Large-scale study of the precision of the approximate number system: Differences between formats, heterogeneity and congruency effects.

The study used a large sample of elementary schoolchildren in Russia (N = 3,448, 51.6% were girls, with a mean age of 8.70 years, ranging 6-11 years) to investigate the congruency, format and heterogeneity effects in a nonsymbolic comparison test and between-individual differences in these effects with generalized linear mixed effects models (GLMMs). The participants were asked to compare two arrays of figures of different colours in spatially separated or spatially intermixed formats. In addition, the figures could be similar or different for the two arrays. The results revealed that congruency (difference between congruent and incongruent items), format (difference between mixed and separated formats) and heterogeneity (difference between homogeneous and heterogeneous conditions) interacted. The heterogeneity effect was higher in the separated format, while the format effect was higher for the homogeneous condition. The separated format produced a greater congruency effect than the mixed format. In addition, the congruency effect was lower in the heterogeneous condition than in the homogeneous condition. Analysis of between-individual differences revealed that there was significant between-individual variance in the format and congruency effects. Analysis of between-grade differences revealed that accuracy improved from grade 1 to grade 4 only for congruent trials in separated formats. Consequently, the congruency effect increased in separated/homogeneous and separated/heterogeneous conditions. In general, the study demonstrated that the test format and heterogeneity affected accuracy and that this effect varied for congruent and incongruent items.

[Morphometric characteristic of twin fetuses during the stages of the intrauterine development according to the ultrasonographic data].

The purpose of this study was to detect the anatomical regularities in the development of twin fetuses on the basis of supravital ultrasound investigations. On the material of ultrasonographic studies of twin fetuses in multiple pregnancy in 328 women of Orenburg and Orenburg region, the successive increase of the ultrasound fetometric parameters was demonstrated with the gradual decline of their increment, which was most expressed in the last month of pregnancy. Fetometric parameters were lower in monochorial twins and in peripheral (and especially marginal) attachment of the umbilical cord to the placenta. Dissociated development of twin fetuses was more expressed in the premature multiple pregnancy.

[The prospects of application of methods of population immune status evaluation when performing mass hygienic studies].

Non-invasive methods of sampling and a range of immunological assays for mass ecologo-hygienic studies of population were developed and introduced into practice in Sysin Scientific Research Institute of Human Ecology and Environmental Hygiene of Russian Academy of Medical Sciences. The studied materials were saliva, urine, breast milk, the condition of lymph nodes, and anamnesis. The complex of non-invasive methods was shown to be less complicated and, at the same time, informative and cheap, which allows recommending it for sociohygienic monitoring when performing mass hygienic studies.