Normal and abnormal human vestibular ocular function

The major motivation of this research is to understand the role the vestibular system plays in sensorimotor interactions which result in spatial disorientation and motion sickness. A second goal was to explore the range of abnormality as it is reflected in quantitative measures of vestibular reflex responses. The results of a study of vestibular reflex measurements in normal subjects and preliminary results in abnormal subjects are presented in this report. Statistical methods were used to define the range of normal responses, and determine age related changes in function

Age-related changes in human posture control: Motor coordination tests

Postural responses to support surface displacements were measured in 214 normal human subjects ranging in age from 7 to 81 years. Motor tests measured leg muscle Electromyography (EMG) latencies, body sway, and the amplitude and timing of changes in center of pressure displacements in response to sudden forward and backward horizontal translations of the support surface upon which the subjects stood. There were small increases in both EMG latencies and the time to reach the peak amplitude of center of pressure responses with increasing age. The amplitude of center of pressure responses showed little change with age if the amplitude measures were normalized by a factor related to subject height. In general, postural responses to sudden translations showed minimal changes with age, and all age related trends which were identified were small relative to the variability within the population

Age-related changes in human posture control: Sensory organization tests

Postural control was measured in 214 human subjects ranging in age from 7 to 81 years. Sensory organization tests measured the magnitude of anterior-posterior body sway during six 21 s trials in which visual and somatosensory orientation cues were altered (by rotating the visual surround and support surface in proportion to the subject's sway) or vision eliminated (eyes closed) in various combinations. No age-related increase in postural sway was found for subjects standing on a fixed support surface with eyes open or closed. However, age-related increases in sway were found for conditions involving altered visual or somatosensory cues. Subjects older than about 55 years showed the largest sway increases. Subjects younger than about 15 years were also sensitive to alteration of sensory cues. On average, the older subjects were more affected by altered visual cues whereas younger subjects had more difficulty with altered somatosensory cues

Heliostat-array wind-tunnel study

CER78-79RLE-JAP-JEC31.Prepared for Martin Marietta Aerospace.Includes bibliographical references (page 24).January 1979

Wind-tunnel study of wind over an offshore platform helideck

CER78-79RE-JAP-JBC25.Prepared for Earl and Wright Consulting Engineers.Includes bibliographical references (page 16).December 1978

Wind tunnel site analysis of Dow Chemical Facility at Rocky Flats, Colorado, part II

Prepared for Research and Ecology, Rocky Flats Division, Dow Chemical Company.CER72-73RNM-JAP-TGH-16.March 1973.Includes bibliographical references.This report deals with two separate problems occurring at the Dow Chemical Company Plutonium Recovery Facility, Rocky Flats Division, namely the dispersion of potential effluents and the protection of parking areas from the destructive action of high velocity west winds by the use of shelterbelts. The dispersion study is a continuation of a previous study and consisted of modeling the geography, wind and turbulence profiles and effluent releases in a wind tunnel study. Dispersion and trajectory behavior was determined by the use of Krypton-85 as a tracer gas. The results reinforce the conclusion advanced in the previous study that Pasquill-Gifford prediction methods apply well to the site. The shelterbelt study consisted of evaluating the effects of porosity, barrier height and length, geometric configuration of barriers, parking lot orientation and wind approach angle upon the protection of parking areas from high velocity wind action in assaulting vehicles with abrasive particles. Tests were accomplished by observing the effectiveness of the wind in transporting a zinc oxide-mineral oil suspension. This effectiveness was correlated to velocity reduction and wind profile modification effectiveness of shelterbelts. It was found that the most effective use of shelterbelts could be accomplished if the parking lot were reoriented with the long side running in a north-south direction

Age-related changes in human vestibulo-ocular reflexes: Sinusoidal rotation and caloric tests

The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR dynamics, and to identify the distributions of parameters which describe VOR responses to caloric and to sinusoidal rotational stimuli in a putatively normal population. Caloric test parameters showed no consistent trend with age. Rotation test parameters showed declining response amplitude and slightly less compensatory response phase with increasing age. The magnitudes of these changes were not large relative to the variability within the population. The age-related trends in VOR were not consistent with the anatomic changes in the periphery reported by others which showed an increasing rate of peripheral hair cell and nerve fiber loss in subjects over 55 years. The poor correlation between physiological and anatomical data suggest that adaptive mechanisms in the central nervous system are important in maintaining the VOR

Age-related changes in human vestibulo-ocular and optokinetic reflexes: Pseudorandom rotation tests

The dynamic response properties of horizontal vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) were characterized in 216 human subjects ranging in age from 7 to 81 years. The object of this cross-sectional study was to determine the effects of aging on VOR and OKR reflex dynamics, and to identify the distributions of parameters which describe VOR and OKR responses to pseudorandom stimuli in a putatively normal population. In general, VOR and OKR response parameters changed in a manner consistent with declining function with increasing age. For the VOR this was reflected in declining response amplitudes, although the magnitude of the decline was small relative to the variability of the data. For the OKR the lag time of the response, probably associated with the time required for visual information processing, increased linearly with age at a rate of about 1 ms per year

Strike point splitting induced by the application of magnetic perturbations on MAST

Divertor strike point splitting induced by resonant magnetic perturbations (RMPs) has been observed on MAST for a variety of RMP configurations in a plasma scenario with Ip=750kA where those configurations all have similar resonant components. Complementary measurements have been obtained with divertor Langmuir probes and an infrared camera. Clear splitting consistently appears in this scenario only in the even configuration of the perturbation coils, similarly to the density pump-out. These results present a challenge for models of plasma response to RMPs.Comment: 9 pages, 4 figures, submitted to the proceedings of the 20th Conference on Plasma Surface Interactions, to be published in the Journal of Nuclear Material