Essays in Matching Theory

Thesis advisor: Utku UnverMy doctoral research focuses on the matching theory and its market design application. Specifically, I work on matching with property rights, where property rights not only mean the ownership, but also refer to the ability to determine how the good is used. In the matching with property rights model, an agent who owns a resource can claim how her resource is offered, depending on what she gets from the system. For example, in a housing exchange for vacation, an agent who gets a house with a car will offer her house also with a car. However, if she is assigned only a house without a car, she might refuse to offer a car. This restriction can be thought as a matching with externality, as someone's consuming my resource in certain way affects my utility. With property rights present, it is not clear how we can achieve a desirable outcome while satisfying the rights. I am currently pursuing two main lines of research in this topic that constitute the two chapters dissertation. In Matching with Property Rights: an Application to a Parking Space Assignment Problem, I introduce parking in urban areas as a matching problem. First, I model the street-parking market as a strategic game and show that the set of Nash equilibrium outcomes is equivalent to the set of stable allocations. However, it is not reasonable to expect drivers to reach a Nash equilibrium in the decentralized system due to lack of information and coordination failure. Therefore, I suggest a centralized mechanism that would enable a parking authority to assign available spaces to drivers in a stable way. The model incorporates resident parking spaces, such that visitors could access vacant resident spaces. To use the resident parking spaces, the system needs to protect exclusive property rights over their parking spaces. I show that, however, there is no mechanism that is stable and protects residents' rights. To resolve this issue, I introduce a new concept, a claim contract, and suggest a mechanism that protects property rights, is strategy proof for the drivers, and approximates a stable matching. Besides its market-design focus, this paper handles both priority-based and property right-based assignment, which considered separately in the matching theory literature. In Housing Market with Contracts, I study matching with property rights problem in the housing market framework. To introduce property rights in housing market, I assume the house can be offered in two contractual terms. Property rights requires that when an agent gets a house in a certain term, her house should also be offered as the same term. Moreover, when every agent owns a house, property rights reduces to an equal-term matching. After defining efficiency and core in equal-term domain, I show that, in a housing market with contracts problem, core may be empty. However, there always exists an efficient, individually rational, and equal-term matching in every housing market with contracts problem. Then I present a mechanism that always produces an efficient, individually rational, and equal-term matching. This is the first attempt to model a matching with contract in a exchange economy.Thesis (PhD) — Boston College, 2018.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Economics

Accurate Mobile Urban Mapping via Digital Map-Based SLAM †

This paper presents accurate urban map generation using digital map-based Simultaneous Localization and Mapping (SLAM). Throughout this work, our main objective is generating a 3D and lane map aiming for sub-meter accuracy. In conventional mapping approaches, achieving extremely high accuracy was performed by either (i) exploiting costly airborne sensors or (ii) surveying with a static mapping system in a stationary platform. Mobile scanning systems recently have gathered popularity but are mostly limited by the availability of the Global Positioning System (GPS). We focus on the fact that the availability of GPS and urban structures are both sporadic but complementary. By modeling both GPS and digital map data as measurements and integrating them with other sensor measurements, we leverage SLAM for an accurate mobile mapping system. Our proposed algorithm generates an efficient graph SLAM and achieves a framework running in real-time and targeting sub-meter accuracy with a mobile platform. Integrated with the SLAM framework, we implement a motion-adaptive model for the Inverse Perspective Mapping (IPM). Using motion estimation derived from SLAM, the experimental results show that the proposed approaches provide stable bird’s-eye view images, even with significant motion during the drive. Our real-time map generation framework is validated via a long-distance urban test and evaluated at randomly sampled points using Real-Time Kinematic (RTK)-GPS

Enhancement of Brillouin light scattering signal with anti-reflection layers on magnetic thin films

The significant enhancement of Brillouin light scattering (BLS) spectroscopy intensity in a ferromagnetic thin film with an additional dielectric anti-reflection layer is experimentally investigated. The anti-reflection layer thickness dependent BLS measurements on ferromagnetic layers are performed systematically. Consequently, we observe that BLS signals are dramatically enhanced by more than 450% at a specific dielectric layer thickness due to the pure optical effect. Because of the large signal enhancements, the errors of the spin wave resonance peak frequencies are noticeably reduced as well. Since many magnetic properties such as the saturation magnetization, the surface anisotropy, and the exchange stiffness constant are determined by the spin wave resonance frequencies from the BLS spectra, the additional anti-reflection layer can help to improve the reliability of BLS experiments. Especially, the BLS signal improvement plays a crucial role in the precise determination of the interfacial Dzyaloshinskii-Moriya interaction (iDMI) energy density, since the iDMI energy density is calculated from the difference of Stokes and anti-Stokes resonance frequencies, which is typically order of 1 GHz. © 20201

Effect of prohibiting the use of Paraquat on pesticide-associated mortality

Abstract Background Paraquat is associated with a high rate of fatalities in acute poisoning. This study aimed to examine the association between the national public health policy that banned the use of paraquat and the incidence of pesticide-associated mortality. Methods All external causes of death from 2009 to 2013 of Korea were analyzed. The intervention was a national public health policy that annulled the authorized use (2011) and banned the purchase of paraquat (2012). Two periods were compared as follows: before (2009-2010) and after (2012-2013) the intervention period. The main outcome was pesticide-associated death coded on the death certificate. Multivariable logistic regression analysis adjustment for gender, age, season and weekday of death, province, education level, marital status, and occupation was performed to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for pesticide-associated mortality. The effect sizes of the intervention across all intents (Accident, Suicide, Homicide, and Undetermined) were compared by adding an interaction term (intervention*intent group) to the above model. Results A total of 127,866 deaths from for all external causes were analyzed, including 65,538 from 2009 to 2010 and 62,373 from 2012 to 2013. Pesticide-associated mortality decreased from 9.7% (2009-2010) to 6.5% (2012-2013) (p < 0.001). The AOR (95% CI) of the intervention on pesticide-associated mortality was 0.59 (0.56-0.62). The AORs of the intervention according to intent were 0.72 (0.55-0.96) in the Accident group, 0.61 (0.58-0.64) in the Suicide group, 1.29 (0.43-3.87) in the Homicide group, and 0.44 (0.38-0.50) in the Undetermined group. Conclusion The national public health policy that banned paraquat resulted in a significant decrease in pesticide-associated mortality

Persistent Continental Shelf Carbon Sink at the Ieodo Ocean Research Station in the Northern East China Sea

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Persistent Continental Shelf Carbon Sink at the Ieodo Ocean Research Station in the Northern East China Sea

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Persistent Continental Shelf Carbon Sink at the Ieodo Ocean Research Station in the Northern East China Sea

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Persistent Continental Shelf Carbon Sink at the Ieodo Ocean Research Station in the Northern East China Sea

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