Self-similarity of solitary waves on inertia-dominated falling liquid films

We propose consistent scaling of solitary waves on inertia-dominated falling liquid films, which accurately accounts for the driving physical mechanisms and leads to a self-similar characterization of solitary waves. Direct numerical simulations of the entire two-phase system are conducted using a state-of-the-art finite volume framework for interfacial flows in an open domain that was previously validated against experimental film-flow data with excellent agreement. We present a detailed analysis of the wave shape and the dispersion of solitary waves on 34 different water films with Reynolds numbers Re=20–120 and surface tension coefficients σ=0.0512–0.072Nm−1 on substrates with inclination angles β=19◦ − 90◦. Following a detailed analysis of these cases we formulate a consistent characterization of the shape and dispersion of solitary waves, based on a newly proposed scaling derived from the Nusselt flat film solution, that unveils a self-similarity as well as the driving mechanism of solitary waves on gravity-driven liquid films. Our results demonstrate that the shape of solitary waves, i.e., height and asymmetry of the wave, is predominantly influenced by the balance of inertia and surface tension. Furthermore, we find that the dispersion of solitary waves on the inertia-dominated falling liquid films considered in this study is governed by nonlinear effects and only driven by inertia, with surface tension and gravity having a negligible influence

Psychological effects of gamified didactics with exergames in Physical Education at primary schools: Results from a natural experiment

The physical effects of exergaming have been proven, but less is known about the psychological effects in elementary schools that make exergames an effective educational tool. The application of gamification to education is still an emerging practice that has been barely studied. The aim of this study was to analyse the effects of a gamified exergaming intervention in Physical Education classes in primary schools on psychological variables like motivation, flow, basic psychological needs and academic performance. A natural experiment with a non-randomised controlled design was run. The participants were recruited from four schools (n = 417), and received traditional didactic intervention or a gamified exergaming intervention. Both lasted 1 month. The results showed better positive gamified exergaming effects on basic psychological needs, academic performance and some flow dimensions. No interaction effects were found in intrinsic motivation, external regulation and amotivation, although specific improvements in the gamified exergaming group are discussed. The Mechanics-Dynamics-Aesthetics gamification model and the Just Dance Now exergame may be resources capable of producing positive psychological effects on school-based Physical Education

Differences in oral health status in elite athletes according to sport modalities

Oral health status may affect physical and sports performance. The purpose of this study was to assess the oral health status and oral health habits of elite athletes according to the performed sports type. A sample of 186 elite athletes divided into individual sports (n = 74; 53 men and 21 women; 24.9 ± 9.3 years) and team sports (n = 112; 97 men and 15 women; 24.5 ± 4.8 years) participated in the study. The decayed, missing, and filled teeth index (DMFT), the oral health impact profile (OHIP), and the diet assessment of caries risk (DACR) were evaluated to assess their oral health status. Athletes in individual modalities had a lower number in total teeth, healthy teeth, and restoration index (p < 0.05). Furthermore, this group showed a greater number of missing (p < 0.001) and decayed teeth (p < 0.05) and a greater DMFT index (p < 0.001). A relationship between sports modality and prevalence of malocclusions (p < 0.01), periodontal plaque (p < 0.05), and the habit of consuming energy drinks (p < 0.05) was also highlighted. Elite athletes who compete in individual sports presented a worse oral situation

Benefits of regular table tennis practice in body composition and physical fitness compared to physically active children aged 10–11 years

The aim of this study was to identify the differences in body composition and physical fitness between children who played table tennis regularly during a two-year period compared to physically active children who were not engaged in a regular activity. Three hundred seventy-four children aged 10 to 11 years were divided into two groups: table tennis players (n = 109 boys and 73 girls) and physically active group (n = 88 boys and 104 girls). Anthropometric analysis included body mass index, skinfolds, perimeters and bone diameters. Somatotype and body composition were determined according to age-specific equations. Physical fitness assessment included hand grip dynamometry (strength), sit-and-reach test (range of movement) and maximal multistage 20 m shuttle run test (cardiovascular fitness). The result show that children who regularly played table tennis had greater bone development and superior physical fitness compared to those who were physically active but not engaged in a regular physical activity. This is the largest study to date presenting data about the potential of table tennis to benefit health in children. These results constitute an important first step in clarifying the effectiveness of table tennis as a health-promotion strategy to encourage children to undertake regular physical activity and limit sedentary behavior

Uniformity transition for ray intensities in random media

This paper analyses a model for the intensity of distribution for rays propagating without absorption in a random medium. The random medium is modelled as a dynamical map. After N iterations, the intensity is modelled as a sum S of N contributions from different trajectories, each of which is a product of N independent identically distributed random variables xk, representing successive focussing or de-focussing events. The number of ray trajectories reaching a given point is assumed to proliferate exponentially: N=ΛN, for some Λ>1. We investigate the probability distribution of S. We find a phase transition as parameters of the model are varied. There is a phase where the fluctuations of S are suppressed as N → ∞, and a phase where the S has large fluctuations, for which we provide a large deviation analysis

Efectos de un entrenamiento pliométrico sobre el rendimiento en la salida de natación en deportistas adolescentes

En la natación el rendimiento depende de diversos factores atendiendo a la distancia de la prueba. La fuerza explosiva puede resultar un elemento clave en pruebas de distancia corta por su relevancia en la fase de salida. El objetivo de este estudio fue analizar la efectividad que posee un entrenamiento pliométrico sobre la fuerza explosiva del tren inferior y su posible transferencia en el rendimiento de la fase de salida. 16 nadadores adolescentes fueron distribuidos aleatoriamente en dos grupos: control (GC) y experimental (GE). El GC realizó un entrenamiento de fuerza resistencia del tren inferior y el GE de pliometría. Tras 6 semanas se analizaron diferentes variables físicas (CMJ y ABK) y cinemáticas (ángulo de salida, ángulo de entrada al agua, distancia de salto, tiempo de vuelo y tiempo en 5 m). El análisis intragrupo no mostró cambios en el GC mientras que el GE experimentó un incremento en la altura de los saltos CMJ (p<0,005) y ABK (p<0,001), y en la variable técnica del ángulo de salida (p<0,03). En las comparaciones intergrupo el GE aumentó el ángulo de salida (p<0,05). El entrenamiento pliométrico mejora la altura de salto vertical pudiendo tener una transferencia positiva sobre el rendimiento de la salida de natación. Se hace necesaria la realización de nuevos estudios en donde se corroboren los resultados obtenidos en esta investigación

Positive attitudes towards racquet sport of primary school teachers

The aim of this study was to know the attitudes towards racquet sports in Spanish primary school teachers. Eighty one teachers from Zaragoza participated in this study, filling out the scale Positive attitudes towards racquet sport of the validated Table Tennis Attitudes Questionnaire. The internal consistency of this scale was measured with the Cronbach alpha coefficient. The results indicate Md=2.19 (SD=0.38) in this scale. The 27.2% of the teachers have never done one training course of this kind of sports, being the badminton the most studied sport. However, the teachers have mainly badminton teaching material. This study shows which is the prevalence of the racquet sports in the teacher programs. Statistically significant relationships were found between the studies of the teachers or the kind of the school, and the attitudes towards racquet sport. The results of this study suggest us that there have to be more educative programs to implementation racquet sports

Effect of ethylene on postharvest strawberry fruit tissue biochemistry

The effect of continuous ethylene supplementation (50 µL L-1) on cold-stored strawberry fruit physiology and biochemistry, including phytohormone (abscisic acid) metabolism was investigated. In comparison with control fruit which exhibited high sucrose and malic acid contents during storage, ethylene-treated fruits showed increased respiration, sucrose hydrolysis and concomitant reducing sugars accumulation. Ethylene supplementation did not have any effect on phenolic profile. ABA biosynthesis, in both flesh and achenes, was promoted by ethylene. The results herein suggest that controlling ethylene after harvest could suppress senescence and extend shelf-life

Gender differences in neuromuscular, haematological, and urinary responses during padel matches

Research on the acute physiological response to a padel match is limited. The present study aimed to: (a) evaluate neuromuscular, urinary, and hematological responses after simulated padel competition (SC) and (b) analyze possible gender differences. In this study, 28 high-level padel players participated (men = 13, age = 26.83 ± 6.57 years; women = 15, age = 30.07 ± 4.36 years). The following parameters were analyzed before and after SC: neuromuscular (hand grip strength, squat jump (SJ), countermovement jump (CMJ), and Abalakov jump (ABK)), hematological (red blood cells, hemoglobin, and hematocrit), and urinary (pH, specific gravity, microalbuminuria, and red blood cells). Significant gender differences were found in neuromuscular and hematological responses, with men obtaining higher values (p < 0.05). For the SC influence, changes were noted in ABK and microalbuminuria (p < 0.05). The percentages of change in hand grip strength, SJ (height and watts), CMJ (height), and ABK (height) were higher for men than women (p < 0.05). SC negatively influenced the neuromuscular parameters to a greater extent in women. Our results could be related to gender differences in game actions, the temporal structure, and anthropometric and physiological characteristics. Game dynamics and a different organic response between male and female padel playing were confirmed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland