Political persuasion on social media: A moderated moderation model of political discussion disagreement and civil reasoning

Abstract

Social media and news use arguably contribute to the prevalence of contentious politics because individuals may express dissent through their social networks as they consume news. This study seeks to test whether individuals might be more open to political persuasion in this context, especially if they are exposed to political disagreement or discuss politics in a civil manner. Relying on survey data from the UK, results based on a moderated moderation model show that (a) social media news use predicts political persuasion on social media (direct effects) and, (b) discussion disagreement and civil reasoning moderate this relationship in two-way and three-way interactions.     

Perturbations in Blood Phosphatidylcholine and Sphingomyelin Fatty Acid Composition in a Sample Population of Cigarette Smokers

Docosahexaenoic (DHA) and arachidonic acids (AA) are polyunsaturated fatty acids (PUFAs), major components of brain tissue and neural systems, and the precursors of a number of biologically active metabolites with functions in inflammation resolution, neuroprotection and other actions. As PUFAs are highly susceptible to peroxidation, we hypothesised whether cigarette smokers would present altered PUFAs levels in plasma and erythrocyte phospholipids. Adult males from Indian, Sri-Lankan or Bangladeshi genetic backgrounds who reported smoking between 20 and 60 cigarettes per week were recruited. The control group consisted of matched non-smokers. A blood sample was taken, plasma and erythrocyte total lipids were extracted, phospholipids were separated by thin layer chromatography, and the fatty acid content analysed by gas chromatography. In smokers, dihomo-gamma-linolenic acid, the AA precursor, was significantly reduced in plasma and erythrocyte phosphatidylcholine. AA and DHA were significantly reduced in erythrocyte sphingomyelin. Relatively short term smoking has affected the fatty acid composition of plasma and erythrocyte phospholipids with functions in neural tissue composition, cell signalling, cell growth, intracellular trafficking, neuroprotection and inflammation, in a relatively young population. As lipid peroxidation is pivotal in the pathogenesis of atherosclerosis and neurodegenerative diseases such as Alzheimer disease, early effects of smoking may be relevant for the development of such conditions.     

The force–time profile of elite front crawl swimmers

Abstract

In this study, we used recently developed technology to determine the force–time profile of elite swimmers, which enabled coaches to make informed decisions on technique modifications. Eight elite male swimmers with a FINA (Federation Internationale de Natation) rank of 900+ completed five passive (streamline tow) and five net force (arms and leg swimming) trials. Three 50-Hz cameras were used to video each trial and were synchronized to the kinetic data output from a force-platform, upon which a motorized towing device was mounted. Passive and net force trials were completed at the participant's maximal front crawl swimming velocity. For the constant tow velocity, the net force profile was presented as a force–time graph, and the limitation of a constant velocity assumption was acknowledged. This allowed minimum and maximum net forces and arm symmetry to be identified. At a mean velocity of 1.92 ± 0.06 m · s^?1, the mean passive drag for the swimmers was 80.3 ± 4.0 N, and the mean net force was 262.4 ± 33.4 N. The mean location in the stroke cycle for minimum and maximum net force production was at 45% (insweep phase) and 75% (upsweep phase) of the stroke, respectively. This force–time profile also identified any stroke asymmetry.     

Self-Controlled Practice Enhances Motor Learning in Introverts and Extroverts

Purpose: The purpose of the present study was to investigate the effects of self-controlled feedback on the learning of a sequential-timing motor task in introverts and extroverts. Method: Fifty-six university students were selected by the Eysenck Personality Questionnaire. They practiced a motor task consisting of pressing computer keyboard keys in a specific spatial and temporal pattern. The experiment consisted of practice, retention, and transfer phases. The participants were distributed into 4 groups, formed by the combination of personality trait (extraversion/introversion) and type of feedback frequency (self-controlled/yoked). Results: The results showed superior learning for the groups that practiced in a self-controlled schedule, in relation to groups who practiced in an externally controlled schedule, F(1, 52) = 4.13, p < .05, η² = .07, regardless of personality trait. Conclusion: We conclude that self-controlled practice enhances motor learning in introverts and extroverts.     

Quantifying stroke coordination during the breathing action in front-crawl swimming using an instantaneous net drag force profile

Abstract

This study used both an instantaneous net drag force profile and a symmetry timing to evaluate the effect of the breathing action on stroke coordination. Twenty elite swimmers completed a total of six randomised front-crawl towing trials: (i) three breathing trials and (ii) three non-breathing trials. The net drag force was measured using an assisted towing device mounted upon a Kistler force platform, and this equipment towed the swimmer at a constant speed. The net drag force profile was used to create a stroke symmetry index for each swimming trial. Analysis using the symmetry indices identified that the majority of participants demonstrated an asymmetrical instantaneous net drag force stroke profile in both the breathing and non-breathing conditions, despite no significant differences in the time from finger-tip entry to finger-tip exit. Within the breathing condition, the faster swimmers compared to the slower swimmers demonstrated a lesser percentage of overlap between stroke phases on their breathing stroke side. During the non-breathing condition, the faster participants compared to the slower swimmers recorded a reduction in the percentage of overlap between stroke phases and less duration in the underwater stroke on their breathing stroke side. This study identified that the majority of participants demonstrated an asymmetrical net drag force profile within both conditions; however, asymmetry was less prevalent when examining with only the timing symmetry index.     

Perceived environmental characteristics and psychosocial factors associated with physical activity levels in adolescents from Northeast Brazil: structural equation modelling analysis

Abstract

This study aimed to investigate the direct and indirect associations between perceived environmental characteristics and psychosocial factors and physical activity levels in adolescents from Northeast Brazil. The sample was composed of 2,361 adolescents aged 14–19 years (56.6% female). Physical activity was measured using a questionnaire and environmental (perceived environmental characteristics) and psychosocial (self-efficacy, social support from parents and friends for physical activity) factors with previously validated scales. Perceived environmental characteristics were not directly associated with the levels of physical activity, but exhibited significant indirect associations, mediated by self-efficacy in males. Self-efficacy and social support were positively and directly associated with physical activity levels, and part of the associations between social support and physical activity was mediated by self-efficacy. Perception of self-efficacy and social support, important factors associated with physical activity levels in adolescents, should be the target of interventions aimed at increasing physical activity. Favorable environments for physical activity also need to be considered, since they have a positive influence on the self-efficacy of adolescents.     

Effects of radiant heat exposure on pacing pattern during a 15-km cycling time trial

Abstract

The goal of this study was to investigate the effects of different durations of skin temperature manipulation on pacing patterns and performance during a 15-km cycling time trial. Nineteen well-trained men completed three 15-km cycling time trials in 18°C and 50% relative humidity with 4.5-km (short-heat), 9.0-km (long-heat) or without (control) radiant heat exposure applied by infrared heaters after 1.5 km in the time trial. During the time trials, power output, mean skin temperature, rectal temperature, heart rate and rating of perceived exertion were assessed. The radiant heat exposure resulted in higher mean skin temperature during the time trial for short-heat (35.0 ± 0.6°C) and long-heat (35.3 ± 0.5°C) than for control (32.5 ± 1.0°C; P < 0.001), whereas rectal temperature was similar (P = 0.55). The mean power output was less for short-heat (273 ± 8 W; P = 0.001) and long-heat (271 ± 9 W; P = 0.02) than for control (287 ± 7 W), but pacing patterns did not differ (P = 0.55). Heart rate was greatest in control (177 ± 9 beats · min^?1; P < 0.001), whereas the rating of perceived exertion remained similar. We concluded that a radiant heat exposure and associated higher skin temperature reduced overall performance, but did not modify pacing pattern during a 15-km cycling time trial, regardless of the duration of the exposure.     

Influence of ski materials on muscle activity

The purpose of this study was to examine whether differences in construction between the compact ski, the racing ski and the soft ski influence the behavioural and electromuscular responses of the user. Eight qualified male ski instructors performed two ‘shuss’ trials and three different basic turns. Six muscles (M. biceps femoris, M. gastrocnemius lateralis and medialis, M. rectus femoris, M. vastus lateralis and M. tibialis anterior) were studied, using a conventional but portable electromyographic (EMG) registration with telemetric synchronization, active electrodes and a six‐channel portable data recorder. Muscle contractions were continuously registered and visualized in raw EMG form and linear envelopes. The differences between the mean rectified EMG data of dynamic contractions while skiing and the mean rectified EMG data of the maximal voluntary contraction were used in the primary analysis of data, from which the participation levels of the muscles investigated could be calculated for each type of ski. Based on this comparison, differences between the effects on muscle activity of the three types of skis were unimportant. In a second phase, the normalized linear envelopes of all subjects were graphically superimposed and averaged. This was performed for each muscle, for each movement, for each leg and for each ski tested. The EMG data were considered in combination with anthropometric values, with snow characteristics and with the velocity of skiing. This study showed systematic differences between the use of the racing, soft and compact ski. On average the soft ski showed the lowest muscle activity patterns and thus the most economical muscular efforts for all muscles investigated and within all movements.     

Measurement of active drag during crawl arm stroke swimming

In order to measure active drag during front crawl swimming a system has been designed, built and tested. A tube (23 m long) with grips is fixed under the water surface and the swimmer crawls on this. At one end of the tube, a force transducer is attached to the wall of the swimming pool. It measures the momentary effective propulsive forces of the hands. During the measurements the subjects’ legs are fixed together and supported by a buoy. After filtering and digitizing the electrical force signal, the mean propulsive force over one lane at constant speeds (ranging from about 1 to 2 m s^‐1) was calculated. The regression equation of the force on the speed turned out to be almost quadratic. At a mean speed of 1.55 m s^‐1 the mean force was 66.3 N. The accuracy of this force measured on one subject at different days was 4.1 N. The observed force, which is equal to the mean drag force, fits remarkably well with passive drag force values as well as with values calculated for propulsive forces during actual swimming reported in the literature. The use of the system does not interfere to any large extent with normal front crawl swimming; this conclusion is based on results of observations of film by skilled swim coaches. It was concluded that the system provides a good method of studying active drag and its relation to anthropometric variables and swimming technique.