Tokyo Institute of Technology

About: Tokyo Institute of Technology is a education organization based out in Tokyo, Tôkyô, Japan. It is known for research contribution in the topics: Thin film & Catalysis. The organization has 46775 authors who have published 101656 publications receiving 2357893 citations. The organization is also known as: Tokyo Tech & Tokodai.

The Hybrid Steepest Descent Method for the Variational Inequality Problem over the Intersection of Fixed Point Sets of Nonexpansive Mappings

Abstract: This paper presents a simple algorithmic solution to the variational inequality problem defined over the nonempty intersection of multiple fixed point sets of nonexpansive mappings in a real Hilbert space. The algorithmic solution is named the hybrid steepest descent method, because it is constructed by blending important ideas in the steepest descent method and in the fixed point theory, and generates a sequence converging strongly to the solution of the problem. The remarkable applicability of this method to the convexly constrained generalized pseudoinverse problem as well as to the convex feasibility problem is demonstrated by constructing nonexpansive mappings whose fixed point sets are the feasible sets of the problems.

Lepton-flavor violation via right-handed neutrino Yukawa couplings in the supersymmetric standard model.

Abstract: Various lepton-flavor-violating (LFV) processes in the supersymmetric standard model with right-handed neutrino supermultiplets are investigated in detail. It is shown that large LFV rates are obtained when $tan\ensuremath{\beta}$ is large. In the case where the mixing matrix in the lepton sector has a similar structure as the Kobayashi-Maskawa matrix and the third-generation Yukawa coupling is as large as that of the top quark, the branching ratios can be as large as $B(\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma})\ensuremath{\simeq}{10}^{\ensuremath{-}11}$ and $B(\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma})\ensuremath{\simeq}{10}^{\ensuremath{-}7}$, which are within the reach of future experiments. If we assume a large mixing angle solution to the atmospheric neutrino problem, the rate for the process $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\gamma}$ becomes larger. We also discuss the difference between our case and the case of the minimal SU(5) grand unified theory.

Efficient Nonsacrificial Water Splitting through Two-Step Photoexcitation by Visible Light using a Modified Oxynitride as a Hydrogen Evolution Photocatalyst

Abstract: A two-step photocatalytic water splitting (Z-scheme) system consisting of a modified ZrO2/TaON species (H2 evolution photocatalyst), an O2 evolution photocatalyst, and a reversible donor/acceptor pair (i.e., redox mediator) was investigated. Among the O2 evolution photocatalysts and redox mediators examined, Pt-loaded WO3 (Pt/WO3) and the IO3−/I− pair were respectively found to be the most active components. Combining these two components with Pt-loaded ZrO2/TaON achieved stoichiometric water splitting into H2 and O2 under visible light, achieving an apparent quantum yield of 6.3% under irradiation by 420.5 nm monochromatic light under optimal conditions, 6 times greater than the yield achieved using a TaON analogue. To the best of our knowledge, this is the highest reported value to date for a nonsacrificial visible-light-driven water splitting system. The high activity of this system is due to the efficient reaction of electron donors (I− ions) and acceptors (IO3− ions) on the Pt/ZrO2/TaON and Pt/WO3 ph...

Combined Measurement and QCD Analysis of the Inclusive e± p Scattering Cross Sections at HERA

Abstract: A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e(+/-)p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q(2), and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.

Surface emitting semiconductor lasers

Abstract: A description is given of the research progress in developing a vertical-cavity surface-emitting (SE) injection laser based on GaAlAs/GaAs and GaInAsP/InP systems Ultimate laser characteristics, device design, state-of-the-art performances, possible device improvement, and future prospects will also be discussed The authors propose a vertical-cavity surface emitting semiconductor laser To reduce the threshold current, they improved the laser reflector and introduced a circular buried heterostructure The microcavity structure, which is 7 mu m long and 6 mu m in diameter, was realized with a threshold of 6 mA Thus, possibilities of an extremely low threshold current SE laser device and a densely packed two-dimensional array are suggested >