The degree resistance distance of cacti

Graph invariants, based on the distances between the vertices of a graph, are widely used in theoretical chemistry. The degree resistance distance   of a graph GG is defined as DR(G)=∑{u,v}⊆V(G)[d(u)+d(v)]R(u,v)DR(G)=∑{u,v}⊆V(G)[d(u)+d(v)]R(u,v), where d(u)d(u) is the degree of the vertex uu, and R(u,v)R(u,v) the resistance distance between the vertices uu and vv. Let Cact(n;t)Cact(n;t) be the set of all cacti possessing nn vertices and tt cycles. The elements of Cact(n;t)Cact(n;t) with minimum degree resistance distance are characterized.