Self-portrait on the Ponte de Dom Luís I

David C Groothuizen Dijkema

I am a doctoral candidate in mathematics at the University of Auckland, under the supervision of Professors Claire Postlethwaite and Vivien Kirk. I am interested in the mathematical theory of dynamical systems, and my thesis is about dynamics near structures known as heteroclinic networks.

My email: david.groothuizen.dijkema@auckland.ac.nz

My University of Auckland profile.

My CV.

Publications and Preprints

  1. David C Groothuizen Dijkema and Claire M Postlethwaite. (2023). Travelling waves and heteroclinic networks in models of spatially-extended cyclic competition. Nonlinearity, 36(12) 6546—6588. DOI: 10.1088/1361-6544/ad0212. arXiv: 2208.05630 [math.DS]

Talks and Posters

Talks

  1. 13 February 2024: Switching and cycling near heteroclinic networks as a piecewise-smooth dynamical system, Australia and New Zealand Industrial and Applied Mathematics (ANZIAM) Conference, Hahndorf, SA, Australia.
  2. 1 December 2023: Switching and cycling near heteroclinic networks as a piecewise-smooth dynamical system, New Zealand Mathematical Society (NZMS) Colloquium, Victoria University of Wellington, NZ. (Received an honourable mention for the NZMS Aitken Award for Best Student Talk.)
  3. 29 November 2023: Travelling waves and heteroclinic networks in spatially-extended models of cyclic competition, New Zealand Mathematics and Statistics Postgraduate (NZMASP) Conference, Victoria University of Wellington, NZ.
  4. 27 June 2023: Dynamics near heteroclinic cycles and networks, Leeds Applied Nonlinear Dynamics (LAND) Seminar, Department of Mathematics, University of Leeds, UK.
  5. 23 June 2023: Dynamics near heteroclinic cycles and networks, Centro de Matemática - Universidade do Porto (CMUP) Seminar, Universidade do Porto, Portugal.
  6. 12 May 2023: Switching near heteroclinic networks as a piecewise-smooth dynamical system, SIAM Conference on Applications of Dynamical Systems, Portland, OR, USA.
  7. 14 November 2022: Switching near heteroclinic networks as a piecewise-smooth system, Sydney Dynamics Group Workshop: Dynamical Systems in NZ - Castaways, Auckland, NZ.
  8. 6 October 2022: Switching near heteroclinic networks as a piecewise-smooth system, Applied Mathematics Unit (AMU) Postgraduate Students Seminar, Department of Mathematics, University of Auckland, NZ.
  9. 7 June 2022: Stability and cycling near heteroclinic cycles and networks, Student Research Conference, Department of Mathematics, University of Auckland, NZ.
  10. 21 July 2021: Spatially extended models of competition between four species, Postgraduate Students Seminar, Department of Mathematics, University of Auckland, NZ. (Received one of four prizes for best talk.)
  11. 8 June 2021: A spatially-extended model of competition between four species, Student Research Conference, Department of Mathematics, University of Auckland, NZ.
  12. 4 February 2021: Heteroclinic networks in partial differential equations, Summer Research Students Conference, Department of Mathematics, University of Auckland, NZ.

Here is the animation that accompanies many of the above talks:

This animation is an example of a trajectory near the Guckenheimer-Holmes cycle, the prototypical example of a heteroclinic cycle. It was first considered by May and Leonard (though not using the terminology of heteroclinic cycles) in their study of nonlinear competition between three species. Each of the three coordinates represents the density of each of three species which compete with each other in a cyclic manner, just like the game of Rock-Paper-Scissors. In their words,

…[A] nonlinear study of this domain of parameter space reveals … a wider class of asymptotic solutions in which the system cycles from being composed almost wholly of population 1, to almost wholly 2, to almost wholly 3, back to 1, but with the time to complete the cycle becoming longer and longer (being proportional to the length of time the system has been running), and with the system coming in turn ever closer to the points with 1 alone, 2 alone and 3 alone, yet never actually converging on any one point.

May R and Leonard L 1975 SIAM J. Appl. Math. 29 243

Posters

  1. 4 December 2023: Travelling waves and heteroclinic networks in spatially-extended models of cyclic competition, New Zealand Mathematical Society (NZMS) Colloquium, Victoria University of Wellington, NZ. (Received the ANZIAM Award for Best Poster Presentation.)
  2. 13 October 2022: Switching near heteroclinic networks as a piecewise-smooth dynamical system, Antipodeal Dynamics Workshop, Centre for Systems, Dynamics and Control, Department of Mathematics, University of Exeter, UK and the Department of Mathematics, University of Auckland, NZ.

My surname

My surname is Dutch, and maximally unpronounceable. The way I say it in English is [ɡɹʉːθ'hɐʉ̯ˌzɪn dæɪ̯'kɪˌmɐ]. The correct way to say it in Dutch, however, is [ˈɣɾoːt.ɦœy̯.zə(n) ˈdɛi̯.kə.mɑ]. In the dialect where my family is from, it is said [ˈχɾɔu̯t.hœː.sə ˈdɛː.kə.mɑ].

If you don't know IPA for some reason, then the way to say my name in English is "grooth-HOW-zin day-KI-mə".