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Abstract-In the past few years, several DHT-based abstractions for peer-to-peer systems have been proposed. The main characteristic is to associate nodes (peers) with keys (objects) and to construct distributed routing structures to support an efficient location. These approaches address the load problem, and load balancing is achieved by moving the keys. However, the problem is still not properly covered. In this paper we present an analysis of structured peer-to-peer systems taking into consideration Zipf-like requests distribution. Based on our analysis, we propose a novel approach for load balancing relying on object popularity. Our approach is based on routing table reorganization in order to balance the lookup traffic load. We have implemented this approach in a Pastry-like system. The obtained results demonstrate a better balance of load, which can lead to improved scalability and performance.

Abstract-In the past few years, several DHT-based abstractions for peer-to-peer systems have been proposed. The main characteristic is to associate nodes (peers) with objects (keys) and to construct distributed routing structures to support efficient location. These approaches partially consider the load problem by balancing storage of objects without, however, considering lookup traffic. In this paper we present an analysis of structured peer-to-peer systems taking into consideration Zipf-like requests distribution. Based on our analysis, we propose a novel approach for load balancing taking into account object popularity. It is based on dynamic routing table reorganization in order to balance the routing load and on caching objects to balance the request load. We can therefore significantly improve the load balancing of traffic in these systems, and consequently their scalability and performance. Results from experimental evaluation demonstrate the effectiveness of our approach.

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Abstract. Under frequent node arrival and departure (churn) in an overlay network structure, the problem of preserving accessibility is addressed by maintaining valid entries in the routing tables towards nodes that are alive. However, if the system fails to replace the entries of dead nodes with entries of live nodes in the routing tables soon enough, requests may fail. In such cases, mechanisms to route around failures are required to increase the tolerance to node failures. Existing Distributed Hash Tables (DHTs) overlays include extensions to provide fault tolerance when looking up keys, however, these are often insufficient. We analyze the case of greedy routing, often preferred for its simplicity, but with limited dependability even when extensions are applied. The main idea is that fault tolerance aspects need to be dealt with already at design time of the overlay. We thus propose a simple overlay that offers support for alternative paths, and we create a routing strategy which takes advantage of all these paths to route the requests, while keeping maintenance cost low. Experimental evaluation demonstrates that our approach provides an excellent resilience to failures.

Abstract

Objective: We aim to evaluate the potential interaction of two insect hemolymph peptides, MDF3 and MDF4, with the human androgen receptor, on the premise that the proliferative effects of the two peptides are (at least in part) a consequence of AR binding. Methods: We employed a bioinformatic approach for the prediction of protein-peptide interaction and peptide aggregation, using various in silico on-line tools such as docking servers, aggregation prediction servers and visualization and analysis software in order to evaluate our results. Results: Our evaluation indicates that MDF3 and MDF4 interact with the androgen human androgen receptor by binding to a helix shown to be involved the receptor dimerization. Out of the two peptides, MDF3 appears to form a more extensive bond network with the receptor. Conclusion: Our analysis indicates that MDF 3 and 4 may be able to activate the human androgen receptor and warrant further investigation of the potential effect on receptor function. MDF3 appears to be the most promising out of the two peptides and its interaction should be further evaluated by both computational and experimental methods.