Microstructural strain memory and associated plasticity in superelastic niti under low cycle fatigue

When cyclically loaded in tension, superelastic Nickel Titanium (NiTi) undergoes a characteristic shakedown behavior which dramatically changes its hysteretic stress–strain response. As many uses of superelastic NiTi involve cyclic loading, a detailed understanding of the interaction between phase transformation and associated plasticity is necessary to predict the lifetime behavior of NiTi devices. Earlier macroscopic studies have dealt with this phenomenon on a bulk material level, but its microstructural origin and small scale analogues remain largely uninvestigated. To that end, low cycle, low strain-rate fatigue tests were performed on superelastic NiTi sheet to examine the local damage and accumulation of plastic deformation that contribute to the evolution of its stress strain response. Local strain measured in situ with Scanning Electron Microscopy Digital Image Correlation was matched with individual microstructural features – such as individual parent grains and grain neighborhoods – measured with Electron Backscatter Diffraction. Martensitic transformation associated with superelasticity was inferred from the full-field strain maps captured each load cycle. Special attention was paid to the particular martensite variants and twinning modes that nucleate in the first cycle and their similitude to subsequent martensite transformation. In addition, cyclic behavior such as martensite retention and ratcheting, strain memory of both martensite and austenite configurations, and damage accumulation are also considered

My heart is racing! Psychophysiological dynamics of skilled racecar drivers

Our purpose was to test the multi-action plan (MAP) model assumptions in which athletes’ psychophysiological patterns differ among optimal and suboptimal performance experiences. Nine professional drivers competing in premier race categories (e.g., Formula 3, Porsche GT3 Cup Challenge) completed the study. Data collection involved monitoring the drivers’ perceived hedonic tone, accuracy on core components of action, posture, skin temperature, respiration rate, and heart rate responses during a 40-lap simulated race. Time marks, gathered at three standardized sectors, served as the performance variable. The A1GP racing simulator (Allinsport, Modena) established a realistic race platform. Specifically, the Barcelona track was chosen due to its inherently difficult nature characterized by intermittent deceleration points. Idiosyncratic analyses showed large individual differences in the drivers’ psychophysiological profile, as well as distinct patterns in regards to optimal and suboptimal performance experiences. Limitations and future research avenues are discussed. Action (e.g., attentional control) and emotion (e.g., biofeedback training) centered applied sport psychology implications are advanced

A systematic review of the experience, occurrence, and controllability of flow states in elite sport

Objectives: This study aimed to provide an up-to-date summary of the literature on flow in elite sport, specifically relating to: (i) how flow is experienced; (ii) how these states occur; and (iii) the potential controllability of flow. Design: Systematic review. Methods: A comprehensive literature search of SPORTdiscus, PsycINFO, SAGE journals online, INGENTA connect, and Web of Knowledge was completed in August, 2011, and yielded 17 empirical studies published between 1992 and 2011. The primarily qualitative findings were analysed thematically and synthesised using a narrative approach. Results: Findings indicated that: (i) some flow dimensions appear to be experienced more consistently than others; (ii) key factors were consistently reported to induce or inhibit flow occurrence; and (iii) the perception that flow experiences could be controllable to some extent, and are not merely ‘coincidental’. Additionally, it is appears that physiology is also relevant in flow, and these experiences may be psychophysiological. Conclusions: Based on these findings, recommendations are made including the need for researchers to move from description to explanation of flow, the use of new methodologies, greater focus on the role of personality factors, and possible refinements of existing flow theory to be more specific to sport

Shared mental models and intra-team psychophysiological patterns: A test of the juggling paradigm

We explored implicit coordination mechanisms underlying the conceptual notion of "shared mental models" (SMM) through physiological (i.e., breathing and heart rates) and affective-cognitive (i.e., arousal, pleasantness, attention, self-efficacy, other's efficacy) monitoring of two professional jugglers performing a real-time interactive task of increasing difficulty. There were two experimental conditions: "individual" (i.e., solo task) and "interactive" (i.e., two jugglers established a cooperative interaction by juggling sets of balls with each other). In both conditions, there were two task difficulties: “easy” and “hard”. Descriptive analyses revealed that engaging in a dyadic cooperative motor task (interactive condition) required greater physiological effort (Median Cohen’s d = 2.13) than performing a solo motor task (individual condition) of similar difficulty. Our results indicated a strong positive correlation between the jugglers’ heart rate for the easy (r = .87) and hard tasks (r = .77). The relationship between the jugglers’ breathing rate was significant for the easy task (r = .73) but non-significant for the hard task. The findings are interpreted based on research on SMM and Theory of Mind. Practitioners should advance the notion of “shared-regulation” in the context of team coordination through the use of biofeedback training

The health outcomes and physical activity in preschoolers (HOPP) study: rationale and design

<p>Abstract</p> <p>Background</p> <p>The early years are the period of growth for which we know the least about the impact of physical activity. In contrast, we know that more than 90 % of school-aged Canadian children, for example, are not meeting physical activity recommendations. Such an activity crisis is a major contributor to recent trends in childhood obesity, to which preschoolers are not immune. The World Health Organization estimated that more than 42 million children under the age of 5 years were overweight world-wide in 2010. If an activity crisis exists during the preschool years, we should also be concerned about its broader impact on health. Unfortunately, the relationship between physical activity and health during the early years is poorly understood. The goal of the Health Outcomes and Physical activity in Preschoolers (HOPP) study is to describe how the prevalence and patterns of physical activity in preschoolers are associated with indices of health.</p> <p>Methods</p> <p>The HOPP study is a prospective cohort study. We aim to recruit 400 3- to 5-year-old children (equal number of boys and girls) and test them once per year for 3 years. Each annual assessment involves 2 laboratory visits and 7 consecutive days of physical activity monitoring with protocols developed in our pilot work. At visit 1, we assess body composition, aerobic fitness, short-term muscle power, motor skills, and have the parents complete a series of questionnaires related to their child’s physical activity, health-related quality of life and general behaviour. Over 7 consecutive days each child wears an accelerometer on his/her waist to objectively monitor physical activity. The accelerometer is programmed to record movement every 3 s, which is needed to accurately capture the intensity of physical activity. At visit 2, we assess vascular structure and function using ultrasound. To assess the associations between physical activity and health outcomes, our primary analysis will involve mixed-effects models for longitudinal analyses.</p> <p>Discussion</p> <p>The HOPP study addresses a significant gap in health research and our findings will hold the potential to shape public health policy for active living during the early years.</p

Can Becoming My Self Influence My Health?: Exploring the Effects of a Eudaimonic-Enhancement Process on Psychological Indicators of Well-Being and Physical Activity

The current study adopts an intervention approach that begins with the assumption that the quality of a person\u27s lived experience is at the core of well-being and health behavior change. Specifically, the present study used a well-being enhancement process grounded in eudaimonia to explore the connection among eudaimonia, indicators of psychological well-being (i.e., personal growth, subjective vitality, self-determination, and life engagement), and physical activity. Participants in the intervention group engaged in 8 weekly, group eudaimonic well-being enhancement (the Well-Being Way, WBW) sessions with assessments at Weeks 1, 8, and 12 (follow-up), and were compared to a comparison group that did not participate. A series of 2 × 3 (Group by Time) repeated measures ANOVAs along with follow-up paired comparisons t-tests were conducted to compare the WBW and comparison groups across time. Results indicated that the WBW group exhibited significant increases in two indices of psychological well-being (trait subjective vitality and self-determination) and in their physical activity levels. The comparison group showed no changes in any of the variables. The results of an exploratory regression analysis provided some evidence that WBW participants who experienced the greatest gains in life engagement and trait subjective vitality also exhibited significant increases in level of physical activity. Discussion focuses on the implications of the Well-Being Way approach for the enhancement of positive well-being and future possibilities for eudaimonic-based approaches to health behavior change. © 2013 Springer Science+Business Media Dordrecht and The International Society for Quality-of-Life Studies (ISQOLS)