The placenta forms a selective barrier that functions to transport nutrients that are of critical use to the fetus. Nutrient transport across the placenta is regulated by many different active transporters found on the surface of both maternal and fetal facing membranes of the placenta. The presence of these transporters in the placenta has been implicated in the facilitation of nutrient diffus...

Figure 1. Bazzania trilobata and other bryophytes growing together. Note the dead tissue in the lower right part of the clump, where nutrient sinks can be mobilized to supply growing apical tissues. Such clumps can play a significant role in the distribution of forest nutrients. Photo by Michael Lüth. One of the most poorly understood abilities of bryophytes by "vascular" botanists is the abili...

One criterion of the effectiveness of nutritional sprays is the rate at which the foliar applied nutrients are absorbed by the leaf and translocated to other plant parts including the roots. Two distinct but not easily separated processes, absorption and transport, are involved. Initial penetration most likely involves passage through the cuticle and epidermal cells (17, 20); stomata may also p...

INTRODUCTION ..................................................................................... 97 NUTRIENT TRANSPORT BY PLACENTA .................................................... 99 Maternal Blood Flow and the Transport of Gases and Water ............................ 99 Glucose ............................................................................................. 100 Amino Acids ....

The nutrient cycles of coastal upwelling zones are studied with simple mass balance models of Ekman transport, longshore transport, surface productivity, and dissolved phosphorous. The models are constrained with data from the Peru, northwest Africa, and Oregon upwelling systems. The onshore-offshore mass balance model agrees with published Ekman transport, surface productivity, and nutrient da...

Little information is available concerning the effects of varying flow rate on nutrient transport by overland flow from areas on which manure was previously applied. The objective of this field study was to measure the effects of varying flow rate on nutrient transport following the application of varying amounts of beef cattle manure to plots containing either no-residue or a wheat residue cov...

A mathematical model for nutritional transport in capillary tissues exchange system in thepresence of magnetic field has been studied. In this case, the cell is deformed. Due to concentrationgradients, the dissolved nutrient in substrate diffuses into surrounding tissue. Theanalytical method is based on perturbation technique while the numerical simulation is basedon finite difference scheme. R...

The cybernetic framework developed by Ramkrishna and co-workers is shown to encompass the regulation of nutrient transport processes as well as the effect of nutrient transport on the biotic phase. A structured model which accounts for both an abiotic or environmental phase and a biotic or cellular phase is proposed to describe bacterial growth on lactose as the limiting carbon and energy sourc...

Animals translocate nutrients by consuming nutrients at one point and excreting them or dying at another location. Such lateral fluxes may be an important mechanism of nutrient supply in many ecosystems, but lack quantification and a systematic theoretical framework for their evaluation. This paper presents a mathematical framework for quantifying such fluxes in the context of mammalian herbivo...