[Needlestick Injuries to Medical Students]. / Nadelstichverletzungen bei Studierenden der Humanmedizin.

The study aimsed at surveying and analysing the prevailing risks for medical students due to so-called needlestick injuries, I. e., injuries to the skin by handling sharp objects by which blood of patients can be transmitted to the health professional. After introducing preventive measures in a typical German university hospital, a total of 1 903 students of human medicine in their clinical period from 2009 to 2012 (from a total of 2 024 subjects - a rate of 94.0%) were questioned in detail about potential needlestick or other injuries related to their work. The results show that such injuries happen particularly during the clinical period of the medical studies: While only 20.6% of the students indicated a needlestick injury at the beginning of this period, half of the students (50.9%) had experienced at least one injury at the end of the clinical period. The activities mentioned most frequently were taking of blood samples and injections. Needlestick injuries happened most frequently in surgical units, in internal medicine, and in gynaecology. Accidents happened mostly during secondary employment, medical traineeship, or in the context of practical nursing. In consequence, measures for improvement of the primary prevention should start with training on the one hand: Only briefing seems to be insufficient - intensive exercises in using stick-proof instruments seems to be more promising. On the other hand, the comprehensive introduction of stick-proof instruments has to be supported.

Absolute interferometric distance measurement using a FM-demodulation technique.

We propose an interferometric method for measuring absolute distances larger than the wavelength. A laser diode is used as a light source. The principle of operation is based on multiple-wavelength interferometry that uses a modulated light source. This method uses the fact that the wavelength of light emitted by the laser diode can be varied by means of the injection current. The modulation of the injection current in combination with the optical heterodyne technique causes a high-frequency phase-modulated detector signal. The phase deviation of the signal is a measure of the optical path difference in the interferometer. By FM demodulation of the detector output with a phase-locked loop demodulator, the optical path difference can be determined directly without the classical ambiguity problem of interferometry. The measuring range in the experiments was limited to 50 mm by the maximum travel range of the used specimen translation stage. Because of the inherent light sensitivity of the method described, the rangefinder can be used for three-dimensional profile measurements on a wide variety of objects, even on diffuse scattering surfaces.