Andy T. Augousti

Ion flux through membrane channels—An enhanced algorithm for the Poisson-Nernst-Planck model

A novel algorithmic scheme for numerical solution of the 3D Poisson‐Nernst‐Planck model is proposed. The algorithmic improvements are universal and independent of the detailed physical model. They include three major steps: an adjustable gradient‐based step value, an adjustable relaxation coefficient, and an optimized segmentation of the modeled space. The enhanced algorithm significantly accelerates the speed of computation and reduces the computational demands. The theoretical model was tested on a regular artificial channel and validated on a real protein channel—α‐hemolysin, proving its efficiency.

Touching ghosts: observing free fall from an infalling frame of reference into a Schwarzschild black hole

The problem of communication between observers in the vicinity of a black hole in a Schwarzschild metric is considered. The classic example of an infalling observer Alice and a static distant mother station (MS) is extended to include a second infalling observer Bob, who follows Alice in falling towards the event horizon. Kruskal coordinates are introduced to analyse this situation, and the pedagogic value of introducing this alternative coordinate system is demonstrated by their ability to provide a graphically based solution to and illustration of this problem. The counterintuitive result that is obtained, which will be of interest to those studying general relativity at an introductory level at final year undergraduate or at graduate level, is that Bob appears to reach a ghostly image of Alice at the event horizon.

The importance of parameter choice in modelling dynamics of the eye lens

The lens provides refractive power to the eye and is capable of altering ocular focus in response to visual demand. This capacity diminishes with age. Current biomedical technologies, which seek to design an implant lens capable of replicating the function of the biological lens, are unable as yet to provide such an implant with the requisite optical quality or ability to change the focussing power of the eye. This is because the mechanism of altering focus, termed accommodation, is not fully understood and seemingly conflicting theories require experimental support which is difficult to obtain from the living eye. This investigation presents finite element models of the eye lens based on data from human lenses aged 16 and 35 years that consider the influence of various modelling parameters, including material properties, a wide range of angles of force application and capsular thickness. Results from axisymmetric models show that the anterior and posterior zonules may have a greater impact on shape change than the equatorial zonule and that choice of capsular thickness values can influence the results from modelled simulations.

Drive system alignment calibration of a microgravity drop tower of novel design

We report here the calibration of the drive system of a new scientific facility for production of microgravity, operating on a novel design of electromagnetically driven platform. The construction achieves the design specification of alignment of the guide rails to better than 0.254mm across the entire guide rail height of 8m, despite a small lean to the right (within tolerance) and it was noted that this alignment is improved by the presence of the trolley that carries the platform.