A Stochastic SEIRS Epidemic Model with Infection Forces and Intervention Strategies.

The spread of epidemics has been extensively investigated using susceptible-exposed infectious-recovered-susceptible (SEIRS) models. In this work, we propose a SEIRS pandemic model with infection forces and intervention strategies. The proposed model is characterized by a stochastic differential equation (SDE) framework with arbitrary parameter settings. Based on a Markov semigroup hypothesis, we demonstrate the effect of the proliferation number R 0 S on the SDE solution. On the one hand, when R 0 S < 1, the SDE has an illness-free solution set under gentle additional conditions. This implies that the epidemic can be eliminated with a likelihood of 1. On the other hand, when R 0 S > 1, the SDE has an endemic stationary circulation under mild additional conditions. This prompts the stochastic regeneration of the epidemic. Also, we show that arbitrary fluctuations can reduce the infection outbreak. Hence, valuable procedures can be created to manage and control epidemics.

Radiation shielding for medical linear accelerator room with useful beam towards its maze / 中华放射医学与防护杂志

Objective To study the calculational method for the radiotherapy facilities of the medical linear accelerator' s useful beam towars its maze.Methods The shielding calculation was made under the relevant national standards for a radiotherapy treatment room and compared with the test results.Results The dose rates at the maze entrance as calculated and measured were 89 and 86 μSv/h inside the maze door,as well as 5.7 and 6.2 μSv/h outside the maze door,respectively.The calculated results were consistent with measured results.Conclusions By comparison of calculated results with measured results,the accuracy of the theoretical calculation method could be verified.