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Turbulence

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https://www.readbyqxmd.com/read/28527541/impact-of-chemoradiation-after-supra-or-infrahyoid-cancer-on-aerodynamic-subjective-and-objective-voice-assessments-a-multicenter-prospective-study
#1
Jérôme R Lechien, Mohamad Khalife, Kathy Huet, Anne-Francoise Fourneau, Véronique Delvaux, Myriam Piccaluga, Bernard Harmegnies, Sven Saussez
OBJECTIVES: The study aimed to investigate the impact of chemoradiotherapy (CRT) on speech and voice quality according to the anatomic localization of the head and neck cancer. METHODS: Thirty-four patients treated by CRT for advanced suprahyoid (N = 17) or infrahyoid (N = 17) cancer were assessed for speech function, videolaryngostroboscopy, Voice Handicap Index, blinded Grade, Roughness, Breathiness, Asthenia, Strain, and Instability, acoustic measurements, and aerodynamic measurements...
May 17, 2017: Journal of Voice: Official Journal of the Voice Foundation
https://www.readbyqxmd.com/read/28524687/observation-of-oscillatory-radial-electric-field-relaxation-in-a-helical-plasma
#2
J A Alonso, E Sánchez, I Calvo, J L Velasco, K J McCarthy, A Chmyga, L G Eliseev, T Estrada, R Kleiber, L I Krupnik, A V Melnikov, P Monreal, F I Parra, S Perfilov, A I Zhezhera
Measurements of the relaxation of a zonal electrostatic potential perturbation in a nonaxisymmetric magnetically confined plasma are presented. A sudden perturbation of the plasma equilibrium is induced by the injection of a cryogenic hydrogen pellet in the TJ-II stellarator, which is observed to be followed by a damped oscillation in the electrostatic potential. The waveform of the relaxation is consistent with theoretical calculations of zonal potential relaxation in a nonaxisymmetric magnetic geometry. The turbulent transport properties of a magnetic confinement configuration are expected to depend on the features of the collisionless damping of zonal flows, of which the present Letter is the first direct observation...
May 5, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28523173/thrombotic-responses-to-coronary-stents-bioresorbable-scaffolds-and-the-kounis-hypersensitivity-associated-acute-thrombotic-syndrome
#3
REVIEW
Nicholas G Kounis, Ioanna Koniari, Anastasios Roumeliotis, Grigorios Tsigas, George Soufras, Nicholas Grapsas, Periklis Davlouros, George Hahalis
Percutaneous transluminal coronary angioplasty with coronary stent implantation is a life-saving medical procedure that has become, nowadays, the most frequent performed therapeutic procedure in medicine. Plain balloon angioplasty, bare metal stents, first and second generation drug-eluting stents, bioresorbable and bioabsorbable scaffolds have offered diachronically a great advance against coronary artery disease and have enriched our medical armamentarium. Stented areas constitute vulnerable sites for endothelial damage, endothelial dysfunction, flow turbulence, hemorheologic changes, platelet dysfunction, coagulation changes and fibrinolytic disturbances...
April 2017: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28521045/effects-of-ambient-temperature-and-water-vapor-on-chamber-pressure-and-oxygen-level-during-low-atmospheric-pressure-stunning-of-poultry
#4
Paul H Holloway, David G Pritchard
The characteristics of the vacuum used in a low atmospheric pressure stunning system to stun (render unconscious) poultry prior to slaughter are described. A vacuum chamber is pumped by a wet screw compressor. The vacuum pressure is reduced from ambient atmospheric pressure to an absolute vacuum pressure of ∼250 Torr (∼33 kPa) in ∼67 sec with the vacuum gate valve fully open. At ∼250 Torr, the sliding gate valve is partially closed to reduce effective pumping speed, resulting in a slower rate of decreasing pressure...
May 17, 2017: Poultry Science
https://www.readbyqxmd.com/read/28516905/the-effects-of-forest-canopy-shading-and-turbulence-on-boundary-layer-ozone
#5
P A Makar, R M Staebler, A Akingunola, J Zhang, C McLinden, S K Kharol, B Pabla, P Cheung, Q Zheng
The chemistry of the Earth's atmosphere close to the surface is known to be strongly influenced by vegetation. However, two critical aspects of the forest environment have been neglected in the description of the large-scale influence of forests on air pollution: the reduction of photolysis reaction rates and the modification of vertical transport due to the presence of foliage. Here we show that foliage shading and foliage-modified vertical diffusion have a profound influence on atmospheric chemistry, both at the Earth's surface and extending throughout the atmospheric boundary layer...
May 18, 2017: Nature Communications
https://www.readbyqxmd.com/read/28516093/iatrogenic-supravalvular-aortic-stenosis
#6
Paolo Bosco, Antonella Ferrara, Samer A M Nashef
We describe a case of hemolytic anemia and proximal anastomotic site stenosis following emergency repair of a Type A aortic dissection. This rare complication led to a reoperation to correct the iatrogenic aortic stenosis and cure the consequent hemolysis. A "sandwich" technique (with two Teflon strips on the outside and inside of the aortic wall) was used in the initial repair to reinforce the suture line and prevent bleeding from the aortic anastomoses. At the time of reoperation, the inner Teflon strip at the proximal aortic anastomosis was found to have inverted into the aortic lumen, as suggested by the preoperative magnetic resonance imaging...
October 2016: Aorta (Stamford, Conn.)
https://www.readbyqxmd.com/read/28515537/estimating-spatially-distributed-turbulent-heat-fluxes-from-high-resolution-thermal-imagery-acquired-with-a-uav-system
#7
Claire Brenner, Christina Elisabeth Thiem, Hans-Dieter Wizemann, Matthias Bernhardt, Karsten Schulz
In this study, high-resolution thermal imagery acquired with a small unmanned aerial vehicle (UAV) is used to map evapotranspiration (ET) at a grassland site in Luxembourg. The land surface temperature (LST) information from the thermal imagery is the key input to a one-source and two-source energy balance model. While the one-source model treats the surface as a single uniform layer, the two-source model partitions the surface temperature and fluxes into soil and vegetation components. It thus explicitly accounts for the different contributions of both components to surface temperature as well as turbulent flux exchange with the atmosphere...
May 19, 2017: International Journal of Remote Sensing
https://www.readbyqxmd.com/read/28512709/influence-of-low-temperature-combustion-and-dimethyl-ether-diesel-blends-on-performance-combustion-and-emission-characteristics-of-common-rail-diesel-engine-a-cfd-study
#8
Venkatesh Tavareppa Lamani, Ajay Kumar Yadav, Kumar Gottekere Narayanappa
Due to presence of more oxygen, absence of carbon-carbon (C-C) bond in chemical structure, and high cetane number of dimethyl ether (DME), pollution from DME operated engine is less compared to diesel engine. Hence, the DME can be a promising alternative fuel for diesel engine. The present study emphasizes the effect of various exhaust gas recirculation (EGR) rates (0-20%) and DME/Diesel blends (0-20%) on combustion characteristics and exhaust emissions of common rail direct injection (CRDI) engine using three-dimensional computational fluid dynamics (CFD) simulation...
May 16, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28509711/trends-in-governance-structure-and-activities-among-not-for-profit-u-s-hospitals-2009-2015
#9
Olena Mazurenko, Taleah Collum, Nir Menachemi
BACKGROUND: In U.S. hospitals, boards of directors (BODs) have numerous governance responsibilities including overseeing hospital activities and guiding strategic decisions. BODs can help hospitals adapt to changes in their markets including those stemming from a shift from fee-for-service to value-based purchasing. The recent increase in market turbulence for hospitals has brought renewed attention to the work of BODs. PURPOSE: The aim of the study was to examine trends in hospital BOD structure and activities and determine whether these changes are commensurate with approaches designed to respond to market pressures...
May 15, 2017: Health Care Management Review
https://www.readbyqxmd.com/read/28508858/onset-of-meso-scale-turbulence-in-active-nematics
#10
Amin Doostmohammadi, Tyler N Shendruk, Kristian Thijssen, Julia M Yeomans
Meso-scale turbulence is an innate phenomenon, distinct from inertial turbulence, that spontaneously occurs at low Reynolds number in fluidized biological systems. This spatiotemporal disordered flow radically changes nutrient and molecular transport in living fluids and can strongly affect the collective behaviour in prominent biological processes, including biofilm formation, morphogenesis and cancer invasion. Despite its crucial role in such physiological processes, understanding meso-scale turbulence and any relation to classical inertial turbulence remains obscure...
May 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/28507125/effective-control-of-complex-turbulent-dynamical-systems-through-statistical-functionals
#11
Andrew J Majda, Di Qi
Turbulent dynamical systems characterized by both a high-dimensional phase space and a large number of instabilities are ubiquitous among complex systems in science and engineering, including climate, material, and neural science. Control of these complex systems is a grand challenge, for example, in mitigating the effects of climate change or safe design of technology with fully developed shear turbulence. Control of flows in the transition to turbulence, where there is a small dimension of instabilities about a basic mean state, is an important and successful discipline...
May 15, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28505869/instability-onset-and-scaling-laws-of-an-auto-oscillating-turbulent-flow-in-a-complex-plasma
#12
M Schwabe, S Zhdanov, C Räth
We study a complex plasma under microgravity conditions that is first stabilized with an oscillating electric field. Once the stabilization is stopped, the so-called heartbeat instability develops. We study how the kinetic energy spectrum changes during and after the onset of the instability and compare with the double cascade predicted by Kraichnan and Leith for two-dimensional turbulence. The onset of the instability manifests clearly in the ratio of the reduced rates of cascade of energy and enstrophy and in the power-law exponents of the energy spectra...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505864/optimal-subgrid-scheme-for-shell-models-of-turbulence
#13
Luca Biferale, Alexei A Mailybaev, Giorgio Parisi
We discuss a theoretical framework to define an optimal subgrid closure for shell models of turbulence. The closure is based on the ansatz that consecutive shell multipliers are short-range correlated, following the third hypothesis of Kolmogorov formulated for similar quantities for the original three-dimensional Navier-Stokes turbulence. We also propose a series of systematic approximations to the optimal model by assuming different degrees of correlations across scales among amplitudes and phases of consecutive multipliers...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505830/modeling-and-statistical-analysis-of-non-gaussian-random-fields-with-heavy-tailed-distributions
#14
Mohsen Ghasemi Nezhadhaghighi, Abbas Nakhlband
In this paper, we investigate and develop an alternative approach to the numerical analysis and characterization of random fluctuations with the heavy-tailed probability distribution function (PDF), such as turbulent heat flow and solar flare fluctuations. We identify the heavy-tailed random fluctuations based on the scaling properties of the tail exponent of the PDF, power-law growth of qth order correlation function, and the self-similar properties of the contour lines in two-dimensional random fields. Moreover, this work leads to a substitution for the fractional Edwards-Wilkinson (EW) equation that works in the presence of μ-stable Lévy noise...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505811/chaotic-lagrangian-models-for-turbulent-relative-dispersion
#15
Guglielmo Lacorata, Angelo Vulpiani
A deterministic multiscale dynamical system is introduced and discussed as a prototype model for relative dispersion in stationary, homogeneous, and isotropic turbulence. Unlike stochastic diffusion models, here trajectory transport and mixing properties are entirely controlled by Lagrangian chaos. The anomalous "sweeping effect," a known drawback common to kinematic simulations, is removed through the use of quasi-Lagrangian coordinates. Lagrangian dispersion statistics of the model are accurately analyzed by computing the finite-scale Lyapunov exponent (FSLE), which is the optimal measure of the scaling properties of dispersion...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505752/surface-switching-statistics-of-rotating-fluid-disk-rim-gap-effects
#16
Yuji Tasaka, Makoto Iima
We examined the influence of internal noise on the irregular switching of the shape of the free surface of fluids in an open cylindrical vessel driven by a bottom disk rotating at constant speed [Suzuki, Iima, and Hayase, Phys. Fluids 18, 101701 (2006)PHFLE61070-663110.1063/1.2359740]. A slight increase in the disk-rim gap (less than 3% of the disk radius) was established experimentally to cause significant changes in this system, specifically, frequent appearance of the surface descending event connecting a nonaxisymmetric shape in strong mixing flow (turbulent flow) and an axisymmetric shape in laminar flow, as well as a shift in critical Reynolds number that define the characteristic states...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28500335/nutrient-consumption-and-chain-tuning-in-diatoms-exposed-to-storm-like-turbulence
#17
Gianluca Dell'Aquila, Maria I Ferrante, Marco Gherardi, Marco Cosentino Lagomarsino, Maurizio Ribera d'Alcalà, Daniele Iudicone, Alberto Amato
Current information on the response of phytoplankton to turbulence is linked to cell size and nutrient availability. Diatoms are considered to be favored by mixing as dissolved nutrients are more easily accessible for non-motile cells. We investigated how diatoms exploit microscale turbulence under nutrient repletion and depletion conditions. Here, we show that the chain-forming diatom Chaetoceros decipiens, continues to take up phosphorus and carbon even when silicon is depleted during turbulence. Our findings indicate that upon silica depletion, during turbulence, chain spectra of C...
May 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28499161/determination-of-the-henry-s-law-constants-of-low-volatility-compounds-via-the-measured-air-phase-transfer-coefficients
#18
Huan-Ping Chao, Jiunn-Fwu Lee, Cary T Chiou
Accurate Henry's law constants (H) are unavailable for the majority of organic pollutants, especially those having a low volatility. A novel kinetics-based experimental method is introduced to determine H for a wide range of low-H compounds. The method consists of measuring independently the water-to-air transfer coefficient (KL) and the associated air-phase transfer coefficient (kG) of a low-H chemical (solute) in water when KL ≅ kGH prevails according to the two-film theory. The kG for a solute is obtained via a developed gas-dynamic equation that relates kG to the solute molecular weight and the solute-vapor escaping efficiency (β) through a boundary air layer...
May 1, 2017: Water Research
https://www.readbyqxmd.com/read/28498701/fast-low-to-high-confinement-mode-bifurcation-dynamics-in-a-tokamak-edge-plasma-gyrokinetic-simulation
#19
C S Chang, S Ku, G R Tynan, R Hager, R M Churchill, I Cziegler, M Greenwald, A E Hubbard, J W Hughes
Transport barrier formation and its relation to sheared flows in fluids and plasmas are of fundamental interest in various natural and laboratory observations and of critical importance in achieving an economical energy production in a magnetic fusion device. Here we report the first observation of an edge transport barrier formation event in an electrostatic gyrokinetic simulation carried out in a realistic diverted tokamak edge geometry under strong forcing by a high rate of heat deposition. The results show that turbulent Reynolds-stress-driven sheared E×B flows act in concert with neoclassical orbit loss to quench turbulent transport and form a transport barrier just inside the last closed magnetic flux surface...
April 28, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28498133/numerical-and-experimental-study-of-the-fundamental-flow-characteristics-of-a-3d-gully-box-under-drainage
#20
Pedro Lopes, Rita F Carvalho, Jorge Leandro
Numerical studies regarding the influence of entrapped air on the hydraulic performance of gullies are nonexistent. This is due to the lack of a model that simulates the air-entrainment phenomena and consequently the entrapped air. In this work, we used experimental data to validate an air-entrainment model that uses a Volume-of-Fluid based method to detect the interface and the Shear-stress transport k-ω turbulence model. The air is detected in a sub-grid scale, generated by a source term and transported using a slip velocity formulation...
May 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
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