Fig. 2From: Ultra-short term HRV features as surrogates of short term HRV: a case study on mental stress detection in real lifeSegmentation process. The ultra-short HRV features were extracted from the central position of the 5 min NN excerpts (left-hand side). This procedure was repeated for the shortest significant length of NN excerpts. The shortest excerpts were extracted from different positions, without overlapping (right-hand side)Back to article page