PD, measurement

Lorazepam The PK-PD modeling of the psychomotor and mnesic effects of a single 2 mg oral dose of lorazepam in healthy volunteers showed that the parameter values derived from PK/PD modeling, and especially the EC values, may provide sensitive indices that can be used, rather than the raw data derived from PD measurements, to compare CNS effects of benzodiazepines... 

The study of hydrogen and deuterium electrosorption in palladium limited volume electrodes (LVE) was carried out by the same group in both acidic and basic solutions [124,130,134]. It was found that the hydrogen capacity, H (D)/Pd, measured electrochemically, depends significantly on sweep rate in cyclic voltammetric experiments and also on the thickness of the LVE. Two different mechanisms of hydrogen desorption, that is, the electrochemical oxidation and the nonelectrochemical recombination step, which take place in parallel within the Pd—LVE, have been postulated. 

An important aspect of PD models is the link between the pharmacokinetics and the pharmacodynamic model, i.e. which concentration drives the drug effect. For empirical models there are many different PK/PD link approaches described and the theory is presented in several review papers [33-35]. The two most popular approaches are described in the following and are also illustrated in Fig. 17.7. The direct link approach assumes that a change in the measured concentration is directly reflected in a change in the measured P D. This is most often observed if the site of PK measurement and the site of PD measurement are identical (e.g. PK measurement in plasma and clotting time as PD measurement). 

Often the drug effect lags behind the measured plasma concentration-time profile ( hysteresis ), i.e. the same PD measurement corresponds to different measured plasma concentrations. In this case often a hypothetical effect compartment is introduced into the model, where a rate constant keo determines the elimination out of this effect compartment. The concentration-time profile within this effect compartment is now linked to the P D effect model. This allows the description of a time delay between the plasma concentration and the PD (see Fig. 17.7) and again a unique relation between concentration and the observed PD is established. 

Partial discharge (PD) measurements applied to components or apparatus subject to electrical stresses, e.g. components according to encapsulation - m or complying with increased safety - e - ... 

For a correct interpretation of PD measurement results it is very helpful to obtain information in addition to a pure PD intensity indicator, e.g. the phase angle (referring to the test voltage) of the PD pulses. A more conventional method is to record the test voltage superposed with the PD pulses. 

All conductors are part of three closed current loops with impressed currents which are kept constant, and a three-phase high voltage system enables simultaneous PD measurements in the three conductors (Fig. 8.9). The complete test circuit is installed in a shielded cabin as a Faraday cage, all power lines enter this cage via filter banks to suppress unwanted signal transmission to the internal test circuit. The main parts of the test circuit are ... 

The main technical data of this 3 AC PD test circuit are summarized in Table 8.4. This test facility enables continuous PD measurements for electrical 3 AC apparatus up to 11 kV and 1000 A, the voltage limitation complying with EN 50019 and IEC 60079-7, but with a margin of safety in the rating of the test voltage. As a total, a throughput power of 104 MVA can be simulated. 

To close this section, two main aspects of PD measuring technique shall be explained in more detail. The first point is to determine the maximum permissible PD intensities in an adequate way. The general aim is to ensure an appropriate quality of dielectrics in electrical apparatus and components or to predict the residual operational lifetime of such parts after a certain time on duty. There is absolutely no algorithm for this, i.e. all values for maximum permissible PD intensities are based on experience in practice. So, the values given in Table 8.5 are near to practice, but may be reduced accordingly for special applications. 

The second point is to compare the appropriateness of PD measurements with that of more conventional loss factor (tan 8) measurements. In general, tan 8 measurements show an integral over the insulating material in its entirety. Deviations from tan 8 due to an insulation impairment restricted to a small (local) area cannot be detected to have been caused by the limited... 

The optical absorption arising from the defect transitions is weak because of the low defect densities and in a thin film cannot be measured by optical transmission. The techniques of PDS, CPM and photoemission yield, described in Section 3.3, have sufficient sensitivity. Photocapacitance, which measures the light-induced change in the depletion layer capacitance, is similarly sensitive to weak absorption (Johnson and Biegelsen 1985). PDS measures the heat absorbed in the sample and detects all of the possible optical transitions. At room temperature virtually all the recombination is non-radiative and generates heat by phonon emission. CPM detects photocarriers and so is primarily sensitive to the optical transitions which excite electrons to... 

Fig. 4.21. PDS measurements of the optical absorption edge and defect transitions of a-Si H samples deposited at different rf power, as indicated (Jackson and Amer 1982).

The catalytic reactivity in the range of 1 to 3 ML Pd on Au(llO) is surprisingly low taking into account the noticeable amount of Pd measured by LEIS on the surface (Fig. 17). This low reactivity could be due either to a low number of active sites (two adjacent Pd atoms) resulting from chemical order or to the tensile stress applied to Pd atoms in pseudomorphic epitaxy with Au substrate. Such a hypothesis would be in agreement with the theoretical predictions of Pallassama and Naurock [21] who propose that Pd stressed in... 

Garnero P, Dehnas PD. Measurements of biochemical markers methods and limitations. In Bhezikian JP, Raisz LG, Rodan GA, eds. Principles of bone biology. San Diego Academic Press, 1996 1277-91. 

Pastoureau P, Delmas PD. Measurement of serum bone Gla-protein (BGP) in humans with an ovine BGP-based radioimmunoassay. Clin Chem 1990 36 1620-4. 

Figure 13.1 Reciprocal space (2D) representation of the diffraction condition Ewald sphere (radius 1/2), limiting sphere (radius 2/2) and PD sphere (double line, radius d ). Left Enlargement of the intersection between PD sphere and reciprocal space point, with approximating tangent plane (dash). The arrow shows the direction of expansion of the diffraction sphere during a PD measurement.

Zhong, L. Chen, G. Xu, Y. A novel calibration method for PD measurements in power cables and joints using capacitive couplers. Meas. Sci. Technol. 2004, 15, 1892-1896. 

Far fewer PK/PD analyses and reports deal with PD measures that are discrete in nature. Variables that represent discrete measures have properties that are distinct from continuous variables. A variable is discrete if the number of values that it can assume is finite or countably infinite. Count data is generally considered a type of discrete variable. 

The blood or plasma concentrations of the parent drug and/or its active metabolites (systemic exposure) may provide an important link between drug dose (exposure) and desirable and/or undesirable drug effects (8). For this reason, the modeling of parent drug and metabolite pharmacokinetics, coupled with pharmacodynamic (PD) measurements, offers an essential development tool for prediction and simulation. 

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