Quantum Monte Carlo calculations of the relaxation energy, pair-correlation function, and annihilating-pair momentum density are presented for a positron immersed in a homogeneous electron gas. We find smaller relaxation energies and contact pair-correlation functions in the important low-density regime than predicted by earlier studies. Our annihilating-pair momentum densities have almost zero...

We introduce a new model of correlated randomly growing graphs and study the fundamental questions detecting correlation estimating aspects structure. The is simple starts with any graphs, such as uniform attachment (UA) or preferential (PA). Given model, pair (G1,G2) grown in two stages: until time t⋆ they are together (i.e., G1=G2), after which grow independently according to underlying growt...

one of the most visible aspects of a forest stand structure is the spatial patterns of trees. competition affects on forest structure and its understanding is important, when the purpose of forest management is to imitate the dynamic of natural ecosystems. for this purpose, an unmanaged intact forest was selected with 26 hectares area. all chestnut leaf oak (quercus castaneifolia) trees with a ...