Intrinsic properties of carbon stars. I. Effective temperature scale of N-type carbon stars     

Takashi Tsuji 《Journal of Astrophysics and Astronomy》1981,2(2):213

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Geological and Hydrodynamical Examination of the Bathyal Tsunamigenic Origin of Miocene Conglomerates in Chita Peninsula, Central Japan     

Toru Tachibana  Yoshinobu Tsuji 《Pure and Applied Geophysics》2011,168(6-7):997-1014

A conglomerate appears on a rocky coast called ??Tsubutega-ura Coast??, located on the southwestern coast near the southern tip of the Chita Peninsula, Aichi Prefecture, central Japan. The conglomerate belongs to Miocene sedimentary rocks termed the Morozaki Group. The conglomerate includes meter-scale boulders, indicating that it was formed by an extraordinary event. In the geological investigation, we observed that the conglomerate shows alternate changes of paleocurrent directions between seaward and landward. This feature is supposed to be formed by tsunami currents. In the hydrodynamical investigation, we obtained following results: (1) the lowest limit of a current velocity to move a boulder of about 3?m in diameter would be about 2?C3?m/s, (2) the speed of tsunami currents reproduced by tsunami simulation exceeds 3?m/s at 300?m in depth when the tsunami is generated by a gigantic earthquake with magnitude 9.0 or more, (3) the transport distance of the boulder would be several hundred?meters to several kilometers by one tsunami event caused by a gigantic earthquake. We conclude that tsunamis best explain the formation of the conglomerate deposited in upper bathyal environments about 200?C400?m depth, both from geological and hydrodynamical viewpoints.  相似文献   

Infrared Emissions from Metals in Carbon Stars and M Giant     

W. Aoki  T. Tsuji  K. Ohnaka 《Astrophysics and Space Science》1997,255(1-2):299-300

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Variations in fraction of absorbed photosynthetically active radiation and comparisons with MODIS data in burned black spruce forests of interior Alaska     

Hiroki Iwata  Masahito Ueyama  Chie Iwama  Yoshinobu Harazono 《Polar Science》2013,7(2):113-124

Absorption of photosynthetically active radiation (PAR) by vegetation was observed in two burned black spruce forests, one and seven years after wildfire, in interior Alaska along with several vegetation properties. This study considered PAR absorption by mosses by examining the relationship between PAR transmittance and fractional coverage of green vegetation. Our results suggest that mosses absorbed a considerable fraction of incoming PAR in the burned forests, which cannot be neglected in evaluating the fraction of absorbed PAR (FPAR). The relationships between FPAR and vegetation indices revealed that enhanced vegetation index (EVI) may be suitable for expressing the spatial and temporal variation of FPAR, regardless of stand age after wildfire. The comparison between the observed in situ FPAR and FPAR derived from Moderate Resolution Imaging Spectroradiometer (MODIS FPAR) clearly showed that MODIS FPAR was highly overestimated. The most likely reason for the overestimation was identified as misclassification of land cover type. The current regional estimation of photosynthesis in boreal region based on the light-use efficiency approach and MODIS FPAR is probably overestimated, and an accurate distribution of FPAR is desired for clarifying the regional carbon exchange in boreal forests.  相似文献   

Gas hydrate saturation at Site C0002, IODP Expeditions 314 and 315, in the Kumano Basin,Nankai trough     

Ayumu Miyakawa  Saneatsu Saito  Yasuhiro Yamada  Hitoshi Tomaru  Masataka Kinoshita  Takeshi Tsuji 《Island Arc》2014,23(2):142-156

The degree of gas hydrate saturation at Integrated Ocean Drilling Program (IODP) Site C0002 in the Kumano Basin, Nankai Trough, was estimated from logging‐while‐drilling logs and core samples obtained during IODP Expeditions 314 and 315. Sediment porosity data necessary for the calculation of saturation were obtained from both core samples and density logs. Two forms of the Archie equation (‘quick‐look’ and ‘standard’) were used to calculate gas hydrate saturation from two types of electrical resistivity log data (ring resistivity and bit resistivity), and a three‐phase Biot‐type equation was used to calculate gas hydrate saturation from P‐wave velocity log data. The gas hydrate saturation baseline calculated from both resistivity logs ranges from 0% to 35%, and that calculated from the P‐wave velocity log ranges from 0% to 30%. High levels of gas hydrate saturation (>60%) are present as spikes in the ring resistivity log and correspond to the presence of gas hydrate concentrations within sandy layers. At several depths, saturation values obtained from P‐wave velocity data are lower than those obtained from bit resistivity data; this discrepancy is related to the presence of free gas at these depths. Previous research has suggested that gas from deep levels in the Kumano Basin has migrated up‐dip towards the southern and seaward edge of the basin near Site C0002. The high saturation values and presence of free gas at site C0002 suggest that a large gas flux is flowing to the southern and seaward edge of the basin from a deeper and/or more landward part of the Kumano Basin, with the southern edge of the Kumano Basin (the location of site C0002) being the main area of fluid accumulation.  相似文献   

Mineral classification from quantitative X-ray maps using neural network: Application to volcanic rocks     

Takeshi  Tsuji  Haruka  Yamaguchi  Teruaki  Ishii  Toshifumi  Matsuoka 《Island Arc》2010,19(1):105-119

We developed a mineral classification technique of electron probe microanalyzer (EPMA) maps in order to reveal the mineral textures and compositions of volcanic rocks. In the case of lithologies such as basalt that include several kinds of minerals, X-ray intensities of several elements derived from EPMA must be considered simultaneously to determine the mineral map. In this research, we used a Kohonen self-organizing map (SOM) to classify minerals in the thin-sections from several X-ray intensity maps. The SOM is a type of artificial neural network that is trained using unsupervised training to produce a two-dimensional representation of multi-dimensional input data. The classified mineral maps of in situ oceanic basalts of the Juan de Fuca Plate allowed us to quantify mineralogical and textural differences among the marginal and central parts of the pillow basalts and the massive flow basalt. One advantage of mineral classification using a SOM is that relatively many minerals can be estimated from limited input elements. By applying our method to altered basalt which contains multiple minerals, we successfully classify eight minerals in thin-section.  相似文献   

Observation of edge waves trapped on the continental shelf in the vicinity of Makurazaki Harbor, Kyushu, Japan     

Takashi Yanuma  Yoshinobu Tsuji 《Journal of Oceanography》1998,54(1):9-18

Sea-bottom pressure gauges were used to measure sea levels at two points on the shelf off the southern coast of Satsuma Peninsula, Kyushu, Japan. Spectral analysis of the observed records and the tide-gauge record of Makurazaki Harbor revealed several predominant common peaks. At the same time, the eigenmodes for the trapped waves on the shelf and inside Makurazaki Bay were obtained numerically using a two-dimensional model, and the periods and the spatial distribution of amplitudes of the proper modes were obtained. A comparison of the calculated modes with the periods and phase patterns of the observed peaks clarified that peaks with periods of 19.5, 16, 13.3, and 12.2 minutes in the shelf region were the modes of standing-edge waves, and the peak with the period of 16 minutes in Makurazaki Harbor was the fundamental mode of the harbor. Among the modes of standing-edge waves, the mode of the period 16 minutes on the shelf had nearly the same period as that of the fundamental mode of Makurazaki Harbor. An analysis of changes of spectral densities of these two modes confirmed that the fundamental mode of the Makurazaki Harbor was induced by this standing-wave mode.  相似文献   

Sulfur bacteria originating from the water and organisms in a hydrothermally active area of the mid-okinawa trough     

Takeshi Naganuma  Eiko Ikemoto  Shunji Sukizaki  Yoshito Tsuji  Hiroshi Hotta 《Journal of Oceanography》1990,46(3):111-117

Hydrothermal venting and associated fauna were observed in the mid-Okinawa Trough during deep-sea diving byShinkai 2000. Water and organisms were collected there for on-board cultivation of sulfur bacteria. Sulfur bacteria capable of growing on an inorganic medium containing thiosulfate were subcultured and isolated. The isolated chemoautotrophic sulfur bacteria were all rod- to beanshaped, nonsporing, and gram-negative. They could also grow on an organic medium and thus were shown to be facultative chemoautotrophs. Their facultative chemoautotrophy would result in synergetic metabolism of both inorganic and organic substrates; thus the sulfur bacteria could be highly adaptive to nutritional diversity of hydrothermal vent areas.  相似文献   

Annual Variability of Sea Surface Height and Upper Layer Thickness in the Pacific Ocean     

Yoshinobu Wakata  Shouko Kitaya 《Journal of Oceanography》2002,58(3):439-450

The annual variabilities of the sea surface height in the Pacific Ocean were investigated by analyzing the TOPEX/POSEIDON satellite data and by solving a reduced gravity model. We discuss how adequately the simple model can capture the variabilities of the sea surface height, and what the cause of the variabilities is. Three large amplitude peaks in the satellite data are found along the 12°N longitude line. Two elongated zones with a large amplitude are also found: one extends east-west along 6°N and the other extends northwestward from South America around 25°S. These features are adequately reproduced in the numerical simulation of the reduced gravity model. The propagation of the Rossby wave is analyzed by the use of the extended Eliassen-Palm flux to investigate the mechanism of these annual variabilities. The two east peaks around 12°N can be explained in terms of the interference between the local Ekman pumping and the free wave emitted near the western coast of North America, and the most western peak is affected by the Rossby wave formed by the local wind stress. The elongated zonal area around 6°N is mainly due to the local Ekman pumping. Another area around 25°S results from the convergence of the free Rossby wave emitted from the eastern boundary and the area with the strong wind stress curl off South America. A discrepancy between the satellite data and the model results suggests that the eastern equatorial Pacific Ocean is relatively calm in the model but not in the satellite data. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Vertical distribution of bacterial abundance in the northwest pacific ocean     

Takeshi Naganuma  Eiko Ikemoto  Shunji Sukizaki  Yoshito Tsuji  Hiroshi Hotta 《Journal of Oceanography》1990,46(3):107-110

Mixed populations of free-living marine bacteria were collected at depths from the surface to the bottom (1,960m in Suruga Bay and 1,585 m in the Japan Sea) in the northwest Pacific during deep-sea diving by the submersible,Shinkai 2000. Their abundance in total cell counts and in lipopolysaccharide (LPS) concentration was found to decrease with increasing depth, and the decreasing profiles were shown to be linear on logarithmic scales. The total cell counts and the LPS concentration showed a linear relationship on arithmetic scales, and the LPS content per cell was found to be 1.02×10^–14 g.  相似文献