4,495 research outputs found
Perfectionism and burnout in canoe polo and kayak slalom athletes: The mediating influence of validation and growth-seeking
Recent research suggests that validation-seeking and dimensions of perfectionism may be antecedents of athlete burnout. The present investigation examined whether validation and growth-seeking mediate the relationship between selforiented and socially prescribed perfectionism and burnout. One-hundred and fifty canoe polo and kayak slalom athletes recruited from the top two divisions in the UK completed measures of validation and growth-seeking (GOI), perfectionism (HMPS), and athlete burnout (ABQ). Analyses supported the mediating role of validation-seeking in the relationship between socially prescribed perfectionism and burnout. However, while bivariate correlations indicated that self-oriented perfectionism was positively related to both validation and growth-seeking, neither mediated the self-oriented perfectionism-burnout relationship. The findings suggest that validation-seeking may be an important psychological factor in the development of burnout for athletes exhibiting high levels of socially prescribed perfectionism. The relationship between self-oriented perfectionism and athlete burnout remains unclear because of its association with multiple motives and with socially prescribed perfectionism
Development and initial validation of the Performance Perfectionism Scale for Sport (PPS-S)
Valid and reliable instruments are required to appropriately study perfectionism. With this in mind, three studies are presented that describe the development and initial validation of a new instrument designed to measure multidimensional performance perfectionism for use in sport (Performance Perfectionism ScaleâSport [PPS-S]). The instrument is based on Hewitt and Flettâs (1991) model of perfectionism and includes self-oriented, socially prescribed, and other-oriented performance perfectionism. These dimensions encapsulate the features of Hewitt and Flettâs dimensions but are focused on athletic performance rather than life generally. The three studies outline item generation and refinement, exploratory, confirmatory, and exploratory-confirmatory examination of factor structure, and initial assessment of construct validity in multiple samples of adolescent and young adult athletes. Findings suggest that the PPS-S is likely to be a reliable and valid measure of performance perfectionism in youth sport. As validation continues, we expect the instrument to have wider applicability for use in adults and other performance contexts (e.g., education and work)
The relative importance of macrophysical and cloud albedo changes for aerosol-induced radiative effects in closed-cell stratocumulus: insight from the modelling of a case study
Aerosolâcloud interactions are explored using 1âŻkm simulations of a case study of predominantly closed-cell SE Pacific stratocumulus clouds. The simulations include realistic meteorology along with newly implemented cloud microphysics and sub-grid cloud schemes. The model was critically assessed against observations of liquid water path (LWP), broadband fluxes, cloud fraction (fc), droplet number concentrations (Nd), thermodynamic profiles, and radar reflectivities. Aerosol loading sensitivity tests showed that at low aerosol loadings, changes to aerosol affected shortwave fluxes equally through changes to cloud macrophysical characteristics (LWP, fc) and cloud albedo changes due solely to Nd changes. However, at high aerosol loadings, only the Nd albedo change was important. Evidence was also provided to show that a treatment of sub-grid clouds is as important as order of magnitude changes in aerosol loading for the accurate simulation of stratocumulus at this grid resolution. Overall, the control model demonstrated a credible ability to reproduce observations, suggesting that many of the important physical processes for accurately simulating these clouds are represented within the model and giving some confidence in the predictions of the model concerning stratocumulus and the impact of aerosol. For example, the control run was able to reproduce the shape and magnitude of the observed diurnal cycle of domain mean LWP to within ââŒââŻ10âŻgâmâ2 for the nighttime, but with an overestimate for the daytime of up to 30âŻgâmâ2. The latter was attributed to the uniform aerosol fields imposed on the model, which meant that the model failed to include the low-Nd mode that was observed further offshore, preventing the LWP removal through precipitation that likely occurred in reality. The boundary layer was too low by around 260âŻm, which was attributed to the driving global model analysis. The shapes and sizes of the observed bands of clouds and open-cell-like regions of low areal cloud cover were qualitatively captured. The daytime fc frequency distribution was reproduced to within Îfcâ=â0.04 for fcâ>âââŒâ0.7 as was the domain mean nighttime fc (at a single time) to within Îfcâ=â0.02. Frequency distributions of shortwave top-of-the-atmosphere (TOA) fluxes from the satellite were well represented by the model, with only a slight underestimate of the mean by 15âŻ%; this was attributed to nearâshore aerosol concentrations that were too low for the particular times of the satellite overpasses. TOA long-wave flux distributions were close to those from the satellite with agreement of the mean value to within 0.4âŻ%. From comparisons of Nd distributions to those from the satellite, it was found that the Nd mode from the model agreed with the higher of the two observed modes to within ââŒââŻ15âŻ%
Image segmentation using a texture gradient based watershed transform
Abstract â The segmentation of images into meaningful and homogenous regions is a key method for image analy-sis within applications such as content based retrieval. The watershed transform is a well established tool for the seg-mentation of images. However, watershed segmentation is often not effective for textured image regions that are per-ceptually homogeneous. In order to properly segment such regions the concept of the âtexture gradient â is now intro-duced. Texture information and its gradient are extracted using a novel non-decimated form of a complex wavelet transform. A novel marker location algorithm is subse-quently used to locate significant homogeneous textured or non textured regions. A marker driven watershed transform is then used to properly segment the identified regions. The combined algorithm produces effective texture and intensity based segmentation for the application to content based im-age retrieval
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