A photodetecting circuit includes an adder that selectively adds outputs of a plurality of circuits for photodetection. The foundation engaging member is configured to abut a substantially planar portion of a foundation of a building structure. The payment authority system may generate a payment code for transmission to the mobile device. A longitudinal cross-sectional shape of at least a portion of the helical thread of the thread forming section in certain embodiments, substantially corresponds to a longitudinal cross-sectional shape of at least a portion of the helical thread of the implant.