Systems and methods are described that facilitate exploration and mining of a corpus of documents using concepts and knowledge, rather than keywords and enable interactive visualization, management, monetization, and personalization of knowledge search results on a user interface. The resistance evaluation unit is utilized for evaluating a ratio of an off-chip resistor and a basic resistor to generate a control signal by a successive approximation method. The medical diagnosis and tracking system also includes a historical images archive adapted to storing the one or more current images andor one or more historical images. The proximal end is attached to the first transducer so as to receive the ultrasonic vibrations therefrom and to transmit the ultrasonic vibrations toward the tip attached to the distal end. The extension arm also includes an upper channel and a lower channel. A sentiment of each of the active users is determined based on the computed sentiment score of each of the selected keywords that are authored by a particular active user.