HumMod Explorer: A Multi-Scale Time-Varying Human Modeling Navigator Liming Xu ∗ Zhejiang University Jeremy Lyle † USM Yubao Wu ‡ USM Zhigeng Pan § Zhejiang University Mingmin Zhang ¶ Zhejiang University David H. Laidlaw ‖ Brown University Robert L. Hester ∗∗ University of Mississippi Medical Center Jian Chen †† USM Abstract We present HumMod Navigator, a multiple-scale physiology data browser for exploring casual relationships of time-varying human modeling data. The visualization makes use of a circular layout and hierarchical relations to effectively visualize interactions be- tween model parameters in an attempt to obtain both a local and comprehensive view of the physiological modeling environment. CR Categories: I.3.6 [Computer Graphics]: Methodology and Techniques—Interaction techniques; Keywords: physiology, time-varying, information visualization Links: DL PDF 1 Introduction Recent success in real-time modeling and simulation of human physiology has imposed grant challenges to data analysis which enable scientists to understand how precisely organism functions intricately and exquisitely by the laws of physics and chemistry. In 1972, Guyton et al. [Guyton AC 1972] published a landmark pa- per giving an integrative model for the circulatory system involv- ing multiple body organ systems. This model was remarkable be- cause of its successful integration of multiple physiological sys- tems, as well as its conciseness and clarity in describing interac- tions between parameters and portraying a comprehensive view of the model. The Guyton model has been extended to a more com- prehensive modeling environment, HumMod [Hester et al. 2011], which models interactions between the cardiovascular, respiratory, renal, neural, endocrine, skeletal muscle, and metabolic physiolo- gies. An important use for the model is to understand physiological mechanisms and interactions that are not evident, allowing one to observe higher level emergent properties of the complex physio- logical systems. In order to accomplish this, one of the difficulties which must be overcome with HumMod is the fact that the number of parameters is prohibitive in developing a clear and comprehen- sive view of the interactions between parameters. Currently the HumMod model contains more than 5000 variables. The integra- tive modeling of HumMod is accomplished by assimilating over 40 years worth of published physiological models for the interactions between parameters. Therefore, good visualization techniques are needed to discern non-obvious relationships between variables. ∗ email: xuliming@zjucadcg.cn † email: samuel.lyle@usm.edu ‡ email: yubao.wu@eagles.usm.edu § email: zgpan@cad.zju.edu.cn ¶ email: zmm@cad.zju.edu.cn ‖ email: dhl@cs.brown.edu ∗∗ e-mail: rhester@umc.edu †† e-mail: jian.chen@usm.edu Figure 1: View of Hierarchical Tree around inner ring. The node at the center of the figure corresponds to the level 0 name. From the adjacent node on the left, the nodes clockwise around the cycle cor- respond to the level 2 names given on the right. Edges from these nodes to the root have been suppressed, except for the rightmost and leftmost neighbor. The level 2 names can be projected downward onto the inner circle to determine their associated global name pa- rameters. 2 Description of Parameter Interactions 2.1 Structure of HumMod To describe the parameter interactions in HumMod, it is necessary to first give a short description of the structure and environment of HumMod. In order to simplify the process of updating the model, All aspects of the model are stored as XML documents. A C++ parser, which additionally includes functionality for solving the equations involved in the model, is used to parse and execute the model. To update the model, it is only necessary to edit or add XML files. Both the parser and XML files are freely available on- line at http://hummod.org/. Parameter interactions can be classified into two types, hierarchical and functional. 2.2 Parameter Interactions: Hierarchical relationships Every parameter used in HumMod has an assigned “global” name. For example, Co2Total includes the parameters or global names of CO2.CO2Total.Inflow and CO2.CO2Total.Outflow. Each global name is made up of three distinct components, namely CO2, CO2Total, and Inflow, and CO2, CO2Total, and Outflow. This represents the fact that within the folder describ- ing CO2, and the specific file describing CO2Total, there are local elements corresponding to both Inflow and Outflow. To simplify our explanations, we will refer to the compo- nents of the name of a model parameter as the level x name, where x refers to the depth. Therefore, for the parameter CO2.CO2Total.Inflow, the level 0 name is CO2, the level 1