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Recent Postings

Quantifying the Social Debates of Anti-Vaccination on Twitter

On Friday, October 6, Xiaoyi Yuan, CSS PhD Student, will present “Quantifying the Social Debates of Anti-Vaccination on Twitter.” Measles is one of the leading causes of death among young children. In many developed countries with high measles, mumps, and rubella (MMR) vaccine coverage, measles outbreaks still happen each year. Social media has been one of the dominant information sources to gain vaccination knowledge and thus has also been the focus of the “anti-vaccine movement”. This talk is about two of my recent research projects on this topic. The first one will be introduced briefly, which is an agent-based model demonstrating how a small amount of online anti-vaccine sentiment could have the power of increasing the probability of measles outbreaks significantly. This research inspired me to investigate details of communicative pattern of “anti-vacciners” by analyzing a large twitter dataset (660892 tweets) after the California Disneyland measles outbreak in 2015. This second research has two main parts: first, in order to identify “anti-vacciners”, I used supervised learning to label each tweet as either positive, neutral, or negative opinion towards vaccination. The linear support vector machine model shows good performance on this dataset with an accuracy score of 72% on test data. Second, Louvain’s method for community detection of the retweet network shows the common pattern of social media communities; i.e., overall fragmented but with a few large communities. By investigating the opinion distribution in big communities, however, I discovered that they are highly overlapped, especially within “anti-vacciners”, meaning that they have more frequent communication within their own opinion group than with others. What’s useful for health communication strategies is to look further into the brokers–those who stand between two or more communities. At the end of the talk, I will address details of analyzing the brokerage as well.

The talk will begin at 3:00 in the Center for Social Complexity Suite located on the 3rd floor of Research Hall, and be followed by a Q&A session along with light refreshments.

These sessions will be live-streamed on the newly created CSS program YouTube channel.

For announcements regarding these and future streams, please join the : CSS/CDS student and alumni Facebook group.

For a list of upcoming and previous seminars, please click here.


ABM for Simulating Spatial Systems: How are we doing?

The CSS seminar speaker on Friday, September 22, will be Andrew Crooks, Associate Professor, Computational Social Science, Department of Computational and Data Sciences, George Mason University. Dr. Crooks’’s talk entitled “ABM for Simulating Spatial Systems: How are we doing?” (abstract below) will begin at 3:00 in the Center for Social Complexity Suite located on the 3rd floor of Research Hall. The talk will be followed by a Q&A session along with light refreshments.

This session will be live-streamed on the newly created CSS program YouTube channel: https://www.youtube.com/channel/UC7YCR-pBTZ_9865orDNVHNA

For announcements regarding this and future streams, please join the CSS/CDS student and alumni Facebook group: https://www.facebook.com/groups/257383120973297/

For a list of upcoming and previous seminars, please visit: https://cos.gmu.edu/cds/calendar/

Abstract: While great advances in modeling have been made, one of the greatest challenges we face is that of understanding human behavior and how people perceive and behave in physical spaces. Can new sources of data (i.e. “big data”) be used to explore the connections between people and places?

In this presentation, I will review the current state of art of modeling geographical systems. I will highlight the challenges and opportunities through a series of examples that new data can be used to better understand and simulate how individuals behave within geographical systems.


“The Quest for Living Beta: Investigating the Implication of Shareholder Networks”

PhD student Matthew Oldham will present the CSS seminar on Friday, September 15 (there will be no seminar on September 8), at 3pm in the Center for Social Complexity Suite located on the 3rd floor of Research Hall. Matthew Oldham, CSS PhD, will be speak on: “The Quest for Living Beta: Investigating the Implication of Shareholder Networks” (abstract below). The presentation will be followed by a Q&A session along with light refreshments.

The seminar will be live-streamed on the newly created CSS program YouTube channel.

For announcements regarding this and future streams, please join the CSS/CDS student and alumni Facebook group.

For a list of upcoming and previous seminars, click here.

Abstract: The behavior of financial markets has, and continues, to frustrate investors and academics. With the advent of new approaches, including complex systems and network analysis, the search for an explanation as to how and why markets behavior as they do has greatly expanded, and moved away from the tradition neoclassical approaches that have been beholden to the Efficient Market Hypothesis.

The complex system approach utilizes a number of a concepts in an attempt to understand stock market returns including; imitation, herding, self-organized co-operativity, and positive feedbacks, with many of these features captured by network analysis. In addition, with the meteoric rises of network science has come the realization that the behavior of a system can vary greatly depending on the network structure (the topology) of a system, thus providing further impetus for the use of network analysis in terms of financial markets.

My presentation will detail my recent research of the US Institutional shareholder networks over the period of 2007-10, a period which includes the beginning of the Global Financial Crisis. The research utilized an extensive dataset provided from the Thomson Reuters 13f database, to undertake a temporal analysis of the networks formed between US institutional investors and the stocks in the S&P 500. The analysis makes use of both projected and bipartite networks and uncovers numerous insights regarding relationships between the market in general, stocks and their shareholders. In addition, I will illustrate how the findings can be used in conjunction with an agent-based model to uncover the workings of the stock market.

9/5/17


“Characterizing the reaction of the population of NYC to a nuclear WM

The first CSS seminar speaker for the fall semester will be William G. Kennedy, Ph.D, Captain, USN (Ret.), Research Faculty, Center for Social Complexity, Krasnow Institute for Advanced Study, George Mason University. Dr. Kennedy’s talk entitled “Characterizing the reaction of the population of NYC to a nuclear WMD” (abstract below) is scheduled for Friday, September 1 and will begin at 3:00 in the Center for Social Complexity Suite located on the 3rd floor of Research Hall. The talk will be followed by a Q&A session along with light refreshments. The presentation will be streamed on our YouTube channel.

Abstract: This talk will review the status of our multi-year project to characterize the reaction of the population of a US megacity to a nuclear WMD event. Our approach is to develop an agent-based model of the New York City area, with agents representing each of the 20-25 million people, and establish a baseline of normal behaviors before exploring the population’s reactions to small (5-10Kt) nuclear weapon explosions. In our first year, we explored understanding a large population’s reaction to a nuclear WMD event with four major activities: (1) reviewing existing social theories and reports of disaster behavior, (2) collecting data and modeling the infrastructure of a mega-city and surrounding region, (3) generating synthetic population, and (4) developing an agent-based model of all the individuals in the region. The review of social science theories and data on individual/group behavior during disasters led to the publication of a case study (the Flint River drinking water crisis) and preparation of two review papers. For the New York City mega-city and surrounding area, we collected spatial, demographic, and workforce data from several sources and devised methods and algorithms to make the data useful for our simulation. Using Python, we processed road data and created one connected network forming the transportation layer of the model. Using demographic data and our own heuristics, again in Python, we synthesized individuals, their households, their associated schools and workplaces and finally their social networks. Other datasets were utilized so that children attend nearby schools or daycare constrained with actual capacities and people are employed in workplaces located nearby matching workforce data. Finally, we began modeling individuals’ movement in three counties, two rural counties and one in the heart of Manhattan. I will start with a discussion of the effects of a nuclear WMD event and then discuss the details our work and our future plans.

Please visit Seminar Calendar to see list of upcoming seminars.

8/28/17


The Origin of Agriculture in the Peiligang Culture

The CSS seminar speaker for Friday, February 27, 2017, will be Yang Zhou, PhD Student, Computational Social Science, Department of Computational and Data Sciences, George Mason University. Yang’s talk, entitled “The Origin of Agriculture in the Peiligang Culture: An Agent-based Modeling Approach” (abstract below), is scheduled to begin at 3:00 in the Center for Social Complexity Suite located on the 3rd floor of Research Hall. The talk will be followed by a Q&A session along with light refreshments.
This session will be live-streamed on the newly created CSS program YouTube channel: https://www.youtube.com/channel/UC7YCR-pBTZ_9865orDNVHNA

Abstract: The emergence of agriculture played an important role in human history as it allowed people to move from a nomadic (i.e. hunter-gather) to a sedentary (i.e. agricultural) lifestyle. This shift in lifestyle not only provided abundant food, but also sufficient numbers of non-cultivating specialists, which are necessary conditions for the rise of a civilization. However, questions about how and why agriculture originated have remained controversial. This paper explores the origin hypotheses of agriculture, using the canonical theory of social complexity as a framework to study the transition from hunter-gatherer to agricultural societies in the region of the Peiligang in China based on existing literature, and develops an agent-based model to simulate the transition process. The model assumes that a combination of population growth and gaining knowledge on plants drove the transition from hunter-gatherer to agriculture. Results show that based on the basic hypotheses and assumptions, the model is able to generate the key phases that are identical with the existing literature on such a transaction.


Dr. Nigel Gilbert of the University of Surrey, a leading scientist in the field of Computational Social Science, as well as long-time friend of our Center and a member of our original External Board, has been appointed Commander of the British Empire (CBE) by H.M. Queen Elizabeth II. Congratulations, Nigel!


Doctorates in Computational Social Science were conferred upon ten of our CSS students at the recent Convocation ceremony for the College of Science. We are so proud of them and of their tremendous accomplishment. Following are the students along with the titles of their dissertations:

  • Thomas J. Dover, Implementing a Complex Social Simulation of the Violent Offending Process: The Promise of a Synthetic Offender
  • Jose Manuel Magallanes, Climate Change and the Potential for Conflict and Extreme Migration in the Andes: A Computational Approach for Interdisciplinary Modeling and Anticipatory Policy Making
  • David P. Masad, Agents in Conflict: Comparative Agent-based Modeling of Intrnational Crises and Conflicts
  • Hugh James McFarlane, An Agent-based Model of Community Authority Structure Resilience
  • Cristina Metgher, A Computational Social Science Approach to the Social Determinants of Cancer
  • Nathan Palmer, Individual and Social Learning: Bounded Rationality from First Principles
  • Ovi Chris Rouly, Towards Emergent Social Complexity
  • Holly Ann Russo, Explaining Box Office Performance from the Bottom up: Data, Theories, and Models
  • Stephen L. Scott, Computational Modeling for Marine Resource Management
  • Hyungsik Shin, An Essay on Micro Heterogeneity and the Evolution of Inequality

Posted 5/12/16.



Multi-Level Regulation in Mammalian Circadian Clock

Casey Diekman (Department of Mathematical Sciences, New Jersey Institute of Technology)

DATE: Monday, 11 April, 2016
TIME: 4:00-5:00pm
LOCATION: Lecture Room (Room 229)
Krasnow Institute Building
George Mason University, Fairfax, VA

Abstract:

Circadian (~24-hour) rhythms offer one of the clearest examples of the interplay between different levels of nervous system organization, with dynamic changes in gene expression leading to daily rhythms in neural activity, physiology, and behavior. The main output signal of the master circadian clock in mammals has long been believed to be a simple day/night difference in the firing rate of neurons within the suprachiasmatic nucleus (SCN). Our recent findings challenge this theory, and demonstrate that a substantial portion of SCN neurons exhibit a more complex and counterintuitive set of electrical state transitions throughout the day/night cycle. In this seminar, I will attempt to provide a mathematical understanding of these daily transitions in SCN electrical state and the functional roles they play in the mammalian circadian clock.



How Firing Rate Heterogeneity is Mediated by Intrinsic and Network Heterogeneity

Monday, March 14, 3pm
Krasnow Institute Room 229
Fairfax Campus

Cheng Ly
Assistant Professor, Statistics & Operations Research Department
Virginia Commonwealth University

Abstract:
Heterogeneity of neural attributes has recently gained a lot of attention and is increasing recognized as a crucial feature in neural processing. Recent experimental recordings in electric fish indicate that the heterogeneous network input can mediate response heterogeneity of superficial pyramidal cells in a cortical area (Marsat Lab, WVU). These data motivated us to theoretically study how heterogeneity of neural attributes in general alter firing rate heterogeneity. We ask how 2 sources of heterogeneity: network (synaptic heterogeneity) and intrinsic heterogeneity alter response heterogeneity.

First we address this in a canonical recurrent spiking network model with random connectivity (Erdos-Renyi graph). The relationship between intrinsic and network heterogeneity can lead to amplification or attenuation of firing rate heterogeneity, and these effects depend on whether the recurrent network is firing asynchronously or rhythmically. We analyze the system and derive compact analytic formulas to precisely describe the phenomena.

Second, we adapt our theory to a delayed feedforward neural network to better model the electric fish system. The theory is used to demonstrate that a feedforward network with structured connectivity rules exhibit qualitatively similar statistics as the experimental data. Specifically, the stimulus tuning of particular cells is related to the network architecture, i.e., the number of synaptic connections. Thus, the model demonstrates that intrinsic and network attributes do not interact in a linear manner but rather in a complex stimulus-dependent fashion to increase or decrease response heterogeneity and thus shape population codes.

This is joint work with Gary Marsat (West Virginia University).
Claudio Cioffi, Joey Harrison, and Meysam Alizadeh, members of the CSC component of the Minerva Project on Radicalization, along with the University of Maryland, the University of Michigan, and the University of Warsaw, presented their work at the 2015 Minerva Meeting and Program in September. At the meeting sponsored by ONR, MASON models drew attention and praise for being at the cutting edge of agent-based simulation research.

Posted 11/12/15


Dr. Shu-Hen Cheng, professor, from National Cheng-chi Univerisity (NCCU) in Taipei, Taiwan, and editor of several noted academic journals, visited the Center for Social Complexity recently to discuss the future of collaboration between our respective groups. Possible topics include agent-based and complexity modeling on domains such as computational historical dynamics, disaster modeling and risk analysis, and applications in economics and finance. Dr. Cioffi will visit Dr. Cheng at the new NCCU institute for computational social science in 2016.

Posted 10/26/15

Claudio Cioffi, Joey Harrison, and Meysam Alizadeh, members of the CSC component of the Minerva Project on Radicalization, along with the University of Maryland, the University of Michigan, and the University of Warsaw, presented their work at the 2015 Minerva Meeting and Program in September. At the meeting sponsored by ONR, MASON models drew attention and praise for being at the cutting edge of agent-based simulation research.

Posted 11/12/15


Dr. Shu-Hen Cheng, professor from National Cheng-chi Univerisity (NCCU) in Taipei, Taiwan, and editor of several noted academic journals, visited the Center for Social Complexity recently to discuss the future of collaboration between our respective groups. Possible topics include agent-based and complexity modeling on domains such as computational historical dynamics, disaster modeling and risk analysis, and applications in economics and finance. Dr. Cioffi will visit Dr. Cheng at the new NCCU institute for computational social science in 2016.

Posted 10/26/15


Dr. Claudio Cioffi attended attended the Global Humanitarian Technology Conference in Seattle October 8-11. This is one of several meetings leading up to his participation in global humanitarian science and technology forums to disseminate the new agent-based model NorthLands of the Mason-Smithsonian Joint Project.


New MASON Northlands Unveiled. Dr. Claudio Cioffi announced the new MASON NorthLands, an agent-based model of climate change and emergent societal impacts, at the annual conference of the European Social Simulation Association (ESSA), in Groningen, Netherlands, September 14-18. This is the main “federated” model of the Mason=Smithsonian Joint Project on Climate and Society, funded by the Cyber-enabled Discoveries and Innovation (CDI) Program of the the National Science Foundation (NSF).

Peter Froncek, GRA and member of the the joint team on the NorthLands model, will present his research on cultural evolution, building on R. Reynolds’s work with cultural algorithms, at the upcoming workshop on Computational Social Science in Cologne, Germany, this month. Peter also passed his qualifying doctoral exams with flying colors and is now preparing his doctoral dissertation proposal leading to candidacy. Sean Luke has released a new version of MASON (Multi-Agent Simulator of Networks and Neighborhoods), available from the MASON website.


Paper-of-Record published by Claudio Cioffi, Dan Rogers, and Bill Honeychurch, on the MASON Hierarchies model, created for advancing understanding of the rise and fall of polities in Inner Asia, including the Mongol Empire. Read: MASON HIERARCHIES: A LONG-RANGE AGENT MODEL OF
POWER, CONFLICT, AND ENVIRONMENT IN INNER ASIA
. 9/17/15


Qing Tian, CSS Faculty, has co-authored two papers published recently in professional journals:

Tian, Q., Brown, D.G., Bao, S, Qi, S. (2015). Assessing and mapping human well-being for sustainable development amid flood hazards: Poyang Lake Region of China. Applied Geography, 63, 66-76.

Tian, Q., Brown, D.G., Zheng, L., Qi, S., Liu, Y., Jiang, L. (2015). The role of cross-scale social and environmental contexts in household-level land-use decisions, Poyang Lake Region. Annals of Association of American Geographers. DOI: 10.1080/00045608.2015.1060921. 9/3/15


Cioffi and Crooks Lecture in Lipari. Claudio Cioffi and Andrew Crooks, Center for Social Complexity, were featured lecturers at the Lipari International Summer School in Computational Social Science held July 25-31 on Lipari Island, Italy. The theme of this year’s session was Algorithms, Data, and Models for Social and Urban System. For more information, visit the school’s web site 8/10/15


Bill Honeychurch, former CSC postdoc and adjunct CSS faculty member, now at Yale University, has a new book out. Inner Asia and the Spatial Politics of Empire, published by Springer, is available for purchase at Amazon. 7/22/15


Andrew Crooks and Bill Kennedy are serving as Acting Director and Senior Adviser, respectively, while Claudio Cioffi is acting as GMU’s Interim Vice President for research. Dr. Cioffi will return to his position as Director of the Center on August 25. 7/22/15


Former CSC researcher develops new MASON model. Ates Hailegiorgis, formerly with the Center for Social Complexity’s Mason-Smithsonian Joint Project on Climate Change and Societal Consequences, and affiliate faculty at the Center, is now with the US Geeological Survey, Leetown Science Center, where he has developed a new MASON model of the lower Mississippi Alluvial Region. For more information, go to http://www.lsc.usgs.gov/ 7/15/15