Les statues comptent parmi les plus remarquables témoignages matériels de l’Antiquité qu’il nous est donné de contempler. Si chacun d’entre nous voit ce qu’elles sont, leur réelle signification nous échappe cependant dans l’ensemble. Délaissant la démarche du catalogage et de la classification typologique, ce travail se propose de les replonger dans une atmosphère sociale parfaitement révisée, reconstituée et interrogée. À quoi cela servait-il d’ériger une statue dans la Rome antique ? À quoi cela sert-il de les étudier présentement ? À cela nous répondons que derrière ces vestiges, c’est la motivation de retrouver une conception du monde différente de la nôtre, mais capable de l’éclairer sous un jour nouveau qui fut pour nous déterminante. Derrière les statues, c’est retrouver l’Homme qu’il soit d’hier ou d’aujourd’hui. C’est surtout dépasser l’inertie apparente pour repenser une vie communautaire dans laquelle l’honneur prévalait et dont la réception s’avère encore à notre temps des plus vivaces. / Statues are the most noticeable tangible testimonies from Antiquity that we are given to contemplate. If each of us can see what they are, yet we can not get their true meaning in their whole. Abandoning the approach of cataloguing and typological classification, this work intends to throw us back to the statues’ social atmosphere that is perfectly revised, reconstituted and questioned. What is the use of erecting a statue in Ancient Rome? What is the use of studying them so far? To answer this question, we can say that beyond these ruins, it is the drive to find again a conception of a world that is different from ours, but a world that is capable of shedding a new light into the meaning of the Statues, which is essential for us. Behind the statues, it is to find again the Man, either the old type or the new type. It is above all to transcend the seeming inertia to think again a community life, in which the honour prevailed and whom reception turns out to be the most vivid in our modern world.

The potential of Indigofera species as forage and/or cover crops for semi-arid and arid environments was investigated in several experiments conducted on the Hatfield Experimental Farm in Pretoria, South Africa. Dormancy associated with hard seededness is the main constraint for uniform germination and large-scale propagation of these species. In this study, pretreatment increased germination in most accessions with scarification being more effective than boiling water treatment in six accessions, but not in the case of I. vohemarensis 8730. In five accessions (I. cryptantha 7067, I. brevicalyx 7517, I. arrecta 7524, I. spicata 8254 and I. vohemarensis 8730), scarification improved the total germination percentage, though it simultaneously resulted in higher seed mortality of I. brevicalyx 7517, I. arrecta 7524 and I. vohemarensis 8730 than in the control. In four accessions (I. brevicalyx 7517, I. arrecta 7524, I. vohemarensis 8730 and I. trita 10297), boiling water treatment improved germination percentage without causing any significant risk of seed mortality in the latter three species. In a field study, 41 Indigofera accessions were characterized in terms of morphological and agronomic parameters, using multivariate techniques to describe their phenotypic variability. Eight morpho-agronomic groups with various potentials were identified along with eight determinant characteristics that can be regarded as the core attributes for future Indigofera germplasm characterisation. Further evaluation of promising accessions revealed remarkable differences, both between and within species, in terms of plant height, canopy spread diameter, forage biomass, crude protein content, in vitro organic matter digestibility and indospicine level of the forage. These suggest the possibility of directly selecting accessions with forage potential for subsequent evaluation with target animals. The response of four selected Indigofera accessions under simulated moisture deficit stress and non-stress conditions exhibited significant variation. I. amorphoides was relatively sensitive while I. vicioides was able to maintain growth under water stress conditions, while the response of the two I. arrecta accessions were intermediate. The influence of season and species on forage quality was also studied. Spring growth had a significantly higher (P< 0.05) CP content than autumn growth in all species. In vitro digestibility of dry material also tended to decrease from the spring of 2004 to the autumn of 2004. Higher levels of Ca, P, Mg, Zn and Cu concentration were revealed in the leaf meal of the first harvest than in the re-growth harvest. All of the species had Ca, Mg, Zn and Mn concentration levels that could support the requirements of ruminants. P and Cu were slightly deficient for some of the species in the autumn suggesting the need to supplement P and Cu from other sources. Compared to Leucaena forage, Indigofera forage had higher apparent organic matter and dry matter digestibility coefficients and higher crude protein and neutral detergent fibre digestibility coefficients. The difference between Indigofera and Leucaena forage in terms of DM intake per unit of metabolic body weight (DMI g BW-0.75 day-1) was not significant (P> 0.05). The digestible organic matter intake (DOMI) and digestible crude protein intake (DCPI) of the sheep on Indigofera forage was similar to that of sheep fed Leucaena. In this study, lack of differences between Indigofera and Leucaena forage in terms of DOMI, DCPI and DNDFI means that Indigofera forage would likely support similar weight gains as that of Leucaena, but lower than that of M. sativa forage. / Thesis (PhD (Plant Production: Pasture Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Fossil fuels are currently the primary industrial energy source on Earth. They are principally composed of complex hydrocarbons in either long-chain or cyclic conformation. Industrial use of petroleum, diesel, oil, tar and other coal-derived products inevitably leads to pollution of the environment. The most serious pollution is caused by polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) that are not easily removed from soil after a spill. Long-chain and cyclic conformation makes fossil fuel hydrocarbons difficult to break down. However, certain free-living soil microorganisms have adapted to utilising these PAHs/PCBs as a source of energy. In many cases, their efficacy is greatly enhanced by the presence of plants. By inhabiting the rhizosphere, microbes form a mutualistic relationship with the plant, receiving nutrients from it and in return providing a less polluted environment in which the plant can grow. The purpose of this study was to elucidate some of the microbial population diversity in PAH/PCB-polluted soils in South Africa through the use of denaturing gradient gel electrophoresis (DGGE). In an initial study, DGGE was employed to separate soil communities in polluted and unpolluted soils into a genetic fingerprint, the main bands of which were sequenced and subjected to a BLAST analysis through a database for possible identification of species present. Phylogenetic and distance studies indicated that unpolluted soils have a far greater species diversity. It thus was evident that PAH/PCB pollution of soil leads to a decrease in microbial diversity by selecting for microorganisms with the ability to activate metabolic pathways allowing them to utilise the pollutants as an alternative source of carbon. Population diversity of pro- and eukaryotes found within polluted and non-polluted soils was compared. DGGE was employed to determine the genetic fingerprint of each population. Following this, dendogram analyses based on Shannon indices were done to determine PAH breakdown potential of prokaryotic vs. eukaryotic communities. A higher diversity and better adaptation potential were evident within prokaryotic than eukaryotic communities in pollution-stressed environments, indicating that the prokaryotic component of these samples had the greatest PAH-metabolism potential. To determine the capacity for PAH/PCB metabolism by the organisms within the soil samples being studied, the presence of xylE and ndoB genes, responsible for toluene/xylene and naphthalene biodegradation, respectively, was determined. DGGE was performed to analyse genetic diversity between these two genes, based on community fingerprints. Polluted soil communities tended to have comparable community diversity within their functional genes, depending on their physical situation, plant species proximity and soil conditions. In general, soil contained indigenous microbes with a high natural potential for biodegradation of PAHs/PCBs. A portion of the 16S gene of eight bacterial isolates representing the most dominant culturable taxa in the polluted soils was sequenced and analysed for identification purposes. These identifications were conducted in conjunction with the use of the catabolic gene probes xylE and ndoB to establish the hydrocarbon degrading capacity of the isolates. Pseudomonas, from the rhizosphere of Cyperus esculentus, was the most common PAH-degrading genus found in this study. Considering the well-established rhizosphere competence and PAH-degrading capacity of Pseudomonas, this genus seems to be the best suited for bioaugmentation purposes in South Africa. The presence of the nifH gene, the general marker gene of nitrogen-fixing bacteria in communities from unpolluted and polluted soils, was determined. It was hypothesised that bioremediation could be enhanced by nitrogen addition to polluted environments. Nested-PCR of the nifH gene was conducted on a diagnostic basis and was followed by DGGE of the product to determine the functional gene diversity within pollution-dwelling, nitrogen-fixing bacterial communities. Nitrogen-fixing microorganisms were present in all the soils sampled but, in only 80% of the pure cultures isolated from polluted and unpolluted soils and rhizospheres. Although different rhizospheres and pollutants were examined, it was found that of the polluted soils studied, most nifH gene diversity of polluted soils existed within machinery oil polluted, wood chip mulched, non-rhizosphere soil. Thus, it would appear that the more polluted the soil the higher the free microbe nitrogen fixation diversity possibly due to environmental stress. / Thesis (PhD (Microbiology))--University of Pretoria, 2007. / Microbiology and Plant Pathology / unrestricted

In the TRISO (tristructural isotropic) coated fuel particle used in the High Temperature Reactor, the most important layer is a silicon carbide layer which acts as a pressure vessel. In this study, we have focused our study on the investigation of the Young’s modulus, hardness, residual stress, and fracture toughness of the SiC layer. Moreover, microstructures and impurities in silicon carbide were characterised and then related to both Young’s modulus and hardness of the SiC layer. Both nanoindentation and micro-indentation were used to determine Young’s modulus and hardness of the SiC. Raman spectroscopy, X-ray diffraction, and scanning electron microscopy techniques were used to examine impurities, phases and microstructure of silicon carbide layers, respectively. Young’s modulus was measured at different positions of a polished surface of the SiC with different CVD growth and crystal orientations. With help from the finite element modelling, it has been found that Young’s modulus of the SiC is dependent on the grain orientation of the SiC. Mechanical properties of silicon carbide are affected by the presence of excess silicon, excess carbon, stacking faults, texture, grain size, property of grain boundary. The effect of these factors on Young’s modulus and hardness, are investigated with the orthogonal analysis. The analysis concludes that the most important factor on Young’s modulus is texture while the most significant factor on hardness is grain boundary. Grain size is secondarily important factor to affect hardness. Stacking faults and impurities almost have no influence on Young’s modulus and hardness. The residual stress in the silicon carbide layer was measured based on the peak shift in Raman spectra of the SiC and is in a range of 150-300 MPa. Fracture resistance in the radial direction of the SiC layer is larger than those in the circumferential direction. The difference is controlled by the layer-like structure of the SiC coating.

Rapid advancement in wireless communications over the years has been the driving force for many novel technologies providing compact and low cost solutions. Recent development of multilayer coplanar waveguide (CPW) MMIC technology promises realization of 3D MMIC in which large area-occupying passive components are translated from horizontal into vertical configuration resulting compact structure. The other main advantages of this technology are elimination of via-holes and wafer-thinning giving alternative performance solution, if not better, from the traditional MMIC. In this thesis, thermal and small-signal characteristics of prefabricated AlGaAs/InGaAs pseudomorphic high electron mobility transistors (pHEMTs) on semi-insulating (S.I.) GaAs substrate incorporated in the 3D MMIC technology have been analysed and modelled for the first time. A comprehensive small-signal parameter extraction procedure has been successfully developed which automatically determines the device small-signal parameters directly from the measured S-parameters. The developed procedure is unique since it provides a great deal of data on measured devices over a wide bias, temperature and frequency range for future incorporation of different active devices for the 3D MMIC technology and provides a first hand knowledge of how the multilayer structure will affect the performance of pre-fabricated pHEMTs. The extracted small-signal models of both pre- and post- multilayer processed pHEMTs have been compared and validated to the RF S-parameters measurements. The main focus was drawn upon the temperature dependent model parameters and how the underlying physics of the transistors behave in response to the change of temperature. These novel insights are especially valuable for devices designed specifically for high power applications like power amplifiers where tremendous heat could be generated. The data can also be interpreted as a way to optimise the multilayer structure, for example, alternative material with different properties can be implemented. The governing physics affecting device performance are also modelled and discussed empirically in details through extracted device parameters. These investigations would assist in the development of reliable, efficient and low cost production of future compact 3D multilayer CPW MMICs.

Radionuclides from natural U-series in sediments from two river catchments in the UK have been studied. The aim was to gain insight into the behaviour of 238U, 234U, 230Th and 226Ra in real natural systems enriched in uranium. A radiochemical method for radium separation followed by alpha spectrometric measurement has been developed. The method allowed use of 225Ra, in equilibrium with the parent 229Th, as a yield determinant, and has been applied in 226Ra concentrations measurements in the selected areas of study.U-series progeny, 238U, 234U, 230Th and 226Ra, in totally dissolved sediments from the valley of the River Noe and the fraction leached by aqua regia, have been measured. Total sediment contents ranged from 9 ± 2 to 184 ± 8 Bq.kg-1 for uranium, 9 ± 3 to 200 ± 13 Bq.kg-1 for thorium and 18 ± 1 to 179 ± 8 Bq.kg-1 for radium. The activity concentrations in the leached fractions, compared with the total, were 46% for uranium, 54% for thorium and 56% for radium, on average. The radionuclides showed extensive disequilibrium and this suggested a complex leaching/accumulation of uranium as well as an impact of organic matter and secondary minerals.Uranium and radium have been geochemically characterised in sediments from near the South Terras abandoned uranium mine, Cornwall. Background activity concentration levels of uranium in sediments ranged from 13 ± 3 to 290 ± 14 Bq.kg-1, with radium from 42 ± 4 to 424 ± 23 Bq.kg-1. Elevated concentrations of uranium and radium were measured in two samples, S3 with 1820 ± 36 Bq.kg-1 for uranium and 940 ± 53 Bq.kg-1 for radium; and S7 with 4350 ± 53 Bq.kg-1 for uranium and 1765 ± 48 Bq.kg-1 for radium. Sequential chemical extraction for the two samples revealed that both uranium and radium were associated with organic and carbonate fractions, with 25 % of the uranium in the resistant phase of S7. 234U/238U activity ratios of the sequential extraction fractions showed different trends in the sediments, and this was linked to the impact of organic matter and/or exchange between water and sediment. Uranium-bearing minerals in association with potassium, calcium, iron, manganese and arsenic have been identified in these sediments.

Bilateral breast augmentation is one of the most common cosmetic surgical procedures carried out on women in the western world. Breast augmentation involves increasing the volume of a woman‘s breasts through surgery by placing a silicone implant in the subglandular or subpectoral cavity. Although a capsule forms inevitably around breast implants as a natural part of healing, it can cause significant morbidity if the capsule becomes firm and contracted, a condition known as breast capsular contracture (BCC). The aetiology of BCC remains unknown however it is characterised by dense fibrocollagenous connective tissue with a local inflammatory response. Host response is influenced by several factors including implant surface texture, chemistry and interactions between cells and the extracellular matrix. Texturing holds the implant in place, thus preventing micromotion at the host prosthesis interface. While in smooth surfaces, the implant moves inside the breast, making the fibroblasts repeatedly produce collagen in response to this host-prosthesis shearing motion. In this thesis, the effect of surface characteristics and specific coatings on the cell-surface interaction has been examined on smooth compared to textured surfaces using commercially available breast implants. The properties of breast implants shells have been characterised using confocal laser microscopy, contact angle measurements, confocal Raman spectroscopy and tensile testing. Confocal laser microscopy was used to evaluate the topographical features and surface roughness of the implant surfaces. Contact angle measurements were carried out to determine the hydrophobicity of the implant surfaces. Chemical characterisation was carried out recording Raman images and spectra of the implants using confocal Raman spectrometer. The mechanical properties of the breast implant shells were measured via tensile testing. Adhesive interactions of breast-derived fibroblasts with breast implant surfaces were examined in-vitro. For this purpose, the effect of four molecule coatings (aggrecan, collagen I, fibronectin, and hyaluronic acid) was evaluated on fibroblast attachment, proliferation, fibroblast morphology, spreading, cytotoxicity and gene expression. Results from in-vitro assays demonstrated cell susceptibility to topography and protein coatings and further showed cytoskeletal re-organisation and modification with specific cell adhesion patterns. Combination of diverse topographies and specific coatings induced differential regulation of the expression of adhesion related genes, such as focal adhesion kinase, paxillin, vinculin, and α-actinin on breast fibroblasts. In conclusion, this thesis has demonstrated the extent and strength of cell adhesion and subsequent cell proliferation and differentiation. This is based on the physical interactions between cells and the extracellular environment in the form of topography and on the chemical interactions mediated by specific coatings. Precise characterisation of the silicone breast implant surfaces was achieved. This may play an important role in the development of improved breast implant surfaces with improved qualities leading the development of surfaces that may be less prone to capsular contracture.

The rapid growth in wireless data traffic in recent years has placed a great strain on the wireless spectrum and the capacity of current wireless networks. In addition, the makeup of the typical wireless propagation environment is rapidly changing as a greater percentage of data traffic moves indoors, where the coverage of radio signals is poor. This dual fronted assault on coverage and capacity has meant that the tradition cellular model is no longer sustainable, as the gains from constructing new macrocells falls short of the increasing cost. The key emerging concept that can solve the aforementioned challenges is smaller base stations such as micro-, pico- and femto-cells collectively known as small cells. However with this solution come new challenges: while small cells are efficient at improving the indoor coverage and capacity; they compound the lack of spectrum even more and cause high levels of interference. Current channel models are not suited to characterise this interference as the small cells propagation environment is vast different. The result is that overall efficiency of the networks suffers. This thesis presents an investigation into the characteristics of the wireless propagation channel in small cell environments, including measurement, analysis, modelling, validation and extraction of channel data. Two comprehensive data collection campaigns were carried out, one of them employed a RUSK channel sounder and featured dual-polarised MIMO antennas. From the first dataset an empirical path loss model, adapted to typical indoor and outdoor scenarios found in small cell environments, was constructed using regression analysis and was validated using the second dataset. The model shows good accuracy for small cell environments and can be implemented in system level simulations quickly without much requirements.

The highly competitive market in the oil refining industry forces refiners look for more detailed information of both feedstocks and products to achieve the optimal economic performance. Due to stricter environmental legislations, the molecular level characterisation has been investigated by various researchers and shows promising advantages in modern refinery design and operation. Although various molecular characterisation methods have been developed, there is an unavoidable trade-off between keeping astronomical molecule details and practicality in industrial applications. In the meantime, many of these methodologies have different characteristics and different focuses according to a particular application purpose. Our aim is hence to tackle the problems of developing manageable and practical technical solutions for molecular characterisation of petroleum fractions for vary refinery processes. A pseudo-component based approach is developed within a modified MTHS (Molecular Type Homologous Series) matrix framework (Peng, 1999) to represent the molecular information of a particular refining stream. This proposed methodology incorporates both molecular type and pseudo-component information by the conjunction of homologous series and boiling points in the matrix framework. To increase the usability of this method, a 3-parameter gamma distribution function is introduced to describe the composition of each structural molecular type. Typical PIONA (paraffin, iso-paraffin, olefin, naphthene, aromatic) analysis, ratios between each homologous types and the percentage of particular carbon type are considered as well as the distillation curve and the density of a stream. More strict product specifications and environmental legislations make strong restriction to the benzene and aromatics content in gasoline products, which motivate refiners to understand, characterise and simulate gasoline catalytic reforming on molecular-level. In this work, kinetic and reactor model of naphtha catalytic reforming is developed based on the proposed MTHS method. The naphtha feedstock composition is represented by the MTHS matrix, and a kinetic network is constructed according to conversions among matrix elements. A process model proposed by Wu (2010) is employed for reforming modelling. The proposed model is then applied to a bench-scale semi-regenerative catalytic reforming unit, which contains 3 fixed-bed reactors, for validation. The influences of essential operating conditions, such as reactor inlet temperature, pressure and weight hourly space velocity (WHSV), on the product distribution and quality are explored. The developed characterisation is also applied in gasoline blending modelling. A molecular-level nonlinear gasoline blending model is developed based on proposed MTHS method with validation. Key properties such as Octane Numbers (ONs) and RVP are blended by molecular matrix elements, and the influence of molecular composition on bulk properties is obvious. A case of recipe optimisation is studied to show the applicability of the proposed method. The implementation of the developed MTHS method for catalytic reforming and gasoline blending demonstrates the compatibility when characterising different petroleum streams, and provides a common platform to simulate and optimise refining operations on the same molecular basis.

The study takes an in-depth look at eight novels by white South African authors in which the main characters are black. The novels that were studied fell into two main categories, those that highlight (although not always to the same extent) the differences between white and black people and those in which the author takes care to depict the black main character as ‘a person just like any other’, or in which the emphasis is on the similarities between people regardless of race. The novels in the first category can be divided into purely fictional works on the one hand (Toiings (1934), Cry, the Beloved Country (1948) and Swart Pelgrim (1952)) and novels based on historical facts (Die Swerfjare van Poppie Nongena (1978) and Bidsprinkaan (2005)) on the other. In the fictional novels in this category, which are also the oldest/earliest of the selected novels, the narrator patronises the black main character, who is seen as naïve and in some cases at the mercy of baser urges. The researcher shows, however, that the intent of the authors was to gain the reader’s empathy for and understanding of the plight of the black character and, by implication, of black people in general. This applies regardless of whether the novel had an explicit political theme (e.g. Cry, the Beloved Country) or not (e.g. Toiings). The novels in the second category, i.e. those in which black characters are portrayed as not substantively different from white characters (Kennis van die Aand (1973), Proteus (2002) and Lerato (unpublished, 2011) also include novels in which the main theme is a political one (Kennis van die Aand) and those in which political issues are not central to the plot (Proteus) or in which there is hardly any reference to political issues at all (Lerato). The outcomes of the study show that the intention of the authors of the studied novels in the pre-apartheid era was to promote understanding and reconciliation and not to strengthen divisive stereotypes. While this cannot be measured in empirical terms, anecdotal evidence suggests that literature does contribute to social change, albeit in an indirect manner. Despite the harsh criticism (particularly from black authors and scholars) of the practice by white authors to make use of black main characters, it can be argued that, within the South African context, such novels have played a role in achieving mutual understanding and reconciliation. There is a notable shift in the post-apartheid novels. Rather than pleading the case of the black main character with the white audience, Meyer (2002) and Homann (2011) portray their black main characters as equal players in a diverse society. If literature is seen as a reflection of society, this is an encouraging sign that South Africa has substantively moved on from apartheid. / Dissertation (MA)--University of Pretoria, 2011. / Afrikaans / unrestricted