“…Equation (1.1) is often referred to as a nonparametric model (a model with all the unknown parameters being in an infinite-dimensional parameter space) in the statistics literature. Such models are motivated by a number of applications arising in biology and physics, for example, in modeling mosquitofish populations [9] and shrimp populations [6], in wave propagation in biotissue [15], in modeling of a complex nonmagnetic dielectric materials [4,10], and in HIV cellular models [3]. Here we only elaborate one of the motivating examples, a recent project investigated by our group.…”