Surveillance colonoscopy in low-risk postpolypectomy patients: Is it necessary?

Aim: Patients who have had colorectal adenomas removed are at increased risk of developing colorectal cancer in the future. We sought to determine whether surveillance colonoscopy at 5 years in low-risk postpolypectomy patients is necessary and effective.

Method: UK multicentre retrospective study.

Diffraction-based femtosecond pulse shaping with a two-dimensional spatial light modulator.

A new diffraction-based method is proposed and demonstrated for simultaneous shaping of both the phase and amplitude of femtosecond laser pulses by use of a phase-only two-dimensional spatial light modulator. The method suppresses certain types of temporal replica features ordinarily observed in femtosecond pulse shaping owing to imperfections in modulator devices and allows for multiplexed outputs suitable for use in various applications.

Degenerate four-wave mixing spectroscopy based on two-dimensional femtosecond pulse shaping.

We report noncollinear, degenerate four-wave mixing experiments that employ a new device based on two-dimensional femtosecond pulse shaping that delays and modulates all incident fields. Heterodyne detection is easily implemented due to the full phase stability of the device.