Melbourne School of Psychological Sciences - Research Publications
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ItemDiversity and Community: The Role of Agent-Based Modeling.(Wiley, 2017-06)Community psychology involves several dialectics between potentially opposing ideals, such as theory and practice, rights and needs, and respect for human diversity and sense of community. Some recent papers in the American Journal of Community Psychology have examined the diversity-community dialectic, some with the aid of agent-based modeling and concepts from network science. This paper further elucidates these concepts and suggests that research in community psychology can benefit from a useful dialectic between agent-based modeling and the real-world concerns of community psychology.
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ItemDiversity and Community Can Coexist(WILEY, 2016-03)We examine the (in)compatibility of diversity and sense of community by means of agent-based models based on the well-known Schelling model of residential segregation and Axelrod model of cultural dissemination. We find that diversity and highly clustered social networks, on the assumptions of social tie formation based on spatial proximity and homophily, are incompatible when agent features are immutable, and this holds even for multiple independent features. We include both mutable and immutable features into a model that integrates Schelling and Axelrod models, and we find that even for multiple independent features, diversity and highly clustered social networks can be incompatible on the assumptions of social tie formation based on spatial proximity and homophily. However, this incompatibility breaks down when cultural diversity can be sufficiently large, at which point diversity and clustering need not be negatively correlated. This implies that segregation based on immutable characteristics such as race can possibly be overcome by sufficient similarity on mutable characteristics based on culture, which are subject to a process of social influence, provided a sufficiently large "scope of cultural possibilities" exists.
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ItemFast and accurate protein substructure searching with simulated annealing and GPUs(BMC, 2010-09-03)BACKGROUND: Searching a database of protein structures for matches to a query structure, or occurrences of a structural motif, is an important task in structural biology and bioinformatics. While there are many existing methods for structural similarity searching, faster and more accurate approaches are still required, and few current methods are capable of substructure (motif) searching. RESULTS: We developed an improved heuristic for tableau-based protein structure and substructure searching using simulated annealing, that is as fast or faster and comparable in accuracy, with some widely used existing methods. Furthermore, we created a parallel implementation on a modern graphics processing unit (GPU). CONCLUSIONS: The GPU implementation achieves up to 34 times speedup over the CPU implementation of tableau-based structure search with simulated annealing, making it one of the fastest available methods. To the best of our knowledge, this is the first application of a GPU to the protein structural search problem.
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ItemModeling cultural dynamics(Routledge, 2017)This chapter provides a broad and selective introduction to diverse literatures on computational approaches to cultural dynamics. It explains the social psychological models of cultural dynamics, and then move to two prominent approaches to cultural dynamics— Axelrod's model of cultural dissemination and evolutionary game theoretic approaches to evolution of cooperation. These approaches focus on complementary aspects of cultural dynamics, and that each has unique strengths in dealing with some aspects, but not others. The Axelrod model has been used to explore the dynamics deriving from transmissions of cultural information and the role of drift and to some extent of importation; however, it does not address invention, or most importantly, selection. The evolutionary game theoretic approaches have a unique strength in examining the importance of the selection process in cultural evolution. The chapter discusses how the existing approaches complement each other, and also point to the gap in the existing theory— neither has addressed the process of invention.
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ItemUltrametric distribution of culture vectors in an extended Axelrod model of cultural dissemination(NATURE PORTFOLIO, 2014-05-02)The Axelrod model of cultural diffusion is an apparently simple model that is capable of complex behaviour. A recent work used a real-world dataset of opinions as initial conditions, demonstrating the effects of the ultrametric distribution of empirical opinion vectors in promoting cultural diversity in the model. Here we quantify the degree of ultrametricity of the initial culture vectors and investigate the effect of varying degrees of ultrametricity on the absorbing state of both a simple and extended model. Unlike the simple model, ultrametricity alone is not sufficient to sustain long-term diversity in the extended Axelrod model; rather, the initial conditions must also have sufficiently large variance in intervector distances. Further, we find that a scheme for evolving synthetic opinion vectors from cultural "prototypes" shows the same behaviour as real opinion data in maintaining cultural diversity in the extended model; whereas neutral evolution of cultural vectors does not.