In this paper, we discuss the nonuniform exponential dichotomy properties of nonautonomous systems of linear differential equations. Since any linear differential systems are kinematically similar to a triangular system, considering the relation between the nonuniform exponential dichotomy properties of the triangular system is necessary. Without loss of generality, we consider block upper triangular systems and give the criteria for the nonuniform exponential dichotomy of triangular systems on the half line for unbounded systems.

The aim of this paper is to investigate results on almost sure convergence of weighted sums of coordinatewise pairwise negatively quadrant dependent random variables taking values in Hilbert spaces. As an application, the almost sure convergence of degenerate von Mises-statistics is investigated. Keywords: Negative quadrant dependence, Hilbert spaces, Weighted sums, Strong laws of large numbers.