Showing papers by "University of Johannesburg published in 2021"

Moths–Flame Optimization Algorithm

Abstract: Moth–flame optimization (MFO) algorithm is a simple and easy to implement, nature-inspired, meta-heuristic algorithm. This chapter covers the introduction to moth flame optimization algorithm, steps for generating moths randomly within the neighbourhood or solution space and solved numerical example are provided. The fitness value for each moth is calculated and the best position obtained is tagged by flame. The updating process takes place after which the process is repeated until a point where criteria for termination is attained. The MFO model was implemented in MATLAB, to illustrate the approach, 30 search agents were considered (n = 30) and the maximum number of iterations were set to 100. The best solution obtained by MFO [1.7999 0.19996] and the best optimal value of the objective function found by MFO is 84. MFO algorithm can be used in diverse areas of operation for scheduling, estimation, simulation, and control.

Natural resource, globalization, urbanization, human capital, and environmental degradation in Latin American and Caribbean countries.

Abstract: The world is increasingly getting urbanized and globalized, and the increase in natural resource exploration could have a far-reaching impact on environmental quality. Since most Latin American and Caribbean countries (LACCs) have proximity to the Amazon, they, therefore, rely heavily on agriculture and mining which develop via deforestation which could exacerbate the already increasing carbon dioxide emissions (CO2 emissions). Therefore, to the best of our knowledge, this study becomes the first to investigate the link between natural resources, globalization, urbanization, and environmental degradation in LACCs countries from 1990 to 2017 with advanced panel data econometric techniques. The unit root tests affirm all the variables to be stationary at first difference, and the Westerlund (Oxf Bull Econ Stat 69(6):709–748, 2007) cointegration test confirms the long-run relationship among the variables. The augmented mean group (AMG) and the common correlated effects mean group (CCEMG) results affirm that the aforementioned variables add to CO2 emissions, while human capital mitigates it. Further findings reveal that human capital performs a moderating role in promoting urbanization sustainability. The country-specific results confirm that economic growth adds to emissions in all the countries, except in the Dominican Republic. A feedback causality exists between economic growth, globalization, urbanization, and CO2 emissions. This study argues for the development of human capital, a gradual transition to sustainable growth-driven and knowledge-based industries, and the introduction of sustainability practices in the natural resource sector to mitigate CO2 emissions in LACCs.

The EDS1–PAD4–ADR1 node mediates Arabidopsis pattern-triggered immunity

Abstract: Plants deploy cell-surface and intracellular leucine rich-repeat domain (LRR) immune receptors to detect pathogens1. LRR receptor kinases and LRR receptor proteins at the plasma membrane recognize microorganism-derived molecules to elicit pattern-triggered immunity (PTI), whereas nucleotide-binding LRR proteins detect microbial effectors inside cells to confer effector-triggered immunity (ETI). Although PTI and ETI are initiated in different host cell compartments, they rely on the transcriptional activation of similar sets of genes2, suggesting pathway convergence upstream of nuclear events. Here we report that PTI triggered by the Arabidopsis LRR receptor protein RLP23 requires signalling-competent dimers of the lipase-like proteins EDS1 and PAD4, and of ADR1 family helper nucleotide-binding LRRs, which are all components of ETI. The cell-surface LRR receptor kinase SOBIR1 links RLP23 with EDS1, PAD4 and ADR1 proteins, suggesting the formation of supramolecular complexes containing PTI receptors and transducers at the inner side of the plasma membrane. We detected similar evolutionary patterns in LRR receptor protein and nucleotide-binding LRR genes across Arabidopsis accessions; overall higher levels of variation in LRR receptor proteins than in LRR receptor kinases are consistent with distinct roles of these two receptor families in plant immunity. We propose that the EDS1–PAD4–ADR1 node is a convergence point for defence signalling cascades, activated by both surface-resident and intracellular LRR receptors, in conferring pathogen immunity. The authors provide mechanistic insights into the crosstalk between signalling components of pattern-triggered immunity and effector-triggered immunity and their molecular linkers.

Industry 4.0 deployment in the construction industry: a bibliometric literature review and UK-based case study

Abstract: Purpose: Industry 4.0 is predicted to be a game-changer, revolutionizing commercial and manufacturing practices through improved knowledge utilization and efficiencies. The barriers however, are significant, and the construction industry remains notoriously slow to take up innovations. This study reviews the research work in Industry 4.0 as it relates to construction, and examines a leading UK-based construction firm to ascertain the prognosis for Industry 4.0 roll-out in terms of the impediments and opportunities. Methodology: A multistage mixed philosophies and methods approach was adopted for this study. First, an interpretivist epistemological lens was used to synthesise extant literature as a means of contextualising the present study. Second, an empirical case study using a post-positivist stance and inductive reasoning was conducted to explore practitioner acceptance of Industry 4.0 in the UK construction context. Findings: Findings from the literature review indicate studies in Industry 4.0 to be a relatively new phenomenon, with developed countries and Germany in particular leading in the field. The range of opportunities are many, but so too are the barriers to enablement. Findings from the case study provide real-world corroboration of the review; practitioners are sanguine about Industry 4.0’s potential to reinvigorate the construction industry, but also note that implementation remains curtailed by residual managerial practices dependent on ‘human interaction.’ At present, much of the focus of industry practitioners is on the implementation of Building Information Modelling (BIM), often at the expense of other more advanced technologies within Industry 4.0. Originality: Research in Industry 4.0 is limited, with the emphasis being on technology application. This paper, by contrast, maps the totality of work carried out so far and presents an assessment of Industry 4.0’s progression, potential and degree of uptake within the UK construction industry.

Residents’ perceived risk, emotional solidarity, and support for tourism amidst the COVID-19 pandemic

Abstract: Due to the spread of COVID-19 and restrictions on international travel, popular destinations around the world have experienced an influx of domestic tourists. Regardless of the economic benefits that tourists could bring, residents have expressed their concerns about the health risks that would accompany tourists. Residents are not risk-proof or risk-tolerant, but the literature to date has overlooked the relevance and importance of residents' perceived risk associated with tourists. Addressing this research gap, this study investigated how residents’ perceived risk, emotional solidarity, and support for tourism were interrelated amid the pandemic. It was found that perceived risk was negatively associated with emotional solidarity and support for tourism, and emotional solidarity had a positive impact on support for tourism. Also, emotional solidarity was a partial mediator between perceived risk and support for tourism. Theoretical and practical implications of the findings are discussed within the closing of the article.

Jet energy scale and resolution measured in proton-proton collisions at s =13 TeV with the ATLAS detector

Abstract: Jet energy scale and resolution measurements with their associated uncertainties are reported for jets using 36-81 fb$^{-1}$ of proton-proton collision data with a centre-of-mass energy of $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC. Jets are reconstructed using two different input types: topo-clusters formed from energy deposits in calorimeter cells, as well as an algorithmic combination of charged-particle tracks with those topo-clusters, referred to as the ATLAS particle-flow reconstruction method. The anti-$k_t$ jet algorithm with radius parameter $R=0.4$ is the primary jet definition used for both jet types. Jets are initially calibrated using a sequence of simulation-based corrections. Next, several $\textit{in situ}$ techniques are employed to correct for differences between data and simulation and to measure the resolution of jets. The systematic uncertainties in the jet energy scale for central jets ($|\eta| 2.5$ TeV). The relative jet energy resolution is measured and ranges from ($24 \pm 1.5$)% at 20 GeV to ($6 \pm 0.5$)% at 300 GeV.

Carbon Nanotubes: Smart Drug/Gene Delivery Carriers

Abstract: The unique properties of carbon nanotubes (CNTs) (such as their high surface to volume ratios, enhanced conductivity and strength, biocompatibility, ease of functionalization, optical properties, etc.) have led to their consideration to serve as novel drug and gene delivery carriers. CNTs are effectively taken up by many different cell types through several mechanisms. CNTs have acted as carriers of anticancer molecules (including docetaxel (DTX), doxorubicin (DOX), methotrexate (MTX), paclitaxel (PTX), and gemcitabine (GEM)), anti-inflammatory drugs, osteogenic dexamethasone (DEX) steroids, etc. In addition, the unique optical properties of CNTs have led to their use in a number of platforms for improved photo-therapy. Further, the easy surface functionalization of CNTs has prompted their use to deliver different genes, such as plasmid DNA (PDNA), micro-RNA (miRNA), and small interfering RNA (siRNA) as gene delivery vectors for various diseases such as cancers. However, despite all of these promises, the most important continuous concerns raised by scientists reside in CNT nanotoxicology and the environmental effects of CNTs, mostly because of their non-biodegradable state. Despite a lack of widespread FDA approval, CNTs have been studied for decades and plenty of in vivo and in vitro reports have been published, which are reviewed here. Lastly, this review covers the future research necessary for the field of CNT medicine to grow even further.

A systematic global stocktake of evidence on human adaptation to climate change

Abstract: Assessing global progress on human adaptation to climate change is an urgent priority. Although the literature on adaptation to climate change is rapidly expanding, little is known about the actual extent of implementation. We systematically screened >48,000 articles using machine learning methods and a global network of 126 researchers. Our synthesis of the resulting 1,682 articles presents a systematic and comprehensive global stocktake of implemented human adaptation to climate change. Documented adaptations were largely fragmented, local and incremental, with limited evidence of transformational adaptation and negligible evidence of risk reduction outcomes. We identify eight priorities for global adaptation research: assess the effectiveness of adaptation responses, enhance the understanding of limits to adaptation, enable individuals and civil society to adapt, include missing places, scholars and scholarship, understand private sector responses, improve methods for synthesizing different forms of evidence, assess the adaptation at different temperature thresholds, and improve the inclusion of timescale and the dynamics of responses. Determining progress in adaptation to climate change is challenging, yet critical as climate change impacts increase. A stocktake of the scientific literature on implemented adaptation now shows that adaptation is mostly fragmented and incremental, with evidence lacking for its impact on reducing risk.

Between a rock and a hard place: Freedom, flexibility, precarity and vulnerability in the gig economy in Africa:

Abstract: The world of work is changing. Communications technologies and digital platforms have enabled some types of work to be delivered from anywhere in the world by anyone with a computer and an internet...

Urban sprawl and its impact on sustainable urban development: a combination of remote sensing and social media data

Abstract: Urbanization is one of the most impactful human activities across the world today affecting the quality of urban life and its sustainable development. Urbanization in Africa is occurring at an unpr...

Chatbots applications in education: A systematic review

Abstract: The introduction of Artificial Intelligence technology enables the integration of Chatbot systems into various aspects of education. This technology is increasingly being used for educational purposes. Chatbot technology has the potential to provide quick and personalised services to everyone in the sector, including institutional employees and students. This paper presents a systematic review of previous studies on the use of Chatbots in education. A systematic review approach was used to analyse 53 articles from recognised digital databases. The review results provide a comprehensive understanding of prior research related to the use of Chatbots in education, including information on existing studies, benefits, and challenges, as well as future research areas on the implementation of Chatbot technology in the field of education. The implications of the findings were discussed, and suggestions were made.

Structure, mechanism and crystallographic fragment screening of the SARS-CoV-2 NSP13 helicase.

Abstract: There is currently a lack of effective drugs to treat people infected with SARS-CoV-2, the cause of the global COVID-19 pandemic. The SARS-CoV-2 Non-structural protein 13 (NSP13) has been identified as a target for anti-virals due to its high sequence conservation and essential role in viral replication. Structural analysis reveals two "druggable" pockets on NSP13 that are among the most conserved sites in the entire SARS-CoV-2 proteome. Here we present crystal structures of SARS-CoV-2 NSP13 solved in the APO form and in the presence of both phosphate and a non-hydrolysable ATP analog. Comparisons of these structures reveal details of conformational changes that provide insights into the helicase mechanism and possible modes of inhibition. To identify starting points for drug development we have performed a crystallographic fragment screen against NSP13. The screen reveals 65 fragment hits across 52 datasets opening the way to structure guided development of novel antiviral agents.

Thermally activated delayed fluorescence (TADF) organic molecules for efficient X-ray scintillation and imaging.

Abstract: X-ray detection, which plays an important role in medical and industrial fields, usually relies on inorganic scintillators to convert X-rays to visible photons; although several high-quantum-yield fluorescent molecules have been tested as scintillators, they are generally less efficient. High-energy radiation can ionize molecules and create secondary electrons and ions. As a result, a high fraction of triplet states is generated, which act as scintillation loss channels. Here we found that X-ray-induced triplet excitons can be exploited for emission through very rapid, thermally activated up-conversion. We report scintillators based on three thermally activated delayed fluorescence molecules with different emission bands, which showed significantly higher efficiency than conventional anthracene-based scintillators. X-ray imaging with 16.6 line pairs mm−1 resolution was also demonstrated. These results highlight the importance of efficient and prompt harvesting of triplet excitons for efficient X-ray scintillation and radiation detection. Triplet exciton harvesting through thermally activated delayed fluorescence is shown to be effective also under X-ray excitation, increasing the efficiency and imaging quality of X-ray detectors based on organic scintillation.

Muon reconstruction and identification efficiency in ATLAS using the full Run 2 pp collision data set at √ s = 13 TeV

Abstract: This article documents the muon reconstruction and identification efficiency obtained by the ATLAS experiment for 139 $$\hbox {fb}^{-1}$$ fb - 1 of pp collision data at $$\sqrt{s}=13$$ s = 13 TeV collected between 2015 and 2018 during Run 2 of the LHC. The increased instantaneous luminosity delivered by the LHC over this period required a reoptimisation of the criteria for the identification of prompt muons. Improved and newly developed algorithms were deployed to preserve high muon identification efficiency with a low misidentification rate and good momentum resolution. The availability of large samples of $$Z\rightarrow \mu \mu $$ Z → μ μ and $$J/\psi \rightarrow \mu \mu $$ J / ψ → μ μ decays, and the minimisation of systematic uncertainties, allows the efficiencies of criteria for muon identification, primary vertex association, and isolation to be measured with an accuracy at the per-mille level in the bulk of the phase space, and up to the percent level in complex kinematic configurations. Excellent performance is achieved over a range of transverse momenta from 3 GeV to several hundred GeV, and across the full muon detector acceptance of $$|\eta |<2.7$$ | η | < 2.7 .

Optimisation of renewable energy powered reverse osmosis desalination systems: A state-of-the-art review

Abstract: Reverse osmosis (RO) desalination has become a prominent desalination method for fresh-water production from either saline seawater or brackish water to meet the ever-growing demand for water, especially in water-scarce regions. Its integration with renewable energy sources (RES) reduces the environmental impact of carbon emission by conventional fossil fuel energy sources. The optimisation of the RES-RO desalination system is intended mainly to minimise total system cost and energy requirements and to guarantee system reliability. In this study, an extensive review of the optimisation of the RES-RO desalination system is presented based on optimal system sizing, optimal system operation and optimal thermodynamic analysis. RES such as geothermal, ocean, wind and solar energy and their hybrids were considered alongside desalination methods. Important findings of the review were discussed, and recommendations made for future work. Key recommendations of this study include the suggestion that extensive optimisation and analysis of a RES-RO system should utilise optimisation approaches that combine the sizing, operation and thermodynamic effect of the system. Future work should furthermore incorporate both economic and reliability indices in the formation of objective functions. Finally, demand response programmes can be introduced to the RES-RO system for demand side management. This has the potential of minimising system cost while maximising fresh-water production.