Aspects are a novel programming language feature, to express concerns in program design that crosscut traditional abstraction boundaries. The focus of this paper are dynamic aspects. Such aspects are specified as pointcut designators (patterns in the call stack), coupled with advice (code whose execution is triggered by the given pattern). We propose a more primitive syntax for pointcut designators, based on regular expressions. This primitive syntax facilitates a new static analysis that in turn enables a more efficient implementation of aspects.