Abstract: The high level of dynamics in today’s online social networks (OSNs) creates new challenges for their infrastructures and providers. In particular, dynamics involving edge creation has direct implications on strategies for resource allocation, data partitioning and replication. Understanding network dynamics in the context of physical time is a critical first step towards a predictive approach towards infrastructure management in OSNs. Despite increasing efforts to study social network dynamics, current analyses mainly focus on change over time of static metrics computed on snapshots of social graphs. The limited prior work models network dynamics with respect to a logical clock. We present results of analyzing a large timestamped dataset describing the initial growth and evolution of a large social network in China. We analyze and model the burstiness of link creation process, using the second derivative, i.e. the acceleration of the degree. This allows us to detect bursts, and to characterize the social activity of a OSN user as one of four phases: acceleration at the beginning of an activity burst, where link creation rate is increasing; deceleration when burst is ending and link creation process is slowing; cruising, when node activity is in a steady state, and complete inactivity.

Bio: Alessandra Sala recently joined Bell Labs Ireland as a research scientist. She is a member of the Industrial Mathematics and Operations Research (IMOR) group within the Enabling Computing Technologies(ETC) domain. In her prior appointment, she held a research associate position in the Department of Computer Science at University of California Santa Barbara. She focused her research on modeling massive graphs with an emphasis on privacy threats for Online Social Network users. Before that, she worked for two years as post-doctoral fellow with the CurrentLab research group led by Prof. Ben Y. Zhao. Before UCSB, she completed her Ph.D in Computer Science at University of Salerno, Italy. Her research interests include algorithms and complexity, distributed data structures, peer-to-peer systems and, lately, graph models and privacy issues in large scale systems.