Fate and transport of coastal driftwood: A critical review.

Driftwood originating from natural and anthropogenic sources is abundant in coastal regions and plays an important role in ecosystems, providing habitat, structure, nutrients, and carbon storage. Conversely, large accumulations of driftwood can litter coastal zones, negatively impact coastal ecosystems and pose hazards to navigation, infrastructure and communities. Knowledge of the processes underlying the fate and transport of coastal driftwood is therefore needed to inform sustainable management practices. The present state of understanding is limited, and predominantly founded on studies of rivers and tsunamis, where the spatio-temporal scales and driving processes are significantly different from typical climatic or storm conditions in coastal waters. The authors critically review research on fate and transport of driftwood in coastal waters, and identify research needs and opportunities. Key knowledge gaps relate to: interactions between driftwood, littoral zone hydrodynamics and geomorphology; mechanisms of driftwood rafting and accumulation; and influence of weathering and degradation on mobility.

Lane bias in elite-level swimming competition.

Performance outcomes at the 2013 World Swimming Championship were previously shown to be biased depending on the swimmer's lane assignment. The purpose of this study was to determine if this kind of bias was unique, and if not, if the bias was related to the temporary or permanent nature of the pool. The effect of lane on the average odd-length split minus the preceding even-length split in the 800- and 1500-m freestyle events, and on the relative change from qualifying to preliminary performance in the 50-m events, was determined for 16 other elite-level competitions. Depending on the swimmers' direction, split times were on average 0.16 s slower or faster in at least one lane at each of the 16 competitions, and in 49% of all lanes analysed. In 5 competitions, swimmers were shown to be faster in a majority of lanes in one direction as compared to the other. Analysis of the 50-m events at these 5 competitions indicate that preliminary performances were between 0.5 and 0.9% slower or faster than qualifying times, which is consistent with the direction effect observed in the distance freestyle events. Further, lane biases occur more often in temporary pools (70% of lanes) than in permanent pools (35% of lanes), with water currents as the most plausible cause. The prevalence of lane bias at elite-level swimming competition highlights the need for the implementation of policies and procedures to prevent such bias from occurring again in the future.

Large N: a strategy for improving regional sport performance.

UNLABELLED: It has been hypothesized that large differences in maximal performance can arise between various geopolitical regions solely on the basis of differing numbers of participants in the target activity. While there is evidence in support of this hypothesis for a measure of intellectual performance, the same relationship has not been examined for a measure of physical performance. PURPOSE: To determine whether the number of participants is a predictor of the best athletic performance in a region. METHODS: The 2005-2010 USA Swimming Age Group Detail reports were used to determine the number of competitive swimmers participating in each age group for the 59 local swimming communities in the United States. The USA Swimming performance database provided 50-yd-freestyle times in each community for boys and girls for each age (6-19 y). Simple linear regression was used to examine the relationship between the outcome variable (fastest time) and the predictor variable (log of the number of swimmers) for each combination of age, sex, and calendar year. RESULTS: The log of the number of swimmers in a region was a significant predictor of the best performance in that region for all 168 combinations of age, sex, and calendar year (P<.05) and explained, on average, 41%, and as much as 62%, of the variance in the fastest time. CONCLUSION: These findings have important implications for the development of regional sport strategic policy. Increasing the number of participants in the target activity appears a viable strategy for improving regional performance.

Current controversy: analysis of the 2013 FINA World Swimming Championships.

UNLABELLED: Anecdotal reports regarding the 2013 Fédération Internationale de Natation World Swimming Championships held in Barcelona suggested that swimming performances were biased, presumably because of a current. PURPOSE: The purpose of this study was to analyze the swimmers' performance data to determine the merit of these rumors. METHODS: The mean time difference between odd and even 50-m lengths for each lane in the 1500-m freestyle was compared. For each 50-m event, a percent change in performance from the preliminaries to semifinals and semifinals to finals was calculated for all qualifying swimmers. Observations were grouped according to the swimmers' lane assignments. RESULTS: For the 1500-m freestyle, lane assignment significantly affected the time difference between odd and even 50-m lengths (P < 0.001). The change in performance for the 50-m events was also affected by lane assignment (P < 0.001). When swimmers transitioned from lanes 1-4 for their first swim (preliminaries or semifinals) to lanes 5-8 for their second (semifinals or finals), their performance time improved by 1.11% (95% confidence interval, 0.82%-1.41%), which was significantly greater than any other lane change scenario. When swimmers were in lanes 5-8 for their first swim and lanes 1-4 for their second, their performance time was slower by 0.59% (95% confidence interval, 0.39%-0.80%), which was significantly worse than any other lane change combination. CONCLUSIONS: Swimmers were advantaged or disadvantaged depending on the direction and lane in which they swam. The existence of a current is the only cause that we can propose to explain these findings. Because one of Fédération Internationale de Natation's primary stated objectives is to provide fairness in competition, new policies are needed to prevent similar biases from occurring in the future.