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Volume 84, Issue 4
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Review
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Kuniaki Tatsuta2008 Volume 84 Issue 4 Pages 87-106
Published: April 30, 2008
Released on J-STAGE: April 17, 2008
JOURNAL FREE ACCESSThe first total synthesis and development of a variety of bioactive natural products have been accomplished by using carbohydrates as a chiral source. In addition, practically useful intermediates have been created, analogs of natural products have been prepared, their structure-activity relationships studied, and the large-scale preparations of medicinally useful compounds established. The key target molecules have been the “Big Four” antibiotics (macrolides, aminoglycosides, β-lactams and tetracyclines), pyranonaphthoquinone antibiotics, glycosidase inhibitors, and a side-chain of cephem antibiotics.
(Communicated by Satoshi OMURA, M.J.A.)View full abstractDownload PDF (489K)
Original Papers
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Hiroyuki K. M. Tanaka, Izumi Yokoyama2008 Volume 84 Issue 4 Pages 107-116
Published: April 30, 2008
Released on J-STAGE: April 17, 2008
JOURNAL FREE ACCESSLava domes are one of the conspicuous topographic features on volcanoes. The subsurface structure of the lava dome is important to discuss its formation mechanism. In the 1944 eruption of Volcano Usu, Hokkaido, a new lava dome was formed at its eastern foot. After the completion of the lava dome, various geophysical methods were applied to the dome to study its subsurface structure, but resulted in a rather ambiguous conclusion. Recently, from the results of the levelings, which were repeated during the eruption, “pseudo growth curves” of the lava dome were obtained. The curves suggest that the lava dome has a bulbous shape. In the present work, muon radiography, which previously proved effective in imaging the internal structure of Volcano Asama, has been applied to the Usu lava dome. The muon radiography measures the distribution of the “density length” of volcanic bodies when detectors are arranged properly. The result obtained is consistent with the model deduced from the pseudo growth curves. The measurement appears to afford useful method to clarify the subsurface structure of volcanoes and its temporal changes, and in its turn to discuss volcanic processes. This is a point of contact between high-energy physics and volcano physics.
(Contributed by Izumi YOKOYAMA, M.J.A.)View full abstractDownload PDF (551K) -
Elizabeth Dologlou2008 Volume 84 Issue 4 Pages 117-122
Published: April 30, 2008
Released on J-STAGE: April 17, 2008
JOURNAL FREE ACCESSStress drop values for fourteen large earthquakes with MW≥5.4 which occurred in Greece during the period 1983–2007 are available. All these earthquakes were preceded by Seismic Electric Signals (SES). An attempt has been made to investigate possible correlation between their stress drop values and the corresponding SES lead times. For the stress drop, we considered the Brune stress drop, ΔσB, estimated from far field body wave displacement source spectra and ΔσSB derived from the strong motion acceleration response spectra. The results show a relation may exist between Brune stress drop, ΔσB, and lead time which implies that earthquakes with higher stress drop values are preceded by SES with shorter lead time.
(Communicated by Seiya UYEDA, M.J.A.)View full abstractDownload PDF (201K)
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