Bayesian identification of acoustic impedance in treated ducts.

The noise reduction of a liner placed in the nacelle of a turbofan engine is still difficult to predict due to the lack of knowledge of its acoustic impedance that depends on grazing flow profile, mode order, and sound pressure level. An eduction method, based on a Bayesian approach, is presented here to adjust an impedance model of the liner from sound pressures measured in a rectangular treated duct under multimodal propagation and flow. The cost function is regularized with prior information provided by Guess's [J. Sound Vib. 40, 119-137 (1975)] impedance of a perforated plate. The multi-parameter optimization is achieved with an Evolutionary-Markov-Chain-Monte-Carlo algorithm.

Photofrin II uptake by atheroma in atherosclerotic rabbits. Fluorescence and high performance liquid chromatographic analysis on post-mortem aorta.

Atherosclerotic lesions were induced in normal and Watanabe rabbits by atherogenic diet and stripping of aorta endothelium. The rabbits were injected with Photofrin II and sacrificed two days later. Atheromatous aorta as well as normal aorta from control animals were characterized by their fluorescence spectra using front face excitation. Characteristic emission peaks at 631 and 694 nm were displayed at atheromatous plaques. The excitation spectrum shows a strong band at 394 nm and weaker bands at 446, 504, 536 and 574 nm. Although no fluorescence of normal aorta can be seen by visual inspection, emission with a maximum at 626 nm was detected by spectrofluorimetry. Normal phase high performance liquid chromatography analysis of extracts from atheroma and control aorta were also carried out. The specific labelling of atheroma involves mainly protoporphyrin, hematoporphyrin and also minor components of Photofrin II which are accumulated. Some other components are accumulated but do not appear to be specifically retained by atheroma.

Results of percutaneous valvuloplasty for calcific aortic stenosis with different balloon catheters.

Percutaneous aortic valvuloplasty is a palliative treatment for patients with calcific aortic stenosis who would be poor candidates for surgical treatment. The results and associated complications of this procedure were analysed in a series of 47 patients in which different types of dilating catheters were used. In 25 patients a single balloon (19 mm) was used (group A), in 13 patients a bifoil balloon (2 x 15mm) (group B), and in the remaining nine patients (group C) a trefoil balloon (3 x 10mm) was used. An increase in aortic valve area was achieved in all patients. The results obtained with the bifoil balloon were better than with the other types of balloon catheter, with an increase in aortic area of + 118% vs. + 74% (monofoil) and + 76% (trefoil) (P less than 0.05). The tolerance of the inflation procedure was also better with this type of balloon, as it allowed for shorter inflation and deflation times. These results show that balloon aortic valvuloplasty, when indicated, is best performed with a bifoil balloon dilating catheter, and undue complications usually do not occur.

Right heart failure due to an inter-atrial shunt after percutaneous mitral balloon dilatation.

Percutaneous mitral valve dilatation was performed in a 61-year-old female patient with severe mitral valve stenosis. The valve could be dilated, but a moderate left to right atrial shunt was present after the procedure. Although the mitral valve area had increased from 1 cm2 to 1.7 cm2, the patient presented 1 week later with right heart failure, explained by right heart volume overload resulting from the persistent shunt. Clinical status quickly improved with diuretics. Although this evolution has not been previously reported, it may be expected in older patients with decreased compliance of pulmonary arteries and right heart chambers.