RESUMO
We present a method for using liquid-crystal variable retarders (LCVR's) with continually varying voltage to measure the Stokes vector of a light beam. The LCVR's are usually employed with fixed retardance values due to the nonlinear voltage-retardance behavior that they show. The nonlinear voltage-retardance relationship is first measured and then a linear fit of the known retardance terms to the detected signal is performed. We use known waveplates (half-wave and quarter-wave) as devices to provide controlled polarization states to the Stokes polarimeter and we use the measured Stokes parameters as functions of the orientation of the axes of the waveplates as an indication of the quality of the polarimeter. Results are compared to a Fourier analysis method that does not take into account the nonlinear voltage-retardance relationship and also to a Fourier analysis method that uses experimental voltage values to give a linear retardance function with time. Also, we present results of simulations for comparison.
RESUMO
We presented two cases of falsely elevated CK-MB due to the presence of a type 2 macro CK, showed by isoenzymes electrophoresis. The association of this CK-MB falsely elevated with some digestive diseases are frequent. Quantification of CK isoenzymes by electrophoresis could be indicated in those cases in which the clinical course or ECG changes do not correlate with the CK-MB values.