for demographic characteristics (IRR=1.25 [95%CI=0.64-2.45]). Following the onset of the COVID-19 pandemic, there were many structural and social changes that created new barriers and facilitators to engagement in methadone use and related support services. Namely, pandemic-related changes in methadone dispensation policies and practices, such as increased flexibilities for take-home methadone doses, temporarily served as facilitators of methadone engagement. Some drug treatment programs were closed because of the pandemic and others newly offered telehealth services, such as for support group meetings. However, the quality of both in-person and virtual support group meetings during the pandemic were not favorably viewed by participants, further hindering their engagement in support services. At a population-level, the onset of the COVID-19 pandemic was associated with an immediate reduction in attending group counseling/support services (13.1% [95%CI=17.4%,8.6%]) as well as a negative impact on the trajectory of attending them. In contrast, there were limited changes in buprenorphine use or methadone use associated with the pandemic; however, methadone use declined over time, starting just before the pandemic.
Conclusions: Before the COVID-19 pandemic, there were substantial gains in the control of the HIV epidemic among PWID in Baltimore, whereas HCV transmission was rampant in this population. The COVID-19 pandemic disrupted engagement in drug treatment and related services; however, structural adaptations including to service delivery helped mitigate its impact on the use of MOUD. This highlights the resiliency of the health system to a large societal disruption and that positive structural changes can protect the health of PWID during societal disruptions and in everyday practice. Programs should focus on expanding the coverage of combination HIV and HCV prevention efforts among PWID, with special emphasis on MOUD as it also has implications for mitigating other drug-related harms (i.e., the overdose crisis)
MECHANISTIC STUDIES OF EXOSOME BIOGENESIS AND ENGINEERING
No full textExosomes are small, single-membrane vesicles of ~30-150 nm in diameter that share the same topology as the cell and are enriched in exosome marker proteins. Exosomes are enriched in a relatively small subset of selected proteins and lipids, and also contain cell-derived RNAs and carbohydrates. Exosomes play important roles in quality control, regulation of the extracellular environment, and intercellular communication, and participate numerous physiological and disease processes. Exosomes and other extracellular vesicles have high potential in diagnostics, as they carry signs of health and disease into the plasma. Furthermore, exosomes have high potential as vehicles for drug and vaccine delivery. My thesis studies add significantly to our understanding of exosome biogenesis by showing that exosomal proteins bud primarily from the plasma membrane, which also informs our ability to load vaccine and therapeutic proteins into the exosome surface and lumen