Availability in BitTorrent Systems

2007

In this paper, we investigate the problem of highly available, massive-scale file distribution in the Internet. To this end, we conduct a large-scale measurement study of BitTorrent, a popular class of systems that use swarms of actively downloading peers to assist each other in file distribution. The first generation of BitTorrent systems used a central tracker to enable coordination among peers, resulting in low availability due to the tracker's single point of failure. Our study analyzes the prevalence and impact of two recent trends to improve BitTorrent availability: (i) use of multiple trackers, and (ii) use of Distributed Hash Tables (DHTs), both of which also help to balance load be…

An Agent-based Service Network for Personal Mobile Devices

2006

We propose the Agent Network for Bluetooth Devices, a system that uses personal mobile devices as adaptive human-environment interfaces to supply people with ad hoc information and high-level services. The ANBD system operates with a hierarchical framework of service-providing nodes, dynamically composed and managed by mobile agents.

Evaluating activator-inhibitor mechanisms for sensors coordination

2007

The possibility to employ reaction-diffusion models to build spatial patterns in sensor networks has been advocated in other works. Nevertheless it has not been investigated how the biologically-inspired solutions perform in comparison to more traditional ones taking into account specificities of sensor networks like severe energy constraints. In this paper we present some preliminary results on the comparison between a biologically inspired coordination mechanism based on activator-inhibitor interaction and a simple mechanism, where nodes do not communicate but activate their sensing circuitry according to some probability.

An Augmented Campus Design for Context-aware Service Provision

2005

This paper deals with the design of a multi-modal system for pervasive context-aware service provision and human-environment interaction in augmented environments by the use of Personal Digital Assistants (PDA) or SmartPhones. The system enables mobile devices and remote displays to perform as interaction devices with pervasive applications which run on a dynamically composed server network. Visual interaction for service setup and provision are driven by appropriate graphical interfaces and XML-based protocols, which are dynamically composed according to the type of service and to the user current position by means of a mobile agent-based framework. The paper discusses both protocols, hard…

The significance of serum soluble IL-2 receptor as a marker for active visceral leishmaniasis in Sicilian patients

1992

SUMMARY Sera from nine Sicilian patients with confirmed visceral leishmaniasis (Leishmania donovani infantum; VL), at the moment of the diagnosis, during the course of the disease and after clinical recovery, were analysed for the concentration of soluble IL-2 receptor (sIL-2R). The results show that sIL-2R is a marker of disease activity, since it is in high concentration at the beginning of infection and returns to the normal range following successful chemotherapy. At the same time of serum analysis for sIL-2R, peripheral blood mononuclear cells (PBMC) of VL patients were stimulated with phytohaemagglutinin (PHA) or antigen and supernatant tested for IL-2 and interferon-gamma (IFN-γ) pro…

Session 10 Photosynthesis

1994