a b s t r a c tThis study presents an evaluation of an advanced Doppler radar-based method for detection of vital signs, presence, and activity of a human subject in a test room with radar-signal reflecting aluminum-coated surfaces. Ten test subjects lay in four positions, and they sat in two locations in the room, both breathing normally and holding their breath. The mean ratios of the pulse rates determined from the radar signal and electrocardiography and respiration reference signals were 110% (respiration) and 99% (heartbeat), and the mean occupied and empty room radar signal variance ratios were 608 (breathing) and 20 (breath-hold). In a one-subject activity monitoring test, walking, standing and lying activities could be well separated from the radar signal. The results are promising and the proposed system seems to have potential to be used in position-independent health and activity monitoring of, for example, elderly people in care homes or intoxicated people in police custody.

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Requirements for patient safety and a high interference rejection ratio in medical equipment create a demand for effective isolation devices. A system scale approach that uses capacitive coupling for power and signal isolation is presented. In addition, we describe the development of an instrumentation system prototype that applies microwaves for power exchange and bidirectional data transfer across the isolation barrier. The system consists of an isolated transducer unit, a central unit, and a single coaxial cable between the units. The isolation capacitance is as low as 1.6 pF, inclusive of the digital data transfer and power exchange up to 600 mW of isolated direct current (dc) power. The system is suitable for line-powered biopotential measurements and it is shown that reducing the isolation capacitance from 180 to 1.6 pF improves the power line rejection by 30 dB in a typical electrocardiogram (ECG) measurement setup.

Millimeter and submillimeter wave receivers in scanning planar near-field test systems are commonly based on harmonic mixing and thus require at least one flexible microwave cable to be connected to them. The phase errors originated in these cables get multiplied and added to the phase of the final detected signal. A complete submillimeter setup with on-the-fly measurement of phase errors is presented. The novel phase error correction system is based on the use of a pilot signal to measure the phase errors caused by cable flexing. The measured phase error surface in the quiet-zone region of a 310 GHz compact antenna test range (CATR) based on a hologram is shown as an application example. The maximum measured phase error due to the cable within a 80 90 cm 2 scan area was 38 .

The recovery of 16 infants born by elective caesarean section with spinal anaesthesia, in which either ephedrine or fluid load was used to prevent maternal hypotension, were studied using Scanlon's neurobehavioural tests and a computerized EEG. Neurobehavioural testing showed no differences between the ephedrine and the non-ephedrine groups of infants at ages of 3 h, 1 day, 2 days and 4-5 days, whereas the spectral EEG showed significant differences between the two groups during the first 2 h after delivery, which had disappeared 24 h later. It is suggested that small doses of ephedrine given to the mother i.v. to prevent hypotension during spinal anaesthesia have short-lived effects on the neonate's central nervous system, which will be detected in the spectral EEG, but not in neurobehavioural tests.

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