Injectivity radius bound of Ricci flow with positive Ricci curvature and   applications
  In this paper, we study the injectivity radius bound for 3-d Ricci flow. As applications we show the long time existence of the Ricci flow with positive Ricci curvature. We also partially settle a question in page 302 of the book of Chow-Lu-Ni (2006). 
Li Ma, Anqiang Zhu
math.DG