Sleep disorder following traumatic brain injury: an investigation of the predictors of sleep disorder 12 months or more following traumatic brain injury

OBJECTIVE: The purpose was to identify the characteristics predictive of sleep disorder in a sample of traumatic brain injury (TBI) patients, twelve months or more following trauma.DESIGN: A between-subject design explored the relationship between the participant's sleep disturbance and the severity of TBI. A within-subjects design investigated reliability of the sleep disorder self-report and explored differences between ratings of the participant and a significant other. In addition, qualitative analysis based on content analysis, investigated themes relating to sleep experiences generated by a semi-structured interviewPARTICIPANTS: Eighteen males and 15 significant others were recruited from patients who were admitted to The Scottish Brain Injury Unit (SBIRS) between June 2002 and June 1997. The participants were predominantly in tire severe TBI category.MEASURES: The following were the factors measured, and the instruments used for this purpose: sleep quality (The Pittsburgh Sleep Index; PSQI), psychological distress (Hamilton rating Scale for Depression, HRSD; Hospital Anxiety and Depression Scale, HADS) and fatigue (Bentall fatigue inventory and a Visual Analogue Scale, VAS-F). Significant others completed only the PSQI.RESULTS: Fifty per cent of the sample reported poor sleep quality and 22 per cent of the participants had insomnia. Among the demographic, affective and injury variables examined, the strongest relationship with sleep quality was linked to depression. The significant other ratings were no different to the participant's self-ratings. Interestingly, sleep quality rather than TBI severity appeared linked to depressionCONCLUSIONS: This sample has reported slightly lower rates of sleep disturbance than a comparable post acute population but this is still more than double the rate of sleep disturbance in the normal population. There was evidence that links may be between poor sleep quality and depression, perhaps even depression secondary to insomnia, rather than TBI. In addition TBI is considered as a model for depression. The importance of evaluating treatments for insomnia in this group is discussed

Transonic small disturbances equation applied to the solution of two-dimensional nonsteady flows

Transonic nonsteady flows are of large practical interest. Aeroelastic instability prediction, control figured vehicle techniques or rotary wings in forward flight are some examples justifying the effort undertaken to improve knowledge of these problems is described. The numerical solution of these problems under the potential flow hypothesis is described. The use of an alternating direction implicit scheme allows the efficient resolution of the two dimensional transonic small perturbations equation

Order Out of Chaos: Slowly Reversing Mean Flows Emerge from Turbulently Generated Internal Waves

We demonstrate via direct numerical simulations that a periodic, oscillating mean flow spontaneously develops from turbulently generated internal waves. We consider a minimal physical model where the fluid self-organizes in a convective layer adjacent to a stably stratified one. Internal waves are excited by turbulent convective motions, then nonlinearly interact to produce a mean flow reversing on timescales much longer than the waves' period. Our results demonstrate for the first time that the three-scale dynamics due to convection, waves, and mean flow is generic and hence can occur in many astrophysical and geophysical fluids. We discuss efforts to reproduce the mean flow in reduced models, where the turbulence is bypassed. We demonstrate that wave intermittency, resulting from the chaotic nature of convection, plays a key role in the mean-flow dynamics, which thus cannot be captured using only second-order statistics of the turbulent motions