Effects of boundary conditions on the critical spanning probability
  The fractions of samples spanning a lattice at its percolation threshold are found by computer simulation of random site-percolation in two- and three-dimensional hypercubic lattices using different boundary conditions. As a byproduct we find $p_c = 0.311605(5)$ in the cubic lattice. 
Muktish Acharyya & Dietrich Stauffer (Cologne University, Germany)