The effect of superimposed ac and dc electric fields on the formation of electroconvection and flexoelectric patterns in nematic liquid crystals was studied. For selected ac frequencies, an extended standard model of the electrohydrodynamic instabilities was used to characterize the onset of pattern formation in the two-dimensional parameter space of the magnitudes of the ac and dc electric field components. Numerical as well as approximate analytical calculations demonstrate that depending on the type of patterns and on the ac frequency, the combined action of ac and dc fields may either enhance or suppress the formation of patterns. The theoretical predictions are qualitatively confirmed by experiments in most cases. Some discrepancies, however, seem to indicate the need to extend the theoretical description.

Abstract. The critical assessment of the legacy of socialist jurisprudence is amongst one of the most difficult tasks of the post-transitory Central-European legal thinking. This study provides a critical reading of the findings of Hungarian socialist legal sociology with respect to the description and analysis of the socialist legal culture. The discussion starts with the first comprehensive empirical survey on the legal knowledge of the population, designed and carried out by Kálmán Kulcsár in 1965 and ends with András Sajó's synthesis on the nature of the Hungarian socialist legal culture elaborated in his monograph entitled Illusion and Reality in Law, published in 1986. The paper's main conclusion is that this two decades long 'golden age' of Hungarian legal sociology offers many valid points in both methodological and substantive terms contrary to the fact that the various findings were mainly elaborated under the pressure of official Marxism-Leninism.

In contrast to the predictions of the standard theory of electroconvection (EC), our experiments showed that the action of superposed ac and dc voltages rather inhibits pattern formation than favours the emergence of instabilities; the patternless region may extend to much higher voltages than the individual ac or dc thresholds. The pattern formation induced by such asymmetrical voltage was explored in a nematic liquid crystal in a wide frequency range. The findings could be qualitatively explained for the conductive EC, but represent a challenging problem for the dielectric EC.