2,528 research outputs found

    Cable Theft and Vandalism by Employees of South Africa’s Electricity Utility Companies: A Theoretical Explanation and Research Agenda

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    Published ArticleIn this paper, the researchers argue that unravelling perceptions and attitudes of relevant employees towards theft and vandalism is critical to stemming electric cable theft. The researchers draw on the Reasoned Action Theory (TRA) and the Theory of Planned Behaviour (TPB) to explain the involvement of electricity utility companies’ own employees in vandalism and theft of electricity copper cables.Drawing on a theoretical research approach involving the examination of mainstream literature, the paper explores the reasons for employees’ engagement in actions that contradict company policy, namely stealing from the employer or vandalizing organisational property. The findings suggests that personal traits (employee perceptions and attitudes), organizational factors (such as organizational climate) constitute presage factors that trigger psychological dispositions to rob the company of its material assets (copper cables) in general and ultimately steal and vandalise copper cables in particular

    Emergency Medical Care and Podiatry

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    Exam paper for first semester (Department of Applied Physics and Engineering Mathematics, B. Tech

    Political discourses on race and social inequalities through social media and live parliamentary debates in South Africa : a content analysis

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    Abstract: This article, informed by framing theory, uses qualitative content analysis to analyse the Economic Freedom Fighters' (EFF) discourses on race and social inequalities through social media and live parliamentary debates in South Africa. The article reveals that protest and provocative political statements by EFF members attract audience and media attention, and reinforce their political agenda. Political personalities communicate their message effectively on social media and influence audiences' perception through protestation. The well-known framing theory by the traditional mass media has been exceeded by that of social media where politicians radically engage their audiences. This paper reveals that the populist political style has much impact on social media, where political actors interact directly with audiences

    Possible modulation of dopaminergic neurotransmission function by acetyl-L-carnitine

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    Acetyl‐L‐Carnitine (ALC) has a putative neuroprotective effect being used in a variety of conditions. Nevertheless, the underlying molecular mechanisms, particularly regarding the induction of changes in neurotransmitter systems, are still not fully understood. We aim to contribute for the elucidation of the mechanisms by which ALC alters neurotransmitter release, using a cell line and an animal model of exposure to methamphetamine (METH). PC12 cells were incubated with several doses of ALC (0.01 to 1.0 mM) alone or in combination with METH 1.0 or 100 µM for 24h or 72h. When combined, ALC preceded METH administration in 30 minutes. Dopamine (DA) content was determined by high performance liquid chromatography. C57BL/6J mice were used for in vivo assays to assess DA striatal binding. Mice were divided into 4 groups, according to different treatments: group 1 (control), group 2 (ALC, 100 mg/kg), group 3 (METH, 10 mg/kg) and group 4 (ALC+METH). Images were acquired in a SPECT/CT scanner (NanoSPECT/CT, Mediso, Hungary) 70 minutes after 123I‐IBZM injection. Regions of interest were drawn in the striata and in the cerebellum to determine the striatal binding ratio. Increased intracellular levels of DA were observed in PC12 cells at 24h and 72h after the administration of ALC. Cells treated with METH 100 µM displayed decreased intracellular levels of DA. ALC prevented the METH‐induced decrease in DA concentration (p<0.0001). On the other hand, a single dose of 10 mg/kg of METH induced a decrease in striatal D2R binding ratios comparing to control group (between 20% and 30%). Interestingly, over time, ALC was able to reverse the decrease on the radiotracer binding induced by METH. The present study indicates a possible effect of ALC over METH‐induced DA release.info:eu-repo/semantics/publishedVersio

    Metallogenetic evolution of the Canadian Cordilleran Orogen

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    From Introduction: The Canadian Cordilleran Orogenic Belt forms part of the circum-Pacific orogenic zone. It underlies an area of about 1,54 million sq. kilometres, is over 2400 kilometres long and 800 kilometres wide. The region is characteristically mountainous, much of it glaciated and alpine, containing plateaux, trenches, valleys, and fjords. The mountains, in general, rise to elevations between 2100 m and 3600 m above sea level, although Mount Logan in the St. Elias Mountains attains an altitude of 6000 m. The Canadian Cordillera is divided into two dominant orogenic belts: the eastern Columbian Orogenic Belt comprising defonned miogeosynclinal rocks and the western Pacific Orogenic Belt comprising allochthonous eugeosynclinal rocks. The Cordillera is further subdivided into five longitudinal tectonic belts within which rocks are broadly similar in type, age, and history. These belts are, from east to west: the Rocky Mountain Belt, the Omineca Crystalline Belt, the Intermontane Belt, the Coast Plutonic Complex, and the Insular Belt (Wheeler et al., 1972a). The Canadian Cordillera is important in that it contains: one of the world's largest lead-zinc-silver mine, Sullivan; the second-largest molybdenum mine, Endako; one of the most important concentrations of porphyry copper deposits, Highland Valley; Canada's largest tungsten mines, Cantung and Mactung; and Canada's second-largest silver district, Keno Hill (Sutherland Brown et a1., 1971). In addition, it contains several large massive sulphide and lead-zinc deposits

    A capacitor voltage balancing approach based on mapping strategy for MMC applications

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    This paper proposes a new strategy to achieve balanced capacitor voltages in modular multilevel converters. Among the possible solutions, centralized arm control approaches are often adopted. These methods require a balancing technique based on a sorted list of the sub-modules according to their capacitor voltages. In order to achieve the aforementioned sorted list, different algorithms have been proposed in literature, such as: Sorting algorithms, max/min approaches, etc. However, the sorting algorithms require a long execution time, while the max/min approaches affect the converter dynamic response during faults. To overcome these issues, a new mapping strategy providing a quasi-sorted list is proposed in this paper. The suggested method is compared in simulation with both the classical bubble sorting algorithm, and the max/min method during both normal and faulty conditions. Moreover, the three methods have been implemented in a Xilinx Zynq-7000 System-on-Chip (SoC) device, in order to analyze the corresponding execution time and the required computational effort. Hardware-in-the-loop results are presented for demonstrating the superior performance of the proposed balancing strategy

    Dispatchable High-Power Wind Turbine Based on a Multilevel Converter with Modular Structure and Hybrid Energy Storage Integration

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    This paper presents a new multilevel converter solution with modular structure and hybrid energy-storage integration suitable to drive modern/future high-power medium-voltage wind turbines. The hybrid energy-storage integration means that part of the converter submodules are built with batteries and part of them with conventional capacitors. Since traditional wind turbines are non-dispatchable generators, the integration of an energy storage system could be beneficial in multiple ways as the wind power plant could provide stability support to the grid, improvement of the unit commitment and economic dispatch, and the power plant owner could increase his revenues in the electricity market. The capacitors of the proposed converter are responsible to transfer the power produced by the wind turbine to the grid, and the batteries are only charged/discharged with the mismatch between the power produced by the turbine and the power to be injected into the grid, considering a dispatchable operation where the power injected into the grid is different from the power generated by the turbine. The medium-voltage structure could be an interesting option to overcome problems related to high currents in modern/future high-power wind turbines resulting in more efficient, more compact and lighter solutions. Modular multilevel converters are suitable to handle medium-voltage levels and they allow for a straightforward integration of energy storage systems in a decentralized manner

    Fast DNA translocation through a solid-state nanopore

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    We report translocation experiments on double-strand DNA through a silicon oxide nanopore. Samples containing DNA fragments with seven different lengths between 2000 to 96000 basepairs have been electrophoretically driven through a 10 nm pore. We find a power-law scaling of the translocation time versus length, with an exponent of 1.26 Âą\pm 0.07. This behavior is qualitatively different from the linear behavior observed in similar experiments performed with protein pores. We address the observed nonlinear scaling in a theoretical model that describes experiments where hydrodynamic drag on the section of the polymer outside the pore is the dominant force counteracting the driving. We show that this is the case in our experiments and derive a power-law scaling with an exponent of 1.18, in excellent agreement with our data.Comment: 5 pages, 2 figures. Submitted to PR

    Engineering tyrosine residues into hemoglobin enhances heme reduction, decreases oxidative stress and increases vascular retention of a hemoglobin based blood substitute

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    Hemoglobin (Hb)-based oxygen carriers (HBOC) are modified extracellular proteins, designed to replace or augment the oxygen-carrying capacity of erythrocytes. However, clinical results have generally been disappointing due to adverse side effects, in part linked to the intrinsic oxidative toxicity of Hb. Previously a redox-active tyrosine residue was engineered into the Hb β subunit (βF41Y) to facilitate electron transfer between endogenous antioxidants such as ascorbate and the oxidative ferryl heme species, converting the highly oxidizing ferryl species into the less reactive ferric (met) form. We inserted different single tyrosine mutations into the ι and β subunits of Hb to determine if this effect of βF41Y was unique. Every mutation that was inserted within electron transfer range of the protein surface and the heme increased the rate of ferryl reduction. However, surprisingly, three of the mutations (βT84Y, ιL91Y and βF85Y) also increased the rate of ascorbate reduction of ferric(met) Hb to ferrous(oxy) Hb. The rate enhancement was most evident at ascorbate concentrations equivalent to that found in plasma (< 100 ΟM), suggesting that it might be of benefit in decreasing oxidative stress in vivo. The most promising mutant (βT84Y) was stable with no increase in autoxidation or heme loss. A decrease in membrane damage following Hb addition to HEK cells correlated with the ability of βT84Y to maintain the protein in its oxygenated form. When PEGylated and injected into mice, βT84Y was shown to have an increased vascular half time compared to wild type PEGylated Hb. βT84Y represents a new class of mutations with the ability to enhance reduction of both ferryl and ferric Hb, and thus has potential to decrease adverse side effects as one component of a final HBOC product
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