Dynamics of the Magellanic system and the galaxy — Present status of theoretical understanding     

Tadayuki Murai  Mitsuaki Fujimoto 《Astrophysics and Space Science》1986,119(1):169-171

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Dissolution and precipitation processes in deformed amphibolites: an example from the ductile shear zone of the Ryoke metamorphic belt, SW Japan   总被引：2，自引：0，他引：2  

R. Imon  T. Okudaira  A. Fujimoto 《Journal of Metamorphic Geology》2002,20(3):297-308

The granitic mylonite zone in the Cretaceous Ryoke metamorphic belt contains deformed amphibolites as thin layers. The amphibolite layers do not exhibit pinch‐and‐swell or boudinage structures, even when contained in a high‐strain granitic mylonite. This mode of occurrence suggests that they were deformed as much as the surrounding granite mylonite. In the highly deformed zone, strongly foliated amphibolites contain Ti‐rich brown amphibole porphyroclasts rimmed by Ti‐poor green amphibole, titanite and chlorite. These porphyroclasts are elongated, forming shear surfaces defined by preferential distribution of the chlorite and titanite. Porphyroclastic plagioclase in the strongly foliated amphibolites consists of two components: an anorthite‐rich core and an anorthite‐poor rim. Based on these observations, the mass‐balanced reaction occurring during deformation is defined as As the reaction products form a weak interconnected matrix, the strain rate of the amphibolites may be controlled by the rate of dissolution–precipitation through fluids. Weakly foliated amphibolites in the low‐strain zone exhibit cataclastic microstructures, whereas the strongly foliated amphibolites do not exhibit such features. These microstructural and chemical changes suggest that high‐strain amphibolites were initially deformed by cataclasis, followed by deformation through metamorphic reactions. During the metamorphism/deformation, old plagioclase grains with high X_an were not stable and dissolved, and new plagioclase grains with low X_an crystallized at the old plagioclase rim. Dissolution of old plagioclase and precipitation of new plagioclase occurred normal to and parallel to the foliation, respectively, reflecting incongruent pressure solution due to differential stress and changes in P–T–H₂O conditions. The development of incongruent pressure solution is attributed to increased fluid flux in the strongly foliated amphibolites, as evidenced by the greater abundance of hydration‐reaction products in the strongly foliated amphibolites than in the weakly foliated ones.  相似文献   

On the sensitivity characteristics of Lacoste & Romberg gravimeter (model G)     

Ichiro Nakagawa  Sinzi Nakai  Ryūichi Shichi  Hirokazu Tajima  Sadakatu Izutuya  Yoshiteru Kono  Toshihiro Higashi  Hiromi Fujimoto  Makoto Murakami  Kazuo Tajima  Minoru Funaki 《Journal of Geodesy》1985,59(1):55-67

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Anomalous deformation of the Earth's bow shock in the lunar wake: Joint measurement by Chang’E-1 and SELENE     

Masaki N. Nishino  Xiao-Dong Wang  Masaki Fujimoto  Hideo Tsunakawa  Yoshifumi Saito  Shoichiro Yokota  Wei Bian  Chun-Lai Li  Masaki Matsushima  Hidetoshi Shibuya  Hisayoshi Shimizu  Futoshi Takahashi  Toshio Terasawa 《Planetary and Space Science》2011,59(5-6):378-386

Because the solar wind (SW) flow is usually super-sonic, a fast-mode bow shock (BS) is formed in front of the Earth's magnetosphere, and the Moon crosses the BS at both dusk and dawn flanks. On the other hand, behind of the Moon along the SW flow forms a tenuous region called lunar wake, where the flow can be sub-Alfvénic (and thus sub-sonic) because of its low-density status. Here we report, with joint measurement by Chang’E-1 and SELENE, that the Earth's BS surface is drastically deformed in the lunar wake. Despite the quasi-perpendicular shock configuration encountered at dusk flank under the Parker-spiral magnetic field, no clear shock surface can be found in the lunar wake, while instead gradual transition of the magnetic field from the upstream to downstream value was observed for a several-minute interval. This finding suggests that the ‘magnetic ramp’ is highly broadened in the wake where a fast-mode shock is no longer maintained due to the highly reduced density. On the other hand, observations at the 100 km altitude on the dayside show that the fast-mode shock is maintained even when the width of the downstream region is smaller than a typical scale length of a perpendicular shock. Our results suggest that the Moon is not so large to eliminate the BS at 100 km altitude on the dayside, while the magnetic field associated with the shock structure is drastically affected in the lunar wake.  相似文献   

Effects of hillslope topography on runoff response in a small catchment in the Fudoji Experimental Watershed,central Japan     

Masamitsu Fujimoto  Nobuhito Ohte  Makoto Tani 《水文研究》2011,25(12):1874-1886

We investigated the role of different hillslope units with different topographic characteristics on runoff generation processes based on field observations at two types of hillslopes (0·1 ha): a valley‐head (a convergent hillslope) and a side slope (a planar hillslope), as well as at three small catchments having two types of slopes with different drainage areas ranging from 1·9 to 49·7 ha in the Tanakami Mountains, central Japan. We found that the contribution of the hillslope unit type to small catchment runoff varied with the magnitude of rainfall. When the total amount of rainfall for a single storm event was < 35 mm, runoff in the small catchment was predominantly generated from the side slope. As the amount of rainfall increased (>35 mm), the valley‐head also began to contribute to the catchment runoff, adding to runoff from the side slope. Although the direct runoff from the valley‐head was greater than that from the side slope, the contribution from the side slope was quantitatively greater than that from the valley‐head due to the proportionally larger area occupied by the side slope in the small catchment. The storm runoff responses of the small catchments reflected the change in the runoff components of each hillslope unit as the amount of rainfall increased and rainfall patterns changed. However, similar runoff responses were found for the small catchments with different areas. The similarity of the runoff responses is attributable to overlay effects of different hillslope units and the similar composition ratios of the valley‐head and side slope in the catchments. This study suggests that the relative roles of the valley‐head and side slope are important in runoff generation and solute transport as the catchment size increases from a hillslope/headwater to a small catchment. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Quick triggering of magnetic reconnection in magnetotail     

Iku Shinohara  Kenny G. Tanaka  Masaki Fujimoto 《Earth, Moon, and Planets》2007,100(3-4):225-232

Recently, quick triggering of magnetic reconnection (QMRT) even in an ion-scale current sheet is found to be possible with the help of the nonlinear evolution of the lower hybrid drift instability (LHDI). The details of the QMRT mechanism are reviewed mostly based on three-dimensional full-particle simulation results of our group. QMRT is mediated by LHDI and its time scale is comparable to the saturation time scale of LHDI. Depending on the initial current sheet thickness, two types of QMRT, so-called Type-I and Type-II QMRT, are demonstrated.  相似文献   

江豚的分娩及相关行为观察   总被引：4，自引：0，他引：4  

杨健  张先锋  堀由纪子  藤本朝海 《海洋与湖沼》1998,29(1):41-46

于１９９３年４月１０日,在日本江之岛水族馆,江豚顺利分娩,对其分娩过程,以及与之相关的呼吸,活动行为进行较详细的观察和研究,结果表明,母豚将小母豚发尾部生以占分娩的绝大部分时间,分娩后期段平均呼吸频率减缓,游动速度放慢,水面活动增多,并趋于单独活动,此外,还记录到母豚的喷水,跳水,收腹,摆尾,转游等分娩时的特殊行为及出生后幼豚的行为。  相似文献   

Sediment and carbon storages in the Yahagi River Delta during the Holocene,central Japan     

Kiyoshi Fujimoto  Kumiko Kawase  Shigehiro Ishizuka  Koji Shichi  Akio Ohira  Hiroshi Adachi 《Quaternary Science Reviews》2009,28(15-16):1472-1480

We estimated stored sediment and carbon during the Holocene for each layer of the Yahagi River Delta, central Japan and discussed the provenance of stored carbon. To estimate the bulk density and the carbon content of each layer, we collected two 30 m deep undisturbed cores. The volume of each layer was calculated using ArcView 3D analyst. Although the volume ratio of each layer to the total volume was calculated to be 9.5% for the top mud layer, 34.9% for the upper sand layer, 32.8% for the middle mud layer and 22.9% for the lower sand layer, the mass ratio of each layer to the total mass was calculated to be 8.5, 40.9, 25.2 and 25.4%, respectively, and the stored carbon ratio in each layer to the total stored carbon was 20.4, 4.7, 55.9 and 18.9%, respectively. These results suggest that the top mud and middle mud layers have a significant role as a place for carbon sequestration during postglacial time. Total stored carbon in the study area of only 92.1 km² was estimated at 26 Tg C, which is equivalent to 0.003% of atmospheric carbon. This suggests that deltas on the globe have accumulated a massive amount of carbon during the evolution. The inorganic carbon ratio to total carbon reached more than 45% around the boundary between the middle mud and lower sand layers. The increasing trend in the C_org/N_total ratio accompanied with a decrease in δ¹³C from the bottom to the top horizon in the middle mud layer indicates a gradual increase in terrestrial organic matter contribution. The relative proportion of terrestrially derived materials decreases with increasing distance seaward.  相似文献   

On the feasibility of characterizing jovian auroral electrons via H3+ infrared line-emission analysis     

Chihiro Tao  Sarah V. Badman  Takeru Uno  Masaki Fujimoto 《Icarus》2012,221(1):236-247

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Cross-scale: multi-scale coupling in space plasmas     

Steven J. Schwartz  Timothy Horbury  Christopher Owen  Wolfgang Baumjohann  Rumi Nakamura  Patrick Canu  Alain Roux  Fouad Sahraoui  Philippe Louarn  Jean-André Sauvaud  Jean-Louis Pinçon  Andris Vaivads  Maria Federica Marcucci  Anastasios Anastasiadis  Masaki Fujimoto  Philippe Escoubet  Matt Taylor  Steven Eckersley  Elie Allouis  Marie-Claire Perkinson 《Experimental Astronomy》2009,23(3):1001-1015

Most of the visible universe is in the highly ionised plasma state, and most of that plasma is collision-free. Three physical phenomena are responsible for nearly all of the processes that accelerate particles, transport material and energy, and mediate flows in systems as diverse as radio galaxy jets and supernovae explosions through to solar flares and planetary magnetospheres. These processes in turn result from the coupling amongst phenomena at macroscopic fluid scales, smaller ion scales, and down to electron scales. Cross-Scale, in concert with its sister mission SCOPE (to be provided by the Japan Aerospace Exploration Agency—JAXA), is dedicated to quantifying that nonlinear, time-varying coupling via the simultaneous in-situ observations of space plasmas performed by a fleet of 12 spacecraft in near-Earth orbit. Cross-Scale has been selected for the Assessment Phase of Cosmic Vision by the European Space Agency.   相似文献