This rnanusuipt has been reproduced from the miuofilm master. UMI films the text directly from!he original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this mproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, cobred or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affed reproduction. In the unlikely event that the author did not send UMI a compleb manuscript and there am missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials...