A edge 2-rainbow dominating function (E2RDF) of a graph G is a ‎function f from the edge set E(G) to the set of all subsets‎ ‎of the set {1,2} such that for any edge.......................

The basic principles of positron annihilation physics are briefly discussed and the three most important experimental techniques used for bulk studies are described (i.e. positron lifetime, angular correlation, Doppler broadening). Several examples of the use of the positron methods are discussed for metals, ceramics and molecular materials, which illustrate the sensitivity of the positron anni...

Since Zwicky proposed the problem of the ‘‘missing mass’’ in 1933, a lot of theoretical and experimental effort has been made in order to unveil the nature of dark matter. Today, WMAP has provided very accurate data regarding the matter density in the Universe [1]. The energy density of the Universe is composed of 4% atoms and roughly 22% dark matter. Data from recent observations indicate that...