Cumulative response

Dicamba (3,6-dichloro-2-methoxybenzoic acid) is primarily used as a postemergence broadleaf herbicide, which interferes with normal plant auxin function, subsequently causing uncontrolled growth and the inhibition of the phototropic and geotropic function. Cumulative response results in plant death. The success of auxinic analogues such as Dicamba and 2,4-dichloropheno-xyacetic acid in weed control has led to widespread manufacturing and use. Estimated U.S. production for Dicamba was 5 million kg in 1990 [391]. 

Figure 3. Cumulative response of RBC AChE based on repetitive OF exposure sufficient to cause the dally responses Indicated followed by 10% reversion and 1% RBC replacement/day.

Thus for example, 5 consecutive daily doses each Inhibiting 10% of the existing enzymes might produce a 40% cumulative response, sufficient to require administrative removal of the worker from further exposure ( ). In point of fact, several biochemical and physiologic processes require considerable modification of Equation 9 to accurately predict cumulative responses especially for dally Inhibitions less than 10%. These processes and their Implications were discussed In the 1982 review and Include ... 

Each of these will have a somewhat moderating effect on cumulative responses, contributing to the reestablishment of a biochemical equilibrium In cholinesterase activity within the blood at a... 

The procedure is used for the simulation of the cumulative response of the shoreline to the sequence of storms after R = 50 years. The experiment is repeated... 

FIGURE 1-2. When dose versus response is plotted as the log of die dose given va-sus the percent cumulative response, the graph b a straight line. The probit scale is a weighted number assigned to the percent cumulative response in order to simplify calculations by using whole numbers that correspond to one or more standard deviations from the LD ... 

These models are polynomials of the second order, i.e., they contain squared terms and binary interactions. In principle one could think of third- and higher-order polynomials, but this is rarely necessary. Ternary interactions are rarely relevant and third-order models or nonlinear models (in the statistical sense of the term nonlinear) do not often occur. Nature can in practice often be approximated, at least locally, by smooth functions such as second-order equations. Exceptions exist for example, pH often leads to sigmoid curves when the measured response is due to the cumulated response of the ionized and nonionized species of the same substance. This curve would be difficult to model over the whole experimental domain with a second-order equation. Quite often, one will not be interested in the whole domain but in a more restricted region. In that case it may be feasible to model the response using a quadratic function of the independent variable. 

Fig. 6. Cumulative log concentration-response curves for the homologous-A/-aLkylcatecholamines,...

It is important to appreciate that the magnitude of the absorbed dose, the relative amounts of bio transformation product, and the distribution and elimination of metaboUtes and parent compound seen with a single exposure, may be modified by repeated exposures. For example, repeated exposure may enhance mechanisms responsible for biotransformation of the absorbed material, and thus modify the relative proportions of the metaboUtes and parent molecule, and thus the retention pattern of these materials. Clearly, this could influence the likelihood for target organ toxicity. Additionally, and particularly when there is a slow excretion rate, repeated exposures may increase the possibiUty for progressive loading of tissues and body fluids, and hence the potential for cumulative toxicity. 

FIGURE 5.4 Microphysiometry responses of HEK 293 cells transfected with human calcitonin receptor, (a) Use of microphysiometry to detect receptor expression. Before transfection with human calcitonin receptor cDNA, HEK cells do not respond to human calcitonin. After transfection, calcitonin produces a metabolic response, thereby indicating successful membrane expression of receptors, (b) Cumulative concentration-response curve to human calcitonin shown in real time. Calcitonin added at the arrows in concentrations of 0.01, 0.1, 1.10, and lOOnM. Dose-response curve for the effects seen in panel B. 

In this section we consider how to express the response of a system to noise employing a method of cumulant expansions [38], The averaging of the dynamical equation (2.19) performed by this technique is a rigorous continuation of the iteration procedure (2.20)-(2.22). It enables one to get the higher order corrections to what was found with the simplest perturbation theory. Following Zatsepin [108], let us expound the above technique for a density of the conditional probability which is the average... 

Positive Step Changes and the Cumulative Distribution. Residence time distributions can also be measured by applying a positive step change to the inlet of the reactor Cm = Cout = 0 for r<0 and C = Co for r>0. Then the outlet response, F i) = CouMICq, gives the cumulative distribution function. ... 

Figure 2. Effect of maitotoxin (MTX) on the log concentration—contractile response curve for Ca in the presence or absence of verapamil or MgCl2 in the rabbit aorta. Control (A), 10" g/mL MTX (o), 10" M verapamil plus 10 g/mL MTX ( ), and 10 mM MgCl2 plus 10" g/mL MTX ( ). The aorta was incubated in a Ca -free solution for 1 hr before the cumulative application of CaCL. Verapamil or MgCl2 and MTX were added 45 and 30 min before the application of CaCL, respectively. The maximum response to norepinephrine (3 x 10" M) is expressed as 100%. Vertical lines indicate the standard error of mean (n=7). (Reproduced with permission from Ref. 13. Copyright 1983 Press Syndicate of the University of Cambridge)...

Figure 3.51. CO chemisorption by pulse response of a reduced 5 wt% Pt/Al203 a. Thermal Conductivity Detector (TCD) signals after the CO pulses, b. Cumulative amount of CO chemisorbed. The monolayer capacity is 0.06 mmol/g Pt, corresponding with a dispersion of 24%.

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