We design a peer-to-peer technique called ZIGZAG for single-source media streaming. ZIGZAG allows the media server to distribute content to many clients by organizing them into an appropriate tree rooted at the server. This applicationlayer multicast tree has a height logarithmic with the number of clients and a node degree bounded by a constant. This helps reduce the number of processing hops on the delivery path to a client while avoiding network bottleneck. Consequently, the end-to-end delay is kept small. Although one could build a tree satisfying such properties easily, an efficient control protocol between the nodes must be in place to maintain the tree under the effects of network dynamics and unpredictable client behaviors. ZIGZAG handles such situations gracefully requiring a constant amortized control overhead. Especially, failure recovery can be done regionally with little impact on the existing clients and mostly no burden on the server. 0-7803-7753-2/03/$17.00 (C) 2003 IEEE

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Objective To estimate bias associated with partial mouth periodontal examination (PMPE) protocols regarding estimates of prevalence, severity and extent of clinical attachment loss (CAL), pocket depth (PD) and gingival recession (REC). Material and Methods A search was made for articles published in English, from 1946–2012, which compared PMPE vs. full mouth periodontal examination (FMPE) protocols for CAL or PD ≥ 4mm or REC ≥ 3mm thresholds. PMPE protocols were evaluated for sensitivity of estimates of periodontitis prevalence, relative biases for severity and extent estimates. Results A review of the literature identified 12 studies which reported 32 PMPE protocols. Three PMPE protocols which had sensitivities ≥ 85% and relative biases ≤ 0.05 in absolute values for severity and extent estimates were: 1) half mouth six-sites, 2) diagonal quadrants six-sites and 3) full mouth mesiobuccal-midbuccal-distobuccal (MB-B-DB). Two other PMPE protocols (full mouth and half mouth mesiobuccal-midbuccal-distolingual) performed well for prevalence and severity of periodontitis; however, their performance in estimates of extent was unknown. Conclusions Among the 32 PMPE protocols listed, the half-mouth six-sites and full-mouth MB-B-DB protocols had the highest sensitivities for prevalence estimates and lowest relative biases for severity and extent estimates.