Quantitative Studies of Microstructural Phase Transformation: Critical Features of Nickel Titanium Polycrystals Undergoing Superelastic Deformation.

This dissertation addresses the stress-induced phase transformation that occurs upon the loading of Nickel-Titanium alloys, leading to their superelastic properties. Superelasticity is widely utilized in biomedical applications including stents and valves, but there is still much that is unknown regarding the interaction between the superelastic martensitic transformation and microstructure of these materials. To help fill this knowledge gap, an experimental technique combining high resolution Scanning Electron Microscopy and Digital Image Correlation was applied to the analysis of superelastic nickel titanium shape memory alloy. The displacement and subsequent strain maps generated from this technique, combined with crystallographic orientation gathered via Electron Backscatter Diffraction, allowed the tracking of subgrain martensite transformation in polycrystalline specimens. Additional analytical tools were developed to determine the configuration of martensite variants in each transformed grain. These observations provide new details on how the macroscopic martensite band progresses through polycrystals and how that martensite is configured in the transformed martensite band. The previously held assumption that in a superelastic polycrystal similarly oriented grains transform similarly is found to be inaccurate based on experimental observations. Previously unobserved lattice correspondence variant configurations of martensite were found to readily develop in the polycrystalline specimens in addition to the previously observed habit plane variants. The appearance of these correspondence variant configurations was due to the large resolved shear stress on twin planes as identified using logistic regression on the configuration fractions and the underlying grain orientations of the polycrystal. Those areas which primarily transformed to correspondence variant configurations accumulated an increased amount of residual strain, which served as a blueprint for subsequent transformation. While the interaction between martensite, plasticity, and polycrystalline microstructures requires more work to fully characterize, this dissertation represents an attempt to understand the complex interactions taking place in superelastic material undergoing cyclic loading.PhDMaterials Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116620/1/mkimieci_1.pd

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

Lessons Learned from the LiFEsports Initiative: Facilitators and Barriers to Successful Community Partnerships

The Learning in Fitness and Education through Sports Initiative at The Ohio State University (Ohio State LiFEsports) fosters community positive youth development (PYD). Youth growing up in urban settings are disproportionally confronted with a wide range of risk factors and need more opportunities for healthy development. Due to encountering such risk factors, urban youth are more likely to develop behavioral health problems that may compromise their long-term development. Community PYD programs are often designed to promote psychological, social and physical health outcomes. Furthermore, community PYD programs partner with other community partners to provide additional program support and development. Established in 2006 through a unique partnership between the College of Social Work and the Department of Athletics, LiFEsports aims to promote health and wellness for Columbus city youth. Each year, LiFEsports serves more than 900 youth through programs such as the LiFEsports summer camp and the LiFEsports clinics. The success of the program would not be possible without collaborations with more than 20 key university and community partnerships. Key university partnerships with Recreational Sports and Transportation and Traffic Management help to provide facilities and transportation to 23 zip codes. Community partners such as Dannon provide support for 10,500 meals for the 600 youth who participate in the LiFEsports camp during the summer months. Marathon Kids helps campers track the mileage of each group, some completing more than 104 miles. Additionally, community partnerships have been established with After-School All-Stars Ohio, Pickerington School District, and the YMCA. These partnerships have allowed the LiFEsports model to expand into 13 before- and after-school programs where an additional 1,100 youth are served throughout the school year. LiFEsports has been able to positively impact the health and wellness for Columbus city youth due to valuable partnerships. Specifically, LiFEsports youth have demonstrated significant growth in life skills such as self-control, effort, teamwork, and social responsibility as well as physical activity, self-efficacy, and cardiovascular fitness. At the conclusion of LiFEsports summer camp, 74.8 percent of youth indicated it was "pretty true" or "really true" that because of LiFEsports they were more likely to engage in at least one hour of physical activity each day. In sum, this poster will discuss the facilitators and barriers to developing community partnerships as well as highlight the contribution such partnerships have had on youth health and wellness, while also giving an outline of community partners that LiFEsports has been or is currently engaged with. This poster serves to enlighten an audience of student, colleagues and community partners about what it takes to charter successful community partnerships.AUTHOR AFFILIATION: Dawn Anderson-Butcher, Professor, College of Social Work, LiFEsports, CAYCI, [email protected] (Corresponding Author); Jerry Davis, Executive Director of Service and Outreach, LiFEsports Intiative; Tasha Henderson, Student Research Assistant, CAYCI, LiFEsports Initiative; Carly Kimiecik, Student Research Assistant, CAYCI, LiFEsports Intiative; Tarkington Newman, Graduate Research Associate, LiFEsports Intiative; Stephen Moore, Program Coordinator, LiFEsports Initiative.The Learning in Fitness and Education through Sports Initiative at The Ohio State University (LiFEsports) fosters community positive youth development (PYD). Each year, LiFEsports serves more than 900 youth through programs such as the LiFEsports summer camp and the LiFEsports clinics. Due to valuable partnerships, LiFEsports has been able to positively impact the health and wellness of Columbus city youth. University partners, such as the department of Athletics, Recreational Sports and the College of Nursing, provide resources that directly impact youth outcomes. Community partners including Dannon and Marathon kids help showcase the important of healthy lifestyle choices and habits that begin in childhood. Sharing the experiences of LiFEsports, the poster will assist the audience in fostering partnerships in relation to their own organizations and programs. Partnerships will highlight a range of impact on the health and well-being of 900+ youth each year

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

Exploring the interactions underlying flow states: A connecting analysis of flow occurrence in European Tour golfers

Objectives: Research to date has identified a range of factors suggested to facilitate flow states in sport. However, less attention has focused on how exactly those facilitating factors influence the occurrence of flow. Therefore, this study aimed to explore the specific ways in which such facilitators influenced flow occurrence in European Tour golfers. Design: Qualitative design. Method: Ten full-time golfers from the European Tour (M age=37; SD=13.08) participated in semi-structured interviews investigating the occurrence of their flow states. Data were interpreted using an iterative process of thematic and connecting analyses. Results: Ten facilitators of flow were identified, of which commitment and the caddie have not been reported previously. Twenty four connecting links were identified in the data, through which the caddie, effective preparation, and high-quality performance appeared to be most influential for flow occurrence. Confidence and concentration also emerged as key constructs underlying the flow experience in this setting. Conclusion: A central contribution of this study is the identification of ways in which facilitating factors could influence flow occurrence in elite golf. This process adds detail to understanding of flow occurrence, and moves beyond simply identifying factors which are associated with the experience. As such, connecting analysis is proposed as an additional strategy for qualitatively investigating flow occurrence in sport. Results are discussed in relation to previous literature, and recommendations are identified for researchers, athletes, coaches and practitioners

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