Extracting the cutoff frequency in the gravitational-wave spectrum of black hole-neutron star mergers

The location of the cutoff in the gravitational-wave spectrum of black hole-neutron star mergers is correlated strongly with the neutron-star radius for the case that the neutron star is disrupted by the black hole during the merger. However, the modulation which appears in the spectrum due to the mode mixing makes it difficult to measure the cutoff frequency if gravitational waves are observed from inclined direction or the binary is precessing. In this letter, we show that the cutoff frequency can be measured even in such situations with a method we have recently proposed to reconstruct the face-on waveforms only from the strain observed from a particular direction. We show that the systematic error in the measurement of the neutron-star radius can be reduced to $\lesssim 5\%$ for the case that tidal disruption of the neutron star occurs significantly.Comment: 6 pages, 2 figure

Extracting the orbital axis from gravitational waves of precessing binary systems

We present a new method for extracting the instantaneous orbital axis only from gravitational wave strains of precessing binary systems observed from a particular observer direction. This method enables us to reconstruct the co-precessing frame waveforms only from observed quantities for the ideal case that the signal-to-noise ratio is high enough to analyze the waveforms directly. Specifically, we do not assume knowledge of the time evolution of the instantaneous orbital axis and the co-precessing waveforms before analyzing the data in our method. We test and measure the accuracy of our method using the numerical relativity simulation data of precessing binary black holes taken from the SXS Catalog. We show that the direction of the orbital axis is extracted within $\approx0.02~{\rm rad}$ error from gravitational waves emitted during the inspiral phase. The co-precessing waveforms are also reconstructed with high accuracy; the mismatch (assuming white noise) between them and the original co-precessing waveforms is typically a few times $10^{-3}$ including the merger-ringdown phase, and can be improved by an order of magnitude focusing only on the inspiral waveform. In this method, the co-precessing frame waveforms are not only the purely technical tools for understanding the complex nature of precessing waveforms but also direct observables.Comment: 12 pages, 8 figures, 1 table, published in PR

Self-motion perception from expanding and contracting optical flows overlapped with binocular disparity

AbstractExpanding and contracting patterns were presented on different disparity planes to investigate the role of stereo depth in vection. Experiment 1 tested the effect of stereo depth on inducing vection with expanding and contracting flows on different disparity planes. Subjects reported whether they felt forward or backward self-motion. The results clearly showed the dominance of the background flow in determining one’s self-motion direction. Experiment 2 tested the effect of stereo depth on a vection direction using two expanding flows. The center of each expansion was displaced to either horizontal side. The subjects judged in which direction they were going when they felt vection. The results demonstrated that the subjects felt their heading biased toward the direction of the center of the farther expansion while feeling vection. The heading perception from the expanding flow was determined only by the background flow, not by 2-D integration of the retinal motion. The result demonstrates the importance of background flow produced by stereo depth in determining one’s self-motion from an expanding/contracting motion

An econometric analysis of unconventional monetary policy : the cases of Japan and United States

In the wake of financial crisis, the use by major advanced countries of unconventional monetary policies, such as credit easing (CE) by central banks toward depository banks as well as quantitative easing (QE), is not without controversy. While QE increases the liability side of the central bank\u27s balance sheet by expanding the monetary base, the new phase of CE policy enlarges the asset side by purchasing different types of credit in order to get credit markets functioning. Nevertheless, many studies have not taken this important difference in policy into account. They have shed light on mechanisms of the determination of interest rate but precluded any endogenous movement of items in the balance sheets of central banks. Instead, this paper attempts to construct a financial model, linked to a macro-econometric model, which reflects the central bank\u27s balance sheet. The two linked models provide a better guide to explaining how a central bank\u27s monetary policy generates impacts on the real economy via depository banks. By undertaking a comparative assessment of the cases of Japan and the USA, this study conducts scenario simulation using the two linked models. It thereby offers an alternative solution to current monetary policy that aims to tackle the problem of deflation

Model of banking behavior : specification and estimation

This study aims to construct a model of the economic behavior of banks as intermediate sectors in macroeconomics that play an important role interplaying between financial and real markets based on a theoretical and empirical perspective. There are two distinguishing characteristics of our approach. First, we specify an economic model of banking behavior, following partially assets and liabilities management (ALM). As the primary object of our paper is to provide an understanding of a bank’s role in macroeconomics rather than the details of ALM, we abstract from that concept and embed its crucial factors into the model specification. Second, we assume that banks have two optimization problems: profit maximization and asset allocation. Banks are assumed to maximize the profit function which takes into consideration items of the balance sheet and income statement. Then, banks are assumed to attempt to determine their optimal portfolio. Although our model is remarkably simple, we consider that our framework is valid to illustrate the mechanism of the loan market

Ultimate low system dark count rate for superconducting nanowire single-photon detector

The dark count rate (DCR) is a key parameter of single-photon detectors. By introducing a bulk optical band-pass filter mounted on a fiber-to-fiber optical bench cooled at 3 K and blocking down to 5 micrometer, we suppressed the DCR of a superconducting nanowire single-photon detector by more than three orders of magnitude. The DCR is limited by the blackbody radiation through a signal passband of 20 nm bandwidth. The figure of merit, system detection efficiency, and DCR were 2.7 x 10^11, 2.3 %, and 0.001 Hz, respectively. Narrowing the bandwidth to 100 GHz suppresses the DCR to 0.0001 Hz and the figure of merit increases to 1.8 x 10^12.Comment: to appear in Optics Letter

ANALYSIS OF THE TRANSFORMATION OF THE VELOCITY OF THE CENTER OF GRAVITY IN RUNNING SINGLE LEG HORIZONTAL JUMP

The purpose of this study was to analyze the transformation of the center of gravity (CG) in the running single leg horizontal jump and to investigate the influence of the forward rotation of the takeoff leg in achieving vertical CG velocity. The subjects were 98 male long jumpers, whose mean best official jump among their recorded trials was 7.16 ± 0.66 m. Their takeoff motion was videotaped with two high-speed cameras. Horizontal CG velocity at touchdown and vertical CG velocity at toe-off had significantly positive correlations with jumping distance; the decrease in horizontal CG velocity during the takeoff phase was significantly and negatively correlated with jumping distance. Forward rotation of the spring-mass model did not contribute to an increase in vertical CG velocity, although it did contribute to an increase in horizontal CG velocity just before toe-off