Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
Volume 85, Issue 10
Displaying 1-7 of 7 articles from this issue
Reviews
  • Toshihiko BABA, Jun ADACHI, Norihiro ISHIKURA, Yohei HAMACHI, Hirokazu ...
    2009 Volume 85 Issue 10 Pages 443-453
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    Slow light with a markedly low group velocity is a promising solution for optical buffering and advanced time-domain optical signal processing. It is also anticipated to enhance linear and nonlinear effects and so miniaturize functional photonic devices because slow light compresses optical energy in space. Photonic crystal waveguide devices generate on-chip slow light at room temperature with a wide bandwidth and low dispersion suitable for short pulse transmission. This paper first explains the delay-bandwidth product, fractional delay, and tunability as crucial criteria for buffering capacity of slow light devices. Then the paper describes experimental observations of slow light pulse, exhibiting their record high values. It also demonstrates the nonlinear enhancement based on slow light pulse transmission.

    (Communicated by Toshimitsu YAMAZAKI, M.J.A.)
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  • How the laser evolved and was extended to terahertz during my research life A personal review
    Jun-ichi NISHIZAWA
    2009 Volume 85 Issue 10 Pages 454-465
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    The present review describes the author’s involvement and contributions to the development of the semiconductor laser and terahertz oscillators at his laboratory during the period between 1957 and now. The author cites records to show that the idea of a semiconductor laser was documented as a Japanese patent in April 1957 prior to those of G. Gould in 1957 and C.H. Townes in 1958. Terahertz oscillators of high Q values with the use of GaP were developed and applied to areas like investigations of molecular dynamics, cancer diagnosis, etc., thus extending the frontiers of science.

    (Contributed by Jun-ichi NISHIZAWA, M.J.A.)
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Original Papers
  • Lidong DAI, Shun-ichiro KARATO
    2009 Volume 85 Issue 10 Pages 466-475
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    Electrical conductivity of minerals is sensitive to water content and hence can be used to infer the water content in the mantle. However, previous studies to infer the water content in the upper mantle were based on pure olivine model of the upper mantle. Influence of other minerals particularly that of orthopyroxene needs to be included to obtain a better estimate of water content in view of the high water solubility in this mineral. Here we report new results of electrical conductivity measurements on orthopyroxene, and apply these results to estimate the water content of the upper mantle of Earth. We found that the electrical conductivity of orthopyroxene is enhanced by the addition of water in a similar way as other minerals such as olivine and pyrope garnet. Using these new results, we calculate the electrical conductivity of pyrolite mantle as a function of water content and temperature incorporating the temperature and water fugacity-dependent hydrogen partitioning. Reported values of asthenosphere conductivity of 4×10−2−10−1 S/m corresponds to the water content of 0.01–0.04 wt%, a result in good agreement with the petrological model of the upper mantle.

    (Communicated by Ikuo KUSHIRO, M.J.A.)
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  • Yoshiaki ORIHARA, Masashi KAMOGAWA, Toshiyasu NAGAO, Seiya UYEDA
    2009 Volume 85 Issue 10 Pages 476-484
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    Nearly twenty anomalous geoelectric field changes were observed before earthquakes at Kozu-shima Island, Japan, from 1997 to 2000. In order to help locating the current sources of the observed anomalous changes, a bipole-dipole resistivity survey was conducted. From the resistivity survey, including current injection into the ground, it was found that various features of the anomalous changes were systematically different from those of changes caused by artificial sources and induction of geomagnetic disturbances. Moreover, it is suspected that the currents of anomalous changes were generated not near the ground surface but deep under the ground.

    (Contributed by Seiya UYEDA, M.J.A.)
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  • Isao YAMAMOTO, Hironobu FUJIWARA, Masashi KAMOGAWA, Atsushi IYONO, Val ...
    2009 Volume 85 Issue 10 Pages 485-490
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    Temporal correlation between atmospheric anomalies and earthquakes has recently been verified statistically through measuring VHF FM radio waves transmitted beyond the line-of-sight. In order to locate the sources of such atmospheric anomalies, we developed a VHF interferometer system (bistatic-radar type) capable of finding the arrival direction of FM radio waves scattered possibly by earthquake-related atmospheric anomalies. In general, frequency modulation of FM radio waves produces ambiguity of arrival direction. However, our system, employing high-sampling rates of the order of kHz, can precisely measure the arrival direction of FM radio waves by stacking received signals.

    (Communicated by Seiya UYEDA, M.J.A.)
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  • Atsuko H. IWANE, Masatoshi MORIMATSU, Toshio YANAGIDA
    2009 Volume 85 Issue 10 Pages 491-499
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    Until recently, actin was thought to act merely as a passive track for its motility partner, myosin, during actomyosin interactions. Yet a recent report having observed dynamical conformational changes in labeled skeletal muscle α-actin suggests that actin has a more active role. Because the labeling technique was still immature, however, conclusions regarding the significance of the different conformations are difficult to make. Here, we describe the preparation of fully active α-actin obtained from a baculovirus expression system. We developed α-actin recombinants, of which subdomains 1 and 2 have specific sites for fluorescent probes. This specific labeling technique offers to significantly expand the information acquired from actin studies.

    (Communicated by Fumio OOSAWA, M.J.A.)
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  • Mitsuo KAKEI, Toshiro SAKAE, Masayoshi YOSHIKAWA
    2009 Volume 85 Issue 10 Pages 500-507
    Published: 2009
    Released on J-STAGE: December 14, 2009
    JOURNAL FREE ACCESS
    It is well known that exposure to environmental cadmium causes itai-itai (ouch-ouch) disease. However, the exact mechanism underlying this bone disease remains unresolved. By focusing on the calcification mechanism, we examined developing tooth enamel in rats exposed to cadmium to test the hypothesis that cadmium exposure may cause defects in crystal formation. Electron microscopy revealed the presence of perforated crystals in developing tooth enamel, indicating that the process of crystal nucleation may have been interrupted by cadmium exposure. Furthermore, biochemical analyses revealed that the catalytic activity of carbonic anhydrase in the immature enamel matrix declined remarkably despite the fact that quantitative reduction of this enzyme was insignificant, suggesting that the decline of catalytic activity may have resulted from the replacement of zinc with cadmium ions. Therefore, we concluded that the poor catalytic activity of cadmium-binding carbonic anhydrase might hinder the nucleation process, leading to an impairment in mineralization that causes itai-itai disease.

    (Communicated by Tatsuo SUDA, M.J.A.)
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