Women's Rugby League: Positional Groups and Peak Locomotor Demands

The aims of this study were to (a) use a data-based approach to identify positional groups within National Rugby League Women's (NRLW) match-play and (b) quantify the peak locomotor demands of NRLW match-play by positional groups. Microtechnology (Global Navigational Satellite System [GNSS] and integrated inertial sensors; n = 142 files; n = 76 players) and match statistics (n = 238 files; n = 80 players) were collected from all NRLW teams across the 2019 season. Data-based clustering of match statistics was utilized to identify positional clusters through classifying individual playing positions into distinct positional groups. Moving averages (0.5, 1, 2, 3, 5, and 10 min) of peak running and average acceleration/deceleration demands were calculated via microtechnology data for each player per match. All analysis was undertaken in R (R Foundation for Statistical Computing) with positional differences determined via a linear mixed model and effect sizes (ES). Data-based clustering suggested that, when informed by match statistics, individual playing positions can be clustered into one of three positional groups. Based on the clustering of the individual positions, these groups could be broadly defined as backs (fullback, wing, and center), adjustables (halfback, five-eighth, and hooker), and forwards (prop, second-row, and lock). Backs and adjustables demonstrated greater running (backs: ES 0.51–1.00; p < 0.05; adjustables: ES 0.51–0.74, p < 0.05) and average acceleration/deceleration (backs: ES 0.48–0.87; p < 0.05; adjustables: ES 0.60–0.85, p < 0.05) demands than forwards across all durations. Smaller differences (small to trivial) were noted between backs and adjustables across peak running and average acceleration/deceleration demands. Such findings suggest an emerging need to delineate training programs in situations in which individual playing positions train in positional group based settings. Collectively, this work informs the positional groupings that could be applied when examining NRLW data and supports the development of a framework for specifically training female rugby league players for the demands of the NRLW competition.

Global Navigational Satellite System Seismic Monitoring

ABSTRACT We have developed a global earthquake deformation monitoring system based on subsecond-latency measurements from ∼2000 existing Global Navigational Satellite System (GNSS) receivers to rapidly characterize large earthquakes and tsunami. The first of its kind, this system complements traditional seismic monitoring by enabling earthquake moment release and, where station density permits, fault-slip distribution, including tsunamigenic slow slip, to be quantified as rupture evolves. Precise point position time series from globally distributed GNSS stations are continuously estimated within an Earth center of mass-fixed reference frame and streamed as local north, east, and vertical coordinates with 1 s updates and global subsecond receiver-to-positions latency. Continuous waveforms are made available via messaging exchanges to third-party users (U.S. Geological Survey, National Oceanic and Atmospheric Administration, network operators, etc.) and internally filtered to trigger coseismic offset estimation that drive downstream point-source and finite-fault magnitude and slip characterization algorithms. We have implemented a corresponding analytics system to capture ∼100 million positions generated per day per thousand global stations positioned. Assessed over one typical week using 1270 globally distributed stations, the latency of position generation at a central analysis center from time of data acquisition in the field averages 0.52 s and is largely independent of station distance. Position variances from nominal in north, east, and vertical average 8, 9, and 12 cm, respectively, predominantly caused by random-walk noise peaking in a ∼4–5min spectral band introduced by global satellite clock corrections. Solutions completeness over the week within 0.5, 1, and 2 s latency is 55%, 90%, and 99%, respectively. This GNSS analysis platform is readily scalable, allowing the accelerating proliferation of low-cost phase-tracking GNSS receivers, including those increasingly embedded in consumer devices such as smartphones, to offer a new means of characterizing large earthquakes and tsunami far more quickly than existing systems allow.

Determination of SLR station coordinates based on LEO, LARES, LAGEOS, and Galileo satellites

The number of satellites equipped with retroreflectors dedicated to Satellite Laser Ranging (SLR) increases simultaneously with the development and invention of the spherical geodetic satellites, low Earth orbiters (LEOs), Galileo and other components of the Global Navigational Satellite System (GNSS). SLR and GNSS techniques onboard LEO and GNSS satellites create the possibility of widening the use of SLR observations for deriving SLR station coordinates, which up to now have been typically based on spherical geodetic satellites. We determine SLR station coordinates based on integrated SLR observations to LEOs, spherical geodetic, and GNSS satellites orbiting the Earth at different altitudes, from 330 to 26,210 km. The combination of eight LEOs, LAGEOS-1/2, LARES, and 13 Galileo satellites increased the number of 7-day SLR solutions from 10–20% to even 50%. We discuss the issues of handling of range biases in multi-satellite combinations and the proper solution constraining and weighting. Weighted combination is characterized by a reduction of formal error medians of estimated station coordinates up to 50%, and the reduction of station coordinate residuals. The combination of all satellites with optimum weighting increases the consistency of station coordinates in terms of interquartile ranges by 10% of horizontal components for non-core stations w.r.t LAGEOS-only solutions.

Plasma density gradients at the edge of polar ionospheric holes: the presence and absence of phase scintillation

Polar holes were observed in the high-latitude ionosphere during a series of multi-instrument case studies close to the northern hemisphere winter solstice in 2014 and 2015. These holes were observed during geomagnetically quiet conditions and under a range of solar activities using the European Incoherent Scatter Scientific Association (EISCAT) Svalbard Radar (ESR) and measurements from Global Navigational Satellite System (GNSS) satellites. Steep electron density gradients have been associated with phase scintillation in previous studies, however, no enhanced scintillation was detected within the electron density gradients at these boundaries. It is suggested that the lack of phase scintillation may be due to low plasma density levels and a lack of intense particle precipitation. It may be that both significant electron density gradients and that plasma density levels above a certain threshold are required for scintillation to occur.