On-the-fly memory compression for multibody algorithms.

Memory and bandwidth demands challenge developers of particle-based codes that have to scale on new architectures, as the growth of concurrency outperforms improvements in memory access facilities, as the memory per core tends to stagnate, and as communication networks cannot increase bandwidth arbitrary. We propose to analyse each particle of such a code to find out whether a hierarchical data representation storing data with reduced precision caps the memory demands without exceeding given error bounds. For admissible candidates, we perform this compression and thus reduce the pressure on the memory subsystem, lower the total memory footprint and reduce the data to be exchanged via MPI. Notably, our analysis and transformation changes the data compression dynamically, i.e. the choice of data format follows the solution characteristics, and it does not require us to alter the core simulation code

Misoprostol alone for the termination of pregnancy

The administration of mifepristone, a powerful antiprogestin, coupled with a prostaglandin, is a highly effective medical method of terminating pregnancy. Of the most widely used prostaglandins, namely gemeprost and misoprostol, the latter shows the greater promise for developing countries, since it can be administered orally and is inexpensive, stable at ambient temperatures and widely available. South African Family Practice Vol. 49 (3) 2007: pp. 1

Using Monte Carlo simulation to quantify the cost impact of systemic risk factors in a project portfolio : a case study

CITATION: Joubert, F. J. & Snyman, M. 2021. Using Monte Carlo simulation to quantify the cost impact of systemic risk factors in a project portfolio : a case study. South African Journal of Industrial Engineering, 32(4):67-82, doi:10.7166/32-4-2518.The original publication is available at http://sajie.journals.ac.zaENGLISH ABSTRACT: In terms of project risk management, ‘systemic risk’ is identified as risks which are artefacts of the environment which a project is executed in, and are related to (i) the project team’s actions, (ii) how project controls are managed and interact, and (iii) how the project is planned and executed. This paper proposes a methodology to estimate the cost impact of systemic risk on a portfolio of projects by using risk quantification and Monte Carlo simulation, in the absence of a validated parametric risk model, to estimate the systemic risks in an entire portfolio of projects. The case study simulation results indicate a significant effect of systemic risks on the project portfolio risk profile, where systemic risks increased the P80 value of the contingency requirement by +85.6%. The successful management of systemic risk would contribute to project success by limiting unnecessary waste.AFRIKAANSE OPSOMMING: In terme van projekrisikobestuur word sistemiese risiko’s geïdentifiseer as risiko’s wat ʼn karakteristiek is van die omgewing waarbinne die projek uitgevoer word. Hierdie risiko’s hou verband met (i) die aksies van die projekbestuurspan, (ii) hoe projekkontroles bestuur word en ineenskakel, en (iii) hoe die projek beplan en uitgevoer word. Hierdie artikel stel ʼn metode voor wat gebruik kan word om die koste-impak van sistemiese risiko’s op ʼn projek portefeulje te bepaal waar daar ʼn gebrek is aan ʼn geldige paremetriese model vir die berekening van sistemiese risiko’s se impak op ʼn hele projekportefeulje. Dit word gedoen deur middel van risiko kwantifisering en Monte Carlo simulasie. Die resultaat toon ʼn noemenswaardige impak van sistemiese risiko’s op die risikoprofiel van die projekportefeulje, waar sistemiese risiko die gebeurlikheidsbegroting met +85.6 % verhoog het. Die suksesvolle bestuur van sistemiese risiko’s kan ʼn noemenswaardige effek op projek sukses uitoefen deur die beperking van onnodige vermorsing.http://sajie.journals.ac.za/pub/article/view/2518Publisher's versio

Critical care triage during the COVID-19 pandemic in South Africa: A constitutional imperative!

Triage and rationing of scarce intensive care unit (ICU) resources are an unavoidable necessity. In routine circumstances, ICU triage is premised on the best interests of an individual patient; however, when increased demand exceeds capacity, as during an infectious disease outbreak, healthcare providers need to make difficult decisions to benefit the broader community while still respecting individual interests. We are currently living through an unprecedented period, with South Africa (SA) facing the challenges of the global COVID-19 pandemic. The Critical Care Society of Southern Africa (CCSSA) expedited the development of a triage guidance document to inform the appropriate and fair use of scarce ICU resources during this pandemic. Triage decision-making is based on the clinical odds of a positive ICU outcome, balanced against the risk of mortality and longer-term morbidity affecting quality of life. Factors such as age and comorbid conditions are considered for their potential impact on clinical outcome, but are never the sole criteria for denying ICU-level care. Arbitrary, unfair discrimination is never condoned. The CCSSA COVID-19 triage guideline is aligned with SA law and international ethical standards, and upholds respect for all persons. The Bill of Rights, however, does not mandate the level of care enshrined in the constitutional right to healthcare. ICU admission is not always appropriate, available or feasible for every person suffering critical illness or injury; however, everyone has the right to receive appropriate healthcare at another level. If ICU resources are used for people who do not stand to benefit, this effectively denies others access to potentially life-saving healthcare. Appropriate triaging can therefore be considered a constitutional imperative

Trends in pharmacotherapy selection for the treatment of alcohol withdrawal in the Free State Province, South Africa

Background.The selection of pharmacotherapy for the treatment of alcohol withdrawal remains a clinical challenge. Research continues into the underlying pathophysiology of dependence and withdrawal. A spectrum of clinical presentations of alcohol dependence is emerging, yet recommendations and guidelines have remained unchanged for some time.  Objectives. To engage with the problem of translating research into practice, as reflected by the selection of pharmacotherapy for alcohol withdrawal by medical practitioners in the Free State Province, South Africa. Methods. A questionnaire-based survey and interviews were conducted among 121 professionals in both the private and public sectors across the province. A subgroup was formed comprising the 58 doctors who indicated that they prescribe for alcohol withdrawal. Participants worked in private general practice, specialist psychiatry practice, in a state hospital or in a treatment centre. Results. Prescribing practices varied based on practitioners’ geographical distribution and professional capacity. Deviation from standard recommendations included the routine use of clothiapine and antidepressants in withdrawal regimens. Prescribing clothiapine appears to be a local custom. While prescription of antidepressants may indicate unrealistic expectations of therapeutic benefit, there are clear indications that this is maintained to mask the diagnosis of an alcohol-related condition. Prescribing for alcohol withdrawal is therefore not necessarily determined by pathophysiology or efficacy of medication. Conclusion. Withdrawal regimens need to be reassessed by researchers, policy makers and funders, balancing new developments with the real-life experiences and challenges of prescribers and their patients

Help-seeking by substance dependants presenting to healthcare professionals in the Free State Province

Introduction. Current data regarding treatment needs in South Africa for substance dependence are based on admissions to specialised treatment centres. The data therefore do not include patients presenting to independent healthcare workers and state hospitals. Aim. The aim of this study was to investigate help-seeking behaviour for substance dependence disorders from the perspective of healthcare professionals at various levels of the referral chain in Free State Province. Design. A descriptive study was performed. Setting. Treatment environments in Free State Province accessible to substance-dependent persons. Participants. General practitioners, private psychiatrists, prescribing healthcare professionals at state hospitals and treatment centres, and non-prescribing therapists responsible for management of substance-dependent persons. Measurements. A questionnaire was used to determine the level of help-seeking experienced by the participants regarding various classes of psycho-active substances. Findings. The presentation of alcohol, cannabis, opioid, benzodiazepine, ecstasy, cocaine and inhalant dependency at general practitioners, private psychiatrists, treatment centres and non-prescribing therapists was compared. Different patterns of help-seeking for substance dependence from the various professional groups were detected. Regarding alcohol dependence, 40.3% of private general medical practitioners reported being confronted with alcohol dependence at least once per month, compared with 100% of treatment centre representatives and private psychiatrists, 70.6% of state hospitals and 53.8% of non-prescribers. State hospitals reported the highest frequency for contact with cases of cannabis dependence, compared with the other professional groups, while psychiatrists reported the highest contact with cases involving benzodiazepine, cocaine and ecstasy. Therapists reported a higher level of contact with inhalant dependence, while this group virtually never presented at general practitioners and private psychiatrists. Conclusion. Help-seeking data can be used in conjunction with other data, such as treatment demand data, to inform and adapt policies and practice. Variations in the manifestation of help-seeking behaviour at various groups may be important pointers to conditions that influence help-seeking, and therefore should be investigated further

Superconducting booster cyclotron studies at GANIL

International audienc

Nuclear structure and reaction studies at SPIRAL

The SPIRAL facility at GANIL, operational since 2001, is described briefly. The diverse physics program using the re-accelerated (1.2 to 25 MeV/u) beams ranging from He to Kr and the instrumentation specially developed for their exploitation are presented. Results of these studies, using both direct and compound processes, addressing various questions related to the existence of exotic states of nuclear matter, evolution of new "magic numbers", tunnelling of exotic nuclei, neutron correlations, exotic pathways in astrophysical sites and characterization of the continuum are discussed. The future prospects for the facility and the path towards SPIRAL2, a next generation ISOL facility, are also briefly presented.Comment: 48 pages, 27 figures. Accepted for publication in Journal of Physics

An examination of semantic impairment in amnestic MCI and AD : What can we learn from verbal fluency?

Introduction The Verbal Fluency Test (VF) is commonly used in neuropsychology. Some studies have demonstrated a marked impairment of semantic VF compared to phonemic VF in Alzheimer’s disease (AD). Since amnestic Mild Cognitive Impairment (aMCI) is associated with increased risk of conversion to incident AD, it is relevant to examine whether a similar impairment is observed in this population. The objective of the present empirical study is to compare VF performance of aMCI patients to those of AD and elderly controls matched one-to-one for age and education. Method Ninety-six participants divided into three equal groups (N = 32: AD, aMCI and Controls) were included in this study. Participants in each group were, on average, 76 years of age and had 13 years of education. A repeated measures ANOVA with the Group (AD, aMCI, NC) as between-subject factor and the Fluency condition (“P” and “animals”) as within-subject factor was performed. T-tests and simple ANOVAs were also conducted to examine the interaction. Results There was a significant interaction between the groups and the verbal fluency condition. In AD, significantly fewer words were produced in both conditions. In contrast, participants with aMCI demonstrated a pattern similar to controls in the phonemic condition, but generated significantly fewer words in the semantic condition. Conclusion These results indicate a semantic memory impairment in aMCI revealed by a simple, commonly-used neuropsychological test. Future studies are needed to investigate if semantic fluency deficits can help predict future conversion to AD

On-the-fly memory compression for multibody algorithms

Memory and bandwidth demands challenge developers of particle-based codes that have to scale on new architectures, as the growth of concurrency outperforms improvements in memory access facilities, as the memory per core tends to stagnate, and as communication networks cannot increase bandwidth arbitrary. We propose to analyse each particle of such a code to find out whether a hierarchical data representation storing data with reduced precision caps the memory demands without exceeding given error bounds. For admissible candidates, we perform this compression and thus reduce the pressure on the memory subsystem, lower the total memory footprint and reduce the data to be exchanged via MPI. Notably, our analysis and transformation changes the data compression dynamically, i.e. the choice of data format follows the solution characteristics, and it does not require us to alter the core simulation code