Chemical reaction rates of quasi-free electrons in non-polar liquids. The equilibrium CO2 + e− CO2−☆
The forward and reverse rates of the reaction CO2 + e− CO2− were determined in tetramethylsilane, neopentane and 2,2,4-trimethylpentane as a function of temperature. The forward reaction is exothermic in solution but the equilibrium constant shifts over four orders of magnitude with changes in solvent. The change in entropy for the forward reaction is approximately the same (−44 cal/mol degree) in the three solvents.
Let a neuronal population be composed of an excitatory group interconnected to an inhibitory group. In the Wilson-Cowan model, the activity of each group of neurons is described by a first-order nonlinear differential equation. The source of the nonlinearity is the interaction between these two groups, which is represented by a sigmoidal function. Such a nonlinearity makes difficult theoretical works. Here, we analytically investigate the dynamics of a pair of coupled populations described by the Wilson-Cowan model by using a linear approximation. The analytical results are compared to numerical simulations, which show that the trajectories of this fourth-order dynamical system can converge to an equilibrium point, a limit cycle, a two-dimensional torus, or a chaotic attractor. The relevance of this study is discussed from a biological perspective.