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Keith M Bayha, Allen G Collins, Patrick M Gaffney
BACKGROUND: Species of the scyphozoan family Pelagiidae (e.g., Pelagia noctiluca, Chrysaora quinquecirrha) are well-known for impacting fisheries, aquaculture, and tourism, especially for the painful sting they can inflict on swimmers. However, historical taxonomic uncertainty at the genus (e.g., new genus Mawia) and species levels hinders progress in studying their biology and evolutionary adaptations that make them nuisance species, as well as ability to understand and/or mitigate their ecological and economic impacts...
2017: PeerJ
Kerstin Romberg, Ellen Tufvesson, Leif Bjermer
BACKGROUND: Strenuous physical activity at an elite level is associated with an increased risk for asthma and, in some sports, also prevalence of allergies. The aim of this study was to investigate the prevalence of asthma and allergy among elite swimmers and tennis players and compare airway hyperreactivity to mannitol and exercise. MATERIALS AND METHODS: One hundred and one adolescent swimmers and 86 tennis players answered a questionnaire about respiratory symptoms and allergy and performed mannitol challenge and sport-specific exercise challenge...
2017: Journal of Asthma and Allergy
Laura M Suppes, Ching-Hua Huang, Wan-Ning Lee, Kyle J Brockman
Pharmaceuticals and personal care products (PPCPs) in swimming pool water are hypothesized to originate from fill water and anthropogenic sources like urine, sweat, swimwear and body surfaces. However, research exploring PPCP origins in pools is lacking. This research investigates PPCP sources at 31 swimming pools. Pool water was analyzed for 24 representative PPCPs using advanced liquid chromatography-mass spectrometry techniques. Fill water was analyzed as a contamination source and to determine if swimmers introduce PPCPs to pools...
October 2017: Journal of Water and Health
Luis Rodriguez, Santiago Veiga
PURPOSE: The aim of the present research was 1) to compare the pacing strategies of different level open water swimmers during the 10km race of the FINA 2015 World Swimming Championships (WCH), and 2) to relate these pacing strategies to the race performance. METHODS: Final and intermediate split times as well as intermediate race positions from the 10-kilometer race participants (69 men and 51 women) were collected from the public domain and were divided into five groups (G1 to G5) depending on their finishing positions...
October 16, 2017: International Journal of Sports Physiology and Performance
Mohannad A Awad, Thomas W Gaither, Gregory P Murphy, Thanabhudee Chumnarnsongkhroh, Ian Metzler, Thomas Sanford, Siobhan Sutcliffe, Michael L Eisenberg, Peter R Carroll, E Charles Osterberg, Benjamin N Breyer
PURPOSE: To explore the relation between cycling and urinary and sexual function in a large, multinational sample of men. MATERIALS AND METHODS: Cyclists were recruited to complete a survey through Facebook advertisements and outreach to sporting clubs. Swimmers and runners were recruited as a comparison group. Cyclists were categorized into low and high intensity cyclists. Participants were queried using validated questionnaires, including the Sexual Health Inventory for Men (SHIM), International Prostate Symptom Score (I-PSS), and National Institute of Health Chronic Prostatitis Symptom Index (NIH-CPSI), in addition to questions about urinary tract infections (UTIs), urethral strictures, genital numbness, and saddle sores...
October 12, 2017: Journal of Urology
Josje van Houwelingen, Melvyn Roerdink, Alja V Huibers, Lotte L W Evers, Peter J Beek
In swimming propelling efficiency is partly determined by intra-cyclic velocity fluctuations. The higher these fluctuations are at a given average swimming velocity, the less efficient is the propulsion. This study explored whether the leg-arm coordination (i.e. phase relation ϕ) within the breaststroke cycle can be influenced with acoustic pacing, and whether the so induced changes are accompanied by changes in intra-cyclic velocity fluctuations. Twenty-six participants were asked to couple their propulsive leg and arm movements to a double-tone metronome beat and to keep their average swimming velocity constant over trials...
2017: PloS One
P H Rhys Evans, M Cameron
For over a century, otolaryngologists have recognised the condition of aural exostoses, but their significance and aetiology remains obscure, although they tend to be associated with frequent swimming and cold water immersion of the auditory canal. The fact that this condition is usually bilateral is predictable since both ears are immersed in water. However, why do exostoses only grow in swimmers and why do they grow in the deep bony meatus at two or three constant sites? Furthermore, from an evolutionary point of view, what is or was the purpose and function of these rather incongruous protrusions? In recent decades, paleoanthropological evidence has challenged ideas about early hominid evolution...
September 15, 2017: Annals of the Royal College of Surgeons of England
Enric Saiz, Albert Calbet, Kaiene Griffell
Planktonic copepods are a very successful group in marine pelagic environments, with a key role in biogeochemical cycles. Among them, the genus Oithona is one of the more abundant and ubiquitous. We report here on the effects of caloric (food) restriction on the ageing patterns of the copepod Oithona davisae. The response of O. davisae to caloric restriction was sex dependent: under food limitation, females have lower age-specific mortality rates and longer lifespans and reproductive periods; male mortality rates and life expectancy were not affected...
October 4, 2017: Scientific Reports
Chuanbin Li, Boyang Qin, Arvind Gopinath, Paulo E Arratia, Becca Thomases, Robert D Guy
Many important biological functions depend on microorganisms' ability to move in viscoelastic fluids such as mucus and wet soil. The effects of fluid elasticity on motility remain poorly understood, partly because the swimmer strokes depend on the properties of the fluid medium, which obfuscates the mechanisms responsible for observed behavioural changes. In this study, we use experimental data on the gaits of Chlamydomonas reinhardtii swimming in Newtonian and viscoelastic fluids as inputs to numerical simulations that decouple the swimmer gait and fluid type in order to isolate the effect of fluid elasticity on swimming...
October 2017: Journal of the Royal Society, Interface
Gordon E Barkwell, James P Dickey
FINA recently approved the backstroke ledge (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare the mechanics of starts performed with and without the OBL2. Ten high-level backstroke swimmers performed three starts with, and three starts without, the OBL2. A wall-mounted force plate measured the lower limb horizontal impulse, vertical impulse, take-off velocity and take-off angle. Entry distance, time to 10 m and start of hip and knee extension were recorded using video cameras...
October 4, 2017: Sports Biomechanics
Rafael A Casuso, Julio Plaza-Díaz, Francisco J Ruiz-Ojeda, Jerónimo Aragón-Vela, Cándido Robles-Sanchez, Nikolai B Nordsborg, Marina Hebberecht, Luis M Salmeron, Jesus R Huertas
We aimed to test whether high-intensity high-volume training (HIHVT) swimming would induce more robust signaling than sprint interval training (SIT) swimming within the m. triceps brachii due to lower metabolic and oxidation. Nine well-trained swimmers performed the two training procedures on separate randomized days. Muscle biopsies from m. triceps brachii and blood samples were collected at three different time points: a) before the intervention (pre), b) immediately after the swimming procedures (post) and c) after 3 h of rest (3 h)...
2017: PloS One
Melanie D Napier, Richard Haugland, Charles Poole, Alfred P Dufour, Jill R Stewart, David J Weber, Manju Varma, Jennifer S Lavender, Timothy J Wade
BACKGROUND: Fecal indicator bacteria used to assess illness risks in recreational waters (e.g., Escherichia coli, Enterococci) cannot discriminate among pollution sources. To address this limitation, human-associated Bacteroides markers have been proposed, but the risk of illness associated with the presence of these markers in recreational waters is unclear. Our objective was to estimate associations between human-associated Bacteroides markers in water and self-reported illness among swimmers at 6 U...
October 2, 2017: Environmental Health: a Global Access Science Source
Maria Papandreou, Evripidis Diamantis, Vasiliki-Ioanna Vrachlioti, Evdokia Billis, John Gliatis
BACKGROUND: Several etiologic factors have been postulated in overhead athletes according to their shoulder injuries, such as the scapular posture asymmetries. The measurement of the acromion border distance has been considered as reliable clinical test for evaluating the static scapula posture. The aim of this study was to quantify the differences in scapular posture between the dominant and non-dominant shoulders in two static positions in volleyball and swimmers athletes with asymptomatic shoulder injuries using the sliding calliper device...
September 29, 2017: Journal of Sports Medicine and Physical Fitness
David Simbaña-Escobar, Philippe Hellard, David B Pyne, Ludovic Seifert
To study the variability in stroking parameters between and within laps and individuals during competitions, we compared and modelled the changes of speed, stroke rate and stroke length in thirty-two top-level male and female swimmers over four laps (L1-L4) in 200-m freestyle events using video-derived 2-dimensional direct linear transformation. For the whole group, speed was greater in L1, with significant decreases across L2, L3 and L4 (1.80±0.10 vs. 1.73±0.08; 1.69±0.09; 1.66±0.09 m.s(-1), p<.05)...
September 27, 2017: Journal of Applied Biomechanics
Enkeleida Lushi, Vasily Kantsler, Raymond E Goldstein
We use a three-bead-spring model to investigate the dynamics of biflagellate microswimmers near a surface. While the primary dynamics and scattering are governed by geometric-dependent direct contact, the fluid flows generated by the swimmer locomotion are important in orienting it toward or away from the surface. Flagellar noise and in particular cell spinning about the main axis help a surface-trapped swimmer escape, whereas the time a swimmer spends at the surface depends on the incident angle. The dynamics results from a nuanced interplay of direct collisions, hydrodynamics, noise, and the swimmer geometry...
August 2017: Physical Review. E
Moslem Moradi, Ali Najafi
Suspensions of hydrodynamical active particles exhibit interesting rheological properties. For a dilute suspension of microswimmers, it has been shown that the effective viscosity of the suspension depends on the volume fraction of swimmers, and it behaves differently for pushers and pullers. Here we develop a theoretical framework to study the rheological properties of an interacting suspension. Taking into account the hydrodynamic interaction between swimmers and considering the small Péclet number condition, we calculate the effective viscosity of a two-dimensional suspension...
August 2017: Physical Review. E
Natsuhiko Yoshinaga, Tanniemola B Liverpool
We study the role of hydrodynamic interactions in the collective behavior of collections of microscopic active particles suspended in a fluid. We introduce a calculational framework that allows us to separate the different contributions to their collective dynamics from hydrodynamic interactions on different length scales. Hence we are able to systematically show that lubrication forces when the particles are very close to each other play as important a role as long-range hydrodynamic interactions in determining their many-body behavior...
August 2017: Physical Review. E
Benno Liebchen, Demian Levis
We generalize the Vicsek model to describe the collective behavior of polar circle swimmers with local alignment interactions. While the phase transition leading to collective motion in 2D (flocking) occurs at the same interaction to noise ratio as for linear swimmers, as we show, circular motion enhances the polarization in the ordered phase (enhanced flocking) and induces secondary instabilities leading to structure formation. Slow rotations promote macroscopic droplets with late time sizes proportional to the system size (indicating phase separation) whereas fast rotations generate patterns consisting of phase synchronized microflocks with a controllable characteristic size proportional to the average single-particle swimming radius...
August 4, 2017: Physical Review Letters
J S Lintuvuori, A Würger, K Stratford
We present a study of the hydrodynamics of an active particle-a model squirmer-in an environment with a broken rotational symmetry: a nematic liquid crystal. By combining simulations with analytic calculations, we show that the hydrodynamic coupling between the squirmer flow field and liquid crystalline director can lead to reorientation of the swimmers. The preferred orientation depends on the exact details of the squirmer flow field. In a steady state, pushers are shown to swim parallel with the nematic director while pullers swim perpendicular to the nematic director...
August 11, 2017: Physical Review Letters
Jiang Zhuang, Byung-Wook Park, Metin Sitti
Despite the large body of experimental work recently on biohybrid microsystems, few studies have focused on theoretical modeling of such systems, which is essential to understand their underlying functioning mechanisms and hence design them optimally for a given application task. Therefore, this study focuses on developing a mathematical model to describe the 3D motion and chemotaxis of a type of widely studied biohybrid microswimmer, where spherical microbeads are driven by multiple attached bacteria. The model is developed based on the biophysical observations of the experimental system and is validated by comparing the model simulation with experimental 3D swimming trajectories and other motility characteristics, including mean squared displacement, speed, diffusivity, and turn angle...
September 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
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