A Fine Grain Microprocessor Design Education considering Situated Nature of Learning (2009)
Ryuichi Takahashi, Hajime Ohiwa, Yoshiyasu Takefuji
This paper proposes a new training method for instructing newcomers in the field of microprocessor design. By using this method, which is an extension of the method known as legitimate peripheral...
High-precision predictions for the acoustic scale in the non-linear regime (2009)
Seo, Hee-Jong, Eckel, Jonathan, Eisenstein, Daniel J., Mehta, Kushal, Metchnik, Marc, Padmanabhan, Nikhil, ...
We measure shifts of the acoustic scale due to nonlinear growth and redshift distortions to a high precision using a very large volume of high-force-resolution simulations. We compare results from...
Characterization of OsNramp1, a metal transporter from rice (2009)
Takahashi, Ryuichi, Ishimaru, Yasuhiro, Senoura, Takeshi, Shimo, Hugo M, Nakanishi, Hiromi, Nishizawa, Naoko K
Cadmium (Cd) is one of the most toxic heavy metals for both plants and humans, and Cd accumulation in rice grains has become a major agricultural problem in Japan. In this study, we investigated the...
Simulations of Wide-Field Weak Lensing Surveys I: Basic Statistics and Non-Gaussian Effects (2009)
Sato, Masanori, Hamana, Takashi, Takahashi, Ryuichi, Takada, Masahiro, Yoshida, Naoki, Matsubara, Takahiko, ...
We study the lensing convergence power spectrum and its covariance for a standard LCDM cosmology. We run 400 cosmological N-body simulations and use the outputs to perform a total of 1000 independent...
Ando, Masaki, Kawamura, Seiji, Sato, Shuichi, Nakamura, Takashi, Tsubono, Kimio, Araya, Akito, ...
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. DECIGO is expected...
Takahashi, Ryuichi, Yoshida, Naoki, Takada, Masahiro, Matsubara, Takahiko, Sugiyama, Naoshi, Kayo, Issha, ...
We use 5000 cosmological N-body simulations of 1(Gpc/h)^3 box for the concordance LCDM model in order to study the sampling variances of nonlinear matter power spectrum. We show that the non-Gaussian...
Ardie, Sintho Wahyuning, Xie, Lina, Takahashi, Ryuichi, Liu, Shenkui, Takano, Tetsuo
A high-affinity K+ transporter PutHKT2;1 cDNA was isolated from the salt-tolerant plant Puccinellia tenuiflora. Expression of PutHKT2;1 was induced by both 300 mM NaCl and K+-starvation stress in...
Nishimichi, Takahiro, Shirata, Akihito, Taruya, Atsushi, Yahata, Kazuhiro, Saito, Shun, Suto, Yasushi, ...
We use a series of cosmological N-body simulations and various analytic models to study the evolution of the matter power spectrum in real space in a \Lambda Cold Dark Matter universe. We compare the...
Search for a Stochastic Background of 100-MHz GravitationalWaves with Laser Interferometers (2008)
Akutsu, Tomotada, Kawamura, Seiji, Nishizawa, Atsushi, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
This Letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm...
Ando, Masaki, Kawamura, Seiji, Nakamura, Takashi, Tsubono, Kimio, Tanaka, Takahiro, Funaki, Ikkoh, ...
DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected...
The Japanese space gravitational wave antenna; DECIGO (2008)
Kawamura, Seiji, Ando, Masaki, Nakamura, Takashi, Tsubono, Kimio, Tanaka, Takahiro, Funaki, Ikkoh, ...
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational...
We investigate the third-order density perturbation and the one-loop correction to the linear power spectrum in the dark-energy cosmological model. Our main interest is to understand the dark-energy...
Search for a stochastic background of 100-MHz gravitational waves with laser interferometers (2008)
Akutsu, Tomotada, Kawamura, Seiji, Nishizawa, Atsushi, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
This letter reports the results of a search for a stochastic background of gravitational waves (GW) at 100 MHz by laser interferometry. We have developed a GW detector, which is a pair of 75-cm...
Simulations of Baryon Acoustic Oscillations I: Growth of Large-Scale Density Fluctuations (2008)
Takahashi, Ryuichi, Yoshida, Naoki, Matsubara, Takahiko, Sugiyama, Naoshi, Kayo, Issha, Nishimichi, Takahiro, ...
We critically examine how well the evolution of large-scale density perturbations is followed in cosmological $N$-body simulations. We first run a large volume simulation and perform a mode-by-mode...
Nishizawa, Atsushi, Kawamura, Seiji, Akutsu, Tomotada, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
Recently, observational searches for gravitational wave background (GWB) have been developed and given constraints on the energy density of GWB in a broad range of frequencies. These constraints have...
Nishizawa, Atsushi, Kawamura, Seiji, Akutsu, Tomotada, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
Recently, observational searches for gravitational wave background (GWB) have been developed and given direct and indirect constraints on the energy density of GWB in a broad range of frequencies....
Nishizawa, Atsushi J., Komatsu, Eiichiro, Yoshida, Naoki, Takahashi, Ryuichi, Sugiyama, Naoshi
Non-linear evolution of density fluctuations yields secondary anisotropies in the cosmic microwave background (CMB), which are correlated with the same density fluctuations that can be measured by...
Nishizawa, Atsushi, Kawamura, Seiji, Akutsu, Tomotada, Arai, Koji, Yamamoto, Kazuhiro, Tatsumi, Daisuke, ...
Recently, observational searches for gravitational wave background (GWB) have developed and given direct and indirect constraints on the energy density of GWB in a broad range of frequencies. These...
A Consistency Relation in Cosmology (2007)
Chiba, Takeshi, Takahashi, Ryuichi
We provide a consistency relation between cosmological observables in general relativity without relying on the equation of state of dark energy. The consistency relation should be satisfied if...
Weak Lensing of Galaxy Clusters in MOND (2007)
Takahashi, Ryuichi, Chiba, Takeshi
We study weak gravitational lensing of galaxy clusters in terms of the MOND (MOdified Newtonian Dynamics) theory. We calculate shears and convergences of background galaxies for three clusters...
Takahashi, Ryuichi, Liu, Shenkui, Takano, Tetsuo
To understand the mechanisms of ion homeostasis in salt-tolerant and salt-sensitive plants, cDNAs for a high-affinity K+ transporter PhaHKT1 were isolated from salt-sensitive (Utsunomiya) and...
Yoo, Chul-Moon, Nakao, Ken-ichi, Kozaki, Hiroshi, Takahashi, Ryuichi
The distance-redshift relation determined by means of gravitational waves in the clumpy universe is simulated numerically by taking into account the effects of gravitational lensing. It is assumed...
Exact Wave Propagation in a Spacetime with a Cosmic String (2005)
Suyama, Teruaki, Tanaka, Takahiro, Takahashi, Ryuichi
We present exact solutions of the massless Klein-Gordon equation in a spacetime in which an infinite straight cosmic string resides. The first solution represents a plane wave entering perpendicular...
When a gravitational wave (GW) from a distant source propagates through the universe, its amplitude and phase change due to gravitational lensing by the inhomogeneous mass distribution. We derive the...
Suyama, Teruaki, Takahashi, Ryuichi, Michikoshi, Shugo
Wave effects can be important for the gravitational lensing of gravitational waves. In such a case, wave optics must be used in stead of geometric optics. We consider a plane wave entering a lens...
Scattering of Gravitational Waves by the Weak Gravitational Fields of Lens Objects (2005)
Takahashi, Ryuichi, Suyama, Teruaki, Michikoshi, Shugo
We consider the scattering of the gravitational waves by the weak gravitational fields of lens objects. We obtain the scattered gravitational waveform by treating the gravitational potential of the...
Classifying the Future of Universes with Dark Energy (2005)
Chiba, Takeshi, Takahashi, Ryuichi, Sugiyama, Naoshi
We classify the future of the universe for general cosmological models including matter and dark energy. If the equation of state of dark energy is less then -1, the age of the universe becomes...
Takahashi, Ryuichi, Nakamura, Takashi
We show that ten(one) years operation of the ultimate DECIGO (DECihertz Interferometer Gravitational wave Observatory) can determine the cosmic equation of the state with such accuracy that...
Quasi-geometrical Optics Approximation in Gravitational Lensing (2004)
The gravitational lensing of gravitational waves should be treated in the wave optics instead of the geometrical optics when the wave length $\lambda$ of the gravitational waves is larger than the...
Takahashi, Ryuichi, Nakamura, Takashi
It may be possible to construct a laser interferometer gravitational wave antenna in space with $h_{rms}\sim 10^{-23}$ at $ f\sim 0.1{\rm Hz}$ in $\sim 2020$. This deci hertz antenna may be called...
Wave Effects in Gravitational Lensing of Gravitational Waves from Chirping Binaries (2003)
Takahashi, Ryuichi, Nakamura, Takashi
In the gravitational lensing of gravitational waves, the wave optics should be used instead of the geometrical optics when the wavelength $\lambda$ of the gravitational waves is longer than the...
Situated Learning on FPGA for Superscalar Microprocessor Design Education (2003)
Ryuichi Takahashi, Hajime Ohiwa
Microprocessor design education is acquiring critical importance, since highly sophisticated functions are supported by microprocessors in many products which cannot lose market windows. In our...
Parameter estimation for Galactic binaries by LISA (2002)
Takahashi, Ryuichi, Seto, Naoki
We calculate how accurately parameters of the short-period binaries $(10^{-4} {Hz} \lsim f\lsim 10^{-2} {Hz})$ will be determined from the gravitational waves by LISA. In our analysis the chirp...
Lens Model Degeneracy and Cosmological Tests by Strong Gravitational Lensing (2001)
Chiba, Takeshi, Takahashi, Ryuichi
We estimate the sensitivity of lensing observables to the parameters in the lens model (isothermal sphere/Navarro-Frenk-White profile) parameters and to cosmological parameters. We find that the...
Gravitational Lens Statistics and The Density Profile of Dark Halos (2001)
Takahashi, Ryuichi, Chiba, Takeshi
We investigate the influence of the inner profile of lens objects on gravitational lens statistics taking into account of the effect of magnification bias and both the evolution and the scatter of...
Ardie, Sintho Wahyuning, Xie, Lina, Takahashi, Ryuichi, Liu, Shenkui, Takano, Tetsuo
A high-affinity K+ transporter PutHKT2;1 cDNA was isolated from the salt-tolerant plant Puccinellia tenuiflora. Expression of PutHKT2;1 was induced by both 300 mM NaCl and K+-starvation stress in...