An inclined detector geometry for improved X-ray total scattering measurements.

X-ray total scattering measurements are implemented using a digital flat-panel area detector in an inclined geometry and compared with the traditional geometry. The traditional geometry is defined here by the incident X-ray beam impinging on and normal to the center-most pixel of a detector. The inclined geometry is defined here by a detector at a pitch angle α, set to 15° in this case, bisected by the vertical scattering plane. The detector is positioned such that the incident X-ray beam strikes the pixels along the bottom edge and 90° scattered X-rays impinge on the pixels along the top edge. The geometric attributes of the inclined geometry translate into multiple benefits, such as an extension of the measurable scattering range to 90°, a 47% increase in the accessible magnitudes of the reciprocal-space vector Q and a leveling of the dynamic range in the measured total scattering pattern. As a result, a sixfold improvement in signal-to-noise ratios is observed at higher scattering angles, enabling up to a 36-fold reduction in acquisition time. Additionally, the extent of applied modification functions is reduced, decreasing the magnitude of termination ripples and improving the real-space resolution of the pair distribution function G(r). Taken all together, these factors indicate that the inclined geometry produces higher quality data than the traditional geometry, usable for simultaneous Rietveld refinement and total scattering studies.

Psychological impact of electrocardiogram screening in National Collegiate Athletic Association athletes.

PURPOSE: Determine the psychological impact of false-positive ECG screening in National Collegiate Athletic Association (NCAA) athletes. METHODS: Athletes representing seven NCAA institutions received a standardised history, physical examination and ECG interpreted using the 2013 Seattle Criteria. Assessments of health attitudes, anxiety and impact of screening on sport were conducted using validated prescreen and postscreen measurements. RESULTS: 1192 student-athletes participated (55.4% male, median age 19 years, 80.4% Caucasian). 96.8% of athletes had a normal cardiovascular screen, 2.9% had a false-positive ECG and 0.3% were diagnosed with a serious cardiac condition. Prior to screening, 4.5% worried about potentially harbouring cardiac disease and 70.1% preferred knowing about an underlying condition, rather than play sports without this knowledge. There was no difference in anxiety described by athletes with a normal versus false-positive screen (p=0.369). Reported anxiety levels during screening also did not differ when analysed by different gender, race, division of play or sport. Athletes with normal and false-positive screens had similar levels of satisfaction (p=0.714) and would recommend ECG screening to other athletes at similar rates (p=0.322). Compared with athletes with a normal screen, athletes with false-positive results also reported feeling safer during competition (p>0.01). In contrast, athletes with false-positive screens were more concerned about the possibility of sports disqualification (p<0.001) and the potential for developing a future cardiac condition (p<0.001). CONCLUSIONS: Athletes with a false-positive ECG do not experience more anxiety than athletes with a normal screen but do express increased concern regarding sports disqualification and the development of a cardiac disorder. These findings do not justify avoiding advanced cardiovascular screening protocols. Further understanding of athlete experiences could better prepare the practising physician to counsel athletes with an abnormal ECG.