Entropic Forces in Binary Hard Sphere Mixtures: Theory and Simulation

We perform extensive Monte Carlo simulations of binary hard-sphere mixtures (with diameter ratios of 5 and 10), to determine the entropic force between (1) a macrosphere and a hard wall, and (2) a pair of macrospheres. The microsphere background fluid (at volume fractions ranging from 0.1 to 0.34) induces an entropic force on the macrosphere(s); the latter component is at infinite dilution. We find good overall agreement, in both cases, with the predictions of an HNC-based theory for the entropic force. Our results also argue for the validity of the Derjaguin approximation relating the force between convex bodies to that between planar surfaces. The earlier Asakura-Oosawa theory, based on a simple geometric argument, is only accurate in the low-density limit.Comment: 13 pages, LaTeX, 10 figure

A pilot study of operating department practitioners undertaking high-risk learning: a comparison of experiential, part-task and hi-fidelity simulation teaching methods

Health care learners commonly rely on opportunistic experiential learning in clinical placements in order to develop cognitive and psychomotor clinical skills. In recent years there has been an increasing effort to develop effective alternative, non-opportunistic methods of learning, in an attempt to bypass the questionable tradition of relying on patients to practice on. As part of such efforts, there is an increased utilisation of simulation-based education. However, the effectiveness of simulation in health care education arguably varies between professions (Liaw, Chan, Scherpbier, Rethans, & Pua, 2012; Oberleitner, Broussard, & Bourque, 2011; Ross, 2012). This pilot study compares the effectiveness of three educational (or ‘teaching’) methods in the development of clinical knowledge and skills during Rapid Sequence Induction (RSI) of anaesthesia, a potentially life-threatening clinical situation. Students of Operating Department Practice (ODP) undertook either a) traditional classroom based and experiential learning, b) part-task training, or c) fully submersive scenario-based simulated learning

Physics-related epistemic uncertainties in proton depth dose simulation

A set of physics models and parameters pertaining to the simulation of proton energy deposition in matter are evaluated in the energy range up to approximately 65 MeV, based on their implementations in the Geant4 toolkit. The analysis assesses several features of the models and the impact of their associated epistemic uncertainties, i.e. uncertainties due to lack of knowledge, on the simulation results. Possible systematic effects deriving from uncertainties of this kind are highlighted; their relevance in relation to the application environment and different experimental requirements are discussed, with emphasis on the simulation of radiotherapy set-ups. By documenting quantitatively the features of a wide set of simulation models and the related intrinsic uncertainties affecting the simulation results, this analysis provides guidance regarding the use of the concerned simulation tools in experimental applications; it also provides indications for further experimental measurements addressing the sources of such uncertainties.Comment: To be published in IEEE Trans. Nucl. Sc

Multi-level agent-based modeling - A literature survey

During last decade, multi-level agent-based modeling has received significant and dramatically increasing interest. In this article we present a comprehensive and structured review of literature on the subject. We present the main theoretical contributions and application domains of this concept, with an emphasis on social, flow, biological and biomedical models.Comment: v2. Ref 102 added. v3-4 Many refs and text added v5-6 bibliographic statistics updated. v7 Change of the name of the paper to reflect what it became, many refs and text added, bibliographic statistics update

Teaching employability skills through simulation games

This paper examines the use of a business simulation game to test its effectiveness in promoting the awareness of employability skills in undergraduate students. A mixed approach using an-online survey tool was used to record student perceptions of how their employability skills were developed across ten courses and three faculties. The survey was conducted before the unit started, and on completion. Key emerging themes show that students demonstrated an increased awareness and development of their employability skills. They acquired and developed their skills by learning how to operate a small business start-up using a business simulation game. This research project was limited to one core unit in the curriculum, and the project is university specific. A cross university research project would add further value to the research project. Students are able to articulate the skills they have acquired and developed thus showing elements of self-awareness. An increase in student’s social capital is likely to enhance their career decisions. This paper will be of value to institutions wishing to evaluate the use of serious business simulation games to embed employability skills into the curriculum

Aligning operational and corporate goals: a case study in cultivating a whole-of-business approach using a supply chain simulation game

This paper outlines the development and use of an interactive computer-based supply chain game to facilitate the alignment of disconnected operational and corporate goals. A multi-enterprise internal cattle supply chain was simulated targeting the operational property managers and the overall impacts of their decision making on corporate goals A three stage multidisciplinary approach was used. A case study based financial analysis was undertaken across the internal cattle supply chain, a participative action research component (developing the game to simulate the flow of product and associated decisions and financial transactions through the internal supply chain of the company for different operational scenarios using measurable and familiar operational and financial criteria as tracking tools), and a qualitative analysis of organisational learning through player debriefing following playing the game. Evaluation of the managers' learning around the need for a change in general practice to address goal incongruence was positive evidenced by changes in practice and the game regarded by the users as a useful form of organisational training. The game provided property managers with practical insights into the strategic implications of their enterprise level decisions on the internal supply chain and on overall corporate performance. The game is unique and is a tool that can be used to help address an endemic problem across multi-enterprise industries in the agrifood sector in Australia

Viscous regularization and r-adaptive remeshing for finite element analysis of lipid membrane mechanics

As two-dimensional fluid shells, lipid bilayer membranes resist bending and stretching but are unable to sustain shear stresses. This property gives membranes the ability to adopt dramatic shape changes. In this paper, a finite element model is developed to study static equilibrium mechanics of membranes. In particular, a viscous regularization method is proposed to stabilize tangential mesh deformations and improve the convergence rate of nonlinear solvers. The Augmented Lagrangian method is used to enforce global constraints on area and volume during membrane deformations. As a validation of the method, equilibrium shapes for a shape-phase diagram of lipid bilayer vesicle are calculated. These numerical techniques are also shown to be useful for simulations of three-dimensional large-deformation problems: the formation of tethers (long tube-like exetensions); and Ginzburg-Landau phase separation of a two-lipid-component vesicle. To deal with the large mesh distortions of the two-phase model, modification of vicous regularization is explored to achieve r-adaptive mesh optimization

Stochastic locality and master-field simulations of very large lattices

In lattice QCD and other field theories with a mass gap, the field variables in distant regions of a physically large lattice are only weakly correlated. Accurate stochastic estimates of the expectation values of local observables may therefore be obtained from a single representative field. Such master-field simulations potentially allow very large lattices to be simulated, but require various conceptual and technical issues to be addressed. In this talk, an introduction to the subject is provided and some encouraging results of master-field simulations of the SU(3) gauge theory are reported.Comment: Talk given at the 35th International Symposium on Lattice Field Theory, 18-24 June 2017, Granada, Spain; LaTeX source with 6 figure

Direct calculation of interfacial tensions from computer simulation: Results for freely jointed tangent hard sphere chains

We develop a methodology for the calculation of surface free energies based on the probability distribution of a wandering interface. Using a simple extension of the NpT sampling, we allow the interface area to randomly probe the available space and evaluate the surface free energy from histogram analysis and the corresponding average. The method is suitable for studying systems with either continuous or discontinuous potentials, as it does not require explicit evaluation of the virial. The proposed algorithm is compared with known results for the surface tension of Lennard--Jones and Square Well fluid, as well as for the interface tension of a bead--spring polymer model and good agreement is found. We also calculate interfacial tensions of freely jointed tangent hard sphere chains on athermal walls for a wide range of chain lengths and densities. The results are compared with three different theoretical approaches, Scaled Particle Theory, the Yu and Wu density functional theory and an analytical approximation based on the latter approach. Whereas SPT only yields qualitative results, the last two approaches are found to yield very good agreement with simulations.Comment: 20 pages, 6 figures, Phys. Rev. E in press

THE IMAGINATIVE REHEARSAL MODEL – DEWEY, EMBODIED SIMULATION, AND THE NARRATIVE HYPOTHESIS

In this contribution I outline some ideas on what the pragmatist model of habit ontology could offer us as regards the appreciation of the constitutive role that imagery plays for social action and cognition. Accordingly, a Deweyan understanding of habit would allow for an understanding of imagery in terms of embodied cognition rather than in representational terms. I first underline the motor character of imagery, and the role its embodiment in habit plays for the anticipation of action. Secondly, I reconstruct Dewey's notion of imaginative rehearsal in light of contemporary, competing models of intersubjectivity such as embodied simulation theory and the narrative practice hypothesis, and argue that the Deweyan model offers us a more encompassing framework which can be useful for reconciling these approaches. In this text I am mainly concerned with sketching a broad picture of the lines along which such a project could be developed. For this reason not all questions are given equal attention, and I shall concentrate mainly on the basic ideas, without going directly into the details of many of them