Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated

The anchors of steel wire ropes, testing methods and their results

The present paper introduces an application of the acoustic and thermographic method in the defectoscopic testing of immobile steel wire ropes at the most critical point, the anchor. First measurements and their results by these new defectoscopic methods are shown. In defectoscopic tests at the anchor, the widely used magnetic method gives unreliable results, and therefore presents a problem for steel wire defectoscopy. Application of the two new methods in the steel wire defectoscopy at the anchor point will enable increased safety measures at the anchor of steel wire ropes in bridge, roof, tower and aerial cable lift constructions

Mehanička ispitivanja čeličnih užadi i čeličnih žica

In the article we are dealing with the problems of the steel wires and steel wire ropes testing, which are very often used today, and at the same time some negatives of the standards valid for steel wire rope testing are mentioned. In the article are mentioned also the drawbacks of new European standards which are implemented to the system of Slovak technical standards. From the rope quality assessment point of view the lifting capacity of the rope as a whole is important. In the article is briefly presented new shredder machine, with the maximum shredding force of 2500 kN. The steel wire ropes with 63 mm in diameter and maximum length of 6 m can be tested using this machine.U članku se raspravlja o problematici ispitivanja čeličnih žica i užadi koja se danas vrlo često koriste, a jednovremeno se spominju i negativne karakteristike normi važećih za testiranje čeličnog užeta. U članku su spomenuti i nedostaci novih evropskih standarda koji se uvode u sistem slovačkih tehničkih normi. Sa stajališta procjene kakvoće užeta, važan je kapacitet dizanja u cjelini. U članku je kratko prikazana nova kidalica s maksimalnom snagom kidanja od 2500 kN. Na tom stroju se mogu ispitati čelična užad promjera 63 mm i maksimalne dužine 6 m

Sidra čeličnih žičanih kabela, metode ispitivanja i njihovi rezultati

The present paper introduces an application of the acoustic and thermographic method in the defectoscopic testing of immobile steel wire ropes at the most critical point, the anchor. First measurements and their results by these new defectoscopic methods are shown. In defectoscopic tests at the anchor, the widely used magnetic method gives unreliable results, and therefore presents a problem for steel wire defectoscopy. Application of the two new methods in the steel wire defectoscopy at the anchor point will enable increased safety measures at the anchor of steel wire ropes in bridge, roof, tower and aerial cable lift constructions.U ovom prilogu predstavlja se primjena jedne akustičke i termografske metode u defektoskopskom ispitivanju nepokretnih čeličnih žičanih kablova na najkritičnijoj točki, na sidru. Najprije su prikazana mjerenja i njihovi rezultati dobiveni tim novim defektoskopskim metodama. U defektoskopskim ispitivanjima na sidru naširoko korištena magnetska metoda pruža nepouzdane rezultate te stoga predstavlja problem za defektoskopiju čelične žice. Primjena dviju novih metoda u defektoskopiji čelične žice na točki sidra omogućit će uporabu mjera veće sigurnosti na sidru čeličnih žičanih kablova u konstrukcijama mostova, krovova, tornjeva, žičara

Sidra čeličnih žičanih kabela, metode ispitivanja i njihovi rezultati

The present paper introduces an application of the acoustic and thermographic method in the defectoscopic testing of immobile steel wire ropes at the most critical point, the anchor. First measurements and their results by these new defectoscopic methods are shown. In defectoscopic tests at the anchor, the widely used magnetic method gives unreliable results, and therefore presents a problem for steel wire defectoscopy. Application of the two new methods in the steel wire defectoscopy at the anchor point will enable increased safety measures at the anchor of steel wire ropes in bridge, roof, tower and aerial cable lift constructions.U ovom prilogu predstavlja se primjena jedne akustičke i termografske metode u defektoskopskom ispitivanju nepokretnih čeličnih žičanih kablova na najkritičnijoj točki, na sidru. Najprije su prikazana mjerenja i njihovi rezultati dobiveni tim novim defektoskopskim metodama. U defektoskopskim ispitivanjima na sidru naširoko korištena magnetska metoda pruža nepouzdane rezultate te stoga predstavlja problem za defektoskopiju čelične žice. Primjena dviju novih metoda u defektoskopiji čelične žice na točki sidra omogućit će uporabu mjera veće sigurnosti na sidru čeličnih žičanih kablova u konstrukcijama mostova, krovova, tornjeva, žičara

Role of somatosensory and vestibular cues in attenuating visually induced human postural sway

The purpose was to determine the contribution of visual, vestibular, and somatosensory cues to the maintenance of stance in humans. Postural sway was induced by full field, sinusoidal visual surround rotations about an axis at the level of the ankle joints. The influences of vestibular and somatosensory cues were characterized by comparing postural sway in normal and bilateral vestibular absent subjects in conditions that provided either accurate or inaccurate somatosensory orientation information. In normal subjects, the amplitude of visually induced sway reached a saturation level as stimulus amplitude increased. The saturation amplitude decreased with increasing stimulus frequency. No saturation phenomena was observed in subjects with vestibular loss, implying that vestibular cues were responsible for the saturation phenomenon. For visually induced sways below the saturation level, the stimulus-response curves for both normal and vestibular loss subjects were nearly identical implying that (1) normal subjects were not using vestibular information to attenuate their visually induced sway, possibly because sway was below a vestibular-related threshold level, and (2) vestibular loss subjects did not utilize visual cues to a greater extent than normal subjects; that is, a fundamental change in visual system 'gain' was not used to compensate for a vestibular deficit. An unexpected finding was that the amplitude of body sway induced by visual surround motion could be almost three times greater than the amplitude of the visual stimulus in normals and vestibular loss subjects. This occurred in conditions where somatosensory cues were inaccurate and at low stimulus amplitudes. A control system model of visually induced postural sway was developed to explain this finding. For both subject groups, the amplitude of visually induced sway was smaller by a factor of about four in tests where somatosensory cues provided accurate versus inaccurate orientation information. This implied that (1) the vestibular loss subjects did not utilize somatosensory cues to a greater extent than normal subjects; that is, changes in somatosensory system 'gain' were not used to compensate for a vestibular deficit, and (2) the threshold for the use of vestibular cues in normals was apparently lower in test conditions where somatosensory cues were providing accurate orientation information

Upcoming Neurophotonics Status Report

Forthcoming status report articles provide updates on microscopy and on diffuse optical imaging in neurophotonics

Re-weighting of somatosensory inputs from the foot and the ankle for controlling posture during quiet standing following trunk extensor muscles fatigue

The present study focused on the effects of trunk extensor muscles fatigue on postural control during quiet standing under different somatosensory conditions from the foot and the ankle. With this aim, 20 young healthy adults were asked to stand as immobile as possible in two conditions of No fatigue and Fatigue of trunk extensor muscles. In Experiment 1 (n = 10), somatosensation from the foot and the ankle was degraded by standing on a foam surface. In Experiment 2 (n = 10), somatosensation from the foot and ankle was facilitated through the increased cutaneous feedback at the foot and ankle provided by strips of athletic tape applied across both ankle joints. The centre of foot pressure displacements (CoP) were recorded using a force platform. The results showed that (1) trunk extensor muscles fatigue increased CoP displacements under normal somatosensatory conditions (Experiment 1 and Experiment 2), (2) this destabilizing effect was exacerbated when somatosensation from the foot and the ankle was degraded (Experiment 1), and (3) this destabilizing effect was mitigated when somatosensation from the foot and the ankle was facilitated (Experiment 2). Altogether, the present findings evidenced re-weighting of sensory cues for controlling posture during quiet standing following trunk extensor muscles fatigue by increasing the reliance on the somatosensory inputs from the foot and the ankle. This could have implications in clinical and rehabilitative areas

Mehanička ispitivanja čeličnih užadi i čeličnih žica

In the article we are dealing with the problems of the steel wires and steel wire ropes testing, which are very often used today, and at the same time some negatives of the standards valid for steel wire rope testing are mentioned. In the article are mentioned also the drawbacks of new European standards which are implemented to the system of Slovak technical standards. From the rope quality assessment point of view the lifting capacity of the rope as a whole is important. In the article is briefly presented new shredder machine, with the maximum shredding force of 2500 kN. The steel wire ropes with 63 mm in diameter and maximum length of 6 m can be tested using this machine.U članku se raspravlja o problematici ispitivanja čeličnih žica i užadi koja se danas vrlo često koriste, a jednovremeno se spominju i negativne karakteristike normi važećih za testiranje čeličnog užeta. U članku su spomenuti i nedostaci novih evropskih standarda koji se uvode u sistem slovačkih tehničkih normi. Sa stajališta procjene kakvoće užeta, važan je kapacitet dizanja u cjelini. U članku je kratko prikazana nova kidalica s maksimalnom snagom kidanja od 2500 kN. Na tom stroju se mogu ispitati čelična užad promjera 63 mm i maksimalne dužine 6 m