Is day-case cataract surgery an attractive alternative from the patients' point of view? A questionnaire survey.

Cataract surgery is the most common elective surgical procedure undertaken in elderly people. In many European countries and in the USA cataract surgery is normally a day-case procedure without an overnight stay in hospital, unlike the situation in Austria where fewer than 2% of patients are day cases. However, there is a lack of prospective studies on patients' need for and acceptance of day-case surgery.

A robust subspace algorithm for principal component analysis.

We present a noise robust PCA algorithm which is an extension of the Oja subspace algorithm and allows tuning the noise sensitivity. We derive a loss function which is minimized by this algorithm and interpret it in a noisy PCA setting. Results on the local stability analysis of this algorithm are given and it is shown that the locally stable equilibria are those which minimize the loss function.