The parameters of nitrate uptake by nitrogen-limited and nonlimited cells of Phaeodac-tylum tricornutum change extensively during nitrate starvation. The saturated uptake rate, affinity constant, and nitrogen cell content decrease by half to three-fourths in 3 days, while the cells remain metabolically active. Under continuous light, the absolute uptake rate goes through a maximum after 3-5 h of starvation, then decreases significantly. Upon re-exposure to nitrate, nonlinear uptake is observed if the cells have been deprived of nitrate for more than 24 h. After a lag time which is related to the duration of the previous starvation phase, a shift-up in saturated uptake rate occurs, leading to ‘recovery of the initial rate within hours. The direction of change in the specific uptake rate depends on the physiological state of the cells before the starvation phase. The relationship between specific uptake rate and nitrogen cell content of nitrogen-starved cultures, although in contrast to that found with nitrogen-limited cultures, has the advantage of better describing results from field studies: low uptake rates and affinity constants in oligotrophic waters and high values in eutrophic waters. These findings have implications within the context of the theory of nutrient limitation and, more

Transient situations in nitrate assimilation by marine diatoms. 2.

informs ® doi 10.1287/orsc.1050.0133 © 2005 INFORMS Sensemaking involves turning circumstances into a situation that is comprehended explicitly in words and that serves as a springboard into action. In this paper we take the position that the concept of sensemaking fills important gaps

Transient situations in nitrate assimilation by marine diatoms. 4. Non-linear phenomena and the estimation of the maximum uptake rate

interaction

scale tundish with steel was conducted. Experiments and simulations were done in steady state and in transient casting conditions. Different turbulence models and other important model variables were studied. 1.

of transient situations has been considered. In the present report, we discuss the effect of novel initial conditions on the transient fluorescence problem. We point out that a particular phase-controll-ed excitation scheme leads to a transient fluorescence spectrum in which one of the Rabi sidebands normally

Much contemporary social psychological theory appears to be theory of group behavior qua group. While group oriented conc"pts may be transiently useful in classifying and systematizing the'vast experimental literature of social psychology, we hold that ultima{ely group behavior can

There is growing interest in understanding and eliciting division of labor within groups of scientists. This paper illustrates the need for this division of labor through a historical example, and a formal model is presented to better analyze situations of this type. Analysis of this model reveals

. Introduction The coronal magnetic field, according to generally accepted views, serves two roles during a transient event such as a flare or a coronal mass ejection. The field physically contains the energy, and it also imposes geometrical structure (before and after an event) because of the frozen