Finding the core members of a virtual community is an important problem in community analysis. Here we presented an simulated annealing algorithm to solve this problem by optimizing the user interests concentration ratio in user groups. As an example, we test this algorithm on a virtual community

decades has focused on how Governments, organisations and individuals make decisions when faced with difÞcult choices, particularly those involving risk. This work has ranged over nuclear waste, ßood control, food safety, transport safety and environmental protection, as well as aspects of public life including sport and leisure and childrenÕs play. For further information visit www.mdx.ac.uk/risk/.

Cracking the core:

for this state of affairs is that existing theories of work The authors express great appreciation to members of the consulting firm that helped us gain access to the organizations where this research was conducted; to Kenneth Brousseau, Daniel Feldman, and Linda Frank for assistance in data collection

In this series of lectures we introduce the projective line over a Jordan system. This can be seen as a generalization of the projective line over a ring. A Jordan system is a substructure of a ring (or an algebra) which is closed with respect to addition (and scalar multiplication) and inversion. Standard examples are special Jordan algebras. A Jordan system can also be seen as a special case of a Jordan pair. We present examples of all these algebraic structures. Moreover, we present, as an associated geometric structure, the projective line over a Jordan system. This projective line naturally appears in the theory of chain geometries: The point set of a chain geometry is the projective line over a K-algebra A (with K a field), and the chains of this geometry are the K-sublines. Each Jordan system J contained in A gives rise to a subgeometry of the chain geometry, with point set the projective line over J. Under certain geometric conditions on the chain geometry, this can be reversed: Each subgeometry can be described with the help of a Jordan system J in A. As an example we study the geometry of points and circles on a non-degenerate quadric in a projective space over K. This can be described as a subgeometry of the chain geometry over an associated Clifford algebra C by finding a suitable Jordan system J in C. Moreover, we study morphisms of the algebraic and the geometric structures under consideration. A series of three lectures to be given on August 21, 22 and 24, 2009.

This paper presents DONet, a Data-driven Overlay Network for live media streaming. The core operations in DONet are very simple: every node periodically exchanges data availability information with a set of partners, and retrieves unavailable data from one or more partners, or supplies available

. Structural properties are determined by the graph structure of the network. These structural properties are used for locating and isolating core members by using importance ranking score and thereby analyzing the effect to remove these members in terrorist networks. The discussion is supported with a case

in the life of the network. Our measurements expose a surprising segmentation of these networks into three regions: singletons who do not participate in the network; isolated communities which overwhelmingly display star structure; and a giant component anchored by a well-connected core region which persists

) analyzing the characteris-tics of the terrorist organization, and proposing an algorithm called Create Vir-tual Community (CVC) based on tree-structure to create a virtual community; (3) proposing a formal definition of Virtual Community (VC) and the VCCM Mining algorithm to mine the core members of a

This study investigates how hard-core members of two non-brand focused consumption-oriented subcultures enact their iden-tities. The authors analyzed data collected from prolonged investi-gations of the North American organized distance running subcul-ture and the Australian Hip Hop culture