Maria Bruna | University of Oxford (original) (raw)
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Papers by Maria Bruna
This project considers the retrieval of vanadium and similar valuable by-products when producing ... more This project considers the retrieval of vanadium and similar valuable by-products when producing steel from iron sands. This recovery should be optimised without compromising steel production. The process is modelled with a system of differential equations. A method is outlined that optimises vanadium recovery once parameters have been identified experimentally.
PLoS Computational Biology, 2014
Journal of Fluid Mechanics, 2014
In this paper we examine the effect that physiological non-polar lipids, residing on the surface ... more In this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non-polar lipid layer, the thickness of the aqueous layer and the concentration of polar lipids which reside at the interface between the two. We also utilise a force balance in the non-polar lipid layer in order to determine its velocity. We show how to obtain previous models in the literature from our model by making particular choices of the parameters. We see the formation of boundary layers in some of these submodels, across which the concentration of polar lipid and the non-polar lipid velocity and film thickness vary. We solve our model numerically for physically realistic parameter values, and we find that the evolution of the aqueous layer and the polar lipid layer are similar to that described by previous authors. However, there are interesting dynamics for the non-polar lipid layer. The effects of altering the key parameters are highlighted and discussed. In particular, we see that the Marangoni number plays a key role in determining how far over the eye the non-polar lipid spreads.
The Journal of Chemical Physics, 2014
The quasi-steady-state approximation (or stochastic averaging principle) is a useful tool in the ... more The quasi-steady-state approximation (or stochastic averaging principle) is a useful tool in the study of multiscale stochastic systems, giving a practical method by which to reduce the number of degrees of freedom in a model. The method is extended here to slow-fast systems in which the fast variables exhibit metastable behaviour. The key parameter that determines the form of the reduced model is the ratio of the timescale for the switching of the fast variables between metastable states to the timescale for the evolution of the slow variables. The method is illustrated with two examples: one from biochemistry (a fast-species-mediated chemical switch coupled to a slower-varying species), and one from ecology (a predator-prey system). Numerical simulations of each model reduction are compared with those of the full system.
PLOS Computational Biology, 2015
This project considers the retrieval of vanadium and similar valuable by-products when producing ... more This project considers the retrieval of vanadium and similar valuable by-products when producing steel from iron sands. This recovery should be optimised without compromising steel production. The process is modelled with a system of differential equations. A method is outlined that optimises vanadium recovery once parameters have been identified experimentally.
PLoS Computational Biology, 2014
Journal of Fluid Mechanics, 2014
In this paper we examine the effect that physiological non-polar lipids, residing on the surface ... more In this paper we examine the effect that physiological non-polar lipids, residing on the surface of an aqueous tear film, have on the film evolution. In our model we track the evolution of the thickness of the non-polar lipid layer, the thickness of the aqueous layer and the concentration of polar lipids which reside at the interface between the two. We also utilise a force balance in the non-polar lipid layer in order to determine its velocity. We show how to obtain previous models in the literature from our model by making particular choices of the parameters. We see the formation of boundary layers in some of these submodels, across which the concentration of polar lipid and the non-polar lipid velocity and film thickness vary. We solve our model numerically for physically realistic parameter values, and we find that the evolution of the aqueous layer and the polar lipid layer are similar to that described by previous authors. However, there are interesting dynamics for the non-polar lipid layer. The effects of altering the key parameters are highlighted and discussed. In particular, we see that the Marangoni number plays a key role in determining how far over the eye the non-polar lipid spreads.
The Journal of Chemical Physics, 2014
The quasi-steady-state approximation (or stochastic averaging principle) is a useful tool in the ... more The quasi-steady-state approximation (or stochastic averaging principle) is a useful tool in the study of multiscale stochastic systems, giving a practical method by which to reduce the number of degrees of freedom in a model. The method is extended here to slow-fast systems in which the fast variables exhibit metastable behaviour. The key parameter that determines the form of the reduced model is the ratio of the timescale for the switching of the fast variables between metastable states to the timescale for the evolution of the slow variables. The method is illustrated with two examples: one from biochemistry (a fast-species-mediated chemical switch coupled to a slower-varying species), and one from ecology (a predator-prey system). Numerical simulations of each model reduction are compared with those of the full system.
PLOS Computational Biology, 2015