We introduce a new centrality index for a bipartite network of papers and authors that we call K-index. The K-index grows with the citation performance of the papers that cite a given researcher and can seen as a measure of scientific social recognition. Indeed, the K-index measures the number of hubs, defined in a self-consistent way in the bipartite network, that cites a given author. We show...

During the liulf year ending January 31, 1911, there have been two groups of boys in a special class in Girard College, one group known as the "Retarded Class," the other as the "Delinquent Class." There were twenty-four boys in the Retarded Class and twenty-eight in the Delinquent Class. Retarded boys are those who have remained unduly long in a grade without promotion, the repeating having be...

Four experiments examined 3- and 4-year-olds' ability to communicate about containment and proximity relations. One hundred twenty-eight children either described where a miniature mouse was hiding in a dollhouse or they searched for the mouse after the experimenter described where it was hiding. The mouse was always hidden with a small landmark that was either in or next to a large landmark. W...

The concept of quasicrystals was first introduced twenty-eight years ago and, since then, over a hundred types have been discovered in the laboratory under precisely controlled physical conditions designed to avoid crystallization. Yet the original theory suggested that quasicrystals can potentially be as robust and stable as crystals, perhaps even forming naturally. These considerations motiva...

We prove that there is a one-to-one correspondence between selfdual metrics on 3CP of positive scalar curvature admitting a non-trivial Killing field but not being conformal to LeBrun metrics, and a class of normal quartic surfaces in CP whose equations can be explicitly written down. As a consequence, we show that the moduli space of these self-dual metrics on 3CP is non-empty and diffeomorphi...