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We present the results of a longitudinal study of the formation of graphomotor skills in elementary school children between the ages of seven and nine (students in the first and second grades). Patterns in how the skills under investigation develop in normal children and those with learning disabilities were revealed using a computerized survey of sequential movement organization and writing functions in combination with a general neuropsychological study. It is shown that graphomotor skills develop unevenly between the first and second grades in children, successful and unsuccessful in academic achievement: second-graders perform assignments faster and with fewer regulatory errors, but the spatial characteristics of their writing become worse. It was also found that children with learning disabilities lag behind in their development and automation of graphomotor and writing skills. This problem may be associated with this group's identified lack of programming and control functions as well as movement sequential organization skills. In addition, a comparative analysis of connections between age, social factors (grade level) and the formation of the functions under investigation was conducted. This analysis has shown that grade level has a greater influence on this process than was previously thought. [This article was translated by Kenneth Cargill.]

In the past two decades, active seismology studies in Russia have made use of powerful (40- and 100-ton) low-frequency vibrators. These sources create a force amplitude of up to 100 tons and function in the 1.5-3, 3-6, and 5-10 Hz frequency bands. The mobile versions of the vibrator have a force amplitude of 40 tons and a 6-12 Hz frequency band. Recording distances for the 100-ton vibrator are as large as 350 km, enabling the refracted waves to penetrate down to 50 km depths. Vibrator operation sessions are highly repeatable, having distinct "summer" or "winter" spectral patterns. A long profile of seismic records allows estimation of fault zone depths using changes in recorded spectra. Other applications include deep seismic profiling, seismic hazard mapping, structural testing, stress-induced anisotropy studies, seismic station calibration, and large-structure integrity testing. The theoretical description of the low-frequency vibrator is given in the appendices, which contain numerical examples. [ABSTRACT FROM AUTHOR]