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111 results on '"Ogawa, Tsutomu"'

1. Measurement and subtraction of Schumann resonances at gravitational-wave interferometers

Author

Coughlin, Michael W., Cirone, Alessio, Meyers, Patrick, Atsuta, Sho, Boschi, Valerio, Chincarini, Andrea, Christensen, Nelson L., De Rosa, Rosario, Effler, Anamaria, Fiori, Irene, Golkowski, Mark, Guidry, Melissa, Harms, Jan, Hayama, Kazuhiro, Kataoka, Yuu, Kubisz, Jerzy, Kulak, Andrzej, Laxen, Michael, Matas, Andrew, Mlynarczyk, Janusz, Ogawa, Tsutomu, Paoletti, Federico, Salvador, Jacobo, Schofield, Robert, Somiya, Kentaro, and Thrane, Eric

Subjects
General Relativity and Quantum Cosmology
Abstract

Correlated magnetic noise from Schumann resonances threatens to contaminate the observation of a stochastic gravitational-wave background in interferometric detectors. In previous work, we reported on the first effort to eliminate global correlated noise from the Schumann resonances using Wiener filtering, demonstrating as much as a factor of two reduction in the coherence between magnetometers on different continents. In this work, we present results from dedicated magnetometer measurements at the Virgo and KAGRA sites, which are the first results for subtraction using data from gravitational-wave detector sites. We compare these measurements to a growing network of permanent magnetometer stations, including at the LIGO sites. We show how dedicated measurements can reduce coherence to a level consistent with uncorrelated noise. We also show the effect of mutual magnetometer attraction, arguing that magnetometers should be placed at least one meter from one another.

Published
2018
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3. Three‐Dimensional Electrical Resistivity Structure Beneath a Strain Concentration Area in the Back‐Arc Side of the Northeastern Japan Arc.

Author

Usui, Yoshiya, Uyeshima, Makoto, Hase, Hideaki, Ichihara, Hiroshi, Aizawa, Koki, Koyama, Takao, Sakanaka, Shin'ya, Ogawa, Tsutomu, Yamaya, Yusuke, Nishitani, Tadashi, Asamori, Koichi, Ogawa, Yasuo, Yoshimura, Ryokei, Takakura, Shinichi, Mishina, Masaaki, and Morita, Yuichi

Subjects
ELECTRICAL resistivity, GLOBAL Positioning System, GEOLOGICAL strains & stresses
Abstract

Intraplate earthquakes occur more frequently in the Japanese islands than in other regions. Large intraplate earthquakes in the island arc preferentially occur in strain concentration zones detected by geological and geodetic studies. Crustal heterogeneity plays a crucial role in generating large intraplate earthquakes and strain concentrations. Thus, we elucidated the crustal heterogeneities beneath a strain concentration area on the back‐arc side of the northeastern Japan Arc based on electrical resistivity, which is sensitive to weak zones in the crust. By deploying wideband magnetotelluric surveys, we revealed the three‐dimensional electrical resistivity structure in the crust, suggesting the coexistence of two different types of strain‐concentration mechanisms in the strain‐concentration area. The shallow conductive layers and lower‐crustal conductors appear to act as low‐elastic‐modulus and low‐viscosity areas, respectively, and are responsible for the strain concentration. We found shallow and lower‐crustal conductors in the strain concentration zone revealed by geological studies. Those conductive areas are considered to act as mechanically weak zones and cause stress loading on the brittle pars of pre‐existing faults, resulting in large intraplate earthquakes. The resultant earthquakes presumably contribute to strain accumulation on a geological timescale. In addition, a spatial correlation between the epicenters of large intraplate earthquakes and edges of lower‐crustal conductors implies the contribution of the fluids in the lower crust to the generation of large earthquakes. We also identified vertical conductors ranging from the lower crust to Quaternary volcanoes, which may indicate trans‐crustal magmatic systems under these volcanoes. Plain Language Summary: Intraplate earthquakes occur more frequently in the Japanese islands than in other regions worldwide. Large intraplate earthquakes in this region preferentially occur in high‐deformation zones, as detected by geological studies and global positioning system (GPS) measurements. Heterogeneous structure in the crust plays a crucial role in the generation of large intraplate earthquakes and high crustal deformations. Thus, we revealed the three‐dimensional crustal electrical resistivity structure beneath a strain‐concentration area in the northeastern Japan. The resistivity structure suggests the coexistence of two different mechanisms of high deformation. Shallow conductive layers and lower‐crustal conductors appear to act as low‐stiffness and low‐viscosity areas, respectively, leading to high crustal deformation. We found shallow and deep conductors in the high‐deformation zones revealed by geological studies. As both can act as weak zones, those conductors presumably play a key role in loading on faults, resulting in intraplate earthquakes. Because the epicenters of large intraplate earthquakes are positioned near the edges of lower‐crustal conductors, the fluids in those deep conductors possibly contribute to the generation of large earthquakes. We also revealed vertical conductors ranging from the deep crust to Quaternary volcanoes, which may indicate magma‐rich areas under these volcanoes. Key Points: The electrical resistivity structure suggests the coexistence of two strain‐concentration mechanisms in the strain‐concentration areaThe shallow conductive layers and lower‐crustal conductors act as low‐elastic‐modulus and low‐viscosity areas, respectivelyWeak zones in the crust, imaged as conductors, presumably cause stress loading on faults and contribute to large intraplate earthquakes [ABSTRACT FROM AUTHOR]

Published
2024
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6. Electrical Resistivity Structure Around the Atotsugawa Fault, Central Japan, Revealed by a New 2‐D Inversion Method Combining Wideband‐MT and Network‐MT Data Sets

Author

Usui, Yoshiya, primary, Uyeshima, Makoto, additional, Ogawa, Tsutomu, additional, Yoshimura, Ryokei, additional, Oshiman, Naoto, additional, Yamaguchi, Satoru, additional, Toh, Hiroaki, additional, Murakami, Hideki, additional, Aizawa, Koki, additional, Tanbo, Toshiya, additional, Ogawa, Yasuo, additional, Nishitani, Tadashi, additional, Sakanaka, Shin 'ya, additional, Mishina, Masaaki, additional, Satoh, Hideyuki, additional, Goto, Tada‐nori, additional, Kasaya, Takafumi, additional, Mogi, Toru, additional, Yamaya, Yusuke, additional, Shiozaki, Ichiro, additional, and Honkura, Yoshimori, additional

Published
2021
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7. Magnetotelluric observations around the focal region of the 2007 Noto Hanto Earthquake (Mj 6.9), Central Japan

Author

Yoshimura, Ryokei, Oshiman, Naoto, Uyeshima, Makoto, Ogawa, Yasuo, Mishina, Masaaki, Toh, Hiroaki, Sakanaka, Shin’ya, Ichihara, Hiroshi, Shiozaki, Ichiro, Ogawa, Tsutomu, Miura, Tsutomu, Koyama, Shigeru, Fujita, Yasuyoshi, Nishimura, Kazuhiro, Takagi, Yu, Imai, Mikihiro, Honda, Ryo, Yabe, Sei, Nagaoka, Shintaro, Tada, Mitsuhiro, and Mogi, Toru

Published
2008
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12. Measurement and subtraction of Schumann resonances at gravitational-wave interferometers

Author

Coughlin, Michael W., primary, Cirone, Alessio, additional, Meyers, Patrick, additional, Atsuta, Sho, additional, Boschi, Valerio, additional, Chincarini, Andrea, additional, Christensen, Nelson L., additional, De Rosa, Rosario, additional, Effler, Anamaria, additional, Fiori, Irene, additional, Gołkowski, Mark, additional, Guidry, Melissa, additional, Harms, Jan, additional, Hayama, Kazuhiro, additional, Kataoka, Yuu, additional, Kubisz, Jerzy, additional, Kulak, Andrzej, additional, Laxen, Michael, additional, Matas, Andrew, additional, Mlynarczyk, Janusz, additional, Ogawa, Tsutomu, additional, Paoletti, Federico, additional, Salvador, Jacobo, additional, Schofield, Robert, additional, Somiya, Kentaro, additional, and Thrane, Eric, additional

Published
2018
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14. <実践報告> 学士課程教育の質保証のための組織的カリキュラム改善の取組 : 「教育改善FD研修会」を通したカリキュラム改善の試み

Author

OGAWA, Tsutomu

Subjects
カリキュラム・フローチャート, undergraduate education, curriculum improvement, curriculum map, グラデュエーション・ポリシー, ComputingMilieux_COMPUTERSANDEDUCATION, カリキュラム・マップ, カリキュラム改善, curriculum flowchart, 学士課程教育, graduation policy
Abstract

This paper introduces a method to promote improvement of the curriculum systematically and continuously, as an example of Yamaguchi University's efforts to guarantee the quality of undergraduate education. It is necessary to restructure the curriculum including liberal arts education with specialized courses for a consistent undergraduate education. Yamaguchi University revised its Graduation Policy and Curriculum Policy that had been made six years ago to specify the system and the correspondence between subjects. Moreover, the curriculum flow chart and results evaluation system were developed. As a result of these approaches, the attitude of teachers towards a systematic match of educational improvement has changed. Moreover, the teachers came to be more interested in the curriculum.

Published
2010

16. Elastic calculation of the thermal strains and stresses of the multilayered plate.

Author

Yamada-Kaneta, Hiroshi, Ogawa, Tsutomu, and Wada, Kunihiko

Subjects
*MULTILAYERED thin films, *ELECTRIC double layer
Abstract

Presents a study that carried out an elastic calculation on the thermal deformation strains and stresses of a multilayered plate (MLP). Composition of the MLP; Minimization of the total Helmholtz-free energy of the MLP; Determination of the radius of curvature of the warpage by a closed form solution.

Published
1987
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17. PRELIMINAR Y RESULTS OF WIDE -BAND MAGNETOTELLURIC SOUNDING IN FUJI VOLCANO, JAPAN

Author

AIZAWA, Koki, YOSHIMURA, Ryokei, YAMAZAKI, Kenichi, KANDA, Wataru, OSHIMAN, Naoto, HASHIMOTO, Takeshi, HURST, Tony., HURST, Tony, SAKANAKA, Shin'ya, FURUKAWA, Yuya, OGAWA, Yasuo, TANK, S.Bulent., TANK, Bulent, UESHIMA, Makoto, OGAWA, Tsutomu, KOYAMA, Shigeru, KAGIYAMA, Tsuneomi, SHIOZAKI, Ichiro, UTO, Tomofumi, YOSHIMURA, Mitsuhiro, and YOSHIMOTO, Kazunori

Subjects
resistivity, 広帯域MT法, magma chamber, マグマ溜り, wide-band magnetotelluric method, 比抵抗, 異方性, Fuji volcano, 富士山
Abstract

2002年9月, 富士山周辺で広帯域 MT観測を行なった。その結果, 富士山直下深部に低抵抗体が存在することが強く示唆された。現在のところ, データの量, 質とも不十分なため, その低抵抗体の深さや広がりは不明である。しかし予備的な解析によると, 低抵抗体の深さの上面は, 深さ 15キロの深部低周波地震の発生領域と一致するために, マグマ溜りを表している可能性がある。また得られたデータには顕著な異方性が見られる。, Wide-band MT soundings in Fuji volcano were carried out September, 2002. Collected data suggestsexistence of low resistivity anomaly deeper part beneath Fuji volcano. A two dimensional inversioncode was applied to data. Preliminary result show that low resitivity body locates at a depth about15-20km which consists with hypo central region of deep low frequency earthquake. This lowresistivity body may be a magma chamber.

Published
2003

19. Effect of verapamil on cardiac protein kinase C activity in diabetic rats

Author

Tanaka Yasushi, Ogawa Tsutomu, Abe Nanami, Ikebuchi Motoyoshi, Shigeta Yukio, Asahina Takayuki, Takagi Yoshihumi, and Kashiwagi Atsunori

Subjects
Blood Glucose, Male, medicine.medical_specialty, Heart Ventricles, PKC activity, Diabetes Mellitus, Experimental, Basal (phylogenetics), Internal medicine, Diabetes mellitus, medicine, Animals, Insulin, Protein Kinase C, Protein kinase C, Pharmacology, chemistry.chemical_classification, Membranes, business.industry, Myocardium, Body Weight, Rats, Inbred Strains, Organ Size, Streptozotocin, medicine.disease, Rats, Cytosol, Endocrinology, Enzyme, Verapamil, chemistry, cardiovascular system, business, medicine.drug
Abstract

We examined the effect of verapamil treatment on cardiac protein kinase C (PKC) activity in streptozocin-induced diabetic rats. Basal cardiac PKC activity in diabetes increased in both cytosolic (by 94%, P less than 0.01) and membrane (by 41%, P less than 0.05) fractions as compared with that in controls. Subcutaneous administration of 8 mg/kg verapamil twice a day for 8 weeks induced a significant decrease in both cytosolic (by 59%, P less than 0.01) and membrane (by 50%, P less than 0.01) PKC activity in diabetes as compared with the activity in the non-treated diabetic groups. In contrast, cardiac cytosolic PKC activity in control rats was significantly (P less than 0.01) decreased by 41% as compared with that of the non-treated control group without there being any change in membrane PKC activity. Our data demonstrate that verapamil treatment may ameliorate the abnormal activation of cardiac PKC in diabetes.

Published
1991

20. BF+2 implantation in predamaged Si with Ge+ or Si+ at doses lower than amorphization

Author

Mori Haruhisa, Masataka Kase, Ogawa Tsutomu, Yoshio Kikuchi, and Mami Kimura

Subjects
Nuclear and High Energy Physics, Crystallography, Materials science, Transmission electron microscopy, Analytical chemistry, Instrumentation, Diode
Abstract

The B diffusion dependence on the preimplantation energy and dose of Ge+ or Si+ was studied. Boron-enhanced diffusion is reduced by moderate lattice disorder below amorphization. The residual damage was examined by cross-sectional transmission electron microscopy, which indicated that amorphization causes the formation of extended defects. A gate-controlled diode was designed and fabricated for the evaluation of preimplanted layer. The dependence of the leakage current on the preimplantation dose indicates that no serious defects are caused by Ge+ implantation at 40 keV and 5 × 1013 cm−2 or Si+ at 40 keV and 2 × 1014 cm−2.

Published
1991

30. Eliminating channeling tail by lower dose preimplantation

Author

Mori Haruhisa, Ogawa Tsutomu, Mami Kimura, and Masataka Kase

Subjects
inorganic chemicals, Secondary ion mass spectrometry, Ion implantation, Physics and Astronomy (miscellaneous), chemistry, Silicon, Annealing (metallurgy), Semiconductor materials, Ion channeling, Analytical chemistry, chemistry.chemical_element, Boron, Spectroscopy
Abstract

We optimized Ge+ and Si+ preimplantation to eliminate the channeling tail and prevent the rapid diffusion of boron and the formation of serious defects. We examined the dependence of the microchanneling of BF+2 implantation or the lattice disorder of preimplanted silicon using secondary‐ion mass spectroscopy and grazing exit Rutherford backscattering spectroscopy. The optimum doses are about 25% those for full amorphization, i.e., preamorphization. The channeling tail is eliminated by disordered layers containing about 60% silicon atoms on irregular sites.

Published
1990

47. Magnetotelluric observations around the focal region of the 2007 Noto Hanto Earthquake (Mj6.9), Central Japan

Author

Yoshimura, Ryokei, Oshiman, Naoto, Uyeshima, Makoto, Ogawa, Yasuo, Mishina, Masaaki, Toh, Hiroaki, Sakanaka, Shin’ya, Ichihara, Hiroshi, Shiozaki, Ichiro, Ogawa, Tsutomu, Miura, Tsutomu, Koyama, Shigeru, Fujita, Yasuyoshi, Nishimura, Kazuhiro, Takagi, Yu, Imai, Mikihiro, Honda, Ryo, Yabe, Sei, Nagaoka, Shintaro, Tada, Mitsuhiro, and Mogi, Toru

Abstract

On 25 March 2007, a damaging earthquake (Mj6.9) occurred near the west coast of the Noto Peninsula, Central Japan. A wideband magnetotelluric (MT) survey was carried out in the onshore area of the source region immediately after the mainshock, with the aim of imaging the heterogeneity of the crustal resistivity structure. The final observation network had consisted of 26 sites. As a preparatory step for imaging three-dimensional features of the resistivity around the focal region, we constructed two-dimensional resistivity models along five profiles using only the TM mode responses, in order to reduce three-dimensional effects. Four profiles are perpendicular to the fault strike, and a fifth profile is parallel to the strike through the mainshock epicenter. Significant characteristics of the resistivity models are: (1) beneath the mainshock hypocenter, there is a conductive body which spreads to the eastern edge of the active aftershock region; (2) a resistive zone is located in the gap of the aftershock distribution between the mainshock hypocenter and the largest eastern aftershock; (3) one of the largest aftershock occurred at the boundary of the resistive zone described above. These results suggest that the deep conductors represent fluid-filled zones and that the lateral heterogeneity could have controlled the slip distribution on the fault plane.

Published
2008
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