Giant dipole resonance with exact treatment of thermal fluctuations

The shape fluctuations due to thermal effects in the giant dipole resonance (GDR) observables are calculated using the exact free energies evaluated at fixed spin and temperature. The results obtained are compared with Landau theory calculations done by parameterizing the free energy. The Landau theory is found to be insufficient when the shell effects are dominating.Comment: 5 pages, 2 figure

Applicability of shape parameterizations for giant dipole resonance in warm and rapidly rotating nuclei

We investigate how well the shape parameterizations are applicable for studying the giant dipole resonance (GDR) in nuclei, in the low temperature and/or high spin regime. The shape fluctuations due to thermal effects in the GDR observables are calculated using the actual free energies evaluated at fixed spin and temperature. The results obtained are compared with Landau theory calculations done by parameterizing the free energy. We exemplify that the Landau theory could be inadequate where shell effects are dominating. This discrepancy at low temperatures and high spins are well reflected in GDR observables and hence insists on exact calculations in such cases.Comment: 10 pages, 2 figure

A self-efficacy approach to holistic student development

Increasing numbers of students are arriving at tertiary institutions lacking in the skills needed to cope with the social and academic demands of higher education. Tertiary institutions are, therefore, faced with the task of equipping students with the skills needed to ensure that they can perform at an acceptable level. One such attempt to address this problem in a foundation course offered by the University of Port Elizabeth (UPE) is outlined. It is argued that student acquisition of the necessary social and academic skills will be more successful if they first believe they are capable of performing well and attaining the goals they set for themselves. The academic and life skills module (UPA111), offered in the foundation programme (UPE Advancement Programme), is designed to increase the self-efficacy of students so that they can approach their tasks with confidence, a positive attitude, and the belief that they can succeed. It is explained how self-efficacy is developed in students in the foundation programme in order to better prepare them for tertiary studies. Preliminary evaluation of the programme indicated that it does increase the self-efficacy of students. South African Journal of Education Vol.24(4) 2004: 289-29

On the origin of trisomy 21 Down syndrome

Background: Down syndrome, characterized by an extra chromosome 21 is the most common genetic cause for congenital malformations and learning disability. It is well known that the extra chromosome 21 most often originates from the mother, the incidence increases with maternal age, there may be aberrant maternal chromosome 21 recombination and there is a higher recurrence in young women. In spite of intensive efforts to understand the underlying reason(s) for these characteristics, the origin still remains unknown. We hypothesize that maternal trisomy 21 ovarian mosaicism might provide the major causative factor. Results: We used fluorescence in situ hybridization (FISH) with two chromosome 21-specific probes to determine the copy number of chromosome 21 in ovarian cells from eight female foetuses at gestational age 14–22 weeks. All eight phenotypically normal female foetuses were found to be mosaics, containing ovarian cells with an extra chromosome 21. Trisomy 21 occurred with about the same frequency in cells that had entered meiosis as in pre-meiotic and ovarian mesenchymal stroma cells. Conclusion: We suggest that most normal female foetuses are trisomy 21 ovarian mosaics and the maternal age effect is caused by differential selection of these cells during foetal and postnatal development until ovulation. The exceptional occurrence of high-grade ovarian mosaicism may explain why some women have a child with Down syndrome already at young age as well as the associated increased incidence at subsequent conceptions. We also propose that our findings may explain the aberrant maternal recombination patterns previously found by family linkage analysis

On the structure of subsets of an orderable group with some small doubling properties

The aim of this paper is to present a complete description of the structure of subsets S of an orderable group G satisfying |S^2| = 3|S|-2 and is non-abelian