This paper describes an experimental investigation of the dynamics of a near-blowoff, bluff-body stabilized flame. This work is motivated by a number of prior observations showing that near-blowoff flames exhibit enhanced unsteadiness. Laser sheet imaging studies and particle image velocimetry velocity field measurements show that the transient dynamics of these flames occur in two distinct stages before blowoff. The first stage is manifested by the presence of localized "holes" in the flame sheet, at locations where the instantaneous stretch rate exceeds the extinction stretch rate. During this stage, the overall flame and wake dynamics appear essentially unaltered and, moreover, the flame can persist indefinitely, although with enhanced unsteadiness. As the equivalence ratio is further decreased, the size of the flame region affected and the duration of these events increases monotonically. As the blowoff point is approached further, this leads to the second stage, large-scale alterations of the wake dynamics, violent flapping of the flame front, and even larger straining of the flame. In some cases, the flow in this second stage bears striking resemblance to the asymmetric von Kármán type flowfield.
Unilateral sinonasal pathology are common presentations but are regarded with caution as neoplastic conditions during their early stages may mimic an inflammatory pathology. The aim of the review was to analyse the varied presentations of patients with unilateral nasal mass and to identify features suggestive of neoplastic pathology. A retrospective review of all cases of unilateral nasal mass/polyp from Jan 09 to Jan 10 presenting at a tertiary care hospital were analysed. The patients were grouped as per their histopathological diagnosis as inflammatory and neoplastic. The demographic data, presenting symptoms, radiological and histopathological findings were compared between the two groups. Out of the 53 patients of unilateral nasal mass, 44 (83.1%) had inflammatory conditions and 9 (16.9%) had neoplastic conditions. Benign nasal polyp and inverted papilloma were the commonest inflammatory and neoplastic condition. Neoplastic conditions were significantly commoner in males (P = 0.0315) and in the age group above 50 years (P = 0.0046). Epistaxis and extranasal symptoms like facial pain, dental and orbital complaints were found to be significantly higher in neoplastic conditions. Neoplastic lesions of nose and paranasal sinus are one of the most challenging conditions that otolaryngologists have to diagnose and treat due to their hidden nature and late presentations. In our review neoplastic conditions were found to be higher in elderly male with epistaxis, extranasal symptoms and presence of extensive soft tissue involvement and bony destruction on CT scan. The clinician should have a high index of suspicion to rule out a neoplastic aetiology in all cases of unilateral nasal mass.
Work to develop a practical, fast diagnostic technique to monitor the proximity of a combustor to blowout using measurements of the flame's acoustic signature is described. The feasibility of this approach was demonstrated on three combustors with different flame holding mechanisms that are used in most practical combustion devices: pilot, swirl, and bluff-body stabilized flames. Extensive high-speed flame images were obtained and analyzed in conjunction with simultaneous acoustic data. These analyses revealed changes in the low-frequency spectrum and/or the increased presence of time-localized and intermittent events in the acoustic data as the combustor approached blowout. Based on these observations, spectral, statistical, wavelet, and thresholding signal-processing schemes were developed for detecting blowout precursors with varying levels of time response, sensitivity, and robustness.
We study how visual representations pre-trained on diverse human video data can enable data-efficient learning of downstream robotic manipulation tasks. Concretely, we pre-train a visual representation using the Ego4D human video dataset using a combination of time-contrastive learning, video-language alignment, and an L1 penalty to encourage sparse and compact representations. The resulting representation, R3M, can be used as a frozen perception module for downstream policy learning. Across a suite of 12 simulated robot manipulation tasks, we find that R3M improves task success by over 20% compared to training from scratch and by over 10% compared to state-of-the-art visual representations like CLIP and MoCo. Furthermore, R3M enables a Franka Emika Panda arm to learn a range of manipulation tasks in a real, cluttered apartment given just 20 demonstrations. Code and pre-trained models are available at https://tinyurl.com/robotr3m.
Background:Adductor canal blocks (ACBs) have become a popular technique for postoperative pain control in total knee arthroplasty patients. Proximal and distal ACB have been compared previously, but important postoperative outcomes have yet to be assessed.Aims:The primary objective of this study is to compare postoperative analgesia between proximal and distal ACB. Secondary outcomes include functional mobility, length of stay (LOS), and adverse events.Settings and Design:This study was a single-center, assessor-blinded, randomized trial.Subjects and Methods:Fifty-seven patients were randomly assigned to receive a proximal (n = 28) or distal (n = 29) ACB. A 20 mL bolus of 5 mg/mL ropivacaine was injected at the respective location followed by 2.0 mg/mL ropivacaine infusion for 24 h.Statistical Analysis:The primary outcome was intra- and postoperative 24-h opioid consumption in intravenous (IV) morphine equivalents. Secondary outcomes include percentage change in timed “Up and Go” (TUG) times, LOS, and average postoperative pain scores. Continuous variables were compared using Student's t-test.Results:The mean (±standard deviation) 24-h intra-and postoperative opioid consumption showed no difference between the proximal and distal groups (39.72 ± 23.6 and 41.28 ± 19.6 mg IV morphine equivalents, respectively, P = 0.793). There was also no significant difference in the median [minimum, maximum] percentage change in TUG times relative to preoperative performance comparing proximal and distal ACB (334.0 [131, 1084] %-change and 458.5 [169, 1696] %-change, respectively, P = 0.130). In addition, there were no differences in postoperative pain scores or LOS.Conclusions:ACB performed at either proximal or distal locations shows no difference in postoperative pain measured by opioid consumption or pain scores. Better TUG performance seen in the proximal group was not statistically significant but might represent a clinically important difference in functional mobility.
Tracheal stenosis (TS), a challenging problem, is a known complication of prolonged intubation and tracheostomy. The management involves a multidisciplinary approach with multiple complex procedures. In this study we discuss our experience with severe TS with regards to patient characteristics, cause and management. A retrospective analysis of 20 patients of severe TS treated at a tertiary care centre was evaluated. Inclusion criteria were all patients with severe TS who required surgical intervention. Exclusion criteria were patients with associated laryngeal stenosis and TS due to cancer. Demographic data was recorded and findings relating to aetiology, characteristics of stenosis and the various aspects of therapeutic procedures performed are discussed with review of literature. Descriptive analysis of data were performed SPSS 18. Results of the 20 patients, 17 patients (85 %) developed TS post tracheostomy, or post intubation and subsequent tracheostomy. 13 Patients (65 %) had true stenosis of which 7 patients (35 %) had simple web or circumferential fibrosis and 6 patients (30 %) had complex stenosis. Seven patients (35 %) had granulations causing severe TS which were mostly suprastomal (5 patients), stomal (5 patients) and combined stomal and suprastomal (3 patients). The average length of stenosis was 3.57 cm (0.5-8 cm). Montgomery t tube insertion was a common procedure in 18 patients (90 %) pre or post intervention. Each patient underwent an average of 3.4 procedures during their course of treatment which included rigid bronchoscopy and mechanical debulking, Nd YAG laser, KTP laser, balloon dilatation and use of stents. Among the 7 patients with granulations 100 % successful decanulation was noted with endoscopic management whereas in 13 patients with true stenosis, 10 patients (76.9 %) required open surgical management (8 tracheal resection and anastomosis and 2 tracheoplasty) with 80 % successful decanulation, 2 patients (15.4 %) were treated with endoscopy with 100 % successful decanulation and 1 patient (7.7 %) was a non surgical candidate on stent. Of the total 20 patients with severe TS in this series, 17 (85 %) of patients who were decanulated, asymptomatic on routine daily activities with normal FFB were considered cured. TS is a challenging condition requiring a highly skilled multidisciplinary team for adequate management. Prolonged intubation and tracheostomy are the common causes leading to tracheal stenosis. Simple tracheal stenosis is easier to manage than a complex stenosis which usually requires an open surgical procedure for successful management. Presence of conditions like tracheoesophageal fistula and long segment tracheomalacia are poor factors for successful management. In our cases successful decanulation was possible in 85 % of the patients following a systematic multidisciplinary approach.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.