Low-Lying Electric Dipole Transitions in Tin Isotopic Chain within the RPA Model

International audienceA nuclear structuremodel based on a finite rank approximation of Skyrme interaction is applied to calculate the distribution of dipole strength in tin isotopes. The model is based on the quasiparticle random phase approximation. The results obtained with the three types of parametrizations of the Skyrme forces (SLy4, SkM∗, and SIII) are compared. The low-lying part of dipole strength distribution reveals the existence of a group of slightly collective states, and the corresponding E1 transition strength increases with the enlargement of neutron excess. The group is associated with the pygmy resonance

Structure of the low-lying states in some N=80 isotones

International audienceThe quasiparticle-phonon model using a separable interaction deduced from a Skyrme force is adopted to compute low-lying spectra and the giant dipole resonance in the N = 80 isotones. It is shown that the Skyrme interaction not only reproduces the fragmentation of the giant resonance but also yields results comparable to the ones obtained when a Woods-Saxon potential is used in the description of the mixed symmetry states recently discovered in these nuclei. This test is encouraging in view of future extensions of the method to neutron-rich nuclei far from stability

Long-acting contraceptive agents: Norethisterone esters of polyunsaturated acids

8 pages, 1 scheme.-- PMID: 6658875 [PubMed].Some new derivatives of norethisterone (17α-ethynyl-17β-hydroxyestr-4-en-3-one) are described in which the 17β-hydroxyl group of the steroid is esterified with polyunsaturated aliphatic acids. The potential of these compounds as long-acting contraceptive agents has been evaluated.The authors thank the Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, for financial support for this work

Effects of phonon-phonon coupling on properties of pygmy resonance in 124-132Sn

Starting from an effective Skyrme interaction we study effects of phonon-phonon coupling on the low-energy electric dipole response in 124-132Sn. The QRPA calculations are performed within a finite rank separable approximation. The inclusion of two-phonon configurations gives a considerable contribution to low-lying strength. Comparison with available experimental data shows a reasonable agreement for the low-energy E1 strength distribution

Long-acting contraceptive agents: Levonorgestrel esters of unsaturated acids

10 pages, 1 scheme.-- Available online 10 January 2003.Esters of levonorgestrel (13β-ethyl-17β-ethynyl-17β-hydroxygon-4-en-3-one) with a variety of unsaturated carboxylic acids have been synthesized for evaluation as potential long-acting, injectable contraceptive agents.The authors thank the World Health Organization for financial support of this work