Lake Baikal is affected by global change and regional human activities. The effects of rising temperature and pollution on the unique endemic littoral amphipod fauna of Lake Baikal are unresolved yet. This thesis provides insights into physiological processes determining thermal tolerance and cadmium (Cd) susceptibility in two littoral amphipod species (Eulimnogammarus verrucosus and Eulimnogammarus cyaneus) compared to the related gammarid Gammarus lacustris, which is ubiquitously spread in the Holarctic. Thermal constraints on the oxygen supply system in E. verrucosus, E. cyaneus and G. lacustris may shape the upper temperature limits to the thermal habitats of the species, in line with the theories of allometry of thermal tolerance and systemic to molecular hierarchy of thermal tolerance. Lethal concentrations of Cd were much lower for E. cyaneus and G. lacustris than for E. verrucosus. However, E. verrucosus showed metabolic depression when exposed to Cd concentrations far below lethal ones. These findings underscore the necessity of water management strategies strictly avoiding chemical contamination of Lake Baikal waters

Jakob, Lena

English

Voice over Internet Protocol (VoIP), also called IP telephony is rapidly becoming a familiar term and as a technology it is invading the enterprise, private usage, and educational and government organizations. Exploiting advanced voice coding &amp; compression techniques and bandwidth sharing over packet switched networks, VoIP can dramatically improve bandwidth efficiency. Moreover enhanced security features, mobility support, and cost reduction features of VoIP are making it a popular choice for personal communication. Due to its rapid growth in popularity VoIP is rapidly becoming the next generation phone system. Lawful interception is a mean of monitoring private communication of users that are suspected of criminal activities or to be a threat to national security. However, government regulatory bodies and law enforcement agencies are becoming conscious of the difficulty of lawful interception of public communication due to the mobilitysupport and advanced security features implemented in some implementations of VoIP technology. There has been continuous pressure from the government upon the operators and vendors to find a solution that would make lawful interception feasible and successful. Key escrow was proposed as a solution by the U. S. National Security Agency. In key escrow the key(s) for a session are entrusted to a trusted third party and upon proper authorization law enforcement agencies can receive the session key(s) from this trusted third party However, key escrow adds some security vulnerabilities and potential risks as an unethical employee of the key escrow agent (or a law enforcement agency that has received the session key(s)) can misuse the key(s) to forge content of a communication session -- as he or she possesses the same key(s) as the user used for this session. This thesis addresses the issue of forged session content, by proposing, implementing, and evaluating a cryptographic model which allows key escrow session content. The implementation utilizes an existing implementation of a Session Initiation Protocol (SIP) user agent ‘minisip’ developed at KTH. The performance evaluation results suggest that the proposed model can support key escrow while protecting the user communication from being forged with the cost of minimal computational resource and negligible overhead. without the possibility of undetectable fabrication of  session content. The implementation utilizes an existing implementation of a Session Initiation Protocol (SIP) user agent ‘minisip’ developed at KTH. The performance evaluation results suggest that the proposed model can support key escrow while protecting the user communication from being forged with the cost of minimal computational resource and negligible overhead

Hossen, MD. Sakhawat

Digitala Vetenskapliga Arkivet - Academic Archive On-line

A Session Initiation Protocol User Agent with Key Escrow

Publikationer från KTH

Academic Archive On-line (KTH, Sweden)

E-LIB Dokumentserver - Staats und Universitätsbibliothek Bremen