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Psychological- medical- and pedagogical commissions (PMPC) are most often established at educational institutions. However, children cannot be thoroughly examined in educational settings in certain cases; therefore, the physicians fail to diagnose mental deficiency in children due to insufficiently careful examinations. Correspondingly, PMDCs, when established at patient-care and preventive facilities, ensure a more accurate diagnosis and determination of an intellectual-deficiency degree in children or teenager; they also provide for elaborating a set of psychological- medical- and pedagogical measures. The experience of establishing PMPC at a regional patient-care and preventive facility, as well as of its cooperation with educational institutions and with social assistance organizations and its functional peculiarities within the structure of the patient-care facility are analyzed in the paper. Recommendations are defined on cooperation between psychiatrists, psychologists, social activists, pedagogues and of other experts working for such commissions.

Significant genetic variation in resistance to cold was detected in samples collected from a natural Drosophila population in spring, summer, and autumn. In the summer sample, phenotypic variation was determined by genetic factors; in the summer and autumn samples, exclusively by environmental factors. Flies collected in spring had the highest longevity at low temperatures. In summer, their longevity at low temperatures was drastically reduced but it was shown to increase in autumn. Cold-resistant flies had high fertility in spring and low fertility in autumn. The seasonal differences in resistance to cold were genetically determined and are probably caused by natural selection.

In spring and summer, the natural population of Drosophila studied exhibited a high level of phenotypic and genotypic heterogeneity with regard to change of individual fertility with an increase of density of adult flies. From spring to autumn, the level of genotypic variation decreased. In autumn, all phenotypic variation resulted from environmental factors. In spring, individuals sensitive to overcrowding, adapted to low density, and highly fertile in low-density conditions prevailed in the population. In summer and autumn, the population was mostly composed of individuals with opposite characteristics. On the basis of the obtained results, a conclusion on operation of cyclic density-dependent selection in the population examined was made. Selection's functional role in control of seasonal population size dynamics is discussed.