Speech-Gesture Mapping and Engagement Evaluation in Human Robot Interaction

A robot needs contextual awareness, effective speech production and complementing non-verbal gestures for successful communication in society. In this paper, we present our end-to-end system that tries to enhance the effectiveness of non-verbal gestures. For achieving this, we identified prominently used gestures in performances by TED speakers and mapped them to their corresponding speech context and modulated speech based upon the attention of the listener. The proposed method utilized Convolutional Pose Machine [4] to detect the human gesture. Dominant gestures of TED speakers were used for learning the gesture-to-speech mapping. The speeches by them were used for training the model. We also evaluated the engagement of the robot with people by conducting a social survey. The effectiveness of the performance was monitored by the robot and it self-improvised its speech pattern on the basis of the attention level of the audience, which was calculated using visual feedback from the camera. The effectiveness of interaction as well as the decisions made during improvisation was further evaluated based on the head-pose detection and interaction survey.Comment: 8 pages, 9 figures, Under review in IRC 201

Cerium oxide Nanoparticles: Their Phosphatase Activity and its Control

Cerium oxide nanoparticles are established scavengers of reactive oxygen and nitrogen species. They have many potential biomedical applications that depend on their physicochemical properties and mode of preparation. Recent studies have found these nanoparticles possess phosphatase mimetic activity. Studying such catalytic activities will qualify their biomedical applications and render information on their bioavailability and potential toxicity. Two oxidation states of cerium exist in these nanoparticles (3+ or 4+). It is hypothesized that the oxidation state of cerium in the nanoparticles determines the amount of adsorbed water on the crystal lattices. This in turn governs their activity as phosphatases. Nanoparticles with higher levels of cerium in the 4+ state exhibit phosphatase activity while those with higher levels of cerium in the 3+ state do not. This phosphatase activity may be controlled with the addition of inhibitory anions. It is hypothesized that anions with structures similar to phosphate can inhibit phosphatase activity by leading to the production of complexes on the surface of cerium oxide nanoparticles. Substrates that were used to test this activity include para-nitrophenyl phosphate (pNPP), 4-methylumbelliferyl phosphate (MUP) and adenosine triphosphate (ATP). To highlight the role of adsorbed water, we also performed experiments on pNPP with methanol as a solvent. The activity was measured by absorbance (pNPP and ATP) or fluorescence (MUP) and reported as nmol of phosphate/min. In some cases this rate was calculated through coupled reactions or by measuring the rate of formation of other colored products formed along with the release of phosphate such as pNP (para-nitrophenol). The phosphatase activity increased as the amount of adsorbed water increased implying that the abundance of adsorbed water makes the surface of 4+ ceria nanoparticles more active. Phosphatase activity for all the substrates exhibited Michaelis-Menten kinetics. Although the phosphatase activity of these nanoparticles is slow (turnover rate) as compared to real biological phosphatases, it can be used as a model catalytic activity to follow other catalytic activities that are associated with nanoparticles that have an abundance of cerium in the 4+ state, such as catalase activity. These results also provide information on the nature of the active sites involved in the catalytic activities associated with these nanoparticles. We identified three inhibitors, tungstate, molybdate and arsenate, which decreased the phosphatase activity of these nanoparticles in a dose dependent manner. Vmax, Km and Ki values were determined by varying substrate concentrations in the presence and absence of inhibitors. A partial mixed inhibition model was fit for each of these inhibitors. Summary: Phosphatase activity of cerium oxide nanoparticles with higher levels of cerium in the 4+ oxidation state was used as a model catalytic activity to study the nature of the active sites involved in catalysis. The study of inhibitors can reveal more information as to the surface binding of substrates in catalysis