911 research outputs found

    Distribution, feeding condition, and growth of Japanese Spanish mackerel (Scomberomorus niphonius) larvae in the Seto Inland Sea

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    Distribution of eggs and larvae and feeding and growth of larvae of Japanese Spanish mackerel (Scomberomorus niphonius) were investigated in relation to their prey in the Sea of Hiuchi, the Seto Inland Sea, Japan, in 1995 and 1996. The abundance of S. niphonius eggs and larvae peaked in late May, corresponding with that of clupeid larvae, the major prey organisms of S. niphonius larvae. The eggs were abundant in the northwestern waters and the larvae were abundant in the southern waters in late May in both years, indicating a southward drift during egg and yolksac stages by residual f low in the central part of the Sea of Hiuchi. Abundance of clupeid larvae in southern waters, where S. niphonius larvae were abundant, may indicate a spawning strategy on the part of first-feeding S. niphonius larvae to encounter the spatial and temporal peak in ichthyoplankton prey abundance in the Seto Inland Sea. Abundance of the clupeid larvae was higher in 1995 than in 1996. Feeding incidence (percentage of stomachs with food; 85.3% in 1995 and 67.7% in 1996) and mean growth rate estimated from otolith daily increments (1.05 mm/d in 1995 and 0.85 mm/d in 1996) of S. niphonius larvae in late May were significantly higher in 1995. Young-of-the-year S. niphonius abundance and catch per unit of fishing effort of 1-year-old S. niphonius in the Sea of Hiuchi was higher in 1995, indicating a more successful recruitment in this year. Spatial and temporal correspondence with high ichthyoplankton prey concentration was considered one of the important determinants for the feeding success, growth, and survival of S. niphonius larvae

    Soliton-induced optical absorption of halogen-bridged mixed-valence binuclear metal complexes

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    Employing the one-dimensional single-band extended Peierls-Hubbard model, we investigate optical conductivity for solitonic excitations in halogen-bridged binuclear metal (MMX) complexes. Photoinduced soliton absorption spectra for MMX chains possibly split into two bands, forming a striking contrast to those for conventional mononuclear metal (MX) analogs, due to the broken electron-hole symmetry combined with relevant Coulomb and/or electron-phonon interactions.Comment: to be published in Phys. Rev. B 70, No. 7, August 15 (2004

    Spin of Stellar-Mass Black Holes Estimated by a Model of Quasi-Periodic Oscillations

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    We have proposed in previous papers that the high-frequency pair QPOs observed in black-hole binaries with frequency ratio 3:2 are inertial-acoustic oscillations (nearly horizontal oscillations with no node in the vertical direction) or g-mode oscillations, which are resonantly excited on warped relativistic disks. The resonance occurs through horizontal motions. In this model the dimensionless spin parameter aa_* of the central sources can be estimated when their masses are known from other observations. This estimate is done for three sources (GRO J1665-40, XTE J1550-564, GRS 1915+105). For all of them we have a0.45a_*\leq 0.45.Comment: 12 pages, 6 figures, PASJ 58 (in press

    Optical characterization of platinum-halide ladder compounds

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    New varieties of quasi-one-dimensional halogen (X)-bridged transition-metal (M) complexes, (C_8_H_6_N_4_)[Pt(C_2_H_8_N_2_)X]_2_X(ClO_4_)_3_\cdotH_2_O (X=Br,Cl) and (C_10_H_8_N_2_)[Pt(C_4_H_13_N_3_)Br]_2_Br_4_\cdot2H_2_O, comprising two-leg ladders of mixed-valent platinum ions, are described in terms of a multiband extended Peierls-Hubbard Hamiltonian. The polarized optical conductivity spectra are theoretically reproduced and the ground-state valence distributions are reasonably determined. The latter variety, whose interchain valence arrangement is out of phase, is reminiscent of conventional MX single-chain compounds, while the former variety, whose interchain valence arrangement is in phase, reveals itself as a novel d-p-\pi-hybridized multiband ladder material.Comment: 9 pages, 10 figures. to be published in Phys. Rev. B 76, November 15, No. 1

    Effect of high annealing temperature on giant tunnel magnetoresistance ratio of CoFeB/MgO/CoFeB magnetic tunnel junctions

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    We report tunnel magnetoresistance (TMR) ratios as high as 472% at room temperature and 804% at 5 K in pseudo-spin valve (SV) CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) annealed at 450oC, which is approaching the theoretically predicted value. By contrast, the TMR ratios for exchange-biased (EB) SV MTJs with a MnIr antiferromagnetic layer are found to drop when they are annealed at 450oC. Energy dispersive X-ray analysis shows that annealing at 450oC induces interdiffusion of Mn and Ru atoms into the MgO barrier and ferromagnetic layers in EB-SV MTJs. Mechanisms behind the different annealing behavior are discussed.Comment: 13 pages, 5 figure