6,215 research outputs found
Nuclear incompressibility using the density dependent M3Y effective interaction
A density dependent M3Y effective nucleon-nucleon (NN) interaction which was
based on the G-matrix elements of the Reid-Elliott NN potential has been used
to determine the incompressibity of infinite nuclear matter. The nuclear
interaction potential obtained by folding in the density distribution functions
of two interacting nuclei with this density dependent M3Y effective interaction
had been shown earlier to provide excellent descriptions for medium and high
energy and heavy ion elastic scatterings as well as and heavy
cluster radioactivities. The density dependent parameters have been chosen to
reproduce the saturation energy per nucleon and the saturation density of spin
and isospin symmetric cold infinite nuclear matter. The result of such
calculations for nuclear incompressibility using the density dependent M3Y
effective interaction based on the G-matrix elements of Reid-Elliott NN
potential predicts a value of about 300 MeV for nuclear incompressibility.Comment: 4 Page
Neutron transition strengths of states in the neutron rich Oxygen isotopes determined from inelastic proton scattering
A coupled-channel analysis of the O data has been
performed to determine the neutron transition strengths of 2 states in
Oxygen targets, using the microscopic optical potential and inelastic form
factor calculated in the folding model. A complex density- and \emph{isospin}
dependent version of the CDM3Y6 interaction was constructed, based on the
Brueckner-Hatree-Fock calculation of nuclear matter, for the folding model
input. Given an accurate isovector density dependence of the CDM3Y6
interaction, the isoscalar () and isovector () deformation
lengths of 2 states in O have been extracted from the
folding model analysis of the data. A specific -dependence of
and has been established which can be linked to the
neutron shell closure occurring at approaching 16. The strongest isovector
deformation was found for 2 state in O, with about 2.5
times larger than , which indicates a strong core polarization by the
valence neutrons in O. The ratios of the neutron/proton transition
matrix elements () determined for 2 states in O have
been compared to those deduced from the mirror symmetry, using the measured
values of 2 states in the proton rich Ne and Mg
nuclei, to discuss the isospin impurity in the excitation of the
and isobars.Comment: Version accepted for publication in Physical Review
Union Averaged Operators with Applications to Proximal Algorithms for Min-Convex Functions
In this paper we introduce and study a class of structured set-valued
operators which we call union averaged nonexpansive. At each point in their
domain, the value of such an operator can be expressed as a finite union of
single-valued averaged nonexpansive operators. We investigate various
structural properties of the class and show, in particular, that is closed
under taking unions, convex combinations, and compositions, and that their
fixed point iterations are locally convergent around strong fixed points. We
then systematically apply our results to analyze proximal algorithms in
situations where union averaged nonexpansive operators naturally arise. In
particular, we consider the problem of minimizing the sum two functions where
the first is convex and the second can be expressed as the minimum of finitely
many convex functions
Four complete genome sequences for Bradyrhizobium sp. strains isolated from an endemic Australian Acacia legume reveal structural variation
Bradyrhizobium sp. strains were isolated from root nodules of the Australian legume, Acacia acuminata (Fabaceae). Here, we report the complete genome sequences of four strains using a hybrid long- and short-read assembly approach. The genome sizes range between;7.1Mbp and;8.1Mbp, each with one single circular chromosome. Whole-genome alignments show extensive structural rearrangement
Periodicity of ideals of minors in free resolutions
We study the asymptotic behavior of the ideals of minors in minimal free
resolutions over local rings. In particular, we prove that such ideals are
eventually 2-periodic over complete intersections and Golod rings. We also
establish general results on the stable behavior of ideals of minors in any
infinite minimal free resolution. These ideals have intimate connections to
trace ideals and cohomology annihilators. Constraints on the stable values
attained by the ideals of minors in many situations are obtained, and they can
be explicitly computed in certain cases.Comment: 28 page
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