Sarah Rajtmajer

Sarah Michele Rajtmajer

Department of Mathematics
The Pennsylvania State University
0109 McAllister Building
University Park, PA 16802
+1 (814) 865-0075
smr48'at'psu.edu


I am a Postdoctoral Fellow in the Department of Mathematics at The Pennsylvania State University.

I have a PhD in Mathematics from the University of Zagreb and a BA in Mathematics and Music from Columbia University. Prior to my post in the Department of Mathematics at Penn State, I worked as a Research Associate at the University of Dubrovnik and as a Postdoctoral Fellow at Penn State's Applied Research Laboratory through the Intelligence Community Postdoctoral Research Fellowship Program.

My research interests include graph theory, game theory, complex networks algorithms, machine learning, data mining and statistics, with particular applications to social networks, neuroscience and chemistry. My work is currently funded by the Army Research Office and focuses on evolutionary game theory over graphs in the domain of online deviance and privacy in social networks.



Publications

Conference Articles (Peer Reviewed)

1. C. Qiu, A. Squicciarini, S. Rajtmajer and J. Caverlee. Dynamic Contract Design for Heterogeneous Workers in Crowdsourcing for Quality Control. International Conference on Digital Society (IEEE ICDS), July 2017.
2. J. Semonsen, C. Griffin, A. Squicciarini and S. Rajtmajer. Consensus on Social Graphs under Increasing Peer Pressure (Extended Abstract). International Conference on Autonomous Agents and Multiagent Systems (AAMAS), May 2017.
3. C. Griffin, S. Rajtmajer and A. Squicciarini. A model of paradoxical privacy behavior (Invited Paper). International Conference on Collaboration and Internet Computing (IEEE CIC), October 2016.
4. A. Tyagi, A. Squicciarini, S. Rajtmajer and C. Griffin. An in-depth study of peer influence on collective decision making for multi-party access control (Invited Paper). International Conference on Information Reuse and Integration (IEEE IRI), July 2016.
5. H. Zhong, H. Li, A. Squicciarini, S. Rajtmajer, C. Griffin, D. Miller and C. Caragea. Content-driven Detection of Cyberbullying on the Instagram Social Network. 25th International Conference on Artificial Intelligence (IJCAI), July 2016.
6. S. Rajtmajer, C. Griffin and A. Squicciarini. Constrained social-energy minimization for multi-party sharing in online social networks. International Conference on Autonomous and Multiagent Systems (AAMAS), May 2016.
7. S. Rajtmajer, C. Griffin and A. Squicciarini. Determining a discrete set of site-constrained privacy options for users in social networks through Stackelberg Games. Conference on Decision and Game Theory for Security (GAMESEC), November 2015.
8. A. Squicciarini, S. Rajtmajer, Y.Liu and C. Griffin. Identification and characterization of cyberbullying dynamics in an online social network. IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM), August 2015.
9. C. Liao, A. Squicciarini, C. Griffin and S. Rajtmajer. A hybrid epidemic model for the spread of abusive content in online social sites. IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM), August 2015.
10. S. Rajtmajer, C. Griffin, D. Mikesell and A. Squicciarini. An evolutionary game model for the spread of non-cooperative behavior in online social networks. 30th ACM/SIGAPP Symposium on Applied Computing, April 2015.
11. C. Griffin, A. Squicciarini, S. Rajtmajer, M. Tentilucci and S. Li. Site-constrained privacy options for users in social networks through Stackelberg Games. 6th ASE International Conference on Social Computing (SocialCom), May 2014.
12. D. Bein, B. B. Madan, S. Phoha, S. Rajtmajer and A. C. Rish. Dynamic data-driven sensor network adaptation for border control. SPIE Defense, Security and Sensing, April 2013.

Journal Articles

1. A. Squicciarini, S. Rajtmajer and C. Griffin. Positive and negative behavior analysis in social networks. WIRE Data Mining and Knowledge Discovery 7, 2017.
2. C. Liao, A. Squicciarini, C. Griffin and S. Rajtmajer. A hybrid epidemic model for deindividuation and antinormative behavior in online social networks. Social Network Analysis and Modeling 6(1), 2016.
3. S. Rajtmajer, A. Roy, R. Albert, P. Molenaar and F. G. Hillary. A voxelwise approach to determine consensus regions-of-interest for the study of brain network plasticity. Frontiers in Neuroanatomy 9(97), 2015.
4. F. G. Hillary, N. D. Castellanos, R. Bajo and S. Rajtmajer. Hyperconnectivity as a common neural response to neurological disorder. Neuropsychology 29(1), 2015.
5. F. G. Hillary, S. Rajtmajer, C. Roman, J. D. Medaglia, J. Slocomb, D. C. Good and G.R. Wylie. The rich get richer: brain injury elicits hyperconnectivity in core subnetworks. PLoS One 9(8), 2014.
6. S. Rajtmajer, B. Smith and S. Phoha. Non-negative sparse autoencoder neural networks for the detection of overlapping, hierarchical communities in networked datasets. Chaos 22, 2012.
7. S. Rajtmajer and D. Vukičević. A note on the Estrada communicability algorithm for community structure detection in complex networks. Applied Mathematics and Computation 217, 2010.
8. S. Rajtmajer and D. Vukičević. A fast approach to the detection of all-purpose hubs in complex networks with chemical applications. Iranian Journal of Mathematical Chemistry 2, 2010.
9. D. Vukičević, S. Rajtmajer and N. Trinajstić. Trees with maximal Second Zagreb Index and prescribed number of vertices of given degree. MATCH Communications in Mathematical and Computer Chemistry 6, 2008.
10. D. Vukičević, J. Sedlar and S. Rajtmajer. A graph theoretical method for the partial ordering of alkanes. Croatia Chemica Acta 80: 169-179, 2007.
11. S. Rajtmajer, A. Milicević, N. Trinajstić, M. Randić and D. Vukičević. On the complexity of Archimedian solids. Journal of Mathematical Chemistry 39: 119-132, 2004.

Book Chapter

1. U. M. Venkatesan, S. Rajtmajer and F. G. Hillary. Connectivity modeling and neuroplasticity after trauma. In Plasticity of Cognition in Neurologic Disorders. Oxford University Press, January 2015.

Conference Articles (Abstract Reviewed)

1. S. Rajtmajer, C. Griffin and A. Belmonte. A coordination game model for information cascades in social networks. 35th Dynamics Days, Durham, January 2016.
2. S. Rajtmajer and F.G. Hillary. Modeling plasticity in brain networks after neurological disruption: a critique of connectivity modeling approaches. International Neuropsychological Society 2014 Mid-Year Meeting, Jerusalem, July 2014.
3. F. G. Hillary and S. Rajtmajer. Hyperconnectivity in brain networks as a marker of recovery following traumatic brain injury. International Neuropsychological Society 2014 Mid-Year Meeting, Jerusalem, July 2014.

Under Review

1. C. Griffin, S. Rajtmajer, A. Squicciarini and A. Belmonte. Consensus and Information Cascades in Game- Theoretic Imitation Dynamics with Static and Dynamic Network Topologies. Resubmitted to SIAM Journal on Applied Dynamical Systems 2017.
2. H. Zhong, A. Squicciarini, D. Miller and S. Rajtmajer. Spatial Attribution of Private Content in Posted Images on the Instagram Social Network. Submitted to PETS 2017.
3. S. Rajtmajer, A. Squicciarini, J. Such, J. Semonsen and A. Belmonte. An Ultimatum Game Model for the Evolution of Privacy in Jointly Managed Content. Submitted to GAMESEC 2017.