Events
Past Event
NICO DECEMBER SEMINAR: Scott Feld, Purdue University "Finding Highly Connected Nodes in Networks: The Power of Common Friends"
Northwestern Institute on Complex Systems (NICO)
11:00 AM
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Lower Level, Chambers Hall
Details
Speaker:
Scott Feld, Professor of Sociology, Purdue University
Title:
Finding Highly Connected Nodes in Networks: The Power of Common Friends
Abstract:
This paper extends the Friendship Paradox – where friends have more friends than random people do, on average – to the more general phenomenon that mutual friends have more friends than friends do, on average. We show that we can find people who who are friends of multiple people in practical sized random samples in one regional Facebook network of 63,392 people with an average of 24 friends each, where people with two friends in a random sample have an average of 212 friends overall, with three friends have an average of 391 friends, etc. We further illustrate this general network phenomenon by taking random samples of citations from 79,034 journal articles. We find that a source cited by two articles in a random sample has an average of 461 citations, placing it in the top 0.01% in numbers of citations among all sources cited by these articles. We provide a general expression for the expected overall number of friends of a person found to have k friends in a random sample from a population with a given distribution of numbers of friends. We show that the effectiveness of using common friends among random samples for finding highly connected nodes is most pronounced when there are nodes with a great disproportion of the ties, as seems to be both typical and important for many types of social and other networks, such as where there are superspreaders of diseases, mega-influencers on the Internet, and highly connected central nodes in centralized neural networks. We discuss further implications, applications, and directions for further research.
Speaker Bio:
Scott Feld served as Assistant to Full Professor of Sociology at the State University of New York at Stony Brook from 1975-1991. He then served as Professor of Sociology at Louisiana State University from 1991 until 2004, and joined the faculty at Purdue University in 2004. He has published over sixty articles, including twelve published in the most prestigious journals in the fields of Sociology and Political Science. His ongoing research interests involve 1) causes and consequences of patterns in social networks, 2) processes of individual and collective decision making, and 3) applications of sociology, most recently including innovations in marriage and divorce laws (covenant marriage). He regularly teaches undergraduate and graduate courses on social networks, research methods, and statistics.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/91453237911
Passcode: NICO2024
Time
Tuesday, December 3, 2024 at 11:00 AM - 12:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Gary Slutkin, Cure Violence Global "The End of Violence - How do we do that?" (co-sponsored with CORNERS)
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speaker:
Gary Slutkin, Founder, Cure Violence Global
Title:
The End of Violence - How do we do that?
Abstract:
Dr. Slutkin will discuss the msin findings in his new book “The End of Violence”
After 20 years fighting epidemics of infectious diseases in the U.S., and abroad with the World Health Organization, Dr. Slutkin returned to Chicago and saw violence acting the same way as these other diseases. He then founded Cure Violence Global to show that violence not only behaves like other epidemics, but its spread can be interrupted and stopped using the same playbook. This approach is now being used widely and for many types of violence.
In this book, Dr. Slutkin reveals how we can now understand how violence spreads from person to person and from country to country, through invisible brain processes that can now be identified. He also found that both the contagion, and its interruption, can work for all forms of violence from child abuse to community violence, violence against women, suicide, and even war, genocide and tyranny. The book provides stories and data on success for several of these different forms of violence in Chicago, Baltimore, NYC, Honduras, Mexico, Colombia, Iraq, Syria and even to stop a potential nuclear war between the U.S. and North Korea.
With this new book, we now have not only a new diagnosis of violence – a disease - but a new method to stop it – with results in dozens of communities and countries, as well as a whole new understanding, language and even a whole new set or workers.
Speaker Bio:
Gary Slutkin is a physician and epidemiologist formerly of the World Health Organization, the Founder and CEO of Cure Violence, and an innovator in epidemic management, public health, behavior change, and data-based approaches to local and global problems.
He led or co-led efforts to reverse epidemics of tuberculosis and cholera in 40 refugee camps, led the efforts to start the national AIDS programs with the 13 countries in the epicenter of the epidemic in central and East Africa and, led World Health Organization’s efforts to reverse the AIDS epidemic in Uganda, the only country to successfully reverse its AIDS epidemic at the time.
After 10 years abroad, Dr. Slutkin returned home to the U.S. and shifted his focus to violence, seeing it as an epidemic process. He is credited with having fully revealed the scientific and practical links for seeing and treating violence as a standard health epidemic. In the year 2000 he founded Cure Violence which has achieved 40% to 70% drops in violence in communities around the world using these methods. The approach has also been successfully adapted to curtail political violence, election violence, and gender-based violence in countries around the world.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/93101362874
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, networks, and artificial intelligence. It brings together attendees ranging from graduate students to senior faculty who span all of the schools across Northwestern, from applied math to sociology to biology and every discipline in-between. Please visit: https://bit.ly/WedatNICO for information on future speakers.
Co-Sponsor:
This speaker is co-sponsored with CORNERS.
Time
Wednesday, April 29, 2026 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Daniel Stouffer, Leibniz Institute "Conceptual and Theoretical Challenges in the Study of Multi-Species Coexistence"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speaker:
Daniel B. Stouffer, Research Group Leader, Department of Evolutionary and Integrative Ecology, the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
Title:
Conceptual and Theoretical Challenges in the Study of Multi-Species Coexistence
Abstract:
The population dynamics of most ecological communities unfold on temporal scales that cannot be fully studied in the laboratory or field. The generation times of trees, for example, are so long and varied that we may need to wait decades to determine how a whole, interconnected forest community responds to a changing climate. Many researchers thus use models to generate predictions that go beyond the bounds of what is experimentally tractable. To do so, it has become common to follow the "model-paramerisation paradigm". For example, a researcher interested in forest dynamics would not conduct long-term experiments to directly probe whether one tree species is ever competitively excluded by any other(s). Instead, they would use data from shorter-term experiments to estimate the parameters of a presupposed model, and then study whether or not their empirically parameterised model predicts competitive exclusion or coexistence. As powerful as this perspective has proven to be, it routinely hinges on multiple key assumptions that limit its versatility. I will describe recent and ongoing work that challenges these assumptions, while also describing some unexpected hurdles encountered along the way.
Speaker Bio:
Daniel B. Stouffer is a Research Group Leader in the Department of Evolutionary and Integrative Ecology at the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany. His group adopts a variety of computational, statistical, and analytical approaches to overcome ecological communities' innate complexity while exploring fundamental biological questions. They work on a variety of topics and systems and are particularly interested in understanding the emergent ecological and evolutionary consequences that arise due to interactions between species.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/98364690035
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, networks, and artificial intelligence. It brings together attendees ranging from graduate students to senior faculty who span all of the schools across Northwestern, from applied math to sociology to biology and every discipline in-between. Please visit: https://bit.ly/WedatNICO for information on future speakers.
Time
Wednesday, May 6, 2026 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Hamsa Bastani, Wharton School, University of Pennsylvania "Challenges in Achieving Human-AI Collaboration"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speaker:
Hamsa Bastani, Associate Professor of Operations, Information, and Decisions, and Statistics and Data Science, Wharton School, University of Pennsylvania
Title:
Challenges in Achieving Human-AI Collaboration
Abstract:
TBA
Speaker Bio:
Hamsa Sridhar Bastani is an Associate Professor of Operations, Information, and Decisions (OID) and Statistics and Data Science at the Wharton School of the University of Pennsylvania, where she co-direct the Wharton Healthcare Analytics Lab. Her research sits at the intersection of machine learning, operations research, and economics. She studies how to design, deploy, and evaluate AI systems that empower human decision-makers and improve societal outcomes.
Professor Bastani aims to combine methodological depth with implementation in consequential environments. She has worked with national governments to deploy algorithms at the country scale for targeted border COVID-19 screening and essential medicine access, and has co-led one of the first large field studies of generative AI tutors in high school mathematics. She studies both the mathematical properties of algorithms and the way people respond to them.
Her research has been published in leading outlets including Nature, Management Science, Operations Research, and PNAS, and has garnered numerous recognitions, including the Wagner Prize for Excellence in Operations Research, the INFORMS Pierskalla Award for best healthcare paper, and the George Nicholson Prize. Previously, she graduated summa cum laude from Harvard in 2012 with an A.M. in physics and an A.B. in physics and mathematics, completed her PhD in Stanford's Electrical Engineering department under the supervision of Mohsen Bayati, and spent a year as a Herman Goldstine postdoctoral fellow at IBM Research.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/99847338986
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, networks, and artificial intelligence. It brings together attendees ranging from graduate students to senior faculty who span all of the schools across Northwestern, from applied math to sociology to biology and every discipline in-between. Please visit: https://bit.ly/WedatNICO for information on future speakers.
Time
Wednesday, May 13, 2026 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Lightning Talks with NU Scholars!
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
NICO is looking for participants to share 12-15 minute lightning talks on their current research. To sign up, please fill out this short survey. These are open to Northwestern graduate students, postdoctoral fellows, and visiting scholars!
All talks will be given in person at Chambers Hall and this event will also be livestreamed via Zoom.
Speakers will be balanced based on their topics/disciplines in order to provide a broad representation of the research activities at NICO
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/98031689779
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, networks, and artificial intelligence. It brings together attendees ranging from graduate students to senior faculty who span all of the schools across Northwestern, from applied math to sociology to biology and every discipline in-between. Please visit: https://bit.ly/WedatNICO for information on future speakers.
Time
Wednesday, May 20, 2026 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)