A high-density crowd state judgment model based on entropy theory

A high-density crowd state is prone to cause large-scale crowd stampede accidents that seriously threaten the people’s security and property. The key to preventing crowd congestion is to accurately predict the location and time of crowd events, particularly when there is a high density of people. In this paper, the entropy theory is used to characterize the state of a crowded system. The theoretical entropy S_r and the actual entropy S of the crowd system are obtained according to the area occupied by the different crowd state The maximum entropy value and the actual entropy value under different conditions of the system are compared to judge the state of crowded extent. The results show that the model is practical and effective. According to the situation of the crowd, different management and evacuation measures are considered to prevent the occurrence of crowd accidents.

Lost in the crowd: Imagining walking in synchrony with a crowd increases affiliation and deindividuation

Moving in time with others-interpersonal coordination-increases affiliation, helping behaviours and gives rise to a host of other prosocial outcomes. Recent research suggests that merely imagining coordination may lead to similar social effects. In the present study, participants were asked to imagine walking with a crowd in a coordinated (versus uncoordinated) way to explore the effects of imagined coordination on individuals' perceptions of themselves and the crowd. Imagined coordination led to greater levels of deindividuation and affiliation. That is, participants were less likely to report seeing themselves as unique individuals, instead viewing themselves as a part of a group (deindividuation) and more likely to report a sense of emotional closeness (affiliation) with the imagined group. Deindividuation partially mediated the effect of imagined coordination on affiliation. This work establishes that imagined synchrony can be employed online to foster prosocial attitudes towards groups of people, and that a process of deindividuation might mediate this effect.

The Discharge Lounge: A Patient Flow Process Solution

BACKGROUND

Patient flow, from emergency department admission through to discharge, influences hospital overcrowding. We aimed to improve patient flow by increasing discharge lounge (DL) usage.

LOCAL PROBLEM

Patients need to receive a continuum of nursing care to encourage compliance with follow-up care after discharge from the acute care setting.

METHODS

Baseline data revealed inefficient use of the DL. We targeted the medical-surgical unit with the lowest DL use and trialed interventions over sequential Plan-Do-Study-Act cycles.

INTERVENTIONS

After surveying the nursing staff, we assessed the influence of 3 interventions on DL usage: educating staff on patient eligibility, engaging a recruitment scout, and displaying a visual cue notifying staff when a patient's discharge order was written.

RESULTS

The unit's average DL use increased from 18% to 36%, while hospital overcrowding and discharge turnaround time decreased.

CONCLUSION

The DL is an effective tool to improve patient flow and decrease hospital overcrowding.

Stress Impairs Skin Barrier Function and Induces α2-3 Linked N-Acetylneuraminic Acid and Core 1 O-Glycans on Skin Mucins in Atlantic Salmon, Salmo salar

The skin barrier consists of mucus, primarily comprising highly glycosylated mucins, and the epithelium. Host mucin glycosylation governs interactions with pathogens and stress is associated with impaired epithelial barrier function. We characterized Atlantic salmon skin barrier function during chronic stress (high density) and mucin O-glycosylation changes in response to acute and chronic stress. Fish held at low (LD: 14–30 kg/m³) and high densities (HD: 50-80 kg/m³) were subjected to acute stress 24 h before sampling at 17 and 21 weeks after start of the experiment. Blood parameters indicated primary and secondary stress responses at both sampling points. At the second sampling, skin barrier function towards molecules was reduced in the HD compared to the LD group (P_app mannitol; p < 0.01). Liquid chromatography–mass spectrometry revealed 81 O-glycan structures from the skin. Fish subjected to both chronic and acute stress had an increased proportion of large O-glycan structures. Overall, four of the O-glycan changes have potential as indicators of stress, especially for the combined chronic and acute stress. Stress thus impairs skin barrier function and induces glycosylation changes, which have potential to both affect interactions with pathogens and serve as stress indicators.

Enforcement may crowd out voluntary support for COVID-19 policies, especially where trust in government is weak and in a liberal society

Effective states govern by some combination of enforcement and voluntary compliance. To contain the COVID-19 pandemic, a critical decision is the extent to which policy makers rely on voluntary as opposed to enforced compliance, and nations vary along this dimension. While enforcement may secure higher compliance, there is experimental and other evidence that it may also crowd out voluntary motivation. How does enforcement affect citizens' support for anti-COVID-19 policies? A survey conducted with 4,799 respondents toward the end of the first lockdown in Germany suggests that a substantial share of the population will support measures more under voluntary than under enforced implementation. Negative responses to enforcement-termed control aversion-vary across the nature of the policy intervention (e.g., they are rare for masks and frequent for vaccination and a cell-phone tracing app). Control aversion is less common among those with greater trust in the government and the information it provides, and among those who were brought up under the coercive regime of East Germany. Taking account of the likely effectiveness of enforcement and the extent to which near-universal compliance is crucial, the differing degrees of opposition to enforcement across policies suggest that for some anti-COVID-19 policies an enforced mandate would be unwise, while for others it would be essential. Similar reasoning may also be relevant for policies to address future pandemics and other societal challenges like climate change.

High housing density increases stress hormone- or disease-associated fecal microbiota in male Brandt's voles (Lasiopodomys brandtii)

Density-dependence is an important mechanism in the population regulation of small mammals. Stressors induced by high-density (e.g., crowding and aggression) can cause physiological and neurological disorders, and are hypothesized to be associated with alterations in gut microbiota, which may in turn reduce the fitness of animals by increasing stress- or disease-associated microbes. In this study, we examined the effects of housing density on the hormone levels, immunity, and composition of gut microbiota in male Brandt's voles (Lasiopodomys brandtii) by conducting two specific housing density experiments with or without physical contact between voles. Voles in high density groups exhibited higher serum corticosterone (CORT), serotonin (5-HT), and immunoglobulin G (IgG) levels, as well as higher testosterone (T) levels only in the experiment with physical contact. Meanwhile, high-density treatments induced significant changes in the composition of gut microbiota by increasing disease-associated microbes. The levels of hormones and immunity (i.e., CORT, 5-HT, and IgG) elevated by the high density treatment were significantly correlated with some specific microbes. These results imply that high-density-induced stress may shape the fitness of animals under natural conditions by altering their gut microbiota. Our study provides novel insights into the potential roles of gut microbiota in the density-dependent population regulation of small rodents as well as the potential mechanisms underlying psychological disorders in humans and animals under crowded conditions.

Challenges to pooling models of crowding: Implications for visual mechanisms

A set of phenomena known as crowding reveal peripheral vision's vulnerability in the face of clutter. Crowding is important both because of its ubiquity, making it relevant for many real-world tasks and stimuli, and because of the window it provides onto mechanisms of visual processing. Here we focus on models of the underlying mechanisms. This review centers on a popular class of models known as pooling models, as well as the phenomenology that appears to challenge a pooling account. Using a candidate high-dimensional pooling model, we gain intuitions about whether a pooling model suffices and reexamine the logic behind the pooling challenges. We show that pooling mechanisms can yield substitution phenomena and therefore predict better performance judging the properties of a set versus a particular item. Pooling models can also exhibit some similarity effects without requiring mechanisms that pool at multiple levels of processing, and without constraining pooling to a particular perceptual group. Moreover, we argue that other similarity effects may in part be due to noncrowding influences like cuing. Unlike low-dimensional straw-man pooling models, high-dimensional pooling preserves rich information about the stimulus, which may be sufficient to support high-level processing. To gain insights into the implications for pooling mechanisms, one needs a candidate high-dimensional pooling model and cannot rely on intuitions from low-dimensional models. Furthermore, to uncover the mechanisms of crowding, experiments need to separate encoding from decision effects. While future work must quantitatively examine all of the challenges to a high-dimensional pooling account, insights from a candidate model allow us to conclude that a high-dimensional pooling mechanism remains viable as a model of the loss of information leading to crowding.

How psychology might alleviate violence in queues: Perceived future wait and perceived load moderate violence against service providers

INTRODUCTION

Queues are inherent to service encounters, as it is not always possible to provide service to all clients at the exact moment they request service. Queues involve waiting for a service in a specific place that might also be crowded, they obstruct the client's' goal of receiving service, and at times lead clients to mistreat service providers and in extreme cases even attack them violently. We show, in a hospital setting, that perceived predicted future wait and load can buffer the causes of violence towards service staff.

METHODS

We combine objective data on crowdedness, reports of violence, and durations of time people waited, with psychological measures of perceived load and perceived future wait, collected from 226 people in the Emergency Department (ED) of a large hospital. Visitors to the ED were recruited as they waited for service. They indicated their perceived load in the ED and their perceived remaining wait for service. This data was then triangulated with objective operational data regarding the actual number of people waiting for service (i.e., crowdedness) and objective data regarding staff calls to security to stop violent accounts.

RESULTS

We find that with increased crowdedness, there are more calls to security reporting violence. However, this relationship is moderated by two factors: when people perceive the future wait to be short and when they perceive the load on the system to be high. Moreover, a three-way interaction shows that crowdedness is associated with more incidents of violence, however high perceived load and low perceived future wait are associated with fewer violent incidents.

CONCLUSIONS

This paper demonstrates the relationship between crowded queues and violence towards service staff, and suggests two psychological mechanisms for buffering such violence: reducing perceived future wait and elevating perceived load.

Social network changes during space restriction in zoo chimpanzees

Several studies across anthropoid species have demonstrated how primates respond to the increased risk of conflict during space restriction with various behavioral strategies. Three strategies have been proposed relating to tension regulation, conflict avoidance, and inhibition. Prior research supporting these strategies has focused on individual- and dyadic-level analyses, yet group-living animals live within a web of inter-individual connections. Here, for the first time, we used a network approach to investigate how social structure and individuals' connectedness change during space restriction. We collected grooming and aggression data during a 6-week control period and a 5-week period of space restriction in a large group of zoo chimpanzees. We compared network density and individual centrality measures (degree, eigenvector, and betweenness centrality) between these two periods using permutation tests. The density of the unidirectional grooming network was significantly lower during space restriction, indicating fewer grooming partners and a less cohesive network. This was mainly due to a reduction in females' grooming partners (degree) and an increase in females' betweenness centrality. We found no differences in the mutual grooming or aggression networks. Our findings are consistent with a conflict avoidance strategy and complement previous findings from the same dataset based on individual behavioral rates that supported a selective inhibition strategy. The results highlight the dynamic nature of social structure and its inherent flexibility to respond effectively to short-term changes in the environment.

Identifying bottlenecks and designing ideas and solutions for improving aircraft passengers' experience during boarding and disembarking

Interferences during the boarding procedure are one of the main reasons of delay and increased turnaround time, becoming a relevant problem for airlines. Observations of the boarding process and questionnaires inside the aircraft revealed three main bottlenecks during the boarding process: (1) Hand luggage: Storage space is not sufficient and/or not used efficiently; (2) Preparation: Passengers are not well prepared for the boarding process; and (3) Communication: Audio announcements are unclear and unfocused. By translating these bottlenecks as possibilities for improvement, solutions were designed for the airport and aircraft interiors to reduce boarding time and improve the passenger boarding experience. Concepts ranged from an app to scan your hand luggage at home and make a reservation for overhead bin space; to a redesigned waiting area to help passengers prepare for boarding; to new boarding methods and redesigned aircraft seats. In this paper, several design concepts are presented in more detail.

Beyond Bouma's window: How to explain global aspects of crowding?

In crowding, perception of an object deteriorates in the presence of nearby elements. Although crowding is a ubiquitous phenomenon, since elements are rarely seen in isolation, to date there exists no consensus on how to model it. Previous experiments showed that the global configuration of the entire stimulus must be taken into account. These findings rule out simple pooling or substitution models and favor models sensitive to global spatial aspects. In order to investigate how to incorporate global aspects into models, we tested a large number of models with a database of forty stimuli tailored for the global aspects of crowding. Our results show that incorporating grouping like components strongly improves model performance.

Risk and protective factors for mental health at a youth mass gathering

BACKGROUND

Mass gatherings are well-documented for their public health risks; however, little research has examined their impact on mental health or focused on young people specifically. This study explores risk and protective factors for mental health at mass gatherings, with a particular focus on characterising attendees with high levels of psychological distress and risk taking.

METHOD

Data collection was conducted in situ at "Schoolies", an annual informal week-long mass gathering of approximately 30,000 Australian school leavers. Participants were 812 attendees of Schoolies on the Gold Coast in 2015 or 2016 (74% aged 17 years old).

RESULTS

In both years, attendee mental health was found to be significantly better than population norms for their age peers. Identification with the mass gathering predicted better mental health, and this relationship became stronger across the course of the mass gathering. Attendees with high levels of psychological distress were more likely to be male, socially isolated, impulsive, and in a friendship group where risk taking was normative.

CONCLUSIONS

Mass gatherings may have a net benefit for attendee mental health, especially for those attendees who are subjectively committed to the event. However, a vulnerable subgroup of attendees requires targeted mental health support.

A universal function for capacity of bidirectional pedestrian streams: Filling the gaps in the literature

In this work, we investigate properties of bidirectional pedestrian streams by studying different experimental datasets from multiple authors. Through the comparison of a scenario where lanes naturally form with two others where lane formation is either obstructed or facilitated, we show the relationship of different pedestrian quantities in regard to the flow ratio (or directional split). On this scope, two measures to account for the degree of congestion and self-organization are introduced. The analysis of the results reveals that the balanced case (where flow is almost equal in both directions) has very peculiar properties which depends on the existence or not of organized lanes and their stability. While the balanced case generally shows the highest level of congestion, this property can quickly change after lanes are formed and when they remain stable. An in-depth investigation revealed that capacity in bidirectional streams is characterized by a dual nature: conflicts with the counter flow and self-organization in lanes. Both aspects have been described using a mathematical model which allowed to define a function for capacity in relation with flow ratio and environmental/cognitive aspects. The expression for capacity proposed in our work agrees with several studies from the literature, eventually allowing to understand the differences among them. We believe our function for capacity enables a more universal treatment of bidirectional streams compared to previous definitions, since it allows to account for steady and non-steady state conditions which represent important mechanisms in their dynamics. The framework introduced here may also help measuring the influence of environmental/cognitive changes in relation with the capacity of bidirectional pedestrian streams.

Does a Provider in Triage and Rapid Medical Evaluation Help With Left Without Being Seen Rates and ED Crowding?

INTRODUCTION

Attempting to reduce ED crowding, the ED team at a rural academic medical center and specialty hospital implemented rapid medical evaluation (RME) with and without a provider in triage (PIT). The purpose of this performance improvement project was to explore how these interventions affected crowding metrics of door-to-disposition time, ED length of stay (LOS), and left without being seen (LWBS) rates for all patients.

METHODS

Using a prospective 2-group design, the pre-RME population served as the historical control group, and postintervention groups included both RME with and without PIT. Group comparisons of crowding metrics included pre- and post-RME with and without PIT.

RESULTS

There were no statistically significant differences in any of the crowding metrics for the emergency severity index (ESI) 3 groups pre- or post-RME. However, mean door-to-disposition times for the post-RME ESI 5 population were shorter compared with the pre-RME ESI 5 patients (2:59:23 vs. 2:00: 42; P = 0.037). Analysis of the post-RME population with and without PIT did not demonstrate significant differences across ESI 3 or 5 groups. Comparisons of post-RME data revealed a significant increase in ED LOS for all admitted patients regardless of their ESI (P = 0.023) and also door-to-disposition times for ESI level-4 patient groups, both with and without PIT (P = 0.022).

IMPLICATIONS FOR PRACTICE

The findings support other studies demonstrating that RME can have positive impact on ED crowding metrics for some patients. Although PIT took longer for some patients, anecdotal findings revealed benefits related to direct discharges and admission occurring during the RME process.

Effects of congestion on drivers' speed choice: Assessing the mediating role of state aggressiveness based on taxi floating car data

Inappropriate cruising speed, such as speeding, is one of the major contributors to the road safety, which increases both the quantitative number and severity of traffic accidents. Previous studies have indicated that traffic congestion is one of the primary causes of drivers' frustration and aggression, which may lead to inappropriate speed choice. In this study, the large taxi floating car data (FCD) was used to empirically evaluate how traffic congestion-related negative moods, defined as state aggressiveness, affected drivers' speed choice. The indirect effect of traffic delay on the cruising speed adjustment through the state aggressiveness was assessed through the mediation analysis. Furthermore, the moderated mediation analysis was performed to explore the effect of driver type, value of time, and working duration on the mediation role of state aggressiveness. The results proved that the state aggressiveness was the mediator of the relationship between travel delays and driving speed adjustment, and the mediation role was different across various driver types. As compared to the aggressive drivers, the normal drivers and the steady drivers tended to behave more aggressively after experiencing non-recurrent congestion during the early stage of the trips. When the value of time was high, steady drivers were more likely to adjust their speed choice although the effect was not statistically significant for other driver types. The validation results indicated that the speed model incorporating state aggressiveness could better predict the travel time than the traditional speed model that only considering the specific expected speed distribution. The prediction results for the manifest indicators of state aggressiveness, such as the maximum speed and the speed deviation, also demonstrated a reasonable reflection of the field data.

Professional resilience among nurses working in an overcrowded emergency department in Taiwan

PURPOSE

Professional resilience has become increasingly important for nurses in adverse work environments to reduce the negative results and increase the positive outcomes of stress. This study aimed to explore and understand the experiences of resilience among nurses in an overcrowded emergency department (ED) and increase knowledge about what nurses identified as protective factors, which may be useful for future planning.

METHODS

A construction-grounded theory (CGT) approach was adopted. Purposive sampling and snowball technique were employed to recruit 13 participants, which proved sufficient to achieve theoretical saturation. In-depth interviews were conducted and audiotaped.

RESULTS

Doubting work value and maintaining optimism were the 2 main themes in the core category of seeing and taking work difficulty and responsibility. Nurses described how their passion for their profession gradually diminished, but they assessed the situation and took responsibility for their jobs.

CONCLUSION

This study found that nurses retain their compassion, which sustains them in their work. The issue of ED overcrowding led to pessimism among nurses. However, work rewards encouraged nurses to adopt a more proactive attitude toward work-related adversity.

Factors influencing experience in crowds - The organiser perspective

Crowds are a commonplace encounter but the experience for participants can be highly variable. Crowds are complex sociotechnical phenomenon, affected by many interacting factors. Little is known, however, about how those responsible for organising crowd situations approach their responsibilities. This study conducted semi-structured interviews (n = 41) with organisers responsible for different aspects of the design, planning, management and operations of events and other crowd situations. The objective was to understand organisers' priorities, along with the consideration given to the experience of crowd participants. The interviews revealed that organisers generally prioritised finance, security and health and safety aspects, whilst giving limited explicit attention to other important factors that affect participant experience. Organisers tended to approach their planning and decisions on the basis of their own experience and judgement, without accessing training or reference to guidance. It is suggested that the non-use of guidance is in part due to problems with the guidance currently available, both its content and its form. The organisers of infrequent or small-scale events have the greatest knowledge and experience gap. It is concluded that in order to achieve a consistent, high quality experience for crowd participants, there needs to be improved understanding among organisers of the complexity of crowds and the multiple factors influencing participant experience. Guidance and tools need to be usable and tailored to organisers' requirements. Organisers of infrequent or small-scale events are especially in need of support.

Association of Overcrowding and Turnover with Self-Harm in a Swiss Pre-Trial Prison

Self-harm is a common issue in detention and includes both suicidal and non-suicidal behaviours. Beyond well-known individual risk factors, institutional factors such as overcrowding (i.e., when the prison population exceeds its capacity) and turnover (i.e., the rate at which the prison population is renewed), may also increase the risk of self-harm. However, these factors are understudied or previous studies reported inconsistent findings. This study investigated the association of self-harm with overcrowding and turnover in the largest pre-trial Swiss prison in Geneva. Data were collected yearly between 2011 and 2017. Measures included self-harm (all kinds of self-injuring acts requiring medical attention, including self-strangulations and self-hangings). We performed meta-regressions to analyse the relationships between self-harm and institutional factors. Self-harm events were frequent, with a prevalence estimate of 26.4%. Overcrowding and turnover were high (average occupation rate of 177% and average turnover of 73%, respectively). Overcrowding and turnover were significantly associated with self-harm (respectively b = 0.068, p < 0.001 and (b = 1.257, p < 0.001). In both cases, self-harm was higher when overcrowding and turnover increased. Overcrowding and turnover raise important human rights concerns and have damaging effects on the health of people living in detention. Identification of and care for this vulnerable population at risk of self-harm are needed and institutional factors should be addressed.

Collective movements of pedestrians: How we can learn from simple experiments with non-human (ant) crowds

Introduction

Understanding collective behavior of moving organisms and how interactions between individuals govern their collective motion has triggered a growing number of studies. Similarities have been observed between the scale-free behavioral aspects of various systems (i.e. groups of fish, ants, and mammals). Investigation of such connections between the collective motion of non-human organisms and that of humans however, has been relatively scarce. The problem demands for particular attention in the context of emergency escape motion for which innovative experimentation with panicking ants has been recently employed as a relatively inexpensive and non-invasive approach. However, little empirical evidence has been provided as to the relevance and reliability of this approach as a model of human behaviour.

Methods

This study explores pioneer experiments of emergency escape to tackle this question and to connect two forms of experimental observations that investigate the collective movement at macroscopic level. A large number of experiments with human and panicking ants are conducted representing the escape behavior of these systems in crowded spaces. The experiments share similar architectural structures in which two streams of crowd flow merge with one another. Measures such as discharge flow rates and the probability distribution of passage headways are extracted and compared between the two systems.

Findings

Our findings displayed an unexpected degree of similarity between the collective patterns emerged from both observation types, particularly based on aggregate measures. Experiments with ants and humans commonly indicated how significantly the efficiency of motion and the rate of discharge depend on the architectural design of the movement environment.

Practical applications

Our findings contribute to the accumulation of evidence needed to identify the boarders of applicability of experimentation with crowds of non-human entities as models of human collective motion as well as the level of measurements (i.e. macroscopic or microscopic) and the type of contexts at which reliable inferences can be drawn. This particularly has implications in the context of experimenting evacuation behaviour for which recruiting human subjects may face ethical restrictions. The findings, at minimum, offer promise as to the potential benefit of piloting such experiments with non-human crowds, thereby forming better-informed hypotheses.

Collective phenomena in crowds-Where pedestrian dynamics need social psychology

This article is on collective phenomena in pedestrian dynamics during the assembling and dispersal of gatherings. To date pedestrian dynamics have been primarily studied in the natural and engineering sciences. Pedestrians are analyzed and modeled as driven particles revealing self-organizing phenomena and complex transport characteristics. However, pedestrians in crowds also behave as living beings according to stimulus-response mechanisms or act as human subjects on the basis of social norms, social identities or strategies. To show where pedestrian dynamics need social psychology in addition to the natural sciences we propose the application of three categories-phenomena, behavior and action. They permit a clear discrimination between situations in which minimal models from the natural sciences are appropriate and those in which sociological and psychological concepts are needed. To demonstrate the necessity of this framework, an experiment in which a large group of people (n = 270) enters a concert hall through two different spatial barrier structures is analyzed. These two structures correspond to everyday situations such as boarding trains and access to immigration desks. Methods from the natural and social sciences are applied. Firstly, physical measurements show the influence of the spatial structure on the dynamics of the entrance procedure. Density, waiting time and speed of progress show large variations. Secondly, a questionnaire study (n = 60) reveals how people perceive and evaluate these entrance situations. Markedly different expectations, social norms and strategies are associated with the two spatial structures. The results from the questionnaire study do not always conform to objective physical measures, indicating the limitations of models which are based on objective physical measures alone and which neglect subjective perspectives.

Factors influencing experience in crowds - The participant perspective

Humans encounter crowd situations on a daily basis, resulting in both negative and positive experiences. Understanding how to optimise the participant experience of crowds is important. In the study presented in this paper, 5 focus groups were conducted (35 participants, age range: 21-71 years) and 55 crowd situations observed (e.g. transport hubs, sport events, retail situations). Influences on participant experience in crowds identified by the focus groups and observations included: physical design of crowd space and facilities (layout, queuing strategies), crowd movement (monitoring capacity, pedestrian flow), communication and information (signage, wayfinding), comfort and welfare (provision of facilities, environmental comfort), and public order. It was found that important aspects affecting participant experience are often not considered systematically in the planning of events or crowd situations. The findings point to human factors aspects of crowds being overlooked, with the experiences of participants often poor.

An ecological analysis of prison overcrowding and suicide rates in England and Wales, 2000-2014

Prisoners are at a greatly increased risk of suicides compared to the general population. Differences in suicide risk can be partly explained by individual risk factors, but the contribution of prison characteristics remains unclear. Overcrowded prisons have higher suicide rates, but this may be related to prison function, security level, population size and turnover. The aim of the current study was to investigate the contribution of each of these prison characteristics to suicide rates, using data from the Ministry of Justice for adult prisons in England and Wales from 2000 to 2014. Negative binomial regression analysis showed that larger population size, higher turnover, higher security and public management were associated with higher suicide rates. When controlling for these factors, overcrowding was not found to be related to suicide rates. Questions remain about the causal mechanisms underlying variation in prison suicides and the impact of the lived experience of overcrowding. Further research is needed to examine the relative contribution of prison and prisoner characteristics to suicides.

Biological sensitivity to context: Cortisol awakening response moderates the effects of neighbourhood density on the development of adolescent externalizing problem behaviours

This four-year longitudinal study attempted to test person-environment interaction theory and biological sensitivity theory by assessing whether individuals' biological stress activity CARAUCg (Cortisol Awakening Response Area Under the Curve with respect to ground) moderates the effects of neighbourhood density on the development of adolescent externalizing problem behaviours. Participants were 358 Dutch adolescents with a mean age of 15 years at the first measurement. Our analyses showed that CARAUCg moderated the effects of neighbourhood density on the level of parent-reported delinquency and aggression and adolescent self-reported delinquency. More specifically, for adolescents with high CARAUCg, higher neighbourhood density significantly predicted higher levels of parent-reported and adolescent self-reported delinquency and aggression, whereas the association was reversed or non-significant for adolescents with low CARAUCg. Our findings suggest that adolescents with different levels of CARAUCg respond differentially to the density of the neighbourhood they live in, supporting for person-environment interaction perspectives and biological sensitivity theory.

A longitudinal investigation of the relationship between crowding and reading: A neurodegenerative approach

We have previously documented two patients (FOL and CLA) with posterior cortical atrophy who achieved accurate and rapid reading despite deficits in ten measures of visual processing, with two notable exceptions: (1) a measure of visual acuity, (2) a measure of visual crowding. Subsequent longitudinal investigation of these patients was carried out, involving annual tests of early visual, visuoperceptual and visuospatial processing and assessment of reading ability. Follow-up assessments identified the evolution of a particular early visual processing deficit, excessive visual crowding; this deficit has been previously implicated in forms of dyslexia. Consistent with the link between crowding and reading dysfunction, follow-up assessments also revealed deterioration in both patients' reading ability. The current findings demonstrate a neurodegenerative approach towards understanding the relationship between visual crowding and the reading system, and suggest possible mechanisms for how excessive crowding may disrupt word recognition.

Neuroprotective Role of L-NG-Nitroarginine Methyl Ester (L-NAME) against Chronic Hypobaric Hypoxia with Crowding Stress (CHC) Induced Depression-Like Behaviour

Improper neuroimmune responses following chronic stress exposure have been reported to cause neuronal dysfunctions leading to memory impairment, anxiety and depression like behaviours. Though several factors affecting microglial activation and consequent alteration in neuro-inflammatory responses have been well studied, role of NO and its association with microglia in stress induced depression model is yet to be explored. In the present study, we validated combination of chronic hypobaric hypoxia and crowding (CHC) as a stress model for depression and investigated the role of chronic stress induced elevated nitric oxide (NO) level in microglia activation and its effect on neuro-inflammatory responses in brain. Further, we evaluated the ameliorative effect of L-NG-Nitroarginine Methyl Ester (L-NAME) to reverse the stress induced depressive mood state. Four groups of male Sprague Dawley rat were taken and divided into control and CHC stress exposed group with and without treatment of L-NAME. Depression like behaviour and anhedonia in rats were assessed by Forced Swim Test (FST) and Sucrose Preference Test (SPT). Microglial activation was evaluated using Iba-1 immunohistochemistry and proinflammatory cytokines were assessed in the hippocampal region. Our result showed that exposure to CHC stress increased the number of active microglia with corresponding increase in inflammatory cytokines and altered behavioural responses. The inhibition of NO synthesis by L-NAME during CHC exposure decreased the number of active microglia in hippocampus as evident from decreased Iba-1 positive cells. Further, L-NAME administration decreased pro-inflammatory cytokines in hippocampus and improved behaviour of rats. Our study demonstrate that stress induced elevation of NO plays pivotal role in altered microglial activation and consequent neurodegenerative processes leading to depression like behaviour in rat.

Evacuation of Pedestrians with Two Motion Modes for Panic System

In this paper, we have captured an underlying mechanism of emergence of collective panic in pedestrian evacuations by using a modification of the lattice-gas model. We classify the motion of pedestrians into two modes according to their moods. One is gentle (mode I), the other is flustered (mode II). First, to research the cause for crowd, we fix the motion modes of pedestrians and increase the proportion of pedestrians with motion mode II (ρ_II). The simulation results show that the pedestrians with motion mode II are lack of evacuation efficiency and cause more casualties. Further, we use the SIS (susceptible-infective-susceptible) model to describe the spreading of the panic mood. The system can be in the high-mix state when the infection probability λ is greater than a fuzzy threshold. In addition, the distances S from wounded people to the exit are researched, the number of wounded people gets maximum at the internal S = 5 ∼ 10, which is independent of ρ_II and λ. This research can help us to understand and prevent the emergence of collective panic and reduce wounds in the real evacuation.

Incipient Social Groups: An Analysis via In-Vivo Behavioral Tracking

Social psychology is fundamentally the study of individuals in groups, yet there remain basic unanswered questions about group formation, structure, and change. We argue that the problem is methodological. Until recently, there was no way to track who was interacting with whom with anything approximating valid resolution and scale. In the current study we describe a new method that applies recent advances in image-based tracking to study incipient group formation and evolution with experimental precision and control. In this method, which we term “in vivo behavioral tracking,” we track individuals’ movements with a high definition video camera mounted atop a large field laboratory. We report results of an initial study that quantifies the composition, structure, and size of the incipient groups. We also apply in-vivo spatial tracking to study participants’ tendency to cooperate as a function of their embeddedness in those crowds. We find that participants form groups of seven on average, are more likely to approach others of similar attractiveness and (to a lesser extent) gender, and that participants’ gender and attractiveness are both associated with their proximity to the spatial center of groups (such that women and attractive individuals are more likely than men and unattractive individuals to end up in the center of their groups). Furthermore, participants’ proximity to others early in the study predicted the effort they exerted in a subsequent cooperative task, suggesting that submergence in a crowd may predict social loafing. We conclude that in vivo behavioral tracking is a uniquely powerful new tool for answering longstanding, fundamental questions about group dynamics.

Association between shelter crowding and incidence of sleep disturbance among disaster evacuees: a retrospective medical chart review study

OBJECTIVES

We determined whether crowding at emergency shelters is associated with a higher incidence of sleep disturbance among disaster evacuees and identified the minimum required personal space at shelters.

DESIGN

Retrospective review of medical charts.

SETTING

30 shelter-based medical clinics in Ishinomaki, Japan, during the 46 days following the Great Eastern Japan Earthquake and Tsunami in 2011.

PARTICIPANTS

Shelter residents who visited eligible clinics.

OUTCOME MEASURES

Based on the result of a locally weighted scatter-plot smoothing technique assessing the relationship between the mean space per evacuee and cumulative incidence of sleep disturbance at the shelter, eligible shelters were classified into crowded and non-crowded shelters. The cumulative incidence per 1000 evacuees was compared between groups, using a Mann-Whitney U test. To assess the association between shelter crowding and the daily incidence of sleep disturbance per 1000 evacuees, quasi-least squares method adjusting for potential confounders was used.

RESULTS

The 30 shelters were categorised as crowded (mean space per evacuee <5.0 m(2), 9 shelters) or non-crowded (≥ 5.0 m(2), 21 shelters). The study included 9031 patients. Among the eligible patients, 1079 patients (11.9%) were diagnosed with sleep disturbance. Mean space per evacuee during the study period was 3.3 m(2) (SD, 0.8 m(2)) at crowded shelters and 8.6 m(2) (SD, 4.3 m(2)) at non-crowded shelters. The median cumulative incidence of sleep disturbance did not differ between the crowded shelters (2.3/1000 person-days (IQR, 1.6-5.4)) and non-crowded shelters (1.9/1000 person-days (IQR, 1.0-2.8); p=0.20). In contrast, after adjusting for potential confounders, crowded shelters had an increased daily incidence of sleep disturbance (2.6 per 1000 person-days; 95% CI 0.2 to 5.0/1000 person-days, p=0.03) compared to that at non-crowded shelters.

CONCLUSIONS

Crowding at shelters may exacerbate sleep disruptions in disaster evacuees; therefore, appropriate evacuation space requirements should be considered.

How Does Emergency Department Crowding Affect Medical Student Test Scores and Clerkship Evaluations?

INTRODUCTION

The effect of emergency department (ED) crowding has been recognized as a concern for more than 20 years; its effect on productivity, medical errors, and patient satisfaction has been studied extensively. Little research has reviewed the effect of ED crowding on medical education. Prior studies that have considered this effect have shown no correlation between ED crowding and resident perception of quality of medical education.

OBJECTIVE

To determine whether ED crowding, as measured by the National ED Overcrowding Scale (NEDOCS) score, has a quantifiable effect on medical student objective and subjective experiences during emergency medicine (EM) clerkship rotations.

METHODS

We collected end-of-rotation examinations and medical student evaluations for 21 EM rotation blocks between July 2010 and May 2012, with a total of 211 students. NEDOCS scores were calculated for each corresponding period. Weighted regression analyses examined the correlation between components of the medical student evaluation, student test scores, and the NEDOCS score for each period.

RESULTS

When all 21 rotations are included in the analysis, NEDOCS scores showed a negative correlation with medical student tests scores (regression coefficient= -0.16, p=0.04) and three elements of the rotation evaluation (attending teaching, communication, and systems-based practice; p<0.05). We excluded an outlying NEDOCS score from the analysis and obtained similar results. When the data were controlled for effect of month of the year, only student test score remained significantly correlated with NEDOCS score (p=0.011). No part of the medical student rotation evaluation attained significant correlation with the NEDOCS score (p≥0.34 in all cases).

CONCLUSION

ED overcrowding does demonstrate a small but negative association with medical student performance on end-of-rotation examinations. Additional studies are recommended to further evaluate this effect.

Does Prison Crowding Predict Higher Rates of Substance Use Related Parole Violations? A Recurrent Events Multi-Level Survival Analysis

Objective

This administrative data-linkage cohort study examines the association between prison crowding and the rate of post-release parole violations in a random sample of prisoners released with parole conditions in California, for an observation period of two years (January 2003 through December 2004).

Background

Crowding overextends prison resources needed to adequately protect inmates and provide drug rehabilitation services. Violence and lack of access to treatment are known risk factors for drug use and substance use disorders. These and other psychosocial effects of crowding may lead to higher rates of recidivism in California parolees.

Methods

Rates of parole violation for parolees exposed to high and medium levels of prison crowding were compared to parolees with low prison crowding exposure. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using a Cox model for recurrent events. Our dataset included 13070 parolees in California, combining individual level parolee data with aggregate level crowding data for multilevel analysis.

Results

Comparing parolees exposed to high crowding with those exposed to low crowding, the effect sizes from greatest to least were absconding violations (HR 3.56 95% CI: 3.05–4.17), drug violations (HR 2.44 95% CI: 2.00–2.98), non-violent violations (HR 2.14 95% CI: 1.73–2.64), violent and serious violations (HR 1.88 95% CI: 1.45–2.43), and technical violations (HR 1.86 95% CI: 1.37–2.53).

Conclusions

Prison crowding predicted higher rates of parole violations after release from prison. The effect was magnitude-dependent and particularly strong for drug charges. Further research into whether adverse prison experiences, such as crowding, are associated with recidivism and drug use in particular may be warranted.

Mass Gathering Medical Care: Resource Document for the National Association of EMS Physicians Position Statement

Mass gatherings are heterogeneous in terms of size, duration, type of event, crowd behavior, demographics of the participants and spectators, use of recreational substances, weather, and environment. The goals of health and medical services should be the provision of care for participants and spectators consistent with local standards of care, protection of continuing medical service to the populations surrounding the event venue, and preparation for surge to respond to extraordinary events. Pre-event planning among jurisdictional public health and EMS, acute care hospitals, and event EMS is essential, but should also include, at a minimum, event security services, public relations, facility maintenance, communications technicians, and the event planners and organizers. Previous documented experience with similar events has been shown to most accurately predict future needs. Future work in and guidance for mass gathering medical care should include the consistent use and further development of universally accepted consistent metrics, such as Patient Presentation Rate and Transfer to Hospital Rate. Only by standardizing data collection can evaluations be performed that link interventions with outcomes to enhance evidence-based EMS services at mass gatherings. Research is needed to evaluate the skills and interventions required by EMS providers to achieve desired outcomes. The event-dedicated EMS Medical Director is integral to acceptable quality medical care provided at mass gatherings; hence, he/she must be included in all aspects of mass gathering medical care planning, preparations, response, and recovery. Incorporation of jurisdictional EMS and community hospital medical leadership, and emergency practitioners into these processes will ensure that on-site care, transport, and transition to acute care at appropriate receiving facilities is consistent with, and fully integrated into the community's medical care system, while fulfilling the needs of event participants.

Going Through, Going Around: A Study on Individual Avoidance of Groups

When avoiding a group, a walker has two possibilities: either he goes through it or around it. Going through very dense groups or around huge ones would not seem natural and could break any sense of presence in a virtual environment. This paper aims to enable crowd simulators to handle such situations correctly. To this end, we need to understand how real humans decide to go through or around groups. As a first hypothesis, we apply the Principle of Minimum Energy (PME) on different group sizes and density. According to this principle, a walker should go around small and dense groups whereas he should go through large and sparse groups. Such principle has already been used for crowd simulation; the novelty here is to apply it to decide on a global avoidance strategy instead of local adaptations only. Our study quantifies decision thresholds. However, PME leaves some inconclusive situations for which the two solutions paths have similar energetic costs. In a second part, we propose an experiment to corroborate PME decisions thresholds with real observations. As controlling the factors of an experiment with many people is extremely hard, we propose to use Virtual Reality as a new method to observe human behavior. This work represents the first crowd simulation algorithm component directly designed from a VR-based study. We also consider the role of secondary factors in inconclusive situations. We show the influence of the group appearance and direction of relative motion in the decision process. Finally, we draw some guidelines to integrate our conclusions to existing crowd simulators and show an example of such integration. We evaluate the achieved improvements.

Disentangling the impact of social groups on response times and movement dynamics in evacuations

Crowd evacuations are paradigmatic examples for collective behaviour, as interactions between individuals lead to the overall movement dynamics. Approaches assuming that all individuals interact in the same way have significantly improved our understanding of pedestrian crowd evacuations. However, this scenario is unlikely, as many pedestrians move in social groups that are based on friendship or kinship. We test how the presence of social groups affects the egress time of individuals and crowds in a representative crowd evacuation experiment. Our results suggest that the presence of social groups increases egress times and that this is largely due to differences at two stages of evacuations. First, individuals in social groups take longer to show a movement response at the start of evacuations, and, second, they take longer to move into the vicinity of the exits once they have started to move towards them. Surprisingly, there are no discernible time differences between the movement of independent individuals and individuals in groups directly in front of the exits. We explain these results and discuss their implications. Our findings elucidate behavioural differences between independent individuals and social groups in evacuations. Such insights are crucial for the control of crowd evacuations and for planning mass events.

Updates since Brown v. Plata: alternative solutions for prison overcrowding in California

With the number of inmates under the care of the California Department of Corrections and Rehabilitation (CDCR) swelling over the past few decades, California faces a challenge. The U.S. Supreme Court ruled in their 2011 decision in Brown v. Plata that overcrowding violates inmates' Eighth Amendment rights, specifically that they are denied adequate medical and mental health care. Federally mandated release programs have historically raised some concerns regarding public safety and fiscal efficiency. Given the large number of mentally ill inmates in the United States, alternatives such as assisted outpatient treatment, mental health courts, and increased funding for substance use treatment can be used proactively to reduce the CDCR population and provide long-term solutions to the overcrowding problem. These alternatives have already shown long-term cost savings in addition to reducing the recidivism of individuals involved and would help provide appropriate diversion for mentally ill individuals.

Oral Disorders, Socioenvironmental Factors and Subjective Perception Impact on Children's School Performance

PURPOSE

To examine the impact of oral disorders, socioenvironmental factors and subjective perceptions on children's school performance.

MATERIALS AND METHODS

The sample of 515 12-year-old children was randomly selected by conglomerate analysis. The children were clinically evaluated (DMFT index, bleeding on probing and DAI index) and asked to complete the questionnaire about family environment, self-perception of health status, oral health-related quality of life (OHRQoL) and school (questions in Child Perceptions Questionnaire - CPQ11-14). A questionnaire about socioeconomic status and perceptions about their children's health was sent to the parents. School performance was measured.

RESULTS

In a multivariate logistic model, the following variables remained statistically significant when associated with adolescents' poor school performance in the final model: number of people living in household, household overcrowding, parental perceptions about their children's oral health, presence of carious lesions and a question from CPQ11-14 about difficulty in paying attention in class because of their teeth, lips, jaws or mouth.

CONCLUSION

The results of this study showed that socioenvironmental factors, subjective perceptions and oral health status of children - particularly carious lesions, have an important impact on school performance, demonstrating the need for planning public health dentistry based on intersectoral public policies.

How to not get stuck-negative feedback due to crowding maintains flexibility in ant foraging

Ant foraging is an important model system in the study of adaptive complex systems. Many ants use trail pheromones to recruit nestmates to resources. Differential recruitment depending on resource quality coupled with positive feedback allows ant colonies to make rapid and accurate collective decisions about how best to allocate their work-force. However, ant colonies can become trapped in sub-optimal foraging decisions if recruitment to a poor resource becomes too strong before a better resource is discovered. Genetic algorithms and Ant Colony Optimisation heuristics can also suffer from being trapped in such local optima. Recently, two negative feedback effects were described, in which an increase in crowding (crowding negative feedback-CNF) or trail pheromones (pheromone negative feedback-PNF) caused a decrease in subsequent pheromone deposition. Using agent based simulations with realistic parameters I test whether these negative feedback effects can prevent simulated ant colonies from becoming trapped in sub-optimal foraging decisions. Colonies are presented with two food sources of different qualities, and these qualities switch part way through the experiment. When either no negative feedback effects are implemented or only PNF is implemented colonies are completely unable to refocus their foraging effort to the high quality feeder. However, when CNF alone is implemented at a realistic level 97% of colonies successfully refocus their foraging effort. This ability to refocus colony foraging efforts is due to the strong reduction of pheromone deposition caused by CNF. This suggests that CNF is an important behaviour enabling ant colonies to maintain foraging flexibility. However, CNF comes at a slight cost to colonies when making their initial foraging decision.

Long-lived crowded-litter mice exhibit lasting effects on insulin sensitivity and energy homeostasis

The action of nutrients on early postnatal growth can influence mammalian aging and longevity. Recent work has demonstrated that limiting nutrient availability in the first 3 wk of life [by increasing the number of pups in the crowded-litter (CL) model] leads to extension of mean and maximal lifespan in genetically normal mice. In this study, we aimed to characterize the impact of early-life nutrient intervention on glucose metabolism and energy homeostasis in CL mice. In our study, we used mice from litters supplemented to 12 or 15 pups and compared those to control litters limited to eight pups. At weaning and then throughout adult life, CL mice are significantly leaner and consume more oxygen relative to control mice. At 6 mo of age, CL mice had low fasting leptin concentrations, and low-dose leptin injections reduced body weight and food intake more in CL female mice than in controls. At 22 mo, CL female mice also have smaller adipocytes compared with controls. Glucose and insulin tolerance tests show an increase in insulin sensitivity in 6 mo old CL male mice, and females become more insulin sensitive later in life. Furthermore, β-cell mass was significantly reduced in the CL male mice and was associated with reduction in β-cell proliferation rate in these mice. Together, these data show that early-life nutrient intervention has a significant lifelong effect on metabolic characteristics that may contribute to the increased lifespan of CL mice.

Effects of facility developments and encounter levels on perceptions of settings, crowding, and norms in a korean park

This article examines potential effects of two physical developments (presence or absence of an aerial tramway, a road vs. a trail) and one social variable (increasing encounters with other people) on individuals' perceptions of settings (i.e., perceived settings), crowding, and acceptance of encounters (i.e., norms) in Mudeungsan Provincial Park in South Korea, where there have been proposals for a new aerial tramway. Data were obtained from 241 students at Chonnam National University, almost all of whom had previously visited this park (e.g., 66 % visited at least one of the two study locations in this park, 55 % visited this park in the past 12 months). Simulated photographs showed encounter levels (1 or 15 hikers), the presence or absence of a tramway, and a road versus a trail. Respondents encountering low numbers of other people felt less crowded, considered these use levels to be more acceptable, and perceived the area as more pristine and less developed. Locations containing an aerial tramway were perceived as more developed and less natural, and higher encounter levels were considered to be more acceptable at these locations. Whether settings contained a road or a trail did not influence perceived settings, crowding, or norms. Implications of these findings for future research and management of parks and related outdoor settings are discussed.

Decarceration of U.S. jails and prisons: where will persons with serious mental illness go?

Decarceration (decreasing the number of persons incarcerated in U.S. jails and prisons) has begun. It is estimated that more than 350,000 persons with serious mental illness (SMI) are among those incarcerated in the United States and that many thousands of them will probably be among those released. Currently, the prison population in general is being reduced as a consequence of concerns about overcrowding and of policies and programs such as reclassification of drug possession, which would affect many persons with mental illness. Court-ordered diversion and changes in sentencing guidelines are also serving to reduce prison populations. In recent years, the mental health system did not have to manage as large a number of persons with SMI, especially those who were among the most difficult and expensive to treat, because many of them were incarcerated in jails and prisons. Now, with decarceration and the release of many such persons, the mental health system may be expected to assume more responsibility for them and should be prepared and funded to meet their needs. This population of persons with SMI needs structure and treatment that, depending upon their individual needs, may include 24-hour supportive housing, ACT and FACT teams, assisted outpatient treatment, psychiatric medication, and psychiatric hospitalization.

Understanding the drivers on medical workloads: an analysis of spectators at the Australian Football League

Objective. The present study was designed to further understand the psychosocial drivers of crowds impacting on the demand for healthcare. This involved analysing different spectator crowds for medical usage at mass gatherings; more specifically, did different football team spectators (of the Australian Football League) generate different medical usage rates. Methods. In total, 317 games were analysed from 10 venues over 2 years. Data were analysed by the ANOVA and Pearson correlation tests. Results. Spectators who supported different football teams generated statistically significant differences in patient presentation rates (PPR) (F15, 618 = 1.998, P = 0.014). The present study confirmed previous findings that there is a positive correlation between the crowd size and PPR at mass gatherings but found a negative correlation between density and PPR (r = –0.206, n = 317, P < 0.0005). Conclusions. The present study has attempted to scientifically explore psychosocial elements of crowd behaviour as a driver of demand for emergency medical care. In measuring demand for emergency medical services there is a need to develop a more sophisticated understanding of a variety of drivers in addition to traditional metrics such as temperature, crowd size and other physical elements. In this study we saw that spectators who supported different football teams generated statistically significant differences in PPR. What is known about this topic? Understanding the drivers of emergency medical care is most important in the mass gathering setting. There has been minimal analysis of psychological ‘crowd’ variables. What does this paper add? This study explores the psychosocial impact of supporting a different team on the PPR of spectators at Australian Football League matches. The value of collecting and analysing these types of data sets is to support more balanced planning, better decision support and knowledge management, and more effective emergency medical demand management. What are the implications for practitioners? This information further expands the body of evidence being created to understand the drivers of emergency medical demand and usage. In addition, it supports the planning and management of emergency medical and health-related requirements by increasing our understanding of the effect of elements of ‘crowd’ that impact on medical usage and emergency healthcare.

Participation in mass gatherings can benefit well-being: longitudinal and control data from a North Indian Hindu pilgrimage event

How does participation in a long-duration mass gathering (such as a pilgrimage event) impact well-being? There are good reasons to believe such collective events pose risks to health. There are risks associated with communicable diseases. Moreover, the physical conditions at such events (noise, crowding, harsh conditions) are often detrimental to well-being. Yet, at the same time, social psychological research suggests participation in group-related activities can impact well-being positively, and we therefore investigated if participating in a long-duration mass gathering can actually bring such benefits. In our research we studied one of the world's largest collective events - a demanding month-long Hindu religious festival in North India. Participants (comprising 416 pilgrims who attended the gathering for the whole month of its duration, and 127 controls who did not) completed measures of self-assessed well-being and symptoms of ill-health at two time points. The first was a month before the gathering commenced, the second was a month after it finished. We found that those participating in this collective event reported a longitudinal increase in well-being relative to those who did not participate. Our data therefore imply we should reconceptualise how mass gatherings impact individuals. Although such gatherings can entail significant health risks, the benefits for well-being also need recognition. Indeed, an exclusive focus on risk is misleading and limits our understanding of why such events may be so attractive. More importantly, as our research is longitudinal and includes a control group, our work adds robust evidence to the social psychological literature concerning the relationship between participation in social group activities and well-being.

Pediatric emergency department crowding is associated with a lower likelihood of hospital admission

OBJECTIVES

Emergency department (ED) crowding may affect disposition decision-making. The objective was to measure the effect of ED crowding on probability of admission and return visit to the ED after discharge.

METHODS

The authors studied a historical cohort at a large pediatric ED over 40 months. Each patient was assigned a score on arrival based on the ED occupancy rate (the ratio of patients to beds). Patients were divided into quintiles by occupancy rate. The proportion admitted for each quintile was compared to the least crowded quintile adjusting for acuity, hospital occupancy, and time of arrival. The same analysis was performed for return visits to the ED within 48 hours. The analyses were repeated for the subsets of patients with asthma and with gastroenteritis and/or dehydration.

RESULTS

From the 40 months of historical data, 198,778 visits were analyzed. The adjusted odds ratio (aOR) for admission among the whole cohort was 0.85 (95% confidence interval [CI]=0.81 to 0.89) comparing the highest to the lowest crowding quintiles (occupancy rate >1.17 and <0.54, respectively). For asthma patients, aOR=0.93 (95% CI=0.72 to 1.20), and for gastroenteritis patients, aOR=0.87 (95% CI=0.65 to 1.17). The aOR of return visits comparing the highest to the lowest crowding quintiles for all patients was aOR=0.87 (95% CI=0.79 to 0.97), for asthma patients was aOR=1.52 (95% CI=0.95 to 2.46), and for gastroenteritis patients was aOR=0.83 (95% CI=0.54 to 1.28).

CONCLUSIONS

Increasing ED crowding is associated with a lower likelihood of hospital admission and lower frequency of return visits within 48 hours.

The Development of Conceptual Models for Mass-Gathering Health

Mass gatherings are an increasingly common feature of modern society. However, descriptive papers that focus on a single event or event type, dominate the literature, and, while these contribute to our understanding of the patient care required at such events, they do not provide an adequate analysis of the health effects of the mass-gathering phenomenon itself. This paper argues for the development of conceptual models and a research template for mass-gathering research. The development of theory and conceptual models would promote a better understanding of the health effects of mass gatherings. Two preliminary conceptual models are presented as a means to encourage further debate about the dominant influences on the health of people where crowds gather and to promote less superficial forms of analysis of the research data.

These conceptual models are based on the idea that mass-gathering health can be understood as an inter-relationship between three domains: (1) the biomedical; (2) the environmental; and (3) the psychosocial. Key features influence the rate of injury and illness and characterize each domain. These key features are more or less well-understood and combine to produce an effect—the patient presentation rate, and a response—the health plan. A new element, the latent potential for injury and illness, is introduced as a mechanism for describing a biomedical precursor state important in assessing health risk during mass gatherings.

The temporal impact of chronic intermittent psychosocial stress on high-fat diet-induced alterations in body weight

BACKGROUND

Chronic stress and diet can independently or in concert influence the body's homeostasis over time. Thus, it is crucial to investigate the interplay of these parameters to gain insight into the evolution of stress-induced metabolic and eating disorders.

METHODS

C57BL/6J mice were subjected to chronic psychosocial (mixed model of social defeat and overcrowding) stress in combination with either a high- or low-fat diet for three or six weeks. To determine the evolution of stress and dietary effects, changes in body weight, caloric intake and caloric efficiency were determined as well as circulating leptin, insulin, glucose and corticosterone levels and social avoidance behaviour.

RESULTS

Exposure to stress for three weeks caused an increase in weight gain, in caloric intake and in caloric efficiency only in mice on a low-fat diet. However, after six weeks, only stressed mice on a high-fat diet displayed a pronounced inhibition of body weight gain, accompanied by reduced caloric intake and caloric efficiency. Stress decreased circulating leptin levels in mice on a low-fat diet after three weeks and in mice on a high-fat diet after three and six weeks of exposure. Plasma levels of insulin and markers of insulin resistance were blunted in mice on high-fat diet following six weeks of stress exposure. Social avoidance following chronic stress was present in all mice after three and six weeks.

CONCLUSIONS

This study describes the evolution of the chronic effects of social defeat/overcrowding stress in combination with exposure to high- or low-fat diet. Most importantly, we demonstrate that a six week chronic exposure to social defeat stress prevents the metabolic effects of high-fat diet, by inhibiting an increase in weight gain, caloric intake and efficiency and insulin resistance as well as in plasma leptin and insulin levels. This study highlights the importance of considering the chronic aspects of both parameters and their time-dependent interplay.

Prison structure, inmate mortality and suicide risk in Europe

Suicide presents a major complication during imprisonment and greatly contributes to the high mortality rate of prisoners. All international studies have found increased suicide rates among prisoners compared to the general population. This study examines risk factors for suicide and mortality in prisoners using supranational data from the Council of Europe Annual Penal Statistics (Statistiques Penales Annuelles du Conseil du L'Europe or SPACE) from 1997 to 2008. Macrostructural risk factors for prison suicide are analyzed from this supranational data set and the identified indicators are further evaluated on the single country level. Sexual offenders, offenders charged with violent crimes and prisoners sentenced for short- and long-term imprisonment are considered to be at an elevated risk for suicide. In addition, prison mortality is associated with overcrowding.

Chronic psychosocial stress induces visceral hyperalgesia in mice

Experimental and clinical evidence has shown that chronic stress plays an important role in the onset and/or exacerbation of symptoms of functional gastrointestinal disorders. Here, we aimed to investigate whether exposure to a chronic and temporally unpredictable psychosocial stressor alters visceral and somatic nociception as well as anxiety-related behaviour. In male C57BL/6J mice, chronic stress was induced by repeated exposure to social defeat (SD, 2 h) and overcrowding (OC, 24 h) during 19 consecutive days. Visceral and somatic nociception was evaluated by colorectal distension and a hot plate, respectively. The social interaction test was used to assess social anxiety. Mice exposed to psychosocial stress developed visceral hyperalgesia and somatic hypoalgesia 24 h following the last stress session. SD/OC mice also exhibited social anxiety-like behaviour. All these changes were also associated with physiological alterations, measured as a decreased faecal pellet output and hypothalamic-pituitary-adrenal (HPA) axis disruption. Taken together, these data confirm that this mouse model of chronic psychosocial stress may be useful for studies on the pathophysiological mechanisms underlying such stress-associated disorders and to further test potential therapies.