Research Articles (Mathematical Sciences)

 

Recent Submissions

  • A simulation age-specific tuberculosis model for the Cape Town metropole 

    Nyabadza, Farai; Winkler, Dieter (Academy of Science of South Africa, 2013-09-18)
    Tuberculosis (TB) continues to present an insurmountable health burden in the Western Cape Province of South Africa. TB dynamics in adults is different from that in children, with the former determining the latter. Because ...

  • Invading a mutualistic network : to be or not to be similar 

    Minoarivelo, Henintsoa Onivola; Hui, Cang (Wiley Open Access, 2016)
    Biological invasion remains a major threat to biodiversity in general and a disruptor to mutualistic interactions in particular. While a number of empirical studies have directly explored the role of invasion in mutualistic ...

  • A geometrical model for testing bilateral symmetry of bamboo leaf with a simplified Gielis equation 

    Lin, Shuyan; Zhang, Li; Reddy, Gadi V. P.; Hui, Cang; Gielis, Johan; Ding, Yulong; Shi, Peijian (Wiley Open Access, 2016)
    The size and shape of plant leaves change with growth, and an accurate description of leaf shape is crucial for describing plant morphogenesis and development. Bilateral symmetry, which has been widely observed but poorly ...

  • The seesaw effect of winter temperature change on the recruitment of cotton bollworms Helicoverpa armigera through mismatched phenology 

    Reddy, Gadi V. P.; Shi, Peijian; Hui, Cang; Cheng, Xiaofei; Ouyang, Fang; Ge, Feng (John Wiley & Sons Ltd., 2015)
    Knowing how climate change affects the population dynamics of insect pests is critical for the future of integrated pest management. Rising winter temperatures from global warming can drive increases in outbreaks of some ...

  • An optimal proportion of mixing broad-leaved forest for enhancing the effective productivity of moso bamboo 

    Cheng, Xiao-Fei; Shi, Pei-Jian; Hui, Cang; Wang, Fu-Sheng; Liu, Guo-Hua; Li, Bai-Lian (John Wiley & Sons Ltd., 2015-03-17)
    Moso bamboos (Phyllostachys edulis) are important forestry plants in southern China, with substantial roles to play in regional economic and ecological systems. Mixing broad-leaved forests and moso bamboos is a common ...

  • Thermodynamics analysis of variable viscosity hydromagnetic Couette flow in a rotating system with Hall effects 

    Makinde, Oluwole D.; Eegunjobi, Adetayo S.; Tshehla, M. Samuel (MDPI, 2015-11-20)
    In this paper, we employed both first and second laws of thermodynamics to analyze the flow and thermal decomposition in a variable viscosity Couette flow of a conducting fluid in a rotating system under the combined ...

  • Social and genetic networks of HIV-1 transmission in New York City 

    Wertheim, Joel O.; Kosakovsky Pond, Sergei L.; Forgione, Lisa A.; Mehta, Sanjay R.; Murrell, Ben; Shah, Sharmila; Smith, Davey M.; Scheffler, Konrad; Torian, Lucia V. (PLoS, 2017-01-09)
    Background Sexually transmitted infections spread across contact networks. Partner elicitation and notification are commonly used public health tools to identify, notify, and offer testing to persons linked in these ...

  • Modelling the trends of inpatient and outpatient rehabilitation for methamphetamine in the Western Cape province of South Africa 

    Mushanyu, J.; Nyabadza, F.; Stewart, A. G. R. (BioMed Central, 2015-12-18)
    Background: Dependence on methamphetamine remains one of the major health and social problem in the Western Cape province of South Africa. We consider a mathematical model that takes into account two forms of rehabilita ...

  • On the transmission dynamics of Buruli ulcer in Ghana : insights through a mathematical model 

    Nyabadza, Farai; Bonyah, Ebenezer (BioMed Central, 2015-11-06)
    Background: Mycobacterium ulcerans is know to cause the Buruli ulcer. The association between the ulcer and environmental exposure has been documented. However, the epidemiology of the ulcer is not well understood. ...

  • Computational and theoretical analysis of human diseases associated with infectious pathogens 

    Noutchie, Suares Clovis Oukouomi; Kwuimy, Cedrick Aurelien Kitio; Tewa, Jean Jules; Nyabadza, Farai; Bildik, Necdet (Hindawi, 2015)
    Mathematical models and computer simulations are useful experimental tools for building and testing theories, assessing quantitative conjectures, answering specific questions, determining sensitivities to changes in parameter ...

  • On the validity of evolutionary models with site-specific parameters 

    Scheffler, Konrad; Murrell, Ben; Pond, Sergei L. Kosakovsky (PLoS, 2014-04-10)
    Evolutionary models that make use of site-specific parameters have recently been criticized on the grounds that parameter estimates obtained under such models can be unreliable and lack theoretical guarantees of convergence. ...

  • Zeta diversity as a concept and metric that unifies incidence-based biodiversity patterns 

    Hui, Cang; McGeoch, Melodie A. (The University of Chicago Press, 2014-11)
    Patterns in species incidence and compositional turnover are central to understanding what drives biodiversity. Here we propose zeta (ζ) diversity, the number of species shared by multiple assemblages, as a concept and ...

  • Spatial assortment of mixed propagules explains the acceleration of range expansion 

    Ramanantoanina, Andriamihaja; Ouhinou, Aziz; Hui, Cang (Public Library of Science, 2014-08)
    Abstract Range expansion of spreading organisms has been found to follow three types: (i) linear expansion with a constant rate of spread; (ii) bi-phase expansion with a faster linear expansion following a slower linear ...

  • On new high order quasilinearization approaches to the nonlinear model of catalytic reaction in a flat particle 

    Motsa, S. S.; Makinde, O. D.; Shateyi, S. (Hindawi Publishing Corporation, 2013)
    A novel computational approach known as pseudospectral quasilinearization (SQLM) is employed to tackle the two-point boundary value problem describing the reactivity behaviour of porous catalyst particles subject to both ...

  • Entropy generation in a couple stress fluid flow through a vertical channel filled with saturated porous media 

    Makinde, Oluwole Daniel; Eegunjobi, Adetayo Samuel (MDPI, 2013-10-25)
    The present work investigates numerically the inherent irreversibility in a steady flow of a couple stress fluid through a vertical channel packed with saturated porous substances. The First and Second Laws of Thermodynamics ...

  • Model checking rational agents 

    Bordini, Rafael H.; Fisher, Michael; Wooldridge, Michael; Visser, Willem (IEEE - -Institute of Electrical and Electronics Engineers, 2004-10)
    Agent-oriented programming techniques seem appropriate for developing systems that operate in complex, dynamic, and unpredictable environments. We aim to address this requirement by developing model-checking techniques for ...

  • Property-based slicing for agent verification 

    Bordini, Rafael H.; Fisher, Michael; Wooldridge, Michael; Visser, Willem (Oxford University Press (OUP), 2009-12)
    Programming languages designed specifically for multi-agent systems represent a new programming paradigm that has gained popularity over recent years, with some multi-agent programming languages being used in increasingly ...

  • A survey of new trends in symbolic execution for software testing and analysis 

    Pasareanu, Corina S.; Visser, Willem (Springer Verlag, 2009-10)
    Symbolic execution is a well-known program analysis technique which represents program inputs with symbolic values instead of concrete, initialized, data and executes the program by manipulating program expressions involving ...

  • Left ventricular segmentation from MRI datasets with edge modelling conditional random fields 

    Dreijer, Janto F.; Herbst, Ben M.; Du Preez, Johan A. (BioMed Central, 2013-07)
    Background: This paper considers automatic segmentation of the left cardiac ventricle in short axis magnetic resonance images. Various aspects, such as the presence of papillary muscles near the endocardium border, makes ...

  • Non-Negative Matrix Factorization for Learning Alignment-Specific Models of Protein Evolution 

    Murrell, Ben; Weighill, Thomas; Buys, Jan; Ketteringham, Robert; Moola, Sasha; Benade, Gerdus; du Buisson, Lise; Kaliski, Daniel; Hands, Tristan; Scheffler, Konrad (PLOS, 2011-12-22)
    Models of protein evolution currently come in two flavors: generalist and specialist. Generalist models (e.g. PAM, JTT, WAG) adopt a one-size-fits-all approach, where a single model is estimated from a number of different ...

  • Codon test : modeling amino acid substitution preferences in coding sequences 

    Delport, Wayne; Scheffler, Konrad; Botha, Gordon; Gravenor, Mike B.; Muse, Spencer V.; Pond, Sergei L. Kosakovsky (PLOS Computational Biology, 2010-08)
    Codon models of evolution have facilitated the interpretation of selective forces operating on genomes. These models, however, assume a single rate of non-synonymous substitution irrespective of the nature of amino acids ...

  • Modeling HIV-1 drug resistance as episodic directional selection 

    Murrell, Ben; De Oliveira, Tulio; Seebregts, Chris; Pond, Sergei L. Kosakovsky; Scheffler, Konrad (PLOS Computational Biology, 2011-05)
    The evolution of substitutions conferring drug resistance to HIV-1 is both episodic, occurring when patients are on antiretroviral therapy, and strongly directional, with site-specific resistant residues increasing in ...

  • Frequent toggling between alternative amino acids Is driven by selection in HIV-1 

    Delport, Wayne; Scheffler, Konrad; Seoighe, Cathal (Public Library of Science, 2008)
    Host immune responses against infectious pathogens exert strong selective pressures favouring the emergence of escape mutations that prevent immune recognition. Escape mutations within or flanking functionally conserved ...

  • Correcting the bias of empirical frequency parameter estimators in codon models 

    Kosakovsky Pond, Sergei; Delport, Wayne; Muse, Spencer V.; Scheffler, Konrad (Public Library of Science -- PLOS, 2010-07)
    Markov models of codon substitution are powerful inferential tools for studying biological processes such as natural selection and preferences in amino acid substitution. The equilibrium character distributions of these ...

  • The geometry of unitary 2-representations of finite groups and their 2-characters 

    Bartlett, Bruce (Springer Link, 2011-02)
    Motivated by topological quantum field theory, we investigate the geometric aspects of unitary 2-representations of finite groups on 2-Hilbert spaces, and their 2-characters. We show how the basic ideas of geometric ...

  • Francis Guthrie : a colourful life 

    Maritz, Pieter; Mouton, Sonja (Springer, 2012-09)
    In 1852, in London, Francis Guthrie posed the question of colouring a map with four colours only, the question that eventually became known as the Four Colour Problem. The problem is famous, but what else do we know of ...

  • Detecting individual sites subject to episodic diversifying selection 

    Murrell, Ben; Wertheim, Joel O.; Moola, Sasha; Weighill, Thomas; Scheffler, Konrad; Pond, Sergei L. Kosakovsky (Public Library of Science, 2012-07-02)
    The imprint of natural selection on protein coding genes is often difficult to identify because selection is frequently transient or episodic, i.e. it affects only a subset of lineages. Existing computational techniques, ...

  • Realization of abstract convex geometries by point configurations 

    Adaricheva, Kira; Wild, Marcel (Elsevier, 2010-01)
    The Edelman-Jamison problem is to characterize those abstract convex geometries that are representable by a set of points in the plane. We show that some natural modification of the Edelman-Jamison problem is equivalent ...

  • The asymptotic number of binary codes and binary matroids 

    Wild, Marcel (Society for Industrial and Applied Mathematics (SIAM), 2006-08)
    The asymptotic number of nonequivalent binary n-codes is determined. This is also the asymptotic number of nonisomorphic binary matroids on n elements.

  • Modelling the South African fruit export infrastructure : a case study 

    Ortmann, F. G.; Van Vuuren, J. H.; Van Dyk, F. E. (Operations Research Society of South Africa, 2006)
    A description is provided of work performed as part of the fruit logistics infrastructure project commissioned by the South African Deciduous Fruit Producers’ Trust and coordinated by the South African Council for ...

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