英语翻译In the present paper we study a diffusing particle that

英语翻译
In the present paper we study a diffusing particle that escapes from a cavity to the outside world through a narrow cylindrical tunnel.While earlier studies of the problem1–3 are focused on the mean particle lifetime,which is only the rst moment of the distribution,we develop a theory that allows us to derive expressions for the Laplace transforms of the particle lifetime probability density and its survival probability.The former is used to obtain an expression for the mean lifetime that contains the results earlier reported in the literature as special cases,which correspond to different escape scenarios.This is a consequence of the fact that our approach is quite general in the sense that it does not assume any particular scenario.The results obtained in the paper show how the escape kinetics depends on the geometric and trans-port parameters of the system,namely,the cavity volume,the length and radius of the tunnel,and the particle diffusion coef?cients in the tunnel and cavity,which may be different.
The model of a diffusing particle escaping from a cavity through a narrow tunnel has been proposed and used when discussing escape of signaling ions and proteins from den-dritic spines,1–4which are small,micrometer in size protrusions on dendrites.Although there is enormous variability in spine morphology,5the classical dendritic spine consists of a bulbous head connected to the parent dendrite by a narrow neck.It is believed that dendritic spines are important for communication between nerve cells,since the majority of excitatory synapses in the brain are on spines rather than dendrites.Cells use spines as sites where suf?ciently high concentrations of signals can be generated and kept long enough to initiate signaling cascades.1–4 Therefore,the signal lifetime in the spine is an important parameter.

本文研究了一种扩散的粒子逃离了腔向外部世界通过一条狭窄的圆柱隧道.而早期的研究集中在problem1-3的平均粒子一生,这是唯一的那一时刻?具时滞参数之竞争,我们建立了一个理论分布表达式,允许我们为拉氏变换导出的概率密度及其粒子一生生存概率.前者是用来获取一个表达式的意思是一生中包含的飞机票