1,416 research outputs found

    Do stiffness and asymmetries predict change of direction performance?

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    Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R-2 = 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n = 9); effect sizes were both "large" in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population

    Anomalous Perceptions and Beliefs Are Associated With Shifts Toward Different Types of Prior Knowledge in Perceptual Inference.

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    Psychotic phenomena manifest in healthy and clinical populations as complex patterns of aberrant perceptions (hallucinations) and tenacious, irrational beliefs ( delusions). According to predictive processing accounts, hallucinations and delusions arise from atypicalities in the integration of prior knowledge with incoming sensory information. However, the computational details of these atypicalities and their specific phenomenological manifestations are not well characterized. We tested the hypothesis that hallucination-proneness arises from increased reliance on overly general application of prior knowledge in perceptual inference, generating percepts that readily capture the gist of the environment but inaccurately render its details. We separately probed the use of prior knowledge to perceive the gist vs the details of ambiguous images in a healthy population with varying degrees of hallucination- and delusion-proneness. We found that the use of prior knowledge varied with psychotic phenomena and their composition in terms of aberrant percepts vs aberrant beliefs. Consistent with previous findings, hallucination-proneness conferred an advantage using prior knowledge to perceive image gist but, contrary to predictions, did not confer disadvantage perceiving image details. Predominant hallucination-proneness actually conferred advantages perceiving both image gist and details, consistent with reliance on highly detailed perceptual knowledge. Delusion-proneness, and especially predominance of delusion-proneness over hallucination-proneness, conferred disadvantage perceiving image details but not image gist, though evidence of specific impairment of detail perception was preliminary. We suggest this is consistent with reliance on abstract, belief-like knowledge. We posit that phenomenological variability in psychotic experiences may be driven by variability in the type of knowledge observers rely upon to resolve perceptual ambiguity

    Improving efficiency in generating submissions and consistency of outcomes for Marine Stewardship Council (MSC) based assessments

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    The prevalence of fishery certification schemes and associated ecolabels has grown over the last ten years with numerous ecolabels now in the marketplace e.g. Friends of the Sea, Naturland, SAI Global Trust (Parkes et al. 2010, Washington and Ababouch 2011, Ward and Phillips 2013). However, one of the most prominent and well regarded, particularly by eNGOs, is the Marine Stewardship Council (MSC) (Gutiérrez et al. 2012, Ponte 2012, Bush et al. 2013, Ward and Phillips 2013) which accounts for greater than 10 % of annual global harvest of wild capture fisheries (MSC 2014b)

    Needs and Experiences of People Living with HIV/AIDS Regarding Implementation of Community Home-based Care Services in a Rural County in Western Kenya

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    Community home-based care framework is an integral and integrated part of health care for people living with HIV/AIDS (PLWHA). This study aimed to report the needs and experiences of PLWHA receiving community home-based care in a rural population in Western Kenya. The sample size for the study was 373 PLWHA who were aged 18 and above, disclosed their HIV sero-status, and were receiving any of the CHBC services. The study was a cross-sectional exploratory and data was gathered over a period of four weeks. The findings revealed that needs were mainly what they lacked which include proper health care facilities; support from the government; drugs, counseling support; knowledge and education on the disease; home care equipment and tools; and adequate qualified healthcare professionals. Another major barrier to quality care is poor road network which impacts transportation for both the health workers and patients in provision and access of health care services and other resources respectively. The findings further revealed a strong relationship between influences of adequate care on the status of the illness. Receiving adequate clinical care p=0.000 (X2 = 159.650, df =10), receiving adequate psychological care p=0.000 (X2 = 107.197, df=4), receiving adequate nursing care p=0.000 (?2 = 35.802, df=4), and receiving adequate social support p=0.000 (?2 = 35.277, df=4) significantly influenced health status of the patients. We recommend continued and timely monitoring and evaluation in implementation of CHBC for these rural populations as critical in understanding contextual factors and experiences of PLWHA for better health outcomes

    The Lyman Continuum Escape Survey: Ionizing Radiation from [O III]-Strong Sources at a Redshift of 3.1

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    We present results from the LymAn Continuum Escape Survey (LACES), a Hubble Space Telescope (HST) program designed to characterize the ionizing radiation emerging from a sample of Lyman alpha emitting galaxies at redshift z≃3.1z\simeq 3.1. As many show intense [O III] emission characteristic of z>6.5z>6.5 star-forming galaxies, they may represent valuable low redshift analogs of galaxies in the reionization era. Using HST Wide Field Camera 3 / UVIS F336WF336W to image Lyman continuum emission, we investigate the escape fraction of ionizing photons in this sample. For 61 sources, of which 77% are spectroscopically confirmed and 53 have measures of [O III] emission, we detect Lyman continuum leakage in 20%, a rate significantly higher than is seen in individual continuum-selected Lyman break galaxies. We estimate there is a 98% probability that ≀2\leq 2 of our detections could be affected by foreground contamination. Fitting multi-band spectral energy distributions (SEDs) to take account of the varying stellar populations, dust extinctions and metallicities, we derive individual Lyman continuum escape fractions corrected for foreground intergalactic absorption. We find escape fractions of 15 to 60% for individual objects, and infer an average 20% escape fraction by fitting composite SEDs for our detected samples. Surprisingly however, even a deep stack of those sources with no individual F336WF336W detections provides a stringent upper limit on the average escape fraction of less than 0.5%. We examine various correlations with source properties and discuss the implications in the context of the popular picture that cosmic reionization is driven by such compact, low metallicity star-forming galaxies.Comment: 26 pages, 16 figures, accepted for publication in Ap

    A Longitudinal Examination of Thriving in Sport Performers

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    To sustain success in sport, athletes need to function effectively in their competitive encounters and maintain this level over repeated events. Yet, to date, little is known about how athletes can continue to fully function (i.e., thrive) in their sporting encounters. Equally, there is a lack of research in relation to the factors that predict thriving. Testing the premise that basic psychological needs (i.e., for autonomy, competence, and relatedness) predict optimal functioning, the aim of this study was to provide the first longitudinal examination of thriving in sport. Sport performers (N = 268) completed questionnaires assessing thriving and basic psychological need satisfaction on three occasions across 28 days. Longitudinal structural equation modeling showed thriving to be highly predicted by both the experience of recent thriving and the perceived satisfaction of basic psychological needs. These findings highlight an important mechanism through which coaches and practitioners can initiate and maintain thriving in the athletes that they work with across a series of sporting encounters

    Thriving on Pressure:A Factor Mixture Analysis of Sport Performers’ Responses to Competitive Encounters

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    Although considerable research exists on performers' responses to sporting encounters, little is known about thriving in sport contexts. The current study examined if distinct response patterns existed between sport performers who thrived in competitive encounters compared with those who did not. Participants were 535 sport performers (134 women; M age = 23.60 years, SD age = 8.08; M competing = 11.84 years, SDcompeting = 7.11). Results of factor mixture analysis supported a four-profile solution comprising a thriving group (n = 146), a low-functioning group (n = 38), and two groups characterized by scores marginally above (n = 131) and below (n = 209) the sample mean. Profile membership was found to be predicted by personal enablers (viz., personal resilient qualities, psychological skills use) and process variables (viz., basic psychological need satisfaction and frustration, challenge appraisal). This examination of thriving in sport performers offers significant implications for research and practice. </p

    What doesn't kill me...: adversity-related experiences are vital in the development of superior Olympic performance

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    Objectives: Recent research suggests that experiencing some adversity can have beneficial outcomes for human growth and development. The purpose of this paper was to explore the adversities that the world’s best athletes encounter and the perceived role that these experiences play in their psychological and performance development. Design: A qualitative design was employed because detailed information of rich quality was required to better understand adversity-related experiences in the world’s best athletes. Methods: Semi-structured interviews were conducted with 10 Olympic gold medalists from a variety of sports. Inductive thematic analysis was used to analyze the data. Results: The findings indicate that the participants encountered a range of sport- and non-sport adversities that they considered were essential for winning their gold medals, including repeated non-selection, significant sporting failure, serious injury, political unrest, and the death of a family member. The participants described the role that these experiences played in their psychological and performance development, specifically focusing on their resultant trauma, motivation, and learning. Conclusions: Adversity-related experiences were deemed to be vital in the psychological and performance development of Olympic champions. In the future, researchers should conduct more in-depth comparative studies of Olympic athletes’ adversity- and growth-related experiences, and draw on existing and alternative theoretical explanations of the growth–performance relationship. For professional practitioners, adversity-related experiences offer potential developmental opportunities if they are carefully and purposely harnessed

    What doesn’t kill me ... : adversity-related experiences are vital in the development of superior Olympic performance

    Get PDF
    Objectives: Recent research suggests that experiencing some adversity can have beneficial outcomes for human growth and development. The purpose of this paper was to explore the adversities that the world’s best athletes encounter and the perceived role that these experiences play in their psychological and performance development. Design: A qualitative design was employed because detailed information of rich quality was required to better understand adversity-related experiences in the world’s best athletes. Method: Semi-structured interviews were conducted with 10 Olympic gold medalists from a variety of sports. Inductive thematic analysis was used to analyze the data. Results: The findings indicate that the participants encountered a range of sport- and non-sport adversities that they considered were essential for winning their gold medals, including repeated non-selection, significant sporting failure, serious injury, political unrest, and the death of a family member. The participants described the role that these experiences played in their psychological and performance development, specifically focusing on their resultant trauma, motivation, and learning. Conclusions: Adversity-related experiences were deemed to be vital in the psychological and performance development of Olympic champions. In the future, researchers should conduct more in-depth comparative studies of Olympic athletesñ€ℱ adversity- and growth-related experiences, and draw on existing and alternative theoretical explanations of the growth-performance relationship. For professional practitioners, adversity-related experiences offer potential developmental opportunities if they are carefully and purposely harnessed

    Catalytic Ignition and Upstream Reaction Propagation in Monolith Reactors

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    Using numerical simulations, this work demonstrates a concept called back-end ignition for lighting-off and pre-heating a catalytic monolith in a power generation system. In this concept, a downstream heat source (e.g. a flame) or resistive heating in the downstream portion of the monolith initiates a localized catalytic reaction which subsequently propagates upstream and heats the entire monolith. The simulations used a transient numerical model of a single catalytic channel which characterizes the behavior of the entire monolith. The model treats both the gas and solid phases and includes detailed homogeneous and heterogeneous reactions. An important parameter in the model for back-end ignition is upstream heat conduction along the solid. The simulations used both dry and wet CO chemistry as a model fuel for the proof-of-concept calculations; the presence of water vapor can trigger homogenous reactions, provided that gas-phase temperatures are adequately high and there is sufficient fuel remaining after surface reactions. With sufficiently high inlet equivalence ratio, back-end ignition occurs using the thermophysical properties of both a ceramic and metal monolith (coated with platinum in both cases), with the heat-up times significantly faster for the metal monolith. For lower equivalence ratios, back-end ignition occurs without upstream propagation. Once light-off and propagation occur, the inlet equivalence ratio could be reduced significantly while still maintaining an ignited monolith as demonstrated by calculations using complete monolith heating
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