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A general chopping peak function for a reservoirs group flood control regulating
No full textFlood event is one of the natural hazards and has affected the most people in the world. As the peak of the flood event is the most striking feature to its hazard, chopping flood peak is often the main goal of preventing flood hazard. To integrate the regulation of the flood storages in a reservoirs group for chopping flood peak, a general relationship among the flood events, the flood storages and the chopping peak has been quantified through Chopping Peak Function (CPF). And we have derived the analytical solutions for a single, a parallel or a cascade reservoirs group while numerical solution for a mixed reservoirs group to their corresponding CPF. Based on the solutions to their CPF, the mechanism is clarified for the integrated reservoirs flood storages regulation. The derived analytical solutions have also been proven to be more efficient for integrating the reservoirs regulation than for only every single reservoir regulation. The numerical solutions for the mixed reservoirs groups are found to be better than that of optimal reservoirs regulation model through NSGA-II in terms of the number and the distribution range of the Pareto frontier. Therefore, our study will not only help understand the regulation of the f lood storages in reservoirs groups for chopping flood peak, but also find an efficient way to prevent flood hazard
Euclid preparation LXXV. Estimating galaxy physical properties using CatBoost chained regressors with attention
No full textThe Euclid Space Telescope will image about 14 000 deg2 of the extragalactic sky at visible and near-infrared wavelengths, providing a dataset of unprecedented size and richness that will facilitate a multitude of studies into the evolution of galaxies. Although spectroscopy will also be available for some of the galaxies, in the vast majority of cases the main source of information will come from broadband images and data products thereof (i.e. photometry). Therefore, there is a pressing need to identify or develop scalable yet reliable methodologies to estimate the redshift and physical properties of galaxies using broadband photometry from Euclid. Optionally, such methods could also include ground-based optical photometry. To address this need, we present a novel method developed as part of a ‘data challenge’ within the Euclid Collaboration to estimate the redshift, stellar mass, star-formation rate, specific star-formation rate, E(B − V), and age of galaxies using mock Euclid and ground-based photometry. The main novelty of our property-estimation pipeline is its use of the CatBoost implementation of gradient-boosted regression-trees together with chained regression and an intelligent, automatic optimisation of the training data. The pipeline also includes a computationally efficient method to estimate prediction uncertainties, and, in the absence of ground-truth labels, it provides accurate predictions for metrics of model performance up to z ∼ 2. We applied our pipeline to several datasets consisting of mock Euclid broadband photometry and mock ground-based ugriz photometry, with the objective of evaluating the performance of our methodology for estimating the redshift and physical properties of galaxies detected in the Euclid Wide Survey. The statistical metrics of prediction residuals vary depending on which mock catalogue and filters are tested. Nonetheless, the quality of our photometric redshift and physical property estimates are highly competitive overall, validating our modelling approach. However, at z ≳ 3.5, the relative sparsity of galaxies resulted in unreliable redshift and physical property estimates, which we argue could be mitigated by building catalogues with better sampling of z ≳ 3.5 galaxies or by switching to the use of spectral energy distribution fitting in this regime. We also find that the inclusion of ground-based optical photometry significantly improves the quality of the property estimation, highlighting the importance of combining Euclid data with ancillary ground-based data from such surveys as the Vera C. Rubin Observatory Legacy Survey of Space and Time and UNIONS
van Aarde Andries G
No full textWhen the first coronavirus disease caused by SARS-CoV-2 virus (COVID-19) case was diagnosed in Wuhan, China, in December 2019, no one would have predicted its rapid global transmission pace. As physicians, epidemiologists and policy makers were frantically investigating the pathogen’s natural reservoir, it rampantly spread to all continents. Beginning with a few cases identified in Wuhan (Li, Liu & Ge 2020), by mid-June 2023, ‘there were 767,984,989 confirmed cases of COVID-19’ globally (World Health Organization [WHO] 2023, p. 1). This exponential increase in global infections from 2019 to 2020 as well as morbidity and mortality rates impelled the WHO to declare COVID-19 a global health emergency of international concern in early 2020 (Sohrabi et al. 2020). By the time, this WHO declaration was lifted in May 2023, COVID-19 had claimed the lives of 6,943,390 people worldwide (WHO 2023) of which 256,542 were Africans (Africa Centre for Disease Control and Prevention 2023). These high mortality statistics at a global level were because of the initial lack of safe, effective vaccines and later, their delayed roll out post-development because of regulatory and policy approval bottlenecks. There are, however, continental and country-level variations that explain delayed vaccine roll out and, in some cases, outright limited access. A case in point is South Africa, which I use as a reference point in this chapter to argue that thousands of lives and livelihoods were lost because of a complex combination of factors that include profiteering by big pharmaceutica
Examining the challenges and strategies of intellectual property management in technology startup companies in South Africa
No full textIntellectual property (IP) refers to the fruits of original human creativity and ingenuity that qualifies for legal protection. Types of IP include patents, copyrights, trademarks, designs, and trade secrets and confidential information. Research has shown that effective management of IP improves business performance and competitiveness, more especially for startup companies. Startup companies are newly formed companies with an objective of developing a unique product or service, bringing it to the market, and making it irresistible and irreplaceable for customers. It is even more crucial for technology focused startup companies to effectively manage their IP portfolios because of the competitiveness of the technology market. Literature reveals that there is consensus amongst researchers about the impact of IP management on performance of business entities. It has also been suggested that larger businesses tend to use formal ways of IP protection than startup or smaller businesses due to various constraints which smaller business are subjected. Research have shown that smaller businesses opt for informal ways of protecting their IP such as trade secrecy but according to the researchers, evidence shows that this approach yields below average business performance. This research studied the challenges to, and strategies of IP management in technology startup companies in South Africa. The research sought to determine how best technology startup companies in South Africa can manage their IP in order to get the best value out of their intangible assets. The study utilised doctrinal research methodology, it analysed primary and secondary sources of law. It was found that South African technology startup companies lack the understanding of IP and the benefits associated with it. Furthermore, they do not have sufficient financial resources to invest in the protection of IP. The study recommends that South African technology startup companies should use cost control strategy to manage IP in order to get the best value
Survival among medically insured and treated head and neck cancer patients with and without HIV in South Africa
No full textObjectives: To assess the association of HIV and overall survival among medically insured head and neck cancer (HNC) patients in South Africa and to examine factors associated with the type of treatment received. Methods: We used reimbursement claims data from a South African medical insurance scheme database from 1 January 2011 to 1 July 2020. We included individuals with at least two International Classification of Diseases (ICD-10) codes for HNC and at least one cancer treatment code within 180 days of the HNC diagnosis. We used logistic regression to identify factors associated with receiving a specific type of cancer treatment and Cox proportional hazards models to examine factors associated with all-cause mortality. Results: We included 566 HNC patients, 49 of whom lived with HIV and 383 were male. Patients with HIV were substantially younger at HNC diagnosis (median age: 52.5 years) than patients without HIV (median age: 61.6 years). We found no clear association between HIV status and the treatment type received. The median survival was 3.78 years (95% confidence interval [CI] 3.01–6.08) and the five-year survival was 46.0% (95% CI 41.2%–51.5%). The risk of death was higher among patients with HIV than those without HIV (adjusted hazard ratio 1.68; 95% CI 1.00–2.81). Conclusion: Medically insured HNC patients in South Africa with HIV had higher mortality than those without HIV. This underscores the importance of tailored cancer care strategies for HNC patients with HIV
On the role of high speed electron beams in the generation of subsonic solitons on electron dynamic timescales
No full textA comprehensive theoretical investigation of the effects of electron beams on high frequency electron-acoustic waves is conducted for plasmas comprising two warm (adiabatic) electron components, Boltzmann electrons, and immobile ions of which one or both adiabatic electron fluid components are modeled as drifting (beams). A systematic approach is followed, starting with a single beam model comprising cool electrons, warm beam electrons, and hot electrons consistent with Berthomier et al. [Phys. Plasmas 7, 2987–2994 (2000)] and then proceeding to models with asymmetric and symmetric counterstreaming electron beams. The subsonic character of the solitons in the nonlinear regime is attributed to the effect of the beam(s) that support(s) the directional change of the backward propagating fast (or both slow mode) waves in the model with a single (counterstreaming) beam(s). This results in the coupling of two wave modes, which decouple for higher beam speeds. The results of our study are generic to other plasma systems containing heavier inertial plasma components as the findings are very similar to ion beam effects on low frequency ion-acoustic waves reported by Zank and McKenzie [J. Plasma Phys. 39, 183–191 (1988)] and Lakhina et al. [Phys. Scr. 95, 105601 (2020)] in models with a single and counterstreaming ion beams, respectively. In fact, similar reasoning applies in validating the generation of subsonic waves in the above reports as it relates to the directional change(s) of the linear wave(s), which also explains the generation of subsonic waves in the paper by Berthomier and coworkers in a single beam model
Synthesis, in silico and antimicrobial activity study of substituted aromatic imines and their corresponding amines
No full textThe antimicrobial properties of Schiff bases and their corresponding amines were assessed by exploring the impact of substituent variations on these activities. The present study involved the synthesis of Schiff base compounds and their corresponding sec-amines, characterization, antibacterial testing, and molecular docking studies. These compounds featured diverse structural components, including alkyl chains, phenyl and methoxy groups. Three of the synthesized compounds are new, viz. N-[(2,3-dimethoxyphenyl) methylene]-1-propanamine (1), N-[(2,3-dimethoxyphenyl)methyl]-1-propanamine (2) and N-[(2,3-dimethoxyphenyl)methylene]-1-butanamine (3). The assessment of antibacterial properties targeted two strains recognized as opportunistic pathogens. Notably, all Schiff base compounds possessing the −C=N moiety exhibited good antibacterial activity against P. aeruginosa and P. agglomerans. Specifically, 1 and 3 demonstrated exceptional effectiveness against the tested bacterial strains, showcasing promising antibacterial capabilities. Furthermore, binding energy calculations revealed that compounds 1 and 3 exhibited binding energies of −3.9, −4.1, and −3.8, −3.9 kcal/mol with respect to P. agglomerans and P. aeruginosa candidate proteins, respectively. This underscores the strong interaction between the synthesized compounds and the bacterial strains, further supporting their potential as potent antimicrobial agents. P. aeruginosa and P. agglomerans were found to be sensitive to both compounds 1 and 3, as well as the standard control ampicillin. The MIC values for P. aeruginosa were 10 mM for 1, and 6 mM for 3. While for P. agglomerans, the MIC values were 6 mM for both 1 and 3
The prevalence of falls among older adults living in long-term care facilities in the City of Cape Town
No full textFalls are a prevalent health concern with a multi-factorial origin and causing numerous complications for older adults, especially those in low- and middle-income countries, such as South Africa. This study aimed to determine the prevalence of falls among older adults living in different types of long-term care facilities in the City of Cape Town. A total of 258 males and females aged between 60 and 95 years were recruited. Data collection occurred from September 2021 to January 2022. Participants were categorized into low, moderate, or high fall risk using the fall-risk assessment tool. Descriptive statistics summarized participant characteristics and fall prevalence. The chi-squared test determined significant associations between facility type, marital status, and educational level, and their relationship to falling. Spearman’s rank correlation coefficient assessed associations between fall occurrence and various risk factors. Findings indicated that the prevalence of falls was 32.6%. Falls were significantly associated with behaviors such as agitation or confusion, and other unmentioned risk factors. Participants living in facilities run by non-profit organizations, and who had a lower education level or were single or widowed, had a higher fall prevalence. The use of anti-depressant and anti-diabetic medications was significantly linked to increased fall risk. These findings can inform future research and the development of strategies to prevent falls among older adults, particularly in LTC facilities
Improved reconstruction of highly boosted -lepton pairs in the decay channels with the ATLAS detector
No full textThis paper presents a new -lepton reconstruction and identification procedure at the ATLAS detector at the Large Hadron Collider, which leads to significantly improved performance in the case of physics processes where a highly boosted pair of -leptons is produced and one -lepton decays into a muon and two neutrinos , and the other decays into hadrons and one neutrino. By removing the muon information from the signals used for reconstruction and identification of the
candidate in the boosted pair, the efficiency is raised to the level expected for an isolated. The new procedure is validated by selecting a sample of highly boosted candidates from the data sample of 140 of proton–proton collisions at 13 TeV recorded with the ATLAS detector. Good agreement is found between data and simulation predictions in both the signal region and in a background validation region. The results presented in this paper demonstrate the effectiveness of the
reconstruction with muon removal in enhancing the signal sensitivity of the boosted channel at the ATLAS detector
What is scholar-baiting? when the watcher is watched, and the social engineering attacks on scholars
No full textI write from the dual position of witness and analyst, using autoethnography to examine a scholar-targeted form of social engineering. The scammers baited me, mimicking academic language, citing published work, and deploying emotionally charged narratives to elicit trust and ethical engagement. From this dual role, I introduce two emergent constructs (“scholar-baiting” and “document staging”) to describe how epistemic trust and narrative craft are exploited in academic-facing fraud. Scholar-baiting is a sub-genre of spear phishing, defined as a narrative-based form of deception. Document staging, on the other hand, is a dramaturgical tactic in which realistic artefacts are embedded to simulate plausibility and suppress suspicion. I further theorise emotional enmeshment and symbolic entrapment as emerging risks for scholars whose work centres on harm, justice, and vulnerability. I conclude by proposing a framework of defensive scholarship that repositions cyber hygiene as a form of epistemic reflexivity. This framing recognises that scholars’ ethical commitments to engagement and vulnerability can be exploited as attack surfaces. By framing scholars as high-trust nodes in digital ecosystems, I highlight a threat to academic labour that remains under-theorised but urgently relevant