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Alexandra E Neal, Paul A Moore
Animals living in aquatic habitats regularly encounter anthropogenic chemical pollution. Typically, the toxicity of a chemical toxicant is determined by the median lethal concentration (LC50) through a static exposure test. However, LC50 values and static tests do not provide an accurate representation of exposure to pollutants within natural stream systems. In their native habitats, animals experience exposure as a fluctuating concentration due to turbulent mixing, temporal variations of contamination (seasonal inputs), and contaminant input type (point vs...
October 19, 2016: Ecotoxicology and Environmental Safety
Stefan Kramel, Greg A Voth, Saskia Tympel, Federico Toschi
We introduce a new particle shape which shows preferential rotation in three dimensional homogeneous isotropic turbulence. We call these particles chiral dipoles because they consist of a rod with two helices of opposite handedness, one at each end. 3D printing is used to fabricate these particles with a length in the inertial range and their rotations are tracked in a turbulent flow between oscillating grids. High aspect ratio chiral dipoles preferentially align with their long axis along the extensional eigenvectors of the strain rate tensor, and the helical ends respond to the extensional strain rate with a mean spinning rate that is nonzero...
October 7, 2016: Physical Review Letters
S R Mittal
A 14 years asymptomatic male was evaluated for a grade 3/6 systolic murmur along lower left parasternal region. Color Doppler evaluation revealed turbulent systolic flow across moderator band with a peak systolic gradient of 127.2 mm hg. There was no other abnormality. This anomaly should be considered in differential diagnosis of systolic murmur in tricuspid area.
August 2016: Journal of the Association of Physicians of India
C F Barenghi, Y A Sergeev, A W Baggaley
Experiments and numerical simulations of turbulent (4)He and (3)He-B have established that, at hydrodynamic length scales larger than the average distance between quantum vortices, the energy spectrum obeys the same 5/3 Kolmogorov law which is observed in the homogeneous isotropic turbulence of ordinary fluids. The importance of the 5/3 law is that it points to the existence of a Richardson energy cascade from large eddies to small eddies. However, there is also evidence of quantum turbulent regimes without Kolmogorov scaling...
October 20, 2016: Scientific Reports
Mesude Ozturk, Dimitrios V Papavassiliou, Edgar A O'Rear
In this work, contributing factors for red blood cell damage in turbulence were investigated by simulating jet flow experiments. Results showed that dissipative eddies comparable or smaller in size to the red blood cells cause hemolysis and that hemolysis corresponds to the number and the surface area of eddies that are associated with Kolmogorov length scale smaller than about 10 µm. The size distribution of Kolmogorov scale eddies was used to define a turbulent flow extensive property with eddies serving as a means to assess the turbulence effectiveness in damaging cells, and a new hemolysis model was proposed...
October 19, 2016: Journal of Biomechanical Engineering
Dhananjai Saranadhi, Dayong Chen, Justin A Kleingartner, Siddarth Srinivasan, Robert E Cohen, Gareth H McKinley
Skin friction drag contributes a major portion of the total drag for small and large water vehicles at high Reynolds number (Re). One emerging approach to reducing drag is to use superhydrophobic surfaces to promote slip boundary conditions. However, the air layer or "plastron" trapped on submerged superhydrophobic surfaces often diminishes quickly under hydrostatic pressure and/or turbulent pressure fluctuations. We use active heating on a superhydrophobic surface to establish a stable vapor layer or "Leidenfrost" state at a relatively low superheat temperature...
October 2016: Science Advances
Hongpeng Lai, Shuyong Wang, Yongli Xie
In the New Qidaoliang Tunnel (China), a rear-end collision of two tanker trunks caused a fire. To understand the damage characteristics of the tunnel lining structure, in situ investigation was performed. The results show that the fire in the tunnel induced spallation of tunnel lining concrete covering 856 m³; the length of road surface damage reached 650 m; the sectional area had a maximum 4% increase, and the mechanical and electrical facilities were severely damaged. The maximum area loss happened at the fire spot with maximum observed concrete spallation up to a thickness of 35...
October 15, 2016: International Journal of Environmental Research and Public Health
Yoshitaka Matsuzaki
Despite many previous in situ estimates of horizontal diffusivity below the sea surface, horizontal diffusivity at the sea surface, which is a parameter required in the prediction of oil diffusion, has not been formulated. This study conducted in situ estimations to quantify horizontal diffusivity at the sea surface. To measure the horizontal diffusivity at and below the sea surface, clusters of thin sponge rubbers (simulating spilled oil), together with drifting buoys, were deployed on successive occasions in Sagami Bay, Japan...
October 14, 2016: Marine Pollution Bulletin
S Longhi
Parity-time (PT) symmetry is one of the most important accomplishments in optics over the past decade. Here the concept of PT mode-locking (ML) of a laser is introduced, in which active phase-locking of cavity axial modes is realized by asymmetric mode coupling in a complex time crystal. PT ML shows a transition from single- to double-pulse emission as the PT symmetry breaking point is crossed. The transition can show a turbulent behavior, depending on a dimensionless modulation parameter that plays the same role as the Reynolds number in hydrodynamic flows...
October 1, 2016: Optics Letters
V A Banakh, I A Razenkov
Experimental data proving the possibility of lidar measurement of the refractive turbulence strength based on the effect of backscattering amplification are reported. It is shown, for the first time to our knowledge, that the values of the amplification factor correlate with the variance of random jitter of the optical image of an incoherent light source depending on the value of the structure constant of the air refractive index turbulent fluctuations averaged over the probing path.
October 1, 2016: Optics Letters
Jenny M Pedersen, Yoo-Sik Shim, Vaibhav Hans, Martin B Phillips, Jeffrey M Macdonald, Glenn Walker, Melvin E Andersen, Harvey J Clewell, Miyoung Yoon
Accurate prediction of metabolism is a significant outstanding challenge in toxicology. The best predictions are based on experimental data from in vitro systems using primary hepatocytes. The predictivity of the primary hepatocyte-based culture systems, however, is still limited due to well-known phenotypic instability and rapid decline of metabolic competence within a few hours. Dynamic flow bioreactors for three-dimensional cell cultures are thought to be better at recapitulating tissue microenvironments and show potential to improve in vivo extrapolations of chemical or drug toxicity based on in vitro test results...
2016: Frontiers in Bioengineering and Biotechnology
Indrajith D Nissanka, Poojitha D Yapa
The ability to calculate the oil droplet size distribution (DSD) and its dynamic behavior in the water column is important in oil spill modeling. Breaking waves disperse oil from a surface slick into the water column as droplets of varying sizes. Oil droplets undergo further breakup and coalescence in the water column due to the turbulence. Available models simulate oil DSD based on empirical/equilibrium equations. However, the oil DSD evolution due to subsequent droplet breakup and coalescence in the water column can be best represented by a dynamic population model...
October 10, 2016: Marine Pollution Bulletin
David A Riehm, David J Rokke, Prakash G Paul, Han Seung Lee, Brent S Vizanko, Alon V McCormick
Lecithin-rich mixtures of the nontoxic surfactants lecithin and Tween 80 are effective marine oil spill dispersants, but produce much higher oil-water interfacial tension than other, comparably effective dispersants. This suggests interfacial phenomena other than interfacial tension influence lecithin-Tween 80 dispersants' effectiveness. The interface between seawater and dispersant-crude oil mixtures was studied using light microscopy, cryogenic scanning electron microscopy, and droplet coalescence tests. Lecithin:Tween 80 ratio was varied from 100:0 to 0:100 and wt% dispersant in the oil was varied from 1...
October 5, 2016: Journal of Colloid and Interface Science
K J Zhao, Y Nagashima, P H Diamond, J Q Dong, K Itoh, S-I Itoh, L W Yan, J Cheng, A Fujisawa, S Inagaki, Y Kosuga, M Sasaki, Z X Wang, L Wei, Z H Huang, D L Yu, W Y Hong, Q Li, X Q Ji, X M Song, Y Huang, Yi Liu, Q W Yang, X T Ding, X R Duan
The synchronization of geodesic acoustic modes (GAMs) and magnetic fluctuations is identified in the edge plasmas of the HL-2A tokamak. Mesoscale electric fluctuations (MSEFs) having components of a dominant GAM, and m/n=6/2 potential fluctuations are found at the same frequency as that of the magnetic fluctuations of m/n=6/2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m/n=6/2 magnetic fluctuations...
September 30, 2016: Physical Review Letters
Mohammad Farazmand, Themistoklis P Sapsis
Drawing upon the bursting mechanism in slow-fast systems, we propose indicators for the prediction of such rare extreme events which do not require a priori known slow and fast coordinates. The indicators are associated with functionals defined in terms of optimally time-dependent (OTD) modes. One such functional has the form of the largest eigenvalue of the symmetric part of the linearized dynamics reduced to these modes. In contrast to other choices of subspaces, the proposed modes are flow invariant and therefore a projection onto them is dynamically meaningful...
September 2016: Physical Review. E
S Murray, M F Lightstone, S Tullis
The target Lagrangian kinematic simulation method was motivated as a stochastic Lagrangian particle model that better synthesizes turbulence structure, relative to stochastic separated flow models. By this method, the trajectories of particles are constructed according to synthetic turbulent-like fields, which conform to a target Lagrangian integral timescale. In addition to recovering the expected Lagrangian properties of fluid tracers, this method is shown to reproduce the crossing trajectories and continuity effects, in agreement with an experimental benchmark...
September 2016: Physical Review. E
Eleftherios Gkioulekas
Using the fusion-rules hypothesis for three-dimensional and two-dimensional Navier-Stokes turbulence, we generalize a previous nonperturbative locality proof to multiple applications of the nonlinear interactions operator on generalized structure functions of velocity differences. We call this generalization of nonperturbative locality to multiple applications of the nonlinear interactions operator "multilocality." The resulting cross terms pose a new challenge requiring a new argument and the introduction of a new fusion rule that takes advantage of rotational symmetry...
September 2016: Physical Review. E
Nicholas M Rathmann, Peter D Ditlevsen
Fully developed homogeneous isotropic turbulence in two dimensions is fundamentally different from that in three dimensions. In two dimensions, the simultaneous inviscid conservation of both kinetic energy and enstrophy within the inertial range of scales leads to a forward cascade of enstrophy and a reverse cascade of energy. In three dimensions, helicity, the integral of the scalar product of velocity and vorticity, is also an inviscid flow invariant along with the energy. Unlike the enstrophy, however, the helicity does not block the forward cascade of energy to small scales...
September 2016: Physical Review. E
Ö D Gürcan, P Morel, S Kobayashi, Rameswar Singh, S Xu, P H Diamond
A detailed systematic derivation of a logarithmically discretized model for two-dimensional turbulence is given, starting from the basic fluid equations and proceeding with a particular form of discretization of the wave-number space. We show that it is possible to keep all or a subset of the interactions, either local or disparate scale, and recover various limiting forms of shell models used in plasma and geophysical turbulence studies. The method makes no use of the conservation laws even though it respects the underlying conservation properties of the fluid equations...
September 2016: Physical Review. E
Mustafa Gulgun
No abstract text is available yet for this article.
October 10, 2016: Medical Principles and Practice: International Journal of the Kuwait University, Health Science Centre
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