Three Essays on Public Economics and Policy

This dissertation studies the effects of public programs that target at disadvantaged population. In particular, I examine the effects of these programs on individual well-being and whether these programs lead to behavior distortions. The dissertation consists of three essays that focus on different policy contexts and different populations. In the first essay, I examine the effects of an active labor market program on the labor market outcomes of veterans. In the 1990s, the US Department of Defense implemented the Transition Assistance Program (TAP) to help military personnel transition to the civilian labor market. The program provides career counseling, employment workshops, and information briefing on educational and medical benefits through the Department of Veterans Affairs. The goal of this study is to measure the long-run effects of TAP on the labor market outcomes of veterans. To identify these effects, I exploit variation in program accessibility generated by its initial rollout process. Using data from the veterans supplement to the Current Population Survey, survey years 2001, 2003 and 2005, I find that TAP improves the labor market outcomes of veterans, measured approximately ten years after their separation from the military. The effects of TAP on labor market outcomes vary across veterans with different lengths of military experience, and these effects attenuate over time. One possible mechanism is that TAP encourages use of the GI Bill, a program that provides tuition reimbursement and a monthly allowance to attend institutions of higher education. Moreover, the effect of TAP is concentrated among participants who, based on self-reports, find TAP most helpful in career related services. In the second essay, I examine linkages between Medicaid availability, insurance coverage for pregnant women, use of prenatal care and the health outcomes of newborns. Medicaid coverage for pregnant women would potentially improve health outcomes of newborns by providing medical services at no cost. At the same time, Medicaid provides an incentive for eligible individuals to drop private insurance coverage. I exploit variation from two federal Medicaid expansions in mid-1980s, which eliminated the eligibility discontinuity across age groups. The main data come from the National Hospital Discharge Survey and the Vital Statistics Birth Records. I employ a difference-in-differences method. Findings suggest that the expansions led to a relative increase in Medicaid coverage for women from the immediately affected age group by a significant 6.5 percentage points. However, up to 60% of new beneficiaries would have been covered by private insurance, absent of the expansions. Findings do not reveal significant improvement in birth outcomes, or increase in prenatal care utilization. In the third essay, I examine the effect of Medicaid on the asset holding behavior of the elderly. Medicaid provides coverage for nursing home care to elderly with limited resources. The eligibility rule potentially creates an incentive for the elderly to reduce their asset by making transfers to children. This study provides empirical evidence for the effect of Medicaid nursing home care policy on elderly\u27s asset allocation. I exploit a policy change in 2006, the Deficit Reduction Act 2005, which imposed stricter penalty to asset transfer behavior when determining Medicaid eligibility. Using data from the Health and Retirement Survey, I employ a difference-in-differences method. I find that the elderly who anticipated nursing home entry significantly reduced asset transfer behavior by 3.2 to 4 percentage points, in response to the policy change. The result is robust across demographic groups and more pronounced for the elderly with the highest nursing home entry risk. The findings provide evidence of moral hazard in the public insurance market: the elderly would game with the system in anticipation of nursing home needs

Many-body dynamics of a Bose system with attractive interactions on a ring

We investigate the many-body dynamics of an effectively attractive one-dimensional Bose system confined in a toroidal trap. The mean-field theory predicts that a bright-soliton state will be formed when increasing the interparticle interaction over a critical point. The study of quantum many-body dynamics in this paper reveals that there is a modulation instability in a finite Bose system correspondingly. We show that Shannon entropy becomes irregular near and above the critical point due to quantum correlations. We also study the dynamical behavior of the instability by exploring the momentum distribution and the fringe visibility, which can be verified experimentally by releasing the trapComment: 6 pages,5 figure

Wind Noise Mitigation via Dynamic Microphone Selection

A recent study of wind noise data suggests wind noise suppression (WNS) algorithms face the largest challenge from wind noise coming from right in front of the user. As a result, the audio quality as a result is significantly worse than all other directions. This study also shows the wind noise does not contaminate all the mics equally, due to the shape of the mic array. Assuming we have some mechanism to detect the most contaminated mics and exclude them from beamforming, the output audio would be significantly improved. Therefore, we created a strategy for an audio system to handle the most challenging case with a detector for wind noise coming from the front. Upon the detection, an audio system switches to a different subset of the microphones to apply WNS, beamforming, and further noise processing

PoLyScriber: Integrated Training of Extractor and Lyrics Transcriber for Polyphonic Music

Lyrics transcription of polyphonic music is challenging as the background music affects lyrics intelligibility. Typically, lyrics transcription can be performed by a two step pipeline, i.e. singing vocal extraction frontend, followed by a lyrics transcriber backend, where the frontend and backend are trained separately. Such a two step pipeline suffers from both imperfect vocal extraction and mismatch between frontend and backend. In this work, we propose a novel end-to-end integrated training framework, that we call PoLyScriber, to globally optimize the vocal extractor front-end and lyrics transcriber backend for lyrics transcription in polyphonic music. The experimental results show that our proposed integrated training model achieves substantial improvements over the existing approaches on publicly available test datasets.Comment: 13 page

Time varying coefficient model for gap times in ecological momentary assessment data

Ecological momentary assessment (EMA) studies investigate instantaneous and repeated observations on subjects over time in their everyday life. Such study designs are useful for applications to public health and social sciences because they provide intensive information about the temporal pattern of one's behavior. Throughout this dissertation, we will use an EMA study of intermittent smokers (ITS) to demonstrate our method. In this EMA study, events such as smoking are of primary interest. Here, we focus on a particular temporal pattern when smoking events are clustered in time. The distributions of the time-clusters or smoking "bouts" and covariates that predict such behavior are our interest. Traditional linear mixed effects models are not typically equipped to properly assess this kind of investigation. In this dissertation, we introduce a method of displaying the temporal behavior of subjects via functions of event gap times which allow us to easily identify bouts. We also apply an existing time-varying coefficient model to cumulative log gap times to characterize the time patterns of smoking while concomitantly adjusting for behavioral covariates that may be time varying and related to smoking. The mixed effects model we consider here produces a linear function with coefficients that change over time and hence, can identify meaningful temporal changes both at the subject and population levels. We also apply the inverse probability of weighting methods to weight the observed cases and handle missing data generated by the study design. Our method has public health significance in that it allows one to identify time patterns (periodic or otherwise) in health event outcomes that can occur multiple times. Hence, one can characterize the time trajectory of these multiply observed events and possibly develop interventions when necessary to alter the time course of such processes

Weather and topographical influences on spatial and temporal variability of winter wheat yield in Oklahoma

Scope and Method of Study: The main objective of this research was to study the influence of weather and topography on the temporal and spatial variability of wheat yields in Oklahoma by examining the soil moisture distribution and storage and evapotranspiration (ET) variability that are induced by topographical changes, and evaluating their correlation with wheat yield variance across the study field. A stratified random sampling method was used to take soil samples in the study field. Elevation data were collected with a GPS unit on a semiregular grid with a distance from 2-8 m. The weather data used for this research was obtained from the Medford Mesonet Station. The seasonal ET data were calculated using weather data and soil data. Topographical factors, aspect, slope and curvature were derived from the DEM using the elevations collected in the study field with the GPS unit. Their correlations with yields were examined. A topography-related soil moisture index (TRSMI) was constructed from combining two topographic variables, slope and curvature, with one soil variable, available soil water content. Its correlations with yields for each year were examined. The correlation between seasonal ET and yields for each growth season was examined.Findings and Conclusions: The examination of relationships between topographical factors, slope and curvature, soil property, and available soil water content for the entire study field showed that available soil water content has the highest correlation with yield among the factors listed above. This demonstrated that the amount of water soils can retain is an important factor in yield variability on a field scale. The correlation coefficient between TRSMI and yields indicates that a positive correlation exists between yield and TRSM. The correlation coefficient between seasonal ET and yields in dry years and years with adequate precipitation is higher than that in wet years. The patterns of correlation coefficients between yields and the slope, curvature, available soil water content, TRSMI, and seasonal ET are for the sample locations are similar to those for the entire study field, but the correlations were stronger

Faster Projected GAN: Towards Faster Few-Shot Image Generation

In order to solve the problems of long training time, large consumption of computing resources and huge parameter amount of GAN network in image generation, this paper proposes an improved GAN network model, which is named Faster Projected GAN, based on Projected GAN. The proposed network is mainly focuses on the improvement of generator of Projected GAN. By introducing depth separable convolution (DSC), the number of parameters of the Projected GAN is reduced, the training speed is accelerated, and memory is saved. Experimental results show that on ffhq-1k, art-painting, Landscape and other few-shot image datasets, a 20% speed increase and a 15% memory saving are achieved. At the same time, FID loss is less or no loss, and the amount of model parameters is better controlled. At the same time, significant training speed improvement has been achieved in the small sample image generation task of special scenes such as earthquake scenes with few public datasets.Comment: 9 pages,7 figures,4 table

Thermopower and Nernst measurements in a half-filled lowest Landau level

Motivated by recent proposal by Potter et al. [Phys. Rev. X 6, 031026 (2016)] concerning possible thermoelectric signatures of Dirac composite fermions, we perform a systematic experimental study of thermoelectric transport of an ultrahigh-mobility GaAs/AlxGa1-xAs two dimensional electron system at filling factor v = 1/2. We demonstrate that the thermopower Sxx and Nernst Sxy are symmetric and anti-symmetric with respect to B = 0 T, respectively. The measured properties of thermopower Sxx at v = 1/2 are consistent with previous experimental results. The Nernst signals Sxy of v = 1/2, which have not been reported previously, are non-zero and show a power law relation with temperature in the phonon-drag dominant region. In the electron-diffusion dominant region, the Nernst signals Sxy of v = 1/2 are found to be significantly smaller than the linear temperature dependent values predicted by Potter et al., and decreasing with temperature faster than linear dependence.Comment: 23 pages, 5 figure