Matemática Física

In this article it is tried to construct a stochastic model which looks a generalized stochastic version of Von Bertalanffy power law model and Richard’s model and one can use to describe biological growth phenomena according to the appropriate situation and suitability of this model. It is mainly constructed to explain growth dynamics of patients infected by COVID-19 in South Korea. Here it is attempted to find the expression of variable of interest at time t and also the MLE of growth rate parameter is worked out. This model is applied to a real life data of infected patients by COVID-19 in South Korea after observing the growth pattern. This model could be used to the data sets of other countries, where no lockdown was imposed as a precautionary measure to deal with this situation. Then a comparative study is made between some well-known models and special cases of the model, described here. It is found that the special cases of the model that is described in this article fits better to the data than others.

The cosmological constant problem is localizated in the convergence between general relativity and quantum field theory, it is considered as a fundamental problem in modern physics. In this paper we describe a different point of view of this problem. We discuss how the problem could depend to different definition of the vacuum energy density.