Test of shell-model interactions for nuclear structure calculations.
The binding energy and excitation spectra of 6Li are calculated in a no-core shell-model space giving encouraging results. The results of this calculation are then treated as a theoretical experiment, against which different effective-interaction approximations are compared. In this way insight into the perturbation expansion for the effective interaction is obtained.
Comparison of the effective interaction to various orders in different mass regions
The convergence of the perturbation expansion for the effective interaction to be used in shell-model calculations is investigated as a function of the mass number A, from A = 4 to A = 208. As the mass number increases, there are more intermediate states to sum over in each higher-order diagram which contributes to the effective interaction. Together with the fact that the energy denominators in each diagram are smaller for larger mass numbers, these two effects could largely enhance higher-order contributions to the effective interaction, thereby deteriorating the order-by-order convergence of the effective interaction. This effect is counterbalanced by the short range of the nucleon - nucleon interaction, which implies that its matrix elements are weaker for valence single-particle states in `large' nuclei with large mass number as compared to those in light nuclei. These effects are examined by comparing various mean values of the matrix elements. It turns out that the contributions from higher-order terms remain fairly stable as the mass number increases from A = 4 to A = 208. The implications for nuclear structure calculations are discussed.
The alcohol-aggression stereotype: a cross-cultural comparison of beliefs.
University students (N = 1,008) in eight countries participated in a survey aimed at mapping cross-cultural alcohol expectancies. Multisample structured means analysis was applied to compare changes in aggressive behaviors believed to occur in connection with drinking after "many" alcoholic drinks. Most subjects expressed the belief that intoxication was associated with greater aggressiveness, but there were significant national differences unrelated to self-reported alcoholic beverage preference, frequency of drinking to intoxication, or rates of personal involvement in episodes of alcohol-related aggression. Thus, the expectation that drinking leads to aggression may be determined to a significant extent by contextual factors and cultural traditions related to alcohol use.