Boundary between the near-Earth (<10RE) plasma sheet and outer plasma sheet: Equatorial observations at 9-15 RE by Geotail

Equatorial observations of a boundary between the near-Earth (<10R_E) plasma sheet and outer plasma sheet in the magnetotail are reported in the present paper. Analyzing energy-time spectrograms of low energy particles obtained by the Geotail spacecraft, we find that there often exists a boundary between the near-Earth plasma sheet and the tail plasma sheet. At this boundary, fluctuating particle spectra in the magnetotail change to stable spectra in the near-Earth region and energy flux of particles increases rapidly. Repeated observations of these signatures suggest that there often exists a spatial boundary between the two regions. In the present paper, we call this boundary near-Earth plasma sheet boundary (NEPS boundary)" and examine it in detail. We show that the NEPS boundary is located usually at distances of around 9-15R_E on the night side near the magnetospheric equator. We also discuss a new method of mapping, in which the NEPS boundary is used as a tracer to map auroral regions to the magnetosphere without using field-line models

Comparative study of the inial spikes of SGR giant flares in 1998 and 2004 observed with GEOTAIL: Do magnetospheric instabilities trigger large scale fracturing of magnetar's crust?

We present the unsaturated peak profile of SGR 1900+14 giant flare on 1998 August 27. This was obtained by particle counters of the Low Energy Particle instrument onboard the GEOTAIL spacecraft. The observed peak profile revealed four characteristic structures: initial steep rise, intermediate rise to the peak, exponential decay and small hump in the decay phase. From this light curve, we found that the isotropic peak luminosity was $2.3\times10^{46}$ erg s$^{-1}$ and the total energy was $4.3 \times 10^{44}$ erg s$^{-1}$ ($E\gtrsim$ 50 keV), assuming that the distance to SGR 1900+14 is 15 kpc and that the spectrum is optically thin thermal bremsstrahlung with $kT =$ 240 keV. These are consistent with the previously reported lower limits derived from Ulysses and Konus-Wind observations. A comparative study of the initial spikes of SGR 1900+14 giant flare in 1998 and SGR 1806-20 in 2004 is also presented. The timescale of the initial steep rise shows the magnetospheric origin, while the timescale of the intermediate rise to the peak indicates that it originates from the crustal fracturing. Finally, we argue that the four structures and their corresponding timescales provide a clue to identify extragalactic SGR giant flares among short GRBs.Comment: 12 pages, 3 figures, accepted by ApJ

Low energy high angular resolution neutral atom detection by means of micro-shuttering techniques: the BepiColombo SERENA/ELENA sensor

The neutral sensor ELENA (Emitted Low-Energy Neutral Atoms) for the ESA cornerstone BepiColombo mission to Mercury (in the SERENA instrument package) is a new kind of low energetic neutral atoms instrument, mostly devoted to sputtering emission from planetary surfaces, from E ~20 eV up to E~5 keV, within 1-D (2x76 deg). ELENA is a Time-of-Flight (TOF) system, based on oscillating shutter (operated at frequencies up to a 100 kHz) and mechanical gratings: the incoming neutral particles directly impinge upon the entrance with a definite timing (START) and arrive to a STOP detector after a flight path. After a brief dissertation on the achievable scientific objectives, this paper describes the instrument, with the new design techniques approached for the neutral particles identification and the nano-techniques used for designing and manufacturing the nano-structure shuttering core of the ELENA sensor. The expected count-rates, based on the Hermean environment features, are shortly presented and discussed. Such design technologies could be fruitfully exported to different applications for planetary exploration.Comment: 11 page

Development of the Virtual Earth\u27s Magnetosphere System (VEMS)

We have constructed a new research environment for geo-space science based on 3-D visualization tool and network database; Virtual Earth\u27s Magnetosphere System (VEMS). With an interactive research environment researchers can visually understand structures of the Earth\u27s magnetosphere using VEMS. On the VEMS, computer simulation results and observation data are simultaneously visualized, having a potential to data assimilation for geo-space studies in the future. Since the VEMS deals with time-dependent data, it also helps researchers to study dynamics of the Earth\u27s magnetosphere. We found that immersive data analyses are possible using the VEMS on a virtual reality system

GEOTAIL observation of the SGR1806-20 Giant Flare: The first 600 ms

On December 27, 2004, plasma particle detectors on the GEOTAIL spacecraft detected an extremely strong signal of hard X-ray photons from the giant flare of SGR1806-20, a magnetar candidate. While practically all gamma-ray detectors on any satellites were saturated during the first ~500 ms interval after the onset, one of the particle detectors on GEOTAIL was not saturated and provided unique measurements of the hard X-ray intensity and the profile for the first 600 ms interval with 5.48 ms time resolution. After ~50 ms from the initial rapid onset, the peak photon flux (integrated above ~50 keV) reached the order of 10^7 photons sec^{-1} cm^{-2}. Assuming a blackbody spectrum with kT=175 keV, we estimate the peak energy flux to be 21 erg sec^{-1} cm^{-2} and the fluence (for 0-600 ms) to be 2.4 erg cm^{-2}. The implied energy release comparable to the magnetic energy stored in a magnetar (~10^{47} erg) suggests an extremely efficient energy release mechanism.Comment: 6 pages, 2 color figures, submitted to Natur

Photoelectron Current Density Emitted from GEOTAIL Spacecraft in Low-density Plasma Estimated from Measurements of Spacecraft Potential and Ambient Plasma

departmental bulletin pape

Tokyo Guidelines 2018 management bundles for acute cholangitis and cholecystitis

Management bundles that define items or procedures strongly recommended in clinical practice have been used in many guidelines in recent years. Application of these bundles facilitates the adaptation of guidelines and helps improve the prognosis of target diseases. In Tokyo Guidelines 2013 (TG13), we proposed management bundles for acute cholangitis and cholecystitis. Here, in Tokyo Guidelines 2018 (TG18), we redefine the management bundles for acute cholangitis and cholecystitis. Critical parts of the bundles in TG18 include the diagnostic process, severity assessment, transfer of patients if necessary, and therapeutic approach at each time point. Observance of these items and procedures should improve the prognosis of acute cholangitis and cholecystitis. Studies are now needed to evaluate the dissemination of these TG18 bundles and their effectiveness. Free full articles and mobile app of TG18 are available at: . Related clinical questions and references are also include

Characteristics of the inverted-V events observed by the KYOKKO satellite

Measurements of both upward and downward electron fluxes on the KYOKKO satellite have revealed following characteristics of the inverted-V events. (1) Inverted-V events have various durations from a few tens of seconds up to several minutes. Existence of the long-duration structure with nearly constant energy of the monoenergetic peak indicates that the inverted-V structure is stable rather than transient and also that the equipotential contours of the electric field for acceleration of auroral electrons are extensive in longitude and have a meridional cross-section that is V-shaped. (2) The source region of inverted-V electrons seems to be on the closed field lines as well as on the open field lines. (3) Inverted-V events occur at all local times except around noon and at higher latitudes in the dayside hemisphere, although the occurrence frequency is least in the morning sector (0300-1200MLT). They occur most frequently at invariant latitudes of 65°-70° in the premidnight sector under disturbed conditions

半球型静電エネルギー分析装置の研究およびロケット・科学衛星による低エネルギー電子測定への応用

京都大学0048新制・論文博士工学博士乙第6030号論工博第1979号新制||工||674(附属図書館)UT51-61-O267(主査)教授 木村 磐根, 教授 加藤 進, 教授 板谷 良平学位規則第5条第2項該当Kyoto UniversityDFA

Coexistence of polar arcs with patches ─Results from the simultaneous observations by Akebono satellite and all-sky imager at Qaanaaq─

To understand the processes of formation of polar arcs together with patches, an investigation has been made based on the simultaneous observations with an all-sky imager at Qaanaaq in Greenland and Akebono (EXOS-D) satellite. On some occasions, we have identified coexistence of polar arcs with patches. Specifically, polar arcs were replaced by patches or vise versa. These phenomena have been seen in the transient periods of IMF polarity change. Growth and decay of polar arcs with respect to the IMF polarity change has also been investigated with a particular interest in a delay time. The delay time was in a range from 30min to 1 hour. Since a life time of patches seems to be longer than 1hour, the coexistence was noticed by the all-sky imager at Qaanaaq