Measurement studies indicate a high rate of node dynamics in p2p systems. In this paper, we address the question of how high a rate of node dynamics can be supported by structured p2p networks. We confine our study to the hypercube routing scheme used by several structured p2p systems. To improve system robustness and facilitate failure recovery, we introduce the property of K-consistency, K ≥ 1, which generalizes consistency defined previously. (Consistency guarantees connectivity from any node to any other node.) We design and evaluate a failure recovery protocol based upon local information for K-consistent networks. The failure recovery protocol is then integrated with a join protocol that has been proved to construct K-consistent neighbor tables for concurrent joins. The integrated protocols were evaluated by a set of simulation experiments in which nodes joined a 2000-node network and nodes (both old and new) were randomly selected to fail concurrently over 10,000 seconds of simulated time. In each such "churn" experiment, we took a "snapshot" of neighbor tables in the network once every 50 seconds and evaluated connectivity and consistency measures over time as a function of the churn rate, timeout value in failure recovery, and K. Storage and communication overheads were also evaluated. We found our protocols to be effective, efficient, and stable for an average node lifetime as low as 8.3 minutes (the median lifetime measured for Napster and Gnutella was 60 minutes [10]).

Inflammatory markers are closely associated with diabetes and IFG in Chinese people. These associations appear to be stronger in women than in men. Furthermore, plasma CRP is positively associated with HbA(1c) even in euglycaemic individuals.

The fundamental goal of virtual worlds is to provide users with the illusion that they are all seeing and interacting with each other in a consistent world. State melding is the core of creating this illusion of a shared reality. It includes two major parts: consistency maintenance and state update dissemination. Welldesigned state melding technologies are also critical for developing a virtual world that can scale to a large number of concurrent users and provide satisfying user experiences. In this article, we present a taxonomy of consistency models and categorization of state update dissemination technologies for virtual worlds. To connect theories and practices, we then apply the taxonomy to case study several state-of-the-art virtual worlds. We also discuss challenges and promising solutions of state melding in large-scale virtual worlds. This survey aims to provide a thorough understanding of existing approaches and their strength and limitations and to assist in developing solutions to improve scalability and performance of virtual worlds.

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