M Tanaka

National Institute for Fusion Science, Tokitsu-chō, Gifu, Japan

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Publications (811)1593.13 Total impact

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    ABSTRACT: This review presents the recent progress in computational materials design, experimental realization, and control methods of spinodal nanodecomposition under three- and two-dimensional crystal-growth conditions in spintronic materials, such as magnetically doped semiconductors. The computational description of nanodecomposition, performed by combining first-principles calculations with kinetic Monte Carlo simulations, is discussed together with extensive electron microscopy, synchrotron radiation, scanning probe, and ion beam methods that have been employed to visualize binodal and spinodal nanodecomposition (chemical phase separation) as well as nanoprecipitation (crystallographic phase separation) in a range of semiconductor compounds with a concentration of transition metal (TM) impurities beyond the solubility limit. The role of growth conditions, codoping by shallow impurities, kinetic barriers, and surface reactions in controlling the aggregation of magnetic cations is highlighted. According to theoretical simulations and experimental results the TM-rich regions appear in the form of either nanodots (the dairiseki phase) or nanocolumns (the konbu phase) buried in the host semiconductor. Particular attention is paid to Mn-doped group III arsenides and antimonides, TM-doped group III nitrides, Mn- and Fe-doped Ge, and Cr-doped group II chalcogenides, in which ferromagnetic features persisting up to above room temperature correlate with the presence of nanodecomposition and account for the application-relevant magneto-optical and magnetotransport properties of these compounds. Finally, it is pointed out that spinodal nanodecomposition can be viewed as a new class of bottom-up approach to nanofabrication.
    Full-text · Article · Dec 2015 · Review of Modern Physics
  • N Akata · H Kakiuchi · T Tamari · M Tanaka · T Kawano · H Miyake · T Uda · K Nishimura
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    ABSTRACT: Free water tritium (FWT) and organically bound tritium (OBT) concentrations in pine needles have been investigated to understand the regional background tritium concentration in Toki City. Samples were regularly collected from pine trees on the National Institute for Fusion Science campus (1998-2012) and the nearby Shiomi Park (SP; 2002-12). FWT and OBT concentrations of the former samples ranged from 0.33 to 0.92 and 0.41 to 1.10 Bq l(-1), respectively, while those of the latter samples ranged from 0.32 to 0.86 and 0.33 to 0.79 Bq l(-1), respectively. Results of both sampling sites were almost the same, and they have been gradually decreased year by year. Concentration level of tritium for Toki City was close to the average background level in Japan. The OBT/FWT ratios were almost 1.0. The apparent half-life of FWT in this period was estimated as almost 10 y, and that of OBT was estimated as almost 12 y; these values were almost the same as the physical half-life. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    No preview · Article · May 2015 · Radiation Protection Dosimetry
  • M Tanaka · T Uda
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    ABSTRACT: Atmospheric tritium concentrations of HTO, HT and CH3T have been measured at Toki, Japan, for the environmental impact assessment of tritium for a fusion test facility. According to the data from 2004 to 2012, the concentrations of HT and HTO in water vapour tend to increase in spring. The seasonal variation in HT concentration at Toki was compared with the H2 concentration between 1990 and 2005 at Tae-ahn Peninsula, Republic of Korea, which is at approximately the same latitude as Toki. The monthly average of HT-specific activity varied from 1.24 × 10(5) to 1.76 × 10(5) TU. The peak of the monthly average H2 concentration did not match that of HT. This indicates that the mechanism of the production or the source of HT might be different from the production mechanism of H2. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
    No preview · Article · May 2015 · Radiation Protection Dosimetry
  • R. Nakane · S. Sugahara · M. Tanaka
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    ABSTRACT: We systematically investigate the structural and magnetic properties of ferromagnetic Fe1− x Si x (0.18 ≤ x ≤ 0.33) films formed by rapid thermal annealing (RTA) on silicon-on-insulator (SOI) substrates. During RTA of an Fe film deposited on a SOI substrate (consisting of a top Si layer, a buried oxide SiO2 layer, and a Si substrate), an Fe1− x Si x film is synthesized by the thermal reaction of the deposited Fe film and the top Si layer, but the reaction is limited by the buried oxide layer in the SOI substrate, thus the Si concentration x in Fe1− x Si x can be controlled by both the initial thicknesses of the Fe film and the top Si layer. A variety of characteristics show that single-phase Fe1− x Si x (x = 0.18, 0.22, and 0.25) films with D03 + B2 structure are successfully obtained by choosing the optimum annealing temperature and time. Furthermore, the ordering fraction of D03 and B2 structures in these films is found to be more than 87%, indicating that the crystalline quality of these films is comparable to that of bulk Fe1− x Si x materials reported so far. On the other hand, it is found that the Fe1− x Si x (x = 0.33) film has Fe3Si and FeSi phases as in the case of bulk Fe1− x Si x with x = 0.33. The film production technique and the quality of the ferromagnetic Fe1− x Si x presented in this study are very attractive and useful for silicon-based spintronic devices which are compatible with the complementary metal-oxide-semiconductor technology.
    No preview · Article · Apr 2015 · Journal of Applied Physics
  • M. Matsuyama · M. Kondo · N. Noda · M. Tanaka · K. Nishimura
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    ABSTRACT: Desorption kinetics of hydrogen isotopes implanted into type 316L stainless steel by glow discharge have been studied by the experiment and numerical calculation. The temperature of a maximum desorption rate depended on glow discharge time and heating rate. Desorption spectra observed under various experimental conditions were successfully reproduced by numerical calculation which is based on a diffusion-limited process. It is suggested, therefore, that desorption rate of a hydrogen isotope implanted into the stainless steel is limited by a diffusion process of hydrogen isotope atoms in bulk. Furthermore, small isotope effects were observed for the diffusion process of hydrogen isotope atoms.
    No preview · Article · Apr 2015 · Fusion Science and Technology
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    ABSTRACT: Simultaneous pancreas-kidney transplantation (SPK) is a definitive treatment for type 1 diabetics with end-stage renal disease (ESRD). Because of the shortage of deceased donors in Japan, the mortality rate during the waiting period is high. We evaluated mortality risk in patients with type 1 diabetes waiting for SPK, and the benefit of living-donor kidney transplantation (LDK) preceding pancreas transplantation, which may reduce mortality in patients awaiting SPK. This retrospective study included 71 patients with type 1 diabetes. Twenty-six patients underwent SPK, 15 underwent LDK, and 30 were waiting for SPK. Their cumulative patient and graft survival rates were retrospectively evaluated. Risk factors contributing to mortality in patients with type 1 diabetes awaiting SPK were evaluated with the use of a Cox proportional hazards model. The 5-year cumulative patient survival rates in the SPK and LDK groups were 100% and 93.3%, respectively (P = .19), and 5-year kidney graft survival rates were 95.7% and 100% (P = .46), respectively. The cumulative survival rate in patients awaiting SPK was 77.7% at 5 years after registration. Duration of dialysis was the only factor significantly associated with patient and graft survivals according to both univariate and multivariate analyses. Patient and graft survival rates were similar in the SPK and LDK groups, but the survival rate of patients awaiting SPK decreased over time. Duration of dialysis was an independent risk factor for patient and graft survival. LDK preceding pancreas transplantation may be an effective therapeutic option for patients with type 1 diabetes and ESRD. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Apr 2015 · Transplantation Proceedings
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    ABSTRACT: Renal transplantation has been established as a treatment for end-stage renal disease (ESRD) due to diabetic nephropathy. However, few studies have focused on the outcome after renal transplantation in patients with ESRD and type 2 diabetic nephropathy. To investigate the effect of renal transplantation on ESRD with type 2 diabetic nephropathy, we retrospectively analyzed patients who received renal transplantation at our facility. This study aimed to compare the outcome of renal transplantation for type 2 diabetic nephropathy with that for nondiabetic nephropathy. We studied 290 adult patients, including 65 with type 2 diabetic nephropathy (DM group) and 225 with nondiabetic nephropathy (NDM group), who underwent living-donor renal transplantation at our facility from February 2008 to March 2013. We compared the 2 groups retrospectively. In the DM and NDM groups, the 5-year patient survival rates were 96.6% and 98.7%, and the 5-year graft survival rates were 96.8% and 98.0%, respectively, with no significant differences between the groups. There were no significant differences in the rates of surgical complications, rejection, and infection. The cumulative incidence of postoperative cardiovascular events was higher in the DM group than in the NDM group (8.5% vs 0.49% at 5 years; P = .002). Patient and graft survival rates after renal transplantation for type 2 diabetic nephropathy are not inferior to those for recipients without diabetic nephropathy. Considering the poor prognosis of patients with diabetic nephropathy on dialysis, renal transplantation can provide significant benefits for these patients. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Mar 2015 · Transplantation Proceedings
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    ABSTRACT: A 35-year-old woman presented at another hospital with right flank pain and high fever. She had undergone reconstruction of the right ureter using ileal segment due to primary megaureter 29 years earlier, and after that she underwent left nephrectomy due to the left pyonephrosis. This time, she suffered from right pyonephrosis. Nephrostomy was carried out and she had treatment with antibiotics. The patient was then admitted to our hospital and antibiotic medication was continued. Her symptoms did not improve. Therefore, we performed resection of the right kidney and ileal segment. The pathological diagnosis was adenocarcinoma in the renal pelvis and ileal segment. She died of the cancer 13 months after surgery.
    No preview · Article · Mar 2015 · Nishinihon Journal of Urology
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    ABSTRACT: Air exerts a negative effect on radiation detection using a gas counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting gas. This reduces radiation counts. The present study examined the influence of air on energy and rise-time spectra measurements using a proportional gas counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting gas inside the gas counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting gas to determine the effect of air on energy and rise-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional gas counter.
    No preview · Article · Mar 2015 · Fusion Science and Technology
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    ABSTRACT: We herein present a novel technique for laparoscopic en bloc excision involving anteriorly extended intersphincteric resection with partial resection of the posterior lobe of the prostate for large rectal gastrointestinal stromal tumors (GISTs). The sequence of neoadjuvant imatinib therapy and this less invasive surgery for marginally resectable rectal GISTs has the potential to obviate the need for urinary reconstruction and permanent stomas without jeopardizing the tumor margin status.
    No preview · Article · Dec 2014 · Techniques in Coloproctology
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    ABSTRACT: This review presents the recent progress in computational materials design, experimental realization, and control methods of spinodal nanodecomposition under three- and two-dimensional crystal-growth conditions in spintronic materials, such as magnetically doped semiconductors. The computational description of nanodecomposition, performed by combining first-principles calculations with kinetic Monte Carlo simulations, is discussed together with extensive electron microscopy, synchrotron radiation, scanning probe, and ion beam methods that have been employed to visualize binodal and spinodal nanodecomposition (chemical phase separation) as well as nanoprecipitation (crystallographic phase separation) in a range of semiconductor compounds with a concentration of transition metal (TM) impurities beyond the solubility limit. The role of growth conditions, co-doping by shallow impurities, kinetic barriers, and surface reactions in controlling the aggregation of magnetic cations is highlighted. According to theoretical simulations and experimental results the TM-rich regions appear either in the form of nanodots (the {\em dairiseki} phase) or nanocolumns (the {\em konbu} phase) buried in the host semiconductor. Particular attention is paid to Mn-doped group III arsenides and antimonides, TM-doped group III nitrides, Mn- and Fe-doped Ge, and Cr-doped group II chalcogenides, in which ferromagnetic features persisting up to above room temperature correlate with the presence of nanodecomposition and account for the application-relevant magneto-optical and magnetotransport properties of these compounds. Finally, it is pointed out that spinodal nanodecomposition can be viewed as a new class of bottom-up approach to nanofabrication.
    Full-text · Article · Dec 2014
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    ABSTRACT: The paper describes a time- and angle-resolved photoemission apparatus consisting of a hemispherical analyzer and a pulsed laser source. We demonstrate 1.48-eV pump and 5.92-eV probe measurements at the 10.5-meV and 240-fs resolutions by use of fairly monochromatic 170-fs pulses delivered from a regeneratively amplified Ti:sapphire laser system operating typically at 250 kHz. The apparatus is capable to resolve the optically filled superconducting peak in the unoccupied states of a cuprate superconductor, Bi2Sr2CaCu2O8 + δ. A dataset recorded on Bi(111) surface is also presented. Technical descriptions include the followings: A simple procedure to fine-tune the spatio-temporal overlap of the pump-and-probe beams and their diameters; achieving a long-term stability of the system that enables a normalization-free dataset acquisition; changing the repetition rate by utilizing acoustic optical modulator and frequency-division circuit.
    No preview · Article · Nov 2014 · Review of Scientific Instruments

  • No preview · Article · Nov 2014 · Pancreas

  • No preview · Article · Nov 2014 · Pancreas

  • No preview · Article · Nov 2014 · Pancreas
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    ABSTRACT: We demonstrate monolithic integration of pseudo-spin-MOSFETs (PS-MOSFETs) using vendor-made MOSFETs fabricated in a low-cost multi-project wafer (MPW) product and lab-made magnetic tunnel junctions (MTJs) formed on the topmost passivation film of the MPW chip. The tunneling magnetoresistance (TMR) ratio of the fabricated MTJs strongly depends on the surface roughness of the passivation film. Nevertheless, after the chip surface was atomically flattened by SiO2 deposition on it and successive chemical–mechanical polish (CMP) process for the surface, the fabricated MTJs on the chip exhibits a sufficiently large TMR ratio (>140%) adaptable to the PS-MOSFET application. The implemented PS-MOSFETs show clear modulation of the output current controlled by the magnetization configuration of the MTJs, and a maximum magnetocurrent ratio of 90% is achieved. These magnetocurrent behaviour is quantitatively consistent with those predicted by HSPICE simulations. The developed integration technique using a MPW CMOS chip would also be applied to monolithic integration of CMOS devices/circuits and other various functional devices/materials, which would open the door for exploring CMOS-based new functional hybrid circuits.
    No preview · Article · Jul 2014 · Solid-State Electronics
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    ABSTRACT: The electronic and magnetic properties of Fe atoms in the ferromagnetic semiconductor (In,Fe)As codoped with Be have been studied by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at the Fe $L_{2,3}$ edge. The XAS and XMCD spectra showed simple spectral line shapes similar to Fe metal, but the ratio of the orbital and spin magnetic moments ($M_\mathrm{orb}$/$M_\mathrm{spin}$) estimated using the XMCD sum rules was significantly larger than that of Fe metal, indicating a significant orbital moment of Fe $3d$ electrons in (In,Fe)As:Be. The positive value of $M_\mathrm{orb}$/$M_\mathrm{spin}$ implies that the Fe $3d$ shell is more than half-filled, which arises from the hybridization of the Fe$^{3+}$ ($d^5$) state with the charge-transfer $d^6\underline{L}$ states, where $\underline{L}$ is a ligand hole in the host valence band. The XMCD intensity as a function of magnetic field indicated hysteretic behavior of the superparamagnetic-like component due to discrete ferromagnetic domains.
    Full-text · Article · May 2014 · Applied Physics Letters
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    ABSTRACT: The electronic structure of doped Mn in (Ga,Mn)As is studied by resonant inelastic X-ray scattering (RIXS). From configuration-interaction cluster-model calculations, the line shapes of the Mn $L_3$ RIXS spectra can be explained by $d$-$d$ excitations from the Mn$^{3+}$ ground state, dominated by charge-transferred states, rather than a Mn$^{2+}$ ground state. Unlike archetypical $d$-$d$ excitation, the peak widths are broader than the experimental energy resolution. We attribute the broadening to a finite lifetime of the $d$-$d$ excitations, which decay rapidly to electron-hole pairs in the host valence and conduction bands through hybridization of the Mn $3d$ orbital with the ligand band.
    Full-text · Article · Mar 2014 · Physical Review Letters
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    ABSTRACT: Polyomavirus BK nephropathy (BKVN) is an important infectious complication in kidney transplant patients. Regular screening using polymerase chain reaction for BK virus DNA in plasma and urinary cytology is effective for early diagnosis of BKVN. However, methods of follow-up and therapeutic targets are not well described. Ten patients with BKVN who received biweekly urinary cytology and repeat biopsies after diagnosis were retrospectively studied. Histological remission of BKVN was determined when biopsy revealed negative SV40 large T-antigen (TAg) staining. Results of urinary cytology and repeat biopsy findings were compared. Urinary decoy cells disappeared in 8 of 10 patients 55 ± 25 (range 13-79) days after index biopsies. In those cases, allograft function was preserved and the final serum creatinine level was 2.14 ± 1.19 (0.80-4.55) mg/dL after 962 ± 393 (325-1563) days of follow-up. Two cases with persistent urinary decoy cells shedding lost their graft 195 and 362 days later. Amongst 29 repeat biopsies, there were 13 TAg-positive and 16 negative biopsies. In 12 of 13 TAg-positive biopsies (92%), urinary decoy cells were still positive, whereas at the same time in 15 TAg-negative biopsies, decoy cells had already disappeared (94%). Cytology testing is advantageous because of its cost effectiveness. Clearance of decoy cells from urine was closely related to histological remission of BKVN, and may possibly be a therapeutic target in BKVN.
    No preview · Article · Mar 2014 · Transplantation Proceedings
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    ABSTRACT: Background Once-daily extended-release tacrolimus (Tac-QD) has been shown to have equivalent efficacy and safety to the twice-daily formulation (Tac-BID) in kidney transplant patients. However, detailed comparison of allograft pathology found on a protocol biopsy (PB) in Tac-QD– versus Tac-BID–based regimens has not been described. Methods We retrospectively investigated 119 de novo living donor kidney transplant patients treated with Tac-QD (n = 90) or Tac-BID (n = 29) and their 3- and 12-month PB results. Other immunosuppressive drugs administered included basiliximab, mycophenolate mofetil, and methylprednisolone. We evaluated daily doses and trough levels of Tac and serum creatinine levels, and compared pathologic findings. Results Daily doses were higher in the Tac-QD group, but trough levels and serum creatinine levels were comparable. On 3- and 12-month PB, the frequency of subclinical rejection was similar between the groups, whereas interstitial fibrosis and tubular atrophy (IF/TA) were less common in the Tac-QD group at 12 months (42.2% vs 20.6%, P = .04). Univariate and multivariate logistic regression analyses revealed that allograft rejection (borderline changes or higher) was associated with IF/TA (odds ratio 4.09, 95% confidence interval 1.76–10.10, P = .001). The Tac-QD–based regimen showed a trend toward the absence of IF/TA but it did not reach statistical significance. Tubular vacuolization and arteriolar hyaline changes were also comparable in the two groups. Conclusions We found a trend toward milder IF/TA, but no significant differences in kidney allograft pathology in patients who were administered Tac-QD– versus Tac-BID–based regimens at 12 months. The effects of Tac-QD on chronic allograft injury must be studied by longer observation.
    No preview · Article · Mar 2014 · Transplantation Proceedings

Publication Stats

13k Citations
1,593.13 Total Impact Points

Institutions

  • 1992-2015
    • National Institute for Fusion Science
      • Department of Helical Plasma Research
      Tokitsu-chō, Gifu, Japan
    • Konan University
      • Department of Physics
      Kōbe, Hyōgo, Japan
  • 1986-2015
    • The University of Tokyo
      • • Institute for Solid State Physics
      • • Department of Electrical and Electronics Engineering
      • • Faculty & Graduate School of Medicine
      • • Institute of Industrial Science
      白山, Tōkyō, Japan
  • 1973-2015
    • Kyushu University
      • • Department of Surgery and Oncology
      • • Division of Surgery
      • • Graduate School of Medical Sciences
      • • Medical Hospital
      • • Division of Internal Medicine
      • • Department of Urology
      Hukuoka, Fukuoka, Japan
  • 2008-2013
    • National Institutes Of Natural Sciences
      Edo, Tōkyō, Japan
  • 2006-2013
    • Japan Atomic Energy Agency
      • • Quantum Beam Science Directorate
      • • Advanced Photon Research Center
      Muramatsu, Niigata, Japan
    • Japan Synchrotron Radiation Research Institute (JASRI)
      Tatsuno, Hyōgo, Japan
  • 1999-2012
    • Tokai University
      • • Department of Emergency and Critical Care Medicine
      • • School of Medicine
      Hiratuka, Kanagawa, Japan
    • Nagoya University
      • Graduate School of Engineering
      Nagoya, Aichi, Japan
  • 2001-2010
    • Kobe Tokiwa University
      Kōbe, Hyōgo, Japan
  • 2009
    • Tohoku University
      • Institute of Multidisciplinary Research for Advanced Materials (IMRAM)
      Sendai, Kagoshima, Japan
  • 1994-2009
    • Nara Medical University
      • Department of Urology
      Kashihara, Nara, Japan
    • Dallas Zoo
      Dallas, Texas, United States
    • The University of Tokushima
      Tokusima, Tokushima, Japan
  • 2007-2008
    • Kobe College
      Kōbe, Hyōgo, Japan
    • Center of Molecular Immunology
      La Habana, La Habana, Cuba
  • 2006-2008
    • Hiroshima University
      Hirosima, Hiroshima, Japan
  • 2005-2008
    • Hitachi, Ltd.
      Edo, Tōkyō, Japan
    • National Institute of Advanced Industrial Science and Technology
      • Electronics and Photonics Research Institute
      Tsukuba, Ibaraki, Japan
    • Osaka City University
      Ōsaka, Ōsaka, Japan
    • Waseda University
      • Graduate School of Science and Engineering
      Edo, Tōkyō, Japan
  • 1996-2007
    • Kyoto University
      • • Division of Applied Biosciences
      • • Advanced Education and Research Center of Energy Science
      • • Department of Physics II
      Kioto, Kyōto, Japan
  • 1993-2001
    • Tokyo Medical and Dental University
      • • Department of Pulmonary Medicine
      • • Department of Biochemical Genetics
      • • Department of Internal Medicine
      Edo, Tokyo, Japan
  • 2000
    • University of Lausanne
      • Institute of Pathology
      Lausanne, Vaud, Switzerland
  • 1992-1999
    • National Institute for Basic Biology
      Okazaki, Aichi, Japan
  • 1998
    • Osaka University
      • Research Center for Nuclear Physics
      Suika, Ōsaka, Japan
    • St. Luke's International Hospital
      Edo, Tōkyō, Japan
  • 1995
    • National Cancer Institute (USA)
      베서스다, Maryland, United States
  • 1983-1995
    • Niigata University
      • Division of Neuropathology
      Niahi-niigata, Niigata, Japan
  • 1990-1992
    • Shinshu University
      • Department of Medicine
      Shonai, Nagano, Japan
  • 1991
    • Kyoto Prefectural University of Medicine
      • Department of Anesthesiology
      Kioto, Kyōto, Japan
  • 1986-1991
    • Tokyo Metropolitan Hiroo Hospital
      • Department of Pathology
      Tōkyō, Japan