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We propose a new approach for using GPUs in large scale simulations of pedestrian evacuation. The Social Distances Model is designed for efficient modeling of pedestrian dynamics. This cellular automata based model, when implemented on the most modern GPUs, can simulate up to 106–108 entities. However, a valuable simulation of pedestrian evacuation must include various factors that govern pedestrian movement, for example, information provided by event organizers and navigation or allocation of other pedestrians. The most common method for introducing such information into simulations is the application of different floor fields. The floor fields provide “local knowledge” that affects pedestrians by modifying the transition functions of an applied cellular automaton. The main disadvantage of this method is its time consuming updating process. We propose a GPU based calculation of static and dynamic floor fields, whereby simulations that use several different floor fields can be efficiently calculated. A single GPU is able to cope with the Social Distance Model calculations, while other GPUs update dynamic floor fields constantly or when required. We also present the classic approach to performing cellular automata based simulations on systems with multiple processing units. The lattice is simply partitioned between the available GPUs. We compare these two approaches in terms of performance and functionality. [ABSTRACT FROM AUTHOR]

We present a new two-level numerical model describing the evolution of transportation network. Two separate but mutually interacting sub-systems are investigated: a starving environment and the network. We assume that the slow modes of the environment growth can be modeled with classical cellular automata (CA) approach. The fast modes representing the transportation network, we approximate by the graph of cellular automata (GCA). This allows the simulation of transportation systems over larger spatio-temporal scales and scrutinizing global interactions between the network and the environment. We show that the model can mimic the realistic evolution of complex river systems. We also demonstrate how the model can simulate a reverse situation. We conclude that the paradigm of this model can be extended further to a general framework, approximating many realistic multiscale transportation systems in diverse fields such as geology, biology and medicine. [ABSTRACT FROM AUTHOR]

Although the emergence of complex biomineralized forms has been investigated for over a century, still little is known on how single cells control morphology of skeletal structures, such as frustules, shells, spicules, or scales. We have run experiments on the shell formation in foraminifera, unicellular, mainly marine organisms that can build shells by successive additions of chambers. We used live imaging to discover that all stages of chamber/shell formation are controlled by dedicated actin-driven pseudopodial structures. Successive reorganization of an F-actin meshwork, associated with microtubular structures, is actively involved in formation of protective envelope, followed by dynamic scaffolding of chamber morphology. Then lamellar dynamic templates create a confined space and control mineralization separated from seawater. These observations exclude extracellular calcification assumed in selected foraminiferal clades, and instead suggest a semiintracellular biomineralization pattern known from other unicellular calcifying and silicifying organisms. These results give a challenging prospect to decipher the vital effect on geochemical proxies applied to paleoceanographic reconstructions. They have further implications for understanding multiscale complexity of biomineralization and show a prospect for material science applications. [ABSTRACT FROM AUTHOR]