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Thesis (MSc. (Vet. Trop. Diseases))--University of Pretoria, 2004. / Includes bibliographical references.

Inventory management is an important part of a good functioning logistic. Nearly all the literature on optimal inventory management uses criteria of cost minimization and profit maximization. To have a well functioning forecasting system it is important to have a balance in the inventory. But, it exist different factors that can results in uncertainties and difficulties to maintain this balance. One important factor is the customers’ demand. Over half of the stocked items are in stock to prevent irregular orders and an uncertainty demand. The customers’ demand can be categorized into four categories: Smooth, Erratic, Intermittent and Lumpy. Items with a lumpy demand i.e. the items that are both intermittent and erratic are the hardest to manage and to forecast. The reason for this is that the quantity and demand for these items varies a lot. These items may also have periods of zero demand. Because of this, it is a challenge for companies to forecast these items. It is hard to manage the random values that appear at random intervals and leaving many periods with zero demand. Due to the lumpy demand, an ongoing problem for most organization is the inaccuracy of forecasts. It is almost impossible to predict exact forecasts. It does not matter how good the forecasts are or how complex the forecast techniques are, the instability of the markets confirm that the forecasts always will be wrong and that errors therefore always will exist. Therefore, we need to accept this but still work with this issue to keep the errors as minimal and small as possible. The purpose with measuring forecast errors is to identify single random errors and systematic errors that show if the forecast systematically is too high or too low. To calculate the forecast errors and measure the forecast accuracy also helps to dimensioning how large the safety stock should be and control that the forecast errors are within acceptable error margins. The research questions answered in this master thesis are: How should one calculate forecast accuracy for stocked items with a lumpy demand? How do companies measure forecast accuracy for stocked items with a lumpy demand, which are the differences between the methods? What kind of information do one need to apply these methods? To collect data and answer the research questions, a literature study have been made to compare how different researchers and authors write about this specific topic. Two different types of case studies have also been made. Firstly, a benchmarking process was made to compare how different companies work with this issue. And secondly, a case study in form of a hypothesis test was been made to test the hypothesis based on the analysis from the literature review and the benchmarking process. The analysis of the hypothesis test finally generated a conclusion that shows that a combination of the measurements WAPE, Weighted Absolute Forecast Error, and CFE, Cumulative Forecast Error, is a solution to calculate forecast accuracy for items with a lumpy demand. The keywords that have been used to search for scientific papers are: lumpy demand, forecast accuracy, forecasting, forecast error.

Jaw disease in kangaroos and wallabies, while uncommon in animals living in the free state, is a major cause of death in captive macropods. There are two major schools of thought regarding its aetiology. The first accepts the findings of Fox (1923) and considers the disease to be actinomycosis while the second believes jaw disease to be one manifestation of necrobacillosis. Regardless of the belief of the authors the clinical and pathological descriptions indicate the condition attacking macropods throughout the world is a single disease. / Over one hundred affected macropods were examined during the course of this study and few species were found to be spared from jaw disease. Cases of lumpy jaw most commonly occurred in the winter months. All ages of macropods were affected although a higher prevalence was recorded in younger animals; however this may have been a reflection of the age of macropods in the zoo under study. The most common site of infection was the premolar and anterior molar region of the oral cavity, regardless of the age of the animal. The gross pathological findings were similar to the descriptions of affected animals by various authors throughout the world. The site of infection could generally be recognized at the gingival crevice, commonly between teeth, and excessive calculus formation associated with gingivitis and gingival recession was a common finding in affected animals. Penetration of the gingival mucosae by plant fibre was not found to be a significant predisposing factor in the initiation of the disease. (For complete abstract open document.)

Thesis (MMedVet (Reproduction))--University of Pretoria, 2006. / Includes bibliographical references.

Thesis (MSc. (Veterinary Science))--University of Pretoria, 2006. / Includes bibliographical references.

Thesis (Ph.D.)(Genetics)--University of Pretoria, 2006. / Includes summary. Available on the Internet via the World Wide Web.

Please read the abstract in the section 00front of this document / Dissertation (MSc (Genetics))--University of Pretoria, 2006. / Genetics / unrestricted

In this study, the genomes of both the attenuated South African lumpy skin disease virus (LSDV) Neethling vaccine strain (LW) and a virulent field isolate from a recent outbreak namely the South African lumpy skin disease virus (LSDV) Neethling Warmbaths isolate (LD) have been cloned, sequenced and analysed. The genomic sequences of the South African LSDV Neethling Warmbaths isolate (LD) and the South African LSDV Neethling vaccine strain (LW), were compared to each other. The virulent South African isolate, LD was also compared to the previously sequenced virulent LSDV Neethling strain 2490 (LK), to determine molecular differences. The LSDV genome is approximately 150 kbp in size and consists of 156 putative genes. Of the 156 potential encoded proteins of the virulent LSDV field isolates, the South African LSDV Neethling Warmbaths isolate (LD) and the LSDV Kenyan Neethling strain 2490 (LK), 120 were identical, 21 showed differences of a single amino acid, 7 showed two amino acid differences, while only one showed three amino acid differences. These were mostly found in the variable terminal regions. The LSDV Kenyan Neethling strain 2490 (LK) was isolated in Kenya in 1958 and than re-isolated in 1987 from lesions of an experimentally infected cow (Tulmanet al. 2001). The South African LSDV Neethling Warmbaths isolate (LD) was isolated from lesions of a severely infected calf in the Northern Province of the Republic of South Africa, on the farm Bothasvlei in 2001 (David Wallace, Biotechnology Division, Onderstepoort Veterinary Institute, Republic of South Africa; Personal communication, 2001). Considering the geographically distant African regions of the isolates, namely South Africa (LD) and Kenya (LK) as well as the time when these viruses were isolated, minimal genetic variation was observed thereby suggesting that lumpy skin disease virus is genetically stable. When the attenuated vaccine strain (L W) was compared with the South African field isolate LD, a total of 480 amino acid differences were observed in 121 of the 156 potential encoded proteins. These were again mainly in genes of the terminal regions and a number of these led to frameshifts that caused truncated open reading frames (ORFs) as well as deletions of up to nine amino acids and insertions of up to 42 amino acids. These modified open reading frames (ORFs) encode proteins that are involved in various aspects, such as the regulation of host immune responses [a soluble interferon (IFN)-gamma receptor, and an interleukin-l (IL-l) receptor-like protein], gene expression (mutT motif proteins), DNA repair (superoxide dismutase), host-range specificity (ankyrin-repeat protein, kelch-like proteins) including proteins with unassigned functions. These differences could lead to a reduction in immuno evasive mechanisms and virulence factors present in attenuated LSDV strains. At this stage, it is not possible to define which amino acid differences in particular are responsible for dramatic alterations in viral virulence. A good indication, however are differences occurring in functional domains. A mutation in a trans-membrane region, for example, could alter the levels of secretion of a protein involved in the regulation of the host immune response. We conclude that the attenuated effect is likely to be the sum of the altered phenotypes of the expressed proteins, although it is also likely that a few specific proteins carry more weight. Further studies to determine the functions of the relevant encoded gene products will hopefully confirm this. The molecular design of an effective vaccine is likely to be based on the strategic manipulation of such genes. / Dissertation (MSc (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Please read the abstract in the section 00front of this document / Dissertation (MSc (Microbiology))--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted