let r be a fnite commutative ring and n(r) be the set of non unit elements of r. the non unit graph of r, denoted by gamma(r), is the graph obtained by setting all the elements of n(r) to be the vertices and defning distinct vertices x and y to be adjacent if and only if x - yin n(r). in this paper, the basic properties of gamma(r) are investigated and some characterization results regarding co...

DTI tractography allows unprecedented understanding of brain neural connectivity in-vivo by capturing water diffusion patterns in brain white-matter microstructures. However, tractography algorithms often output hundreds of thousands of fibers, rendering the computation needed for subsequent data analysis intractable. A remedy is to group the fibers into bundles using fiber clustering technique...

This paper presents an architecture and protocol in support of seamless mobility for future IP Radio Access Networks (IPRANs). It encompasses a novel approach for seamless handoff and proactive relocation of IP roaming state. The latter establishes a generic substrate for proactive state relocation of different context classes relating to the state of IP connectivity for a mobile node (MN). To ...

Significant research effort has been devoted to the topological features of complex networks to enhance the performance of dynamic processes implemented on these networks. In this work, we investigate how to optimize a network for a given dynamic process via a minor topological modification. The algebraic connectivity a(G) of a network G characterizes the performance of e.g. synchronization of ...

The authors previously published an iterative process to generate a class of projectiveplanarK3,4-free graphs called ‘patch graphs’. They also showed that any simple, almost 4-connected, nonplanar, and projective-planar graph that is K3,4-free is a subgraph of a patch graph. In this paper, we describe a simpler and more natural class of cubic K3,4free projective-planar graphs which we call Möbi...

Cellular communications are aligning rapidly to adopt suitable network models for supporting packet switched services over IP networks. Pure third generation (3G) wireless architectures have already adopted IP as the network layer bearer within their core network component specification. This article presents an architecture and protocol in support of proactive mobility management for future IP...

Parasites exert a major impact on the eco-evolutionary dynamics of their hosts and the associated biotic environment. Migration constitutes an effective means for long-distance invasions of vector-borne parasites and promotes their rapid spread. Yet, ecological and spatial information on population-specific host-parasite connectivity is essentially lacking. Here, we address this question in a s...

The contact vector (CV) of a protein structure is one of the simplest and most condensed descriptions of protein structure available. It lists the number of contacts each amino acid has with the surrounding structure and has frequently been used e.g. to derive approximative folding energies in protein folding analysis. The CV, however, is a lossy structure representation, as it does not contain...

A graph is said to be P 4-connected if for every partition of its vertex-set into two nonempty disjoint sets, some P 4 in the graph has vertices from both sets in the partition. A P 4-chain is a sequence of vertices such that every four consecutive ones induce a P 4. The main result of this work states that a graph is P 4-connected if and only if each pair of vertices is connected by a P 4-chai...

We prove that, if M is a weakly 4-connected matroid with |E(M)| 7 and neither M nor M∗ is isomorphic to the cycle matroid of a ladder, then M has a proper minor M ′ such that M ′ is weakly 4-connected and |E(M ′)| |E(M)| − 2 unless M is some 12-element matroid with a special structure. © 2007 Elsevier Inc. All rights reserved.