We tested the thermogenic hypothesis that reductions in blood pressure and self-reported state anxiety and altered brain electrocortical (electroencephalographic, EEG) activity after acute exercise are due to increased body temperature. Eleven fit [cycle peak O2 consumption (VO2peak) = 57 +/- 5.8 ml.kg-1 x min-1] males (26 +/- 5.8 yr) were randomly assigned to four 20-min conditions in a within-subjects counterbalanced design: 1) thermoneutral (32-35 degrees C) or 2) cold (18-23 degrees C) cycling at 70% VO2peak, 3) passive warm water exposure (39-41 degrees C), and 4) quiet rest (60 dB below ambient; 22 +/- 1 degrees C). All exercise testing was conducted in shoulder-deep water. Esophageal temperature increased equally during thermoneutral cycling (+1.45 +/- 0.05 degrees C) and passive heating (+1.51 +/- 0.06 degrees C), was blunted during cold cycling (+0.40 +/- 0.12 degrees C), and was unchanged at rest. Mean radial arterial pressure (MAP), self-reported state anxiety (State-Trait Anxiety Inventory, STAI), and spontaneous occipital (O1 + O2) and photostimulated temporal (T5 + T6) surface EEG activity (10-20 system) in theta (4-8 Hz), alpha (9-13 Hz), and beta (14-40 Hz) frequency bands were assessed 5 min pre- and 10-15 and 20-25 min postcondition and analyzed in 4- (condition) by-3 (time) repeated-measures analysis of variance (P < 0.05). Results showed a condition-by-time interaction for MAP, which decreased from pre- to 15 min postcondition for thermoneutral cycling (81 +/- 2 to 73 +/- 2.7 mmHg) and passive heating (86 +/- 2.5 to 74 +/- 1.4 mmHg) and persisted at 25 min postcondition.(ABSTRACT TRUNCATED AT 250 WORDS)

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The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported ‘anomalous’ elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

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