FociCounter: a freely available PC programme for quantitative and qualitative analysis of gamma-H2AX foci.

Gamma-H2AX foci are sensitive and specific indicator for the induction of DNA double-strand breaks (DSBs) and an immunocytochemical assay with antibodies recognizing gamma-H2AX has become the gold standard for the detection of this type of DNA lesion. Quantification of gamma-H2AX foci can be achieved by various methods such as Western blotting, flow cytometry, visual analysis and computational analysis with a fluorescence microscope. The best sensitivity is achieved by computer analysis.

Active stabilization of a rapidly chirped laser by an optoelectronic digital servo-loop control.

We propose and demonstrate a novel active stabilization scheme for wide and fast frequency chirps. The system measures the laser instantaneous frequency deviation from a perfectly linear chirp, thanks to a digital phase detection process, and provides an error signal that is used to servo-loop control the chirped laser. This way, the frequency errors affecting a laser scan over 10 GHz on the millisecond timescale are drastically reduced below 100 kHz.