Alexei Navalny, the most prominent figure in the Russian opposition, turns 47 this weekend in a cell of a few square meters and without contact with the outside. He is not the only political prisoner to denounce severe punishments for openly criticizing the regime.

Most of the attention goes to Navalny and other prominent figures such as Vladimir Kara-Murza, who was sentenced last month to 25 years on treason charges. But there is a growing number of less famous prisoners who are in prison under similar conditions.