Until now, depletion induced transitions have been the hallmark of multicomponent systems only. Monte Carlo simulations reveal a depletion-induced phase transition from cluster vapor to cluster solid in a one-component uid with competing short range and long range interactions. This con rms a prediction made by earlier theoretical work. Analysis of renormalized cluster-cluster and clustervapor ...

Recent simulations of diffusion limited cluster-cluster aggregation (DLCA) have shown systematic inhomogeneities in the shape and orientation of clusters formed when a sedimentary force is applied. Using custom simulation and visualisation techniques and programs we have carried out a microscopic study of these sedimentary inhomogeneities and have mapped out the model parameter space. We find v...

We present two projects related to interaction in the Virgo cluster. In the first section we draw a quantitative comparison of the distribution of the galaxies and the intra-cluster gas taking into account that the Virgo cluster has an irregular structure consisting of several subclusters. In the second section we show hydrodynamic simulations of the interaction (ram pressure stripping) of a ga...

The structure and aggregation kinetics of three-dimensional clusters composed of two different monomeric species at three concentrations are thoroughly investigated by means of extensive, large-scale computer simulations. The aggregating monomers have all the same size and occupy the cells of a cubic lattice. Two bonding schemes are considered: (a) the binary diffusion-limited cluster-cluster a...

Metal-poor globular clusters (MPGCs) are a unique probe of the early universe, in particular the reionization era. A popular hypothesis is that the observed truncation of MPGC formation is due to reionization. Under this hypothesis, constraining the formation epoch of MPGCs provides a complementary constraint on the epoch of reionization. Moreover, as the earliest reionizing sources first forme...

A general correction term in the radius of gyration ~caling law is discussed. The work incorporates the finite size effect considered by Ball and Jullien (J. Ph_»s. Left. Fiance 45 (1984) L1031j and is a potentially useful extension of their analysis to polydisperse systems. Numerical simulations verify these re~ults for one particular model, and demonstrate the remarkable

Stability in cluster analysis is strongly dependent on the data set, especially on how well separated and how homogeneous the clusters are. In the same clustering, some clusters may be very stable and others may be extremely unstable. The Jaccard coefficient, a similarity measure between sets, is used as a clusterwise measure of cluster stability, which is assessed by the bootstrap distribution...

In this paper, we introduce a notion of unistructural cluster algebras, for which the set of cluster variables uniquely determines the clusters. We prove that cluster algebras of Dynkin type and cluster algebras of rank 2 are unistructural, then prove that if A is unistructural or of Euclidean type, then f : A → A is a cluster automorphism if and only if f is an automorphism of the ambient fiel...

Radio continuum emission at 1.4 GHz was used to identify active galaxies in a sample of 20 nearby Abell clusters. The radio emission indicates either an active galactic nucleus or current star formation, and optical spectroscopy was used to evaluate which of these dominates for each of the radio-selected galaxies. In an analysis which parallels the blue fractions of Butcher-Oemler studies, we c...

It is proved that any cluster-tilted algebra defined in the cluster category C(H) has the same representation type as the initial hereditary algebra H . For any valued quiver (Γ,Ω), an injection from the subset PI(Ω) of the cluster category C(Ω) consisting of indecomposable preprojective objects, preinjective objects and the first shifts of indecomposable projective modules to the set of cluste...