Reconsidering the performance of DEVS modeling and simulation environments using the DEVStone benchmark

The discrete event system specification formalism, which supports hierarchical and modular model composition, has been widely used to understand, analyze and develop a variety of systems. Discrete event system specification has been implemented in various languages and platforms over the years. The DEVStone benchmark was conceived to generate a set of models with varied structure and behavior, and to automate the evaluation of the performance of discrete event system specification-based simulators. However, DEVStone is still in a preliminary phase and more model analysis is required. In this paper, we revisit DEVStone introducing new equations to compute the number of events triggered. We also introduce a new benchmark with a similar central processing unit and memory requirements to the most complex benchmark in DEVStone, but with an easier implementation and with it being more manageable analytically. Finally, we compare both the performance and memory footprint of five different discrete event system specification simulators in two different hardware platforms

Chapter 18: Standardizing DEVS Simulation Middleware

International audienc

Identification and Activity of a Series of Azole-based Compounds with Lactate Dehydrogenase-directed Anti-malarial Activity.

Plasmodium falciparum, the causative agent of malaria, relies extensively on glycolysis coupled with homolactic fermentation during its blood-borne stages for energy production. Selective inhibitors of the parasite lactate dehydrogenase (LDH), central to NAD(+) regeneration, therefore potentially provide a route to new antimalarial drugs directed against a novel molecular target. A series of heterocyclic, azole-based compounds are described that preferentially inhibit P. falciparum LDH at sub-micromolar concentrations, typically at concentrations about 100-fold lower than required for human lactate dehydrogenase inhibition. Crystal structures show these competitive inhibitors form a network of interactions with amino acids within the active site of the enzyme, stacking alongside the nicotinamide ring of the NAD(+) cofactor. These compounds display modest activity against parasitized erythrocytes, including parasite strains with known resistance to existing anti-malarials and against Plasmodium berghei in BALB/c mice. Initial toxicity data suggest the azole derivatives have generally low cytotoxicity, and preliminary pharmoco-kinetic data show favorable bioavailability and circulation times. These encouraging results suggest that further enhancement of these structures may yield candidates suitable for consideration as new therapeutics for the treatment of malaria. In combination these studies also provide strong support for the validity of targeting the Plasmodium glycolytic pathway and, in particular, LDH in the search for novel anti-malarials

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries

This was an investigator initiated study funded by Nestle Health Sciences through an unrestricted research grant, and by a National Institute for Health Research (UK) Professorship held by RP. The study was sponsored by Queen Mary University of London