707 research outputs found
Emergence of (bi)multi-partiteness in networks having inhibitory and excitatory couplings
(Bi)multi-partite interaction patterns are commonly observed in real world
systems which have inhibitory and excitatory couplings. We hypothesize these
structural interaction pattern to be stable and naturally arising in the course
of evolution. We demonstrate that a random structure evolves to the
(bi)multi-partite structure by imposing stability criterion through
minimization of the largest eigenvalue in the genetic algorithm devised on the
interacting units having inhibitory and excitatory couplings. The evolved
interaction patterns are robust against changes in the initial network
architecture as well as fluctuations in the interaction weights.Comment: 6 pages, 7 figure
Optimization of synchronizability in multiplex networks
We investigate the optimization of synchronizability in multiplex networks
and demonstrate that the interlayer coupling strength is the deciding factor
for the efficiency of optimization. The optimized networks have homogeneity in
the degree as well as in the betweenness centrality. Additionally, the
interlayer coupling strength crucially affects various properties of individual
layers in the optimized multiplex networks. We provide an understanding to how
the emerged network properties are shaped or affected when the evolution
renders them better synchronizable.Comment: 6 pages and 6 figure
Analytical results for stochastically growing networks: connection to the zero range process
We introduce a stochastic model of growing networks where both, the number of
new nodes which joins the network and the number of connections, vary
stochastically. We provide an exact mapping between this model and zero range
process, and use this mapping to derive an analytical solution of degree
distribution for any given evolution rule. One can also use this mapping to
infer about a possible evolution rule for a given network. We demonstrate this
for protein-protein interaction (PPI) network for Saccharomyces Cerevisiae.Comment: 4+ pages, revtex, 3 eps figure
Optimization of synchronizability in multiplex networks by rewiring one layer
Peer reviewedPublisher PD
Self-organized and driven phase synchronization in coupled maps
We study the phase synchronization and cluster formation in coupled maps on
different networks. We identify two different mechanisms of cluster formation;
(a) {\it Self-organized} phase synchronization which leads to clusters with
dominant intra-cluster couplings and (b) {\it driven} phase synchronization
which leads to clusters with dominant inter-cluster couplings. In the novel
driven synchronization the nodes of one cluster are driven by those of the
others. We also discuss the dynamical origin of these two mechanisms for small
networks with two and three nodes.Comment: 4 pages including 2 figure
Spectral properties and pattern selection in fractal growth networks
A model for the generation of fractal growth networks in Euclidean spaces of
arbitrary dimension is presented. These networks are considered as the spatial
support of reaction-diffusion and pattern formation processes. The local
dynamics at the nodes of a fractal growth network is given by a nonlinear map,
giving raise to a coupled map system. The coupling is described by a matrix
whose eigenvectors constitute a basis on which spatial patterns on fractal
growth networks can be expressed by linear combination. The spectrum of
eigenvalues the coupling matrix exhibits a nonuniform distribution that is
reflected in the presence of gaps or niches in the boundaries of stability of
the synchronized states on the space of parameters of the system. These gaps
allow for the selection of specific spatial patterns by appropriately varying
the parameters of the system.Comment: 9 pages, 6 Figs, Submitted to Physica
Giant lipoma: an unusual cause of carpal tunnel syndrome
Carpal tunnel syndrome, in its idiopathic form, is an extremely common entrapment neuropathy in the clinical practice however secondary compressive causes are rare. Among secondary causes, tumors are even rarer. Although lipomas are the most common soft tissue tumor in the body, <5% of the benign tumors of the hand are lipomas. A 48-year old manual laborer man presented to us with a two-year history of numbness, tingling and burning pain in the palmar surface of the left hand and fingers along with a progressively increasing swelling in the hand and wrist. His medical history was unremarkable and no trauma episode was reported. According to the clinical examination and the result of median nerve conduction study (NCS) the diagnosis of carpal tunnel syndrome was established. Operative release of the transverse carpal ligament was subsequently performed along with excision of the lipoma using extensile open approach. Intraoperatively, median nerve and its digital branches were found to be stretched over the giant lipoma causing substantial compression to median nerve. Histopathological findings of the resected mass were consistent with lipoma. After two years the patient was pain-free without any sign of tumor recurrence. Lipomas are infrequently seen in hand and wrist, however giant lipoma as a cause of secondary carpal tunnel syndrome is even more rare, which makes this case interesting.Key words: Lipoma, carpal tunnel syndrome, median nerve, nerve compressio
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