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vertical velocity storage

Sergei B Yakushin, Theodore Raphan, Bernard Cohen
Semicircular canal afferents sense angular acceleration and output angular velocity with a short time constant of ≈4.5 s. This output is prolonged by a central integrative network, velocity storage that lengthens the time constants of eye velocity. This mechanism utilizes canal, otolith, and visual (optokinetic) information to align the axis of eye velocity toward the spatial vertical when head orientation is off-vertical axis. Previous studies indicated that vestibular-only (VO) and vestibular-pause-saccade (VPS) neurons located in the medial and superior vestibular nucleus could code all aspects of velocity storage...
2017: Frontiers in Neurology
F C Zuma E Maia, Renato Cal, Ricardo D'Albora, Sergio Carmona, Michael C Schubert
Tilt suppression refers to both tilting the head away from an Earth vertical axis and a reduction of an induced horizontal nystagmus. This phenomenon of reducing an induced horizontal nystagmus involves a circuitry of neurons within the vestibular nuclei and the cerebellum (collectively referred to as velocity storage) and signals from the otolith end organs. Lesions involving this circuitry can disrupt tilt suppression of induced horizontal nystagmus. We investigated the clinical value of combining the horizontal head-shaking nystagmus test with tilt suppression in 28 patients with unilateral peripheral vestibular hypofunction and 11 patients with lesions affecting the central nervous system...
June 2017: Journal of Neurology
Guanhua Lv, Jinxiang Li, Shao-Long Tie, Sheng Lan
The influence of a three-dimensional (3D) photonic crystal (PC) on the plasmonic properties of gold nanorods (GNRs), which are placed on the surface of the PC, was investigated both numerically and experimentally. The 3D PC formed by closely packed polystyrene spheres was fabricated by using a pressure controlled isothermal heating vertical deposition technique. For a GNR whose longitudinal surface plasmon resonance (LSPR) is located at the bandgap edges of the PC, a dramatic narrowing of the absorption spectrum as well as an enhancement in electric field and thus the absorption was observed...
June 27, 2016: Optics Express
Giuseppe D'Avenio, Mauro Grigioni, Carla Daniele, Umberto Morbiducci, Kathrin Hamilton
BACKGROUND: Prosthetic heart valves can be associated to mechanical loading of blood, potentially linked to complications (hemolysis and thrombogenicity) which can be clinically relevant. In order to test such devices in pulsatile mode, pulse duplicators (PDs) have been designed and built according to different concepts. This study was carried out to compare anemometric measurements made on the same prosthetic device, with two widely used PDs. METHODS: The valve (a 27-mm bileaflet valve) was mounted in the aortic section of the PD...
2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Pieter S Pauw, Sjoerd E A T M van der Zee, Anton Leijnse, Gualbert H P Oude Essink
This article deals with the quantification of saltwater upconing below horizontal wells in freshwater lenses using analytical solutions as a computationally fast alternative to numerical simulations. Comparisons between analytical calculations and numerical simulations are presented regarding three aspects: (1) cyclic pumping; (2) dispersion; and (3) finite horizontal wells in a finite domain (a freshwater lens). Various hydrogeological conditions and pumping regimes within a dry half year are considered. The results show that the influence of elastic and phreatic storage (which are not taken into account in the analytical solutions) on the upconing of the interface is minimal...
July 2016: Ground Water
N Shimizu, S Wood, K Kushiro, S Yanai, A Perachio, T Makishima
The central vestibular system plays an important role in higher neural functions such as self-motion perception and spatial orientation. Its ability to store head angular velocity is called velocity storage mechanism (VSM), which has been thoroughly investigated across a wide range of species. However, little is known about the mouse VSM, because the mouse lacks typical ocular responses such as optokinetic after nystagmus or a dominant time constant of vestibulo-ocular reflex for which the VSM is critical. Experiments were conducted to examine the otolith-driven eye movements related to the VSM and verify its characteristics in mice...
January 29, 2015: Neuroscience
C H Kim, J E Shin, C I Song, M H Yoo, H J Park
OBJECTIVES: To describe vertical and horizontal components of head-shaking nystagmus (HSN) in various vestibular disorders. DESIGN: Retrospective case review. SETTING: Tertiary care academic referral centre. PARTICIPANTS: Head-shaking nystagmus was assessed in 66 vestibular neuritis (VN) patients at acute (<7 days) and follow-up (2 months), and 65 Meniere's disease (MD) and 76 migrainous vertigo (MV) in interictal period...
October 2014: Clinical Otolaryngology
Brandon Schmandt, Steven D Jacobsen, Thorsten W Becker, Zhenxian Liu, Kenneth G Dueker
The high water storage capacity of minerals in Earth's mantle transition zone (410- to 660-kilometer depth) implies the possibility of a deep H2O reservoir, which could cause dehydration melting of vertically flowing mantle. We examined the effects of downwelling from the transition zone into the lower mantle with high-pressure laboratory experiments, numerical modeling, and seismic P-to-S conversions recorded by a dense seismic array in North America. In experiments, the transition of hydrous ringwoodite to perovskite and (Mg,Fe)O produces intergranular melt...
June 13, 2014: Science
Benjamin D Robertson, Gregory S Sawicki
We present a simplified Hill-type model of the human triceps surae-Achilles tendon complex working on a gravitational-inertial load during cyclic contractions (i.e. vertical hopping). Our goal was to determine the role that neural control plays in governing muscle, or contractile element (CE), and tendon, or series elastic element (SEE), mechanics and energetics within a compliant muscle-tendon unit (MTU). We constructed a 2D parameter space consisting of many combinations of stimulation frequency and magnitude (i...
July 21, 2014: Journal of Theoretical Biology
Takeshi Tsutsumi, Takuo Ikeda, Shigeru Kikuchi
OBJECTIVE: To document a patient with periodic alternating nystagmus (PAN) caused by acute disseminated encephalomyelitis (ADEM) and suggest a mechanism to explain her PAN. PATIENT: A 34-year-old woman with PAN caused by ADEM. INTERVENTION: Diagnostic. RESULTS: The patient complained of severe disequilibrium from the disease onset. Four years after onset, when she visited us, the patient exhibited prominent PAN consisting of alternating rightward and leftward components, which cycled about every 90 seconds and were accompanied by a 5-second translating phase with downbeating nystagmus...
June 2014: Otology & Neurotology
Luke Chen, G Michael Halmagyi, Michael J Todd, Swee T Aw
Gaucher's disease (GD) is a hereditary lysosomal storage disease characterized by abnormal deposition of glucocerebroside due to the enzyme glucocerebrosidase deficiency, resulting in multi-organ pathology. GD type III has a progressive neurological involvement. We studied the vestibular and saccadic abnormalities in GD type III to determine if these parameters may be useful for assessing neurological involvement. We evaluated the vestibular and saccadic responses of two siblings with genetically identified GD type III on enzyme replacement therapy...
2014: JIMD Reports
Mario Lamontagne, Matthew J Kennedy
Repetitive vertical hopping is a simple and relatively controlled task useful for studying basic neuromuscular properties and tissue mechanics. However, several biomechanical and physiological factors are involved. This article provides an overview of muscle and tendon properties and how these interact during vertical hopping. Muscle properties discussed are force-velocity and force-length relationships, electromechanical delay, muscle fiber type, stretch induced contraction amplification, and muscle spindle afferent feedback...
2013: Research in Sports Medicine
Aasef G Shaikh, Sarah Marti, Alexander A Tarnutzer, Antonella Palla, Thomas O Crawford, David S Zee, Dominik Straumann
Ataxia-telangiectasia (A-T) is a progressive neurodegenerative disorder with prominent eye movement deficits localizing to the cerebellum. We sought to determine if 4-aminopyridine (4-AP), which putatively enhances the precision of Purkinje neurons, could improve the disorders of eye movements and vestibular function in A-T. The influence of 4-AP on disorders of eye movements and vestibular function was studied in four A-T patients. The effects on the cerebellar control of vestibulo-ocular reflex (VOR) was quantitatively assessed by the decay time constant of per- and post-rotational nystagmus during constant velocity en bloc rotations...
November 2013: Journal of Neurology
J Perez-Gomez, J A L Calbet
AIM: This study aims to review the main methods used to improve vertical jump performance (VJP). METHODS: Although many training routines have been proposed, these can be grouped into four main categories: plyometric training (PT), weight training (WT), whole body vibration training (VT) and electromyostimulation training (ET). PT enhances muscular force, the rate of force development (RFD), muscular power, muscle contraction velocity, cross-sectional area (CSA), muscle stiffness allowing greater storage and release of elastic energy...
August 2013: Journal of Sports Medicine and Physical Fitness
Peter J Metaxas, Joao Sampaio, André Chanthbouala, Rie Matsumoto, Abdelmadjid Anane, Albert Fert, Konstantin A Zvezdin, Kay Yakushiji, Hitoshi Kubota, Akio Fukushima, Shinji Yuasa, Kazumasa Nishimura, Yoshinori Nagamine, Hiroki Maehara, Koji Tsunekawa, Vincent Cros, Julie Grollier
Domain walls, nanoscale transition regions separating oppositely oriented ferromagnetic domains, have significant promise for use in spintronic devices for data storage and memristive applications. The state of these devices is related to the wall position and thus rapid operation will require a controllable onset of domain wall motion and high speed wall displacement. These processes are traditionally driven by spin transfer torque due to lateral injection of spin polarized current through a ferromagnetic nanostrip...
2013: Scientific Reports
Marcus Hardie, Shaun Lisson, Richard Doyle, William Cotching
Preferential flow in agricultural soils has been demonstrated to result in agrochemical mobilisation to shallow ground water. Land managers and environmental regulators need simple cost effective techniques for identifying soil - land use combinations in which preferential flow occurs. Existing techniques for identifying preferential flow have a range of limitations including; often being destructive, non in situ, small sampling volumes, or are subject to artificial boundary conditions. This study demonstrated that high frequency soil moisture monitoring using a multi-sensory capacitance probe mounted within a vertically rammed access tube, was able to determine the occurrence, depth, and wetting front velocity of preferential flow events following rainfall...
January 2013: Journal of Contaminant Hydrology
Bence Kopper, Zsolt Csende, Sándor Sáfár, Tibor Hortobágyi, József Tihanyi
In the present study we investigated displacement, time, velocity and acceleration history of center of mass (COM) and electrical activity of knee extensors to estimate the dominance of the factors influencing the vertical velocity in squat jumps (SJs), countermovement jumps (CMJs) and drop jumps (DJs) performed with small (40°) and large (80°) range of joint motion (SROM and LROM). The maximum vertical velocity (v4) was 23.4% (CMJ) and 7.8% (DJ) greater when the jumps were performed with LROM compared with SROM (p < 0...
February 2013: Journal of Electromyography and Kinesiology
G Mauroy, B Schepens, P A Willems
When leaping an obstacle, the runner increases the vertical velocity of his/her centre of mass (COM) at takeoff to augment the amplitude and duration of the aerial phase over it. This study analyses the modification of the bouncing mechanism of running when approaching a barrier. The forces exerted by the feet on the ground are measured by a 13-m-long force platform during the four to nine running steps preceding the jump over a 0.45- to 0.85-m-high barrier, at an approaching speed between 9 and 21 km h(-1)...
April 2013: European Journal of Applied Physiology
Giovanni Bertolini, Stefano Ramat, Christopher J Bockisch, Sarah Marti, Dominik Straumann, Antonella Palla
BACKGROUND: The rotational vestibulo-ocular reflex (rVOR) generates compensatory eye movements in response to rotational head accelerations. The velocity-storage mechanism (VSM), which is controlled by the vestibulo-cerebellar nodulus and uvula, determines the rVOR time constant. In healthy subjects, it has been suggested that self-motion perception in response to earth-vertical axis rotations depends on the VSM in a similar way as reflexive eye movements. We aimed at further investigating this hypothesis and speculated that if the rVOR and rotational self-motion perception share a common VSM, alteration in the latter, such as those occurring after a loss of the regulatory control by vestibulo-cerebellar structures, would result in similar reflexive and perceptual response changes...
2012: PloS One
Richard F Lewis, Csilla Haburcakova, Wangsong Gong, Faisal Karmali, Daniel M Merfeld
To investigate the characteristics of eye movements produced by electrical stimulation of semicircular canal afferents, we studied the spatial and temporal features of eye movements elicited by short-term lateral canal stimulation in two squirrel monkeys with plugged lateral canals, with the head upright or statically tilted in the roll plane. The electrically induced vestibuloocular reflex (eVOR) evoked with the head upright decayed more quickly than the stimulation signal provided by the electrode, demonstrating an absence of the classic velocity storage effect that improves the dynamics of the low-frequency VOR...
September 2012: Journal of Neurophysiology
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