The Fiscal Burden of Korean Reunification: A Generational Accounting Approach

This paper uses Generational Accounting to assess the fiscal impacts of Korean reunification. Our findings suggest that early reunification will result in a large increase in the fiscal burden for most current and future generations of South Koreans. The Korean reunification's fiscal impact appears much larger than that of German reunification, due to a wider gap in productivity between the two Koreas and North Korea's much larger share of the unified country's population. The projected large-scale fiscal burden on South Korea is attributable primarily to the rapid increase in social welfare expenditure for North Korean residents, rather than to the direct reconstruction cost of the North Korean economic system after the disintegration of its old economic regime.

Colour constancy in dichromats and trichromats: dependence on task

An important topic in the field of colour vision is the impact of colour vision deficiencies on daily life tasks. Investigating the extent to which colour constancy (i.e. the ability to recognise surface colour under different illuminants) is preserved in colour vision- deficient observers can provide us with insight into the nature and function of trichromatic colour vision. The first chapter of this thesis provides a summary of the very basics of colour vision, colour vision deficiencies, as well as colour constancy. Studies conducted on the colour constancy abilities of colour-vision-deficient observers versus those with normal colour vision are reviewed. The second chapter presents and reports the aims and methods of the proposed experiment (which could not take place due to the COVID-19 pandemic). This experiment investigated the colour constancy abilities of trichromats versus dichromats using two different colour constancy tasks (2D achromatic adjustment vs. 3D blocks-copying/selection task) and aimed to show how colour constancy depends on observer type as well as task type. The third chapter comprises of a computerised simulation. This simulation aimed to model the colour constancy of “ideal” observers when presented with various surfaces and illuminants. These observers involve simulated normal trichromats, anomalous trichromats and dichromats. A variety of yellow, blue, green and red illuminant shifts (from neutral daylight) were used, and surface chromaticity and observer types were compared. Overall, whilst no three-way interaction between illuminant shift, surface chromaticity and observer type were found in the simulation, strong main effects were found. It is suggested that a combination of simulated and experimental research is needed to understand the colour constancy mechanisms underpinning dichromacy and trichromacy at multiple levels (cone-based, cognitive and computational)

Generational accounting in Korea

노트 : The views expressed herein are those of the authors and are not necessarily those of the National Bureau ofEconomic Research

The fiscal burden of Korean reunification

노트 : The views expressed herein are those of the author(s) and not necessarily those of the National Bureau of Economic Research

Clustering Spam Domains and Destination Websites: Digital Forensics with Data Mining

Spam related cyber crimes have become a serious threat to society. Current spam research mainly aims to detect spam more effectively. We believe the identification and disruption of the supporting infrastructure used by spammers is a more effective way of stopping spam than filtering. The termination of spam hosts will greatly reduce the profit a spammer can generate and thwart his ability to send more spam. This research proposes an algorithm for clustering spam domains extracted from spam emails based on the hosting IP addresses and tracing the IP addresses over a period of time. The results show that many seemingly unrelated spam campaigns are actually related if the domain names in the URLs are investigated; spammers have a sophisticated mechanism for combating URL blacklisting by registering many new domain names every day and flushing out old domains; the domains are hosted at different IP addresses across several networks, mostly in China where legislation is not as tight as in the United States; old IP addresses are replaced by new ones from time to time, but still show strong correlation among them. This paper demonstrates an effective use of data mining to relate spam emails for the purpose of identifying the supporting infrastructure used for spamming and other cyber criminal activities

Conjuntos, reglas y clases naturales: [ ] frente a { }

We discuss a set-theoretic treatment of segments as sets of valued features and of natural classes as intensionally defined sets of sets of valued features. In this system, the empty set { } corresponds to a completely underspecified segment, and the natural class [ ] corresponds to the set of all segments, making a feature ± Segment unnecessary. We use unification, a partial operation on sets, to implement feature-filling processes, and we combine unification with set subtraction to implement feature-changing processes. We show how unification creates the illusion of targeting only underspecified segments, and we explore the possibility that only unification rules whose structural changes involve a single feature are UG-compatible. We show that no such Singleton Set Restriction can work with rules based on set subtraction. The system is illustrated using toy vowel harmony systems and a treatment of compensatory lengthening as total assimilation.Discutimos en este trabajo el tratamiento teórico conjunto de los segmentos entendidos como agrupaciones de rasgos especificados, y de las clases naturales entendidas como agrupaciones definidas intensionalmente de grupos de rasgos especificados. En este sistema, el conjunto vacío { } se corresponde con un segmento completamente inespecificado, y la clase natural [ ] se corresponde con el conjunto de todos los segmentos, lo que hace innecesario el rasgo ± Segmento. Nos servimos de la unificación –una operación parcial sobre los conjuntos– para implementar los procesos de rellenado de rasgos, y combinamos la unificación con la sustracción de todo el conjunto para llevar a cabo los procesos de cambio de rasgos. Mostramos cómo la unificación afecta aparentemente solo a los segmentos subespecificados, y exploramos la posibilidad de que únicamente sean compatibles con la GU las reglas de unificación cuyos cambios estructurales implican a un único rasgo. Comprobamos que la Restricción de un Conjunto Unitario no puede funcionar con reglas basadas en la sustracción de todo el conjunto. Como ilustración del sistema nos servimos de sistemas de prueba sobre la armonía vocálica así como del tratamiento del alargamiento compensatorio como una asimilación completa

Semi-Analytic Techniques for Solving Quasi-Normal Modes

In this chapter, we discuss an approach to obtaining black hole quasi-normal modes known as the asymptotic iteration method, which was initially developed in mathematics as a new way to solve for eigenvalues in differential equations. Furthermore, we demonstrate that the asymptotic iteration method allows one to also solve for the radial quasi-normal modes on a variety of black hole spacetimes for a variety of perturbing fields. A specific example for Dirac fields in a general dimensional Schwarzschild black hole spacetime is given, as well as for spin-3/2 field quasi-normal modes

Adaptation of an evidence-based intervention to promote colorectal cancer screening: a quasi-experimental study

Background To accelerate the translation of research findings into practice for underserved populations, we investigated the adaptation of an evidence-based intervention (EBI), designed to increase colorectal cancer (CRC) screening in one limited English-proficient (LEP) population (Chinese), for another LEP group (Vietnamese) with overlapping cultural and health beliefs. Methods Guided by Diffusion of Innovations Theory, we adapted the EBI to achieve greater reach. Core elements of the adapted intervention included: small media (a DVD and pamphlet) translated into Vietnamese from Chinese; medical assistants distributing the small media instead of a health educator; and presentations on CRC screening to the medical assistants. A quasi-experimental study examined CRC screening adherence among eligible Vietnamese patients at the intervention and control clinics, before and after the 24-month intervention. The proportion of the adherence was assessed using generalized linear mixed models that account for clustering under primary care providers and also within-patient correlation between baseline and follow up. Results Our study included two cross-sectional samples: 1,016 at baseline (604 in the intervention clinic and 412 in the control clinic) and 1,260 post-intervention (746 in the intervention and 514 in the control clinic), including appreciable overlaps between the two time points. Pre-post change in CRC screening over time, expressed as an odds ratio (OR) of CRC screening adherence by time, showed a marginally-significant greater increase in CRC screening adherence at the intervention clinic compared to the control clinic (the ratio of the two ORs = 1.42; 95% CI 0.95, 2.15). In the sample of patients who were non-adherent to CRC screening at baseline, compared to the control clinic, the intervention clinic had marginally-significant greater increase in FOBT (adjusted OR = 1.77; 95% CI 0.98, 3.18) and a statistically-significantly greater increase in CRC screening adherence (adjusted OR = 1.70; 95% CI 1.05, 2.75). Conclusions Theoretically guided adaptations of EBIs may accelerate the translation of research into practice. Adaptation has the potential to mitigate health disparities for hard-to-reach populations in a timely manner

Molecular Beam Epitaxial Growth Optimization for Next Generation Optoelectronic Devices Based on III-V Semiconductors

Molecular beam epitaxy (MBE) has been serving as the best tool for group III-V compound growths due to its capability of depositing epilayers with high single-crystalline quality, high purity and Angstrom-scale thickness precision. In spite of decades of work, further optimizations of MBE growth conditions are required in order to meet the increasing demands of next-generation and novel devices. For instance, low temperature (LT) deposition far away from thermal equilibrium growth conditions brings several benefits such as suppressed undesirable interface inter-diffusion, dopant diffusion and segregation. More importantly, it has been proven to be a very useful method in forming non-stoichiometric III-V compounds. Although this creates defects like group V antisites and interstitials, they can be utilized in making terahertz (THz) photoconductive antennas (PCAs). Since the development of THz technology in the late 20th century, THz PCAs have been drawing tremendous research interest due to their low-cost and portability. The amount of embedded excess As which alters the LT grown III-V material properties is sensitive to the V/III flux ratio, and more importantly, the growth temperature at the range of ∼200–300◦C. It is crucial to determine a critical substrate temperature that simultaneously maximizes the excess As incorporation without losing single crystallinity, as both features are essential for high-performance broadband THz PCAs applications. However, substrate temperature monitoring becomes difficult when the growth is switched to the LT regime. Conventional substrate temperature measurement techniques such as pyrometry have limited precision at LT due to the exponential decrease of the substrate thermal radiation intensity with the temperature, hence an alternative means for precise temperature monitoring is required. InAlGaAs has been an emerging candidate for 1319 nm laser-pumped, high-efficiency photonic power converters (PPCs). To acquire smooth surface morphology and minimize crystalline defects, such quaternary material is preferred to be lattice-matched on InP(001) substrates. A clear correlation between group III compositions, lattice constant and bandgap of InAlGaAs, as well as a reproducible approach to grow lattice-matched InAlGaAs structures need to be established to optimize the PPC performance. This thesis conducts a comprehensive study of optimizing MBE growth conditions of several III-V materials, including LT GaAs, mid-temperature (MT) and LT InGaAs-InAlAs superlattice (SL), and InAlGaAs, with parameters such as substrate temperature, As overpressure and doping concentration being repetitively tuned. In particular, an integrated spectral pyrometry (ISP) technique is proposed, which is particularly well suited to monitor the growth temperature of InAs and InSb. Potentially, ISP can also be applied to other LT growths with semiconductors of smaller bandgaps when pyrometer does not work. In-growth and post-growth surface morphologies were investigated with the aid of reflection high energy electron diffraction (RHEED) and Nomarski microscopy. LT GaAs and InGaAs-InAlAs SL based THz PCAs were characterized with 780 and 1550 nm pumped time-domain spectroscopy (TDS) measurements and the correlation between THz signal amplitude, pulse width and bandwidth with growth and annealing temperatures are discussed. The material properties of InAlGaAs structures were investigated with an emphasis on discussing challenges of lattice mismatch and in-growth flux drift studied by high-resolution x-ray diffraction (HRXRD) fitting. The performance of InAlGaAs p-n junctions was optimized by MBE. State-of-the-art 1319 nm pumped single-junction (SJ) and two-junction (TJ) PPC devices are presented. The effects of growth temperature on current-voltage characteristics and unintentionally strained InAlGaAs epilayers on quantum efficiency are discussed