Concept: Nautical mile
Plastic marine pollution in the open ocean of the southern hemisphere is largely undocumented. Here, we report the result of a (4489km) 2424 nautical mile transect through the South Pacific subtropical gyre, carried out in March-April 2011. Neuston samples were collected at 48 sites, averaging 50 nautical miles apart, using a manta trawl lined with a 333μm mesh. The transect bisected a predicted accumulation zone associated with the convergence of surface currents, driven by local winds. The results show an increase in surface abundance of plastic pollution as we neared the center and decrease as we moved away, verifying the presence of a garbage patch. The average abundance and mass was 26,898particles km(-2) and 70.96gkm(-2), respectively. 88.8% of the plastic pollution was found in the middle third of the samples with the highest value of 396,342particles km(-2) occurring near the center of the predicted accumulation zone.
Match Analysis of U9 and U10 English Premier League Academy Soccer Players using a Global Positioning System: Relevance for Talent Identification and Development
- Journal of strength and conditioning research / National Strength & Conditioning Association
- Published over 7 years ago
The purpose of this study was to examine the match activity profile of U9 and U10 elite soccer players and to establish if there were any differences between players who were subsequently retained or released by their clubs. Such information should prove valuable in the design of training programs for these very young players and in the talent identification and development process. A Global Positioning System was used to analyze 2-4 inter-academy 6-a-side matches of English Premier League Academy players (U9: N = 22 and U10: N = 12) who trained three times a week (4.5 h) . Speed zones were created based on 5 and 10 m sprint times and an independent sample t-test was employed for a statistical analysis.Both squads covered ∼4000 m in total or ∼4700 m·h during a match (NS between squads), with the U10s tending to cover a greater distance at moderate (p = 0.10) and high speeds (p = 0.08) than the U9s. Retained group covered a greater distance than released group (retained vs. released: 4478 ± 513 m vs. 4091 ± 462 m, p < 0.05) during a match and covered a greater distance during low speed running in absolute (1226 ± 259 m vs. 1005 ± 221 m, p < 0.05) and relative (1325 ± 235 m[BULLET OPERATOR]h vs. 1132 ± 210 m[BULLET OPERATOR]h, p < 0.05) terms.Thus, U9 and U10 players cover over 4000 m in match play and those players who are retained by academies cover a greater distance in total and at low speeds (2.1-3.1 m·s). This information may support the preparation of squad training programs and the talent identification and development process.
The environmental risks of 22 contaminants, comprising 6 metals, 10 PAHs and 6 PCB congeners occurring in UK estuaries and coastal waters were assessed as single substances. Sediment samples were taken within 12 nautical miles of the English and Welsh coastlines between 1999 and 2011. The measured environmental concentrations were compared to quality standards including ERL, ERM and EAC, all of which have been established internationally. Out of a total of 38,031 individual samples analysed, 42.6% and 7.7% exceeded the ERL/EAC and ERM values, respectively. The highest Risk Characterisation Ratios (RCRs) for metals, PAHs and PCBs were observed for copper, fluorene and CB118 (2,3',4,4',5-pentachlorobiphenyl). In general, the highest concentrations of PAHs and PCBs were observed in 2011 in the Lower Medway indicating a potential risk to the aquatic environment. This study suggests that re-suspension of contaminants banned over 20years ago is still an ongoing issue.
Fiber materials with different structural features, which in many cases endow the fibers extraordinary functions, are drawing considerable attention from biomedical and material researchers. Here, perfusable necklace-like knotted microfibers are presented for the first time. Additionally, a novel microfluidic spinning method facilitates the production of variable knots and channels. Not only spindle-, but also hemisphere- and petal-knotted microfibers can be controllably fabricated. Generation and perfusion of both Janus channels and helical channel in the knotted microfibers are also shown. With no need of oil and surfactant, the spinning process is highly cytocompatible. The potential bioengineering and biomedical application of the knotted hollow microfiber is demonstrated by its cell-encapsulation feasibility and the unique liver acinus-like diffusion gradient in the knot. The merits of perfusability, cytocompatibility, and structural diversity of the microfibers may open more avenues for further material and biomedical investigation.
Hull biofouling is a well-known problem for the shipping industry, leading to increased resistance and fuel consumption. Considering that the effects of hull form on resistance are known to be higher for a less slender hull, it is hypothesised in this paper that the effect of biofouling roughness on resistance is also dependent on the hull form. To test this hypothesis, previously reported full-scale numerical results on a containership are re-analysed. Form effects on roughness penalties, corresponding to KΔCT = 0.058 ± 0.025, are observed at a low speed (19 knots, Res = 2.29 × 109), which are however cancelled out by traditionally neglected roughness effects on wave-making resistance at a higher speed (24 knots, Res = 2.89 × 109). It is concluded that hull form effects on biofouling penalties can be significant at low speeds, though not generalisable for higher speeds, namely when wave-making resistance corresponds to ≥ 29% of total resistance.
An experiment comparing the location accuracy of gravity matching-aided navigation in the ocean and simulation is very important to evaluate the feasibility and the performance of an INS/gravity-integrated navigation system (IGNS) in underwater navigation. Based on a 1' × 1' marine gravity anomaly reference map and multi-model adaptive Kalman filtering algorithm, a matching location experiment of IGNS was conducted using data obtained using marine gravimeter. The location accuracy under actual ocean conditions was 2.83 nautical miles (n miles). Several groups of simulated data of marine gravity anomalies were obtained by establishing normally distributed random error N ( u , σ 2 ) with varying mean u and noise variance σ 2 . Thereafter, the matching location of IGNS was simulated. The results show that the changes in u had little effect on the location accuracy. However, an increase in σ 2 resulted in a significant decrease in the location accuracy. A comparison between the actual ocean experiment and the simulation along the same route demonstrated the effectiveness of the proposed simulation method and quantitative analysis results. In addition, given the gravimeter (1-2 mGal accuracy) and the reference map (resolution 1' × 1'; accuracy 3-8 mGal), location accuracy of IGNS was up to reach ~1.0-3.0 n miles in the South China Sea.
The variation of a marine gravity anomaly reference map is one of the important factors that affect the location accuracy of INS/Gravity integrated navigation systems in underwater navigation. In this study, based on marine gravity anomaly reference maps, new characteristic parameters of the gravity anomaly were constructed. Those characteristic values were calculated for 13 zones (105°-145° E, 0°-40° N) in the Western Pacific area, and simulation experiments of gravity matching-aided navigation were run. The influence of gravity variations on the accuracy of gravity matching-aided navigation was analyzed, and location accuracy of gravity matching in different zones was determined. Studies indicate that the new parameters may better characterize the marine gravity anomaly. Given the precision of current gravimeters and the resolution and accuracy of reference maps, the location accuracy of gravity matching in China’s Western Pacific area is ~1.0-4.0 nautical miles (n miles). In particular, accuracy in regions around the South China Sea and Sulu Sea was the highest, better than 1.5 n miles. The gravity characteristic parameters identified herein and characteristic values calculated in various zones provide a reference for the selection of navigation area and planning of sailing routes under conditions requiring certain navigational accuracy.
Canada’s third-generation HFSWR forms the foundation of a maritime domain awareness system that provides enforcement agencies with real-time persistent surveillance out to and beyond the 200 nautical mile exclusive economic zone (EEZ). Cognitive sense-and-adapt technology and dynamic spectrum management ensures robust and resilient operation in the highly congested High Frequency (HF) band. Dynamic spectrum access enables the system to simultaneously operate on two frequencies on a non-interference and non-protected basis, without impacting other spectrum users. Sense-and-adapt technologies ensure that the system instantaneously switches to a new vacant channel on the detection of another user or unwanted jamming signal. Adaptive signal processing techniques mitigate against electrical noise, interference and clutter. Sense-and-adapt techniques applied at the detector and tracker stages maximize the probability of track initiation whilst minimizing the probability of false or otherwise erroneous track data.
The number of validation studies of commercially available foot pods that provide estimates of running speed is limited and these studies have been conducted under laboratory conditions. Moreover, internal data handling and algorithms used to derive speed from these pods are proprietary and thereby unclear. The present study investigates the use of foot contact time (CT) for running speed estimations, which potentially can be used in addition to the global positioning system (GPS) in situations where GPS performance is limited. CT was measured with tri axial inertial sensors attached to the feet of 14 runners, during natural over ground outdoor running, under optimized conditions for GPS. The individual relationships between running speed and CT were established during short runs at different speeds on two days. These relations were subsequently used to predict instantaneous speed during a straight line 4 km run with a single turning point halfway. Stopwatch derived speed, measured for each of 32 consecutive 125m intervals during the 4 km runs, was used as reference. Individual speed-CT relations were strong (r2 >0.96 for all trials) and consistent between days. During the 4km runs, median error (ranges) in predicted speed from CT 2.5% (5.2) was higher (P<0.05) than for GPS 1.6% (0.8). However, around the turning point and during the first and last 125m interval, error for GPS-speed increased to 5.0% (4.5) and became greater (P<0.05) than the error predicted from CT: 2.7% (4.4). Small speed fluctuations during 4km runs were adequately monitored with both methods: CT and GPS respectively explained 85% and 73% of the total speed variance during 4km runs. In conclusion, running speed estimates bases on speed-CT relations, have acceptable accuracy and could serve to backup or substitute for GPS during tarmac running on flat terrain whenever GPS performance is limited.
In patients with peripheral artery disease (PAD), the different distances between stops and the stop durations recorded with Global Positioning System (GPS) during a 1 hour stroll in the community are highly variable. Nevertheless, the reliability of the greatest community walk distance (greatest distance), the average of walking speeds (average speed) and the durations of stops (average stop durations) have not been studied.