Gas chromatography - mass spectrometry (GC-MS) is an established instrumental technique used for the analysis of fire debris for accelerant detection. However, matrix problems, such as pyrolysis product interference, are still encountered. These interferences often lead to inconclusive interpretation of the chromatographic results. This study describes methods for analysing arson accelerants using gas chromatography coupled with ion trap mass spectrometry. The latter technique lends itself to both conventional (GC-MS) as well as tandem mass spectrometry (GC-MS-MS). Since petrol (gasoline) is one of the more common distillate blends used by arsonists, especially in South Africa, the identification of petrol in fire debris samples was investigated. In order to overcome pyrolysis product interference and improve detection selectivity of the aromatic hydrocarbons in petrol residues, tandem mass spectrometry was used in combination with capillary gas chromatography. The added parameter of the third dimension of selectivity proved to be superior to conventional GC-MS in obtaining characteristic aromatic hydrocarbon profiles for petrol without interference from pyrolysis artefacts. / Dissertation (MSc (Applied Chemistry))--University of Pretoria, 2007. / Chemistry / unrestricted

The Hersiliidae of the Afrotropical Region is revised and the phylogenetic positions of taxa within the family cladistically analysed. The following genera have been newly erected: Tyrotama gen. nov. for Tama arida and seven additional species, and Prima gen. nov. for P. ansieae spec. nov. and one additional species. The genera Murricia Simon and Neotama Baehr&Baehr are recorded for the first time from the Afrotropical Region. All valid species are redescribed. The following 20 species are newly described: Hersilia beva, H. bubi, H. caronae, H. dilumen, H. eloetsensis, H. moheliensis, H. plara, H. salda, H. taita, H. tamatavensis, H. unca, H. woutrinae, Murricia emlynae, M. uva, Prima ansieae, P. syda, Tyrotama gamkasiensis, T. taris, T. makalaliensis, T. Namibia. The males of T. arida and T. bicava are described for the first time. The following species have been synonymized: Hersilia segeregata Benoit with H. occidentalis Simon, Hersilia nossibeensis Strand with H. insulana Strand, Tama obscura Smithers with Tyrotama arida (Smithers). For Hersilia insulana Strand a lectotype and paralectotype have been designated; a neotype has been designated for H. vinsoni Lucas. Hersilia corticola Lawrence was transferred to Neotama and Hersiliopsis madagascariensis Wundelich was transferred to Hersilia Audouin. The following species remain doubtful: Hersilia kauderni Strand, H. stumpfi Strand, H. fossulata Karsch. A total of 47 hersiliid species are recorded for the Afrotropical Region. Keys are provided to the six genera of the Afrotropical Hersiliidae and the species of Hersilia and Tyrotama. A cladistic analysis based on 48 characters and 22 species inferred the following phylogeny: ((Hersiliola Tyrotama) (Neotama (Prima (Murricia Hersilia)))). Morphological data supports the monophyly of Tyrotama and the phylogeny suggests that the genus is not closely related to Tama. The new genus Prima is weakly supported as the sister taxon of Neotama. Support for the genus Hersilia is weak and synapomorphies that unite five identified species groups within the genus are much more consistent than those that unite Hersilia. However, the genus Hersilia is retained until a comprehensive generic level analysis for the world is conducted. / Thesis (PhD (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / unrestricted

The research proposes that the adoption of a hybrid leadership and governance framework by the South African public service is crucial for improving service delivery in South Africa. The leadership and governance framework of the South African public service has had a negative impact on its effectiveness and efficiency. The study analysed service delivery performance in four South African public service departments against the backdrop of their leadership and governance frameworks, namely: Departments of Health, Housing, Justice and Constitutional Development and Safety and Security. The study found that the frameworks currently in use are not very effective in redressing service delivery imbalances and inequities in South Africa, especially in previously disadvantaged communities. The needs and demands of the South African public are not being adequately met. The study found that there are a number of interrelated variables, which were hampering the effectiveness of the public service. The most important of these variables were identified as human resource and financial constraints, the lack of technical skills, the lack of co-ordination, ineffective intergovernmental relations (IGR) between the three spheres of government, ineffective policy implementation, conflict between the classical public administration model and the new public management (NPM) paradigm, and the lack of effective monitoring and evaluation systems. In view of the challenges facing the South African public service, this thesis presents an alternative, hybrid leadership and governance model. This model has been designed in response to the unique circumstances faced by the public service in the post-apartheid era (post-1994) public service. It requires a conception of public service leadership and governance that draws on various relevant approaches while adapting these to the prevailing local narratives already existing in the country. It incorporates traditional African ethics and values, transformational leadership and team leadership, and encompasses effective governance approaches, such as civic governance. It also includes accountability, transparency and public participation. It is evident from the four cases presented herein, that such transformation is crucial for improving the effectiveness and efficiency of the South African public service. The leadership and governance framework developed in this study is flexible, as it can be applied to diverse settings and circumstances. This study thus advances a pragmatic transformational African model for the improvement of service delivery in South Africa. / Thesis (PhD (Public Affairs))--University of Pretoria, 2004. / School of Public Management and Administration (SPMA) / unrestricted

No other references could be found in the literature where IVP embryos, exposed to FMDV were rendered free of the virus. To the best of my knowledge this is the first report that describes the association of FMDV with IVP embryos during IVM and IVF. Also, this is the first description of a treatment protocol where IVP embryos can be cleared of infective FMDV. Washing embryos in accordance with IETS regulations was ineffective in clearing FMDV from IVP embryos when IVM and IVF were done in the presence of FMDV; however, treatment with acid as described during these experiments was effective for achieving FMDV - free IVP embryos. This work might enable the production of IVP embryos in countries where FMDV is endemic, permitting the subsequent movement of the embryos to other countries. Also, it might serve as a way of preserving genetic material from animals during an outbreak of the disease, in countries where FMD is not endemic, through the production of disease-free embryos. This work might also be of use to the wildlife industry in South Africa. If a protocol was developed for the in vitro production of game animal embryos, notably buffalo, treatment with MES could enable the production of embryos free of FMDV. This would facilitate movement of embryos from areas in South Africa where FMDV is endemic. / Dissertation (MMedVet (Gyn))--University of Pretoria, 2005. / Production Animal Studies / unrestricted

An investigation of complaints about the cause of poor product quality and performance pointed to critical control points (CCP’s) in the pelleting process that were either absent or not monitored and controlled. The non-conformance cost due to poor pellet quality and product inconsistency is quite significant. The positive relationship between pellet quality and animal performance is well known. Poor and inconsistent quality of pelleted feed is the consequence of many contributing factors such as formulation, processing variables, people and the manufacturing environment, which affect pellet quality either individually or in combination. Data collected on the control of some critical elements in the production process revealed that many production parameters are often not closely monitored or controlled, and that quality control limits are often poorly enforced or non-existent, explaining the varying causes for complaints on the quality and inconsistency of pelleted feed. Production facilities differ in layout and the success of a Hazard Analysis Critical Control Point (HACCP) program exists in its systematic method of process analysis, applying appropriate risk controls and timely corrective protocols. Modified HACCP programs can be utilized to reduce process parameter variation resulting in improved product quality and consistency. A HACCP system modified for the pelleting environment was used as an intervention tool to address poor pellet quality and product inconsistency in a broiler feed mill. Implementation of the system was achieved by measuring the quality and variability of products and processes prior to implementation. The processing layout was identified, analysed, CCP’s and limits set after which the CCP’s were measured and compared to ideal targets. Corrective actions and changes to the production process were prioritised in order of each CCP’s contribution to pellet quality. Monitoring, control and corrective protocols were introduced for CCP’s through consecutive training and work sessions. Re-assessment of the pellet quality and product variation concluded the intervention phase. Data analysed from the first phase helped to facilitate the restructuring of the production process and the implementation of improvement phases. Systematic analysis identified formulation (fat addition levels and point of addition) and mash grinding fraction as key areas of improvement. This was achieved by lowering the fat percentage in the mixer from 3.50 to 0.5%, thereafter adding the fat by means of a post pelleting fat coater. The coarse pre-pelleting mash fraction (particle size being above 2360mm), was reduced from 28.5 to 1% on average and the ideal target particle size (being from 600mm to 1440mm), was increased from 20.5 to 51% on average. This increase was achieved by correcting and improving grinding operation with a larger capacity hammermill. Conditioning temperature increased from 64.5 to 74.5oC. Correcting the above changes to critical factors contributed to increasing the pellet percentage of the final product at loading from 63.05 to 86.18%. Improved monitoring of CCP’s and timely corrective protocols led to a further improvement in loaded pellet percentage from 86 to 90% and also improved the repeatability in obtaining better pellet quality at loading. The STDEV of the final product pellet percentage showed an improvement of 13.3 to 5.39. Hazard analysis and the collection of data helped in identifying further areas of improvement. In conclusion, the HACCP system as implemented in this plant, resulted in the improvement of pellet quality (percentage of pellets at loading and pellet durability) as well as a reduction in its variability. It is recommended that HACCP systems should be used more pro-actively as a quality assurance tool for process improvement, assuring product safety, reducing process variation and increasing product quality. / Dissertation (MSc (Production Animal Studies))--University of Pretoria, 2003. / Production Animal Studies / unrestricted

No abstract available / Researchers require an accurate measurement of fertility in the bitch for the comparison ofinsemination methods, assessing the effects of procedures on fertility and assessing the effectsof drugs on fertility. In clinical practice, a prospective measurement would enable thepractitioner to select bitches with the largest numbers of follicles for breeding by artificialmeans or natural mating with valuable semen or studs. The ratio between the numbers ofcorpora lutea or follicles and litter size is a more sensitive measurement of fertility than islitter size, as the latter does not reflect the total number of oocytes that were available forfertilization. Magnetic resonance imaging (MRI) has proven to be of value in diagnosticimagery of particularly soft tissues. This is the first study that evaluated the use of MRI incanine reproduction and was done to determine whether the numbers of corpora lutea orfollicles can be counted accurately by means of MRI.The study was divided into two experiments. In Experiment 1, 16 bitches were used. Apartfrom one bitch that was in anoestrus, they were either in the follicular, early, or late lutealphase. Their ovaries were collected via ovariohysterectomy and placed into a phantom forMRI. The phantom was then scanned in three planes with a slice interval and slice thickness of 1 mm, using a 1.5 Tesla SIEMENS Magnetom Symphony scanner. A circular polarizedhead array coil was also used around the phantom. The T2-weigthed images were consideredbetter than T1-weighted images. This study showed that although the corpora lutea or folliclescould be identified in most but not all images, it was not possible to accurately count thenumber of corpora lutea or follicles in the ovaries of bitches using MRI techniques andapparatus commonly used in human MRI units. Follicles were commonly confused withcorpora lutea on the images. Although the study was not designed to detect ovarian pathology,MRI of the ovary in the phantom study, showed promise in detecting cystic ovarian disease.In Experiment 2, it was attempted to find the ovaries, and count the structures in them, bydoing MRI on two live, sedated bitches that were in the late follicular phase, whereafter thebitches were spayed and the ovarian structures counted. The effect of motion was so great thatno image could be generated on which any ovary or its structures could be identified.There still exists no reliable, non-invasive means by which the number corpora lutea orfollicles can be counted in the bitch. Further studies are required to evaluate more advancedMRI techniques and apparatus. / Navorsers benodig 'n akurate meting van vrugbaarheid in die teef vir die vergelyking vaninseminasiemetodes en vir die beoordeling van die effekte van prosedures en middels opvrugbaarheid. In praktyk sou veral 'n prospektiewe meting van vrugbaarheid nuttig wees,omdat dit die klinikus in staat sal stel om daardie tewe met die grootste aantal follikels teselekteer vir teling in gevalle waar die koste van òf die semen òf dekking baie hoog is. Dieverhouding tussen die aantal korpora lutea of follikels en werpselgrootte is 'n sensitiewermaatstaf van vrugbaarheid as werpselgrootte op sigself; omdat laasgenoemde nie dievolledige aantal oösiete wat beskikbaar was vir bevrugting in bereken bring nie. Magnetieseresonansie beelding (MRB) is reeds bewys as 'n waardevolle tegniek vir die verkryging vandiagnostiese beelde van veral sagte weefsels. Hierdie is die eerste studie wat die gebruik vanMRB op die geslagstelsel van honde beoordeel en was spesifiek uitgevoer om vas te stel ofdie korpora lutea of follikels in die eierstokke van tewe d.m.v. MRB akkuraat getel kan word.Die studie was verdeel in 2 eksperimente. In Eksperiment 1 was 16 tewe gebruik. Behalwe vireen teef wat in anestrus was, was hulle òf in die follikulêre fase, òf in die vroeë òf in die laatluteale fases. Hul eierstokke was versamel deur middel van ovariohistorektomie en in 'nfantoom geplaas vir MRB. Die fantoom was geskandeer in drie oriëntasies reghoekig totmekaar, en 'n snitdikte en 'n snitinterval van 1mm is gebruik. Die MRB aparaat was 'n 1.5 Tesla SIEMENS Magnetom Symphony skandeerder. 'n Kopspoel was gebruik rondom diefantoom. Die T2-gerigte beelde was beter as die T1-gerigte beelde. Hierdie studie het getoondat alhoewel die korpora lutea of follikels in die meeste beelde van die eierstokkegeïdentifiseer kan word, dit nie moontlik is om hierdie strukture in die eierstokke van tewe tetel m.b.v. die apparaat wat oor die algemeen in die gemidelde privaathospitaal beskikbaar isnie. Dit was ook nie moontlik om altyd korpora lutea van follikels te onderskei nie. Alhoeweldie studie nie ontwerp was om vir patologiese letsels op die eierstokke te soek nie, was diemeeste ovariële siste duidelik sigbaar op die beelde in die fantoomstudie, wat daarop dui datMRB in hierdie verband belowend mag wees.In Eksperiment 2 is gepoog om die eierstokke in twee lewendige tewe wat laat in diefollikulêre fase en onder berusting was, d.m.v. MRB op te spoor en die strukture daarin te tel,waarna 'n ovariohisterektomie op elke teef uitgevoer was en die strukture getel was. Die effekvan beweging wat deur asemhaling teweeg gebring is was egter só groot dat daar geen beeldgegenereer kon word waarop 'n eierstok of sy strukture herken kon word nie.Daar bestaan steeds geen betroubare manier, anders as disseksie van die eierstokke, om diefollikels of korpora lutea indie eierstokke van tewe akkuraat te tel nie. Verdere navorsing isnodig om meer gevorderde MRB tegnieke en apparaat vir hierdie doel te evalueer. / Dissertation (MMedVet (Reproduction))--University of Pretoria, 2005. / Production Animal Studies / unrestricted

Large epidemics of poliomyelitis spread across the world in the first half of the 20th century. However, polio incidence fell rapidly across the world following the introduction of the oral poliovirus vaccine (OPV). Since the introduction of immunisation with OPV, the vaccine had a remarkable track record of success, because the number of wild-type polio cases decreased from 350 000 to 500 and the number of polio endemic countries declined from 125 to 10. Thus, the global eradication of wild-type poliovirus (PV) seems a realistic goal for the foreseeable future. Despite its many advantages, one disadvantage of the OPV is the potential risk of revertants of the OPV strains, which may cause neurological complications in vaccine recipients and susceptible contacts. Immunocompetent persons excrete OPV strains for a limited period of time. In contrast, immunodeficient people may become chronically infected and excretion times as long as 10 years have been reported. As a consequence, in the last phase of polio eradication this group of people may serve as potential reservoirs for vaccine-derived polioviruses (VDPVs). Two cases of vaccine-associated paralytic poliomyelitis have been reported in human immunodeficiency virus (HIV)-positive children, although, presently there is no evidence for prolonged excretion of PV from patients with HIV and acquired immunodeficiency syndrome (AIDS). Highly evolved VDPVs have been isolated from sewage and river water even in the absence of cases of paralytic poliomyelitis. This study aimed to investigate the prevalence of PVs in sewage and river water as well as in stool specimens of HIV-positive children (including those with an AIDS indicator condition according to the Centers for Disease Control and Prevention classification). Secondly, the study investigated the occurrence of genomic mutations in these OPV isolates. A total of 49 PV vaccine strains were isolated from the sewage and river water, and 13 PV vaccine strains were detected in the stools of immunodeficient children. Two of the immunodeficient patients (vaccinated 15 months ago) tested positive for Sabin PVs type 1 and 3. Another immunodeficient patient (vaccinated 42 months ago) tested positive for Sabin PV type 1. The 5’untranslated and the VP1 regions in the genomes of the OPV isolates were partially sequenced. The majority of the OPV strains detected in the sewage and river water displayed >99% VP1 sequence identity to the original PV vaccine strains and were classified as “OPV-like viruses”. Two OPV isolates were identified as “suspected” VDPVs, since these isolates showed £99% VP1 sequence identity to the PV vaccine strains and had probably replicated in one or more people for 12 to 16 months since the administration of the initiating OPV dose. In contrast, three “suspected” immunodeficient VDPVs were identified in the stools of the immunodeficient children. All of the OPV-like and “suspected” VDPV isolates carried genomic mutations, which had been associated with reversion of the attenuated PV phenotypes to increased neurovirulence. The identification of OPV-like and “suspected” VDPVs in this study emphasised the fundamental importance regarding the control of health risks constituted by OPV vaccination, particularly with regard to immunodeficient individuals such as HIV-positive children, and the possible role of water in the transmission of potentially hazardous VDPVs. These research findings provided valuable data, concerning prolonged excretion of OPV strains by individuals with secondary immunodeficiency and this could have major implications for strategies aimed for the global post-polio eradication era. / Thesis (PhD (Medical Virology))--University of Pretoria, 2004. / Medical Virology / unrestricted

The rapid development and spread of bacterial resistance to antimicrobial drugs is an increasing threat to human and animal health. Information on the prevalence of bacterial resistance to specific antimicrobial agents in both humans and animals together with changes occurring over time, is required to understand the magnitude of the problem, to make decisions and to take actions that are based on risk assessment (3). The ultimate goal is to preserve the effectiveness of available antimicrobial drugs for the benefit of future generations of animals and humans. The emergence of resistance and the spread of resistant bacteria can be limited by implementing a veterinary antimicrobial drug policy, in which inter alia systematic monitoring and prudent use play essential parts (1). Testing the susceptibility of bacteria to antimicrobial drugs is fundamental to the study of resistance. Sensitivity testing serves two purposes: to provide reliable results to the prescriber of antimicrobial drugs and to monitor changes in susceptibility of microbial populations. Standardized methods are needed for surveillance in the national and international context and harmonization of methods to provide meaningful comparisons between individual centres and countries (1, 3). The objective of this study was to establish a repeatable, standardized laboratory procedure for monitoring the development of antimicrobial resistance in bacteria isolated from animals and food of animal origin in South Africa. The bacteria included in this study represented three different groups, namely zoonotic bacteria (Salmonella), indicator bacteria (Escherichia coli, Enterococcus faecalis, E. faecium) and veterinary pathogens (Mannheimia haemolytica). Thirty isolates of each organism were collected with the aim of standardizing the laboratory methodology for a future national veterinary surveillance programme. Susceptibility to 10 antimicrobial agents was determined by means of minimum inhibitory concentrations (MIC’s) using the microdilution method. The method according to the National Committee for Clinical Laboratory Standards was used as the standard. Susceptibility tests were repeated once for each individual organism. Quality control measures were included to ensure that accurate results were obtained. Repeatability was satisfactory as results from duplicate tests differed by only one twofold dilution. Multi-well plates prepared in-house for MIC determinations also yielded repeatable results after two months of storage at -70°C. Within this limited sample of bacteria, MIC results did not indicate meaningful resistance against any of the 10 selected antimicrobials. / Dissertation (MSc (Veterinary Tropical Diseases))--University of Pretoria, 2001. / Veterinary Tropical Diseases / unrestricted

The aim of this thesis is to prove the lifting property of zero divisors, n-zero divisors, nilpotent elements and a criteria for the lifting of polynomially ideal elements in C*-algebras. Chapter 1 establishes the foundation on which the machinery to prove the lifting properties stated above rests upon. Chapter 2 proves the lifting of zero divisors in C*-algebras. The generalization of this problem to lifting n-zero divisors in C*-algebras requires the advent of the corona C*-algebra, a result of the school of non-commutative topology. The actual proof reduces the general case to the case of the corona of a non-unital _-unital C*-algebra. Chapter 3 proves the lifting of the property of a nilpotent element also by a reduction to the case of the corona of a non-unital _-unital C*-algebra. The case of the corona of a non-unital _-unital C*-algebra is proved via a lifting of a triangular form in the corona. Finally in Chapter 4, a criterion is established to determine exactly when the property of a polynomially ideal element can be lifted. It is also shown that due to topological obstructions, this is not true in any C*-algebra. / Dissertation (MSc (Mathematics and Applied Mathematics))--University of Pretoria, 2004. / Mathematics and Applied Mathematics / unrestricted

This research seeks to examine the experience of educators regarding the support they receive from their principals during the implementation process of OBE at secondary school level. The study thus intends to explore the reaction of educators towards OBE as a newly introduced approach in South Africa and the impact of managerial support to educators towards the implementation of OBE. This study is a case study of two secondary schools at Vuwani in Limpopo Province. The study uses the questionnaires, face-to-face interview and focus group interviews to collect data. Questionnaires were distributed randomly among teachers of the two schools. The principals of the two schools were interviewed. Few educators were engaged in a focus group interviews. Categories and themes were used to analyse the data. Educators were given two weeks to complete and return the questionnaires. Each principal was interviewed once for an hour. Focus group interviews were conducted once in each school for a period of two hours. Letters to the principals and the educators of the respective schools were written to seek permission and positive participation in the case study. Five major themes emerged from the study: 1. Management and leadership skills 2. Resources 3. Workshops and / or courses and / or In-service training 4. Problem solving skills 5. Communication and networking / Dissertation (MEd (Education Management))--University of Pretoria, 2004. / Education Management and Policy Studies / unrestricted