Dynamical independence: Discovering emergent macroscopic processes in complex dynamical systems

We introduce a notion of emergence for macroscopic variables associated with highly multivariate microscopic dynamical processes. Dynamical independence instantiates the intuition of an emergent macroscopic process as one possessing the characteristics of a dynamical system "in its own right," with its own dynamical laws distinct from those of the underlying microscopic dynamics. We quantify (departure from) dynamical independence by a transformation-invariant Shannon information-based measure of dynamical dependence. We emphasize the data-driven discovery of dynamically independent macroscopic variables, and introduce the idea of a multiscale "emergence portrait" for complex systems. We show how dynamical dependence may be computed explicitly for linear systems in both time and frequency domains, facilitating discovery of emergent phenomena across spatiotemporal scales, and outline application of the linear operationalization to inference of emergence portraits for neural systems from neurophysiological time-series data. We discuss dynamical independence for discrete- and continuous-time deterministic dynamics, with potential application to Hamiltonian mechanics and classical complex systems such as flocking and cellular automata.

Sampling distribution for single-regression Granger causality estimators

The single-regression Granger-Geweke causality estimator has previously been shown to solve known problems associated with the more conventional likelihood-ratio estimator; however, its sampling distribution has remained unknown. We show that, under the null hypothesis of vanishing Granger causality, the single-regression estimator converges to a generalized χ2 distribution, which is well approximated by a Γ distribution. We show that this holds too for Geweke's spectral causality averaged over a given frequency band, and derive explicit expressions for the generalized χ2 and Γ-approximation parameters in both cases. We present a Neyman–Pearson test based on the single-regression estimators, and discuss how it may be deployed in empirical scenarios. We outline how our analysis may be extended to the conditional case, point-frequency spectral Granger causality, and the important case of state-space Granger causality.

Global COVID-19 lockdown highlights humans as both threats and custodians of the environment

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundreds of reports of unusual species observations from around the world suggest that animals quickly responded to the reductions in human presence. However, negative effects of lockdown on conservation also emerged, as confinement resulted in some park officials being unable to perform conservation, restoration and enforcement tasks, resulting in local increases in illegal activities such as hunting. Overall, there is a complex mixture of positive and negative effects of the pandemic lockdown on nature, all of which have the potential to lead to cascading responses which in turn impact wildlife and nature conservation. While the net effect of the lockdown will need to be assessed over years as data becomes available and persistent effects emerge, immediate responses were detected across the world. Thus, initial qualitative and quantitative data arising from this serendipitous global quasi-experimental perturbation highlights the dual role that humans play in threatening and protecting species and ecosystems. Pathways to favorably tilt this delicate balance include reducing impacts and increasing conservation effectiveness.

A new approach to comprehensively evaluate the morphological properties of the human femoral head: example of application to osteoarthritic joint

Osteoarthritis affects the morphological properties of the femoral head. The goal of this study was to develop a method to elucidate whether these changes are localised to discrete regions, or if the reported trends in microstructural changes may be identified throughout the subchondral bone of the human femoral head. Whole femoral heads extracted from osteoarthritic (n = 5) and healthy controls (n = 5) underwent microCT imaging 39 μm voxel size. The subchondral bone plate was virtually isolated to evaluate the plate thickness and plate porosity. The trabecular bone region was divided into 37 volumes of interest spatially distributed in the femoral head, and bone morphometric properties were determined in each region. The study showed how the developed approach can be used to study the heterogeneous properties of the human femoral head affected by a disease such as osteoarthritis. As example, in the superior femoral head osteoarthritic specimens exhibited a more heterogeneous micro-architecture, with trends towards thicker cortical bone plate, higher trabecular connectivity density, higher trabecular bone density and thicker structures, something that could only be observed with the newly developed approach. Bone cysts were mostly confined to the postero-lateral quadrants extending from the subchondral region into the mid trabecular region. Nevertheless, in order to generalise these findings, a larger sample size should be analysed in the future. This novel method allowed a comprehensive evaluation of the heterogeneous micro-architectural properties of the human femoral head, highlighting effects of OA in the superior subchondral cortical and trabecular bone. Further investigations on different stages of OA would be needed to identify early changes in the bone.

Information flow in finite flocks

We explore information flow in finite active matter flocks by simulating the canonical Vicsek model and estimating the flow of information as a function of noise (the variability in the extent to which each animal aligns with its neighbours). We show that the global transfer entropy for finite flocks not only fails to peak near the phase transition, as demonstrated for the canonical 2D Ising model, but remains constant from the transition throughout the entire ordered regime to very low noise values. This provides a foundation for future study regarding information flow in more complex models and real-world flocking data.

P3769Rapid referral to a one-stop AF clinic following possible AF detection by community pharmacists leads to early diagnosis and appropriate anticoagulant treatment

Background

Atrial fibrillation is the most common cardiac arrhythmia globally, responsible for one third of ischaemic strokes, often resulting in death or incapacity. This condition, frequently asymptomatic is estimated to be up to 50% undiagnosed. Reducing this risk with appropriate detection and management strategies offers substantial economic and patient benefits. Community pharmacists have been shown to be an accessible healthcare professional capable of detecting atrial fibrillation. Concerns raised utilising community pharmacists is the additional workload for primary care physicians, and lack of a clear pathway to ensure patients are adequate followed with assurance of initiation of anticoagulation therapy.

Purpose

To assess the feasibility of screening by community pharmacists with onward referral to an innovative one-stop AF clinic to enable identification of new cases of AF and subsequent initiation of anticoagulation within 2 weeks.

Methods

21 pharmacies were recruited and trained on pathophysiology of AF and demonstration of pulse taking using pulse check and Kardia mobile device. Any person walking into a community pharmacy aged ≥65 years was offered a free pulse check. For any irregularity detected, individualised counselling was offered with a referral made to a one-stop AF clinic for confirmation and initiation of anticoagulation. Written patient consent was obtained.

Results

672 people were recruited with an average age of 69±3.5 years and 58% female (n=389). There was a history of hypertension in 618 (92%) and diabetes in 242 (36%), the most common co-morbidities. 45 people were referred following an irregular pulse or abnormal ECG rhythm strip, of whom 11 (1.6% of total population) had a confirmed AF diagnosis within 30 day follow up. An additional 8 cases with known AF not receiving anticoagulation termed (actionable AF) were also referred. All 19 cases of new or untreated AF were prescribed anticoagulation by the one stop clinic in accordance with guideline recommendations

Conclusions

ESC guidance recommends opportunistic screening for AF by pulse taking or ECG rhythm strip in patients ≥65 years of age. The 1.6% incidence of new AF was in accordance with meta-analyses identifying 1.4% of those aged ≥65 on a single time point check for presence of AF. Our model utilises the un-tapped skills of community pharmacy to deliver pulse checks of ECG rhythm recordings in an accessible primary care location with a clear referral pathway that is effective in early review and ensuring suitable patients receive anticoagulation. The innovative pathway could provide remote triage at scale and help address the missing people with undiagnosed and actionable AF by opening new channels for identification by healthcare professionals managing long term conditions who like pharmacists have not been considered suitable healthcare professionals due to lack of an established pathway for confirming the potential diagnosis of AF.

Acknowledgement/Funding

NHS England Test Bed Programme

A holistic measurement model of movement competency in children

Different countries have different methods for assessing movement competence in children; however, it is unclear whether the test batteries that are used measure the same aspects of movement competence. The aim of this paper was to (1) investigate whether the Test of Gross Motor Development (TGMD-2) and Körperkoordinations Test für Kinder (KTK) measure the same aspects of children's movement competence and (2) examine the factorial structure of the TGMD-2 and KTK in a sample of Australian children. A total of 158 children participated (M age = 9.5; SD = 2.2). First, confirmatory factor analysis examined the independent factorial structure of the KTK and TGMD-2. Second, it was investigated whether locomotor, object control and body coordination loaded on the latent variable Movement Competency. Confirmatory factor analysis indicated an adequate fit for both the KTK and TGMD-2. An adequate fit was also achieved for the final model. In this model, locomotor (r = .86), object control (r = .71) and body coordination (r = .52) loaded on movement competence. Findings support our hypothesis that the TGMD-2 and KTK measure discrete aspects of movement competence. Future researchers and practitioners should consider using a wider range of test batteries to assess movement competence.

Care or cash: assessing quality of care provided by drug retailers in Nepal

Staff in the pharmacies of urban Lalitpur, Nepal, were interviewed, observed in their work, and tested through the use of a researcher posing as a client to assess the quality of care they provide, and their potential as health informants to the general public. Note was made of advice given to clients describing cough symptoms and diarrhoea, symptoms underlying two major causes of morbidity and mortality in Nepal. Data were also collected on the uses made of pharmacies by the general public, in terms of the provision of health care. Results show that people do indeed frequently use pharmacies as a primary care service. However, staff have minimal training. The quality of the advice they provide is varied, but many ask for no additional information on symptoms, and give average or poor advice on the use of the drugs they recommend. Drug retailers are particularly weak on giving explanations to clients about possible side effects and contraindications and rarely refer clients to health professionals. Most "consultations" last less than two minutes. Drug retail staff perceive the provision of health information to be an important and necessary part of their work, and many express a desire for further training. One obvious constraint to developing their health care role, however, would be the undoubted conflict between the financial interests of the drug retailer and the importance for the vast majority of clients of receiving adequate treatment but at limited cost. An important question is whether much higher priority is to provide the drug retailer with more training on drug use and control.

Neural complexity: a graph theoretic interpretation

One of the central challenges facing modern neuroscience is to explain the ability of the nervous system to coherently integrate information across distinct functional modules in the absence of a central executive. To this end, Tononi et al. [Proc. Natl. Acad. Sci. USA. 91, 5033 (1994)] proposed a measure of neural complexity that purports to capture this property based on mutual information between complementary subsets of a system. Neural complexity, so defined, is one of a family of information theoretic metrics developed to measure the balance between the segregation and integration of a system's dynamics. One key question arising for such measures involves understanding how they are influenced by network topology. Sporns et al. [Cereb. Cortex 10, 127 (2000)] employed numerical models in order to determine the dependence of neural complexity on the topological features of a network. However, a complete picture has yet to be established. While De Lucia et al. [Phys. Rev. E 71, 016114 (2005)] made the first attempts at an analytical account of this relationship, their work utilized a formulation of neural complexity that, we argue, did not reflect the intuitions of the original work. In this paper we start by describing weighted connection matrices formed by applying a random continuous weight distribution to binary adjacency matrices. This allows us to derive an approximation for neural complexity in terms of the moments of the weight distribution and elementary graph motifs. In particular, we explicitly establish a dependency of neural complexity on cyclic graph motifs.

Neural complexity and structural connectivity

Tononi [Proc. Natl. Acad. Sci. U.S.A. 91, 5033 (1994)] proposed a measure of neural complexity based on mutual information between complementary subsystems of a given neural network, which has attracted much interest in the neuroscience community and beyond. We develop an approximation of the measure for a popular Gaussian model which, applied to a continuous-time process, elucidates the relationship between the complexity of a neural system and its structural connectivity. Moreover, the approximation is accurate for weakly coupled systems and computationally cheap, scaling polynomially with system size in contrast to the full complexity measure, which scales exponentially. We also discuss connectivity normalization and resolve some issues stemming from an ambiguity in the original Gaussian model.

Spatially embedded random networks

Many real-world networks analyzed in modern network theory have a natural spatial element; e.g., the Internet, social networks, neural networks, etc. Yet, aside from a comparatively small number of somewhat specialized and domain-specific studies, the spatial element is mostly ignored and, in particular, its relation to network structure disregarded. In this paper we introduce a model framework to analyze the mediation of network structure by spatial embedding; specifically, we model connectivity as dependent on the distance between network nodes. Our spatially embedded random networks construction is not primarily intended as an accurate model of any specific class of real-world networks, but rather to gain intuition for the effects of spatial embedding on network structure; nevertheless we are able to demonstrate, in a quite general setting, some constraints of spatial embedding on connectivity such as the effects of spatial symmetry, conditions for scale free degree distributions and the existence of small-world spatial networks. We also derive some standard structural statistics for spatially embedded networks and illustrate the application of our model framework with concrete examples.

Economic analysis of a community-based falls prevention program

OBJECTIVES

To undertake a cost-benefit analysis of 'Stay on Your Feet', a community-based falls prevention program targeting older people at all levels of risk in New South Wales, Australia. Hospital separations were monitored in the intervention region, a control region and for the state of New South Wales as a whole. Changing admission patterns over the intervention period were used to assess the impact of the program.

METHODS

Cost-benefit analysis compared the costs of the program with two estimates of savings from avoided hospital admissions. The first compared the cost of hospital admissions in the intervention region to a control region of similar demographics, while the second compared hospital utilization in the intervention region with the state of New South Wales as a whole using falls-related hospital diagnosis related group (DRG) codes.

RESULTS

The total direct costs of the program were estimated at A dollars 781,829. Both methods identified clear overall net benefits ranging from A dollars 5.4 million for avoided hospitalizations alone to A dollars 16.9 million for all avoided direct and indirect costs. The confidence intervals around these estimates were small. The average overall benefit to cost ratio for the intervention as a whole was 20.6:1.

CONCLUSIONS

These findings suggest that well-designed community-based interventions targeting falls prevention among older people are highly cost effective and a wise investment for all levels of government. The models used are conservative and are likely to underestimate the real benefit of the intervention, which may have lasted for some time beyond the life of the program.

What's Needed to Increase Research Capacity in Rural Primary Health Care?

The aim of this study is to identify ways to build research capacity within primary health. A consultation was undertaken in late 2004 using a combination of a one-page survey and a guided meeting format, in a primary health setting in rural NSW. Most (81.3%) of the 134 individuals consulted were part of an Area Health Service, with 12.7% from non-government settings. Most (80.6%) were clinicians, with a third (31.5%) nurses, 8.3% in medicine, and the remainder from a range of allied health professions. Eleven organisations were represented. The main outcome measures were identification of support needs, processes to enhance research engagement, and barriers and enablers to clinicians' research involvement. The results showed that popular delivery modes for research training and support were courses and "one-to- one" advice. Writing topics were generally more popular than others. Common barriers were time and technology issues. A key enabler was a discipline-specific focus. This is one of few rural Australian consultations on research needs in primary health conducted with a diverse range of clinicians at the clinician level. It will direct future research capacity building efforts towards maximising face-to-face discipline specific options and minimising technology use.

Active school playgrounds-myth or reality? Results of the "move it groove it" project

BACKGROUND

School playgrounds during break times provide potential opportunities for children to be active during the school day. However, there is limited research on how active children really are during these breaks.

METHODS

The CAST (Children's Activity Scanning Tool) instrument was developed, validated, and used to assess the percentages of children engaged in moderate to vigorous physical activity (MVPA) and vigorous physical activity (VPA-a subset of MVPA) in 18 primary schools (children ages 5-12) in rural Australia. Related environmental factors were also measured.

RESULTS

For a school of median size (200 students), 51.4% of boys and 41.6% of girls were engaged in MVPA while 14.7% of boys and 9.4% of girls were engaged in VPA. Levels of engagement in MVPA and VPA were significantly higher during lunch periods than during recess. MVPA and VPA engagement in smaller schools was significantly higher than in larger schools.

CONCLUSIONS

With growing concern about children's physical activity (PA), school playgrounds offer an opportunity to increase children's MVPA engagement especially among girls. Consideration may be given to the lengthening of recess periods in order to increase PA levels. More research is needed to investigate factors affecting PA levels in larger schools.

Repeat use of emergency contraception: How frequent is it?

OBJECTIVE

To measure the level of repeat use of emergency contraception (EC) in family planning clinics (FPCs) in North and East Devon.

DESIGN

An audit of repeat use of EC was carried out in seven FPCs, in parallel with a client survey. All women seeking EC in the study period were included (n = 572).

RESULTS

Nearly 70% of women had 'ever' used EC prior to the study visit; over half had previously used EC in the year of the study; a quarter had previously used EC three or more times in the same period. Teenagers were more likely to have previously used EC in the study year, but half of all repeat users were aged 20 and older. Asked why EC was needed today, most women reported current use of regular contraception, but almost a quarter had had unprotected sex, and half reported a condom mishap.

CONCLUSIONS

These results show frequent repeat use of EC and do not support recent research based on general practice records, which suggests that repeat use is rare. If EC users use multiple sources of EC, or prefer alternative sources, repeat use of EC will be underestimated if calculated using general practitioner (GP) records alone.