Statistical study on propagation characteristics of Omega signals (VLF) in magnetosphere detected by the Akebono satellite

This paper shows a statistical analysis of 10.2 kHz Omega broadcasts of an artificial signal broadcast from ground stations, propagated in the plasmasphere, and detected using an automatic detection method we developed. We study the propagation patterns of the Omega signals to understand the propagation characteristics that are strongly affected by plasmaspheric electron density and the ambient magnetic field. We show the unique propagation patterns of the Omega 10.2 kHz signal when it was broadcast from two high-middle-latitude stations. We use about eight years of data captured by the Poynting flux analyzer subsystem on board the Akebono satellite from October 1989 to September 1997. We demonstrate that the signals broadcast from almost the same latitude (in geomagnetic coordinates) propagated differently depending on the geographic latitude. We also study propagation characteristics as a function of local time, season, and solar activity. The Omega signal tended to propagate farther on the nightside than on the dayside and was more widely distributed during winter than during summer. When solar activity was at maximum, the Omega signal propagated at a lower intensity level. In contrast, when solar activity was at minimum, the Omega signal propagated at a higher intensity and farther from the transmitter station.Comment: 14 pages, 12 figure

自然電波を利用した地球近傍プラズマ空間のグローバルセンシング法の開発

金沢大学学術メディア創成センター宇宙プラズマ環境の衛星観測や理論・シミュレーションによるモデリングなど種々の研究がすすめられているが、従来の磁気圏観測は衛星を現場に送り込み、「その場(in situ)」を直接計測する形態が主で、磁気圏全体の巨視的な変動の把握が困難であった。本申請課題では、申請者らによって提案された確率差分方程式に基づく「柔軟な」モデルを用い、自然電波の特性からプラズマ圏の電子密度分布を求めるリモートセンシング法を研究・開発した。本研究課題2年目(最終年度)に当たる今年度は、下記の項目について研究を進め、以下の成果を得た。(1)雷起源の自然電波であるホイスラー波の自動検出アルゴリズムの開発テンプレートマッチング法の導入により、ホイスラー波の分散値を高速かつ高精度に推定する手法を開発した。さらに、ノンダクト伝搬・マルチパス伝搬の効果によって、一次近似表現できないホイスラスペクトルも、高速走査法を導入することで定量化することに成功した。(2)あけぼの実観測データに対する応用あけぼの広帯域受信器のデータに開発アルゴリズムを適用し、一軌道に渡るホイスラ波の分散値の空間変化特性を明らかにした。さらに前述の提案アルゴリズムが、十分に衛星上でリアルタイム処理可能な計算量であることも示した。(3)ホイスラの分散値から電子密度の空間分布を求めるアルゴリズムの検討計算機シミュレーションによって、プラズマ圏内を伝搬するホイスラ波の分散値から、プラズマ圏内の電子密度の空間分布が一意に決定できることを証明した。さらにあけぼの衛星の実観測データを使って、数例について実際に電子密度の空間分布推定を行なった。研究課題/領域番号:15760298, 研究期間(年度):2003 – 2004出典：「自然電波を利用した地球近傍プラズマ空間のグローバルセンシング法の開発」研究成果報告書　課題番号15760298（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-15760298/)を加工して作

Bone invasion-targeted chemotherapy with a novel anionic platinum complex (3Pt) for oral squamous cell carcinoma

13301甲第5138号博士（医学）金沢大学博士論文本文Full 以下に掲載：Cancer Science 110(10) pp.3288-3295 2019. Wiley. 共著者：Yoshiya Kasahara, Kazuhira Endo, Takayoshi Ueno, Haruna Ueno, Makiko Moriyama‐Kita, Akira Odani, Tomokazu Yoshizak

Development of a Science Database System Applicable to Various Access Restrictions

金沢大学総合メディア基盤センターWe developed a general-purpose database (DB) system that manages and opens experimental and/or observational data accumulated in universities and academic institutes. This platform works as a web-DB management system in which databases can be easily managed without special skills and facilities. By defining a group manager and data manager, the proposed system defines a flexible access restriction for each user and each unit of datasets under the control of these managers. We demonstrate how a variety of web-DBs are appropriately integrated under one management system in such situations in which each web-DB has a different user interface in its search and data distribution functions and is designed with a different language (or script) and connection method to its DB. In spite of the diversity of web-DBs, the proposed system is highly suitable for practical use

Discovery of proton hill in the phase space during interactions between ions and electromagnetic ion cyclotron waves

宇宙空間で電波を生み出す陽子の集団を発見 --JAXAの人工衛星「あらせ」の観測と解析から--. 京都大学プレスリリース. 2021-07-12.A study using Arase data gives the first observational evidence that the frequency drift of electromagnetic ion cyclotron (EMIC) waves is caused by cyclotron trapping. EMIC emissions play an important role in planetary magnetospheres, causing scattering loss of radiation belt relativistic electrons and energetic protons. EMIC waves frequently show nonlinear signatures that include frequency drift and amplitude enhancements. While nonlinear growth theory has suggested that the frequency change is caused by nonlinear resonant currents owing to cyclotron trapping of the particles, observational evidence for this has been elusive. We survey the wave data observed by Arase from March, 2017 to September 2019, and find the best falling tone emission event, one detected on 11th November, 2017, for the wave particle interaction analysis. Here, we show for the first time direct evidence of the formation of a proton hill in phase space indicating cyclotron trapping. The associated resonance currents and the wave growth of a falling tone EMIC wave are observed coincident with the hill, as theoretically predicted

学術情報部門活動報告

[総合メディア基盤センター活動報告

Spin fluctuations from Bogoliubov Fermi surfaces in the superconducting state of S-substituted FeSe

The study of the iron-based superconductor, FeSe, has resulted in various topics, such as the interplay among superconductivity, nematicity, and magnetism, Bardeen-Cooper-Schrieffer Bose-Einstein-condensation (BCS-BEC) crossover, and Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconductivity. Recently, topologically protected nodal Fermi surfaces, referred to as Bogoliubov Fermi surfaces (BFSs), have garnered much attention. A theoretical model for the S-substituted FeSe system demonstrated that BFSs can manifest under the conditions of spin-orbit coupling, multi-band systems, and superconductivity with time-reversal symmetry breaking. Here we report the observation of spin fluctuations originating from BFSs in the superconducting (SC) state via $^{77}$Se-nuclear magnetic resonance measurements to 100 mK. In a heavily S-substituted FeSe, we found an anomalous enhancement of low-energy spin fluctuations deep in the SC state, which cannot be explained by an impurity effect. Such unusual behavior implies the presence of significant spin fluctuations of Bogoliubov quasiparticles, which are associated with possible nesting properties between BFSs

Spatial Evolution of Wave‐Particle Interaction Region Deduced From Flash‐Type Auroras and Chorus‐Ray Tracing

In-situ observations of spatial variations of the wave-particle interaction region require a large number of satellite probes. As an alternative, flash-type auroras, a kind of pulsating aurora, driven by discrete chorus elements, can be used to investigate the interaction region with a high spatial resolution. We estimated the spatial extent of wave-particle interaction region from ground-based observations of flash aurora at Gakona (62.39°N, 214.78°E), Alaska at subauroral latitudes, and found that the auroral expansion was predominantly to the low-latitude side. The spatial displacement is thought to be caused by the propagation effects of chorus waves in the magnetosphere. Using ray tracing analysis to take into account chorus wave propagation, we reconstructed the spatiotemporal evolution of the volume emission rate and confirmed that the predominant expansion is toward the lower-latitude side in the ionosphere. This study shows that chorus wave propagation in the magnetosphere gives new insight for characterizing the transverse size (across the geomagnetic field line) of wave-particle interaction regions. The calculated spatial scale of the column auroral emission shows a correlation with the magnetic latitude of the resonance region at magnetic latitudes within 10° of the equatorial plane of the magnetosphere. Our results suggest that the spatial scale of a flash aurora is indirectly related to the chorus amplitude because the latitudinal range of the wave-particle interaction is important for the growth of wave amplitude

データリポジトリの横断検索のためのタグ管理システム

金沢大学総合メディア基盤センター近年, 世界では論文や研究データを始めとした研究成果などに対してアクセスを容易にし, データの発信, 共有, 再利用を促すことを目的としたオープンサイエンスと呼ばれる試みが活発になってきているこれに伴って国内でも既存のリポジトリソフトウェアを利用して，論文だけでなく，研究データを対象としたデータリポジトリの構築が行われている．しかし，データリポジトリとして利用することを考えた場合，メタデータを画一化できないことなどから，ユーザが所望したデータにたどりつけないなど，現状では共有，再利用は容易ではない．そこで, 本研究ではこの問題を解決しより利便性を向上させるインターフェースの開発を目的としている. 本インターフェースは, ユーザがより容易にアイテムを共有, 再利用できるよう，アイテムにタグを割り振ることによって，メタデータに欠けているものを補完し管理を行うシステムである.Recent years, an attempt for the purpose of publishing, sharing, reusing data called "Open Science" has become active for easier access to papers and research data. Along with this, in Japan, academic repositories are built at many academic research institutions using a repository system named WEKO. When we consider using WEKO as a data repository, it is not easy for the users to search the data which they wish because metadata are not well standardized in many academic elds. In the present study, we developed a new user interface for the data repository using WEKO3, which is expected to be a mainstream of repository system in the future. This interface is a system that manages items by assigning tags to them, and aims to form collective knowledge by sharing tags among multiple repositories