NONLINEAR PROOF-OF-WORK: IMPROVING THE ENERGY EFFICIENCY OF BITCOIN MINING

Bitcoin is probably the most well-known blockchain system in existence. It employs the proof-of-work (PoW) consensus algorithm to add transactions to the blockchain. This process is better known as Bitcoin mining. PoW requires miners to compete in solving a cryptographic puzzle before being allowed to add a block of transactions to the blockchain. This mining process is energy-intensive and results in high energy wastage. The underlying cause of this energy inefficiency is the result of the current implementation of the PoW algorithm. PoW assigns the same cryptographic puzzle to all miners, creating a linear probability of success between the miner’s computational power as a proportion of the total computational power of the network. To address this energy inefficiency of the PoW mining process, the researchers investigated whether a nonlinear probability of success, between the miner’s computation power and its probability of success, will result in better energy usage. A nonlinear proof-of-work (nlPoW) algorithm was constructed by using a design science approach to derive the requirements for and structure of the algorithm. The Bitcoin mining process was tested through statistical simulation, comparing the performance of nlPoW with PoW. Preliminary results, simulating a network of 1000 miners with identical computational power, indicate that nlPoW reduce the number of hash computations, and therefore the energy consumption, required by Bitcoin mining. The findings are significant because nlPoW does not reduce the degree of decentralised consensus, or trade energy usage for some other resource as is the case with many other attempts to address the energy consumption problem in PoW

Hypercoagulation and the structural properties of plasma proteins in rheumatoid arthritis

Thesis (PhD)--Stellenbosch University, 2022.ENGLISH ABSTRACT: Rheumatoid Arthritis (RA) is the most common chronic inflammatory joint disease globally and typically affects smaller synovial joints. The exact pathogenic cause of RA is yet to be fully determined, with the current paradigm viewing aetiology as a complex interaction between various genetic, environmental and immunological factors. The generation of self-antigens and a subsequent break in immune tolerance causes a systemic autoimmune response that affects tissues and organs other than synovial joints, including the cardiovascular system. Individuals suffering from RA have an excessive risk for early development of numerous cardiovascular diseases (CVD), such as venous and arterial thrombosis. Increased CVD morbidity and mortality risk in RA is exacerbated by heightened arthritis severity, which indicates that immunopathological mechanisms could affect cellular and soluble components responsible for regulating blood flow and perfusion. Upstream from inflammation-induced haemostatic dysregulation, posttranslational modifications of endogenous proteins that generates autoantigenicity in RA is known to target prominent clotting factors such as fibrinogen and fibrin. The extent and effect of these alterations on the normal function and structure of fibrin(ogen) within the context of coagulation has to date not been extensively considered. This study therefore aimed to identify and characterise the mechanistic and structural abnormalities of blood clot formation in RA patients. Peripheral blood samples were collected from individuals with active RA disease alongside age- and gender-matched healthy individuals that served as experimental controls. Functional and structural analysis was conducted of whole blood and fibrin clots formed from RA and control samples and compared. Clot structures were further examined to determine the possible impact of autoimmune-related citrullination and alterations of the protein secondary structure. Increased expression levels of C-reactive protein, serum amyloid A and intercellular adhesion molecule 1 measured by immunoassay was confirmed in RA patients, indicating a state of acute systemic inflammation and endothelial dysregulation. Initiation and propagation of clot formation as measured by thromboelastography occurred at a more rapid rate in RA whole blood samples compared to controls. However, maximal measured strength of formed thrombi was attenuated in RA. This observation was consistent with decreased platelet activity levels (P-selectin ELISA), alongside abnormal fibrin clot properties observed using electron microscopy, where RA clots consisted of dense fibrin fibre networks with increased fibre diameter. The identification of citrullination as a possible cause of altered fibrin clot properties in RA was accomplished by using immunofluorescence microscopy. Finally, the abrogation of fibrin clot viscoelasticity was reflected in additional microscopical and spectrochemical analysis of protein secondary structure, in which increased β-sheet generation during clot formation but similar relative β-sheet composition to that of healthy controls was indicated. These findings strongly suggests that immunopathological mechanisms intrinsic to RA may cause a thrombotic complication in which elevated fibrin deposition is offset by structural alterations that compromise clot stability and could therefore increase the risk of rupture under the influence of flow shear forces. This potential cause of thromboembolism is of important clinical relevance, and further mechanistic insights are necessary in order to identify and possibly mitigate this serious risk in the RA population.AFRIKAANSE OPSOMMING: Rumatoïede artritis (RA) is the mees algemene chroniese inflammatoriese gewrig siekte wêreldwyd en affekteer gewoonlik kleiner sinoviale gewrigte. The presiese patogeniese oorsaak van RA is tot hede nog nie ten volle bepaal nie, met die huidige etologiese siening as ‘n komplekse interaksie tussen verskeie genetiese, omgewings en immunologiese faktore. Die generering van self-antigene en ‘n daaropvolgende breek in immuun toleransie veroorsaak ‘n sistemiese outo-immuunreaksie wat weefsel en organe anders as die van sinoviale gewrigte affekteer, wat die kardiovaskulêre sisteem insluit. Individue wat ly aan RA het ‘n oortollige risiko vir vroeë ontwikkeling vand verskeie kardiovaskulêre siektes, soos veneus en arteriale trombose. Verhoogde kardiovaskulêre morbiditeit en mortaliteit in RA word vererger deur akute artritis simptome, wat aandui dat immuno-patologiese meganismes moontlik sellulêre en oplosbare komponente verantwoordelik vir die regulasie van bloedvloei en perfusie affekteer. Voorafgaande van hemostatiese wanregulasie veroorsaak deur inflammasie, is post- translasionele veranderinge van endogene proteïene wat outo-antigenisiteit in RA genereer bekend om prominente stollings faktore soos fibrinogeen en fibrien te teiken. Die omvang en effek van hierdie veranderinge op die normale funksie en struktuur van fibrinogeen en fibrien binne die konteks van koagulasie tot hede nog nie breedvoerig oorweeg nie. Hierdie studies het dus gepoog om die meganistiese end strukturele abnormaliteite van bloedstolling in RA pasiënte te indentifiseer en te karakteriseer. Perifere bloed monsters is versamel van individue met aktiewe RA tesame met ouderdom- en geslagsooreenstemende gesonde individue wat as eksperimentele kontroles gedien het. Funksionele en strukturele analises was uitgevoer op heelbloed en fibrienklonte gevorm van RA en kontrole monsters, en met mekaar vergelyk. Klontstrukture is verder bestudeer om die moontlike impak van outo-immuun verwante sitrullinasie te bepaal, tesame met veranderinge in die proteïen sekondêre struktuur. Verhoogde vlakke van C-reaktiewe proteïen, serum ameloïed A, en intersellulêre adhesie molekule 1 gemeet deur immuuntoetsing is bevestig in RA pasiënte, wat ‘n toestand van akute sistemiese inflammasie en endoteel disregulasie aandui. Die begin en aanvoering van bloedstolling gemeet deur tromboelastografie het geskied teen ‘n versnelde tempo in RA heelbloed in vergelyking met kontroles. The maksimum bepaalde vlak van trek sterkte in gevormde klonte was egter verswak in RA. Hierdie waarneming was konsekwent met verlaagde plaatjie aktiwiteit (P-selektien ELISA) tesame met abnormale fibrienklont eienskappe waargeneem met elektron mikroskopie, waar RA klonte saamgestel is deur digte fibrien netwerke met verhoogde vesel deursnee. Die wegdoening van fibrien klont viskoelastisiteit was gereflekteer in addisionele mikroskopiese en spektrochemiese analise van proteïen sekondêre struktuur, waarin verhoogde β-blad generering gedurende stolling plaasvind maar relatiewe gelyke saamstelling van β-blad inhoud bestaan met die van gesonde individue. Hierdie resultate dui baie sterk aan dat immunopatologiese meganismes intrinsiek tot RA trombotiese komplikasies mag veroorsaak. Verhoogde fibrien neerslag mag deur strukturele veranderinge teengewerk word en dus ‘n kompromie inhou vir klot stabiliteit en die risiko verhoog vir die los skeur van klonte onder invloed van vloei-skeer kragte. Die moontlike oorsaak van tromboembolisme is van uiterse belangrike kliniese belang, en verdere meganistiese insigte word benodig om sodoende hierdie ernstige risiko in die RA populasie te identifiseer en te versag.Doctora

Between market, state and society : labour codes of conduct in the southern African garment industry

This paper compares the way garment factory workers in South Africa, Swaziland and Lesotho experience the interaction between mechanisms for inspecting labour codes of conduct and government functions and trade unions. In South Africa and Swaziland there was little awareness of the potential impact of such instruments on working conditions. In Lesotho, where there is a high profile campaign, workers are more aware of the codes, but confusion over who visitors to factories are, and corporate whitewash, limit the impact of instruments. In all three countries workers perceived the impact of codes of conduct on labour rights as negligible. This differed between firms, with workers in firms supplying to the higher end of the South African market being more positive. Given the absence of coherent global governance of trade in the garment industry, codes of conduct will remain an inadequate response to the abuse of workers’ rights, worldwide and in southern Africa.http://www.tandfonline.com/loi/cdsa20gv201

Enclave Rustenburg : platinum mining and the post-apartheid social order

In the absence of a levelling out of income and resources, as well as arbitrary violence in everyday life, the post-apartheid social order is characterised by the formation of various enclaves. In the platinum mining town of Rustenburg, these enclaves are constructed on the foundations of the apartheid categories ‘suburb’, ‘compound’, ‘township’ and ‘homeland’. Such enclaves include security villages, converted compounds with access control, and informal settlements with distinctive gender, linguistic and class formations. The article draws on David Harvey’s formulation of absolute, relative and relational space and the case of Rustenburg to elaborate the concept of enclave further.[L’enclave Rustenburg : la mine de platine et l’ordre social post-apartheid.] En l’absence d’un nivellement des revenus et ressources, en plus d’une violence arbitraire dans la vie de tous les jours, l’ordre social post-apartheid est caracte´rise´ par la formation de diffe´rentes enclaves. Dans la ville des mines de platine de Rustenburg, ces enclaves sont construites sur les fondations des cate´gories de l’apartheid « suburb » (ou banlieue), « compound » (habitations dans un enclos), « township » (bidonville) et « homeland » (bantoustans ou foyers nationaux). Ces enclaves comprennent des villages se´curise´s, des compounds convertis avec un controˆle d’acce`s, et des implantations informelles avec des formations distinctives de genre, de langue et de classe. L’article se base sur la formulation de David Harvey de l’espace absolu, relatif et relationnel et sur le cas de Rustenburg pour de´tailler davantage le concept de l’enclave.http://tandfonline.com/loi/crea202016-12-31hb2016Sociolog

The Garment Industry in its Economic, Political and Social Context

This special CBDS Working Paper originates from a longer-term collaboration between Associate Professors Søren Jeppesen, CBS and Andries Bezuidenhout, UFH. The collaboration started more than 10 years ago and will have its main output with the forthcoming book (preliminarily) titled, ‘Enclave Development: State, Market, And Society in Lesotho, South Africa and Swaziland’s Garment Manufacturing Industries’. The collaboration has benefitted from primary and secondary data from two research projects and support from our institutions. The first project was part of a large research project, titled ‘The Outsourcing for Development project’, based at CBS and Aalborg University, Denmark. The project was funded by the Danish Development Research Council and investigated different aspects of the contemporary situation among firms from developing countries in an era of globalisation and outsourcing of production from North to South. As part of a sub-study on ‘CSR, Development and Outsourcing’ we undertook a comparative investigation of the impact of codes of conduct on working conditions in garment factories in different countries in Southern Africa. The second project was part of a large comparative study on the role of Labour movements in Southern Africa, anchored at the Sociology at Work Unit, Witwatersrand University, South Africa. The project also supported the comparative study of the impact on codes of conduct, with funding from the Norwegian Development Agency (Norad). Over the years, our respective institutions (Department of Intercultural Communication and Management, later renamed Department of Management, Society and Communication (MSC) at CBS and Sociology of Work, Wits University, Department of Sociology, University of Pretoria and lastly Department of Development Studies (DDS), University of Fort Hare (UFH)) have supported us collegially and with funds for travel, student assistance and more. We highly appreciate this. During the project, we have benefitted from the work of numerous student and research assistants. They include; Lasse B. Jensen, Alvin P. Ljosa, Sameer Azizi, Amanda Haarmaan, and Zartashia Ahmed (CBS), and Hamadziripi Tamukamoyo, Wits University (and other SA assistants). We would like to thank all for the great help

Erythrocyte, Platelet, Serum Ferritin, and P-Selectin Pathophysiology Implicated in Severe Hypercoagulation and Vascular Complications in COVID-19

CITATION: Venter, C. et al. 2020. Erythrocyte, Platelet, Serum Ferritin, and P-Selectin Pathophysiology Implicated in Severe Hypercoagulation and Vascular Complications in COVID-19. International Journal of Molecular Sciences, 21(21). doi:10.3390/ijms21218234The original publication is available at https://www.mdpi.com/journal/ijmsProgressive respiratory failure is seen as a major cause of death in severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2)-induced infection. Relatively little is known about the associated morphologic and molecular changes in the circulation of these patients. In particular, platelet and erythrocyte pathology might result in severe vascular issues, and the manifestations may include thrombotic complications. These thrombotic pathologies may be both extrapulmonary and intrapulmonary and may be central to respiratory failure. Previously, we reported the presence of amyloid microclots in the circulation of patients with coronavirus disease 2019 (COVID-19). Here, we investigate the presence of related circulating biomarkers, including C-reactive protein (CRP), serum ferritin, and P-selectin. These biomarkers are well-known to interact with, and cause pathology to, platelets and erythrocytes. We also study the structure of platelets and erythrocytes using fluorescence microscopy (using the markers PAC-1 and CD62PE) and scanning electron microscopy. Thromboelastography and viscometry were also used to study coagulation parameters and plasma viscosity. We conclude that structural pathologies found in platelets and erythrocytes, together with spontaneously formed amyloid microclots, may be central to vascular changes observed during COVID-19 progression, including thrombotic microangiopathy, diffuse intravascular coagulation, and large-vessel thrombosis, as well as ground-glass opacities in the lungs. Consequently, this clinical snapshot of COVID-19 strongly suggests that it is also a true vascular disease and considering it as such should form an essential part of a clinical treatment regime.https://www.mdpi.com/1422-0067/21/21/8234Publishers versio

Between market, state and society: Labour codes of conduct in the southern African garment industry

This paper compares the way garment factory workers in South Africa, Swaziland and Lesotho experience the interaction between mechanisms for inspecting labour codes of conduct and government functions and trade unions. In South Africa and Swaziland there was little awareness of the potential impact of such instruments on working conditions. In Lesotho, where there is a high profile campaign, workers are more aware of the codes, but confusion over who visitors to factories are, and corporate whitewash, limit the impact of instruments. In all three countries workers perceived the impact of codes of conduct on labour rights as negligible. This differed between firms, with workers in firms supplying to the higher end of the South African market being more positive. Given the absence of coherent global governance of trade in the garment industry, codes of conduct will remain an inadequate response to the abuse of workers’ rights, worldwide and in southern Africa.http://www.tandfonline.com/loi/cdsa20gv201

Post-colonial workplace regimes in the engineering industry in South Africa, Swaziland and Zimbabwe

This paper considers the nature of workplace regimes that are constructed on the ruins what has become known as the 'apartheid workplace regime' by analysing a sub-sector of the engineering industry as a case study. In the context of the breakdown of the racial division of labour in the workplace, wage and job colour bars still operate informally. With the racial structure of power in the workplace no longer supported by the state, the language of 'flexibility' and 'globalisation' reinforce the arbitrary exercise of power over a layer of contract workers. Migrant labour remains as a key characteristic of the labour market in Southern Africa as such, and this is reinforced by the segmentation of the labour market into 'permanent' and 'contract' employees. While the segregation of facilities according to 'race' is no longer sanctioned by the state, workers experience segregation along company lines of hierarchy as 'racial'. The location of the industry in the industrial geography of apartheid is replicated in the context of Southern Africa, specifically because of the state formation of Swaziland, and the resemblance this has to the former Bantustans under apartheid. The concept 'post-colonial workplace regime' is developed in order to describe and understand these transitions