A comparative study of the geohydrology of archaean formations and associated rocks in the North-Western Transvaal and the North-Western Cape Province

An area of 4 400 km² in the North-western Transvaal is compared to an area of 75 000 km² in the North-western Cape Province with regard to geology, physiography, and hydrology. In the Transvaal the Archaean Formations range from the Swaziland System to the Dominion Reef System, with younger intrusives and a cover of Tertiary to Recent ferricrete, calcrete and soil. In the Cape Province the comparable formations are the Kheis System to the Soetlief Formation, younger intrusives and a Tertiary to Recent cover of wind-blown sand, calcrete and soil. The available literature on the geological formations and structure is reviewed. Outcrops are scarce in the Transvaal in an almost featureless tree-covered plain with ill-defined drainage, except for the two perennial rivers. In the Cape Province relief is higher and drainage better developed towards the perennial Orange River. Large portions of the Bushmanland Plateau are nevertheless, covered by sand and calcrete, without well-developed drainage. The rain falls during summer in both areas, and the average annual rainfall is 526 mm in the Transvaal, and 176 mm in the Cape Province. In both areas the farms and villages are almost entirely dependant on ground-water supplies. The importance of geophysical methods in the selection of borehole sites is stressed, and a summary is given of the more important geological and geophysical procedures and methods in both areas. This included magnetic, electromagnetic, and electrical resistivity methods. A summary is given of previous hydrological investigations in both areas. It was fragmentary, and only a few reports from the Cape Province could be traced. The results of a total of nearly 1 500 boreholes drilled in Archaean Formations in the Transvaal, and nearly 3 800 boreholes drilled in these formations in the Cape Province are analysed with respect to different parameters. Boreholes are classified according to the geological formation in which they occur, and the physiographical conditions ruling in the area. In the different formations in the Transvaal, the (percentage of successful boreholes ranged from 30 per cent in the Dominion Reef System to 38 per cent in the Archaean Granite. In the Cape Province it ranged from 29 per cent in the Grey Gneiss to 45 per cent in the Kheis System, except for the adamellite with 6 per cent and the Soetlief lava with 90 per cent successful boreholes. In both areas certain geological and physiographical controls were determined by means of which borehole results can be improved. Analyses of geophysical data, especially apparent resistivity at the rest level, sometimes gave positive results. Depths at which water was struck, rest levels, depth of weathering, and other parameters are compared for different formations and areas

Consensus report: E. coli O104:H4 (HUSEC041) and the potential threat to European water supplies.

Among the 3rd Seminar for PhD students working on Water and Health which was held in Cannes on 27–29 June 2011, experts from a number of universities and research institutes took the opportunity to discuss the emergence of Escherichia coli O104:H4 in Europe. Especially, possible threats for European water suppliers were considered. The consensus is summarized in this report. The main conclusion was that E. coli O104:H4 would not pose a substantial risk to well managed water supplies, especially where regular monitoring of indicator E. coli is negative. However, this may not apply for small and very small water systems which are quite common in Europe. New strategies like the Water Safety Plan approach are needed to protect also small scale drinking water systems and private wells in Europe. Water used in the processing of foods likely to be eaten raw, especially sprouts, should be of drinking water quality

Emergence of ferromagnetism and Jahn-Teller distortion in low Cr-substituted LaMnO3

The emergence of a ferromagnetic component in $LaMnO_{3}$ with low Cr-for-Mn substitution has been studied by x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Mn and Cr K edges. The local magnetic moment strength for the Mn and Cr are proportional to each other and follows the macroscopic magnetization. The net ferromagnetic components of $Cr^{3+}$ and $Mn^{3+}$ are found antiferromagnetically coupled. Unlike hole doping by La site substitution, the inclusion of $Cr^{3+}$ ions up to x = 0.15 does not decrease the Jahn-Teller (JT) distortion and consequently does not significantly affect the orbital ordering. This demonstrates that the emergence of the ferromagnetism is not related to JT weakening and likely arises from a complex orbital mixing.Comment: 5 figure

Collecting evidence on the use of parliamentary oversight tools : a South African case study

CITATION: Van Rensburg, W. J., Vrey, F. & Neethling, T. 2020. Collecting evidence on the use of parliamentary oversight tools : a South African case study. African Evaluation Journal, 8(1):a424, doi:10.4102/aej.v8i1.424.The original publication is available at https://aejonline.org/index.php/aej/Background: Parliament, through its oversight function, plays a central role in holding the executive to account. In South Africa’s 2014 Defence Review policy document, it was stated that the ‘Defence Force is in a critical state of decline’. This brings about the question whether the South African Parliament effectively held the executive to account regarding developments around defence. Objectives: The article aims to gather evidence on the use of oversight tools by the South African Parliament over a 20-year period, within the post-1994 democratic dispensation, in order to determine the broader trajectory of parliamentary defence oversight. Method: To determine the trajectory of oversight, this article gathered evidence on the use of internationally recognised parliamentary oversight tools by South Africa’s two parliamentary defence committees from 1994 to 2014. The period allows for a 20-year review of oversight of defence, inclusive of four full parliamentary terms. Evidence was collected on parliamentary debates, questions, special inquiries, oversight visits and the use of external audits as oversight tools. Results: The article found that tools were used with varying degrees of success. Results for research on each oversight tool is discussed. Conclusion: Based on evidence on the use of oversight tools, this article concludes that over a 20-year period there was a declining trajectory in parliamentary oversight of the defence portfolio. The proven applicability of the criteria utilised in this article can serve to inform evaluations of the effectiveness of parliamentary oversight, specifically at committee level.Publisher's versio

PINK1 regulated mitophagy is evident in skeletal muscles

PINK1, mutated in familial forms of Parkinson’s disease, initiates mitophagy following mitochondrial depolarization. However, it is difficult to monitor this pathway physiologically in mice as loss of PINK1 does not alter basal mitophagy levels in most tissues. To further characterize this pathway in vivo, we used mito-QC mice in which loss of PINK1 was combined with the mitochondrial-associated POLGD257A mutation. We focused on skeletal muscle as gene expression data indicates that this tissue has the highest PINK1 levels. We found that loss of PINK1 in oxidative hindlimb muscle significantly reduced mitophagy. Of interest, the presence of the POLGD257A mutation, while having a minor effect in most tissues, restored levels of muscle mitophagy caused by the loss of PINK1. Although our observations highlight that multiple mitophagy pathways operate within a single tissue, we identify skeletal muscle as a tissue of choice for the study of PINK1-dependant mitophagy under basal conditions

Heterogeneous Nuclear Ribonucleoprotein L is required for the survival and functional integrity of murine hematopoietic stem cells

The proliferation and survival of hematopoietic stem cells (HSCs) has to be strictly coordinated to ensure the timely production of all blood cells. Here we report that the splice factor and RNA binding protein hnRNP L (heterogeneous nuclear ribonucleoprotein L) is required for hematopoiesis, since its genetic ablation in mice reduces almost all blood cell lineages and causes premature death of the animals. In agreement with this, we observed that hnRNP L deficient HSCs lack both the ability to self-renew and foster hematopoietic differentiation in transplanted hosts. They also display mitochondrial dysfunction, elevated levels of γH2AX, are Annexin V positive and incorporate propidium iodide indicating that they undergo cell death. Lin-c-Kit+ fetal liver cells from hnRNP L deficient mice show high p53 protein levels and up-regulation of p53 target genes. In addition, cells lacking hnRNP L up-regulated the expression of the death receptors TrailR2 and CD95/Fas and show Caspase-3, Caspase-8 and Parp cleavage. Treatment with the pan-caspase inhibitor Z-VAD-fmk, but not the deletion of p53, restored cell survival in hnRNP L deficient cells. Our data suggest that hnRNP L is critical for the survival and functional integrity of HSCs by restricting the activation of caspase-dependent death receptor pathways

Lessons from a major pest invasion : the polyphagous shot hole borer in South Africa

CITATION: Paap, T. et al. 2020. Lessons from a major pest invasion : the polyphagous shot hole borer in South Africa. South African Journal of Science, 116(11/12):8757, doi:10.17159/sajs.2020/8757.The original publication is available at https://sajs.co.zaThe arrival and establishment of invasive forest pests can cause devastating environmental damage and great economic impact. For example, the cost over the past decade of dealing with the arrival of a single invasive beetle in the USA, the emerald ash borer (Agrilus planipennis), is estimated at more than USD10 billion.1 Originating from Asia, this beetle has killed hundreds of millions of native ash trees since it became established in the USA. However, this beetle is but one of hundreds of invasive insect pests that impact forests in the USA, and that contribute to a global tree health crisis caused by invasive insects and pathogenic microorganisms.2-4 South Africa is no different from other countries and is experiencing an increasing rate of introductions of damaging forest pests.5,6 These invasions are largely unintentional and are a by-product of globalisation and increasing global trade.7,8 The movement of living plants and plant products, including untreated wood packaging materials (i.e. pallets, dunnage and crating), is known to be a major pathway for these pests.9,10 For clarification, in this commentary we use the terms ‘insect’ and ‘pathogen’ to distinguish between the two types of organisms, although we also use the general term ‘pest’ to refer to both groups. The term ‘invasive pest’ is used for introduced species that, in addition to maintaining a self-sustaining population, show evidence of spread and impact.https://sajs.co.za/article/view/8757Publisher's versio

The break up of heavy electrons at a quantum critical point

The point at absolute zero where matter becomes unstable to new forms of order is called a quantum critical point (QCP). The quantum fluctuations between order and disorder that develop at this point induce profound transformations in the finite temperature electronic properties of the material. Magnetic fields are ideal for tuning a material as close as possible to a QCP, where the most intense effects of criticality can be studied. A previous study on theheavy-electron material $YbRh_2Si_2$ found that near a field-induced quantum critical point electrons move ever more slowly and scatter off one-another with ever increasing probability, as indicated by a divergence to infinity of the electron effective mass and cross-section. These studies could not shed light on whether these properties were an artifact of the applied field, or a more general feature of field-free QCPs. Here we report that when Germanium-doped $YbRh_2Si_2$ is tuned away from a chemically induced quantum critical point by magnetic fields there is a universal behavior in the temperature dependence of the specific heat and resistivity: the characteristic kinetic energy of electrons is directly proportional to the strength of the applied field. We infer that all ballistic motion of electrons vanishes at a QCP, forming a new class of conductor in which individual electrons decay into collective current carrying motions of the electron fluid.Comment: Pdf files of article available at http://www.physics.rutgers.edu/~coleman/online/breakup.pdf, pdf file of news and views article available at http://www.physics.rutgers.edu/~coleman/online/nvbreakup.pd

Intraspecific and within-isolate sequence variation in the ITS rRNA gene region of Pythium mercuriale sp. nov. (Pythiaceae)

Sixteen Pythium isolates from diverse hosts and locations, which showed similarities in their morphology and sequences of the internal transcribed spacer (ITS) region of their rRNA gene, were investigated. As opposed to the generally accepted view, within single isolates ITS sequence variations were consistently found mostly as part of a tract of identical bases (A-T) within ITS1, and of GT or GTTT repeats within the ITS2 sequence. Thirty-one different ITS sequences obtained from 39 cloned ITS products from the 16 isolates showed high sequence and length polymorphisms within and between isolates. However, in a phylogenetic analysis, they formed a cluster distinct from those of other Pythium species. Additional sequencing of two nuclear genes (elongation factor 1α and β-tubulin) and one mitochondrial gene (nadh1) revealed high levels of heterozygosity as well as polymorphism within and between isolates, with some isolates possessing two or more alleles for each of the nuclear genes. In contrast to the observed variation in the ITS and other gene areas, all isolates were phenotypically similar. Pythium mercuriale sp. nov. (Pythiaceae) is characterized by forming thin-walled chlamydospores, subglobose to obovoid, papillate sporangia proliferating internally and smooth-walled oogonia surrounded by multiple antheridia. Maximum likelihood phylogenetic analyses based on both ITS and β-tubulin sequence data place P. mercuriale in a clade between Pythium and Phytophthor