ar X iv : c on d - m at / 9 51 01 54 v 1 2 7 O ct 1 99 5 Power - law Distributions in the Kauffman Net

ar X iv : c on d - m at / 9 51 01 27 v 1 2 3 O ct 1 99 5 1 / f - noise in the Bak - Sneppen model

We calculate time correlation functions in the Bak-Sneppen model (Phys. Rev. Lett. 71 4083 (1993)), a model showing self-organised criticality. For a random neighbour version of the model, analytical results are presented, while on a one dimensional lattice we give numerical results. The power spectrum of these correlation functions shows 1/f-behaviour in both cases.

ar X iv : c on d - m at / 9 51 01 44 v 1 2 5 O ct 1 99 5 SPIN STIFFNESS IN THE HUBBARD MODEL

The spin stiffness ρ s of the repulsive Hubbard model that occurs in the hy-drodynamic theory of antiferromagnetic spin waves is shown to be the same as the thermodynamically defined stiffness involved in twisting the order parameter. New expressions for ρ s are derived, which enable easier interpretation , and connections with superconducting weight and gauge invariance are discussed.

ar X iv : c on d - m at / 9 51 01 12 v 1 1 9 O ct 1 99 5 Phase Diagram of the 1 D Anderson Lattice

We map out the phase diagram of the one–dimensional Anderson lattice by studying the ground state magnetization as a function of band–filling using the density matrix renormalization group technique. For strong coupling, we find that the quarter–filled system has an S=0 ground state with strong antiferromagnetic correlations. As additional electrons are put in, we find first a ferromagnetic pha...

ar X iv : c on d - m at / 9 51 01 10 v 1 1 9 O ct 1 99 5 Pinning of a solid – liquid – vapour interface by stripes of obstacles .

Pinning of a solid–liquid–vapour interface by stripes of obstacles. Abstract We use a macroscopic Hamiltonian approach to study the pinning of a solid–liquid–vapour contact line on an array of equidistant stripes of obstacles perpendicular to the liquid. We propose an estimate of the density of pinning stripes for which collective pinning of the contact line happens. This estimate is shown to b...

ar X iv : d g - ga / 9 51 00 06 v 1 2 3 O ct 1 99 5 GROUP SYSTEMS , GROUPOIDS , AND MODULI SPACES OF PARABOLIC BUNDLES