Spin-other-orbit operator in the tensorial form of second quantization

The tensorial form of the spin-other-orbit interaction operator in the formalism of second quantization is presented. Such an expression is needed to calculate both diagonal and off-diagonal matrix elements according to an approach, based on a combination of second quantization in the coupled tensorial form, angular momentum theory in three spaces (orbital, spin and quasispin), and a generalized graphical technique. One of the basic features of this approach is the use of tables of standard quantities, without which the process of obtaining matrix elements of spin-other-orbit interaction operator between any electron configurations is much more complicated. Some special cases are shown for which the tensorial structure of the spin-other-orbit interaction operator reduces to an unusually simple form

Isoscalar Hamiltonians for light atomic nuclei

The charge-dependent realistic nuclear Hamiltonian for a nucleus, composed of neutrons and protons, can be successfully approximated by a charge-independent one. The parameters of such a Hamiltonian, i.e., the nucleon mass and the NN potential, depend upon the mass number A, charge Z and isospin quantum number T of state of the studied nucleus.Comment: REVTeX, 22 pages, 3 eps figures, to appear in PR

New Poropanchax from D.R. Congo.

12 pages : illustrations (some color), color map ; 26 cm.A new procatopodid, assigned to the genus Poropanchax, is described from a wetland habitat located adjacent to the Inga Falls in Lower Congo. Poropanchax pepo, new species, is distinguished from all congeners by a combination of characters including a higher D/A ratio, rounded anal and dorsal fins, a humeral blotch in males, and the absence of a sharp ventral process on the basipterygium. The finding of a Poropanchax species in Lower Congo was unexpected, since the closest known congeneric population is located in northwestern Gabon, some 700 kilometers to the north. As recognized herein the genus Poropanchax is a clade comprised of five species geographically restricted to humid coastal regions of west and west-central Africa