OpenCASA: A new open-source and scalable tool for sperm quality analysis
Fig 7
Verification of the ch-index in a non-chemotaxis condition.
The ch-index provides information about the percentage of the angles ψ that point in the gradient direction with respect to the total of angles taken into account. In the case of a non- chemotaxis condition, a uniform distribution of the instantaneous directionality angles is expected, so defining γ = 30° and considering the angles ψ in the range [−30°,+30°] as chemotactical responses to the gradient, theoretically the percentage of those angles with respect to the total number of angles would be . Analysing the histogram, as expected, the ch-index was centred close to the theoretical value (17.90±0.46%) with some variation due to the sampling and the noise of the system (e.g. intersection of trajectories).