Brasselet number and Newton polygons

We present a formula to compute the Brasselet number of $f:(Y,0)\to (\C, 0)$ where $Y\subset X$ is a non-degenerate complete intersection in a toric variety $X$. As applications we establish several results concerning invariance of the Brasselet number for families of non-degenerate complete intersections. Moreover, when $(X,0) = (\mathbb{C}^n,0)$ we derive sufficient conditions to obtain the invariance of the Euler obstruction for families of complete intersections with an isolated singularity which are contained in $X$.