Asymmetric Preferences for Monetary Policy Rules in the Visegrad Four and the Financial Crisis

This paper analyses asymmetric preferences for the monetary policies of the Visegrad Four (the Czech Republic, Hungary, Poland, and Slovakia). We extend Surico's (2007) asymmetric preference model to a small open economy in order to consider the exchange rate for a monetary policy framework as suggested by several earlier studies on the Visegrad Four. The results suggest that two asymmetries are evident in all the countries: an aversion to interest rates above the reference value and a preference for nominal exchange rate depreciation relative to the euro area. Moreover, the Czech policy does not exhibit any change in preferences during the recent financial crisis, while Poland responds aggressively.Asymmetric objective, monetary policy rule

Financial Integration and International Transmission of Business Cycles: Evidence from Dynamic Correlations

We estimate determinants of dynamic correlations of output comovement of OECD countries between 1990 and 2008. We show that trade intensity, degree of financial integration and specialization pattern have significantly different effects on comovements at different frequencies. This can bias the results using aggregate data or statistical filters. For example, financial integration is showed to have the highest positive effect for middle business frequencies, while it is insignificant for short-term frequencies.Business Cycle, Transmission, Financial Integration, Dynamic Correlation

Vortex-lattice melting in two-dimensional superconductors in intermediate fields

To examine the field dependence of the vortex lattice melting transition in two-dimensional (2D) superconductors, Monte Carlo simulations of the 2D Ginzburg-Landau (GL) model are performed by extending the conventional lowest Landau level (LL) approximation to include several {\it higher} LL modes of the superconducting order parameter with LL indices up to six. It is found that a nearly vertical melting line in lower fields, which is familiar within the elastic theory, is reached just by including higher LL modes with LL indices less than five, and that the first order character of the melting transition in higher fields is significantly weakened with decreasing the field. Nevertheless, a genuine crossover to the consecutive continuous melting picture intervened by a hexatic liquid is not found within the use of the GL model.Comment: 6 pages, 7 figures. To appear in Phys. Rev.

Structured Hammerstein-Wiener Model Learning for Model Predictive Control

This paper aims to improve the reliability of optimal control using models constructed by machine learning methods. Optimal control problems based on such models are generally non-convex and difficult to solve online. In this paper, we propose a model that combines the Hammerstein-Wiener model with input convex neural networks, which have recently been proposed in the field of machine learning. An important feature of the proposed model is that resulting optimal control problems are effectively solvable exploiting their convexity and partial linearity while retaining flexible modeling ability. The practical usefulness of the method is examined through its application to the modeling and control of an engine airpath system.Comment: 6 pages, 3 figure

Experimental Verification of a One-Dimensional Diffraction-Limit Coronagraph

We performed an experimental verification of a coronagraph. As a result, we confirmed that, at the focal region where the planetary point spread function exists, the coronagraph system mitigates the raw contrast of a star-planet system by at least $1\times10^{-5}$ even for the 1-$\lambda/D$ star-planet separation. In addition, the verified coronagraph keeps the shapes of the off-axis point spread functions when the setup has the source angular separation of 1$\lambda/D$. The low-order wavefront error and the non-zero extinction ratio of the linear polarizer may affect the currently confirmed contrast. The sharpness of the off-axis point spread function generated by the sub-$\lambda/D$ separated sources is promising for the fiber-based observation of exoplanets. The coupling efficiency with a single mode fiber exceeds 50% when the angular separation is greater than 3--4$\times 10^{-1}\lambda/D$. For sub-$\lambda/D$ separated sources, the peak positions (obtained with Gaussian fitting) of the output point spread functions are different from the angular positions of sources; the peak position moved from about $0.8\lambda/D$ to $1.0\lambda/D$ as the angular separation of the light source varies from $0.1\lambda/D$ to $1.0\lambda/D$. The off-axis throughput including the fiber-coupling efficiency (with respect to no focal plane mask) is about 40% for 1-$\lambda/D$ separated sources and 10% for 0.5-$\lambda/D$ separated ones (excluding the factor of the ratio of pupil aperture width and Lyot stop width), where we assumed a linear-polarized-light injection. In addition, because this coronagraph can remove point sources on a line in the sky, it has another promising application for high-contrast imaging of exoplanets in binary systems.Comment: 18 pages, 10 figures, accepted for the Publications of the Astronomical Society of the Pacifi

Analysis of a city‐wide COVID‐19 prevention strategy for aged‐care facilities during third and fifth waves of COVID‐19 in Kyoto City, Kyoto, Japan

[Background] During the third wave of the COVID-19 pandemic at the end of 2020, clusters occurred frequently in aged-care facilities (ACFs), which put pressure on the medical field in Japan. Based on this experience, Kyoto University and Kyoto City collaborated to promote a citywide COVID-19 prevention strategy to prevent the spread of COVID-19 within ACFs. The aim of this study was to clarify the effect of the prevention strategy among ACFs in Kyoto City during the third and fifth waves of the pandemic. [Methods] During the study period, the following measures were adopted as the prevention strategy in all ACFs: (1) active polymerase chain reaction (PCR) mass testing and facility-wide testing when a single case was identified, (2) implementation of strategies to prevent transmission within a facility, and (3) vaccination program for ACFs. [Results] Of the 1, 144 facilities subjected to the mass testing, 71.0% participated in the whole program including active PCR testing. The remainder participated in the rest of the programs. The prevalence of ACF-related COVID-19 cases among total COVID-19 cases in Kyoto City decreased from 7.9% in the third wave to 4.1% in the fourth wave and 2.1% in the fifth wave. The incidence of clusters and proportion of severe elderly cases also decreased during the study period. [Conclusions] A city-wide multidisciplinary effort including PCR mass testing and a vaccination program in cooperation with a university and local administrative office successfully reduced the clusters and transmission in ACFs in Kyoto City, Japan