The formation and growth of leaves around the stem of a plant often leads to a helical structure consisting of two counter-rotating sets of spirals. Similar arrangements (parastichies) are found for the petals, florets, stamens, etc. of many flowers. Douady and Couder [Phys. Rev. Lett. 68, 2098...

Batteries are one of the most common devices used for saving electrical energy in various applications. It is necessary to understand the battery behavior and performance during charge and discharge cycles. An accurate model of a battery with a specific application is needed for an appropriate...

In the current study, a multi-arc predicting model for DC critical flashover voltage of iced and pre-contaminated long insulator strings under low atmospheric pressure is developed. The model is composed of a series of different polarity surface arcs, icicle-icicle air gap arcs, and residual...

We analyze a mathematical model of the simultaneous transmission of two HIV subtypes and their control by vaccines. Two vaccines are analyzed which utilize different mechanisms, one in which the vaccine take differs for each subtype, and the other in which a different level of reduced...

A simple theoretical framework is presented that addresses the question of how different vaccination strategies work against a pathogen which infects two species. This is first studied in purely theoretical terms to determine which equilibria will be stable for which parameter combinations. Two...

Realistic models have a larger number of parameters than simple models do. In such realistic models some of the parameter values will be less realistic because of the availability and the difficulty in estimation. On the contrary, a simple model with a smaller number of parameters of which...