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Now showing items 58-77 of 357

  • A Computer Simulation Study of Anatomy Induced Drift of Spiral Waves in the Human Atrium 

    Kharche, Sanjay R.; Biktasheva, I. V.; Seemann, Gunnar; Zhang, Henggui; Biktashev, V. N. (Hindawi Publishing Corporation, 2014)
    The interaction of spiral waves of excitation with atrial anatomy remains unclear. This simulation study isolates the role of atrial anatomical structures on spiral wave spontaneous drift in the human atrium. We implemented ...
  • Conditions for propagation and block of excitation in an asymptotic model of atrial tissue. 

    Simitev, R. D.; Biktashev, V. N. (2006)
    Detailed ionic models of cardiac cells are difficult for numerical simulations because they consist of a large number of equations and contain small parameters. The presence of small parameters, however, may be used for ...
  • Conditions for sink-to-source transitions and runaway feedbacks from the land carbon cycle 

    Cox, Peter M.; Huntingford, Chris; Jones, Chris D. (Cambridge University Press, 2006-02)
    The first GCM climate-carbon cycle simulation indicated that the land biosphere could provide a significant acceleration of 21st century climate change (Cox et al. 2000). In this numerical experiment the carbon storage was ...
  • Cone exchange transformations and boundedness of orbits 

    Ashwin, Peter; Goetz, Arek (Cambridge University Press, 2010)
    We introduce a class of two-dimensional piecewise isometries on the plane that we refer to as cone exchange transformations (CETs). These are generalizations of interval exchange transformations (IETs) to 2D unbounded ...
  • Confidence in Classification: A Bayesian Approach 

    Krzanowski, Wojtek J.; Bailey, Trevor C.; Partridge, Derek; Fieldsend, Jonathan E.; Everson, Richard M.; Schetinin, Vitaly (Springer Verlag, 2006)
    Bayesian classification is currently of considerable interest. It provides a strategy for eliminating the uncertainty associated with a particular choice of classifiermodel parameters, and is the optimal decision-theoretic ...
  • Confident interpretation of Bayesian decision tree ensembles for clinical applications 

    Schetinin, Vitaly; Fieldsend, Jonathan E.; Partridge, Derek; Coats, Timothy J.; Krzanowski, Wojtek J.; Everson, Richard M.; Bailey, Trevor C.; Hernandez, Adolfo (Institute of Electrical and Electronics Engineers (IEEE), 2007)
    Bayesian averaging (BA) over ensembles of decision models allows evaluation of the uncertainty of decisions that is of crucial importance for safety-critical applications such as medical diagnostics. The interpretability ...
  • A conjecture of Stanley on alternating permutations 

    Chapman, Robin; Williams, Lauren K. (Electronic Journal of Combinatorics, 2007)
    We give two simple proofs of a conjecture of Richard Stanley concerning the equidistribution of derangements and alternating permutations with the maximal number of fixed points.
  • Context-dependent interaction leads to emergent search behavior in social aggregates 

    Torney, Colin; Neufeld, Zoltan; Couzin, Iain D. (National Academy of Sciences, 2009)
    Locating the source of an advected chemical signal is a common challenge facing many living organisms. When the advecting medium is characterized by either high Reynolds number or high Peclet number, the task becomes highly ...
  • Control of scroll-wave turbulence using resonant perturbations 

    Morgan, S. W.; Biktasheva, I. V.; Biktashev, V. N. (American Physical Society, 2008)
    Turbulence of scroll waves is a sort of spatiotemporal chaos that exists in three-dimensional excitable media. Cardiac tissue and the Belousov-Zhabotinsky reaction are examples of such media. In cardiac tissue, chaotic ...
  • Control-based continuation of unstable periodic orbits 

    Sieber, J.; Krauskopf, Bernd; Wagg, David; Neild, Simon; Gonzalez-Buelga, A. (American Society of Mechanical Engineers (ASME), 2011)
    We present an experimental procedure to track periodic orbits through a fold (saddle-node) bifurcation and demonstrate it with a parametrically excited pendulum experiment where the tracking parameter is the amplitude of ...
  • Controlling unstable chaos: stabilizing chimera states by feedback 

    Sieber, J.; Omel'chenko, Oleh E.; Wolfrum, Matthias (American Physical Society, 2014)
    We present a control scheme that is able to find and stabilize an unstable chaotic regime in a system with a large number of interacting particles. This allows us to track a high dimensional chaotic attractor through a ...
  • Convergence to local random attractors 

    Ashwin, Peter; Ochs, Gunter (Taylor & Francis, 2003)
    Random attractors allow one to classify qualitative and quantitative aspects of the long-time behaviour of stochastically forced systems viewed as random dynamical systems (RDS) in an analogous way to attractors for ...
  • Coronal Alfvén speed determination : consistency between seismology using AIA/SDO transverse loop oscillations and magnetic extrapolation 

    Verwichte, E.; Van Doorsselaere, T.; Foullon, Claire; White, R.S. (American Astronomical Society / IOP Publishing, 2013)
    Two transversely oscillating coronal loops are investigated in detail during a flare on the 2011 September 6 using data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. We compare two ...
  • Correcting the finite-ensemble bias of the ignorance score 

    Siegert, Stefan; Ferro, Christopher A.T.; Stephenson, David B. (Royal Meteorological Society, 2015)
    This study considers the application of the Ignorance Score (also known as the Logarithmic Score) in the context of ensemble verification. In particular, we consider the case where an ensemble forecast is transformed to a ...
  • A counterexample to "positive realness preserving model reduction with ℋ∞ norm error bounds" 

    Guiver, Chris; Opmeer, Mark R. (Institute of Electrical and Electronics Engineers (IEEE), 2011)
    We provide a counterexample to the H∞ error bound for the difference of a positive real transfer function and its positive real balanced truncation stated in “Positive realness preserving model reduction with H∞ norm error ...
  • Countertraveling waves in rotating Rayleigh-Bénard convection. 

    Li, Ligang; Liao, X.; Zhang, Keke (American Physical Society, 2008)
    Linear and nonlinear counter-traveling waves in a fluid-filled annular cylinder with realistic no-slip boundary conditions uniformly heated from below and rotating about a vertical axis are investigated. When the gap of ...
  • Criteria for robustness of heteroclinic cycles in neural microcircuits. 

    Ashwin, Peter; Karabacak, Ozkan; Nowotny, Thomas (BioMed Central / SpringerOpen, 2011)
    We introduce a test for robustness of heteroclinic cycles that appear in neural microcircuits modeled as coupled dynamical cells. Robust heteroclinic cycles (RHCs) can appear as robust attractors in Lotka-Volterra-type ...
  • Critical fronts in initiation of excitation waves 

    Idris, I.; Biktashev, V. N. (American Physical Society, 2007)
    We consider the problem of initiation of propagating waves in a one-dimensional excitable fiber. In the FitzHugh-Nagumo theory, the key role is played by "critical nucleus" and "critical pulse" solutions whose (center-) ...
  • Cycling chaos: its creation, persistence and loss of stability in a model of nonlinear magnetoconvection 

    Ashwin, Peter; Rucklidge, Alastair M. (Elsevier, 1998)
    We examine a model system where attractors may consist of a heteroclinic cycle between chaotic sets; this `cycling chaos' manifests itself as trajectories that spend increasingly long periods lingering near chaotic invariant ...
  • Cycling chaotic attractors in two models for dynamics with invariant subspaces 

    Ashwin, Peter; Rucklidge, Alastair M.; Sturman, Rob (American Institute of Physics, 2004)
    Nonergodic attractors can robustly appear in symmetric systems as structurally stable cycles between saddle-type invariant sets. These saddles may be chaotic giving rise to "cycling chaos." The robustness of such attractors ...