Academic dress is only worn on ceremonial occasions: the university anniversary or "dies natalis", inaugural lectures, and the public defence of a doctoral thesis. On such occasions, the assembled professors line up as a "cortège" headed by the university beadle, who also wears an academic gown and carries the university's mace. Male professors remove their beret when sitting down and put it on when standing up (e.g. to lecture or to address a doctoral candidate during the thesis defence). Female professors may keep the beret on at all times.