An Optical Approach to the Dynamical Casimir Effect

We recently proposed a new approach to analyze the parametric resonance in a vibrating cavity based on the analysis of classical optical paths. This approach is used to examine various models of cavities with moving walls. We prove that our method is useful to extract easily basic physical outcome.Comment: 9 page

Exact closed form analytical solutions for vibrating cavities

For one-dimensional vibrating cavity systems appearing in the standard illustration of the dynamical Casimir effect, we propose an approach to the construction of exact closed-form solutions. As new results, we obtain solutions that are given for arbitrary frequencies, amplitudes and time regions. In a broad range of parameters, a vibrating cavity model exhibits the general property of exponential instability. Marginal behavior of the system manifests in a power-like growth of radiated energy.Comment: 17 pages, 7 figure

Balloon aortic valvuloplasty for severe aortic stenosis may reduce mitral regurgitation in mid-term follow-up

INTRODUCTION: Mitral regurgitation (MR) is a frequent complication in patients with severe aortic stenosis (AS). MATERIAL AND METHODS: Echocardiographic assessment of MR was performed at baseline, at 30 days and at 6 months after balloon aortic valvuloplasty (BAV). RESULTS: Data of 271 patients were included in our final analysis, of which 21.2% (n = 85) had at least moderate MR at baseline (in 19 (22.3%) subjects MR was diagnosed as primary). Both groups showed similar severity of AS, but patients in the MR group had a greater left ventricle (LV) size (p = 0.003 for LVESD, p = 0002 for LVEDD) and slightly lower LV ejection fraction (p = 0.04). Mitral regurgitation parameters significantly improved both at 30 days and 6 months after BAV in the MR group (MR jet area: 7.2 (4.5–9.9) vs. 3.6 (2.3–7.2) cm(2), and 7.2 (4.5–9.9) vs. 3.2 (2.1–6.7) cm(2); %MR/left atrial area 34.5 (23.4–42.7) vs. 17.5 (9.3–29.5) and 34.5 (23.4–42.7) vs. 14.5 (8.3–24.5), p < 0.001 for all). In multivariate logistic regression analysis, the change at 30 days, from baseline, in the LVESD (OR = 1.87; 95% CI: 1.23–2.87; p < 0.001) and LVEF (OR = 0.95; 95% CI: 0.87–1.01; p < 0.001); MR jet area (OR = 2.2, 95% CI: 1.5–4.6; p < 0.001) and the presence of primary MR (OR = 3.2, 95% CI: 1.04–5.98; p < 0.001) were retained as independent predictors of significant persisting MR at 6 months. CONCLUSIONS: Balloon aortic valvuloplasty may reduce MR in mid-term follow-up. Predictors of persistent MR at 6 months after BAV included an increase of LVESD and MR jet area and decrease of LVEF at 30 days