Stimulus-response theory

FIGURE 3.5 Major components of classical receptor theory. Stimulus is the product of intrinsic efficacy (s), receptor number [R], and fractional occupancy as given by the Langmuir adsorption isotherm. A stimulus-response transduction function f translates this stimulus into tissue response. The curves defining receptor occupancy and response are translocated from each other by the stimulus-response function and intrinsic efficacy. 

By utilizing complete dose-response curves, the method devised by Barlow, Scott, and Stephenson [9] can be used to measure the affinity of a partial agonist. Using null procedures, the effects of stimulus-response mechanisms are neutralized and receptor-specific effects of agonists are isolated. This method, based on classical or operational receptor theory, depends on the concept of equiactive concentrations of drug. Under these circumstances, receptor stimuli can be equated since it is assumed that equal responses emanate from equal stimuli in any given system. An example of this procedure is given in Section 12.2.1. 

In terms of classical receptor theory—where response is a hyperbolic function of stimulus (Response = Stimulus/ (Stimulus 4- [3), [3 is a transducer function reflecting the efficiency of the stimulus-response mechanism of the system), and stimulus is given by Stimulus = [A] e/([A] + KA) (e is the efficacy of the agonist)— Response is given by... 

The time that a molecule spends in a reactive system will affect its probability of reacting and the measurement, interpretation, and modeling of residence time distributions are important aspects of chemical reaction engineering. Part of the inspiration for residence time theory came from the black box analysis techniques used by electrical engineers to study circuits. These are stimulus-response or input-output methods where a system is disturbed and its response to the disturbance is measured. The measured response, when properly interpreted, is used to predict the response of the system to other inputs. For residence time measurements, an inert tracer is injected at the inlet to the reactor, and the tracer concentration is measured at the outlet. The injection is carried out in a standardized way to allow easy interpretation of the results, which can then be used to make predictions. Predictions include the dynamic response of the system to arbitrary tracer inputs. More important, however, are the predictions of the steady-state yield of reactions in continuous-flow systems. All this can be done without opening the black box. 

Koetting MC, et al. Stimulus-responsive hydrogels theory, modem advances, and applications. Mater Sci Eng R Rep 2015 93 1—49. 

To increase efficiency, many companies adopted the learning theory s stimulus/response model of behavior modification, where the employees who worked the fastest and produced the most results were rewarded with raises, promotions, or other positive reinforcers [3]. This relates to our discussion on rewards and doing a job faster to keep being rewarded. 

This is another important point at the x-axis of the reaction time distribution. Its meaning can only be understood on a theoretical basis. The hypothetical neural representation suggests that there are two parts of the pathway within the cortex a linear part and a cyclical part. According to this theory, the point (Fp-2ET) divides these two parts in the minimal stimulus-response pathway. It has to be shown that this division by (Fp-2ET) is valid in all pathways. 

In this case, the slope of the initial step is important as this contains the high-frequency information. Any phase differences observed between stimulus and response and not caused by the DSC instrument itself will invalidate the simple reversing/non-reversing methods, but are coped with in linear-response theory. 

The increasing interest in polymer blends has acted as a stimulus not only to the aspects just outlined but also to a study of interactions between polymer A and polymer B in solution as a route to quantifying their thermodynamic compatibility. Hyde167 has reviewed the relevant theory whilst Kratochvfl and co-workers168,169 have been responsible for much of the latest experimental studies. 

These considerations have to be applied to phenomena in which the external field has its origin in the solute (or, better, in the response of the solute to some stimulus). The characteristics of this field (behaviour in time, shape, intensity) strongly depend on the nature of the stimulus and on the properties of the solute. The analysis we have reported of the behaviour of the solvent under the action of a sinusoidal field can here be applied to the Fourier development of the field under examination. It may happen that the Fourier decomposition will reveal a range of frequencies at which experimental determinations are not available to have a detailed description of the phenomena an extension of the s(w) spectrum via simulations should be made. It may also happen that the approximation of a linear response fails in such cases the theory has to be revisited. It is a problem similar to the one we considered in Section 1.1.2 for the description of static nonlinear solvation of highly charged solutes. 

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