Eating disordered behaviours in portuguese athletes: the influence of personal, sport, and psychological variables

Objective: This study describes eating disordered behaviours in a sample of Portuguese elite athletes and analyses the impact of personal and sports factors on those eating disordered behaviours. Method: Two hundred and ninety athletes (51.7% males) practicing collective (64.8%) and individual sports have been included. The evaluation protocol included the Eating Disorder Examination Questionnaire; the Sport Condition Questionnaire; the Sport Anxiety Scale; the Task and Ego Orientation in Sport Questionnaire; the Cognitive Evaluation of Sport–Threat Perceptions; and the Self-Presentation Exercise Questionnaire. Results: Females, athletes with a higher body mass index, and those with a desire to weigh less, reported more eating disordered behaviours. No relation with sports variables was found. Finally, a higher prevalence of eating disorders behaviour was predicted by lower satisfaction in terms of body shape and physical appearance, higher anxiety and impression motivation. Conclusion: Personal characteristics of athletes, as well as their body satisfaction, anxiety, impression motivation and threat perception, and coach comments on their weight, represent dimensions that could raise the risk for eating disorders

A calibration disk for the correction of radial errors from chromatic abberation and rotor stretch in the Optima AUC™ analytical ultracentrifuge

Accepted author manuscriptExperiments performed in the analytical ultracentrifuge (AUC) measure sedimentation and diffusion coefficients, as well as the partial concentration of colloidal mixtures of molecules in the solution phase. From this information, their abundance, size, molar mass, density and anisotropy can be determined. The accuracy with which these parameters can be determined depends in part on the accuracy of the radial position recordings and the boundary conditions used in the modeling of the AUC data. The AUC instrument can spin samples at speeds up to 60,000 rpm, generating forces approaching 300,000 g. Forces of this magnitude will stretch the titanium rotors used in the instrument, shifting the boundary conditions required to solve the flow equations used in the modeling of the AUC data. A second source of error is caused by the chromatic aberration resulting from imperfections in the UV–visible absorption optics. Both errors are larger than the optical resolution of currently available instrumentation. Here, we report software routines that correct these errors, aided by a new calibration disk which can be used in place of the counterbalance to provide a calibration reference for each experiment to verify proper operation of the AUC instrument. We describe laboratory methods and software routines in UltraScan that incorporate calibrations and corrections for the rotor stretch and chromatic aberration in order to support Good Manufacturing Practices for AUC data analysis.Ye

Measuring compressibility in the optima AUC™ analytical ultracentrifuge

Accepted author manuscript.A method is described to accurately measure the compressibility of liquids using an analytical ultracentrifuge. The method makes use of very large pressure gradients, which can be generated in the analytical ultracentrifuge at high speeds to induce a maximum compression signal. Taking advantage of the new Optima AUC, which offers 10 micron radial resolution, a novel calibration centerpiece for measuring rotor stretch, and a speed-ramping procedure, even the weak compressibility of liquids like water, typically considered to be incompressible, could be detected. A model using the standard expression for the secant-average bulk modulus describing the relative compression of a liquid in the analytical ultracentrifuge is derived. The model is a function of the loading volume and the hydrostatic pressure generated in the analytical ultracentrifuge, as well as the secant-average bulk modulus. The compressibility of water and toluene were measured and the linear secant-average bulk modulus and meniscus positions were fitted. In addition to the measurement of the compressibility of liquids, applications for this method include an improved prediction of boundary conditions for multi-speed analytical ultracentrifugation experiments to better describe highly heterogeneous systems with analytical speed-ramping procedures, and the prediction of radius-dependent density variations.Ye