The spontaneous formation of lipid vesicles (liposomes) in aqueous lecithin/bile salt mixtures is studied using time-resolved static and dynamic light scattering. These measurements reveal a strong dependence of the kinetic rates and end-state liposome properties on total amphiphile concentration and, even more pronounced, on ionic strength. The observed trends contradict equilibrium calculations, but are in quantitative agreement with a kinetic model that we present. This model identifies the key kinetic steps during vesicle formation: rapid formation of disc-like intermediate micelles, growth of these micelles and closure to form vesicles. This work offers conclusive evidence for kinetic rather than thermodynamic control of the end-state properties.

We present some analytic results for the steady states of the Penna model of senescence, generalised to allow genetically identical individuals to die at different ages via an arbitrary survival function. Modelling this with a Fermi function (of modest width) we obtain a clear mortality plateau late in life: something that has so far eluded explanation within such mutation accumulation models. This suggests that factors causing variable mortality within genetically identical subpopulations, which include environmental effects, may be essential to understanding the mortality plateau seen in many real species.

We consider a lattice gas with quenched impurities or "quenched-annealed binary mixture" on the Bethe lattice. The quenched part represents a porous matrix in which the (annealed) lattice gas resides. This model features the three main factors of fluids in random porous media: wetting, randomness, and confinement. The recursive character of the Bethe lattice enables an exact treatment, whose key ingredient is an integral equation yielding the one-particle effective field distribution. Our analysis shows that this distribution consists of two essentially different parts. The first one is a continuous spectrum and corresponds to the macroscopic volume accessible to the fluid, the second is discrete and comes from finite closed cavities in the porous medium. Those closed cavities are in equilibrium with the bulk fluid within the grand canonical ensemble we use, but are inaccessible in real experimental situations. Fortunately, we are able to isolate their contributions. Separation of the discrete spectrum facilitates also the numerical solution of the main equation. The numerical calculations show that the continuous spectrum becomes more and more rough as the temperature decreases, and this limits the accuracy of the solution at low temperatures.

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We build upon our previous analytical results for the Penna model of senescence to include positive mutations. We investigate whether a small but non-zero positive mutation rate gives qualitatively different results to the traditional Penna model in which no positive mutations are considered. We find that the high-lifespan tail of the distribution is radically changed in structure, but that there is not much effect on the bulk of the population. The mortality plateau that we found previously for a stochastic generalization of the Penna model is stable to a small positive mutation rate.