Tokyo University of Science

About: Tokyo University of Science is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 15800 authors who have published 24147 publications receiving 438081 citations. The organization is also known as: Tōkyō Rika Daigaku & Science University of Tokyo.

Primordial non-Gaussianities in general modified gravitational models of inflation

Abstract: We compute the three-point correlation function of primordial scalar density perturbations in a general single-field inflationary scenario, where a scalar field has a direct coupling with the Ricci scalar R and the Gauss-Bonnet term . Our analysis also covers the models in which the Lagrangian includes a function non-linear in the field kinetic energy X = −(∂)2/2, and a Galileon-type field self-interaction G(,X), where G is a function of and X. We provide a general analytic formula for the equilateral non-Gaussianity parameter fNLequil associated with the bispectrum of curvature perturbations. A quasi de Sitter approximation in terms of slow-variation parameters allows us to derive a simplified form of fNLequil convenient to constrain various inflation models observationally. If the propagation speed of the scalar perturbations is much smaller than the speed of light, the Gauss-Bonnet term as well as the Galileon-type field self-interaction can give rise to large non-Gaussianities testable in future observations. We also show that, in Brans-Dicke theory with a field potential (including f(R) gravity), fNLequil is of the order of slow-roll parameters as in standard inflation driven by a minimally coupled scalar field.

Preparation of nanosized gold particles in a biopolymer using UV photoactivation.

Abstract: Gold nanoparticles have been prepared by UV photoactivation in the presence of a biopolymer, sodium alginate. The particles are characterized by UV-vis spectra and TEM studies. Both particle size and the UV-visible absorption peak are dependent on the sodium alginate concentration. The effects of various other parameters such as change of light source, cell material of the reaction chamber, heating effect, irradiation time, and HAuCl4 concentration are studied. The particles are spherical and in situ stabilized by the biopolymer. The method is very simple and reproducible.

Finding Exponential Product Formulas of Higher Orders

Abstract: This article is based on a talk presented at a conference “Quantum Annealing and Other Optimization Methods” held at Kolkata, India on March 2–5, 2005. It will be published in the proceedings “Quantum Annealing and Other Optimization Methods” (Springer, Heidelberg) pp. 39–70. In the present article, we review the progress in the last two decades of the work on the Suzuki-Trotter decomposition, or the exponential product formula. The simplest Suzuki-Trotter decomposition, or the well-known Trotter decomposition [1–4] is given by e x(A+B) = e xA e xB + O(x 2 ), (1) where x is a parameter and A and B are arbitrary operators with some commutation relation [A, B] 6 0. Here the product of the exponential operators on the right-hand side is regarded as an approximate decomposition of the exponential operator on the left-hand side with correction terms of the second order of x. Mathematicians put Eq. (1) in the form e xA e xB = e x(A+B)+O(x 2 ) (2)