Isospin singlet (pn) pairing and quartetting contribution to the binding energy of nuclei

Isospin singlet (pn) pairing as well as quartetting in nuclei is expected to arise near the symmetry line $N=Z$. Empirical values can be deduced from the nuclear binding energies applying special filters. Within the local density approximation, theoretical estimates for finite nuclei are obtained from results for the condensation energy of asymmetric nuclear matter. It is shown that the isospin singlet condensation energy drops down abruptly for |N-Z|~4 for medium nuclei in the region A=40. Furthermore, alpha-like quartetting and the influence of excitations are discussed.Comment: 19 pages, 19 figures, submitted to PR

Endogenous factors that relate to the eating habits of adolescents

The aim in this research was to determine how endogenous factors such as gender, intelligence, self-concept, and personality relate to the eating habits of adolescents. An empirical investigation was conducted using 340 secondary school learners, 162 boys and 178 girls. From the results it appeared that girls tend to have more unhealthy eating habits than boys and adolescents with high intelligence are at risk of developing unhealthy eating behaviour. A strong relationship existed between the physical self and eating habits. The most important personality factors associated with eating habits were social boldness and individualism. South African Journal of Education Vol.24(3) 2004: 189-19

Mechanistic analysis of ammonium inhibition of atmospheric methane consumption in forest soils

Methane consumption by forest soil was studied in situ and in vitro with respect to responses to nitrogen additions at atmospheric and elevated methane concentrations. Methane concentrations in intact soil decreased continuously from atmospheric levels at the surface to 0.5 ppm at a depth of 14 cm. The consumption rate of atmospheric methane in soils, however, was highest in the 4- to 8-cm depth interval (2.9 nmol per g of dry soil per day), with much lower activities below and above this zone. In contrast, extractable ammonium and nitrate concentrations were highest in the surface layer (0 to 2 cm; 22 and 1.6 μmol per g of dry soil, respectively), as was potential ammonium-oxidizing activity (19 nmol per g of dry soil per day). The difference in zonation between ammonium oxidation and methane consumption suggested that ammonia-oxidizing bacteria did not contribute significantly to atmospheric methane consumption. Exogenous ammonium inhibited methane consumption in situ and in vitro, but the pattern of inhibition did not conform to expectations based on simple competition between ammonia and methane for methane monooxygenase. The extent of ammonium inhibition increased with increasing methane concentration. Inhibition by a single ammonium addition remained constant over a period of 39 days. In addition, nitrite, the end product of methanotrophic ammonia oxidation, was a more effective inhibitor of methane consumption than ammonium. Factors that stimulated ammonium oxidation in soil, e.g., elevated methane concentrations and the availability of cosubstrates such as formate, methanol, or β- hydroxybutyrate, enhanced ammonium inhibition of methane oxidation, probably as a result of enhanced nitrite production

Ammonium and nitrite inhibition of methane oxidation by Methylobacter albus BG8 and Methylosinus trichosporium OB3b at low methane concentrations

Methane oxidation by pure cultures of the methanotrophs Methylobacter albus BG8 and Methylosinus trichosporium OB3b was inhibited by ammonium choride and sodium nitrite relative to that in cultures assayed in either nitrate-containing or nitrate-free medium. M. albus was generally more sensitive to ammonium and nitrite than M. trichosporium. Both species produced nitrite from ammonium; the concentrations of nitrite produced increased with increasing methane concentrations in the culture headspaces. Inhibition of methane oxidation by nitrite was inversely proportional to headspace methane concentrations, with only minimal effects observed at concentrations of \u3e500 ppm in the presence of 250 μM nitrite. Inhibition increased with increasing ammonium at methane concentrations of 100 ppm. In the presence of 500 μM ammonium, inhibition increased initially with increasing methane concentrations from 1.7 to 100 ppm; the extent of inhibition decreased with methane concentrations of \u3e100 ppm. The results of this study provide new insights that explain some of the previously observed interactions among ammonium, nitrite, methane, and methane oxidation in soils and aquatic systems

Suppression of combustion oscillations with mechanical devices Interim report

Static rocket thrust chamber simulator for cylindrical cold flow-type apparatus desig

Precritical pair fluctuations and formation of a pseudogap in low-density nuclear matter

Low-density nuclear matter at finite temperature is considered representing the strong coupling situation of a highly correlated fermion system. One-particle se lf-energies and the density of states in the vicinity of the pairing transition point are presented. Within the Green function approach model calculations are p erformed using the thermodynamic $T$ matrix in ladder approximation. As a main r esult the formation of a pseudogap in the level density near the critical temper ature of the pairing phase transition has been found. It is shown that compared to mean field, the picture of the onset of the pairing transition is essentially changed if correlations are taken into account