Leptoproduction of Heavy Quarks in the Fixed and Variable Flavor Schemes   (CONFERENCE Version)
  We compare the results of the fixed-flavor scheme calculation of Laenen, Riemersma, Smith and van Neerven with the variable-flavor scheme calculation of Aivazis, Collins, Olness and Tung for neutral-current (photon-mediated) heavy-flavor (charm and bottom) production. We compare the structure function $F_2(x,Q^2)$ throughout phase space, and also analyze the $\mu$-dependenceWe find that the former calculation is most applicable near threshold, while the latter works well for asymptotic $Q^2$. 
Fredrick I. Olness and Stephan T. Riemersma