tmtesdeigafnsruoarlmeoosacfnixlAl2a,rtt/ihoCen2Hsnud2 mideibsacewhraadyre,gnwes,eiwtcyhaaninleidnitsfeiiszrepthoroaf dtdutuhcse-t oscillations in dust population are also dying away, in good agreement with the model's 'stable spiral' solution, shown in Fig. 4 as well as in Fig. ...