Recognizing Engagement Behaviors in Human-Robot Interaction

Based on analysis of human-human interactions, we have developed an initial model of engagement for human-robot interaction which includes the concept of connection events, consisting of: directed gaze, mutual facial gaze, conversational adjacency pairs, and backchannels. We implemented the model in the open source Robot Operating System and conducted a human-robot interaction experiment to evaluate it

CARBON QUANTUM DOTS: BRIDGING THE GAP BETWEEN CHEMICAL STRUCTURE AND MATERIAL PROPERTIES

Carbon quantum dots (CQDs) are the latest generation of carbon nanomaterials in applications where fullerenes, carbon nanotubes, and graphene are abundantly used. With several attractive properties such as tunable optical property, edge-functionalization, and defect-rich chemical structure, CQDs have the potential to revolutionize optoelectronics, electro- and photocatalysis, and biomedical applications. Chemical modifications through the addition of heteroatoms, chemical reduction, and surface passivation are found to alter the band gap, spectral position, and emission pathways of CQDs. Despite extensive studies, fundamental understanding of structure-property relationship remains unclear due to the inhomogeneity in chemical structure and a complex emission mechanism for CQDs. This dissertation outlines a series of works that investigate the structure-property relationship of CQDs and its impact in a variety of applications. First, this relationship was explored by modifying specific chemical functionalities of CQDs and relating them to differences observed in optical, catalytic, and pharmacological performance. While a number of scientific articles reported that top-down or bottom-up synthesized CQDs yielded similar properties, the results herein present dissimilar chemical structures as well as photoluminescent and metal sensing properties. Second, the role of nitrogen heteroatoms in top-down synthesized CQD was studied. The effect of nitrogen atoms on spectral position and fluorescence quantum yield was considerably studied in past reports; however, thorough investigation to differentiate various nitrogen related chemical states was rarely reported. By finely tuning both the quantity of nitrogen doping and the distribution of nitrogen-related chemical states, we found that primary amine and pyridine induce a red-shift in emission while pyrrolic and graphitic nitrogen produced a blue-shift in emission. The investigation of nitrogen chemical states was extended to bottom-up synthesized CQDs with similar results. Finally, top-down, bottom-up, nitrogen-doped and chemically reduced CQDs were separately tested for their ability to act as photodynamic anti-cancer agents. This series of experiments uncovered the distribution of reactive oxygen species produced during light exposure which elucidated the photodynamic mechanisms of cancer cytotoxicity. The results presented in this dissertation provide key insight into engineering finely-tailored CQDs as the ideal nanomaterial for a broad range of applications

Toward language-independent program verification

Recent years have seen a renewed interest in the area of deductive program verification, with focus on verifying real-world software components. Success stories include the verification of operating system kernels and of compilers. This dissertation describes techniques for automatically building efficient correct-by-construction program verifiers for real-world languages from operational semantics. In particular, reachability logic is proposed as a foundation for achieving language-independent program verification. Reachability logic can express both operational semantics and program correctness properties, and has a sound and (relatively) complete proof systems that derives the program correctness properties from the operational semantics. These techniques have been implemented in the K verification infrastructure, which in turn yielded automatic program verifiers for C, Java, and JavaScript. These verifiers are evaluated by checking the full functional correctness of challenging heap manipulation programs implementing the same data-structures in these languages (e.g. AVL trees). This dissertation also describes the natural proof methodology for automated reasoning about heap properties

Towards long-term social child-robot interaction: using multi-activity switching to engage young users

Social robots have the potential to provide support in a number of practical domains, such as learning and behaviour change. This potential is particularly relevant for children, who have proven receptive to interactions with social robots. To reach learning and therapeutic goals, a number of issues need to be investigated, notably the design of an effective child-robot interaction (cHRI) to ensure the child remains engaged in the relationship and that educational goals are met. Typically, current cHRI research experiments focus on a single type of interaction activity (e.g. a game). However, these can suffer from a lack of adaptation to the child, or from an increasingly repetitive nature of the activity and interaction. In this paper, we motivate and propose a practicable solution to this issue: an adaptive robot able to switch between multiple activities within single interactions. We describe a system that embodies this idea, and present a case study in which diabetic children collaboratively learn with the robot about various aspects of managing their condition. We demonstrate the ability of our system to induce a varied interaction and show the potential of this approach both as an educational tool and as a research method for long-term cHRI

Gold nanoparticles with\ua0patterned surface monolayers for\ua0nanomedicine: current perspectives

Molecular self-assembly is a topic attracting intense scientific interest. Various strategies have been developed for construction of molecular aggregates with rationally designed properties, geometries, and dimensions that promise to provide solutions to both theoretical and practical problems in areassuch as drug delivery, medical diagnostics, and biosensors, to name but a few. In this respect, gold nanoparticles covered with self-assembled monolayers presenting nanoscale surface patterns\u2014typically patched, striped or Janus-like domains\u2014represent an emerging field. These systems are particularly intriguing for use in bio-nanotechnology applications, as presence of such monolayers with three-dimensional (3D) morphology providesnanoparticles with surface-dependent properties that, in turn, affect their biological behavior. Comprehensive understanding of the physicochemical interactions occurring at the interface between these versatile nanomaterials and biological systems is therefore crucial to fully exploit their potential. This review aims to explore the current state of development of such patterned, self-assembled monolayer-protected gold nanoparticles, through step-by-step analysis of their conceptual design, synthetic procedures, predicted and determined surface characteristics, interactions with and performance in biological environments, and experimental and computational methods currently employed for their investigation

STRATEGIES TO IMPROVE ELECTROCHEMICAL DETECTION OF NITRIC OXIDE IN BIOLOGICAL ENVIRONMENTS

Nitric oxide (NO) is a gaseous molecule of vast biological significance whose activity is likely to be concentration-dependent. As our understanding of this molecule becomes more nuanced and precise, so too must detection strategies evolve to detect NO with greater precision and accuracy. Spectroscopic techniques are able to measure NO with high specificity, but the only technique unhindered by complex instrumentation and the requirement for additional reagents, and able to measure NO directly in situ, is electrochemistry. However, bare electrodes are unable measure NO with sufficient selectivity and sensitivity, particularly in biological environments, necessitating the use of transducer surface modifiers to improve performance. Herein, systematic evaluations and comparisons of electrochemical NO sensor modifications were carried out. Electropolymerized films (EPFs) represent a class of selectivity-enhancing membranes favorable for their reproducible and self-terminating depositions. Six different monomers were evaluated for their permselectivity characteristics for NO against a panel of electroactive biological interferents. After tailored optimizations of their deposition parameters, polymers were also evaluated for their anti-fouling properties in simulated wound fluid. In addition to EPFs, another common strategy to improve NO sensor performance is the incorporation of metallophthalocyanine (MPc) electrocatalysts. Four MPc macrocycles (M = iron, cobalt, nickel, and zinc) previously determined to have the highest electrocatalytic activity towards NO oxidation were evaluated for their selectivity characteristics. The ability to specifically coordinate with NO at the metal center (as opposed to weak physisorption on the aromatic periphery) proved an adequate predictor of selectivity findings. Based on these evaluations of different modifiers, a solid-state electrochemical NO sensor was designed for long-term use in proteinaceous media. With extensive characterizations of sensocompatibility, the final NO sensor was capable of high sensitivity and selectivity retention with continuous operation in culture media. The sensor was then used to successfully interrogate the temporal (> 24 h) and spatial concentration profiles of macrophage NO release under neutral and pro-inflammatory stimulated conditions. Lastly, hydrogen sulfide (H2S) is another gasotransmitter responsible for mediating many of the same biological processes as NO, and may either upregulate or inhibit NO production in a manner likely to be concentration-dependent. An EPF-modified, solid-state electrode was therefore developed for selective detection of H2S for subsequent incorporation into a NO/H2S dual-sensor.Doctor of Philosoph