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Item Survival of American Kestrels Across Eastern North America and Investigations Into Overlooked Drivers of the Continental Population Decline(2024-05)The American Kestrel, a small falcon species found throughout North America, was once regarded as a common sight in both agricultural and grassland habitats. Since the 1970’s, kestrel abundance has declined in Christmas Bird Counts, Breeding Bird Surveys, and migration counts. While this decline has attracted the attention of many researchers, the driver, or drivers, of this population trend still remains unknown. While much attention has been paid to reproduction, another key life history trait, survival, has received relatively little consideration. Proper survival estimation provides key population demographic information that is essential to understanding potential drivers of population trends. Additionally, survival estimation throughout the full annual cycle and across geographical regions allows researchers to pinpoint when and where mortality occurs and, therefore, where resources should be allocated for potential mitigation and conservation action. This project provides known-fate survival estimates throughout the full annual cycle and within geographically disparate regions, including data on both adult and juvenile American Kestrels. This data is a vast improvement upon our current knowledge of kestrel survival and can help orient future research and conservation efforts towards areas and stages of increased mortality. In the search for potential drivers of the population decline, some drivers have seemingly been “ruled out” due to assumptions about kestrels and their interactions with their environment. In multiple publications, predation of kestrels by Cooper’s hawks has been regarded as an unlikely cause of the kestrel’s population decline, despite Cooper’s hawks being known to predate kestrels and our knowledge of Cooper’s hawk’s increasing population trends that are concurrent with the kestrel’s declining population trends. As these studies focused on the impacts of direct predation by Cooper’s hawks on kestrels, effectively showing that predation events occur too scarcely to limit kestrel populations, they entirely overlooked the nonconsumptive impacts of these species interacting. This project employs an experimental playback framework to simulate the presence of a Cooper’s hawk within a kestrel’s breeding territory. This simulation allows for evaluation of nonconsumptive impacts of Cooper’s hawks on kestrel behavior, nestling development, and survival post-fledge, which this study suggests are all impacted by the Cooper’s hawk presence. Due to their adaptability, habitat change, particularly in the form of urbanization, has also been effectively excluded as a potential cause of the American Kestrel’s decline. Kestrels are currently considered suburban adaptable, suggesting that the species is able to adapt to urbanization and thrive in human-dominated landscapes. While some kestrels live in cities and suburban areas full-time, this title veils the impacts of increased human disturbance, collisions with man-made structures, alterations in prey abundance, and exposure to human-associated toxins on those individuals that are not adapted to these environments. Overwintering migratory individuals may be impacted even more severely by urbanization as they are not necessarily adapted to urban conditions at any other point in their annual cycle. This study investigated the effects of urbanization on American Kestrel abundance and sex ratios by surveying overwintering populations annually in a rapidly urbanized region. Using this long-term dataset provided insight into kestrel population demographics before, during, and after human development, which elucidated that kestrel populations decreased and became more male-dominated in response to urbanization.Item Three Essays on International Cooperation, Central Bank Swap Lines, and Benchmark Interest Rates(2024-05)This dissertation comprises three chapters that contribute to a deeper understanding of the Global Financial Crisis (GFC), the Federal Reserve’s international response, and the U.S. government’s campaign for benchmark interest rate reform, shedding light on the implications for effective monetary policy transmission and the evolving landscape of the international financial system. The first chapter analyzes the role of currency swap lines by the Federal Reserve during the GFC, the European debt crisis, and the Covid-19 crisis. It argues that LIBOR’s integration into the U.S. domestic financial system prompted the revival of swap lines to address eurodollar interbank market dysfunction and influence LIBOR. Empirical analysis reveals that a USD LIBOR panel bank in a foreign central bank’s jurisdiction significantly predicts a dollar swap line extension from the Fed. The essay also argues that LIBOR explains why only certain central banks were granted unlimited drawing access to Fed swap lines and eventually converted into standing arrangements. In the second chapter, an instrumental variable regression is employed to address whether Fed swap line drawings by foreign central banks are responsive to dislocations in the foreign exchange market as proxied by covered interest parity (CIP) deviations versus dislocations in the eurodollar interbank market as proxied by LIBOR. The results indicate little empirical support that swap line drawings significantly respond to CIP deviations but do respond to LIBOR deviations from the Fed funds rate consistent with the narrative of the first essay. The third chapter explores the political economy of international benchmark interest rate reform. The GFC and the LIBOR scandal emphasized the need for reform and new regulatory standards, particularly in monetary transmission mechanisms. U.S. agencies spearheading the reform efforts exercising extraterritorial jurisdiction in prosecuting foreign banks for LIBOR manipulation, effectively discouraging their participation. The reform replaced LIBOR with central bank-administered benchmark reference rates, strengthening monetary control and financial stability. The chapter examines the power dynamics and welfare redistribution resulting from this transition, with the United States benefiting from increased influence over global dollar credit conditions through the widespread adoption of its replacement rate, the secured overnight funding rate (SOFR).Item From Micromotors to Solid Surfactants: Synthesis and Applications of Heterogeneous Polymer Particles(2024-05)Colloid science has classically concerned itself with the investigation of properties of dispersed phases in a bulk medium. This has led to the development of a rich amount of chemistry, physics, and engineering that have facilitated the evolution and maturation of this field. One of the many developments made over the last 30 years is the introduction of colloidal particles that are heterogenous in both chemistry and shape. These heterogeneities can introduce behaviors that are not achievable in homogeneous systems and that are specific to the type and class of nonuniformity. This has led to the development of numerous technologies, two of which are Janus micromotors and solid surfactants. In this dissertation, we will develop new methods to synthesize and characterize these two heterogeneous polymer particle systems. In Chapter 1, we give an overview of the field of heterogeneous particles and techniques one can use to synthesize them. We then discuss the current state of the field for both solid surfactants and Janus micromotors. In Chapter 2 we develop dynamic light scattering as a characterization method to study the bulk three-dimensional active motion of Janus micromotors. From this work we find that dynamic light scattering can successfully characterize the non-steady state bulk active motion of Janus micromotor systems. This work positions dynamic light scattering to become an advanced characterization technique for Janus micromotor systems. In Chapter 3, we study the assembly mechanism of Janus particle solid surfactants at immiscible interfaces using dynamic pendant drop tensiometry. We find that by tuning the properties of the Janus particle that one can simultaneously both the binding energy but also the kinetics of assembly. In Chapter 4, we develop a new dimensionless number termed the active Bond number which can be used to analyze the deformation of immiscible interfaces by active matter and self-propelled colloids. We find that the active bond number is highly successful at predicting deformations for multiple experimental systems and can be broadly useful. We then conclude the dissertation with a summary of work and a future perspective on the fields of heterogeneous particles.Item THE ROLE OF INTRINSICALLY DISORDERED PROTEINS IN THE REGULATION OF CHROMOSOME SEGREGATION(2024-05)Kinetochores connect chromosomes and spindle microtubules to maintain genomic integrity through cell division. The intrinsically disordered kinetochore protein Spc105 (KNL1 in humans) has a well-characterized role as a molecular hub in the spindle assembly checkpoint. Here, we establish an additional role for Spc105 in promotion of accurate chromosome segregation through modulation of attachment stability. We identify a linkage between Spc105 and a poorly understood pathway involving minus-end directed motor dynein and microtubule attachment protein Ndc80. Using optogenetic oligomerization assays to recapitulate to kinetochore in the cytoplasm, we determine that core pools of the checkpoint protein BubR1 and the adaptor complex RZZ contribute to this linkage. Furthermore, a minimal segment of Spc105 with a propensity to multimerize has been identified as the linkage to RZZ and dynein. This region has protein binding motifs that mediate the interactions in this complex and had not been characterized in Drosophila until now. Deletion of the minimal region from Spc105 compromises the recruitment of its binding partners to kinetochores and elevates chromosome missegregation due to merotelic attachments. Restoration of normal chromosome segregation and localization of BubR1 and RZZ requires both the protein binding motifs and oligomerization of Spc105. Together, our results reveal that higher-order multimerization of Spc105 contributes to localizing a core pool of RZZ that promotes accurate chromosome segregation. We additionally demonstrate that the microtubule binding and PP1 binding properties of the N-terminal region of Spc105 are not mutually exclusive, and both can be recruited by the N-terminus of Spc105 in cytosolic oligomers.Item Development of the TolTEC Data Reduction Pipeline and the Application of Hierarchical Bayesian Inference to TolTEC Data(2024-05)TolTEC is a millimeter-wavelength imaging polarimeter now installed on the 50-meter Large Millimeter Telescope that simultaneously maps the sky using 7718 dual- polarization Lumped Element Kinetic Inductance Detectors distributed among three monochromatic arrays, centered at 1.1, 1.4, and 2.0 mm (273, 214, and 150 GHz). The camera is currently in the commissioning phase and has completed two observational runs, in June and December of 2022. This work offers a comprehensive review of the TolTEC data reduction and mapmaking pipeline Citlali (v4.0), an open-source, high-performance, and parallelized software package written in C++. Citlali rapidly transforms the raw time-ordered data from all categories of TolTEC data into two-dimensional maps of the sky, in addition to performing map coaddition and post-mapmaking point source filtering. The pipeline’s design philosophy, data streaming and parallelization model, timestream reduction stages, mapmaking algorithms, and iterative mapmaking routine are detailed. Maps of sources observed during TolTEC’s 2022 commissioning, including the radio quasar J1159+292, the Crab Nebula, and the Monoceros R2 Giant Molecular Cloud, which were produced using Citlali, are presented. The analysis investigates the flux recovery from extended sources by Citlali’s iterative mapmaker and compares results from the built-in mapmakers to maps created with the maximum likelihood mapmaker Minkasi. This work also details a C++ hierarchical Bayesian MCMC software package developed for fitting dust emission SEDs in each pixel of TolTEC maps. This code integrates instrumental PSF data into a forward-fitting model to maintain contributions from higher-resolution observations within the dataset. Both modified blackbody and physically motivated dust models using the Astrodust+PAH model of Hensley and Draine 2023 have been implemented. Results from applying this software to simulated dust SEDs, as well as to WISE, Spitzer, and Herschel observations of the face-on spiral galaxy NGC 3938, are presented.
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