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Search Results: 1 - 10 of 4155 matches for " Kento Tanaka "
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Reading Aloud Performance and Listening Ability in an L2: The Case of College-Level Japanese EFL Users  [PDF]
Shigeo Kato, Kento Tanaka
Open Journal of Modern Linguistics (OJML) , 2015, DOI: 10.4236/ojml.2015.52015
Abstract: Recent advance in neuropsychology has evidenced a facilitative role of sensorimotor activity for the development in L2 speech perception. The study attempted to examine the relationship between reading aloud (RA) performance, grammatical knowledge and listening ability with 31 college-level Japanese EFL users. The result demonstrated highly significant correlations between all the variables, and the subsequent multiple regression analysis also indicated RA significantly accounting for listening. Supplementary analyses dividing the participants by listening ability demonstrated that while significant correlation was maintained between L2 knowledge and listening with less-proficient listeners, it disappeared with proficient listeners; in contrast, significant correlation between RA and listening performance was maintained in both groups, indicating that production accuracy/fluency still played an important role in advanced L2 listening.
Effective System for Simulating Dust Continuum Observations on Distributed Computing Resources
Kazutaka Motoyama,Yoshikazu Tanaka,Kento Aida,Eisaku Sakane,Kenichi Miura
Physics , 2013,
Abstract: We present an effective system for simulating dust continuum observations by radiative transfer simulations. By using workflow management system RENKEI-WFT, we utilized distributed computing resources and automated a sequence of computational tasks required for radiative transfer modeling, namely, main radiative transfer simulations, pre-/post-processes, and data transfer between computing resources. Our system simultaneously executes a lot of radiative transfer simulations with different input parameters on distributed computing resources. This capability of our system enables us to conduct effective research by radiative transfer simulation. As a demonstration of our system, we simulated dust continuum observations of protoplanetary disk. We performed hydrodynamic simulation modeling photoevaporating protoplanetary disk irradiated by ultra violet radiation from nearby massive stars. Results of this hydrodynamic simulation were used as input data for radiative transfer simulations. Expected spectral energy distributions and intensity maps were obtained by our system.
Revisiting a gravity-darkened and precessing planetary system PTFO 8-8695: spin-orbit non-synchronous case
Shoya Kamiaka,Kento Masuda,Yuxin Xue,Yasushi Suto,Tsubasa Nishioka,Risa Murakami,Koichiro Inayama,Madoka Saitoh,Michisuke Tanaka,Atsunori Yonehara
Physics , 2015, DOI: 10.1093/pasj/psv063
Abstract: We reanalyse the time-variable lightcurves of the transiting planetary system PTFO 8-8695, in which a planet of 3 to 4 Jupiter mass orbits around a rapidly rotating pre-main-sequence star. Both the planetary orbital period of 0.448 days and the stellar spin period less than 0.671 days are unusually short, which makes PTFO 8-8695 an ideal system to check the model of gravity darkening and nodal precession. While the previous analysis of PTFO 8-8695 assumed that the stellar spin and planetary orbital periods are the same, we extend the analysis by discarding the spin-orbit synchronous condition, and find three different classes of solutions roughly corresponding to the nodal precession periods of 199$\pm$16, 475$\pm$21, and 827$\pm$53 days that reproduce the transit lightcurves observed in 2009 and 2010. We compare the predicted lightcurves of the three solutions against the photometry data of a few percent accuracy obtained at Koyama Astronomical Observatory in 2014 and 2015, and find that the solution with the precession period of 199$\pm$16 days is preferred even though preliminary. Future prospect and implications to other transiting systems are briefly discussed.
Spin-Orbit Angles of Kepler-13Ab and HAT-P-7b from Gravity-Darkened Transit Light Curves
Kento Masuda
Physics , 2015, DOI: 10.1088/0004-637X/805/1/28
Abstract: Analysis of the transit light curve deformed by the stellar gravity darkening allows us to photometrically measure both components of the spin-orbit angle $\psi$, its sky projection $\lambda$ and inclination of the stellar spin axis $i_\star$. In this paper, we apply the method to two transiting hot Jupiter systems monitored with the Kepler spacecraft, Kepler-13A and HAT-P-7. For Kepler-13A, we find $i_\star=81^\circ\pm5^\circ$ and $\psi=60^\circ\pm2^\circ$ adopting the spectroscopic constraint $\lambda=58.6^\circ\pm2.0^\circ$ by Johnson et al. (2014). In our solution, the discrepancy between the above $\lambda$ and that previously reported by Barnes et al. (2011) is solved by fitting both of the two parameters in the quadratic limb-darkening law. We also report the temporal variation in the orbital inclination of Kepler-13Ab, $\mathrm{d} |\cos i_{\rm orb}|/\mathrm{d}t=(-7.0\pm0.4)\times10^{-6}\,\mathrm{day}^{-1}$, providing further evidence for the spin-orbit precession in this system. By fitting the precession model to the time series of $i_{\rm orb}$, $\lambda$, and $i_\star$ obtained with the gravity-darkened model, we constrain the stellar quadrupole moment $J_2=(6.1\pm0.3)\times10^{-5}$ for our new solution, which is several times smaller than $J_2=(1.66\pm0.08)\times10^{-4}$ obtained for the previous one. We show that the difference can be observable in the future evolution of $\lambda$, thus providing a possibility to test our solution with follow-up observations. The second target, HAT-P-7, is the first F-dwarf star analyzed with the gravity-darkening method. Our analysis points to a nearly pole-on configuration with $\psi=101^\circ\pm2^\circ$ or $87^\circ\pm2^\circ$ and the gravity-darkening exponent $\beta$ consistent with $0.25$. Such an observational constraint on $\beta$ can be useful for testing the theory of gravity darkening.
Very Low-Density Planets around Kepler-51 Revealed with Transit Timing Variations and an Anomaly Similar to a Planet-Planet Eclipse Event
Kento Masuda
Physics , 2014, DOI: 10.1088/0004-637X/783/1/53
Abstract: We present an analysis of the transit timing variations (TTVs) in the multi-transiting planetary system around Kepler-51 (KOI-620). This system consists of two confirmed transiting planets, Kepler-51b ($P_{\rm b} = 45.2\,\mathrm{days}$) and Kepler-51c ($P_{\rm c} = 85.3\,\mathrm{days}$), and one transiting planet candidate KOI-620.02 ($P_{02} = 130.2\,\mathrm{days}$), which lie close to a $1:2:3$ resonance chain. Our analysis shows that their TTVs are consistently explained by the three-planet model, and constrains their masses as $M_{\rm b} = 2.1_{-0.8}^{+1.5} M_{\oplus}$ (Kepler-51b), $M_{\rm c} = 4.0 \pm 0.4 M_{\oplus}$ (Kepler-51c), and $M_{02} = 7.6 \pm 1.1 M_{\oplus}$ (KOI-620.02), thus confirming KOI-620.02 as a planet in this system. The masses inferred from the TTVs are rather small compared to the planetary radii based on the stellar density and planet-to-star radius ratios determined from the transit light curves. Combining these estimates, we find that all three planets in this system have densities among the lowest determined, $\rho_p \lesssim 0.05\,{\rm g\,cm^{-3}}$. With this feature, the Kepler-51 system serves as another example of low-density compact multi-transiting planetary systems. We also identify a curious feature in the archived Kepler light curve during the double transit of Kepler-51b and KOI-620.02, which could be explained by their overlapping on the stellar disk (a planet-planet eclipse). If this is really the case, the sky-plane inclination of KOI-620.02's orbit relative to that of Kepler-51b is given by $\Delta \Omega = -25.3_{-6.8}^{+6.2}\mathrm{deg}$, implying significant misalignment of their orbital planes. This interpretation, however, seems unlikely because such an event that is consistent with all of the observations is found to be exceedingly rare.
Solution Generating Technique for Noncommutative Orbifolds
Kento Ichikawa
Physics , 2001, DOI: 10.1143/PTP.108.383
Abstract: We propose the relationships between the noncommutative solitons and the (fractional) D-branes on the C^2/Z_n orbifold and extend the solution generating technique for the orbifold. As applications, we determine how tachyon condensations occur in various D-Dbar systems on the orbifolds. The calculations give results consistent with BSFT. The extended solution generating technique enables us to calculate more general decay modes of D-Dbar systems.
Fano manifolds which are not slope stable along curves
Kento Fujita
Mathematics , 2011,
Abstract: We show that a Fano manifold (X,-K_X) is not slope stable with respect to a smooth curve Z if and only if (X,Z) is isomorphic to one of (projective space, line), (product of projective line and projective space, fiber of second projection) or (blow up of projective space along linear subspace of codimension two, nontrivial fiber of blow up).
Fano manifolds having (n-1,0)-type extremal rays with large Picard number
Kento Fujita
Mathematics , 2012,
Abstract: We classify smooth Fano manifolds X with the Picard number $\rho_X \geq 3$ such that there exists an extremal ray which has a birational contraction that maps a divisor to a point.
Towards a criterion for slope stability of Fano manifolds along divisors
Kento Fujita
Mathematics , 2013,
Abstract: We give a simple criterion for slope stability of Fano manifolds $X$ along divisors or smooth subvarieties. As an application, we show that $X$ is slope stable along an ample effective divisor $D\subset X$ unless $X$ is isomorphic to a projective space and $D$ is a hyperplane section. We also give counterexamples to Aubin's conjecture on the relation between the anticanonical volume and the existence of a K\"ahler-Einstein metric. Finally, we consider the case that $\dim X=3$; we give a complete answer for slope (semi)stability along divisors of Fano threefolds.
Complete Ricci flat Torus fibrations over ALE spaces
Kento Niikura
Mathematics , 2013,
Abstract: We investigate complete noncompact Ricci-flat manifolds which are not of maximal volume growth. We show that the manifolds with a curvature decay condition and a holonomy decay condition are asymptotic to torus fibrations over ALE spaces. In particular, we classify complete noncompact 4-dimensional hyperk\"aler manifolds by the volume growth. As an application, we give the uniqueness of tangent cones of collapsing manifolds with some conditions.
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