Developing flow in S-shaped ducts. 1: Square cross-section duct

Laser-Doppler velocimetry was used to measure the laminar and turbulent flow in an S-duct formed with two 22.5 deg sectors of a bend with ratio of mean radius of curvature to hydraulic diameter of 7.0. The boundary layers at the inlet to the bend were about 25% and 15% of the hydraulic diameter for the laminar and turbulent flows, respectively. Pressure-driven secondary flows develop in the first half of the S-duct and persist into the second half but are largely reversed by the exit plane as a consequence of the change in the sense of curvature. There is, however, a region near the outer wall of the second bend where the redistribution of the streamwise isotachs results in a reinforcement of the secondary flow which was established in the first half of the S-duct. The net redistribution of the streamwise isotachs is comparable to that occurring in unidirectional bends of stronger curvature. The wall pressure distribution was also measured for the turbulent flow and quantifies the expected large variations in the longitudinal pressure gradient distributions which occur at different radial locations

Surveillance of healthcare-associated infection in hospitalised South African children: Which method performs best?

Background. In 2012, the South African (SA) National Department of Health mandated surveillance of healthcare-associated infection (HAI), but made no recommendations of appropriate surveillance methods.Methods. Prospective clinical HAI surveillance (the reference method) was conducted at Tygerberg Children’s Hospital, Cape Town, from 1 May to 31 October 2015. Performance of three surveillance methods (point prevalence surveys (PPSs), laboratory surveillance and tracking of antimicrobial prescriptions) was compared with the reference method using surveillance evaluation guidelines. Factors associated with failure to detect HAI were identified by logistic regression analysis.Results. The reference method detected 417 HAIs among 1 347 paediatric hospitalisations (HAI incidence of 31/1000 patient days; 95% confidence interval (CI) 28.2 - 34.2). Surveillance methods had variable sensitivity (S) and positive predictive value (PPV): PPS S = 24.9% (95% CI 21 - 29.3), PPV = 100%; laboratory surveillance S = 48.4% (95% CI 43.7 - 53.2), PPV = 55.2% (95% CI 50.1 - 60.2); and antimicrobial prescriptions S = 66.4% (95% CI 61.8 - 70.8%), PPV = 88.5% (95% CI 84.5 - 91.6). Combined laboratory-antimicrobial surveillance achieved superior HAI detection (S = 84.7% (95% CI 80.9 - 87.8%), PPV = 97% (95% CI 94.6 - 98.4%)). Factors associated with failure to detect HAI included patient transfer (odds ratio (OR) 2.0), single HAI event (OR 2.8), age category 1 - 5 years (OR 2.1) and hospitalisation in a general ward (OR 2.3).Conclusions. Repeated PPSs, laboratory surveillance and/or antimicrobial prescription tracking are feasible HAI surveillance methods for low-resource settings. Combined laboratory-antimicrobial surveillance achieved the best sensitivity and PPV. SA paediatric healthcare facilities should individualise HAI surveillance, selecting a method suited to available resources and practice context

Influence of variation of etching conditions on the sensitivity of PADC detectors with a new evaluation method

At the Paul Scherrer Institut, a personal neutron dosimetry system based on chemically etched poly allyl diglycol carbonate (PADC) detectors and an automatic track counting (Autoscan 60) for neutron dose evaluations has been in routine use since 1998. Today, the hardware and the software of the Autoscan 60 are out of date, no spare components are available anymore and more sophisticated image-analysis systems are already developed. Therefore, a new evaluation system, the ‘TASLIMAGE', was tested thoroughly in 2009 for linearity, reproducibility, influence of etching conditions and so forth, with the intention of replacing the Autoscan 60 in routine evaluations. The TASLIMAGE system is based on a microscope (high-quality Nikon optics) and an ultra-fast three-axis motorised control for scanning the detectors. In this paper, the TASLIMAGE system and its possibilities for neutron dose calculation are explained in more detail and the study of the influence of the variation of etching conditions on the sensitivity and background of the PADC detectors is described. The etching temperature and etching duration were varied, which showed that the etching conditions do not have a significant influence on the results of non-irradiated detectors. However, the sensitivity of irradiated detectors decreases by 5 % per 1°C when increasing the etching temperature. For the variation of the etching duration, the influence on the sensitivity of irradiated detectors is less pronounce

Basin-Fill Stratigraphy, Quaternary History, and Paleomagnetics of the Eagle Flat Study Area, Southern Hudspeth County, Texas

Data and analyses of basin-fill stratigraphy, paleomagnetics, Quaternary history, and pseudo-fissures/fissures were acquired and interpreted by the Bureau of Economic Geology (BEG) in the Eagle Flat study area in southern Hudspeth County, Texas. These investigations were funded by the Texas Low-Level Radioactive Waste Disposal Authority (the Authority) as part of the evaluation of a proposed site for the Texas low-level radioactive waste repository. Data and information developed as a result of these investigations will be used to evaluate the proposed waste repository site and surrounding region and to provide data for performance assessment, design, and licensing activities. Basin-fill sediments are composed predominantly of sandy mud and mud; sands are abundant at the surface in the vicinity of the proposed repository site, and gravels are abundant at the base of the basin fill adjacent to the bedrock. Basin-fill thickness ranges from 163 ft (50 m) on the southeast side of the proposed site to 715 ft (218 m) on the northeast side of the proposed site. Basin-fill thickness is approximately 200 ft (61 m) on the west side of the proposed site. Coarser basin-fill deposits are interpreted as proximal alluvial fans and colluvium, and finer sands and muds are interpreted as ephemeral stream, distal alluvial fan, alluvial flat, and eolian deposits. At the proposed site, near-surface fine gravel and coarse to fine sand deposits exhibit characteristics consistent with fluvial deposition. Some well-sorted fine-grained sands have textures consistent with eolian sediments. Fine-grained sands and muds are interpreted as distal alluvial fan and ephemeral stream deposits.Bureau of Economic Geolog

The Clostridium difficile problem: A South African tertiary institution's prospective perspective

BACKGROUND AND OBJECTIVES: The aim of this study is to report the incidence of Clostridium difficile-associated disease (CDAD) in a tertiary-care hospital in South Africa and to identify risk factors, assess patient outcomes and determine the impact of the hypervirulent strain of the organism referred to as North American pulsed-field type 1 (NAP1). METHODS: Adults who presented with diarrhoea over a period of 15 months were prospectively evaluated for CDAD using stool toxin enzyme immunoassay (EIA). Positive specimens were evaluated by PCR. Patient demographics, laboratory parameters and outcomes were analysed. RESULTS: CDAD was diagnosed in 59 (9.2%) of 643 patients (median age 39 years, IQR 30 - 55). Thirty-four (58%) were female. Recent antibiotic exposure was reported in 39 (66%), 27 (46%) had been hospitalised within 3 months, and 14 (24%) had concomitant inflammatory bowel disease (IBD). Nineteen (32%) had community-acquired CDAD (CA-CDAD). The annual incidence of hospital-acquired CDAD (HA-CDAD) was 8.7 cases/10 000 hospitalisations. Two cases of the hypervirulent strain NAP1 were identified. Seven (12%) patients underwent colectomy (OR 6.83; 95% CI 2.41 - 19.3). On logistic regression, only antibiotic exposure independently predicted for CDAD (OR 2.9; 95% CI 1.6 - 5.1). Three (16%) cases of CA-CDAD reported antibiotic exposure (v. 90% of HA-CDAD, p<0.0001). Twelve (86%) patients had concomitant IBD (p<0.0001 v. HA-CDAD). CA-CDAD was significantly associated with antibiotic exposure (OR 0.04, 95% CI 0.01 - 0.24) and IBD (OR 9.6, 95% CI 1.15 - 79.8). CONCLUSION: The incidence of HA-CDAD in the South African setting is far lower than that reported in the West. While antibiotic use was a major risk factor for HA-CDAD, CA-CDAD was not associated with antibiotic therapy. Concurrent IBD was a predictor of CA-CDAD

A framework for preventing healthcare-associated infection in neonates and children in South Africa

CITATION: Dramowski, A., Cotton, M. F. & Whitelaw, A. 2017. A framework for preventing healthcare-associated infection in neonates and children in South Africa. South African Medical Journal, 107(3):192-195, doi:10.7196/SAMJ.2017.v107i3.12035.The original publication is available at http://www.samj.org.zaHealthcare-associated infection (HAI) is a frequent and serious complication affecting 4 - 8% of hospitalised children and neonates in high-income countries. The burden of HAI in South African (SA) paediatric and neonatal wards is substantial but underappreciated, owing to a lack of HAI surveillance and reporting. Maternal and child health and infection prevention are priority areas for healthcare quality improvement in the National Core Standards programme. Despite increasing recognition in SA, infection prevention efforts targeting hospitalised children and neonates are hampered by health system, institutional and individual patient factors. To ensure safe healthcare delivery to children, a co-ordinated HAI prevention strategy should promote development of infection prevention norms and policies, education, patient safety advocacy, healthcare infrastructure, surveillance and research. We present a framework for SA to develop and expand HAI prevention in hospitalised neonates and children.http://www.samj.org.za/index.php/samj/article/view/11817Publisher's versio

CYRI/ Fam49 proteins represent a new class of Rac1 interactors

Fam49 proteins, now referred to as CYRI (CYFIP-related Rac Interactor), are evolutionarily conserved across many phyla. Their closest relative by amino acid sequence is CYFIP, as both proteins contain a domain of unknown function DUF1394. We recently showed that CYRI and the DUF1394 can mediate binding to Rac1 and evidence is building to suggest that CYRI plays important roles in cell migration, chemotaxis and pathogen entry into cells. Here we discuss how CYRI proteins fit into the current framework of the control of actin dynamics by positive and negative feedback loops containing Rac1, the Scar/WAVE Complex, the Arp2/3 Complex and branched actin. We also provide data regarding the interaction between Rac1 and CYRI in an unbiassed mass spectrometry screen for interactors of an active mutant of Rac1

Coupled genomic evolutionary histories as signatures of organismal innovations in cephalopods: co-evolutionary signatures across levels of genome organization may shed light on functional linkage and origin of cephalopod novelties

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ritschard, E. A., Whitelaw, B., Albertin, C. B., Cooke, I. R., Strugnell, J. M., & Simakov, O. Coupled genomic evolutionary histories as signatures of organismal innovations in cephalopods: co-evolutionary signatures across levels of genome organization may shed light on functional linkage and origin of cephalopod novelties. BioEssays, 41, (2019): 1900073, doi: 10.1002/bies.201900073.How genomic innovation translates into organismal organization remains largely unanswered. Possessing the largest invertebrate nervous system, in conjunction with many species‐specific organs, coleoid cephalopods (octopuses, squids, cuttlefishes) provide exciting model systems to investigate how organismal novelties evolve. However, dissecting these processes requires novel approaches that enable deeper interrogation of genome evolution. Here, the existence of specific sets of genomic co‐evolutionary signatures between expanded gene families, genome reorganization, and novel genes is posited. It is reasoned that their co‐evolution has contributed to the complex organization of cephalopod nervous systems and the emergence of ecologically unique organs. In the course of reviewing this field, how the first cephalopod genomic studies have begun to shed light on the molecular underpinnings of morphological novelty is illustrated and their impact on directing future research is described. It is argued that the application and evolutionary profiling of evolutionary signatures from these studies will help identify and dissect the organismal principles of cephalopod innovations. By providing specific examples, the implications of this approach both within and beyond cephalopod biology are discussed.E.A.R. and O.S. are supported by the Austrian Science Fund (Grant No. P30686‐B29). E.A.R. is supported by Stazione Zoologica Anton Dohrn (Naples, Italy) PhD Program. The authors wish to thank Graziano Fiorito (SZN, Italy), Hannah Schmidbaur (University of Vienna, Austria), Thomas Hummel (University of Vienna, Austria) for many insightful comments and reading of the draft manuscript. The authors would like to apologize to all colleagues whose work has been omitted due to space constraints