Showing papers by "University of South Africa published in 1972"
TL;DR: In this article, the structural influences of misfit, bonding and crystal dimension in epitaxial bicrystals are reviewed and a model in which the inter-action between the crystal halves is represented by a periodic force acting at the interface, the crystals are approximated by elastic continua and the structure is assumed to be governed by lowest energy principles.
128 citations
TL;DR: The infrared spectra of copper(II) acetate monohydrate (I), copper (II) monodeuterium oxide ( II ), and anhydrous copper( II) acetates ( III ) have been studied between 350 °K and 77 °K in the range of 4000-300 cm −1, and the splitting obtained for nearly all of the fundamental modes of the acetate groups is interpreted in terms of the opposite bidentate, bridging acetates groups in the formula unit, and corresponds to the g- and u-splitting of vibrations observed in
37 citations
Journal Article•
TL;DR: The non-central Wishart distribution was first derived by Anderson and Girshick (1944) and Anderson (1946) for the linear and planer cases as discussed by the authors.
Abstract: The non-central Wishart distribution was first derived by Anderson and Girshick (1944) and Anderson (1946) for the linear and planer cases. Herz (1955) expressed the distribution as a Bessel function and James (1961) as a series of zonal polynomials. This non-central distribution plays an important part in deriving a number of test-statistics in multivariate analysis. The distribution as well as the distributions derived from it, are difficult to handle. In this paper it is shown how the non-central distribution can be approximated by a central distribution or by a central distribution together with the generalised Laguerre polynomials.
35 citations
TL;DR: In this article, two new approaches are presented, one introduces a refinement of the well-known concept of the shielding of the field of a dislocation by others and by free surfaces, and the other one uses the exact solution of the governing equation of a simple case as a first approximation for the more complicated governing equation.
34 citations
TL;DR: In this paper, the authors investigated the off-shell variation of the binding energy of the triton E T for exactly phase-equivalent separable potentials of rank two, and showed that E T ( γ, β ) reaches a lower limit of about 8.2 MeV if γ β 2 ⪢ 1 or E B ⫢ E D, the deuteron binding energy.
16 citations
TL;DR: In this paper, the crystal structure of NH 4 BF 4 (IV) has been determined at 140°K by standard Weissenberg techniques using visual estimation of intensities and has been refined by full-matrix least-squares methods to a conventional R = 0.10.
13 citations
TL;DR: In this paper, the second moment of a central component of the 59Co NMR line in a single, four-layer orthorhombic crystal of K3Co(CN)6 was measured.
Abstract: From measurements of the second moment of a central component of the 59Co NMR line in a single, four-layer orthorhombic crystal of K3Co(CN)6, the chemical shifts (σzz — σxx) and (σxx — σyy) have been found to be (±15.5 ± 1.0) × 10−5 and (±17.8 ± 1.0) × 10−5, respectively. The principal axes of the σ's nearly coincide with the crystallographic a, b, and c axes. The room temperature values of the quadrupole coupling constant and asymmetry parameter are (5.88 ± 0.01) MHz and 0.9 ± 0.004 respectively. The quadrupole coupling constant increases linearly with decreasing temperature in the range 100 K < T < 500 K, the temperature coefficient being −1.58 × 10−4 K−1.
Aus Messungen des zweiten Moments einer Zentralkomponente der 59Co NMR-Linie in einem vier-schichtigen orthorombischen Einkristall von K3Co(CN)6 wurden die chemischen Verschiebungen (σzz — σxx) und (σxx — σyy) zu (±15,5 ± 1,0) × 10−5 und (±17,8 ± 1,0) × 10−5 bestimmt. Die Hauptachsen der σ's stimmen fast mit den kristallographischen a, b und c-Achsen uberein. Bei Zimmertemperatur ist der Wert der Quadrupolkopplungskonstante (5,88 ± 0,01) MHz und der des Asymmetrieparameters 0,9 ± 0,004. Im Bereich 100 K < T < 500 K steigt die Quadrupolkopplungskonstante linear mit abnehmender Temperatur an. Der Temperaturkoeffizient hierfur betragt −1,58 × 10−4 K−1.
12 citations
TL;DR: In this paper, it is shown that an investigation of the on-shell T -matrix as a function of the strength of the interaction can provide much information on the off-shell behaviour of its T-matrix.
9 citations
Journal Article•
TL;DR: In this article, the author comments upon some aspects of environmental law, particularly in context with potential remedies which the law affords to the environmentalist, and special attention will be paid to the role of criminal law, which in our time and society is still a major instrument in curbing reprehensible activities.
Abstract: In this paper the author comments upon some aspects of environmental law, particularly in context with potential remedies which the law affords to the environmentalist. Amongst other things special attention will be paid to the role of criminal law, which in our time and society is still a major instrument in curbing reprehensible activities.
6 citations
TL;DR: A strategy for assessing change in the effective ability of a person, from the pre-traumatic to the post-traumatic state, is given, and the importance of work performance criteria in this regard, is stressed.
5 citations
Journal Article•
TL;DR: As long as the Security Council has no means of enforcing its South West Africa resolutions by some chapters 5 or 6 peace force, and as long as enforcement measures under chapter 7 remain improbable, it is ultimately for South Africa to decide whether it will be prepared to render these resolutions effective as discussed by the authors.
Abstract: As long as the Security Council has no means of enforcing its South West Africa resolutions by some chapters 5 or 6 peace force, and as long as enforcement measures under chapter 7 remain improbable, it is ultimately for South Africa to decide whether it will be prepared to render these resolutions effective. In this respect, it will be incumbent on South Africa to define its position not only as regards South West Africa, but also vis-a-vis the United Nations, and to indicate on what basis it is prepared to resume a debate on South West Africa.
TL;DR: Psychiatric aspects which are juridically relevant in the assessment of the quantum of damages in delictual (tort) actions involving head injuries are discussed and some discussion is devoted to the practical approach in the presentation of expert evidence in court.
TL;DR: In this paper, the delta-shell potential is used to calculate three-nucleon bound-state properties with respect to the 1S0 and 3S1 phase shifts.
Abstract: Publisher Summary This chapter reviews three-nucleon bound-state properties using delta-shell nucleon–nucleon interactions. Two reasons for the use of delta-shell potential are (1) with an appropriate choice of the potential parameters, an amazingly good fit to the 1S0 and 3S1 phase shifts is obtained and (2) as the potential is local, several three-nucleon properties can be calculated easily using the hyperspherical harmonics formalism. The bound-state properties are much more sensitive with respect to variations in the effective ranges than to variations in the scattering lengths. There is almost no dependency on the singlet scattering length. The large sensitivity for the singlet effective range is interesting as its experimental error is considerable and a change of the parameter within its error could give a variation in binding energy of about 500keV. Until the value of that parameter is better known, not much can be done with the dependency on the other parameters.
01 Dec 1972
TL;DR: In this paper, a modified random walk method based on the Aris integrals has been formulated for the evaluation of plate height contributions, which yields values in exact correspondence with that obtained from Giddings nonequilibium theory.
Abstract: A modified random walk method, based on the Aris integrals, has been formulated for the evaluation of plate height contributions. The method is simple to apply, yet yields values in exact correspondence with that obtained from Giddings nonequilibium theory.
TL;DR: This chapter focuses on the bound state properties of the triton for such nearly separable potentials, and an investigation of the behavior of δ(k,s) as a function of s for a given potential reveals much about theNearly separable character of its associated T-matrix.
Abstract: Publisher Summary Many realistic potentials are, in a sense, nearly separable. This chapter focuses on the bound state properties of the triton for such nearly separable potentials. An investigation of the behavior of δ(k,s) as a function of s for a given potential reveals much about the nearly separable character of its associated T-matrix. The chapter describes that several different local and nonlocal potentials are all nearly separable in the sense. As they are also fitted to roughly the same on-shell T-matrix up to reasonably high energies, one expects that their off-shell T-matrices should also be rather similar. The off-shell behavior of the nearly separable potentials must be very similar if they are all fitted to the same phase shift up to sufficiently high energies. The MIRT potential departs somewhat from the others for the low values of s. Local potentials with realistic phase shifts have much more in common with certain classes of non-local potentials then is commonly accepted. Such potentials must have repulsive phase shifts at high energies and also must be mainly determined by the on-shell behavior of the T-matrix.