Hiroshi Takuma

University of Tsukuba

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Co-Authors

Kazuko Shimizu

University of Electro-Communications

Fujio Shimizu

University of Electro-Communications

Ken‐ichi Ueda

University of Electro-Communications

H. Nishioka

University of Electro-Communications

Akira Sasaki

National Institutes for Quantum and Radiological Science and Technology

K. Ueda

Waseda University

Akira Tamaoka

University of Tsukuba

Kenichi Ueda

University of Iowa

K. Hakuta

University of Electro-Communications

Takami Tomiyama

Teijin (Japan)

Cooperative Institutions

The University of Tokyo

113

Osaka University

104

Kyoto University

University of Electro-Communications

Japan Science and Technology Agency

Japan Atomic Energy Agency

Osaka City University

Tohoku University

Advanced Science Research Center

University of Tsukuba

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Single-shot UV autocorrelator that uses a two-photon-induced photoacoustic signal in water

Optics Letters (1993)

H. Nishioka M. Ishiguro T. Kawasumi Ken‐ichi Ueda Hiroshi Takuma

A single-shot autocorrelation of an ultrashort UV pulse is measured by detecting a two-photon-induced photoacoustic signal in water. A supersonic wave representing the autocorrelation function is detected by a polyvinylidene fluoride piezoelectric film with a spatial resolution of less than 60 microm. The detection sensitivity is higher than that of a multiphoton-induced fluorescence method by approximately 2 orders of magnitude.

Autocorrelator

SIGNAL (programming language)

Photoacoustic Spectroscopy

10.1364/ol.18.000045

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Citations (9)

Amyloid-β E22Δ variant induces synaptic alteration in mouse hippocampal slices

Neuroreport (2008)

Hiroshi Takuma Rie Teraoka Hiroshi Mori Takami Tomiyama

We recently identified a novel amyloid precursor protein mutation (E693Δ) in familial Alzheimer's-type dementia. This mutation produces amyloid-β (Aβ) variant lacking glutamate-22 (E22Δ), which showed enhanced oligomerization but no fibrillization. Here, we examined in-vitro toxicity of Aβ E22Δ peptide. Wild-type Aβ1-42 showed a dose-dependent (1 nM to 1 μM) cytotoxicity to cultured neuronal cells in the 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide assay, whereas Aβ1-42 E22Δ was toxic only weakly at 1 μM. In mouse hippocampal slices, however, Aβ1-42 E22Δ caused a dose-dependent (0.1–10 μM) decrease of synaptophysin, whereas wild-type Aβ1-42 was trophic at 0.1–1 μM and toxic at 10 μM. These results suggest that extracellular Aβ E22Δ causes more potent synaptic alteration, but lower neurodegeneration, than wild-type Aβ probably because of its unique aggregation property.

Synaptophysin

Amyloid (mycology)

Neurotoxicity

Neurotoxin

10.1097/wnr.0b013e3282fb78c4

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Citations (30)

Cold-electron production for optical-field ionization x-ray lasers using mixed gases

Physical Review A (1997)

Keisuke Nagashima T. Matoba Hiroshi Takuma

The use of mixed gases of working atoms with a much higher density of hydrogen has been proposed in recombination type x-ray lasers excited by high-intensity ultrashort pulse lasers. Hydrogen was chosen as the most suitable material to supply low-energy electrons in the optical-field ionization. Numerical analysis shows that a maximum gain can be expected for lithiumlike neon at a relatively low neon density of $9\ifmmode\times\else\texttimes\fi{}{10}^{17}{\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ with 60 times higher hydrogen density.

10.1103/physreva.56.5183

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Citations (2)

High-energy flashlamp-pumped Ti:sapphire laser for Yb:glass chirped-pulse amplification

Akihiko Nishimura Akira Ohzu A. Sugiyama Yoichiro Maruyama Takasi Arisawa

Summary form only given. A new flashlamp-pumped Ti:sapphire laser has been demonstrated for further high-energy Yb:glass chirped pulse amplification (CPA) experiments. The pulse energies of 6.5 J at 800 nm were obtained by from a flashlamp pumped Ti:sapphire laser in a system optimized for short-pulse discharge.

Chirped pulse amplification

Ti:sapphire laser

10.1109/cleo.1998.676020

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Time Dependent Fluorescence Spectrum of an e-Beam Pumped KrF Laser Medium in a High Current Density Range

Japanese Journal of Applied Physics (1980)

Hideo Hara Nobuhiko Umezu Kazuko Umezu Hiroshi Takuma Susumu Namba

Parametric dependence of the time dependent fluorescence spectrum of an e-beam pumped KrF laser medium was investigated in a high current density range of 120 to 250 A/cm 2 . Higher optimum pressure and shorter pulse duration were the prominent features. The results were fitted with a proposed rate equation model, indicating that the high current density e-beam pumping is favorable for high efficiency laser operation mainly because of a great deal of reduction of the three body quenching rate at higher temperature. A possibility of generating 25m J/cm 3 of 250 nm photons with an efficiency of 8% was predicted.

Rate equation

10.1143/jjap.19.l241

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TDP-43 M337V Mutation in Familial Amyotrophic Lateral Sclerosis in Japan

Internal Medicine (2010)

Akira Tamaoka Makoto Arai Masanari Itokawa Tetsuaki Arai Masato Hasegawa

The clinical features of a Japanese family with autosomal dominant adult-onset amyotrophic lateral sclerosis (ALS) are reported. Weakness initially affected the bulbar musculature, with later involvement of the extremities. Genetic studies failed to detect any mutations of the Cu/Zn superoxide dismutase-1 (SOD1) and Dynactin1 (DCTN1) genes, but revealed a single base pair change from wild-type adenine to guanine at position 1009 in TAR-DNA-binding protein (TDP-43), resulting in a methionine-to-valine substitution at position 337. The immunohistochemical study on autopsied brain of the proband's aunt showed TDP-43-positive cytoplasmic inclusions in the anterior horn cells of the spinal cord and in the hypoglossal nucleus, as well as glial cytoplasmic inclusions in the precentral gyrus, suggesting that a neuroglial proteinopathy was related to TDP-43. In conclusion, a characteristic clinical phenotype of familial ALS with initial bulbar symptoms occurred in this family with TDP-43 M337V substitution, the pathomechanism of which should be elucidated.

Proband

C9ORF72

10.2169/internalmedicine.49.2915

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Citations (47)

Pulsed relativistic electron beam of 3 ns produced by a velvet cathode

Review of Scientific Instruments (1991)

Qi Zhang Da Xing Ken-ichi Ueda Ken-ichi Ueda Hiroshi Takuma

A pulsed relativistic electron beam with a 3 ns duration was produced using Febetron 706 and electron beam tube with velvet cathode. Cathode current density of 7 kA/cm2 and lifetime of longer than 1000 shots were obtained.

Relativistic electron beam

Velvet

Vacuum tube

10.1063/1.1142530

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Citations (7)

All-Fiber Linearly-Polarized Yb-doped Fiber Laser yielding 2.2-W Green Second Harmonics

A. Shirakawa Kenji Hiwada Shota Hasegawa K. Ueda Hiroshi Takuma

Linearly-polarized, 12-W Yb-doped double-clad fiber laser has been constructed by use of polarization-maintaining fibers and an in-line polarizer. 2.2-W green light was also obtained by second harmonic generation in a periodically-poled MgO:LiNbO 3 .

Polarizer

10.1109/cleopr.2005.1569457

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Citations (7)

Comparison of Ne20, Ne22, and Ne21 laser traps

Fujio Shimizu Kazuko Shimizu Hiroshi Takuma

The laser cooling and trapping of Ne20 (Ref. 1) and Ne21 are expected to show considerably different characteristics because of the existence of the hyperfine structure for Ne21 and the difference in the statistics between two species. Although the natural abundance of Ne21 is only 0.257%, a highly efficient trapping technique we have developed has enabled us to trap visually observable numbers of Ne21 and to study the characteristics.

Trap (plumbing)

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Laser cooling and trapping of Ne metastable atoms

Physical review. A, General physics (1989)

Fujio Shimizu Kazuko Shimizu Hiroshi Takuma

A neon atomic beam in the metastable state 1${s}_{5}$ has been decelerated and trapped by the spontaneous light force of a resonant laser in a quadrupole magnetic field. Trapping has been achieved on all isotopes $^{20}\mathrm{Ne}$, $^{21}\mathrm{Ne}$, and $^{22}\mathrm{Ne}$ using a sample with natural abundance. For $^{20}\mathrm{Ne}$, approximately 4\ifmmode\times\else\texttimes\fi{}${10}^{7}$ atoms are trapped.

Metastability

Atomic beam

10.1103/physreva.39.2758

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Citations (62)