Browsing by Author "Sarpe, Vladimir"
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- ItemOpen AccessBiological Simulation and Evolutionary Optimization: Modelling the Physiology Behind Influenza A Infection(2012-10-03) Sarpe, Vladimir; Jacob, ChristianUsing agent-based methodology and a 3-dimensional modelling and visualization environment (LINDSAY Composer), we present an agent-based simulation of the decentralized processes in the human immune system. The agents in our model – such as immune cells, viruses and cytokines – interact through simulated physics in two different, compartmentalized and decentralized 3-dimensional environments namely, (1) within the tissue and (2) inside a lymph node. While the two environments are separated and perform their computations asynchronously, an abstract form of communication is allowed in order to replicate the exchange, transportation and interaction of immune system agents between these sites. The distribution of simulated processes, that can communicate across multiple, local CPUs or through a network of machines, provides a starting point to build decentralized systems that replicate larger-scale processes within the human body, thus creating integrated simulations with other physiological systems, such as the circulatory, endocrine, or nervous system. One of the challenges of modelling biological systems is choosing the parameter values which lend it biological credibility. As a potential solution, we propose a parameter tuning approach using Particle Swarm Optimization. This approach relies on a graphical representation of an expected outcome as the metric for evaluating the feasibility of a particular set of parameters. As part of our experiments, we apply the optimization approach to the parameters of the clonal selection mechanism within the simulated lymph node. The results of the optimization allow us to understand the benefits and limitations of using this approach, as well as predict its applicability to larger, more complex biological simulations.
- ItemOpen AccessOptimization of Swarm-Based Simulations(2012-08-16) von Mammen, Sebastian; Sarraf Shirazi, Abbas; Sarpe, Vladimir; Jacob, ChristianIn computational swarms, large numbers of reactive agents are simulated. The swarm individuals may coordinate their movements in a “search space” to create efficient routes, to occupy niches, or to find the highest peaks. From a more general perspective though, swarms are a means of representation and computation to bridge the gap between local, individual interactions, and global, emergent phenomena. Computational swarms bear great advantages over other numeric methods, for instance, regarding their extensibility, potential for real-time interaction, dynamic interaction topologies, close translation between natural science theory and the computational model, and the integration of multiscale and multiphysics aspects. However, the more comprehensive a swarm-based model becomes, the more demanding its configuration and the more costly its computation become. In this paper, we present an approach to effectively configure and efficiently compute swarm-based simulations by means of heuristic, population-based optimization techniques. We emphasize the commonalities of several of our recent studies that shed light on top-down model optimization and bottom-up abstraction techniques, culminating in a postulation of a general concept of self-organized optimization in swarm-based simulations.
- ItemOpen AccessSimulating the decentralized processes of the human immune system in a virtual anatomy model(BioMed Central, 2013-04-17) Sarpe, Vladimir; Jacob, Christian