A.N. Kudinov - Dr. Sc. (Phys.-Math.), Professor, Tver State University. E-mail: mathlab@yandex.ru D.Y. Lebedev - Post-graduate Student, Tver State University. E-mail: dangerr27@mail.ru V.N. Ryzikov - Ph. D. (Phys.-Math.), Associate Professor, Tver State University. E-mail: vlr@yandex.ru V.P. Tsvetkov - Dr. Sc. (Phys.-Math.), Professor, Tver State University. E-mail: tsvet@tversu.ru I.V. Tsvetkov - Dr. Sc. (Eng.), Professor, Tver State University. E-mail: tsvet@tversu.ru A.P. Ivanov - Dr. Sc. (Med.), Professor, Research advisor of Tver Cardiologic Dispensary. E-mail: ivanovcardio2010@yandex.ru