Browsing Research Articles (Mathematical Sciences) by Title

Now showing items 11-30 of 37

    • 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 ...

    • 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 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 ...

    • 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 ...

    • 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 ...

    • 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 ...

    • 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 ...

    • 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 ...

    • 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 ...

    • 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 ...

    • 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 ...

    • 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. ...

    • 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. ...

    • 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 ...

    • Partitioning the hypercube Qn into n isomorphic edge-disjoint trees 

      Wagner, Stephan; Wild, Marcel (TU Graz University of Technology, 2011)
      ENGLISH ABSTRACT: The problem of finding edge-disjoint trees in a hypercube e.g. arises in the context of parallel computing. Independent of applications it is of high aesthetic appeal.

    • 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 ...

    • 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 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 ...

    • 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 ...

    • 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 ...