RESUMEN
We present modeling and analysis of a hysteretic deformable mirror where the facesheet interacts with a continuous layer of piezoelectric material that can be actuated distributively by a matrix of electrodes through multiplexing. Moreover, a method to calculate the actuator influence functions is described considering the particular arrangement of electrodes. The results are presented in a semi-analytical model to describe the facesheet's deformation caused by a high-density array of actuators, and validated in a simulation. The proposed modeling of an interconnection layout of electrodes is used to determine the optimal pressures the actuators must exert to achieve a desired surface deformation.
RESUMEN
The results of surgery for benign oesophageal stricture in 53 consecutive cases referred to a sub-regional Cardiothoracic Unit are presented. The operations included retrograde dilatation and either total fundoplication or Allison repair, or an oesophageal resection with gastro-oesophageal anastomosis through a trans-thoracic approach. Postoperative fatality was 9%. Most subsequent deaths were due to unrelated acute events with a 5-year survival rate of 62%. Sixty per cent were free from dysphagia and 82% led active and independent lives without support. Surgery offers an alternative to dilatation in elderly patients with oesophageal stricture.