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Recorded head kinematics from head-impact measurement devices (HIMd) are pivotal for evaluating brain stress and strain through head finite element models (hFEM). The variability in kinematic recording windows across HIMd presents challenges as they yield inconsistent hFEM responses. Despite establishing an ideal recording window for maximum principal strain (MPS) in brain tissue, uncertainties persist about the impact characteristics influencing vulnerability when this window is shortened. This study aimed to scrutinize factors within impact kinematics affecting the reliability of different recording windows on whole-brain peak MPS using a validated hFEM. Utilizing 53 on-field head impacts recorded via an instrumented mouthguard during a Canadian varsity football game, 10 recording windows were investigated with varying pre- and post-impact-trigger durations. Tukey pair-wise comparisons revealed no statistically significant differences in MPS responses for the different recording windows. However, specific impacts showed marked variability up to 40%. It was found, through correlation analyses, that impacts with lower peak linear acceleration exhibited greater response variability across different pre-trigger durations. Signal shape, analyzed through spectral analysis, influenced the time required for MPS development, resulting in specific impacts requiring a prolonged post-trigger duration. This study adds to the existing consensus on standardizing HIMd acquisition time windows and sheds light on impact characteristics leading to peak MPS variation across different head impact kinematic recording windows. Considering impact characteristics in research assessments is crucial, as certain impacts, affected by recording duration, may lead to significant errors in peak MPS responses during cumulative longitudinal exposure assessments., (© 2024. The Author(s) under exclusive licence to Biomedical Engineering Society.)

Herein, precision recording of indented dots and lines in As10Se90 and As2S3 chalcogenide glass films by a focused laser beam is demonstrated and the kinetics and mechanisms of mass transfer under illumination are studied. Due to inhomogeneous intensity distribution and local heating of the film at the focal point, the beam at rest produces an indentation whose depth increases with time and laser power. Illumination by a moving beam leads to formation of groves whose morphology depends on the beam speed and power. At low light intensities, formation of the indentations occurs in the solid phase, due to photoinduced radial diffusion of the film constituents coupled with electrons and holes created by light. The two main driving forces present are: 1) a lateral steady‐state electric field formed due to different mobilities of electrons and holes and 2) driving force of thermodiffusion (Soret effect). At high light intensities, formation of the indentations and grooves occurs with the participation of a liquid phase, with an additional mechanism of viscous flow caused by a gradient in surface tension. However, the contribution of viscous flow mechanism is small compared with diffusion mass transfer. Calculated profiles of the indentations and grooves are in a good agreement with experimental data. [ABSTRACT FROM AUTHOR]