Light scattering measurements were performed on the binary liquid mixture carbon tetrachloride–perfluoromethylcyclohexane at its critical concentration and immediately above its critical consolute temperature. Measurements of time averaged intensities as a function of scattering angle and temperature distance from the critical consolute temperature, T−Tc, yielded the critical parameters γ = 1.220±0.018, ξ0 = 2.28±0.21 Å, and ν = 0.626±0.013. Here γ describes the temperature dependence of the susceptibility χ according to the relation χ∝ε−γ, where ε = (T−Tc)/Tc. ξ0 and ν characterize the correlation length with ξ = ξ0ε−ν, which is a measure of the spatial extent of local concentration fluctuations. These values of γ and ν agree well with the scaling and universality hypothesis. Time dependence of the intensity as a function of scattering angle and of T−Tc was determined by measuring the photocurrent autocorrelation function. These measurements yielded decay rates for concentration fluctuations. Combination of decay rates, correlation lengths, and viscosities allowed a direct comparison with the mode–mode coupling theory of Kawasaki. Excellent coincidence of theory and experiment was found except in the vicinity of Kξ = 1, where decay rates were high when compared to theory. K is the magnitude of the momentum transfer vector. Sources of error in the critical parameters obtained from light scattering intensity measurements were analyzed in detail. A useful equation is derived which relates the actual scattering angle inside a cylindrical cell to eight experimental parameters including five ’’alignment’’ parameters which are subject to error. Graphical criteria are presented for estimating uncertainties in critical parameters γ, ξ0, ν, and η.

Objective Turn sections represent the second largest part of total race time in 1500 m freestyle races and may substantially affect race results. Therefore, the aim of the study was to investigate individual race strategies and compare the effect of start, swim, and turn performances between short-course and long-course races. Video footages were collected from all 16 male finalists at the 2018 short and 2019 long-course World swimming championships (age 23.06 ± 2.3 years, FINA points 941 ± 42) for subsequently analysis of start, turn, and swim performance. Results The larger number of turns in short-course races resulted in significantly faster race times (p = 0.004), but slower mean turn times compared to long-course races (p < 0.001). Total race velocity closely correlated with swim and turn but not start section velocity in short- (r ≥ 0.80, p ≤ 0.017) and long-course races (r ≥ 0.83, p ≤ 0.011). Analysis of individual race strategies showed that turn performance affected race results in 6 (75%) and 3 (37.5%) of the 8 world-best 1500 m swimmers in short-course and long-course races, respectively. Medal standing was improved for 1st, 3rd, and 4th ranked short- as well as 1st and 2nd ranked long-course finalist. Coaches, athletes, and performance analysts may carefully consider the importance of turn performance additionally to free-swimming skills.

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Objective Turn sections represent the second largest part of total race time in 1500 m freestyle races and may substantially affect race results. Therefore, the aim of the study was to investigate individual race strategies and compare the effect of start, swim, and turn performances between short-course and long-course races. Video footages were collected from all male finalists at the 2018 short- (n = 8, age 22.8 ± 2.4 years, FINA points 953 ± 27) and 2019 long-course World swimming championships (n = 8, age 23.3 ± 2.2 years, FINA points 951 ± 23) for subsequently analysis of start, turn, and swim performance. Results The larger number of turns in short-course races resulted in significantly faster race times (p < 0.001), but slower mean turn times compared to long-course races (p < 0.001). Total race time closely correlated with swim and turn but not start section time in short- (r ≥ 0.76, p ≤ 0.030) and long-course races (r ≥ 0.96, p < 0.001). Analysis of individual race strategies showed that turn performance affected race results in 9 of the 16 world-best 1500 m swimmers and improved medal standing of 1st, 3rd, and 4th ranked short- as well as 1st and 2nd ranked long-course finalist. Coaches, athletes, and performance analysts may carefully consider the importance of turn performance additionally to free-swimming skills.