J. H. van der Merwe

Shell model calculations on natural parity states in 10≦ A≦14 nuclei

Shell model calculations of natural parity states in the 10≦A≦14 mass region have been performed by assuming an inert4He core with the residual interaction in the 1p shell only. The modified surface delta interaction (MSDI) has been used as an effective two-body interaction. The MSDI parameters as well as the single-particle binding energies have been deduced from a least-squares fit to experimentally known levels in, firstly, the seperate10B,11B-C,12C,13C-N and14N nuclei, and secondly, the whole mass region 10≦A≦14. Multipole moments for ground states and M1 and E2 radiative widths for excited states have been calculated with the resultant wave functions.

Resource-directed spatial planning of agritourism with GIS.

This article shows how modern spatial computing technology can be used for the development of spatial policy and planning of agritourism. An application is performed in the Western Cape province of South Africa. The article overviews provincial tourism development policy, the tourism marketing framework and the expressed tourist preferences that translate into spatial suitability indicators or attraction features captured in the agritourism resource base. Special attention is given to the conceptual foundations of what defines attraction and which can be captured in a spatial format as mapped variables. The methodological approach of spatial multiple criteria evaluation is applied through weighted linear combination of spatial factor layers as images in a geographical information system. The outcome in map format demonstrates the applicability of the technique to the Western Cape. The finely detailed spatial result is compared with coarser regional indicators from a spatial development framework proposed for guiding official tourism planning. The entrepreneurial implications of the analyses are indicated. The results are useful for entrepreneurial and regulatory planning that can be replicated in different spatial locations if the appropriate database can be constructed.

Environmental footprint of aircraft noise exposure at Cape Town International Airport

ABSTRACT Worldwide, aircraft noise is an environmental problem with social, technical and economic ramifications. The problem arises from increased air traffic, urban encroachment and uncoordinated planning near airports. In developing countries like South Africa this problem is often deemed to be of little importance. The paper provides a background sketch of the development of Cape Town International Airport and the noise control framework. It provides a brief overview of noise measurement and the way in which GIS is employed to determine the noise ‘footprint’ and manifestations of human exposure. The paper explores international findings about the effects of noise on incompatible land uses and vulnerable populations around major airports. GIS is employed to empirically establish the potential noise exposure of variously defined sensitive land use categories and vulnerable population groups in the noise-affected area at Cape Town International Airport.ABSTRACT Worldwide, aircraft noise is an environmental problem with social, technical and economic ramifications. The problem arises from increased air traffic, urban encroachment and uncoordinated planning near airports. In developing countries like South Africa this problem is often deemed to be of little importance. The paper provides a background sketch of the development of Cape Town International Airport and the noise control framework. It provides a brief overview of noise measurement and the way in which GIS is employed to determine the noise ‘footprint’ and manifestations of human exposure. The paper explores international findings about the effects of noise on incompatible land uses and vulnerable populations around major airports. GIS is employed to empirically establish the potential noise exposure of variously defined sensitive land use categories and vulnerable population groups in the noise-affected area at Cape Town International Airport.

COULOMB ENERGY DIFFERENCES OF MIRROR NUCLEI IN THE sd SHELL.

Abstract The Carlson-Talmi shell-model theory for Coulomb energies of mirror nuclei indicates an appreciable discontinuity of the harmonic oscillator parameter e 2 (v/π) 1 2 and the nuclear radius parameter r0 at A = 29. To be more realistic, configuration mixing within the sd shell at least should be taken into account. Considerations of a qualitative nature suffice to show that thereby the discontinuity loses its significance.

Shell-model relationships between negative-parity states of even-massA=30–40 nuclei

Simple relationships between the negative-parityenergy level structures of the even-mass nuclei pairsA=30 and 32, 34 and 40, 34 and 36, 34 and 38, 40 and 38 are established along lines similar to the well-known Pandya transformation between the particle-hole spectrum of40K and the particle-particle spectrum of38Cl. The relationships are generated within the framework of thejj-coupling shell model, using standard Racah algebra, and no assumption is made about the physical nature of the nuclear two-body interaction. Candidates for the 1f7/2 and 2p3/2 multiplets are selected on the basis of their measured spectroscopic strengths inl=3 or 1 single-particle transfer reactions with due allowance for member fragmentation and mixing between the two configurations in terms of the calculation of spectroscopic-strength weighted centroids. The calculated correlated energy spectra are discussed with reference to the results of previous interaction-dependent shell-model calculations, especially those employing the modified surface delta interaction. Consideration is also given to uncertain or ambiguous spin and parity assignments, deduced two-body interaction matrix elements, and the isospinT=0 and 1 and single-particle 1f7/2 and 2p3/2 splittings.