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Experimental and theoretical studies on nonlinear propagation of a-few-optical-cycle pulses in a photoniccrystal fiber -beyond the slowly-varying-envelope approximation-

Experimental and theoretical studies on nonlinear propagatio...

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International Conference on Ultrafast Phenomena, UP 2002

作者： Fang, Xiaojun Hirasawa, Masakatsu Morita, Ryuji Yamashita, Mikio Windeler, Robert S. Department of Applied Physics Hokkaido University Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Kita-13 Nishi-8 Kita-ku Sapporo060-8628 Japan Bell Laboratories Lucent Technologies 700 Mountain Avenue Murray HillNJ070974 United States

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Bayesian on-line learning: a sequential Monte Carlo with Rao-Blackwellization

Bayesian on-line learning: a sequential Monte Carlo with Rao...

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IEEE Workshop on Neural Networks for Signal Processing

作者： K. Yosui T. Kurihara K. Wada T. Souma T. Matsumoto The Core Research for Evolutional Science and Technology Japan Science and Technology Agency-CREST Japan Department of Electrical Waseda University Shinjuku Tokyo Japan

ISBN: (纸本)0780376161

This paper proposes a Rao-Blackwellised sequential Monte Carlo (RBSMC) scheme for on-line learning with feedforward neural nets. The proposed algorithm is tested against an example and the performance is compared with those of the conventional sequential Monte Carlo as well as the extended Kalman filter (EKF). The proposed scheme outperforms those conventional algorithms.

关键词： Bayesian methods Monte Carlo methods Sampling methods Nonlinear filters Feeds Neural networks Sequential analysis Kalman filters Training data Uncertainty

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Recent progress of semiconductor photonic crystals

Recent progress of semiconductor photonic crystals

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IEEE Conference on Nanotechnology

作者： M. Imada S. Noda Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation (JST) Kyoto Japan Department of Electronic Science and Engineering Kyoto University Kyoto Japan

Recent progresses in the field of semiconductor photonic crystals, including three-dimensional and two-dimensional photonic crystals are presented. First, the fabrication of three-dimensional photonic crystals is reviewed and experimental results on the introduction of the light emitter into three-dimensional crystals are reported. Second, two unique devices using two-dimensional photonic crystals, surface-emitting-type single-defect channel-drop filters and photonic crystal lasers are presented.

关键词： Photonic crystals Surface emitting lasers Optical filters Optical device fabrication Light emitting diodes Crystallization Photonic band gap Optical control Optical waveguides Optical surface waves

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Lipocalin-type prostaglandin D synthase in cerebrospinal fluid of patients with aneurysmal subarachnoid hemorrhage scavenges bile pigments

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International Congress Series 2002年第C期1233卷 447-451页

作者： Inui, Takashi Mase, Mitsuhito Emi, Maiko Nakau, Hiroya Seiki, Kousuke Oda, Hiroshi Yamada, Kazuo Urade, Yoshihiro Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Japan Department of Molecular Behavioral Biology Osaka Bioscience institute Suita Osaka 565-0874 6-2-4 Furuedai Japan Department of Neurosurgery Nagoya City University Medical School Nagoya 467-8602 Japan Department of Biological Chemistry Central Research institute Maruha Corporation Tsukuba 300-4295 Japan

Lipocalin-type prostaglandin D synthase (L-PGDS) is one of the major proteins in human cerebrospinal fluid (CSF) and binds various small lipophilic substances, such as bilirubin and biliverdin. The L-PGDS concentration increased in the CSF of patients with aneurysmal subarachnoid hemorrhage (SAH) from day 1 (10.5 μg/ml) to day 5 (25.6) and returned to the basal level after 2 months (12.9). L-PGDS purified from the CSF of SAH patients showed an absorbance spectrum with a peak at 392 nm in the visible range. The absorbance at 392 nm of the purified L-PGDS increased from day 1 (0.16/mg protein) to day 5 (0.44) and almost disappeared 2 months after SAH (0.11). Conversely, the enzyme activity of the purified L-PGDS decreased from day 1 (0.71 μmol/min/mg protein) to day 5 (0.28) and recovered 2 months after SAH (0.76). These results indicate that L-PGDS binds and scavenges bile pigments that accumulate in the CSF after SAH. © 2002 Elsevier science B.V.

关键词： Bile pigments Cerebrospinal fluid Lipocalin superfamily Prostaglandin D synthase Subarachnoid hemorrhage

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Enzymatic formation of prostaglandin D₂, E₂, and F_2α in the parasitic protozoan Trypanosoma brucei

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International Congress Series 2002年第C期1233卷 461-466页

作者： Kubata, Bruno Kilunga Duszenko, Michael Kabututu, Zakayi Rawer, Marc Szallies, Alexander Inui, Takashi Urade, Yoshihiro Hayaishi, Osamu Department of Molecular Behavioral Biology Osaka Bioscience Institute Furuedai Suita Osaka 565-0874 Japan Physiologisch-chemisches Institut der Universität Tübingen 72076 Tübingen Hoppe-Seyler-Str. 4 Germany Department of Molecular Protozoology Research Institute for Microbial Diseases Osaka University Suita Osaka 565 Japan Core Research for Evolutional Science and Technology (CREST) Japan Science and Technology Corporation (JST) Japan

African trypanosomiasis (sleeping sickness in humans or nagana in domestic animals) is caused by infection with African trypanosomes and is characterized by a marked increase in prostaglandin (PG) production. Although PGs are known to cause pathogenesis of African trypanosomiasis, little is known about the mechanism of up-regulation of PG production during this disease. In the present study, we investigated the metabolism of arachidonic acid in African trypanosomes and found that by using EIA and gas chromatography mass spectrometry (GC-MS), Trypanosoma brucei produces and secretes PGD₂, E₂, and F_2α. Interestingly, PGs were differentially produced by the different life stages of the parasite. PGF_2α was the most abundant PG produced by the cell lysates. Moreover, PG synthase activities were recovered in the cytosolic fraction and were abolished by heating (100 °C, 5 min). Prostaglandin (PG) formation in African trypanosomes is catalyzed by enzymatic systems, which are markedly different from their mammalian counterparts that are localized in the microsomal fraction. The release of PGs from live trypanosomes into the culture media indicates that T. brucei may well produce PGs that are, in part, responsible for the symptoms observed in patients with African trypanosomiasis. © 2002 Elsevier science B.V.

关键词： Arachidonic acid Pathogenesis Prostaglandins Sleeping sickness T. brucei

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Experimental and theoretical investigation on nonlinear 4.5-optical-cycle-pulse propagation in photonic crystal fibers

Experimental and theoretical investigation on nonlinear 4.5-...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Xiaojun Fang M. Adachi N. Karasawa R. Morita M. Yamashita R.S. Windeler Department of Applied Physics Hokkaido University Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Sapporo Japan Bell Laboratories Lucent Technologies Inc. NJ USA

Summary form only given. In this paper, we demonstrate the experimental evolution of ultra-broad spectra generated by photonic crystal fibers (PCFs) of different lengths, and theoretically analyze the nonlinear process based on our derived nonlinear propagation equation beyond the slowly-varying-envelope approximation (SVEA). The calculated results of the complicated frequency-dependent phase are significantly useful for extremely flexible and accurate active-chirp compensation by a 4-f pulse shaper with a spatial phase modulator for monocycle-pulse generation.

关键词： Optical pulse generation Photonic crystal fibers Optical pulses Supercontinuum generation Numerical simulation Autocorrelation Optical propagation Nonlinear equations Microstructure Pulse measurements

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Photon-number squeezing by the nonlinear backward pump process in a constant-voltage heterojunction LED

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Physical Review B 2002年第16期65卷 165325-165325页

作者： Hiroyuki Sumitomo Masamichi Yamanishi Yutaka Kadoya Department of Physical Electronics Faculty of Engineering and Hiroshima-Branch of Research Project for Core Research for Evolutional Science and Technology (CREST) JST Hiroshima University 1-4-1 Kagamiyama Higashi-Hiroshima 739-8527 Japan

We investigated extensively the sub-Poissonian-photon-state generation by the microscopic backward-pump (BP) process in a semiconductor heterojunction light-emitting diode (LED) under constant-voltage operation. In particular, the BP rate relative to the forward pump rate has been carefully evaluated from the dc characteristics of the LED and shown to depend strongly on the injection current and the device temperature. We then compare the experimental results of the photon-number squeezing performed at various temperatures in the constant-voltage-drive setup with the theoretical prediction estimated numerically using the parameter values determined from the dc measurements. As a consequence, it was proven that the observed squeezing at room temperature is successfully interpreted only in terms of the nonlinear BP model, while that at low temperature (∼100 K) is explained simply by the conventional model based on macroscopic Coulomb-blockade effect for the pump-noise suppression.

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Electric-field effect on 2s excitons of a natural-quantum-well crystal (C6H13NH3)2PbI4

Electric-field effect on 2s excitons of a natural-quantum-we...

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Nonlinear Optics: Materials, Fundamentals and Applications, NLO 2002

作者： Tanaka, Kenichiro Nabeshima, Yasuo Kondo, Takashi Ito, Ryoichi Ema, Kazuhiro Department of Materials Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Department of Physics Meiji University 1-1-1 Higashi-Mita Tama-ku Kanagawa Kawasaki214-8571 Japan Department of Physics Sophia University 7-1 Kioi-cho Chiyoda-ku Tokyo102-8554 Japan Core Research for Evolutional Science and Technology Japan Science and Technology Corporation Japan

Unusual blue shift was observed on quantum-confined 2s exciton in a natural-quantum-well crystal (C6H13NH3)2PbI4 under the longitudinal electric field. This is attributed to the mixing of the 2s state with the triplet... 详细信息

ISBN: (纸本)1557527210

关键词： Excitons

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Theory of photon-number squeezing in a heterojunction LED by the nonlinear backward pump process

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Physical Review B 2002年第16期65卷 165326-165326页

We present a theoretical framework for sub-Poissonian-photon-state generation based on a microscopic backward-pump (BP) process in a semiconductor heterojunction light-emitting diode (LED). The model, which takes into account the BP and nonradiative recombination processes as well as the dynamical response of the external circuit, is applicable to practical LED’s. It is shown that the nonlinear dependence of the BP rate on the carrier number in the active region brings about the photon-number squeezing below the full-shot-noise level, without recourse to a high-impedance constant-current source. We also point out that the bandwidth of the squeezing by the nonlinear BP process is wider than that limited by the recombination lifetime. In addition, we discuss the origin of the nonlinearity of the BP rate based on a microscopic model for the injected carriers in the active region. The nonlinearity is suggested to be due to the rises of the electron temperature and of energetic position of the quasi-Fermi level, with increasing pump current.

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Superconducting and magnetic characteristics in the multilayered high-Tc cuprates TlBa2Ca2Cu3O10−y with Tc>130 K probed by Cu and Tl NMR: High value for Tc

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Physical Review B 2002年第18期65卷 184504-184504页

作者： H. Kotegawa Y. Tokunaga K. Ishida G.-q. Zheng Y. Kitaoka A. Iyo Y. Tanaka H. Ihara Department of Physical Science Graduate School of Engineering Science Osaka University Toyonaka Osaka 560-8531 Japan Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology Corporation (JST) Kawaguchi Saitama 332-0012 Japan National Institute of Advanced Industrial Science and Technology (AIST) Umezono Tsukuba 305-8568 Japan

We report 63Cu and 205Tl nuclear magnetic resonance (NMR) measurements on trilayered high-Tc compounds TlBa2Ca2Cu3O10−y (Tl-1223) that were synthesized at a high pressure and exhibits a high value of superconducting (SC) transition temperature Tc>130 K. In the SC state, the nuclear spin-lattice relaxation rate 1/T1 reveals a T3 behavior below Tc, followed by a T1T=const behavior at very low temperatures. The results are accounted for by the d-wave pairing model where the presence of the residual density of the states Nres(EF) is incorporated at the Fermi level to be consistent with the experiments. The important finding is that the size [in Nres(EF)] is much smaller for the present compounds of Tl-1223 with Tc>130 K than for the previous Tl-2223. Correspondingly, it is shown that an NMR intensity at a satellite peak in the Tl-NMR spectrum, which originates from a possible substitution of Tl for Ca, is much smaller for the former than for the latter. The synthesis technique at a high pressure is found to be a good way to remove such a crystal imperfection due to Tl/Ca intersubstitution. We have demonstrated from a microscopic point of view that as a result of decreasing the degree of disorder effect, the Tc in Tl-1223 has revealed a value higher than 130 K.

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