arXiv subjects

Eytan Domany

Publications and source records attributed to Eytan Domany.

45 records · Page 3Linked to original sources

arXiv1997

Ostwald Ripening in Two Dimensions: Treatment with Pairwise Interactions

We present a systematic extension of mean field models for Ostwald ripening in two dimensions. We derived, using a mean field type approximation, an analytic expression for pairwise interactions between the minority phase droplets. These interactions appear in dynamic equations for the droplets' radii and positions, which are solved numerically for systems of tens of thousands of droplets, yielding very good agreement with recent experiments.

cond-mat.stat-mech↗

arXiv1997

Ostwald ripening in Two Dimensions: Correlations and Scaling Beyond Mean Field

We present a systematic quasi-mean field model of the Ostwald ripening process in two dimensions. Our approach yields a set of dynamic equations for the temporal evolution of the minority phase droplets' radii. The equations contain only pairwise interactions between the droplets; these interactions are evaluated in a mean- field type manner. We proceed to solve numerically the dynamic equations for systems of tens of thousands of interacting droplets. The numerical results are compared with the experimental data obtained by Krichevsky and Stavans for the relatively large volume fraction $ϕ=0.13$. We found good agreement with experiment even for various correlation functions.

cond-mat.stat-mech↗

arXiv1997

Recovery of Protein Structure from Contact Maps

We present an efficient algorithm to recover the three dimensional structure of a protein from its contact map representation. First we show that when a physically realizable map is used as target, our method generates a structure whose contact map is essentially similar to the target. Furthermore, the reconstructed and original structures are similar up to the resolution of the contact map representation. Next we use non-physical target maps, obtained by corrupting a physical one; in this case our method essentially recovers the underlying physical map and structure. Hence our algorithm will help to fold proteins, using dynamics in the space of contact maps. Finally we investigate the manner in which the quality of the recovered structure degrades when the number of contacts is reduced.

cond-mat.soft↗

arXiv1997

Damage Spreading in the Ising Model

We present two new results regarding damage spreading in ferromagnetic Ising models. First, we show that a damage spreading transition can occur in an Ising chain that evolves in contact with a thermal reservoir. Damage heals at low temperature and spreads for high T. The dynamic rules for the system's evolution for which such a transition is observed are as legitimate as the conventional rules (Glauber, Metropolis, heat bath). Our second result is that such transitions are not always in the directed percolation universality class.

cond-mat.stat-mech↗

arXiv1997

Data clustering using a model granular magnet

We present a new approach to clustering, based on the physical properties of an inhomogeneous ferromagnet. No assumption is made regarding the underlying distribution of the data. We assign a Potts spin to each data point and introduce an interaction between neighboring points, whose strength is a decreasing function of the distance between the neighbors. This magnetic system exhibits three phases. At very low temperatures it is completely ordered; all spins are aligned. At very high temperatures the system does not exhibit any ordering and in an intermediate regime clusters of relatively strongly coupled spins become ordered, whereas different clusters remain uncorrelated. This intermediate phase is identified by a jump in the order parameters. The spin-spin correlation function is used to partition the spins and the corresponding data points into clusters. We demonstrate on three synthetic and three real data sets how the method works. Detailed comparison to the performance of other techniques clearly indicates the relative success of our method.

cond-mat.dis-nn↗

arXiv1997

What the survivors' areas do at long times?

We investigate the long time behavior of the survivors' area in the scaling state of two dimensional soap froth. We relate this problem to the recently studied temporal decay of the fraction of Potts spins that have never been flipped till time t. The results of our topological simulations are consistent with the value $θ=1$ for the scaling exponent of the survivors' areas, in agreement with a recently obtained analytical result. We find, however, that the relaxation time needed to get into the scaling regime depends on the degree of randomness in the topological rearrangements and becomes very large in the deterministic limit.

cond-mat.stat-mech↗

arXiv1996

An Objective Definition of Damage Spreading - Application to Directed Percolation

We present a general definition of damage spreading in a pair of models. Using this general framework, one can define damage spreading in an objective manner, that does not depend on the particular dynamic procedure that is being used. The formalism is applied to the Domany-Kinzel cellular automaton in one dimension; the active phase of this model is shown to consist of three sub-phases, characterized by different damage-spreading properties.

cond-mat.stat-mech↗

arXiv1995

Search for Kosterlitz-Thouless transition in a triangular Ising antiferromagnet with further-neighbour ferromagnetic interactions

We investigate an antiferromagnetic triangular Ising model with anisotropic ferromagnetic interactions between next-nearest neighbours, originally proposed by Kitatani and Oguchi (J. Phys. Soc. Japan {\bf 57}, 1344 (1988)). The phase diagram as a function of temperature and the ratio between first- and second- neighbour interaction strengths is thoroughly examined. We search for a Kosterlitz-Thouless transition to a state with algebraic decay of correlations, calculating the correlation lengths on strips of width up to 15 sites by transfer-matrix methods. Phenomenological renormalization, conformal invariance arguments, the Roomany-Wyld approximation and a direct analysis of the scaled mass gaps are used. Our results provide limited evidence that a Kosterlitz-Thouless phase is present. Alternative scenarios are discussed.

cond-mat↗

arXiv1995

Topological model of soap froth evolution with deterministic T2-processes

We introduce a topological model for the evolution of 2d soap froth. The topological rearrangements (T2 processes) are deterministic (unlike the standard stochastic model): the final topology depends on the areas of the neighboring cells. The new model gives agreement with experiments in the transient regime, where the previous models failed qualitatively, and also improves agreement in the scaling state.

cond-mat↗