A novel ventricular map of electrograms duration as a method to identify areas of slow conduction during ablation of ventricular tachycardia

Funding Acknowledgements Type of funding sources: None. Background – Wave front inhomogeneous propagation is crucial for reentry circuit generation. Bipolar EGM duration is indicative of local conduction delay and may identify areas of low conduction as a functional substrate. This study aimed to create a map of EGM duration during the VT (VEDUM Map) to identify the area of the slowest conduction and to verify if RF delivery at this area allows to rapidly interrupt the VT. Methods – 24 high-density VTs maps (21 patients) were analyzed. Activation maps and voltage maps during SR were performed. An offline remap confirmed with MathLab software was customized to visualize the longest duration electrogram during VT. Results – All of the VTs were interrupted during the first RF delivery (mean time 7,3 ± 5,4 sec (range 3-25 sec)) at the area with the longest EGM duration (212 ± 47 ms (range 113-330 ms)). . In 9 pts (37,5%) the longest EGM was located at the entrance or exit area of the activation maps while in 5 pts (21%) the EGM covered the full diastolic phase. Finally, in 10 pts the longest EGM occurred in the mid-exit-diastolic phase. Conclusions - A novel Ventricular map of Electrograms DUration (VEDUM Map) is highly accurate in defining a conductive vulnerable zone of the VT circuit. The longest EGM duration within the isthmus is highly predictive of rapid VT termination. Quantitative variablesQualitative variablesMeanMedianStandard DeviationAge71738.40BMI26.624.54.02LV EDV16315442.7LV EDD61.2629.9LV EF38.7369.74VT cycle lenght (TCL)35537556.4EGM max. duration in VT21220847EGM max dur / TCL58.260.512Maximum EGM duration localization in CLProto = 12.5%Meso = 33.3%Tele = 25%Full = 20.8%Myocardium voltage characteristics in VEDUM EGMHealthy = 25%Transition = 20.8%Scar = 41.7%Critical Isthmus area12.3107.3VT Interruption during RFYes = 79.2%No = 20.8%Time (seconds) to interruption765Access typeEndo = 58.3%Epi = 29.2%Clinical and procedural dataAbstract Figure.

Novel soliton solutions to the Atangana–Baleanu fractional system of equations for the ISALWs

This work deals the construction of novel soliton solutions to the Atangana–Baleanu (AB) fractional system of equations for the ion sound and Langmuir waves by using Sardar-subequation method (SSM). The outcomes are in the form of bright, singular, dark and combo soliton solutions. These solutions have wide applications in the arena of optoelectronics and wave propagation. The bright solitons will be a vast advantage in controlling the soliton disorder, dark solitons are also beneficial for soliton communication when a background wave exists and singular solitons only elaborate the shape of solitons and show a total spectrum of soliton solutions created from the model. These results would be very helpful to study and understand the physical phenomena in nonlinear optics. The performance of the SSM shows that this is powerful, talented, suitable and direct technique to discover the exact solutions for a number of nonlinear fractional models.

NUMERICAL SIMULATION OF THREE-DIMENSIONAL WAVE ATTRACTORS

Internal and inertial waves obey very specific dispersion relation, which defines the direction of wave propagation with respect to the gravity or axis of rotation, but which does no define the wavelength. Particular cases of scale effects are described in (Brouzet et al., 2017). In closed geometrics the presence of a monochromatic wavemaker can produce wave beams, which after multiple reflections from the boundaries may approach a closed loop – the wave attractor. In ideal fluids the concentration of energy on the wave attractor can grow without any limits. In viscous stratified or rotating fluids the concentration will be balanced with dissipation due to viscosity, which results in appearance of wave attractors of finite width. The characterization of the flow with the Reynolds number based on the boundary conditions is questionable in this case, since on the attractor the velocity can be several times magnified. When the wave beam is reflected from an inclined plane, the horizontal component of velocity rotates, as was first described by O. Phillips, while preserving the angle with the gravity or axis of rotation. With the help of ray tracing it can be shown that due to this effect the three-dimensional accumulation of wave energy can occur. First qualitative and quantitative correspondence of laboratory and numerical simulation of wave attractors in the pseudo-2D laboratory tank with trapezoidal section was described in (Brouzet et al., 2016), and importance of dissipation on the lateral boundaries was shown (F. Beckebanze et al., 2018). For high Schdmidt number there appear the folded structures, which can interact with the background wave motion (Sibgatullin, Kalugin 2016). In (Brouzet et al., 2016b), (Dauxois et al., 2018) cascade of triadic resonances in (1,1) produced by a wave attractor was demonstrated. Three-dimensional accumulation of wave energy in trapezoidal frustum with a localized wavemaker was investigated in (Pillet et al., 2018). Numerical simulations of the present work had showed the importance of phase shift in transversal direction. An attractor can have the same form as the 2D attractor in any given longitudinal cut, but the phase of oscillation can change up to counter-phase. Interplay of 3D concentration of waves beams, dissipation and phase shifting impact the final energy distribution in transversal direction. First three-dimensional simulations (Sibgatullin et al., 2017) of tidal and symmetric forcing on the rotating layer of fluid with inclined walls showed three-dimensional twisted structure of waves attractors for precession of one boundary of the layer in opposite direction to the rotation of the layer. With growth of the amplitude of the external forcing the the instability of triadic resonance appears, but in contrast to the internal wave attractors, triadic resonances take place in azimuthal (transversal to the trapeze) section. The turbulent regimes generated by the background wave attractors are studied, with analysis of full power income and total dissipation. The research was supported by the Program of Fundamental Research of the Presidium of the Russian Academy of Sciences No. 26

Parametric subharmonic instability in a narrow-band wave spectrum

Parametric subharmonic instability arising in a narrow-band wave spectrum is investigated. Using a statistical equation that describes weakly nonlinear interactions in a random wave field, we perform analytical and numerical stability analyses for a modulating wave train. The analytically obtained growth rate $\unicode[STIX]{x1D706}=(-\unicode[STIX]{x1D707}+\sqrt{\unicode[STIX]{x1D707}^{2}+4CE_{B}})/2$ agrees favourably with the results from direct numerical experiments, where $\unicode[STIX]{x1D707}$ is the half-value width of the background wave frequency spectrum, $E_{B}$ is the background wave energy density, and $C$ is a constant. This expression has two asymptotic limits: $\unicode[STIX]{x1D706}\sim \sqrt{CE_{B}}$ for $\unicode[STIX]{x1D707}\ll \sqrt{CE_{B}}$ and $\unicode[STIX]{x1D706}\sim CE_{B}/\unicode[STIX]{x1D707}$ for $\unicode[STIX]{x1D707}\gg \sqrt{CE_{B}}$. In the terms of weak turbulence, these two growth rates correspond to the ones occurring in the dynamic and kinetic time scales. In this way, our formulation successfully unifies the two conventional types of parametric subharmonic instability and offers a new criterion to determine the applicability of the classical kinetic equation in three-wave systems.

A New Defect Detection Method of Ultrasonic TOFD Image for Lateral Waves Suppression

TOFD (Time of flight diffraction) is suitable for the weld defects in the detection and has been widely used in the vessel of pressure. To widen the range of detection in TOFD and the removal of the background wave, a new lateral wave suppression method for TOFD image is proposed. Firstly, ultrasound TOFT image signal of the model is established. Secondly, a new searching clustering algorithm is proposed. Then, it is used to lateral wave suppression. The results show that the lateral wave can be eliminated effectively even if lateral waves are shaking seriously.

Vortex Stability in a Large-Scale Internal Wave Shear

The effect of a large-scale internal wave on a multipolar compound vortex was simulated numerically using a 3D Boussinesq pseudospectral model. A suite of simulations tested the effect of a background internal wave of various strengths, including a simulation with only a vortex. Without the background wave, the vortex remained apparently stable for many hundreds of inertial periods but then split into two dipoles. With increasing background wave amplitude, and hence shear, dipole splitting occurred earlier and was less symmetric in space. Theoretical considerations suggest that the vortex alone undergoes a self-induced mixed barotropic–baroclinic instability. For a vortex plus background wave, kinetic energy spectra showed that the internal wave supplied energy for the dipole splitting. In this case, it was found that the presence of the wave hastened the time to instability by increasing the initial perturbation to the vortex. Results suggest that the stability and fate of submesoscale vortices in the ocean may be significantly modified by the presence of large-scale internal waves. This could in turn have a significant effect on the exchange of energy between the submesoscale and both larger and smaller scales.

Limited‐view diffraction tomography in a nonuniform background

The main problems in geophysical diffraction tomography are (1) complicated media and (2) rather limited acquisition geometries. Existing algorithms solve the limited‐view problem in an iterative manner, but are valid only for line sources and 2-D homogeneous background models. In this paper, we derive an iterative algorithm based on asymptotic wave theory that can compensate for a limited acquisition geometry. The method is valid for a 2-D nonuniform background model and point‐source illumination (i.e., a 2.5-D geometry). Paraxial ray tracing is employed to model the arbitrary background wave response, and the general structure of the algorithm has a strong resemblance to the iterative ART‐algorithm used in straight ray tomography. Our method is shown to be stable in the presence of moderate white noise and gives reasonable results, both geometrically and quantitatively, when applied to synthetic crosshole data involving a nonhomogeneous background model and limited view.