The brush includes a core formed from a metal wire bent into a U and the branches of which are twisted to trap radial bristles between them, the core being fixed to the end of a wand. The node is configured, in response to receiving a request for file access from a mobile terminal, to identify a user folder, to determine whether the file managing system manages the user folder and, in dependence upon whether the file managing system manages the user folder, to retrieve an entry point for the user folder and to transmit the entry point to the mobile terminal. This new technique provides a highly localized targeting of tumor cells with only minor effects on overlying skin. In a number of embodiments, generating depth estimates considers the similarity of pixels in multiple spectral channels.