12,903 research outputs found
The role of topology and mechanics in uniaxially growing cell networks
In biological systems, the growth of cells, tissues, and organs is influenced
by mechanical cues. Locally, cell growth leads to a mechanically heterogeneous
environment as cells pull and push their neighbors in a cell network. Despite
this local heterogeneity, at the tissue level, the cell network is remarkably
robust, as it is not easily perturbed by changes in the mechanical environment
or the network connectivity. Through a network model, we relate global tissue
structure (i.e. the cell network topology) and local growth mechanisms (growth
laws) to the overall tissue response. Within this framework, we investigate the
two main mechanical growth laws that have been proposed: stress-driven or
strain-driven growth. We show that in order to create a robust and stable
tissue environment, networks with predominantly series connections are
naturally driven by stress-driven growth, whereas networks with predominantly
parallel connections are associated with strain-driven growth
Gandy-Paun-Rozenberg Machines
Gandy-Paun-Rozenberg machines are introduced as certain graph rewriting
systems. A representation of Gandy-Paun-Rozenberg machines by Gandy machines is
given. A construction of a Gandy-Paun-Rozenberg machine solving 3-SAT problem in a
polynomial time is shown
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