Optimizing gamma-ray spectrometers for UAV-borne surveys with geophysical applications.

Heavy duty unmanned aerial vehicles (UAVs) have made it possible to fly with large gamma-ray spectrometers that weigh several kilograms. Moreover, they can be purchased at an affordable price. These large UAV-borne gamma-ray detection systems are used to map the naturally occurring radionuclides K, U, Th.

Footprint and height corrections for UAV-borne gamma-ray spectrometry studies.

Advancements in the development of gamma-ray spectrometers (GRS) have led to small and lightweight spectrometers that can be used under unmanned aerial vehicles (UAVs). Airborne GRS measurements are used to determine radionuclide concentrations in the ground, among which the natural occurring radionuclides K, U, and Th. For successful applications of these GRS sensors, it is important that absolute values of concentrations can be measured.

[Avoidable visual impairment among residents in care institutions: lessons from an intervention project in the Den Bosch region].

Introduction: Many elderly in care institutions in The Netherlands are visually impaired (visual acuity < 0.3). They fall more frequently, are more depressed and require more care.

[Increase in the demand for eye-care services in the Netherlands 2010-2020].

Objective: The demand for eye-care services in the Netherlands is increasing. This article indicates the causes and attempts to provide an estimate of the increase between 2010 and 2020 and to indicate what will be the consequences.

Design: Descriptive study.

Monte Carlo based calibration of scintillation detectors for laboratory and in situ gamma ray measurements.

The calibration of scintillation detectors for gamma radiation in a well characterized setup can be transferred to other geometries using Monte Carlo simulations to account for the differences between the calibration and the other geometry. In this study a calibration facility was used that is constructed from bricks of well-known activity concentrations of ⁴⁰K and of radionuclides from the ²³⁸U- and ²³²Th-series. Transfer of the calibration was attempted to a Marinelli beaker geometry with the detector inside a lead shield and to an in situ application with the detector positioned on a sand bed.