H. W. Jentink

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The effects of cooling of a hand on lateral and contralateral digital skin blood flow were investigated in 18 patients with primary or secondary Raynaud's phenomenon. The aim of the study was to compare photoelectrical plethsmography (PhEP) and laser Doppler flowmetry (LDF). PhEP and LDF were used simultaneously for skin blood flow measurements of the third(More)
Optical air flow measurements can support the testing of aircraft and can be instrumental to in-flight investigations of the atmosphere or atmospheric phenomena. Furthermore, optical air flow meters potentially contribute as avionics systems to flight safety and as air data systems. The qualification of these instruments for the flight environment is where(More)
New expressions are presented for light propagation in media for the whole range of absorption and for isotropic as well as for anisotropic scattering with an average cosine of the scattering angle between 0 and 0.9995. The method is based on the rigorous solution of the transport equation for Rayleigh-Gans scattering. The calculated angular intensity(More)
In March 1997 NLR investigated the icing atmosphere for aircraft by flying with an instrumented research aircraft through clouds. Liquid water content, droplet diameter distributions and air temperature were measured. Large droplets were found in air masses with a limited extent. Results from the measurement campaign are presented and compared with limits(More)
In their report on laser Doppler flow measurements (J. Biomed. Eng. 1985, 7, 225) Boggett et al. compared, among other things, three different light sources for use in a laser Doppler device. The aim of that study was to distinguish between Doppler shifted and non-shifted backscattered light to obtain a flow dependent signal, which is not caused by(More)
A very small and simple velocimeter is presented consisting of a diode laser with a gradient-index lens in front of it. The basis of the velocity measurement is the mixing that occurs when light, scattered back by the moving object into the laser cavity, interferes with light inside the laser. This mixing induces large fluctuations of the laser intensity(More)
Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded simultaneously in each infant. During 212 apneic spells with a(More)
Changes in forehead skin blood flow during active and quiet sleep were determined in 16 healthy neonates using a recently developed semi-conductor laser Doppler flow meter with-out light conducting fibres. Measurements were carried out at a postnatal age varying from 5 hours to 7 days. The two sleep states could be distinguished in 17 recordings. The mean(More)
Reactive hyperaemia, which occurs after a period of arterial occlusion is the result of an autoregulatory mechanism, involving local factors and autonomic nerve system control. To determine this autoregulatory mechanism in cutaneous blood flow in premature newborns measured the cutaneous reactive hyperaemia response after a 1 min occlusion, using a diode(More)