Branch Retinal Artery Occlusion - Pathophysiology. 1  Most commonly, a branch retinal artery occlusion occurs secondary to an embolus. Emboli typically originate within vessels upstream where they dislodge and travel within the circulatory system to ultimately become lodged downstream in a vessel with a smaller lumen.
Ragtime is a musical form or style that is defined as a syncopated melody (usually in 2/4 time) over a regular, march tempo bass line. Improvisation was common but little of that aspect has been preserved.
The emergence of mature ragtime is usually dated to 1897, the year in which several important early rags were published. In 1899, Scott Joplin 's  Maple Leaf Rag  was published and became a great hit and demonstrated more depth and sophistication than earlier ragtime.