Explore the vast range of titles available.

The present study aimed to validate and compare the football-specific measurement accuracy of two optical tracking systems engineered by TRACAB. The \"Gen4\" system consists of two multi-camera units (a stereo pair) in two locations either side of the halfway line, whereas the distributed \"Gen5\" system combines two stereo pairs on each side of the field as well as two monocular systems behind the goal areas. Data were collected from 20 male football players in two different exercises (a football sport-specific running course and small-sided games) in a professional football stadium. For evaluating the accuracy of the systems, measures were compared against simultaneously recorded measures of a reference system (VICON motion capture system). Statistical analysis uses RMSE for kinematic variables (position, speed and acceleration) and the difference in percentages for performance indicators (e.g. distance covered, peak speed) per run compared to the reference system. Frames in which players were obviously not tracked were excluded. Gen5 had marginally better accuracy (0.08 m RMSE) for position measurements than Gen4 (0.09 m RMSE) compared to the reference. Accuracy difference in instantaneous speed (Gen4: 0.09 m⋅s-1 RMSE; Gen5: 0.08 m⋅s-1 RMSE) and acceleration (Gen4: 0.26 m⋅s-2 RMSE; Gen5: 0.21 m⋅s-2 RMSE) measurements were significant, but also trivial in terms of the effect size. For total distance travelled, both Gen4 (0.42 ± 0.60%) and Gen5 (0.27 ± 0.35%) showed only trivial deviations compared to the reference. Gen4 showed moderate differences in the low-speed distance travelled category (-19.41 ± 13.24%) and small differences in the high-speed distance travelled category (8.94 ± 9.49%). Differences in peak speed, acceleration and deceleration were trivial (<0.5%) for both Gen4 and Gen5. These findings suggest that Gen5's distributed camera architecture has minor benefits over Gen4's single-view camera architecture in terms of accuracy. We assume that the main benefit of the Gen5 towards Gen4 lies in increased robustness of the tracking when it comes to optical overlapping of players. Since differences towards the reference system were very low, both TRACAB's tracking systems can be considered as valid technologies for football-specific performance analyses in the settings tested as long as players are tracked correctly.

The purpose of this study was to assess the measurement accuracy of the most commonly used tracking technologies in professional team sports (i.e., semi-automatic multiple-camera video technology (VID), radar-based local positioning system (LPS), and global positioning system (GPS)). The position, speed, acceleration and distance measures of each technology were compared against simultaneously recorded measures of a reference system (VICON motion capture system) and quantified by means of the root mean square error RMSE. Fourteen male soccer players (age: 17.4±0.4 years, height: 178.6±4.2 cm, body mass: 70.2±6.2 kg) playing for the U19 Bundesliga team FC Augsburg participated in the study. The test battery comprised a sport-specific course, shuttle runs, and small sided games on an outdoor soccer field. The validity of fundamental spatiotemporal tracking data differed significantly between all tested technologies. In particular, LPS showed higher validity for measuring an athlete's position (23±7 cm) than both VID (56±16 cm) and GPS (96±49 cm). Considering errors of instantaneous speed measures, GPS (0.28±0.07 m⋅s-1) and LPS (0.25±0.06 m⋅s-1) achieved significantly lower error values than VID (0.41±0.08 m⋅s-1). Equivalent accuracy differences were found for instant acceleration values (GPS: 0.67±0.21 m⋅s-2, LPS: 0.68±0.14 m⋅s-2, VID: 0.91±0.19 m⋅s-2). During small-sided games, lowest deviations from reference measures have been found in the total distance category, with errors ranging from 2.2% (GPS) to 2.7% (VID) and 4.0% (LPS). All technologies had in common that the magnitude of the error increased as the speed of the tracking object increased. Especially in performance indicators that might have a high impact on practical decisions, such as distance covered with high speed, we found >40% deviations from the reference system for each of the technologies. Overall, our results revealed significant between-system differences in the validity of tracking data, implying that any comparison of results using different tracking technologies should be done with caution.

Background The endosymbiotic relationship between Wolbachia bacteria and insects has been of interest for many years due to their diverse types of host reproductive phenotypic manipulation and potential role in the host’s evolutionary history and population dynamics. Even though infection rates are high in Lepidoptera and specifically in butterflies, and reproductive manipulation is present in these taxa, less attention has been given to understanding how Wolbachia is acquired and maintained in their natural populations, across and within species having continental geographical distributions. Results We used whole genome sequencing data to investigate the phylogenetics, demographic history, and infection rate dynamics of Wolbachia in four species of the Spicauda genus of skipper butterflies (Lepidoptera: Hesperiidae), a taxon that presents sympatric and often syntopic distribution, with drastic variability in species abundance in the Neotropical region. We show that infection is maintained by high turnover rates driven mainly by pervasive horizontal transmissions, while also presenting novel cases of double infection by distantly related supergroups of Wolbachia in S. simplicius. Conclusions Our results suggest that Wolbachia population dynamics is host species-specific, with genetic cohesiveness across wide geographical distributions. We demonstrate that low coverage whole genome sequencing data can be used for an exhaustive assessment of Wolbachia infection in natural populations of butterflies, as well as its dynamics in closely related host species. This ultimately leads to a better understanding of the endosymbiotic population dynamics of Wolbachia and its effects on the host’s biology and evolution.

Freshwater pearl mussels (FPMs, Margaritifera margaritifera, Linnaeus, 1758) are endangered and particularly vulnerable to climate change. To create effective conservation strategies, we studied their thermal tolerance and the impact of elevated water temperatures on growth and survival. Our experiments included field mesocosm studies in five FPM-streams in the Vogtland region (Germany) (2016 to 2020), as well as laboratory experiments at temperatures ranging from 1 to 26 °C. Growth of juvenile FPMs increased significantly within a temperature gradient from 12 to 21 °C. In the streams, maximum growth was 8.9 µm/d in surface water and 6.5 µm/d in the interstitial. The upper thermal tolerance for the mussels ranged from 22.1 to 22.9 °C, resulting in low survival during hot summer periods in 2018 and 2019. Warming during winter (+5 °C) did not significantly affect growth and survival, but survival during winter increased with the pre-overwintering shell length. Exceeding a shell length of about 1100 µm in December indicating gill development corelated to 50% survival. Shell length in December is primarily controlled by growth depending on water temperatures during summer. These findings define the thermal niche of juvenile FPMs (average summer temperatures of 14.5–21 °C) and have implications for water management, conservation strategies, and site selection for releasing captive-breeding mussels.

In flying animals, wing morphology is typically assumed to influence flight behaviours. Whether seasonal polymorphism in butterfly morphology is linked to adaptive flight behaviour remains unresolved. Here, we compare the flight behaviours and wing morphologies of the spring and summer forms of two closely related butterfly species, Pieris napi and P. rapae. We first quantify three‐dimensional flight behaviour by reconstructing individual flight trajectories using stereoscopic high‐speed videography in an experimental outdoor cage. We then measure wing size and shape, which are characteristics assumed to influence flight behaviours in butterflies. We show that seasonal, but not interspecific, differences in flight behaviour might be associated with divergent forewing shapes. During spring, Pieris individuals are small and have elongated forewings, and generally fly at low speed and acceleration, while having a high flight curvature. On the contrary, summer individuals are larger and exhibit rounded forewings. They fly at high speed and acceleration, while having high turning acceleration and advance ratio. Our study provides one of the first quantitative pieces of evidence of different flight behaviours between seasonal forms of two Pieris butterfly species. We discuss the possibility that this co‐divergence in flight behaviour and morphology is an adaptation to distinct seasonal environments. Properly identifying the mechanisms underpinning such divergence, nonetheless, requires further investigations to disentangle the interacting effects of microhabitats, predator community, parasitoid pressure and behavioural differences between sexes. Our study focuses on quantifying the flight behaviours of two closely related Pieris white butterflies and their seasonal forms, using high‐speed videography. Our results suggest that there are no interspecific but seasonal differences in flight behaviours. Our study provides quantitative evidence of different flight behaviours between seasonal forms of Pieris butterflies, and these differences were better predicted by forewing shape and size, rather than other factors (e.g. species identity and ambient temperature).

Electronic performance and tracking systems (EPTS) traditionally rely on one of two body positions as the ultimate representative for the entire body in space: the upper torso between the scapulae (GPS- and radar-based systems) or the body’s estimated center (optical and some radar-based systems). The aim of this study was to quantify the impact of the respective reference point upon the resulting kinematic tracking variables. We present a marker-based method comparing center of pelvis (COP) derived tracking variables with center of scapulae (COS) derived tracking variables in a 30 × 30 m (900 m2) VICON measurement area. Fourteen male soccer players completed a running circuit with prescribed team-sport specific movements. Results showed that differences between COP and COS heavily depend on the underlying movement characteristic. Low-speed running showed the lowest deviations whereas accelerated movements and movements with sharp changes in direction lead to a significant increase in the observed differences. Results further showed that COS sprinting distance was on average −44.65% (p < 0.001) lower in comparison to COP. Similarly, maximum speed obtained from COS was −2.94% (p = 0.001) lower in comparison to COP. On the contrary, maximum acceleration values of COS were on average 16.15% (p = 0.02) higher compared to COP. Our work illustrates that the anatomical reference point used to represent the entire body in space needs to be carefully considered in the interpretation of tracking variables delivered by different EPTS.

This study quantified the contribution of game interruptions to the fatigue-related declines in match running performance over the course of a football match. Using a semi-automatic multiple camera system, the running activity of 792 individual German Bundesliga performances was divided into pre-defined 15-minute intervals and subsequently analysed under two prerequisites: with (effective playing time) and without (total playing time) consideration of game interruptions. Results showed a significant decline in effective playing time over the course of a match, from 66.3% of the total playing time in the first 15 minutes to 55.9% in the final 15 minutes of a match. Under consideration of the total playing time, match running performances decreased by 24.2% on average; considering the effective playing time, they decreased on average by only 10.2%. It can, therefore, be concluded that more than half (57.9%) of the commonly reported decline in match running performance cannot be assigned to physical fatigue, but rather to an increase in game interruptions as the game progresses. In conclusion, this study demonstrated for the first time that the decline in players' match running performance during football matches is substantially amplified by a proven increase in game interruptions, indicating that there may be a tendency among practitioners to overestimate fatigue-induced performance declines.

Spatio-temporal parameters like step length, step frequency and ground contact time are directly related to sprinting performance. There is still a lack of knowledge, however, on how these parameters interact. Recently, various algorithms for the automatic detection of step parameters during sprint running have been presented which have been based on data from motion capture systems, video cameras, opto-electronic systems or Inertial measurement units. However, all of these methods suffer from at least one of the following shortcomings: they are (a) not applicable for more than one sprinter simultaneously, (b) only capable of capturing a small volume or (c) do not provide accurate spatial parameters. To circumvent these issues, the radio-based local position measurement system RedFIR could be used to obtain spatio-temporal information during sprinting based on lightweight transmitters attached to the athletes. To assess and optimize the accuracy of these parameters 19 100 m sprints of twelve young elite athletes (age: 16.5 ± 2.3 years) were recorded by a radio-based tracking system and a opto-electronic reference instrument. Optimal filter parameters for the step detection algorithm were obtained based on RMSE differences between estimates and reference values on an unseen test set. Attaching a transmitter above the ankle showed the best results. Bland-Altman analysis yielded 95% limits of agreement of [−14.65 cm, 15.05 cm] for step length [−0.016 s, 0.016 s] for step time and [−0.020 s, 0.028 s] for ground contact time, respectively. RMS errors smaller than 2% for step length and step time show the applicability of radio-based tracking systems to provide spatio-temporal parameters. This creates new opportunities for performance analysis that can be applied for any running discipline taking place within a stadium. Since analysis for multiple athletes is available in real-time this allows immediate feedback to coaches, athletes and media.

The freshwater pearl mussel Margaritifera margaritifera is an endangered bivalve which is usually regarded as sedentary, although individual movement has been observed both vertically and horizontally. Little is known about the causes and rates of mussel movement. The objective of this study was to test the effect of microhabitat characteristics on the horizontal movement distance and rates of freshwater pearl mussels. A total of 120 mussels (length range 40–59 mm) were marked individually with passive integrated transponder tags, placed in stream microhabitats differing in their sediment composition and monitored biweekly over a period of 10 weeks. Mussels situated in sand-dominated habitats had a significantly higher mean movement rate (3.2 ± 4.2 cm/day, mean ± SD) than mussels situated in gravel-dominated (1.9 ± 2.7 cm/day) or stone-dominated habitats (1.8 ± 3.2 cm/day). The direction of the movements appeared random; however, an emigration from sandy habitats was observed, probably to avoid dislodgment from these hydraulically unstable habitats. This study demonstrates that freshwater pearl mussels can actively emigrate from unsuitable microhabitats. Once suitable streams with respect to physical, chemical, and biological quality were identified, it is therefore only necessary to identify suitable mesohabitats (area of 10–30 m2) when reintroducing or relocating mussels.

Large-scale additive manufacturing (LSAM) has been developing a huge potential to address certain tasks in industrial applications over the last years. Particularly granule extrusion technologies enable the processing of an enormous variety of materials but also introduce new challenges in printing large-scale parts. Compared to fused layer modelling and due to larger nozzle diameters as well as higher extrusion rates strand geometry and consequently, process-related voids are enlarged. A promising approach to improve part quality is the integration of carbon dioxide laser (CO 2 ) radiation into the additive manufacturing process to weld deposited strands by increasing the interface temperature. Experiments are conducted for polymethyl methacrylate (PMMA) and styrene-acrylonitrile (SAN) which are very good absorbers of the wavelength 10.6 µm. Due to the locally defined heat treatment, merely certain areas of the strands are heated to a desired temperature. This leads to a more complete diffusion. At the same time, temperature gradients in the overall part are avoided. By means of a thermographic camera, the temperatures at the re-melting process of deposited strands can be precisely monitored. Therefore, the relation between laser intensity and resulting temperature can be transferred into a repeatable process window. The interaction between laser and deposited material leads to a wider contact area between stacked strands. While flexural strength is not significantly affected, compared to specimens manufactured without any heat treatment bending force is increased by 66% (PMMA) and 48% (SAN), respectively. In addition, voids between adjacent strands are reduced by up to 57%.