The heavy-duty circuit breaker contains a first moveable arcing contact piece and a second moveable arcing contact piece as well as an auxiliary drive for driving the second arcing contact piece. Quantitative information of a 3D retinal layer structure is acquired by detecting a range in which a peak of a retinal reflectance distribution obtained by OCT scanning is lost. The user can select individual search results to be shared and, in response to a search query, the user is provided with responsive search results, and also identification of individuals, from the user’s social network, that are responsive to the user’s search query. The detection arrangement allows the detection of islanding conditions even when the load is well matched to the generated power. The correctness checks determine a safe point in the program up to which the operations executed by the main hardware thread are correct. The volume control comprises a user setting and a master setting, wherein the user volume setting is operable to adjust the system volume over a limited volume range near the master volume setting, and wherein the master volume is operable to change over time based on user volume settings.