Social aspects of collision avoidance: a detailed analysis of two-person groups and individual pedestrians.

Pedestrian groups are commonly found in crowds but research on their social aspects is comparatively lacking. To fill that void in literature, we study the dynamics of collision avoidance between pedestrian groups (in particular dyads) and individual pedestrians in an ecological environment, focusing in particular on (i) how such avoidance depends on the group's social relation (e.g. colleagues, couples, friends or families) and (ii) its intensity of social interaction (indicated by conversation, gaze exchange, gestures etc). By analyzing relative collision avoidance in the "center of mass" frame, we were able to quantify how much groups and individuals avoid each other with respect to the aforementioned properties of the group. A mathematical representation using a potential energy function is proposed to model avoidance and it is shown to provide a fair approximation to the empirical observations. We also studied the probability that the individuals disrupt the group by "passing through it" (termed as intrusion). We analyzed the dependence of the parameters of the avoidance model and of the probability of intrusion on groups' social relation and intensity of interaction. We confirmed that the stronger social bonding or interaction intensity is, the more prominent collision avoidance turns out. We also confirmed that the probability of intrusion is a decreasing function of interaction intensity and strength of social bonding. Our results suggest that such variability should be accounted for in models and crowd management in general. Namely, public spaces with strongly bonded groups (e.g. a family-oriented amusement park) may require a different approach compared to public spaces with loosely bonded groups (e.g. a business-oriented trade fair).

The trefoil factor family 1 (TFF-1) and 3 (TFF-3) are upregulated in the saliva, gingival crevicular fluid and serum of periodontitis patients.

OBJECTIVE: This study aimed to investigate the levels of trefoil factor family (TFF)-1, TFF-3 and interleukin (IL)-1ß in gingival crevicular fluid (GCF), saliva and serum of patients with gingivitis, stage 3 periodontitis and healthy individuals. MATERIALS AND METHODS: A total of 100 individuals consisting of 25 periodontally healthy, 25 gingivitis and 50 stage 3 periodontitis, were enrolled in the study. Clinical periodontal examinations were recorded and GCF, saliva and serum samples were obtained. TFF-1, TFF-3 and IL-1ß were measured by ELISA. RESULTS: TFF-1 and TFF-3 levels in both GCF, saliva and serum were higher in periodontitis patients than healthy controls (p < .001) and gingivitis group (p < .01). The levels of these peptides in all biofluids were similar between gingivitis and healthy control groups (p > .05). GCF, saliva and serum IL-1ß levels were also higher in periodontitis patients than the controls (p < .01). Periodontitis patients had elevated GCF and saliva IL-ß levels than gingivitis group (p < .001). CONCLUSION: Elevated TFF-1 and TFF-3 levels both locally and systemically in periodontitis in parallel to increased IL-1ß levels might suggest that these peptides are involved in host response during the periodontal tissue destruction.

Leucine-rich alpha-2 glycoprotein (LRG): A novel acute phase protein expressed in Stage 3 Grade C periodontitis before and after periodontal therapy.

BACKGROUND: Leucine-rich alpha-2 glycoprotein (LRG) is a novel acute phase protein involved in inflammation-associated diseases and that considered to be induced by multiple proinflammatory cytokines. This study aimed to investigate gingival crevicular fluid (GCF) and serum levels of LRG, interleukin (IL)-6 and tumor necrosis factor (TNF)-α in patients with Stage 3 periodontitis before and after non-surgical periodontal treatment. METHODS: Twenty-five Stage 3 periodontitis and twenty-five periodontally healthy individuals were enrolled in the study. Clinical periodontal measurements were recorded; periodontitis patients received non-surgical periodontal treatment, and GCF and serum samples were obtained at baseline and at 6 weeks after treatment. LRG, IL-6 and TNF-α were determined by ELISA. RESULTS: GCF and serum LRG, IL-6 and TNF-α were significantly higher in periodontitis group than healthy controls (P < .001). A significant decrease in GCF and serum LRG, IL-6 and TNF-α was detected after periodontal treatment compared with baseline values of periodontitis patients (P < .001). CONCLUSION: Our findings revealed that LRG expression was increased in Stage 3 periodontitis both locally and systemically, and non-surgical periodontal therapy was effective in reducing LRG levels in GCF and serum of these patients.

Nonsurgical Periodontal Therapy Reduces Salivary and Gingival Crevicular Fluid YKL-40 and IL-6 Levels in Chronic Periodontitis.

PURPOSE: A novel acute-phase protein, YKL-40, is known as an inflammation-associated glycoprotein. YKL-40 is shown to be linked to inflammation, endothelial dysfunction and tissue remodeling secreted by various cells and is also considered to be stimulated by cytokines such as interleukin-6 (IL-6). The present study aimed to investigate YKL-40 and IL-6 levels in saliva and gingival crevicular fluid (GCF) of patients with chronic periodontitis (CP) after non-surgical periodontal therapy for the first time. MATERIALS AND METHODS: Twenty-six CP patients and 26 periodontally healthy individuals were enrolled. Clinical measurements were recorded; saliva and GCF samples were obtained at baseline and 1 and 3 months after non-surgical periodontal therapy. Levels of YKL-40 and IL-6 in saliva and GCF were analysed by ELISA. RESULTS: Salivary and GCF YKL-40 and IL-6 levels were found to be statistically significantly higher in CP patients compared to healthy controls at baseline (p < 0.001). At 1 and 3 months after the completion of treatment, both YKL-40 and IL-6 levels in saliva and GCF had statistically significantly decreased compared with baseline values in CP patients (p < 0.001). On the other hand, no statistically significant difference was observed between 1 and 3 months in terms of salivary and GCF YKL-40 and IL-6 levels or any of the clinical findings (p > 0.016). CONCLUSION: Salivary and GCF YKL-40 levels may be useful to evaluate resolution of periodontal inflammation. Within the limits of this study, YKL-40 acute-phase protein might be a potential biomarker for detection of periodontitis and monitoring the response to periodontal therapy.

Local and systemic levels of aMMP-8 in gingivitis and stage 3 grade C periodontitis.

THE OBJECTIVE: This study aimed to analyze active matrix metalloproteinase (aMMP-8) levels in gingival crevicular fluid (GCF), saliva and serum in the context of new criteria of gingivitis and stage 3 grade C periodontitis. THE BACKGROUND: Periodontal disease is an inflammatory process that can result in tooth loss and also is considered a modifying factor for systemic health. Matrix metalloproteinase (MMP)-8 is the major collagenase of periodontal tissue breakdown. METHODS: Totally 83 systemically healthy and non-smoker individuals consisting of 23 periodontally healthy, 20 gingivitis and 40 stage 3 periodontitis, were recruited to the study. Clinical periodontal examinations of probing depth (PD), clinical attachment loss (CAL), gingival index (GI), plaque index (PI) and bleeding on probing (BOP) were recorded; and GCF, saliva and serum samples were obtained. aMMP-8 was measured by immunofluorometric assay (IFMA). RESULTS: GCF and serum aMMP-8 levels were significantly increased in periodontitis and gingivitis compared to healthy ones (P < .001), whereas gingivitis and periodontitis patients showed similar levels of aMMP-8 in GCF and serum (P > .05). Saliva levels of aMMP-8 were higher in periodontitis patients than both gingivitis and healthy individuals (P < .001). There was no significant difference in salivary aMMP-8 levels between gingivitis group and healthy controls (P > .05). CONCLUSION: These findings support the involvement of aMMP-8 in periodontal diseases and suggest that its local and systemic levels can reflect stage 3 grade C periodontitis. Moreover, aMMP-8 in GCF and serum seems to have a potential to differentiate between gingivitis and periodontal health.

Effect of non-surgical periodontal treatment on gingival crevicular fluid hypoxia inducible factor-1 alpha, vascular endothelial growth factor and tumor necrosis factor-alpha levels in generalized aggressive periodontitis patients.

BACKGROUND: Hypoxia-inducible angiogenic pathway involving hypoxia inducible factor-1 alpha (HIF-1α), vascular endothelial growth factor (VEGF) and tumor necrosis factor-alpha (TNF-α) may regulate several biological processes related to inflammation. The present study aimed to assess the effect of non-surgical periodontal treatment on gingival crevicular fluid (GCF) HIF-1α, VEGF, and TNF-α levels in generalized aggressive periodontitis (G-AgP). METHODS: Twenty G-AgP patients and 20 periodontally healthy individuals were included. G-AgP patients received scaling and root planning (SRP), per quadrant at a 1-week-interval, performed with ultrasonic and periodontal hand instruments. GCF samples were collected and clinical periodontal parameters including probing depth, clinical attachment level, gingival index and plaque index were recorded at baseline, 1 and 3 months after treatment. Biomarker levels in GCF were analyzed by ELISA. RESULTS: At baseline all clinical parameters and GCF HIF-1α, VEGF, and TNF-α levels were significantly higher in G-AgP patients compared to healthy control (P < 0.05). All clinical parameters improved over the 3-month-period in G-AgP patients (P < 0.05). GCF HIF-1α levels in G-AgP reduced at 1 and 3 months post-treatment, however, this did not reach to statistical significance (P > 0.05). GCF VEGF and TNF-α levels remained unchanged throughout the study period (P > 0.05). CONCLUSIONS: Within the limitations of the present study, although HIF-1α seems to possess a potential diagnostic value for G-AgP, it might not be a proper predictor of clinically favorable treatment outcome. SRP plus different adjunctive therapies could provide better information about the prognostic role of hypoxia-inducible angiogenic pathway in G-AgP.

Salivary biomarkers in the context of gingival inflammation in children with cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) is a life-threatening chronic inflammatory disease in children due to respiratory complications. Saliva could serve as a reservoir of bacterial colonization and potentially reflect systemic inflammation. This study investigated whether salivary triggering receptor expressed on myeloid cells 1 (TREM-1), peptidoglycan recognition protein 1 (PGLYRP1), interleukin (IL)-1ß, and calprotectin are associated with CF or reflect concomitant gingival inflammation. METHODS: Ten CF (aged 3 to 12 years) and 10 systemically healthy (SH) age- and sex-matched children (C) were enrolled in the study. Individuals with CF underwent routine laboratory determinations. Probing depth, gingival index (GI), plaque index (PI), and bleeding on probing (BOP) were recorded on fully erupted teeth and saliva samples collected. Salivary TREM-1, PGLYRP1, IL-1ß, and calprotectin were analyzed by enzyme-linked immunosorbent assay. RESULTS: Children with CF had significantly higher BOP scores (P = 0.001) and calprotectin levels (P = 0.017) compared with the C group. TREM-1, PGLYRP1, and IL-1ß could not distinguish between CF and SH but showed positive correlation with GI, PI, and BOP in both groups. Calprotectin levels positively correlated with procalcitonin (P = 0.014), thrombocyte counts (P = 0.001), mean platelet volume (P = 0.030), and with PGLYRP1 (P = 0.019) and IL-1ß (P = 0.013) in CF children. Receiver operating characteristic curve analysis for calprotectin (CFvsC) showed an area under the curve of 0.79 (95% CI 0.58 to 0.99, P = 0.034). CONCLUSIONS: CF children presented with higher gingival inflammation scores and salivary calprotectin levels, that correlated with systemic inflammatory markers. Salivary calprotectin levels were not associated with periodontal parameters. Hence, preliminary data demonstrate that salivary calprotectin might have a chairside diagnostic potential for CF in children.

Intrinsic group behaviour II: On the dependence of triad spatial dynamics on social and personal features; and on the effect of social interaction on small group dynamics.

In a follow-up to our work on the dependence of walking dyad dynamics on intrinsic properties of the group, we now analyse how these properties affect groups of three people (triads), taking also in consideration the effect of social interaction on the dynamical properties of the group. We show that there is a strong parallel between triads and dyads. Work-oriented groups are faster and walk at a larger distance between them than leisure-oriented ones, while the latter move in a less ordered way. Such differences are present also when colleagues are contrasted with friends and families; nevertheless the similarity between friend and colleague behaviour is greater than the one between family and colleague behaviour. Male triads walk faster than triads including females, males keep a larger distance than females, and same gender groups are more ordered than mixed ones. Groups including tall people walk faster, while those with elderly or children walk at a slower pace. Groups including children move in a less ordered fashion. Results concerning relation and gender are particularly strong, and we investigated whether they hold also when other properties are kept fixed. While this is clearly true for relation, patterns relating gender often resulted to be diminished. For instance, the velocity difference due to gender is reduced if we compare only triads in the colleague relation. The effects on group dynamics due to intrinsic properties are present regardless of social interaction, but socially interacting groups are found to walk in a more ordered way. This has an opposite effect on the space occupied by non-interacting dyads and triads, since loss of structure makes dyads larger, but causes triads to lose their characteristic V formation and walk in a line (i.e., occupying more space in the direction of movement but less space in the orthogonal one).

Identification of social relation within pedestrian dyads.

This study focuses on social pedestrian groups in public spaces and makes an effort to identify the type of social relation between the group members. As a first step for this identification problem, we focus on dyads (i.e. 2 people groups). Moreover, as a mutually exclusive categorization of social relations, we consider the domain-based approach of Bugental, which precisely corresponds to social relations of colleagues, couples, friends and families, and identify each dyad with one of those relations. For this purpose, we use anonymized trajectory data and derive a set of observables thereof, namely, inter-personal distance, group velocity, velocity difference and height difference. Subsequently, we use the probability density functions (pdf) of these observables as a tool to understand the nature of the relation between pedestrians. To that end, we propose different ways of using the pdfs. Namely, we introduce a probabilistic Bayesian approach and contrast it to a functional metric one and evaluate the performance of both methods with appropriate assessment measures. This study stands out as the first attempt to automatically recognize social relation between pedestrian groups. Additionally, in doing that it uses completely anonymous data and proves that social relation is still possible to recognize with a good accuracy without invading privacy. In particular, our findings indicate that significant recognition rates can be attained for certain categories and with certain methods. Specifically, we show that a very good recognition rate is achieved in distinguishing colleagues from leisure-oriented dyads (families, couples and friends), whereas the distinction between the leisure-oriented dyads results to be inherently harder, but still possible at reasonable rates, in particular if families are restricted to parent-child groups. In general, we establish that the Bayesian method outperforms the functional metric one due, probably, to the difficulty of the latter to learn observable pdfs from individual trajectories.

Intrinsic group behaviour: Dependence of pedestrian dyad dynamics on principal social and personal features.

Being determined by human social behaviour, pedestrian group dynamics may depend on "intrinsic properties" such as the purpose of the pedestrians, their personal relation, gender, age, and body size. In this work we investigate the dynamical properties of pedestrian dyads (distance, spatial formation and velocity) by analysing a large data set of automatically tracked pedestrian trajectories in an unconstrained "ecological" setting (a shopping mall), whose apparent physical and social group properties have been analysed by three different human coders. We observed that females walk slower and closer than males, that workers walk faster, at a larger distance and more abreast than leisure oriented people, and that inter-group relation has a strong effect on group structure, with couples walking very close and abreast, colleagues walking at a larger distance, and friends walking more abreast than family members. Pedestrian height (obtained automatically through our tracking system) influences velocity and abreast distance, both growing functions of the average group height. Results regarding pedestrian age show that elderly people walk slowly, while active age adults walk at the maximum velocity. Groups with children have a strong tendency to walk in a non-abreast formation, with a large distance (despite a low abreast distance). A cross-analysis of the interplay between these intrinsic features, taking in account also the effect of an "extrinsic property" such as crowd density, confirms these major results but reveals also a richer structure. An interesting and unexpected result, for example, is that the velocity of groups with children increases with density, at least in the low-medium density range found under normal conditions in shopping malls. Children also appear to behave differently according to the gender of the parent.

Deciphering the crowd: modeling and identification of pedestrian group motion.

Associating attributes to pedestrians in a crowd is relevant for various areas like surveillance, customer profiling and service providing. The attributes of interest greatly depend on the application domain and might involve such social relations as friends or family as well as the hierarchy of the group including the leader or subordinates. Nevertheless, the complex social setting inherently complicates this task. We attack this problem by exploiting the small group structures in the crowd. The relations among individuals and their peers within a social group are reliable indicators of social attributes. To that end, this paper identifies social groups based on explicit motion models integrated through a hypothesis testing scheme. We develop two models relating positional and directional relations. A pair of pedestrians is identified as belonging to the same group or not by utilizing the two models in parallel, which defines a compound hypothesis testing scheme. By testing the proposed approach on three datasets with different environmental properties and group characteristics, it is demonstrated that we achieve an identification accuracy of 87% to 99%. The contribution of this study lies in its definition of positional and directional relation models, its description of compound evaluations, and the resolution of ambiguities with our proposed uncertainty measure based on the local and global indicators of group relation.

Joint attention by gaze interpolation and saliency.

Joint attention, which is the ability of coordination of a common point of reference with the communicating party, emerges as a key factor in various interaction scenarios. This paper presents an image-based method for establishing joint attention between an experimenter and a robot. The precise analysis of the experimenter's eye region requires stability and high-resolution image acquisition, which is not always available. We investigate regression-based interpolation of the gaze direction from the head pose of the experimenter, which is easier to track. Gaussian process regression and neural networks are contrasted to interpolate the gaze direction. Then, we combine gaze interpolation with image-based saliency to improve the target point estimates and test three different saliency schemes. We demonstrate the proposed method on a human-robot interaction scenario. Cross-subject evaluations, as well as experiments under adverse conditions (such as dimmed or artificial illumination or motion blur), show that our method generalizes well and achieves rapid gaze estimation for establishing joint attention.

Automated discrimination of psychotropic drugs in mice via computer vision-based analysis.

We developed an inexpensive computer vision-based method utilizing an algorithm which differentiates drug-induced behavioral alterations. The mice were observed in an open-field arena and their activity was recorded for 100 min. For each animal the first 50 min of observation were regarded as the drug-free period. Each animal was exposed to only one drug and they were injected (i.p.) with either amphetamine or cocaine as the stimulant drugs or morphine or diazepam as the inhibitory agents. The software divided the arena into virtual grids and calculated the number of visits (sojourn counts) to the grids and instantaneous speeds within these grids by analyzing video data. These spatial distributions of sojourn counts and instantaneous speeds were used to construct feature vectors which were fed to the classifier algorithms for the final step of matching the animals and the drugs. The software decided which of the animals were drug-treated at a rate of 96%. The algorithm achieved 92% accuracy in sorting the data according to the increased or decreased activity and then determined which drug was delivered. The method differentiated the type of psychostimulant or inhibitory drugs with a success ratio of 70% and 80%, respectively. This method provides a new way to automatically evaluate and classify drug-induced behaviors in mice.