The Role of Projection in the Control of Bird Flocks

Swarming is a conspicuous behavioural trait observed in bird flocks, fish shoals, insect swarms and mammal herds. It is thought to improve collective awareness and offer protection from predators. Many current models involve the hypothesis that information coordinating motion is exchanged between neighbors. We argue that such local interactions alone are insufficient to explain the organization of large flocks of birds and that the mechanism for the exchange of long-ranged information necessary to control their density remains unknown. We show that large flocks self-organize to the maximum density at which a typical individual is still just able to see out of the flock in many directions. Such flocks are marginally opaque - an external observer can also just still see a substantial fraction of sky through the flock. Although seemingly intuitive we show that this need not be the case; flocks could easily be highly diffuse or entirely opaque. The emergence of marginal opacity strongly constrains how individuals interact with each other within large swarms. It also provides a mechanism for global interactions: An individual can respond to the projection of the flock that it sees. This provides for faster information transfer and hence rapid flock dynamics, another advantage over local models. From a behavioural perspective it optimizes the information available to each bird while maintaining the protection of a dense, coherent flock.Comment: PNAS early edition published online at http://www.pnas.org/cgi/doi/10.1073/pnas.140220211

A Feedback System for the Motor Learning of Skills in Golf

AbstractThis paper presents a feedback GUI to improve the motor skills of a subject performing a golf putt. In this paper inertial sensors (gyroscopes) and video were used to capture the swing. Feedback was provided by a graphical user interface created in Matlab and displayed the video of the putt and quantitative values such as the putt tempo (ratio Backswing duration: Downswing duration) and score which gives an indication of how close the putt tempo is to the ideal rato of (2:1). A zero-crossing method was used to determine the swing phases and durations from the rotational velocity.The effectiveness of the feedback GUI was tested using 10 participants (4 experienced and 6 inexperienced). Each participant executed two sets of 15 putts over distances of 3m, 6m and 9m on an artificial turf putting surface with feedback provided by the GUI between the two sets of putts. The results indicated that overall tempo ratio of experienced and inexperienced participants became closer to 2:1 after the feedback. The standard deviation also decreased which meant that participants also improved their putting consistency. The results indicate that the participants were able to improve their skill in terms of putting performance indicators after using the feedback GUI

Noisy Spins and the Richardson-Gaudin Model.

We study a system of spins (qubits) coupled to a common noisy environment, each precessing at its own frequency. The correlated noise experienced by the spins implies long-lived correlations that relax only due to the differing frequencies. We use a mapping to a non-Hermitian integrable Richardson-Gaudin model to find the exact spectrum of the quantum master equation in the high-temperature limit and, hence, determine the decay rate. Our solution can be used to evaluate the effect of inhomogeneous splittings on a system of qubits coupled to a common bath.D. A. R. and A. L. gratefully acknowledge the Engineering and Physical Sciences Research Council for financial support, under Grants No. EP/M506485/1 and No. EP/P034616/1, respectivel

USING WEARABLE TECHNOLOGY TO DETECT CHANGES TO TRUNK POSITION AND POWER IN CYCLING

This pilot study aimed to quantify the change of CoM acceleration when the trunk position and the power output was varied during indoor cycling. Triathletes (n=4) performed a varied indoor cycling power protocol in their natural training environment whilst wearing a trunk (sacrum) mounted wearable device containing a triaxial accelerometer. Mediolateral acceleration increased 26% as athletes moved from the drops position, to the aerodynamic position and back to the drops position. Although longitudinal acceleration increased 8%, minimal differences in anteroposterior CoM magnitude were observed. Power output was found to have an effect on both the mediolateral and longitudinal acceleration alongside increases in RPE. The results indicate that accelerometers may be effective in monitoring changes to trunk position and power output

Predicting sizes of hexagonal and gyroid metal nanostructures from liquid crystal templating

We describe a method to predict and control the lattice parameters of hexagonal and gyroid mesoporous materials formed by liquid crystal templating. In the first part, we describe a geometric model with which the lattice parameters of different liquid crystal mesophases can be predicted as a function of their water/surfactant/oil volume fractions, based on certain geometric parameters relating to the constituent surfactant molecules. We demonstrate the application of this model to the lamellar (LR), hexagonal (H1), and gyroid bicontinuous cubic (V1) mesophases formed by the binary Brij-56 (C16EO10)/water system and the ternary Brij-56/hexadecane/water system. In this way, we demonstrate predictable and independent control over the size of the cylinders (with hexadecane) and their spacing (with water). In the second part, we produce mesoporous platinum using as templates hexagonal and gyroid phases with different compositions and show that in each case the symmetry and lattice parameter of the metal nanostructure faithfully replicate those of the liquid crystal template, which is itself in agreement with the model. This demonstrates a rational control over the geometry, size, and spacing of pores in a mesoporous metal

Choice of activity-intensity classification thresholds impacts upon accelerometer-assessed physical activity-health relationships in children

It is unknown whether using different published thresholds (PTs) for classifying physical activity (PA) impacts upon activity-health relationships. This study explored whether relationships between PA (sedentary [SED], light PA [LPA], moderate PA [MPA], moderate-to-vigorous PA, vigorous PA [VPA]) and health markers differed in children when classified using three different PTs

Picture This! Reflecting on the Use of Posters as Expressions of PhD Research Projects

The presentation of posters at scientific conferences to visually represent research projects is a widespread international practice. The main purpose of this paper is to offer reflections relating to posters as visual representations of research studies conducted by PhD candidates. As the basis for our reflections, we consider the main purposes and intended learning outcomes linked to posters and reflect on some of the design and assessment issues associated with the multi-faceted purposes of posters in contexts such as postgraduate research conferences. Notably, the paper includes a set of illustrative vignettes written by a group of PhD students from the Faculty of Humanities at the University of Manchester who were required to design and exhibit posters at an annually held postgraduate research conference. This reflexive dialogue raises a series of issues for consideration by those who are actively involved with the design, presentation, observation and assessment of posters produced by PhD candidates.Exploring Visual Representation of Concepts in Learning and Teaching in Higher Educatio

Coral bleaching impacts from back-to-back 2015–2016 thermal anomalies in the remote central Indian Ocean

Studying scleractinian coral bleaching and recovery dynamics in remote, isolated reef systems offers an opportunity to examine impacts of global reef stressors in the absence of local human threats. Reefs in the Chagos Archipelago, central Indian Ocean, suffered severe bleaching and mortality in 2015 following a 7.5 maximum degree heating weeks (DHWs) thermal anomaly, causing a 60% coral cover decrease from 30% cover in 2012 to 12% in April 2016. Mortality was taxon specific, with Porites becoming the dominant coral genus post-bleaching because of an 86% decline in Acropora from 14 to 2% cover. Spatial heterogeneity in Acropora mortality across the Archipelago was significantly negatively correlated with variation in DHWs and with chlorophyll-a concentrations. In 2016, a 17.6 maximum DHWs thermal anomaly caused further damage, with 68% of remaining corals bleaching in May 2016, and coral cover further declining by 29% at Peros Banhos Atoll (northern Chagos Archipelago) from 14% in March 2016 to 10% in April 2017. We therefore document back-to-back coral bleaching and mortality events for two successive years in the remote central Indian Ocean. Our results indicate lower coral mortality in 2016 than 2015 despite a more severe thermal anomaly event in 2016. This could be caused by increased thermal resistance and resilience within corals surviving the 2015 thermal anomaly; however, high bleaching prevalence in 2016 suggests there remained a high sensitivity to bleaching. Similar coral mortality and community change were seen in the Chagos Archipelago following the 1998 global bleaching event, from which recovery took 10 yr. This relatively rapid recovery suggests high reef resiliency and indicates that the Archipelago’s lack of local disturbances will increase the probability that the reefs will again recover over time. However, as the return time between thermal anomaly events becomes shorter, this ability to recover will become increasingly compromised