Essays on the identification of treatment effects with applications to the labor market

This dissertation contains three independent essays; each essay can be read in isolation. The first essay investigates the causal effect of criminal convictions on various labor market outcomes in young adults. The estimation method used is a nonparametric bounding approach intended to partially identify the causal effect. The data used for this essay comes from the 1997 National Longitudinal Survey of the Youth. The second essay reevaluates the causal effect of post-secondary schooling on unemployment incidence using historical data from the 1980 U.S. Census and information on cohort level Vietnam War conscription risk. Conscription risk is used as an instrument for endogenous post-secondary schooling in a specification that accounts for the discrete nature of the treatment and outcome of interest. The third essay investigates the underlying necessary assumptions needed for the monotone instrumental variable (MIV) assumption to have identifying power on both the upper and lower bounds of a treatment effect when the treatment of interest is binary. I show that if the treatment is monotonic in the instrument, as is routinely assumed in the literature on instrumental variables, then for the MIV to have identifying power on both the lower and upper bounds of the treatment effect, the conditional-on-received-treatment outcomes cannot exhibit the same monotonicity assumed by the MIV. Results are highlighted with an application investigating the effect of criminal convictions on job match quality using data from the 1997 National Longitudinal Survey of the Youth

Semantic and global irrealism

2010 Summer.Includes bibliographic references (pages 77-82).Covers not scanned.Print version deaccessioned 2022.This thesis is concerned with skepticism about linguistic meaning and the consequences that follow from this view. After clarifying various positions that support skepticism about meaning - broadly classified under the umbrella term semantic irrealism - I weave a common thread through these different characterizations and use that formulation for the remainder of the thesis. In chapter two I examine the premises for the argument that semantic irrealism globalizes to the conclusion that no sentence is substantially true. After evaluating attempts found within the literature to block this inference, I argue that it cannot be blocked in the ways considered. Chapter three is a response to objections that the global irrealist position is both incoherent and unstable. I argue that it is neither and conclude that if semantic irrealism is the case, then this necessarily entails global irrealism

Preventing Neonatal Abstinence Syndrome within the Opioid Epidemic: A Uniform Facilitative Policy

The United States is currently in the midst of an opioid epidemic that has hit states in the southern New England regions particularly hard — with Massachusetts as one primary example. One of the many unfortunate results of the epidemic is a dramatic upsurge in cases of opioid dependency by expectant women that result in children born with Neonatal Abstinence Syndrome (NAS). NAS is a clinical syndrome that occurs when a newborn suffers withdrawal symptoms as a consequence of abrupt discontinuation of prenatal substance exposure. The expenses of treating and rehabilitating these drug-dependent newborns, predominantly shouldered by state taxpayers, are extremely costly, with a mean cost per stay of $93,400 for pharmacologically-treated cases. This Article illustrates a policy, grounded in facilitative principles, designed to reduce incidents of NAS. Key components to the solution’s success should rely on early identification of opioid abuse or dependence during pregnancy, as well as adherence to a standardized protocol implemented uniformly throughout public hospitals state-wide. The Article concludes by reemphasizing the importance of acting promptly and assertively to protect society’s most vulnerable members from the tragic epidemic

Computationally Relaxed Locally Decodable Codes, Revisited

We revisit computationally relaxed locally decodable codes (crLDCs) (Blocki et al., Trans. Inf. Theory '21) and give two new constructions. Our first construction is a Hamming crLDC that is conceptually simpler than prior constructions, leveraging digital signature schemes and an appropriately chosen Hamming code. Our second construction is an extension of our Hamming crLDC to handle insertion-deletion (InsDel) errors, yielding an InsDel crLDC. This extension crucially relies on the noisy binary search techniques of Block et al. (FSTTCS '20) to handle InsDel errors. Both crLDC constructions have binary codeword alphabets, are resilient to a constant fraction of Hamming and InsDel errors, respectively, and under suitable parameter choices have poly-logarithmic locality and encoding length linear in the message length and polynomial in the security parameter. These parameters compare favorably to prior constructions in the poly-logarithmic locality regime

Pulsational Analysis of the Cores of Massive Stars and its Relevance to Pulsar Kicks

The mechanism responsible for the natal kicks of neutron stars continues to be a challenging problem. Indeed, many mechanisms have been suggested, and one hydrodynamic mechanism may require large initial asymmetries in the cores of supernova progenitor stars. Goldreich, Lai, & Sahrling (1997) suggested that unstable g-modes trapped in the iron (Fe) core by the convective burning layers and excited by the $\epsilon$-mechanism may provide the requisite asymmetries. We perform a modal analysis of the last minutes before collapse of published core structures and derive eigenfrequencies and eigenfunctions, including the nonadiabatic effects of growth by nuclear burning and decay by both neutrino and acoustic losses. In general, we find two types of g-modes: inner-core g-modes, which are stabilized by neutrino losses and outer-core g-modes which are trapped near the burning shells and can be unstable. Without exception, we find at least one unstable g-mode for each progenitor in the entire mass range we consider, 11 M_{\sun} to 40 M_{\sun}. More importantly, we find that the timescales for growth and decay are an order of magnitude or more longer than the time until the commencement of core collapse. We conclude that the $\epsilon$-mechanism may not have enough time to significantly amplify core g-modes prior to collapse.Comment: 32 pages including 12 color figures and 2 tables, submitted to Ap

Universal Cyclic Topology in Polymer Networks

Polymer networks invariably possess topological defects: loops of different orders which have profound effects on network properties. Here, we demonstrate that all cyclic topologies are a universal function of a single dimensionless parameter characterizing the conditions for network formation. The theory is in excellent agreement with both experimental measurements of hydrogel loop fractions and Monte Carlo simulations without any fitting parameters. We demonstrate the superposition of the dilution effect and chain-length effect on loop formation. The one-to-one correspondence between the network topology and primary loop fraction demonstrates that the entire network topology is characterized by measurement of just primary loops, a single chain topological feature. Different cyclic defects cannot vary independently, in contrast to the intuition that the densities of all topological species are freely adjustable. Quantifying these defects facilitates studying the correlations between the topology and properties of polymer networks, providing a key step in overcoming an outstanding challenge in polymer physics.National Science Foundation (U.S.) (Award DMR-1253306

Effect of Concept Cartoons on Kindergarten Pupils’ Numeracy and Science Performance in Sagnarigu-Tamale, Ghana

This study sought to establish the effect of Concept Cartoons on Kindergarten Pupils’ Numeracy and Science Performance at a demonstration primary school in Sagnarigu-Tamale, Ghana using the experimental research design. The population of the study was 100 KG-2 A and B Pupils in the school. A purposive sampling technique was used to select an intact class of 58 pupils that had difficulty in participation and performance in natural science and numeracy. A pre-test was conducted to determine the initial performance of pupils before the intervention that was done through teaching with the support of the concept cartoons. The analysis of the first two objectives involved mean scores and standard deviation. Pre-test and post-test scores were analysed to address the two objectives. The study established that the use of concept cartoons significantly improved the pupils’ achievement in natural science and numeracy lessons. Therefore, the use of concept cartoons as a teaching aid is a powerful approach to improve the performance of pupils in sciences and numeracy. The study recommended that teachers of sciences and numeracy in early primary education ought to use the concept cartoon approach in order to improve the performance of pupils in the s

Locally Decodable/Correctable Codes for Insertions and Deletions

Recent efforts in coding theory have focused on building codes for insertions and deletions, called insdel codes, with optimal trade-offs between their redundancy and their error-correction capabilities, as well as efficient encoding and decoding algorithms. In many applications, polynomial running time may still be prohibitively expensive, which has motivated the study of codes with super-efficient decoding algorithms. These have led to the well-studied notions of Locally Decodable Codes (LDCs) and Locally Correctable Codes (LCCs). Inspired by these notions, Ostrovsky and Paskin-Cherniavsky (Information Theoretic Security, 2015) generalized Hamming LDCs to insertions and deletions. To the best of our knowledge, these are the only known results that study the analogues of Hamming LDCs in channels performing insertions and deletions. Here we continue the study of insdel codes that admit local algorithms. Specifically, we reprove the results of Ostrovsky and Paskin-Cherniavsky for insdel LDCs using a different set of techniques. We also observe that the techniques extend to constructions of LCCs. Specifically, we obtain insdel LDCs and LCCs from their Hamming LDCs and LCCs analogues, respectively. The rate and error-correction capability blow up only by a constant factor, while the query complexity blows up by a poly log factor in the block length. Since insdel locally decodable/correctble codes are scarcely studied in the literature, we believe our results and techniques may lead to further research. In particular, we conjecture that constant-query insdel LDCs/LCCs do not exist