Slow Diffusion of Cosmic-Rays around a Supernova Remnant (2010)
Fujita, Yutaka, Ohira, Yutaka, Takahara, Fumio
We study the escape of cosmic-ray protons accelerated at a supernova remnant (SNR). We are interested in their propagation in interstellar medium (ISM) after they leave the shock neighborhood where...
Effects of Neutral Particles on Modified Shocks at Supernova Remnants (2009)
Ohira, Yutaka, Takahara, Fumio
H-alpha emission from supernova remnants (SNRs) implies the existence of neutral hydrogens in the ambient medium. In the precursor of an SNR shock modified by cosmic rays (CRs), upstream plasmas are...
Molecular Clouds as a Probe of Cosmic-Ray Acceleration in a Supernova Remnant (2009)
Fujita, Yutaka, Ohira, Yutaka, Tanaka, Shuta J., Takahara, Fumio
We study cosmic-ray acceleration in a supernova remnant (SNR) and the escape from it. We model nonthermal particle and photon spectra for the hidden SNR in the open cluster Westerlund 2, and the...
Escape-limited Model of Cosmic-ray Acceleration Revisited (2009)
Ohira, Yutaka, Murase, Kohta, Yamazaki, Ryo
The spectrum of cosmic rays (CRs) is affected by their escape from an acceleration site. This may have been observed not only in the gamma-ray spectrum of young supernova remnants (SNRs) such as RX...
Ohira, Yutaka, Terasawa, Toshio, Takahara, Fumio
H-alpha emission from supernova remnants (SNRs) implies the existence of neutral hydrogen in the circumstellar medium. Some of the neutral particles penetrating the shock are ionized by the charge...
Ohira, Yutaka, Reville, Brian, Kirk, John G., Takahara, Fumio
In supernova remnants, the nonlinear amplification of magnetic fields upstream of collisionless shocks is essential for the acceleration of cosmic rays to the energy of the "knee" at $10^{15.5}$ eV....
Ohira, Yutaka, Reville, Brian, Kirk, John G., Takahara, Fumio
In supernova remnants, the nonlinear amplification of magnetic fields upstream of collisionless shocks is essential for the acceleration of cosmic rays to the energy of the "knee" at 10^{15.5}eV. A...
Oblique Ion Two-Stream Instability in the Foot Region of a Collisionless Shock (2008)
Ohira, Yutaka, Takahara, Fumio
Electrostatic behavior of a collisionless plasma in the foot region of high Mach number perpendicular shocks is investigated through the two-dimensional linear analysis and electrostatic...
水田地域における生態系保全水路の実用可能性の検討 (2008)
大平, 裕, 弓削, こずえ, 栗山, 竜司, 安東, 茂, 阿南, 光政, Ohira, Yutaka, ...
コンクリート製の U 型水路は， カエル類の産卵と成長のために不可欠な樹林－水田間のエコロジカルコリドーを分断し，...
Anan, Mitsumasa, Yuge, Kozue, Ohira, Yutaka, Nakano, Yoshisuke, 阿南, 光政, 弓削, こずえ, ...
The objective of this study is evaluating the effect of the land use condition on the ecological system in the rural area. The field observation was conducted in a 600ha study site, which is located...
Absence of Electron Surfing Acceleration in a Two-Dimensional Simulation (2007)
Ohira, Yutaka, Takahara, Fumio
Electron acceleration in high Mach number perpendicular shocks is investigated through two-dimensional electrostatic particle-in-cell (PIC) simulation. We simulate the shock foot region by modeling...
阿南, 光政, 大平, 裕, 弓削, こずえ, 中野, 芳輔, Anan, Mitsumasa, Ohira, Yutaka, ...
本研究では,水田の利用形態が生物の生息環境に与える影響を評価するため,土地利用形態の異なる水田3筆について,生態系調査を実施した.調査は,水...
農家管理による水田生態系保全を目的とした小型魚道の開発(Ⅰ) : 室内実験によるモデル魚道の流況評価 (2006)
大平, 裕, 中野, 芳輔, 弓削, こずえ, 林田, 創, Ohira, Yutaka, Nakano, Yoshisuke, ...
農村地域の生態系保全は,水路などの農業水利施設などを利用した水生生物のエコロジカルコリドー機能の保全と向上が重要である.河川や頭首工では...
農家管理による水田生態系保全を目的とした小型魚道の開発(Ⅱ) : モデル魚道による遡上効果の評価 (2006)
大平, 裕, 中野, 芳輔, 弓削, こずえ, 柴田, 幸二, Ohira, Yutaka, Nakano, Yoshisuke, ...
本研究は,堰や落差工で分断された水路のエコロジカルコリドー機能を,農家や住民参加により保全,向上することを目的に,ラダー型魚道,フリュ-ム型...
農家管理による水田生態系保全を目的とした小型魚道の開発(Ⅲ) : 現地実験による魚道3タイプの遡上効果の実証 (2006)
大平, 裕, 中野, 芳輔, 弓削, こずえ, 柴田, 幸二, Ohira, Yutaka, Nakano, Yoshisuke, ...
本研究は,住民参加による水路の生態系保全活動に資することを目的とした小型魚道の開発の一環として,現地実験によりラダー型魚道,フリュ-ム型魚...
農家管理による水田生態系保全を目的とした小型魚道の開発(Ⅳ) : 現地実験による斜水路型および連続堰型魚道の遡上効果の実証 (2006)
大平, 裕, 中野, 芳輔, 弓削, こずえ, 柴田, 幸二, Ohira, Yutaka, Nakano, Yoshisuke, ...
本研究は,農村生態系の保全に貢献することを目的とした平板斜水路型魚道,小段斜水路型魚道,連続堰型魚道の遡上効果を,灌漑期の水路を用いた現地...