著者

IITAKA T.

雑誌

Nature

巻号頁・発行日

vol.430, pp.442-445, 2004

被引用文献数

2 220

著者

Duan Lian Hong Young-Joo Yasuno Yoshiaki

出版者

Optical Society of America

雑誌

Optics Express (ISSN:10944087)

巻号頁・発行日

vol.21, no.13, pp.15787-15808, 2013-06

被引用文献数

25

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An automated choroidal vessel segmentation and quantification method for high-penetration optical coherence tomography (OCT) was developed for advanced visualization and evaluation of the choroidal vasculature. This method uses scattering OCT volumes for the segmentation of choroidal vessels by using a multi-scale adaptive threshold. The segmented choroidal vessels are then processed by multi-scale morphological analysis to quantify the vessel diameters. The three-dimensional structure and the diameter distribution of the choroidal vasculature were then obtained. The usefulness of the method was then evaluated by analyzing the OCT volumes of normal subjects.

著者

Suzuki Jun Denning Daniel P Imanishi Eiichi Horvitz H Robert Nagata Shigekazu

出版者

American Association for the Advancement of Science

雑誌

Science (ISSN:00368075)

巻号頁・発行日

2013-07-11

被引用文献数

420

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アポトーシス時のリン脂質暴露に関与する因子の同定. 京都大学プレスリリース. 2013-07-12.

著者

Hara K. O. Usami N. Toh K. Baba M. Toko K. Suemasu T.

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.112, no.08, pp.083108, 2012-10

被引用文献数

83

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Excess-carrier recombination mechanisms in undoped BaSi2 epitaxial films grown by molecular beam epitaxy on n-type silicon substrates have been studied by the microwave-detected photoconductivity decay measurement. The measured excess-carrier decay is multiexponential, and we divided it into three parts in terms of the decay rate. Measurement with various excitation laser intensities indicates that initial rapid decay is due to Auger recombination, while the second decay mode with approximately constant decay to Shockley-Read-Hall recombination. Slow decay of the third decay mode is attributed to the carrier trapping effect. To analyze Shockley-Read-Hall recombination, the formulae are developed to calculate the effective lifetime (time constant of decay) from average carrier concentration. The measurement on the films with the thickness of 50–600 nm shows that the decay due to Shockley-Read-Hall recombination is the slower in the thicker films, which is consistent with the formulae. By fitting the calculated effective lifetime to experimental ones, the recombination probability is extracted. The recombination probability is found to be positively correlated with the full width at half-maximum of the X-ray rocking curves, suggesting that dislocations are acting as recombination centers.

著者

Ogawa Kyohei Nakamura Takashi Terada Yasuhiko Kose Katsumi Haishi Tomoyuki

出版者

American Institute of Physics

雑誌

Applied physics letters (ISSN:00036951)

巻号頁・発行日

vol.98, no.23, pp.234101, 2011-06

被引用文献数

81 12

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We have developed the first magnetic resonance (MR) microscope using a high critical-temperature superconducting bulk magnet. The bulk magnet comprises six annular bulk superconductors (60 mm outer diameter, 28 mm inner diameter, 20 mm high) made of c-axis oriented single-domain EuBa2Cu3Oy crystals. The magnet was energized using a superconducting NMR magnet operating at 4.7 T. The inhomogeneity of the trapped magnetic field measured with MR imaging was 3.1 ppm (rms) in the ϕ6.2 mm×9.1 mm cylindrical region. Three-dimensional MR images of a chemically fixed mouse embryo acquired with voxels of (50 μm)3 demonstrated the potential of our system.

著者

Unno Hiroshi Terauchi Tachio Kobayashi Naoki

出版者

ACM

雑誌

Proceeding POPL '13 Proceedings of the 40th annual ACM SIGPLAN-SIGACT symposium on Principles of programming languages

巻号頁・発行日

pp.75-86, 2013-01

被引用文献数

30

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We present an automated approach to relatively completely verifying safety (i.e., reachability) property of higher-order functional programs. Our contribution is two-fold. First, we extend the refinement type system framework employed in the recent work on (incomplete) automated higher-order verification by drawing on the classical work on relatively complete "Hoare logic like" program logic for higher-order procedural languages. Then, by adopting the recently proposed techniques for solving constraints over quantified first-order logic formulas, we develop an automated type inference method for the type system, thereby realizing an automated relatively complete verification of higher-order programs.

著者

Yukiko Hirabayashi Shinjiro Kanae

出版者

水文・水資源学会/日本地下水学会/日本水文科学会/陸水物理研究会

雑誌

Hydrological Research Letters (ISSN:18823416)

巻号頁・発行日

vol.3, pp.6-9, 2009 (Released:2009-01-29)

参考文献数

7

被引用文献数

23 58

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Flooding is one of the major risks anticipated to increase in association with anthropogenically induced climate change which is likely to intensify the global water cycle. Currently, 20 to 300 million people per year are affected by floods that threaten both social security and sustainable development. This study presents the first estimate of future populations at risk of flooding. Results indicate that in the case of 3°C warming from the average of 1980-1999, approximately 300 million people could be at risk even in years of relatively low flooding; this number corresponds to the number of people affected in a devastating flood year at present. If the temperature increase is greater than 3°C, the flood-affected population would likely be even larger. We suggest that approximately 2°C warming, rather than 3°C warming, should be considered the critical level of temperature increase.

著者

Shinohara Masanobu Io Katsuhiro Shindo Keisuke Matsui Masashi Sakamoto Takashi Tada Kohei Kobayashi Masayuki Kadowaki Norimitsu Takaori-Kondo Akifumi

出版者

Nature Publishing Group

雑誌

Scientific Reports (ISSN:20452322)

巻号頁・発行日

vol.2, 2012-11-13

被引用文献数

86

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新規発癌遺伝子アポベック3による新たな発癌機構. 京都大学プレスリリース. 2012-11-14.

著者

Okada Susumu Oshiyama Atsushi

出版者

American Physical Society

雑誌

Physical review letters (ISSN:00319007)

巻号頁・発行日

vol.87, no.14, pp.146803, 2001-09

被引用文献数

332

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We report first-principles total-energy electronic-structure calculations in the density-functional theory performed for hexagonally bonded honeycomb sheets consisting of B, N, and C atoms. We find that the ground state of BNC sheets with particular stoichiometry is ferromagnetic. Detailed analyses of energy bands and spin densities unequivocally reveal the nature of the ferromagnetic ordering, leading to an argument that the BNC sheet is a manifestation of the flat-band ferromagnetism.

著者

Narusaka Mari Kubo Yasuyuki Hatakeyama Katsunori Imamura Jun Ezura Hiroshi Nanasato Yoshihiko Tabei Yutaka Takano Yoshitaka

出版者

Public Library of Science

雑誌

PLoS ONE (ISSN:19326203)

巻号頁・発行日

vol.8, no.2, pp.e55954, 2013-02

被引用文献数

77 10

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A major class of disease resistance (R) genes which encode nucleotide binding and leucine rich repeat (NB-LRR) proteins have been used in traditional breeding programs for crop protection. However, it has been difficult to functionally transfer NB-LRR-type R genes in taxonomically distinct families. Here we demonstrate that a pair of Arabidopsis (Brassicaceae) NB-LRR-type R genes, RPS4 and RRS1, properly function in two other Brassicaceae, Brassica rapa and Brassica napus, but also in two Solanaceae, Nicotiana benthamiana and tomato (Solanum lycopersicum). The solanaceous plants transformed with RPS4/RRS1 confer bacterial effector-specific immunity responses. Furthermore, RPS4 and RRS1, which confer resistance to a fungal pathogen Colletotrichum higginsianum in Brassicaceae, also protect against Colletotrichum orbiculare in cucumber (Cucurbitaceae). Importantly, RPS4/RRS1 transgenic plants show no autoimmune phenotypes, indicating that the NB-LRR proteins are tightly regulated. The successful transfer of two R genes at the family level implies that the downstream components of R genes are highly conserved. The functional interfamily transfer of R genes can be a powerful strategy for providing resistance to a broad range of pathogens.

著者

Yamamoto Shinya Humle Tatyana Tanaka Masayuki

出版者

Public Library of Science

雑誌

PLoS ONE (ISSN:19326203)

巻号頁・発行日

vol.8, no.1, 2013-01-30

被引用文献数

56

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技を盗むチンパンジー : 効率のよい道具使用テクニックを他者から見て学ぶ--ヒト特有と考えられている累積進化文化の認知的基盤--. 京都大学プレスリリース. 2013-01-31.

著者

Uchida Eriko Mizuguchi Hiroyuki Ishii-Watabe Akiko HAYAKAWA Takao

出版者

公益社団法人日本薬学会

雑誌

Biological & pharmaceutical bulletin (ISSN:09186158)

巻号頁・発行日

vol.25, no.7, pp.891-897, 2002-07-01

被引用文献数

3 96

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Non-viral gene transfer into a wide range of human cells was examined in order to clarify the factors that affect the efficiency and safety of non-viral vectors and to optimize the conditions so that high efficiency and low toxicity could be achieved. Six non-viral vectors (Lipofectin, LipofectAMINE PLUS, SuperFect, Effectene, DMRIE-C and DOTAP) were used to transfect a mammalian expression plasmid pCMVβ into 16 types of human primary cells and cultured cell lines. Transfection efficiency was quantified using a galactosidase assay. Cytotoxic effects were measured by lactate dehydrogenase (LDH) assay and WST-8 assay. In serum-free conditions, LipofectAMINE PLUS, Effectene and SuperFect, on average, transfected DNA more successfully than Lipofectin, DMRIE-C, and DOTAP, although the levels of gene expression with these vectors varied remarkably in different cells. The most effective vector also differed depending on the cell type. Serum was found to inhibit gene transfer and reduce the cytotoxicity of all of these vectors except Effectene. The efficiency and toxicity of the non-viral vectors used depended on the type of vector, the DNA/vector ratio, the type of cell, and the presence of serum. These results provided useful information for the optimization of transfer conditions of these non-viral vectors.

著者

Ui Takashi

出版者

Academic Press Inc

雑誌

Games and Economic Behavior (ISSN:08998256)

巻号頁・発行日

vol.31, no.1, pp.121-135, 2000-04

被引用文献数

80

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In potential games, as considered by Monderer and Shapley (1996a, Games Econom. Behav. 14, 124-143), each player's gain from a deviation is equal to the gain in a potential function. We prove that a game has a potential function if and only if its payoff functions coincide with the Shapley value of a particular class of cooperative games indexed by the set of strategy profiles. Also a potential function of a noncooperative potential game coincides with the potentials (cf. Hart and Mas-Colell, 1989, Econometrica 57, 589-614) of cooperative games indexed by the strategy set. Journal of Economic Literature Classification Numbers: C71, C72. (C) 2000 Academic Press (C) 2000 Academic Press.

著者

Sugisaki Mitsuru Ren Hong-Wen Nair Selvakumar V. Nishi Kenichi Masumoto Yasuaki

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.66, no.23, pp.235309, 2002-12

被引用文献数

56 47

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The effects of external electric and magnetic fields on InP self-assembled quantum dots (QDs) were investigated by means of single dot spectroscopy. By systematically changing a bias applied to the sample, successive energy shifts of the photoluminescence (PL) peaks from excitons and biexcitons due to the quantum confined Stark effect were clearly observed. The quadratic Stark coefficient was evaluated to be of the order of 10-31 Fcm2. The energy separation of the PL peaks arising from the excitons and biexcitons changed with the applied electric field, reflecting a slight difference of the Stark coefficient between the exciton and biexciton states. The existence of permanent dipole moments was also revealed in both the exciton and biexciton states. The spatial separations between the electrons and holes along the growth direction in a QD were estimated to be 7 Å for the exciton state, and 8 Å for the biexciton state. Further, the diamagnetic shift and the Zeeman splitting of the exciton states were clearly observed in a magnetic field. It was found that the diamagnetic coefficient gradually decreases on decreasing the QD size. A simple qualitative model can explain that this result is due to competition between quantum confinement and magnetic confinement.

著者

Tomimoto Shinichi Kurokawa Atsushi Sakuma Yoshiki Usuki Tatsuya Masumoto Yasuaki

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.76, no.20, pp.205317, 2007-11

被引用文献数

14 10

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Recombination dynamics of excitons confined in disk-shaped InAs/InP quantum dots is studied by time-resolved photoluminescence measurements. By comparing the result with that in a homologous ultrathin quantum well, it is revealed that the lateral confinement of excitons suppresses the thermal variation of the radiative recombination lifetime. The oscillator strength of the radiative transition is reduced with the decrease of the disk height, which is attributed to the increasing tunneling into the InP barrier of the exciton wave function.

著者

Ryu S. Hatsugai Y.

出版者

American Physical Society

雑誌

Physical review B (ISSN:10980121)

巻号頁・発行日

vol.73, no.24, pp.245115, 2006-06

被引用文献数

134

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The entanglement entropy (von Neumann entropy) has been used to characterize the complexity of many-body ground states in strongly correlated systems. In this paper, we try to establish a connection between the lower bound of the von Neumann entropy and the Berry phase defined for quantum ground states. As an example, a family of translational invariant lattice free fermion systems with two bands separated by a finite gap is investigated. We argue that, for one-dimensional (1D) cases, when the Berry phase (Zak's phase) of the occupied band is equal to pi×(odd integer) and when the ground state respects a discrete unitary particle-hole symmetry (chiral symmetry), the entanglement entropy in the thermodynamic limit is at least larger than ln 2 (per boundary), i.e., the entanglement entropy that corresponds to a maximally entangled pair of two qubits. We also discuss how this lower bound is related to vanishing of the expectation value of a certain nonlocal operator which creates a kink in 1D systems.

著者

Matsuda Tadashi Sakakibara Jun

出版者

American Institute of Physics

雑誌

Physics of fluids (ISSN:10706631)

巻号頁・発行日

vol.17, no.2, pp.025106, 2005-01

被引用文献数

48 41

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Turbulent vortical structures in a round free jet of water were experimentally visualized by using stereo particle image velocimetry (PIV). A laser light sheet illuminated a cross-sectional plane normal to the axis of the jet, and two charge-coupled device cameras captured particle images in the same region of interest but from different directions. The stereo-PIV algorithm had been applied to obtain two-dimensional, three-component (2D-3C) velocity distributions on various cross-sectional planes along the axis downstream. All nine components of the velocity gradient tensor were reconstructed from time-dependent 2D-3C velocity data by locally assuming Taylor's frozen field hypothesis based on the convective velocity evaluated from the mean flow profile. Isosurfaces of the swirling strength lambdai revealed that the existence of a group of hairpinlike vortex structures was quite evident around the rim of the shear layer of the jet. The center of curvature of the head of the hairpin was typically observed around r/b = 1.5, and the azimuthal spacing between the legs of the hairpin was roughly 0.9b. A similar hairpin structure was estimated by linear stochastic estimation. The typical spacing between the legs of the estimated hairpin was 0.65b, which is generally constant over the range of Re = 1500–5000.

著者

Hattori Toshiaki

出版者

American Institute of Physics

雑誌

The journal of chemical physics (ISSN:00219606)

巻号頁・発行日

vol.133, no.20, pp.204503, 2010-11

被引用文献数

9

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A general theoretical framework of two-dimensional time-domain second-order and third-order terahertz spectroscopy has been presented. The theoretical treatment is based on a classical and phenomenological model with weak nonlinearities. Three types of nonlinearity sources, anharmonicity, nonlinear coupling, and nonlinear damping, were considered. The second-order THz spectroscopy has an exact correspondence to fifth-order off-resonance Raman spectroscopy, and it has been shown that the present treatment gives exactly the same results as of the quantum mechanical theory under the weak nonlinearity condition. General expressions for the nonlinear signal have been obtained for a single-mode system, and numerical calculations for delta-function incident terahertz pulses were shown. For the third-order signal, two-level systems were also considered for comparison. Contributions of two types of incident pulse sequences have been studied separately in the third-order signals. Profiles of the two-dimensional signals were found to depend on the origin and order of the nonlinearity and also on the pulse sequence. The results of the present study show that the two-dimensional signal features of second- and third-order nonlinear terahertz spectroscopy can clarify the nature of the system which is not accessible using linear spectroscopy.

著者

Tsai Melody Ohniwa Ryosuke L Kato Yusuke Takeshita Sayaka L Ohta Toshiko Saito Shinji Hayashi Hideo Morikawa Kazuya

出版者

BioMed Central

雑誌

BMC microbiology (ISSN:14712180)

巻号頁・発行日

vol.11, pp.13, 2011-01

被引用文献数

99 26

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BackgroundThe ability of staphylococci to grow in a wide range of salt concentrations is well documented. In this study, we aimed to clarify the role of cardiolipin (CL) in the adaptation of Staphylococcus aureus to high salinity.ResultsUsing an improved extraction method, the analysis of phospholipid composition suggested that CL levels increased slightly toward stationary phase, but that this was not induced by high salinity. Deletion of the two CL synthase genes, SA1155 (cls1) and SA1891 (cls2), abolished CL synthesis. The cls2 gene encoded the dominant CL synthase. In a cls2 deletion mutant, Cls1 functioned under stress conditions, including high salinity. Using these mutants, CL was shown to be unnecessary for growth in either basal or high-salt conditions, but it was critical for prolonged survival in high-salt conditions and for generation of the L-form.ConclusionsCL is not essential for S. aureus growth under conditions of high salinity, but is necessary for survival under prolonged high-salt stress and for the generation of L-form variants.

著者

Ishizuka Shogo Yamada Akimasa Islam Muhammad Monirul Shibata Hajime Fons Paul Sakurai Takeaki Akimoto Katsuhiro Niki Shigeru

出版者

American Institute of Physics

雑誌

Journal of applied physics (ISSN:00218979)

巻号頁・発行日

vol.106, no.3, pp.034908, 2009-08

被引用文献数

143 57

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The systematic variations in the structural, optical, and electrical properties of polycrystalline Cu(In,Ga)Se2 (CIGS) thin films with Na doping level were investigated. Precise control of the Na concentration in CIGS films was demonstrated using alkali-silicate glass thin layers of various thicknesses deposited on substrates prior to CIGS growth. The CIGS grain size was observed to decrease with increasing Na concentration, although the surface morphology became smoother and exhibited a stronger (112) texture, which has been demonstrated consequence of larger grain size. The Ga composition gradient in the CIGS films was found to become large due to the presence of Na during growth, which in turn led to a decrease in the nominal band gap energy. Variations in the photoluminescence spectra and electrical properties suggested that the formation of an acceptor energy state, which may originate from OSe point defects, was enhanced in the presence of Na. This result suggests that not only Na, but also the presence of O in combination with Na contributes to the compensation of point defects and enhances p-type conductivity in CIGS films.