Circular Corridor Research Articles

Development and experimental validation of a humanoid pedestrian model that captures stepping behavior and body rotation

This paper presents a novel humanoid pedestrian model (HPM) incorporating stepping behavior and body rotation. The HPM is composed of two main components: (a) body modeling and (b) gait planning. A pedestrian is represented as a three-dimensional skeleton with 11 degrees of freedom in the body modeling component, which provides a universal approach for explaining the mathematical correlations between joint rotation angles and critical gait parameters such as step length, step width, and projected shoulder width. A framework for designing gaits that accounts for step-synchronization behavior and the effect of body rotation on stepping behavior is offered by the gait planning process. To validate the model, two types of experiments were conducted: nine sets of single-file experiments and 10 sets of bidirectional flow experiments, in which pedestrians walked in a 0.5-m-wide circular corridor and rotated their bodies to avoid collisions. It was suggested by the fundamental diagrams that body rotation reduces the walking speed of a pedestrian and consequently affects the overall flow rate. Furthermore, it was found that pedestrians were more resistant to moving forward in narrow bidirectional flow environments and tend to wait for a larger gap in front to take a longer or faster step. This behavior led to the formation of stop-and-go waves in the narrow-corridor scenario. The simulation results were consistent with the experimental findings in terms of flow-density relationships and the reproduction of stop-and-go waves. Additionally, synchronized steps were detected in the simulation and quantitatively compared with a publicly available dataset. The HPM offers a new perspective on modeling pedestrian dynamics and emphasizes the necessity of accounting for micro-characteristics at the step level in pedestrian models.

Parameters to characterize the internal recirculation of an oxidation ditch

Mixed liquor circulates ceaselessly in the closed-loop corridor in an oxidation ditch (OD), which is significantly different from other wastewater treatment processes. The internal recirculation ratio (IRR), i.e., the ratio between circulation flow rate (QCC) and influent flow rate (QIn), and the circulatory period (T), i.e. the time consumed for the mixed liquor to complete one lap in the circular corridor, was used to quantify the internal recirculation characteristics of the OD system. In order to elucidate the characteristics and applicability of IRR and T, this study obtained the numerical relationship between IRR and T by formula derivation. It also discusses the factors influencing IRR and analyses the applications of IRR and T. The results showed that IRR = QCC/QIn = HRT/T = HRT ž IRF (HRT = hydraulic retention time of the mixed liquor in the circular corridor; IRF = internal recirculation frequency). Moreover, three kinds of parameters had an effect on IRR: QIn; reactor dimensions, i.e., length (Lmid), width (B), and height (H) of the circular corridor; and horizontal velocity of the mixed liquor in the circular corridor (v). QIn changed IRR by altering HRT. However, B, H, Lmid, and v changed IRR by altering IRF and T. Furthermore, the same IRR corresponded to many different HRT and IRF. Therefore, when QIn and QCC varied in the OD system, using HRT and IRF to evaluate the variation of QIn and QCC, respectively, was better than using IRR to evaluate their synthetical variation. IRF and T were useful for directly and precisely characterizing the circulation speed and circulation flow rate in the circular corridor, while IRR was more useful for evaluating the dilution effect of reflux on influent.

Particular internal recirculation frequency scope for enhancing denitrifying phosphorus removal in an oxidation ditch.

This study investigated the influence of the unique internal recirculation characteristics of an oxidation ditch (OD) system, namely, the internal recirculation frequency (IRF) on denitrifying phosphorus removal (DNPR). The ratios of denitrifying polyphosphate-accumulating organisms (DPAOs) to polyphosphate-accumulating organisms (PAOs) under different IRF conditions were measured using a batch experiment. On this basis, the variation of nutrient transformations was studied using the IRF changes by the mass balance method. The results showed that, for the OD system that had an anaerobic zone upstream from the circular corridor and set anoxic and aerobic zones along the circular corridor, when the IRF was between 3.4 h-1 and 7.5 h-1, the DPAOs/PAOs ratio reached about 50%. Approximately 20% of the total phosphorus (TP) was removed and over 11% of the total nitrogen (TN) was transformed into nitrogen gas by the DNPR process, and meanwhile the total removal efficiencies of the TP and TN were over 93% and 80%. When the IRF was greater than 11.5 h-1, the TN removal efficiency decreased significantly, and this was not conducive to simultaneous nitrogen and phosphorus removal. The results indicated that the OD process would possess a better DNPR potential if the IRF were controlled within the proper scope.

Closed-loop interactions between a shoal of zebrafish and a group of robotic fish in a circular corridor

Collective behavior based on self-organization has been observed in populations of animals from insects to vertebrates. These findings have motivated engineers to investigate approaches to control autonomous multi-robot systems able to reproduce collective animal behaviors, and even to collectively interact with groups of animals. In this article, we show collective decision making by a group of autonomous robots and a group of zebrafish, leading to a shared decision about swimming direction. The robots can also modulate the collective decision-making process in biased and non-biased experimental setups. These results demonstrate the possibility of creating mixed societies of vertebrates and robots in order to study or control animal behavior.

Modeling crowd dynamics through coarse-grained data analysis.

Understanding and predicting the collective behaviour of crowds is essential to improve the efficiency of pedestrian flows in urban areas and minimize the risks of accidents at mass events. We advocate for the development of crowd traffic management systems, whereby observations of crowds can be coupled to fast and reliable models to produce rapid predictions of the crowd movement and eventually help crowd managers choose between tailored optimization strategies. Here, we propose a Bi-directional Macroscopic (BM) model as the core of such a system. Its key input is the fundamental diagram for bi-directional flows, i.e. the relation between the pedestrian fluxes and densities. We design and run a laboratory experiments involving a total of 119 participants walking in opposite directions in a circular corridor and show that the model is able to accurately capture the experimental data in a typical crowd forecasting situation. Finally, we propose a simple segregation strategy for enhancing the traffic efficiency, and use the BM model to determine the conditions under which this strategy would be beneficial. The BM model, therefore, could serve as a building block to develop on the fly prediction of crowd movements and help deploying real-time crowd optimization strategies.

Infiltrating the zebrafish swarm: design, implementation and experimental tests of a miniature robotic fish lure for fish–robot interaction studies

Robotic fish are nowadays developed for various types of research, such as bio-inspiredrobotics, biomimetics and animal behavior studies. In the context of our research on the social interactions of the zebrafish Danio Rerio, we developed a miniature robotic fish lure for direct underwater interaction with the living fish. This remotely controlled and waterproof device has a total length of 7.5 cm with the same size ratio as zebrafish and is able to beat its tail with different frequencies and amplitudes, while following the group of living animals using a mobile robot moving outside water that is coupled with the robotic lure using magnets. The robotic lure is also equipped with a rechargeable battery and can be used autonomously underwater for experiments of up to 1 h. We performed experiments with the robot moving inside an aquarium with living fish to analyze its impact on the zebrafish behavior. We found that the beating rate of the tail increased the attractiveness of the lure among the zebrafish shoal. We also demonstrated that the lure could influence a collective decision of the zebrafish shoal, the swimming direction, when moving with a constant linear speed inside a circular corridor. This new robotic fish design and the experimental results are promising for the field of fish---robot interaction.

Searching for Mobile Intruders in Circular Corridors by Three 1- Searchers

Searching for Mobile Intruders in Circular Corridors by Three 1- Searchers

Immobility time during the forced swimming test predicts sensitivity to amitriptyline, whereas traveled distance in the circular corridor indicates resistance to treatment in female Wistar rats.

Among the main issues in the pharmacological treatment of depression are the wide variation in response to antidepressants among individual patients and the lack of indexes that allow prediction of which drug will be effective in a particular case. We evaluated whether differential sensitivity to amitriptyline is related to dichotomous categorization of individuals on the basis of their behavioral responses to two common paradigms used to evaluate the potential of tricyclic drugs as antidepressants. Hence, we categorized a cohort of 38 female rats on the basis of their immobility time in the conditioning phase of the forced swimming test [FST; high immobility (HI) vs. low immobility (LI) rats] and their locomotor behavior in the circular corridor test [high locomotor response (HR) vs. low locomotor response (LR) rats]. We subjected the rodents to the FST while under the influence of vehicle (n=20) or amitriptyline (15 mg/kg; n=18). We found no statistical evidence of dependence between categorizations of rats on the basis of their behavior in the FST and circular corridor test. Rats categorized as HI/LI and HR/LR significantly differed in their sensitivity/resistance to amitriptyline, as evidenced by changes (or lack thereof) in their immobility time, climbing time, and swimming time during the FST. These results confirm that different behavioral styles among rats are linked to differential sensitivity/resistance to antidepressants. However, we specifically found that categorizing rats as HI/LI better reflected sensitivity to amitriptyline, whereas categorizing them as HR/LR better revealed resistance to the drug. These differential responses should be considered in experimental approaches.

Behavioral and neuroendocrine consequences of juvenile stress combined with adult immobilization in male rats

Exposure to stress during childhood and adolescence increases vulnerability to developing several psychopathologies in adulthood and alters the activity of the hypothalamic-pituitary-adrenal (HPA) axis, the prototypical stress system. Rodent models of juvenile stress appear to support this hypothesis because juvenile stress can result in reduced activity/exploration and enhanced anxiety, although results are not always consistent. Moreover, an in-depth characterization of changes in the HPA axis is lacking. In the present study, the long-lasting effects of juvenile stress on adult behavior and HPA function were evaluated in male rats. The juvenile stress consisted of a combination of stressors (cat odor, forced swim and footshock) during postnatal days 23–28. Juvenile stress reduced the maximum amplitude of the adrenocorticotropic hormone (ACTH) levels (reduced peak at lights off), without affecting the circadian corticosterone rhythm, but other aspects of the HPA function (negative glucocorticoid feedback, responsiveness to further stressors and brain gene expression of corticotrophin-releasing hormone and corticosteroid receptors) remained unaltered. The behavioral effects of juvenile stress itself at adulthood were modest (decreased activity in the circular corridor) with no evidence of enhanced anxiety. Imposition of an acute severe stressor (immobilization on boards, IMO) did not increase anxiety in control animals, as evaluated one week later in the elevated-plus maze (EPM), but it potentiated the acoustic startle response (ASR). However, acute IMO did enhance anxiety in the EPM, in juvenile stressed rats, thereby suggesting that juvenile stress sensitizes rats to the effects of additional stressors.

Evaluation of a Novel Cone Beam Computed Tomography Scanner for Bone Density Examinations in Preoperative 3D Reconstructions and Correlation with Primary Implant Stability

Bone density examination (BDE) using preoperative cone beam computed tomography (CBCT) might be used to predict primary implant stability in implant patients. The aim of the study was to validate a novel CBCT scanner in vitro with regard to BDE in preoperative scans and to analyze the in vivo correlation of CBCT scan results with primary implant stability measurements. A CBCT scanner was validated in vitro with regard to spatial uniformity and linearity of CT numbers (Hounsfield units, HU) by using a series of phantoms and plastic and hydroxyapatite specimens of various densities. Forty-nine patients (27 female and 22 male, mean age 55.6 ± 9.8) were scanned prior to and 1 to 6 months after the placement of 155 dental implants of different lengths and diameters. Mean and peak insertion torque (IT) in Ncm were registered during implant placement. Resonance frequency analysis (RFA) measurements in ISQ units were performed after placement. The second scan was used to export and superimpose the exact positions of bone and implants into the first scan. Virtual probes with the same length as the actual implant were automatically placed at the implant sites, and mean HU values were measured in a 1 mm-wide circular corridor from the tip of the threads and out. The in vitro validation showed high uniformity and linearity of CT numbers (HU). The clinical study showed significant correlations between bone density and ISQ, mean IT, and peak IT, respectively. The WhiteFox CBCT scanner measures bone density with high accuracy. There is a correlation between bone density and primary implant stability as assessed with IT and RFA measurements. The findings suggest that BDE may be used as an additional feature in treatment-planning software to estimate primary stability at predetermined implant sites.

Ecological Aesthetic of Wind Environment about the Circular Earth Building in Fujian, China

Green building has become the trend of urban development in the twenty-first century as the threat of global warming is ever more challenging. The traditional Tulou in Fujian, China, characterized by its distinct building form and local culture is an outstanding representation of ecological building. From the perspective of ecological aesthetic, this research discusses the aesthetic factors of wind environment of Eryi Lou, the largest Tulou in Fujian. Starting from the GIS analysis on the overall environment, also assisted by MapInFo, this research further analyzes the external and internal wind environment of the Eryi Lou through site measurement of the buildings ventilation efficiency. Results showed that building form of Eryi Lou corresponded with topography and landform, as well as life wisdom of symbiosis with the environment and meets the requirements of ecological aesthetics criteria of both local characteristics and national character. The design of the major entrance with Feng Shui-oriented axis, as well as the design of courtyard in the quadrangle, circular corridors, and windows on the forth-storey are all intended for better cross-ventilation and heat dissipation. Such a design is a combination of aesthetics and human-based functional use, proving that Eryi Lou is an ecological building corresponding to the concept of ecological aesthetics, is an exemplar of symbiotic relationship between modern city development and environment.

Searching for mobile intruders in circular corridors by two 1-searchers

We consider the problem of searching for a mobile intruder in a circular corridor by two mobile searchers, who hold one flashlight. A circular corridor is a polygon with one polygonal hole such that its outer and inner boundaries are mutually weakly visible. Both 1-searchers always direct their flashlights at the inner boundary. The objective is to decide whether there exists a search schedule for two 1-searchers to detect the intruder, no matter how fast he moves, and if so, generate a search schedule. We give a characterization of the circular corridors, which are searchable by two 1-searchers. Based on our characterization, an O ( n log n ) time algorithm is then presented to determine the searchability of a circular corridor, where n denotes the total number of vertices of the outer and inner boundaries. Moreover, a search schedule can be reported in time linear in its size, if it exists.

Temperamental traits in mice(II): Consistency across apparatus

The present study examines the consistency across apparatus of murine activity, anxiety and novelty seeking traits. The activity, anxiety and novelty seeking factor scores extracted from the study of Ibáñez et al. (2007) were correlated with several behaviours assessed in tests of activity and anxiety (photocell box and light–dark test; sub-sample 1 = 32) and novelty seeking (circular corridor; sub-sample 2 = 65). The activity factor predicted ambulation behaviour in all the apparatus used; the anxiety factor inversely predicted the time in the light side of the light–dark test, whereas novelty seeking predicted ambulation in the circular corridor. We have described three moderately consistent factors in mice, supporting the proposal that they could be considered to be homologous to the human personality traits activity, anxiety and novelty seeking.

Litter size affects emotionality in adult male rats

The role of natural variations in pre-weaning litter size in rodent adult emotionality and the importance of maternal care as a possible mediating factor have been frequently neglected. To address these issues, maternal behaviour of Sprague–Dawley dams differing in natural number of pups was studied for the first seven postnatal days. Later, adult behaviour of representative male offspring was studied in the elevated plus-maze, the circular corridor, the dark–light box and the forced swimming test. Three groups of offspring were selected in function of the number of littermates: L < 10 group (less than 10 pups per dam), L10–15 (between 10 and 15 pups per dam) and L > 15 group (more than 15 pups per dam). L < 10 litters showed a reduced habituation of activity across time in a circular corridor and as compared to L > 15 litters, L < 10 litters showed a lower activity during the first 5 min of exposure to the circular corridor. L < 10 litters had also higher signs of anxiety in the elevated plus-maze, in comparison to the other two groups. In addition, L < 10 litters showed in the forced swimming test reduced struggling and more mild swimming behavior than the other two groups. These abnormalities in L < 10 litters are not explained by maternal behavior since they received individually more maternal care than L > 15, as assessed by total licking-grooming observed during the whole observation period divided by number of pups. Although previous data from several laboratories have demonstrated that low maternal care is associated with heightened emotionality at adulthood, the present results suggest an important contribution of spontaneous litter size to adult emotional behavior that cannot be explained by concomitant changes in maternal care.

Relationship between impulsivity, hyperactivity and working memory: a differential analysis in the rat

BackgroundImpulsivity is a behavioural trait that comprises several distinct processes. It is a key feature of many psychopathologies such as mania, addictive disorders or attention deficit-hyperactivity disorders. To date, the aspects of impulsiveness involved in these pathologies have not yet been explicitly defined. In these disorders, sensation or drug seeking and cognitive deficits are closely related, but the nature of these relationships remains largely unknown. A new animal model of impulsiveness based on spontaneous inter-individual differences is proposed here to help clarify the relationship between characteristic aspects of impulsive-related pathologies.MethodsRats were divided into sub-groups according to their scores in three operant tasks with varying degrees of behavioural inhibition, timing and motor vs. cognitive impulsivity demands. These tasks included a fixed consecutive number schedule (ability to complete an action to receive a reinforcer), a multiple fixed-interval/extinction schedule of reinforcement (high level of responding), and a delayed reward task (delay discounting). In addition, measurements of locomotor responses to novelty and to amphetamine in a circular corridor, and working memory in an 8-arm radial maze were obtained.ResultsSubstantial behavioural inter-individual differences were observed in each task, whereas few inter-task relationships were found. Impulsive rats, as defined in a task requiring inhibition of premature responses, presented a higher increase in amphetamine-induced locomotion. Reduced working memory performance was only observed in hyperactive rats in an extinction schedule.ConclusionThis novel approach shows that distinct aspects of impulsiveness and hyperactivity can be expressed based on large inter-individual differences that vary from poorly to highly adapted behaviours ones in a normal population of rats. Inhibitory deficit was related to a higher response to psychostimulants a characteristic of rats predisposed to amphetamine self-administration and related to higher limbic dopaminergic activity, whereas working memory capacity was only related to hyperactivity. This approach allows for the identification of particular individuals presenting distinct behavioural characteristics of impulsive-related psychopathologies. These individuals may be of great interest in the modelling of these disorders and the exploration of their neurobiological bases.

Influence of reactivity to novelty and anxiety on hypothalamic–pituitary–adrenal and prolactin responses to two different novel environments in adult male rats

Since stressor-induced activation of the hypothalamic–pituitary–adrenal (HPA) axis is involved in some stress-related pathologies, much attention has been paid in laboratory animals to the study of the relationship between endocrine, particularly HPA, responsiveness to stressors and other individual characteristics, such as reactivity to novelty and fear/anxiety. In the present study, adult male rats were classified as high or low reactive to novelty (HR versus LR), as a function of the horizontal activity displayed during 30 min in a circular corridor, and as high or low anxiety (HA versus LA) as a function of the time spent in the open arms of the elevated plus-maze. Then, the behavioural and hormonal response to two distinct novel environments (the hole-board and the light–dark) was assessed in the same subjects, using a counterbalanced design. Plasma prolactin, ACTH and corticosterone responses to the hole-board were higher than to the light–dark, a good correlation between the two tests being found for each hormone. Whereas the hormonal response to the novel environments was not affected by anxiety, HR rats showed a consistently higher HPA response than LR rats when the criteria to classify the animals were the activity during the first 15 min in the circular corridor, but not when the activity during the second 15 min was considered. Neither trait affected prolactin response. The present results demonstrate a good within-individual consistency of the endocrine response to novel environments and support the hypothesis of a higher HPA response to stressors for HR versus LR rats. In contrast, no contribution of fear/anxiety to endocrine responsiveness was observed.

Perseverance of exploration in novel environments predicts morphine place conditioning in rats

Reactivity to novelty has been related to operant drug self-administration but does not seem involved in the conditioned place preference (CPP). To further assess this issue our aims were to investigate: (1) the importance of the initial versus delayed activity in the novel environment to predict the CPP induced by morphine; (2) the separate contribution of trait anxiety in morphine CPP. Male Sprague–Dawley rats were exposed to a circular corridor for 30 min to assess reactivity to novelty and to the elevated plus-maze and the light–dark tests as measures of anxiety and morphine CPP was then studied (three pairings with 5 mg/kg s.c. morphine and three with saline). Delayed activity in the corridor (16–30 min) correlated positively with CPP score, whereas the initial activity (0–15 min) did not. High-responders (HR), those more active during the second half of the corridor, developed morphine CPP in contrast to low-responders (LR). Also, HR and LR did not differ in anxiety nor any plus-maze or light–dark test measure correlated with CPP behaviour. Enhanced vulnerability to develop morphine CPP is predicted by a higher delayed activity in a novel environment, regardless of anxiety.

Hippocampus and remote spatial memory in rats

Damage to the hippocampus typically produces temporally graded retrograde amnesia, whereby memories acquired recently are impaired more than memories acquired remotely. This phenomenon has been demonstrated repeatedly in a variety of species and tasks. It has also figured prominently in theoretical treatments of memory and hippocampal function. Yet temporally graded retrograde amnesia has not been demonstrated following hippocampal damage in spatial tasks like the water maze. We have assessed recent and remote spatial memory following hippocampal lesions in three different tests of spatial memory: (1) the standard water maze; (2) the Oasis maze, a dry-land version of the water maze; and (3) the annular water maze, where training and testing occur within a circular corridor. Training protocols were developed for each task such that retention of spatial memory could be expressed after very long retention intervals. In addition, retention in each task was assessed with single probe trials so that the assessment of remote memory did not depend on the ability to relearn across multiple trials. The findings were consistent across the three tasks. In the standard water maze (Experiment 1), spatial memory was impaired after training-surgery intervals of 1 day, 8 weeks, or 14 weeks. Similarly, in the Oasis maze (Experiment 2), spatial memory was impaired after training-surgery intervals of 1 day and 9 weeks. Finally, in the annular water maze (Experiment 3), spatial memory was impaired after training-surgery intervals of 9 weeks and 14 weeks. Dorsal hippocampal lesions impaired performance to the same extent as complete lesions. The impairment in remote spatial memory could reflect disruption of previously acquired spatial information. Alternatively, it is possible that in these tasks hippocampal lesions might produce an impairment in performance that prevents the expression of an otherwise intact spatial memory.

Responsiveness of the hypothalamic–pituitary–adrenal axis to different novel environments is a consistent individual trait in adult male outbred rats

Susceptibility to some stress-induced pathologies may be strongly related to individual differences in the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis to stressors. However, there have been few attempts in rodents to study the reliability of the individual differences in the responsiveness of the HPA to stressors and the relationship to resting corticosterone levels. In the present work, we used a normal population of Sprague-Dawley rats, with a within-subject design. Our objectives were to study: (a) the reliability of the ACTH and corticosterone response to three different novel environments widely used in psychopharmacology and (b) the relationship between stress levels of HPA hormones and the daily pattern of corticosterone secretion (six samples over a 24-h-period). Animals were repeatedly sampled using tail-nick procedure. The novel environments were the elevated plus-maze, the hole-board and the circular corridor. Animals were sampled just after 15 min exposure to the tests and again at 15 and 30 min after the termination of exposure to them (post-tests). The hormonal levels just after the tests indicate that the hole-board seems to be more stressful than the circular corridor and the elevated plus-maze, the latter being characterized by the lowest defecation rate. Correlational analysis revealed that daily pattern of resting plasma corticosterone levels did not correlate to HPA responsiveness to the tests, suggesting no relationship between resting and stress levels of HPA hormones. In contrast, the present study demonstrates, for the first time, a good within-subject reliability of the ACTH and corticosterone responses to the three environments, suggesting that HPA responsiveness to these kind of stressors is a consistent individual trait in adult rats, despite differences in the physical characteristics of the novel environments.

Long-term effects of a single exposure to stress in adult rats on behavior and hypothalamic–pituitary–adrenal responsiveness: comparison of two outbred rat strains

We have previously observed that a single exposure to immobilization (IMO), a severe stressor, caused long-term (days to weeks) desensitization of the response of the hypothalamic–pituitary–adrenal (HPA) axis to the homotypic stressor, with no changes in behavioral reactivity to novel environments. In contrast, other laboratories have reported that a single exposure to footshock induced a long-term sensitization of both HPA and behavioral responses to novel environments. To test whether these apparent discrepancies can be explained by the use of different stressors or different strains of rats, we studied in the present work the long-term effects of a single exposure to two different stressors (footshock or IMO) in two different strains of rats (Sprague–Dawley from Iffa-Credo and Wistar rats from Harlan). We found that both strains showed desensitization of the HPA response to the same (homotypic) stressor after a previous exposure to either shock or IMO. The long-term effects were higher after IMO than shock. No major changes in behavior in two novel environments (circular corridor, CC and elevated plus-maze, EPM) were observed after a single exposure to shock or IMO in neither strain, despite the fact that shocked rats showed a conditioned freezing response to the shock boxes. The present results demonstrate that long-term stress-induced desensitization of the HPA axis is a reliable phenomenon that can be observed with different stressors and strains. However, only behavioral changes related to shock-induced conditioned fear were found, which suggests that so far poorly characterized factors are determining the long-term behavioral consequences of a single exposure to stress.