The role of competition in structuring primate communities under different productivity regimes in the Amazon

The factors responsible for the formation of Amazonian primate communities are not well understood. Here we investigated the influence of interspecific competition in the assembly of these communities, specifically whether they follow an assembly rule known as "favored states". According to this rule, interspecific competition influences final species composition, resulting in functional groups that are equally represented in the community.We compiled presence-absence data for primate species at 39 Amazonian sites in Brazil, contrasting two regions with distinct productivity regimes: the eutrophic Juruá River basin and the oligotrophic Negro River basin. We tested two hypotheses: that interspecific competition is a mechanism that influences the structure of Amazonian primate communities, and that competition has had a greater influence on the structure of primate communities in regions with low productivity, where resources are more limited. We used null models to test the statistical significance of the results, and found a non-random pattern compatible with the favored states rule in the two regions. Our findings suggest that interspecific competition is an important force driving primate community assembly regardless of productivity regimes

Decentralizing volunteer computing coordination

This paper attempted to decentralize volunteer computing (VC) coordination with the goal of reducing the reliance on a central coordination server, which had been criticized for performance bottleneck and single point of failure. On analyzing the roles and functions that the VC components played for the centralized master/worker coordination model, this paper proposed a decen-tralized VC coordination framework based on distributed hash table (DHT) and peer-to-peer (P2P) overlay and then successfully mapped the centralized VC coordination into distributed VC coordination. The proposed framework has been implemented on the performance-proven DHT P2P overlay Chord. The initial verification has demonstrated the effectiveness of the framework when working in distributed environments

Decentralizing volunteer computing coordination

This paper attempted to decentralize volunteer computing (VC) coordination with the goal of reducing the reliance on a central coordination server, which had been criticized for performance bottleneck and single point of failure. On analyzing the roles and functions that the VC components played for the centralized master/worker coordination model, this paper proposed a decen-tralized VC coordination framework based on distributed hash table (DHT) and peer-to-peer (P2P) overlay and then successfully mapped the centralized VC coordination into distributed VC coordination. The proposed framework has been implemented on the performance-proven DHT P2P overlay Chord. The initial verification has demonstrated the effectiveness of the framework when working in distributed environments

Achieving dynamic workload balancing for P2P Volunteer Computing

This paper argues that the decentralization feature of Peer-to-Peer (P2P) overlay is more suitable for Volunteer Computing (VC), compared to the centralized master/worker structure in terms of performance bottleneck and single point of failure. Based on the P2P overlay Chord, this paper focused on the design of a workload balancing protocol to coordinate VC. The goal of the protocol was to maximize overall speed-up against the heterogeneity and churn of volunteers. The roles of a facilitator and volunteers (peers) were defined; the key components were designed, including job, result and container. Distributed workload balancing algorithms were proposed to direct the workflow of the key roles for joining and leaving, job search and distribution and result collection. Criteria and metrics were proposed to evaluate the algorithms in regards to the effectiveness against churn and the overall speed-up against number of volunteers. Simulations were devised and completed upon the N-Queen Problem to measure these qualities. Conclusions confirmed that the results were on the right track