10.1083/jcb/1722iti3jcb1722iti3Sometimes size does matter D uring myofi broblast differentiation in vitro, “supermature” focal adhesions (FAs) arise due to increased physical stress, report Goffi n et al. (page 259). Additionally, increased tension induces accumulation of αsmooth muscle actin (α-SMA) in stress fi bers that are anchored at these FAs. In vivo, the extracellu...

Model-based revision of knowledge bases ex­ pressed as first-order theories was shown in [Winslett 88b] to be useful as a means of de­ scribing and reasoning about the effects of ac­ tions. This paper shows that model-based the­ ory revision is actually expressible as a form of circumscription. This shows that in cer­ tain applications, the cumbersome conceptu­ ally machinery of circumscription...