Long wavelength structural anomalies in jammed systems

The structural properties of static, jammed packings of monodisperse spheres in the vicinity of the jamming transition are investigated using large-scale computer simulations. At small wavenumber $k$, we argue that the anomalous behavior in the static structure factor, $S(k) \sim k$, is consequential of an excess of low-frequency, collective excitations seen in the vibrational spectrum. This anomalous feature becomes more pronounced closest to the jamming transition, such that $S(0) \to 0$ at the transition point. We introduce an appropriate dispersion relation that accounts for these phenomena that leads us to relate these structural features to characteristic length scales associated with the low-frequency vibrational modes of these systems. When the particles are frictional, this anomalous behavior is suppressed providing yet more evidence that jamming transitions of frictional spheres lie at lower packing fractions that that for frictionless spheres. These results suggest that the mechanical properties of jammed and glassy media may therefore be inferred from measurements of both the static and dynamical structure factors.Comment: 8 pages, 6 figure captions. Completely revised version to appear in Phys. Rev.

A polarizable ion model for the structure of molten AgI

The results are reported of the molecular dynamics simulations of the coherent static structure factor of molten AgI at 923 K using a polarizable ion model. This model is based on a rigid ion potential, to which the many body interactions due to the anions induced polarization are added. The calculated structure factor is in better agreement with recent neutron diffraction data than that obtained by using simple rigid ion pair potentials. The Voronoi-Delaunay method has been applied to study the relationship between voids in the spatial distribution of cations and the prepeak of the structure factor.Comment: 12 pages, 4 figure

INDISIM-YEAST, an individual-based model to study yeast

INDISIM-YEAST, an individual-based simulator, models the evolution of a yeast population by setting up rules of behaviour for each individual cell according to their own biological rules and characteristics. It takes into account the uptake, metabolism, budding reproduction and viability of the yeast cells, over a period of time in the bulk of a liquid medium, occupying a three dimensional closed spatial grid with two kinds of particles (glucose and ethanol). Each microorganism is characterized by its biomass, genealogical age, states in the budding cellular reproduction cycle and position in the space among others. Simulations are carried out for population properties (global properties), as well as for those properties that pertain to individual yeast cells (microscopic properties). The results of the simulations are in good qualitative agreement with established experimental trends.Peer Reviewe

Exploring lag phase and growth initiation of a yeast culture by means of an Individual-based Model

Postprint (published version

Effect of the inoculum characteristics on the first stages of a growing yeast population in beer fermentations by means of an individual-based Model

Postprint (published version

The structure of molten AgCl revisited

We have studied the total structure of molten AgCl at 1073 K by means of two polarizable ion models via molecular dynamics simulations. The model potentials consisted of either the Vashishta–Rahman (VR) or the Born–Mayer rigidion potentials to which the anion-induced polarization contribution is added. Both model potentials reproduce well the main features of the structure of molten AgCl with that using the VR model potential giving marginally better results

The structure of molten AgCl revisited

We have studied the total structure of molten AgCl at 1073 K by means of two polarizable ion models via molecular dynamics simulations. The model potentials consisted of either the Vashishta–Rahman (VR) or the Born–Mayer rigidion potentials to which the anion-induced polarization contribution is added. Both model potentials reproduce well the main features of the structure of molten AgCl with that using the VR model potential giving marginally better results.Postprint (published version