Length and position dependence of the best-fit fibril fragmentation model. (a) Schematic illustration of a fibril fragmentation reaction. (b) The fragmentation rate matrix kFrag represented as a contour diagram, showing the first order fragmentation rate constants as a function of fibril length i, and position of breakage j, expressed as the number of monomers or nanometers in the brackets. (c) The fibril fragmentation rate constant as a function of fibril length for the best-fit fragmentation model. (d) Example of fragmentation rate constant as a function of breakage position for a fibril of 2000 nm in length for the best-fit fragmentation model. In (c) and (d), the shaded area indicates 95% confidence functional prediction bounds. The dotted red line in (c) and (d) shows the results obtained using the Hill model (37). To see this figure in color, go online.