Lassi Päivärinta is a Finnish mathematician, professor at Tallinn University of Technology, Estonia, author of more than 70 scientific publications. His research mainly lies in the field of inverse problems and partial differential equations. He headed the Finnish Center of Excellence for the Study of Inverse Problems, was the director of the Rolf Nevanlinna Institute. Professor Pyavyarinta is the editor–in-chief of the journal Inverse Problems and Images. In 2006, he was awarded the Magnus Ernroth Foundation Prize in Mathematics from the Finnish Society of Sciences and Literature. He is a member of the Finnish Academy of Sciences, and one of the founders of the Finnish Inverse Problem Society, the world's first scientific society for inverse problems.

On September 19, at the seminar of the Russian Scientific Research Center of the Southern Federal University, Professor Pyavyarinta gave a lecture on backscattering from the screen using only one incoming harmonic time plane wave, but with measurements of the scattered wave in all directions. Professor Pyavyarinta focused on the (2D) case, i.e., the case of (backscattering) from an open bounded smooth curve.

The seminar "Seminar on Analysis, Differential Equations and Mathematical Physics" was attended by more than thirty mathematicians - specialists from leading scientific and educational centers of the world in Russia and other countries, including graduate students and students of the Institute of Mathematics, Mechanics and Computer Science of the Southern Federal University and young scientists.

Online scientific seminar of the Regional Scientific and Educational Mathematical Center (https://rmc.sfedu.ru /) it is held regularly every two weeks, announcements of new seminars and videos of previous seminars are available on the website http://msrn.sfedu.ru/sl . The seminar is attended by leading researchers from around the world whose research interests are related to analysis, differential equations and mathematical physics. The scientific seminar of the mathematical center is open, and everyone can take part in it.