SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Track and field athletics

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Four heteropod lizard trackways discovered in the Hasandong Formation (Aptian-early Albian), South Korea assigned to Sauripes hadongensis, n. ichnogen., n. ichnosp., which represents the oldest lizard tracks in the world. Most tracks are pes tracks (N = 25) that are very small, average 22.29 mm long and 12.46 mm wide. The pes tracks show “typical” lizard morphology as having curved digit imprints that progressively increase in length from digits I to IV, a smaller digit V that is separated from the other digits by a large interdigital angle. The manus track is 19.18 mm long and 19.23 mm wide, and shows a different morphology from the pes. The predominant pes tracks, the long stride length of pes, narrow trackway width, digitigrade manus and pes prints, and anteriorly oriented long axis of the fourth pedal digit indicate that these trackways were made by lizards running bipedally, suggesting that bipedality was possible early in lizard evolution.

Concepts: Track and field athletics, South Korea, Length, Numerical digit, Lizard, Dinosaur, Bipedalism, Trackway

28

The Laetoli site (Tanzania) contains the oldest known hominin footprints, and their interpretation remains open to debate, despite over 35 years of research. The two hominin trackways present are parallel to one another, one of which is a composite formed by at least two individuals walking in single file. Most researchers have focused on the single, clearly discernible G1 trackway while the G2/3 trackway has been largely dismissed due to its composite nature. Here we report the use of a new technique that allows us to decouple the G2 and G3 tracks for the first time. In so doing we are able to quantify the mean footprint topology of the G3 trackway and render it useable for subsequent data analyses. By restoring the effectively ‘lost’ G3 track, we have doubled the available data on some of the rarest traces directly associated with our Pliocene ancestors.

Concepts: Time, Arithmetic mean, Track and field athletics, Open set, Ecological footprint, Footprint, 2002 in music, Trackway

27

Gait recognition can potentially provide a noninvasive and effective biometric authentication from a distance. However, the performance of gait recognition systems will suffer in real surveillance scenarios with multiple interacting individuals and where the camera is usually placed at a significant angle and distance from the floor. We present a methodology for view-invariant monocular 3-D human pose tracking in man-made environments in which we assume that observed people move on a known ground plane. First, we model 3-D body poses and camera viewpoints with a low dimensional manifold and learn a generative model of the silhouette from this manifold to a reduced set of training views. During the online stage, 3-D body poses are tracked using recursive Bayesian sampling conducted jointly over the scene’s ground plane and the pose-viewpoint manifold. For each sample, the homography that relates the corresponding training plane to the image points is calculated using the dominant 3-D directions of the scene, the sampled location on the ground plane and the sampled camera view. Each regressed silhouette shape is projected using this homographic transformation and is matched in the image to estimate its likelihood. Our framework is able to track 3-D human walking poses in a 3-D environment exploring only a 4-D state space with success. In our experimental evaluation, we demonstrate the significant improvements of the homographic alignment over a commonly used similarity transformation and provide quantitative pose tracking results for the monocular sequences with a high perspective effect from the CAVIAR dataset.

Concepts: Dimension, Manifold, Track and field athletics, Camera, Gait analysis, Facial recognition system, Biometrics, Möbius transformation

23

The purpose of this study was to assess the veracity of the Court of Arbitration for Sport’s assertion that sex-differences in athletic performance in elite-standard track and field competition is of the order of 10-12%. Exponential curves were fitted to the data of selected track and field events of the finals of all IAAF World Championships and Olympic Games from 1983 to 2016. For each curve, the coefficient of determination R(2) was calculated, in combination the corresponding 95% confidence intervals for the curve constants. Sex-differences were evaluated via differences in the fitted curves between men and women. Mean performances of winners, as well as overall performance means of all participants, were also analyzed. The calculated sex-difference was 8.2 ± 1.0% - 11.8 ± 2.1% for sprints, 10.3 ± 3.3% - 12.8 ± 4.0% for middle and long-distance events, 9.7 ± 2.9% - 13.1 ± 2.9% for relays and 14.2 ± 2.2% - 25.0 ± 4.4% for jumps. This study therefore confirms that the percentage difference accepted by the CAS is appropriate for elite-standard track and field events.

Concepts: Olympic Games, Normal distribution, Track and field athletics, Summer Olympic Games, Ancient Olympic Games, Olympic sports, Pentathlon, IAAF World Championships in Athletics

23

To develop an efficient nanotechnology fluorescence-based method to track cell proliferation to avoid the limitations of current cell-labeling dyes.

Concepts: Tracking, Track and field athletics

18

For centuries, the mechanisms surrounding spatially complex animal migrations have intrigued scientists and the public. We present a new methodology using ocean heat content (OHC), a habitat metric that is normally a fundamental part of hurricane intensity forecasting, to estimate movements and migration of satellite-tagged marine fishes. Previous satellite-tagging research of fishes using archival depth, temperature and light data for geolocations have been too coarse to resolve detailed ocean habitat utilization. We combined tag data with OHC estimated from ocean circulation and transport models in an optimization framework that substantially improved geolocation accuracy over SST-based tracks. The OHC-based movement track provided the first quantitative evidence that many of the tagged highly migratory fishes displayed affinities for ocean fronts and eddies. The OHC method provides a new quantitative tool for studying dynamic use of ocean habitats, migration processes and responses to environmental changes by fishes, and further, improves ocean animal tracking and extends satellite-based animal tracking data for other potential physical, ecological, and fisheries applications.

Concepts: Statistics, Energy, Fish, Temperature, Thermodynamics, Human migration, Track and field athletics, Geolocation

17

The commonly used muscle injury grading systems based on three grades of injury, representing minor, moderate and complete injuries to the muscle, are lacking in diagnostic accuracy and provide limited prognostic information to the clinician. In recent years, there have been a number of proposals for alternative grading systems. While there is recent evidence regarding the prognostic features of muscle injuries, this evidence has not often been incorporated into the grading proposals. The British Athletics Muscle Injury Classification proposes a new system, based on the available evidence, which should provide a sound diagnostic base for therapeutic decision-making and prognostication. Injuries are graded 0-4 based on MRI features, with Grades 1-4 including an additional suffix ‘a’, ‘b’ or ‘c’ if the injury is ‘myofascial’, ‘musculo-tendinous’ or ‘intratendinous’. Retrospective and prospective studies in elite track and field athletes are underway to validate the classification for use in hamstring muscle injury management. It is intended that this grading system can provide a suitable diagnostic framework for enhanced clinical decision-making in the management of muscle injuries and assist with future research to inform the development of improved prevention and management strategies.

Concepts: Grade, Injuries, Injury, Proposal, Proposals, Track and field athletics

16

To investigate the impact of training modification on achieving performance goals. Previous research demonstrates an inverse relationship between injury burden and success in team sports. It is unknown whether this relationship exists within individual sport such as athletics.

Concepts: Track and field athletics

14

Enhancing our understanding of athlete development would be valuable for coaches, parents and administrators to set realistic performance expectations and to advance youth sport policy. To this end, a database of track and field performances was examined. Records of 134,313 performances by athletes aged between 12 and 35 years in sprinting, throwing, jumping and middle distance events were analysed. Results revealed that a minority (Male, 9%; Female, 13%) of top 20 ranked senior athletes were also ranked in the top 20 at Under 13 (U13). These results were supported by the finding that a minority of athletes retained their top 20 ranking at subsequent age grades (36.3% U13-U15; 23% U13-U17; 13% U13-U20; 43.3% U15-U17; 22.1% U15-U20; 41.8% U17-U20). By U20, less than 30% of athletes who had been ranked in the top 20 at U13 were still listed on the national rankings. Examining a broader sample of athletes revealed weak to moderate correlations between performances at different age grades until at least Under 17-Under 20. These findings reinforce the message that excelling at youth level in competitive athletics is not a prerequisite for senior success.

Concepts: Non-parametric statistics, Ranking, Track and field athletics, Heptathlon, Sprint, 60 metres, Middle distance track event

12

LIDAR-based analyses of the first theropod dinosaur trackways known from the state of Arkansas, USA are reported. The trackways were found on a limestone bedding plane in the Albian De Queen Formation in an active gypsum quarry. Because limited access precluded thorough field study, fieldwork focused on preserving the entire site digitally with ground-based LIDAR, and detailed measurements were later taken digitally from point cloud data. The site contains eight tridactyl trackways associated with sauropod trackways and numerous isolated tracks. Although there appear to be two different tridactyl morphotypes, we show that the tracks are all likely from a single species of trackmaker. We apply a simple method of estimating substrate consistency by comparing the differences between true track dimensions and apparent track dimensions. The tridactyl tracks at the southern end of the site are preserved with significantly greater differences in true vs. apparent dimensions and are shallower than the rest of the tridactyl tracks at the site, which we interpret as the result of outward expansion of the soft tissues of the foot upon contact with a firm substrate. We interpret the firm substrate as having high bulk density and high shear strength, which also explain associated manus-only sauropod tracks. We show that the tridactyl tracks are likely from theropod trackmakers and that footprint lengths, trackway paces, stride lengths, and pace angulations of the De Queen trackways are statistically indistinguishable from equivalent measurements of theropod trackways in the Glen Rose Formation. The Glen Rose tracks are attributed to the large-bodied theropod, Acrocanthosaurus and we likewise attribute the De Queen tracks to Acrocanthosaurus, which is known from skeletal remains in temporally equivalent units and from the mine itself.

Concepts: Track and field athletics, Dinosaur, Saurischia, Theropoda, Deinonychus, Spinosaurus, Trackway, Acrocanthosaurus