Search

Your search keyword '"Asakawa, Makoto"' showing total 159 results
Start Over Author "Asakawa, Makoto"
159 results on '"Asakawa, Makoto"'

2. Accurate Phase Calibration of Multistatic Imaging System for Medical and Industrial Applications.

Author

Tabata, Hiroshi, Asakawa, Makoto R., and Yamaguchi, Soichiro

Subjects
MICROWAVE imaging, IMAGING systems, ANTENNAS (Electronics), REFLECTANCE, INDUSTRIALISM
Abstract

Multistatic imaging systems are commonly used in radar systems and microwave imaging. In these systems, many antennas are arranged three-dimensionally and connected to RF switches. The length of each transmitter (Tx) and receiver (Rx) channel differs slightly, causing artifacts in high-resolution image reconstruction. This study presents a novel method for the phase calibration of multistatic systems. This method does not require system reconstruction and can automatically perform phase calibration in a short time. This method is expected to facilitate an accurate phase measurement in multistatic systems. The approach involves phase calibration by analyzing the reflection coefficients of antenna elements in the time domain. Imaging experiments were performed on a multistatic imaging system using this calibration method, and the position and shape of a metal rod with a diameter one-fourth of a wavelength were reconstructed by simple back-projection with an accuracy beyond the diffraction limit. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

3. Ablation phenomena by intense terahertz vortex beam

Author

Wang, You Wei, Segawa, Sadashi, Shimizu, Tomoki, Agulto, Verdad C., Mag-usara, Valynn Katrine, Kato, Kosaku, Miyamoto, Katsuhiko, Omatsu, Takashige, Makino, Kotaro, Tominaga, Junji, Isoyama, Goro, Asakawa, Makoto, and Nakajima, Makoto

Published
2022
Full Text
View/download PDF

6. Association between preoperative characteristics and risk of anaesthesia-related death in dogs in small-animal referral hospitals in Japan

Author

Itami, Takaharu, Aida, Hiroko, Asakawa, Makoto, Fujii, Yoko, Iizuka, Tomoya, Imai, Ayako, Iseri, Toshie, Ishizuka, Tomohito, Kakishima, Kei, Kamata, Masatoshi, Miyabe-Nishiwaki, Takako, Nagahama, Shotaro, Naganobu, Kiyokazu, Nishimura, Ryohei, Okano, Shozo, Sano, Tadashi, Yamashita, Kazuto, Yamaya, Yoshiki, and Yanagawa, Masashi

Published
2017
Full Text
View/download PDF

9. Generation of a Sub-Picosecond Sheet Electron Beam Using a 100 fs Laser

Author

Yoshimatsu,Shizuki, Matsubara,Hiroki, Michishita,Ryosuke, Asakawa,Makoto, Shirai,Tomohiro, Nakajima,Makoto, Horii,Ryosuke, Miyajima,Yuki, Karaki,Yuga, and Yamaguchi,Soichiro

Subjects
electron-sources - Electron sources, Accelerator Physics
Abstract

The biggest benefit of DC photoelectron-gun driven by the sub-picosecond laser is that such type of guns can be operated with the current density much higher than the Child’s low limitation. We demonstrated 0.3 nC bunch generation by irradiating a 100 fs Ti:sapphire laser focused to 0.1 square-cm area onto a tangsten photocathode installed in a diode type 40 kV DC gun. The drawback is the strong Coulomb repulsive force by which electrons may suffer the emittance degradation in the vicinity of the cathode. To reduce the repulsive force at the cathode surface, we are trying to generate a “sheet-like” photoelectron bunch. In our experiments, electron bunches are generated by irradiating the laser pulse shaped in an ellipse onto the photocathode. The ellipticity is set in the range of 0.03-0.05 while the most of sheet-beam experiments were conducted with the ellipticity about 0.1. The smaller the ellipcity, the longer the circumference; this may reduce the radial electric field on the electron bunch side-wall. Moreover the electron bunch shape is rather a “line” than a “sheet” due to the short duration of the drive laser pulse. We conducted a preliminaly experiment and observed that the elliptical photo-electron bunch had much larger divergence angle in the minor axis direction. In the presentation, experimental results, the numerical simulation on the particle motion and the design of the sheet-photo-electron DC gun will be discussed.

Published
2023
Full Text
View/download PDF

13. Laser-Induced Periodic Surface Structures on Ge2Sb2Te5 Irradiated by Terahertz Free-Electron Laser Vortex Beam

Author

Wang, Youwei, primary, Segawa, Sadashi, additional, Shimizu, Tomoki, additional, Ota, Masato, additional, Agulto, Verdad C., additional, Mag-Usara, Valynn Katrine, additional, Miyamoto, Katsuhiko, additional, Omatsu, Takashige, additional, Makino, Kotaro, additional, Tominaga, Junji, additional, Isoyama, Goro, additional, Asakawa, Makoto, additional, and Nakajima, Makoto, additional

Published
2022
Full Text
View/download PDF

17. Spintronic Terahertz Emission and Magnetic Anisotropy of Epitaxial Platinum Heterostructures on MgO(110) Substrate

Author

Tetsukawa, Shoei, primary, Liu, Shuang, additional, Mag-Usara, Valynn Katrine, additional, Agulto, Verdad Canila, additional, Kohda, Makoto, additional, Thompson, Ryan, additional, Gamou, Hiromu, additional, Du, Ye, additional, Karube, Shutaro, additional, Nitta, Junsaku, additional, Tani, Masahiko, additional, Asakawa, Makoto, additional, and Nakajima, Makoto, additional

Published
2021
Full Text
View/download PDF

19. Analysis of Mixed State of AP/HTPB Composite Propellant by X-ray Computed Tomography

Author

Asakawa, Makoto R., Hosomi, Naomasa, Otake, Kana, Uegaki, Natsuyo, Iwasaki, Akihiro, Matsumoto, Kotaro, Habu, Hiroto, and Yamaguchi, Soichiro

Subjects
Propellant, X-ray CT, Materials science, X ray computed, Particle Dispersion, Composite number, Composite Propellant, State (functional analysis), Tomography, Mixed Degree, Composite material
Abstract

Accepted: 2017-12-12, 資料番号: SA1180317000

Published
2019
Full Text
View/download PDF

29. Smith-Purcell Radiation Emitted by Pico-second Electron Bunches from a 30 keV Photo-Electron Gun

Author

Asakawa, Makoto and Yamaguchi, Soichiro

Subjects
Physics::Optics, Physics::Accelerator Physics, FEL Oscillators and Long Wavelengths FEL, Accelerator Physics
Abstract

In this paper, an experiment to generate Smith-Purcell radiation using pico-second electron bunches is reported. The electron bunch was produced by a DC 30 keV photo-electron electron gun driven by a 100 fs Ti:sapphire laser. The charge of the bunch varied from 1 pC to 300 pC by changing the laser power. Smith-Purcell radiation experiment was performed with the central part of the entire electron bunch. Estimation of pulsewidth of the bunch based on the envelope equation showed that the pulsewidth of the bunch at the anode electrode increased from 0.8 ps to 3.2 ps as the bunch charge increase from 0.1 pC to 11 pC. Such electron bunch was traveled along the surface of the metallic grating with a period of 2 mm. The radiation wavelength was estimated to be 4 mm at an obserbation angle of 10 degree. The radiation power was measured by a bolometer and quadraticallly increased with the bunch charge. Numerical simulation of this experiment indicated the enhancement of the harmonic components of the radiation. We are now constructing a THz-TDS system to measure the time-trace of the electric field of the radiation., Proceedings of the 39th Free Electron Laser Conference, FEL2019, Hamburg, Germany

Published
2019
Full Text
View/download PDF

35. The Current Status of the J-KAREN Laser Upgrade

Author

Kiriyama, Hiromitsu, primary, Kando, Masaki, additional, Pirozhkov, Alexander S., additional, Kishimoto, Maki, additional, Kon, Akira, additional, Nishiuchi, Mamiko, additional, Sakaki, Hironao, additional, Ogura, Koichi, additional, Kanasaki, Masato, additional, Tanaka, Hirotaka, additional, Fukuda, Yuji, additional, Mori, Michiaki, additional, Mashiba, Yuji, additional, Asakawa, Makoto R., additional, Sagisaka, Akito, additional, Koga, James, additional, Esirekepov, Timur Zh., additional, Hayashi, Yukio, additional, Kotaki, Hideyuki, additional, Miyasaka, Yasuhiro, additional, Sekiguchi, Kentaro, additional, Bulanov, Sergei V., additional, and Kondo, Kiminori, additional

Published
2016
Full Text
View/download PDF

36. Recent Advances on the J-KAREN laser upgrade

Author

Kiriyama, Hiromitsu, primary, Mori, Michiaki, additional, Pirozhkov, Alexander S., additional, Ogura, Koichi, additional, Nishiuchi, Mamiko, additional, Kando, Masaki, additional, Sakaki, Hironao, additional, Kon, Akira, additional, Kanasaki, Masato, additional, Tanaka, Hirotaka, additional, Fukuda, Yuji, additional, Koga, James, additional, Sagisaka, Akito, additional, Esirkepov, Timur Zh., additional, Hayashi, Yukio, additional, Kotaki, Hideyuki, additional, Bulanov, Sergei V., additional, Kondo, Kiminori, additional, Bolton, Paul R., additional, Mashiba, Yuji, additional, Asakawa, Makoto R., additional, Slezak, Ondrej, additional, Vojna, David, additional, Sawicka-Chyla, Magda, additional, Jambunathan, Venkatesan, additional, Lucianetti, Antonio, additional, and Mocek, Tomas, additional

Published
2015
Full Text
View/download PDF

38. Development of Compton X-Ray Spectrometer for Fast Ignition Experiment

Author

KOJIMA, Sadaoki, ARIKAWA, Yasunobu, IKENOUCHI, Takahito, NAGAI, Takahiro, ABE, Yuki, SAKATA, Shohei, INOUE, Hiroaki, NAMIMOTO, Takuya, FUJIOKA, Shinsuke, NAKAI, Mitsuo, SHIRAGA, Hiroyuki, GEKKO-XII&LFEX Team, OZAKI, Tetsuo, ASAKAWA, Makoto R., KATO, Ryukou, and AZECHI, Hiroshi

Subjects
filter stack spectrometer, fast electron, inertial confinement fusion, fast ignition, x-ray spectrometer
Abstract

In the context of Fast Ignition, the fast electron temperature is a key parameter to determine the laser-to-fast electron energy conversion efficiency. Bremsstrahlung X-ray (γ-ray) emission represents an attractive alternative to measure this fundamental parameter. In this study, a single-shot high-energy γ-ray spectrometer with sensitivity ranging from 0.5 MeV to 7 MeV was developed, allowing to estimate the γ-ray spectrum in the fast ignition.

Published
2014
Full Text
View/download PDF

40. Green Fluorescent Protein Gene Insertion of Sendai Virus Infection in Nude Mice: Possibility as an Infection Tracer

Author

Agungpriyono, Dewi Ratih, Yamaguchi, Ryoji, Uchida, Kazuyuki, Tohya, Yukinobu, Kato, Atsushi, Nagai, Yoshiyuki, Asakawa, Makoto, Tateyama, Susumu, 山口, 良二, 内田, 和幸, 遠矢, 幸伸, 加藤, 篤, 永井, 美之, 浅河, 誠, 立山, 晉, ヤマグチ, リョウジ, ウチダ, カズユキ, トオヤ, ユキノブ, カトウ, アツシ, ナガイ, ヨシユキ, アサカワ, マコト, タテヤマ, ススム, Agungpriyono, Dewi Ratih, Yamaguchi, Ryoji, Uchida, Kazuyuki, Tohya, Yukinobu, Kato, Atsushi, Nagai, Yoshiyuki, Asakawa, Makoto, Tateyama, Susumu, 山口, 良二, 内田, 和幸, 遠矢, 幸伸, 加藤, 篤, 永井, 美之, 浅河, 誠, 立山, 晉, ヤマグチ, リョウジ, ウチダ, カズユキ, トオヤ, ユキノブ, カトウ, アツシ, ナガイ, ヨシユキ, アサカワ, マコト, and タテヤマ, ススム

Abstract

The green fluorescent protein(GFP)marker from jellyfish Aequorea victoria is considered to have potential use in the study of host-pathogen relationships, by tracing infections in living cells, organs and animals.We compared the pathogenicity of Sendai virus with an inserted GFP gene(GFP-SeV)with that of its wild-type(Wt-SeV)to determine the usefulness of the recombinant virus in long-term infection of BALB / c nude(nu / nu)mice.The results indicated that the presence of GFP in infected cells could be analyzed easily and sensitively.GFP helped in identifying and in understanding the cellular sites of viral replication in vitro and in vivo.However, the GFP insertion into the Wt-SeV genome, led to decreased pathogenicity, altering the in vivo viral kinetics., オワングゲラAequorea victoria由来緑色蛍光タンパク質(GFP)は, 生細胞, 器官, 動物の感染実験において, 宿主と病原体の関係を研究するうえで有用であると考えられている.今回, BALB / c(nu / nu)ヌードマウスにおける長期感染実験における有用性を検討する目的で, GFP遺伝子を挿入したセンダイウイルスと親株の病原性を比較した.検索の結果, 感染細胞におけるGFPの局在は簡便かつ高感度で解析できることが示された.GFPはin vitroおよびin vivoにおいて, 細胞内でのウイルス増殖部位の同定や解析に有用であった.しかしながら, 親株へのGFP遺伝子挿入は病原性の低下をまねき, その結果in vivoにおけるウイルス動態の変化がもたらされたと考えられた.

Published
2008

44. Charcot–Leyden crystals: do they exist in veterinary species? A case report and literature review

Author

Choi, Eunju, Miller, Andrew D., Devenish, Elizabeth, Asakawa, Makoto, McConkey, Marina, and Peters-Kennedy, Jeanine

Abstract

The Charcot–Leyden crystal (CLC) is a major human eosinophil protein that readily crystallizes; these crystals are common in eosinophilic diseases. Although anecdotal existence of these crystals is known in veterinary pathology, definitive reports do not exist, to our knowledge. We identified eosinophilic crystals in a laryngeal myxosarcoma from a 2-y-old, spayed female, Labrador Retriever dog that were tentatively interpreted as CLCs. However, Ziehl–Neelsen acid-fast stain was negative, arguing against CLCs. The crystals stained red with Masson trichrome, precluding collagen. Periodic acid–Schiff and alcian blue were negative. The crystals stained positively with Okajima, and no myoglobin immunoreactivity was detected, supporting their identity as hemoglobin crystals. In the absence of a hematologic abnormality, these crystals were interpreted to be abnormal hemoglobin breakdown products. Protein sequence comparison was pursued to determine whether a protein similar to CLC exists in mammals. Only 3 nonhuman primate species, the Sumatran orangutan (Pongo abelii), rhesus macaque (Macaca mulatta), and cynomolgus monkey (Macaca fascicularis), had a sequence similarity of >80%. Of the crystal-forming residues, 12 of 54 (22%) were different in the Sumatran orangutan and 15 of 54 (28%) were different in the Macacaspp., which may affect the crystallization process. The lack of reports of CLCs in nonhuman species and our results collectively suggest that CLCs are human-specific.

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results