Sustained swimming of bluefin tuna was analysed from video recordings made of a captive patrolling fish school [lengths (L) 1.7-3.3 m, body mass (M) 54433 kg]. Speeds ranged from 0.6 to 1.2 L s-' (86260 km day-') while stride length during steady speed swimming varied between 0.54 and 0.93 L. Maximum swimming speed was estimated by measuring twitch contraction of the anaerobic swimming muscle in pithed fish 5 min after death. Muscle contraction time increased from the shortest just behind the head (3G50ms at 20% L) to the longest at the tail peduncle (8G90 ms at 80% L) (all at 28" C). A fish (L= 2.26 m) with a muscle contraction time of 50 ms at 25% L can have a maximum tail beat frequency of 10 Hz and maximum swimming speed of 15 m s -I (54 km h-') with a stride length of 0.65 L. With a stride length of 1 L a speed of 22.6 m s-' (81.4 km h-') is possible. Power used at maximum speed was estimated for this fish at between IOand40 kW, withcorrespondingvaluesforthedragcoefficient at a Reynoldsnumber of 4.3 x 10' of 0,0007 and 0.0027.

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Este trabajo tiene como objetivo mostrar y proponer una metodología híbrida de enseñanza-aprendizaje de matemáticas universitarias con las primeras experiencias de un modelo educativo emergente elaborado con base en la “Guía para el retorno a las actividades presenciales en la Universidad Autónoma Metropolitana” (México). Con él se desea probar que la educación presencial y remota ofrecen resultados similares de aprendizaje en matemáticas. Para lograr este objetivo hemos aplicado una propuesta metodológica que combina una clase presencial de matemáticas y una vídeo clase en la sala ZOOM con apoyo de material educativo en Power Point y EXCEL. Tamaño de muestra: 70 estudiantes.

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