Shozo Mihara

Clues to the cause of the Tsushima leopard cat ( Prionailurus bengalensis euptilura ) decline from isotopic measurements in three species of Carnivora

The estimated population of the Tsushima leopard cat Prionailurus bengalensis euptilura is only 80–110 individuals. However, the cause of the population decline is not clear. We investigated temporal changes in the food habits of the cat and two other species of Carnivora (marten and weasel) inhabiting the Tsushima Islands by measuring δ13C and δ15N values in hair samples. Hair samples of the cat were collected not only from specimens and furs, but also from feces. The gathering of hair from cat feces was most efficient when the feces were collected in the spring. The food habit of male cats seemed to be more diverse and tended to comprise prey of higher trophic levels than the food habits of the females. The δ13C and δ15N measurements suggested that the trophic level of the food sources has been decreasing over the last several decades for the cat and weasel, but not for the marten. Increased consumption of prey from lower trophic levels in the food habit of the cat seems to be related to the decline of the cat population because these phenomena occurred simultaneously.

Depth Profile of Radioactivity Induced in the Thick Concrete Shield in EP1 Beam Line at the KEK 12-GeV Proton Synchrotron Facility

Abstract The evaluation of radioactivity induced in the concrete shield is important for the decommissioning of accelerator facilities. Specific activities of gamma-ray emitters of nuclear spallation products and thermal neutron capture products and beta-ray emitters such as tritium and 14C, and 36Cl in the concrete shield along the 12-GeV proton beam line (EP1 beam line, High Energy Accelerator Research Organization) were determined. The depth profiles of the radioactivity of each nuclide in the 6-m-thick concrete shield of the beam lines were compared, and the secondary particles and induced nuclear reactions were discussed.