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71.
A. M. Swinbank A. C. Edge Ian Smail J. P. Stott M. Bremer Y. Sato C. van Breukelen M. Jarvis I. Waddington L. Clewley J. Bergeron G. Cotter S. Dye J. E. Geach E. Gonzalez-Solares P. Hirst R. J. Ivison S. Rawlings C. Simpson G. P. Smith A. Verma T. Yamada 《Monthly notices of the Royal Astronomical Society》2007,379(4):1343-1351
72.
Machiko Yamada Eri Katsuki Mayuko Otsubo Mayumi Kawaguchi Kazuhiko Ichimi Hideki Kaeriyama Kuninao Tada Paul J. Harrison 《Journal of Oceanography》2010,66(6):755-771
Seven Skeletonema species were identified at one station in the industrial harbor Dokai Bay, Japan, in October 2007 and then monthly from January
2008 to December 2009 by morphological scanning electron microscopy observations and molecular analyses of mainly the large
subunit (LSU) rDNA. We refer to one species identified as S. dohrnii using LSU rDNA, but as S. marinoi using the small subunit (SSU) rDNA and consequently we use the term S. marinoi-dohrnii complex. This is the first time that S. ardens, S. costatum s.s., and S. pseudocostatum have been recorded in Japan and that S. menzelii and S. tropicum have been identified by molecular methods in Japan. The S. marinoi-dohrnii complex was isolated with high frequency all year-round, and S. japonicum was also isolated with high frequency but not so in summer. S. Tropicum was isolated from September to December, but S. ardens and S. costatum s.s. were isolated only when the water temperature exceeded 20°C. S. pseudocostatum bloomed just once, in summer, but S. menzelii was isolated in May and again in October. The continuous year-round occurrence of S. costatum s.l. in the bay is supported by the succession of these seven species. Six of the species, except S. menzelii, were important components of algal blooms in the bay. One to four species of Skeletonema were isolated every month. Monthly species diversity was higher when S. ardens, S. costatum s.s., and S. tropicum that are usually associated with tropical or subtropical waters, were isolated. In general, species diversity of the genus
Skeletonema was very high in Dokai Bay. 相似文献
73.
Osamu Seki Takeshi Nakatsuka Kimitaka Kawamura Sei-Ichi Saitoh Masaaki Wakatsuchi 《Marine Chemistry》2007,104(3-4):253-265
C37–C39 alkenones were measured in time-series sediment trap samples collected from August 1998 to June 2000 at two depths in the seasonal sea ice region of the western Sea of Okhotsk, off Sakhalin, in order to investigate alkenone production and water-column processes in the region. Measurable export fluxes of alkenones are ranged from < 0.1 to 5.8 μg/m2/day and clearly showed that the alkenone production was restricted to autumn. In 1998, maximum export flux of alkenones occurred in September when surface water column was well stratified with low nutrients in the surface mixing layer. In the next year, the maximum flux is observed in October. Comparison between alkenone temperature and satellite based sea surface temperature (SST) shows that the estimated alkenone temperatures in August 1998 were found to be 10 °C lower than the temporal satellite SST, suggesting that alkenones are produced in surface to subsurface thermocline layers during the period. Annual mean flux of alkenones is lower in the lower traps than that of the upper traps, suggesting rapid degradation of alkenones in water column, but the UK37′ value is not significantly altered. This study indicates that UK37′ values preserved in the surface sediments off Sakhalin reflect the seasonal temperature signal of near surface water, rather than annual mean surface temperature. 相似文献
74.
Stratigraphic architecture of sedimentary basin induced by mantle diapiric upwelling and eustatic event 总被引:1,自引:0,他引:1
The stratigraphic architecture of sedimentary basin provides important constraints on the rheological structure of the upper mantle and the crust, eustatic events and tectonic movements. In this study, we examined the convective coupling between the uppermost mantle and ductile lower crust as a formation mechanism of sedimentary basins. In this mechanism, the lower crust is squeezed by the upper mantle flow associated with mantle diapiric upwelling, resulting in the surface subsidence and formation of sedimentary basin. We investigated the stratigraphic architecture by taking into account the horizontal migration of the upwelling in time and spatial domains. The sedimentary basin is characterized by both the thickness and formation period for its gross feature and the sequence stratigraphy. The decay of the upwelling causes the surface uplift, and some parts of sediments deposited during the surface subsidence are consequently eroded. The subsidence area moves as the activity of upwelling horizontally migrates, resulting in the formation of unconformity for the uplifted and eroded area over the previous upwelling. We also incorporated the effects of third order eustasy, with amplitude of 100 m and period of 1 Myr, into convective coupling model. An application of our model to Karatsu-Sasebo coalfield in the Tertiary of the northwest Kyushu, Japan, indicates that the stratigraphic architecture of sedimentary basin including two effects, i.e. convective coupling and eustasy, may provide important information about the viscosity structure of the lower crust and uppermost mantle and spatio-temporal growth and decay histories of the mantle diapiric upwelling. 相似文献
75.
By means of nanoscale surface observation, we have proposed a new approach for investigating fine crystals of cosmic materials to reveal their origin and growth conditions. Several different morphologies of polyhedral fine olivines with faceted faces have been found in Allende carbonaceous chondrite (4.5 byr in geochronological age). In the present work, molecular level topography of the faceted matrix olivine by Atomic Force Microscopy (AFM) has successfully been performed. The matrix olivine found to have preserved growth step pattern on its surface even though quite long time has passed since they formed in the early Solar System. The surface pattern suggests that the faceted matrix olivine could have been condensed from the gas phase, and possibly that these olivine crystals had continued to grow under a rapid cooling condition (0.1-1 K s−1). The estimated cooling rate agrees well with predictions based on hypothetical rapid heating and cooling events such as shock wave heating. 相似文献
76.
R. Yamada I. Yamada S. Tanaka N. Kobayashi Y. Ishihara K. Yomogida A. Fujimura 《Planetary and Space Science》2009,57(7):751-763
We developed a seismometer system for a hard landing “penetrator” probe in the course of the former Japanese LUNAR-A project to deploy new seismic stations on the Moon. The penetrator seismometer system (PSS) consists of two short-period sensor components, a two-axis gimbal mechanism for orientation, and measurement electronics. To carry out seismic observations on the Moon using the penetrator, the seismometer system has to function properly in a lunar environment after a hard landing (impact acceleration of about 8000 G), and requires a signal-to-noise ratio to detect lunar seismic events. We evaluated whether the PSS could satisfactorily observe seismic events on the Moon by investigating the frequency response, noise level, and response to ground motion of our instrument in a simulated lunar environment after a simulated impact test. Our results indicate that the newly developed seismometer system can function properly after impact and is sensitive enough to detect seismic events on the Moon. Using this PSS, new seismic data from the Moon can be obtained during future lunar missions. 相似文献
77.
Shin Ozawa Eiji Ohtani Masaaki Miyahara Akio Suzuki Makoto Kimura Yoshinori Ito 《Meteoritics & planetary science》2009,44(11):1771-1786
Abstract— The high‐pressure polymorphs of olivine, pyroxene, and plagioclase in or adjacent to shock melt veins (SMVs) in two L6 chondrites (Sahara 98222 and Yamato 74445) were investigated to clarify the related transformation mechanisms and to estimate the pressure‐temperature conditions of the shock events. Wadsleyite and jadeite were identified in Sahara 98222. Wadsleyite, ringwoodite, majorite, akimotoite, jadeite, and lingunite (NaAlSi3O8‐hollandite) were identified in Yamato 74445. Wadsleyite nucleated along the grain boundaries and fractures of original olivine. The nucleation and growth of ringwoodite occurred along the grain boundaries of original olivine, and as intracrystalline ringwoodite lamellae within original olivine. The nucleation and growth of majorite took place along the grain boundaries or fractures in original enstatite. Jadeite‐containing assemblages have complicated textures containing “particle‐like,” “stringer‐like,” and “polycrystalline‐like” phases. Coexistence of lingunite and jadeite‐containing assemblages shows a vein‐like texture. We discuss these transformation mechanisms based on our textural observations and chemical composition analyses. The shock pressure and temperature conditions in the SMVs of these meteorites were also estimated based on the mineral assemblages in the SMVs and in comparison with static high‐pressure experimental results as follows: 13–16 GPa, >1900 °C for Sahara 98222 and 17–24 GPa, >2100 °C for Yamato 74445. 相似文献
78.
Lyα Blobs (LAB), large, extended Lyα emitters, are enigmatic objects that calls on much attention in the field of galaxy formation and evolution. So far, discovery of more than twenty giant (>60 kpc) LABs have been reported and new searches are on-going. Many of the groups who study LABs attended the workshop in Heidelberg, “Understanding Lyα Emitters”, 2008 October 6–10. We had useful discussions on the various important aspects of LABs including the search or detection methods, origins of the extended Lyα emission, and their physical properties. 相似文献
79.
Summary The open-path eddy covariance (EC) method often shows unlikely downward CO2 fluxes in late winter and early spring over drained paddy fields with few active plants. To understand why, we carried out
intensive measurements in a bare paddy field from 9 to 11 April 2003, simultaneously using open- and closed-path EC methods;
aerodynamic and dynamic closed-chamber methods were also used. During this period, the open-path EC method showed downward
daytime CO2 fluxes ranging from 0 to −5.9 μmol m−2 s−1, even after application of the WPL correction (density correction) and ordinary quality control tests. Because the closed-path
EC and aerodynamic methods showed upward CO2 fluxes, the downward CO2 fluxes observed with open-path EC appear not to represent true CO2 transport. Diurnal variations in the downward daytime CO2 fluxes appeared to be correlated with increases in solar radiation during the day, and also with increases in sensible heat
flux in weak winds but not under strongly windy conditions. The daytime 10-Hz time series data of vertical wind and CO2 mixing ratio demonstrated that updrafts were CO2 depleted in the open-path system, whereas the same updrafts were CO2 enriched in the closed-path system. Careful examination of the discrepancies between the open- and the closed-path EC measurements
revealed that the amplitudes of the 10-Hz temperature signals from the sonic anemometer and the resultant sensible heat fluxes
were too small to compensate for the discrepancies observed during the daytime. The open-path EC method with the conventional
application of the WPL correction is not necessarily appropriate for measuring small magnitudes of CO2 flux (≤5 μmol m−2 s−1) under such surface and atmospheric conditions that the magnitude of the WPL correction is as great as that of the uncorrected
CO2 flux itself.
Author’s addresses: Keisuke Ono, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604, Japan; Akira Miyata, Tomoyasu Yamada, National
Institute for Agro-Environmental Sciences, Tsukuba, Japan 相似文献
80.
Gaku Tokuda Akinori Yamada Kazuma Nakano Nao O. Arita & Hideo Yamasaki 《Marine Ecology》2008,29(1):106-114
Deep‐sea hydrothermal vents are unique light‐independent ecosystems that are sustained by chemosynthetic bacteria. For many of the invertebrates inhabiting in such environments, bacteria play essential roles in both energy acquisition and detoxification of potentially toxic gases such as H2S. In this study, the bacterial flora present on the gills of Alvinocaris longirostris (Bresiliidae: Caridea), a shrimp inhabiting hydrothermal vents (1532 m depth) at the Hatoma Knoll of the Okinawa Trough, was investigated. Bacterial 16S rDNA fragments were successfully amplified from the gills and 70% of these fragments showed an identical pattern in the restriction fragment length polymorphism analysis. These fragments were assigned to the ribotype AL‐1. Phylogenetic analyses suggest that AL‐1 forms a monophyletic clade with Sulfurovum spp. (ε‐Proteobacteria). Fluorescence in situ hybridization for AL‐1 and electron microscopy showed the presence of short‐rod bacteria lining up on the cuticular layer of the surface of the gill filaments. These results suggest that bacterial association with gills also occurs in bresiliid shrimps. 相似文献