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- Dirk Helbing, Anders Johansson, Joachim Mathiesen, Mogens H Jensen, Alex Hansen
- Physical review letters
- 2006

We propose a many-particle-inspired theory for granular outflows from a hopper and for the escape dynamics through a bottleneck based on a continuity equation in polar coordinates. If the inflow is below the maximum outflow, we find an asymptotic stationary solution. If the inflow is above this value, we observe queue formation, which can be described by a… (More)

- Jeppe Juul, Kim Sneppen, Joachim Mathiesen
- Physical review. E, Statistical, nonlinear, and…
- 2013

The spatial rock-paper-scissors ecosystem, where three species interact cyclically, is a model example of how spatial structure can maintain biodiversity. We here consider such a system for a broad range of interaction rates. When one species grows very slowly, this species and its prey dominate the system by self-organizing into a labyrinthine… (More)

- Stéphane Santucci, Knut Jørgen Måløy, +6 authors Purusattam Ray
- Physical review. E, Statistical, nonlinear, and…
- 2007

We analyze the statistical distribution function for the height fluctuations of brittle fracture surfaces using extensive experimental data sampled on widely different materials and geometries. We compare a direct measurement of the distribution to an analysis based on the structure functions. For length scales delta larger than a characteristic scale… (More)

- J. Mathiesen, I. Procaccia, H. L. Swinney, M. Thrasher
- 2006

– We investigate whether fractal viscous fingering and diffusion-limited aggregates are in the same scaling universality class. We bring together the largest available viscous fingering patterns and a novel technique for obtaining the conformal map from the unit circle to an arbitrary singly connected domain in two dimensions. These two Laplacian fractals… (More)

- Eran Bouchbinder, Joachim Mathiesen, Itamar Procaccia
- Physical review. E, Statistical, nonlinear, and…
- 2004

The calculation of the stress field around an arbitrarily shaped crack in an infinite two-dimensional elastic medium is a mathematically daunting problem. With the exception of few exactly soluble crack shapes the available results are based on either perturbative approaches or on combinations of analytic and numerical techniques. We present here a general… (More)

- Maria Thomsen, Anier Hernandez-Garcia, +4 authors Robert Feidenhans'l
- PloS one
- 2014

In this study we estimate the subcutaneous tissue counter pressure during drug infusion from a series of injections of insulin in type 2 diabetic patients using a non-invasive method. We construct a model for the pressure evolution in subcutaneous tissue based on mass continuity and the flow laws of a porous medium. For equivalent injection forces we… (More)

- Joachim Mathiesen, Namiko Mitarai, Kim Sneppen, Ala Trusina
- Physical review letters
- 2011

Ecological systems comprise an astonishing diversity of species that cooperate or compete with each other forming complex mutual dependencies. The minimum requirements to maintain a large species diversity on long time scales are in general unknown. Using lichen communities as an example, we propose a model for the evolution of mutually excluding organisms… (More)

- Namiko Mitarai, Joachim Mathiesen, Kim Sneppen
- Physical review. E, Statistical, nonlinear, and…
- 2012

The biological requirements for an ecosystem to develop and maintain species diversity are in general unknown. Here we consider a model ecosystem of sessile and mutually excluding organisms competing for space [Mathiesen et al. Phys. Rev. Lett. 107, 188101 (2011)]. Competition is controlled by an interaction network with fixed links chosen by a Bernoulli… (More)

- V Reeve, J Mathiesen, W Fong
- Journal of forensic sciences
- 1976

Eighty-one glass samples were analyzed by EDX; two were indistinguishable. However, when the physical properties of the glass samples were considered, all glass samples were distinguishable from each other. The need to examine glass with respect not only to physical properties but also to elemental composition has been demonstrated. The authors believe that… (More)

- Joachim Mathiesen, Luiza Angheluta, Peter T. H. Ahlgren, Mogens H. Jensen
- Proceedings of the National Academy of Sciences…
- 2013

Using empirical data from a social media site (Twitter) and on trading volumes of financial securities, we analyze the correlated human activity in massive social organizations. The activity, typically excited by real-world events and measured by the occurrence rate of international brand names and trading volumes, is characterized by intermittent… (More)