A review of Southern African kimberlites and exploration techniques

The dissertation reviews the present knowledge regarding diamonds, from its formation in the lithospheric upper mantle at depths between 150 and 300 km, to its final valuation in terms of US$/carat by diamantaires in London, Antwerp, Tel Aviv and New York. The dissertation is divided into two complimentary sections. Section one focuses on the formation, emplacement, occurrence and characteristics of kimberlites and, when present, their associated trace amounts of diamonds. The section follows a logical sequence from the regional tectonic-, local structrual- and geodynamic controls on kimberlite formation and emplacement to the characteristics of individual kimberlite morphology, mineralogy, petrography and geochemistry. Finally, the environment or diamond formation, resorption and the characteristics that have led to the marketability of diamonds are discussed. Section two reviews the current exploration techniques used in locating diamondiferous kimberliies and the subsequent economic evaluation of these kimberlites. A brief history of known Southern African kimberlite occurrences, grades, tonnages, tectonic settings, ages and regional structural controls is given. The prospective countries mentioned are Angola, Botswana, Lesotho, South Africa, Swaziland, Tanzania and Zimbabwe. Exploration techniques considered are ; the application of a landscape analysis and investigation of the surface processes active in a given area, indicator mineral sampling (with reference to their mineralogy and exploration significance), remote sensing techniques (subdivided into satellite imagery and aerial photography), geophysical techniques (including the magnetic-, gravity-, electrical-, radiometric- and seismic methods as well as heat flow models), geochemical techniques, petrographic- and electron beam techniques as well as geobotanical- and geobiological techniques. Finally, a brief summary of current evaluation techniques employed on diamondiferous kimberlite deposits is presented. The review covers kimberlite sampling methods, sample processing, diamond grade distributions (with reference to the experimental variogram model, statistical methods used in grade distribution calculations as well as block definition and local grade estimation). Stone size distributions, including microdiamond counts and value estimation, are also discussed.KMBT_363Adobe Acrobat 9.54 Paper Capture Plug-i

Improved characterization of protein sources and implications on evaluation of rations for dairy cows

Thesis (MScAgric)--Stellenbosch University, 2017.ENGLISH ABSTRACT: This study looked at a recent development in a new laboratory assay used to determine the unavailable nitrogen (uN) fraction in non-forage feeds. The need for this new assay was brought about as the current methods used to determine the uN fraction provide inconsistent results with varying amounts of AA being liberated. Furthermore, the need to improve nitrogen utilization efficiency (NUE) in dairy cows is necessary to reduce harmful waste to the environment and decrease feed costs. For that reason an effective approach to improve NUE, as well as improve protein characterization, is by improving the estimation of protein fractions such as the unavailable one. However, due to the assay being a novel procedure the implementation of the procedure in our laboratory required slight modifications in order to replicate the procedure. Nonetheless, successful results were obtained on 19 protein sources that are commonly used in South Africa with comparable values being achieved in different laboratories. Although the procedure was developed to determine the uN fraction, it became apparent that the rumen degradable (RDP) and undegradable protein (RUP) fractions need to be determined in order to quantify uN. Consequently, the new assay has provided a drastic improvement in past procedure to determine the uN fraction with comparable values for both RDP and RUP in the literature. As for the uN fraction, the new assay reports significantly higher values than previously presumed ranging from 34.53g kg-1 CP in sunflower meal to 447.70 g kg-1 CP in feather meal. These values indicate that there has been a drastic underestimation in the uN fraction, which has resulted in high levels of N excretion as well as an unnecessary expense for the farmer. The uN fraction, and relative assay, has also been recently implemented in the Cornell Net Carbohydrate and Protein System (CNCPS) which in addition to the former acid detergent insoluble nitrogen (ADIN) method, allows for a comparison to be made between the different procedures. Using this nutritional model to make this comparison in 10 rations that were supplied to us, it was evident that NUE could be improved in addition to income over feed costs (IOFC). When implementing the uN fraction, as opposed to the traditional detergent system, the rations resulted in a reduction of IOFC from R0.10 to R39.50 per cow/day. In addition, the nutritional model showed a range of milk loss from 0.31 l to 7.90 l per cow/day as a result of the true protein unavailable to the animal. Moreover, by optimizing the rations for both IOFC and productive N, an improved composition was noted which resulted in an improved IOFC ranging from R0.16 to R7.16 per cow/day. However, owing to the new assay being a novel and an in vitro procedure, we would recommend further studies on both in vitro and in vivo trials to confirm our findings.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaa

Inclusion body hepatitis associated with an outbreak of fowl adenovirus type 2 and type 8b in broiler flocks in South Africa

Inclusion body hepatitis is an acute disease of chickens ascribed to viruses of the genus Aviadenovirus and referred to as fowl adenovirus (FAdV). There are 12 FAdV types (FAdV1 to FAdV8a and FAdV8b to FAdV11), classified into five species based on their genotype (designated FAdVA to FAdVE). A total of 218 000 chickens, 2–29 days of age, were affected over a 1-year period, all testing positive by microscopy, virus isolation and confirmation with polymerase chain reaction (PCR). Affected birds were depressed, lost body weight, were weak and had watery droppings. Pathological changes observed during necropsy indicated consistent changes in the liver, characterised by hepatomegaly, cholestasis and hepatitis. Lesions were also discernible in the spleen, kidney and gizzard wall and were characterised by splenomegaly, pinpoint haemorrhages, nephritis with haemorrhage,visceral gout and serosal ecchymosis of the gizzard wall. Histopathological lesions were most consistently observed in the liver but could also be seen in renal and splenic tissue. Virus isolation was achieved in embryonated eggs and most embryos revealed multifocal to diffuse hepatic necrosis, with a mixed cellular infiltrate of macrophages and heterophils (necro-granulomas), even in the absence of macroscopic pathology. Virus isolation results were verified by histopathology and PCR on embryonic material and further characterised by nucleotide sequence analysis. Two infectious bursal disease virus isolates were also made from the Klerksdorp flock. Nucleotide sequence analysis of the L1 hexon loop of all the FAdVisolates indicated homology (99%) with prototype strains P7-A for FAdV-2, as well as for FAdV-8b

Molecular differentiation and pathogenicity of Aviadenoviruses isolated during an outbreak of inclusion body hepatitis in South Africa

Fowl adenovirus (FAdV) is a member of the genus Aviadenovirus and causes a number of economically important poultry diseases. One of these diseases, inclusion body hepatitis (IBH), has a worldwide distribution and is characterised by acute mortality (5% - 20%) in production chickens. The disease was first described in the United States of America in 1963 and has also been reported in Canada, the United Kingdom, Australia, France and Ireland, but until now, not in South Africa. Adenoviruses isolated from the first outbreak of IBH in South Africa were able to reproduce the disease in chicken embryo livers. The aim of the present study was to characterise the viruses and determine the pathogenicity of the FAdV strains responsible for the first reported case of IBH in South Africa. Polymerase chain reaction (PCR) amplification of the L1 loop region of the fowl adenovirus hexon gene using degenerate primer pair hexon A/B was used to identify the viruses that were isolated. Restriction fragment length polymorphism (RFLP) of the amplification products was used for the differentiation of 14 isolates of fowl adenovirus. Sequencing of the PCR products followed by amino acid comparison and phylogenetic analysis using the L1 loop region of the hexon protein was done to determine the identity of the isolates. Amino acid sequences of the hexon genes of all the South African isolates were compared with those of reference strains representing FAdV species. Amino acid comparison of 12 South Africa field isolates to FAdV reference strains revealed a high sequence identity (> 93.33%) with reference strains T8-A and 764. Two of the isolates had high sequence identity (93.40%) with reference strains P7-A, C2B and SR48. Phylogenetic analysis of the L1 loop region of the hexon protein of all 14 South African isolates was consistent with their RFLP clusters. The mortality rates of embryos challenged with 10(6) egg infective doses (EID50) FAdV 2 were 80% - 87% and mortality rates for embryos challenged with 10(5.95) (EID50) FAdV 8b were 65% - 80%

Molecular phylogeny of Duvenhage virus

The Duvenhage virus (DUVV) constitutes one of the 11 species in the Lyssavirus genus and causes fatal rabies encephalitis. The virus is associated with insectivorous bat species and three human cases have been reported, all of which were linked to contact with bats. Few of these isolates have been studied and thus little is known about the phylogeny and epidemiology of this lyssavirus. Until 2007, when an isolate was made from the East African country of Kenya, all isolations of this virus had been from southern Africa. This discovery led to many questions regarding the spread and diversity of this lyssavirus. Phylogenetic analysis indicated that the DUVV isolates constitute two different lineages, in which the southern African isolates group together to form one lineage and the more recent isolate from Kenya constitutes a new, second lineage. We found that the new isolate has a genetic variation that has not yet been seen for DUVV. Not only is our lack of knowledge regarding the geographical distribution of this uniquely African virus emphasised, but we have also demonstrated the potential diversity within this genotype.http://www.sajs.co.z

Occurrence of Babesia felis and Babesia leo in various wild felid species and domestic cats in Southern Africa, based on reverse line blot analysis

Reverse line blot (RLB) is a hybridization assay that can be used to detect various blood parasites and differentiate between them. Results, using the RLB, showed that Babesia felis and Babesia leo occurred as single or mixed infections in various felid species, but most frequently in domestic cats and lions, respectively. Prevalence of infection in free-ranging cheetahs in Namibia was low (7, 5%), whereas 50% of free-ranging lions in South Africa and Swaziland were infected. A large number (52, 9%) of samples tested positive only for Babesia, neither B. felis nor B. leo. This could be an indication of at least one further, as yet undescribed, Babesia species in felids.Mrs. Gerty Pretorius (Clinical Pathology Section, Department of Companion Animal Clinical Studies), and Prof. Moritz van Vuuren (Department of Veterinary Tropical Diseases) submitted blood specimens. This report emanates from project 36-5-613 which was approved by the Research Committee of the Faculty of Veterinary Science and the Animal Use and Care Committee of the University of Pretoria

Observable dynamic models of reagent effects for model based froth flotation control

This article demonstrates the feasibility of including simple reagent addition models in an existing observable dynamic model of a froth flotation circuit. The existing model has full state observability and parameter identifiability using measurements that are commonly available on flotation circuits. This article qualitatively evaluates the possible impact of varying frother dosage on the model parameters. A Sobol sensitivity analysis indicates that the air recovery model parameters are most influential in the determination of grade and recovery. The model is expanded with two different reagent effect models. Both expansions include mass balance models of the frother concentration in each cell. The first model expands an empirical parameter in the air recovery model, related to the froth height at which peak air recovery (PAR) is achieved, as a linear function of frother concentration. The second model adds a linear frother concentration term to the existing air recovery model to modify the steady-state air recovery directly. Observability analyses of the expanded models show that all states and the important time-varying model parameters are observable (and identifiable) from the available on-line measurements. Most importantly, the frother concentrations are shown to be observable without concentration measurements. Simulations of the model expansions show that the second model can qualitatively predict the impact of increased frother dosage on air recovery, grade, and recovery, while the first model can only predict the correct effect under certain conditions.https://www.journals.elsevier.com/ifac-papersonlineElectrical, Electronic and Computer Engineerin

Molecular differentiation and pathogenicity of Aviadenoviruses isolated during an outbreak of inclusion body hepatitis in South Africa

Fowl adenovirus (FAdV) is a member of the genus Aviadenovirus and causes a number of economically important poultry diseases. One of these diseases, inclusion body hepatitis (IBH), has a worldwide distribution and is characterised by acute mortality (5% – 20%) in production chickens. The disease was first described in the United States of America in 1963 and has also been reported in Canada, the United Kingdom, Australia, France and Ireland, but until now, not in South Africa. Adenoviruses isolated from the first outbreak of IBH in South Africa were able to reproduce the disease in chicken embryo livers. The aim of the present study was to characterise the viruses and determine the pathogenicity of the FAdV strains responsible for the first reported case of IBH in South Africa. Polymerase chain reaction (PCR) amplification of the L1 loop region of the fowl adenovirus hexon gene using degenerate primer pair hexon A/B was used to identify the viruses that were isolated. Restriction fragment length polymorphism (RFLP) of the amplification products was used for the differentiation of 14 isolates of fowl adenovirus. Sequencing of the PCR products followed by amino acid comparison and phylogenetic analysis using the L1 loop region of the hexon protein was done to determine the identity of the isolates. Amino acid sequences of the hexon genes of all the South African isolates were compared with those of reference strains representing FAdV species. Amino acid comparison of 12 South Africa field isolates to FAdV reference strains revealed a high sequence identity (> 93.33%) with reference strains T8-A and 764. Two of the isolates had high sequence identity (93.40%) with reference strains P7-A, C2B and SR48. Phylogenetic analysis of the L1 loop region of the hexon protein of all 14 South African isolates was consistent with their RFLP clusters. The mortality rates of embryos challenged with 106 egg infective doses (EID50) FAdV 2 were 80% – 87% and mortality rates for embryos challenged with 105.95 (EID50) FAdV 8b were 65% – 80%.http://www.jsava.co.zaam201

A morphological study of the shape of the corpus callosum in normal, schizophrenic and bipolar patients

Abnormalities in the morphology of the corpus callosum have been found to be involved in cognitive impairments or abnormal behaviour in patients with mental disorders such as schizophrenia and bipolar disorder. The present study investigated morphological shape differences of the corpus callosum in a large cohort of 223 participants between normal, schizophrenic and bipolar patients on MRI scans, CT scans and cadaver samples. Healthy samples were compared to a mental disorder population sample to determine morphological shapes variations associated with schizophrenia and bipolar disorder. Landmark-based methodology was used to contour the corpus callosum shape that served as standard positions to allow for radial and thickness partitioning in order to determine shape variations within the specific localised anatomical sections of the corpus callosum. Shape analysis was performed using Ordinary Procrustes averaging and superimposing landmarks to define an average landmark position for the specific regions of the corpus callosum. No significant global shape differences were found between the different mental disorders. Schizophrenia and bipolar shapes differed mostly in the genu-rostrum, posterior body, isthmus and splenium. Sample group comparisons yielded significant differences between all groups and global measurement parameters and in various sub-regions. The findings of the present study suggest that the corpus callosum in schizophrenia and bipolar differs significantly compared to healthy controls, specifically in the anterior body and isthmus for schizophrenia and only in the isthmus for bipolar disorder. Shape changes in these regions may possibly, in part, be responsible for the symptoms and cognitive impairments observed in schizophrenia and bipolar disorder.http://wileyonlinelibrary.com/journal/joahj2023AnatomyPhysiolog

Sibling Support Program: A Family-Centered Mental Health Initiative

Sibling Support Program: A Family-Centered Mental Health Initiative was developed at the Eunice Kennedy Shriver Center of the University of Massachusetts Medical School. The project is currently implemented at Cambridge Health Alliance in Cambridge, Massachusetts as an IRB-approved research study, and at another Boston-based hospital as a Quality Improvement (QI) initiative. The program was also piloted at Boston Children\u27s Hospital in Boston, Massachusetts. The project explores the impact of mental illness on typically developing siblings and caregivers of children with psychiatric needs. Project goals: to increase resiliency and mitigate the trauma commonly experienced by siblings of children admitted for psychiatric hospitalization; to build skills, competency and confidence among parents; to help restore family stability post-discharge; to build capacity among medical practitioners. Interventions include psycho-educational groups for caregivers, and sibling support groups for children growing up alongside the patient. Participants complete surveys following the intervention to report on knowledge learned, satisfaction level, and behavioral change anticipated by the participant. Over 1,500 participants have participated in this innovative program that utilizes parent mentors and medical trainees to deliver interventions, with high satisfaction scores among participants. Results suggest that a child\u27s mental illness can be traumatic for family members, and that sharing stories can alleviate the stress and anxiety related to living in a home with a child with mental illness. The program serves as a training rotation for psychiatry residents through Harvard Medical School