Clustering data by inhomogeneous chaotic map lattices

A new approach to clustering, based on the physical properties of inhomogeneous coupled chaotic maps, is presented. A chaotic map is assigned to each data-point and short range couplings are introduced. The stationary regime of the system corresponds to a macroscopic attractor independent of the initial conditions. The mutual information between couples of maps serves to partition the data set in clusters, without prior assumptions about the structure of the underlying distribution of the data. Experiments on simulated and real data sets show the effectiveness of the proposed algorithm.Comment: 8 pages, 6 figures. Revised version accepted for publication on Physical Review Letter

Preparation of ring-shaped composite bonded magnets with continuously controlled anisotropy distribution for internal space

We have already reported an advanced method for producing a radially-anisotropic rare earth composite bonded magnet with continuously controlled direction of anisotropy. The magnet has been applied to an inner rotor as a practical usage. In this study, the outstanding preparation method was adopted into the preparation of a magnet applied for an outer rotor. An optimized condition of extrusion and compaction at an elevated temperature could be obtained. In addition, a low pressure configuration to the ring-shaped magnet from plural preformed magnets was carried out, which had specific distribution of magnetic anisotropy for internal space for a small motor, by using self recoverability based on the viscous deformation without an alignment field. No deterioration of magnetic properties was detected through the process even if those magnets were miniaturized. Resultantly, the (BH)max of a ring-shaped magnet with the continuously controlled direction of magnetic anisotropy attained the value of 186 kJ/m3, and we obtained sine-wave magnetic anisotropy distribution, even if those magnets were miniaturized.International Conference on Magnetism, ICM 2009; Karlsruhe; 26 July 2009 through 31 July 200

Modeling Connectivity in Terms of Network Activity

A new complex network model is proposed which is founded on growth with new connections being established proportionally to the current dynamical activity of each node, which can be understood as a generalization of the Barabasi-Albert static model. By using several topological measurements, as well as optimal multivariate methods (canonical analysis and maximum likelihood decision), we show that this new model provides, among several other theoretical types of networks including Watts-Strogatz small-world networks, the greatest compatibility with three real-world cortical networks.Comment: A working manuscript, 5 pages, 3 figures, 1 tabl

Exact Minimum Eigenvalue Distribution of an Entangled Random Pure State

A recent conjecture regarding the average of the minimum eigenvalue of the reduced density matrix of a random complex state is proved. In fact, the full distribution of the minimum eigenvalue is derived exactly for both the cases of a random real and a random complex state. Our results are relevant to the entanglement properties of eigenvectors of the orthogonal and unitary ensembles of random matrix theory and quantum chaotic systems. They also provide a rare exactly solvable case for the distribution of the minimum of a set of N {\em strongly correlated} random variables for all values of N (and not just for large N).Comment: 13 pages, 2 figures included; typos corrected; to appear in J. Stat. Phy

Emergent complex neural dynamics

A large repertoire of spatiotemporal activity patterns in the brain is the basis for adaptive behaviour. Understanding the mechanism by which the brain's hundred billion neurons and hundred trillion synapses manage to produce such a range of cortical configurations in a flexible manner remains a fundamental problem in neuroscience. One plausible solution is the involvement of universal mechanisms of emergent complex phenomena evident in dynamical systems poised near a critical point of a second-order phase transition. We review recent theoretical and empirical results supporting the notion that the brain is naturally poised near criticality, as well as its implications for better understanding of the brain

Installation and Test of the ATLAS Muon Endcap Trigger Chamber Electronics

For the detector commissioning planned in 2007, a sector assembly of the ATLAS muon endcap trigger chambers is being progressed in CERN. Final technical test of the electronics mounted on a sector must be made at this stage. For systematic test of the electronics (sector test), we have developed a DAQ system on top of the ATLAS online software framework. The system is not dedicated only for this test, but can be used also for the front-end detector part of the overall ATLAS DAQ system. In the presentation, the procedure, meaning and results of the sector test are discussed after brief introduction of the TGC electronics and the sector structure as a construction unit. We introduce plans of further detailed and elaborated tests for the whole system using cosmic ray and single halo muons when all the TGC sub-detector part is completed as concluding remark