Nutrient supply rate

In some cases, resins have been used to try to determine only the plant or more generally the biological availability of an ionic species. Resins placed in soil have also been used to study ion speciation, soil microbiology, various phosphorus measurements, soil nutrient supply rate, nutrient transformations and movement, and micronutrient and metal toxicity [22-25],... 

Climate-induced changes in nutrient supply rates are a consequence of alterations in the hydrohgical cycle ard in meridional... 

In tropical waters, vertical stratification persists throughout the year and production is permanently limited by nutrient supply rates, which are controlled by internal recycling and slow upward diffusion from deep water. Under these conditions, productivity is low throughout the year. 

Because productivity in most arctic ecosystems is constrained by low nutrient availability, the most common responses to nutrient addition are increases in nutrient uptake and plant nutrient mass followed by increased plant production and biomass. Similar effects on growth can be expected in response to warming through direct responses of increased productivity in a wanner environment and through enhanced nutrient uptake as a result of increased nutrient supply rate, as mineralization is likely to increase in the warmed soils (Nadelhoffer et al, 1992). 

M. C. Drew, L. R. Saker, Nutrient supply and the growth of the seminal root system in barley II. Localized compensatory changes in lateral root growth and the rates of nitrate uptake when nitrate is restricted to only one part of the root system. J. E.xp. Bot. 26 79 (1976). 

Permeability The rate of microbial ability to metabolize hydrocarbons is limited primarily by the availability of electron acceptors and nutrient supply. In... 

Nutrients are carried back to the sea surface by the return flow of deep-water circulation. The degree of horizontal segregation exhibited by a biolimiting element is thus determined by the rates of water motion to and from the deep sea, the flux of biogenic particles, and the element s recycling efficiency (/and from the Broecker Box model). If a steady state exists, the deep-water concentration gradient must be the result of a balance between the rates of nutrient supply and removal via the physical return of water to the sea surface. 

In upwelling areas, the resupply of DSi via Ekman transport leads to a silica trapping effect as illustrated in Figure 16.4. Under these conditions, growth rates in the surface waters are controlled by the supply rate of DSi via upwelling. An example of nutrient... 

The rate of growth of human and experimental cancers is initially quite rapid (exponential) and then slows until a plateau is reached. The decrease in growth rate with increasing tumor size is related both to a decrease in the proportion of cancer cells actively proliferating (termed the growth fraction) and to an increase in the rate of cell loss due to hypoxic necrosis, poor nutrient supply, immunological defense mechanisms, and other processes. 

Animal cells add a significant layer of complexity to the system due to their dependence on cell-matrix and cell-cell signaling pathways. Unicellular species such as bacteria and yeasts tend to grow and proliferate as fast as nutrients can be supplied. In fact, their growth rates are typically proportional to the amounts of nutrients available. By contrast, however, cells from multicellular organisms must develop mechanisms that include both nutrient supplies and signal pathways that control cell division. Thus, while nutrients are necessary for an animal cell to proliferate, the cell must receive stimulatory chemical signals from other, usually adjacent, cells. 

The formula for BCD in Eq. (2) was derived under the assumption that the bacterial growth rate was mineral nutrient limited. If the supply rate of labile organic carbon from allochthonous and autochthonous sources is insufficient to meet this demand, the pool of labile dissolved organic carbon (DOC) will eventually be depleted and the bacteria will become carbon... 

Interest in dietary components which explain differences in breast cancer rates comes from strong correlations between nutrient supply within nations and their age-adjusted rates for breast cancer (11). The most frequently cited dietary components related to higher risk of breast cancer are total fat, total protein, calories, animal fat, animal protein, and a lack of fiber. Overall it has not been possible to identify the specific dietary constituents responsible for the observed incidence since the intakes of many dietary factors such as protein, fat, and calories are strongly intercorrelated. Other studies of nutrient intake and breast... 

Butler (1987) has considered the physics of gaseous exchange and rate of nutrient supply and concludes that a 100 1 culture running in the continuous mode may be more efficient than a 1000 1 batch system. Different systems for large scale production have been compared by van Wezel (1985)who concludes that continuous perfusion systems are the most efficient for production of cellular components. 

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