The Structure and Evolution of Molecular Clouds: from Clumps to Cores to the Imf

o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o We review the pr gress that has been made in bserving and analyzing m lecular cl ud structure in recent years. Structures are self-similar ver a wide range f scales, with similar p wer law indexes, independent f the star-f rming nature f a cl ud. C mparis n f structures at parsec-scale res luti n in a star-f rming and n n-star-f rming cl ud sh w that the average densities in the f rmer are higher but the structural characteristics in each cl ud are much the same. In gravitati nally b und regi ns f a cl ud, h wever, and at higher densities and res luti n, the selfsimilar scaling relati nships break d wn, and it is p ssible t bserve the first steps t ward star f rmati n. High-res luti n bservati ns f the dense individual starf rming c res within the clumps h ld the key t an empirical understanding f the rigins f the stellar initial mass functi n.