Kerr effect in multilayer dielectric coatings.

We report the utilization of the optical Kerr effect in multilayer dielectric coatings, previously discussed only theoretically. We present the design and realization of multilayer dielectric optical structures with layer-specific Kerr nonlinearities, which permit tailoring of the intensity-dependent effects. The modulation depth in reflectance reaches up to 6% for the demonstrated examples of dielectric nonlinear multilayer coatings. We show that the nonlinearity is based on the optical Kerr effect, with the recovery time faster than the laser pulse envelope of 1 ps. Due to high flexibility in design, the reported dielectric nonlinear multilayer coatings have the potential to open hitherto unprecedented possibilities in nonlinear optics and ultrafast laser applications.

Highly-dispersive mirrors reach new levels of dispersion.

A highly-dispersive mirror with the unprecedented group delay dispersion of -10000 fs2 in the wavelength range of 1025-1035 nm is reported. Reproducible production of a coating with such a high dispersion was possible due to the recently developed robust synthesis technique. Successful employment of the new highly-dispersive mirror in an oscillator is demonstrated.

260-megahertz, megawatt-level thin-disk oscillator.

A Kerr-lens mode-locked (KLM) Yb:YAG thin-disk oscillator delivering 215-fs pulses with 75-W average power and 1.4-MW peak power at a repetition rate of 260 MHz is presented. Self-starting KLM is demonstrated at an output power of 68 W. This is the highest repetition rate of any mode-locked thin-disk oscillators so far. Concepts for scaling the repetition rate up to 1 GHz are discussed.

Energy scaling of Kerr-lens mode-locked thin-disk oscillators.

Geometric scaling of a Kerr-lens mode-locked Yb:YAG thin-disk oscillator yields femtosecond pulses with an average output power of 270 W. The scaled system delivers femtosecond (210-330 fs) pulses with a peak power of 38 MW. These values of average and peak power surpass the performance of any previously reported femtosecond laser oscillator operated in atmospheric air.

Correcting biases in psychiatric diagnostic practice in Northwest Russia: comparing the impact of a general educational program and a specific diagnostic training program.

BACKGROUND: A general education in psychiatry does not necessary lead to good diagnostic skills. Specific training programs in diagnostic coding are established to facilitate implementation of ICD-10 coding practices. However, studies comparing the impact of these two different educational approaches on diagnostic skills are lacking. The aim of the current study was to find out if a specific training program in diagnostic coding improves the diagnostic skills better than a general education program, and if a national bias in diagnostic patterns can be minimised by a specific training in diagnostic coding. METHODS: A pre post design study with two groups was carried in the county of Archangelsk, Russia. The control group (39 psychiatrists) took the required course (general educational program), while the intervention group (45 psychiatrists) were given a specific training in diagnostic coding. Their diagnostic skills before and after education were assessed using 12 written case-vignettes selected from the entire spectrum of psychiatric disorders. RESULTS: There was a significant improvement in diagnostic skills in both the intervention group and the control group. However, the intervention group improved significantly more than did the control group. The national bias was partly corrected in the intervention group but not to the same degree in the control group. When analyzing both groups together, among the background factors only the current working place impacted the outcome of the intervention. CONCLUSION: Establishing an internationally accepted diagnosis seems to be a special skill that requires specific training and needs to be an explicit part of the professional educational activities of psychiatrists. It does not appear that that skill is honed without specific training. The issue of national diagnostic biases should be taken into account in comparative cross-cultural studies of almost any character. The mechanisms of such biases are complex and need further consideration in future research. Future research should also address the question as to whether the observed improvement in diagnostic skills after specific training actually leads to changes in routine diagnostic practice.