Background Fibre-optic nasoendoscopy and fibre-optic laryngoscopy are high-risk procedures in the coronavirus disease 2019 era, as they are potential aerosol-generating procedures. Barrier protection remains key to preventing transmission. Methods A device was developed that patients can wear to reduce potential aerosol contamination of the surroundings. Conclusion This device is simple, reproducible, easy to use, economical and well-tolerated. Full personal protection equipment should additionally be worn by the operator.

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The feasibility of transferring power over a wide range of distances and orientation offsets has been proven in air for various commercial applications, notably in the electric vehicle industry, by using two loosely-coupled RLC circuits that are tuned to resonate at the same frequency. Key system concepts for resonant wireless power transfer, such as frequency splitting, maximum operating distance, and behavior of the system as it becomes over and under coupled, are well understood theoretically, and demonstrated experimentally. Although prior work on WPT in air is quite extensive and mature, very little research has been conducted on underwater WPT. In particular, no studies have been published describing how basic system concepts vary within a conducting medium such as seawater. In this paper, we report the results of experiments addressing the effects of seawater conductivity on underwater resonant wireless power transfer, compared to the basic system concepts exhibited in air. Results indicate that the losses due to seawater become noticeable for frequencies around 20 kHz, and can be large for frequencies above 50 kHz.

This paper describes the design, calibration and application of an instrument that measures the effects of unsteady air flow (airwake) on a helicopter in flight. The instrument is a 1/54th-scale model helicopter that is mounted on a six-component dynamic force balance to measure the forces and moments that an airwake imposes onto the helicopter; it is therefore an ‘Airwake Dynamometer’ to which we have given the name AirDyn. The AirDyn has been designed, in particular, to measure the effect of a ship airwake on a helicopter translating over the ship's landing deck. The AirDyn, which has been implemented in a water tunnel, in preference to a wind tunnel, senses the integrated effect of a turbulent airwake on the helicopter, and the resulting unsteady forces and moments are an indication of the workload the pilot would need to exert to counteract these effects in a real helicopter. Binocular sensing elements and semiconductor strain gauges have been adopted to achieve high sensitivity and relatively high stiffness. The compact strain gauge balance is fitted into the helicopter fuselage, and protective coatings and a flexible bellows are used to seal the balance and protect it from the water. The coefficient matrix of the AirDyn has been obtained by static calibrations, while impulse excitation tests have confirmed that its frequency response is suitable for the measurements of unsteady loads. The application of the instrument is illustrated by using it to quantify the effect that a bulky ship mast has on the airwake and thus on a helicopter as it lands onto a simplified ship in a scaled 50 knot headwind.

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