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111.
Keisuke Ishida Yasuyuki Tsujino Takeshi Kozai Tadashi Sato Francis Hirsch 《中国科学D辑(英文版)》2009,52(12):1910-1923
The last appearance datum of the radiolarian Kilinora spiralis is recorded above the first appearance datum of the ammonite Ataxioceras (A.) kurisakense in the Todoro Section of the Kurisaka Formation, Southern Kurosegawa Terrane, Shikoku, SW Japan. The constraint by ammonite
age prolongs the range of the Kilinora spiralis Zone, a remarkable Jurassic radiolarian zone in Japan-NW Pacific region, into the lower Kimmeridgian. The direct correlation
of the Kilinora spiralis zone with the Late Jurassic ammonite faunal succession in the Kurisaka Formation will provide a clue to the still pending
chronological difference between European and North American radiolarian zones. 相似文献
112.
Marine Geophysical Research - After the twenty-first century, the Global Navigation Satellite System-Acoustic ranging (GNSS-A) technique detected geodetic events such as co- and postseismic effects... 相似文献
113.
Napakhwan Whanpetch Masahiro Nakaoka Hiroshi Mukai Takao Suzuki Satoshi Nojima Takashi Kawai Chittima Aryuthaka 《Estuarine, Coastal and Shelf Science》2010
Seagrass beds are susceptible to various natural and human-induced disturbances. Disturbances affect not only seagrasses, but also the abundance and diversity of associated macrofaunal communities. The Andaman Sea coast of Thailand was heavily affected by the tsunami of December 26, 2004. To examine its impact on seagrass macrofaunal communities, we compared the abundance, diversity and taxa composition by quantitative samplings in 2001 (before the tsunami) and in 2005 and 2006 (after the tsunami). Macrobenthic animals and sediments were collected from vegetated and nonvegetated areas of two sites that had received different levels of tsunami disturbances. A large decline in abundance and diversity was observed in the nonvegetated areas after the tsunami, whereas an increase was observed in the vegetated areas. The magnitude of decline and subsequent recovery of abundance and diversity of macrobenthic animals in nonvegetated areas were similar between the two sites, suggesting that their temporal changes were not solely related to the magnitude of the tsunami disturbance. Similarity of the benthic animals differed greatly between 2001 and 2005–2006 at the nonvegetated areas, whereas it varied less among the 3 years at the seagrass-vegetated areas. This study demonstrated that the presence of seagrass vegetation alters the patterns of temporal variation in macrofaunal assemblages and subsequent recovery processes following a tsunami. 相似文献
114.
Tomoyuki Shikata Sou Nagasoe Tadashi Matsubara Yasuhiro Yamasaki Yohei Shimasaki Yuji Oshima Takuji Uchida Ian R. Jenkinson Tsuneo Honjo 《Journal of Oceanography》2008,64(3):355-365
In the present study, we have investigated the conditions influencing encystment and excystment in the dinoflagellate Gyrodinium instriatum under laboratory conditions. We incubated G. instriatum in modified whole SWM-3 culture medium and in versions of modified SWM-3 from which NO3
−, PO4
3−, NO3
− + PO4
3−, or Si had been omitted and observed encystment. Percentage encystment was high in the media without N and without P, while
the percentage encystment in the medium lacking both N and P was highest. Moreover, to investigate N or P concentration which
induced the encystment, Gyrodinium instriatum was also incubated in media with different concentrations of inorganic N and P; the concentrations of NO2
− + NO3
− and PO4
3− were measured over time. The precursors of cysts appeared within 2 or 3 days of a decrease in NO2
− + NO3
− or PO4
3− concentration to values lower than 1 μM or 0.2 μM, respectively. When cysts produced in the laboratory were incubated, we observed excystment after 8–37 days, without a mandatory
period of darkness or low temperature. We incubated cysts collected from nature at different temperatures or in the dark or
light and observed excystments. Natural cysts excysted at temperatures from 10 to 30°C, in both light and dark, but excystment
was delayed at low temperatures. These studies indicate that G. instriatum encysts in low N or P concentration and excysts over a wide temperature range, regardless of light conditions, after short
dormancy periods. 相似文献
115.
Ayako?ShinozakiEmail author Hisako?Hirai Hiroyuki?Kagi Tadashi?Kondo Taku?Okada Daisuke?Nishio-Hamane Shin-ichi?Machida Tetsuo?Irifune Takumi?Kikegawa Takehiko?Yagi 《Physics and Chemistry of Minerals》2012,39(2):123-129
High pressure and temperature reactions of a mixture of forsterite and hydrogen molecules have been carried out using a laser
heated diamond anvil cell at 9.8–13.2 GPa and ~1,000 K. In situ X-ray diffraction measurements showed no sign of decomposition
or phase transitions of the forsterite under these experimental conditions, indicating that the olivine structure was maintained
throughout all runs. However, a substantial expansion of the unit cell volume of the forsterite was observed for samples down
to ~3 GPa upon quenching to ambient pressure at room temperature. The Raman spectroscopy measurements under pressure showed
significant shifts of the Raman peaks of the Si–O vibration modes for forsterite and of the intramolecular vibration mode
for H2 molecules toward a lower frequency after heating. Additionally, no OH vibration modes were observed by Raman and FT-IR spectroscopic
measurements. These lines of evidence show that the observed volume expansion in forsterite is not explained by the incorporation
of hydrogen atoms as hydroxyl, but suggest the presence of hydrogen as molecules in the forsterite structure under these high
pressure and temperature conditions. 相似文献
116.
Polymerizations of organic monomers including amino acids, nucleotides and monosaccharides are essential processes for chemical evolution of life. Since these reactions proceed with “dehydration” reactions, they are possibly promoted if combined with thermodynamically favorable “hydration” reactions of minerals and salts. To test the possibility, we conducted heating experiments of the simplest amino acid “glycine (Gly)” mixed with four simple anhydrous salts (MgSO4, SrCl2, BaCl2 and Li2SO4) at 140 °C up to 20 days. Gly polymerization was strongly promoted by mixing with the salts in the order of MgSO4 > SrCl2 > BaCl2 > Li2SO4. Up to 6-mer of Gly polymers were synthesized in the Gly-MgSO4 mixture, and a total yield of Gly polymers attained about 7% of the initial amount of Gly by the 20 days heating. The total yield was about 200 times larger than that from the heating of Gly alone. XRD measurements of the Gly-MgSO4 mixture revealed the generation of MgSO4 monohydrate during Gly polymerization. These observations indicate that Gly polymerization was promoted by the salt hydrations through the hydration-dehydration interactions. Based on the observations, we tried to find a relationship between thermodynamic characteristics of the interactions and the promotion effects of each salt on Gly polymerization. It was found that the salts having lower hydration ΔrG0 (easier to hydrate) promote Gly polymerization more strongly. The relationship was used to estimate promotion effects of simple oxide minerals on Gly polymerization. The estimations were consistent with previous observations about the effects of these minerals on Gly polymerization. The fact suggests that the hydration-dehydration interactions between amino acids and minerals are an important mechanism for amino acids’ polymerizations on minerals. 相似文献
117.
The role of bedrock groundwater in rainfall–runoff processes is poorly understood. Hydrometric, tracer and subsurface water potential observations were conducted to study the role of bedrock groundwater and subsurface flow in the rainfall–runoff process in a small headwater catchment in Shiranui, Kumamoto prefecture, south‐west Japan. The catchment bedrock consists of a strongly weathered, fractured andesite layer and a relatively fresh continuous layer. Major chemical constituents and stable isotopic ratios of δ18O and δD were analysed for spring water, rainwater, soil water and bedrock groundwater. Temporal and spatial variation in SiO2 showed that stream flow under the base flow condition was maintained by bedrock groundwater. Time series of three components of the rainstorm hydrograph (rainwater, soil water and bedrock groundwater) separated by end member mixing analysis showed that each component fluctuated during rainstorm, and their patterns and magnitudes differed between events. During a typical mid‐magnitude storm event, a delayed secondary runoff peak with 1·0 l s−1 was caused by increase in the bedrock groundwater component, whereas during a large rainstorm event the bedrock groundwater component increased to ≈ 2·5 l s−1. This research shows that the contribution of bedrock groundwater and soil water depends strongly on the location of the groundwater table, i.e. whether or not it rises above the soil–bedrock interface. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
118.
Tadashi Yokoyama 《Planetary and Space Science》2002,50(1):63-77
Due to the tides, the orbits of Phobos and Triton are contracting. While their semi major axes are decreasing, several possibilities of secular resonances involving node, argument of the pericenter and mean motion of the Sun will take place. In the case of Mars, if the obliquity (ε), during the passage through some resonances, is not so small, very significant variations of the inclination will appear. In one case, capture is almost certain provided that ε?20°. For Triton there are also similar situations, but capture seems to be not possible, mainly because in S1 state, Triton's orbit is sufficiently inclined (far) with respect to the Neptune's equator. Following Chyba et al. (Astron. Astrophys. 219 (1989) 123), a simplified equation that gives the evolution of the inclination versus the semi major axis, is derived. The time needed for Triton crash onto Neptune is longer than that one obtained by these authors, but the main difference is due to the new data used here. In general, even in the case of non-capture passages, some significant jumps in inclination and in eccentricities are possible. 相似文献
119.
120.
Proton heating at stream interaction regions in the solar wind is investigated based on the solar wind data obtained by Suisei spacecraft between 0.68 and 1.01 AU from the Sun. The deflection angle of the solar wind flow in the ecliptic plane is used to identify the interaction region. In the solar wind flows coming from east of the Sun in low-speed streams and coming from west in high-speed streams, the radial gradient of proton temperature is flattened owing to heating in the interaction region. From comparison of the best-fitted power law dependence of proton temperature on the radial distance in the deflected flow with that in the non-deflected flow, it is suggested that heating in the interaction regions starts around 0.6–0.7 AU from the Sun. 相似文献