Essays in Applied Microeconomics

The first chapter examines the role that same-sex marriage legalization had on the number of adoptions of children from foster care in the United States. We do so by employing a synthetic difference-in-differences estimator which leverages both the differential timing of these laws across states and the subsequent wave of state-level legal protections which give foster-care agencies the right to deny service to same-sex couples based on religiously-held beliefs. Using highly detailed, county-level data of nearly 20 million children in the foster care system from 1995-2020, our findings reveal that same-sex marriage legalization led to a 3.8%-5.9% increase in the annual number of adoptions. We show that this is driven by an asymmetric substitution in the composition of adoptive household types away from unmarried couples and single women and towards recognized families. Back-of-the-envelope calculations suggest that 1) same-sex marriage indirectly caused an additional 10,000- 17,500 additional adoptions within an average four-year time window after its passage and 2) that there would have been 2,900-4,500 more adoptions from 2016 to 2019 without laws which grant foster-care agencies the right to refuse service to same-sex couples. The second chapter examines the role that teacher union strength played in the reopening decisions of public schools in Connecticut throughout the ’20-’21 academic school year. To do so, I construct a measure of union strength that combines the number of pages in a union’s collective bargaining agreement with a text analysis that measures the expansiveness of their contract’s leave policies. I find that school districts with strong unions were less likely to offer in-person classes throughout the 2020-2021 academic year. However, this effect becomes insignificant when accounting f or t he local incidence of COVID-19. Instead, I find that differences in the vote share for the Democratic presidential nominee of 2020 and the number of COVID-19 cases were stronger predictors of reopening decisions. The results contradict the consensus within the literature that unions and political attitudes prevented schools from reopening. These results suggest that using more geographically granular data and a longer time horizon to define reopening decisions describes the differences in results. The third chapter examines the effect of negative health shocks on the retirement decisions of peers. I do so by gathering detailed data on players from the National Football League (NFL) from 1980-2019. The introduction and advancement of research into chronic traumatic encephalopathy (CTE), coupled with increasing early-life mortality among NFL players, has significantly increased the salience of American football’s long-term negative health effects. I exploit the quasi-random timing of early-life, CTE-related mortality of both former and current players on the retirement decisions of their teammates. I demonstrate that these players are significantly more likely to retire than comparable peers in the seasons following one of these deaths. This magnitude of this effect larger for players with fewer years of college attendance, but is uncorrelated with the amount of time shared as teammates

A suboptimal 5' splice site downstream of HIV-1 splice site A1 is required for unspliced viral mRNA accumulation and efficient virus replication

BACKGROUND: Inefficient alternative splicing of the human immunodeficiency virus type 1(HIV-1) primary RNA transcript results in greater than half of all viral mRNA remaining unspliced. Regulation of HIV-1 alternative splicing occurs through the presence of suboptimal viral 5' and 3' splice sites (5' and 3'ss), which are positively regulated by exonic splicing enhancers (ESE) and negatively regulated by exonic splicing silencers (ESS) and intronic splicing silencers (ISS). We previously showed that splicing at HIV-1 3'ss A2 is repressed by ESSV and enhanced by the downstream 5'ss D3 signal. Disruption of ESSV results in increased vpr mRNA accumulation and exon 3 inclusion, decreased accumulation of unspliced viral mRNA, and decreased virus production. RESULTS: Here we show that optimization of the 5'ss D2 signal results in increased splicing at the upstream 3'ss A1, increased inclusion of exon 2 into viral mRNA, decreased accumulation of unspliced viral mRNA, and decreased virus production. Virus production from the 5'ss D2 and ESSV mutants was rescued by transient expression of HIV-1 Gag and Pol. We further show that the increased inclusion of either exon 2 or 3 does not significantly affect the stability of viral mRNA but does result in an increase and decrease, respectively, in HIV-1 mRNA levels. The changes in viral mRNA levels directly correlate with changes in tat mRNA levels observed upon increased inclusion of exon 2 or 3. CONCLUSION: These results demonstrate that splicing at HIV-1 3'ss A1 is regulated by the strength of the downstream 5'ss signal and that suboptimal splicing at 3'ss A1 is necessary for virus replication. Furthermore, the replication defective phenotype resulting from increased splicing at 3'ss A1 is similar to the phenotype observed upon increased splicing at 3'ss A2. Further examination of the role of 5'ss D2 and D3 in the alternative splicing of 3'ss A1 and A2, respectively, is necessary to delineate a role for non-coding exon inclusion in HIV-1 replication

From Frictional to Viscous Behavior: Three Dimensional Imaging and Rheology of Gravitational Suspensions

We probe the three dimensional flow structure and rheology of gravitational (non-density matched) suspensions for a range of driving rates in a split-bottom geometry. We establish that for sufficiently slow flows, the suspension flows as if it were a dry granular medium, and confirm recent theoretical modeling on the rheology of split-bottom flows. For faster driving, the flow behavior is shown to be consistent with the rheological behavior predicted by the recently developed "inertial number approaches for suspension flows.Comment: 5 pages, 4 figures, accepted for Phys. Rev. E. (R

High-speed electrochemical imaging

The design, development, and application of high-speed scanning electrochemical probe microscopy is reported. The approach allows the acquisition of a series of high-resolution images (typically 1000 pixels μm–2) at rates approaching 4 seconds per frame, while collecting up to 8000 image pixels per second, about 1000 times faster than typical imaging speeds used up to now. The focus is on scanning electrochemical cell microscopy (SECCM), but the principles and practicalities are applicable to many electrochemical imaging methods. The versatility of the high-speed scan concept is demonstrated at a variety of substrates, including imaging the electroactivity of a patterned self-assembled monolayer on gold, visualization of chemical reactions occurring at single wall carbon nanotubes, and probing nanoscale electrocatalysts for water splitting. These studies provide movies of spatial variations of electrochemical fluxes as a function of potential and a platform for the further development of high speed scanning with other electrochemical imaging techniques

Biology and Clinical Significance of Virulence Plasmids in Salmonella Serovars

Non-typhoid Salmonella strains containing virulence plasmids are highly associated with bacteremia and disseminated infection in humans. These plasmids are found in Salmonella serovars adapted to domestic animals, such as Salmonella dublin and Salmonella choleraesuis, as well as in the widely distributed pathogens Salmonella typhimurium and Salmonella enteritidis. Although virulence plasmids differ between serovars, all contain a highly conserved 8-kb region containing the spv locus that encodes the spvR regulatory gene and four structural spvABCD genes. Studies in mice suggest that the spv genes enhance the ability of Salmonella strains to grow within cells of the reticuloendothelial system. The spv genes are not expressed during exponential growth in vitro but are rapidly induced following entry of Salmonella strains into mammalian cells, including macrophages. Transcription of the spv genes is controlled by the stationary-phase (T factor RpoS, and mutations in RpoS abolish virulence. These studies suggest that the ability of Salmonella strains to respond to starvation stress in the host tissues is an essential component of virulenc

Permission to exist *

Abstract We provide a new model that generates persistent performance differences amongst seemingly similar enterprises. Our model provides a mechanism whereby efficient incumbent rivals can give permission for an inefficient firm to exist in the presence of efficient entrants. We demonstrate that, in a repeated game, an efficient incumbent has a unilateral incentive to establish a relational contract that softens price competition to either strengthen the inefficient firm in a war of attrition that emerges post-entry or reduce the value to the inefficient firm of selling its position to entrants. The paper provides conditions under which that equilibrium exists and derives a number of empirical predictions as implications of the model. It is demonstrated that performance differences are likely to be associated with stability in the identity of firms in the market

Photometric Supernova Cosmology with BEAMS and SDSS-II

Supernova cosmology without spectroscopic confirmation is an exciting new frontier which we address here with the Bayesian Estimation Applied to Multiple Species (BEAMS) algorithm and the full three years of data from the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SN). BEAMS is a Bayesian framework for using data from multiple species in statistical inference when one has the probability that each data point belongs to a given species, corresponding in this context to different types of supernovae with their probabilities derived from their multi-band lightcurves. We run the BEAMS algorithm on both Gaussian and more realistic SNANA simulations with of order 10^4 supernovae, testing the algorithm against various pitfalls one might expect in the new and somewhat uncharted territory of photometric supernova cosmology. We compare the performance of BEAMS to that of both mock spectroscopic surveys and photometric samples which have been cut using typical selection criteria. The latter typically are either biased due to contamination or have significantly larger contours in the cosmological parameters due to small data-sets. We then apply BEAMS to the 792 SDSS-II photometric supernovae with host spectroscopic redshifts. In this case, BEAMS reduces the area of the (\Omega_m,\Omega_\Lambda) contours by a factor of three relative to the case where only spectroscopically confirmed data are used (297 supernovae). In the case of flatness, the constraints obtained on the matter density applying BEAMS to the photometric SDSS-II data are \Omega_m(BEAMS)=0.194\pm0.07. This illustrates the potential power of BEAMS for future large photometric supernova surveys such as LSST.Comment: 25 pages, 15 figures, submitted to Ap