Characteristic times for transport processes in biological systems may be evaluated as mean transit times (MTTs) (for transit states) or mean residence times (MRT) (for steady states). It is shown in a general framework of a (linear) reaction–diffusion–convection equation that these two times are related. Analytical formulas are also derived to calculate moments of exit time distribution using ...

Quantitative knowledge of stabilizationand decomposition processes is necessary to understand, assess and predict effects of land use changes on storage and stability of soil organic carbon (soil C) in the tropics. Although it is well documented that different soil types have different soil C stocks, it is presently unknown how different soil types affect the stability of recently formed soil C...

BACKGROUND AND AIMS Leaf longevity is controlled by the light gradient in the canopy and also by the nitrogen (N) sink strength in the plant. Stand density may influence leaf dynamics through its effects on light gradient and on plant growth and reproduction. This study tests the hypothesis that the control by the light gradient is manifested more in the vegetative period, whereas the opposite ...

The concentrations of resources in forage are not perfectly balanced to the needs of an animal, and food species differ in these concentrations. Under many circumstances, animals should thus forage on multiple food species to attain the maximum and most balanced intake of several resources. In this article we present a model to extend optimal foraging theory to incorporate concurrent foraging f...

This study quantitatively describes the host-searching behavior of Fopius arisanus (Sonan) (Hymenoptera: Braconidae), an important egg-larval parasitoid of tephritid fruit fly pests, on coffee berries infested with host eggs of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). We also investigate the parasitoid’s response to local variation in host patch qualit...

We show that residence time measures can be used to identify the geometrical and transmission properties of a defect along path. The model we study is based on one-dimensional simple random walk. sites lattice are regular, i.e., jumping probabilities same in each site, except for called defect, where different. At side an absorbing site present. by measuring fraction particles crossing channel ...