The inflaton potential in four-dimensional theory is rather arbitrary, and fine-tuning is required generically. By contrast, inflation in the brane world scenario has the interesting feature that the inflaton potential is motivated from higher dimensional gravity, or more generally, from bulk modes or string theory. We emphasize this feature with examples. We also consider the impact on the spe...

In electric circuit theory, it is of great interest to compute the effective resistance between any pair of vertices of a network, as well as the Kirchhoff index. During the past decade these parameters have been applied in organic chemistry as natural structural indexes different from the usual ones in order to achieve an improvement in the discrimination between different molecules that have ...

We review two clustering algorithms (hard c-means and single linkage) and three indexes of crisp cluster validity (Hubert's statistics, the Davies-Bouldin index, and Dunn's index). We illustrate two deficiencies of Dunn's index which make it overly sensitive to noisy clusters and propose several generalizations of it that are not as brittle to outliers in the clusters. Our numerical examples sh...

OBJECTIVE To provide guidance on selecting the most appropriate price index for adjusting health expenditures or costs for inflation. DATA SOURCES Major price index series produced by federal statistical agencies. STUDY DESIGN We compare the key characteristics of each index and develop suggestions on specific indexes to use in many common situations and general guidance in others. DATA C...

W hat is today’s big monetary policy issue? It is, surely, the extraordinary volatility of the financial markets and the wide quality spreads that opened up between riskier bonds and Treasury bonds following the Russian default in mid-August 1998. No one forecast these problems; the financial-market upset certainly was not a real, live policy issue back in the spring and early summer. We should...