Achnanthidium delmontii sp. nov., a new species from French rivers

A new freshwater diatom species belonging to the genus Achnanthidium Kütz. has been found in several French rivers namely those of the Languedoc–Roussillon and Rhin–Meuse regions. Achnanthidium delmontii sp. nov. is described based on light and scanning electron microscopy observations. This species belongs to the group of Achnanthidium taxa with terminal raphe fissures curved to the same side of the valve and it is compared to the most related species: Achnanthidium pfisteri Lange–Bertalot, Achnanthidium pyrenaicum (Husdedt) Kobayasi, Achnanthidium temniskovae Ivanov et Ector and Achnanthidium zhakovschikovii Potapova. The assessment of its ecology was made through physicochemical analysis carried out on sites which are part of water quality monitoring networks. Some comments are made on the rapid expansion of Achnanthidium delmontii sp. nov

Collective Path Connecting the Oblate and Prolate Local Minima in 68Se

By means of the adiabatic self-consistent collective coordinate method and the pairing plus quadrupole interaction, we have obtained the selfconsistent collective path connecting the oblate and prolate local minima in 68Se for the first time. Along the collective path, the triaxial deformation parameter (gamma) changes between 0 and 60 (degree) keeping the axially symmetric deformation parameter (beta) approximately constant, indicating the importance of triaxial deformation dynamics in the oblate-prolate shape coexistence phenomena.Comment: 6 pages including 6 eps figure

Application of the Adiabatic Selfconsistent-Collective-Coordinate Method to a Solvable Model of Prolate-Oblate Shape Coexistence

The adiabatic selfconsistent collective coordinate method is applied to an exactly solvable multi-O(4) model which simulates nuclear shape coexistence phenomena. Collective mass and dynamics of large amplitude collective motions in this model system are analysed, and it is shown that the method can well describe the tunneling motions through the barrier between the prolate and oblate local minima in the collective potential. Emergence of the doublet pattern is well reproduced.Comment: 25 pages including 9 figure

Collective Paths Connecting the Oblate and Prolate Shapes in 68Se and 72Kr Suggested by the Adiabatic Self-Consistent Collective Coordinate Method

By means of the adiabatic self-consistent collective coordinate method and the pairing-plus-quadrupole interaction, we have obtained the self-consistent collective path connecting the oblate and prolate local minima in 68Se and 72Kr for the first time. The self-consistent collective path is found to run approximately along the valley connecting the oblate and prolate local minima in the collective potential energy landscape. This result of calculation clearly indicates the importance of triaxial deformation dynamics in oblate-prolate shape coexistence phenomena.Comment: 24 pages including 5 figure