Record of Cryptopsara couesii GILL (Lophiiformes: Ceratiidae) from off-Kume Island, Ryukyu Islands, Western Japan

深層水取水施設にはしばしば深海生物が迷入するので,深海生物研究の定点観測施設としての意義もある。このたび,深海魚の一種であるミツクリエナガテョウチンアンコウが沖縄県深層水研究所(久米島)で採取された。この深層水取水施設の取水口は久木島沖の東シナ海,水深612mにある。ミツクリエナガチョウチンアンコウの分布域にはまだ不明な点が多いが,本種が東シナ海にまで分布することが初めて分かったので報告する。Facilities for the utilization of deep-sea water often catch deep-sea organisms that stray actively or passively into the influx tubes, and thus provide the chances for long-term in situ collection. Recently, a female specimen of the ceratioid, Cryptopsara couesii, was collected at the Okinawa dee-sea water facility. The inlet has been placed off Kume Island at the water depth of 612 m in the Eastern China Sea. Information about the distribution of C. couesii is only limited, and this finding adds a new geographical record to be archived.原著論

Study of hadron interactions in a lead-emulsion target

Topological and kinematical characteristics of hadron interactions have been studied using a lead-emulsion target exposed to 2, 4 and 10 GeV/c hadron beams. A total length of 60 m $\pi^-$ tracks was followed using a high speed automated emulsion scanning system. A total of 318 hadron interaction vertices and their secondary charged particle tracks were reconstructed. Measurement results of interaction lengths, charged particle multiplicity, emission angles and momenta of secondary charged particles are compared with a Monte Carlo simulation and appear to be consistent. Nuclear fragments emitted from interaction vertices were also detected by a newly developed emulsion scanning system with wide-angle acceptance. Their emission angle distributions are in good agreement with the simulated distributions. Probabilities of an event being associated with at least one fragment track are found to be greater than 50% for beam momentum $P > 4$ GeV/c and are well reproduced by the simulation. These experimental results validate estimation of the background due to hadron interactions in the sample of $\tau$ decay candidates in the OPERA $\nu_{\mu} \to \nu_{\tau}$ oscillation experiment.Comment: 14 pages, 11 figure

VLBI Detections of Parsec-Scale Nonthermal Jets in Radio-Loud Broad Absorption Line Quasars

We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey (SDSS) Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The VLBI instrument we used was developed by the Optically ConnecTed Array for VLBI Exploration project (OCTAVE), which is operated as a subarray of the Japanese VLBI Network (JVN). We aimed at selecting BAL quasars with nonthermal jets suitable for measuring their orientation angles and ages by subsequent detailed VLBI imaging studies to evaluate two controversial issues of whether BAL quasars are viewed nearly edge-on, and of whether BAL quasars are in a short-lived evolutionary phase of quasar population. We detected 20 out of 22 sources using the OCTAVE baselines, implying brightness temperatures greater than 10^5 K, which presumably come from nonthermal jets. Hence, BAL outflows and nonthermal jets can be generated simultaneously in these central engines. We also found four inverted-spectrum sources, which are interpreted as Doppler-beamed, pole-on-viewed relativistic jet sources or young radio sources: single edge-on geometry cannot describe all BAL quasars. We discuss the implications of the OCTAVE observations for investigations for the orientation and evolutionary stage of BAL quasars.Comment: 10 pages, no figure, 3 tables, accepted for publication in PAS