Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
Volume 77 , Issue 7
Showing 1-4 articles out of 4 articles from the selected issue
  • Viacheslav PILIPENKO, Sergey SHALIMOV, Seiya UYEDA, Haruo TANAKA
    2001 Volume 77 Issue 7 Pages 125-130
    Published: 2001
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    Kushida noticed anomalous over-horizon reception of FM radio waves (-80MHz) before earthquakes when epicenters were in a certain sensitive region. The suggested method of earthquake prediction recognizes precursors in supposedly back-scattered waves from the ionosphere several days or few weeks before the seismic events. We try to clarify the possible underlying physical mechanism for this method within the framework of existing notions on the lithosphere-atmosphere-ionosphere coupling. Gravity waves in the atmosphere are speculated to be generated by quasi-periodic movements of tectonic blocks or yield of gases along faults. Conversion of large-scale gravity waves above a seismically active region into ionospheric disturbances involves formation of sporadic E-layer. The sporadic E-layer in turn may be regarded as a free energy source of generation of small-scale (a few meters) ionospheric plasma irregularities, presumably due to the modified gradient-drift plasma instability. These meter-range irregularities could be the reason for the back-scattered VHF radio waves. Some experimental tests for verification of this hypothesis are suggested.
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  • Kazuhiro SUZUKI, Hirotaka ODA, Mitsuhiko OGAWA, Etsuko NIU, Akiko IKED ...
    2001 Volume 77 Issue 7 Pages 131-134
    Published: 2001
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    According to folklore the fleet that was dispatched to Japan for the second Mongol invasion of 1281 encountered a fierce typhoon at Takashima. Radiocarbon (14C) ages of wooden anchors and planks excavated from the submerged site at Takashima were determined using accelerator mass spectrometry (AMS). The 14C ages are 745±20 BP for bamboo and 770±20 BP for wood from the intact wooden anchor, and 840±20/865±20 BP for the planks, respectively. The calibrated bamboo age of 1268-1284 cal AD and the slightly older age of 1257-1279 cal AD for wood suggest that the wooden anchor was manufactured just before the invasion. The age range of planks (1191-1236 and 1163-1215 cal AD) is consistent with an idea that they are likely to be derived from contemporaneous ships. The high-precision AMS 14C dating confirms that the wooden anchors and planks are remains of wrecked Mongolian warships that were involved in the second Mongol invasion.
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  • Yoshihiko TAMURA, Yoshiyuki TATSUMI, Dapeng ZHAO, Yukari KIDO, Hiroshi ...
    2001 Volume 77 Issue 7 Pages 135-139
    Published: 2001
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    Clustering of volcanic centers, low-velocity regions in the mantle wedge and local negative Bouguer gravity anomalies along the rear of the volcanic arc are closely correlated in Northeast Japan. These observations may be best explained by the presence of inclined, finger-like, hot regions in the mantle wedge of the subduction zone. These fingers, perpendicular to the arc-trench system in the Northeast Japan arc, have an average separation of -80km and an average width of 50km. Each of ten fingers extends from the deep mantle (>150km) below the back-arc region toward the shallower mantle (-50km) beneath the volcanic front. Quaternary volcanoes are built immediately above the hot mantle fingers. Volcanic basements are uplifted by repeated injection of magmas into the crust, accompanied by Quaternary volcanic activity on the surface. Although volcanic activity is rare along the Japan Sea coast, the hot mantle fingers exist with-in the mantle wedge as evidenced by tomographic results. The negative Bouguer anomalies at the rear of the volcanic arc could be caused by magmas supplied from the hot mantle fingers, which have not yet been erupted, but may have accumulated at the Moho discontinuity.
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  • Asako HASE, Kiichi ARAHATA
    2001 Volume 77 Issue 7 Pages 140-143
    Published: 2001
    Released: October 17, 2006
    JOURNALS FREE ACCESS
    Emerin is an inner nuclear membrane protein, which is the gene product responsible for X-linked Emery-Dreifuss muscular dystrophy (X-EDMD). In this study we extracted emerin from mammalian cells and examined the DNA binding property by in vitro binding assay with double-strand DNA cellulose. We prepared emerins from two sources; the native emerin in HeLa cells and the recombinant human emerin produced in COS7. These samples were incubated with DNA cellulose, and the bound proteins were directly eluted with salt-containing buffers. These elutants were subsequently analyzed by SDS-PAGE and western blotting. The results showed that 1) both HeLa cell emerin and recombinant COST emerin were recovered in the elutants of the binding assays, and 2) several other nuclear proteins were always co-isolated in the purification procedure of recombinant COS7 emerin. These results suggest that emerin is tightly integrated in some protein“complex”with other nuclear components and binds DNA as a protein complex. In this study we demonstrated that emerin directly or indirectly binds to DNA.
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