Tag: dynamics

Criticality in Biochemical Networks

J Royal Society Interface

Researchers from our center, in collaboration with State University of New York, Binghamton University and the Instituto Gulbenkian de Ciência developed a mathematical and computational framework to understand how biochemical networks contribute to the evolvability, robustness, and resilience of biological organisms.

In a paper in the journal Journal of the Royal Society InterfaceLuis Rocha, George J. Klir Professor of Systems Science, and Drs. Manuel Marques-Pita and Santosh Manicka (who earned his Ph.D. in complex networks and systems from the Luddy School), show that a large amount of redundancy exists in how genes, proteins and other biochemical components process signals. This results in much robustness to perturbations, allowing biological systems to exist in a stable or near-critical dynamical regime, despite being composed of thousands of biochemical variables which would ordinarily result in chaotic dynamics.

The measure of effective connectivity developed by Rocha and Marques-Pita captures redundancy in automata networks and is shown in the paper to be highly predictive of dynamical regime of biochemical systems ranging from flower development to breast cancer in humans. The approach thus adds empirical validity to several  well-known hypotheses in theoretical biology: 1) that canalization adds robustness to biological development put forth by C.H. Waddington, 2) that redundancy is essential for evolvability put forth by Michael Conrad, and 3) that biological organisms exist in a near-critical dynamical regime put forth by Stuart Kauffman. The new work further connects the three hypotheses by equating canalization with redundancy, providing a  measure of effective connectivity based on dynamical redundancy, and further showing that this measure very accurately predicts the dynamical regime of biochemical networks.

You can read the article following the links in reference:

Manicka Santosh, Marques-Pita Manuel and Rocha Luis M. [2022]. “Effective connectivity determines the critical dynamics of biochemical continue reading.

New Ph.D. Graduate

Congratulations to Alexander Gates for successfully defending his dissertation entitled “The anatomical and effective structure of complex systems” on April 3rd 2017, co-supervised by Randy beer and Luis Rocha. Alex completed a dual-PhD degree in the Complex Systems track of the Informatics PhD Program as well as the Cognitive Science program at Indiana University. Alex has accepted a postdoctoral position at Northeastern University at the Center for Complex Network Research. … continue reading.

Control of Complex Networks

Network science has allowed us to understand the organization of complex systems across disciplines. However, there is a need to understand how to control them; for example, to identify strategies to revert a diseased cell to a healthy state in cancer treatment. Recent work in the field—based on linear control theory—suggests that the controllability of complex systems can be predicted solely from the graph of interactions between variables, without considering their dynamics. Such graph-based approaches have been used, for instance, to suggest that biological systems are harder to control and have appreciably different control profiles than social or technological systems. The methodology has also been increasingly used in many applications from financial to biochemical networks.

In work published today in Nature Scientific Reports, CNetS graduate student Alexander Gates and Professor Luis Rocha demonstrate that such graph-based methods fail to characterize controllability when dynamics are introduced. The study computed the control profiles of large ensembles of multivariate systems as well as existing Systems Biology models of biochemical regulation in various organisms.… continue reading.

CNetS team studies generalized modularity in complex networks & Systems

mediumModularity in complex systems can be observed in networks and across dynamical states, time scales, and in response to different kinds of perturbations. In a paper published in Physical Review E (Rapid Communication), Kolchinsky, Gates & Rocha propose a principled alternative to detecting communities in static and dynamical networks. The method demonstrates that standard modularity measures on static networks can be seen as a special case of measuring the spread of perturbations in dynamical systems. Thus, the new method offers a powerful tool for exploring the modular organization of complex dynamical systems.… continue reading.

Awards at CCS 2015

Optimized-IU_poster_5_botsThe CNetS poster “The Rise of Social Bots in Online Social Networks” by Emilio Ferrara, Onur Varol, Prashant Shiralkar, Clayton Davis, Filippo Menczer, and Alessandro Flammini won a Best Poster Award at CCS 2015. The poster was presented by Clayton Davis. The results will also appear in the paper “The Rise of Social Bots” to be published in Comm. ACM (in press, preprint).

The paper “Modularity and the Spread of Perturbations in Complex Dynamical Systems” by Artemy Kolchinsky, Alexander J. Gates and Luis M. Rocha, and the poster “Information Theoretic Structures of the French Revolution” by Alexander Barron, Simon DeDeo and Rebecca Spang won additional awards.

Finally, our former postdoctoral scientist Bruno Gonçalves (now tenured faculty member at Aix-Marseille Université) received a Junior Scientist Award from the Complex Systems Society for his contributions to the study of human social behavior from large-scale online attention and behavioral data. This is the second Junior Scientist Award for CNetS (the first was won by Filippo Radicchi).

Congratulations to the CNetS team!

  … continue reading.