Extension of random-phase approximation preserving energy weighted sum rules: an application to a 3-level Lipkin model

A limitation common to all extensions of random-phase approximation including only particle-hole configurations is that they violate to some extent the energy weighted sum rules. Considering one such extension, the improved RPA (IRPA), already used to study the electronic properties of metallic clusters, we show how it can be generalized in order to eliminate this drawback. This is achieved by enlarging the configuration space, including also elementary excitations corresponding to the annihilation of a particle (hole) and the creation of another particle (hole) on the correlated ground state. The approach is tested within a solvable 3-level model.Comment: 2 figure

Fully-Renormalized QRPA fulfills Ikeda sum rule exactly

The renormalized quasiparticle-RPA is reformulated for even-even nuclei using restrictions imposed by the commutativity of the phonon creation operator with the total particle number operator. This new version, Fully-Renormalized QRPA (FR-QRPA), is free from the spurious low-energy solutions. Analytical proof is given that the Ikeda sum rule is fullfiled within the FR-QRPA.Comment: 9 page

Self-Consistent Quasi-Particle RPA for the Description of Superfluid Fermi Systems

Self-Consistent Quasi-Particle RPA (SCQRPA) is for the first time applied to a more level pairing case. Various filling situations and values for the coupling constant are considered. Very encouraging results in comparison with the exact solution of the model are obtained. The nature of the low lying mode in SCQRPA is identified. The strong reduction of the number fluctuation in SCQRPA vs BCS is pointed out. The transition from superfluidity to the normal fluid case is carefully investigated.Comment: 23 pages, 18 figures and 1 table, submitted to Phys. Rev.

Mineralogy of the pliocene trachyte and its carbonatitic minette inclusions in Ostrvica, FYR of Macedonia

The trachyte at Ostrvica hill (age 3.21±0.10 Ма) in Vardar zone is the most evolved volcan- ics of the ultrapotassic Pliocene-Quaternary series in F.Y.R. of Macedonia. It is aphyric, with clinopy- roxene and phlogopite microphenocrysts within a sanidine-anorthoclase groundmass. It contains inclu- sions of carbonatitic minette ranging in size from several mm to 6–7 cm. They are light coloured por- phyric rocks, rich in vacuoles, composed of phlogopite and completely altered olivine(?) phenocrysts amongst acicular clinopyroxenes within a feldspar–calcite groundmass with abundant Fe-oxides and acicular apatite microlites. The inclusions are rimmed by a mm thick mixing zone composed of the same minerals but with intermediate composition between that of minette and trachyte. The clinopyroxenes are mainly diopside-augite with low Ti and Al content (with 6Al only in the minette). Positive correla- tions are observed between Na and Fe3+, Al and Ti, and negative one – between Al and Si. In the inclu- sions phlogopites the negative correlation between Mg# and 4Al is found. The feldspars in the trachyte and minette inclusions are Ca-sanidine to Ca-anorthoclase, in the mixing zone – sanidine only. In the in- clusions two plagioclase generations (An41 and An25) exist. The estimated crystallization temperature of the minette clinopyroxenes is 1280–1180С, of plagioclase (An41) – 1130С and in the hosting trachyte – 1080С, at the pressures 6.9 and 7.7 kbar, respectively. The temperature of the feldspars crystalliza- tion (K-Na-feldspars and Pl24) in the minette groundmass is 809–878C. By analogy with other ultrapo- tassic volcanics from F.Y.R Macedonia it is suggested, that the discussed volcanics originated from phlogopite-bearing metasomatised mantle

Determination of the trace element content in Bulgarian bottled potable waters by total reflection X-ray fluorescence analysis

The content of S, Cl, K, Ca, Mn, Fe, Ni, Cu, Zn, As, Br, Rb and Ba in several brands of Bulgarian bottled potable waters ("Savina" table, "Gorna Banya" mineral, "Bankya" mineral, "Kom" mineral, "Thorn Spring" mineral, "Hissar" mineral, "Devin" spring and mineral and "Mihalkovo" spring and mineral) was determined by total reflection X-ray fluorescence (TXRF) analysis using gallium as internal standard. The spring waters generally displayed lower mineralization (total dissolved solids, TDS content) than the mineral waters, even those originating from the same location. The content of S, Cl, K and Ca was at the mg L -1 level, while that of Mn, Fe, Ni, Cu, Zn, As, Br, Rb and Baat the lower µg L -1 level. The trace element content of the mineral waters did not considerably change (less than ±30 % difference) over a storage period of approx. 2.5 years after bottling

Journalists in Switzerland. Structure and Attitudes

Results of a survey of Swiss Journalists