Dynamic vaccination games and variational inequalities on time-dependent sets

This paper presents a model of a dynamic vaccination game in a population consisting of a collection of groups, each of which holds distinct perceptions of vaccinating versus non-vaccinating risks. Vaccination is regarded here as a game due to the fact that the payoff to each population group depends on the so-called perceived probability of getting infected given a certain level of the vaccine coverage in the population, a level that is generally obtained by the vaccinating decisions of other members of a population. The novelty of this model resides in the fact that it describes a repeated vaccination game (over a finite time horizon) of population groups whose sizes vary with time. In particular, the dynamic game is proven to have solutions using a parametric variational inequality approach often employed in optimization and network equilibrium problems. Moreover, the model does not make any assumptions upon the level of the vaccine coverage in the population, but rather computes this level as a final result. This model could then be used to compute possible vaccine coverage scenarios in a population, given information about its heterogeneity with respect to perceived vaccine risks. In support of the model, some theoretical results were advanced (presented in the appendix) to ensure that computation of optimal vaccination strategies can take place; this means, the theory states the existence, uniqueness and regularity (in our case piecewise continuity) of the solution curves representing the evolution of optimal vaccination strategies of each population group.     

苹果双变气调贮藏

苹果双变气调贮藏(TDCA)是在产地简易气调贮藏基础上,总结发展形成的一项新的理论与技术。与传统气调不同,TDCA贮藏初期采用较高温度(10℃或更高),高CO_2(10％以上),并在贮藏期间变动,由高到低。对比试验证明,TDCA贮藏效果优于冷藏,与气调相近。其生理机制在于显著抑制呼吸作用;抑制乙烯的生成和催熟作用,减弱叶绿素和原果胶分解;保持果实色泽和硬度,抑制虎皮病的发生。初步确定的双变模式在生产上应用获得良好效益。同时还讨论了贮藏期间温度和气体成分变动之间相互依赖的辨证关系以及环境因子变动的合理性。