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A theory of many-dimensional real-time quantum dynamics is studied in terms of action decomposed function (ADF), a class of quantum wave function. In the preceding companion paper [ S. Takahashi and K. Takatsuka Phys. Rev. A 89 012108 (2014)], we showed that semiclassical dynamics for ADF in the Lagrange picture of phase flow can be described in terms of what we call deviation determinant and associated quantum phases without use of the stability matrix. Consequently, the Hessian of the involved potential functions is not required in this formalism. This paper is devoted to an analysis of the mechanism of quantum diffusion (quantum smoothing) that removes the singularity inherent in the semiclassical ADF: We derive a Lorentzian form for the amplitude factor of ADF. The real part of its denominator comes from the deviation determinant, while the imaginary part reflects quantum diffusion and is proportional to the Planck constant. The presence of the nonzero imaginary part smooths out the singularity and removes the divergence. Besides, this imaginary part can be obtained through a Wronskian relation with the deviation vectors, which can be solved rather easily at each space-time point on a classical trajectory. A number of theoretical advantages of the Lorentzian form and the Wronskian relation are illustrated theoretically and numerically. It turns out that there is no essential difficulty in applications to many-dimensional heavy-particle systems such as molecules. The theory is examined with stringent numerical tests. [ABSTRACT FROM AUTHOR]

We study a quantum theory in terms of action decomposed function (ADF), a class of quantum wave function, towards many-dimensional applications to quantum dynamics of heavy particles as in chemical reactions. The equation of motion for the complex-valued amplitude of ADF represents a coupling between the internal diffusive motion of a wave packet and dynamics of its group velocity in a hierarchical manner ascending from classical to purely quantum mechanics via semiclassical dynamics. We attempt to solve this equation of motion dividing it into two stages: a semiclassical level and beyond. In this paper, as the first stage, we develop a semiclassical approximation in the Lagrange picture of classical phase flow. In the Euler picture (as in the standard WKB picture), continuous integration of the stability matrix along the paths is required. By adopting the Lagrange picture, on the other hand, we represent the semiclassical amplitude in terms of what we call deviation determinant, which can be evaluated readily in many-dimensional systems. Numerical tests show that ADF reproduces quantum wave packets at each space-time point along classical paths very well. However, the ADF in this stage is not free of the semiclassical singularity. In other words, the wave functions diverge at turning points or caustics, depending on the initial conditions chosen. This divergence is known to take place at points where classical paths smoothly distributed in phase space have "focuses" in configuration space (or momentum space) and reflects an intrinsic relationship between quantum and classical mechanics. Therefore, it is by studying the mechanism of removing the singularity that the essential feature of quantum mechanics will be clarified. This aspect will be discussed in a companion paper [ K. Takatsuka and S. Takahashi Phys. Rev. A 89 012109 (2014)] as the second stage of many-body quantum theory. [ABSTRACT FROM AUTHOR]

Introduction:Steam pops (SPs) during radiofrequency catheter ablation (RFA) using force sensing catheters are infrequent but represent a potential severe complication such as embolic stroke, cardiac perforation. SPs remains unpredictable, and unclear in detailed phenomenon.Methods:In an ex vivo, we set the bovine myocardium to 36 °C in a constant temperature bath and performed an experiment in a water tank that generated a non-pulsatile flow. RFA using irrigation catheter was applied at catheter-tissue contact force (CF) 5, 10, 20g, 30g, 40g, and 50g for 30sec. The increase of tissue echogenicity (increased echo brightness) observed by intracardiac echocardiographic images using ViewFlex™ Xtra and impedance during RFA were evaluated with and without SPs.Results:SPs phenomenon appeared in 48 out of 137 sites (35%), and the increased echo brightness during RFA was observed in 89 lesions (65%). All lesions with SPs showed increased echo brightness before SPs (6.4±6.1sec before SPs). Sites with SPs showed stronger CF (30.8±14.8g vs. 22.9±15.9g, p=0.0047), higher initial impedance (78±12Ω vs. 73±9Ω, p=0.0063), greater impedance drops in 5 seconds after the beginning of RFA (13±7Ω, vs. 6±5Ω, p<0.0001), and earlier appearance of increased echo brightness (9.7±6.2 vs 17.4±6.3 sec, p<0.0001). Among 89 lesions with increased echo brightness, sites with SPs showed greater impedance drops in 5 seconds after the beginning of RFA (13±7Ω, vs. 7±6Ω, P<0.0001). In ROC curve analysis of the impedance drops in 5 seconds after the beginning of RFA (AUC, 0.81; sensitivity, 85%; specificity, 71%), optimal cut-off value of SPs was 7.6Ω, and SPs were not observed in lesions with the impedance drops of 3Ω or less. (Figure)Conclusions:The increase of tissue echogenicity observed by ICE images show the pre-state of all steam pops during RFA. Steam pops could be avoided by checking the impedance drop at the initial stage of RFA under ICE monitoring.

No relevant conflicts of interest to declare.