Wino Dark Matter and Future dSph Observations

We discuss the indirect detection of the wino dark matter utilizing gamma-ray observations of dwarf spheroidal galaxies (dSphs). After carefully reviewing current limits with particular attention to astrophysical uncertainties, we show prospects of the wino mass limit in future gamma-ray observation by the Fermi-LAT and the GAMMA-400 telescopes. We find that the improvement of the so-called $J$-factor of both the classical and the ultra-faint dSphs will play a crucial role to cover whole mass range of the wino dark matter. For example, with $\delta (\log_{10}J) = 0.1$ for both the classical and the ultra-faint dSphs, whole wino dark matter mass range can be covered by 15 years and 10 years data at the Fermi-LAT and GAMMA-400 telescopes, respectively.Comment: 32 pages, 13 figure

Antioxidant Activity of Intramolecularly Hydrogen Bonded 2-Aminophenol

The antioxidant activities of five classes of 2-aminophenol (model compound) and 2-aminophenols with substituent at the phenyl ring were studied in the oxidation of tetralin induced by an azo-initiator at 61℃. 2-Aminophenols with electron-donating groups at the 4-position exhibited higher antioxidant activity than that of the model compound. However, introduction of the methoxy group at the 4-position reduced the antioxidant activity by 8 % that of the model compound. 2-Aminophenols with electron-donating groups at the 5-position have little effect on the antioxidant activity. 2-Aminophenols with electron-donating groups at both the 4- and 6-positions showed remarkable antioxidant activity. These results were discussed in terms of the hydrogen bonding effect and bond dissociation energies of the O-H and NH-H bonds

Examination of Wireless Power Transfer Combined With the Utilization of Distance Detection

Wireless power transfer using magnetic resonant coupling is expected to be widely used in the charging of an electric vehicle and in the use of home electric appliances. Wireless power transfer requires a high efficiency and power transfer over a long distance. However, the efficiency is reduced by the increase of the transmission distance and the change of the impedance of the receiving load. Therefore, a distance sensor using magnetic resonant coupling is proposed. In this paper, we propose a method of power transfer and distance detection using one couple of coils in real time. We also propose to use different frequencies in the power transfer and the distance detection, which are superposed and separated. Using the proposed approach, we demonstrated that the power transfer and the distance detection can be performed without relying on the change of the transmission distance.ArticleIEEE TRANSACTIONS ON MAGNETICS. 50(11):4005304 (2014)journal articl

LLC resonance power transformers using magnetoplated wire

The use of magneto-plated wire (MPW) allows for reduction of winding loss component from the proximity effect. compared with a copper wire (COW). A MPW is a COW with a circumference that is plated with a magnetic thin film. In this paper, we clarify the basic characteristics and the efficiency characteristics of a transformer using a MPW and a COW. We found that the resistances of a primary coil made of COW and MPW at a frequency f = 500 kHz are 1.56 Omega and 1.12 Omega, respectively, and decreased 28%. The short circuit inductances of the COW and the MPW at a frequency f = 500 kHz are 26 mu H and 29.6 mu H, respectively, and increased 13.8%. The efficiencies of an LLC resonant converter using the COW and the MPW at a frequency f = 500 kHz are 90.2% and 92.2%, respectively, and increased 2%.ArticleINTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS. 47(3):719-727 (2015)journal articl

Suzaku X-Ray Spectroscopy of a Peculiar Hot Star in the Galactic Center Region

We present the results of a Suzaku study of a bright point-like source in the 6.7 keV intensity map of the Galactic center region. We detected an intense FeXXV 6.7 keV line with an equivalent width of ~1 keV as well as emission lines of highly ionized Ar and Ca from a spectrum obtained by the X-ray Imaging Spectrometer. The overall spectrum is described very well by a heavily absorbed (~2x10^{23}cm^{-2}) thin thermal plasma model with a temperature of 3.8+/-0.6 keV and a luminosity of ~3x10^{34} erg s^{-1} (2.0--8.0 keV) at 8 kpc. The absorption, temperature, luminosity, and the 6.7 keV line intensity were confirmed with the archived XMM-Newton data. The source has a very red (J-Ks=8.2 mag) infrared spectral energy distribution (SED), which was fitted by a blackbody emission of ~1000 K attenuated by a visual extinction of ~31 mag. The high plasma temperature and the large X-ray luminosity are consistent with a wind-wind colliding Wolf-Rayet binary. The similarity of the SED to those of the eponymous Quintuplet cluster members suggests that the source is a WC-type source.Comment: Accepted for publication on PASJ Vol.60, SP-1, 200