16 research outputs found

    Diet of the mesopelagic fish Notoscopelus japonicus (Family: Myctophidae) associated with the continental slope off the Pacific coast of Honshu, Japan

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    The diet of Notoscopelus japonicus, one of the dominant mesopelagic fishes in the transitional waters of the western North Pacific, was examined in 106 specimens collected over the continental slope off the Pacific coast of northern Japan during April and October 1996. The prey comprised mainly crustaceans, such as copepods, ostracods, euphausiids and amphipods. Euphausia pacifica was the dominant prey, representing 83.1% by number and 72.4% by wet weight of the total diet. Between April and October, there was no shift in prey species consumed, but prey size decreased significantly and prey number per fish stomach increased in October. These results indicate that, in October, N. japonicus consumed larger numbers of smaller E. pacifica, rather than shifting to other prey taxa. The pronounced importance of E. pacifica in the diet was ascribed to its co-occurrence with N. japonicus at night in the surface layer and during the daytime in the near-bottom layer

    Electron transfer and decay processes of highly charged iodine ions

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    In the present experimental work we have investigated multi-electron transfer processes in Iq+ (q = 10, 15, 20 and 25) + Ne, Ar, Kr and Xe collisions at 1.5q keV energy. Using the coincidence technique between charge-selected projectile and recoil ions, the branching ratios between Auger and radiative decay channels have been measured in decay processes of multiply excited states formed by multi-electron transfer collisions. By combining these ratios with the measured absolute cross sections for total and single electron transfer processes, the partial cross sections for various charge changing processes have been determined. It has been shown that, in all the multi-electron transfer processes investigated, the Auger decays are far dominant over the radiative decay processes and the branching ratios are clearly characterized by the average principal quantum number <n> of the initial excited states of projectile ions, estimated from the extended classical-over-barrier-model (ECBM). We could express the branching ratios in high Rydberg states formed in multi-electron transfer processes by using the decay probability of one Auger electron emission
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