The role of physics in radioecology and radiotoxicology.

This article gives an overview of physical concepts important for radioecology and radiotoxicology to help bridge a gap between non-physicists in these scientific disciplines and the intricate language of physics. Relying on description and only as much mathematics as necessary, we discuss concepts ranging from fundamental natural forces to applications of physical modelling in phenomenological studies. We first explain why some atomic nuclei are unstable and therefore transmute. Then we address interactions of ionising radiation with matter, which is the foundation of both radioecology and radiotoxicology. We continue with relevant naturally occurring and anthropogenic radionuclides and their properties, abundance in the environment, and toxicity for the humans and biota. Every radioecological or radiotoxicological assessment should take into account combined effects of the biological and physical half-lives of a radionuclide. We also outline the basic principles of physical modelling commonly used to study health effects of exposure to ionising radiation, as it is applicable to every source of radiation but what changes are statistical weighting factors, which depend on the type of radiation and exposed tissue. Typical exposure doses for stochastic and deterministic health effects are discussed, as well as controversies related to the linear no-threshold hypothesis at very low doses.

Classification scheme for phenomenological universalities in growth problems in physics and other sciences.

A classification in universality classes of broad categories of phenomenologies, belonging to physics and other disciplines, may be very useful for a cross fertilization among them and for the purpose of pattern recognition and interpretation of experimental data. We present here a simple scheme for the classification of nonlinear growth problems. The success of the scheme in predicting and characterizing the well known Gompertz, West, and logistic models, suggests to us the study of a hitherto unexplored class of nonlinear growth problems.