Chains, trains and contractile fields

Unimodal wave trains and solitons in convex FPU chains

We consider atomic chains with nearest neighbour interactions and study periodic and homoclinic travelling waves which are called wave trains and solitons, respectively. Our main result is a new existence proof which relies on the constrained maximisation of the potential energy and exploits the invariance properties of an improvement operator. The approach is restricted to convex interaction p...

Attosecond pulse trains generated using two color laser fields.

We investigate the spectral and temporal structure of high harmonic emission from argon exposed to an infrared laser field and its second harmonic. For a wide range of generating conditions, trains of attosecond pulses with only one pulse per infrared cycle are generated. The synchronization necessary for producing such trains ensures that they have a stable pulse-to-pulse carrier envelope phas...

From Markov Chains to Gibbs Fields

Exponentiation Using Addition Chains for Finite Fields

Bruen chains over fields of small order

We extend the classi cation of the Bruen chains to all elds of order at most 49, by showing the non-existence of Bruen chains over the elds of order 41, 43, 47 and 49. c © 2004 Elsevier B.V. All rights reserved.