Absence Of Wakes Research Articles

A National Survey on Coma Epidemiology, Evaluation, and Therapy in India: Revisiting the Curing Coma Campaign Come Together Survey.

The limited representation from developing countries in the original COME TOGETHER survey gave us an impetus to conduct this survey in the Indian subcontinent. This cross-sectional online survey was conducted from August through September 2022. Participants were health care physicians caring for patients with coma and disorders of consciousness. Fischer's exact test or the Mann-Whitney U-test was used to compare respondents who agreed or disagreed with the preestablished coma definition. Fleiss κ values were calculated to assess agreement among respondents. A p value less than 0.05 was considered statistically significant. The survey was completed by 130 physicians. We found substantial interrater agreement on absence of wakefulness (71.54%; κ = 0.71), Glasgow Coma Score ≤ 8 (78.46%; κ = 0.78), and failure to respond purposefully to visual, verbal, or tactile stimuli (66.15%; κ = 0.66). Reported common etiologies of coma included traumatic brain injury (50.76%), ischemic stroke (30%), and intracerebral hemorrhage (29.23%). The most common clinical assessment tools used for coma included the Glasgow Coma Score (92.3%) and neurological examination (60.8%). Neurological examination was the most commondiagnostic tool used(100%), followed by magnetic resonance imaging (89.2%), basic laboratory studies (88.5%), and head computed tomography/angiography (86.9%). Pharmacological interventions used to stimulate arousal in patients with coma were sedation vacation (91.5%), electrolyte/endocrine correction (65.4%), osmotic therapy with mannitol (60%), hypertonic saline (54.6%), modafinil (46.9%), and antidote for drugs (45.4%). Among the nonpharmacological interventions, sensory stimulation (57.7%) was the most commonly used modality. The most common discharge disposition for comatose patients who survived hospitalization were home with or without services (70.0%). Differences from the global survey were noted regarding the following: traumatic brain injury being the most common etiology of coma in India, more frequent practice of sedation interruption, less frequent use of electroencephalography in India, rare use of pharmacological neurostimulants, and home being the most common discharge disposition in India.

The Curing Coma Campaign International Survey on Coma Epidemiology, Evaluation, and Therapy (COME TOGETHER)

BackgroundAlthough coma is commonly encountered in critical care, worldwide variability exists in diagnosis and management practices. We aimed to assess variability in coma definitions, etiologies, treatment strategies, and attitudes toward prognosis.MethodsAs part of the Neurocritical Care Society Curing Coma Campaign, between September 2020 and January 2021, we conducted an anonymous, international, cross-sectional global survey of health care professionals caring for patients with coma and disorders of consciousness in the acute, subacute, or chronic setting. Survey responses were solicited by sequential emails distributed by international neuroscience societies and social media. Fleiss κ values were calculated to assess agreement among respondents.ResultsThe survey was completed by 258 health care professionals from 41 countries. Respondents predominantly were physicians (n = 213, 83%), were from the United States (n = 141, 55%), and represented academic centers (n = 231, 90%). Among eight predefined items, respondents identified the following cardinal features, in various combinations, that must be present to define coma: absence of wakefulness (81%, κ = 0.764); Glasgow Coma Score (GCS) ≤ 8 (64%, κ = 0.588); failure to respond purposefully to visual, verbal, or tactile stimuli (60%, κ = 0.552); and inability to follow commands (58%, κ = 0.529). Reported etiologies of coma encountered included medically induced coma (24%), traumatic brain injury (24%), intracerebral hemorrhage (21%), and cardiac arrest/hypoxic-ischemic encephalopathy (11%). The most common clinical assessment tools used for coma included the GCS (94%) and neurological examination (78%). Sixty-six percent of respondents routinely performed sedation interruption, in the absence of contraindications, for clinical coma assessments in the intensive care unit. Advanced neurological assessment techniques in comatose patients included quantitative electroencephalography (EEG)/connectivity analysis (16%), functional magnetic resonance imaging (7%), single-photon emission computerized tomography (6%), positron emission tomography (4%), invasive EEG (4%), and cerebral microdialysis (4%). The most commonly used neurostimulants included amantadine (51%), modafinil (37%), and methylphenidate (28%). The leading determinants for prognostication included etiology of coma, neurological examination findings, and neuroimaging. Fewer than 20% of respondents reported routine follow-up of coma survivors after hospital discharge; however, 86% indicated interest in future research initiatives that include postdischarge outcomes at six (85%) and 12 months (65%).ConclusionsThere is wide heterogeneity among health care professionals regarding the clinical definition of coma and limited routine use of advanced coma assessment techniques in acute care settings. Coma management practices vary across sites, and mechanisms for coordinated and sustained follow-up after acute treatment are inconsistent. There is an urgent need for the development of evidence-based guidelines and a collaborative, coordinated approach to advance both the science and the practice of coma management globally.

Effects of Yoga on Sleep Quality, Depression, Anxiety, Stress, and Blood Glucose Levels Among Tertiary Students

Sleep is defined as an easily reversible periodic state marked by the absence of wakefulness. Studies have shown that university students tend to have a diminished amount of sleep. This would lead to the loss of concentration, daytime sleepiness, and reduced academic performances. The aim of this study was to investigate the effects of yoga on overall sleep quality, depression, anxiety, stress, and blood glucose levels. A total of 88 participants with 44 students in each group, control and experimental, were recruited from Universiti Tunku Abdul Rahman based on the outcome of the Godin Shephard questionnaire. A total score of less than 14 was considered mild hence falling into the control group while above 14 and had practiced yoga for a minimum of 6 weeks were placed in the experimental group. The participants were required to self-administer a set of questionnaires consisting of socio-demographic information, the Pittsburgh Sleep Quality Index (PSQI) questionnaire and Depression, Anxiety, Stress Scores. Three components of sleep, namely the habitual sleep efficiency, sleep disturbances, and daytime dysfunctions, were better in the experimental group compared to the control one. Depression, anxiety, stress, and blood glucose levels also appeared to be more desirable in the experimental group with yoga students. It was found that blood glucose levels were positively correlated to the Global PSQI score, depression, anxiety, and stress measures in this study. In conclusion, yoga-practicing students have healthier sleep patterns, negative emotional states, and blood glucose levels. In order to obtain more conclusive findings, similar studies should be carried out in different universities with larger sample size and for longer periods.

Unsteady experimental and numerical investigation of aerodynamic performance in ultra-high-lift LPT

Detailed experimental and numerical investigations were performed for an ultra-high-lift front-loaded low-pressure turbine cascade (Zw = 1.58) with periodic wakes. The interaction mechanisms between the incoming wakes and endwall secondary flow were carefully examined. Wakes were produced by moving upstream rods, and flow field downstream of the cascade was measured using a seven-hole probe. Experimental results revealed that incoming wakes influenced not only the boundary layer development of the blade suction surface but also the complex endwall secondary vortex structures. On the suction surface: Incoming wakes clearly suppressed the suction side separation bubble at a low Reynolds number of 25000. Nevertheless, the effects of different wake passing frequencies were not significantly different at Re = 100000, and the profile losses under wake passing were even greater than in the absence of wakes. At the endwalls: Incoming wakes more strongly suppressed secondary flow at Re = 100000 than at Re = 25000, because the low-momentum fluid inside the incoming wakes clearly increased the endwall cross-passage pressure gradient at Re = 25000. The experimental results indicated that periodic wakes decreased the passage vortex and counter vortex core strength by 25% and 30%, respectively, at Re = 100000. Instantaneous results also demonstrated that endwall secondary vortices decreased significantly near the position of wakes passing.

Unsteady wakes-secondary flow interactions in a high-lift low-pressure turbine cascade

Detailed experimental measurements were conducted to study the interactions between incoming wakes and endwall secondary flow in a high-lift Low-Pressure Turbine (LPT) cascade. All of the measurements were conducted in both the presence and absence of incoming wakes, and numerical analysis was performed to elucidate the flow mechanism. With increasing Reynolds number, the influence of the incoming wakes on suppressing the secondary flow gradually increased owing to the greater influence of incoming wakes on reducing the negative incidence angle at higher Reynolds numbers, leading to a lower blade loading near the leading edge and suppression of the Pressure Side (PS) leg of the horseshoe vortex. However, the effect of unsteady wakes on suppressing the profile losses gradually became weaker owing to the reduced size of the Suction Side (SS) separation bubble and increased mixing loss in the free-flow region at high Reynolds numbers. Incoming wakes clearly improved the aerodynamic performance of the low-pressure turbine cascade at low Reynolds numbers of 25,000 and 50,000. In contrast, at the high Reynolds number of 100,000, the profile loss at the midspan and mass-averaged total losses downstream of the cascade were higher in the presence of wakes than in the absence of wakes, and the unsteady wakes exerted a negative influence on the aerodynamic performance of the LPT cascade.

Influence of topography and wakes on wind turbulence: measurements and interpretation of results

ABSTRACTIn order to perform detailed calculations of dynamic loads on wind turbines due to turbulence, a precise wind simulator is needed. International standards give guidelines to generate a synthetic wind for a flat terrain in the absence of wakes. Measurements in complex terrain and under wake effects have been analysed with the purpose of establishing some modifications to those guidelines that improve the simulated wind turbulence characteristics. A modification of the spectrum shape is proposed for locations affected by wind turbine wakes. Modifications are also proposed for the ratios of standard deviations and the turbulence lengths, which give a tendency to turbulence isotropy, as the complexity of the terrain and wake effects become more relevant. The parameter called normalized turbulence intensity (NTI) is introduced to quantify the ‘complexity’ of a location. Copyright © 2011 John Wiley & Sons, Ltd.

The Effect of Leading-Edge Geometry on Wake Interactions in Compressors

The effect of leading-edge geometry on the wake/boundary-layer interaction was studied in a low-speed single-stage HP compressor. Both a 3:1 elliptic and a circular leading edge were tested on a controlled diffusion aerofoil stator blade. Experiments were undertaken on the stator suction surface; these included hotwire boundary-layer traverses, surface hotfilm measurements, and high resolution leading-edge pressure measurements. Steady computational fluid dynamics (CFD) predictions were also performed to aid the interpretation of the results. The two leading-edge shapes gave rise to significantly different flows. For a blade with an elliptic leading edge (Blade A), the leading-edge boundary layer remained attached and laminar in the absence of wakes. The wake presence led to the formation of a thickened laminar boundary layer in which turbulent disturbances were observed to form. Measurements of the trailing-edge boundary layer indicated that the wake/leading-edge interaction for Blade A raised the suction-surface loss by 20%. For a blade with a circular leading edge (Blade B), the leading-edge boundary-layer exhibited a separation bubble, which was observed to reattach laminar in the absence of wakes. The presence of the wake moved the separation position forward while inducing a turbulent reattachment upstream of the leading-edge time-average reattachment position. This produced a region of very high momentum thickness at the leading edge. The suction-surface loss was found to be 38% higher for Blade B than for Blade A. Wake traverses downstream of the blades were used to determine the total profile loss of each blade. The profile loss of Blade B was measured to be 32% higher than that of Blade A.

Absence of wake in faint television meteors

Absence of wake in faint television meteors

Ship wake-detection procedure using conjugate gradient trained artificial neural networks

A method has been developed to reduce large two-dimensional images to significantly smaller feature lists. These feature lists overcome the problem of storing and manipulating large amounts of data. A new artificial neural network using conjugate gradient training methods, operating on sets of feature lists, was successfully trained to determine the presence or absence of wakes in synthetic aperture radar images. A comparison has been made between the different conjugate gradient and steepest-descent training methods and has demonstrated the superiority of the former over the latter. >

Steady Fluid Flow in a Radial Vaneless Diffuser

The performance of a centrifugal pump or compressor system has often been investigated on an overall basis for a wide range of operations and these investigations have, in the past, resulted in some remarkable technical advances. Detailed and penetrating studies of both the rotor and the components up and downstream are essential to obtain a knowledge of the critical areas and to increase further the efficiency of the system. In this study one problem area, the flow in radial diffusers in the absence of unsteady flow, is isolated and an extensive analytical and experimental study concerning this has been undertaken. In the absence of wakes from the impeller or other unsteady flow phenomena, the formation of a boundary layer on the side walls of the diffuser is the main cause of a loss in diffuser efficiency. The boundary layers which are three dimensional in character are investigated for several inlet conditions, and the theoretical results are compared with those of the experiments; the agreement is good. The analysis is extended for a three-dimensional compressible boundary layer.