178 results on '"Ryo Kikuchi"'
Search Results
52. Neutral Atom Density at Current Zero in Interruption of Intense-Mode Vacuum Arc
- Author
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Haruki Ejiri, Ryo Kikuchi, Yoshimitsu Niwa, Junichi Kondo, Yuichi Hirano, Akira Daibo, Yuki Inada, Kunihiko Hidaka, Yo Sasaki, Naoki Asari, and Akiko Kumada
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Arc (geometry) ,Electric arc ,Materials science ,Energetic neutral atom ,Transient recovery voltage ,Electrode ,Vacuum arc ,Atomic physics ,Current (fluid) ,Anode - Abstract
Neutral atom density in intense-mode vacuum arc just before current zero as a determinant factor for the current interruption success or failure was measured by Shack-Hartmann laser wavefront sensors. The electrode selected in this study was Cu50Cr50 wt.% and the contact diameter of 6 mm. 50-Hz sinusoidal current of 2 kA rms or 4 kA rms was applied to the electrode gap and current of 1 kA p was superimposed just before current-zero point, and transient recovery voltage with height of 25 kV was applied to the electrode gap at current zero. The neutral atom density in the 4.5-mm gap was about 2.5–4.0 × 1019 m-2 for the current of 2 kA rsm , and 5.0–8.0 × 1019 m-2 for the current of 4 kA rms , respectively. In the intense-mode vacuum arcs, the anode surface was heated during high-current arc period, and the critical neutral atom density for TRV of 25 kV was suggested to be around 5.0–8.0 × 1019 m-2.
- Published
- 2021
53. Molecular Dynamics Analysis of the Acceleration of Intergranular Cracking of Ni-Base Superalloy Caused by Accumulation of Vacancies and Dislocations Around Grain Boundaries
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Ken Suzuki, Ryo Kikuchi, and Shujiro Suzuki
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Superalloy ,chemistry.chemical_classification ,Molecular dynamics ,Cracking ,Acceleration ,Materials science ,Creep ,Base (chemistry) ,chemistry ,Metallurgy ,Grain boundary ,Intergranular corrosion - Abstract
Ni-based superalloys with excellent high temperature strength have been used in advanced thermal power plants. It was found that grain boundary cracking is caused in the alloy under creep-fatigue loading due to the degradation of the crystallinity of grain boundaries and the grain boundary cracking degrades the lifetime of the alloy drastically. In order to clarify the mechanism of intergranular cracking, in this research, static and dynamic strains were applied to a bicrystal structure of the alloy perpendicularly to the grain boundary using molecular dynamics analysis. In addition, the effect of the accumulation of vacancies in the area with high-density of dislocations on the strength of the bicrystal structure was analysed. It was found that the fracture mode of the bicrystal structure changed from ductile transgranular fracture to brittle intergranular one as strong functions of the combination of Schmid factor of the two grains and the density of defects around the grain boundary. The local heavy plastic deformation occurred around the grain boundary with large difference in Schmid factor between nearby grains and the diffusion of the newly grown dislocations and vacancies was suppressed by the large strain field due to the large mismatch of the crystallographic orientation between the grains. The accumulation of vacancies accelerated the local plastic deformation around the grain boundary. Therefore, the mechanism of the acceleration of intergranular cracking under creep-fatigue loading was successfully clarified by MD analysis.
- Published
- 2021
54. Initiation Process of Vacuum Breakdown Between Cu and CuCr Electrodes
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Hiroyuki Nagai, Shigeyasu Matsuoka, Ryo Kikuchi, Kunihiko Hidaka, Tetsu Shioiri, Yuki Inada, and Akiko Kumada
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Nuclear and High Energy Physics ,Electron density ,Materials science ,Plasma ,Electron ,Condensed Matter Physics ,01 natural sciences ,Cathode ,010305 fluids & plasmas ,Anode ,law.invention ,law ,0103 physical sciences ,Electrode ,Plasma diagnostics ,Composite material ,Flare - Abstract
During the breakdown process in a vacuum, plasma flares initiated on cathode and anode surfaces expand and collide. The plasma flare behavior is quite important for the optimization of the spark conditioning of vacuum interrupters. Here, copper–chromium alloys are widely used as an electrode material in the large-capacity vacuum circuit breakers. In this article, high-speed spectroscopy is conducted on the plasma flares generated between a CuCr (Cr-35wt%) anode and a Cu cathode in order to elucidate the plasma temperature, particle composition, and electron density. The experimental results show that the anode flare has 1024–1025m−3 electron, and its temperature is approximately 13 000 K. The composition ratio of vapor atoms consisting the anode flare is Cu:Cr = 6:4–7:3, which is almost the same with that of anode material composition.
- Published
- 2019
55. Myasthenia gravis after allogeneic bone marrow transplantation: A case report and literature review
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Ryo Kikuchi, Yutaka Tsutsumi, Shinichi Ito, Takanori Teshima, Satomi Matsuoka, and Takashi Kamiishi
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Male ,0301 basic medicine ,medicine.medical_treatment ,Graft vs Host Disease ,Hematopoietic stem cell transplantation ,Disease ,lcsh:RC254-282 ,Lower limb weakness ,03 medical and health sciences ,0302 clinical medicine ,Myasthenia Gravis ,medicine ,Humans ,Autogenous bone ,Bone Marrow Transplantation ,lcsh:RC633-647.5 ,business.industry ,Marrow transplantation ,Myeloid leukemia ,lcsh:Diseases of the blood and blood-forming organs ,Hematology ,General Medicine ,Odds ratio ,Middle Aged ,Allografts ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,medicine.disease ,Myasthenia gravis ,Leukemia, Myeloid, Acute ,surgical procedures, operative ,030104 developmental biology ,Oncology ,Chronic Disease ,Immunology ,business ,030217 neurology & neurosurgery - Abstract
A 52-year-old man with acute myeloid leukemia underwent allogeneic hematopoietic stem cell transplantation and developed extensive chronic graft-versus-host disease and myasthenia gravis (MG), which became involved with oculobulbar and proximal upper and lower limb weakness in 677 days. In the literature, we identified 24 cases where MG developed after allo-SCT. Graft-versus-host disease development and male recipients of female donors might be prone to the development of posttransplant MG (odds ratio, 3.75). Keywords: Acetylcholine receptor antibody, Allogeneic stem cell transplantation, Chronic GVHD, Myasthenia gravis
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- 2019
56. Gene Polymorphism of Tacrolimus-Metabolizing Enzymes Associated With Impaired Absorption of Tacrolimus Following Allogeneic Hematopoietic Stem Cell Transplantation: A Case Report
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Shinichi Ito, Takanori Teshima, Satomi Matsuoka, Ryo Kikuchi, and Yutaka Tsutsumi
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Adolescent ,Cyclophosphamide ,medicine.medical_treatment ,Administration, Oral ,Graft vs Host Disease ,Hematopoietic stem cell transplantation ,Pharmacology ,Polymerase Chain Reaction ,Tacrolimus ,Oral administration ,medicine ,Humans ,ATP Binding Cassette Transporter, Subfamily B, Member 1 ,Transplantation ,Polymorphism, Genetic ,CYP3A4 ,business.industry ,Hematopoietic Stem Cell Transplantation ,DNA ,medicine.disease ,Fludarabine ,Leukemia, Myeloid, Acute ,Leukemia ,surgical procedures, operative ,Female ,Surgery ,business ,Immunosuppressive Agents ,Busulfan ,medicine.drug - Abstract
Objective To elucidate the mechanisms by which orally administered tacrolimus was not absorbed in a patient following allogeneic hematopoietic stem cell transplantation. Clinical Course A 17-year-old girl with acute myeloid leukemia underwent HLA-haploidentical peripheral blood stem cell transplantation following fludarabine, busulfan, and total-body irradiation. Graft-vs-host disease prophylaxis was post-transplant cyclophosphamide, followed by intravenous tacrolimus and mycophenolate mofetil. When tacrolimus was switched to oral administration, its blood level declined rapidly, resulting in development of acute graft-vs-host disease, which was ameliorated by switching back to intravenous administration. Methods/Results To elucidate if impaired tacrolimus absorption could be related to genetic polymorphism of tacrolimus-metabolizing enzymes, we analyzed gene polymorphisms of cytochrome P450 3A4, cytochrome P450 3A5, and multidrug resistance 1 (MDR1). The patient had wild-type cytochrome P450 3A4 (*1/*1) and variant-type cytochrome P450 3A5 (*3/*3), while MDR1 genes (2677A/G, 3435C/C) were wild-type. Conclusion Wild-type MDR1 gene product P-glycoprotein expressed in the intestine reduces drug absorption from the gastrointestinal tract and may have contributed to low blood levels of tacrolimus in this patient when tacrolimus was orally administered.
- Published
- 2019
57. Effect of high hydrostatic pressure and reducing sodium chloride and phosphate on physicochemical properties of beef gels
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Ryo Kikuchi, Anastasiia Maksimenko, Tadayuki Nishiumi, and Satomi Tsutsuura
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chemistry.chemical_compound ,chemistry ,Sodium ,0103 physical sciences ,Hydrostatic pressure ,chemistry.chemical_element ,010502 geochemistry & geophysics ,010306 general physics ,Condensed Matter Physics ,Phosphate ,01 natural sciences ,0105 earth and related environmental sciences ,Nuclear chemistry - Abstract
The effect of high hydrostatic pressure (HHP) treatment (100–200 MPa, 10 min, 20°C) combined with sodium chloride and sodium phosphate on the physicochemical properties of beef gels was investigate...
- Published
- 2019
58. An Economic Feasibility Analysis Of Inclusionary Zoning In Toronto, Ontario
- Author
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Ryo Kikuchi
- Abstract
The Government of Ontario has recently introduced legislation which would allow municipalities to implement inclusionary zoning, a policy tool which would require developers to include affordable housing units in new residential developments. This study examines the potential impacts that implementing an inclusionary zoning program would have on the decision making process of developers operating in the Toronto housing market. The author found that without sufficient incentives inclusionary zoning policies impact the financial returns new developments are able to generate. This paper concludes that in order for inclusionary zoning to be successfully implemented without causing financial hardship on developers, incentives such as density bonuses should be offered.
- Published
- 2021
59. Flavonoids in the flowers of Primula ×polyantha Mill. and Primula primulina (Spreng.) H. Hara (Primulaceae)
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Rinchen Yangzom, Toru Ota, Takayuki Mizuno, Kazuhisa Kato, Yoshinori Murai, Fumi Tatsuzawa, Ryo Kikuchi, and Tsukasa Iwashina
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0106 biological sciences ,Plant Science ,Flowers ,Horticulture ,Biology ,01 natural sciences ,Biochemistry ,Anthocyanins ,chemistry.chemical_compound ,Flavonols ,Primulina ,Botany ,Molecular Biology ,Primulaceae ,chemistry.chemical_classification ,Flavonoids ,Peonidin ,010405 organic chemistry ,General Medicine ,biology.organism_classification ,Hirsutidin ,0104 chemical sciences ,Primula ,chemistry ,Petal ,Kaempferol ,010606 plant biology & botany - Abstract
Two undescribed anthocyanins and two undescribed flavonols were isolated from the flowers of Primula ×polyantha Mill., along with five known anthocyanins and four known flavonols. The two undescribed anthocyanins and the two undescribed flavonols were determined to be hirsutidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside, 7-O-methyl-petunidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside, quercetin 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside], and kaempferol 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside] using chemical and spectroscopic methods. They were also found in the flowers of the Himalayan wild species, Primula primulina (Spreng.) H. Hara except for quercetin 3-O-β-[(6""-acetylglucopyranosyl)-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside]. The flower color variations of P. ×polyantha cultivars, reflected by the hue values (b*/a*) of the colors, were due to the glycosidic patterns in the anthocyanins and their concentrations in the petals. Moreover, in the P. ×polyantha cultivars with violet-blue flowers, both the intermolecular copigmentation occurs between hirsutidin 3-O-β-galactopyranoside-5-O-β-glucopyranoside and another flavonol, quercetin 3-O-β-glucopyranosyl-(1 → 2)-β-glucopyranosyl-(1 → 6)-β-glucopyranoside. Moreover, the flower color variation was affected by the pH value.
- Published
- 2021
60. Electron and Neutral Density Distributions of Vacuum Arcs Under Anode-Spot Mode
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Ryo Kikuchi, Akiko Kumada, Haruki Ejiri, Kunihiko Hidaka, Yuichi Hirano, and Yuki Inada
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Anode spot ,Materials science ,Mode (statistics) ,Electron ,Electrical and Electronic Engineering ,Atomic physics ,Neutral density filter - Published
- 2021
61. Evaluation and Improvement Proposals for a Business Facility Solar and Ground-Heat Hybrid Heat Supply System
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Andante Hadi Pandyaswargo, Daiki Yoshidome, Ryo Kikuchi, and Hiroshi Onoda
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Ideal (set theory) ,Piping ,business.industry ,Nuclear engineering ,Heat supply ,Coefficient of performance ,law.invention ,Thermal insulation ,law ,Geothermal heat pump ,Environmental science ,business ,Efficient energy use ,Heat pump - Abstract
In this study, we proposed improvements based on actual measured data of a hybrid heat supply system that uses solar heat and ground heat as the heat sources of a restaurants complex in Honjo city, Saitama, Japan. Our evaluation from the actual monitoring measurements showed that the solar heat collection efficiency was 50–60%. The geothermal Heat Pump’s Coefficient of Performance decreased significantly in the summer. We propose to set the heat insulation and burial depth of the piping from the ground heat collection to the heat pump and recommends five units of 5 units of solar heat collectors as the most ideal scenario.
- Published
- 2020
62. Intestinal goblet cells protect against GVHD after allogeneic stem cell transplantation via Lypd8
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Hiroyuki Ohigashi, Yuta Hasegawa, Ko Ebata, Reiki Ogasawara, Keitaro Matsuo, Ryo Kikuchi, Daigo Hashimoto, Yoshihiro Matsuno, Takanori Teshima, Masahiro Onozawa, Emi Yokoyama, Eiko Hayase, Shuichiro Takahashi, Junichi Sugita, Takahide Ara, Clara Noizat, Kana Matsuda, Kiyoshi Takeda, Shoko Ono, and Ryu Okumura
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0301 basic medicine ,medicine.medical_treatment ,Graft vs Host Disease ,Hematopoietic stem cell transplantation ,Gut flora ,digestive system ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Intestinal mucosa ,immune system diseases ,medicine ,Animals ,Intestinal Mucosa ,Inner mucus layer ,Goblet cell ,biology ,business.industry ,Hematopoietic Stem Cell Transplantation ,General Medicine ,respiratory system ,biology.organism_classification ,Mucus ,Gastrointestinal Microbiome ,Transplantation ,surgical procedures, operative ,030104 developmental biology ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Immunology ,Goblet Cells ,Stem cell ,business - Abstract
Graft-versus-host disease (GVHD) and infection are major obstacles to successful allogeneic hematopoietic stem cell transplantation (HSCT). Intestinal goblet cells form the mucus layers, which spatially segregate gut microbiota from host tissues. Although it is well known that goblet cell loss is one of the histologic features of GVHD, effects of their loss in pathophysiology of GVHD remain to be elucidated. In mouse models of allogeneic HSCT, goblet cells in the colon were significantly reduced, resulting in disruption of the inner mucus layer of the colon and increased bacterial translocation into colonic mucosa. Pretransplant administration of interleukin-25 (IL-25), a growth factor for goblet cells, protected goblet cells against GVHD, prevented bacterial translocation, reduced plasma concentrations of interferon-γ (IFN-γ) and IL-6, and ameliorated GVHD. The protective role of IL-25 was dependent on Lypd8, an antimicrobial molecule produced by enterocytes in the colon that suppresses motility of flagellated bacteria. In clinical colon biopsies, low numbers of goblet cells were significantly associated with severe intestinal GVHD, increased transplant-related mortality, and poor survival after HSCT. Goblet cell loss is associated with poor transplant outcome, and administration of IL-25 represents an adjunct therapeutic strategy for GVHD by protecting goblet cells.
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- 2020
63. Progress of Secure Computation: Basic Constructions and Dedicated Algorithms
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Ryo Kikuchi and Dai Ikarashi
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- 2018
64. Evaluation of Thermal Resistance for Underfill Layer in Three-dimensional Stacked ICs by Transient Thermal Analysis
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Seiki Sakuyama, Ryo Kikuchi, Taiji Sakai, and Makoto Sasaki
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Materials science ,Thermal resistance ,Transient (oscillation) ,Composite material ,Thermal analysis ,Layer (electronics) ,Flip chip - Published
- 2018
65. Password-Based Authentication Protocol for Secret-Sharing-Based Multiparty Computation
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Koji Chida, Koki Hamada, Ryo Kikuchi, and Dai Ikarashi
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0301 basic medicine ,Password ,Authentication ,Computer science ,business.industry ,Applied Mathematics ,Computation ,0102 computer and information sciences ,01 natural sciences ,Computer Graphics and Computer-Aided Design ,Secret sharing ,03 medical and health sciences ,030104 developmental biology ,010201 computation theory & mathematics ,Authentication protocol ,Signal Processing ,Electrical and Electronic Engineering ,business ,Computer network - Published
- 2018
66. Analysis of Fluid Flow in Heat Exchanger with Scraping Boundary Layer
- Author
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Ryo Kikuchi
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Boundary layer ,Materials science ,Heat exchanger ,Fluid dynamics ,Mechanics - Published
- 2018
67. Gvhd Targets Organoid-Forming Biliary Epithelial Stem Cells Via a TGF-β-Dependent Manner
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Emi Yokoyama, Daigo Hashimoto, Zixuan Zhang, Eiko Hayase, Kazuki Yoneda, Takahide Ara, Takanori Teshima, Shuichiro Takahashi, Tomoko Sekiguchi, Takahiro Tateno, Hiroyuki Ohigashi, Yuta Hasegawa, Xuanzhong Chen, Hajime Senjo, and Ryo Kikuchi
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Dependent manner ,Chemistry ,Immunology ,Organoid ,Cell Biology ,Hematology ,Stem cell ,Biochemistry ,health care economics and organizations ,Transforming growth factor ,Cell biology - Abstract
[Introduction] Graft-versus-host disease (GVHD) is a potentially life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). We and others have shown that GVHD targets adult tissue stem cells in the gut and skin, while a role of liver tissue stem cells in hepatic GVHD remains to be clarified. Biliary epithelial cells (BECs) are primary targets in hepatic GVHD and a single BEC stem cell gives rise to multipotent liver organoids (Cao W: Gastroenterology 2017). We studied the fate and role of BEC stem cells in experimental hepatic GVHD. [Methods] B6D2F1 recipients were lethally irradiated and transplanted with 5 x 10 6 splenocytes plus 5 x 10 6 bone marrow cells from allogeneic (B6) or syngeneic (B6D2F1) donors on day 0. Liver organoids were generated from the bile ducts isolated from the liver right lobe. [Results] Flowcytometric analyses of the liver demonstrated donor T cell infiltration in the liver within the first week after allo-HCT, followed by massive infiltration of monocytes and macrophages. Hepatic GVHD was characterized by apoptosis of BEC (Figure 1A), elevated expression of Mmp7, a biomarker of biliary injury (Figure 1B), and elevation of plasma levels of total bilirubin (Figure 1C). To evaluate fate of BEC stem cells in hepatic GVHD, we enumerated BEC-derived organoids generated from the right lobe of the liver isolated after allo-HCT. The organoid-forming BEC stem cells were profoundly reduced at later time point after allo-HCT (Figure 1D), while they persisted in syngeneic controls, indicating that GVHD targets BEC stem cells. Next, we explored the mechanism of BEC stem cell injury. Among the cytokines elevated in the liver after allo-HCT, we found that TGF-β , not IFN-γ or TNF-α, inhibited generation of liver organoids (Figure 1E). Furthermore, we found that liver infiltrating mononuclear cells isolated from the allogeneic livers, not from syngeneic livers, suppressed growth of liver organoids. This effect was abrogated by the addition of a TGF-β inhibitor, SB-431542 in culture. Among these cells, monocyte-derived macrophages, not Kupffer cells, demonstrated enhanced production of TGF-β after allo-HCT (Figure 1F), suggesting that TGF-β from inflammatory macrophages damaged BEC stem cells. Based on these findings, we next tested if TGF-β inhibition could protect BEC stem cells and ameliorate hepatic GVHD after allo-HCT. Admnistration of SB-431542 from day +14 to day +28 after allo-HCT significantly increased organoid-forming BEC stem cells, suppressed BEC apoptosis and Mmp7 expression, and mitigated jaundice on day +28 after allogeneic HCT, indicating that TGF-β inhibition is a novel therapeutic strategy against hepatic GVHD (Figure 1, G-J). [Conclusion] Our results for the first time demonstrated that hepatic GVHD targets BEC stem cells via a TGF-β-dependent manner. Mmp7 and organoid-forming capacity could be the biomarkers for hepatic GVHD. BEC stem-cell protection by TGF-β inhibition is a promising novel therapeutic strategy against hepatic GVHD. Figures1: (A) Proportion of cleaved caspase 3 (cCaspase3) + cells among the biliary epithelial cells (BECs) on day +28. (B) Total RNA extracted from the liver on day +28 was subjected to Q-PCR targeting Mmp7. (C) Plasma levels of total bilirubin at indicated time points. (D) The numbers of organoid derived from the right lobe of the liver at indicated time point are shown. (E) Absolute numbers of TGF-β producing Kupffer cells and macrophages (Mφ) in the liver on day +28 are shown. (F) Liver organoids were enumerated after incubation in the presence or absence of TGF-β for 4 days. (G-J) Allogeneic recipients were intraperitoneally injected with 5 mg/kg SB-431542 daily from day +14 to day +28 after allogeneic HCT, and recipient mice were sacrificed on day +28. Numbers of organoids derived from the right lobe of the livers (G), the proportion of cCaspase3 + BECs (H), relative expression of Mmp7 in the liver (I), and plasma levels of total bilirubin (J) are shown. *; p < .05, **; p < .01, ***; p < .005. Figure 1 Figure 1. Disclosures Teshima: CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding; Takeda Pharmaceutical Company: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis International AG: Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Gentium/Jazz Pharmaceuticals: Consultancy; Bristol Myers Squibb: Honoraria; Sanofi S.A.: Research Funding; TEIJIN PHARMA Limited: Research Funding; Nippon Shinyaku Co., Ltd.: Research Funding; Fuji pharma CO.,Ltd: Research Funding; Pfizer Inc.: Honoraria; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Kyowa Kirin Co.,Ltd.: Honoraria, Research Funding; Astellas Pharma Inc.: Research Funding; Janssen Pharmaceutical K.K.: Other.
- Published
- 2021
68. Computational SS and conversion protocols in both active and passive settings
- Author
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Wakaha Ogata, Dai Ikarashi, Koki Hamada, Ryo Kikuchi, and Koji Chida
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Protocol (science) ,Computer Networks and Communications ,business.industry ,Computer science ,020206 networking & telecommunications ,02 engineering and technology ,Cryptographic protocol ,Secret sharing ,Computer data storage ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,business ,Software ,Information Systems ,Block (data storage) ,Computer network - Abstract
Secret sharing (SS) has been extensively studied as both a means of secure data storage and a fundamental building block for multiparty computation (MPC). For these purposes, code-efficiency and MPC-suitability are required for SS but they are incomparable. Recently, a computational SS and a conversion protocol were proposed. The computational SS is code-efficient and the conversion protocol converts shares of the computational (code-efficient) SS into those of an MPC-suitable SS, and it can be applied to reduce the amount of data storage while maintaining extendibility to MPC. However, this protocol is one-way: one cannot convert the share of MPC output value. In addition, it is only passively secure. The authors propose three protocols and a new computational SS. The first protocol is the inverse of the existing protocol, that is, it converts an MPC-suitable SS to the existing SS. The other two protocols are actively secure conversion protocols that convert shares between the new SS and an MPC-suitable SS. The new computational SS is code-efficient when the number of parties is small, so these two protocols are for converting between the code-efficient SS and an MPC-suitable SS. These two conversion protocols are actively secure in the honest majority.
- Published
- 2017
69. Change of the Effective Strength of Grain Boundaries in Alloy 617 Under Creep-Fatigue Loadings at 800°C
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Hideo Miura, Kenta Ishihara, Wataru Suzuki, Ryo Kikuchi, and Ken Suzuki
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Crystallinity ,Materials science ,Creep ,Alloy ,engineering ,Grain boundary ,engineering.material ,Composite material ,Creep fatigue ,Electron backscatter diffraction - Abstract
In this study, both EBSD (Electron Back-Scatter Diffraction) analysis and a micro tensile test system with FIB (Focused Ion Beam) equipment were applied to bicrystal specimens of Alloy 617 in order to establish a quantitative theory of the lifetime evaluation method under creep-fatigue loadings. The IQ (Image Quality) value which is obtained from the diffraction pattern (Kikuchi pattern) indicates the total density of defects such as vacancies, dislocations, and local strain was used for quantitatively evaluating the crystallinity of the alloy. KAM (Kernel Average Misorientation) value was also used for density analysis of GN (Generally Necessary) dislocations. Continuous changes of microtexture of grains and grain boundaries were observed by applying an intermittent creep fatigue test. As a result, it was confirmed that the IQ value around specific grain boundaries in damaged specimen was drastically degraded compared to that of the initial specimen. Intergranular cracks always occurred when the IQ value decreased to a certain value. Therefore, there is a correlation between the IQ value and the strength of a grain boundary in this alloy. The decrease of the IQ value was attributed to the accumulation of both dislocations and vacancies around the specific grain boundaries under creep loading. The accumulation rate under the creep-fatigue loading was clearly higher than that under simple fatigue and creep loadings. Finally, it was clarified that the degradation of the crystallinity in the vicinity of a grain boundary was a criterion of an intergranular crack under creep-fatigue loadings.
- Published
- 2019
70. Optimization Method for Controller Parameters Using Support Vector Machine
- Author
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Takenori Atsumi, Toshiki Saito, and Ryo Kikuchi
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Support vector machine ,Control theory ,Computer science ,Control system ,0202 electrical engineering, electronic engineering, information engineering ,020206 networking & telecommunications ,020201 artificial intelligence & image processing ,02 engineering and technology ,Inverted pendulum - Abstract
In actual industrial processes, it is difficult to optimize parameters for a control system because of its perturbations. As a result, the performance of the control system may depend on a designer experience. To solve this problem, we have proposed a method to optimize the controller parameters with support vector machine. With the proposed method, we can obtain a robust controller without the need for designer's rich experience. Experimental results show that the proposed method enables us to design parameters for a robust controller in a two-wheeled inverted pendulum.
- Published
- 2019
71. Efficient Secure Multi-Party Protocols for Decision Tree Classification
- Author
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Koki Hamada, Ryo Kikuchi, Atsunori Ichikawa, and Wakaha Ogata
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Polynomial (hyperelastic model) ,050101 languages & linguistics ,05 social sciences ,Decision tree ,02 engineering and technology ,Exponential function ,Combinatorics ,Tree (descriptive set theory) ,Maximum depth ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,0501 psychology and cognitive sciences ,Oblivious ram ,Communication complexity ,MathematicsofComputing_DISCRETEMATHEMATICS ,Mathematics - Abstract
We propose novel secure multi-party protocols for decision-tree classification. Our protocols hide not only an input vector and an output class but also the structure of the tree, which incurs an exponential communication complexity in terms of the maximum depth of the tree, \(d_{max}\), for a naive construction. We tackle this problem by applying Oblivious RAM (ORAM) and obtain two efficient constructions with polynomial communication complexity (that counts the number of multiplications). The first protocol simulates ORAM in secure multi-party computation. The communication complexity of the first protocol is \(O(d_{max}^3 \log d_{max})\) in the online phase and \(O(d_{max}^4 \log d_{max})\) in total. We then improve this protocol by removing the position-map accesses, which is the most time-consuming parts in the ORAM. In the second protocol, we reduce the communication complexity to \(O(d_{max}^2 \log d_{max})\) in the online phase and \(O(d_{max}^3 \log d_{max})\) in total, and also reduce the number of rounds from \(O(d_{max}^2)\) to \(O(d_{max})\). We implemented the proposed two constructions and the naive one, and experimentally evaluated their performance.
- Published
- 2019
72. Field Extension in Secret-Shared Form and Its Applications to Efficient Secure Computation
- Author
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Ai Ishida, Ryo Kikuchi, Jacob C. N. Schuldt, Yusuke Sakai, Dai Ikarashi, Takahiro Matsuda, Nuttapong Attrapadung, and Koki Hamada
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Password ,Authentication ,Computer science ,Computation ,Boolean circuit ,Distributed computing ,020206 networking & telecommunications ,02 engineering and technology ,Secret sharing ,Consistency (database systems) ,0202 electrical engineering, electronic engineering, information engineering ,Secure multi-party computation ,020201 artificial intelligence & image processing ,Protocol (object-oriented programming) - Abstract
Secure computation enables participating parties to jointly compute a function over their inputs while keeping them private. Secret sharing plays an important role for maintaining privacy during the computation. In most schemes, secret sharing over the same finite field is normally utilized throughout all the steps in the secure computation. A major drawback of this “uniform” approach is that one has to set the size of the field to be as large as the maximum of all the lower bounds derived from all the steps in the protocol. This easily leads to a requirement for using a large field which, in turn, makes the protocol inefficient. In this paper, we propose a “non-uniform” approach: dynamically changing the fields so that they are suitable for each step of computation. At the core of our approach is a surprisingly simple method to extend the underlying field of a secret sharing scheme, in a non-interactive manner, while maintaining the secret being shared. Using our approach, default computations can hence be done in a small field, which allows better efficiency, while one would extend to a larger field only at the necessary steps. As the main application of our technique, we show an improvement upon the recent actively secure protocol proposed by Chida et al. (Crypto’18). The improved protocol can handle a binary field, which enables XOR-free computation of a boolean circuit. Other applications include efficient (batch) equality check and consistency check protocols, which are useful for, e.g., password-based threshold authentication.
- Published
- 2019
73. [Thrombotic microangiopathy developing subsequent to tocilizumab therapy in a patient with TAFRO syndrome]
- Author
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Shinichi, Ito, Yutaka, Tsutsumi, Ryo, Kikuchi, Satomi, Matsuoka, and Norihiko, Shimoyama
- Subjects
Male ,Thrombotic Microangiopathies ,Castleman Disease ,Humans ,Middle Aged ,Antibodies, Monoclonal, Humanized - Abstract
We report a case of a 60-year-old male who presented with fever and anasarca as well as hepatosplenomegaly, general lymphadenopathy, and disseminated intravascular coagulation (DIC), and was, therefore, admitted to our hospital. In addition, the patient suffered from respiratory failure and renal dysfunction and had pleural effusion and ascites. The pathological diagnosis from lymph node biopsy suggested multicentric Castleman's disease of the plasma cell type; however, the presence of high IL-6 levels, myelofibrosis, thrombocytopenia, anasarca, renal dysfunction, and hepatosplenomegaly led to a definitive diagnosis of TAFRO syndrome. Tocilizumab was administered on day 15 of disease diagnosis, resulting in the improvement in DIC but not other symptoms. As schizocytes were detected in the peripheral blood, he also experienced disturbance of consciousness and thrombotic microangiopathy (TMA) was considered. Following plasma exchange (PE) and continuous hemodiafiltration (CHDF), his symptoms temporarily improved. However, his condition worsened again, and he eventually died on day 33. Pathological autopsy revealed that although the lymph nodes were not enlarged, he had organomegaly, gastrointestinal and omental hemorrhage, and acute necrotizing pancreatitis. Since TMA developed after the administration of tocilizumab, the possibility of drug-induced secondary TMA cannot be ruled out.
- Published
- 2018
74. Gilteritinib Enhances Graft-Versus-Leukemia Effects Against FLT3-ITD+ Leukemia after Mouse Allogeneic HSCT
- Author
-
Tatsuya Kawase, Tomoko Sekiguchi, Ryo Kikuchi, Zixuan Zhang, Masao Nakagawa, Kazuki Yoneda, Takanori Teshima, Hajime Senjo, Daigo Hashimoto, Hirofumi Tsuzuki, Hiroyuki Ohigashi, Yuta Hasegawa, Xuanzhong Chen, and Takashi Ishio
- Subjects
Transplantation ,business.industry ,Gilteritinib ,Cell Biology ,Hematology ,medicine.disease ,Leukemia ,Allogeneic hsct ,Cancer research ,Molecular Medicine ,Immunology and Allergy ,Medicine ,business ,Flt3 itd - Published
- 2021
75. Understanding the actual situation of energy supply and demand in large-scale waste treatment and recycling facilities and evaluating the effect of CO2 reduction
- Author
-
Ryo KIKUCHI, Yuki OKANOYA, Daiki YOSHIDOME, and Hiroshi ONODA
- Published
- 2021
76. Fundamental Study on the Mechanism of Intergranular Cracking in Polycrystalline Ni-Based Superalloys by using Molecular Dynamics Analysis
- Author
-
Ken Suzuki and Ryo Kikuchi
- Subjects
Superalloy ,Molecular dynamics ,Fundamental study ,Cracking ,Materials science ,Thermodynamics ,Crystallite ,Intergranular corrosion ,Mechanism (sociology) - Published
- 2021
77. Effect of high hydrostatic pressure in combination with low salt content for the improvement of texture and palatability of meat gels
- Author
-
Satomi Tsutsuura, Tadayuki Nishiumi, Anastasiia Maksimenko, and Ryo Kikuchi
- Subjects
Materials science ,Low salt ,Hydrostatic pressure ,Palatability ,Food science ,Texture (crystalline) - Abstract
The effect of high hydrostatic pressure (HHP) treatment of 200 MPa for 10 min at room temperature in combination with salt (sodium chloride) and phosphate (sodium pyrophosphate) addition on the microstructure and sensory characteristics of beef gels were investigated. Sensory evaluation was involving students and staff of the Niigata University, using Scheffe’s paired comparison method with grade. Gel microstructure was observed using scanning electron microscopy (JSM-6510LA, JEOL LTD., Japan). The free amino acid content of beef gels was analyzed by an amino acid analyzer (JLC-500/V, JEOL LTD., Japan). The results of sensory evaluation revealed that high pressure at 200 MPa improved the cohesiveness and springiness (elasticity) while significantly decreasing the softness in low salt and/or low phosphate beef gels (p < 0.05). Irrespective of the salt and/or phosphate content in the beef samples, panellists noted that the pressurized beef gels were firmer, more elastic, and more pleasant to bite. The scanning electron microscopy images revealed that high pressure treatment at 200 MPa produced a dense, homogeneous networked structure with small cavities for water retention in low salt beef gels. The total free amino acid content of low salt and/or low phosphate beef gels was increased by high pressure at 200 MPa (p < 0.05). The present study confirmed that high hydrostatic pressure at 200 MPa was effective in producing low salt and/or low phosphate beef gels while providing high quality textural and organoleptic properties.
- Published
- 2020
78. Influence of CuCr electrode composition on 2D electron and metal vapor density distribution over vacuum arc
- Author
-
Kunihiko Hidaka, Ryo Kikuchi, Hiroyuki Nagai, Mitsuaki Maeyama, Yuki Inada, and Akiko Kumada
- Subjects
Electrode material ,Electron density ,Materials science ,Vapour density ,Acoustics and Ultrasonics ,Analytical chemistry ,Electron ,Vacuum arc ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Metal ,visual_art ,Vacuum circuit breakers ,Electrode ,visual_art.visual_art_medium - Published
- 2020
79. Numerical Simulation of Turbulent-like Behavior of Air and SF6 Arc Plasmas in a Model Circuit Breaker
- Author
-
Yasunori Tanaka, Masaya Shigeta, Akiko Kumada, Takayasu Fujino, Yuki Inada, and Ryo Kikuchi
- Subjects
Arc (geometry) ,Materials science ,Computer simulation ,Turbulence ,Mechanics ,Plasma ,Circuit breaker - Published
- 2020
80. Molecular Dynamics Analysis of the Mechanism of Grain Boundary Cracking of a Copper Bicrystal by Defect Accumulation
- Author
-
Ken Suzuki, Hideo Miura, and Ryo Kikuchi
- Subjects
Molecular dynamics ,Cracking ,Materials science ,chemistry ,Chemical physics ,chemistry.chemical_element ,Grain boundary ,Copper ,Mechanism (sociology) - Published
- 2020
81. Evaluation of the in-vessel heat transfer for the debris removal of the Fukushima Daiichi nuclear power plant
- Author
-
Ryo Kikuchi, Hikaru Mitsuda, Shuichiro Miwa, Katsumasa Miyoshi, Nassim Sahboun, and Michitsugu Mori
- Subjects
Scope (project management) ,Power station ,020209 energy ,Nuclear engineering ,Energy Engineering and Power Technology ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Debris ,Nuclear decommissioning ,law.invention ,Nuclear Energy and Engineering ,law ,Heat transfer ,Nuclear power plant ,0202 electrical engineering, electronic engineering, information engineering ,Environmental science ,Decay heat ,Current (fluid) ,Safety, Risk, Reliability and Quality ,Waste Management and Disposal ,0105 earth and related environmental sciences - Abstract
As the investigation on the decommissioning of Fukushima Daichi Power Plant (F1) advances further, deepening the knowledge on the reactor building behavior under the different debris removal method is a vital assessment to be made. As the submersion-method has been well investigated in the past, the main scope of the current paper will be on the dry-method where it is assumed that the debris cooling takes place under contact with a small quantity of water or with the air. In this paper, following the discussion of the effectiveness of the dry retrieval method for F1, the feasibility of the method is assessed under the different debris location assumption and time-evolving decay heat from the debris. From the analysis result, potential improvement, as well as the applicability of dry-method, will be discussed.
- Published
- 2020
82. Molecular Dynamics Analysis on the Intergranular Cracking Mechanism of Ni-base Superalloy due to the Accumulation of Vacancies around a Grain Boundary
- Author
-
Ryo Kikuchi, Hideo Miura, and Ken Suzuki
- Subjects
Superalloy ,Molecular dynamics ,Cracking ,Materials science ,Metallurgy ,Grain boundary ,Intergranular corrosion ,Base (exponentiation) ,Mechanism (sociology) - Published
- 2020
83. Rituximab Maintenance Therapy and Bendamustine Containing Treatments may improve the Survival of Mantle Cell Lymphoma: Retrospective Analysis in Single Institute
- Author
-
Yutaka Tsutsumi, Ryo Kikuchi, Shinichi Ito, and Satomi Matsuoka
- Subjects
Oncology ,Bendamustine ,medicine.medical_specialty ,business.industry ,Induction chemotherapy ,medicine.disease ,International Prognostic Index ,Maintenance therapy ,immune system diseases ,hemic and lymphatic diseases ,Internal medicine ,medicine ,Autologous transplantation ,Rituximab ,Mantle cell lymphoma ,business ,Survival rate ,medicine.drug - Abstract
Introduction: The prognosis for mantle cell lymphoma (MCL) has remained poor despite the current use of autologous transplantation and induction chemotherapy that includes high-dose cytarabine. The introduction of rituximab and bendamustine, however, has led to the improvement of prognosis of diffuse large B-Cell lymphoma and indolent lymphoma. For these reasons, we analyzed the effectivity of rituximab maintenance therapy and bendamustine against mantle cell lymphoma at our hospital.Methods: We selected 22 cases of MCL for which treatment was initiated between January 2004 and December 2016 at our hospital. We compared the cases based on the use of rituximab maintenance therapy or bendamustine, simplified Mantle Cell Lymphoma International Prognostic Index (sMIPI), staging, and treatment regimens to analyze the effect of rituximab maintenance therapy and bendamustine on prognosis.Results: Overall five-year survival rate was 67%. Significant difference (P=0.0432) was observed in the 5-year survival rate between the group treated with rituximab maintenance therapy (90.9%) and the group that was not (56.2%). Likewise, significant difference (P=0.0197) was observed in the 5-year survival rate between the group that received bendamustine during the course of treatment (90.9%) and the group that did not (50%). Majority of the cases in the group that received bendamustine, however, had been treated with rituximab maintenance therapy.Conclusion: Our study showed an improvement in prognosis of MCL due to the treatment with rituximab maintenance therapy and bendamustine. Although the analysis was conducted on a limited number of cases, we believe that rituximab maintenance therapy and treatments that include bendamustine are promising therapies for MCL.
- Published
- 2018
84. High-Throughput Secure AES Computation
- Author
-
Koki Hamada, Benny Pinkas, Ryo Kikuchi, Koji Chida, and Dai Ikarashi
- Subjects
Computer science ,business.industry ,Computation ,Distributed computing ,media_common.quotation_subject ,Advanced Encryption Standard ,Secure multi-party computation ,Benchmark (computing) ,Performance improvement ,business ,Function (engineering) ,Throughput (business) ,Protocol (object-oriented programming) ,media_common - Abstract
This work describes a three-times ($3\times$) improvement to the performance of secure computation of AES over a network of three parties with an honest majority. The throughput that is achieved is even better than that of computing AES in some scenarios of local (non-private) computation. The performance improvement is achieved through an optimization of the generic secure protocol, and, more importantly, through an optimization of the description of the AES function to support more efficient secure computation, and an optimization of the protocol to the underlying architecture. This demonstrates that the development process of efficient secure computation must include adapting the description of the computed function to be tailored to the protocol, and adapting the implementation of the protocol to the architecture. This work focuses on the secure computation of AES since it has been widely investigated as a de-facto standard performance benchmark for secure computation, and is also important by itself for many applications. Furthermore, parts of the improvements are general and not specific to AES, and can be applied to secure computation of arbitrary functions.
- Published
- 2018
85. Comparative Study of the Effectiveness of Perturbative Methods for Creating Official Microdata in Japan
- Author
-
Toru Yoshitake, Ryo Kikuchi, Fumika Akutsu, and Shinsuke Ito
- Subjects
060201 languages & linguistics ,Computer science ,0602 languages and literature ,0202 electrical engineering, electronic engineering, information engineering ,Econometrics ,Microdata (statistics) ,020201 artificial intelligence & image processing ,06 humanities and the arts ,02 engineering and technology ,Census ,Coding (social sciences) - Abstract
The Statistics Bureau of Japan currently creates and provides anonymized microdata for six surveys. Anonymized microdata from the Population Census of Japan are created using non-perturbative methods such as recoding, top coding, and record deletion as well as the perturbative method of swapping.
- Published
- 2018
86. Adaptively and Unconditionally Secure Conversion Protocols between Ramp and Linear Secret Sharing
- Author
-
Koji Chida, Koki Hamada, Dai Ikarashi, and Ryo Kikuchi
- Subjects
Homomorphic secret sharing ,Proactive secret sharing ,Computer science ,Applied Mathematics ,Computer security ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Secret sharing ,Shamir's Secret Sharing ,Active security ,Signal Processing ,Secure multi-party computation ,Verifiable secret sharing ,Electrical and Electronic Engineering ,computer - Published
- 2015
87. Secret Sharing with Share-Conversion: Achieving Small Share-Size and Extendibility to Multiparty Computation
- Author
-
Dai Ikarashi, Koki Hamada, Ryo Kikuchi, Koji Chida, Wakaha Ogata, and Katsumi Takahashi
- Subjects
Homomorphic secret sharing ,Theoretical computer science ,Proactive secret sharing ,Computer science ,Applied Mathematics ,Computation ,Computer security ,computer.software_genre ,Computer Graphics and Computer-Aided Design ,Secret sharing ,Signal Processing ,Secure multi-party computation ,Verifiable secret sharing ,Electrical and Electronic Engineering ,computer - Published
- 2015
88. Efficacy and prognosis of antiviral therapy on hepatitis C following treatment of lymphoma in HCV-positive diffuse large-cell lymphoma
- Author
-
Souichi Shiratori, Yutaka Tsutsumi, Hirohito Naruse, Satomi Matsuoka, Daiki Kudo, Yoshiya Yamamoto, Shinichi Ito, Takanori Teshima, Chie Nakayama, Koki Kamada, and Ryo Kikuchi
- Subjects
Oncology ,Male ,medicine.medical_treatment ,Pilot Projects ,Hepacivirus ,CHOP ,Antibodies, Monoclonal, Murine-Derived ,0302 clinical medicine ,hemic and lymphatic diseases ,Antineoplastic Combined Chemotherapy Protocols ,Stage (cooking) ,Aged, 80 and over ,Hematology ,Antiviral therapy ,virus diseases ,General Medicine ,Hepatitis C ,Middle Aged ,Survival Rate ,Vincristine ,030220 oncology & carcinogenesis ,HCV ,RNA, Viral ,030211 gastroenterology & hepatology ,Rituximab ,Female ,Original Article ,Lymphoma, Large B-Cell, Diffuse ,medicine.drug ,Adult ,medicine.medical_specialty ,Antiviral Agents ,Disease-Free Survival ,03 medical and health sciences ,Internal medicine ,medicine ,Humans ,Cyclophosphamide ,Aged ,Diffuse large B cell lymphoma (DLBCL) ,Chemotherapy ,business.industry ,medicine.disease ,digestive system diseases ,Lymphoma ,Direct-acting antiviral agents (DAAs) ,Doxorubicin ,Immunology ,Prednisone ,business - Abstract
The purpose of this study is to study the usefulness of post-remission antiviral therapy in cases of HCV-RNA-positive diffuse large-cell lymphoma. Antiviral therapy against HCV was performed after remission using CHOP or CHOP-like chemotherapy in combination with rituximab in five successive cases of HCV-RNA-positive diffuse large-cell lymphoma. The control groups consisted of a group of HCV-RNA-positive diffuse large-cell lymphoma cases prior to this trial (control 1), and a group of cases that tested negative for HIV, HCV, and HBV (control 2). All the cases were in remission at the time of initial treatment. There were no significant differences between the three groups in terms of age, sex, treatment, stage, or International Prognosis Index (IPI). When HCV antiviral therapy was performed after treatment for diffuse large-cell lymphoma, we observed no recurrence or deaths, and the 2-year overall survival and progression-free survival rates were significantly greater than those in the control 1 group (P = 0.0246). It is possible that a better prognosis can be achieved by performing HCV antiviral therapy after achieving remission in cases of HCV-RNA-positive diffuse large-cell lymphoma through the use of R-CHOP or similar treatments.
- Published
- 2017
89. Cryptanalysis of Comparable Encryption in SIGMOD'16
- Author
-
Keita Xagawa, Ryo Kikuchi, and Caleb Horst
- Subjects
Theoretical computer science ,Plaintext-aware encryption ,Computer science ,Data_CODINGANDINFORMATIONTHEORY ,0102 computer and information sciences ,02 engineering and technology ,Security token ,Encryption ,01 natural sciences ,law.invention ,Watermarking attack ,Multiple encryption ,Filesystem-level encryption ,law ,020204 information systems ,Ciphertext ,0202 electrical engineering, electronic engineering, information engineering ,business.industry ,Adversary ,Deterministic encryption ,Ciphertext indistinguishability ,Symmetric-key algorithm ,010201 computation theory & mathematics ,Probabilistic encryption ,56-bit encryption ,40-bit encryption ,Attribute-based encryption ,Link encryption ,business ,Cryptanalysis ,Security parameter - Abstract
Comparable Encryption proposed by Furukawa (ESORICS 2013, CANS 2014) is a variant of order-preserving encryption (OPE) and order-revealing encryption (ORE); we cannot compare a ciphertext of v and another ciphertext of v', but we can compare a ciphertext of v and a token of b and compare a token of $b$ and another token of b'. Comparable encryption allows us to implement range and point queries while keeping the order of v's as secret as possible. Recently, Karras, Malhotra, Bhatt, Nikitin, Antyukhov, and Idreos independently re-define comparable encryption and propose two schemes, a basic one and an "ambiguous" one, based on linear algebra~(SIGMOD 2016). The basic scheme is just comparable encryption. To hide the order revealed by tokens, they also proposed an ambiguous scheme where each ciphertext has two interpretations v and vdummy. In the context of an indexed database, this means that every encryption has two places in the database corresponding to the two interpretations, masking the correct placement in the database unless the dummy value is detectable. They assessed that their basic scheme (and ambiguous scheme upon the basic scheme) is secure against known-plaintext attacks; the adversary will require O(l) plaintext-ciphertext pairs to recover secret key, where l is a security parameter. This paper cryptanalyzes their comparable encryption schemes by using simple linear algebra. We show that a few tokens and a few plaintext-ciphertext pairs instead of O(l) pairs allow us to mount several attacks efficiently. Our attacks are summarized as follows: Attacks against the basic scheme: -A ciphertext-only attack using two tokens orders the ciphertexts correctly. -A known-plaintext attack using two tokens and two plaintexts reveals exact value of v. Attacks against the ambiguous scheme: -A ciphertext-only attack using two tokens orders the ciphertexts with a constant probability. -A known-plaintext attack using three tokens and three plaintexts reveals exact value of v.
- Published
- 2017
90. Not Specific Cytokines but B Symptoms or C Reactive Proteins were Related the Infusion Reactions in Rituximab Treated B Cell Non-Hodgkin’s Lymphoma
- Author
-
Ryo Kikuchi, Shinichi Ito, Takanori Teshima, Satomi Matsuoka, and Yutaka Tsutsumi
- Subjects
medicine.medical_specialty ,Chemotherapy ,business.industry ,medicine.medical_treatment ,Follicular lymphoma ,medicine.disease ,Gastroenterology ,Lymphoma ,medicine.anatomical_structure ,B symptoms ,immune system diseases ,hemic and lymphatic diseases ,Internal medicine ,Immunology ,Prednisolone ,Medicine ,Rituximab ,medicine.symptom ,business ,Diffuse large B-cell lymphoma ,B cell ,medicine.drug - Abstract
Purpose: The purpose of this study is to analyze the risk factor for infusion related reaction (IRR) due to the rituximab treatment in patients with B cell non-Hodgkin’s lymphoma. Methods: A retrospective analysis was conducted the newly diagnosed B cell non-Hodgkin’s lymphoma patients who have received rituximab contained chemotherapy. Several factors with cytokines in patients were calculated. A P value
- Published
- 2017
91. APOLLON Protein Promotes Early Mitotic CYCLIN A Degradation Independent of the Spindle Assembly Checkpoint
- Author
-
Atsushi Kawabata, Hirokazu Ohata, Nobumichi Ohoka, Mikihiko Naito, and Ryo Kikuchi
- Subjects
Cyclin E ,biology ,Chemistry ,Cyclin D ,Cyclin A ,Cyclin B ,Cell Cycle Checkpoints ,Spindle Apparatus ,U937 Cells ,Cell Biology ,G2-M DNA damage checkpoint ,Biochemistry ,Inhibitor of Apoptosis Proteins ,Cell biology ,Proteolysis ,biology.protein ,Cyclin-dependent kinase complex ,Humans ,biological phenomena, cell phenomena, and immunity ,Anaphase-promoting complex ,Molecular Biology ,Cyclin A2 ,HeLa Cells - Abstract
In the mammalian cell cycle, both CYCLIN A and CYCLIN B are required for entry into mitosis, and their elimination is also essential to complete the process. During mitosis, CYCLIN A and CYCLIN B are ubiquitylated by the anaphase-promoting complex/cyclosome (APC/C) and then subjected to proteasomal degradation. However, CYCLIN A, but not CYCLIN B, begins to be degraded in the prometaphase when APC/C is inactivated by the spindle assembly checkpoint (SAC). Here, we show that APOLLON (also known as BRUCE or BIRC6) plays a role in SAC-independent degradation of CYCLIN A in early mitosis. APPOLON interacts with CYCLIN A that is not associated with cyclin-dependent kinases. APPOLON also interacts with APC/C, and it facilitates CYCLIN A ubiquitylation. In APPOLON-deficient cells, mitotic degradation of CYCLIN A is delayed, and the total, but not the cyclin-dependent kinase-bound, CYCLIN A level was increased. We propose APPOLON to be a novel regulator of mitotic CYCLIN A degradation independent of SAC.
- Published
- 2014
92. HCV in Lymphoid Neoplasms
- Author
-
Teshima T, Ryo Kikuchi, Yamamoto Y, Matsuoka S, Tsutsumi Y, Naruse H, and Shinichi Ito
- Subjects
business.industry ,Open access publishing ,Hepatitis C virus ,medicine ,Library science ,Rituximab ,Lymphoid neoplasms ,business ,medicine.disease_cause ,medicine.disease ,Virology ,medicine.drug ,Non-Hodgkin's lymphoma - Published
- 2016
93. Investigation of the dominant factors of the strength of a grain boundary in Ni-base superalloy using molecular dynamics analysis
- Author
-
Ken Suzuki, Wataru Suzuki, Ryo Kikuchi, and Hideo Miura
- Subjects
Superalloy ,Molecular dynamics ,Materials science ,Grain boundary ,Composite material ,Base (exponentiation) - Published
- 2019
94. Design Method for Controller Parameters using Support Vector Machine
- Author
-
Ryo Kikuchi, Toshiki Saitoh, and Takenori Atsumi
- Subjects
Support vector machine ,Computer science ,Control theory - Published
- 2019
95. F223 Performance measurements on a thermoacoustic heat pump
- Author
-
Yuki Ueda, Atsushi Akisawa, and Ryo Kikuchi
- Subjects
Materials science ,law ,Acoustics ,Thermoacoustic heat engine ,Heat pump ,law.invention - Published
- 2013
96. Evaluation of Secure Computation in a Distributed Healthcare Setting
- Author
-
Eizen, Kimura, Koki, Hamada, Ryo, Kikuchi, Koji, Chida, Kazuya, Okamoto, Shirou, Manabe, Tomohiko, Kuroda, Yasushi, Matsumura, Toshihiro, Takeda, and Naoki, Mihara
- Subjects
Health Information Exchange ,Software Design ,Humans ,Computer Security ,Confidentiality - Abstract
Issues related to ensuring patient privacy and data ownership in clinical repositories prevent the growth of translational research. Previous studies have used an aggregator agent to obscure clinical repositories from the data user, and to ensure the privacy of output using statistical disclosure control. However, there remain several issues that must be considered. One such issue is that a data breach may occur when multiple nodes conspire. Another is that the agent may eavesdrop on or leak a user's queries and their results. We have implemented a secure computing method so that the data used by each party can be kept confidential even if all of the other parties conspire to crack the data. We deployed our implementation at three geographically distributed nodes connected to a high-speed layer two network. The performance of our method, with respect to processing times, suggests suitability for practical use.
- Published
- 2016
97. How to Circumvent the Two-Ciphertext Lower Bound for Linear Garbling Schemes
- Author
-
Koutarou Suzuki, Ryo Kikuchi, and Carmen Kempka
- Subjects
NAND gate ,0102 computer and information sciences ,02 engineering and technology ,Function (mathematics) ,01 natural sciences ,Upper and lower bounds ,XNOR gate ,010201 computation theory & mathematics ,Proof of concept ,Ciphertext ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Algorithm ,Security parameter ,AND gate ,Mathematics - Abstract
At EUROCRYPT 2015, Zahur et al. argued that all linear, and thus, efficient, garbling schemes need at least two k-bit elements to garble an AND gate with security parameter k. We show how to circumvent this lower bound, and propose an efficient garbling scheme which requires less than two k-bit elements per AND gate for most circuit layouts. Our construction slightly deviates from the linear garbling model, and constitutes no contradiction to any claims in the lower-bound proof. With our proof of concept construction, we hope to spur new ideas for more practical garbling schemes. Our construction can directly be applied to semi-private function evaluation by garbling XOR, XNOR, NAND, OR, NOR and AND gates in the same way, and keeping the evaluator oblivious of the gate function.
- Published
- 2016
98. Pattern of population genetic structure revealed by nuclear simple sequence repeat markers in the understory perennialVeratrum albumssp.oxysepalum(Melanthiaceae) with a disjunct pattern of chloroplast DNA haplotypes
- Author
-
Jae-Hong Pak, Ryo Kikuchi, Masayuki Maki, and Hirosho Takahashi
- Subjects
education.field_of_study ,biology ,Ecology ,Population ,Disjunct distribution ,Disjunct ,biology.organism_classification ,Gene flow ,Phylogeography ,Melanthiaceae ,Evolutionary biology ,Genetic structure ,Genetic variation ,education ,Ecology, Evolution, Behavior and Systematics - Abstract
Compared to tree species, there still remains a very limited number of phylogeographical studies on temperate forest perennials. In the present study, we used nuclear microsatellite markers to detect extant patterns of population genetic structure of the perennial plant Veratrum album ssp. oxysepalum in the understory of temperate forests, aiming to provide insights into the post-glacial history of the species and the reasons for the disjunct distribution of chloroplast DNA (cpDNA) haplotypes found in a previous study. We examined eight polymorphic nuclear microsatellite loci to examine genetic variation within and among 32 populations of V. album ssp. oxysepalum and seven populations of Veratrum stamineum. The population of V. album ssp. oxysepalum was split into two groups: those in the northern part of the Japanese Archipelago and all others. In addition, each population group was split into two subgroups. Only one population of V. stamineum included a substantial number of individuals categorized as V. album ssp. oxysepalum. The population genetic structure revealed by nuclear microsatellites suggests that V. album ssp. oxysepalum migrated from Eurasia into the Japanese Archipelago at least twice before the last glacial era through two different land bridges: the Korean Peninsula and Sakhalin. In addition, there appeared to be at least two refugia of V. album ssp. oxysepalum in each of the areas, dominated by the two different lineages from Eurasia during the last glacial era. The disjunct geographical pattern found in cpDNA variation in a previous study was blurred in the genetic structure as revealed by microsatellite markers, probably as a result of extensive gene flow via pollen. Currently, one-directional introgressive hybridization occurs from V. album ssp. oxysepalum to V. stamineum at only one locality; there is no evidence of the opposite pattern. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 108, 278–293.
- Published
- 2012
99. Disjunct distribution of chloroplast DNA haplotypes in the understory perennial Veratrum album ssp. oxysepalum (Melanthiaceae) in Japan as a result of ancient introgression
- Author
-
Hiroshi Takahashi, Ryo Kikuchi, Masayuki Maki, and Pak Jae-Hong
- Subjects
Chloroplast capture ,Physiology ,Range (biology) ,DNA, Chloroplast ,Disjunct distribution ,Genetic Variation ,Introgression ,Plant Science ,Biology ,Disjunct ,Genes, Plant ,biology.organism_classification ,Biological Evolution ,Monophyly ,Melanthiaceae ,Haplotypes ,Japan ,Chloroplast DNA ,DNA, Ribosomal Spacer ,Botany ,Hybridization, Genetic ,Veratrum ,Ecosystem ,History, Ancient ,Phylogeny - Abstract
• The Quaternary climatic changes resulted in range shifts of species, providing chances for hybridization. However, the genetic signatures of such ancient introgression have rarely been reported. To investigate such signatures, we performed a phylogeographical study on the perennial plant Veratrum album ssp. oxysepalum, which may have hybridized long ago with another congeneric species, V. stamineum. • Sequence variations in chloroplast DNA (cpDNA) were examined in 43 populations in Japan and adjacent areas. Phylogenetic analyses of different cpDNA haplotypes were conducted on the basis of cpDNA and nuclear ribosomal internal transcribed spacer (nrITS) variations. • In the Japanese archipelago, two major groups of haplotypes were detected, one of which was distributed in a disjunct pattern. The major haplotype, occupying the central part of the species' distribution, formed a monophyletic group with V. stamineum in phylogenetic trees on the basis of cpDNA variation, although the two species did not form a monophyletic group in phylogenetic trees on the basis of nrITS variation. • Historical hybridization between V. album ssp. oxysepalum and V. stamineum in refugia during the Quaternary climatic oscillations, and the resulting chloroplast capture of V. stamineum by V. album ssp. oxysepalum, are most probably responsible for the disjunct distribution of cpDNA in V. album ssp. oxysepalum.
- Published
- 2010
100. Effect of the density of vacancies on the strength of grain boundaries in polycrystalline materials analyzed by molecular dynamics simulations
- Author
-
Ryo Kikuchi, Ken Suzuki, and Yiqing Fan
- Subjects
Molecular dynamics ,Materials science ,Condensed matter physics ,Grain boundary ,Crystallite - Published
- 2018
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