Abstract. BitTorrent is one of the Internet's most efficient content distribution protocols. It is known to perform very well over the wired Internet where end-to-end performance is almost guaranteed. However, in wireless ad hoc networks, many constraints appear as the scarcity of resources and their shared nature, which make running BitTorrent with its default configuration not lead to best performances. To these constraints it adds the fact that peers are both routers and end-users and that TCP-performance drops seriously with the number of hops. We show in this work that the neighbor selection mechanism in BitTorrent plays an important role in determining the performance of the protocol when deployed over a wireless ad hoc network. It is no longer efficient to choose and treat with peers independently of their location. A first solution is to limit the scope of the neighborhood. In this case, TCP connections are fast but there is no more diversity of pieces in the network: pieces propagate in a unique direction from the seed to distant peers. This prohibits peers from reciprocating data and leads to low sharing ratios and suboptimal utilization of network resources. To recover from these impairments, we propose an enhancement to BitTorrent which aims to minimize the time to download the content and at the same time to enforce cooperation among peers. Our solution considers a restricted neighborhood to reduce routing overhead and to improve throughput, while establishing few connections to remote peers to improve diversity of pieces. With the help of extensive NS-2 simulations, we show that these enhancements to BitTorrent significantly improve the file completion time while fully profiting from the incentives implemented in BitTorrent to enforce fair sharing.

Glomus tumors are uncommon benign tumors developing from the neuro-myo-arterial glomus body. They are typically located in the fingers. The extra-digital involvement is unusual and makes diagnosis difficult. Only few cases have been reported in literature. We report an exceptional case of a glomus tumor of the lower leg in a 65-year-old male. The diagnosis was clinically suspected and confirmed by a biopsy. Surgical excision gave immediate pain relief. The aim of this report is to make the surgical community more aware of this entity based on the analysis of our own experience and a review of the literature.

Lipoma is a relatively frequent, benign soft-tissue tumor rarely located in the hand. A lipoma of the hand causing a carpal tunnel syndrome by compression of the median nerve is exceptional. We report the case of a 70-year-old female presenting with a carpal tunnel syndrome. A compression of the median nerve by a lipoma was discovered during surgery. Transverse carpal ligament release with lipoma excision and neurolysis of the median nerve were performed. Histopathological study of the resected mass was consistent with a lipoma. Two-month postoperatively, the patient recovered full hand function with entire disappearance of acroparesthesia. Carpal tunnel syndrome caused by space occupying lesions is rare. Diagnosis is difficult, usually based on the clinical study, electrophysiology and magnetic resonance imaging (MRI). Transverse carpal ligament release and excision of lipoma provides excellent functional recovery.

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