In my PhD thesis, I constructed with the help of cubical set theory, an "approximation space" to the space of positive scalar curvature metrics whose homotopy groups are precisely concordance classes of positive scalar curvature metrics. I further showed that the index difference factors through that space. To achieve this, I established a new model for the classifying space of real K-theory using invertible pseudo Dirac operators.
In my Master's Thesis I answered a question raised by Edward Witten what the fourth Pin bordism group of the classifying space