Google Earth 12 43' N, 3 09' E

Homepage of Sjors van der Stelt

Sjors van der Stelt MSc
Korteweg-de Vries Instituut Faculteit FNWI
Universiteit van Amsterdam

Office

Science Park 904
1098 XH Amsterdam
The Netherlands

Postal address

P.O. Box 94248
1090 GE Amsterdam 

 Tel:  +31-20-592-4091
E-mail: S.vanderstelt at uva dot nl

Mathematical

PhD student in applied analysis, partial differential equations and dynamical systems since March 2007.

Research

The research I am involved in focuses on the modelling of vegetation patterns. Vegetation patterns are spotted or striped patterns that are found on the edge of deserts around the world. One can view the patterns on the different pictures on this website. They may be seen as forecast for desertification, a process that has speeded up during the last years as a consequence of climate change and overgrazing by cattle. Ecologists such as Max Rietkerk have developed mathematical models that are meant to model the patterns. From a mathematician's point of view, these models are nonlinear reaction-diffusion or reaction-advection equations. We study one particular model, that may be seen as both a generalization of Klausmeier's 1999 model and as a generalization of the by now well-studied Gray-Scott model from the early eigthies -- in fact, the model we study is a system of reaction-advection-diffusion equations, in which the amount of available water in an ecosystem has a nonlinear interplay with the biomass. People involved in the project are Arjen Doelman, Geertje Hek, Jens Rademacher, and Max Rietkerk.

One can download a Google Placemark File developed by Max Rietkerk and Johan van de Koppel that enables you to make a journey around the earth with Google Earth and view pattern formation in different ecosystems.

Steppe in southern Mongolia, near the Gobi. Vegetation Patterns in Niger, 12 43' N, 3 09' E. © Google Earth Mountains in southern Mongolia, near the Gobi. Altitude
© Sjors van der Stelt approx. 2 kms above sea level. © Sjors van der Stelt

Publications

Talks

AUTO Package

AUTO is a bifurcation and continuation package that is used by many applied mathematicians (and the like) to obtain insight in the existence and stability of bifurcation solutions for a (system of) PDE(s) at some critical value. It uses a so-called constants file, more about which is explained in Doedel et al. For users of AUTO, I have written the so called Online Guide to Auto Constants that may serve as a reminder for the definitions of these constants.

Reading Group Pattern Formation

Participants: Arjen Doelman, Ale Jan Homburg, Jens Rademacher, Vivi Rottschäfer, Martin van der Schans, Sjors van der Stelt, Huib de Swart, Antonios Zagaris, Julia Zijlstra.
We will read the book Pattern Formation by Rebecca Hoyle (Univ. of Surrey). Meetings will generally be hold at CWI Amsterdam.

Date Speaker Topic
February 4, 2009 none Bifurcation theory, center manifold reduction
February 25, 2009 Julia Zijlstra Symmetry, groups
March 18, 2009 Julia Zijlstra Semidirect products, Lie groups and representations
April 8, 2009 Sjors van der Stelt Bifurcations with symmetry 1: the Equivariant Branching Lemma
June 10, 2009 Sjors van der Stelt Bifurcations with symmetry 2: Hopf bifurcations with symmetry
June 24, 2009 Sjors van der Stelt Bifurcations with symmetry 3: Bifurcations in a Box
September 7, 2009 Martin van der Schans Simple Lattice Patterns 1: steady bifurcations
September 21, 2009 Martin van der Schans Simple Lattice Patterns 2: other bifurcations
October 5, 2009 Julia Zijlstra Superlattices, hidden symmetries and other complications

Onderwijs (Education)

  • 2009: Lineaire algebra
  • 2009: Lineaire analyse
    • Een (mijns inziens weinig fraaie) uitwerking van een deel van opgave 2.14. De extra opgave van 26 februari.
  • 2008: Bètagamma Wiskundige Methoden en Technieken
  • 2008: Dynamische systemen
  • 2007: Modelbouw
  • 2007: Wiskunde Medische Informatiekunde Module 3
  • 2007: Wiskunde Medische Informatiekunde Module 8 (kansrekening)
  • 2007: Continue Wiskunde & Stochastiek voor Informatici
  • 2007: Wiskunde Medische Informatiekunde Module 5 (lineaire algebra en differentiaalvergelijkingen)

    • AIO Seminar

    I was co-organizer with Abdelghafour Es-Saghouani of the AiO Seminar that is to be held at Fridays during the year 2008-2009.
    During the academic year 2009-2010, I am managing organizer of the AIO seminar (website will come shortly) in cooperation with Enno Veerman and Ricardo Reis da Silva.

    Non-mathematical

    Uitgave boek bomen Artis en Hortus (in Dutch)

    Binnen redelijke termijn zal de tweede uitgave van het boek De Bomen in Artis en Hortus van mijn vader Hans van der Stelt verschijnen. Het boek behandelt een flink aantal van de soms 'gewone', soms heel zeldzame bomen uit de arboreta Artis en Hortus Botanicus te Amsterdam. De tekeningen zijn van de hand van Hans van der Stelt, met in de nieuwe uitgave tekeningen van enkele nieuw besproken bomen van mijn grootmoeder Hilde van der Stelt-Strijbos. Hans van der Stelt zelf is door ziekte helaas niet meer in staat de tekeningen te maken. De teksten bij de tekeningen zijn geschreven in een heldere, voor leken begrijpelijke stijl maar niet zonder allerlei wetenswaardigheden die ook voor specialisten interessant zijn.
    Het boek zal worden uitgebracht door uitgever Architectura en Natura en de vormgeving wordt opnieuw verzorgd door de bekende vormgever Piet Schreuders. Het gehele project wordt door mij aangestuurd.

    More

    I am also secretary of the board of the union of residents that live in the Amsterdam monument Het Nieuwe Huis. In 2009, the building is renovated. This project is led by the union board of Het Nieuwe Huis in cooperation with corporation Samenwerking that owns and hires the building to the union.
    Besides all this, until recently, I worked in Brasserie Harkema one evening a week, just for the fun of it.

    Last update of this page : Juli 24, 2009 CET

    free hit counter