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Dynamic Multi-System Resilience in Human Aging/Dynamical systems approach to studying resilience in older adults

From Complex Time

November 12, 2018
1:40 pm - 2:20 pm


Ravi Varadhan (Johns Hopkins Univ.)


Resilience may be defined as the ability of a system to recover from a stressor of sufficiently large magnitude that the system is pushed into a state far from its original equilibrium state, ultimately retaining essential identity and function. In this talk, we will discuss the distinction between related concepts of homeostasis, robustness, and resilience. We will describe a dynamical systems modeling approach to studying resilience, and present some examples based on the stimulus-response experiments conducted in the Women's Health and Aging Study.

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Post-meeting Reflection

Ravi Varadhan (Johns Hopkins Univ.) Link to the source page

Alfonse Hoekstra's discussion of multiscale resilience was fascinating to me. The network simulation models of Dervis and Peter Hoffman were very interesting and provide useful insights, but to mimic the complexity of human physiology, we would need hierarchically structured networks. I wonder if there are some invariance principles in multi-scale resilience that could reduce the degree of complexity of this type of modeling. The principles and results of hierarchy theory could be relevant here.

Sanne's talk on DIORs (dynamic indicators of resilience) was also quite interesting. There are several open questions here: how to model temporal autocorrelation; how to handle non-stationary time series; how to do systems identification with DIORs, i.e. how can we predict responses of frail/nonfrail using estimates of DIORs. I also think the idea of reactive tuning to stimulus can be examined using novel metrics of DIORs. I would be interested in exploring these ideas in my work!

The second day's talks were also very interesting. Heather's case history was captivating, highlighting the challenges of treating a human being as a complex physiological system. I liked her point that we need to observe and let the system tell us what needs to be done. Ingrid's talk was very informative on the modeling of complex ecological systems. Porter's talk on the resilience of the Pueblo Indian nation to colonization was very educational for me. I can relate to my own Hindu/Indian culture's resilience in having survived several invasions and colonization over the centuries. The idea of axiology, the systems of values which provide the core resilience to a culture, was most interesting. Warren presented some exquisite data on mouse resilience. To me, tlis hehighlighted the huge potential of using mouse models to develop a comprehensive modeling framework for resilience.

Reference Material

The volume by Howard Pattee entitled "Hierarchy Theory; The Challenge of Complex Systems.", which was published in 1973 could be very relevant to the work on multiscale resilience that Alfonse Hoekstra presented.

Title Author name Source name Year Citation count From Scopus. Refreshed every 5 days. Page views Related file
Stimulus-response paradigm for characterizing the loss of resilience in homeostatic regulation associated with frailty3 R. Varadhan, C. L. Seplaki, Q. L. Xue, K. Bandeen-Roche, L. P. Fried Mechanisms of Ageing and Development 2008 81 4
Hierarchy theory: the challenge of complex systems2 H.H. Pattee 1973 0 5