432 research outputs found
Provenance of Lower Cretaceous sediments in the Nariwa and Hokubo areas, Okayama Prefecture, deduced from detrital modes and geochemistry of sandstones
Petrographic and geochemical study of sandstones from the Kenseki Formation have shown that the sandstones are compositionally immature. The immaturity is reflected geochemically by their low SiO2 contents (52-66 wt%) and petrographically by low modal percents of quartz and K-feldspar, and high modal percents of plagioclase and volcanic lithic fragmants. The Kensaki sandstones are, however, poor in Na2O (up to 2.1 wt%).
Both petrography and geochemistry suggest a heterogeneous source lithologies of acidic and basic volcanics, sedimentary, and ultramafic rocks. Petrographic evidence is supplied by quartz and plagioclase of volcanic origin, acidic volcanic fragments, basic volcanic fragments, volcanic glass, serpentinite fragments and detrital spinel grains. Geochemical evidence is provided by high FeO* (total iron as FeO), MgO, TiO2, CaO and K2O contents.
Petrographic and geochemical study of the Kenseki sandstones indicate calc-alkaline oceanic island are provenance. The sediments were locally derived, with Alpine-type ultramafic rocks exposed in the north and volcanic materials of the Akiyoshi Belt supplying the bulk of the detritus
Physical Relation of Source I to IRc2 in the Orion KL Region
We present mid-infrared narrow-band images of the Orion BN/KL region, and
N-band low-resolution spectra of IRc2 and the nearby radio source "I." The
distributions of the silicate absorption strength and the color temperature
have been revealed with a sub-arcsecond resolution. The detailed structure of
the 7.8 micron/12.4 micron color temperature distribution was resolved in the
vicinity of IRc2. A mid-infrared counterpart to source I has been detected as a
large color temperature peak. The color temperature distribution shows an
increasing gradient from IRc2 toward source I, and no dominant temperature peak
is seen at IRc2. The spectral energy distribution of IRc2 could be fitted by a
two-temperature component model, and the "warmer component" of the infrared
emission from IRc2 could be reproduced by scattering of radiation from source
I. IRc2 itself is not self-luminous, but is illuminated and heated by an
embedded luminous young stellar object located at source I.Comment: 20 pages, 11 figures. Minor corrections had been done in the ver.2.
Accepted for publication in PAS
岡山県に分布する白亜紀前期羽山層砕屑物質の供給源:砕屑粒の鉱物化学組成とモード組成から導かれる制約
Petrographic and phase chemistry studies of detrital grains were carried out on sandstones from the Lower Cretaceous Hayama Formation, Inner Zone of Southwest Japan, to determine their provenance and the tectonic setting during the early Cretaceous. The results of the modal mineralogy suggest that the Hayama Formation has magmatic arc provenance and that deposition of the sediments took place in the back-arc areas with detritus mostly derived from the magmatic arc and rifted continental margins. The chemical compositions of chromian spinel, chlorite and sphene indicate that significant proportions of the detrital grains were derived from mafic and/or ultramafic sources. The source areas are the mafic and ophiolitic rocks in the Sangun-Renge and Akiyoshi terranes and the felsic volcanic rocks probably from either the Akiyoshi terrane or a source not presently exposed in southwest Japan. However, minor amounts of the detritus were derived from the basement rocks; i.e., carbonates and siliciclastic rocks of the Akiyoshi terrane and the metamorphosed mafic rocks of the Chizu terrane
Crystalline Silicate Feature of the Vega-like star HD145263
We have observed the 8-13 m spectrum (R250) of the Vega-like star
candidate HD145263 using Subaru/COMICS. The spectrum of HD145263 shows the
broad trapezoidal silicate feature with the shoulders at 9.3 m and 11.44
m, indicating the presence of crystalline silicate grains. This detection
implies that crystalline silicate may also be commonly present around Vega-like
stars. The 11.44 m feature is slightly shifted to a longer wavelength
compared to the usual 11.2-3 m crystalline forsterite feature detected
toward Herbig Ae/Be stars and T Tauri stars. Although the peak shift due to the
effects of the grain size can not be ruled out, we suggest that Fe-bearing
crystalline olivine explains the observed peak wavelength fairly well.
Fe-bearing silicates are commonly found in meteorites and most interplanetary
dust particles, which originate from planetesimal-like asteroids. According to
studies of meteorites, Fe-bearing silicate must have been formed in asteroidal
planetesimals, supporting the scenario that dust grains around Vega-like stars
are of planetesimal origin, if the observed 11.44 m peak is due to
Fe-bearing silicates.Comment: accepted for Publication in ApJ
A Case of Takotsubo Cardiomyopathy after Surgery for Common Bile Duct Stones
Takotsubo cardiomyopathy (TC) is a rare reversible circulatory syndrome often detected in elderly patients after general surgery. We report the case of an 85-year-old woman who was admitted for obstructive jaundice and underwent ERCP and ENBD before operation. She finally underwent cholecystectomy and choledocholithotomy with the diagnosis of gallbladder and common bile duct stones. In the evening just after the operation, without symptoms of cardiac failure, her ECG suddenly exhibited abnormal ST-T elevation in leads II, III, and V2-V6, though neither CPK(MB) nor troponin T was elevated. Echocardiogram demonstrated basal hyperkinesis and apical dyskinesis, suggesting TC. Conservative treatment enabled recovery, ECG was normalized in a month, and the postoperative course was satisfactory. The stress on her during treatment might have been a cause of this unique cardiomyopathy, and it should be recalled that TC is a potential complication of hepato-biliary-pancreatic surgery
Hydrodynamic coupling between two fluid membranes
The coupled in-plane diffusion dynamics between point-particles embedded in
stacked fluid membranes are investigated. We calculate the contributions to the
coupling longitudinal and transverse diffusion coefficients due to particle
motion within the different as well as the same membranes. The stacked geometry
leads to a hydrodynamic coupling between the two membranes.Comment: 9 Pages, 5 figures. Accepted for publication in J. Phys.: Condens.
Matte
Microextensive Chaos of a Spatially Extended System
By analyzing chaotic states of the one-dimensional Kuramoto-Sivashinsky
equation for system sizes L in the range 79 <= L <= 93, we show that the
Lyapunov fractal dimension D scales microextensively, increasing linearly with
L even for increments Delta{L} that are small compared to the average cell size
of 9 and to various correlation lengths. This suggests that a spatially
homogeneous chaotic system does not have to increase its size by some
characteristic amount to increase its dynamical complexity, nor is the increase
in dimension related to the increase in the number of linearly unstable modes.Comment: 5 pages including 4 figures. Submitted to PR
Crystal structure of A3B3 complex of V-ATPase from Thermus thermophilus
Vacuolar-type ATPases (V-ATPases) exist in various cellular membranes of many organisms to regulate physiological processes by controlling the acidic environment. Here, we have determined the crystal structure of the A3B3 subcomplex of V-ATPase at 2.8 Å resolution. The overall construction of the A3B3 subcomplex is significantly different from that of the α3β3 sub-domain in FoF1-ATP synthase, because of the presence of a protruding ‘bulge' domain feature in the catalytic A subunits. The A3B3 subcomplex structure provides the first molecular insight at the catalytic and non-catalytic interfaces, which was not possible in the structures of the separate subunits alone. Specifically, in the non-catalytic interface, the B subunit seems to be incapable of binding ATP, which is a marked difference from the situation indicated by the structure of the FoF1-ATP synthase. In the catalytic interface, our mutational analysis, on the basis of the A3B3 structure, has highlighted the presence of a cluster composed of key hydrophobic residues, which are essential for ATP hydrolysis by V-ATPases
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