Density Profile and Flow of Miscible Fluid with Dissimilar Constituent Masses

A computer simulation model is used to study the density profile and flow of a miscible gaseous fluid mixture consisting of differing constituent masses (m(A) = m(B)/3) through an open matrix. The density profile is found to decay with the height proportional to exp(-m(A(B))h), consistent with the barometric height law. The flux density shows a power-law increase proportional to (p(c) - p)(a) with mu similar or equal to 2.3 at the porosity 1 - p above the pore percolation threshold 1 - p(c). (C) 2002 Elsevier Science B.V. All rights reserved

Improving primary care antimicrobial stewardship by implementing a peer audit and feedback intervention in Cape Town community healthcare centres

Background. The increasing prevalence of antibiotic resistance is a major threat to public health. Primary care, where 80% of antibiotics are consumed, is a pivotal setting to direct antimicrobial stewardship (AMS) efforts. However, the ideal model to improve antibiotic prescribing in primary care in low-resource settings is not known.Objective. To implement a multidisciplinary audit and feedback AMS intervention with the aim to improve appropriate antibiotic prescribing at primary care level.Methods. The intervention was implemented and monitored in 10 primary care centres of the Cape Town metropole between July 2017 and June 2019. The primary and secondary outcome measures were monthly adherence to a bundle of antibiotic quality process measures and monthly antibiotic consumption, respectively. Multidisciplinary audit and feedback meetings were initiated and integrated into facility clinical meetings. Two Excel tools were utilised to automatically calculate facility audit scores and consumption. Once a month, 10 antibiotic prescriptions were randomly selected for a peer review audit by the team. The prescriptions were audited for adherence to a bundle of seven antibiotic process measures using the standard treatment guidelines (STG) and Essential Medicines List (EML) as standard. Concurrently, primary care pharmacists monitored monthly antibiotic consumption by calculating defined daily doses (DDDs) per 100 prescriptions dispensed. Adherence and consumption feedback were regularly provided to the facilities. Learning collaboratives involving representative multidisciplinary teams were held twice-yearly. Pre-, baseline and post-intervention periods were defined as 6 months before, first 6 months and last 6 months of the study, respectively.Results. The mean overall adherence increased from 19% (baseline) to 47% (post intervention) (p<0.001). Of the 2 077 prescriptions analysed, 33.7% had an antibiotic prescribed inappropriately. No diagnosis had been captured in patient notes, and the antibiotic chosen was not according to the STG and EML in 30.1% and 31.7% of cases, respectively. Seasonal variation was observed in prescribing adherence, with significantly lower adherence in winter and spring months (adjusted odds ratio 0.60). A reduction of 12.9 DDDs between the pre- and post-intervention periods (p=0.0084) was documented, which represented a 19.3% decrease in antibiotic consumption.Conclusion. The study demonstrated that peer reviewed audit and feedback is an effective AMS intervention to improve antibiotic prescribing in primary care in a low-resource setting. The intervention, utilising existing resources and involving multidisciplinary engagement, may be incorporated into existing quality improvement processes at facility level, to ensure sustainable change

Low mortality of people living with diabetes mellitus diagnosed with COVID-19 and managed at a field hospital in Western Cape Province, South Africa

Background. The novel coronavirus disease 2019 (COVID-19) was declared an international pandemic by the World Health Organization in March 2020. Throughout the pandemic, the association between diabetes mellitus (DM) and more severe COVID-19 has been well described internationally, with limited data, however, on South Africa (SA). The role of field hospitals in the management of patients with COVID-19 in SA has not yet been described. Objectives. To describe the mortality and morbidity of people living with DM (PLWD) and comorbid COVID-19, as well as to shed light on the role of intermediate facilities in managing DM and COVID-19 during the pandemic. Methods. This is a single-centre cross-sectional descriptive study that included all patients with confirmed COVID-19 and pre-existing or newly diagnosed DM (of any type) admitted to the Cape Town International Convention Centre (CTICC) Intermediate Care Bed Facility from June 2020 to August 2020. This study presents the profile of patients admitted to the CTICC, and reports on the clinical outcome of PLWD diagnosed with COVID-19, and additionally determines some associations between risk factors and death or escalation of care in this setting. Results. There were 1 447 admissions at the CTICC, with a total of 674 (46.6%) patients who had confirmed DM, of whom 125 (19%) were newly diagnosed diabetics and 550 (81%) had pre-existing DM. Included in this group were 57 referrals from the telemedicine platform – a platform that identified high-risk diabetic patients with COVID-19 in the community, and linked them directly to hospital inpatient care. Of the 674 PLWD admitted, 593 were discharged alive, 45 were escalated to tertiary hospital requiring advanced care and 36 died. PLWD who died were older, had more comorbidities (specifically chronic obstructive pulmonary disease, congestive cardiac failure and chronic kidney disease) and were more likely to be on insulin.Conclusions. In a resource-limited environment, interdisciplinary and interfacility collaboration ensured that complicated patients with DM and COVID-19 were successfully managed in a field hospital setting. Telemedicine offered a unique opportunity to identify high-risk patients in the community and link them to in-hospital monitoring and care. Future studies should explore ways to optimise this collaboration, as well as to explore possibilities for early identification and management of high-risk patients

Impact of dislocations and dangling bond defects on the electrical performance of crystalline silicon thin films

A wide variety of liquid and solid phase crystallized silicon films are investigated in order to determine the performance limiting defect types in crystalline silicon thin-film solar cells. Complementary characterization methods, such as electron spin resonance, photoluminescence, and electron microscopy, yield the densities of dangling bond defects and dislocations which are correlated with the electronic material quality in terms of solar cell open circuit voltage. The results indicate that the strongly differing performance of small-grained solid and large-grain liquid phase crystallized silicon can be explained by intra-grain defects like dislocations rather than grain boundary dangling bonds. A numerical model is developed containing both defect types, dislocations and dangling bonds, describing the experimental results

The prothrombotic state in paroxysmal nocturnal hemoglobinuria: a multifaceted source

Paroxysmal nocturnal hemoglobinuria is a rare acquired hematologic disorder, the most serious complication of which is thrombosis. The increased incidence of thrombosis in paroxysmal nocturnal hemoglobinuria is still poorly understood, but unlike many other thrombotic disorders, predominantly involves complement-mediated mechanisms. This review article discusses the different factors that contribute to the increased risk of thrombosis in paroxysmal nocturnal hemoglobinuria. Paroxysmal nocturnal hemoglobinuria leads to a complex and multifaceted prothrombotic state due to the pathological effects of platelet activation, intravascular hemolysis and neutrophil/monocyte activation. Platelet and endothelial microparticles as well as oxidative stress may play a role. Impaired fibrinolysis has also been observed and may be caused by several mechanisms involving interactions between complement activation, coagulation and fibrinolysis. While many factors may affect thrombosis in paroxysmal nocturnal hemoglobinuria, the relative contribution of each mechanism that has been implicated is difficult to quantify. Further studies, including novel in vivo and in vitro thrombosis models, are required in order to define the role of the individual mechanisms contributing to thrombosis, impaired fibrinolysis and clarify other complement-driven prothrombotic mechanisms in paroxysmal nocturnal hemoglobinuria

Explanations of Black-Box Model Predictions by Contextual Importance and Utility

The significant advances in autonomous systems together with an immensely wider application domain have increased the need for trustable intelligent systems. Explainable artificial intelligence is gaining considerable attention among researchers and developers to address this requirement. Although there is an increasing number of works on interpretable and transparent machine learning algorithms, they are mostly intended for the technical users. Explanations for the end-user have been neglected in many usable and practical applications. In this work, we present the Contextual Importance (CI) and Contextual Utility (CU) concepts to extract explanations that are easily understandable by experts as well as novice users. This method explains the prediction results without transforming the model into an interpretable one. We present an example of providing explanations for linear and non-linear models to demonstrate the generalizability of the method. CI and CU are numerical values that can be represented to the user in visuals and natural language form to justify actions and explain reasoning for individual instances, situations, and contexts. We show the utility of explanations in car selection example and Iris flower classification by presenting complete (i.e. the causes of an individual prediction) and contrastive explanation (i.e. contrasting instance against the instance of interest). The experimental results show the feasibility and validity of the provided explanation methods