We investigate the range of inflationary universe models driven by scalar fields possessing a general interaction potential of the form V (φ) = V0φ n exp(−λφm). Power-law, de Sitter and intermediate inflationary universes emerge as special cases together with several new varieties of inflation. Analysing the behaviour of these models at the extrema of φ we derive sufficient constraints on the m...

The local level model with stochastic volatility, recently proposed for U.S. by Stock and Watson (Why Has U.S. Inflation Become Harder to Forecast?, Journal of Money, Credit and Banking, Supplement to Vol. 39, No. 1, February 2007), provides a simple yet sufficiently rich framework for characterizing the evolution of the main stylized facts concerning the U.S. inflation. The model decomposes in...

In this paper, we study the evolution of the Internet topology over the last three years. We study the evolution at three different levels: a) each node individually, b) the network as a whole, c) the path level. First, we find that the degrees of the nodes increase in a “rich get richer” fashion: the increase is proportional to the degree of the node. Second, we identify that new edges prefer ...

We calculate the NAIRU for the U.S. in a framework where inflation and the unemployment rate can respond to each other. The NAIRU is defined as the component of the actual unemployment rate that is uncorrelated with inflation in the long run. Using a structural VAR approach, the NAIRU and core inflation can be estimated simultaneously. Our estimation results show that the NAIRU falls dramatical...