Experimental Analyses of Step Extent and Contact Buffer in Pedestrian Dynamics

This study aims to quantify and develop a deeper understanding of the parameters that underpin the development of a new, predictive, microscopic model of pedestrian movement with the potential to accurately reflect the complexity of flow dynamics now and into the future. It presents the results and analyses of two single file experiments designed to quantify the physical space taken up by the extent of a person's stepping movement (maximum step extent) and the minimum distance between points of inter-person contact (contact buffer) across a range of walking speeds. The experiments successfully used high-resolution optical motion capture and enhanced video analysis to quantify the dynamic changes in gait and spatial parameters, which were manifested as overlapping steps, and changes to step extent, step length, step frequency, and contact distance. The sum of the step extent and contact buffer, at different speeds, was found to be within a few centimetres of the inter-person distance (headway), leading to the conclusion that these parameters are therefore key components for the derivation of inter-person spacing and, hence, overall crowd movement. The work informs the longer term aim of developing the mathematical model which has the potential to include pedestrian demographics, walking ability and cognitive capabilities

Physician–Patient Communication About Prescription Medication Nonadherence: A 50-state Study of America’s Seniors

CONTEXT: Understanding and improving the quality of medication management is particularly important in the context of the Medicare prescription drug benefit that took effect last January 2006. OBJECTIVE: To determine the prevalence of physician–patient dialogue about medication cost and medication adherence among elderly adults nationwide. DESIGN: Cross-sectional survey. PARTICIPANTS: National stratified random sample of community-dwelling Medicare beneficiaries aged 65 and older. MAIN OUTCOME MEASURES: Rates of physician–patient dialogue about nonadherence and cost-related medication switching. RESULTS: Forty-one percent of seniors reported taking five or more prescription medications, and more than half has 2 or more prescribing physicians. Thirty-two percent overall and 24% of those with 3 or more chronic conditions reported not having talked with their doctor about all their different medicines in the last 12 months. Of seniors reporting skipping doses or stopping a medication because of side effects or perceived nonefficacy, 27% had not talked with a physician about it. Of those reporting cost-related nonadherence, 39% had not talked with a physician about it. Thirty-eight percent of those with cost-related nonadherence reported switching to a lower priced drug, and in a multivariable model, having had a discussion about drug cost was significantly associated with this switch (odds ratio [OR] 5.04, 95% confidence interval [CI] 4.28–5.93, P < .001). CONCLUSIONS: We show that there is a communication gap between seniors and their physicians around prescription medications. This communication problem is an important quality and safety issue, and takes on added salience as physicians and patients confront new challenges associated with coverage under new Medicare prescription drug plans. Meeting these challenges will require that more attention be devoted to medication management during all clinical encounters

Regression-based analysis of front crawl swimming using upper-arm mounted accelerometers

The 41st International Engineering in Medicine and Biology Conference, Berlin, Germany, 23-27 July 2019Wearable accelerometers can be used to quantify movement during swimming, enabling objective performance analysis. This study examined arm acceleration during front crawl swimming, and investigated how accelerometer-derived features change with lap times. Thirteen participants swam eight 50m laps using front crawl with a tri-axial accelerometer attached to each upper arm. Data were segmented into individual laps; lap times estimated and individual strokes extracted. Stroke times, root mean squared (RMS) acceleration, RMS jerk and spectral edge frequencies (SEF) were calculated for each stroke. Movement symmetry was assessed as the ratio of the minimum to maximum feature value for left and right arms. A regularized multivariate regression model was developed to estimate lap time using a subset of the accelerometer-derived features. Mean lap time was 56.99±11.99s. Fifteen of the 42 derived features were significantly correlated with lap time. The regression model included 5 features (stroke count, mean SEF of the X and Z axes, stroke count symmetry, and the coefficient of variation of stroke time symmetry) and estimated 50m lap time with a correlation coefficient of 0.86, and a cross-validated RMS error of 6.38s. The accelerometer-derived features and developed regression model may provide a useful tool to quantitatively evaluate swimming performance.European Research CouncilScience Foundation IrelandInsight Research Centre2020-02-13 JG: docx replaced with INSIGHT submitted PD

The Feasibility of Equine Field-Based Postural Sway Analysis Using a Single Inertial Sensor

(1) Background: Postural sway is frequently used to quantify human postural control, balance, injury, and neurological deficits. However, there is considerably less research investigating the value of the metric in horses. Much of the existing equine postural sway research uses force or pressure plates to examine the centre of pressure, inferring change at the centre of mass (COM). This study looks at the inverse, using an inertial measurement unit (IMU) on the withers to investigate change at the COM, exploring the potential of postural sway evaluation in the applied domain. (2) Methods: The lipopolysaccharide model was used to induce transient bilateral lameness in seven equines. Horses were monitored intermittently by a withers fixed IMU over seven days. (3) Results: There was a significant effect of time on total protein, carpal circumference, and white blood cell count in the horses, indicating the presence of, and recovery from, inflammation. There was a greater amplitude of displacement in the craniocaudal (CC) versus the mediolateral (ML) direction. A significant difference was observed in the amplitude of displacement in the ML direction between 4–12 h and 168 h. (4) Conclusions: The significant reduction in ML displacement during the acute inflammation period alongside greater overall CC displacement may be a compensatory behaviour for bilateral lameness

The Feasibility of Equine Field-Based Postural Sway Analysis Using a Single Inertial Sensor

(1) Background: Postural sway is frequently used to quantify human postural control, balance, injury, and neurological deficits. However, there is considerably less research investigating the value of the metric in horses. Much of the existing equine postural sway research uses force or pressure plates to examine the centre of pressure, inferring change at the centre of mass (COM). This study looks at the inverse, using an inertial measurement unit (IMU) on the withers to investigate change at the COM, exploring the potential of postural sway evaluation in the applied domain. (2) Methods: The lipopolysaccharide model was used to induce transient bilateral lameness in seven equines. Horses were monitored intermittently by a withers fixed IMU over seven days. (3) Results: There was a significant effect of time on total protein, carpal circumference, and white blood cell count in the horses, indicating the presence of, and recovery from, inflammation. There was a greater amplitude of displacement in the craniocaudal (CC) versus the mediolateral (ML) direction. A significant difference was observed in the amplitude of displacement in the ML direction between 4–12 h and 168 h. (4) Conclusions: The significant reduction in ML displacement during the acute inflammation period alongside greater overall CC displacement may be a compensatory behaviour for bilateral lameness

A cyclic GMP signalling module that regulates gliding motility in a malaria parasite.

The ookinete is a motile stage in the malaria life cycle which forms in the mosquito blood meal from the zygote. Ookinetes use an acto-myosin motor to glide towards and penetrate the midgut wall to establish infection in the vector. The regulation of gliding motility is poorly understood. Through genetic interaction studies we here describe a signalling module that identifies guanosine 3', 5'-cyclic monophosphate (cGMP) as an important second messenger regulating ookinete differentiation and motility. In ookinetes lacking the cyclic nucleotide degrading phosphodiesterase delta (PDEdelta), unregulated signalling through cGMP results in rounding up of the normally banana-shaped cells. This phenotype is suppressed in a double mutant additionally lacking guanylyl cyclase beta (GCbeta), showing that in ookinetes GCbeta is an important source for cGMP, and that PDEdelta is the relevant cGMP degrading enzyme. Inhibition of the cGMP-dependent protein kinase, PKG, blocks gliding, whereas enhanced signalling through cGMP restores normal gliding speed in a mutant lacking calcium dependent protein kinase 3, suggesting at least a partial overlap between calcium and cGMP dependent pathways. These data demonstrate an important function for signalling through cGMP, and most likely PKG, in dynamically regulating ookinete gliding during the transmission of malaria to the mosquito