Aoyama Gakuin University

About: Aoyama Gakuin University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Superconductivity & Thin film. The organization has 3494 authors who have published 6419 publications receiving 115648 citations. The organization is also known as: Aoyama gakuin daigaku.

Energy gaps in Bi-Sr-Ca-Cu-O and Bi-Sr-Cu-O systems by electron tunneling.

Abstract: We report the results of electron tunneling studies of the Bi-Sr-Ca-Cu-O and Bi-Sr-Cu-O systems by using point-contact tunneling. In these studies, we observed two distinctive energy gaps at each Bi-Sr-Ca-Cu-O system, having extremely large values. The larger values of the ratios 2{Delta}/{ital kT}{sub {ital c}} are 10--12 for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} and 9--11 for Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}Oi{sub {ital y}} and the smaller values are 5.5--6.1 for Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub {ital y}}. These differences can be attributed to the gap anisotropies and the ratios of gaps are 1.7--1.8 for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub {ital y}} and 1.5--1.8 for Bi{sub 2}Sr{sub 2}Ca{sub 2}C{sub 3}O{sub {ital y}}. The ratio 2{Delta}/{ital kT}{sub {ital c}} in the Ca-absent material Bi{sub 2}Sr{sub 2}CuO{sub {ital y}} was obtained as 5.4--7.4. The gap values are quite reproducible for the bulk, single crystal, and thin films.

Fast Negative Photochromism of 1,1'-Binaphthyl-Bridged Phenoxyl-Imidazolyl Radical Complex.

Abstract: Negative photochromism, in which a thermally stable colored form isomerizes to the transient colorless form by light irradiation and the back reaction occurs thermally, is advantageous in its applications for photoswitching materials because visible light can cause the photochromic color change of the materials. Moreover, the photochromic color change can be induced even on the inside of the materials due to the absence of the reabsorption of the visible excitation light by the photogenerated colorless species. While several negative photochromic compounds have been reported, the time scales of the back reaction are still slower than minutes, and no available fast responsive negative photochromic compounds have been reported. Here, we developed a negative photochromic 1,1′-binaphthyl-bridged phenoxyl–imidazolyl radical complex (BN-PIC) which enables fast photoswitching by visible light. The stable colored BN-PIC shows instantaneous decoloration by visible light irradiation, and the photogenerated colorles...

The Swift/BAT Hard X-ray Transient Monitor

Abstract: The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for a full-day observation and a time resolution as fine as 64 seconds. The three main purposes of the monitor are (1) the discovery of new transient X-ray sources, (2) the detection of outbursts or other changes in the flux of known X-ray sources, and (3) the generation of light curves of more than 900 sources spanning over eight years. The primary interface for the BAT transient monitor is a public web page. Between 2005 February 12 and 2013 April 30, 245 sources have been detected in the monitor, 146 of them persistent and 99 detected only in outburst. Among these sources, 17 were previously unknown and were discovered in the transient monitor. In this paper, we discuss the methodology and the data processing and filtering for the BAT transient monitor and review its sensitivity and exposure. We provide a summary of the source detections and classify them according to the variability of their light curves. Finally, we review all new BAT monitor discoveries; for the new sources that are previously unpublished, we present basic data analysis and interpretations.

Cosmological perturbations in a healthy extension of Hořava gravity

Abstract: In Hořava's theory of gravity, Lorentz symmetry is broken in exchange for renormalizability, but the original theory has been argued to be plagued with problems associated with a new scalar mode stemming from the very breaking of Lorentz symmetry. Recently, Blas, Pujolas, and Sibiryakov have proposed a healthy extension of Hořava gravity, in which the behavior of the scalar mode is improved. In this paper, we study scalar modes of cosmological perturbations in extended Hořava gravity. The evolution of metric and density perturbations is addressed analytically and numerically. It is shown that for vanishing non-adiabatic pressure of matter the large scale evolution of cosmological perturbations converges to that described by a single constant, ζ, which is an analog of a curvature perturbation on the uniform-density slicing commonly used in usual gravitational theories. The subsequent evolution is thus determined completely by the value of ζ.

Suzaku Discovery of a Hard X-Ray Tail in the Persistent Spectra from the Magnetar 1E 1547.0-5408 during its 2009 Activity

Abstract: The fastest-rotating magnetar 1E 1547.0-5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28-29, 7 days after the onset of its latest bursting activity. After removing burst events, the absorption-uncorrected 2-10 keV flux of the persistent emission was measured with the XIS as 5.7e-11 ergs cm-2 s-1, which is 1-2 orders of magnitude higher than was measured in 2006 and 2007 when the source was less active. The persistent emission was also detected significantly with the HXD in >10 keV up to at least ~110 keV, with an even higher flux of 1.3e-10 ergs cm-2 s-1 in 20-100 keV. The pulsation was detected at least up to 70 keV at a period of 2.072135+/-0.00005 s, with a deeper modulation than was measured in a fainter state. The phase-averaged 0.7-114 keV spectrum was reproduced by an absorbed blackbody emission with a temperature of 0.65+/-0.02 keV, plus a hard power-law with a photon index of ~1.5. At a distance of 9 kpc, the bolometric luminosity of the blackbody and the 2-100 keV luminosity of the hard power-law are estimated as (6.2+/-1.2)e+35 ergs s-1 and 1.9e+36 ergs s-1, respectively, while the blackbody radius becomes ~5 km. Although the source had not been detected significantly in hard X-rays during the past fainter states, a comparison of the present and past spectra in energies below 10 keV suggests that the hard component is more enhanced than the soft X-ray component during the persistent activity.