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Recent collapses of SIP servers (e.g., Skype outage) indicate that the built-in SIP overload control mechanism cannot mitigate overload effectively. We introduce our analytical approach by investigating an overloaded tandem server scenario. Our analytical model: (1) considers a general case that both arrival rate and service rate for signaling messages are(More)
Tryptophan 2,3-dioxygenase (TDO), a liver-specific cytosolic hemoprotein, is the rate-limiting enzyme in L-tryptophan catabolism and thus a key serotonergic determinant. Glucocorticoids transcriptionally activate the TDO gene with marked enzyme induction. TDO is also regulated by heme, its prosthetic moiety, as its expression and function are significantly(More)
OBJECTIVE Prenatal deletion of the type II transforming growth factor-β (TGF-β) receptor (TBRII) prevents normal vascular morphogenesis and smooth muscle cell (SMC) differentiation, causing embryonic death. The role of TBRII in adult SMC is less well studied. Clarification of this role has important clinical implications because TBRII deletion should ablate(More)
Recent collapses of Session Initiation Protocol (SIP) servers indicate that the built-in SIP overload control mechanism cannot mitigate overload effectively. In this paper, we propose a new SIP overload control algorithm by introducing a novel analytical approach to model the dynamic behaviour of a SIP network where each server has a finite buffer. Three(More)
The increasing complexity and explosive growth of smartphone applications, together with the more prevalent use of cloud computing, have inspired strong motivation for offloading computation of mobile apps to the cloud. However, there exist vulnerabilities in apps if they are offloaded in public cloud environment. In this paper, we argue that keeping(More)
Retransmission mechanism helps SIP maintain its reliability, but it can also make an overload worse. Recent server collapses due to emergency-induced call volume in carrier networks indicate that the built-in overload control mechanism cannot handle overload conditions effectively. Since the retransmissions caused by the overload are redundant, we suggest(More)
As a main signaling protocol for multimedia sessions in the Internet, SIP (Session Initiation Protocol) introduces a retransmission mechanism to maintain the reliability for its real-time transmission. However, retransmission will make the server overload worse. Recent collapse of SIP servers due to emergency-induced call volume indicates that the built-in(More)
Recent server collapse in carrier networks (e.g., Skype outage) indicates that message retransmissions triggered by various SIP timers make the overload worse. The built-in overload control mechanism cannot handle overload conditions effectively. Since the retransmissions stimulated by the overload introduce more overhead rather than reliability, we suggest(More)