This manusdpt has been reproâuced from the microfilm master. UMI films aie text directly from the original or copy submitled. Thus, some aiesis and dissertation copies are in typewriter face. h i l e othem may be from any type of amputer printer. ïhe quality d this nproduction is drpenâent upon the qwlity of the copy subrnïtted. Broken or indistinct print cobred or poor quality illustrations and photognphs, pnnt bkedthmugh, substandard margins, and impmper alignment can advenely affect reproducüon. In the unlikely event that the auaior did not send UMI a compfete manuscript and there are missing pages, these will be noted. Also. if unsuthorired copyright material had to be rmoved, a note will indicate the deletion. OversUe materials (e-g., ...