959 research outputs found

    A comparative assessment of the economic benefits from shale gas extraction in the Karoo, South Africa

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    It has been said that the development of a shale gas industry could be a ‘game changer’ for South Africa. Proponents of shale gas tend to emphasise the benefits, whilst opponents emphasise the environmental costs. This paper is an attempt to inform the policy debate by highlighting both the potential economic benefits and environmental costs. To date, the Econometrix report (published in 2012) provides the only estimate of the economic impacts that may emanate from developing the Karoo’s shale gas. The report uses a Keynesian multiplier model to estimate the impacts. The analysis performed in this paper estimates the economic impacts using a Computable General Equilibrium (CGE) modelling approach, and the results are compared to the findings of the Econometrix report. In doing so, this paper provides an expanded view of the potential economic impact. Accordingly, this paper provides a number of findings on the estimated economic impact of shale gas extraction – based on the application of an economy-wide impact modelling methodology – which should be of interest to both opponents and proponents of the shale gas industry. By including all possible results, such as a boost in public sector jobs and an analysis of the impact on consumer prices and jobs in other sectors, this paper expands the current understanding of the likely impact of shale gas extraction in the Karoo of South Africa.Key words: shale gas extraction, economy-wide modelling, CGE, exhaustible resources

    The Dependence of the Resistance of Silver Films upon the Method of Deposition

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    Most observers investigating the specific resistance in thin metallic films have found that it decreases rapidly with time. In the present investigation Brashear\u27s process of obtaining silver films was followed

    The Hall Effect and the Specific Resistance of Thin Silver Films

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    The Hall Effect of ordinary metals may be expressed by the equation E=HIa/e where E = the Hall Effect, I= the primary current, e= the thickness of the conductor and a= a constant whose value in silver lies between.00083 to.00090. In the present investigation the above equation was found to hold in thin silver films, and that has a value of.00084

    Tenascin-C fragments are endogenous inducers of cartilage matrix degradation

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    Cartilage destruction is a hallmark of osteoarthritis (OA) and is characterized by increased protease activity resulting in the degradation of critical extracellular matrix (ECM) proteins essential for maintaining cartilage integrity. Tenascin-C (TN-C) is an ECM glycoprotein, and its expression is upregulated in OA cartilage. We aimed to investigate the presence of TN-C fragments in arthritic cartilage and establish whether they promote cartilage degradation. Expression of TN-C and its fragments was evaluated in cartilage from subjects undergoing joint replacement surgery for OA and RA compared with normal subjects by western blotting. The localization of TN-C in arthritic cartilage was also established by immunohistochemistry. Recombinant TN-C fragments were then tested to evaluate which regions of TN-C are responsible for cartilage-degrading activity in an ex vivo cartilage explant assay measuring glycosaminoglycan (GAG) release, aggrecanase and matrix metalloproteinase (MMP) activity. We found that specific TN-C fragments are highly upregulated in arthritic cartilage. Recombinant TN-C fragments containing the same regions as those identified from OA cartilage mediate cartilage degradation by the induction of aggrecanase activity. TN-C fragments mapping to the EGF-L and FN type III domains 3-8 of TN-C had the highest levels of aggrecan-degrading ability that was not observed either with full-length TN-C or with other domains of TN-C. TN-C fragments represent a novel mechanism for cartilage degradation in arthritis and may present new therapeutic targets for the inhibition of cartilage degradation

    A Computational Channel Model for Magnetic Induction-Based Subsurface Applications

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    There are many underground applications based on magnetic fields generated by an oscillating magnetic source. For them, a magnetic dipole in a three-layered region with upper semi-infinite air layer can be a convenient idealization used for their planning, development, and operation. Solutions are in the form of the well-known Sommerfeld integral expressions that can be evaluated by numerical methods. A set of field expressions to be numerically evaluated by an efficient algorithm are not collected comprehensively yet, or at least in a directly usable form. In this paper, the explicit magnetic field solutions for the vertical magnetic dipole and the horizontal magnetic dipole for a general source-observer location are derived from the Hertz vector. They can be properly combined to model the problem of a tilted magnetic dipole source for horizontally or inclined stratified media. As a result, a complete set of integral equations of the Sommerfeld type valid from the near zone to the far zone are formulated. A method for numerical evaluation of the field expressions for high accurate computations is described. The numerical results are validated using the finite element method for all the possible source-receiver configurations and three well-spanned frequencies of typical subsurface applications. Both numerical solutions agree according to the normalized root-mean-square error-based fit metric. Numerical results for two cases of study are presented to see its usefulness for subsurface applications. A MATLAB implementation of the mathematical description outlined in this paper and the proposed evaluation method is freely available for download

    Identifying the Comparative Advantage of Products and Industries of South Africa’s Mpumalanga Province

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    Knowledge of a region’s comparative advantage may dictate its industrial development agenda and realistic export opportunities. Through the effective targeting of specific sectors and industries within the South African provinces, provincial government entities can determine which sector or industry could gain the most from effective targeting for industrial development, development planning and export promotion. This study determined the comparative advantage of South Africa’s Mpumalanga province by estimating the Revealed Comparative Advantage Index (RCA). The study revealed that the products with the highest comparative advantage (RCA) and realistic export opportunities (REO) are manganese products, salted meat (beef), frozen fish, chewing gum, tomatoes, soups and broths. In addition, the results of the RCA analysis were matched to the export opportunities identified by the decision support model (TRADE-DSM) to determine which of the comparative advantage products have realistic export opportunities. Eight of the top 15 comparative advantage products were found to have realistic export opportunities according to the TRADE-DSM.Keywords: Competitiveness, Decision Support Model (DSM), Export, Revealed Comparative Advantage (RCA), Mpumalanga Province, Trade, South Afric

    Changes in male rat urinary protein profile during puberty: a pilot study

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    BACKGROUND: Androgen-dependent proteins (lipocalins) circulate in blood of male rats and mice and, being small (~ 18 kDa), pass freely into glomerular filtrate. Some are salvaged in proximal nephrons but some escape in urine. Several organic molecules can bind to these proteins causing, where salvage occurs, nephropathy including malignancy in renal cortex. In urine, both free lipocalins and ligands contribute to an increasingly-recognised vital biological role in social communication between adults, especially in the dark where reliance is on smell and taste. Crystal structure of the first-characterised lipocalin of male rats, α2u-globulin, has been determined and peptide sequences for others are available, but no study of occurrence during early puberty has been made. We have followed temporal occurrence in urine of juveniles (n = 3) for non-invasive pilot study by high resolution gradient mini-gel electrophoresis, tryptic digest of excised protein bands, and LC-MS/MS of digest to identify peptide fragments and assign to specific lipocalins. Study objective refers directly to external availability for social communication but also indirectly to indicate kinetics of circulating lipocalins to which some xenobiotics may bind and constitute determinants of renal disease. RESULTS: Mini-gels revealed greater lipocalin complexity than hitherto recognised, possibly reflecting post-translational modifications. Earliest patterns comprised rat urinary protein 1, already evident in Sprague-Dawley and Wistar strains at 36 and 52 days, respectively. By 44 and 57 days major rat protein (α2u-globulin) occurred as the progressively more dominant protein, though as two forms with different electrophoretic mobility, characterised by seven peptide sequences. No significant change in urinary testosterone had occurred in Wistars when major rat protein became evident, but testosterone surged by 107 days concomitant with the marked abundance of excreted lipocalins. CONCLUSIONS: Qualitative temporal changes in the composition of excreted lipocalins early in puberty, and apparent increase in major urinary protein as two resolvable forms, should catalyse systematic non-invasive study of urinary lipocalin and testosterone dynamics from early age, to illuminate this aspect of laboratory rodent social physiology. It could also define the potential temporal onset of nephrotoxic ligand risk, applicable to young animals used as toxicological models
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