Events
Past Event
WED@NICO SEMINAR: Richard Lueptow, McCormick School of Engineering "Mixing by Cutting and Shuffling: Remarkably Persistent Structures"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level Chambers Hall
Details
Mixing by Cutting and Shuffling: Remarkably Persistent Structures
Speaker:
Richard Lueptow - Professor of Mechanical Engineering and Senior Associate Dean for Research, McCormick School of Engineering
Talk Abstract:
Engineers and scientists think of mixing in terms of diffusion, chaotic advection (stirring), or turbulence. However, mixing can also be accomplished by cutting and shuffling, like that used to mix a deck of cards or the colors of a Rubik's Cube. While other means of mixing have long been studied, mixing by cutting and shuffling is not well explored or understood. Unlike the stretching and folding characteristic of chaotic advection, cutting and shuffling maps do not stretch the material and exhibit no chaotic behavior in the usual sense—yet they can mix quite efficiently under certain conditions. In a 3D geometry, a physical model of cutting and shuffling is a spherical tumbler that is half-filled with a granular material undergoing a bi-axial rotation protocol—a rotation about one axis followed by a rotation about another axis for each iteration. X-ray visualization of the flowing granular material reveals non-mixing regions. Simulations of the granular system confirm the non-mixing regions. To further explore cutting and shuffling of a hemisphere, the problem can be mathematically formulated as a Piecewise Isometries (PWIs) transformation that cuts an object into a finite number of pieces and rearranges them into the object's original shape. Computationally recording the cut locations from the PWI on the hemispherical shell yields beautifully intricate complex patterns. However, the PWI transformation requires the assumption of a non-physical granular flow. Hence, it is remarkable that non-mixing regions identified using PWIs correspond to surprisingly persistent non-mixing regions and global barriers to mixing that occur in both experiments and continuum model simulations. This extraordinary merging of the mathematics of PWIs, traditional dynamical systems approaches, and physical applications is leading toward a novel paradigm for understanding and predicting mixing in physical systems based on cutting and shuffling. Funded by NSF Grant #CMMI-1435065.
Live Stream:
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Time
Wednesday, January 18, 2017 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 w/ Northwestern Scholars!
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speakers:
Yessica Herrera, Visiting Scholar, Northwestern Institute on Complex Systems
Talk Title: The Body Speaks: Visual Patterns of Psychological Stress
Aakriti Kumar, Post-Doctoral Fellow, Northwestern Institute on Complex Systems
Talk Title: Evaluating Elements of Empathic Communication with Experts, Crowds, and Large Language Models
Tingyu "Mark" Zhao, PhD Student, Industrial Engineering and Management Sciences
Talk Title: Noise Filtering in Complex Networks
Sign Up:
Sign up to present at a future Lightning Talk session. NICO Lightning Talks are open to graduate students, postdoctoral fellows, and visiting scholars.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/95387714084
Passcode: NICO25
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, data science and network science. 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 14, 2025 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)
WED@NICO SEMINAR: Rosemary Braun, Northwestern University "The Scale of Life"
Northwestern Institute on Complex Systems (NICO)
12:00 PM
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Lower Level, Chambers Hall
Details
Speaker:
Rosemary Braun, Associate Professor, Department of Molecular Biosciences, Northwestern University
Title:
The Scale of Life
Abstract:
Living systems exhibit surprising and beautiful self-organization at all scales. At the atomic level, proteins self-assemble into macromolecular complexes. The function of these machines is orchestrated within the cell by regulatory networks, whose activity is in turn dictated by, and coordinated with, the cells environment. This coordination takes place across large spans of space and time: the size and lifetime of organisms as large as the blue whale. Populations and ecosystems of many organisms in turn exhibit remarkable emergent dynamics. Today, advances in single-cell assays enable us to probe the molecular state of every cell in a sample in high-dimensional detail. But is this the correct scale at which to probe living systems? What can we learn from this data, and how can we abstract from the microscopic details to macroscopic phenotypes? In this talk, I will discuss some of our recent work bridging the cell and tissue/organism scales, and discuss some challenges and opportunities for the future.
Speaker Bio:
Rosemary Braun is an Associate Professor of Molecular Biosciences, Applied Mathematics [ESAM], and Physics at Northwestern University. A theoretical physicist by training, she earned her PhD in Physics from the University of Illinois, followed by a Masters in Biostatistics from Johns Hopkins University. She completed her postdoctoral training at the National Cancer Institute (NIH) before joining Northwestern as a faculty member. Today, she works at the intersection of statistics, mathematics, and biology to develop computational tools for analyzing high-dimensional data. In addition to her Northwestern affiliations, she is also Associate Director of the National Institute for Theory and Mathematics in Biology, as well as external faculty of the Santa Fe Institute.
Location:
In person: Chambers Hall, 600 Foster Street, Lower Level
Remote option: https://northwestern.zoom.us/j/97015976754
Passcode: NICO25
About the Speaker Series:
Wednesdays@NICO is a vibrant weekly seminar series focusing broadly on the topics of complex systems, data science and network science. 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 21, 2025 at 12:00 PM - 1:00 PM
Location
Lower Level, Chambers Hall Map
Contact
Calendar
Northwestern Institute on Complex Systems (NICO)