https://hdl.handle.net/13049/9 Wed, 04 Nov 2026 07:44:35 GMT 2026-11-04T07:44:35Z https://hdl.handle.net/13049/851 Nutritional content, phytochemicals, and biological activity in leafy vegetables Olekile, Tibe; Baghali, Guys Mathapa Indigenous leafy vegetables play a significant role in the provision of nutrients, vitamins, minerals, and phytochemicals required for growth, maintenance, and protection from chronic diseases. These leafy vegetables are usually collected in the veld during the rainy season and consumed as food and/or medicine. Due to urbanization and westernization, the consumption of these leafy vegetables is decreasing. The phytochemicals play an important role as antioxidants in suppressing free radicals that can damage important cellular components, resulting in lifestyle diseases such as hypertension, diabetes, atherosclerosis, cancer, and stroke. Eating these indigenous vegetables is advantageous in many fronts. Firstly, the majority of them are wild and therefore freely available and accessible to everyone willing and interested in harvesting. Secondly, they are not contaminated with toxic modern pesticides and fertilizers compared to commercial vegetables. In addition to nutritional value, these leafy vegetables have financial and economic value to local rural communities who trade in indigenous food products. The African indigenous leafy vegetables contain valuable nutrients, minerals, and vitamins needed to promote good health. These leafy vegetables have potential for cultivation, and their consumption should be promoted. In this chapter, the nutritional, phytochemicals, health value, and properties of the indigenous leafy vegetables are described. Book Chapter Thu, 01 Jan 2026 00:00:00 GMT https://hdl.handle.net/13049/851 2026-01-01T00:00:00Z https://hdl.handle.net/13049/834 The variability and predictability of the IRI B 0 , B 1 parameters over Grahamstown, South Africa McKinnell, Lee-Anne; Chimidza, Oyapo; Cilliers, Pierre The International Reference Ionosphere (IRI) parameters B0 and B1 provide a representation of the thickness and shape, respectively, of the F2 layer of the bottomside ionosphere. These parameters can be derived from electron density profiles that are determined from vertical incidence ionograms. This paper aims to illustrate the variability of these parameters for a single mid latitude station and demonstrate the ability of the Neural Network (NN) modeling technique for developing a predictive model for these parameters. Grahamstown, South Africa (33.3°S, 26.5°E) was chosen as the mid latitude station used in this study and the B0 and B1 parameters for an 11 year period were determined from electron density profiles recorded at that station with a University of Massachusetts Lowell Center for Atmospheric Research (UMLCAR) Digisonde. A preliminary single station NN model was then developed using the Grahamstown data from 1996 to 2005 as a training database, and input parameters known to affect the behaviour of the F2 layer, such as day number, hour, solar and magnetic indices. An analysis of the diurnal, seasonal and solar variations of these parameters was undertaken for the years 2000, 2005 and 2006 using hourly monthly median values. Comparisons between the values derived from measured data and those predicted using the two available IRI-2001 methods (IRI tables and Gulyaeva, T. Progress in ionospheric informatics based on electron density profile analysis of ionograms. Adv. Space Res. 7(6), 39–48, 1987.) and the newly developed NN model are also shown in this paper. The preliminary NN model showed that it is feasible to use the NN technique to develop a prediction tool for the IRI thickness and shape parameters and first results from this model reveal that for the mid latitude location used in this study the NN model provides a more accurate prediction than the current IRI model options. Journal article Tue, 15 Sep 2009 00:00:00 GMT https://hdl.handle.net/13049/834 2009-09-15T00:00:00Z https://hdl.handle.net/13049/833 Implementation of a boundary element method for high frequency scattering by convex polygons with impedance boundary conditions Mokgolele, Mosiamisi Many acoustic and electromagnetic wave scattering problems can be formulated as the Helmholtz equation. Standard finite and boundary element method solution of these problems becomes expensive, as the frequency of incident wave increases. On going research has been devoted to finding methods that do not loose robustness when the wave number increases. Recently, Chandler-Wilde et al. have proposed a novel Galerkin boundary element method to solve the problem of acoustic scattering by a convex polygon with impedance boundary conditions. They applied approximation spaces consisting of piecewise polynomials supported on a graded mesh with smaller elements adjacent to the corners of the polygon and multiplied by plane wave basis functions. They demonstrated via rigorous error analysis that was supported by numerical experiments that the number of degrees of freedom required to achieve a prescribed level of accuracy need only grow logarithmically as frequency increases. In this paper, we discuss issues related to detail implementation of their numerical method. Journal article Fri, 01 Jan 2016 00:00:00 GMT https://hdl.handle.net/13049/833 2016-01-01T00:00:00Z https://hdl.handle.net/13049/832 Effect of hollow centre post in coupled combline resonators Pholele, Thato M.; Chuma, Joseph M.; Ngebani, Ibo The effect of thickness of a hollow post in a combline resonator on the resonant frequency, coupling coefficients and spurious performance are analysed. It is shown that both the electric and magnetic couplings are not significantly affected by the size of the thickness of the hollow post, whereas the resonant frequency and spurious free band both change. When the thickness of the hollow post reduces the spurious free band deteriorates while the resonant frequency increases. Working paper Sun, 01 Jan 2017 00:00:00 GMT https://hdl.handle.net/13049/832 2017-01-01T00:00:00Z