Model and on the value of the HB exponent. In addition, the dependence of the magnitude of the stress overshoot Δ on µ$_{2}$ ( A ) will be investigated as it is critical to our understanding of its role as a mechanism for shear local- isation. It will be of interest to observe what happens to the location of the shear-band for samples with higher µ$_{2}$ ( A ), in light of the results published in [33]. We also intend to compare our VF simulations with simulations using the Soft Disk Model [24]. 

The author would like to acknowledge IRCSET Embark for funding this project. IITAC, the HEA, the National Development Plan and the Trinity Centre for High Per- formance Computing are acknowledged for the use of the computing facilities at TCD. S.J. Cox, Aberystwyth is thanked for his useful input and correspondence in rela- tion to this work. This publication has emerged from re- search conducted with the financial support of the Euro- pean Space Agency (MAP AO-99-108:C14914/02/NL/SH and AO-99-075:C14308/00/NL/SH). This material is based upon works supported by the Science Foundation Ire- land under Grant No. (08/RFP/MTR1083 and STTF 08). We would also like to thank the anonymous referees whose input helped greatly in improving the quality of this manuscript. 

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