Subsurface structure under a basaltic monogenetic volcano near the active Atera fault     

T. Tanaka  H. Aoki  A. J. Martin  K. Oshita  K. Nozaki  M. Onishi 《Tectonophysics》2004,378(3-4):197

In this study, we examined the subsurface structure in the vicinity of the active Atera fault beneath at least one monogenetic volcano that forms the Sakashita body of the Ueno basalts, central Japan. Microgravity and seismic reflection surveys over an area of about 3×3 km (horizontal)×1 km (vertical from surface) revealed that (1) a low-density body interpreted as the damaged zone of the Atera fault reaches a depth more than 200 m below sea level; and (2) a weak zone of crust that may exist about 1.5 km southwest of the Atera fault in a direction parallel to it. By combining the shape of the Sakashita body and (2), we propose that a dyke extending in a NW–SE direction with several vent alignments in the same direction may exist along this weak zone. This suggests that the studied area was governed in the NW–SE compressional and NE–SW extensional stress field when the Sakashita body formed.  相似文献   

Thermal equation of state of majorite with MORB composition     

Yu Nishihara  Ichiro Aoki  Eiichi Takahashi  Ken-ichi Funakoshi 《Physics of the Earth and Planetary Interiors》2005,148(1):73-84

In situ synchrotron X-ray diffraction experiments were conducted using the SPEED-1500 multi-anvil press at SPring-8 on majoritic garnet synthesized from natural mid-ocean ridge basalt (MORB), whose chemical composition is close to the average of oceanic crust, at 19 GPa and 2200 K. Pressure-volume-temperature data were collected using a newly developed high-pressure cell assembly to 21 GPa and 1273 K. Data were fit to the high-temperature Birch-Murnaghan equation of state, with fixed values for the ambient cell volume (V₀ = 1574.14(4) Å³) and the pressure derivative of the isothermal bulk modulus (K^′T = 4). This yielded an isothermal bulk modulus of K_T0 = 173(1) GPa, a temperature derivative of the bulk modulus (∂K_T/∂T)_P = −0.022(5) GPa K⁻¹, and a volumetric coefficient of thermal expansivity α = a + bT with values of a = 2.0(3) × 10⁻⁵ K⁻¹ and b = 1.0(5) × 10⁻⁸ K⁻². The derived thermoelastic parameters are very similar to those of pyrope. The density of subducted oceanic crust compared to pyrolitic mantle at the conditions in Earth's transition zone (410-660 km depth) was calculated using these results and previously reported thermoelastic parameters for MORB and pyrolite mineral assembledges. These calculations show that oceanic crust is denser than pyrolitic mantle throughout the mantle transition zone along a normal geotherm, and the density difference is insensitive to temperature at the pressures in lower part of the transition zone.  相似文献   

Cloning and sequencing of the allophycocyanin genes fromSpirulina maxima (Cyanophyta)     

Song  Qin  Kojima  Hiroyuki  Kawata  Yoshikazu  Yano  Shin-ichi  Cheng-kui  Zeng 《中国海洋湖沼学报》1998,16(1):6-11

The genes coding for the α-and β-subunit of allophycocyanin (apcA andapcB) from the cyanophyteSpirulina maxima were cloned and sequenced. The results revealed 44.4% of nucleotide sequence similarity and 30.4% of similarity of deduced amino acid sequence between them. The amino acid sequence identities betweenS. maxima andS. platensis are 99.4% for α subunit and 100% for β subunit.

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Transposable genetic elements inSpirulina and potential applications for genetic engineering     

Kojima  Hiroyuki  Song  Qin  Ajith Kumar  Thankappan  Kawata  Yoshikazu  Yano  Shin-ichi 《中国海洋湖沼学报》1998,16(1):30-39

Transposable elements in cyanobacteria are briefly reviewed. Evidence is presented to show that transposable elements inSpirulina platensis is actually reflected on the phenotype change, i e., helical to straight filaments. Transposition intermediates of DNA were isolated from the extrachromosome and the transposition was related to helical variations inSpirulina. Uses of transposable elements for microalgal recombination are discussed based on the transposition mechanism.

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Applying the adjoint-free 4dVar assimilation to modeling the Kuroshio south of Japan     

Miyazawa  Yasumasa  Yaremchuk  Max  Varlamov  Sergey M.  Miyama  Toru  Aoki  Kunihiro 《Ocean Dynamics》2020,70(8):1129-1149

Ocean Dynamics - Operational ocean nowcast/forecast systems require real-time sampling of oceanic data for representing realistic oceanic conditions. Satellite altimetry plays a key role in...  相似文献   

Effects of alkali and alkaline-earth cations on the high-pressure sound velocities of aluminosilicate glasses     

Aoki  Koji  Sakamaki  Tatsuya  Ohashi  Tomonori  Ikeda  Osamu  Suzuki  Akio 《Physics and Chemistry of Minerals》2020,47(6):1-9

Physics and Chemistry of Minerals - A black tourmaline sample from Seagull batholith (Yukon Territory, Canada) was established to be a schorl with concentrations of Fe2+ among the highest currently...  相似文献   

The Southern Annular Mode and opposite-phased Basin Mode of the Southern Ocean circulation     

Yuji Iijima  Shigeru Aoki  Kunio Kutsuwada 《Journal of Oceanography》2009,65(1):53-60

Over the Southern Ocean the dominant modes of the atmospheric field are known as the Southern Annular Mode (SAM) or Antarctic Oscillation, and the Pacific South American (PSA) pattern. Statistical analysis of sea surface wind (SSW) from satellite observation revealed two leading modes of SAM-like and PSA patterns. In the high latitudes, the SAM-like pattern of the SSW had a large amplitude over the Bellingshausen Basin and Australian-Antarctic Basin, with opposite phase between the two basins. On the intraseasonal time scale, large-scale sea surface height (SSH) also had notable variability, showing a basin-scale anti-phase mode over the two basins. To explain the response of oceanic variations to these atmospheric modes, we analyzed the relationship between the dominant modes of wind stress and large-scale SSH on the intraseasonal time scale. The SAM-like pattern of wind stress was correlated with the SSH variation over the two basins. The SSH basin mode was most simply explained by a simple barotropic response to the SAM-like mode of wind stress, with the curl of opposite phase between the two basins. We conclude that the zonal asymmetry of the wind field of the SAM plays an important role in driving the antiphase SSH basin modes.  相似文献   

Influence of the east-west component of the interplanetary magnetic field on the intensity of the auroral electrojet     

Kazuyuki Hakamada  Takao Aoki  Takashi Murayama 《Planetary and Space Science》1980,28(1):29-39

Analysis of interplanetary data has been made to evaluate the influence of the Biny component of the IMF on the magnitude of the AL index, especially with reference to the contribution of B_y in the reconnection process between the IMF and geomagnetic fields in the dayside part of the magnetosphere. The results of the analysis showed that the effect of Biny on AL is predominantly of a different type from that expected by the current theory of reconnection, and the B_y effect of the latter type was found to be much less significant in magnitude than the theory predicts. The discrepancy may be resolved if the region where the reconnection takes place has an elongated shape.  相似文献   

The 1996 subaqueous eruption at Academii Nauk volcano (Kamchatka) and its effects on Karymsky lake     

S. M. Fazlullin  S. V. Ushakov  R. A. Shuvalov  M. Aoki  A. G. Nikolaeva  E. G. Lupikina 《Journal of Volcanology and Geothermal Research》2000,97(1-4)

A subaqueous eruption in Karymsky lake in the Academii Nauk caldera dramatically changed its water column structure, water chemistry and biological system in less than 24 h, sending major floodwaves down the discharging river and eruption plumes with ash and gases high into the atmosphere. Prior to the eruption, the lake had a pH of about 7, was dominated by bicarbonate, and well stocked with fish, but turned in early 1996 into a stratified, initially steaming waterbody, dominated by sulfate with high Na and K levels, and devoid of fish. Blockage of the outlet led to rising waterlevels, followed by dam breakage and catastrophic water discharge. The total energy input during the eruption is estimated at about 10¹⁶ J. The stable isotope composition of the lake water remained dominated by the meteoric meltwaters after the eruption.  相似文献   

A practical model to estimate photosynthetically active radiation using general meteorological elements in a temperate humid area and comparison among models     

Yasuko Mizoguchi  Yukio Yasuda  Yoshikazu Ohtani  Tsutomu Watanabe  Yuji Kominami  Katsumi Yamanoi 《Theoretical and Applied Climatology》2014,115(3-4):583-589

Although accurately evaluating photosynthetically active radiation is important, much effort is required to measure this radiation using a quantum sensor. We develop a new model that makes estimates using only general meteorological data—solar radiation, atmospheric pressure, air temperature, and relative humidity. Root mean square deviations for eight datasets at five sites in Japan were smaller than 5.2 %, similar to error in other studies and to individual differences of quantum sensors. Most root mean square deviations of nine previous models and our eight datasets are larger than that of the new estimation model, which performed well. This suggests that the model is useful for estimating photosynthetically active radiation in a temperate, humid area of Japan.  相似文献