Do healthcare services behave as complex systems? Analysis of patterns of attendance and implications for service delivery

Background: The science of complex systems has been proposed as a way of understanding health services and the demand for them, but there is little quantitative evidence to support this. We analysed patterns of healthcare use in different urgent care settings to see if they showed two characteristic statistical features of complex systems: heavy-tailed distributions (including the inverse power law) and generative burst patterns. Methods: We conducted three linked studies. In study 1 we analysed the distribution of number of contacts per patient with an urgent care service in two settings: emergency department (ED) and primary care out-of-hours (PCOOH) services. We hypothesised that these distributions should be heavy-tailed (inverse power law or log-normal) in keeping with typical complex systems. In study 2 we analysed the distribution of bursts of contact with urgent care services by individuals: correlated bursts of activity occur in complex systems and represent a mechanism by which overall heavy-tailed distributions arise. In study 3 we replicated the approach of study 1 using data systematically identified from published sources. Results: Study 1 involved data from a PCOOH service in Scotland (725,000) adults, 1.1 million contacts) and an ED in New Zealand (60,000 adults, 98,000 contacts). The total number of contacts per individual in each dataset was statistically indistinguishable from an inverse power law (p &gt; 0.05) above 4 contacts for the PCOOH data and 3 contacts for the ED data. Study 2 found the distribution of contact bursts closely followed a heavy-tailed distribution (p &lt; 0.008), indicating the presence of correlated bursts. Study 3 identified data from 17 studies across 8 countries and found distributions similar to study 1 in all of them. Conclusions: Urgent healthcare use displays characteristic statistical features of large complex systems. These studies provide strong quantitative evidence that healthcare services behave as complex systems and have important implications for urgent care. Interventions to manage demand must address drivers for consultation across the whole system: focusing on only the highest users (in the tail of the distribution) will have limited impact on efficiency. Bursts of attendance - and ways to shorten them - represent promising targets for managing demand.</p

Markerless tracking of tennis racket motion using a camera

This research is concerned with tracking tennis racket movements. Previously, stereo camera systems have been used to track markers attached to rackets, which allows for racket movements to be obtained in three-dimensions. Typically, markers are manually selected on the image plane but this can be time consuming and inaccurate. This paper discusses a markerless method to measure three-dimensional racket movements using a camera. The method relies on a silhouette of a racket captured with a camera whose relative pose (rotation and translation) is unknown. A candidate relative pose is used to measure the inconsistency between the silhouette and a set of racket silhouettes captured with a fully calibrated camera. The measure of inconsistency can be formulated as a cost function associated with the candidate relative pose. By adjusting parameters of the pose to minimise the cost, an accurate estimation for the true pose of the racket can be made. A validation scheme was developed to compare pose estimates with data obtained using camera calibration software. Rotation about the axis of x, y, z' were accurate to within 2.5° for 88, 90 and 86 % of estimates respectively and resultant translation to within 5 mm for 72% of estimates. This research is the first step in a process to fully validate a novel method for measuring tennis racket movements in real play conditions

Effectiveness of a Targeted, Peer-Driven Skin Cancer Prevention Program for Lifeguards

Lifeguards working at outdoor pools typically receive high amounts of sun exposure, increasing their risk for developing skin cancer. This study evaluates the effectiveness of a targeted, peer-driven intervention for skin cancer prevention among lifeguards. Nine pools received the targeted intervention, Pool Cool Plus, and five received the standard Pool Cool prevention program. Lifeguards completed surveys at the beginning and end of the summer. Lifeguards in both the targeted intervention and standard program groups increased their sun safety practices and reported more sun-safe pool policies and environments. Sunburn rates decreased among lifeguards participating in Pool Cool Plus. Future research should test the feasibility and effectiveness of disseminating the Pool Cool Plus program

Measurement of main strings movement and its effect on tennis ball spin

Ball spin plays an important role in the modern game of tennis. Previous work has shown that reducing the number of cross strings in a tennis racket can increase rebound ball spin. The aim of this study was to further our understanding of the effect of the number of cross strings on ball spin generation. Two rackets were tested, one with 16 main and 19 cross strings and the other with 16 main and 12 cross strings. The racket frame was fully-constrained and a ball was fired onto the strings at inbound angles of 24 and 38º. Inbound velocity was set at 30 m/s and inbound spin was varied from 0 to 500 rad/s. Ball velocity and spin, and lateral main string deflections during impact, were measured from high-speed video footage. Lateral string deflections were consistently larger for the racket with fewer cross strings. The racket with fewer cross strings produced slightly higher rebound spin and lower horizontal rebound velocity, which was attributed to the main strings returning during the restitution phase of the impact

Titan/Saturn System Mission 2008: Exploring Titan on a Budget (and Without Aerocapture!)

This presentation was part of the session : Probe Missions to the Giant Planets, Titan and VenusSixth International Planetary Probe WorkshopTitan has been the topic of a number of mission studies in recent years, culminating in the 2007 Titan Explorer flagship mission study led by APL with JPL participation. This study, as with those previous, made use of the favorable conditions of Titan's atmosphere to allow aerocapture directly into Titan orbit, a technique which would provide over 6 km/s delta-V capability, greatly increasing delivered mass to Titan when compared to purely propulsive options. This year NASA has chosen to continue study of a Titan/Saturn System Mission, but with new ground rules that encourage a quick flight time to Titan while precluding the use of aerocapture. Further direction includes performing Saturn system science (including Enceladus) in addition to purely Titan-focused investigations, as well as a requirement to provide accommodation for a European-provided in-situ vehicle that would be delivered to Titan by the orbiter spacecraft. The financial cap for the US portion of the mission has been set at $2.1B (FY07). The sum of these constraints has resulted in a complete redesign of the Titan mission and flight system, the most notable changes being driven by the necessity of providing a large onboard chemical delta-v capability to take the place of aerocapture. Responding to these constraints, the JPL-APL-ESA/ESTEC team has developed a concept that meets study ground rules and provides an extremely valuable post-Cassini exploration of Titan and the Saturn system. This paper presents an introduction to the challenges, the trades and the resulting mission and flight system concept being developed for this potential outer planets flagship mission.NAS