Spurious currents

As a final note on this section, whichever method is used, it is also necessary to consider how the pyroelectric is mechanically mounted in the system. Any mechanical clamping (such as bonding the material to a substrate of different thermal expansion coefficient) can lead to spurious currents due to changes in the stress on the sample, coupling via one or more of the piezoelectric coefficients. 

There are a number of limitations in interface capturing schemes that continue to be addressed by researchers. One is the problem of so-called parasitic or spurious currents [6] which can be attributed to the interfacial regions being underresolved. These currents can be reduced via formulations that strictly enforce energy conservation and account for exchanges of kinetic and surface energies [11]. There are also difficulties in computations at small values of surface tension when the computed objects (drops, filaments, bubbles) become very small and cannot be... 

A capacitive circuit magnifies the harmonic effects when present in the system, as discussed in Section 23.5.2, and gives rise to spurious voltages and currents, raising the normal V, and Ji to and respectively,... 

Current available information does not permit definitive conclusions on the nature, specificity, and mechanism of action of the protein cofactor (s) of lipoprotein lipase. It is verj difiicult to correlate the observations described above (summarized in Table 10) since the enzyme preparations used were not pure or well characterized, and were derived from various sources. For instance, two species of lipoprotein lipase have been reported to exist in rat adipose tissue (G4), and major differences between enzymes of liver and adipose tissue have been noted (G16). Also, the nature of the apoprotein preparations employed as protein cofactor (s) of lipoprotein lipase has not been clearly specified in all the studies contaminated materials may account for the spurious results observed. At present, it is not known how apoproteins such as apo Glu, apo Ala, and apo Ser could exhibit their activator or inhibitor activity on lipoprotein lipase. If these different apoproteins indeed prove to be cofactors for lipoprotein lipase, the nature of the lipid-protein specificity must be established and thus the role played by carbohydrates, since some of these apoproteins are glycoproteins. 

Electrical connections for resistivity measurements usually include separate current and voltage leads and the resistance is measured by determining voltage changes with a constant current source across the sample. This technique avoids spurious voltages at the contact points of a two or three contact connection but introduces a consideration of current path separate from the voltage measurement that can lead to faulty measurements. 

Various DMEs have been developed [7] and they are useful in various experiments. Blunt-ended DMEs are, for example, not useful in experiments carried out at higher frequencies. The shielding effect mentioned earlier creates a non-uniform distribution of current along the surface of the drop, and spurious frequency dispersion effects appear. 

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