Three-body problem     

Christian Marchal  Junzo Yoshida  Sun Yi-Sui 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):65-93

In the first part of this paper [Marchal, Yoshida, Sun Yi-Sui 1985] we have analyzed three-body systems satisfying the condition rkR where k is a suitable constant, r the mutual distance of the two masses of the binary and R the distance between the center of mass of the binary and the third mass.That condition rkR puts limits on the acceleration of the third mass and these limits allow us to determine the corresponding escape velocities.In this second part we look for initial conditions under which the inequality rkR will remain forever satisfied and we develop the corresponding tests of escape and their applications.This leads to a major improvement of the knowledge of the nature of three-body motions especially in the vicinity of triple close approaches.The region of bounded motions is much smaller than was generally expected and numerical computations of particular solutions show that we approach very near to the true limit.  相似文献   

Characterization of water quality variation in the Mekong River at Vientiane by frequent observations     

Toshiaki Iida  Somphone Inkhamseng  Koshi Yoshida  Hajime Tanji 《水文研究》2011,25(23):3590-3601

To better understand the variation of water quality in the Mekong River, sampling and measurement were scheduled twice a week for about 3 years at Vientiane, followed by basic statistical analysis of the observed data. The frequent measurement revealed detailed characteristics of the water quality variation, which had not been detected by monthly observation in the previous studies. The variation in total ionic content was considered to be governed by dilution of the amount of water. Increases in turbidity could be attributed to physical effects including surface soil erosion and bed material resuspension at the time of discharge increase. Nitrogen concentrations were stably low during the low flow period and abruptly increased in May. After the annual maximum in late May, the nitrate concentration steadily decreased regardless of the remarkable rise in the discharge from mid‐July, whereas the ammonium concentration remained at a similar level until October. It was considered that the first small discernable runoff after the long dry season flushed the accumulated nitrogen in the surface soil and mobilized the nitrogen in the riverbed. The variation in phosphorus concentrations was different from that in nitrogen concentrations. During the high flow period, continual dilutions at discharge peaks and occasional large additions of phosphorus by surface runoff were suggested. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Large kinetic power in FRII radio jets     

Hirotaka Ito  Motoki Kino  Nozomu Kawakatu  Naoki Isobe  Shoichi Yamada 《Astrophysics and Space Science》2007,311(1-3):335-339

We investigate the total kinetic powers (L _j) and ages (t _age) of powerful jets of four FR II radio sources (Cygnus A, 3C 223, 3C 284, and 3C 219) by the detail comparison of the dynamical model of expanding cocoons with observed ones. It is found that these sources have quite large kinetic powers with the ratio of L _j to the Eddington luminosity (L _Edd) resides in 0.02<L _j/L _Edd<10. Reflecting the large kinetic powers, we also find that the total energy stored in the cocoon (E _c) exceed the energy derived from the minimum energy condition (E _min): 2<E _c/E _min<160. This implies that a large amount of kinetic power is carried by invisible components such as thermal leptons (electron and positron) and/or protons.  相似文献   

The continuous limit of the multiple lens effect and the optical scalar equation     

Hiroshi Yoshida  Kouji Nakamura  Minoru Omote 《Monthly notices of the Royal Astronomical Society》2005,358(1):39-48

We study the continuous limit of the multiple gravitational lensing theory based on the thin lens approximation. We define a new, light-path dependent angular diameter distance     and show that it satisfies the optical scalar equation. The distance provides relations between quantities used in gravitational lensing theory (the convergence, the shear and the twist terms) and those used in scalar optics theory (the rates of expansion, shear and rotation).  相似文献   

High inorganic phosphate concentration in coral mucus and its utilization by heterotrophic bacteria in a Malaysian coral reef          下载免费PDF全文

Ryota Nakajima  Yasuaki Tanaka  Teruaki Yoshida  Tamami Fujisawa  Asami Nakayama  Yumi Fuchinoue  Bin Haji Ross Othman  Tatsuki Toda 《Marine Ecology》2015,36(3):835-841

Inorganic nutrient contents of mucus released by Acropora corals and its utilization by heterotrophic bacteria at several different hour intervals in the coral mucus were investigated at a coral reef in Malaysia. The dissolved inorganic phosphate (DIP) concentration was 135‐fold higher than in the ambient seawater, probably due to inorganic P release from the coral gut cavity. We experimentally confirmed that heterotrophic bacteria rapidly (within 8 h) consumed ca. 80% of the initial concentration of DIP derived from coral mucus. High DIP concentration in coral mucus may enhance heterotrophic bacterial production and associated carbon flow in the microbial loop of reef ecosystems.  相似文献   

Nucleosynthesis of ⁵⁶Ni in wind-driven supernova explosions and constraints on the central engine of gamma-ray bursts     

Keiichi Maeda  Nozomu Tominaga 《Monthly notices of the Royal Astronomical Society》2009,394(3):1317-1324

Theoretically expected natures of a supernova (SN) driven by a wind/jet are discussed. Approximate analytical formulations are derived to clarify basic physical processes involved in the wind/jet-driven explosions, and it is shown that the explosion properties are characterized by the energy injection rate     and the mass injection rate     . To explain observations of Supernova 1998bw associated with gamma-ray burst (GRB) 980425, the following conditions are required:     and     (if the wind Lorentz factor  Γ_w∼ 1  ) or     (if  Γ_w≫ 1  ). In Supernova 1998bw, ⁵⁶Ni  (∼0.4 M_⊙)  is probably produced in the shocked stellar mantle, not in the wind. The expected natures of SNe, e.g. ejected ⁵⁶Ni mass and ejecta mass, vary depending on     and     . The sequence of the SN properties from high     and     to low     and     is as follows: Supernova 1998bw-like – intermediate case – low mass ejecta  (≲1 M_⊙)  where ⁵⁶Ni is from the wind – whole collapse. This diversity may explain the diversity of SNe associated with GRBs. Our result can be used to constrain natures of the wind/jet, which are linked to the central engine of GRBs, by studying properties of the associated SNe.  相似文献   

Kolmogorov dissipation scales in weakly ionized plasmas     

V. Krishan  Z. Yoshida 《Monthly notices of the Royal Astronomical Society》2009,395(4):2039-2044

In a weakly ionized plasma, the evolution of the magnetic field is described by a 'generalized Ohm's law' that includes the Hall effect and the ambipolar diffusion terms. These terms introduce additional spatial and time-scales which play a decisive role in the cascading and the dissipation mechanisms in magnetohydrodynamic turbulence. We determine the Kolmogorov dissipation scales for the viscous, the resistive and the ambipolar dissipation mechanisms. The plasma, depending on its properties and the energy injection rate, may preferentially select one of these dissipation scales, thus determining the shortest spatial scale of the supposedly self-similar spectral distribution of the magnetic field. The results are illustrated taking the partially ionized part of the solar atmosphere as an example. Thus, the shortest spatial scale of the supposedly self-similar spectral distribution of the solar magnetic field is determined by any of the four dissipation scales given by the viscosity, the Spitzer resistivity (electron–ion collisions), the resistivity due to electron–neutral collisions and the ambipolar diffusivity. It is found that the ambipolar diffusion dominates for reasonably large energy injection rate. The robustness of the magnetic helicity in the partially ionized solar atmosphere would facilitate the formation of self-organized vortical structures.  相似文献   

The Charnockite — A-type Granitoid — Charnockite Cycle in Southwestern India     

H.M. Rajesh  M. Yoshida 《Gondwana Research》2001,4(2):187

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Geology and geochemistry of lavas at Nekoma volcano: Implications for origin of Quaternary low-K andesite in the north-eastern Honshu arc, Japan   总被引：4，自引：0，他引：4  

Jun-Ichi Kimura  Tomoyuki Tanji  Takeyoshi Yoshida  Shigeru Iizumi 《Island Arc》2001,10(2):116-134

Abstract Nekoma volcano forms part of the arc axis volcanic array of the North-eastern Honshu arc, Japan, which is commonly characterized by medium-K lava suites. However, Nekoma is exceptional because many of its lavas are low-K. This anomaly has been a matter of debate. Nekoma was active from 1.1 to 0.35 Ma. The volcano consists of thick andesite flows and domes associated with block and ash flow deposits produced during lava dome formation. A horseshoe-shaped collapse caldera was formed at the summit and small lava domes extruded into the caldera. Stratigraphy, published K–Ar ages, and tephrochronology define three stages of volcanic activity, about 1.1 Ma (Stage 1), 0.8–0.6 Ma (Stage 2) and 0.45–0.35 Ma (Stage 3; post caldera stage). Low-K andesites occur in all stages. Extremely low-K andesite was also associated in Stage 2 and medium-K andesite was dominant in Stage 3. In general, lavas changed from low-K to medium-K after caldera formation. Geochemical study of the Nekoma lavas shows that both low-K and medium-K lavas are isotopically similar and were derived from a common source. Adatara and Azuma volcanoes, which lie close to Nekoma, also have both low-K and medium-K andesites. However, Sr isotope ratios or temporal-spatial variations in K-level lava classification vary between the three centers. Comparisons of K suites and Sr isotope ratios with frontal arc volcanoes in North-east–Honshu suggest source heterogeneity existed in both medium- and low-K suites. The K contents of lavas and their Sr isotopes are not simply related. This requires re-examination of models for chemical variation of andesites in arcs.  相似文献   

On the mechanism of the olivine-spinel phase transformation     

Nozomu Hamaya  Syun-iti Akimoto 《Physics of the Earth and Planetary Interiors》1982,29(1):6-11

Recent experiments on the olivine-spinel phase transformation in Ni₂SiO₄ have provided the following fundamental results: (1) the interphase structural orientation relationships with $\text{(100)}{}_{\mathrm{<mtext>ol</mtext>}}\text{|(111)}{}_{\mathrm{<mtext>sp</mtext>}}\text{and}\text{[001]}{}_{\mathrm{<mtext>ol</mtext>}}\text{|[}\text{1}\text{10]}{}_{\mathrm{<mtext>sp</mtext>}}$ between the olivine and spinel phases upon transformation; and (2) the growth of 300 μm spinel single crystal from single crystals of olivine. In the light of these observations, transformation mechanisms proposed have been compared. We conclude that neither a nucleation and growth model nor a martensite model is verified by the experimental results. The former model lacks consistency in terms of the interphase relationships, and the latter cannot offer a dislocation-multiplication mechanism for the growth process.  相似文献