An electro-optical distance measuring device. Methods of using such fluids in subterranean operations also are provided. The system may enable a trainer component and a classifier component to determine the probability a user may take a particular action and to make predictions of likely user actions based on the observations of the user and the identified pattern of the user’s actions. The user interfaces may be automatically updated based on a context selected by the user. Each mounting portion may have a passageway therethrough to receive the proximal end of the corresponding pedicle screw; each passageway may intersect the edge of the corresponding engagement surface to facilitate percutaneous placement.