A procedure for stable electrical measurements on a rock sample against high contact resistance as a prerequisite for electrical tomography

令和4年度 Conductivity Anomaly研究会日時：令和4年12月26日（月）09:25-18:30, 12月27日（火）09:00-16:30場所：京都大学防災研究所連携研究棟3階301号室およびZoo

Magnetotelluric and temperature monitoring after the 2011 sub-Plinian eruptions of Shinmoe-dake volcano

Three sub-Plinian eruptions took place on 26–27 January 2011 at Shinmoe-dake volcano in the Kirishima volcanic group, Japan. During this event, GPS and tiltmeters detected syn-eruptive ground subsidence approximately 7 km to the WNW of the volcano. Starting in March 2011, we conducted broad-band magnetotelluric (MT) measurements at a site located 5 km NNW of the volcano, beneath which the Shinmoe-dake magma plumbing system may exist. In addition, temperature monitoring of fumaroles and hot-springs near the MT site was initiated in July 2011. Our MT data record changes in apparent resistivity of approximately ±5%, along with a ±1◦ phase change in the off-diagonal component of the impedance tensor (Zxy and Zyx ). Using 1-D inversion, we infer that these slight changes in resistivity took place at relatively shallow depths of only a few hundred meters, at the transition between a near-surface resistive layer and an underlying conductive layer. Resistivity changes observed since March 2012 are correlated with the observed temperature increases around the MT monitoring site. These observations suggest the existence beneath the MT site of pathways which enable volatile escape

Seismicity controlled by resistivity structure : the 2016 Kumamoto earthquakes, Kyushu Island, Japan

The M JMA 7.3 Kumamoto earthquake that occurred at 1:25 JST on April 16, 2016, not only triggered aftershocks in the vicinity of the epicenter, but also triggered earthquakes that were 50–100 km away from the epicenter of the main shock. The active seismicity can be divided into three regions: (1) the vicinity of the main faults, (2) the northern region of Aso volcano (50 km northeast of the mainshock epicenter), and (3) the regions around three volcanoes, Yufu, Tsurumi, and Garan (100 km northeast of the mainshock epicenter). Notably, the zones between these regions are distinctively seismically inactive. The electric resistivity structure estimated from one-dimensional analysis of the 247 broadband (0.005–3000 s) magnetotelluric and telluric observation sites clearly shows that the earthquakes occurred in resistive regions adjacent to conductive zones or resistive-conductive transition zones. In contrast, seismicity is quite low in electrically conductive zones, which are interpreted as regions of connected fluids. We suggest that the series of the earthquakes was induced by a local accumulated stress and/or fluid supply from conductive zones. Because the relationship between the earthquakes and the resistivity structure is consistent with previous studies, seismic hazard assessment generally can be improved by taking into account the resistivity structure. Following on from the 2016 Kumamoto earthquake series, we suggest that there are two zones that have a relatively high potential of earthquake generation along the western extension of the MTL

Identification and structural analysis of C-terminally truncated collapsin response mediator protein-2 in a murine model of prion diseases

<p>Abstract</p> <p>Background</p> <p>Prion diseases are fatal neurodegenerative disorders that accompany an accumulation of the disease-associated form(s) of prion protein (PrP^Sc) in the central nervous system. The neuropathological changes in the brain begin with focal deposits of PrP^Sc, followed by pathomorphological abnormalities of axon terminal degeneration, synaptic loss, atrophy of dendritic trees, and eventual neuronal cell death in the lesions. However, the underlying molecular basis for these neuropathogenic abnormalities is not fully understood.</p> <p>Results</p> <p>In a proteomic analysis of soluble proteins in the brains of mice challenged intracerebrally with scrapie prion (Obihiro I strain), we found that the amount of the full-length form of collapsin response mediator protein-2 (CRMP-2; 61 kDa) decreased in the late stages of the disease, while the amount of its truncated form (56 kDa) increased to comparable levels observed for the full-length form. Detailed analysis by liquid chromatography-electrospray ionization-tandem mass spectrometry showed that the 56-kDa form (named CRMP-2-ΔC) lacked the sequence from serine⁵¹⁸to the C-terminus, including the C-terminal phosphorylation sites important for the regulation of axonal growth and axon-dendrite specification in developing neurons. The invariable size of the mRNA transcript in Northern blot analysis suggested that the truncation was due to post-translational proteolysis. By overexpression of CRMP-2-ΔC in primary cultured neurons, we observed the augmentation of the development of neurite branch tips to the same levels as for CRMP-2^T514A/T555A, a non-phosphorylated mimic of the full-length protein. This suggests that the increased level of CRMP-2-ΔC in the brain modulates the integrity of neurons, and may be involved in the pathogenesis of the neuronal abnormalities observed in the late stages of the disease.</p> <p>Conclusions</p> <p>We identified the presence of CRMP-2-ΔC in the brain of a murine model of prion disease. Of note, C-terminal truncations of CRMP-2 have been recently observed in models for neurodegenerative disorders such as ischemia, traumatic brain injury, and Wallerian degeneration. While the structural identity of CRMP-2-ΔC in those models remains unknown, the present study should provide clues to the molecular pathology of degenerating neurons in prion diseases in connection with other neurodegenerative disorders.</p

地殻活動地磁気現象検出のための地域地磁気モデルの精度 : 北陸・近畿・中国地方における観測点の効果

地球主磁場の空間分布についてのいくつかの仮定にもとづき，観測所データをもとに構成可能な日本周辺の地域地磁気モデルの決定精度を評価した。地域地磁気モデルは，地磁気変化のなかから地殻活動起源のわずかな変化を抽出するための基準として用いられるものであり，1 nT よりも高い精度が求められる。評価の結果，西日本におけるモデルの精度が不十分であることが示された。防災研究所が展開する地磁気観測点のなかでは，鳥取観測点の位置におけるモデル決定精度がもっとも低く，同観測点における地磁気観測が日本周辺の地域地磁気モデルの精度向上のために最重要であることが結論される。Accuracy of the regional geomagnetic field model based on geomagnetic observatories in Japan has been examined under some assumptions on the spatial distribution of the Earth's geomagnetic main field variation. The geomagnetic field model is used as a reference to distinguish small tectonomagnetic signals which are as small as 1 nT from the main field variation, so that the model should be more accurate than 1 nT. This criterion is satisfied in east Japan, whereas it is not satisfied in the vast part of west Japan. It is clarified that the model has the least accuracy at the place of the TOT site among all stations deployed by Disaster Prevention Research Institute (DPRI). This means that the TOT site has a great importance to determine more accurate reference field models.地球主磁場の空間分布についてのいくつかの仮定にもとづき，観測所データをもとに構成可能な日本周辺の地域地磁気モデルの決定精度を評価した。地域地磁気モデルは，地磁気変化のなかから地殻活動起源のわずかな変化を抽出するための基準として用いられるものであり，1 nT よりも高い精度が求められる。評価の結果，西日本におけるモデルの精度が不十分であることが示された。防災研究所が展開する地磁気観測点のなかでは，鳥取観測点の位置におけるモデル決定精度がもっとも低く，同観測点における地磁気観測が日本周辺の地域地磁気モデルの精度向上のために最重要であることが結論される。Accuracy of the regional geomagnetic field model based on geomagnetic observatories in Japan has been examined under some assumptions on the spatial distribution of the Earth's geomagnetic main field variation. The geomagnetic field model is used as a reference to distinguish small tectonomagnetic signals which are as small as 1 nT from the main field variation, so that the model should be more accurate than 1 nT. This criterion is satisfied in east Japan, whereas it is not satisfied in the vast part of west Japan. It is clarified that the model has the least accuracy at the place of the TOT site among all stations deployed by Disaster Prevention Research Institute (DPRI). This means that the TOT site has a great importance to determine more accurate reference field models

A New Development Of Scanning Hydrogen Imaging System And Its Application

ABSTRACTScanning type electron-stimulated desorption (ESD) spectroscopy to detect hydrogen on solid surfaces has been described. To analyze a two-dimensional distribution of hydrogen on solid surface, a pencil-type fine-focused electron gun, of which spot size is less than 300 nm at 800 eV, has been developed using a thermal field emitter. The lateral resolution of analysis is achieved less than 1 μm.Letters were drawn on a hydrogen-terminated Si(100) surface by irradiation of continuous electron beam to remove hydrogen from the surface, and by the following scanning ESD measurement, a clear letters were confirmed on this surface. Direct lithography by an electron beam on silicon surfaces has been realized.</jats:p