On the evolution of flow topology in turbulent Rayleigh-Bénard convection

Copyright 2016 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.Small-scale dynamics is the spirit of turbulence physics. It implicates many attributes of flow topology evolution, coherent structures, hairpin vorticity dynamics, and mechanism of the kinetic energy cascade. In this work, several dynamical aspects of the small-scale motions have been numerically studied in a framework of Rayleigh-Benard convection (RBC). To do so, direct numerical simulations have been carried out at two Rayleigh numbers Ra = 10(8) and 10(10), inside an air-filled rectangular cell of aspect ratio unity and pi span-wise open-ended distance. As a main feature, the average rate of the invariants of the velocity gradient tensor (Q(G), R-G) has displayed the so-calledPeer ReviewedPostprint (author's final draft

New subgrid-scale models for large-eddy simulation of Rayleigh-Bénard convection

Published under licence in Journal of Physics: Conference Series by IOP Publishing Ltd. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.At the crossroad between flow topology analysis and the theory of turbulence, a new eddy-viscosity model for Large-eddy simulation has been recently proposed by Trias et al.[PoF, 27, 065103 (2015)]. The S3PQR-model has the proper cubic near-wall behaviour and no intrinsic limitations for statistically inhomogeneous flows. In this work, the new model has been tested for an air turbulent Rayleigh-Benard convection in a rectangular cell of aspect ratio unity and n span-wise open-ended distance. To do so, direct numerical simulation has been carried out at two Rayleigh numbers Ra = 108 and 1010, to assess the model performance and investigate a priori the effect of the turbulent Prandtl number. Using an approximate formula based on the Taylor series expansion, the turbulent Prandtl number has been calculated and revealed a constant and Ra-independent value across the bulk region equals to 0.55. It is found that the turbulent components of eddy-viscosity and eddy-diffusivity are positively prevalent to maintain a turbulent wind essentially driven by the mean buoyant force at the sidewalls. On the other hand, the new eddy-viscosity model is preliminary tested for the case of Ra = 108 and showed overestimation of heat flux within the boundary layer but fairly good prediction of turbulent kinetics at this moderate turbulent flow.Peer ReviewedPostprint (published version

A study of the efficacy of furosemide as a prophylaxis of acute renal failure in coronary artery bypass grafting patients: A clinical trial

BACKGROUND: Renal failure is a frequent event after coronary artery bypass grafting (CABG). Hemodynamic alterations during surgery as well as the underlying disease are the predisposing factors. We aimed to study intermittent furosemide therapy in the prevention of renal failure in patients undergoing CABG. METHODS: In a single-blind randomized controlled trial, 123 elective CABG patients, 18-75 years, entered the study. Clearance of creatinine, urea and water were measured. Patients were randomly assigned into three groups: furosemide in prime (0.3-0.4 mg/kg); intermittent furosemide during CABG (0.2 mg/kg, if there was a decrease in urinary excretion) and control (no furosemide). RESULTS: There was a significant change in serum urea, sodium and fluid balance in �intermittent furosemide� group; other variables did not change significantly before or after the operation. Post-operative fluid balance was significantly higher in �intermittent furosemide� group (2573 ± 205 ml) compared to control (1574 ± 155 ml) (P < 0.010); also, fluid balance was higher in �intermittent furosemide� group (2573 ± 205 ml) compared to �furosemide in prime� group (1935 ± 169 ml) (P < 0.010). CONCLUSION: The study demonstrated no benefit from intermittent furosemide in elective CABG compared to furosemide in prime volume or even placebo. © 2015, Isfahan University of Medical Sciences(IUMS). All rights reserved

A priori study of subgrid-scale features in turbulent Rayleigh-Bénard convection

At the crossroad between flow topology analysis and turbulence modeling, a priori studies are a reliable tool to understand the underlying physics of the subgrid-scale (SGS) motions in turbulent flows. In this paper, properties of the SGS features in the framework of a large-eddy simulation are studied for a turbulent Rayleigh-Bénard convection (RBC). To do so, data from direct numerical simulation (DNS) of a turbulent air-filled RBC in a rectangular cavity of aspect ratio unity and p spanwise open-ended distance are used at two Rayleigh numbers Ra € (108, 1010) [Dabbagh et al.,Peer ReviewedPostprint (author's final draft

Mechanical Circulatory Support in High-Risk Percutaneous Coronary Intervention

The use of mechanical circulatory devices to support high-risk elective percutaneous coronary intervention (PCI) has become more common as the group of patients considered inoperable or high risk for surgical revascularization has grown. Most of the data examining outcomes in high-risk PCI are observational and retrospective. Limited prospective randomized studies have been unable to show improved clinical outcomes with routine mechanical circulatory support (MCS) in patients with a high burden of coronary artery disease and reduced ejection fraction. The role for MCS in high-risk PCI continues to evolve as understanding of the appropriate groups for this therapy evolves

Deep learning-enabled technologies for bioimage analysis.

Deep learning (DL) is a subfield of machine learning (ML), which has recently demonstrated its potency to significantly improve the quantification and classification workflows in biomedical and clinical applications. Among the end applications profoundly benefitting from DL, cellular morphology quantification is one of the pioneers. Here, we first briefly explain fundamental concepts in DL and then we review some of the emerging DL-enabled applications in cell morphology quantification in the fields of embryology, point-of-care ovulation testing, as a predictive tool for fetal heart pregnancy, cancer diagnostics via classification of cancer histology images, autosomal polycystic kidney disease, and chronic kidney diseases

Effect of vaginal misoprostol on cervical priming in diagnostic dilatation and curettage

Introduction:Dilatation of cervix is essential for dilatation and curettage and hysteroscopy as well. Complications encountered during the procedure are partly related to difficulties in cervical dilatation. Finding the materials which can cause cervical dilatation more easily is important. The purpose of the present study is to evaluate the effect of vaginal Misoprostol on priming the cervix before dilatation in patients who are candidate for this procedure. Methods: A randomized clinical trial was performed on 60 women who were candidated for D&C. In 30 patients (case group), 200 mg Misoprostol (one tablet) was administered in posterior fornix of vagina 4 hours before operation, whereas in other 30 patients (control group), placebo was used. Then the two groups were compared according to their need to Hagar dilatator thinner than number 5 for dilatation of cervix and the duration of dilatation and curettage. Results: It was revealed that measures like age, parity and previous delivery methods did not show a statistically significant difference between two groups. 6 patients (20), in the case group, and 26 (87) in the control group needed the Hager dilatator number 5 to dilate the cervix (P<0.005) which their difference was statistically significant. The mean duration of D&C in the control group was 19±4 minute versus 12.7±2.8 minute in case group which showed a statistically significant difference (P<0.001). Conclusion: Vaginal misoprostol is a suitable agent for priming the cervix in order to dilate more easily before D&C

Air conditioning systems and nosocomial infections in Mosul hospitals

Background: Nosocomial infections (NIs) have proven to be persistent and sometimes complicated problem. More than one third of all nosocomial infections possibly involve airborne transmission. The aim of this study is to estimate the types of bacteria that could be present in air-conditioning systems of some hospitals and their antibiotic sensitivity profile. Materials and methods: Swab samples were taken from air-conditioning system filters and rendered for bacterial identification and evaluation of their antibiotic susceptibility. Results: The results showed twenty isolates from three different hospitals. Ibn Sina showed ١٦ isolates (٥ S. aureus; ٣ S. epidermidis; ٤ S. saprophyticus; ١ E. coli; ١ Proteus mirabilis; ١ Klebsiella pneumoniae and ١ Pseudomonas aeruginosa), Ibn Al- Atheer hospital showed only ٢ isolates (١ S.aureus, and ١ Streptococcus) and Al- Jumhori hospital showed only ٢ isolates (١ S. aureus, and ١ S. saprophyticus); most of this isolates are resistant to the antibiotics used in this study. Conclusion: there are a risky bacteria located in air conditioners especially indoor conventional systems more than the hospital designed systems and still both represent a susceptible source for nosocomial infection

Synthesis of new metronidazole derivatives with suspected antimicrobial activity

Metronidazole has a bactericidal effect against many anaerobic gram positive and gram negative bacteria, but has no activity against aerobic bacteria. Metronidazole activity is mostly contributed to its reduced form that produced from anaerobic reduction inside the micro-organisms. In this research, the reduced form of metronidazole was synthesized and termed compound ( I ) which diazonated to form a diazonium interme-diate, this intermediate coupled with two phenolic compounds to give compounds ( II ) and ( III ) which are azo derivatives. The structures of these compounds were identified by physical and spectroscopic ( U.V. and FTIR ) techniques. The antibacterial activity of the synthesized compounds were examined against two aerobic gram positive bacteria ( Staphylococcus aureus, Streptococcus pneumoniae ); two aerobic gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli ) and one anaerobic gram positive bacteria ( Clostridium Perfringens ) by using two techniques: dilution and disc diffusion methods. Opposite to our expectance, these products showed no antibacterial activity against the tested bacteria at the concentrations use

Cardiac Tamponade Secondary to COVID-19

A 67-year-old female presented with upper respiratory symptoms and was diagnosed with COVID-19. She was found to have a large hemorrhagic pericardial effusion with echocardiographic signs of tamponade and mild left ventricular impairment. Clinical course was complicated by development of Takotsubo cardiomyopathy. She was treated with pericardiocentesis, colchicine, corticosteroids and hydroxychloroquine with improvement in symptoms