The job is defined by the script: bigbox_scaling_crn.bbs
This has a big box 302x302x302 cells with bio-physically realistic
Courtmanche kinetics (22 ODE per cell) and NO output: see only diff
and euler devices there - so convenient for pure scaling purpose.
The graph shows the speedup for Beatbox 
compiled with the mpicc compiler option
-O3 ("optimised"), and with -O0 -g compiler
option ("non-optimized").
