Neoproterozoic Magmatism and Metamorphism in Northwestern Indian Shield: Implications of Rodinia-Gondwana Tectonics     

K.C. Gyani  T.K. Biswal  M. Yoshida 《Gondwana Research》2001,4(4):625-626

  相似文献   

Nobuo Ikebe     

Manzo Chiji  Masaru Yoshida 《Gondwana Research》2001,4(1):121

  相似文献   

Mechanism and future risk of slope instability induced by extreme rainfall event in Izu Oshima Island,Japan     

Towhata  Ikuo  Goto  Satoshi  Goto  Shigeru  Akima  Takeshi  Tanaka  Junya  Uchimura  Taro  Wang  Gonghui  Yamaguchi  Hiroshi  Aoyama  Shogo 《Natural Hazards》2021,105(1):501-530

Natural Hazards - A volcanic slope in Izu Oshima Island in Japan experienced a profound rain-induced disaster in October 2013. Since this slope had been stable for centuries except for minor...  相似文献   

Heavy oil exposure increases viral production in natural marine bacterial populations     

Mitsuhiro Yoshida  Satoru Suzuki 《Journal of Oceanography》2014,70(1):115-122

This study examined whether heavy oil (HO) increases viral production and how that change may affect the marine bacterial community. The addition of a relatively low concentration (10 μg/mL) of HO to seawater resulted in the highest degree of viral lysis. Although the composition of the bacterial community did not change upon the viral lysis in terms of the taxa present, the relative abundance of the γ-Proteobacteria family Alteromonadaceae decreased (by 10 %) after the HO exposure, implying that the selective lysis by viruses and induced prophages may be responsible for changes in the composition of the bacterial community.  相似文献   

Landslide Susceptibility Mapping along Bhalubang–Shiwapur Area of Mid-Western Nepal Using Frequency Ratio and Conditional Probability Models   总被引：3，自引：3，他引：0  

Amar Deep Regmi  Kohki Yoshida  Hamid Reza Pourghasemi  Megh Raj DhitaL  Biswajeet Pradhan 《山地科学学报》2014,11(5):1266-1285

Roads constructed in fragile Siwaliks are prone to large number of instabilities. Bhalubang–Shiwapur section of Mahendra Highway lying in Western Nepal is one of them. To understand the landslide causative factor and to predict future occurrence of the landslides, landslide susceptibility mapping(LSM) of this region was carried out using frequency ratio(FR) and weights-of-evidence(W of E) models. These models are easy to apply and give good results. For this, landslide inventory map of the area was prepared based on the aerial photo interpretation, from previously published/unpublished reposts, and detailed field survey using GPS. About 332 landslides were identified and mapped, among which 226(70%) were randomly selected for model training and the remaining 106(30%) were used for validation purpose. A spatial database was constructed from topographic, geological, and land cover maps. The reclassified maps based on the weight values of frequency ratio and weights-of-evidence were applied to get final susceptibility maps. The resultant landslide susceptibility maps were verified andcompared with the training data, as well as with the validation data. From the analysis, it is seen that both the models were equally capable of predicting landslide susceptibility of the region(W of E model(success rate = 83.39%, prediction rate = 79.59%); FR model(success rate = 83.31%, prediction rate = 78.58%)). In addition, it was observed that the distance from highway and lithology, followed by distance from drainage, slope curvature, and slope gradient played major role in the formation of landsides. The landslide susceptibility maps thus produced can serve as basic tools for planners and engineers to carry out further development works in this landslide prone area.  相似文献   

Short‐term temporal variation in gelatinous zooplankton populations over 48 hours in a coral reef at Redang Island,Malaysia     

Ryota Nakajima  Dhugal J. Lindsay  Teruaki Yoshida  Bin Haji Ross Othman  Tatsuki Toda 《Marine Ecology》2014,35(2):254-260

Gelatinous zooplankton abundance and species composition were investigated at 3‐h intervals for a 48‐h period at a fringing reef in Malaysia. A total of 20 gelatinous zooplankton species were observed; the community was dominated by the calycophoran siphonophore Diphyes chamissonis (79.9%), followed by the trachymedusdae Aglaura hemistoma (5.6%) and Liriope tetraphylla (4.8%). The gelatinous zooplankton were not collected in the water column during most of the daytime hours (1200, 1500 and 1800 h) but were common during the night. However, an abrupt peak in abundance was found at 0900 h on the second day. The times of appearance at night were different depending on the species, and the number of species was also different depending on the hour of sampling. Sampling at 3‐h intervals over a 48‐h period revealed that the temporal variation (or sampling availability) was large in this study. Careful consideration should be given to the sampling variability in handling the gelatinous zooplankton samples in coral reef areas.  相似文献   

Desorption kinetics of hydrophobic organic contaminants from marine plastic pellets     

Satoshi Endo  Masaki Yuyama  Hideshige Takada 《Marine pollution bulletin》2013

This study investigated the desorption behavior of polychlorinated biphenyls (PCBs) from marine plastic pellets. Long-term desorption experiments were conducted using field-collected polyethylene (PE) pellets. The results indicate that the desorption kinetics highly depends on the PE-water partition coefficients of PCB congeners. After 128 d of the experiment, the smallest congener considered (CB 8) had desorbed nearly completely (98%), whereas major fractions (90–99%) of highly chlorinated congeners remained in the pellets. An intraparticle diffusion model mostly failed to reproduce the desorption kinetics, whereas an aqueous boundary layer (ABL) diffusion model well approximated the data. The desorption half-lives are estimated to 14 d to 210 years for CB 8 to CB 209 in an actively stirred solution (ABL thickness: 30 μm). Addition of methanol to water enhanced the desorption to a large extent. A need for further work to explore roles of organic matter in facilitating solute transfer is suggested.  相似文献   

Proterozoic Events in East Gondwana, Progress in 1999     

M. Yoshida  M. Santosh  C.B. Dissanayake 《Gondwana Research》2000,3(2)

  相似文献   

Lithostratigraphy and Structural Evolution of the Kalima-Moga Tin District, Kibaran Belt (Maniema, Congo)     

J. Kokonyangi  A.B. Kampunzu  M. Yoshida 《Gondwana Research》2000,3(2)

  相似文献   

Experimental constraints on permeable gas transport in crystalline silicic magmas     

Satoshi Okumura  Michihiko Nakamura  Tsukasa Nakano  Kentaro Uesugi  Akira Tsuchiyama 《Contributions to Mineralogy and Petrology》2012,164(3):493-504

The gas and fluid transport in magmas via permeable flow through interconnected bubble networks controls the rate of outgassing from magmas ascending in volcanic conduits and the fluid transport in the mushy boundary layer of magma reservoirs. Hence, clarifying its mechanism and rate is crucial to understanding the explosivity of volcanic eruptions and the evolution and dynamics of a magma reservoir. Recent experimental studies have determined the gas permeabilities in crystal-free rhyolite and basalt. However, no experimental study has investigated the effect of the crystal contents on the permeable gas transport in magmas. In this study, we performed decompression experiments for hydrous rhyolitic melts having crystallinities of 30 and 50 vol% to examine the effect of crystals on the bubble microstructure and gas permeability during magma vesiculation. Size-controlled (100-meshed) corundum crystals were used as an analog of the phenocrysts in silicic magmas. Microstructural analyses using X-ray CT showed that bubbles coalesce and their connectivity increases with a decrease in the final pressure after the decompression, that is, an increase in the vesicularity. As long as the vesicularities of melt part in the crystal-free basis (melt vesicularity) were similar, no clear effect of the crystallinity on the degree of bubble coalescence and connectivity was observed at melt vesicularities <68 vol%. The corundum showed a large contact angle with aqueous fluid as well as plagioclase and alkaline feldspar; this failed to induce the efficient heterogeneous nucleation and coalescence of bubbles on its surface. The gas permeabilities of all the run products were lower than the detection limits of the present analysis (the order of 10⁻¹⁶ m²) at melt vesicularities <68 vol%. These results show that silicic magmas containing 30 and 50 vol% phenocrysts with a large contact angle have low gas permeabilities until the vesicularity becomes large (at least >68 vol%). This result indicates that the permeable fluid transport through a deep volcanic conduit, which has been proposed on the basis of the observations of volcanic gases and natural products, is so slow that other processes, like shear deformation or magma convection, may be needed to explain the observations.  相似文献