A device for transferring articles from between two spaced locations, the device has at least two groups of inclined platforms, each platform having an upper article-receiving surface and a leading edge region, wherein each article-receiving surface of the first group is overlapped by a platform of the second group. Services may be developed that can be used to support different client devices with different capabilities. Flywheel speed may be monitored to provide feedback on power extraction for further control of the system. A controller is connected to the receiver and the controller stores each transmitter identifying code in a corresponding storage location. The mean particle size of the calcium containing compound is preferably smaller than 100 nm.