without doubt is one important aspects of sustainable forest management the continuing forest regeneration. identify and determine is effective dispersal and distribution pattern of regeneration patches in various types of forest and its evolution, in maintaining biodiversity in natural ecosystems. purpose was chosen of gorazbon district kheyrod forest for study, all patches regeneration were l...

This paper studies several aspects of asymptotically hyperbolic Einstein metrics, mostly on 4-manifolds. We prove boundary regularity (at infinity) for such metrics and establish uniqueness under natural conditions on the boundary data. By examination of explicit black hole metrics, it is shown that neither uniqueness nor finiteness holds in general for AH Einstein metrics with a prescribed con...

We discuss pseudo-Riemannian metrics on 2-dimensional manifolds such that the geodesic flow admits a nontrivial integral quadratic in velocities. We construct (Theorem 1) local normal forms of such metrics. We show that these metrics have certain useful properties similar to those of Riemannian Liouville metrics, namely: • they admit geodesically equivalent metrics (Theorem 2); • one can use th...

human activities induced changes in land cover/use have extensive impacts on the landscape. in recent years, these changes had an increasingly growth due to irrational use of the natural resources in iran. hence, considering the negative effects of the inappropriate use of land and land-use change, understanding of the landscape changes over time is necessary to planning and implementation of s...