Head movement in conversation

This work explores the function and form of head movement and specifically head nods in free conversation. It opens with a comparison of three theories that are often considered as triggers for head nods: mimicry, backchannel responses, and responses to speakers' trouble. Early in this work it is assumed that head nods are well defined in terms of movement, and that they can be directly attributed, or at least better explained, by one theory compared to the others. To test that, comparisons between the theories are conducted following two different approaches. In one set of experiments a novel virtual reality method enables the analysis of perceived plausibility of head nods generated by models inspired by these theories. The results suggest that participants could not consciously assess differences between the predictions of the different theories. In part, this is due to a mixture of gamification and study design challenges. In addition, these experiments raise the question of whether or not it is reasonable to expect people to consciously process and report issues with the non-verbal behaviour of their conversational partners. In a second set of experiments the predictions of the theories are compared directly to head nods that are automatically detected from motion capture data. Matching the predictions with automatically detected head nods showed that not only are most predictions wrong, but also that most of the detected head nods are not accounted by any of the theories under question. Whereas these experiments do not adequately answer which theory best describe head nods in conversation, they suggest new avenues to explore: are head nods well defined in the sense that multiple people will agree that a specific motion is a head nod? and if so, what are their movement characteristics and what is their reliance on conversational context? Exploring these questions revealed a complex picture of what people consider to be head nods and their reliance on context. First, the agreement on what is a head nod is moderate, even when annotators are presented with video snippets that include only automatically detected nods. Second, head nods share movement characteristics with other behaviours, specifically laughter. Lastly, head nods are more accurately defined by their semantic characteristics than by their movement properties, suggesting that future detectors should incorporate more contextual features than movement alone. Overall, this thesis questions the coherence of our intuitive notion of a head nod and the adequacy of current approaches to describe the movements involved. It shows how some of the common theories that describe head movement and nods fail to explain most head movement in free conversation. In addition, it highlights subtleties in head movement and nods that are often overlooked. The findings from this work can inform the development of future head nods detection approaches, and provide a better understanding of non-verbal communication in general

Speakers Raise their Hands and Head during Self-Repairs in Dyadic Conversations

People often encounter difficulties in building shared understanding during everyday conversation. The most common symptom of these difficulties are self-repairs, when a speaker restarts, edits or amends their utterances mid-turn. Previous work has focused on the verbal signals of self-repair, i.e. speech disfluences (filled pauses, truncated words and phrases, word substitutions or reformulations), and computational tools now exist that can automatically detect these verbal phenomena. However, face-to-face conversation also exploits rich non-verbal resources and previous research suggests that self-repairs are associated with distinct hand movement patterns. This paper extends those results by exploring head and hand movements of both speakers and listeners using two motion parameters: height (vertical position) and 3D velocity. The results show that speech sequences containing self-repairs are distinguishable from fluent ones: speakers raise their hands and head more (and move more rapidly) during self-repairs. We obtain these results by analysing data from a corpus of 13 unscripted dialogues, and we discuss how these findings could support the creation of improved cognitive artificial systems for natural human-machine and human-robot interaction

The NlpD Lipoprotein Is a Novel Yersinia pestis Virulence Factor Essential for the Development of Plague

Yersinia pestis is the causative agent of plague. Previously we have isolated an attenuated Y. pestis transposon insertion mutant in which the pcm gene was disrupted. In the present study, we investigated the expression and the role of pcm locus genes in Y. pestis pathogenesis using a set of isogenic surE, pcm, nlpD and rpoS mutants of the fully virulent Kimberley53 strain. We show that in Y. pestis, nlpD expression is controlled from elements residing within the upstream genes surE and pcm. The NlpD lipoprotein is the only factor encoded from the pcm locus that is essential for Y. pestis virulence. A chromosomal deletion of the nlpD gene sequence resulted in a drastic reduction in virulence to an LD50 of at least 107 cfu for subcutaneous and airway routes of infection. The mutant was unable to colonize mouse organs following infection. The filamented morphology of the nlpD mutant indicates that NlpD is involved in cell separation; however, deletion of nlpD did not affect in vitro growth rate. Trans-complementation experiments with the Y. pestis nlpD gene restored virulence and all other phenotypic defects. Finally, we demonstrated that subcutaneous administration of the nlpD mutant could protect animals against bubonic and primary pneumonic plague. Taken together, these results demonstrate that Y. pestis NlpD is a novel virulence factor essential for the development of bubonic and pneumonic plague. Further, the nlpD mutant is superior to the EV76 prototype live vaccine strain in immunogenicity and in conferring effective protective immunity. Thus it could serve as a basis for a very potent live vaccine against bubonic and pneumonic plague

Systemic Arthritis in Children: A Review of Clinical Presentation and Treatment

Systemic juvenile idiopathic arthritis (sJIA) constitutes a small part of juvenile idiopathic arthritis (JIA), yet has a disproportionally higher rate of mortality. Despite being grouped under JIA, it is considered to be a multifactorial autoinflammatory disease. The objective of this paper is to review the epidemiology, pathogenesis, genetics, clinical manifestations, complications, therapy, prognosis, and outcome of sJIA. The presentation and clinical manifestations of sJIA have not changed much in the past several decades, but the collective understanding of the pathogenesis and the development of new targeted therapies (particularly the biologic agents) have transformed and improved the disease outcome for children with sJIA