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Surfers both cooperate and compete around a scarce natural resource – ocean waves suited for surfing – often with a fraught mix of motives and feelings, pro-social and anti-social. Much as surfers constantly adapt to a dynamic wave environment, their pro- and anti-social motives readily mix and shift, based on their interpretation of quickly changing context. What we learn from surfers is something materialistic focus on self-interest and realities of scarcity or abundance might de-emphasize or miss: a culture of interpretation and reasoning (e.g. 'localism') is as important in the formation of shifting pro- and anti-social attitudes as the material reality of wave scarcity or abundance itself. [ABSTRACT FROM AUTHOR]

A Marangoni surfer is an object embedded in a gas–liquid interface, propelled by gradients in surface tension. We derive an analytical theorem for the lower bound on the viscous dissipation by a Marangoni surfer in the limit of small Reynolds and capillary numbers. The minimum dissipation can be expressed with the reciprocal difference between drag coefficients of two passive bodies of the same shape as the Marangoni surfer, one in a force-free interface and the other in an interface with surface incompressibility. The distribution of surface tension that gives the optimal propulsion is given by the surface tension of the solution for the incompressible surface and the flow is a superposition of both solutions. For a surfer taking the form of a thin circular disk, the minimum dissipation is $16\mu a V^2$ , giving a Lighthill efficiency of $1/3$. This places the Marangoni surfers among the hydrodynamically most efficient microswimmers. [ABSTRACT FROM AUTHOR]

Microfluidics has enabled the miniaturization of fluidic systems for various biomedical and industrial applications, including small-scale robotic propulsion. One mechanism for generating propulsive force through microfluidics is by exploiting the solutal Marangoni effect via releasing surfactant on the air-water interface. Surfactants locally reduce the surface tension, which leads to a surface stress that can propel the floating robot, called Marangoni surfer. However, so far the release of the surfactant is not controllable. In this study, we combine microfluidics-based Marangoni propulsion with a novel untethered magnetic pumping mechanism to enhance its controllability. The proposed magnetic micropump capitalizes on the interaction force between two soft magnets, which can generate a pumping force of 4.64 mN to actuate a membrane, and achieve a deformation of 450 μm. Net flow is achieved using a nozzle/diffuser flow rectifier whose efficacy as a function of the channel geometry is numerically studied. We investigate the flow rate of the pump with regard to the actuation frequency. Finally, we demonstrate its ability to control the motion of the Marangoni surfer. [ABSTRACT FROM AUTHOR]

Surfing is a growing, high-participation recreational and competitive activity. It is relatively unique, being performed on, in, and through water with a range of temperatures. In other sports, warm-up and heat retention have proved useful at augmenting performance and ameliorating injury risk. Little work has been carried out examining this in surfing. The purpose of this work was to measure thermal profiles in surfers with and without warm-up and passive heat retention, and secondarily to assess any potential influence on free surfing. A repeated measures pre- and post- design was adopted whereby participants surfed in an artificial wave pool following an active warm-up combined with passive heat retention (experimental condition) and after no warm-up (control). Core body temperature was measured both occasions. Our results showed increases in core body temperature were greater for the experimental condition versus control (p = 0.006), and a time effect exists (p < 0.001)—in particular, a warm-up effect in the water itself was shown in both groups, possibly due to further activity (e.g., paddling) and wetsuit properties. Finally, performance trended to being superior following warm-up. We conclude that body warmth in surfers may be facilitated by an active warm-up and passive heat retention. In free surfing, this is associated with a trend towards better performance; it may also reduce injury risk. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The recent rise in professionalisation and institutionalisation of competitive surfing has resulted in a dramatic increase in the use of alternative training modalities. These are often employed in an attempt to increase exposure to surf-like activities when appropriate ocean conditions are not available. It is commonly accepted that practice sessions should be grounded in theory, with training content informed by a clear scientific rationale. Despite this, research is yet to offer surfing coaches and surfers effective strategies to assist in implementing appropriate 'off water' training modalities. It is widely accepted that integrating a representative learning design is crucial towards the transfer of performance to competition environments. Therefore, the aim of this paper is to promote representative learning design (RLD) as a contemporary, principled framework that can underpin the creation of surfing training design and performance. Examples of constraints relevant to surfing are considered, and the efficacy and rationale of popular training methods are challenged. Finally, practical implications and coaching tools to underpin the implementation of representative learning design in surf training are provided. [ABSTRACT FROM AUTHOR]

Copyright of Leisure/Loisir: Journal of the Canadian Association for Leisure Studies is the property of Routledge and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose. The present study aimed to describe the main characteristics of Brazilian surfers and their injuries, and to analyze the probability of developing injuries according to skill level, experience in surfing, training volume, and age. Methods. A total of 1829 Brazilian surfers answered an electronic survey about their characteristics and previous and current injuries. The association between participant characteristics and percentage of injuries was investigated using a chi-squared test. The statistical significance of the results was assumed at a p-value < 0.05. The prevalence ratio (PR) was also calculated to illustrate the probability of having injuries. Results. Most surfers are men (84.2%), young adults (72.0%), with more than 2 years of experience in surfing (60.7%), with an intermediate level of skill (49.3%), recreational surfers (99.2%), and who practice surfing 1 to 2 days a week (79.7%) for 1 to 3 hours a day (65.9%). About 55.5% of the participants were already affected by an injury or had some surfing-related pain. In the last 12 months, 52.2% of surfers suffered injuries. For both, more than 50% of injuries occurred in the lower limbs. Brazilian surfers with higher skill levels, time of experience, hours per day of surf training, and age presented higher prevalence ratios of previous and current injuries. Conclusions. In summary, Brazilian surfers are predominantly male, young adults, and non-competitive athletes. The most injured anatomical region in this group is the lower limbs. Contrary to expectation, higher experience and skill levels might not act as protective factors against injuries due to increased training volume. [ABSTRACT FROM AUTHOR]

This article presents a case study of a weight lifter who was diagnosed with a surfer's knot, a benign subcutaneous nodule typically found in areas subjected to repetitive trauma during surfing. The weight lifter presented with soft tissue nodules in the shoulders and upper back, which were initially unclear based on history and clinical examination alone. Ultrasonography and magnetic resonance imaging (MRI) were used to confirm the diagnosis, showing hypoechoic nodules with low T1 and T2 signal intensity. The study highlights the unexpected diagnosis of surfer's knot in a weight lifter and suggests that weight lifters may experience similar microtrauma to surfers, leading to the development of these nodules. [Extracted from the article]

This study aims to analyze skylight conditions surrounding the newly constructed Timau National Observatory (TNO) in Kijang, Indonesia. The analysis was carried out with the primary reason of determining the initial conditions and surroundings of the area, thereby providing valuable information for future observers who will be using the facility. To achieve the stated aim, the sky brightness in the study area was measured in units of magnitudes per square arcsecond (mpsas) at a 20-kilometer radius. Furthermore, numerous observations were conducted at 32 distinct observation points using Sky Quality Meter (SQM) LUDL (SQM -LU-DL), which was directed towards the zenith. The results obtained from these observations were subsequently analyzed using Surfer software with the primary aim of determining sky brightness in the study area. The analysis showed variations in sky quality in a 20 km radius, ranging from 21.64 to 20.37 magnitudes per square arcsecond (mpsas). The measurements showed that sky quality fdl between the categories of great dark and semi-suburban transitional skies. However; it was important to comprehend that recent investigations had identified bright areas surrounding the observatory area, capable of diminishing the visual quality of sky if left unaddressed. [ABSTRACT FROM AUTHOR]