University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

A simple and faster branch-and-bound algorithm for finding a maximum clique

Abstract: This paper proposes new approximate coloring and other related techniques which markedly improve the run time of the branch-and-bound algorithm MCR (J. Global Optim., 37, 95–111, 2007), previously shown to be the fastest maximum-clique-finding algorithm for a large number of graphs. The algorithm obtained by introducing these new techniques in MCR is named MCS. It is shown that MCS is successful in reducing the search space quite efficiently with low overhead. Consequently, it is shown by extensive computational experiments that MCS is remarkably faster than MCR and other existing algorithms. It is faster than the other algorithms by an order of magnitude for several graphs. In particular, it is faster than MCR for difficult graphs of very high density and for very large and sparse graphs, even though MCS is not designed for any particular type of graphs. MCS can be faster than MCR by a factor of more than 100,000 for some extremely dense random graphs.

Suppression of Charge Carrier Recombination in Lead-Free Tin Halide Perovskite via Lewis Base Post-treatment.

Abstract: Lead-free tin perovskite solar cells (PSCs) show the most promise to replace the more toxic lead-based perovskite solar cells. However, the efficiency is significantly less than that of lead-based PSCs as a result of low open-circuit voltage. This is due to the tendency of Sn2+ to oxidize into Sn4+ in the presence of air together with the formation of defects and traps caused by the fast crystallization of tin perovskite materials. Here, post-treatment of the tin perovskite layer with edamine Lewis base to suppress the recombination reaction in tin halide PSCs results in efficiencies higher than 10%, which is the highest reported efficiency to date for pure tin halide PSCs. The X-ray photoelectron spectroscopy data suggest that the recombination reaction originates from the nonstoichiometric Sn:I ratio rather than the Sn4+:Sn2+ ratio. The amine group in edamine bonded the undercoordinated tin, passivating the dangling bonds and defects, resulting in suppressed charge carrier recombination.

A luciferin analogue generating near-infrared bioluminescence achieves highly sensitive deep-tissue imaging

Abstract: In preclinical cancer research, bioluminescence imaging with firefly luciferase and D-luciferin has become a standard to monitor biological processes both in vitro and in vivo. However, the emission maximum (λmax) of bioluminescence produced by D-luciferin is 562 nm where light is not highly penetrable in biological tissues. This emphasizes a need for developing a red-shifted bioluminescence imaging system to improve detection sensitivity of targets in deep tissue. Here we characterize the bioluminescent properties of the newly synthesized luciferin analogue, AkaLumine-HCl. The bioluminescence produced by AkaLumine-HCl in reactions with native firefly luciferase is in the near-infrared wavelength ranges (λmax=677 nm), and yields significantly increased target-detection sensitivity from deep tissues with maximal signals attained at very low concentrations, as compared with D-luciferin and emerging synthetic luciferin CycLuc1. These characteristics offer a more sensitive and accurate method for non-invasive bioluminescence imaging with native firefly luciferase in various animal models. D-luciferin is the standard bioluminescent substrate for in vitro and in vivo imaging. Here the authors introduce AkaLumine-HCl, a soluble luciferin analogue with a near-infrared emission maximum, which allows deep tissue imaging at lower concentrations than D-luciferin.

ULF electromagnetic precursors for an earthquake at Biak, Indonesia on February 17, 1996

Abstract: ULF electromagnetic emissions associated with a large earthquake occurred at Biak Island, Indonesia at 5h 59m UT on February 17, 1996 (magnitude (Mw) = 8.2 and depth = 20 km from USGS catalog), have been investigated on the basis of ULF magnetic observations at two stations, Biak and Darwin in Australia (about 1,200 km apart). Though a simple analysis of magnetic field intensity (horizontal and vertical magnetic field components) at both stations was found to be closely correlated with geomagnetic ΣKp activity, a detailed analysis of the difference of H and Z components at the two stations, the polarization analysis (Z/H) and fractal analysis (frequency spectrum slope) at these two stations has yielded that the ULF emissions (in the frequency range from 5 mHz to 30 mHz) about 1.5–1.0 months before the quake are likely to be a precursory signature of the quake with its intensity on the order of 0.2–0.3 nT.