Introduction: The influence of power (Watt [W]) and total energy (Joule [J]) on lesion size and the optimal overlap ratio remain unclear in laser balloon (LB) ablation for atrial fibrillation. We aimed to evaluate lesion size and visible gaps after LB ablation with various energy settings and different overlap ratios in vitro model.
Methods and Results:Chicken muscles were cauterized using the first-generation LB with single applications of full and a half duration of six energy settings (5.5 W/30 seconds [165 J] to 12 W/20 seconds [240 J]) and varying power (5.5-12 W) at the constant total energy (160 J). Three overlapped ablations with different ratios (25% and 50%) for each energy setting were also performed to evaluate the visible gap degree categorized from 1 (perfect) to 3 (poor). Twenty lesions were evaluated for each energy setting. In single applications of full duration, lesion depth, lesion volume, and maximum lesion diameter increased according to the total energy (all, P < .001) and were greater than in those of half duration in each energy setting (all, P < .05).However, applications with larger power created larger lesion volume and maximum lesion diameter at constant total energy (P < .05). The visible gap degree was better in all energy settings with 50% overlapped ablation than in those with 25% (all, P < .001).Conclusion: Lesion size depends not only on power but also on total energy in the LB ablation. Sufficiently overlapped ablations allow continuous lesion formation. K E Y W O R D S laser ablation experiment, laser balloon, laser energy setting, lesion size, optimal overlap ratio
We study the critical behavior of a random field O(N ) spin model with a second-rank random anisotropy term in spatial dimensions 4 < d < 6, by means of the replica method and the 1/N expansion. We obtain a replica-symmetric solution of the saddle-point equation, and we find the phase transition obeying dimensional reduction. We study the stability of the replica-symmetric saddle point against the fluctuation induced by the second-rank random anisotropy. We show that the eigenvalue of the Hessian at the replica-symmetric saddle point is strictly positive. Therefore, this saddle point is stable and the dimensional reduction holds in the 1/N expansion. To check the consistency with the functional renormalization group method, we obtain all fixed points of the renormalization group in the large N limit and discuss their stability. We find that the analytic fixed point yielding the dimensional reduction is practically singly unstable in a coupling constant space of the given model with large N . Thus, we conclude that the dimensional reduction holds for sufficiently large N .
Mapping the Abelian Higgs model to the massive sine–Gordon theory, the phase structure of the Abelian Higgs model is studied. The effect of interaction between instantons in the Abelian Higgs model is treated through the renormalization-group study of the massive sine–Gordon model. In the small dynamical-mass region the interaction between instantons is not negligible, and the effective density of instantons becomes very low at long distance (over the crossover distance) by the pairing mechanism. Therefore, the Abelian Higgs model reduces to a massive scalar theory interacting with very dilute instantons. In the large dynamical-mass region, the pairing mechanism of instanton and anti-instanton does not occur. This crossover phenomenon can be observed by the Wilson loop of a fractional charge. The relationship with the massive Schwinger–Thirring model is also discussed. It is also shown that the recently studied topological-field region is an ultraviolet fixed point of the renormalization-group flow.
We calculate connected correlators in Gaussian orthogonal, unitary and symplectic random matrix ensembles by the replica method in the 1/Nexpansion. We obtain averaged one-point Green's functions up to the nextto-leading order O(1/N), wide two-level correlators up to the first nontrivial order O(1/N 2 ) and wide three-level correlators up to the first nontrivial order O(1/N 4 ) by carefully treating fluctuations in saddle-point evaluation.
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