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Sample records for sinusoidal galvanic vestibular

  1. A study on vestibular-evoked myogenic potentials via galvanic vestibular stimulation in normal people

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    Ying Cheng

    2018-03-01

    Discussions: Galvanic vestibular stimulation could elicit biphasic EMG responses from SCM via the vestibular nerve but not from the otolith organs. Galvanic stimulation together with air conducted sound (ACS or bone conducted vibration (BCV can elicit VEMPs and may enable the differentiation of retrolabyrinthine lesions from labyrinthine lesions in vestibular system.

  2. Galvanic vestibular stimulation speeds visual memory recall.

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    Wilkinson, David; Nicholls, Sophie; Pattenden, Charlotte; Kilduff, Patrick; Milberg, William

    2008-08-01

    The experiments of Alessandro Volta were amongst the first to indicate that visuo-spatial function can be altered by stimulating the vestibular nerves with galvanic current. Until recently, the beneficial effects of the procedure were masked by the high levels of electrical current applied, which induced nystagmus-related gaze deviation and spatial disorientation. However, several neuropsychological studies have shown that much weaker, imperceptible currents that do not elicit unpleasant side-effects can help overcome visual loss after stroke. Here, we show that visual processing in neurologically healthy individuals can also benefit from galvanic vestibular stimulation. Participants first learnt the names of eight unfamiliar faces and then after a short delay, answered questions from memory about how pairs of these faces differed. Mean correct reaction times were significantly shorter when sub-sensory, noise-enhanced anodal stimulation was administered to the left mastoid, compared to when no stimulation was administered at all. This advantage occurred with no loss in response accuracy, and raises the possibility that the procedure may constitute a more general form of cognitive enhancement.

  3. Evaluation of Galvanic Vestibular Stimulation System

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    Kofman, I. S.; Warren, E.; DeSoto, R.; Moroney, G.; Chastain, J.; De Dios, Y. E.; Gadd, N.; Taylor, L.; Peters, B. T.; Allen, E.; hide

    2017-01-01

    Microgravity exposure results in an adaptive central reinterpretation of information from multiple sensory sources to produce a sensorimotor state appropriate for motor actions in this unique environment, but this new adaptive state is no longer appropriate for the 1-g gravitational environment on Earth. During these gravitational transitions, astronauts experience deficits in both perceptual and motor functions including impaired postural control, disruption in spatial orientation, impaired control of locomotion that include alterations in muscle activation variability, modified lower limb kinematics, alterations in head-trunk coordination as well as reduced dynamic visual acuity. Post-flight changes in postural and locomotor control might have adverse consequences if a rapid egress was required following a long-duration mission, where support personnel may not be available to aid crewmembers. The act of emergency egress includes, but is not limited to standing, walking, climbing a ladder, jumping down, monitoring displays, actuating discrete controls, operating auxiliary equipment, and communicating with Mission Control and recovery teams while maintaining spatial orientation, mobility and postural stability in order to escape safely. The average time to recover impaired postural control and functional mobility to preflight levels of performance has been shown to be approximately two weeks after long-duration spaceflight. The postflight alterations are due in part to central reinterpretation of vestibular information caused by exposure to microgravity. In this study we will use a commonly used technique of transcutaneous electrical stimulation applied across the vestibular end organs (galvanic vestibular stimulation, GVS) to disrupt vestibular function as a simulation of post-flight disturbances. The goal of this project is an engineering human-in-the-loop evaluation of a device that can degrade performance of functional tasks (e.g. to maintain upright balance

  4. Galvanic Vestibular Stimulation in Hemi-Spatial Neglect

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    David eWilkinson

    2014-01-01

    Full Text Available Hemi-spatial neglect is an attentional disorder in which the sufferer fails to acknowledge or respond to stimuli appearing in contralesional space. In recent years, it has become clear that a measurable reduction in contralesional neglect can occur during galvanic vestibular stimulation, a technique by which transmastoid, small amplitude current induces lateral, attentional shifts via asymmetric modulation of the left and right vestibular nerves. However, it remains unclear whether this reduction persists after stimulation is stopped. To estimate longevity of effect, we therefore conducted a double-blind, randomized, dose-response trial involving a group of stroke patients suffering from left-sided neglect (n=52, mean age=66 years. To determine whether repeated sessions of galvanic vestibular stimulation more effectively induce lasting relief than a single session, participants received 1, 5, or 10 sessions, each lasting 25mins, of sub-sensory, left-anodal right-cathodal noisy direct current (mean amplitude=1mA. Ninety five percent confidence intervals indicated that all three treatment arms showed a statistically significant improvement between the pre-stimulation baseline and the final day of stimulation on the primary outcome measure, the conventional tests of the Behavioural Inattention Test. More remarkably, this change (mean change=28%, SD=18 was still evident 1month later. Secondary analyses indicated an allied increase of 20% in median Barthel Index score, a measure of functional capacity, in the absence of any adverse events or instances of participant non-compliance. Together these data suggest that galvanic vestibular stimulation, a simple, cheap technique suitable for home-based administration, may produce lasting reductions in neglect that are clinically important. Further protocol optimization is now needed ahead of a larger effectiveness study.

  5. Intermediate Latency-Evoked Potentials of Multimodal Cortical Vestibular Areas: Galvanic Stimulation

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    Stefan Kammermeier

    2017-11-01

    Full Text Available IntroductionHuman multimodal vestibular cortical regions are bilaterally anterior insulae and posterior opercula, where characteristic vestibular-related cortical potentials were previously reported under acoustic otolith stimulation. Galvanic vestibular stimulation likely influences semicircular canals preferentially. Galvanic stimulation was compared to previously established data under acoustic stimulation.Methods14 healthy right-handed subjects, who were also included in the previous acoustic potential study, showed normal acoustic and galvanic vestibular-evoked myogenic potentials. They received 2,000 galvanic binaural bipolar stimuli for each side during EEG recording.ResultsVestibular cortical potentials were found in all 14 subjects and in the pooled data of all subjects (“grand average” bilaterally. Anterior insula and posterior operculum were activated exclusively under galvanic stimulation at 25, 35, 50, and 80 ms; frontal regions at 30 and 45 ms. Potentials at 70 ms in frontal regions and at 110 ms at all of the involved regions could also be recorded; these events were also found using acoustic stimulation in our previous study.ConclusionGalvanic semicircular canal stimulation evokes specific potentials in addition to those also found with acoustic otolith stimulation in identically located regions of the vestibular cortex. Vestibular cortical regions activate differently by galvanic and acoustic input at the peripheral sensory level.SignificanceDifferential effects in vestibular cortical-evoked potentials may see clinical use in specific vertigo disorders.

  6. Galvanic Vestibular Stimulation (GVS) as an Analogue of Post-flight Sensorimotor Dysfunction

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    National Aeronautics and Space Administration — Aim 1A (complete): Tolerance to GVS. Dilda, V, MacDougall HG, Moore, ST. Tolerance to extended Galvanic vestibular stimulation: optimal exposure for astronaut...

  7. Multifaceted Effects of Noisy Galvanic Vestibular Stimulation on Manual Tracking Behavior in Parkinson’s Disease

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    Soojin eLee

    2015-02-01

    Full Text Available Parkinson’s disease (PD is a neurodegenerative movement disorder that is characterized clinically by slowness of movement, rigidity, tremor, postural instability, and often cognitive impairments. Recent studies have demonstrated altered cortico-basal ganglia rhythms in PD, which raises the possibility of a role for non-invasive stimulation therapies such as noisy galvanic vestibular stimulation (GVS. We applied noisy GVS to 12 mild-moderately affected PD subjects (Hoehn & Yahr 1.5-2.5 off medication while they performed a sinusoidal visuomotor joystick tracking task, which alternated between 2 task conditions depending on whether the displayed cursor position underestimated the actual error by 30% (‘Better’ or overestimated by 200% (‘Worse’. Either sham or subthreshold, noisy GVS (0.1-10 Hz, 1/f-type power spectrum was applied in pseudorandom order. We used exploratory (Linear Discriminant Analysis with bootstrapping and confirmatory (robust multivariate linear regression methods to determine if the presence of GVS significantly affected our ability to predict cursor position based on target variables. Variables related to displayed error were robustly seen to discriminate GVS in all subjects particularly in the Worse condition. If we considered higher frequency components of the cursor trajectory as noise, the signal-to-noise ratio of cursor trajectory was significantly increased during the GVS stimulation. The results suggest that noisy GVS influenced motor performance of the PD subjects, and we speculate that they were elicited through a combination of mechanisms: enhanced cingulate activity resulting in modulation of frontal midline theta rhythms, improved signal processing in neuromotor system via stochastic facilitation and/or enhanced vigor known to be deficient in PD subjects. Further work is required to determine if GVS has a selective effect on corrective submovements that could not be detected by the current analyses.

  8. Multifaceted effects of noisy galvanic vestibular stimulation on manual tracking behavior in Parkinson’s disease

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    Lee, Soojin; Kim, Diana J.; Svenkeson, Daniel; Parras, Gabriel; Oishi, Meeko Mitsuko K.; McKeown, Martin J.

    2015-01-01

    Parkinson’s disease (PD) is a neurodegenerative movement disorder that is characterized clinically by slowness of movement, rigidity, tremor, postural instability, and often cognitive impairments. Recent studies have demonstrated altered cortico-basal ganglia rhythms in PD, which raises the possibility of a role for non-invasive stimulation therapies such as noisy galvanic vestibular stimulation (GVS). We applied noisy GVS to 12 mild-moderately affected PD subjects (Hoehn and Yahr 1.5–2.5) off medication while they performed a sinusoidal visuomotor joystick tracking task, which alternated between 2 task conditions depending on whether the displayed cursor position underestimated the actual error by 30% (‘Better’) or overestimated by 200% (‘Worse’). Either sham or subthreshold, noisy GVS (0.1–10 Hz, 1/f-type power spectrum) was applied in pseudorandom order. We used exploratory (linear discriminant analysis with bootstrapping) and confirmatory (robust multivariate linear regression) methods to determine if the presence of GVS significantly affected our ability to predict cursor position based on target variables. Variables related to displayed error were robustly seen to discriminate GVS in all subjects particularly in the Worse condition. If we considered higher frequency components of the cursor trajectory as “noise,” the signal-to-noise ratio of cursor trajectory was significantly increased during the GVS stimulation. The results suggest that noisy GVS influenced motor performance of the PD subjects, and we speculate that they were elicited through a combination of mechanisms: enhanced cingulate activity resulting in modulation of frontal midline theta rhythms, improved signal processing in neuromotor system via stochastic facilitation and/or enhanced “vigor” known to be deficient in PD subjects. Further work is required to determine if GVS has a selective effect on corrective submovements that could not be detected by the current analyses

  9. Galvanic vestibular stimulation combines with Earth-horizontal rotation in roll to induce the illusion of translation.

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    Schneider, Erich; Bartl, Klaus; Glasauer, Stefan

    2009-05-01

    Human head rotation in roll around an earth-horizontal axis constitutes a vestibular stimulus that, by its rotational component, acts on the semicircular canals (SCC) and that, by its tilt of the gravity vector, also acts on the otoliths. Galvanic vestibular stimulation (GVS) is thought to resemble mainly a rotation in roll. A superposition of sinusoidal GVS with a natural earth-horizontal roll movement was therefore applied in order to cancel the rotation effects and to isolate the otolith activation. By self-adjusting the amplitude and phase of GVS, subjects were able to minimize their sensation of rotation and to generate the perception of a linear translation. The final adjustments are in the range of a model that predicts SCC activation during natural rotations and GVS. This indicates that the tilt-translation ambiguity of the otoliths is resolved by SCC-otolith interaction. It is concluded that GVS might be able to cancel rotations in roll and that the residual tilt of the gravitoinertial force is possibly interpreted as a linear translation.

  10. Central adaptation to repeated galvanic vestibular stimulation: implications for pre-flight astronaut training.

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    Valentina Dilda

    Full Text Available Healthy subjects (N = 10 were exposed to 10-min cumulative pseudorandom bilateral bipolar Galvanic vestibular stimulation (GVS on a weekly basis for 12 weeks (120 min total exposure. During each trial subjects performed computerized dynamic posturography and eye movements were measured using digital video-oculography. Follow up tests were conducted 6 weeks and 6 months after the 12-week adaptation period. Postural performance was significantly impaired during GVS at first exposure, but recovered to baseline over a period of 7-8 weeks (70-80 min GVS exposure. This postural recovery was maintained 6 months after adaptation. In contrast, the roll vestibulo-ocular reflex response to GVS was not attenuated by repeated exposure. This suggests that GVS adaptation did not occur at the vestibular end-organs or involve changes in low-level (brainstem-mediated vestibulo-ocular or vestibulo-spinal reflexes. Faced with unreliable vestibular input, the cerebellum reweighted sensory input to emphasize veridical extra-vestibular information, such as somatosensation, vision and visceral stretch receptors, to regain postural function. After a period of recovery subjects exhibited dual adaption and the ability to rapidly switch between the perturbed (GVS and natural vestibular state for up to 6 months.

  11. Central adaptation to repeated galvanic vestibular stimulation: implications for pre-flight astronaut training.

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    Dilda, Valentina; Morris, Tiffany R; Yungher, Don A; MacDougall, Hamish G; Moore, Steven T

    2014-01-01

    Healthy subjects (N = 10) were exposed to 10-min cumulative pseudorandom bilateral bipolar Galvanic vestibular stimulation (GVS) on a weekly basis for 12 weeks (120 min total exposure). During each trial subjects performed computerized dynamic posturography and eye movements were measured using digital video-oculography. Follow up tests were conducted 6 weeks and 6 months after the 12-week adaptation period. Postural performance was significantly impaired during GVS at first exposure, but recovered to baseline over a period of 7-8 weeks (70-80 min GVS exposure). This postural recovery was maintained 6 months after adaptation. In contrast, the roll vestibulo-ocular reflex response to GVS was not attenuated by repeated exposure. This suggests that GVS adaptation did not occur at the vestibular end-organs or involve changes in low-level (brainstem-mediated) vestibulo-ocular or vestibulo-spinal reflexes. Faced with unreliable vestibular input, the cerebellum reweighted sensory input to emphasize veridical extra-vestibular information, such as somatosensation, vision and visceral stretch receptors, to regain postural function. After a period of recovery subjects exhibited dual adaption and the ability to rapidly switch between the perturbed (GVS) and natural vestibular state for up to 6 months.

  12. Framing susceptibility in a risky choice game is altered by galvanic vestibular stimulation.

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    Preuss, Nora; Kalla, Roger; Müri, Rene; Mast, Fred W

    2017-06-07

    Recent research provides evidence that galvanic vestibular stimulation (GVS) has a modulating effect on somatosensory perception and spatial cognition. However, other vestibular stimulation techniques have induced changes in affective control and decision making. The aim of this study was to investigate the effect of GVS on framing susceptibility in a risky-choice game. The participants were to decide between a safe and a risky option. The safe option was framed either positively or negatively. During the task, the participants were exposed to either left anodal/right cathodal GVS, right anodal/left cathodal GVS, or sham stimulation (control condition). While left anodal/right cathodal GVS activated more right-hemispheric vestibular brain areas, right anodal/left cathodal GVS resulted in more bilateral activation. We observed increased framing susceptibility during left anodal/right cathodal GVS, but no change in framing susceptibility during right anodal/left cathodal GVS. We propose that GVS results in increased reliance on the affect heuristic by means of activation of cortical and subcortical vestibular-emotional brain structures and that this effect is modulated by the lateralization of the vestibular cortex.

  13. Differential effects of galvanic vestibular stimulation on arm position sense in right- vs. left-handers.

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    Schmidt, Lena; Artinger, Frank; Stumpf, Oliver; Kerkhoff, Georg

    2013-04-01

    The human brain is organized asymmetrically in two hemispheres with different functional specializations. Left- and right-handers differ in many functional capacities and their anatomical representations. Right-handers often show a stronger functional lateralization than left-handers, the latter showing a more bilateral, symmetrical brain organization. Recent functional imaging evidence shows a different lateralization of the cortical vestibular system towards the side of the preferred hand in left- vs. right-handers as well. Since the vestibular system is involved in somatosensory processing and the coding of body position, vestibular stimulation should affect such capacities differentially in left- vs. right-handers. In the present, sham-stimulation-controlled study we explored this hypothesis by studying the effects of galvanic vestibular stimulation (GVS) on proprioception in both forearms in left- and right-handers. Horizontal arm position sense (APS) was measured with an opto-electronic device. Second, the polarity-specific online- and after-effects of subsensory, bipolar GVS on APS were investigated in different sessions separately for both forearms. At baseline, both groups did not differ in their unsigned errors for both arms. However, right-handers showed significant directional errors in APS of both arms towards their own body. Right-cathodal/left-anodal GVS, resulting in right vestibular cortex activation, significantly deteriorated left APS in right-handers, but had no detectable effect on APS in left-handers in either arm. These findings are compatible with a right-hemisphere dominance for vestibular functions in right-handers and a differential vestibular organization in left-handers that compensates for the disturbing effects of GVS on APS. Moreover, our results show superior arm proprioception in left-handers in both forearms. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Pre-adaptation to noisy Galvanic vestibular stimulation is associated with enhanced sensorimotor performance in novel vestibular environments

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    Steven T Moore

    2015-06-01

    Full Text Available Performance on a visuomotor task in the presence of novel vestibular stimulation was assessed in nine healthy subjects. Four subjects had previously been adapted to 120 minutes exposure to noisy Galvanic vestibular stimulation (GVS over 12 weekly sessions of 10 minutes; the remaining five subjects had never experienced GVS. Subjects were seated in a flight simulator and asked to null the roll motion of a visual bar presented on a screen using a joystick. Both the visual bar and the simulator cabin were moving in roll with a pseudorandom (sum of sines waveform that were uncorrelated. The cross correlation coefficient, which ranges from 1 (identical waveforms to 0 (unrelated waveforms, was calculated for the ideal (perfect nulling of bar motion and actual joystick input waveform for each subject. The cross correlation coefficient for the GVS-adapted group (0.90 [SD 0.04] was significantly higher (t[8]=3.162; p=0.013 than the control group (0.82 [SD 0.04], suggesting that prior adaptation to GVS was associated with an enhanced ability to perform the visuomotor task in the presence of novel vestibular noise.

  15. Can Postural Instability Respond to Galvanic Vestibular Stimulation in Patients with Parkinson’s Disease?

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    Hiroshi Kataoka

    2016-01-01

    Full Text Available Objective Galvanic vestibular stimulation (GVS activates the vestibular afferents, and these changes in vestibular input exert a strong influence on the subject’s posture or standing balance. In patients with Parkinson’s disease (PD, vestibular dysfunction might contribute to postural instability and gait disorders. Methods Current intensity was increased to 0.7 mA, and the current was applied to the patients for 20 minutes. To perform a sham stimulation, the current intensity was increased as described and then decreased to 0 mA over the course of 10 seconds. The patient’s status was recorded continuously for 20 minutes with the patient in the supine position. Results Three out of 5 patients diagnosed with PD with postural instability and/or abnormal axial posture showed a reduction in postural instability after GVS. The score for item 12 of the revised Unified Parkinson’s Disease Rating Scale part 3 was decreased in these patients. Conclusions The mechanism of postural instability is complex and not completely understood. In 2 out of the 5 patients, postural instability was not changed in response to GVS. Nonetheless, the GVS-induced change in postural instability for 3 patients in our study suggests that GVS might be a therapeutic option for postural instability.

  16. Comparison of Postural Responses to Galvanic Vestibular Stimulation between Pilots and the General Populace

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    Yang Yang

    2015-01-01

    Full Text Available Galvanic vestibular stimulation (GVS can be used to study the body’s response to vestibular stimuli. This study aimed to investigate whether postural responses to GVS were different between pilots and the general populace. Bilateral bipolar GVS was applied with a constant-current profile to 12 pilots and 12 control subjects via two electrodes placed over the mastoid processes. Both GVS threshold and the center of pressure’s trajectory (COP’s trajectory were measured. Position variability of COP during spontaneous body sway and peak displacement of COP during GVS-induced body sway were calculated in the medial-lateral direction. Spontaneous body sway was slight for all subjects, and there was no significant difference in the value of COP position variability between the pilots and controls. Both the GVS threshold and magnitude of GVS-induced body deviation were similar for different GVS polarities. GVS thresholds were similar between the two groups, but the magnitude of GVS-induced body deviation in the controls was significantly larger than that in the pilots. The pilots showed less GVS-induced body deviation, meaning that pilots may have a stronger ability to suppress vestibular illusions.

  17. Effects of deuterium oxide and galvanic vestibular stimulation on visual cortical cell function

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    Reinis, S.; Landolt, J.P.; Weiss, D.S.; Money, K.E.

    1984-01-01

    The spontaneous and evoked unit activities of complex visual cortical cells were recorded from Brodmann's area 18 in immobilized, unanesthetized cats before, during, and after stimulation of the vestibular system. The vestibular system was stimulated by intravenous injection of deuterium oxide (D2O)--a noted nystagmogenic agent--or by direct galvanic stimulation of the labyrinth. Measures of the receptive-field areas, poststimulus time histograms, directional preferences, and the optimal speed of the light bar stimulating the cell were obtained before and after the application of D2O. Directional preferences were determined in a novel manner, using a method derived from a hierarchical clustering technique. Data were collected and analyzed from a) visual cortical cells in cats with intact labyrinths, b) visual cortical cells in cats following bilateral labrinthectomies, and c) nonvisual cortical cells in cats with intact labyrinths. The other cellular characteristics were also altered by the D2O. Galvanic stimulation of the labyrinth resembles, in its effects, the injection of D2O. In labyrinth-intact cats, the time course of area 18 spontaneous activity dramatically increased 30 min or more after D2O was administered. It peaked 2-3 h later and still had not returned to preinjection levels even 7 h after the D2O administration. In bilaterally labyrinthectomized cats, the spontaneous activity of the visual cells did not change following D2O administration. In nonvisual cells from labyrinth-intact cats, the spontaneous activity demonstrated a slight but significant decrease over time after D2O injection. In pilot studies, the cats were injected with D2O. Within 8-10 min afterward, signs of positional nystagmus commenced; and within 30 min, problems in maintaining balance were noted. This continued for 7-8 h before disappearing. In the labyrinthectomized animals, such effects were not observed

  18. Effects of deuterium oxide and galvanic vestibular stimulation on visual cortical cell function

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    Reinis, S.; Landolt, J.P.; Weiss, D.S.; Money, K.E.

    1984-03-01

    The spontaneous and evoked unit activities of complex visual cortical cells were recorded from Brodmann's area 18 in immobilized, unanesthetized cats before, during, and after stimulation of the vestibular system. The vestibular system was stimulated by intravenous injection of deuterium oxide (D2O)--a noted nystagmogenic agent--or by direct galvanic stimulation of the labyrinth. Measures of the receptive-field areas, poststimulus time histograms, directional preferences, and the optimal speed of the light bar stimulating the cell were obtained before and after the application of D2O. Directional preferences were determined in a novel manner, using a method derived from a hierarchical clustering technique. Data were collected and analyzed from a) visual cortical cells in cats with intact labyrinths, b) visual cortical cells in cats following bilateral labrinthectomies, and c) nonvisual cortical cells in cats with intact labyrinths. The other cellular characteristics were also altered by the D2O. Galvanic stimulation of the labyrinth resembles, in its effects, the injection of D2O. In labyrinth-intact cats, the time course of area 18 spontaneous activity dramatically increased 30 min or more after D2O was administered. It peaked 2-3 h later and still had not returned to preinjection levels even 7 h after the D2O administration. In bilaterally labyrinthectomized cats, the spontaneous activity of the visual cells did not change following D2O administration. In nonvisual cells from labyrinth-intact cats, the spontaneous activity demonstrated a slight but significant decrease over time after D2O injection. In pilot studies, the cats were injected with D2O. Within 8-10 min afterward, signs of positional nystagmus commenced; and within 30 min, problems in maintaining balance were noted. This continued for 7-8 h before disappearing. In the labyrinthectomized animals, such effects were not observed.

  19. Galvanic vestibular stimulation may improve anterior bending posture in Parkinson's disease.

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    Okada, Yohei; Kita, Yorihiro; Nakamura, Junji; Kataoka, Hiroshi; Kiriyama, Takao; Ueno, Satoshi; Hiyamizu, Makoto; Morioka, Shu; Shomoto, Koji

    2015-05-06

    This study investigated the effects of binaural monopolar galvanic vestibular stimulation (GVS), which likely stimulates the bilateral vestibular system, on the anterior bending angle in patients with Parkinson's disease (PD) with anterior bending posture in a single-blind, randomized sham-controlled crossover trial. The seven PD patients completed two types of stimulation (binaural monopolar GVS and sham stimulation) applied in a random order 1 week apart. We measured each patient's anterior bending angles while he or she stood with eyes open and eyes closed before/after the stimulations. The anterior bending angles in both the eyes-open and the eyes-closed conditions were significantly reduced after the GVS. The amount of change in the eyes-closed condition post-GVS was significantly larger than that by sham stimulation. The amount of change in anterior bending angles in the GVS condition was not significantly correlated with Unified Parkinson's Disease Rating Scale motor score, disease duration, the duration of the postural deformities, and the anterior bending angles before the GVS. Binaural monopolar GVS might improve anterior bending posture in PD patients, irrespective of the duration and the severity of disease and postural deformities. Binaural monopolar GVS might be a novel treatment strategy to improve anterior bending posture in PD.

  20. Tolerance to extended galvanic vestibular stimulation: optimal exposure for astronaut training.

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    Dilda, Valentina; MacDougall, Hamish G; Moore, Steven T

    2011-08-01

    We have developed an analogue of postflight sensorimotor dysfunction in astronauts using pseudorandom galvanic vestibular stimulation (GVS). To date there has been no study of the effects of extended GVS on human subjects and our aim was to determine optimal exposure for astronaut training based on tolerance to intermittent and continuous galvanic stimulation. There were 60 subjects who were exposed to a total of 10.5 min of intermittent GVS at a peak current of 3.5 mA or 5 mA. A subset of 24 subjects who tolerated the intermittent stimulus were subsequently exposed to 20-min continuous stimulation at 3.5 mA or 5 mA. During intermittent GVS the large majority of subjects (78.3%) reported no or at most mild motion sickness symptoms, 13.3% reported moderate symptoms, and 8.3% experienced severe nausea and requested termination of the stimulus. During 20-min continuous exposure, 83.3% of subjects reported no or at most mild motion sickness symptoms and 16.7% (all in the 5-mA group) experienced severe nausea. Based on these results, we propose two basic modes of GVS application to minimize the incidence of motion sickness: intermittent high (5 mA) amplitude, suited to simulation of intensive operator tasks requiring a high-fidelity analogue of postflight sensorimotor dysfunction such as landing or docking maneuvers; and continuous low (3.5 mA) amplitude stimulation, for longer simulation scenarios such as extra vehicular activity. Our results suggest that neither mode of stimulation would induce motion sickness in the large majority of subjects for up to 20 min exposure.

  1. Wavelet-Based Artifact Identification and Separation Technique for EEG Signals during Galvanic Vestibular Stimulation

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    Adib, Mani; Cretu, Edmond

    2013-01-01

    We present a new method for removing artifacts in electroencephalography (EEG) records during Galvanic Vestibular Stimulation (GVS). The main challenge in exploiting GVS is to understand how the stimulus acts as an input to brain. We used EEG to monitor the brain and elicit the GVS reflexes. However, GVS current distribution throughout the scalp generates an artifact on EEG signals. We need to eliminate this artifact to be able to analyze the EEG signals during GVS. We propose a novel method to estimate the contribution of the GVS current in the EEG signals at each electrode by combining time-series regression methods with wavelet decomposition methods. We use wavelet transform to project the recorded EEG signal into various frequency bands and then estimate the GVS current distribution in each frequency band. The proposed method was optimized using simulated signals, and its performance was compared to well-accepted artifact removal methods such as ICA-based methods and adaptive filters. The results show that the proposed method has better performance in removing GVS artifacts, compared to the others. Using the proposed method, a higher signal to artifact ratio of −1.625 dB was achieved, which outperformed other methods such as ICA-based methods, regression methods, and adaptive filters. PMID:23956786

  2. Wavelet-Based Artifact Identification and Separation Technique for EEG Signals during Galvanic Vestibular Stimulation

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    Mani Adib

    2013-01-01

    Full Text Available We present a new method for removing artifacts in electroencephalography (EEG records during Galvanic Vestibular Stimulation (GVS. The main challenge in exploiting GVS is to understand how the stimulus acts as an input to brain. We used EEG to monitor the brain and elicit the GVS reflexes. However, GVS current distribution throughout the scalp generates an artifact on EEG signals. We need to eliminate this artifact to be able to analyze the EEG signals during GVS. We propose a novel method to estimate the contribution of the GVS current in the EEG signals at each electrode by combining time-series regression methods with wavelet decomposition methods. We use wavelet transform to project the recorded EEG signal into various frequency bands and then estimate the GVS current distribution in each frequency band. The proposed method was optimized using simulated signals, and its performance was compared to well-accepted artifact removal methods such as ICA-based methods and adaptive filters. The results show that the proposed method has better performance in removing GVS artifacts, compared to the others. Using the proposed method, a higher signal to artifact ratio of −1.625 dB was achieved, which outperformed other methods such as ICA-based methods, regression methods, and adaptive filters.

  3. Influence of Electrotactile Tongue Feedback on Controlling Upright Stance during Rotational and/or Translational Sway-referencing with Galvanic Vestibular Stimulation

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    Wood, Scott J.; Tyler, Mitchell E.; Bach-y-Rita, Paul; MacDougall, Hamish G.; Moore, Steven T.; Stallings, Valerie L.; Paloski, William H.; Black, F. Owen

    2007-01-01

    Integration of multi-sensory inputs to detect tilts relative to gravity is critical for sensorimotor control of upright orientation. Displaying body orientation using electrotactile feedback to the tongue has been developed by Bach-y-Rita and colleagues as a sensory aid to maintain upright stance with impaired vestibular feedback. MacDougall et al. (2006) recently demonstrated that unpredictably varying Galvanic vestibular stimulation (GVS) significantly increased anterior-posterior (AP) sway during rotational sway referencing with eyes closed. The purpose of this study was to assess the influence of electrotactile feedback on postural control performance with pseudorandom binaural bipolar GVS. Postural equilibrium was measured with a computerized hydraulic platform in 10 healthy adults (6M, 4F, 24-65 y). Tactile feedback (TF) of pitch and roll body orientation was derived from a two-axis linear accelerometer mounted on a torso belt and displayed on a 144-point electrotactile array held against the anterior dorsal tongue (BrainPort, Wicab, Inc., Middleton, WI). Subjects were trained to use TF by voluntarily swaying to draw figures on their tongue, both with and without GVS. Subjects were required to keep the intraoral display in their mouths on all trials, including those that did not provide TF. Subjects performed 24 randomized trials (20 s duration with eyes closed) including four support surface conditions (fixed, rotational sway-referenced, translating the support surface proportional to AP sway, and combined rotational-translational sway-referencing), each repeated twice with and without GVS, and with combined GVS and TF. Postural performance was assessed using deviations from upright (peak-to-peak and RMS sway) and convergence toward stability limits (time and distance to base of support boundaries). Postural stability was impaired with GVS in all platform conditions, with larger decrements in performance during trials with rotation sway

  4. Noisy galvanic vestibular stimulation promotes GABA release in the substantia nigra and improves locomotion in hemiparkinsonian rats.

    Directory of Open Access Journals (Sweden)

    Ghazaleh Samoudi

    Full Text Available BACKGROUND: The vestibular system is connected to spinal, cerebellar and cerebral motor control structures and can be selectively activated with external electrodes. The resulting sensation of disturbed balance can be avoided by using stochastic stimulation patterns. Adding noise to the nervous system sometimes improves function. Small clinical trials suggest that stochastic vestibular stimulation (SVS may improve symptoms in Parkinson's disease. We have investigated this claim and possible mechanisms using the 6-hydroxydopamine (6-OHDA hemilesion model of Parkinson's disease. METHODOLOGY/PRINCIPAL FINDINGS: Animals were tested in the accelerating rod test and the Montoya staircase test of skilled forelimb use. In 6-OHDA hemilesioned animals, SVS improved rod performance by 56±11 s. At group level L-DOPA treatment had no effect, but positive responders improved time on rod by 60±19 s. Skilled forelimb use was not altered by SVS. To investigate how SVS may influence basal ganglia network activity, intracerebral microdialysis was employed in four regions of interest during and after SVS. In presence of the γ-amino buturic acid (GABA transporter inhibitor NNC 711, SVS induced an increase in GABA to 150±15% of baseline in the substantia nigra (SN of unlesioned animals, but had no effect in the pedunculopontine nucleus (PPN, the striatum or the ventromedial thalamus (VM. Dopamine release remained stable in all areas, as did GABA and amine concentrations in the SN of unstimulated controls. Following SVS, a sustained increase in GABA concentrations was observed in the ipsilesional, but not in the contralesional SN of 6-OHDA hemilesioned rats. In contrast, L-DOPA treatment produced a similar increase of GABA in the ipsi- and contra-lesional SN. CONCLUSIONS/SIGNIFICANCE: SVS improves rod performance in a rat model of Parkinson's disease, possibly by increasing nigral GABA release in a dopamine independent way. We propose that SVS could be useful for

  5. Electrical vestibular stimulation after vestibular deafferentation and in vestibular schwannoma.

    Directory of Open Access Journals (Sweden)

    Swee Tin Aw

    Full Text Available BACKGROUND: Vestibular reflexes, evoked by human electrical (galvanic vestibular stimulation (EVS, are utilized to assess vestibular function and investigate its pathways. Our study aimed to investigate the electrically-evoked vestibulo-ocular reflex (eVOR output after bilateral and unilateral vestibular deafferentations to determine the characteristics for interpreting unilateral lesions such as vestibular schwannomas. METHODS: EVOR was recorded with dual-search coils as binocular three-dimensional eye movements evoked by bipolar 100 ms-step at EVS intensities of [0.9, 2.5, 5.0, 7.5, 10.0] mA and unipolar 100 ms-step at 5 mA EVS intensity. Five bilateral vestibular deafferented (BVD, 12 unilateral vestibular deafferented (UVD, four unilateral vestibular schwannoma (UVS patients and 17 healthy subjects were tested with bipolar EVS, and five UVDs with unipolar EVS. RESULTS: After BVD, bipolar EVS elicited no eVOR. After UVD, bipolar EVS of one functioning ear elicited bidirectional, excitatory eVOR to cathodal EVS with 9 ms latency and inhibitory eVOR to anodal EVS, opposite in direction, at half the amplitude with 12 ms latency, exhibiting an excitatory-inhibitory asymmetry. The eVOR patterns from UVS were consistent with responses from UVD confirming the vestibular loss on the lesion side. Unexpectedly, unipolar EVS of the UVD ear, instead of absent response, evoked one-third the bipolar eVOR while unipolar EVS of the functioning ear evoked half the bipolar response. CONCLUSIONS: The bidirectional eVOR evoked by bipolar EVS from UVD with an excitatory-inhibitory asymmetry and the 3 ms latency difference between normal and lesion side may be useful for detecting vestibular lesions such as UVS. We suggest that current spread could account for the small eVOR to 5 mA unipolar EVS of the UVD ear.

  6. Analysis of Postural Control Adaptation During Galvanic and Vibratory Stimulation

    National Research Council Canada - National Science Library

    Fransson, P

    2001-01-01

    The objective for this study was to investigate whether the postural control adaptation during galvanic stimulation of the vestibular nerve were similar to that found during vibration stimulation to the calf muscles...

  7. Exhibition of Stochastic Resonance in Vestibular Perception

    Science.gov (United States)

    Galvan-Garza, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Oman, C. M.; Mulavara, A. P.

    2016-01-01

    (OTO) with SVS up to 700 µA. A sinusoidal galvanic vestibular stimulation (GVS) perceptual threshold was also measured on each test day and used to normalize the SVS levels across subjects. In roll-tilt thresholds with SVS, the characteristic SR curve was qualitatively exhibited in 10 of 12 subjects, and the improvement in motion threshold was significant in 6 subjects, indicating that optimal SVS improved passive body motion perception in a way that is consistent with classical SR theory. A probabilistic comparison to numeric simulations further validated these experimental results. On the second test session, 4 out of the 10 SR exhibitors showed repeated improvement with SVS compared to the no SVS condition. Data collection is ongoing for the last two test sessions in which SCC and OTO only perceptual motion recognition thresholds are being measured with SVS. The final results of these test sessions will give insight into whether vestibular perceptual SR can occur when only one type of vestibular sensor is sensing motion or if it is more evident when sensory integration between the SCC and OTO is occurring during the motion. The overall purpose of this research is to further quantify the effects of SVS on various sensorimotor tasks and to gain a more fundamental understanding of how SVS causes SR in the vestibular system. In the context of human space flight, results from this research will help in understanding how SVS may be practically implemented in the future as a component of a comprehensive countermeasure plan for G-transition adaptation.

  8. Vestibular migraine

    DEFF Research Database (Denmark)

    Lempert, Thomas; Olesen, Jes; Furman, Joseph

    2012-01-01

    This paper presents diagnostic criteria for vestibular migraine, jointly formulated by the Committee for Classification of Vestibular Disorders of the Bárány Society and the Migraine Classification Subcommittee of the International Headache Society (IHS). The classification includes vestibular...... migraine and probable vestibular migraine. Vestibular migraine will appear in an appendix of the third edition of the International Classification of Headache Disorders (ICHD) as a first step for new entities, in accordance with the usual IHS procedures. Probable vestibular migraine may be included...... in a later version of the ICHD, when further evidence has been accumulated. The diagnosis of vestibular migraine is based on recurrent vestibular symptoms, a history of migraine, a temporal association between vestibular symptoms and migraine symptoms and exclusion of other causes of vestibular symptoms...

  9. Cross-Modal Calibration of Vestibular Afference for Human Balance.

    Directory of Open Access Journals (Sweden)

    Martin E Héroux

    Full Text Available To determine how the vestibular sense controls balance, we used instantaneous head angular velocity to drive a galvanic vestibular stimulus so that afference would signal that head movement was faster or slower than actual. In effect, this changed vestibular afferent gain. This increased sway 4-fold when subjects (N = 8 stood without vision. However, after a 240 s conditioning period with stable balance achieved through reliable visual or somatosensory cues, sway returned to normal. An equivalent galvanic stimulus unrelated to sway (not driven by head motion was equally destabilising but in this situation the conditioning period of stable balance did not reduce sway. Reflex muscle responses evoked by an independent, higher bandwidth vestibular stimulus were initially reduced in amplitude by the galvanic stimulus but returned to normal levels after the conditioning period, contrary to predictions that they would decrease after adaptation to increased sensory gain and increase after adaptation to decreased sensory gain. We conclude that an erroneous vestibular signal of head motion during standing has profound effects on balance control. If it is unrelated to current head motion, the CNS has no immediate mechanism of ignoring the vestibular signal to reduce its influence on destabilising balance. This result is inconsistent with sensory reweighting based on disturbances. The increase in sway with increased sensory gain is also inconsistent with a simple feedback model of vestibular reflex action. Thus, we propose that recalibration of a forward sensory model best explains the reinterpretation of an altered reafferent signal of head motion during stable balance.

  10. Vestibular feedback maintains reaching accuracy during body movement

    Science.gov (United States)

    Reynolds, Raymond F.

    2016-01-01

    Key points Reaching movements can be perturbed by vestibular input, but the function of this response is unclear.Here, we applied galvanic vestibular stimulation concurrently with real body movement while subjects maintained arm position either fixed in space or fixed with respect to their body.During the fixed‐in‐space conditions, galvanic vestibular stimulation caused large changes in arm trajectory consistent with a compensatory response to maintain upper‐limb accuracy in the face of body movement.Galvanic vestibular stimulation responses were absent during the body‐fixed task, demonstrating task dependency in vestibular control of the upper limb.The results suggest that the function of vestibular‐evoked arm movements is to maintain the accuracy of the upper limb during unpredictable body movement, but only when reaching in an earth‐fixed reference frame. Abstract When using our arms to interact with the world, unintended body motion can introduce movement error. A mechanism that could detect and compensate for such motion would be beneficial. Observations of arm movements evoked by vestibular stimulation provide some support for this mechanism. However, the physiological function underlying these artificially evoked movements is unclear from previous research. For such a mechanism to be functional, it should operate only when the arm is being controlled in an earth‐fixed rather than a body‐fixed reference frame. In the latter case, compensation would be unnecessary and even deleterious. To test this hypothesis, subjects were gently rotated in a chair while being asked to maintain their outstretched arm pointing towards either earth‐fixed or body‐fixed memorized targets. Galvanic vestibular stimulation was applied concurrently during rotation to isolate the influence of vestibular input, uncontaminated by inertial factors. During the earth‐fixed task, galvanic vestibular stimulation produced large polarity‐dependent corrections in arm

  11. Sinusoidal obstruction syndrome.

    Science.gov (United States)

    Valla, Dominique-Charles; Cazals-Hatem, Dominique

    2016-09-01

    Sinusoidal obstruction syndrome (SOS) is characterized by damage to small hepatic vessels affecting particularly sinusoidal endothelium. Damaged sinusoids can be associated with a partial or complete occlusion of small hepatic veins, hence the previous denomination of hepatic veno-occlusive disease (VOD). Exposure to certain exogenous toxins appears to be specific to this condition and is frequently included in its definition. Typical histopathological features of SOS in a liver biopsy specimen are presented in the text. The purpose of this article is to provide an overview on the different entities corresponding to this general definition. Such entities include: (i) liver disease related to pyrrolizidine alcaloids; (ii) liver injury related to conditioning for hematopoietic stem cell transplantation; (iii) vascular liver disease occurring in patients treated with chemotherapy for liver metastasis of colorectal cancer; and (iv) other liver diseases related to toxic agents. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. Noise upon the Sinusoids

    DEFF Research Database (Denmark)

    Jensen, Karl Kristoffer

    2005-01-01

    Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having...... control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity’s (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary...

  13. Task-dependent vestibular feedback responses in reaching.

    Science.gov (United States)

    Keyser, Johannes; Medendorp, W Pieter; Selen, Luc P J

    2017-07-01

    When reaching for an earth-fixed object during self-rotation, the motor system should appropriately integrate vestibular signals and sensory predictions to compensate for the intervening motion and its induced inertial forces. While it is well established that this integration occurs rapidly, it is unknown whether vestibular feedback is specifically processed dependent on the behavioral goal. Here, we studied whether vestibular signals evoke fixed responses with the aim to preserve the hand trajectory in space or are processed more flexibly, correcting trajectories only in task-relevant spatial dimensions. We used galvanic vestibular stimulation to perturb reaching movements toward a narrow or a wide target. Results show that the same vestibular stimulation led to smaller trajectory corrections to the wide than the narrow target. We interpret this reduced compensation as a task-dependent modulation of vestibular feedback responses, tuned to minimally intervene with the task-irrelevant dimension of the reach. These task-dependent vestibular feedback corrections are in accordance with a central prediction of optimal feedback control theory and mirror the sophistication seen in feedback responses to mechanical and visual perturbations of the upper limb. NEW & NOTEWORTHY Correcting limb movements for external perturbations is a hallmark of flexible sensorimotor behavior. While visual and mechanical perturbations are corrected in a task-dependent manner, it is unclear whether a vestibular perturbation, naturally arising when the body moves, is selectively processed in reach control. We show, using galvanic vestibular stimulation, that reach corrections to vestibular perturbations are task dependent, consistent with a prediction of optimal feedback control theory. Copyright © 2017 the American Physiological Society.

  14. Body ownership and embodiment: vestibular and multisensory mechanisms.

    Science.gov (United States)

    Lopez, C; Halje, P; Blanke, O

    2008-06-01

    Body ownership and embodiment are two fundamental mechanisms of self-consciousness. The present article reviews neurological data about paroxysmal illusions during which body ownership and embodiment are affected differentially: autoscopic phenomena (out-of-body experience, heautoscopy, autoscopic hallucination, feeling-of-a-presence) and the room tilt illusion. We suggest that autoscopic phenomena and room tilt illusion are related to different types of failures to integrate body-related information (vestibular, proprioceptive and tactile cues) in addition to a mismatch between vestibular and visual references. In these patients, altered body ownership and embodiment has been shown to occur due to pathological activity at the temporoparietal junction and other vestibular-related areas arguing for a key importance of vestibular processing. We also review the possibilities of manipulating body ownership and embodiment in healthy subjects through exposition to weightlessness as well as caloric and galvanic stimulation of the peripheral vestibular apparatus. In healthy subjects, disturbed self-processing might be related to interference of vestibular stimulation with vestibular cortex leading to disintegration of bodily information and altered body ownership and embodiment. We finally propose a differential contribution of the vestibular cortical areas to the different forms of altered body ownership and embodiment.

  15. Sinusoidal Representation of Acoustic Signals

    Science.gov (United States)

    Honda, Masaaki

    Sinusoidal representation of acoustic signals has been an important tool in speech and music processing like signal analysis, synthesis and time scale or pitch modifications. It can be applicable to arbitrary signals, which is an important advantage over other signal representations like physical modeling of acoustic signals. In sinusoidal representation, acoustic signals are composed as sums of sinusoid (sine wave) with different amplitudes, frequencies and phases, which is based on the timedependent short-time Fourier transform (STFT). This article describes the principles of acoustic signal analysis/synthesis based on a sinusoid representation with focus on sine waves with rapidly varying frequency.

  16. Peripheral Vestibular System Disease in Vestibular Schwannomas

    DEFF Research Database (Denmark)

    Møller, Martin Nue; Hansen, Søren; Caye-Thomasen, Per

    2015-01-01

    density of the peripheral vestibular nerve branches, and atrophy of the neuroepithelium of the vestibular end organs. In cases with small tumors, peripheral disease occurred only in the tissue structures innervated by the specific nerve from which the tumor originated. CONCLUSION: Vestibular schwannomas...... are associated with distinctive disease of the peripheral vestibular tissue structures, suggesting anterograde degeneration and that dizziness in these patients may be caused by deficient peripheral vestibular nerve fibers, neurons, and end organs. In smaller tumors, a highly localized disease occurs, which...

  17. Imposed currents in galvanic cells

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Soestbergen, M.; Bazant, M.Z.

    2009-01-01

    We analyze the steady-state behavior of a general mathematical model for reversible galvanic cells, such as redox flow cells, reversible solid oxide fuel cells, and rechargeable batteries. We consider not only operation in the galvanic discharging mode, spontaneously generating a positive current

  18. Sinusoids theory and technological applications

    CERN Document Server

    Kythe, Prem K

    2014-01-01

    A Complete Treatment of Current Research Topics in Fourier Transforms and Sinusoids Sinusoids: Theory and Technological Applications explains how sinusoids and Fourier transforms are used in a variety of application areas, including signal processing, GPS, optics, x-ray crystallography, radioastronomy, poetry and music as sound waves, and the medical sciences. With more than 200 illustrations, the book discusses electromagnetic force and sychrotron radiation comprising all kinds of waves, including gamma rays, x-rays, UV rays, visible light rays, infrared, microwaves, and radio waves. It also covers topics of common interest, such as quasars, pulsars, the Big Bang theory, Olbers' paradox, black holes, Mars mission, and SETI.The book begins by describing sinusoids-which are periodic sine or cosine functions-using well-known examples from wave theory, including traveling and standing waves, continuous musical rhythms, and the human liver. It next discusses the Fourier series and transform in both continuous and...

  19. Galvanic element. Galvanisches Element

    Energy Technology Data Exchange (ETDEWEB)

    Sprengel, D.; Haelbig, H.

    1980-01-03

    The invention concerns a gas-tight sealed accumulator with positive and negative electrode plates and an auxillary electrode electroconductively bound to the latter for suppressing oxygen pressure. The auxillary electrode is an intermediate film electrode. The film catalysing oxygen reduction is hydrophilic in character and the other film is hydrophobic. A double coated foil has proved to be advantageous, the hydrophilic film being formed from polymer-bound activated carbon and the hydrophrobic film from porous polytetrafluoroethylene. A metallic network of silver or nickel is rolled into the outer side of the activated carbon film. This auxillary electrode can be used to advantage in all galvanic elements. Even primary cells fall within the scope of application for auxillary electrodes because many of these contain a highly oxidized electrodic material which tends to give off oxygen.

  20. Neurophysiology of vestibular rehabilitation.

    Science.gov (United States)

    Hain, Timothy C

    2011-01-01

    The vestibular system is a sophisticated human control system. Accurate processing of sensory input about rapid head and postural motion is critical. Not surprisingly, the body uses multiple, partially redundant sensory inputs and motor outputs, combined with a very competent central repair capability. The system as a whole can adapt to substantial peripheral vestibular dysfunction. The Achilles' heel of the vestibular system is a relative inability to repair central vestibular dysfunction.

  1. Neurophysiology of vestibular rehabilitation

    OpenAIRE

    Hain Timothy, C.

    2011-01-01

    The vestibular system is a sophisticated human control system. Accurate processing of sensory input about rapid head and postural motion is critical. Not surprisingly, the body uses multiple, partially redundant sensory inputs and motor outputs, combined with a very competent central repair capability. The system as a whole can adapt to substantial peripheral vestibular dysfunction. The Achilles' heel of the vestibular system is a relative inability to repair central vestibular dysfunction.

  2. Perception of the dynamic visual vertical during sinusoidal linear motion.

    Science.gov (United States)

    Pomante, A; Selen, L P J; Medendorp, W P

    2017-10-01

    The vestibular system provides information for spatial orientation. However, this information is ambiguous: because the otoliths sense the gravitoinertial force, they cannot distinguish gravitational and inertial components. As a consequence, prolonged linear acceleration of the head can be interpreted as tilt, referred to as the somatogravic effect. Previous modeling work suggests that the brain disambiguates the otolith signal according to the rules of Bayesian inference, combining noisy canal cues with the a priori assumption that prolonged linear accelerations are unlikely. Within this modeling framework the noise of the vestibular signals affects the dynamic characteristics of the tilt percept during linear whole-body motion. To test this prediction, we devised a novel paradigm to psychometrically characterize the dynamic visual vertical-as a proxy for the tilt percept-during passive sinusoidal linear motion along the interaural axis (0.33 Hz motion frequency, 1.75 m/s 2 peak acceleration, 80 cm displacement). While subjects ( n =10) kept fixation on a central body-fixed light, a line was briefly flashed (5 ms) at different phases of the motion, the orientation of which had to be judged relative to gravity. Consistent with the model's prediction, subjects showed a phase-dependent modulation of the dynamic visual vertical, with a subject-specific phase shift with respect to the imposed acceleration signal. The magnitude of this modulation was smaller than predicted, suggesting a contribution of nonvestibular signals to the dynamic visual vertical. Despite their dampening effect, our findings may point to a link between the noise components in the vestibular system and the characteristics of dynamic visual vertical. NEW & NOTEWORTHY A fundamental question in neuroscience is how the brain processes vestibular signals to infer the orientation of the body and objects in space. We show that, under sinusoidal linear motion, systematic error patterns appear in the

  3. [Vestibular compensation studies]. [Vestibular Compensation and Morphological Studies

    Science.gov (United States)

    Perachio, Adrian A. (Principal Investigator)

    1996-01-01

    The following topics are reported: neurophysiological studies on MVN neurons during vestibular compensation; effects of spinal cord lesions on VNC neurons during compensation; a closed-loop vestibular compensation model for horizontally canal-related MVN neurons; spatiotemporal convergence in VNC neurons; contributions of irregularly firing vestibular afferents to linear and angular VOR's; application to flight studies; metabolic measures in vestibular neurons; immediate early gene expression following vestibular stimulation; morphological studies on primary afferents, central vestibular pathways, vestibular efferent projection to the vestibular end organs, and three-dimensional morphometry and imaging.

  4. Galvanic corrosion in odontological alloys

    International Nuclear Information System (INIS)

    Riesgo, O.; Bianchi, G.L.; Duffo, G.S.

    1993-01-01

    Galvanic corrosion can occur when different alloys are placed in direct contact within the oral cavity or within tissues. Concern has been expressed associated with the coupling of selected restorative materials as well as implant material with various alloys used for restorative procedures. This could be critical if the crown or bridge had subgingival finish line with a metallic zone in contact with the tissue, and the implant was made in titanium alloy. The present work shows the results of galvanic coupling studies done on implants of titanium alloy connected to nickel-chromium and cobalt-chromium alloys. (Author)

  5. Vestibular perception following acute unilateral vestibular lesions.

    Directory of Open Access Journals (Sweden)

    Sian Cousins

    Full Text Available Little is known about the vestibulo-perceptual (VP system, particularly after a unilateral vestibular lesion. We investigated vestibulo-ocular (VO and VP function in 25 patients with vestibular neuritis (VN acutely (2 days after onset and after compensation (recovery phase, 10 weeks. Since the effect of VN on reflex and perceptual function may differ at threshold and supra-threshold acceleration levels, we used two stimulus intensities, acceleration steps of 0.5°/s(2 and velocity steps of 90°/s (acceleration 180°/s(2. We hypothesised that the vestibular lesion or the compensatory processes could dissociate VO and VP function, particularly if the acute vertiginous sensation interferes with the perceptual tasks. Both in acute and recovery phases, VO and VP thresholds increased, particularly during ipsilesional rotations. In signal detection theory this indicates that signals from the healthy and affected side are still fused, but result in asymmetric thresholds due to a lesion-induced bias. The normal pattern whereby VP thresholds are higher than VO thresholds was preserved, indicating that any 'perceptual noise' added by the vertigo does not disrupt the cognitive decision-making processes inherent to the perceptual task. Overall, the parallel findings in VO and VP thresholds imply little or no additional cortical processing and suggest that vestibular thresholds essentially reflect the sensitivity of the fused peripheral receptors. In contrast, a significant VO-VP dissociation for supra-threshold stimuli was found. Acutely, time constants and duration of the VO and VP responses were reduced - asymmetrically for VO, as expected, but surprisingly symmetrical for perception. At recovery, VP responses normalised but VO responses remained shortened and asymmetric. Thus, unlike threshold data, supra-threshold responses show considerable VO-VP dissociation indicative of additional, higher-order processing of vestibular signals. We provide evidence of

  6. Beyond the Vestibulo-Ocular Reflex: Vestibular Input is Processed Centrally to Achieve Visual Stability

    Directory of Open Access Journals (Sweden)

    Edwin S. Dalmaijer

    2018-03-01

    Full Text Available The current study presents a re-analysis of data from Zink et al. (1998, Electroencephalography and Clinical Neurophysiology, 107, who administered galvanic vestibular stimulation through unipolar direct current. They placed electrodes on each mastoid and applied either right or left anodal stimulation. Ocular torsion and visual tilt were measured under different stimulation intensities. New modelling introduced here demonstrates that directly proportional linear models fit reasonably well with the relationship between vestibular input and visual tilt, but not to that between vestibular input and ocular torsion. Instead, an exponential model characterised by a decreasing slope and an asymptote fitted best. These results demonstrate that in the results presented by Zink et al. (1998, ocular torsion could not completely account for visual tilt. This suggests that vestibular input is processed centrally to stabilise vision when ocular torsion is insufficient. Potential mechanisms and seemingly conflicting literature are discussed.

  7. Cosmology and the Sinusoidal Potential

    Science.gov (United States)

    Bartlett, David F.

    2006-06-01

    The nature of dark matter (and dark energy) remains a mystery. An alternative is being explored by several scientists: changing Newton's (and Einstein's) field equations. The sinusoidal potential is the latest attempt[1]. Here the gravitational law is alternately attractive and repulsive:φ = -GM cos(kor)/r, where λo=2π/ko = 1/20 of the distance from the sun to the center of the Milky Way. The proposal accommodates several structural features of the Milky Way including, paradoxically, its spiral shape and flat rotation curve. The sinusoidal potential's unique feature is strong galactic tidal forces (dg/dr). These may explain why the new planetoid Sedna is securely between the Kuiper Belt and the Oort cloud and why distant comets are more influenced by galactic tides that are in the r, rather than the z-direction.At this meeting I discuss the consequences of the sinusoidal potential for cosmology. Here the alternation of attraction and repulsion gives (i) an open universe, and (ii) gravitational lensing which is usually weak, but occasionally very strong. An open universe is one that, asymptotically, has a size R which varies directly as time t. The open universe conflicts both with the old Einstein-deSitter model (R α t2/3} and the new accelerating one. The evidence for an accelerating universe decisively rejects the Einstein-deSitter model. The rejection of an open (or empty) universe is less secure. This rejection is influenced by the different ways the groups studying the brightness of supernovae use the HST. Surprising additional inputs include neutrino masses, the equivalence principle, LSB galaxies, and "over-luminous" Sn1a. I thank Mostafa Jon Dadras and Patrick Motl for early help and John Cumalat for continual support. [1] D.F. Bartlett, "Analogies between electricity and gravity", Metrologia 41, S115-S124 (2004).

  8. Asymmetric vestibular stimulation reveals persistent disruption of motion perception in unilateral vestibular lesions.

    Science.gov (United States)

    Panichi, R; Faralli, M; Bruni, R; Kiriakarely, A; Occhigrossi, C; Ferraresi, A; Bronstein, A M; Pettorossi, V E

    2017-11-01

    Self-motion perception was studied in patients with unilateral vestibular lesions (UVL) due to acute vestibular neuritis at 1 wk and 4, 8, and 12 mo after the acute episode. We assessed vestibularly mediated self-motion perception by measuring the error in reproducing the position of a remembered visual target at the end of four cycles of asymmetric whole-body rotation. The oscillatory stimulus consists of a slow (0.09 Hz) and a fast (0.38 Hz) half cycle. A large error was present in UVL patients when the slow half cycle was delivered toward the lesion side, but minimal toward the healthy side. This asymmetry diminished over time, but it remained abnormally large at 12 mo. In contrast, vestibulo-ocular reflex responses showed a large direction-dependent error only initially, then they normalized. Normalization also occurred for conventional reflex vestibular measures (caloric tests, subjective visual vertical, and head shaking nystagmus) and for perceptual function during symmetric rotation. Vestibular-related handicap, measured with the Dizziness Handicap Inventory (DHI) at 12 mo correlated with self-motion perception asymmetry but not with abnormalities in vestibulo-ocular function. We conclude that 1 ) a persistent self-motion perceptual bias is revealed by asymmetric rotation in UVLs despite vestibulo-ocular function becoming symmetric over time, 2 ) this dissociation is caused by differential perceptual-reflex adaptation to high- and low-frequency rotations when these are combined as with our asymmetric stimulus, 3 ) the findings imply differential central compensation for vestibuloperceptual and vestibulo-ocular reflex functions, and 4 ) self-motion perception disruption may mediate long-term vestibular-related handicap in UVL patients. NEW & NOTEWORTHY A novel vestibular stimulus, combining asymmetric slow and fast sinusoidal half cycles, revealed persistent vestibuloperceptual dysfunction in unilateral vestibular lesion (UVL) patients. The compensation of

  9. Vestibular apparatus disorders after external radiation therapy for head and neck cancers

    International Nuclear Information System (INIS)

    Gabriele, P.; Orecchia, R.; Sannazzari, G.L.; Magnano, M.; Albera, R.

    1992-01-01

    External irradiation of different head and neck cancers may involve parts of the ear. The vestibular function of 25 patients in which the inner ear was comprised in the irradiated volume was investigated by electronystagmography (ENG). Doses administered (3/5 with vertigo) showed vestibular abnormalities to ENG (44% of the total). Altered responses to specific test were as follows : 6 patients to the bithermal caloric stimulation, to pendular-sinusoidal 2, and the other 3 to both of them. Patients were evaluated 3 and 6 months after ending of the radiation therapy course. At the 1st evaluation, abnormalities to caloric test were noted in 3 patients (12%) and to sinusoidal rotary test in 1 patient (4%). At the second rates of abnormal response increased to 36 and 20% respectively. Vestibular disorders seemed to be scantely related to total radiation dose. Data of literature are discussed in order to identify possible implications on treatment planning. (author). 33 refs., 3 tabs

  10. The reliability of nonlinear least-squares algorithm for data analysis of neural response activity during sinusoidal rotational stimulation in semicircular canal neurons.

    Science.gov (United States)

    Ren, Pengyu; Li, Bowen; Dong, Shiyao; Chen, Lin; Zhang, Yuelin

    2018-01-01

    Although many mathematical methods were used to analyze the neural activity under sinusoidal stimulation within linear response range in vestibular system, the reliabilities of these methods are still not reported, especially in nonlinear response range. Here we chose nonlinear least-squares algorithm (NLSA) with sinusoidal model to analyze the neural response of semicircular canal neurons (SCNs) during sinusoidal rotational stimulation (SRS) over a nonlinear response range. Our aim was to acquire a reliable mathematical method for data analysis under SRS in vestibular system. Our data indicated that the reliability of this method in an entire SCNs population was quite satisfactory. However, the reliability was strongly negatively depended on the neural discharge regularity. In addition, stimulation parameters were the vital impact factors influencing the reliability. The frequency had a significant negative effect but the amplitude had a conspicuous positive effect on the reliability. Thus, NLSA with sinusoidal model resulted a reliable mathematical tool for data analysis of neural response activity under SRS in vestibular system and more suitable for those under the stimulation with low frequency but high amplitude, suggesting that this method can be used in nonlinear response range. This method broke out of the restriction of neural activity analysis under nonlinear response range and provided a solid foundation for future study in nonlinear response range in vestibular system.

  11. Quantification of vestibular-induced eye movements in zebrafish larvae

    Directory of Open Access Journals (Sweden)

    Mo Weike

    2010-09-01

    Full Text Available Abstract Background Vestibular reflexes coordinate movements or sensory input with changes in body or head position. Vestibular-evoked responses that involve the extraocular muscles include the vestibulo-ocular reflex (VOR, a compensatory eye movement to stabilize retinal images. Although an angular VOR attributable to semicircular canal stimulation was reported to be absent in free-swimming zebrafish larvae, recent studies reveal that vestibular-induced eye movements can be evoked in zebrafish larvae by both static tilts and dynamic rotations that tilt the head with respect to gravity. Results We have determined herein the basis of sensitivity of the larval eye movements with respect to vestibular stimulus, developmental stage, and sensory receptors of the inner ear. For our experiments, video recordings of larvae rotated sinusoidally at 0.25 Hz were analyzed to quantitate eye movements under infrared illumination. We observed a robust response that appeared as early as 72 hours post fertilization (hpf, which increased in amplitude over time. Unlike rotation about an earth horizontal axis, rotation about an earth vertical axis at 0.25 Hz did not evoke eye movements. Moreover, vestibular-induced responses were absent in mutant cdh23 larvae and larvae lacking anterior otoliths. Conclusions Our results provide evidence for a functional vestibulo-oculomotor circuit in 72 hpf zebrafish larvae that relies upon sensory input from anterior/utricular otolith organs.

  12. Issues in recycling galvanized scrap

    Energy Technology Data Exchange (ETDEWEB)

    Koros, P.J. [LTV Steel Co., Inc., Cleveland, OH (United States); Hellickson, D.A. [General Motors Corp., Detroit, MI (United States); Dudek, F.J. [Argonne National Lab., IL (United States)

    1995-02-10

    The quality of the steel used for most galvanizing (and tinplate) applications makes scrap derived from their production and use a premier solid charge material for steelmaking. In 1989 the AISI created a Task Force to define the issues and to recommend technologically and economically sound approaches to assure continued, unhindered recyclability of the growing volume of galvanized scrap. The AISI program addressed the treatment of full-sized industrial bales of scrap. The current, on-going MRI (US)--Argonne National Laboratory program is focused on ``loose`` scrap from industrial and post-consumer sources. Results from these programs, issues of scrap management from source to steel melting, the choices for handling zinc in iron and steelmaking and the benefits/costs for removal of zinc (and lead) from scrap prior to melting in BOF and foundry operations are reviewed in this paper.

  13. Single ICCII Sinusoidal Oscillators Employing Grounded Capacitors

    Directory of Open Access Journals (Sweden)

    J. W. Horng

    2011-09-01

    Full Text Available Two inverting second-generation current conveyors (ICCII based sinusoidal oscillators are presented. The first sinusoidal oscillator is composed of one ICCII, two grounded capacitors and two resistors. The oscillation condition and oscillation frequency can be orthogonally controllable. The second sinusoidal oscillator is composed of one ICCII, two grounded capacitors and three resistors. The oscillation condition and oscillation frequency can be independently controllable through different resistors.

  14. Left hemispheric dominance of vestibular processing indicates lateralization of cortical functions in rats.

    Science.gov (United States)

    Best, Christoph; Lange, Elena; Buchholz, Hans-Georg; Schreckenberger, Mathias; Reuss, Stefan; Dieterich, Marianne

    2014-11-01

    Lateralization of cortical functions such as speech dominance, handedness and processing of vestibular information are present not only in humans but also in ontogenetic older species, e.g. rats. In human functional imaging studies, the processing of vestibular information was found to be correlated with the hemispherical dominance as determined by the handedness. It is located mainly within the right hemisphere in right handers and within the left hemisphere in left handers. Since dominance of vestibular processing is unknown in animals, our aim was to study the lateralization of cortical processing in a functional imaging study applying small-animal positron emission tomography (microPET) and galvanic vestibular stimulation in an in vivo rat model. The cortical and subcortical network processing vestibular information could be demonstrated and correlated with data from other animal studies. By calculating a lateralization index as well as flipped region of interest analyses, we found that the vestibular processing in rats follows a strong left hemispheric dominance independent from the "handedness" of the animals. These findings support the idea of an early hemispheric specialization of vestibular cortical functions in ontogenetic older species.

  15. Spatio-temporal pattern of vestibular information processing after brief caloric stimulation

    International Nuclear Information System (INIS)

    Marcelli, Vincenzo; Esposito, Fabrizio; Aragri, Adriana; Furia, Teresa; Riccardi, Pasquale; Tosetti, Michela; Biagi, Laura; Marciano, Elio; Di Salle, Francesco

    2009-01-01

    Processing of vestibular information at the cortical and subcortical level is essential for head and body orientation in space and self-motion perception, but little is known about the neural dynamics of the brain regions of the vestibular system involved in this task. Neuroimaging studies using both galvanic and caloric stimulation have shown that several distinct cortical and subcortical structures can be activated during vestibular information processing. The insular cortex has been often targeted and presented as the central hub of the vestibular cortical system. Since very short pulses of cold water ear irrigation can generate a strong and prolonged vestibular response and a nystagmus, we explored the effects of this type of caloric stimulation for assessing the blood-oxygen-level-dependent (BOLD) dynamics of neural vestibular processing in a whole-brain event-related functional magnetic resonance imaging (fMRI) experiment. We evaluated the spatial layout and the temporal dynamics of the activated cortical and subcortical regions in time-locking with the instant of injection and were able to extract a robust pattern of neural activity involving the contra-lateral insular cortex, the thalamus, the brainstem and the cerebellum. No significant correlation with the temporal envelope of the nystagmus was found. The temporal analysis of the activation profiles highlighted a significantly longer duration of the evoked BOLD activity in the brainstem compared to the insular cortex suggesting a functional de-coupling between cortical and subcortical activity during the vestibular response.

  16. Electronically tunable RC sinusoidal oscillators

    International Nuclear Information System (INIS)

    Florescu, Valeriu

    2008-01-01

    This paper presents two types of active configurations for realizing electronically tunable RC sinusoidal oscillators. The type-1 network employs two grounded scaled resistances KR 1 and KR 2 , where K is scaling factor. The frequency of oscillation W 0 is controlled conveniently by adjusting K, since W 0 appears in the form W 0 =1/K √ R 1 C 1 R 2 C 2 . For realizing the scaled resistances, an active configuration is proposed, which realizes KR 1 =R 1 /(1+f(V B )), where f(V B ) denotes a function of a controlling voltage V B . Thus the frequency tuning can be effected by controlling a voltage V B . The type-2 oscillator uses two periodically switched conductances. It is shown that the tuning of oscillation frequency can be done by varying the pulse width-to-period ratio (t/T) of the periodically switched conductances. (author)

  17. Angiogenesis in vestibular schwannomas

    DEFF Research Database (Denmark)

    Møller, Martin Nue; Werther, Kim; Nalla, Amarnadh

    2010-01-01

    Vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) are potent mediators of tumor angiogenesis. It has been demonstrated that vestibular schwannoma VEGF expression correlates with tumor growth pattern, whereas knowledge on the expression of MMPs is lacking. This study...

  18. Vestibular function testing.

    LENUS (Irish Health Repository)

    Lang, E E

    2010-06-01

    Vestibular symptoms of vertigo, dizziness and dysequilibrium are common complaints which can be disabling both physically and psychologically. Routine examination of the ear nose and throat and neurological system are often normal in these patients. An accurate history and thorough clinical examination can provide a diagnosis in the majority of patients. However, in a subgroup of patients, vestibular function testing may be invaluable in arriving at a correct diagnosis and ultimately in the optimal treatment of these patients.

  19. Common Vestibular Disorders

    Directory of Open Access Journals (Sweden)

    Dimitrios G. Balatsouras

    2017-01-01

    Full Text Available The three most common vestibular diseases, benign paroxysmal positional vertigo (BPPV, Meniere's disease (MD and vestibular neuritis (VN, are presented in this paper. BPPV, which is the most common peripheral vestibular disorder, can be defined as transient vertigo induced by a rapid head position change, associated with a characteristic paroxysmal positional nystagmus. Canalolithiasis of the posterior semicircular canal is considered the most convincing theory of its pathogenesis and the development of appropriate therapeutic maneuvers resulted in its effective treatment. However, involvement of the horizontal or the anterior canal has been found in a significant rate and the recognition and treatment of these variants completed the clinical picture of the disease. MD is a chronic condition characterized by episodic attacks of vertigo, fluctuating hearing loss, tinnitus, aural pressure and a progressive loss of audiovestibular functions. Presence of endolymphatic hydrops on postmortem examination is its pathologic correlate. MD continues to be a diagnostic and therapeutic challenge. Patients with the disease range from minimally symptomatic, highly functional individuals to severely affected, disabled patients. Current management strategies are designed to control the acute and recurrent vestibulopathy but offer minimal remedy for the progressive cochlear dysfunction. VN is the most common cause of acute spontaneous vertigo, attributed to acute unilateral loss of vestibular function. Key signs and symptoms are an acute onset of spinning vertigo, postural imbalance and nausea as well as a horizontal rotatory nystagmus beating towards the non-affected side, a pathological headimpulse test and no evidence for central vestibular or ocular motor dysfunction. Vestibular neuritis preferentially involves the superior vestibular labyrinth and its afferents. Symptomatic medication is indicated only during the acute phase to relieve the vertigo and nausea

  20. Imposed currents in galvanic cells

    International Nuclear Information System (INIS)

    Biesheuvel, P.M.; Soestbergen, M. van; Bazant, M.Z.

    2009-01-01

    We analyze the steady-state behavior of a general mathematical model for reversible galvanic cells, such as redox flow cells, reversible solid oxide fuel cells, and rechargeable batteries. We consider not only operation in the galvanic discharging mode, spontaneously generating a positive current against an external load, but also operation in two modes which require a net input of electrical energy: (i) the electrolytic charging mode, where a negative current is imposed to generate a voltage exceeding the open-circuit voltage, and (ii) the 'super-galvanic' discharging mode, where a positive current exceeding the short-circuit current is imposed to generate a negative voltage. Analysis of the various (dis-)charging modes of galvanic cells is important to predict the efficiency of electrical to chemical energy conversion and to provide sensitive tests for experimental validation of fuel cell models. In the model, we consider effects of diffuse charge on electrochemical charge-transfer rates by combining a generalized Frumkin-Butler-Volmer equation for reaction kinetics across the compact Stern layer with the full Poisson-Nernst-Planck transport theory, without assuming local electroneutrality. Since this approach is rare in the literature, we provide a brief historical review. To illustrate the general theory, we present results for a monovalent binary electrolyte, consisting of cations, which react at the electrodes, and non-reactive anions, which are either fixed in space (as in a solid electrolyte) or are mobile (as in a liquid electrolyte). The full model is solved numerically and compared to analytical results in the limit of thin diffuse layers, relative to the membrane thickness. The spatial profiles of the ion concentrations and electrostatic potential reveal a complex dependence on the kinetic parameters and the imposed current, in which the diffuse charge at each electrode and the total membrane charge can have either sign, contrary perhaps to intuition

  1. Deregulated genes in sporadic vestibular schwannomas

    DEFF Research Database (Denmark)

    Cayé-Thomasen, Per; Helweg-Larsen, Rehannah Holga Andrea; Stangerup, Sven-Eric

    2010-01-01

    In search of genes associated with vestibular schwannoma tumorigenesis, this study examines the gene expression in human vestibular nerve versus vestibular schwannoma tissue samples using microarray technology.......In search of genes associated with vestibular schwannoma tumorigenesis, this study examines the gene expression in human vestibular nerve versus vestibular schwannoma tissue samples using microarray technology....

  2. Mathematical Models of the Sinusoidal Screen Family

    Directory of Open Access Journals (Sweden)

    Tajana Koren

    2011-06-01

    Full Text Available In this paper we will define a family of sinusoidal screening elements and explore the possibilities of their application in graphic arts, securities printing and design solutions in photography and typography editing. For this purpose mathematical expressions of sinusoidal families were converted into a Postscript language. The introduction of a random variable results in a countless number of various mutations which cannot be repeated without knowing the programming code itself. The use of the family of screens in protection of securities is thus of great importance. Other possible application of modulated sinusoidal screens is related to the large format color printing. This paper will test the application of sinusoidal screens in vector graphics, pixel graphics and typography. The development of parameters in the sinusoidal screen element algorithms gives new forms defined within screening cells with strict requirements of coverage implementation. Individual solutions include stochastic algorithms, as well as the autonomy of screening forms in regard to multicolor printing channels.

  3. Hereditary familial vestibular degenerative diseases.

    NARCIS (Netherlands)

    Sun, J.; Alphen, A.M. van; Wagenaar, M.; Huygen, P.L.M.; Hoogenraad, C.C.; Hasson, T.; Koekkoek, S.K.; Bohne, B.A.; Zeeuw, C.I. de

    2001-01-01

    Identification of genes involved in hereditary vestibular disease is growing at a remarkable pace. Mutant mouse technology can be an important tool for understanding the biological mechanism of human vestibular diseases.

  4. Galalctic Tides & the Sinusoidal Potential

    Science.gov (United States)

    Bartlett, David F.

    2011-05-01

    The sinusoidal potential is a nonNewtonian alternative to dark matter. Instead of φ = -GM/r we write φ = -(GM/r) cos kor, where ko= 2π/ λo and λo = Ro/20= 400 pc. Evidence for this choice for the "wavelength” λo has been given in one article and many previous meetings of the AAS & DDA. The solar system and nearby stars are trapped in a local groove of width Δr Quality (4 types) and semi-major axis aoriginal . For 10 of the 12 classes radial tides dominate Z-tides. The classic Oort cloud comets (1851-1996) have a particularly strong modulation with galactic longitude. This modulation is exactly in those directions where a radial tide would be important. The equally numerous recent Oort comets (1996-2008) show a different evidence for strong radial tides. The recent comets generally have much larger perihelion distances q than the classic ones. Here the evidence is that a radial tide is removing angular momentum from the orbit and thus bringing the perihelion closer to the earth and to observers.

  5. Distinct roles of Eps8 in the maturation of cochlear and vestibular hair cells.

    Science.gov (United States)

    Tavazzani, Elisa; Spaiardi, Paolo; Zampini, Valeria; Contini, Donatella; Manca, Marco; Russo, Giancarlo; Prigioni, Ivo; Marcotti, Walter; Masetto, Sergio

    2016-07-22

    Several genetic mutations affecting the development and function of mammalian hair cells have been shown to cause deafness but not vestibular defects, most likely because vestibular deficits are sometimes centrally compensated. The study of hair cell physiology is thus a powerful direct approach to ascertain the functional status of the vestibular end organs. Deletion of Epidermal growth factor receptor pathway substrate 8 (Eps8), a gene involved in actin remodeling, has been shown to cause deafness in mice. While both inner and outer hair cells from Eps8 knockout (KO) mice showed abnormally short stereocilia, inner hair cells (IHCs) also failed to acquire mature-type ion channels. Despite the fact that Eps8 is also expressed in vestibular hair cells, Eps8 KO mice show no vestibular deficits. In the present study we have investigated the properties of vestibular Type I and Type II hair cells in Eps8-KO mice and compared them to those of cochlear IHCs. In the absence of Eps8, vestibular hair cells show normally long kinocilia, significantly shorter stereocilia and a normal pattern of basolateral voltage-dependent ion channels. We have also found that while vestibular hair cells from Eps8 KO mice show normal voltage responses to injected sinusoidal currents, which were used to mimic the mechanoelectrical transducer current, IHCs lose their ability to synchronize their responses to the stimulus. We conclude that the absence of Eps8 produces a weaker phenotype in vestibular hair cells compared to cochlear IHCs, since it affects the hair bundle morphology but not the basolateral membrane currents. This difference is likely to explain the absence of obvious vestibular dysfunction in Eps8 KO mice. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  6. Integration of Visual and Vestibular Information Used to Discriminate Rotational Self-Motion

    Directory of Open Access Journals (Sweden)

    Florian Soyka

    2011-10-01

    Full Text Available Do humans integrate visual and vestibular information in a statistically optimal fashion when discriminating rotational self-motion stimuli? Recent studies are inconclusive as to whether such integration occurs when discriminating heading direction. In the present study eight participants were consecutively rotated twice (2s sinusoidal acceleration on a chair about an earth-vertical axis in vestibular-only, visual-only and visual-vestibular trials. The visual stimulus was a video of a moving stripe pattern, synchronized with the inertial motion. Peak acceleration of the reference stimulus was varied and participants reported which rotation was perceived as faster. Just-noticeable differences (JND were estimated by fitting psychometric functions. The visual-vestibular JND measurements are too high compared to the predictions based on the unimodal JND estimates and there is no JND reduction between visual-vestibular and visual-alone estimates. These findings may be explained by visual capture. Alternatively, the visual precision may not be equal between visual-vestibular and visual-alone conditions, since it has been shown that visual motion sensitivity is reduced during inertial self-motion. Therefore, measuring visual-alone JNDs with an underlying uncorrelated inertial motion might yield higher visual-alone JNDs compared to the stationary measurement. Theoretical calculations show that higher visual-alone JNDs would result in predictions consistent with the JND measurements for the visual-vestibular condition.

  7. Galvanic corrosion of beryllium welds

    International Nuclear Information System (INIS)

    Hill, M.A.; Butt, D.P.; Lillard, R.S.

    1997-01-01

    Beryllium is difficult to weld because it is highly susceptible to cracking. The most commonly used filler metal in beryllium welds is Al-12 wt.% Si. Beryllium has been successfully welded using Al-Si filler metal with more than 30 wt.% Al. This filler creates an aluminum-rich fusion zone with a low melting point that tends to backfill cracks. Drawbacks to adding a filler metal include a reduction in service temperature, a lowering of the tensile strength of the weld, and the possibility for galvanic corrosion to occur at the weld. To evaluate the degree of interaction between Be and Al-Si in an actual weld, sections from a mock beryllium weldment were exposed to 0.1 M Cl - solution. Results indicate that the galvanic couple between Be and the Al-Si weld material results in the cathodic protection of the weld and of the anodic dissolution of the bulk Be material. While the cathodic protection of Al is generally inefficient, the high anodic dissolution rate of the bulk Be during pitting corrosion combined with the insulating properties of the Be oxide afford some protection of the Al-Si weld material. Although dissolution of the Be precipitate in the weld material does occur, no corrosion of the Al-Si matrix was observed

  8. Electrocatalysts Prepared by Galvanic Replacement

    Directory of Open Access Journals (Sweden)

    Athanasios Papaderakis

    2017-03-01

    Full Text Available Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, Mnoble, when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mMnoblen+ → nMm+ + mMnoble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a Mnoble-rich shell and M-rich core (denoted as Mnoble(M leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition as well as the various options for the support are also reviewed.

  9. Sinusoidal masks for single channel speech separation

    DEFF Research Database (Denmark)

    Mowlaee, Pejman; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2010-01-01

    In this paper we present a new approach for binary and soft masks used in single-channel speech separation. We present a novel approach called the sinusoidal mask (binary mask and Wiener filter) in a sinusoidal space. Theoretical analysis is presented for the proposed method, and we show...... that the proposed method is able to minimize the target speech distortion while suppressing the crosstalk to a predetermined threshold. It is observed that compared to the STFTbased masks, the proposed sinusoidal masks improve the separation performance in terms of objective measures (SSNR and PESQ) and are mostly...

  10. Dyscalculia and vestibular function.

    Science.gov (United States)

    Smith, P F

    2012-10-01

    A few studies in humans suggest that changes in stimulation of the balance organs of the inner ear (the 'vestibular system') can disrupt numerical cognition, resulting in 'dyscalculia', the inability to manipulate numbers. Many studies have also demonstrated that patients with vestibular dysfunction exhibit deficits in spatial memory. It is suggested that there may be a connection between spatial memory deficits resulting from vestibular dysfunction and the occurrence of dyscalculia, given the evidence that numerosity is coupled to the processing of spatial information (e.g., the 'spatial numerical association of response codes ('SNARC') effect'). The evidence supporting this hypothesis is summarised and potential experiments to test it are proposed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. The vestibular implant: Frequency-dependency of the electrically evoked Vestibulo-Ocular Reflex in humans

    Directory of Open Access Journals (Sweden)

    Raymond eVan De Berg

    2015-01-01

    Full Text Available The Vestibulo-Ocular Reflex (VOR shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR elicited by a vestibular implant, showed the same frequency-dependency.Twelve vestibular electrodes implanted in 7 patients with bilateral vestibular hypofunction were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5Hz, 1Hz, and 2Hz. The main characteristics of the eVOR were evaluated and compared to the natural VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies.A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the natural VOR. Other characteristics of the (eVOR (angle, habituation-index, and asymmetry showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the normal vestibular system.

  12. Practical uses of galvanized steel in electric utility applications

    International Nuclear Information System (INIS)

    Bueche, D.G.

    1995-01-01

    Steel corrosion has been shown to be a major problem for the electric utility industry. Galvanizing has been shown to prevent or substantially slow steel corrosion. This paper describes the galvanizing process, discusses the properties associated with the galvanized coating, and demonstrates galvanizing's durability in specific, real world applications in the electric utility industry

  13. Vestibular Dysfunction in Patients with Enlarged Vestibular Aqueduct.

    Science.gov (United States)

    Zalewski, Chris K; Chien, Wade W; King, Kelly A; Muskett, Julie A; Baron, Rachel E; Butman, John A; Griffith, Andrew J; Brewer, Carmen C

    2015-08-01

    Enlarged vestibular aqueduct (EVA) is the most common inner ear malformation. While a strong correlative relationship between EVA and hearing loss is well established, its association with vestibular dysfunction is less well understood. In this study, we examine the effects of EVA on the vestibular system in patients with EVA. Prospective, cross-sectional study of a cohort ascertained between 1999 and 2013. National Institutes of Health Clinical Center, a federal biomedical research facility. In total, 106 patients with unilateral or bilateral EVA, defined as a midpoint diameter greater than 1.5 mm, were referred or self-referred to participate in a study of the clinical and molecular aspects of EVA. Clinical history was ascertained with respect to the presence or absence of various vestibular signs and symptoms and history of head trauma. Videonystagmography (VNG), cervical vestibular evoked myogenic potential (cVEMP), and rotational vestibular testing (RVT) were performed to assess the vestibular function. Of the patients with EVA, 45% had vestibular signs and symptoms, and 44% of tested patients had abnormal VNG test results. An increased number of vestibular signs and symptoms was correlated with the presence of bilateral EVA (P = .008) and a history of head injury (P VNG results also correlated with a history of head injury (P = .018). Vestibular dysfunction is common in patients with EVA. However, not all patients with vestibular signs and symptoms have abnormal vestibular test results. Clinicians should be aware of the high prevalence of vestibular dysfunction in patients with EVA. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

  14. Role of cerebellar nodulus and uvula on the vestibular quick phase spatial constancy.

    Science.gov (United States)

    Pettorossi, V E; Grassi, S; Errico, P; Barmack, N H

    2001-01-01

    We investigated the orientation of quick phases (QPs) of vestibularly-induced eye movements in rabbits in response to "off-vertical" sinusoidal vestibular stimulation. We also examined the possible role of the cerebellar nodulus and ventral uvula in controlling QP spatial orientation and modification. During "off-vertical" vestibular stimulation QPs remained aligned with the earth's horizontal plane, while the slow phases (SPs) were aligned with the plane of vestibular stimulation. This suggests that QPs are coded in gravito-inertial coordinates and SPs in head coordinates. When rabbits were oscillated in the light (20 degrees peak-to-peak; 0.2 Hz) about an "off-vertical" axis for 2 h, the QPs changed their trajectory, abandoning the earth's horizontal plane to approach the plane of the stimulus. By contrast, in the absence of conjunctive optokinetic stimulation, QPs remained fixed in the earth's horizontal plane even after 2 h of "off-vertical" stimulation. The conjunctive combination of optokinetic and vestibular stimulation caused QPs to change their plane of rotation. After lesion of the nodulus-uvula the ability of rabbits to reorient QPs during conjoint vestibular-optokinetic stimulation was maintained. We conclude that the space orientation and adaptation of QPs do not require cerebellar control.

  15. Encryption in Chaotic Systems with Sinusoidal Excitations

    Directory of Open Access Journals (Sweden)

    G. Obregón-Pulido

    2014-01-01

    Full Text Available In this contribution an encryption method using a chaotic oscillator, excited by “n” sinusoidal signals, is presented. The chaotic oscillator is excited by a sum of “n” sinusoidal signals and a message. The objective is to encrypt such a message using the chaotic behavior and transmit it, and, as the chaotic system is perturbed by the sinusoidal signal, the transmission security could be increased due to the effect of such a perturbation. The procedure is based on the regulation theory and consider that the receiver knows the frequencies of the perturbing signal, with this considerations the algorithm estimates the excitation in such a way that the receiver can cancel out the perturbation and all the undesirable dynamics in order to produce only the message. In this way we consider that the security level is increased.

  16. Drug therapy for peripheral vestibular vertigo

    Directory of Open Access Journals (Sweden)

    L. M. Antonenko

    2017-01-01

    Full Text Available The choice of effective treatments for vestibular vertigo is one of the important problems, by taking into account the high prevalence of peripheral vestibular diseases. Different drugs, such as vestibular suppressants for the relief of acute vertigo attacks and vestibular compensation stimulants for rehabilitation treatment, are used to treat vestibular vertigo. Drug therapy in combination with vestibular exercises is effective in patients with vestibular neuronitis, Meniere's disease, so is that with therapeutic maneuvers in patients with benign paroxysmal positional vertigo. The high therapeutic efficacy and safety of betahistines permit their extensive use for the treatment of various vestibular disorders.

  17. Age-related decline in functional connectivity of the vestibular cortical network.

    Science.gov (United States)

    Cyran, Carolin Anna Maria; Boegle, Rainer; Stephan, Thomas; Dieterich, Marianne; Glasauer, Stefan

    2016-04-01

    In the elderly, major complaints include dizziness and an increasing number of falls, possibly related to an altered processing of vestibular sensory input. In this study, we therefore investigate age-related changes induced by processing of vestibular sensory stimulation. While previous functional imaging studies of healthy aging have investigated brain function during task performance or at rest, we used galvanic vestibular stimulation during functional MRI in a task-free sensory stimulation paradigm to study the effect of healthy aging on central vestibular processing, which might only become apparent during stimulation processing. Since aging may affect signatures of brain function beyond the BOLD-signal amplitude-such as functional connectivity or temporal signal variability--we employed independent component analysis and partial least squares analysis of temporal signal variability. We tested for age-associated changes unrelated to vestibular processing, using a motor paradigm, voxel-based morphometry and diffusion tensor imaging. This allows us to control for general age-related modifications, possibly originating from vascular, atrophic or structural connectivity changes. Age-correlated decreases of functional connectivity and increases of BOLD--signal variability were associated with multisensory vestibular networks. In contrast, no age-related functional connectivity changes were detected in somatosensory networks or during the motor paradigm. The functional connectivity decrease was not due to structural changes but to a decrease in response amplitude. In synopsis, our data suggest that both the age-dependent functional connectivity decrease and the variability increase may be due to deteriorating reciprocal cortico-cortical inhibition with age and related to multimodal vestibular integration of sensory inputs.

  18. Estimating Aquifer Properties Using Sinusoidal Pumping Tests

    Science.gov (United States)

    Rasmussen, T. C.; Haborak, K. G.; Young, M. H.

    2001-12-01

    We develop the theoretical and applied framework for using sinusoidal pumping tests to estimate aquifer properties for confined, leaky, and partially penetrating conditions. The framework 1) derives analytical solutions for three boundary conditions suitable for many practical applications, 2) validates the analytical solutions against a finite element model, 3) establishes a protocol for conducting sinusoidal pumping tests, and 4) estimates aquifer hydraulic parameters based on the analytical solutions. The analytical solutions to sinusoidal stimuli in radial coordinates are derived for boundary value problems that are analogous to the Theis (1935) confined aquifer solution, the Hantush and Jacob (1955) leaky aquifer solution, and the Hantush (1964) partially penetrated confined aquifer solution. The analytical solutions compare favorably to a finite-element solution of a simulated flow domain, except in the region immediately adjacent to the pumping well where the implicit assumption of zero borehole radius is violated. The procedure is demonstrated in one unconfined and two confined aquifer units near the General Separations Area at the Savannah River Site, a federal nuclear facility located in South Carolina. Aquifer hydraulic parameters estimated using this framework provide independent confirmation of parameters obtained from conventional aquifer tests. The sinusoidal approach also resulted in the elimination of investigation-derived wastes.

  19. Unidirectional Motion of Vehicle on Sinusoidal Path

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 17; Issue 4. Unidirectional Motion of Vehicle on Sinusoidal Path: Can it Cause Illusory Forward and Backward Motion? Anuj Bhatnagar. Classroom Volume 17 Issue 4 April 2012 pp 387-392 ...

  20. Riding the Ferris Wheel: A Sinusoidal Model

    Science.gov (United States)

    Mittag, Kathleen Cage; Taylor, Sharon E.

    2011-01-01

    When thinking of models for sinusoidal waves, examples such as tides of the ocean, daily temperatures for one year in your town, light and sound waves, and certain types of motion are used. Many textbooks [1, p. 222] also present a "Ferris wheel description problem" for students to work. This activity takes the Ferris wheel problem out of the…

  1. Model selection and comparison for independents sinusoids

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2014-01-01

    In the signal processing literature, many methods have been proposed for estimating the number of sinusoidal basis functions from a noisy data set. The most popular method is the asymptotic MAP criterion, which is sometimes also referred to as the BIC. In this paper, we extend and improve this me...

  2. Is galvanic corrosion between titanium alloy and stainless steel spinal implants a clinical concern?

    Science.gov (United States)

    Serhan, Hassan; Slivka, Michael; Albert, Todd; Kwak, S Daniel

    2004-01-01

    Surgeons are hesitant to mix components made of differing metal classes for fear of galvanic corrosion complications. However, in vitro studies have failed to show a significant potential for galvanic corrosion between titanium and stainless steel, the two primary metallic alloys used for spinal implants. Galvanic corrosion resulting from metal mixing has not been described in the literature for spinal implant systems. To determine whether galvanic potential significantly affects in vitro corrosion of titanium and stainless steel spinal implant components during cyclical compression bending. Bilateral spinal implant constructs consisting of pedicle screws, slotted connectors, 6.35-mm diameter rods and a transverse rod connector assembled in polyethylene test blocks were tested in vitro. Two constructs had stainless steel rods with mixed stainless steel (SS-SS) and titanium (SS-Ti) components, and two constructs had titanium rods with mixed stainless steel (Ti-SS) and titanium (Ti-Ti) components. Each construct was immersed in phosphate-buffered saline (pH 7.4) at 37 C and tested in cyclic compression bending using a sinusoidal load-controlling function with a peak load of 300 N and a frequency of 5 Hz until a level of 5 million cycles was reached. The samples were then removed and analyzed visually for evidence of corrosion. In addition, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were used to evaluate the extent of corrosion at the interconnections. None of the constructs failed during testing. Gross observation of the implant components after disassembly revealed that no corrosion had occurred on the surface of the implants that had not been in contact with another component. The Ti-Ti interfaces showed some minor signs of corrosion only detectable using SEM and EDS. The greatest amount of corrosion occurred at the SS-SS interfaces and was qualitatively less at the SS-Ti and Ti-SS interfaces. The results from this study indicate

  3. The vestibular implant: Quo vadis?

    Directory of Open Access Journals (Sweden)

    Raymond eVan De Berg

    2011-08-01

    Full Text Available AbstractObjective: to assess the progress of the development of the vestibular implant and its feasibility short-term. Data sources: a search was performed in Pubmed, Medline and Embase. Key words used were vestibular prosth* and vestibular implant. The only search limit was language: English or Dutch. Additional sources were medical books, conference lectures and our personal experience with per-operative vestibular stimulation in patients selected for cochlear implantation.Study selection: all studies about the vestibular implant and related topics were included and evaluated by two reviewers. No study was excluded since every study investigated different aspects of the vestibular implant. Data extraction and synthesis: data was extracted by the first author from selected reports, supplemented by additional information, medical books conference lectures. Since each study had its own point of interest with its own outcomes, it was not possible to compare data of different studies. Conclusion: to use a basic vestibular implant in humans seems feasible in the very near future. Investigations show that electric stimulation of the canal nerves induces a nystagmus which corresponds to the plane of the canal which is innervated by the stimulated nerve branch. The brain is able to adapt to a higher baseline stimulation, while still reacting on a dynamic component. The best response will be achieved by a combination of the optimal stimulus (stimulus profile, stimulus location, precompensation, complemented by central vestibular adaptation. The degree of response will probably vary between individuals, depending on pathology and their ability to adapt.

  4. True incidence of vestibular schwannoma?

    DEFF Research Database (Denmark)

    Stangerup, Sven-Eric; Tos, Mirko; Thomsen, Jens

    2010-01-01

    The incidence of diagnosed sporadic unilateral vestibular schwannomas (VS) has increased, due primarily to more widespread access to magnetic resonance imaging.......The incidence of diagnosed sporadic unilateral vestibular schwannomas (VS) has increased, due primarily to more widespread access to magnetic resonance imaging....

  5. Dissolved oxygen detection by galvanic displacement-induced

    Indian Academy of Sciences (India)

    Dissolved oxygen detection by galvanic displacement-induced graphene/silver nanocomposite ... dissolved oxygen (DO) detection based on a galvanic displacement synthesized reduced graphene oxide–silver nanoparticles ... Current Issue

  6. Epitaxial growth by monolayer restricted galvanic displacement

    Directory of Open Access Journals (Sweden)

    Vasilić Rastko

    2012-01-01

    Full Text Available The development of a new method for epitaxial growth of metals in solution by galvanic displacement of layers pre-deposited by underpotential deposition (UPD was discussed and experimentally illustrated throughout the lecture. Cyclic voltammetry (CV and scanning tunneling microscopy (STM are employed to carry out and monitor a “quasi-perfect”, two-dimensional growth of Ag on Au(111, Cu on Ag(111, and Cu on Au(111 by repetitive galvanic displacement of underpotentially deposited monolayers. A comparative study emphasizes the displacement stoichiometry as an efficient tool for thickness control during the deposition process and as a key parameter that affects the deposit morphology. The excellent quality of layers deposited by monolayer-restricted galvanic displacement is manifested by a steady UPD voltammetry and ascertained by a flat and uniform surface morphology maintained during the entire growth process.

  7. Simulation to coating weight control for galvanizing

    Science.gov (United States)

    Wang, Junsheng; Yan, Zhang; Wu, Kunkui; Song, Lei

    2013-05-01

    Zinc coating weight control is one of the most critical issues for continuous galvanizing line. The process has the characteristic of variable-time large time delay, nonlinear, multivariable. It can result in seriously coating weight error and non-uniform coating. We develop a control system, which can automatically control the air knives pressure and its position to give a constant and uniform zinc coating, in accordance with customer-order specification through an auto-adaptive empirical model-based feed forward adaptive controller, and two model-free adaptive feedback controllers . The proposed models with controller were applied to continuous galvanizing line (CGL) at Angang Steel Works. By the production results, the precise and stability of the control model reduces over-coating weight and improves coating uniform. The product for this hot dip galvanizing line does not only satisfy the customers' quality requirement but also save the zinc consumption.

  8. Visuo-Vestibular Interactions

    Science.gov (United States)

    1997-01-01

    Session TA3 includes short reports covering: (1) Vestibulo-Oculomotor Interaction in Long-Term Microgravity; (2) Effects of Weightlessness on the Spatial Orientation of Visually Induced Eye Movements; (3) Adaptive Modification of the Three-Dimensional Vestibulo-Ocular Reflex during Prolonged Microgravity; (4) The Dynamic Change of Brain Potential Related to Selective Attention to Visual Signals from Left and Right Visual Fields; (5) Locomotor Errors Caused by Vestibular Suppression; and (6) A Novel, Image-Based Technique for Three-Dimensional Eye Measurement.

  9. Vestibular rehabilitation outcomes in the elderly with chronic vestibular dysfunction.

    Science.gov (United States)

    Bayat, Arash; Pourbakht, Akram; Saki, Nader; Zainun, Zuraida; Nikakhlagh, Soheila; Mirmomeni, Golshan

    2012-11-01

    Chronic vestibular dysfunction is a frustrating problem in the elderly and can have a tremendous impact on their life, but only a few studies are available. Vestibular rehabilitation therapy (VRT) is an important therapeutic option for the neuro-otologist in treating patients with significant balance deficits. The purpose of this study was to assess the effect of vestibular rehabilitation on dizziness in elderly patients with chronic vestibular dysfunction. A total of 33 patients older than 60 years with chronic vestibular dysfunction were studied. Clinical and objective vestibular tests including videonystagmography (VNG) and dizziness handicap inventory (DHI) were carried out at their first visit, 2 weeks, and 8 weeks post-VRT. The VRT exercises were performed according to Cawthorne and Cooksey protocols. Oculomotor assessments were within normal limits in all patients. Nineteen patients (57.57%) showed abnormal canal paralysis on caloric testing which at follow-up sessions; CP values were decreased remarkably after VRT exercises. We found a significant improvement between pre-VRT and post-VRT total DHI scores (P < 0.001). This improvement was most prominent in functional subscore. Our study demonstrated that VRT is an effective therapeutic method for elderly patients with chronic vestibular dysfunction.

  10. Galvanic manifestation of spontaneous coherence in the negative glow

    International Nuclear Information System (INIS)

    Zhechev, D; Parvanova, N

    2002-01-01

    Both the magnetic depolarization of the spontaneous emission from self-aligned states and the discharge galvanic reaction are measured simultaneously in a magnetic field. The observed galvanic peak is ascribed to magnetic destruction of self-aligned ensembles of atoms. This presents galvanic manifestation of coherent conductivity. (letter to the editor)

  11. 76 FR 29266 - Galvanized Steel Wire From China and Mexico

    Science.gov (United States)

    2011-05-20

    ...)] Galvanized Steel Wire From China and Mexico Determinations On the basis of the record \\1\\ developed in the... reason of imports from China and Mexico of galvanized steel wire, provided for in subheading 7217.20.30... subsidized imports of galvanized steel wire from China and Mexico. Accordingly, effective March 31, 2011, the...

  12. 77 FR 28404 - Galvanized Steel Wire From China and Mexico

    Science.gov (United States)

    2012-05-14

    ...)] Galvanized Steel Wire From China and Mexico Determinations On the basis of the record \\1\\ developed in the... reason of imports from Mexico of galvanized steel wire, provided for in subheadings 7217.20.30, 7217.20... galvanized steel wire from China and Mexico were sold at LTFV within the meaning of 733(b) of the Act (19 U.S...

  13. Biphase sinusoidal oscillator based on negative resistor.

    Science.gov (United States)

    Bayard, Jean

    2010-06-01

    This paper describes a biphase sinusoidal generator which provides two signals: v(ref)=V(M) sin(omegat) and v(out)=V(M) sin(omegat+DeltaPhi), where DeltaPhi is in the range 0, pi/2 or -pi/2, 0 and is not dependent on the frequency value. It is based on a negative resistor and it requires very few components. SPICE simulations and measurements on an experimental setup confirm the theoretical analysis.

  14. Presbivértigo: ejercicios vestibulares Presbivertigo: vestibular exercises

    Directory of Open Access Journals (Sweden)

    Esther Bernal Valls

    2006-12-01

    Full Text Available El uso de ejercicios en el tratamiento de pacientes con déficit vestibular crónico está incrementándose de forma notable, lo que evidencia que se trata de un procedimiento que resulta beneficioso para este tipo de pacientes. Los buenos resultados que se obtienen sugieren que los ejercicios vestibulares dan lugar a una estabilidad postural y a una disminución de la sensación de desequilibrio.The use of exercises in the treatment of patients with vestibular deficits is increasing in a representative way, what evidences this is a profitable process for this kind of patients. The good results suggest that vestibular exercises permit a postural stability and a decrease in the perception of disequilibrium.

  15. Galvanic high energy cells with molten electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Borger, W.; Kappus, W.; Kunze, D.; Laig-Hoerstebrock, H.; Panesar, H.; Sterr, G.

    1981-01-01

    To develop a galvanic cell with molten salt electrolyte for electric vehicle propulsion and load leveling as well as to fabricate ten prototype cells with a capacity of at least 150 Ah (5 hour rate) and an energy density of 80 Wh/kg was the objective of this project.

  16. Galvanic Cells: Anodes, Cathodes, Signs and Charges

    Science.gov (United States)

    Goodwin, Alan

    2011-01-01

    Electrochemistry is a difficult subject for students at school and beyond and even for their teachers. This article explores the difficult "truth" that, when a current flows from a galvanic cell, positive ions within the cell electrolyte move towards the electrode labelled positive. This seems to contravene the basic rule that like charges repel…

  17. Postural Effects of Vestibular Manipulation Depend on the Physical Activity Status.

    Directory of Open Access Journals (Sweden)

    Julien Maitre

    Full Text Available The purpose of this study was to compare the effects of galvanic vestibular stimulation (GVS on postural control for participants of different physical activity status (i.e. active and non-active. Two groups of participants were recruited: one group of participants who regularly practised sports activities (active group, n = 17, and one group of participants who did not practise physical and/or sports activities (non-active group, n = 17. They were compared in a reference condition (i.e bipedal stance with eyes open and four vestibular manipulation condition (i.e. GVS at 0.5 mA and 3 mA, in accordance with two designs lasting 20 seconds. The centre of foot pressure displacement velocities were compared between the two groups. The main results indicate that the regular practice of sports activities counteracts postural control disruption caused by GVS. The active group demonstrated better postural control than the non-active group when subjected to higher vestibular manipulation. The active group may have developed their ability to reduce the influence of inaccurate vestibular signals. The active participants could identify the relevant sensory input, thought a better central integration, which enables them to switch faster between sensory inputs.

  18. Rotatory and collic vestibular evoked myogenic potential testing in normal-hearing and hearing-impaired children.

    Science.gov (United States)

    Maes, Leen; De Kegel, Alexandra; Van Waelvelde, Hilde; Dhooge, Ingeborg

    2014-01-01

    Vertigo and imbalance are often underestimated in the pediatric population, due to limited communication abilities, atypical symptoms, and relatively quick adaptation and compensation in children. Moreover, examination and interpretation of vestibular tests are very challenging, because of difficulties with cooperation and maintenance of alertness, and because of the sometimes nauseatic reactions. Therefore, it is of great importance for each vestibular laboratory to implement a child-friendly test protocol with age-appropriate normative data. Because of the often masked appearance of vestibular problems in young children, the vestibular organ should be routinely examined in high-risk pediatric groups, such as children with a hearing impairment. Purposes of the present study were (1) to determine age-appropriate normative data for two child-friendly vestibular laboratory techniques (rotatory and collic vestibular evoked myogenic potential [cVEMP] test) in a group of children without auditory or vestibular complaints, and (2) to examine vestibular function in a group of children presenting with bilateral hearing impairment. Forty-eight typically developing children (mean age 8 years 0 months; range: 4 years 1 month to 12 years 11 months) without any auditory or vestibular complaints as well as 39 children (mean age 7 years 8 months; range: 3 years 8 months to 12 years 10 months) with a bilateral sensorineural hearing loss were included in this study. All children underwent three sinusoidal rotations (0.01, 0.05, and 0.1 Hz at 50 degrees/s) and bilateral cVEMP testing. No significant age differences were found for the rotatory test, whereas a significant increase of N1 latency and a significant threshold decrease was noticeable for the cVEMP, resulting in age-appropriate normative data. Hearing-impaired children demonstrated significantly lower gain values at the 0.01 Hz rotation and a larger percentage of absent cVEMP responses compared with normal-hearing children

  19. Perspectives on aging vestibular function

    Directory of Open Access Journals (Sweden)

    Eric eAnson

    2016-01-01

    Full Text Available Much is known about age related anatomical changes in the vestibular system. Knowledge regarding how vestibular anatomical changes impact behavior for older adults continues to grow, in line with advancements in diagnostic testing. However, despite advancements in clinical diagnostics, much remains unknown about the functional impact that an aging vestibular system has on daily life activities like standing and walking. Modern diagnostic tests are very good at characterizing neural activity of the isolated vestibular system, but the tests themselves are artificial and do not reflect the multi-sensory aspects of natural human behavior. Also, the majority of clinical diagnostic tests are passively applied because active behavior can enhance performance. In this perspective paper we review anatomical and behavioral changes associated with an aging vestibular system and highlight several areas where a more functionally relevant perspective can be taken. For postural control, a multi-sensory perturbation approach could be used to bring balance rehabilitation into the arena of precision medicine. For walking and complex gaze stability, this may result in less physiologically specific impairments, but the trade-off would be a greater understanding of how the aging vestibular system truly impacts the daily life of older adults.

  20. Vestibular findings in fibromyalgia patients

    Directory of Open Access Journals (Sweden)

    Zeigelboim, Bianca Simone

    2011-07-01

    Full Text Available Introduction: Fibromyalgia (FM is a non-inflammatory musculoskeletal chronic syndrome, whose etiology is unknown, characterized by a diffuse pain, increase in palpation sensitivity and such symptoms as tiredness, insomnia, anxiety, depression, cold intolerance and otologic complaints. Objective: Evaluate the vestibular behavior in fibromyalgia patients. Method: A retrospective transversal study was performed. 25 patients aged between 26 and 65 (average age - 52.2 and standard deviation - 10.3 were evaluated and submitted to the following procedures: anamnesis, otorhinolaryngologic and vestibular evaluation by way of vector electronystamography. Results: a The most evident otoneurologic symptoms were: difficulty or pain when moving the neck and pain was spread to an arm or shoulder (92.0% in each, dizziness (84.0% and headache (76.0%. The different clinical symptoms mostly reported were: depression (80.0%, anxiety (76.0% and insomnia (72.0%; b vestibular examination showed an alteration in 12 patients (48.0% in the caloric test; c an alteration in the peripheral vestibular system prevailed, and d deficient peripheral vestibular disorders were prevalent. Conclusion: This study enabled the importance of the labyrinthic test to be verified, thus emphasizing that this kind of people must be studied better, since a range of rheumatologic diseases can cause severe vestibular changes as a result of their manifestations and impairment areas.

  1. Atypical Manifestation of Vestibular Schwannoma

    Directory of Open Access Journals (Sweden)

    Webster, Guilherme

    2013-09-01

    Full Text Available Introduction: Vestibular schwannoma (also known as acoustic neuroma is a benign tumor whose cells are derived from Schwann sheaths, which commonly occurs from the vestibular portion of the eighth cranial nerve. Furthermore, vestibular schwannomas account for ∼8% of intracranial tumors in adults and 80 to 90% of tumors of the cerebellopontine angle. Its symptoms are varied, but what stands out most is a unilateral sensorineural hearing loss, with a low index of speech recognition. Objective: Describe an atypical manifestation of vestibular schwannoma. Case Report: The 46-year-old woman had vertigo and binaural hearing loss and fullness, with ear, nose, and throat examination suggestive of cochlear injury. After 6 months, the patient developed worsening of symptoms and onset of right unilateral tinnitus. In further exams the signs of cochlear damage remained, except for the vestibular test (hyporeflexia. Magnetic resonance imaging showed an expansive lesion in the right cerebellopontine angle. Discussion: This report warns about the atypical manifestations of vestibular schwannoma, which must always be remembered in investigating and diagnosing hearing loss.

  2. Vestibular hearing and neural synchronization.

    Science.gov (United States)

    Emami, Seyede Faranak; Daneshi, Ahmad

    2012-01-01

    Objectives. Vestibular hearing as an auditory sensitivity of the saccule in the human ear is revealed by cervical vestibular evoked myogenic potentials (cVEMPs). The range of the vestibular hearing lies in the low frequency. Also, the amplitude of an auditory brainstem response component depends on the amount of synchronized neural activity, and the auditory nerve fibers' responses have the best synchronization with the low frequency. Thus, the aim of this study was to investigate correlation between vestibular hearing using cVEMPs and neural synchronization via slow wave Auditory Brainstem Responses (sABR). Study Design. This case-control survey was consisted of twenty-two dizzy patients, compared to twenty healthy controls. Methods. Intervention comprised of Pure Tone Audiometry (PTA), Impedance acoustic metry (IA), Videonystagmography (VNG), fast wave ABR (fABR), sABR, and cVEMPs. Results. The affected ears of the dizzy patients had the abnormal findings of cVEMPs (insecure vestibular hearing) and the abnormal findings of sABR (decreased neural synchronization). Comparison of the cVEMPs at affected ears versus unaffected ears and the normal persons revealed significant differences (P < 0.05). Conclusion. Safe vestibular hearing was effective in the improvement of the neural synchronization.

  3. Regorafenib suppresses sinusoidal obstruction syndrome in rats.

    Science.gov (United States)

    Okuno, Masayuki; Hatano, Etsuro; Nakamura, Kojiro; Miyagawa-Hayashino, Aya; Kasai, Yosuke; Nishio, Takahiro; Seo, Satoru; Taura, Kojiro; Uemoto, Shinji

    2015-02-01

    Sinusoidal obstruction syndrome (SOS), a form of drug-induced liver injury related to oxaliplatin treatment, is associated with postoperative morbidity after hepatectomy. This study aimed to examine the impact of regorafenib, the first small-molecule kinase inhibitor to show efficacy against metastatic colorectal cancer, on a rat model of SOS. Rats with monocrotaline (MCT)-induced SOS were divided into two groups according to treatment with either regorafenib (6 mg/kg) or vehicle alone, which were administered at 12 and 36 h, respectively, before MCT administration. Histopathologic examination and serum biochemistry tests were performed 48 h after MCT administration. Sinusoidal endothelial cells were evaluated by immunohistochemistry and electron microscopy. To examine whether regorafenib preserved remnant liver function, a 30% hepatectomy was performed in each group. The rats in the vehicle group displayed typical SOS features, whereas these features were suppressed in the regorafenib group. The total SOS scores were significantly lower in the regorafenib group than in the vehicle group. Immunohistochemistry and electron microscopy showed that regorafenib had a protective effect on sinusoidal endothelial cells. The postoperative survival rate after 7 d was significantly better in the regorafenib group than that in the vehicle group (26.7% versus 6.7%, P Regorafenib reduced the phosphorylation of extracellular signal-regulated kinase, which induced matrix metalloproteinase-9 (MMP-9) activation and decreased the activity of MMP-9, one of the crucial mediators of SOS development. Regorafenib suppressed MCT-induced SOS, concomitant with attenuating extracellular signal-regulated kinase phosphorylation, and MMP-9 activation, suggesting that regorafenib may be a favorable agent for use in combination with oxaliplatin-based chemotherapy. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Galvanic corrosion -- Effect of environmental and experimental variables

    International Nuclear Information System (INIS)

    Roy, A.K.; Fleming, D.L.; Lum, B.Y.

    1999-01-01

    Galvanic corrosion behavior of A 516 steel (UNS K01800) coupled to UNS N06022 and UNS R53400, respectively was evaluated in an acidic brine (pH ∼ 2.75) at 30 C, 60 C and 80 C using zero resistance ammeter method. A limited number of experiments were also performed in a neutral brine involving A 516 steel/UNS N06022 couple. The steady-state galvanic current and galvanic potential were measured as functions of anode-to-cathode (A/C) area ratio and electrode distance. Results indicate that the galvanic current was gradually reduced as the A/C area ratio was increased. No systematic trend on the effect of A/C area ratio on the galvanic potential was observed. Also, no significant effect of electrode distance on the galvanic current and galvanic potential was evident. In general, increased galvanic current was noticed with increasing temperature. The limited data obtained in the neutral brine indicate that the galvanic current was reduced in this environment compared to that in the acidic brine. Optical microscopic examination was performed on all tested specimens to evaluate the extent of surface damage resulting from galvanic interaction. A 516 steel suffered from general corrosion and crevice corrosion in all environments tested. Very light crevice corrosion mark was observed with UNS N06022 and R53400 in the acidic brine at 60 C and 80 C. However, this mark appears to be a surface discoloration and no actual crevice was detected

  5. Galvanically Decoupled Current Source Modules for Multi-Channel Bioimpedance Measurement Systems

    Directory of Open Access Journals (Sweden)

    Roman Kusche

    2017-10-01

    Full Text Available Bioimpedance measurements have become a useful technique in the past several years in biomedical engineering. Especially, multi-channel measurements facilitate new imaging and patient monitoring techniques. While most instrumentation research has focused on signal acquisition and signal processing, this work proposes the design of an excitation current source module that can be easily implemented in existing or upcoming bioimpedance measurement systems. It is galvanically isolated to enable simultaneous multi-channel bioimpedance measurements with a very low channel-coupling. The system is based on a microcontroller in combination with a voltage-controlled current source circuit. It generates selectable sinusoidal excitation signals between 0.12 and 1.5 mA in a frequency range from 12 to 250 kHz, whereas the voltage compliance range is ±3.2 V. The coupling factor between two current sources, experimentally galvanically connected with each other, is measured to be less than −48 dB over the entire intended frequency range. Finally, suggestions for developments in the future are made.

  6. Aging of the Human Vestibular System

    OpenAIRE

    Zalewski, Christopher K.

    2015-01-01

    Aging affects every sensory system in the body, including the vestibular system. Although its impact is often difficult to quantify, the deleterious impact of aging on the vestibular system is serious both medically and economically. The deterioration of the vestibular sensory end organs has been known since the 1970s; however, the measurable impact from these anatomical changes remains elusive. Tests of vestibular function either fall short in their ability to quantify such anatomical deteri...

  7. Corrosion of Galvanized Steel Under Different Soil Moisture Contents

    OpenAIRE

    Pereira,Roseana Florentino da Costa; Oliveira,Edkarlla Sousa Dantas de; Lima,Maria Alice Gomes de Andrade; Brasil,Simone Louise Delarue Cezar

    2015-01-01

    Galvanized steel has been widely applied in different applications and the industry significantly increased its production in recent years. Some galvanized structures can be completely or partially buried, such as transmission tower footings. The corrosion of these metallic structures is related to the soil chemical and physicochemical properties, which define the aggressiveness of the environment. To assess the effect of the soil moisture on galvanized steel corrosion, a comparative study wa...

  8. Amplitude Modulated Sinusoidal Signal Decomposition for Audio Coding

    DEFF Research Database (Denmark)

    Christensen, M. G.; Jacobson, A.; Andersen, S. V.

    2006-01-01

    In this paper, we present a decomposition for sinusoidal coding of audio, based on an amplitude modulation of sinusoids via a linear combination of arbitrary basis vectors. The proposed method, which incorporates a perceptual distortion measure, is based on a relaxation of a nonlinear least......-squares minimization. Rate-distortion curves and listening tests show that, compared to a constant-amplitude sinusoidal coder, the proposed decomposition offers perceptually significant improvements in critical transient signals....

  9. Compressed Domain Packet Loss Concealment of Sinusoidally Coded Speech

    DEFF Research Database (Denmark)

    Rødbro, Christoffer A.; Christensen, Mads Græsbøll; Andersen, Søren Vang

    2003-01-01

    We consider the problem of packet loss concealment for voice over IP (VoIP). The speech signal is compressed at the transmitter using a sinusoidal coding scheme working at 8 kbit/s. At the receiver, packet loss concealment is carried out working directly on the quantized sinusoidal parameters......, based on time-scaling of the packets surrounding the missing ones. Subjective listening tests show promising results indicating the potential of sinusoidal speech coding for VoIP....

  10. Parametric modeling for damped sinusoids from multiple channels

    DEFF Research Database (Denmark)

    Zhou, Zhenhua; So, Hing Cheung; Christensen, Mads Græsbøll

    2013-01-01

    frequencies and damping factors are then computed with the multi-channel weighted linear prediction method. The estimated sinusoidal poles are then matched to each channel according to the extreme value theory of distribution of random fields. Simulations are performed to show the performance advantages......The problem of parametric modeling for noisy damped sinusoidal signals from multiple channels is addressed. Utilizing the shift invariance property of the signal subspace, the number of distinct sinusoidal poles in the multiple channels is first determined. With the estimated number, the distinct...... of the proposed multi-channel sinusoidal modeling methodology compared with existing methods....

  11. Stereotactic radiotherapy for vestibular schwannoma

    DEFF Research Database (Denmark)

    Muzevic, Dario; Legcevic, Jelena; Splavski, Bruno

    2014-01-01

    BACKGROUND: Vestibular schwannomas (acoustic neuromas) are common benign tumours that arise from the Schwann cells of the vestibular nerve. Management options include observation with neuroradiological follow-up, microsurgical resection and stereotactic radiotherapy. OBJECTIVES: To assess...... the effect of stereotactic radiotherapy compared to observation, microsurgical resection, any other treatment modality, or a combination of two or more of the above approaches for vestibular schwannoma. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials; PubMed; EMBASE; CINAHL......; Web of Science; CAB Abstracts; ISRCTN and additional sources for published and unpublished trials. The date of the search was 24 July 2014. SELECTION CRITERIA: Randomised controlled trials (RCTs) exploring the efficacy of stereotactic radiotherapy compared with observation alone, microsurgical...

  12. [Infrared videonystagmography in vestibular diagnosis].

    Science.gov (United States)

    Frisina, A; Piazza, F; Quaranta, N

    2000-01-01

    Vestibular examination relied upon electronystagmography (ENG) for more than 50 years. This method is based on recording of nystagmus (Ny) without any possibility to see the ocular movements directly. More recently, infrared videonystagmography (VNG) entered the diagnostic protocol of vestibular disorders. VNG permits to record and visualize Ny, both in the darkness and with open eyes. Aim of the present study was to verify the possible advantages of VNG versus ENG for functional evaluation of the vestibular system in patients suffering from otoneurological disorders. To that purpose, VNG and ENG tracings were recorded in 12 patients. The preliminary results show that there are not significant differences in quantitative evaluation of Ny between the two methods. Anyhow, VNG has some technical and clinical advantages that make it the method of choice.

  13. Stochastic analysis/synthesis using sinusoidal atoms

    DEFF Research Database (Denmark)

    Jensen, Kristoffer

    2008-01-01

    This work proposes a method for re-synthesizing music for use in perceptual experiments regarding structural changes and in music creation. Atoms are estimated from music audio, modelled in a stochastic model, and re-synthesized from the model pa- rameters. The atoms are found by splitting...... sinusoids into short segments, and modelled into amplitude and envelope shape, frequency, time and duration. A simple model for creating envelopes with percussive, sustained or crescendo shape is presented. Single variable and joint probability density functions are created from the atom parameters and used...... to re-create sounds with the same distribution of the atoms parameters. A novel method for visualization music, the musigram, permits a better understanding of the re- synthesized sounds....

  14. Sinusoidal Order Estimation Using Angles between Subspaces

    Directory of Open Access Journals (Sweden)

    Søren Holdt Jensen

    2009-01-01

    Full Text Available We consider the problem of determining the order of a parametric model from a noisy signal based on the geometry of the space. More specifically, we do this using the nontrivial angles between the candidate signal subspace model and the noise subspace. The proposed principle is closely related to the subspace orthogonality property known from the MUSIC algorithm, and we study its properties and compare it to other related measures. For the problem of estimating the number of complex sinusoids in white noise, a computationally efficient implementation exists, and this problem is therefore considered in detail. In computer simulations, we compare the proposed method to various well-known methods for order estimation. These show that the proposed method outperforms the other previously published subspace methods and that it is more robust to the noise being colored than the previously published methods.

  15. Postural threat differentially affects the feedforward and feedback components of the vestibular-evoked balance response.

    Science.gov (United States)

    Osler, Callum J; Tersteeg, M C A; Reynolds, Raymond F; Loram, Ian D

    2013-10-01

    Circumstances may render the consequence of falling quite severe, thus maximising the motivation to control postural sway. This commonly occurs when exposed to height and may result from the interaction of many factors, including fear, arousal, sensory information and perception. Here, we examined human vestibular-evoked balance responses during exposure to a highly threatening postural context. Nine subjects stood with eyes closed on a narrow walkway elevated 3.85 m above ground level. This evoked an altered psycho-physiological state, demonstrated by a twofold increase in skin conductance. Balance responses were then evoked by galvanic vestibular stimulation. The sway response, which comprised a whole-body lean in the direction of the edge of the walkway, was significantly and substantially attenuated after ~800 ms. This demonstrates that a strong reason to modify the balance control strategy was created and subjects were highly motivated to minimise sway. Despite this, the initial response remained unchanged. This suggests little effect on the feedforward settings of the nervous system responsible for coupling pure vestibular input to functional motor output. The much stronger, later effect can be attributed to an integration of balance-relevant sensory feedback once the body was in motion. These results demonstrate that the feedforward and feedback components of a vestibular-evoked balance response are differently affected by postural threat. Although a fear of falling has previously been linked with instability and even falling itself, our findings suggest that this relationship is not attributable to changes in the feedforward vestibular control of balance. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  16. Vestibular migraine: who is the patient?

    Science.gov (United States)

    Colombo, Bruno; Teggi, Roberto

    2017-05-01

    Vestibular migraine has been classified as a specific entity in which vestibular symptomatology is defined as part of the migrainous disorder. New and appropriate diagnostic criteria have been proposed by the Barany and International Headache Societies. The diagnosis of vestibular migraine mainly depends on the patient history. The NIVE project is a prospectic multicentric study on vestibular migraine. The aim of this project is to evaluate demographics, epidemiology, clinical manifestations of migraine and vertigo in a large cohort of Caucasian patients affected by vestibular migraine.

  17. Variable Dimension Trellis-Coded Quantization of Sinusoidal Parameters

    DEFF Research Database (Denmark)

    Larsen, Morten Holm; Christensen, Mads G.; Jensen, Søren Holdt

    2008-01-01

    In this letter, we propose joint quantization of the parameters of a set of sinusoids based on the theory of trellis-coded quantization. A particular advantage of this approach is that it allows for joint quantization of a variable number of sinusoids, which is particularly relevant in variable...

  18. Towards a neuromorphic vestibular system.

    Science.gov (United States)

    Corradi, Federico; Zambrano, Davide; Raglianti, Marco; Passetti, Giovanni; Laschi, Cecilia; Indiveri, Giacomo

    2014-10-01

    The vestibular system plays a crucial role in the sense of balance and spatial orientation in mammals. It is a sensory system that detects both rotational and translational motion of the head, via its semicircular canals and otoliths respectively. In this work, we propose a real-time hardware model of an artificial vestibular system, implemented using a custom neuromorphic Very Large Scale Integration (VLSI) multi-neuron chip interfaced to a commercial Inertial Measurement Unit (IMU). The artificial vestibular system is realized with spiking neurons that reproduce the responses of biological hair cells present in the real semicircular canals and otholitic organs. We demonstrate the real-time performance of the hybrid analog-digital system and characterize its response properties, presenting measurements of a successful encoding of angular velocities as well as linear accelerations. As an application, we realized a novel implementation of a recurrent integrator network capable of keeping track of the current angular position. The experimental results provided validate the hardware implementation via comparisons with a detailed computational neuroscience model. In addition to being an ideal tool for developing bio-inspired robotic technologies, this work provides a basis for developing a complete low-power neuromorphic vestibular system which integrates the hardware model of the neural signal processing pathway described with custom bio-mimetic gyroscopic sensors, exploiting neuromorphic principles in both mechanical and electronic aspects.

  19. Perspectival Structure and Vestibular Processing

    DEFF Research Database (Denmark)

    Alsmith, Adrian John Tetteh

    2016-01-01

    I begin by contrasting a taxonomic approach to the vestibular system with the structural approach I take in the bulk of this commentary. I provide an analysis of perspectival structure. Employing that analysis and following the structural approach, I propose three lines of empirical investigation...

  20. Significant vestibular system impairment is common in a cohort of elderly patients referred for assessment of falls risk.

    Science.gov (United States)

    Jacobson, Gary P; McCaslin, Devin L; Grantham, Sarah L; Piker, Erin G

    2008-01-01

    Falls in elderly patients are associated with morbidity, mortality, and cost to the healthcare system. The development of falls risk assessment programs have represented a method of responding to what is known about injurious falls. The multidimensional assessments involve the comparison against normative data of a patient's performance on metrics known to influence the likelihood of future falls. The factors assessed usually include falls and medication history, measures of mentation, depression, orthostatic hypotension, simple or choice reaction time, gait stability, postural stability, and the integrity of the patient's vision, somesthetic, and vestibular senses. This investigation was conducted to measure the proportion of patients referred for falls risk assessment who have evidence of vestibular system impairment. Qualitative, retrospective review of data collected from 2003 to 2007. The cohort was 185 consecutive patients referred for multidimensional assessments of falls risk. Patients underwent quantitative assessments of peripheral and central vestibular system function consisting of electro- or videonystagmography (i.e., ENG/VNG), and sinusoidal harmonic acceleration testing. Results of these tests were compared to normative data. We found that 73% of the sample who underwent vestibular system assessment had quantitative evidence of either peripheral or central vestibular system impairment. Our results suggest that quantitative assessments of the vestibulo-ocular reflex should be conducted on patients who are evaluated for falls risk. These examinations should include at least caloric testing and, where available, rotational testing.

  1. Flow-accelerated corrosion characteristics of galvanically coupled dissimilar metals

    International Nuclear Information System (INIS)

    Choi, Yoon Seok; Kim, Jnng Gu

    2001-01-01

    Flow accelerated galvanic corrosion characteristics of a carbon steel coupled to stainless steel were investigated in deaerated alkaline-chloride solutions as a function of flow velocities, pH and temperatures. The electrochemical properties of specimens were investigated by potentiodynamic test and galvanic corrosion test using RCE(Rotating Cylinder Electrode). Carbon steel showed active behavior in the deaerated alkaline-chloride solution. The galvanic current density of carbon steel increased with increasing flow velocity and temperature, but decreased with increasing pH. Flow velocity had a small effect on the galvanic current density at 25 deg. C, whereas the flow velocity increased galvanic current density significantly at 50 .deg. C and 75 .deg. C. This might be due to the increased solubility of magnetite at the higher temperatures

  2. HASHIMOTO THYROIDITIS AND VESTIBULAR DYSFUNCTION.

    Science.gov (United States)

    Chiarella, Giuseppe; Russo, Diego; Monzani, Fabio; Petrolo, Claudio; Fattori, Bruno; Pasqualetti, Giuseppe; Cassandro, Ettore; Costante, Giuseppe

    2017-07-01

    The aim of this review was to analyze the existing literature concerning the relationship between Hashimoto thyroiditis (HT) and vestibular dysfunction. We used electronic databases (PubMed, EMBASE, Cochrane Library) to search and collect all published articles about the association between HT and vestibular disorders. Several observational and retrospective studies have postulated a relationship between thyroid autoimmunity and vestibular disorders. In most cases, an appropriate control group was lacking, and the impact of thyroid functional status could not precisely be established. In recent years, two well-designed prospective studies have provided convincing evidence that the association is not random. One article reported that patients with Ménière disease (MD) had a significantly higher prevalence of positive anti-thyroid autoantibody as compared to healthy controls. Moreover, more than half of MD patients had either positive anti-thyroid or non-organ-specific autoantibody titers, compared to less than 30% of both patients with unilateral vestibular paresis without cochlear involvement and healthy controls. Another study found that patients with benign paroxysmal positional vertigo (BPPV) had significantly higher serum thyroid-stimulating hormone and antithyroid autoantibody levels than healthy controls. Additionally, almost one-fifth of euthyroid patients with HT had signs of BPPV. The published results indicate that patients with MD or BPPV are potential candidates to also develop HT. Thus, in HT patients, the presence of even slight symptoms or signs potentially related to vestibular lesions should be carefully investigated. AITD = autoimmune thyroid disease; BPPV = benign paroxysmal positional vertigo; EH = endolymphatic hydrops; HT = Hashimoto thyroiditis; L-T 4 = L-thyroxine; MD = Ménière disease; PS = Pendred syndrome; Tg = thyroglobulin; TPO = thyroid peroxidase; TSH = thyroid-stimulating hormone.

  3. Sensorless optimal sinusoidal brushless direct current for hard disk drives

    Science.gov (United States)

    Soh, C. S.; Bi, C.

    2009-04-01

    Initiated by the availability of digital signal processors and emergence of new applications, market demands for permanent magnet synchronous motors have been surging. As its back-emf is sinusoidal, the drive current should also be sinusoidal for reducing the torque ripple. However, in applications like hard disk drives, brushless direct current (BLDC) drive is adopted instead of sinusoidal drive for simplification. The adoption, however, comes at the expense of increased harmonics, losses, torque pulsations, and acoustics. In this paper, we propose a sensorless optimal sinusoidal BLDC drive. First and foremost, the derivation for an optimal sinusoidal drive is presented, and a power angle control scheme is proposed to achieve an optimal sinusoidal BLDC. The scheme maintains linear relationship between the motor speed and drive voltage. In an attempt to execute the sensorless drive, an innovative power angle measurement scheme is devised, which takes advantage of the freewheeling diodes and measures the power angle through the detection of diode voltage drops. The objectives as laid out will be presented and discussed in this paper, supported by derivations, simulations, and experimental results. The proposed scheme is straightforward, brings about the benefits of sensorless sinusoidal drive, negates the need for current sensors by utilizing the freewheeling diodes, and does not incur additional cost.

  4. Prophylactic treatment of vestibular migraine

    Directory of Open Access Journals (Sweden)

    Márcio Cavalcante Salmito

    Full Text Available Abstract Introduction: Vestibular migraine (VM is now accepted as a common cause of episodic vertigo. Treatment of VM involves two situations: the vestibular symptom attacks and the period between attacks. For the latter, some prophylaxis methods can be used. The current recommendation is to use the same prophylactic drugs used for migraines, including β-blockers, antidepressants and anticonvulsants. The recent diagnostic definition of vestibular migraine makes the number of studies on its treatment scarce. Objective: To evaluate the efficacy of prophylactic treatment used in patients from a VM outpatient clinic. Methods: Review of medical records from patients with VM according to the criteria of the Bárány Society/International Headache Society of 2012 criteria. The drugs used in the treatment and treatment response obtained through the visual analog scale (VAS for dizziness and headache were assessed. The pre and post-treatment VAS scores were compared (the improvement was evaluated together and individually, per drug used. Associations with clinical subgroups of patients were also assessed. Results: Of the 88 assessed records, 47 were eligible. We included patients that met the diagnostic criteria for VM and excluded those whose medical records were illegible and those of patients with other disorders causing dizziness and/or headache that did not meet the 2012 criteria for VM. 80.9% of the patients showed improvement with prophylaxis (p < 0.001. Amitriptyline, Flunarizine, Propranolol and Topiramate improved vestibular symptoms (p < 0.001 and headache (p < 0.015. The four drugs were effective in a statistically significant manner. There was a positive statistical association between the time of vestibular symptoms and clinical improvement. There was no additional benefit in hypertensive patients who used antihypertensive drugs as prophylaxis or depressed patients who used antidepressants in relation to other prophylactic drugs. Drug

  5. 76 FR 55031 - Galvanized Steel Wire From the People's Republic of China: Preliminary Affirmative Countervailing...

    Science.gov (United States)

    2011-09-06

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-976] Galvanized Steel Wire From... galvanized steel wire (galvanized wire) from the People's Republic of China (PRC). For information on the..., filed in proper form, concerning imports of galvanized wire from the PRC.\\1\\ The Department initiated a...

  6. 77 FR 17418 - Galvanized Steel Wire From the People's Republic of China: Final Affirmative Countervailing Duty...

    Science.gov (United States)

    2012-03-26

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-976] Galvanized Steel Wire From... exporters of galvanized steel wire (galvanized wire) from the People's Republic of China (the PRC). For... three parties withdrew their requests for a hearing. \\1\\ See Galvanized Steel Wire From the People's...

  7. Defibrotide: An Oligonucleotide for Sinusoidal Obstruction Syndrome.

    Science.gov (United States)

    Aziz, May T; Kakadiya, Payal P; Kush, Samantha M; Weigel, Kylie; Lowe, Denise K

    2018-02-01

    To review the efficacy and safety of defibrotide as well as its pharmacology, mechanism of action, pharmacokinetics (PK), drug-drug interactions, dosing, cost considerations, and place in therapy. A PubMed search was performed through August 2017 using the terms defibrotide, oligonucleotide, hepatic veno-occlusive disease (VOD), sinusoidal obstruction syndrome (SOS), and hematopoietic cell transplantation (HCT). Other data sources were from references of identified studies, review articles, and conference abstracts plus manufacturer product labeling and website, the Food and Drug Administration website, and clinicaltrials.gov. English-language trials that examined defibrotide's pharmacodynamics, mechanism, PK, efficacy, safety, dosing, and cost-effectiveness were included. Trials have confirmed the safety and efficacy of defibrotide for treatment of VOD/SOS in adult and pediatric HCT patients, with complete response rates and day +100 overall survival rates ranging from 25.5% to 76% and 35% to 64%, respectively. The British Committee for Standards in Haematology/British Society for Blood and Marrow Transplantation Guidelines recommend defibrotide prophylaxis in pediatric and adult HCT patients with risk factors for VOD/SOS; however, its prophylactic use in the United States is controversial. Although there are efficacy data to support this strategy, cost-effectiveness data have not shown it to be cost-effective. Defibrotide has manageable toxicities, with low rates of grade 3 to 4 adverse effects. Defibrotide is the first medication approved in the United States for the treatment of adults and children with hepatic VOD/SOS, with renal or pulmonary dysfunction following HCT. Data evaluating defibrotide for VOD/SOS prevention are conflicting and have not shown cost-effectiveness.

  8. Sinusoidal Analysis-Synthesis of Audio Using Perceptual Criteria

    Science.gov (United States)

    Painter, Ted; Spanias, Andreas

    2003-12-01

    This paper presents a new method for the selection of sinusoidal components for use in compact representations of narrowband audio. The method consists of ranking and selecting the most perceptually relevant sinusoids. The idea behind the method is to maximize the matching between the auditory excitation pattern associated with the original signal and the corresponding auditory excitation pattern associated with the modeled signal that is being represented by a small set of sinusoidal parameters. The proposed component-selection methodology is shown to outperform the maximum signal-to-mask ratio selection strategy in terms of subjective quality.

  9. Personality Changes in Patients with Vestibular Dysfunction

    Directory of Open Access Journals (Sweden)

    Paul eSmith

    2013-10-01

    Full Text Available The vestibular system is a sensory system that has evolved to detect linear and angular acceleration of the head in all planes so that the brain is not predominantly reliant on visual information to determine self-motion. Since the vestibular system first evolved in invertebrate species in order to detect gravitational vertical, it is likely that the central nervous system has developed a special dependence upon vestibular input. In addition to the deficits in eye movement and postural reflexes that occur following vestibular dysfunction, there is convincing evidence that vestibular loss also causes cognitive and emotional disorders, some of which may be due to the reflexive deficits and some of which are related to the role that ascending vestibular pathways to the limbic system and cortex play in the sense of spatial orientation. Beyond this, however, patients with vestibular disorders have been reported to experience other personality changes that suggest that vestibular sensation is implicated in the sense of self. These are depersonalisation and derealisation symptoms such as feeling ‘spaced out’, ‘body feeling strange’ and ‘not feeling in control of self’. We suggest in this review that these symptoms suggest that the vestibular system may make a unique contribution to the concept of self through the information regarding self-motion and self-location that it transmits, albeit indirectly, to areas of the brain such as the temporo-parietal junction.

  10. A vestibular phenotype for Waardenburg syndrome?

    Science.gov (United States)

    Black, F. O.; Pesznecker, S. C.; Allen, K.; Gianna, C.

    2001-01-01

    OBJECTIVE: To investigate vestibular abnormalities in subjects with Waardenburg syndrome. STUDY DESIGN: Retrospective record review. SETTING: Tertiary referral neurotology clinic. SUBJECTS: Twenty-two adult white subjects with clinical diagnosis of Waardenburg syndrome (10 type I and 12 type II). INTERVENTIONS: Evaluation for Waardenburg phenotype, history of vestibular and auditory symptoms, tests of vestibular and auditory function. MAIN OUTCOME MEASURES: Results of phenotyping, results of vestibular and auditory symptom review (history), results of vestibular and auditory function testing. RESULTS: Seventeen subjects were women, and 5 were men. Their ages ranged from 21 to 58 years (mean, 38 years). Sixteen of the 22 subjects sought treatment for vertigo, dizziness, or imbalance. For subjects with vestibular symptoms, the results of vestibuloocular tests (calorics, vestibular autorotation, and/or pseudorandom rotation) were abnormal in 77%, and the results of vestibulospinal function tests (computerized dynamic posturography, EquiTest) were abnormal in 57%, but there were no specific patterns of abnormality. Six had objective sensorineural hearing loss. Thirteen had an elevated summating/action potential (>0.40) on electrocochleography. All subjects except those with severe hearing loss (n = 3) had normal auditory brainstem response results. CONCLUSION: Patients with Waardenburg syndrome may experience primarily vestibular symptoms without hearing loss. Electrocochleography and vestibular function tests appear to be the most sensitive measures of otologic abnormalities in such patients.

  11. Epidemiology and natural history of vestibular schwannomas

    DEFF Research Database (Denmark)

    Stangerup, Sven-Eric; Caye-Thomasen, Per

    2012-01-01

    This article describes various epidemiologic trends for vestibular schwannomas over the last 35 years, including a brief note on terminology. Additionally, it provides information on the natural history of tumor growth and hearing level following the diagnosis of a vestibular schwannoma. A treatm......This article describes various epidemiologic trends for vestibular schwannomas over the last 35 years, including a brief note on terminology. Additionally, it provides information on the natural history of tumor growth and hearing level following the diagnosis of a vestibular schwannoma...

  12. Galvanic cell for processing of used nuclear fuel

    Science.gov (United States)

    Garcia-Diaz, Brenda L.; Martinez-Rodriguez, Michael J.; Gray, Joshua R.; Olson, Luke C.

    2017-02-07

    A galvanic cell and methods of using the galvanic cell is described for the recovery of uranium from used nuclear fuel according to an electrofluorination process. The galvanic cell requires no input energy and can utilize relatively benign gaseous fluorinating agents. Uranium can be recovered from used nuclear fuel in the form of gaseous uranium compound such as uranium hexafluoride, which can then be converted to metallic uranium or UO.sub.2 and processed according to known methodology to form a useful product, e.g., fuel pellets for use in a commercial energy production system.

  13. About neutralization of the toxic waste of galvanic production

    International Nuclear Information System (INIS)

    Akhmetzhanova, Z.Kh.; Samatov, I.B.

    1996-01-01

    The nature of heavy metals ions migration to environment from the galvanic production is considered in the article. The method of toxic precipitations transformation to non-toxic ones is proposed. The essence of stabilization method of heavy metals hydroxides precipitations consists in transformation of galvanic precipitations mixture to same metals ferrites mixture. The reaction has followed in oxygen medium under heating of galvanic precipitations from 70 up 90 deg C. Before heating the precipitation have acid medium, after temperature treatment the medium turn to the neutral one. These compounds are presented as ferrite class and can be serve as base for various pigments. (author)

  14. Personal reflections on a galvanizing trail.

    Science.gov (United States)

    O'Dell, B L

    1998-01-01

    This article encompasses my perception of, and experience in, an exciting segment of the trace element era in nutrition research: the role of zinc in the nutrition of animals and humans. Zinc has been a major player on the stage of trace element research, and it has left a trail that galvanized the attention of many researchers, including myself. It is ubiquitous in biological systems, and it plays a multitude of physiologic and biochemical functions. A brief historical overview is followed by a discussion of the contributions the work done in my laboratory has made toward understanding the physiological and biochemical functions of zinc. The effort of 40 years has led to the belief that one of zinc's major roles, and perhaps its first limiting role, is to preserve plasma-membrane function as regards ion channels and signal transduction. Although substantial knowledge has been gained relating to the importance of zinc in nutrition, much remains to be discovered.

  15. Adaptive Feedforward Cancellation of Sinusoidal Disturbances in Superconducting RF Cavities

    CERN Document Server

    Kandil, T H; Hartung, W; Khalil, H; Popielarski, J; Vincent, J; York, R C

    2004-01-01

    A control method, known as adaptive feedforward cancellation (AFC) is applied to damp sinusoidal disturbances due to microphonics in superconducting RF (SRF) cavities. AFC provides a method for damping internal, and external sinusoidal disturbances with known frequencies. It is preferred over other schemes because it uses rudimentary information about the frequency response at the disturbance frequencies, without the necessity of knowing an analytic model (transfer function) of the system. It estimates the magnitude and phase of the sinusoidal disturbance inputs and generates a control signal to cancel their effect. AFC, along with a frequency estimation process, is shown to be very successful in the cancellation of sinusoidal signals from different sources. The results of this research may significantly reduce the power requirements and increase the stability for lightly loaded continuous-wave SRF systems.

  16. Asymptotic Theory of the Least Squares Estimators of Sinusoidal Signal

    National Research Council Canada - National Science Library

    Kundu, Debasis

    1997-01-01

    ... normality are derived for the sinusoidal signal under the assumption of normal error (Kundu; 1993) and under the assumptions of independent and identically distributed random variables in Kundu and Mitra...

  17. Converter for Measurement of non-sinusoidal current peak value

    DEFF Research Database (Denmark)

    Butvin, P.; Nielsen, Otto V; Brauer, Peter

    1997-01-01

    A linear-response toroid with core wound of rapidly quenched soft magnetic metallic ribbon and fitted with two windings is used to enable correct measurement of mean peak value of non-sinusoidal and not noise-free alternating current.......A linear-response toroid with core wound of rapidly quenched soft magnetic metallic ribbon and fitted with two windings is used to enable correct measurement of mean peak value of non-sinusoidal and not noise-free alternating current....

  18. [Effectiveness of Self-efficacy Promoting Vestibular Rehabilitation Program for Patients with Vestibular Hypofunction].

    Science.gov (United States)

    Lee, Hyun Jung; Choi-Kwon, Smi

    2016-10-01

    In this study an examination was done of the effect of self-efficacy promoting vestibular rehabilitation (S-VR) on dizziness, exercise selfefficacy, adherence to vestibular rehabilitation (VR), subjective and objective vestibular function, vestibular compensation and the recurrence of dizziness in patients with vestibular hypofunction. This was a randomized controlled study. Data were collected 3 times at baseline, 4 and 8 weeks after beginning the intervention. Outcome measures were level of dizziness, exercise self-efficacy, and level of adherence to VR. Subjective and objective vestibular function, vestibular compensation and the recurrence of dizziness were also obtained. Data were analyzed using Windows SPSS 21.0 program. After 4 weeks of S-VR, there was no difference between the groups for dizziness, subjective and objective vestibular functions. However, exercise self-efficacy and adherence to VR were higher in the experimental group than in the control group. After 8 weeks of S-VR, dizziness (p=.018) exercise self-efficacy (pexercise self-efficacy, subjective vestibular function and adherence to VR. Objective vestibular function and vestibular compensation were also improved in the experimental group at the end of 8 weeks of S-VR.

  19. 76 FR 19382 - Galvanized Steel Wire From China and Mexico

    Science.gov (United States)

    2011-04-07

    ... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-479 and 731-TA-1183-1184 (Preliminary)] Galvanized Steel Wire From China and Mexico AGENCY: United States International Trade Commission. ACTION... the United States is materially retarded, by reason of [[Page 19383

  20. Cerebellar nodulectomy impairs spatial memory of vestibular and optokinetic stimulation in rabbits.

    Science.gov (United States)

    Barmack, N H; Errico, P; Ferraresi, A; Fushiki, H; Pettorossi, V E; Yakhnitsa, V

    2002-02-01

    Natural vestibular and optokinetic stimulation were used to investigate the possible role of the cerebellar nodulus in the regulation and modification of reflexive eye movements in rabbits. The nodulus and folium 9d of the uvula were destroyed by surgical aspiration. Before and after nodulectomy the vertical and horizontal vestibuloocular reflexes (VVOR, HVOR) were measured during sinusoidal vestibular stimulation about the longitudinal (roll) and vertical (yaw) axes. Although the gain of the HVOR (G(HVOR) = peak eye movement velocity/peak head velocity) was not affected by the nodulectomy, the gain of the VVOR (G(VVOR)) was reduced. The gains of the vertical and horizontal optokinetic reflexes (G(VOKR), G(HOKR)) were measured during monocular, sinusoidal optokinetic stimulation (OKS) about the longitudinal and vertical axes. Following nodulectomy, there was no reduction in G(VOKR) or G(HOKR). Long-term binocular OKS was used to generate optokinetic afternystagmus, OKAN II, that lasts for hours. After OKAN II was induced, rabbits were subjected to static pitch and roll, to determine how the plane and velocity of OKAN II is influenced by a changing vestibular environment. During static pitch, OKAN II slow phase remained aligned with earth-horizontal. This was true for normal and nodulectomized rabbits. During static roll, OKAN II remained aligned with earth-horizontal in normal rabbits. During static roll in nodulectomized rabbits, OKAN II slow phase developed a centripetal vertical drift. We examined the suppression and recovery of G(VVOR) following exposure to conflicting vertical OKS for 10-30 min. This vestibular-optokinetic conflict reduced G(VVOR) in both normal and nodulectomized rabbits. The time course of recovery of G(VVOR) after conflicting OKS was the same before and after nodulectomy. In normal rabbits, the head pitch angle, at which peak OKAN II velocity occurred, corresponded to the head pitch angle maintained during long-term OKS. If the head was

  1. Cold laminar galvanizing: a new anti-corrosion concept

    International Nuclear Information System (INIS)

    Bagnulo, L.H.

    1984-01-01

    Cold laminar galvanizing, a recent anticorrosion technology, now combines the most positive characteristics of the hot galvanizing protective systems. This patented technology has a zinc laminated foil (obtained by processing 99.9% pure zinc ingots) that is homogeneous and isotropic, with a standard thickness of 80-100μm. This foil is backed with an electro-conductive, selfadhesive glue prepared under an original formula. The zinc laminated foil offers excellent anchorage and elevated resistance to the main atmospheric agents

  2. 76 FR 68422 - Galvanized Steel Wire From Mexico: Preliminary Determination of Sales at Less Than Fair Value and...

    Science.gov (United States)

    2011-11-04

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-201-840] Galvanized Steel Wire From... determines that galvanized steel wire (galvanized wire) from Mexico is being, or is likely to be, sold in the... investigation on galvanized wire from Mexico. See Galvanized Steel Wire from the People's Republic of China and...

  3. [Threefold intraoperative electrophysiological monitoring of vestibular neurectomy].

    Science.gov (United States)

    Hausler, R; Kasper, A

    1991-01-01

    A threefold intraoperative monitoring of facial nerve, auditory nerve and vestibular nerve function was performed in 14 cases of retrosigmoidal neurectomy. The facial nerve was monitoring with a pressure transducer placed against the cheek (Opalarm system). The auditory nerve was monitored with acoustically (click) evoked early potentials and the vestibular nerve was monitored with electrically evoked vestibular potentials obtained by direct stimulation (biphasic current pulses of 0.75-mA p-p, 100 us, 20/s) of the exposed vestibular nerve in the cerebellopontine angle before, during and after neurectomy. A characteristic vertex negative peak having a latency of approximately 2 ms and approximately 0.5 uV amplitude was obtained between a forehead and an ipsilateral ear lobe electrode (2 x 1,000 averaged responses over 10 ms) before the neurectomy. This response disappeared after selective vestibular nerve section proximal to the stimulation site. A diminished response amplitude was measured after incomplete nerve section. Simultaneous acoustic masking had no influence on the vestibular potential. The 14 operated patients became all free of vertiginous spells and drop-attacks except one patient who developed a contralateral Menière's. Facial nerve function remained normal in all. Hearing preservation was obtained in 12 patients (86%). The threefold intraoperative monitoring has turned out to be an additional safety factor for facial and auditory nerve preservation and, thanks to the recording of vestibular potentials, it increased the efficiency of vestibular neurectomy.

  4. Vestibular Function and Activities of Daily Living

    Directory of Open Access Journals (Sweden)

    Aisha Harun MD

    2015-09-01

    Full Text Available Objective: Vestibular dysfunction increases with age and is associated with mobility difficulties and fall risk in older individuals. We evaluated whether vestibular function influences the ability to perform activities of daily living (ADLs. Method: We analyzed the 1999 to 2004 National Health and Nutrition Examination Survey of adults aged older than 40 years ( N = 5,017. Vestibular function was assessed with the Modified Romberg test. We evaluated the association between vestibular function and difficulty level in performing specific basic and instrumental ADLs, and total number of ADL impairments. Results: Vestibular dysfunction was associated with significantly higher odds of difficulty with nine ADLs, most strongly with difficulty managing finances (odds ratio [ OR ] = 2.64, 95% confidence interval [CI] = [1.18, 5.90]. In addition, vestibular dysfunction was associated with a significantly greater number of ADL impairments (β = .21, 95% CI = [0.09, 0.33]. This effect size was comparable with the influence of heavy smoking (β = .21, 95% CI = [0.06, 0.36] and hypertension (β = .10, 95% CI = [0.02, 0.18] on the number of ADL impairments. Conclusion: Vestibular dysfunction significantly influences ADL difficulty, most strongly with a cognitive rather than mobility-based task. These findings underscore the importance of vestibular inputs for both cognitive and physical daily activities.

  5. Improving Sensorimotor Adaptation Following Long Duration Space Flight by Enhancing Vestibular Information Transfer

    Science.gov (United States)

    Mulavara, A. P.; Kofman, I. S.; De Dios, Y. E; Galvan, R.; Goel, R.; Miller, C.; Peters, B.; Cohen, H. S.; Jeevarajan, J.; Reschke, M.; hide

    2014-01-01

    performance in both ML and anteroposterior planes while stimulating in the ML axis only. We have shown the efficacy of VSR stimulations on enhancing physiological and perceptual responses of whole-body orientation during low frequency perturbations (0.1 Hz) on the ocular motor system using a variable radius centrifuge on both physiological (using eye movements) and perceptual responses (using a joystick) to track imposed oscillations. The variable radius centrifuge provides a selective tilting sensation that is detectable only by the otolith organs providing conflicting information from the canal organs of the vestibular system (intra-vestibular conflict). These results indicate that VSR can improve performance in sensory conflict scenarios like that experienced during space flight. We have showed the efficacy of VSR stimulation to improve balance and locomotor control on subjects exposed to continuous, sinusoidal lateral motion of the support surface while walking on a treadmill while viewing perceptually matched linear optic flow. We have shown the safety of short term continuous use of up to 4 hours of VSR stimulation and its efficacy in improving balance and locomotor function in Parkinson's Disease patients. This technique for improving vestibular signal detection may thus provide additional information to improve strategic abilities. We hypothesize that VSR stimulation will act synergistically with SA training to improve adaptability by increased utilization of vestibular information and therefore serve to optimize and personalize the SA countermeasure prescription. This forms the basis of its usefulness both as a training modality and further help in significantly reducing the number of days required to recover functional performance to preflight levels after long duration space flight.

  6. Failure analysis of edge discoloration of galvanized fuel tank

    Directory of Open Access Journals (Sweden)

    Jitendra Mathur

    2015-10-01

    Full Text Available A peculiar type of edge discoloration defect on the surface of some galvanized fuel tank was observed, causing significant appearance problems. In the present study, the surface defect was characterized by visual inspection, optical microscopy, scanning electron microscopy and energy dispersive spectroscopic analysis to understand the source and mechanism of the defect. In the visual inspection, these peculiar surface appearances were observed in fuel tank at three distinct locations. The SEM examination exhibited two distinct regions on the surface apart from the normal galvanized surface: (1 galvannealed, (2 mixture of galvanized and galvannealed texture. The energy dispersive spectroscopic analysis of galvannealed region indicated enrichment of Zn and Al whereas in the region of galvanized majorly Zn was observed. Surface texture of galvannealed region showed majorly zeta crystals along with skin pass marks; whereas no such zeta crystals were observed in case of galvanized regions. Based on the preliminary results, the following hypothesis was made: Coil processed during galvanizing to galvannealing transition. Thickness and width changed to wider and thicker section, which resulted into lower line speed. Due to the lower Al content, lower speed and thicker section combination resulted in formation of partial GA in the coil owing to the internal heat content of the coil. This paper presents the results of the investigation.

  7. Effects of vibrotactile vestibular substitution on vestibular rehabilitation - preliminary study,

    Directory of Open Access Journals (Sweden)

    Cibele Brugnera

    2015-12-01

    Full Text Available ABSTRACT INTRODUCTION: Some patients with severe impairment of body balance do not obtain adequate improvement from vestibular rehabilitation (VR. OBJECTIVE: To evaluate the effectiveness of Vertiguard(tm biofeedback equipment as a sensory substitution (SS of the vestibular system in patients who did not obtain sufficient improvement from VR. METHODS: This was a randomized prospective clinical study. Thirteen patients without satisfactory response to conventional VR were randomized into a study group (SG, which received the vibrotactile stimulus from Vertiguard(tm for ten days, and a control group (CG, which used equipment without the stimulus. For pre- and post-treatment assessment, the Sensory Organization Test (SOT protocol of the Computerized Dynamic Posturography (CDP and two scales of balance self-perception, Activities-specific Balance Confidence (ABC and Dizziness Handicap Inventory (DHI, were used. RESULTS: After treatment, only the SG showed statistically significant improvement in C5 (p = 0.007 and C6 (p = 0.01. On the ABC scale, there was a significant difference in the SG (p= 0.04. The DHI showed a significant difference in CG and SG with regard to the physical aspect, and only in the SG for the functional aspect (p = 0.04. CONCLUSION: The present findings show that sensory substitution using the vibrotactile stimulus of the Vertiguard(tm system helped with the integration of neural networks involved in maintaining posture, improving the strategies used in the recovery of body balance.

  8. Vapour galvanizing (Sherardizing) of copper with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wortelen, Dietbert; Bracht, Hartmut [Westfaelische Wilhelms-Universitaet Muenster (Germany); Natrup, Frank; Graf, Wolfram [Bodycote Waermebehandlung GmbH, Sprockhoevel (Germany)

    2010-07-01

    Using a vapour galvanizing technique called Sherardizing we investigated the growth kinetics and coefficients of zinc copper phases. For this purpose polished (OFHC)-copper plates and zinc powder have been sealed in quartz ampoules under inert gas atmospheres and annealed at a temperature range between 300 and 410 C. In order to study the coating thickness and the phase composition, cross sections were prepared, which have been analyzed by means of optical microscopy and scanning electron microscopy. We were able to demonstrate that the coating thickness is a function of the parabolic time law and that the formed coatings are composed of two layers referring to the ordered {beta}-CuZn and {gamma}-Cu{sub 5}Zn{sub 8}-phases. To enhance the coating quality, small amounts of ZnCl{sub 2} were added to the zinc powder. It was observed that the coating thickness decreased with increasing ZnCl{sub 2}. Experiments with variable Ar-pressure demonstrated a reduced coating growth with increasing pressures. Further measurements with ZnCl{sub 2} were performed to check whether an electrochemical mechanism is involved in the coating process.

  9. Passive Resonant Bidirectional Converter with Galvanic Barrier

    Science.gov (United States)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  10. Acute Bilateral Superior Branch Vestibular Neuropathy

    Directory of Open Access Journals (Sweden)

    Dario A. Yacovino

    2018-05-01

    Full Text Available The rapid onset of a bilateral vestibular hypofunction (BVH is often attributed to vestibular ototoxicity. However, without any prior exposure to ototoxins, the idiopathic form of BVH is most common. Although sequential bilateral vestibular neuritis (VN is described as a cause of BVH, clinical evidence for simultaneous and acute onset bilateral VN is unknown. We describe a patient with an acute onset of severe gait ataxia and oscillopsia with features compatible with acute BVH putatively due to a bilateral VN, which we serially evaluated with clinical and laboratory vestibular function testing over the course of 1 year. Initially, bilateral superior and horizontal semicircular canals and bilateral utricles were impaired, consistent with damage to both superior branches of each vestibular nerve. Hearing was spared. Only modest results were obtained following 6 months of vestibular rehabilitation. At a 1-year follow-up, only the utricular function of one side recovered. This case is the first evidence supporting an acute presentation of bilateral VN as a cause for BVH, which would not have been observed without critical assessment of each of the 10 vestibular end organs.

  11. Bottomside sinusoidal irregularities in the equatorial F region

    Science.gov (United States)

    Valladares, C. E.; Hanson, W. B.; Mcclure, J. P.; Cragin, B. L.

    1983-01-01

    By using the Ogo 6 satellite, McClure and Hanson (1973) have discovered sinusoidal irregularities in the equatorial F region ion number density. In the present investigation, a description is provided of the properties of a distinct category of sinusoidal irregularities found in equatorial data from the AE-C and AE-E satellites. The observed scale sizes vary from about 300 m to 3 km in the direction perpendicular to B, overlapping with and extending the range observed by using Ogo 6. Attention is given to low and high resolution data, a comparison with Huancayo ionograms, the confinement of 'bottomside sinusoidal' (BSS) irregularities essentially to the bottomside of the F layer, spectral characteristics, and BSS, scintillation, and ionosonde observations.

  12. Preservation of vestibular function after scala vestibuli cochlear implantation.

    Science.gov (United States)

    Suzuki, Mitsuya; Goto, Takio; Kashio, Akinori; Yasui, Takuya; Sakamoto, Takashi; Ito, Ken; Yamasoba, Tatsuya

    2011-10-01

    A 58-year-old man, in whom the cochlear implant (CI) had been inserted into the left ear, had right middle-ear cancer. The CI was removed immediately before receiving subtotal removal of right temporal bone. Four months later, the CI was again inserted in his left cochlea. Because of obliterated scala tympani, the 22 active electrodes of the CI were placed into the scala vestibuli. After the surgery, the patient complained that he experienced rotary vertigo and "jumbling of vertical direction" of objects on walking. Using rotation test, we evaluated vestibular function of remaining left ear. Numerous horizontal nystagmus beats were induced during earth-vertical axis rotation, whereas vertical downbeat nystagmus was scarcely induced during off-vertical axis rotation. The horizontal vestibulo-ocular reflex (VOR) was almost normally induced by sinusoidal stimulation at 0.8Hz. These data suggest that the scala vestibuli insertion of CI would be not so invasive against the lateral semicircular canal. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Aging of the Human Vestibular System

    Science.gov (United States)

    Zalewski, Christopher K.

    2015-01-01

    Aging affects every sensory system in the body, including the vestibular system. Although its impact is often difficult to quantify, the deleterious impact of aging on the vestibular system is serious both medically and economically. The deterioration of the vestibular sensory end organs has been known since the 1970s; however, the measurable impact from these anatomical changes remains elusive. Tests of vestibular function either fall short in their ability to quantify such anatomical deterioration, or they are insensitive to the associated physiologic decline and/or central compensatory mechanisms that accompany the vestibular aging process. When compared with healthy younger individuals, a paucity of subtle differences in test results has been reported in the healthy older population, and those differences are often observed only in response to nontraditional and/or more robust stimuli. In addition, the reported differences are often clinically insignificant insomuch that the recorded physiologic responses from the elderly often fall within the wide normative response ranges identified for normal healthy adults. The damaging economic impact of such vestibular sensory decline manifests itself in an exponential increase in geriatric dizziness and a subsequent higher prevalence of injurious falls. An estimated $10 to $20 billion dollar annual cost has been reported to be associated with falls-related injuries and is the sixth leading cause of death in the elderly population, with a 20% mortality rate. With an estimated 115% increase in the geriatric population over 65 years of age by the year 2050, the number of balanced-disordered patients with a declining vestibular system is certain to reach near epidemic proportions. An understanding of the effects of age on the vestibular system is imperative if clinicians are to better manage elderly patients with balance disorders, dizziness, and vestibular disease. PMID:27516717

  14. Progress Toward Development of a Multichannel Vestibular Prosthesis for Treatment of Bilateral Vestibular Deficiency

    Science.gov (United States)

    FRIDMAN, GENE Y.; DELLA SANTINA, CHARLES C.

    2014-01-01

    This article reviews vestibular pathology and the requirements and progress made in the design and construction of a vestibular prosthesis. Bilateral loss of vestibular sensation is disabling. When vestibular hair cells are injured by ototoxic medications or other insults to the labyrinth, the resulting loss of sensory input disrupts vestibulo-ocular reflexes (VORs) and vestibulo-spinal reflexes that normally stabilize the eyes and body. Affected individuals suffer poor vision during head movement, postural instability, chronic disequilibrium, and cognitive distraction. Although most individuals with residual sensation compensate for their loss over time, others fail to do so and have no adequate treatment options. A vestibular prosthesis analogous to cochlear implants but designed to modulate vestibular nerve activity during head movement should improve quality of life for these chronically dizzy individuals. We describe the impact of bilateral loss of vestibular sensation, animal studies supporting feasibility of prosthetic vestibular stimulation, the current status of multichannel vestibular sensory replacement prosthesis development, and challenges to successfully realizing this approach in clinical practice. In bilaterally vestibular-deficient rodents and rhesus monkeys, the Johns Hopkins multichannel vestibular prosthesis (MVP) partially restores the three-dimensional (3D) VOR for head rotations about any axis. Attempts at prosthetic vestibular stimulation of humans have not yet included the 3D eye movement assays necessary to accurately evaluate VOR alignment, but these initial forays have revealed responses that are otherwise comparable to observations in animals. Current efforts now focus on refining electrode design and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimizing stimulus protocols to improve dynamic range and reduce excitation–inhibition asymmetry, and adapting laboratory MVP prototypes into devices

  15. Progress toward development of a multichannel vestibular prosthesis for treatment of bilateral vestibular deficiency.

    Science.gov (United States)

    Fridman, Gene Y; Della Santina, Charles C

    2012-11-01

    This article reviews vestibular pathology and the requirements and progress made in the design and construction of a vestibular prosthesis. Bilateral loss of vestibular sensation is disabling. When vestibular hair cells are injured by ototoxic medications or other insults to the labyrinth, the resulting loss of sensory input disrupts vestibulo-ocular reflexes (VORs) and vestibulo-spinal reflexes that normally stabilize the eyes and body. Affected individuals suffer poor vision during head movement, postural instability, chronic disequilibrium, and cognitive distraction. Although most individuals with residual sensation compensate for their loss over time, others fail to do so and have no adequate treatment options. A vestibular prosthesis analogous to cochlear implants but designed to modulate vestibular nerve activity during head movement should improve quality of life for these chronically dizzy individuals. We describe the impact of bilateral loss of vestibular sensation, animal studies supporting feasibility of prosthetic vestibular stimulation, the current status of multichannel vestibular sensory replacement prosthesis development, and challenges to successfully realizing this approach in clinical practice. In bilaterally vestibular-deficient rodents and rhesus monkeys, the Johns Hopkins multichannel vestibular prosthesis (MVP) partially restores the three-dimensional (3D) VOR for head rotations about any axis. Attempts at prosthetic vestibular stimulation of humans have not yet included the 3D eye movement assays necessary to accurately evaluate VOR alignment, but these initial forays have revealed responses that are otherwise comparable to observations in animals. Current efforts now focus on refining electrode design and surgical technique to enhance stimulus selectivity and preserve cochlear function, optimizing stimulus protocols to improve dynamic range and reduce excitation-inhibition asymmetry, and adapting laboratory MVP prototypes into devices

  16. Some New Results on the Estimation of Sinusoids in Noise

    DEFF Research Database (Denmark)

    Nielsen, Jesper Kjær

    2012-01-01

    This thesis is concerned with the problem of estimating sinusoidal parameters from noisy observations. This field of research is applicable to solving problems in a large number of areas such as music and speech processing, electrocardiography, seismology, radar and sonar processing, astronomy....... Third, an efficient algorithm for performing inference and interpolation in a dynamic sinusoidal model is proposed. This method is applied to packet-loss concealment, and listening tests indicate that the proposed algorithm can be used for this purpose. Fourth, the Capon filtering method for amplitude...

  17. CNNs for sinusoidal signal recognition in hearing rehabilitation

    Science.gov (United States)

    Carnimeo, Leonarda; Giaquinto, Antonio

    2003-04-01

    In this paper, a contribution is given to provide a tool to the recognition of sinusoidal signals with a particular reference to the field of pediatric hearing rehabilitation. To this purpose, a synthesis technique previously developed by the authors' is used to design a Cellular Neural Network for an Associative Memory able to compare submitted discrete-time sinusoidal signals with memorized ones. A robustness analysis of the synthesized associative memory is also developed both for noisy inputs and for parameter variations. Simulation results are then reported to illustrate the performances of the designed network.

  18. Can Electrical Vestibular Noise Be Used for the Treatment of Brain Diseases?

    Science.gov (United States)

    Yamamoto, Yoshiharu; Soma, Rika; Struzik, Zbigniew R.; Kwak, Shin

    2005-11-01

    The therapy currently available for the treatment of degenerative neurological diseases is far from satisfactory, and a novel therapeutic strategy, especially for pharmacologically unresponsive patients, would be welcomed. The vestibular nerves are known to influence neuronal circuits in the medullary cardiovascular areas and, through the cerebellar vermis, the basal ganglia and the limbic system. By means of noisy galvanic vestibular stimulation (GVS), it may now be possible to ameliorate blunted responsiveness of degenerated neuronal circuits in the brains of multiple system atrophy (MSA) and/or Parkinson's disease (PD) patients, through a mechanism known as stochastic resonance. We evaluate the effect of 24-hour noisy GVS on long-term heart rate dynamics in seven MSA patients, and on daytime locomotor activity dynamics in twelve patients with either PD or levodopa unresponsive parkinsonism. Short-range heart rate variability and long-range anti-correlation of trunk activity are significantly increased by the noisy GVS compared with sham stimulation, suggestive of improved autonomic and motor responsiveness. The noisy GVS is effective in boosting the neuro-degenerative brains of MSA and/or PD patients, including those unresponsive to standard levodopa therapy.

  19. Laboratory studies of galvanic corrosion. I. Two-metal couples

    International Nuclear Information System (INIS)

    Mansfeld, F.; Kenkel, J.V.

    1975-01-01

    Galvanic interaction of stainless steel 304L, Ni 270, Cu, Ti--6Al--4V, Sn, 4130 steel, Cd, and Zn has been studied in 3.5 percent NaCl using galvanic current and weight loss measurements in 24-hour tests. Galvanic couples of 4130 steel and one of the Al alloys 1100, 2024, 2219, 6061, and 7075 have also been evaluated in tap water and distilled water. Galvanic current data can be used to assess both the effect of different dissimilar cathode materials as well as the relative susceptibility to galvanic corrosion of anode materials. For 3.5 percent NaCl, it has been found that the effect of the cathode material decreases in the order Cu greater than Ni greater than stainless steel greater than Ti--6Al--4V, while the relative susceptibility of anode materials decreases in the order Sn greater than Zn greater than 4130 steel greater than Cd. An analysis of data in various electrolytes shows that coupling of 4130 steel to Al alloys leads to cathodic protection of the steel in 3.5 percent NaCl, but to accelerated corrosion in tap water and distilled water. (U.S.)

  20. Vestibular Restoration and Adaptation in Vestibular Neuritis and Ramsay Hunt Syndrome With Vertigo.

    Science.gov (United States)

    Martin-Sanz, Eduardo; Rueda, Almudena; Esteban-Sanchez, Jonathan; Yanes, Joaquin; Rey-Martinez, Jorge; Sanz-Fernandez, Ricardo

    2017-08-01

    To evaluate vestibular restoration and the evolution of the compensatory saccades in acute severe inflammatory vestibular nerve paralysis, including vestibular neuritis and Ramsay Hunt syndrome with vertigo. Prospective. Tertiary referral center. Vestibular neuritis (n = 18) and Ramsay Hunt syndrome patients with vertigo (n = 13) were enrolled. After treatment with oral corticosteroids, patients were followed up for 6 months. Functional recovery of the facial nerve was scored according to the House-Brackman grading system. Caloric and video head impulse tests were performed in every patient at the time of enrolment. Subsequently, successive video head impulse test (vHIT) exploration was performed at the 1, 3, and 6-month follow-up. Eighteen patients with vestibular neuritis and 13 with Ramsay Hunt syndrome and associated vertigo were included. Vestibular function was significantly worse in patients with Ramsay Hunt syndrome than in those with vestibular neuritis. Similar compensatory saccades velocity and latency values were observed in both groups, in both the caloric and initial vHIT tests. Successive vHIT results showed a significantly higher vestibulo-ocular reflex gain recovery in vestibular neuritis patients than in Ramsay Hunt syndrome patients. A significantly faster reduction in the latency, velocity, and organization of the compensatory saccades was observed in neuritis than in Ramsay Hunt syndrome patients. In addition to the recovery of the vestibulo-ocular reflex, the reduction of latency, velocity and the organization of compensatory saccades play a role in vestibular compensation.

  1. Cross-axis adaptation improves 3D vestibulo-ocular reflex alignment during chronic stimulation via a head-mounted multichannel vestibular prosthesis

    Science.gov (United States)

    Dai, Chenkai; Fridman, Gene Y.; Chiang, Bryce; Davidovics, Natan; Melvin, Thuy-Anh; Cullen, Kathleen E.; Della Santina, Charles C.

    2012-01-01

    By sensing three-dimensional (3D) head rotation and electrically stimulating the three ampullary branches of a vestibular nerve to encode head angular velocity, a multichannel vestibular prosthesis (MVP) can restore vestibular sensation to individuals disabled by loss of vestibular hair cell function. However, current spread to afferent fibers innervating non-targeted canals and otolith endorgans can distort the vestibular nerve activation pattern, causing misalignment between the perceived and actual axis of head rotation. We hypothesized that over time, central neural mechanisms can adapt to correct this misalignment. To test this, we rendered five chinchillas vestibular-deficient via bilateral gentamicin treatment and unilaterally implanted them with a head mounted MVP. Comparison of 3D angular vestibulo-ocular reflex (aVOR) responses during 2 Hz, 50°/s peak horizontal sinusoidal head rotations in darkness on the first, third and seventh days of continual MVP use revealed that eye responses about the intended axis remained stable (at about 70% of the normal gain) while misalignment improved significantly by the end of one week of prosthetic stimulation. A comparable time course of improvement was also observed for head rotations about the other two semicircular canal axes and at every stimulus frequency examined (0.2–5 Hz). In addition, the extent of disconjugacy between the two eyes progressively improved during the same time window. These results indicate that the central nervous system rapidly adapts to multichannel prosthetic vestibular stimulation to markedly improve 3D aVOR alignment within the first week after activation. Similar adaptive improvements are likely to occur in other species, including humans. PMID:21374081

  2. A microfluidic galvanic cell on a single layer of paper

    Science.gov (United States)

    Purohit, Krutarth H.; Emrani, Saina; Rodriguez, Sandra; Liaw, Shi-Shen; Pham, Linda; Galvan, Vicente; Domalaon, Kryls; Gomez, Frank A.; Haan, John L.

    2016-06-01

    Paper microfluidics is used to produce single layer galvanic and hybrid cells to produce energy that could power paper-based analytical sensors. When two aqueous streams are absorbed onto paper to establish co-laminar flow, the streams stay in contact with each other with limited mixing. The interface at which mixing occurs acts as a charge-transfer region, eliminating the need for a salt bridge. We designed a Cusbnd Zn galvanic cell that powers an LED when two are placed in series. We also used more powerful redox couples (formate and silver, formate and permanganate) to produce higher power density (18 and 3.1 mW mg-1 Pd). These power densities are greater than previously reported paper microfluidic fuel cells using formate or methanol. The single layer design is much more simplified than previous reports of multi-layer galvanic cells on paper.

  3. DEPOSITION OF NICKEL ON CARBON FIBRES BY GALVANIC METHOD

    Directory of Open Access Journals (Sweden)

    Pavol Štefánik

    2012-01-01

    Full Text Available The investigation of coating parameters in quasi-static coating of Ni layer on carbon fibre tow by galvanic method is presented. The tow of fibres was immersed in typical galvanic bath based on NiSO4, NiCl2, Na2SO4 and H3BO3 and current to carbon fibres was supplied by two leading metal rolls which are parts of continuous coating apparatus. The main parameters were current of 1 A, electrolyte temperature of 50 °C and the distance from power contacts to level of galvanic bath (8 or 13 cm. The amount and structure of deposited Ni layer at coating time 15 and 90 seconds of exposure in electrolyte and depth of immersion of tow into bath were discussed.

  4. Performance of Inductors Attached to a Galvanizing Bath

    Science.gov (United States)

    Zhou, Xinping; Yuan, Shuo; Liu, Chi; Yang, Peng; Qian, Chaoqun; Song, Bao

    2013-12-01

    By taking a galvanizing bath with inductors from an Iron and Steel Co., Ltd as an example, the distributions of Lorentz force and generated heat in the inductor are simulated. As a result, the zinc flow and the temperature distribution driven by the Lorentz force and the generated heat in the inductor of a galvanizing bath are simulated numerically, and their characteristics are analyzed. The relationship of the surface-weighted average velocity at the outlet and the temperature difference between the inlet and the outlet and the effective power for the inductor is studied. Results show that with an increase in effective power for the inductor, the surface-weighted average velocity at the outlet and the temperature difference between the inlet and the outlet increase gradually. We envisage this work to lay a foundation for the study of the performance of the galvanizing bath in future.

  5. Opto-galvanic effect on degenerate magnetic states of sputtered atoms in a glow discharge

    International Nuclear Information System (INIS)

    Zhechev, D; Steflekova, V

    2014-01-01

    The opto-galvanic response of some degenerate states of sputtered atoms to linearly- and circularly polarize light is studied. On the same optical transition both time-resolved- and amplitude opto-galvanic signals are found depending on the polarizations of light absorbed. The latter induces galvanic responses differing in opto-galvanic efficiency, time-evolution and sensitivity to discharge current and laser power. The differences are ascribed to the rate constants of the decay processes, characterizing aligned and oriented atoms

  6. Trans-sinusoidal maxillary distraction in three cleft patients.

    NARCIS (Netherlands)

    Wenghoefer, M.H.; Martini, M.; Nadjmi, N.; Schutyser, F.A.C.; Jagtman, A.K.; Bergé, S.J.

    2006-01-01

    The trans-sinusoidal maxillary distractor (TS-MD) was used to achieve maxillary advancement in three patients with repaired cleft lip and palate. After preoperative computer-aided planning of the distraction vectors, each TS-MD was bent on a stereolithographic model of the maxilla of the patient.

  7. Sinusoidal velaroidal shell – numerical modelling of the nonlinear ...

    African Journals Online (AJOL)

    The nonlinearity, applied to a sinusoidal velaroidal shell with the inner radius r0, the outer variables radii from 10m to 20m and the number of waves n=8, will give rise to the investigation of its nonlinear buckling resistance. The building material is a high-performant concrete. The investigation emphasizes more on the ...

  8. Optimization for sinusoidal profiles in surface relief gratings ...

    Indian Academy of Sciences (India)

    2014-02-07

    Feb 7, 2014 ... filometry [7–9] and monitoring of surface self-diffusion of solids under ultrahigh vacuum conditions [10]. In the present work, recording parameters, i.e. exposure time and deve- lopment time for fabrication of such holographic gratings have been optimized to obtain nearly perfect sinusoidal profiles in the ...

  9. Evoked responses to sinusoidally modulated sound in unanaesthetized dogs

    NARCIS (Netherlands)

    Tielen, A.M.; Kamp, A.; Lopes da Silva, F.H.; Reneau, J.P.; Storm van Leeuwen, W.

    1. 1. Responses evoked by sinusoidally amplitude-modulated sound in unanaesthetized dogs have been recorded from inferior colliculus and from auditory cortex structures by means of chronically indwelling stainless steel wire electrodes. 2. 2. Harmonic analysis of the average responses demonstrated

  10. Deep-etched sinusoidal polarizing beam splitter grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lv, Peng

    2010-04-01

    A sinusoidal-shaped fused-silica grating as a highly efficient polarizing beam splitter (PBS) is investigated based on the simplified modal method. The grating structure depends mainly on the ratio of groove depth to grating period and the ratio of incident wavelength to grating period. These ratios can be used as a guideline for the grating design at different wavelengths. A sinusoidal-groove PBS grating is designed at a wavelength of 1310 nm under Littrow mounting, and the transmitted TM and TE polarized waves are mainly diffracted into the zeroth order and the -1st order, respectively. The grating profile is optimized by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient (>95.98%) over the O-band wavelength range (1260-1360 nm) for both TE and TM polarizations. The sinusoidal grating can exhibit higher diffraction efficiency, larger extinction ratio, and less reflection loss than the rectangular-groove PBS grating. By applying wet etching technology on the rectangular grating, which was manufactured by holographic recording and inductively coupled plasma etching technology, the sinusoidal grating can be approximately fabricated. Experimental results are in agreement with theoretical values.

  11. Using piecewise sinusoidal basis functions to blanket multiple wire segments

    CSIR Research Space (South Africa)

    Lysko, AA

    2009-06-01

    Full Text Available This paper discusses application of the piecewise sinusoidal (PWS) basis function (BF) over a chain of several wire segments, for example as a multiple domain basis function. The usage of PWS BF is compared to results based on the piecewise linear...

  12. Pelagic behaviour of reservoir fishes: sinusoidal swimming and associated behaviour

    OpenAIRE

    JAROLÍM, Oldřich

    2009-01-01

    Annotation Long-term fixed-location hydroacoustic study with uplooking transducer was performed during 2005 in Římov reservoir, Czech Republic. It dealt mainly with fish behaviour in the open water of reservoir, especially with sinusoidal swimming behaviour. The dependence of pelagic fish behaviour on environmental conditions was also studied.

  13. BPM Offset Determination by Sinusoidal Quadrupole K-modulation

    CERN Document Server

    Baer, T; Wenninger, J

    2011-01-01

    To ensure an adequate orbit steering that maximizes the machine aperture, a good knowledge of the BPM measurement offsets is crucial. During this MD, a sinusoidal k-modulation of individually powered quadrupoles was performed to determine the offsets of the nearby BPMs. An accuracy of 10µm for the determination of the absolute beam position is reached.

  14. 40 CFR 465.20 - Applicability; description of the galvanized basis material subcategory.

    Science.gov (United States)

    2010-07-01

    ... galvanized basis material subcategory. 465.20 Section 465.20 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS COIL COATING POINT SOURCE CATEGORY Galvanized Basis Material Subcategory § 465.20 Applicability; description of the galvanized basis material...

  15. 7 CFR 1755.370 - RUS specification for seven wire galvanized steel strand.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false RUS specification for seven wire galvanized steel..., ACCEPTABLE MATERIALS, AND STANDARD CONTRACT FORMS § 1755.370 RUS specification for seven wire galvanized... Steel Wire Strand, issued May 1978. All seven wire galvanized steel strand purchased after April 1, 1990...

  16. 76 FR 73589 - Galvanized Steel Wire From the People's Republic of China: Amended Preliminary Determination of...

    Science.gov (United States)

    2011-11-29

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-975] Galvanized Steel Wire From... galvanized steel wire from the People's Republic of China (``PRC'').\\1\\ We are amending our Preliminary... Fair Value and Postponement of Final Determination: Galvanized Steel Wire from the People's Republic of...

  17. 76 FR 33242 - Galvanized Steel Wire From the People's Republic of China: Postponement of Preliminary...

    Science.gov (United States)

    2011-06-08

    ... DEPARTMENT OF COMMERCE International Trade Administration [C-570-976] Galvanized Steel Wire From... the countervailing duty investigation of galvanized steel wire from the People's Republic of China. See Galvanized Steel Wire From the People's Republic of China: Initiation of Countervailing Duty...

  18. Hydrogen embrittlement and galvanic corrosion of titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Soh, Jeong Ryong; Jeong, Y. H.; Choi, B. K.; Baek, J. H.; Hwang, D. Y.; Choi, B. S.; Lee, D. J

    2000-06-01

    The material properties including the fracture behavior of titanium alloys used as a steam generator tube in SMART can be degraded de to the hydrogen embrittlement and the galvanic corrosion occurring as a result of other materials in contact with titanium alloys in a conducting corrosive environment. In this report the general concepts and trends of hydrogen embrittlement are qualitatively described to adequately understand and expect the fracture behavior from hydrogen within the bulk of materials and under hydrogen containing environments because hydrogen embrittlement may be very complicated process. And the characteristics of galvanic corrosion closely related to hydrogen embrittlement is qualitatively based on wimple electrochemical theory.

  19. Hydrogen embrittlement and galvanic corrosion of titanium alloys

    International Nuclear Information System (INIS)

    Soh, Jeong Ryong; Jeong, Y. H.; Choi, B. K.; Baek, J. H.; Hwang, D. Y.; Choi, B. S.; Lee, D. J.

    2000-06-01

    The material properties including the fracture behavior of titanium alloys used as a steam generator tube in SMART can be degraded de to the hydrogen embrittlement and the galvanic corrosion occurring as a result of other materials in contact with titanium alloys in a conducting corrosive environment. In this report the general concepts and trends of hydrogen embrittlement are qualitatively described to adequately understand and expect the fracture behavior from hydrogen within the bulk of materials and under hydrogen containing environments because hydrogen embrittlement may be very complicated process. And the characteristics of galvanic corrosion closely related to hydrogen embrittlement is qualitatively based on wimple electrochemical theory

  20. Unilateral vestibular loss impairs external space representation.

    Directory of Open Access Journals (Sweden)

    Liliane Borel

    Full Text Available The vestibular system is responsible for a wide range of postural and oculomotor functions and maintains an internal, updated representation of the position and movement of the head in space. In this study, we assessed whether unilateral vestibular loss affects external space representation. Patients with Menière's disease and healthy participants were instructed to point to memorized targets in near (peripersonal and far (extrapersonal spaces in the absence or presence of a visual background. These individuals were also required to estimate their body pointing direction. Menière's disease patients were tested before unilateral vestibular neurotomy and during the recovery period (one week and one month after the operation, and healthy participants were tested at similar times. Unilateral vestibular loss impaired the representation of both the external space and the body pointing direction: in the dark, the configuration of perceived targets was shifted toward the lesioned side and compressed toward the contralesioned hemifield, with higher pointing error in the near space. Performance varied according to the time elapsed after neurotomy: deficits were stronger during the early stages, while gradual compensation occurred subsequently. These findings provide the first demonstration of the critical role of vestibular signals in the representation of external space and of body pointing direction in the early stages after unilateral vestibular loss.

  1. Metabolic disorders of the vestibular system.

    Science.gov (United States)

    Rybak, L P

    1995-01-01

    This article reviews the impact of metabolic disorders on vestibular function. Diabetes mellitus is a disorder of glucose metabolism that can be associated with vestibular dysfunction. Vertigo can be alleviated by diet management in many cases. Elevated levels of blood lipids have been implicated in cochleovestibular disorders. Treatment with a lipid-lowering drug has resulted in improved auditory and vestibular function in a placebo-controlled trial. Hypothyroidism may affect different parts of the vestibular system depending on the severity and duration of thyroid deficiency. Severe congenital hypothyroidism can cause central vestibular disorders affecting the cerebellum, whereas mild hypothyroidism may result in peripheral vestibulopathy. Endogenous alterations in concentrations of estrogen and progesterone in the premenstrual syndrome or with the use of exogenous hormones such as oral contraceptives may trigger vertigo. Metabolic evaluations for unexplained vertigo should include a lipoprotein profile, with cholesterol and triglyceride levels, glucose tolerance test, and thyroid hormone measurements. Nutritional and drug therapy may be useful to reverse the vestibular dysfunction.

  2. Patients with vestibular loss, tullio phenomenon, and pressure-induced nystagmus: vestibular atelectasis?

    Science.gov (United States)

    Wenzel, Angela; Ward, Bryan K; Schubert, Michael C; Kheradmand, Amir; Zee, David S; Mantokoudis, Georgios; Carey, John Patrick

    2014-06-01

    To propose an etiology for a syndrome of bilateral vestibular hypofunction and sound and/or pressure-evoked eye movements with normal hearing thresholds. Retrospective case series. Tertiary care referral center. Four patients with bilateral vestibular hypofunction, sound and/or pressure-evoked nystagmus and normal hearing thresholds were identified over a 3-year period. No evidence of other known vestibular disorders was identified. None of these patients presented with a history of exposure to toxins, radiation, aminoglycosides or chemotherapy; head trauma; or a family history of inherited vestibular loss. All patients underwent high-resolution CT scan of the temporal bones to evaluate for labyrinthine dehiscence. Additionally, all individuals underwent audiometric testing to ANSI standards, vestibular-evoked myogenic potentials (VEMP) testing using either click stimulus cervical VEMPs (cVEMPs), or tone burst ocular VEMPs (oVEMPs). Bithermal caloric stimulation was used to measure horizontal semicircular canal function, with either videonystagmography (VNG) or electronystagmography (ENG) to record eye movements. Individual responses of each of the 6 semicircular canals (SCC) to rapid head rotations were tested with the bedside head impulse test. We identified 4 patients with a combination of bilateral vestibular hypofunction and sound and/or pressure-induced eye movements, normal-hearing thresholds and no evidence for any other vestibular disorder. We suggest that this unique combination of symptoms should be considered as the clinical presentation of vestibular atelectasis, which has been previously described histologically as collapse of the endolymph-containing portions of the labyrinth.

  3. ERG voltage-gated K+ channels regulate excitability and discharge dynamics of the medial vestibular nucleus neurones.

    Science.gov (United States)

    Pessia, Mauro; Servettini, Ilenio; Panichi, Roberto; Guasti, Leonardo; Grassi, Silvarosa; Arcangeli, Annarosa; Wanke, Enzo; Pettorossi, Vito Enrico

    2008-10-15

    The discharge properties of the medial vestibular nucleus neurones (MVNn) critically depend on the activity of several ion channel types. In this study we show, immunohistochemically, that the voltage-gated K(+) channels ERG1A, ERG1B, ERG2 and ERG3 are highly expressed within the vestibular nuclei of P10 and P60 mice. The role played by these channels in the spike-generating mechanisms of the MVNn and in temporal information processing was investigated electrophysiologically from mouse brain slices, in vitro, by analysing the spontaneous discharge and the response to square-, ramp- and sinusoid-like intracellular DC current injections in extracellular and whole-cell patch-clamp studies. We show that more than half of the recorded MVNn were responsive to ERG channel block (WAY-123,398, E4031), displaying an increase in spontaneous activity and discharge irregularity. The response to step and ramp current injection was also modified by ERG block showing a reduction of first spike latency, enhancement of discharge rate and reduction of the slow spike-frequency adaptation process. ERG channels influence the interspike slope without affecting the spike shape. Moreover, in response to sinusoid-like current, ERG channel block caused frequency-dependent gain enhancement and phase-lead shift. Taken together, the data demonstrate that ERG channels control the excitability of MVNn, their discharge regularity and probably their resonance properties.

  4. Novel Galvanic Corrosion Inhibitors: Synthesis, Characterization, Fabrication and Testing

    Science.gov (United States)

    2007-09-30

    Polyimide Insulated Electrical Wire", SAMPE pp.16, Jan/Feb 1984. 11. Brown, S. R.; Deluccia, J.J., " Galvanic Corrosion Fatigue Testing of 7075-T6...Modified Microporous Aluminosilicate" Development of Adsorbents for Air and Water Treatment Conference, 226th American Chemical Society (ACS) National

  5. Galvanic Cells and the Determination of Equilibrium Constants

    Science.gov (United States)

    Brosmer, Jonathan L.; Peters, Dennis G.

    2012-01-01

    Readily assembled mini-galvanic cells can be employed to compare their observed voltages with those predicted from the Nernst equation and to determine solubility products for silver halides and overall formation constants for metal-ammonia complexes. Results obtained by students in both an honors-level first-year course in general chemistry and…

  6. Galvanic corrosion of laser weldments of AA6061 aluminium alloy

    International Nuclear Information System (INIS)

    Rahman, A.B.M. Mujibur; Kumar, S.; Gerson, A.R.

    2007-01-01

    Galvanic corrosion of laser welded AA6061 aluminium alloy, arising from the varying rest potentials of the various weldment regions, was examined. The weld fusion zone is found to be the most cathodic region of the weldment while the base material is the most anodic region. The rate of galvanic corrosion, controlled by the cathodic process at the weld fusion zone, increases with time until a steady state maximum is reached. On galvanic corrosion the corrosion potential of the weld fusion zone shifts in the positive direction and the free corrosion current increases. It is proposed that the cathodic process at the weld fusion zone causes a local increase in pH that in turn causes dissolution of the surface film resulting in the loss of Al to solution and the increase of intermetallic phases. The increase in galvanic corrosion may result from either the build up of the intermetallic phases in the surface layer and/or significant increase in surface area of the weld fusion zone due to the porous nature of the surface layer

  7. Effects of galvanic distortions on magnetotelluric data: Interpretation ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    But in the case of field data the problem is ... The distorted data set is corrected using the MT response for DRS model and further ... ments, the apparent resistivity and phase at differ- ... from the telluric field, which is of galvanic or inductive ...

  8. An Easy-to-Assemble Three-Part Galvanic Cell

    Science.gov (United States)

    Eggen, Per-Odd; Skaugrud, Brit

    2015-01-01

    The galvanic cell presented in this article is made of only three parts, is easy to assemble, and can light a red light emitting diode (LED). The three cell components consist of a piece of paper with copper sulfate, a piece of paper with sodium sulfate, and a piece of magnesium ribbon. Within less than 1 h, students have time to discuss the…

  9. 76 FR 21914 - Galvanized Steel Wire From China and Mexico

    Science.gov (United States)

    2011-04-19

    ... INTERNATIONAL TRADE COMMISSION [Investigation Nos. 701-TA-479 and 731-TA-1183-1184 (Preliminary)] Galvanized Steel Wire From China and Mexico AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject antidumping and countervailing duty investigations. DATES: Effective Date...

  10. The sinusoidal lining cells in "normal" human liver. A scanning electron microscopic investigation

    DEFF Research Database (Denmark)

    Horn, T; Henriksen, Jens Henrik Sahl; Christoffersen, P

    1986-01-01

    The scanning electron microscopic was used to study the fenestrations of human liver sinusoids. Thirteen biopsies, where light microscopy and transmission electron microscopy revealed normal sinusoidal architecture, were investigated. The number of fenestrae was calculated in acinar zone 3...

  11. Unified design of sinusoidal-groove fused-silica grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lu, Peng

    2010-10-20

    A general design rule of deep-etched subwavelength sinusoidal-groove fused-silica grating as a highly efficient polarization-independent or polarization-selective device is studied based on the simplified modal method, which shows that the device structure depends little on the incident wavelength, but mainly on the ratio of groove depth to incident wavelength and the ratio of wavelength to grating period. These two ratios could be used as the design guidelines for wavelength-independent structure from deep ultraviolet to far infrared. The optimized grating profile with a different function as a polarizing beam splitter, a polarization-independent two-port beam splitter, or a polarization-independent grating with high efficiency of -1st order is obtained at a wavelength of 1064 nm, and verified by using the rigorous coupled-wave analysis. The performance of the sinusoidal grating is better than a conventional rectangular one, which could be useful for practical applications.

  12. Investigation of Calibrating Force Transducer Using Sinusoidal Force

    International Nuclear Information System (INIS)

    Zhang Li; Wang Yu; Zhang Lizhe

    2010-01-01

    Sinusoidal force calibration method was studied several years before at Physikalisch-Technische Bundesanstalt (PTB). A similar dynamic force calibration system is developed at Changcheng Institute of Metrology and Measurement (CIMM). It uses electro-dynamic shakers to generate dynamic force in the range from 1 N to 20 kN, and heterodyne laser interferometers are used for acceleration measurement. The force transducer to be calibrated is mounted on the shaker, and a mass block is screwed on the top of force transducer, the sinusoidal forces realized by accelerated load masses are traceable to acceleration and mass according to the force definition. The methods of determining Spatial-dependent acceleration on mass block and measuring the end mass of force transducer in dynamic force calibration are discussed in this paper.

  13. Electric stimulation with sinusoids and white noise for neural prostheses

    Directory of Open Access Journals (Sweden)

    Daniel K Freeman

    2010-02-01

    Full Text Available We are investigating the use of novel stimulus waveforms in neural prostheses to determine whether they can provide more precise control over the temporal and spatial pattern of elicited activity as compared to conventional pulsatile stimulation. To study this, we measured the response of retinal ganglion cells to both sinusoidal and white noise waveforms. The use of cell-attached and whole cell patch clamp recordings allowed the responses to be observed without significant obstruction from the stimulus artifact. Electric stimulation with sinusoids elicited robust responses. White noise analysis was used to derive the linear kernel for the ganglion cell’s spiking response as well as for the underlying excitatory currents. These results suggest that in response to electric stimulation, presynaptic retinal neurons exhibit bandpass filtering characteristics with peak response that occur 25ms after onset. The experimental approach demonstrated here may be useful for studying the temporal response properties of other neurons in the CNS.

  14. Interactive Healthcare Systems in the Home: Vestibular Rehabilitation

    DEFF Research Database (Denmark)

    Aarhus, Rikke; Grönvall, Erik; Larsen, Simon Bo

    2010-01-01

    Vestibular dysfunction is a balance disorder, causing dizziness that provokes discomfort and fall situations. This paper discusses early results from a project that aims to develop assistive technologies to support home-based rehabilitation for elderly affected by Vestibular dysfunction.......Vestibular dysfunction is a balance disorder, causing dizziness that provokes discomfort and fall situations. This paper discusses early results from a project that aims to develop assistive technologies to support home-based rehabilitation for elderly affected by Vestibular dysfunction....

  15. Vestibular Schwannoma or acoustic neuroma

    Directory of Open Access Journals (Sweden)

    Hekmatara M

    1997-04-01

    Full Text Available Vestibular schwannoma is the most common tumor of the posterior fossa of the skull. Patients referred with the primary otologic symptoms such as hearing loss, tinnitus, vertigo, imbalance, and the cranial nerve palsy. Thirty-three patients were operated and treated by a team of otolaryngologist and neurosurgeon, anudiometrist, and internist. Patients'chiefcomplaint was due to 94% hearing loss and 27% tinnitus. They scarcely complain of vertigo. If a patient refers with the palsy or paralysis of facial nerve preoperation, we must think of the facial nerve schwannoma or hemangioma or congential cholestoma or malignant metastases rather than acoustic neuroma. The best way for preoperative diagnosis is audiometry, ABR (Auditory Brain Response, and SDS (speech discrimination score with 90% success, but computer Tomography (CT scan and MRI (Magnetic Resonance Image are the valuable anatomic diagnostic radiographic devices. The best method of operation is translabirynthine approach (TLA, since it has the advantages such as an easy access to nerve paths and being the nearest path to CPA (Cerebellopontine Angle. Physicians ought to talk to patients about the importance of the microscopic surgery, surgical methods, and their probable diverse effects such as hearing loss, facial nerve palsy, and intracranial problems.

  16. Vestibular Function Impairment in Alzheimer's Disease.

    Science.gov (United States)

    Nakamagoe, Kiyotaka; Fujimiya, Suguru; Koganezawa, Tadachika; Kadono, Kotarou; Shimizu, Kotone; Fujizuka, Natsu; Takiguchi, Shino; Ueno, Tomoyuki; Monzen, Tatsuya; Tamaoka, Akira

    2015-01-01

    Falls and fractures due to impaired balance in patients with Alzheimer's disease (AD) have an adverse effect on the clinical course of the disease. To evaluate balance impairment in AD from the viewpoint of vestibular functional impairment. The subjects were 12 patients with AD, 12 dementia-free elderly adults, and 12 younger adults. Vestibular function was assessed using a stepping test, caloric nystagmus, and a visual suppression (VS) test. The stepping test was abnormal in 9 of the 12 patients in the AD group. An abnormal stepping test was not associated with self-reported dizziness or tendency to fall. Significant VS abnormalities were present in the AD group. The suppression rate of VS was lower in AD patients with either a tendency to fall or constructional apraxia than in AD patients without either. The velocity of the rapid phase of caloric nystagmus before the VS test was similar in the AD group and the elderly control group. Significant abnormalities of both caloric nystagmus and VS were not present in either the elderly or the younger control groups. AD could involve impairments in the vestibular control of balance. The VS test is useful for assessing the tendency to fall in AD. Impairment of VS in AD might arise from cerebral vestibular cortex impairment rather than comorbid peripheral vestibular disorders.

  17. Complications of Microsurgery of Vestibular Schwannoma

    Directory of Open Access Journals (Sweden)

    Jan Betka

    2014-01-01

    Full Text Available Background. The aim of this study was to analyze complications of vestibular schwannoma (VS microsurgery. Material and Methods. A retrospective study was performed in 333 patients with unilateral vestibular schwannoma indicated for surgical treatment between January 1997 and December 2012. Postoperative complications were assessed immediately after VS surgery as well as during outpatient followup. Results. In all 333 patients microsurgical vestibular schwannoma (Koos grade 1: 12, grade 2: 34, grade 3: 62, and grade 4: 225 removal was performed. The main neurological complication was facial nerve dysfunction. The intermediate and poor function (HB III–VI was observed in 124 cases (45% immediately after surgery and in 104 cases (33% on the last followup. We encountered disordered vestibular compensation in 13%, permanent trigeminal nerve dysfunction in 1%, and transient lower cranial nerves (IX–XI deficit in 6%. Nonneurological complications included CSF leakage in 63% (lateral/medial variant: 99/1%, headache in 9%, and intracerebral hemorrhage in 5%. We did not encounter any case of meningitis. Conclusions. Our study demonstrates that despite the benefits of advanced high-tech equipment, refined microsurgical instruments, and highly developed neuroimaging technologies, there are still various and significant complications associated with vestibular schwannomas microsurgery.

  18. Increased sinusoidal volume and solute extraction during retrograde liver perfusion

    International Nuclear Information System (INIS)

    Bass, N.M.; Manning, J.A.; Weisiger, R.A.

    1989-01-01

    Retrograde isolated liver perfusion has been used to probe acinar functional heterogeneity, but the hemodynamic effects of backward flow have not been characterized. In this study, extraction of a long-chain fatty acid derivative, 12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazol-amino stearate (12-NBDS), was greater during retrograde than during anterograde perfusion of isolated rat liver. To determine whether hemodynamic differences between anterograde and retrograde perfused livers could account for this finding, the hepatic extracellular space was measured for both directions of flow by means of [ 14 C]sucrose washout during perfusion as well as by direct measurement of [ 14 C]sucrose entrapped during perfusion. A three- to fourfold enlargement of the total hepatic extracellular space was found during retrograde perfusion by both approaches. Examination of perfusion-fixed livers by light microscopy and morphometry revealed that marked distension of the sinusoids occurred during retrograde perfusion and that this accounts for the observed increase in the [ 14 C]sucrose space. These findings support the hypothesis that maximum resistance to perfusate flow in the isolated perfused rat liver is located at the presinusoidal level. In addition, increased transit time of perfusate through the liver and greater sinusoidal surface area resulting from sinusoidal distension may account for the higher extraction of 12-NBDS and possibly other compounds by retrograde perfused liver

  19. Dietary macronutrients and the aging liver sinusoidal endothelial cell.

    Science.gov (United States)

    Cogger, Victoria Carroll; Mohamad, Mashani; Solon-Biet, Samantha Marie; Senior, Alistair M; Warren, Alessandra; O'Reilly, Jennifer Nicole; Tung, Bui Thanh; Svistounov, Dmitri; McMahon, Aisling Clare; Fraser, Robin; Raubenheimer, David; Holmes, Andrew J; Simpson, Stephen James; Le Couteur, David George

    2016-05-01

    Fenestrations are pores within the liver sinusoidal endothelial cells (LSECs) that line the sinusoids of the highly vascularized liver. Fenestrations facilitate the transfer of substrates between blood and hepatocytes. With pseudocapillarization of the hepatic sinusoid in old age, there is a loss of fenestrations. LSECs are uniquely exposed to gut-derived dietary and microbial substrates delivered by the portal circulation to the liver. Here we studied the effect of 25 diets varying in content of macronutrients and energy on LSEC fenestrations using the Geometric Framework method in a large cohort of mice aged 15 mo. Macronutrient distribution rather than total food or energy intake was associated with changes in fenestrations. Porosity and frequency were inversely associated with dietary fat intake, while fenestration diameter was inversely associated with protein or carbohydrate intake. Fenestrations were also linked to diet-induced changes in gut microbiome, with increased fenestrations associated with higher abundance of Firmicutes and reduced abundance of Bacteroidetes Diet-induced changes in levels of several fatty acids (C16:0, C19:0, and C20:4) were also significantly inversely associated with fenestrations, suggesting a link between dietary fat and modulation of lipid rafts in the LSECs. Diet influences fenestrations and these data reflect both the key role of the LSECs in clearing gut-derived molecules from the vascular circulation and the impact these molecules have on LSEC morphology. Copyright © 2016 the American Physiological Society.

  20. Fibronectin Extra Domain A Promotes Liver Sinusoid Repair following Hepatectomy.

    Directory of Open Access Journals (Sweden)

    Bridget Sackey-Aboagye

    Full Text Available Liver sinusoidal endothelial cells (LSECs are the main endothelial cells in the liver and are important for maintaining liver homeostasis as well as responding to injury. LSECs express cellular fibronectin containing the alternatively spliced extra domain A (EIIIA-cFN and increase expression of this isoform after liver injury, although its function is not well understood. Here, we examined the role of EIIIA-cFN in liver regeneration following partial hepatectomy. We carried out two-thirds partial hepatectomies in mice lacking EIIIA-cFN and in their wild type littermates, studied liver endothelial cell adhesion on decellularized, EIIIA-cFN-containing matrices and investigated the role of cellular fibronectins in liver endothelial cell tubulogenesis. We found that liver weight recovery following hepatectomy was significantly delayed and that sinusoidal repair was impaired in EIIIA-cFN null mice, especially females, as was the lipid accumulation typical of the post-hepatectomy liver. In vitro, we found that liver endothelial cells were more adhesive to cell-deposited matrices containing the EIIIA domain and that cellular fibronectin enhanced tubulogenesis and vascular cord formation. The integrin α9β1, which specifically binds EIIIA-cFN, promoted tubulogenesis and adhesion of liver endothelial cells to EIIIA-cFN. Our findings identify a role for EIIIA-cFN in liver regeneration and tubulogenesis. We suggest that sinusoidal repair is enhanced by increased LSEC adhesion, which is mediated by EIIIA-cFN.

  1. Can a finding of cervical vestibular evoked myogenic potentials contribute to vestibular migraine diagnostics?

    Directory of Open Access Journals (Sweden)

    Tihana Vešligaj

    2016-02-01

    Full Text Available Aim To investigate differences in vestibular evoked myogenic potentials (VEMP results with patients suffering from vestibular migraine and healthy people, taking into consideration values of threshold and latency of occurrence of the characteristic wave complex, size of amplitude, and interaural amplitude ratio. According to the results, determine the importance and usefulness of VEMP in vestibular migraine diagnostics. Methods A total number of 62 subjects were included in the study, 32 of them belonging to a group of patients suffering from vestibular migraine (VM, while other 30 were in a control group of healthy subjects. Information was collected during the diagnostic evaluation. General and otoneurological history of patients and bedside tests, audiological results, videonystagmography and cervical vestibular evoked myogenic potentials (cVEMP were made. Results There was a difference in an interaural ratio of amplitudes in the experimental and control groups, but it was not found to be clinically significant. By ToneBurst 500 Hz method, the interaural amplitude ratio higher than 35% was measured in 46.97% subjects, while the response was totally unilaterally missing in 28.8% patients. Conclusion Even the sophisticated method as cVEMP does not give the ultimate result confirming the vestibular migraine diagnosis, and neither do other diagnostic methods. cVEMP result can contribute to the completion of full mosaic of vestibular migraine diagnostics.

  2. Expression of vesicular glutamate transporters in peripheral vestibular structures and vestibular nuclear complex of rat.

    Science.gov (United States)

    Zhang, F X; Pang, Y W; Zhang, M M; Zhang, T; Dong, Y L; Lai, C H; Shum, D K Y; Chan, Y S; Li, J L; Li, Y Q

    2011-01-26

    Glutamate transmission from vestibular end organs to central vestibular nuclear complex (VNC) plays important role in transferring sensory information about head position and movements. Three isoforms of vesicular glutamate transporters (VGLUTs) have been considered so far the most specific markers for glutamatergic neurons/cells. In this study, VGLUT1 and VGLUT2 were immunohistochemically localized to axon terminals in VNC and somata of vestibular primary afferents in association with their central and peripheral axon endings, and VGLUT1 and VGLUT3 were co-localized to hair cells of otolith maculae and cristae ampullaris. VGLUT1 and VGLUT2 defined three subsets of Scarpa's neurons (vestibular ganglionic neurons): those co-expressing VGLUT1 and VGLUT2 or expressing only VGLUT2, and those expressing neither. In addition, many neurons located in all vestibular subnuclei were observed to contain hybridized signals for VGLUT2 mRNA and a few VNC neurons, mostly scattered in medial vestibular nucleus (MVe), displayed VGLUT1 mRNA labelling. Following unilateral ganglionectomy, asymmetries of VGLUT1-immunoreactivity (ir) and VGLUT2-ir occurred between two VNCs, indicating that the VNC terminals containing VGLUT1 and/or VGLUT2 are partly of peripheral origin. The present data indicate that the constituent cells/neurons along the vestibular pathway selectively apply VGLUT isoforms to transport glutamate into synaptic vesicles for glutamate transmission. © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

  3. Origin of vestibular dysfunction in Usher syndrome type 1B.

    NARCIS (Netherlands)

    Sun, J.; Alphen, A.M. van; Wagenaar, M.; Huygen, P.L.M.; Hoogenraad, C.C.; Hasson, T.; Koekkoek, S.K.; Bohne, B.A.; Zeeuw, C.I. de

    2001-01-01

    It is still debated to what extent the vestibular deficits in Usher patients are due to either central vestibulocerebellar or peripheral vestibular problems. Here, we determined the origin of the vestibular symptoms in Usher 1B patients by subjecting them to compensatory eye movement tests and by

  4. Relationships Between Vestibular Measures as Potential Predictors for Spaceflight Sensorimotor Adaptation

    Science.gov (United States)

    Clark, T. K.; Peters, B.; Gadd, N. E.; De Dios, Y. E.; Wood, S.; Bloomberg, J. J.; Mulavara, A. P.

    2016-01-01

    Introduction: During space exploration missions astronauts are exposed to a series of novel sensorimotor environments, requiring sensorimotor adaptation. Until adaptation is complete, sensorimotor decrements occur, affecting critical tasks such as piloted landing or docking. Of particularly interest are locomotion tasks such as emergency vehicle egress or extra-vehicular activity. While nearly all astronauts eventually adapt sufficiently, it appears there are substantial individual differences in how quickly and effectively this adaptation occurs. These individual differences in capacity for sensorimotor adaptation are poorly understood. Broadly, we aim to identify measures that may serve as pre-flight predictors of and individual's adaptation capacity to spaceflight-induced sensorimotor changes. As a first step, since spaceflight is thought to involve a reinterpretation of graviceptor cues (e.g. otolith cues from the vestibular system) we investigate the relationships between various measures of vestibular function in humans. Methods: In a set of 15 ground-based control subjects, we quantified individual differences in vestibular function using three measures: 1) ocular vestibular evoked myogenic potential (oVEMP), 2) computerized dynamic posturography and 3) vestibular perceptual thresholds. oVEMP responses are elicited using a mechanical stimuli approach. Computerized dynamic posturography was used to quantify Sensory Organization Tests (SOTs), including SOT5M which involved performing pitching head movements while balancing on a sway-reference support surface with eyes closed. We implemented a vestibular perceptual threshold task using the tilt capabilities of the Tilt-Translation Sled (TTS) at JSC. On each trial, the subject was passively roll-tilted left ear down or right ear down in the dark and verbally provided a forced-choice response regarding which direction they felt tilted. The motion profile was a single-cycle sinusoid of angular acceleration with a

  5. Difference in quick phases induced by horizontal and vertical vestibular stimulations: role of the otolithic input.

    Science.gov (United States)

    Pettorossi, V E; Errico, P; Ferraresi, A

    1997-01-01

    Quick phases (QPs) induced by horizontal and vertical sinusoidal vestibular stimulations were studied in rabbits, cats, and humans. In all the animals, large and frequent horizontal QPs were observed following yaw stimulation in prone position. By contrast, QPs were almost absent during roll stimulation in rabbits, and they were small and oblique during pitch stimulation in cats and humans. As a result of these differences, the range of gaze displacement induced by vestibular stimulations was greater in the horizontal plane than in the vertical one. We also found that the trajectory of the QPs in rabbits was kept horizontal even when the yaw rotation was off vertical axis of +/- 45 degrees in the sagittal plane. Moreover, in the rabbit, the rare horizontal QPs induced by roll stimulation did not change their orientation at various pitch angles of roll stimulation axis. The QPs were also analyzed following roll stimulation of the rabbit in supine position. In this condition, in which the otolithic receptors were activated in the opposite way compared to prone position, large vertical QPs were elicited. We concluded that these results provide evidence that the otolithic signal plays a role in controlling occurrence and trajectory orientation of the QPs.

  6. Neural Correlates of Sensory Substitution in Vestibular Pathways Following Complete Vestibular Loss

    Science.gov (United States)

    Sadeghi, Soroush G.; Minor, Lloyd B.; Cullen, Kathleen E.

    2012-01-01

    Sensory substitution is the term typically used in reference to sensory prosthetic devices designed to replace input from one defective modality with input from another modality. Such devices allow an alternative encoding of sensory information that is no longer directly provided by the defective modality in a purposeful and goal-directed manner. The behavioral recovery that follows complete vestibular loss is impressive and has long been thought to take advantage of a natural form of sensory substitution in which head motion information is no longer provided by vestibular inputs, but instead by extra-vestibular inputs such as proprioceptive and motor efference copy signals. Here we examined the neuronal correlates of this behavioral recovery after complete vestibular loss in alert behaving monkeys (Macaca mulata). We show for the first time that extra-vestibular inputs substitute for the vestibular inputs to stabilize gaze at the level of single neurons in the VOR premotor circuitry. The summed weighting of neck proprioceptive and efference copy information was sufficient to explain simultaneously observed behavioral improvements in gaze stability. Furthermore, by altering correspondence between intended and actual head movement we revealed a four-fold increase in the weight of neck motor efference copy signals consistent with the enhanced behavioral recovery observed when head movements are voluntary versus unexpected. Thus, taken together our results provide direct evidence that the substitution by extra-vestibular inputs in vestibular pathways provides a neural correlate for the improvements in gaze stability that are observed following the total loss of vestibular inputs. PMID:23077054

  7. Interactions of touch feedback with muscle vibration and galvanic vestibular stimulation in the control of trunk posture

    NARCIS (Netherlands)

    Maaswinkel, E.; Veeger, H.E.J.; van Dieen, J.H.

    2014-01-01

    This study investigated the effect of touch on trunk sway in a seated position. Two touch conditions were included: touching an object with the index finger of the right hand (hand-touch) and maintaining contact with an object at the level of the spine of T10 on the mid back (back-touch). In both

  8. Galvanic corrosion between carbon steel 1018 and Alloy 600 in crevice with boric acid solution

    International Nuclear Information System (INIS)

    Kim, Dong Jin; Kim, Hong Pyo; Kim, Joung Soo; Machonald, Digby D.

    2005-01-01

    This work dealt with the evaluation of galvanic corrosion rate in a corrosion cell having annular gap of 0.5 mm between carbon steel 1018 and alloy 600 as a function of temperature and boron concentration. Temperature and boron concentration were ranged from 110 to 300 .deg. C and 2000∼10000 ppm, respectively. After the operating temperature of the corrosion cell where the electrolyte was injected was attained at setting temperature, galvanic coupling was made and at the same time galvanic current was measured. The galvanic corrosion rate decreased with time, which was described by corrosion product such as protective film as well as boric acid deposit formed on the carbon steel with time. From the galvanic current obtained as a function of temperature and boron concentration, it was found that the galvanic corrosion rate decreased with temperature while the corrosion rate increased with boron concentration. The experimental results obtained from galvanic corrosion measurement were explained by adhesive property of corrosion product such as protective film, boric acid deposit formed on the carbon steel wall and dehydration of boric acid to be slightly soluble boric acid phase. Moreover the galvanic corrosion rate calculated using initial galvanic coupling current instead of steady state coupling current was remarked, which could give us relatively closer galvanic corrosion rate to real pressurized water reactor

  9. Very High Frequency Galvanic Isolated Offline Power Supply

    DEFF Research Database (Denmark)

    Pedersen, Jeppe Arnsdorf

    During the last decades many researchers have turned their attention to raising the operation frequency of power converters to the very high frequency (VHF) range going from 30 MHz to 300 MHz. Increasing the operating frequency of a power converter leads to smaller energy storing components...... inverters with a single combined rectifier. The converter designed to deliver 9 W to a 60 V LED load and is achieving an efficiency of 89.4% and a power density of 2.14 W3 . The development of this converter proof that offline VHF converter can be implemented with high efficiencies even for low power applications...... are described together with the possibility of using capacitors as the power galvanic isolation, both methods of creating galvanic isolation are implemented in converters. Regarding EMC a series of converters with different filter implementations are examined. The results from the conducted mea-surement from 150...

  10. Processing hot-dip galvanized AHSS grades: a challenging task

    Energy Technology Data Exchange (ETDEWEB)

    Pichler, A.; Hebesberger, T.; Tragl, E.; Traint, S.; Faderl, J.; Angeli, G.; Koesters, K. [voestalpine Stahl GmbH, Linz (Austria)

    2005-07-01

    High-strength thin sheet steel grades have gained a considerable market share. At present a very strong demand has been observed for DP (dual-phase), CP (complex phase) and TRIP grades, which are often summarized as advanced high-strength steel grades (AHSS). The potential benefits of applying AHSS grades were impressively demonstrated in the ULSAC-AVC project, in which a remarkable reduction in mass and an increase in stiffness and crash safety were achieved by using a very high share of AHSS steel grades. The present contribution concentrates on hot-dip galvanized AHSS thin sheet grades. The hot-dip galvanizeability of such grades is critically discussed after an overview is provided of the metallurgy of AHSS grades, including microstructure, mechanical properties, phase transformations and required alloy design. Based on these fundamentals, the processing of AHSS grades in the hot-dip galvanizing line is discussed and the resulting properties presented. (orig.)

  11. Simulation of galvanic corrosion using boundary element method

    International Nuclear Information System (INIS)

    Zaifol Samsu; Muhamad Daud; Siti Radiah Mohd Kamaruddin; Nur Ubaidah Saidin; Abdul Aziz Mohamed; Mohd Saari Ripin; Rusni Rejab; Mohd Shariff Sattar

    2011-01-01

    Boundary element method (BEM) is a numerical technique that used for modeling infinite domain as is the case for galvanic corrosion analysis. The use of boundary element analysis system (BEASY) has allowed cathodic protection (CP) interference to be assessed in terms of the normal current density, which is directly proportional to the corrosion rate. This paper was present the analysis of the galvanic corrosion between Aluminium and Carbon Steel in natural sea water. The result of experimental was validated with computer simulation like BEASY program. Finally, it can conclude that the BEASY software is a very helpful tool for future planning before installing any structure, where it gives the possible CP interference on any nearby unprotected metallic structure. (Author)

  12. Reprocessing of zinc galvanic waste sludge by selective precipitation

    Czech Academy of Sciences Publication Activity Database

    Jandová, J.; Maixner, J.; Grygar, Tomáš

    2002-01-01

    Roč. 46, č. 2 (2002), s. 52-55 ISSN 0862-5468 R&D Projects: GA AV ČR IBS4032004; GA ČR GA203/99/0067 Institutional research plan: CEZ:AV0Z4032918; CEZ:MSM 223100002 Keywords : galvanic sludge * recovery * zinc Subject RIV: CA - Inorganic Chemistry Impact factor: 0.354, year: 2002

  13. Silver matrix composites reinforced with galvanically silvered particles

    OpenAIRE

    J. Śleziona; J. Wieczorek,

    2007-01-01

    Purpose: The paper presents the possibility of the application of metalic layers drifted with the use of the galvanic methods on the ceramic particles surface. The application of the layers was aimed at obtaining the rewetting of the reinforcing particles with the liquid silver in the course of the producing of silver matrix composites with the use of mechanical stirring method. To enable introducing of the iron powder and glass carbon powder to liquid silver the solution of covering the powd...

  14. Sinusoidal modulation analysis for optical system MTF measurements.

    Science.gov (United States)

    Boone, J M; Yu, T; Seibert, J A

    1996-12-01

    The modulation transfer function (MTF) is a commonly used metric for defining the spatial resolution characteristics of imaging systems. While the MTF is defined in terms of how an imaging system demodulates the amplitude of a sinusoidal input, this approach has not been in general use to measure MTFs in the medical imaging community because producing sinusoidal x-ray patterns is technically difficult. However, for optical systems such as charge coupled devices (CCD), which are rapidly becoming a part of many medical digital imaging systems, the direct measurement of modulation at discrete spatial frequencies using a sinusoidal test pattern is practical. A commercially available optical test pattern containing spatial frequencies ranging from 0.375 cycles/mm to 80 cycles/mm was sued to determine the MRF of a CCD-based optical system. These results were compared with the angulated slit method of Fujita [H. Fujita, D. Tsia, T. Itoh, K. Doi, J. Morishita, K. Ueda, and A. Ohtsuka, "A simple method for determining the modulation transfer function in digital radiography," IEEE Trans. Medical Imaging 11, 34-39 (1992)]. The use of a semiautomated profiled iterated reconstruction technique (PIRT) is introduced, where the shift factor between successive pixel rows (due to angulation) is optimized iteratively by least-squares error analysis rather than by hand measurement of the slit angle. PIRT was used to find the slit angle for the Fujita technique and to find the sine-pattern angle for the sine-pattern technique. Computer simulation of PIRT for the case of the slit image (a line spread function) demonstrated that it produced a more accurate angle determination than "hand" measurement, and there is a significant difference between the errors in the two techniques (Wilcoxon Signed Rank Test, p < 0.001). The sine-pattern method and the Fujita slit method produced comparable MTF curves for the CCD camera evaluated.

  15. Central vestibular dysfunction in an otorhinolaryngological vestibular unit: incidence and diagnostic strategy.

    Science.gov (United States)

    Mostafa, Badr E; Kahky, Ayman O El; Kader, Hisham M Abdel; Rizk, Michael

    2014-07-01

    Introduction Vertigo can be due to a variety of central and peripheral causes. The relative incidence of central causes is underestimated. This may have an important impact of the patients' management and prognosis. Objective The objective of this work is to determine the incidence of central vestibular disorders in patients presenting to a vestibular unit in a tertiary referral academic center. It also aims at determining the best strategy to increase the diagnostic yield of the patients' visit. Methods This is a prospective observational study on 100 consecutive patients with symptoms suggestive of vestibular dysfunction. All patients completed a structured questionnaire and received bedside and vestibular examination and neuroimaging as required. Results There were 69 women and 31 men. Their ages ranged between 28 and 73 (mean 42.48 years). Provisional videonystagmography (VNG) results were: 40% benign paroxysmal positional vertigo (BPPV), 23% suspicious of central causes, 18% undiagnosed, 15% Meniere disease, and 4% vestibular neuronitis. Patients with an unclear diagnosis or central features (41) had magnetic resonance imaging (MRI) and Doppler studies. Combining data from history, VNG, and imaging studies, 23 patients (23%) were diagnosed as having a central vestibular lesion (10 with generalized ischemia/vertebra basilar insufficiency, 4 with multiple sclerosis, 4 with migraine vestibulopathy, 4 with phobic postural vertigo, and 1 with hyperventilation-induced nystagmus). Conclusions Combining a careful history with clinical examination, VNG, MRI, and Doppler studies decreases the number of undiagnosed cases and increases the detection of possible central lesions.

  16. Central Vestibular Dysfunction in an Otorhinolaryngological Vestibular Unit: Incidence and Diagnostic Strategy

    Directory of Open Access Journals (Sweden)

    Mostafa, Badr E.

    2014-03-01

    Full Text Available Introduction Vertigo can be due to a variety of central and peripheral causes. The relative incidence of central causes is underestimated. This may have an important impact of the patients' management and prognosis. Objective The objective of this work is to determine the incidence of central vestibular disorders in patients presenting to a vestibular unit in a tertiary referral academic center. It also aims at determining the best strategy to increase the diagnostic yield of the patients' visit. Methods This is a prospective observational study on 100 consecutive patients with symptoms suggestive of vestibular dysfunction. All patients completed a structured questionnaire and received bedside and vestibular examination and neuroimaging as required. Results There were 69 women and 31 men. Their ages ranged between 28 and 73 (mean 42.48 years. Provisional videonystagmography (VNG results were: 40% benign paroxysmal positional vertigo (BPPV, 23% suspicious of central causes, 18% undiagnosed, 15% Meniere disease, and 4% vestibular neuronitis. Patients with an unclear diagnosis or central features (41 had magnetic resonance imaging (MRI and Doppler studies. Combining data from history, VNG, and imaging studies, 23 patients (23% were diagnosed as having a central vestibular lesion (10 with generalized ischemia/vertebra basilar insufficiency, 4 with multiple sclerosis, 4 with migraine vestibulopathy, 4 with phobic postural vertigo, and 1 with hyperventilation-induced nystagmus. Conclusions Combining a careful history with clinical examination, VNG, MRI, and Doppler studies decreases the number of undiagnosed cases and increases the detection of possible central lesions.

  17. Vestibular neuritis: three-dimensional videonystagmography and vestibular evoked myogenic potential results.

    Science.gov (United States)

    Chen, C W; Young, Y H; Wu, C H

    2000-10-01

    Eight patients diagnosed with vestibular neuritis received the newly developed three-dimensional videonystagmography (3D VNG) and vestibular evoked myogenic potential (VEMP) examination in order to localize the lesion site. Two (25%) of the 8 patients exhibited spontaneous nystagmus with 3 components, indicating that both the horizontal semicircular canal (HSCC) and anterior semicircular canal (ASCC) were affected. The remaining 6 patients (75%) displayed only horizontal nystagmus, meaning that only the HSCC was involved. Seven (88%) of the 8 patients had bilateral normal VEMPs, revealing sparing of the posterior semicircular canal (PSCC). In a comparative study, another seven patients with vestibular neuritis 1 year post-treatment also received the caloric test, 3D VNG and VEMP examination. Only one patient exhibited spontaneous nystagmus. An absent caloric response of the lesioned side persisted in 5 (71%) of the 7 patients. However, all patients showed normal VEMPs bilaterally. 3D VNG and VEMP examination indicates that vestibular neuritis mainly affects the superior division of the vestibular nerve, which innervates the HSCC and ASCC. Meanwhile, the function of the PSCC and saccule, innervated by the inferior vestibular nerve, is preserved.

  18. Propiedades de transporte de una superred de grafeno tipo sinusoidal

    OpenAIRE

    J. A. Briones-Torres; I. Rodríguez-Vargas

    2015-01-01

    En este trabajo usamos el método de la matriz de transferencia para estudiar el tunelamiento de los electrones de Dirac a través de superredes en grafeno. Consideramos una superred con potencial sinusoidal o polaridad invertida, para ello consideramos dos maneras de crearla, una por medio de sustratos mixtos junto con la aplicación de un campo perpendicular sobre el sustrato de Óxido de Silicio (SiO2), la otra por medio de potenciales alternados aplicados perpendicularmente sobre la sábana de...

  19. Ageing monitoring in IGBT module under sinusoidal loading

    DEFF Research Database (Denmark)

    Ghimire, Pramod; Pedersen, Kristian Bonderup; Rannestad, Bjørn

    2015-01-01

    This paper presents monitoring of ageing in high power insulated gate bipolar transistor (IGBT) modules subjected to sinusoidal loading at nominal power level. On-state voltage for IGBT, diode, and rise in interconnection resistance are used as ageing parameters. These are measured in three...... different ways: calibration of power modules after 24 h of operation, offline characterization every 5 min of operation, and continuous measurement during normal converter operation. Four power modules are tested, which are cycled to different degradation levels by number of cycles, where one is tested...

  20. Numerical analysis of beam with sinusoidally corrugated webs

    Science.gov (United States)

    Górecki, Marcin; Pieńko, Michał; Łagoda, GraŻyna

    2018-01-01

    The paper presents numerical tests results of the steel beam with sinusoidally corrugated web, which were performed in the Autodesk Algor Simulation Professional 2010. The analysis was preceded by laboratory tests including the beam's work under the influence of the four point bending as well as the study of material characteristics. Significant web's thickness and use of tools available in the software allowed to analyze the behavior of the plate girder as beam, and also to observe the occurrence of stresses in the characteristic element - the corrugated web. The stress distribution observed on the both web's surfaces was analyzed.

  1. Galvanic corrosion of copper-cast iron couples

    International Nuclear Information System (INIS)

    Smart, N.R.; Rance, A.P.; Fennell, P.A.H.

    2005-01-01

    To ensure the safe encapsulation of spent nuclear fuel rods for geological disposal, SKB are considering using the Copper-Cast Iron Canister, which consists of an outer copper canister and an inner cast iron container. The canister will be placed into boreholes in the bedrock of a geologic repository and surrounded by bentonite clay. In the unlikely event of the outer copper canister being breached, water would enter the annulus between the inner and outer canister and at points of contact between the two metals there would be the possibility of galvanic interactions. Although this subject has been considered previously from both a theoretical standpoint and by experimental investigations there was a need for further experimental studies in support of information provided by SKB to the Swedish regulators (SKI). In the work reported here copper-cast iron galvanic couples were set up in a number of different environments representing possible conditions in the SKB repository. The tests investigated two artificial porewaters at 30 deg C and 50 deg C, under aerated and deaerated conditions. Tests were also carried out in a 30 wt% bentonite slurry made up in artificial groundwater. The potential of the couples and the currents passing between the coupled electrodes were monitored for several months. The effect of growing an oxide film on the surface of the cast iron prior to coupling it with copper was investigated. In addition, some crevice specimens based on the multi-crevice assembly (MCA) design were used to simulate the situation where the copper canister will be in direct contact with the cast iron inner vessel. The electrochemical results are presented graphically in the form of electrode potentials and galvanic corrosion currents as a function of time. The galvanic currents in aerated conditions were much higher than in deaerated conditions. For example, at 30 deg C, galvanic corrosion rates as low as 0.02 μm/year for iron were observed after deaeration, but

  2. A Galvanic Coupling Method for Assessing Hydration Rates

    Directory of Open Access Journals (Sweden)

    Clement Ogugua Asogwa

    2016-07-01

    Full Text Available Recent advances in biomedical sensors, data acquisition techniques, microelectronics and wireless communication systems opened up the use of wearable technology for ehealth monitoring. We introduce a galvanic coupled intrabody communication for monitoring human body hydration. Studies in hydration provide the information necessary for understanding the desired fluid levels for optimal performance of the body’s physiological and metabolic processes during exercise and activities of daily living. Current measurement techniques are mostly suitable for laboratory purposes due to their complexity and technical requirements. Less technical methods such as urine color observation and skin turgor testing are subjective and cannot be integrated into a wearable device. Bioelectrical impedance methods are popular but mostly used for estimating total body water with limited accuracy and sensitive to 800 mL–1000 mL change in body fluid levels. We introduce a non-intrusive and simple method of tracking hydration rates that can detect up to 1.30 dB reduction in attenuation when as little as 100 mL of water is consumed. Our results show that galvanic coupled intrabody signal propagation can provide qualitative hydration and dehydration rates in line with changes in an individual’s urine specific gravity and body mass. The real-time changes in galvanic coupled intrabody signal attenuation can be integrated into wearable electronic devices to evaluate body fluid levels on a particular area of interest and can aid diagnosis and treatment of fluid disorders such as lymphoedema.

  3. Deformation and fatigue behavior of hot dip galvanized coatings

    International Nuclear Information System (INIS)

    Camurri, Carlos P.; Benavente, Raul G.; Roa, Isidoro S.; Carrasco, Claudia C.

    2005-01-01

    This paper reports on the results of a study of the effect of static and dynamic stresses on hot dip galvanized coatings on SAE 1020 steel substrates. Galvanizing was performed using baths maintained at 450 deg. C, the zinc containing 0.16% Ti and 0.02% Fe and with Al and Ni in the ranges 0-0.20% and 0-0.30%, respectively. Static three-point bend tests were conducted with applied stresses in the range 428-790 MPa. Dynamic bend-fatigue tests involved stresses in the range 228-578 MPa at a cyclic frequency of 0.25 Hz for up to 700 cycles. The total crack density in the coatings was measured before and after the tests using light optical and electron microscopy. The results showed that the crack density increased as the applied stress increased and crack propagation was promoted perpendicular to the substrate. The number of cycles had no effect on the crack density and propagation at stresses lower than 386 MPa. At higher stresses the number of applied cycles contributed only to crack propagation. It was concluded that the best bath composition for preventing fatigue crack propagation is one that minimized the formation of thinner brittle layers in the galvanized coatings

  4. [Exposure to metal compounds in occupational galvanic processes].

    Science.gov (United States)

    Surgiewicz, Jolanta; Domański, Wojciech

    2006-01-01

    Occupational galvanic processes are provided in more than 600 small and medium enterprises in Poland. Workers who deal with galvanic coating are exposed to heavy metal compounds: tin, silver, copper and zinc. Some of them are carcinogenic, for example, hexavalent chromium compounds, nickel and cadmium compounds. Research covered several tens of workstations involved in chrome, nickel, zinc, tin, silver, copper and cadmium plating. Compounds of metals present in the air were determined: Cr, Ni, Cd, Sn, Ag--by atomic absorption spectrometry with electrothermal atomization (ET-AAS) and Zn--by atomic absorption spectrometry with flame atomization (F-AAS). The biggest metal concentrations--of silver and copper--were found at workstations of copper, brass, cadmium, nickel and chrome plating, conducted at the same time. Significant concentrations of copper were found at workstations of maintenance bathing and neutralizing of sewage. The concentrations of metals did not exceed Polish MAC values. MAC values were not exceeded for carcinogenic chromium(VI), nickel or cadmium, either. In galvanic processes there was no hazard related to single metals or their compounds, even carcinogenic ones. Combined exposure indicators for metals at each workstation did not exceed 1, either. However, if there are even small quantities of carcinogenic agents, health results should always be taken into consideration.

  5. Micro-electrochemical characterization of galvanic corrosion of TA2/316L composite plate

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, X.; Li, X.; Dong, C.; Xiao, K. [Corrosion and Protection Center, University of Science and Technology Beijing (China)

    2011-12-15

    Galvanic corrosion behavior of TA2/316L composite plate was investigated in the solution of 3.5 wt% NaCl by galvanic potential monitoring, scanning localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating micro-electrode (SVME) techniques. The results demonstrated that the pitting corrosion resistance of 316L for the galvanic combination sample is lower, and the coupled current density is higher than for the single 316L sample. It indicates that the galvanic action works on the corrosion behavior of the TA2 titanium alloy/316L stainless steel galvanic combination in sodium chloride solution. The galvanic effect width was determined as 1500 {mu}m. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Galvanic manufacturing in the cities of Russia: potential source of ambient nanoparticles.

    Directory of Open Access Journals (Sweden)

    Kirill S Golokhvast

    Full Text Available Galvanic manufacturing is widely employed and can be found in nearly every average city in Russia. The release and accumulation of different metals (Me, depending on the technology used can be found in the vicinities of galvanic plants. Under the environmental protection act in Russia, the regulations for galvanic manufacturing do not include the regulations and safety standards for ambient ultrafine and nanosized particulate matter (PM. To assess whether Me nanoparticles (NP are among environmental pollutants caused by galvanic manufacturing, the level of Me NP were tested in urban snow samples collected around galvanic enterprises in two cities. Employing transmission electronic microscopy, energy-dispersive X-ray spectroscopy, and a laser diffraction particle size analyzer, we found that the size distribution of tested Me NP was within 10-120 nm range. This is the first study to report that Me NP of Fe, Cr, Pb, Al, Ni, Cu, and Zn were detected around galvanic shop settings.

  7. Vestibular migraine: clinical and epidemiological aspects

    Directory of Open Access Journals (Sweden)

    Ligia Oliveira Gonçalves Morganti

    Full Text Available ABSTRACT INTRODUCTION: Vestibular migraine (VM is one of the most often common diagnoses in neurotology, but only recently has been recognized as a disease. OBJECTIVE: To analyze the clinical and epidemiological profile of patients with VM. METHODS: This was a retrospective, observational, and descriptive study, with analysis of patients' records from an outpatient VM clinic. RESULTS: 94.1% of patients were females and 5.9% were males. The mean age was 46.1 years; 65.6% of patients had had headache for a longer period than dizziness. A correlation was detected between VM symptoms and the menstrual period. 61.53% of patients had auditory symptoms, with tinnitus the most common, although tonal audiometry was normal in 68.51%. Vectoelectronystagmography was normal in 67.34%, 10.20% had hyporeflexia, and 22.44% had vestibular hyperreflexia. Electrophysiological assessment showed no abnormalities in most patients. Fasting plasma glucose and glycemic curve were normal in most patients, while the insulin curve was abnormal in 75%. 82% of individuals with MV showed abnormalities on the metabolism of carbohydrates. CONCLUSION: VM affects predominantly middle-aged women, with migraine headache representing the first symptom, several years before vertigo. Physical, auditory, and vestibular evaluations are usually normal. The most frequent vestibular abnormality was hyperreflexia. Most individuals showed abnormality related to carbohydrate metabolism.

  8. Interaural difference values of vestibular evoked myogenic.

    Directory of Open Access Journals (Sweden)

    Marziyeh Moallemi

    2015-01-01

    Full Text Available Migraine is a neurologic disease, which often is associated with a unilateral headache. Vestibular abnormalities are common in migraine. Vestibular evoked myogenic potentials (VEMPs assess otolith function in particular functional integrity of the saccule and the inferior vestibular nerve. We used VEMP to evaluate if the migraine headache can affect VEMP asymmetry parameters. A total of 25 patients with migraine (22 females and 3 males who were diagnosed according to the criteria of IHS-1988 were enrolled in this cross-sectional study. Control group consisted of 26 healthy participants (18 female and 8 male, without neurotological symptoms and history of migraine. The short tone burst (95 dB nHL, 500 Hz was presented to ears. VEMP was recorded with surface electromyography over the contracted ipsilateral sternocleidomastoid (SCM muscle. Although current results showed that the amplitude ratio is greater in migraine patients than normal group, there was no statistical difference between two groups in mean asymmetry parameters of VEMP. Asymmetry measurements in vestibular evoked myogenic potentials probably are not indicators of unilateral deficient in saccular pathways of migraine patients.

  9. CONTRIBUTION OF THE AUDIOLOGICAL AND VESTIBULAR ASSESSMENT TO THE DIFFERENTIAL AND ETIOLOGICAL DIAGNOSIS OF PERIPHERIC VESTIBULAR SYNDROMES

    Directory of Open Access Journals (Sweden)

    Loreta Ungureanu

    2012-09-01

    Full Text Available Scope of the study: Vestibular pathology is a complex one, requiring a minute clinical evaluation, as well as numerous paraclinical investigations. The present study analyzes the contribution of the modern methods of vestibular and auditive investigation to the diagnosis of dizziness. Materials and method: The results of the investigations performed on 84 patients with peripheric vestibular syndrome, on whom a complete audiological and vestibular assessment had been also made, have been retrospectively analyzed. Results: Anamnestic data and the results of evaluation permitted classification of peripheric vestibular pathology according to topo-lesional and etiological criteria. The most frequently diagnosed diseases were: benign paroxysmal positional vertigo, Ménière syndrome and vestibular neuronitis. Conclusions: Testing of the vestibulo-ocular and vestibulo-spinal reflexes through videonystagmoscopy and, respectively, computerized dynamic posturography, besides tonal vocal audiometry and precocious auditive potentials, is especially important for a positive diagnosis and etiological differentiation of vestibular syndromes.

  10. Formal concept analysis applied to the prediction of additives for galvanizing process

    Directory of Open Access Journals (Sweden)

    J. Klimeš

    2010-04-01

    Full Text Available Formal concept analysis is a new mathematical approach to data analysis, data mining and to discavering patterns in data. The result of the application of the formal concept analysis method to the behavior of the galvanizing of rimmed steel is presented. Effects of additives in the galvanizing process have been correlated to the chemical element properties of the additives. This model may also help to design new alloys as additives in the galvanizing process.

  11. Directional plasticity rapidly improves 3D vestibulo-ocular reflex alignment in monkeys using a multichannel vestibular prosthesis.

    Science.gov (United States)

    Dai, Chenkai; Fridman, Gene Y; Chiang, Bryce; Rahman, Mehdi A; Ahn, Joong Ho; Davidovics, Natan S; Della Santina, Charles C

    2013-12-01

    Bilateral loss of vestibular sensation can be disabling. We have shown that a multichannel vestibular prosthesis (MVP) can partly restore vestibular sensation as evidenced by improvements in the 3-dimensional angular vestibulo-ocular reflex (3D VOR). However, a key challenge is to minimize misalignment between the axes of eye and head rotation, which is apparently caused by current spread beyond each electrode's targeted nerve branch. We recently reported that rodents wearing a MVP markedly improve 3D VOR alignment during the first week after MVP activation, probably through the same central nervous system adaptive mechanisms that mediate cross-axis adaptation over time in normal individuals wearing prisms that cause visual scene movement about an axis different than the axis of head rotation. We hypothesized that rhesus monkeys would exhibit similar improvements with continuous prosthetic stimulation over time. We created bilateral vestibular deficiency in four rhesus monkeys via intratympanic injection of gentamicin. A MVP was mounted to the cranium, and eye movements in response to whole-body passive rotation in darkness were measured repeatedly over 1 week of continuous head motion-modulated prosthetic electrical stimulation. 3D VOR responses to whole-body rotations about each semicircular canal axis were measured on days 1, 3, and 7 of chronic stimulation. Horizontal VOR gain during 1 Hz, 50 °/s peak whole-body rotations before the prosthesis was turned on was prosthetic stimulation under normal diurnal lighting. Similar improvements were noted for all animals, all three axes of rotation tested, for all sinusoidal frequencies tested (0.05-5 Hz), and for high-acceleration transient rotations. VOR asymmetry changes did not reach statistical significance, although they did trend toward slight improvement over time. Prior studies had already shown that directional plasticity reduces misalignment when a subject with normal labyrinths views abnormal visual scene

  12. Adaptation of postural recovery responses to a vestibular sensory illusion in individuals with Parkinson disease and healthy controls.

    Science.gov (United States)

    Lester, Mark E; Cavanaugh, James T; Foreman, K Bo; Shaffer, Scott W; Marcus, Robin; Dibble, Leland E

    2017-10-01

    The ability to adapt postural responses to sensory illusions diminishes with age and is further impaired by Parkinson disease. However, limited information exists regarding training-related adaptions of sensory reweighting in these populations. This study sought to determine whether Parkinson disease or age would differentially affect acute postural recovery or adaptive postural responses to novel or repeated exposure to sensory illusions using galvanic vestibular stimulation during quiet stance. Acutely, individuals with Parkinson disease demonstrated larger center of pressure coefficient of variation compared to controls. Unlike individuals with Parkinson disease and asymptomatic older adults, healthy young adults acutely demonstrated a reduction in Sample Entropy to the sensory illusion. Following a period of consolidation Sample Entropy increased in the healthy young group, which coincided with a decreased center of pressure coefficient of variation. Similar changes were not observed in the Parkinson disease or older adult groups. Taken together, these results suggest that young adults learn to adapt to vestibular illusion in a more robust manner than older adults or those with Parkinson disease. Further investigation into the nature of this adaptive difference is warranted. Published by Elsevier Ltd.

  13. New insights into pathophysiology of vestibular migraine

    Directory of Open Access Journals (Sweden)

    Juan Manuel Espinosa-Sanchez

    2015-02-01

    Full Text Available Vestibular migraine (VM is a common disorder in which genetic, epigenetic and environmental factors probably contribute to its development. The pathophysiology of VM is unknown; nevertheless in the last few years, several studies are contributing to understand the neurophysiological pathways involved in VM. The current hypotheses are mostly based on the knowledge of migraine itself. The evidence of trigeminal innervation of the labyrinth vessels and the localization of vasoactive neuropeptides in the perivascular afferent terminals of these trigeminal fibers support the involvement of the trigemino-vascular system. The neurogenic inflammation triggered by activation of the trigeminal-vestibulocochlear reflex, with the subsequent inner ear plasma protein extravasation and the release of inflammatory mediators, can contribute to a sustained activation and sensitization of the trigeminal primary afferent neurons explaining VM symptoms. The reciprocal connections between brainstem vestibular nuclei and the structures that modulate trigeminal nociceptive inputs (rostral ventromedial medulla, ventrolateral periaqueductal grey, locus coeruleus and nucleus raphe magnus are critical to understand the pathophysiology of VM. Although cortical spreading depression can affect cortical areas involved in processing vestibular information, functional neuroimaging techniques suggest a dysmodulation in the multimodal sensory integration and processing of vestibular and nociceptive information, resulting from a vestibulo-thalamo-cortical dysfunction, as the pathogenic mechanism underlying VM. The elevated prevalence of VM suggests that multiple functional variants may confer a genetic susceptibility leading to a dysregulation of excitatory-inhibitory balance in brain structures involved in the processing of sensory information, vestibular inputs and pain. The interactions among several functional and structural neural networks could explain the pathogenic

  14. Alexander von Humboldt: galvanism, animal electricity, and self-experimentation part 1: formative years, naturphilosophie, and galvanism.

    Science.gov (United States)

    Finger, Stanley; Piccolino, Marco; Stahnisch, Frank W

    2013-01-01

    During the 1790s, Alexander von Humboldt (1769-1859), who showed an early interest in many facets of natural philosophy and natural history, delved into the controversial subject of galvanism and animal electricity, hoping to shed light on the basic nature of the nerve force. He was motivated by his broad worldview, the experiments of Luigi Galvani, who favored animal electricity in more than a few specialized fishes, and the thinking of Alessandro Volta, who accepted specialized fish electricity but was not willing to generalize to other animals, thinking Galvani's frog experiments flawed by his use of metals. Differing from many German Naturphilosophen, who shunned "violent" experiments, the newest instruments, and detailed measurement, Humboldt conducted thousands of galvanic experiments on animals and animal parts, as well as many on his own body, some of which caused him great pain. He interpreted his results as supporting some but not all of the claims made by both Galvani and Volta. Notably, because of certain negative findings and phenomenological differences, he remained skeptical about the intrinsic animal force being qualitatively identical to true electricity. Hence, he referred to a "galvanic force," not animal electricity, in his letters and publications, a theoretical position he would abandon with Volta's help early in the new century.

  15. Propiedades de transporte de una superred de grafeno tipo sinusoidal

    Directory of Open Access Journals (Sweden)

    J. A. Briones-Torres

    2015-01-01

    Full Text Available En este trabajo usamos el método de la matriz de transferencia para estudiar el tunelamiento de los electrones de Dirac a través de superredes en grafeno. Consideramos una superred con potencial sinusoidal o polaridad invertida, para ello consideramos dos maneras de crearla, una por medio de sustratos mixtos junto con la aplicación de un campo perpendicular sobre el sustrato de Óxido de Silicio (SiO2, la otra por medio de potenciales alternados aplicados perpendicularmente sobre la sábana de grafeno. Calculamos las propiedades de transmisión, transporte y estructura electrónica, variando diferentes parámetros como ángulo de incidencia, anchos de pozos y barreras y diferente número de barreras. Se encontró (1 el importante papel que juega el efecto Klein en tales estructuras, (2 las propiedades de transmisión y transporte presentan cierta simetría respecto del origen de la energía, y (3 el carácter sinusoidal del sistema trae consigo una baja en el nivel de energía de las subbandas en el espectro de estados acotados, además las degenera y origina que la apertura-cierre de las minibandas sea en el mismo nivel de energía.

  16. Observation of Sinusoidal Voltage Behaviour in Silver Doped YBCO

    Science.gov (United States)

    Altinkok, Atilgan; Olutas, Murat; Kilic, Kivilcim; Kilic, Atilla

    The influence of bi-directional square wave (BSW) current was investigated on the evolution of the V - t curves at different periods (P) , temperatures and external magnetic fields. It was observed that slow transport relaxation measurements result in regular sinusoidal voltage oscillations which were discussed mainly in terms of the dynamic competition between pinning and depinning.The symmetry in the voltage oscillations was attributed to the elastic coupling between the flux lines and the pinning centers along grain boundaries and partly inside the grains. This case was also correlated to the equality between flux entry and exit along the YBCO/Ag sample during regular oscillations. It was shown that the voltage oscillations can be described well by an empirical expression V (t) sin(wt + φ) . We found that the phase angle φgenerally takes different values for the repetitive oscillations. Fast Fourier Transform analysis of the V - t oscillations showed that the oscillation period is comparable to that (PI) of the BSW current. This finding suggests a physical mechanism associated with charge density waves (CDWs), and, indeed, the weakly pinned flux line system in YBCO/Ag resembles the general behavior of CDWs. At certain values of PI, amplitude of BSW current, H and T, the YBCO/Ag sample behaves like a double-integrator, since it converts the BSW current to sinusoidal voltage oscillations in time.

  17. Removal of Stationary Sinusoidal Noise from Random Vibration Signals.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Brian; Cap, Jerome S.

    2018-02-01

    In random vibration environments, sinusoidal line noise may appear in the vibration signal and can affect analysis of the resulting data. We studied two methods which remove stationary sine tones from random noise: a matrix inversion algorithm and a chirp-z transform algorithm. In addition, we developed new methods to determine the frequency of the tonal noise. The results show that both of the removal methods can eliminate sine tones in prefabricated random vibration data when the sine-to-random ratio is at least 0.25. For smaller ratios down to 0.02 only the matrix inversion technique can remove the tones, but the metrics to evaluate its effectiveness also degrade. We also found that using fast Fourier transforms best identified the tonal noise, and determined that band-pass-filtering the signals prior to the process improved sine removal. When applied to actual vibration test data, the methods were not as effective at removing harmonic tones, which we believe to be a result of mixed-phase sinusoidal noise.

  18. Mapping surface properties of sinusoidal roughness standards by TPM

    International Nuclear Information System (INIS)

    Liu, X; Rubert, P

    2005-01-01

    We report our investigation on the surface properties of sinusoidal roughness standards made from pure electroformed nickel. Two specimens having a sinusoidal profile with nominal R a of 0.36 μm and a peak spacing of 25 μm are chosen for this investigation. One specimen is further treated with a hard protective coating of nickel-boron. The surface topography, friction, hardness and Young's modulus of the specimens were measured by a novel instrument, the multi-function Tribological Probe Microscope (TPM). The results show that hardness of these two specimens is 14.1 GPa for uncoated specimen and 25.7 GPa for the coated one, while the Young's modulus is 188 GPa and 225 GPa, respectively. The ramping force was set to 3mN for both the specimens and the effect of the tip penetration was investigated by comparing the topography measurements before and after hardness mapping. It has been found out that there is no significant change in the averaged profiles over the scanned area, which indicates the topography distortion seen in the multi-function mapping, is recoverable. Cross correlation between topography and its corresponding hardness/Young's modulus has been carried out and the result will be discussed in the paper

  19. Hydraulic testing in granite using the sinusoidal variation of pressure

    International Nuclear Information System (INIS)

    Black, J.H.; Holmes, D.C.; Noy, D.J.

    1982-09-01

    Access to two boreholes at the Carwynnen test site in Cornwall enabled the trial of a number of innovative approaches to the hydrogeology of fractured crystalline rock. These methods ranged from the use of seisviewer data to measure the orientation of fractures to the use of the sinusoidal pressure technique to measure directional hydraulic diffusivity. The testing began with a short programme of site investigation consisting of borehole caliper and seisviewer logging followed by some single borehole hydraulic tests. The single borehole hydraulic testing was designed to assess whether the available boreholes and adjacent rock were suitable for testing using the sinusoidal method. The main testing methods were slug and pulse tests and were analysed using the fissured porous medium analysis proposed in Barker and Black (1983). Derived hydraulic conductivity (K) ranged from 2 x 10 -12 m/sec to 5 x 10 -7 m/sec with one near-surface zone of high K being perceived in both boreholes. The results were of the form which is typical of fractured rock and indicated a combination of high fracture frequency and permeable granite matrix. The results are described and discussed. (author)

  20. Galvanic corrosion of metals and coatings when coupled to uranium in severe environments

    International Nuclear Information System (INIS)

    Winkle, J.R.; Childs, E.L.

    1982-01-01

    The results of galvanic testing were varied in each environment. The position of metals in the galvanic series was not fixed, but changed with environment. In all cases where high general and galvanic corrosion rates were observed, the conditions of potential, pH, and impurity content could be correlated with regions of oxide surface film instability outlined by Pourbaix Diagrams. The majority of the severe corrosion reactions were observed in the acidic environment, although a few were noted in the caustic environment. The presence of chlorides tended to enhance galvanic corrosion rates at the neutral environment. 10 tables

  1. Studies into the Factors that Affects the Service Integrity of Galvanizing Kettle

    OpenAIRE

    Muhammed Olawale Hakeem AMUDA; Ayisat Adebukunola LAWAL; Olakunle Wasiu SUBAIR; Ganiyu Ishola LAWAL

    2008-01-01

    The finding of studies into the factors that affects optimal performance of galvanizing kettle is presented in this paper. The production schedule and history of a failed galvanizing kettle for 3-consecutively years in a hot-dip galvanizing industry was collated and analyzed. The analysis of the collated data revealed that average galvanizing temperatures for the 3-year under review were 483.9°C (2003), 482.25°C (2004) and 482°C (2005) respectively. The amount of flux, and dross produced in t...

  2. Vestibular evaluation in children with otitis media with effusion.

    Science.gov (United States)

    Kolkaila, E A; Emara, A A; Gabr, T A

    2015-04-01

    Fifty per cent of children with serous otitis media may have some balance disturbances. To evaluate vestibular function in children with otitis media with effusion. The control group comprised 25 children with bilateral normal hearing and middle-ear function. The study group consisted of 30 children with bilateral otitis media with effusion; these were divided into 2 subgroups according to air-bone gap size. Measures included the Arabic Dizziness Handicap Inventory, an imbalance evaluation sheet for children, vestibular bedside tests for children, and air- and bone-conducted vestibular-evoked myogenic potential testing. Arabic Dizziness Handicap Inventory scores and some vestibular bedside test results were significantly abnormal, with normal video-nystagmography results, in children with otitis media with effusion. Air-conducted vestibular-evoked myogenic potentials were recorded in 73 per cent of children with otitis media with effusion, with significantly delayed latencies. Bone-conducted vestibular-evoked myogenic potentials were successfully detected in 100 per cent of children with otitis media with effusion with similar results to the control group. The Arabic Dizziness Handicap Inventory and vestibular bedside tests are valuable tools for detecting vestibular impairment in children. Bone-conducted vestibular-evoked myogenic potentials are useful for vestibular system evaluation.

  3. Sinusoidal voltage protocols for rapid characterisation of ion channel kinetics.

    Science.gov (United States)

    Beattie, Kylie A; Hill, Adam P; Bardenet, Rémi; Cui, Yi; Vandenberg, Jamie I; Gavaghan, David J; de Boer, Teun P; Mirams, Gary R

    2018-03-24

    Ion current kinetics are commonly represented by current-voltage relationships, time constant-voltage relationships and subsequently mathematical models fitted to these. These experiments take substantial time, which means they are rarely performed in the same cell. Rather than traditional square-wave voltage clamps, we fitted a model to the current evoked by a novel sum-of-sinusoids voltage clamp that was only 8 s long. Short protocols that can be performed multiple times within a single cell will offer many new opportunities to measure how ion current kinetics are affected by changing conditions. The new model predicts the current under traditional square-wave protocols well, with better predictions of underlying currents than literature models. The current under a novel physiologically relevant series of action potential clamps is predicted extremely well. The short sinusoidal protocols allow a model to be fully fitted to individual cells, allowing us to examine cell-cell variability in current kinetics for the first time. Understanding the roles of ion currents is crucial to predict the action of pharmaceuticals and mutations in different scenarios, and thereby to guide clinical interventions in the heart, brain and other electrophysiological systems. Our ability to predict how ion currents contribute to cellular electrophysiology is in turn critically dependent on our characterisation of ion channel kinetics - the voltage-dependent rates of transition between open, closed and inactivated channel states. We present a new method for rapidly exploring and characterising ion channel kinetics, applying it to the hERG potassium channel as an example, with the aim of generating a quantitatively predictive representation of the ion current. We fitted a mathematical model to currents evoked by a novel 8 second sinusoidal voltage clamp in CHO cells overexpressing hERG1a. The model was then used to predict over 5 minutes of recordings in the same cell in response to

  4. Evaluation of postural control in unilateral vestibular hypofunction

    Directory of Open Access Journals (Sweden)

    Rafaela Maia Quitschal

    2014-07-01

    Full Text Available INTRODUCTION: Patients with vestibular hypofunction, a typical finding in peripheral vestibular disorders, show body balance alterations. OBJECTIVE: To evaluate the postural control of patients with vertigo and unilateral vestibular hypofunction. METHOD: This is a clinical cross-sectional study. Twenty-five patients with vertigo and unilateral vestibular hypofunction and a homogeneous control group consisting of 32 healthy individuals were submitted to a neurotological evaluation including the Tetrax Interactive Balance System posturography in eight different sensory conditions. RESULTS: For different positions, vertiginous patients with unilateral vestibular hypofunction showed significantly higher values of general stability index, weight distribution index, right/left and tool/heel synchronizations, Fourier transformation index and fall index than controls. CONCLUSION: Increased values in the indices of weight distribution, right/left and tool/heel synchronizations, Fourier transformation and fall risk characterize the impairment of postural control in patients with vertigo and unilateral vestibular hypofunction.

  5. Current and Voltage Mode Multiphase Sinusoidal Oscillators Using CBTAs

    Directory of Open Access Journals (Sweden)

    M. Sagbas

    2013-04-01

    Full Text Available Current-mode (CM and voltage-mode (VM multiphase sinusoidal oscillator (MSO structures using current backward transconductance amplifier (CBTA are proposed. The proposed oscillators can generate n current or voltage signals (n being even or odd equally spaced in phase. n+1 CBTAs, n grounded capacitors and a grounded resistor are used for nth-state oscillator. The oscillation frequency can be independently controlled through transconductance (gm of the CBTAs which are adjustable via their bias currents. The effects caused by the non-ideality of the CBTA on the oscillation frequency and condition have been analyzed. The performance of the proposed circuits is demonstrated on third-stage and fifth-stage MSOs by using PSPICE simulations based on the 0.25 µm TSMC level-7 CMOS technology parameters.

  6. Phonological awareness and sinusoidal amplitude modulation in phonological dislexia.

    Science.gov (United States)

    Peñaloza-López, Yolanda; Herrera-Rangel, Aline; Pérez-Ruiz, Santiago J; Poblano, Adrián

    2016-04-01

    Dyslexia is the difficulty of children in learning to read and write as results of neurological deficiencies. The objective was to test the Phonological awareness (PA) and Sinusoidal amplitude modulation (SAM) threshold in children with Phonological dyslexia (PD). We performed a case-control, analytic, cross sectional study. We studied 14 children with PD and 14 control children from 7 to 11 years of age, by means of PA measurement and by SAM test. The mean age of dyslexic children was 8.39 years and in the control group was 8.15. Children with PD exhibited inadequate skills in PA, and SAM. We found significant correlations between PA and SAM at 4 Hertz frequency, and calculated regression equations that predicts between one-fourth and one-third of variance of measurements. Alterations in PA and SAM found can help to explain basis of deficient language processing exhibited by children with PD.

  7. New Realizations of Single OTRA-Based Sinusoidal Oscillators

    Directory of Open Access Journals (Sweden)

    Hung-Chun Chien

    2014-01-01

    Full Text Available This study proposes three new sinusoidal oscillators based on an operational transresistance amplifier (OTRA. Each of the proposed oscillator circuits consists of one OTRA combined with a few passive components. The first circuit is an OTRA-based minimum RC oscillator. The second circuit is capable of providing independent control on the condition of oscillation without affecting the oscillation frequency. The third circuit exhibits independent control of oscillation frequency through a capacitor. This study first introduces the OTRA and the related formulations of the proposed oscillator circuits, and then discusses the nonideal effects, sensitivity analyses, and frequency stability of the presented circuits. The proposed oscillators exhibit low sensitivities and good frequency stability. Because the presented circuits feature low impedance output, they can be connected directly to the next stage without cascading additional voltage buffers. HSPICE simulations and experimental results confirm the feasibility of the new oscillator circuits.

  8. One-dimensional plasma photonic crystals with sinusoidal densities

    International Nuclear Information System (INIS)

    Qi, L.; Shang, L.; Zhang, S.

    2014-01-01

    Properties of electromagnetic waves with normal and oblique incidence have been studied for one-dimensional plasma layers with sinusoidal densities. Wave transmittance as a function of wave frequency exhibits photonic band gaps characteristic of photonic crystals. For periodic structures, increasing collision frequency is demonstrated to lead to greater absorption, increasing the modulation factor enlarges the gap width, and increasing incidence angle can change the gap locations of the two polarizations. If a defect layer is introduced by inserting a new plasma layer in the center, a defect mode may appear within the gap. Periodic number, collision frequency, and modulation factor can affect magnitude of the defect mode. The incidence angle enables the frequency to be tuned. Defect layer thickness affects both frequency and number of defect modes. These results may provide theoretical guidance in designing tunable narrow-band filters

  9. Response of resonant gravitational wave detectors to damped sinusoid signals

    International Nuclear Information System (INIS)

    Pai, A; Celsi, C; Pallottino, G V; D'Antonio, S; Astone, P

    2007-01-01

    Till date, the search for burst signals with resonant gravitational wave (GW) detectors has been done using the δ-function approximation for the signal, which was reasonable due to the very small bandwidth of these detectors. However, now with increased bandwidth (of the order of 10 or more Hz) and with the possibility of comparing results with interferometric GW detectors (broad-band), it is very important to exploit the resonant detectors' capability to detect also signals with specific wave shapes. As a first step, we present a study of the response of resonant GW detectors to damped sinusoids with given frequency and decay time and report on the development of a filter matched to these signals. This study is a preliminary step towards the comprehension of the detector response and of the filtering for signals such as the excitation of stellar quasi-normal modes

  10. Vestibular-ocular accommodation reflex in man

    Science.gov (United States)

    Clark, B.; Randle, R. J.; Stewart, J. D.

    1975-01-01

    Stimulation of the vestibular system by angular acceleration produces widespread sensory and motor effects. The present paper studies a motor effect which has not been reported in the literature, i.e., the influence of rotary acceleration of the body on ocular accommodation. The accommodation of 10 young men was recorded before and after a high-level deceleration to zero velocity following 30 sec of rotating. Accommodation was recorded continuously on an infrared optometer for 110 sec under two conditions: while the subjects observed a target set at the far point, and while they viewed the same target through a 0.3-mm pinhole. Stimulation by high-level rotary deceleration produced positive accommodation or a pseudomyopia under both conditions, but the positive accommodation was substantially greater and lasted much longer during fixation through the pinhole. It is hypothesized that this increase in accommodation is a result of a vestibular-ocular accommodation reflex.

  11. Corrosion behaviour and biocorrosion of galvanized steel water distribution systems.

    Science.gov (United States)

    Delaunois, F; Tosar, F; Vitry, V

    2014-06-01

    Galvanized steel tubes are a popular mean for water distribution systems but suffer from corrosion despite their zinc or zinc alloy coatings. First, the quality of hot-dip galvanized (HDG) coatings was studied. Their microstructure, defects, and common types of corrosion were observed. It was shown that many manufactured tubes do not reach European standard (NBN EN 10240), which is the cause of several corrosion problems. The average thickness of zinc layer was found at 41μm against 55μm prescribed by the European standard. However, lack of quality, together with the usual corrosion types known for HDG steel tubes was not sufficient to explain the high corrosion rate (reaching 20μm per year versus 10μm/y for common corrosion types). Electrochemical tests were also performed to understand the corrosion behaviours occurring in galvanized steel tubes. Results have shown that the limiting step was oxygen diffusion, favouring the growth of anaerobic bacteria in steel tubes. EDS analysis was carried out on corroded coatings and has shown the presence of sulphur inside deposits, suggesting the likely bacterial activity. Therefore biocorrosion effects have been investigated. Actually sulphate reducing bacteria (SRB) can reduce sulphate contained in water to hydrogen sulphide (H2S), causing the formation of metal sulphides. Although microbial corrosion is well-known in sea water, it is less investigated in supply water. Thus, an experimental water main was kept in operation for 6months. SRB were detected by BART tests in the test water main. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Plasma characteristics in non-sinusoidally excited CCP discharges

    Science.gov (United States)

    Lafleur, Trevor; Booth, Jean-Paul

    2012-10-01

    Using particle-in-cell (PIC) simulations we perform a characterization of the plasma response to positive pulse-type voltage excitations (with a repetition frequency of 13.56 MHz) in a geometrically symmetric CCP reactor (with a gap length of 2 cm) operated with argon (for pressures between 20-500 mTorr). Use of these non-sinusoidal waveforms generates an electrical asymmetry effect in the system, which necessitates the formation of a DC bias. This DC bias, together with the shape of the voltage waveforms used, produces a number of new phenomena that are not present in typical sinusoidal discharges: (1) the plasma density and ion flux can be increased as the pulse width is reduced, (2) a significant asymmetry in the ion fluxes to the powered and grounded electrodes develops as the pressure increases, (3) the average ion energy striking the grounded electrode remains low and approximately constant as the pulse width decreases, and (4) the sheath at the grounded electrode never fully collapses; electrons are no longer lost in sharp pulses, but escape essentially throughout the rf cycle. Effects (1) and (3) above offer the possibility for a new form of control in these types of discharges, where the ion flux can be increased while the ion energy on the grounded electrode can be kept small and essentially constant. This effect has recently been exploited to control the crystallinity of silicon thin films [1], where the low ion bombarding energy was found to improve the quality of films grown. [4pt] [1] Johnson E V, Pouliquen S, Delattre P A, and Booth J P, J. Non-Cryst. Solids 2012, in press.

  13. Nematic liquid crystals on sinusoidal channels: the zigzag instability.

    Science.gov (United States)

    Silvestre, Nuno M; Romero-Enrique, Jose M; Telo da Gama, Margarida M

    2017-01-11

    Substrates which are chemically or topographically patterned induce a variety of liquid crystal textures. The response of the liquid crystal to competing surface orientations, typical of patterned substrates, is determined by the anisotropy of the elastic constants and the interplay of the relevant lengths scales, such as the correlation length and the surface geometrical parameters. Transitions between different textures, usually with different symmetries, may occur under a wide range of conditions. We use the Landau-de Gennes free energy to investigate the texture of nematics in sinusoidal channels with parallel anchoring bounded by nematic-air interfaces that favour perpendicular (hometropic) anchoring. In micron size channels 5CB was observed to exhibit a non-trivial texture characterized by a disclination line, within the channel, which is broken into a zigzag pattern. Our calculations reveal that when the elastic anisotropy of the nematic does not favour twist distortions the defect is a straight disclination line that runs along the channel, which breaks into a zigzag pattern with a characteristic period, when the twist elastic constant becomes sufficiently small when compared to the splay and bend constants. The transition occurs through a twist instability that drives the defect line to rotate from its original position. The interplay between the energetically favourable twist distortions that induce the defect rotation and the liquid crystal anchoring at the surfaces leads to the zigzag pattern. We investigate in detail the dependence of the periodicity of the zigzag pattern on the geometrical parameters of the sinusoidal channels, which in line with the experimental results is found to be non-linear.

  14. Representative Sinusoids for Hepatic Four-Scale Pharmacokinetics Simulations.

    Directory of Open Access Journals (Sweden)

    Lars Ole Schwen

    Full Text Available The mammalian liver plays a key role for metabolism and detoxification of xenobiotics in the body. The corresponding biochemical processes are typically subject to spatial variations at different length scales. Zonal enzyme expression along sinusoids leads to zonated metabolization already in the healthy state. Pathological states of the liver may involve liver cells affected in a zonated manner or heterogeneously across the whole organ. This spatial heterogeneity, however, cannot be described by most computational models which usually consider the liver as a homogeneous, well-stirred organ. The goal of this article is to present a methodology to extend whole-body pharmacokinetics models by a detailed liver model, combining different modeling approaches from the literature. This approach results in an integrated four-scale model, from single cells via sinusoids and the organ to the whole organism, capable of mechanistically representing metabolization inhomogeneity in livers at different spatial scales. Moreover, the model shows circulatory mixing effects due to a delayed recirculation through the surrounding organism. To show that this approach is generally applicable for different physiological processes, we show three applications as proofs of concept, covering a range of species, compounds, and diseased states: clearance of midazolam in steatotic human livers, clearance of caffeine in mouse livers regenerating from necrosis, and a parameter study on the impact of different cell entities on insulin uptake in mouse livers. The examples illustrate how variations only discernible at the local scale influence substance distribution in the plasma at the whole-body level. In particular, our results show that simultaneously considering variations at all relevant spatial scales may be necessary to understand their impact on observations at the organism scale.

  15. Sinusoidal Obstruction Syndrome (Hepatic Veno-Occlusive Disease)

    Science.gov (United States)

    Fan, Cathy Q.; Crawford, James M.

    2014-01-01

    Hepatic sinusoidal obstruction syndrome (SOS) is an obliterative venulitis of the terminal hepatic venules, which in its more severe forms imparts a high risk of mortality. SOS, also known as veno-occlusive disease (VOD), occurs as a result of cytoreductive therapy prior to hematopoietic stem cell transplantation (HSCT), following oxaliplatin-containing adjuvant or neoadjuvant chemotherapy for colorectal carcinoma metastatic to the liver and treated by partial hepatectomy, in patients taking pyrrolizidine alkaloid-containing herbal remedies, and in other particular settings such as the autosomal recessive condition of veno-occlusive disease with immunodeficiency (VODI). A central pathogenic event is toxic destruction of hepatic sinusoidal endothelial cells (SEC), with sloughing and downstream occlusion of terminal hepatic venules. Contributing factors are SEC glutathione depletion, nitric oxide depletion, increased intrahepatic expression of matrix metalloproteinases and vascular endothelial growth factor (VEGF), and activation of clotting factors. The clinical presentation of SOS includes jaundice, development of right upper-quadrant pain and tender hepatomegaly, ascites, and unexplained weight gain. Owing to the potentially critical condition of these patients, transjugular biopsy may be the preferred route for liver biopsy to exclude other potential causes of liver dysfunction and to establish a diagnosis of SOS. Treatment includes rigorous fluid management so as to avoid excessive fluid overload while avoiding too rapid diuresis or pericentesis, potential use of pharmaceutics such as defibrotide, coagulolytic agents, or methylprednisolone, and liver transplantation. Proposed strategies for prevention and prophylaxis include reduced-intensity conditioning radiation for HSCT, treatment with ursodeoxycholic acid, and inclusion of bevacizumab with oxaliplatin-based chemotherapeutic regimes. While significant progress has been made in understanding the pathogenesis

  16. Vestibular involvement in adults with HIV/AIDS.

    Science.gov (United States)

    Heinze, Barbara M; Vinck, Bart M; Hofmeyr, Louis M; Swanepoel, De Wet

    2014-04-01

    HIV/AIDS is responsible for widespread clinical manifestations involving the head, and neck. The prevalence and nature of vestibular involvement is still largely unknown. This study, aimed to describe and compare the occurrence and nature of vestibular involvement among a group of, adults infected with HIV compared to a control group. It also aimed to compare the vestibular function, of symptomatic and asymptomatic HIV positive adults who receive antiretroviral (ARV) therapies to, subjects not receiving ARV. A cross-sectional study was conducted on 53 adults (29 male, 24 female, aged 23-49 years, mean=38.5, SD=4.4) infected with HIV, compared to a control group of 38 HIV negative adults (18, male, 20 female, aged 20-49 years, mean=36.9, SD=8.2). A structured interview probed the subjective, perception of vestibular symptoms. Medical records were reviewed for CD4+ cell counts and the use of, ARV medication. An otologic assessment and a comprehensive vestibular assessment (bedside, assessments, vestibular evoked myogenic potentials, ocular motor and positional tests and bithermal, caloric irrigation) were conducted. Vestibular involvement occurred in 79.2% of subjects with HIV in all categories of disease, progression, compared to 18.4% in those without HIV. Vestibular involvement increased from 18.9% in CDC category 1 to 30.2% in category 2. Vestibular involvement was 30.1% in category 3. There were, vestibular involvement in 35.9% of symptomatic HIV positive subjects, and 41.5% in asymptomatic, HIV positive subjects. There was no significant difference in the occurrence of vestibular involvement, in subjects receiving ARV therapies compared to those not receiving ARV therapies (p=.914; chi-square, test). The odds ratio indicates that individuals with HIV have a 16.61 times higher risk of developing, vestibular involvement during their lifetime of living with the disease and that it may occur despite, being asymptomatic. Vestibular involvement was significantly more

  17. Bedside examination for vestibular screening in occupational medicine.

    Science.gov (United States)

    Zamysłowska-Szmytke, Ewa; Szostek-Rogula, Sylwia; Śliwińska-Kowalska, Mariola

    2015-01-01

    The aim of the study was to assess the usefulness of bedside examination for screening of vestibular and balance system for occupational medicine purposes. Study group comprised 165 patients referred to Audiology and Phoniatric Clinic due to vestibular and/or balance problems. Caloric canal paresis of 19% was the cut off value to divide patients into 43 caloric-positive vestibular subjects and 122 caloric-negative patients. The latter group comprised 79 subjects revealing abnormalities of videonystagmographic (VNG) oculomotor tests (central group) and 43 subjects with normal VNG. Vestibular and balance symptoms were collected. Five tests were included to bedside examination: Romberg and Unterberger tests, Head Impulse Test (HIT), Dynamic Visual Acuity (DVA) and gaze nystagmus assessment. Vestibular and balance symptoms were reported by 82% of vestibular, 73% of central and 40% of VNG-normal patients. Thirteen out of 18 VNG-normal but symptomatic subjects (73%) had abnormal tests in clinical assessment. The sensitivity of bedside test set for vestibular pathology was 88% as compared to caloric test and 68% for central pathology as compared to VNG oculomotor tests. The combination of 5 bedside tests reveal satisfactory sensitivity to detect vestibular abnormalities. Bedside examination abnormalities are highly correlated with vestibular/balance symptoms, regardless the normal results of VNG. Thus, this method should be recommended for occupational medicine purposes. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  18. Bedside examination for vestibular screening in occupational medicine

    Directory of Open Access Journals (Sweden)

    Ewa Zamysłowska-Szmytke

    2015-04-01

    Full Text Available Objectives: The aim of the study was to assess the usefulness of bedside examination for screening of vestibular and balance system for occupational medicine purposes. Study group comprised 165 patients referred to Audiology and Phoniatric Clinic due to vestibular and/or balance problems. Caloric canal paresis of 19% was the cut off value to divide patients into 43 caloric-positive vestibular subjects and 122 caloric-negative patients. The latter group comprised 79 subjects revealing abnormalities of videonystagmographic (VNG oculomotor tests (central group and 43 subjects with normal VNG. Material and Methods: Vestibular and balance symptoms were collected. Five tests were included to bedside examination: Romberg and Unterberger tests, Head Impulse Test (HIT, Dynamic Visual Acuity (DVA and gaze nystagmus assessment. Results: Vestibular and balance symptoms were reported by 82% of vestibular, 73% of central and 40% of VNG-normal patients. Thirteen out of 18 VNG-normal but symptomatic subjects (73% had abnormal tests in clinical assessment. The sensitivity of bedside test set for vestibular pathology was 88% as compared to caloric test and 68% for central pathology as compared to VNG oculomotor tests. Conclusions: The combination of 5 bedside tests reveal satisfactory sensitivity to detect vestibular abnormalities. Bedside examination abnormalities are highly correlated with vestibular/balance symptoms, regardless the normal results of VNG. Thus, this method should be recommended for occupational medicine purposes.

  19. Corrosion protection of galvanized steels by silane-based treatments

    Science.gov (United States)

    Yuan, Wei

    The possibility of using silane coupling agents as replacements for chromate treatments was investigated on galvanized steel substrates. In order to understand the influence of deposition parameters on silane film formation, pure zinc substrates were first used as a model for galvanized steel to study the interaction between silane coupling agents and zinc surfaces. The silane films formed on pure zinc substrates from aqueous solutions were characterized by ellipsometry, contact angle measurements, reflection absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. The deposition parameters studied include solution concentration, solution dipping time and pH value of the applied solution. It appears that silane film formation involved a true equilibrium of hydrolysis and condensation reactions in aqueous solutions. It has been found that the silane film thickness obtained depends primarily on the solution concentration and is almost independent of the solution dipping time. The molecular orientation of applied silane films is determined by the pH value of applied silane solutions and the isoelectric point of metal substrates. The deposition window in terms of pH value for zinc substrates is between 6.0 and 9.0. The total surface energy of the silane-coated pure zinc substrates decreases with film aging time, the decrease rate, however, is determined by the nature of silane coupling agents. Selected silane coupling agents were applied as prepaint or passivation treatments onto galvanized steel substrates. The corrosion protection provided by these silane-based treatments were evaluated by salt spray test, cyclic corrosion test, electrochemical impedance spectroscopy, and stack test. The results showed that silane coupling agents can possibly be used to replace chromates for corrosion control of galvanized steel substrates. Silane coatings provided by these silane treatments serve mainly as physical barriers. Factors that

  20. Corrosion Degradation of Coated Aluminum Alloy Systems through Galvanic Interactions

    Science.gov (United States)

    2017-07-19

    REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...19b. TELEPHONE NUMBER (Include area code) Corrosion  Degradation  of  Coated  Aluminum  Alloy  Systems  through  Galvanic...their  low  density  and  relatively  high  strength.   While  exhibiting  significant  general   corrosion  resistance,  these

  1. Complications of microsurgery of vestibular schwannoma

    Czech Academy of Sciences Publication Activity Database

    Betka, J.; Zvěřina, E.; Balogová, Zuzana; Profant, Oliver; Skřivan, J.; Kraus, J.; Lisý, J.; Syka, Josef; Chovanec, M.

    2014-01-01

    Roč. 2014, May 28 (2014), s. 315952 ISSN 2314-6133 R&D Projects: GA MZd NT12459 Grant - others:GA MZd(CZ) NT11543; GA MŠk(CZ) UNCE 204013; GA UK(CZ) SVV 266513; GA MŠk(CZ) Prvouk-P27/LF1/1 Institutional support: RVO:68378041 Keywords : acoustic neurona surgery * tumor surgery * vestibular schwannomas Subject RIV: FF - HEENT, Dentistry Impact factor: 1.579, year: 2014

  2. Contribution to the study of the influence of zinc bath composition on corrosion resistance of coatings obtained by galvanization

    International Nuclear Information System (INIS)

    Cabrillac, Claude

    1969-01-01

    This research thesis deals with the influence of zinc purity on the corrosion resistance of a coating obtained by galvanization, and on its effect on cathodic protection. This study therefore addresses methods and tests processes (notably salt spray test) aiming at assessing the efficiency of steel protection by hot galvanization, and aims at highlighting the influence of galvanization bath purity or composition on corrosion resistance of galvanized layers

  3. Coating adherence in galvanized steel assessed by acoustic emission wavelet analysis

    International Nuclear Information System (INIS)

    Gallego, Antolino; Gil, Jose F.; Vico, Juan M.; Ruzzante, Jose E.; Piotrkowski, Rosa

    2005-01-01

    Coating-substrate adherence in galvanized steel is evaluated by acoustic emission wavelet analysis in scratch tests on hot-dip galvanized samples. The acoustic emission results are compared with optical and electron microscopy observations in order to understand coating features related to adherence and to establish criteria aimed at improving the manufacture process

  4. Area effect on galvanic corrosion of condenser materials with titanium tubes in nuclear power plants

    International Nuclear Information System (INIS)

    Hwang, Seong Sik; Kim, Joung Soo; Kim, Uh Chul

    1993-01-01

    Titanium tubes have recently been used in condensers of nuclear power plants since titanium has very good corrosion resistance to seawater. However, when it is connected to Cu alloys as tube sheet materials and these Cu alloys are connected to carbon steels as water box materials, it makes significant galvanic corrosion on connected materials. It is expected from electrochemical tests that the corrosion rate of carbon steel will increase when it is galvanically coupled with Ti or Cu in sea water and the corrosion rate of Cu will increase when it is coupled with Ti, of this couple is exposed to sea water for a long time. It is also expected that the surface area ratios, R 1 (surface area of carbon steel/surface area of Ti) and R 2 (surface area of carbon steel/surface area of Cu) are very improtant for the galvanic corrosion of carbon steel and that these should not be kept to low values in order to minimize the galvanic corrosion on the carbon steel of the water box. Immersed galvanic corrosion tests show that the corrosion rate of carbon steel is 4.4 mpy when this ratio is 10 -2 . The galvanic corrosion rate of this carbon steel is increased from 4.4 mpy to 13 mpy at this area ratio, 1, when this connected galvanic specimen is galvanically coupled with a Ti tube. This can be rationalized by the combined effects of R 1 and R 2 on the polarization curve. (Author)

  5. Finishes for Metals. Paintability of Galvanized Steel, Corrosion Resistance of Metallized Coatings.

    Science.gov (United States)

    Building Research Inst., Inc., Washington, DC.

    Two papers are presented. The first, "Report of the AISI Research Project on the Paintability of Galvanized Steel," was a project aimed at determining optimum procedures for painting bright-spangled galvanized sheet steel products using three classes of trade sales paints--metallic zinc-dust, portland cement-in-oil, and water base emulsion paints.…

  6. Radiotherapy for Vestibular Schwannomas: A Critical Review

    International Nuclear Information System (INIS)

    Murphy, Erin S.; Suh, John H.

    2011-01-01

    Vestibular schwannomas are slow-growing tumors of the myelin-forming cells that cover cranial nerve VIII. The treatment options for patients with vestibular schwannoma include active observation, surgical management, and radiotherapy. However, the optimal treatment choice remains controversial. We have reviewed the available data and summarized the radiotherapeutic options, including single-session stereotactic radiosurgery, fractionated conventional radiotherapy, fractionated stereotactic radiotherapy, and proton beam therapy. The comparisons of the various radiotherapy modalities have been based on single-institution experiences, which have shown excellent tumor control rates of 91-100%. Both stereotactic radiosurgery and fractionated stereotactic radiotherapy have successfully improved cranial nerve V and VII preservation to >95%. The mixed data regarding the ideal hearing preservation therapy, inherent biases in patient selection, and differences in outcome analysis have made the comparison across radiotherapeutic modalities difficult. Early experience using proton therapy for vestibular schwannoma treatment demonstrated local control rates of 84-100% but disappointing hearing preservation rates of 33-42%. Efforts to improve radiotherapy delivery will focus on refined dosimetry with the goal of reducing the dose to the critical structures. As future randomized trials are unlikely, we suggest regimented pre- and post-treatment assessments, including validated evaluations of cranial nerves V, VII, and VIII, and quality of life assessments with long-term prospective follow-up. The results from such trials will enhance the understanding of therapy outcomes and improve our ability to inform patients.

  7. Audiovestibular Function Deficits in Vestibular Schwannoma

    Directory of Open Access Journals (Sweden)

    Constantin von Kirschbaum

    2016-01-01

    Full Text Available Introduction. Vestibular schwannomas (VS are benign tumours of the vestibular nerve and can lead to hearing loss, tinnitus, vertigo, facial palsy, and brainstem compression. Audiovestibular diagnostic tests are essential for detection and treatment planning. Methods. Medline was used to perform a systematic literature review with regard to how audiovestibular test parameters correlate with symptoms, tumour size, and tumour location. Results. The auditory brainstem response can be used to diagnose retrocochlear lesions caused by VS. Since hearing loss correlates poorly with tumour size, a retrocochlear lesion is probably not the only cause for hearing loss. Also cochlear mechanisms seem to play a role. This can be revealed by abnormal otoacoustic emissions, despite normal ABR and new MRI techniques which have demonstrated endolymphatic hydrops of the inner ear. Caloric and head impulse tests show frequency specific dynamics and vestibular evoked myogenic potentials may help to identify the location of the tumour regarding the involved nerve parts. Conclusion. In order to preserve audiovestibular function in VS, it is important to stop the growth of the tumour and to avoid degenerative changes in the inner ear. A detailed neurotological workup helps to diagnose VS of all sizes and can also provide useful prognostic information.

  8. Corrosive microenvironments at lead solder surfaces arising from galvanic corrosion with copper pipe.

    Science.gov (United States)

    Nguyen, Caroline K; Stone, Kendall R; Dudi, Abhijeet; Edwards, Marc A

    2010-09-15

    As stagnant water contacts copper pipe and lead solder (simulated soldered joints), a corrosion cell is formed between the metals in solder (Pb, Sn) and the copper. If the resulting galvanic current exceeds about 2 μA/cm(2), a highly corrosive microenvironment can form at the solder surface, with pH chloride concentrations at least 11 times higher than bulk water levels. Waters with relatively high chloride tend to sustain high galvanic currents, preventing passivation of the solder surface, and contributing to lead contamination of potable water supplies. The total mass of lead corroded was consistent with predictions based on the galvanic current, and lead leaching to water was correlated with galvanic current. If the concentration of sulfate in the water increased relative to chloride, galvanic currents and associated lead contamination could be greatly reduced, and solder surfaces were readily passivated.

  9. Galvanic Corrosion between Alloy 690 and Magnetite in Alkaline Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Soon-Hyeok Jeon

    2015-12-01

    Full Text Available The galvanic corrosion behavior of Alloy 690 coupled with magnetite has been investigated in an alkaline solution at 30 °C and 60 °C using a potentiodynamic polarization method and a zero resistance ammeter. The positive current values were recorded in the galvanic couple and the corrosion potential of Alloy 690 was relatively lower. These results indicate that Alloy 690 behaves as the anode of the pair. The galvanic coupling between Alloy 690 and magnetite increased the corrosion rate of Alloy 690. The temperature increase led to an increase in the extent of galvanic effect and a decrease in the stability of passive film. Galvanic effect between Alloy 690 and magnetite is proposed as an additional factor accelerating the corrosion rate of Alloy 690 steam generator tubing in secondary water.

  10. Effect of galvanic coupling between overpack materials for high-level nuclear waste containers

    International Nuclear Information System (INIS)

    Dunn, D.S.; Cragnolino, G.A.; Sridhar, N.

    1998-01-01

    The effect of environmental parameters and area ratio on the galvanic protection of Alloy 825 by A516 steel was studied. A simplified model was used to calculate the potential and corrosion current density of the bimetallic couple as a function of the galvanic coupling efficiency. Galvanic corrosion tests were performed to gain confidence in the calculated values. Both the calculations and laboratory testing indicate that, with highly efficient coupling, the potential of the galvanic couple is maintained below the repassivation potential for Alloy 825 in chloride-containing solutions. As a result, the initiation of localized corrosion on Alloy 825 is prevented. The formation of oxides, scales, and corrosion product layers between the barriers is shown to reduce the efficiency of the galvanic couple, which may result in conditions under which the localized corrosion of the inner corrosion resistant barrier can occur

  11. Effect of Dynamic Flow on the Structure of Inhibition Layer in Hot-dip Galvanizing

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Young Sool; Kim, Myung Soo; Kim, Su Young [POSCO Technical Research Labs., Gwangyang (Korea, Republic of); Paik, Doo Jin [POSCO Kwangyang Steel Works, Gwangyang (Korea, Republic of)

    2011-02-15

    The effect of dynamic flow or forced convection were investigated and compared on the formation of inhibition layer, galvanizing and galvannealing reactions through the hot-dip galvanizing simulator with the oscillation of specimen in zinc bath, continuous galvanizing pilot plant with zinc pumping system through the snout and continuous galvanizing operation with Dynamic Galvanizing{sup TR} system. The interfacial Al pick-up was not consistent between the results of simulator, pilot plant and line operation, but the morphology of inhibition layer became compact and refined by the forced convection. The growth of Fe-Zn intermetallics at the interface was inhibited by the forced convection, whereas the galvannealing rate would be a little promoted.

  12. Effect of Dynamic Flow on the Structure of Inhibition Layer in Hot-dip Galvanizing

    International Nuclear Information System (INIS)

    Jin, Young Sool; Kim, Myung Soo; Kim, Su Young; Paik, Doo Jin

    2011-01-01

    The effect of dynamic flow or forced convection were investigated and compared on the formation of inhibition layer, galvanizing and galvannealing reactions through the hot-dip galvanizing simulator with the oscillation of specimen in zinc bath, continuous galvanizing pilot plant with zinc pumping system through the snout and continuous galvanizing operation with Dynamic Galvanizing TR system. The interfacial Al pick-up was not consistent between the results of simulator, pilot plant and line operation, but the morphology of inhibition layer became compact and refined by the forced convection. The growth of Fe-Zn intermetallics at the interface was inhibited by the forced convection, whereas the galvannealing rate would be a little promoted

  13. 76 FR 47150 - Galvanized Steel Wire From the People's Republic of China and Mexico: Postponement of Preliminary...

    Science.gov (United States)

    2011-08-04

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-975, A-201-840] Galvanized Steel... in the Federal Register the initiation of the antidumping duty investigations of galvanized steel... is January 1, 2010, through December 31, 2010. See Galvanized Steel Wire From the People's Republic...

  14. 77 FR 17430 - Galvanized Steel Wire From the People's Republic of China: Final Determination of Sales at Less...

    Science.gov (United States)

    2012-03-26

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-975] Galvanized Steel Wire From... Determination of sales at less than fair value (``LTFV'') in the antidumping investigation of galvanized steel... galvanized steel wire from the PRC is being, or is likely to be, sold in the United States at LTFV, as...

  15. 76 FR 72721 - Galvanized Steel Wire From China and Mexico; Scheduling of the Final Phase of Countervailing Duty...

    Science.gov (United States)

    2011-11-25

    ...)] Galvanized Steel Wire From China and Mexico; Scheduling of the Final Phase of Countervailing Duty and... galvanized steel wire, provided for in subheading 7217.20 of the Harmonized Tariff Schedule of the United... merchandise as galvanized steel wire which is a cold- drawn carbon quality steel product in coils, of solid...

  16. 76 FR 68407 - Galvanized Steel Wire From the People's Republic of China: Preliminary Determination of Sales at...

    Science.gov (United States)

    2011-11-04

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-570-975] Galvanized Steel Wire From... galvanized steel wire from the People's Republic of China (``PRC'') is being, or is likely to be, sold in the... concerning imports of galvanized steel wire from the PRC, filed in proper form by Davis Wire Corporation...

  17. Galvanizing industry: evaluation of exposure levels using biomonitors

    International Nuclear Information System (INIS)

    Menezes, Maria Angela de B.C.; Sabino, Claudia de V.S.; Amaral, Angela Maria; Mattos, Silvania V. de M.; S. Filho, Serafim; Maia, Elene Cristina P.

    1999-01-01

    In Brazil, statistical surveys concerning occupational diseases refer to accidents and damages. The surveys do not refer to the occupational diseases developed through long exposures to hazardous work conditions, involving physical risk and toxic chemical substances. The Program of Medical Control of Occupational Health determines the Maximum Biological Levels Allowed and the Values of Normality References. But concerning metal and toxic inorganic, values of only few elements are established. In Belo Horizonte and surroundings areas, which is an important industrial centre in the country, there are different industries distributed over various areas. There are about 80 galvanizing industries which are responsible for the majority of the metal contamination hospitalities. A preliminary sampling was performed in order to conduct a survey of the exposures to elements related to occupational diseases in galvanizing industry. The preliminary results for toxic and non-toxic elements obtained using hair and fingernails as biomonitors are shown. The K 0 parametric neutron activation analysis method was applied and the elements determined were: Ag, Al, Au, Cl, Co, Cr, Cu, Fe, I, Mn, Na, Ti, V, Ta, and Zn. (author)

  18. Gold recovery from organic solvents using galvanic stripping

    Energy Technology Data Exchange (ETDEWEB)

    Flores, C.; O`Keefe, T.J. [Univ. of Missouri, Rolla, MO (United States). Dept. of Metallurgical Engineering

    1995-08-01

    A novel process using solid metals for the direct reduction of more noble metal ions from solvent extraction organics has been developed. Base metals recovery has been the principal focus of investigations to date but feasibility tests have now also been made on galvanically stripping selected precious metals. In this study gold (III) was loaded from an aqueous HAuCl{sub 4}{center_dot}3H{sub 2}O solution into a mixed organic 40 vol.% TBP, 10 vol.% D2EHPA in kerosene. The direct precipitation of metallic gold from the loaded organic phase using zinc powder and iron, aluminum and copper slabs at 70 C was successfully demonstrated. The gold reduction rates were relatively fast even though the conductivity of the organic solutions is very low. The reaction rates were studied as a function of the variables zinc particulate size, oxygen and nitrogen atmosphere, water content in the organic phase, organic ratios and temperature. The gold morphology was usually powdery or dendritic in nature but continuous films were obtained in some instances. Activation energies were calculated and possible reaction mechanisms are discussed. In general, the results obtained were very promising and showed that gold can be successfully cemented from selected organic solvents by galvanic stripping using less noble solid metal reductants.

  19. Setup of Galvanic Sensors for the Monitoring of Gilded Bronzes

    Directory of Open Access Journals (Sweden)

    Sara Goidanich

    2014-04-01

    Full Text Available Traditional electrochemical techniques, such as linear polarization resistance (Rp, and electrochemical impedance spectroscopy (EIS, cannot be applied to gilded bronzes, as it may not be possible to interpret the results obtained due to the bimetallic nature of the studied material. The measurement of the macrocouple current generated by the gold/bronze galvanic couple can be used as an indicator of degradation processes. Nevertheless, this measurement cannot be performed directly on the original artifacts due to the systematic presence of short-circuits between the two metals. In the present work the use of galvanic sensors is proposed as a possible solution for the monitoring of gilded bronze artefacts. The sensors have been designed to simulate real gilded bronze surfaces in terms of composition and stratigraphy and have proved to be a reliable diagnostic tool for the in situ monitoring of the rates of deterioration of gilded bronze surfaces and to test new conservation treatments. Their set-up and application is reported and their performances discussed.

  20. Pseudarthrosis due to galvanic corrosion presenting as subarachnoid hemorrhage

    Directory of Open Access Journals (Sweden)

    Rosemary Noel Beavers

    2017-01-01

    Full Text Available Two unlike metals near one another can break down as they move toward electrochemical equilibrium resulting in galvanic corrosion. We describe a case of electrochemical corrosion resulting in pseudarthrosis, followed by instrumentation failure leading to subarachnoid hemorrhage. A 53-year-old female with a history of cervical instability and two separate prior cervical fusion surgery with sublaminar cables presented with new onset severe neck pain. Restricted range of motion in her neck and bilateral Hoffman's was noted. X-ray of her cervical spine was negative. A noncontrast CT scan of her head and neck showed subarachnoid hemorrhage in the prepontine and cervicomedullary cisterns. Neurosurgical intervention involved removal of prior stainless steel and titanium cables, repair of cerebrospinal fluid leak, and nonsegmental C1–C3 instrumented fusion. She tolerated the surgery well and followed up without complication. Galvanic corrosion of the Brook's fusion secondary to current flow between dissimilar metal alloys resulted in catastrophic instrumentation failure and subarachnoid hemorrhage.

  1. Separation of cations of heavy metalsfrom concentrated galvanic drains

    Directory of Open Access Journals (Sweden)

    L. P. Bondareva

    2018-01-01

    Full Text Available When applying galvanic coatings, soluble salts of heavy metals such as iron, copper, nickel, zinc, cadmium, chromium and other metals are used, toxic cations enter the water, with subsequent migration to the biosphere. To date, many methods have been developed for cleaning galvanic sewage, which cannot be considered sufficiently effective. The joint sorption of divalent cations of copper, nickel and cadmium from concentrated aqueous solutions was investigated. Calculation and experimental methods were used to determine the separation conditions of the bivalent ion systems that differed and close in sorption properties on the aminophosphonic polyampholyte Purolite S950 in a natrium form. It is shown that the cadmium (II cations can be isolated from solutions containing copper (II or nickel (II cations even at the height of the sorption layer of 0.13 m due to the difference in the defining characteristics of the cations. This layer height can be used not only in a chromatographic column, but also in a concentrating cartridge. Separation of the copper (II and nickel (II close to the sorption properties requires an absorbing layer of 0.76 m, which can only be used in a chromatographic column, but not for a concentrating cartridge. In this paper, the degrees of ion separation in various sorption conditions are calculated. The applicability of the conductometric method for controlling the ion exchange process is shown not only when the free cations are isolated from aqueous solutions but also bound to complexes.

  2. Galvanizing industry: evaluation of exposure levels using biomonitors

    Energy Technology Data Exchange (ETDEWEB)

    Menezes, Maria Angela de B.C.; Sabino, Claudia de V.S.; Amaral, Angela Maria [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Mattos, Silvania V. de M. [FUNED, Belo Horizonte, MG (Brazil). Div. de Bromatologia e Toxicologia; S. Filho, Serafim [Secretaria Municipal de Saude de Belo Horizonte, MG (Brazil). Coordenacao de Saude do Trabalhador; Maia, Elene Cristina P. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica

    1999-11-01

    In Brazil, statistical surveys concerning occupational diseases refer to accidents and damages. The surveys do not refer to the occupational diseases developed through long exposures to hazardous work conditions, involving physical risk and toxic chemical substances. The Program of Medical Control of Occupational Health determines the Maximum Biological Levels Allowed and the Values of Normality References. But concerning metal and toxic inorganic, values of only few elements are established. In Belo Horizonte and surroundings areas, which is an important industrial centre in the country, there are different industries distributed over various areas. There are about 80 galvanizing industries which are responsible for the majority of the metal contamination hospitalities. A preliminary sampling was performed in order to conduct a survey of the exposures to elements related to occupational diseases in galvanizing industry. The preliminary results for toxic and non-toxic elements obtained using hair and fingernails as biomonitors are shown. The K{sub 0} parametric neutron activation analysis method was applied and the elements determined were: Ag, Al, Au, Cl, Co, Cr, Cu, Fe, I, Mn, Na, Ti, V, Ta, and Zn. (author) 8 refs., 3 figs., 2 tabs.; e-mail: menezes at urano.cdtn.br

  3. Vertical Soil Profiling Using a Galvanic Contact Resistivity Scanning Approach

    Directory of Open Access Journals (Sweden)

    Luan Pan

    2014-07-01

    Full Text Available Proximal sensing of soil electromagnetic properties is widely used to map spatial land heterogeneity. The mapping instruments use galvanic contact, capacitive coupling or electromagnetic induction. Regardless of the type of instrument, the geometrical configuration between signal transmitting and receiving elements typically defines the shape of the depth response function. To assess vertical soil profiles, many modern instruments use multiple transmitter-receiver pairs. Alternatively, vertical electrical sounding can be used to measure changes in apparent soil electrical conductivity with depth at a specific location. This paper examines the possibility for the assessment of soil profiles using a dynamic surface galvanic contact resistivity scanning approach, with transmitting and receiving electrodes configured in an equatorial dipole-dipole array. An automated scanner system was developed and tested in agricultural fields with different soil profiles. While operating in the field, the distance between current injecting and measuring pairs of rolling electrodes was varied continuously from 40 to 190 cm. The preliminary evaluation included a comparison of scan results from 20 locations to shallow (less than 1.2 m deep soil profiles and to a two-layer soil profile model defined using an electromagnetic induction instrument.

  4. DISPLAY OF PIXEL LOSS AND REPLICATION IN REPROJECTING RASTER DATA FROM THE SINUSOIDAL PROJECTION

    Science.gov (United States)

    Recent studies show the sinusoidal projection to be a superior planar projection for representing global raster datasets. This study uses the sinusoidal projection as a basis for evaluating pixel loss and replication in eight other planar map projections. The percent of pixels ...

  5. Vestibular control of sympathetic activity. An otolith-sympathetic reflex in humans.

    Science.gov (United States)

    Kaufmann, H; Biaggioni, I; Voustianiouk, A; Diedrich, A; Costa, F; Clarke, R; Gizzi, M; Raphan, T; Cohen, B

    2002-04-01

    It has been proposed that a vestibular reflex originating in the otolith organs and other body graviceptors modulates sympathetic activity during changes in posture with regard to gravity. To test this hypothesis, we selectively stimulated otolith and body graviceptors sinusoidally along different head axes in the coronal plane with off-vertical axis rotation (OVAR) and recorded sympathetic efferent activity in the peroneal nerve (muscle sympathetic nerve activity, MSNA), blood pressure, heart rate, and respiratory rate. All parameters were entrained during OVAR at the frequency of rotation, with MSNA increasing in nose-up positions during forward linear acceleration and decreasing when nose-down. MSNA was correlated closely with blood pressure when subjects were within +/-90 degrees of nose-down positions with a delay of 1.4 s, the normal latency of baroreflex-driven changes in MSNA. Thus, in the nose-down position, MSNA was probably driven by baroreflex afferents. In contrast, when subjects were within +/-45 degrees of the nose-up position, i.e., when positive linear acceleration was maximal along the naso-ocipital axis, MSNA was closely related to gravitational acceleration at a latency of 0.4 s. This delay is too short for MSNA changes to be mediated by the baroreflex, but it is compatible with the delay of a response originating in the vestibular system. We postulate that a vestibulosympathetic reflex, probably originating mainly in the otolith organs, contributes to blood pressure maintenance during forward linear acceleration. Because of its short latency, this reflex may be one of the earliest mechanisms to sustain blood pressure upon standing.

  6. Sinusoidal oscillators and waveform generators using modern electronic circuit building blocks

    CERN Document Server

    Senani, Raj; Singh, V K; Sharma, R K

    2016-01-01

    This book serves as a single-source reference to sinusoidal oscillators and waveform generators, using classical as well as a variety of modern electronic circuit building blocks. It provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators and includes a catalogue of over 600 configurations of oscillators and waveform generators, describing their relevant design details and salient performance features/limitations. The authors discuss a number of interesting, open research problems and include a comprehensive collection of over 1500 references on oscillators and non-sinusoidal waveform generators/relaxation oscillators. Offers readers a single-source reference to everything connected to sinusoidal oscillators and waveform generators, using classical as well as modern electronic circuit building blocks; Provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators; Includes a catalog of over 600 configurations of oscillato...

  7. Internal Models, Vestibular Cognition, and Mental Imagery: Conceptual Considerations.

    Science.gov (United States)

    Mast, Fred W; Ellis, Andrew W

    2015-01-01

    Vestibular cognition has recently gained attention. Despite numerous experimental and clinical demonstrations, it is not yet clear what vestibular cognition really is. For future research in vestibular cognition, adopting a computational approach will make it easier to explore the underlying mechanisms. Indeed, most modeling approaches in vestibular science include a top-down or a priori component. We review recent Bayesian optimal observer models, and discuss in detail the conceptual value of prior assumptions, likelihood and posterior estimates for research in vestibular cognition. We then consider forward models in vestibular processing, which are required in order to distinguish between sensory input that is induced by active self-motion, and sensory input that is due to passive self-motion. We suggest that forward models are used not only in the service of estimating sensory states but they can also be drawn upon in an offline mode (e.g., spatial perspective transformations), in which interaction with sensory input is not desired. A computational approach to vestibular cognition will help to discover connections across studies, and it will provide a more coherent framework for investigating vestibular cognition.

  8. Translabyrinthine surgery for disabling vertigo in vestibular schwannoma patients

    NARCIS (Netherlands)

    Godefroy, W. P.; Hastan, D.; van der Mey, A. G. L.

    2007-01-01

    To determine the impact of translabyrinthine surgery on the quality of life in vestibular schwannoma patients with rotatory vertigo. Prospective study in 18 vestibular schwannoma patients. The study was conducted in a multispecialty tertiary care clinic. All 18 patients had a unilateral

  9. Assessment of auditory and vestibular functions in vitiligo patients

    Directory of Open Access Journals (Sweden)

    Eman Abd Elmohsin Dawoud

    2017-09-01

    Conclusion: The results in this study showed that 50% of vitiligo patients suffered from peripheral vestibular disorders in addition to auditory affection. Vitiligo patients require routine monitoring for auditory and vestibular functions for early identification and monitoring of changes as the disease progress.

  10. Inner ear malformations in siblings presenting with vestibular ...

    African Journals Online (AJOL)

    Although the association between inner ear abnormalities and progressive sensorineural hearing loss is well known, vestibular signs or loss of vestibular function in these ... We provide a brief overview of the latest classification of these inner ear defects as well as a review of the literature pertaining to children with inner ear ...

  11. Vestibular morphology in the German Waltzing guinea pig.

    Science.gov (United States)

    Kawaguchi, Sachie; Hultcrantz, Malou; Jin, Zhe; Ulfendahl, Mats; Suzuki, Mamoru

    2010-04-01

    The German waltzing guinea pig is a special strain of animal with a recessively inherited inner ear defect, resulting in deafness and a severe vestibular dysfunction. The hearing loss in the cochlea of the German strain is a result of a collapse of the Reissner membrane and the absence of scala media. The vestibular organ has not yet been described. German waltzing guinea pigs (homozygote and heterozygote) of different ages ranging from embryologic age 25 days to adulthood were investigated. The living animals were tested with four different vestibular tests, and the fetuses were controlled according to breeding. The morphology of the vestibular parts (ampulla, saccule, and utricle) was observed by using the light and transmission electron microscopy. Collapse of the membranous labyrinth was found already at embryologic age 50 days and progressed over time. Vestibular dysfunction was noted already from birth. Vestibular atelectasis has been shown to have the same morphology as the reported vestibular dysfunction in the German waltzing guinea pig. Owing to this similarity, this animal can be a good model for vestibular research.

  12. A review of the interrelationship between vestibular dysfunction ...

    African Journals Online (AJOL)

    functions, the effect of rehabilitation focused on the functioning of a specific canal, and the effect of different rehabilitation programmes on different vestibular deficiencies are suggested. Keywords: Vestibular dysfunction; Motor development; Learning disabilities; Posture; Rehabilitation and exercises. South African Journal ...

  13. Acute Unilateral Vestibular Failure Does Not Cause Spatial Hemineglect.

    Directory of Open Access Journals (Sweden)

    Julian Conrad

    Full Text Available Visuo-spatial neglect and vestibular disorders have common clinical findings and involve the same cortical areas. We questioned (1 whether visuo-spatial hemineglect is not only a disorder of spatial attention but may also reflect a disorder of higher cortical vestibular function and (2 whether a vestibular tone imbalance due to an acute peripheral dysfunction can also cause symptoms of neglect or extinction. Therefore, patients with an acute unilateral peripheral vestibular failure (VF were tested for symptoms of hemineglect.Twenty-eight patients with acute VF were assessed for signs of vestibular deficits and spatial neglect using clinical measures and various common standardized paper-pencil tests. Neglect severity was evaluated further with the Center of Cancellation method. Pathological neglect test scores were correlated with the degree of vestibular dysfunction determined by the subjective visual vertical and caloric testing.Three patients showed isolated pathological scores in one or the other neglect test, either ipsilesionally or contralesionally to the VF. None of the patients fulfilled the diagnostic criteria of spatial hemineglect or extinction.A vestibular tone imbalance due to unilateral failure of the vestibular endorgan does not cause spatial hemineglect, but evidence indicates it causes mild attentional deficits in both visual hemifields.

  14. Long-term hearing preservation in vestibular schwannoma

    DEFF Research Database (Denmark)

    Stangerup, Sven-Eric; Thomsen, Jens; Tos, Mirko

    2010-01-01

    The aim of the present study was to evaluate the long-term hearing during "wait and scan" management of vestibular schwannomas.......The aim of the present study was to evaluate the long-term hearing during "wait and scan" management of vestibular schwannomas....

  15. Evidence for cognitive vestibular integration impairment in idiopathic scoliosis patients

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    Mercier Pierre

    2009-08-01

    Full Text Available Abstract Background Adolescent idiopathic scoliosis is characterized by a three-dimensional deviation of the vertebral column and its etiopathogenesis is unknown. Various factors cause idiopathic scoliosis, and among these a prominent role has been attributed to the vestibular system. While the deficits in sensorimotor transformations have been documented in idiopathic scoliosis patients, little attention has been devoted to their capacity to integrate vestibular information for cognitive processing for space perception. Seated idiopathic scoliosis patients and control subjects experienced rotations of different directions and amplitudes in the dark and produced saccades that would reproduce their perceived spatial characteristics of the rotations (vestibular condition. We also controlled for possible alteration of the oculomotor and vestibular systems by measuring the subject's accuracy in producing saccades towards memorized peripheral targets in absence of body rotation and the gain of their vestibulo-ocular reflex. Results Compared to healthy controls, the idiopathic scoliosis patients underestimated the amplitude of their rotations. Moreover, the results revealed that idiopathic scoliosis patients produced accurate saccades to memorized peripheral targets in absence of body rotation and that their vestibulo-ocular reflex gain did not differ from that of control participants. Conclusion Overall, results of the present study demonstrate that idiopathic scoliosis patients have an alteration in cognitive integration of vestibular signals. It is possible that severe spine deformity developed partly due to impaired vestibular information travelling from the cerebellum to the vestibular cortical network or alteration in the cortical mechanisms processing the vestibular signals.

  16. Vestibular characterization in the menstrual cycle Caracterização vestibular no ciclo menstrual

    Directory of Open Access Journals (Sweden)

    Cintia Ishii

    2009-06-01

    Full Text Available Hormonal disorders in the menstrual cycle can affect labyrinthine fluid homeostasis, causing balance and hearing dysfunctions. STUDY DESIGN: Clinical prospective. AIM: compare the results from vestibular tests in young women, in the premenstrual and postmenstrual periods. MATERIALS AND METHODS: twenty women were selected with ages ranging from 18 to 35 years, who were not using any kind of contraceptive method for at least six months, and without vestibular or hearing complaints. The test was carried out in each subject before and after the menstrual period, respecting the limit of ten days before or after menstruation. RESULTS: there was a statistically significant difference in the menstrual cycle phases only in the following vestibular tests: calibration, saccadic movements, PRPD and caloric-induced nystagmus. We also noticed that age; a regular menstrual cycle; hearing loss or dizziness cases in the family; and premenstrual symptoms such as tinnitus, headache, sleep disorders, anxiety, nausea and hyperacusis can interfere in the vestibular test. CONCLUSION: there are differences in the vestibular tests of healthy women when comparing their pre and postmenstrual periods.As alterações hormonais do ciclo menstrual podem comprometer a homeostase dos fluidos labirínticos, gerando alterações no equilíbrio e na audição. FORMA DO ESTUDO: Clínico prospectivo. OBJETIVO: Comparar os resultados dos testes do exame vestibular em mulheres jovens, nos períodos pré e pós-menstrual. MATERIAL E MÉTODO: Foram selecionadas vinte mulheres, entre dezoito e trinta e cinco anos, que não fizessem uso de qualquer tipo de anticoncepcional, com audição normal e sem queixas vestibulares. O exame vestibular foi realizado em cada participante no período pré e no período pós-menstrual, em ordem aleatória, e respeitando o limite de até dez dias antes do início da menstruação e até dez dias após o início da menstruação. RESULTADO: Foi observada

  17. A vestibular sensation: probabilistic approaches to spatial perception.

    Science.gov (United States)

    Angelaki, Dora E; Klier, Eliana M; Snyder, Lawrence H

    2009-11-25

    The vestibular system helps maintain equilibrium and clear vision through reflexes, but it also contributes to spatial perception. In recent years, research in the vestibular field has expanded to higher-level processing involving the cortex. Vestibular contributions to spatial cognition have been difficult to study because the circuits involved are inherently multisensory. Computational methods and the application of Bayes theorem are used to form hypotheses about how information from different sensory modalities is combined together with expectations based on past experience in order to obtain optimal estimates of cognitive variables like current spatial orientation. To test these hypotheses, neuronal populations are being recorded during active tasks in which subjects make decisions based on vestibular and visual or somatosensory information. This review highlights what is currently known about the role of vestibular information in these processes, the computations necessary to obtain the appropriate signals, and the benefits that have emerged thus far.

  18. Regeneration of hair cells in the mammalian vestibular system.

    Science.gov (United States)

    Li, Wenyan; You, Dan; Chen, Yan; Chai, Renjie; Li, Huawei

    2016-06-01

    Hair cells regenerate throughout the lifetime of non-mammalian vertebrates, allowing these animals to recover from hearing and balance deficits. Such regeneration does not occur efficiently in humans and other mammals. Thus, balance deficits become permanent and is a common sensory disorder all over the world. Since Forge and Warchol discovered the limited spontaneous regeneration of vestibular hair cells after gentamicininduced damage in mature mammals, significant efforts have been exerted to trace the origin of the limited vestibular regeneration in mammals after hair cell loss. Moreover, recently many strategies have been developed to promote the hair cell regeneration and subsequent functional recovery of the vestibular system, including manipulating the Wnt, Notch and Atoh1. This article provides an overview of the recent advances in hair cell regeneration in mammalian vestibular epithelia. Furthermore, this review highlights the current limitations of hair cell regeneration and provides the possible solutions to regenerate functional hair cells and to partially restore vestibular function.

  19. Development and regeneration of vestibular hair cells in mammals.

    Science.gov (United States)

    Burns, Joseph C; Stone, Jennifer S

    2017-05-01

    Vestibular sensation is essential for gaze stabilization, balance, and perception of gravity. The vestibular receptors in mammals, Type I and Type II hair cells, are located in five small organs in the inner ear. Damage to hair cells and their innervating neurons can cause crippling symptoms such as vertigo, visual field oscillation, and imbalance. In adult rodents, some Type II hair cells are regenerated and become re-innervated after damage, presenting opportunities for restoring vestibular function after hair cell damage. This article reviews features of vestibular sensory cells in mammals, including their basic properties, how they develop, and how they are replaced after damage. We discuss molecules that control vestibular hair cell regeneration and highlight areas in which our understanding of development and regeneration needs to be deepened. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Vestibular schwannoma with contralateral facial pain – case report

    Directory of Open Access Journals (Sweden)

    Ghodsi Mohammad

    2003-03-01

    Full Text Available Abstract Background Vestibular schwannoma (acoustic neuroma most commonly presents with ipsilateral disturbances of acoustic, vestibular, trigeminal and facial nerves. Presentation of vestibular schwannoma with contralateral facial pain is quite uncommon. Case presentation Among 156 cases of operated vestibular schwannoma, we found one case with unusual presentation of contralateral hemifacial pain. Conclusion The presentation of contralateral facial pain in the vestibular schwannoma is rare. It seems that displacement and distortion of the brainstem and compression of the contralateral trigeminal nerve in Meckel's cave by the large mass lesion may lead to this atypical presentation. The best practice in these patients is removal of the tumour, although persistent contralateral pain after operation has been reported.

  1. Isothermal sinusoidal analysis of balanced compound Vuilleumier heat pumps

    International Nuclear Information System (INIS)

    Finkelstein, T.

    1992-01-01

    This paper reports on Vuilleumier heat pumps with balanced compounding which have been under investigation for about fifteen years but have not yet reached the stage of commercial utilization. Previously published analytical treatment based upon isothermal treatment of the variable-volume spaces resulted in closed form solution of considerable complexity of the coupled differential equations but applied only to free piston machines. In contrast, the procedure presented here is based on previously demonstrated sinusoidal excursions of the reciprocators. It is of the same order of accuracy, but much more simple and usable. It was found that there is only negligible difference between the results of the present and the previous approach. Additionally, the treatment presented here is applicable to kinematic machines, as well as to free piston machines. For the latter design, an equation for the natural frequency is also derived. Ideal proportions and practical expressions for the energy streams are derived. Gas forces are plotted versus displacement and it is shown that they are equivalent to a linear spring, which is of importance for the concept of a free-piston design

  2. Sinusoidal Wave Estimation Using Photogrammetry and Short Video Sequences

    Directory of Open Access Journals (Sweden)

    Ewelina Rupnik

    2015-12-01

    Full Text Available The objective of the work is to model the shape of the sinusoidal shape of regular water waves generated in a laboratory flume. The waves are traveling in time and render a smooth surface, with no white caps or foam. Two methods are proposed, treating the water as a diffuse and specular surface, respectively. In either case, the water is presumed to take the shape of a traveling sine wave, reducing the task of the 3D reconstruction to resolve the wave parameters. The first conceived method performs the modeling part purely in 3D space. Having triangulated the points in a separate phase via bundle adjustment, a sine wave is fitted into the data in a least squares manner. The second method presents a more complete approach for the entire calculation workflow beginning in the image space. The water is perceived as a specular surface, and the traveling specularities are the only observations visible to the  cameras, observations that are notably single image. The depth ambiguity is removed given additional constraints encoded within the law of reflection and the modeled parametric surface. The observation and constraint equations compose a single system of equations that is solved with the method of least squares adjustment. The devised approaches are validated against the data coming from a capacitive level sensor and on physical targets floating on the surface. The outcomes agree to a high degree.

  3. Defibrotide in Severe Sinusoidal Obstruction Syndrome: Medicine and Economic Issues.

    Science.gov (United States)

    Steelandt, Julie; Bocquet, François; Cordonnier, Anne-Laure; De Courtivron, Charlotte; Fusier, Isabelle; Paubel, Pascal

    2017-02-01

    In Europe, Defitelio (defibrotide) has a Market Authorization in curative treatment of severe sinusoidal obstruction syndrome (SOS) but not in prophylaxis (2013). In France, defibrotide has had a compassionate-use program since 2009. Today, the high cost of defibrotide remains a major hurdle for hospital budgets. Medicine and economic issues were evaluated for the 39 hospitals of the French Public Assistance-Hospitals of Paris (AP-HP). We analyzed literature reviews, consumption, and expenditures through AP-HP data in 2014 and patient profiles with defibrotide in the corresponding diagnostic-related groups (DRGs) and consulted a board of hematologists. Finally, 18 publications were selected. Between 2011 and 2014 consumption increased to €5.2M. In 2014, 80 patients receiving defibrotide were mainly ascribed to the DRG "hematopoietic stem cell transplantation" levels 3 or 4. The tariffs attributed to drugs (€3544 to 4084) cover a small part of treatment costs (€97,524 for an adult). French experts thus recommended a harmonization of indications in prophylaxis (off-label use), improvement of pretransplant care, and optimization of the number of vials used. The economic impact led experts to change their practices. They recommended the restriction of defibrotide use to SOS curative treatment and to high-risk situations in prophylaxis. Copyright © 2017 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

  4. Sinusoidal visuomotor tracking: intermittent servo-control or coupled oscillations?

    Science.gov (United States)

    Russell, D M; Sternad, D

    2001-12-01

    In visuomotor tasks that involve accuracy demands, small directional changes in the trajectories have been taken as evidence of feedback-based error corrections. In the present study variability, or intermittency, in visuomanual tracking of sinusoidal targets was investigated. Two lines of analyses were pursued: First, the hypothesis that humans fundamentally act as intermittent servo-controllers was re-examined, probing the question of whether discontinuities in the movement trajectory directly imply intermittent control. Second, an alternative hypothesis was evaluated: that rhythmic tracking movements are generated by entrainment between the oscillations of the target and the actor, such that intermittency expresses the degree of stability. In 2 experiments, participants (N = 6 in each experiment) swung 1 of 2 different hand-held pendulums, tracking a rhythmic target that oscillated at different frequencies with a constant amplitude. In 1 line of analyses, the authors tested the intermittency hypothesis by using the typical kinematic error measures and spectral analysis. In a 2nd line, they examined relative phase and its variability, following analyses of rhythmic interlimb coordination. The results showed that visually guided corrective processes play a role, especially for slow movements. Intermittency, assessed as frequency and power components of the movement trajectory, was found to change as a function of both target frequency and the manipulandum's inertia. Support for entrainment was found in conditions in which task frequency was identical to or higher than the effector's eigenfrequency. The results suggest that it is the symmetry between task and effector that determines which behavioral regime is dominant.

  5. GABAergic systems in the vestibular nucleus and their contribution to vestibular compensation.

    Science.gov (United States)

    Gliddon, Catherine M; Darlington, Cynthia L; Smith, Paul F

    2005-01-01

    GABA and the GABAA and GABAB receptors play a pivotal role in the coordination of the central vestibular pathways. The commissural inhibition, which exists between the two vestibular nucleus complexes (VNCs) and which is responsible for enhancing the dynamic sensitivity of VNC neurons to head acceleration, is known to be substantially mediated by GABA acting on GABAA and GABAB receptors. After unilateral vestibular deafferentation (UVD), the large asymmetry in spontaneous resting activity between the two VNCs is reinforced and exacerbated by the GABAergic interaction between the ipsilateral and contralateral sides. Although it has been suggested that reduced GABAergic inhibition of the ipsilateral VNC may be partially responsible for the recovery of resting activity that underlies vestibular compensation of the static symptoms of UVD, at present there are few data available to test this hypothesis systematically. There is some evidence that GABA concentrations change in the ipsilateral VNC during the development of compensation; however, it is unclear whether these changes relate to GABA release or to metabolic pools of GABA. Most biochemical studies of GABA receptors have been conducted at the gene expression level. Therefore, it is unclear whether changes in the receptor protein also occur, although the most recent data suggest that changes in GABAA and GABAB receptor density in the VNC are unlikely. The few radioligand binding data relate to GABAA receptors with benzodiazepine binding sites only. A decrease in the sensitivity of ipsilateral VNC neurons from compensated animals to GABA receptor agonists has been reported; however, these studies have employed brainstem slices and therefore the functional identity of the neurons involved has been unclear. Although it seems likely that some changes in central GABAergic systems accompany the recovery of resting activity in the ipsilateral VNC during the development of vestibular compensation, at the present stage

  6. Electric Current Transmission Through Tissues of the Vestibular Labyrinth of a Patient: Perfection of the Vestibular Implant

    Science.gov (United States)

    Demkin, V. P.; Shchetinin, P. P.; Melnichuk, S. V.; Kingma, H.; Van de Berg, R.; Pleshkov, M. O.; Starkov, D. N.

    2018-03-01

    An electric model of current transmission through tissues of the vestibular labyrinth of a patient is suggested. To stimulate directly the vestibular nerve in surgical operation, terminations of the electrodes are implanted through the bone tissue of the labyrinth into the perilymph in the vicinity of the vestibular nerve. The biological tissue of the vestibular labyrinth surrounding the electrodes and having heterogeneous composition possesses conductive and dielectric properties. Thus, when a current pulse from the vestibular implant is applied to one of the electrodes, conductive disturbance currents may arise between the electrodes and the vestibular nerves that can significantly deteriorate the direct signal quality. To study such signals and to compensate for the conductive disturbance currents, an equivalent electric circuit with actual electric impedance properties of tissues of the vestibular system is suggested, and the time parameters of the conductive disturbance current transmission are calculated. It is demonstrated that these parameters can reach large values. The suggested electric model and the results of calculations can be used for perfection of the vestibular implant.

  7. EL SINDROME VESTIBULAR EN EL ADULTO MAYOR

    Directory of Open Access Journals (Sweden)

    Dr. Hamlet Suárez

    2016-11-01

    Full Text Available El vértigo, la inestabilidad y las caídas tienen una incidencia relevante en el adulto mayor, disminuye su calidad de vida y puede ser causa de muerte en esta población. Este artículo describe las presentaciones clínicas y el abordaje de la evaluación de la patología vestibular en este grupo de edad, utilizando diferentes instrumentos para el diagnóstico así como también las reglas generales del tratamiento.

  8. Vestibular function in the space environment

    Science.gov (United States)

    Von Baumgarten, R. J.; Harth, O.; Thuemler, R.; Baldrighi, G.; Shillinger, G. L., Jr.

    1975-01-01

    The present work presents new results about the interdependence of optical illusory sensations and eye movements in man. To establish to what degree certain illusions previously obtained during centrifugation and parabolic flight can be explained by eye movements and by neuronal integration in the brain, real eye movements were measured as they occurred in the dark without optical fixation, during rectilinear accelerations on the ground, and during weightlessness in parabolic flight. Results provide valuable insight into normal vestibular function as well as resolution of within-the-eye and behind-the-eye contributions to the above illusions.

  9. Effect of chemical composition of steel on the structure of hot – dip galvanized coating

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-01-01

    Full Text Available This article describes the effect of the content of conventional steel impurity elements on the thickness and composition of the zinc layer. This article is focused primarily on low-temperature, batch hot-dip galvanizing; however, the continuous coating process is also mentioned. The main discussion covers galvanizing from pure zinc melt, and only touches on galvanizing from melts with the usual amounts of aluminium (0,2 wt. %. Silicon, phosphorus, aluminium and sulfur may have an especially negative effect on the mechanical properties of the coating and its final appearance. The content of ballast carbon and manganese has a rather limited effect on composition and coating thickness.

  10. Full-Band Quasi-Harmonic Analysis and Synthesis of Musical Instrument Sounds with Adaptive Sinusoids

    Directory of Open Access Journals (Sweden)

    Marcelo Caetano

    2016-05-01

    Full Text Available Sinusoids are widely used to represent the oscillatory modes of musical instrument sounds in both analysis and synthesis. However, musical instrument sounds feature transients and instrumental noise that are poorly modeled with quasi-stationary sinusoids, requiring spectral decomposition and further dedicated modeling. In this work, we propose a full-band representation that fits sinusoids across the entire spectrum. We use the extended adaptive Quasi-Harmonic Model (eaQHM to iteratively estimate amplitude- and frequency-modulated (AM–FM sinusoids able to capture challenging features such as sharp attacks, transients, and instrumental noise. We use the signal-to-reconstruction-error ratio (SRER as the objective measure for the analysis and synthesis of 89 musical instrument sounds from different instrumental families. We compare against quasi-stationary sinusoids and exponentially damped sinusoids. First, we show that the SRER increases with adaptation in eaQHM. Then, we show that full-band modeling with eaQHM captures partials at the higher frequency end of the spectrum that are neglected by spectral decomposition. Finally, we demonstrate that a frame size equal to three periods of the fundamental frequency results in the highest SRER with AM–FM sinusoids from eaQHM. A listening test confirmed that the musical instrument sounds resynthesized from full-band analysis with eaQHM are virtually perceptually indistinguishable from the original recordings.

  11. Growth and galvanic replacement of silver nanocubes in organic media

    Science.gov (United States)

    Polavarapu, Lakshminarayana; Liz-Marzán, Luis M.

    2013-05-01

    Although metal nanoparticles with various shapes can be prepared in polar organic solvents, little has been advanced toward the shape-controlled synthesis in non-polar solvents. We report a simple method for the synthesis of nearly monodisperse single crystalline silver nanocubes in a non-polar solvent (1,2-dichlorobenzene) by using oleylamine as both a reducing and capping agent. Mechanistic studies based on the time evolution of Ag nanoparticles revealed that multiply twinned nanocrystals form at the beginning of the reaction, which are gradually transformed into single crystalline Ag nanocubes by oxidative etching. Control experiments showed that the solvent plays an important role in the formation of such single crystalline Ag nanocubes. The effects of reaction temperature, oleylamine concentration, solvent, and the nature of the silver ion precursor on the morphology and monodispersity of the nanoparticles were systematically investigated. Additionally, the galvanic replacement reaction with HAuCl4 in an organic medium was implemented to prepare hydrophobic hollow Au-Ag nanocages with tunable localized surface plasmon resonances.Although metal nanoparticles with various shapes can be prepared in polar organic solvents, little has been advanced toward the shape-controlled synthesis in non-polar solvents. We report a simple method for the synthesis of nearly monodisperse single crystalline silver nanocubes in a non-polar solvent (1,2-dichlorobenzene) by using oleylamine as both a reducing and capping agent. Mechanistic studies based on the time evolution of Ag nanoparticles revealed that multiply twinned nanocrystals form at the beginning of the reaction, which are gradually transformed into single crystalline Ag nanocubes by oxidative etching. Control experiments showed that the solvent plays an important role in the formation of such single crystalline Ag nanocubes. The effects of reaction temperature, oleylamine concentration, solvent, and the nature of the

  12. Charging system with galvanic isolation and multiple operating modes

    Science.gov (United States)

    Kajouke, Lateef A.; Perisic, Milun; Ransom, Ray M.

    2013-01-08

    Systems and methods are provided for operating a charging system with galvanic isolation adapted for multiple operating modes. A vehicle charging system comprises a DC interface, an AC interface, a first conversion module coupled to the DC interface, and a second conversion module coupled to the AC interface. An isolation module is coupled between the first conversion module and the second conversion module. The isolation module comprises a transformer and a switching element coupled between the transformer and the second conversion module. The transformer and the switching element are cooperatively configured for a plurality of operating modes, wherein each operating mode of the plurality of operating modes corresponds to a respective turns ratio of the transformer.

  13. Corrosion of bare and galvanized steel in gypsum

    Directory of Open Access Journals (Sweden)

    Gómez, Mercedes

    1988-12-01

    Full Text Available Gypsum is a relatively low-cost building material much abounding in our country. When it is put in contact with steel, it may produce high corrosion rates due to its pH value (close to 7. This work reports the results obtained in studying the corrosion rates of bare and galvanized steel in contact with gypsum and plaster, as well as the influence curing thermal treatment applied to gypsum, enviromental relative humidity and addition of compounds with different natures and purposes may have in such process. In-situ observations, as well as the measurement of the Polarization Resistance and the weight loss have been used as measurement technics. From the results obtained it has been possible to deduce that galvanized steel has better behaviour in dry enviroments than bare steel in the same conditions and moist atmosphere induces proportionally more corrosion in galvanized steel than in bare one. Additions to gypsum do not modified these conclusions, though it may be pointed out that addition of nitrites or lime improves the behaviour of bare steel, while galvanized behaviour is not modified. The addition of lime is not recommended because phenomena of dilated along time expansion may take place.

    El yeso es un material de construcción de relativo bajo coste y que, además, es muy abundante en nuestro país. Debido a su pH cercano a la neutralidad, cuando entra en contacto con el acero, este puede corroerse a elevadas velocidades. En esta comunicación se presentan los resultados de un estudio sobre la velocidad de corrosión del acero desnudo y galvanizado en contacto con yeso y escayola y la influencia que tienen: el tratamiento térmico del curado del yeso, la humedad relativa ambiental y la adición de aditivos de diversa naturaleza y finalidad. Como técnicas de medida se han utilizado la medida de la Resistencia de Polarización y de la pérdida de peso, así como observaciones visuales. De los resultados se puede deducir que en

  14. Theory of the Spin Galvanic Effect at Oxide Interfaces

    Science.gov (United States)

    Seibold, Götz; Caprara, Sergio; Grilli, Marco; Raimondi, Roberto

    2017-12-01

    The spin galvanic effect (SGE) describes the conversion of a nonequilibrium spin polarization into a transverse charge current. Recent experiments have demonstrated a large conversion efficiency for the two-dimensional electron gas formed at the interface between two insulating oxides, LaAlO3 and SrTiO3 . Here, we analyze the SGE for oxide interfaces within a three-band model for the Ti t2 g orbitals which displays an interesting variety of effective spin-orbit couplings in the individual bands that contribute differently to the spin-charge conversion. Our analytical approach is supplemented by a numerical treatment where we also investigate the influence of disorder and temperature, which turns out to be crucial to providing an appropriate description of the experimental data.

  15. Model-based Vestibular Afferent Stimulation: Modular Workflow for Analyzing Stimulation Scenarios in Patient Specific and Statistical Vestibular Anatomy

    Directory of Open Access Journals (Sweden)

    Michael Handler

    2017-12-01

    Full Text Available Our sense of balance and spatial orientation strongly depends on the correct functionality of our vestibular system. Vestibular dysfunction can lead to blurred vision and impaired balance and spatial orientation, causing a significant decrease in quality of life. Recent studies have shown that vestibular implants offer a possible treatment for patients with vestibular dysfunction. The close proximity of the vestibular nerve bundles, the facial nerve and the cochlear nerve poses a major challenge to targeted stimulation of the vestibular system. Modeling the electrical stimulation of the vestibular system allows for an efficient analysis of stimulation scenarios previous to time and cost intensive in vivo experiments. Current models are based on animal data or CAD models of human anatomy. In this work, a (semi-automatic modular workflow is presented for the stepwise transformation of segmented vestibular anatomy data of human vestibular specimens to an electrical model and subsequently analyzed. The steps of this workflow include (i the transformation of labeled datasets to a tetrahedra mesh, (ii nerve fiber anisotropy and fiber computation as a basis for neuron models, (iii inclusion of arbitrary electrode designs, (iv simulation of quasistationary potential distributions, and (v analysis of stimulus waveforms on the stimulation outcome. Results obtained by the workflow based on human datasets and the average shape of a statistical model revealed a high qualitative agreement and a quantitatively comparable range compared to data from literature, respectively. Based on our workflow, a detailed analysis of intra- and extra-labyrinthine electrode configurations with various stimulation waveforms and electrode designs can be performed on patient specific anatomy, making this framework a valuable tool for current optimization questions concerning vestibular implants in humans.

  16. STATE ANXIETY, SUBJECTIVE IMBALANCE AND HANDICAP IN VESTIBULAR SCHWANNOMA

    Directory of Open Access Journals (Sweden)

    Yougan Saman

    2016-07-01

    Full Text Available ABSTRACTEvidence is emerging of a significant clinical and neuro-anatomical relationship between balance and anxiety. Research has suggested a potentially priming effect with anxiety symptoms predicting a worsening of balance function in patients with underlying balance dysfunction. We propose to show that a vestibular stimulus is responsible for an increase in state anxiety and there is a relationship between increased state anxiety and worsening balance function. Aims1.To quantify state anxiety following a vestibular stimulus in patients with a chronic vestibular deficit.2.To determine if state anxiety during a vestibular stimulus would correlate with the severity of chronic balance symptoms and handicap. MethodsTwo separate cohorts Vestibular Schwannoma (VS patients underwent vestibular tests (electronystagmography, cervical and ocular vestibular evoked myogenic potentials and caloric responses and questionnaire assessment (Vertigo handicap Questionnaire, Vertigo Symptom Scale, State Trait Anxiety InventoryFifteen post resection Vestibular schwannoma patients, with complete unilateral vestibular deafferentation, were assessed at a minimum of 6 months after surgery in Experiment 1 (Aim 1. Forty-five patients with VS in-situ and with preserved vestibular function formed the cohort for Experiment 2 (Aim 2. Experiment 1: VS subjects (N=15 with a complete post-resection unilateral vestibular deafferentation completed a State anxiety questionnaire before caloric assessment and again afterwards with the point of maximal vertigo as the reference (Aim 1. Experiment 2: State anxiety measured at the point of maximal vertigo following a caloric assessment was compared between two groups of presenting with balance symptoms (Group 1 N=26 and without balance symptoms (Group 2 N=11 (Aim 2. The presence of balance symptoms was defined as having a positive score on the VSS-VER.ResultsIn experiment 1, a significant difference (p<0.01 was found when comparing

  17. Cytotoxic effect of galvanically coupled magnesium-titanium particles.

    Science.gov (United States)

    Kim, Jua; Gilbert, Jeremy L

    2016-01-01

    Recent work has shown that reduction reactions at metallic biomaterial surfaces can induce significant killing of cells in proximity to the surface. To exploit this phenomenon for therapeutic purposes, for example, for cancer tumor killing or antibacterial effects (amongst other applications), magnesium metal particles, galvanically coupled to titanium by sputtering, have been evaluated for their cell-killing capability (i.e. cytotoxicity). Magnesium (Mg) particles large enough to prevent particle phagocytosis were investigated, so that only electrochemical reactions, and not particle toxicity per se, caused cytotoxic effects. Titanium (Ti) coated magnesium particles, as well as magnesium-only particles were introduced into MC3T3-E1 mouse pre-osteoblast cell cultures over a range of particle concentrations, and cells were observed to die in a dosage-dependent manner. Ti-coated magnesium particles killed more cells at lower particle concentration than magnesium alone (Pmagnesium and magnesium-titanium had no significant difference at similar particle concentrations. Complete cell killing occurred at 750μg/ml and 1500μg/ml for Mg-Ti and Mg, respectively. Thus, this work demonstrates that galvanically coupled Mg-Ti particles have a significant cell killing capability greater than Mg alone. In addition, when the pH associated with complete killing with particles was created using NaOH only (no particles), then the percentage of cells killed was significantly less (Pmagnesium-titanium microparticles kill cells more effectively than magnesium particles alone. The killing effect was shown to not be due to pH shifts since no differences were seen for different particle types and pH adjusted medium without particles did not exhibit the same level of killing. The significance of this work is the recognition of this killing effect with Mg particles and the potential therapeutic applications in infection control and cancer treatment that this process may provide. Copyright

  18. Development of Continuous Galvanization-compatible Martensitic Steel

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Y. F.; Song, T. J.; Kim, Han S.; De Cooman [Pohang Univ. of Science and Technology, Pohang (Korea, Republic of); Kwak, J. H. [POSCO Gwangyang Works, Gwangyang (Korea, Republic of)

    2012-01-15

    The development of martensitic grades which can be processed in continuous galvanizing lines requires the reduction of the oxides formed on the steel during the hot dip process. This reduction mechanism was investigated in detail by means of High Resolution Transmission Electron Microscopy (HR-TEM) of cross-sectional samples. Annealing of a martensitic steel in a 10% H{sub 2} + N{sub 2} atmosphere with the dew point of -35 .deg. C resulted in the formation of a thin c-xMno.SiO{sub 2} (x>1) oxide film and amorphous a-xMnO.SiO{sub 2} oxide particles on the surface. During the hot dip galvanizing in Zn-0.13%Al, the thin c-xMnO.SiO{sub 2} (x>1) oxide films was reduced by the Al. The a-xMnO.SiO{sub 2} (x<0.9) and a-SiO{sub 2} (x>1) oxide film was also reduced and the amorphous a-xMnO.SiO{sub 2} and a-SiO{sub 2} particles were embedded in the Fe{sub 2}Al{sub 5-x}Zn{sub x} inhibition layer formed at the steel/coating interface during hot dipping. The results clearly show that Al in the liquid Zn bath can reduce the crystalline c-xMn.SiO{sub 2} (x>1) oxides but not the amorphous a-xMnO.SiO{sub 2} (x<0.9) and a-SiO{sub 2} oxides. These oxides remain embedded in the Zn layer or in the inhibition layer, making it possible to apply a Zn or Zn-alloy coating on martensitic steel by hot dipping. The hot dipping process was also found to deteriorate the mechanical properties, independently of the Zn bath composition.

  19. Computationally Efficient Amplitude Modulated Sinusoidal Audio Coding using Frequency-Domain Linear Prediction

    DEFF Research Database (Denmark)

    Christensen, M. G.; Jensen, Søren Holdt

    2006-01-01

    A method for amplitude modulated sinusoidal audio coding is presented that has low complexity and low delay. This is based on a subband processing system, where, in each subband, the signal is modeled as an amplitude modulated sum of sinusoids. The envelopes are estimated using frequency......-domain linear prediction and the prediction coefficients are quantized. As a proof of concept, we evaluate different configurations in a subjective listening test, and this shows that the proposed method offers significant improvements in sinusoidal coding. Furthermore, the properties of the frequency...

  20. Effectiveness of vestibular exercise in acute vertigo

    International Nuclear Information System (INIS)

    Hashim, N.D.; Abdullah, A.; Ami, M.; Rahman, R.A.

    2015-01-01

    To evaluate effectiveness of vestibular exercises in acute vertigo. 45 patients with acute vertigo were divided into 2 groups; 23 in study group (SG) and 22 in control group (CG). All patients were given tablet betahistine 24 mg twice daily as basic medical treatment and tablet Stemetil 5mg as a rescue. Those in SG also received vestibular exercise. Assessment was done using validated questionnaires, neuro-otology tests and individual diaries. Results : Intragroup comparison of intensity of symptoms showed a significant improvement from baseline, 3-month and 6-month visit with p<0.001. While intergroup comparison showed reduction of scores in both groups and which was greater in SG at 6 months visit. An improvement of neuro-otology tests was seen in all five tests whereby the Romber test, Unterberger-Fukuda test and spontaneous nystagmus test showed earlier improvement in SG at 3-month visit than CG. The SG also recovered faster and used lesser medication. 30.4% patients in SG were asymptomatic as early as first to third week after intervention. The number of rescue medications required in each group lessened towards the end of study. By week 7, 56.3% of SG and 43.8% of CG needed no rescue medication. (author)

  1. Treatment of peripheral vestibular dysfunction using photobiomodulation

    Science.gov (United States)

    Lee, Min Young; Hyun, Jai-Hwan; Suh, Myung-Whan; Ahn, Jin-Chul; Chung, Phil-Sang; Jung, Jae Yun; Rhee, Chung Ku

    2017-08-01

    Gentamicin, which is still used in modern medicine, is a known vestibular toxic agent, and various degrees of balance problems have been observed after exposure to this pharmacologic agent. Photobiomodulation is a candidate therapy for vertigo due to its ability to reach deep inner ear organs such as the cochlea. Previous reports have suggested that photobiomodulation can improve hearing and cochlea function. However, few studies have examined the effect of photobiomodulation on balance dysfunction. We used a rat model to mimic human vestibulopathy resulting from gentamicin treatment and evaluated the effect of photobiomodulation on vestibular toxicity. Slow harmonic acceleration (SHA) rotating platform testing was used for functional evaluation and both qualitative and quantitative epifluorescence analyses of cupula histopathology were performed. Animals were divided into gentamicin only and gentamicin plus laser treatment groups. Laser treatment was applied to one ear, and function and histopathology were evaluated in both ears. Decreased function was observed in both ears after gentamicin treatment, demonstrated by low gain and no SHA asymmetry. Laser treatment minimized the damage resulting from gentamicin treatment as shown by SHA asymmetry and recovered gain in the treated ear. Histology results reflected the functional results, showing increased hair cell density and epifluorescence intensity in laser-treated cupulae.

  2. Impedance pattern of vaginal and vestibular mucosa in cyclic goats

    Directory of Open Access Journals (Sweden)

    Ivo Křivánek

    2008-01-01

    Full Text Available The changes of vaginal and vestibular impedance during the oestrous cycle in goats were examined. The onset of oestrus was teased with a buck once a day during the experiment. Impedance was mea­sured by a four-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall at the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the vestibular dorsal wall 5 cm from the vulva and at the vulva. The im­pe­dan­ce was measured once a day from 4 days before the expected oestrus to 6 days after onset of oestrus. The vaginal impedance at the cervix decreased during pro-oestrus (P < 0.01 and increased du­ring oestrus (P < 0.01. The vestibular impedance 5 cm from the vulva decreased during pro-oestrus (P < 0.01 and increased after oestrus (P < 0.01. The decrease of vaginal impedance during peri-oestrus was nearly twofold in comparison with the vestibular impedance 5 cm from the vulva. No sig­ni­fi­cant decrease of the vestibular impedance at the vulva was found during the oestrous cycle. The results indicate that the vaginal impedance at the cervix and vestibular impedance 5 cm from the vulva measured by means of a four-terminal method during the oestrous cycle display cyclic changes that are closely related to the oestrous behaviour of goats.

  3. Vestibular and balance issues following sport-related concussion.

    Science.gov (United States)

    Valovich McLeod, Tamara C; Hale, Troy D

    2015-01-01

    To review relevant literature regarding the effect of concussion on vestibular function, impairments, assessments and management strategies. REASONING: Dizziness and balance impairments are common following sport-related concussion. Recommendations regarding the management of sport-related concussion suggest including tests of balance within the multifactorial assessment paradigm for concussive injuries. The literature was searched for guidelines and original studies related to vestibular impairments following concussion, oculomotor and balance assessments and treatment or rehabilitation of vestibular impairments. The databases searched included Medline, CINAHL, Sport Discus and the Cochrane Database of Systematic Reviews through October 2013. Dizziness following concussion occurs in ∼67-77% of cases and has been implicated as a risk factor for a prolonged recovery. Balance impairments also occur after concussion and last 3-10 days post-injury. Assessments of balance can be done using both clinical and instrumented measures with success. Vestibular rehabilitation has been shown to improve outcomes in patients with vestibular impairments, with one study demonstrating success in decreasing symptoms and increasing function following concussion. Best practices suggest that the assessment of vestibular function through cranial nerve, oculomotor and balance assessments are an important aspect of concussion management. Future studies should evaluate the effectiveness of vestibular rehabilitation for improving patient outcomes.

  4. Clinical evaluation of elderly people with chronic vestibular disorder.

    Science.gov (United States)

    Gazzola, Juliana Maria; Ganança, Fernando Freitas; Aratani, Mayra Cristina; Perracini, Monica Rodrigues; Ganança, Maurício Malavasi

    2006-01-01

    Dizziness is common among the elderly. To characterize social, demographic, clinical, functional and otoneurological data in elderly patients with chronic vestibular disorder. A sequential study of 120 patients with chronic vestibular disorder. Simple descriptive analyses were undertaken. Most of the patients were female (68.3%) with a mean age of 73.40+/-5.77 years. The average number of illnesses associated with the vestibular disorder was 3.83+/-1.84; the patients were taking on average 3.86+/-2.27 different medications. The most prevalent diagnosis on the vestibular exam was unilateral vestibular loss (29.8%) and the most prevalent etiology was metabolic vestibulopathy (40.0%) followed by benign paroxysmal positional vertigo (36.7%). Fifty-two patients (43.3%) had experienced dizziness for 5 years or more. Sixty-four patients (53.3%) had at least one fall in the last year and thirty-five (29.2%) had recurrent falls. Most of the sample included females with associated diseases, and using many different drugs. The most prevalent vestibular diseases were metabolic and vascular labyrinth conditions. Dizziness is a chronic symptom in elderly patients. The association of two vestibular diseases is common. Falls are prevalent in chronic dizzy elderly patients.

  5. [Vestibular testing abnormalities in individuals with motion sickness].

    Science.gov (United States)

    Ma, Yan; Ou, Yongkang; Chen, Ling; Zheng, Yiqing

    2009-08-01

    To evaluate the vestibular function of motion sickness. VNG, which tests the vestibular function of horizontal semicircular canal, and CPT, which tests vestibulospinal reflex and judge proprioceptive, visual and vestibular status, were performed in 30 motion sickness patients and 20 healthy volunteers (control group). Graybiel score was recorded at the same time. Two groups' Graybiel score (12.67 +/- 11.78 vs 2.10 +/- 6.23; rank test P<0.05), caloric test labyrinth value [(19.02 +/- 8.59) degrees/s vs (13.58 +/- 5.25) degrees/s; t test P<0.05], caloric test labyrinth value of three patients in motion sickness group exceeded 75 degrees/s. In computerized posturography testing (CPT), motion sickness patients were central type (66.7%) and disperse type (23.3%); all of control group were central type. There was statistical significance in two groups' CTP area, and motion sickness group was obviously higher than control group. While stimulating vestibulum in CPT, there was abnormality (35%-50%) in motion sickness group and none in control group. Generally evaluating CPT, there was only 2 proprioceptive hypofunction, 3 visual hypofunction, and no vestibular hypofunction, but none hypofunction in control group. Motion sickness patients have high vestibular susceptible, some with vestibular hyperfunction. In posturography, a large number of motion sickness patients are central type but no vestibular hypofunction, but it is hard to keep balance when stimulating vestibulum.

  6. Improving Sensorimotor Function Using Stochastic Vestibular Stimulation

    Science.gov (United States)

    Galvan, R. C.; Clark, T. K.; Merfeld, D. M.; Bloomberg, J. J.; Mulavara, A. P.; Oman, C. M.

    2014-01-01

    Astronauts experience sensorimotor changes during spaceflight, particularly during G-transition phases. Post flight sensorimotor changes may include postural and gait instability, spatial disorientation, and visual performance decrements, all of which can degrade operational capabilities of the astronauts and endanger the crew. Crewmember safety would be improved if these detrimental effects of spaceflight could be mitigated by a sensorimotor countermeasure and even further if adaptation to baseline could be facilitated. The goal of this research is to investigate the potential use of stochastic vestibular stimulation (SVS) as a technology to improve sensorimotor function. We hypothesize that low levels of SVS will improve sensorimotor performance through stochastic resonance (SR). The SR phenomenon occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. Two studies have been initiated to investigate the beneficial effects and potential practical usage of SVS. In both studies, electrical vestibular stimulation is applied via electrodes on the mastoid processes using a constant current stimulator. The first study aims to determine the repeatability of the effect of vestibular stimulation on sensorimotor performance and perception in order to better understand the practical use of SVS. The beneficial effect of low levels of SVS on balance performance has been shown in the past. This research uses the same balance task repeated multiple times within a day and across days to study the repeatability of the stimulation effects. The balance test consists of 50 sec trials in which the subject stands with his or her feet together, arms crossed, and eyes closed on compliant foam. Varying levels of SVS, ranging from 0-700 micro A, are applied across different trials. The subject-specific optimal SVS level is that which results in the best balance performance as measured by inertial

  7. Corrosion Inhibition of the Galvanic Couple Copper-Carbon Steel in Reverse Osmosis Water

    Directory of Open Access Journals (Sweden)

    Irene Carrillo

    2011-01-01

    Full Text Available The purpose of this paper is to evaluate the electrochemical behaviour of corrosion inhibition of the copper-carbon steel galvanic couple (Cu-CS, exposed to reverse osmosis water (RO used for rinsing of heat exchangers for heavy duty machinery, during manufacture. Molybdate and nitrite salts were utilized to evaluate the inhibition behaviour under galvanic couple conditions. Cu-CS couple was used as working electrodes to measure open circuit potential (OCP, potentiodynamic polarization (PP, and electrochemical impedance spectroscopy (EIS. The surface conditions were characterized by scanning electron microscopy (SEM and electron dispersive X-ray spectroscopy (EDS. The most effective concentration ratio between molybdate and nitrite corrosion inhibitors was determined. The morphological study indicated molybdate deposition on the anodic sites of the galvanic couple. The design of molybdate-based corrosion inhibitor developed in the present work should be applied to control galvanic corrosion of the Cu-CS couple during cleaning in the manufacture of heat exchangers.

  8. Fiber Finishes for Improving Galvanic Resistance of Imide-Based Composites

    National Research Council Canada - National Science Library

    Allred, R. E

    1998-01-01

    The objective of this program is the development and demonstration of galvanic corrosion resistant carbon/ BMI composites through the use of reactive finishes to form coatings that isolate the carbon...

  9. Thin film galvanic cell with RbAg4I5 solid electrolyte

    International Nuclear Information System (INIS)

    Bodnaruk, L.I.; Danilov, A.V.; Kulinkovich, V.E.; Aleskovskij, V.B.

    1975-01-01

    In order to decrease the size and weight and to increase the specific capacity and energy of galvanic cells, some solid electrolytes in the form of thin films are proposed. The galvanic cells were prepared by a combined method: the cathodic and anodic materials (Te and Ag) were evaporated under vacuo to cover an electrolyte layer, the latter being obtained by impregnating the porous materials with RbAg 4 I 5 acetonic solution. The most specific charge curves of the galvanic cells at various current densities are given: specific energy of the samples was 0.2 to 0.7 watt-h/kg, their capacity being 0.1 to 0.2 mah. Behaviour of the cells when stored (that of Ag(RbAg 4 I 5 ) interface in particular) was investigated, namely, the effect of the storage time on the capacity and internal resistance of the galvanic cell

  10. Reaction kinetics of the formation of intermetallic Fe – Zn during hot - dip galvanizing of steel

    Directory of Open Access Journals (Sweden)

    P. Pokorny

    2016-01-01

    Full Text Available This review article mainly describes the composition of intermetallic Fe - Zn, i.e. zeta (ζ, delta (δ1k + δ1p, gamma1 (Γ1 and gamma (Γ on galvanized steel during low temperature galvanization (t ~ 450 °C. It gives detailed the formation, growth of individual phases during galvanization and their interaction. In terms of the kinetics, the formation of the coating is defined by a parabolic kinetic equation of the growth of different intermetallic phases under ideal conditions. From the available literature the rate constants of the formation of individual intermetallic phases and also for the total coating are cited. The composition of the intermetallic phases, iron content, crystal structure, and group symmetry in which the surface of galvanized steel forms.

  11. Studies into the Factors that Affects the Service Integrity of Galvanizing Kettle

    Directory of Open Access Journals (Sweden)

    Muhammed Olawale Hakeem AMUDA

    2008-12-01

    Full Text Available The finding of studies into the factors that affects optimal performance of galvanizing kettle is presented in this paper. The production schedule and history of a failed galvanizing kettle for 3-consecutively years in a hot-dip galvanizing industry was collated and analyzed. The analysis of the collated data revealed that average galvanizing temperatures for the 3-year under review were 483.9°C (2003, 482.25°C (2004 and 482°C (2005 respectively. The amount of flux, and dross produced in the corresponding years were 169.15kg and 31.6 tons, 56.31kg and 10.5 tons and 101.14 and 18.91 tonnes for 2003, 2004 and 2005 respectively. During these years, zinc consumed averaged 647, 334 and 446 tonnes respectively.Stochiometry evaluation of flux, and dross in a hot-dip galvanizing process determined flux required as 60 kg/year and dross produced as 90 slabs / month.The study revealed that the lifespan of galvanizing kettle is greatly reduced by temperature fluctuation, dross formation, excess flux additions and combinations of these factors.It is recommended that improved service integrity of galvanizing kettle is assured at galvanizing temperature of 460°C, flux consumption of 0.15 –0.20kg daily and constant removal of dross at 3-5 slabs per day. This reduces the formation of skim lines, which leads to pits on the walls of the kettle.

  12. Corrosion behaviour and galvanic coupling with steel of Al-based coating alternatives to electroplated cadmium

    Energy Technology Data Exchange (ETDEWEB)

    Fasuba, O.A.; Yerokhin, A., E-mail: A.Yerokhin@sheffield.ac.uk; Matthews, A.; Leyland, A.

    2013-08-15

    The galvanic corrosion behaviour of bare steel coupled to steel with an Al–Zn flake inorganic spin coating, an Al-based slurry sprayed coating, an arc sprayed Al coating and electroplated cadmium has been investigated. The sacrificial and galvanic behaviour of the coatings was studied in 3.5 wt. % NaCl solution using open-circuit potential, potentiodynamic polarisation and electrochemical noise measurements. The coatings were characterised by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Experimental results showed that the Al-based slurry sprayed coating exhibited an open-circuit potential closer to the steel substrate than other coatings, as well as a low corrosion current density and a more positive corrosion potential. In terms of the galvanic suitability of the investigated coatings for the steel substrate, both the Al–Zn flake inorganic spin coating and the Al-based slurry sprayed coating show low galvanic current, in comparison with the arc sprayed Al coating and electroplated cadmium. This behaviour confirms their superior cathodic protection capability and galvanic compatibility over other coatings tested. Electrochemical noise measurements provide accurate information on the coatings' galvanic behaviour, which can be complimented by the data obtained from superposition of potentiodynamic corrosion scans of the coating and bare steel, provided that the corrosion potential difference between the two materials does not exceed 300 mV. - Highlights: • Al-based slurry coating has best galvanic compatibility with steel. • Mg, Cr, P in Al-based slurry coating reinforce its corrosion resistance. • Ennoblement of Al–Zn flake coating compromises its cathodic protection. • Poor corrosion behaviour of arc sprayed Al coating caused by rough morphology. • Electrochemical noise provides adequate estimates of galvanic behaviour.

  13. Dynamic performance of maximum power point tracking circuits using sinusoidal extremum seeking control for photovoltaic generation

    Science.gov (United States)

    Leyva, R.; Artillan, P.; Cabal, C.; Estibals, B.; Alonso, C.

    2011-04-01

    The article studies the dynamic performance of a family of maximum power point tracking circuits used for photovoltaic generation. It revisits the sinusoidal extremum seeking control (ESC) technique which can be considered as a particular subgroup of the Perturb and Observe algorithms. The sinusoidal ESC technique consists of adding a small sinusoidal disturbance to the input and processing the perturbed output to drive the operating point at its maximum. The output processing involves a synchronous multiplication and a filtering stage. The filter instance determines the dynamic performance of the MPPT based on sinusoidal ESC principle. The approach uses the well-known root-locus method to give insight about damping degree and settlement time of maximum-seeking waveforms. This article shows the transient waveforms in three different filter instances to illustrate the approach. Finally, an experimental prototype corroborates the dynamic analysis.

  14. Inverse modelling and pulsating torque minimization of salient pole non-sinusoidal synchronous machines

    Energy Technology Data Exchange (ETDEWEB)

    Ait-gougam, Y.; Ibtiouen, R.; Touhami, O. [Laboratoire de Recherche en Electrotechnique, Ecole Nationale Polytechnique, BP 182, El-Harrach 16200 (Algeria); Louis, J.-P.; Gabsi, M. [Systemes et Applications des Technologies de l' Information et de l' Energie (SATIE), CNRS UMR 8029, Ecole Normale Superieure de Cachan, 61 Avenue du President Wilson, 94235 Cachan Cedex (France)

    2008-01-15

    Sinusoidal motor's mathematical models are usually obtained using classical d-q transformation in the case of salient pole synchronous motors having sinusoidal field distribution. In this paper, a new inverse modelling for synchronous motors is presented. This modelling is derived from the properties of constant torque curves in the Concordia's reference frame. It takes into account the non-sinusoidal field distribution; EMF, self and mutual inductances having non-sinusoidal variations with respect to the angular rotor position. Both copper losses and torque ripples are minimized by adapted currents waveforms calculated from this model. Experimental evaluation was carried out on a DSP-controlled PMSM drive platform. Test results obtained demonstrate the effectiveness of the proposed method in reducing torque ripple. (author)

  15. Influence of sinusoidal flow on the thermal and hydraulic performance of microchannel heat sink

    International Nuclear Information System (INIS)

    Om, N I; Gunnasegaran, P; Rajasegaran, S

    2013-01-01

    In this paper, the effect of sinusoidal flow on the thermal and hydraulic performance of microchannel heat sink (MCHS) is numerically investigated. This investigation covers Reynolds number in the range of 100 ≤ Re ≤ 1000 and pure water is used as a working fluid. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using finite volume method (FVM). The water flow field and heat transfer performance inside the sinusoidal microchannels is simulated and the results are compared with the straight microchannels. The effect of using sinusoidal microchannels on temperature distribution, Nusselt number, friction factor and thermal resistance is presented in this paper. It is found that with same rectangular cross-section, sinusoidal microchannels have a better heat transfer performance compared to the straight microchannels.

  16. Outcomes after vestibular rehabilitation and Wii® therapy in patients with chronic unilateral vestibular hypofunction.

    Science.gov (United States)

    Verdecchia, Daniel H; Mendoza, Marcela; Sanguineti, Florencia; Binetti, Ana C

    2014-01-01

    Vestibular rehabilitation therapy is an exercise-based programme designed to promote central nervous system compensation for inner ear deficit. The objective of the present study was to analyse the differences in the perception of handicap, the risk of falls, and gaze stability in patients diagnosed with chronic unilateral vestibular hypofunction before and after vestibular rehabilitation treatment with complementary Wii® therapy. A review was performed on the clinical histories of patients in the vestibular rehabilitation area of a university hospital between April 2009 and May 2011. The variables studied were the Dizziness Handicap Inventory, the Dynamic Gait Index and dynamic visual acuity. All subjects received complementary Wii® therapy. There were 69 cases (41 woman and 28 men), with a median age of 64 years. The initial median Dizziness Handicap Inventory score was 40 points (range 0-84, percentile 25-75=20-59) and the final, 24 points (range 0-76, percentile 25-75=10.40), P<.0001. The initial median for the Dynamic Gait Index score was 21 points (range 8-24, percentile 25-75=17.5-2.3) and the final, 23 (range 12-24, percentile 25-75=21-23), P<.0001. The initial median for dynamic visual acuity was 2 (range 0-6, percentile 25-75=1-4) and the final, 1 (range 0-3, percentile 25-75=0-2), P<.0001. A reduction was observed in the Dizziness Handicap Inventory Values. Values for the Dynamic Gait Index increased and dynamic visual acuity improved. All these variations were statistically significant. Copyright © 2013 Elsevier España, S.L.U. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

  17. Influence of MAO Treatment on the Galvanic Corrosion Between Aluminum Alloy and 316L Steel

    Science.gov (United States)

    Yang, Yuanhang; Gu, Yanhong; Zhang, Lei; Jiao, Xiangdong; Che, Juntie

    2017-12-01

    To slow down the galvanic corrosion of aluminum alloy and 316L stainless steel in subsea water, a micro-arc oxidation (MAO) coating was prepared on the surface of the Al alloy, and no treatment was performed on the surface of the 316L. The surface morphology of MAO-coated Al alloy was evaluated using a scanning electron microscope (SEM) before and after corrosion. A micro-hardness tester was used to measure the micro-hardness. Corrosion behaviors were evaluated by open-circuit potential (OCP), potentiodynamic polarization (PDP) and electrode impedance spectroscopy (EIS) tests in a 3.5 g/L NaCl solution. The results of PDP testing show that the corrosion potential of the MAO-coated galvanic pair was more positive than that of the uncoated galvanic pair and that the corrosion current density was smaller than that of the uncoated galvanic pair. EIS results show that the impedance of the galvanic pair increased after MAO coating. SEM images show that the corrosion damage of the uncoated Al alloy was more severe than that of the MAO-coated one, and the post-corrosion images of the surface of the 316L connected with MAO-coated Al alloy were more compact than those of the 316L connected with uncoated Al alloy. A physical model was developed to discuss the influence of MAO treatment on the galvanic corrosion process and corrosion mechanism.

  18. An optimized method for mouse liver sinusoidal endothelial cell isolation

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Jeremy, E-mail: jeremy.meyer@hcuge.ch [Division of Digestive and Transplantation Surgery, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Genève 14 (Switzerland); Unit of Surgical Research, University of Geneva, Rue Michel-Servet 1, 1206 Genève (Switzerland); Lacotte, Stéphanie, E-mail: stephanie.lacotte@unige.ch [Unit of Surgical Research, University of Geneva, Rue Michel-Servet 1, 1206 Genève (Switzerland); Morel, Philippe, E-mail: philippe.morel@hcuge.ch [Division of Digestive and Transplantation Surgery, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Genève 14 (Switzerland); Unit of Surgical Research, University of Geneva, Rue Michel-Servet 1, 1206 Genève (Switzerland); Gonelle-Gispert, Carmen, E-mail: carmen.gonelle@unige.ch [Unit of Surgical Research, University of Geneva, Rue Michel-Servet 1, 1206 Genève (Switzerland); Bühler, Léo, E-mail: leo.buhler@hcuge.ch [Division of Digestive and Transplantation Surgery, University Hospitals of Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Genève 14 (Switzerland); Unit of Surgical Research, University of Geneva, Rue Michel-Servet 1, 1206 Genève (Switzerland)

    2016-12-10

    The objective of the present study was to develop an accurate and reproducible method for liver sinusoidal endothelial cell (LSEC) isolation in mice. Non-parenchymal cells were isolated using a modified two-step collagenase digestion combined with Optiprep density gradient centrifugation. LSEC were further purified using two prevalent methods, short-term selective adherence and CD146+ magnetic-activated cell sorting (MACS), and compared in terms of cell yield, viability and purity to our purification technique using CD11b cell depletion combined with long-term selective adherence. LSEC purification using our technique allowed to obtain 7.07±3.80 million LSEC per liver, while CD146+ MACS and short-term selective adherence yielded 2.94±1.28 and 0.99±0.66 million LSEC, respectively. Purity of the final cell preparation reached 95.10±2.58% when using our method. In contrast, CD146+ MACS and short-term selective adherence gave purities of 86.75±3.26% and 47.95±9.82%, respectively. Similarly, contamination by non-LSEC was the lowest when purification was performed using our technique, with a proportion of contaminating macrophages of only 1.87±0.77%. Further, isolated cells analysed by scanning electron microscopy presented typical LSEC fenestrations organized in sieve plates, demonstrating that the technique allowed to isolate bona fide LSEC. In conclusion, we described a reliable and reproducible technique for the isolation of high yields of pure LSEC in mice. This protocol provides an efficient method to prepare LSEC for studying their biological functions. - Highlights: • This protocol provides an efficient method to prepare primary mouse LSEC for studying their biological functions. • The liver cell dispersion step was improved by performing a retrograde cannulation of the liver. • The cell yield and the purity obtained were higher than comparative techniques in mice. • Contaminating macrophages were removed by introducing a CD11b- magnetic

  19. An optimized method for mouse liver sinusoidal endothelial cell isolation

    International Nuclear Information System (INIS)

    Meyer, Jeremy; Lacotte, Stéphanie; Morel, Philippe; Gonelle-Gispert, Carmen; Bühler, Léo

    2016-01-01

    The objective of the present study was to develop an accurate and reproducible method for liver sinusoidal endothelial cell (LSEC) isolation in mice. Non-parenchymal cells were isolated using a modified two-step collagenase digestion combined with Optiprep density gradient centrifugation. LSEC were further purified using two prevalent methods, short-term selective adherence and CD146+ magnetic-activated cell sorting (MACS), and compared in terms of cell yield, viability and purity to our purification technique using CD11b cell depletion combined with long-term selective adherence. LSEC purification using our technique allowed to obtain 7.07±3.80 million LSEC per liver, while CD146+ MACS and short-term selective adherence yielded 2.94±1.28 and 0.99±0.66 million LSEC, respectively. Purity of the final cell preparation reached 95.10±2.58% when using our method. In contrast, CD146+ MACS and short-term selective adherence gave purities of 86.75±3.26% and 47.95±9.82%, respectively. Similarly, contamination by non-LSEC was the lowest when purification was performed using our technique, with a proportion of contaminating macrophages of only 1.87±0.77%. Further, isolated cells analysed by scanning electron microscopy presented typical LSEC fenestrations organized in sieve plates, demonstrating that the technique allowed to isolate bona fide LSEC. In conclusion, we described a reliable and reproducible technique for the isolation of high yields of pure LSEC in mice. This protocol provides an efficient method to prepare LSEC for studying their biological functions. - Highlights: • This protocol provides an efficient method to prepare primary mouse LSEC for studying their biological functions. • The liver cell dispersion step was improved by performing a retrograde cannulation of the liver. • The cell yield and the purity obtained were higher than comparative techniques in mice. • Contaminating macrophages were removed by introducing a CD11b- magnetic

  20. Improved results for vestibular schwannoma radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Flickinger, J C; Kondziolka, D; Pollock, B; Lunsford, L D

    1995-07-01

    PURPOSE/OBJECTIVE: Treatment techniques in radiosurgery have changed since 1987. We reviewed patients who received radiosurgery for vestibular schwannoma to identify these changes and to investigate any differences in tumor control and complications. MATERIALS and METHODS: One hundred thirty-eight unilateral vestibular schwannoma patients with a minimum follow-up of two years after treatment with gamma knife radiosurgery between 1987 and 1992 were analyzed. The early treatment group consisted of 55 patients treated between 1987-1989 (median: tumor volume 3.63 cc, Dmin 18.1 Gy, Dmax 35.4 Gy, isocenters 2.3, follow-up 50.4 mos.). The later treatment group consisted of 83 patients treated between 1990-1992 (median: tumor volume 3.81 cc, Dmin 16.0 Gy, Dmax 31.6 Gy, isocenters 4.7, follow-up 35.8 mos.) RESULTS: Clinical tumor recurrence requiring surgical intervention occurred in one patient in each group. The overall actuarial clinical tumor control rate was 98%. Slight increases in tumor size (1 to 2 mm) were identified in five other patients not requiring intervention, because of no further tumor growth (n=4) or shrinkage (n=1). This led to an overall radiologic tumor control rate of 92% (not significantly different in either group). Compared to the early treatment group, the incidence of facial neuropathy (temporary or permanent) decreased in the later group (49% vs. 11%, p < 0.0001), as did trigeminal neuropathy (40% vs. 8%, p < 0.0001). Serviceable hearing preservation improved only slightly in the later group (27% vs. 40%, p = 0.70). CONCLUSION: We document a significant decrease in the morbidity of vestibular schwannoma radiosurgery over this time period with no decrease in the high rate of tumor control. This improvement is attributed to a) better conformal dose-planning with stereotactic MRI rather than CT, b) an increase in the number of isocenters used, and c) a reduction in the average dose administered by 2 Gy.

  1. Proton beam stereotactic radiosurgery of vestibular schwannomas

    International Nuclear Information System (INIS)

    Harsh, Griffith R.; Thornton, Allan F.; Chapman, Paul H.; Bussiere, Marc R.; Rabinov, James D.; Loeffler, Jay S.

    2002-01-01

    Purpose: The proton beam's Bragg peak permits highly conformal radiation of skull base tumors. This study, prompted by reports of transient (30% each) and permanent (10% each) facial and trigeminal neuropathy after stereotactic radiosurgery of vestibular schwannomas with marginal doses of 16-20 Gy, assessed whether proton beam radiosurgery using a marginal dose of only 12 Gy could control vestibular schwannomas while causing less neuropathy. Methods and Materials: Sixty-eight patients (mean age 67 years) were treated between 1992 and 1998. The mean tumor volume was 2.49 cm 3 . The dose to the tumor margin (70% isodose line) was 12 Gy. The prospectively specified follow-up consisted of neurologic evaluation and MRI at 6, 12, 24, and 36 months. Results: After a mean clinical follow-up of 44 months and imaging follow-up of 34 months in 64 patients, 35 tumors (54.7%) were smaller and 25 (39.1%) were unchanged (tumor control rate 94%; actuarial control rate 94% at 2 years and 84% at 5 years). Three tumors enlarged: one shrank after repeated radiosurgery, one remained enlarged at the time of unrelated death, and one had not been imaged for 4 years in a patient who remained asymptomatic at last follow-up. Intratumoral hemorrhage into one stable tumor required craniotomy that proved successful. Thus, 97% of tumors required no additional treatment. Three patients (4.7%) underwent shunting for hydrocephalus evident as increased ataxia. Of 6 patients with functional hearing ipsilaterally, 1 improved, 1 was unchanged, and 4 progressively lost hearing. Cranial neuropathies were infrequent: persistent facial hypesthesia (2 new, 1 exacerbated; 4.7%); intermittent facial paresthesias (5 new, 1 exacerbated; 9.4%); persistent facial weakness (2 new, 1 exacerbated; 4.7%) requiring oculoplasty; transient partial facial weakness (5 new, 1 exacerbated; 9.4%), and synkinesis (5 new, 1 exacerbated; 9.4%). Conclusion: Proton beam stereotactic radiosurgery of vestibular schwannomas at the

  2. Walking strategies of visually impaired people on trapezoidal- and sinusoidal-section tactile groundsurface indicators.

    Science.gov (United States)

    Ranavolo, A; Conte, C; Iavicoli, S; Serrao, M; Silvetti, A; Sandrini, G; Pierelli, F; Draicchio, F

    2011-03-01

    The visual system in walking serves to perceive feedback or feed-forward signals. Therefore, visually impaired persons (VIP) have biased motor control mechanisms. The use of leading indicators (LIs) and long canes helps to improve their walking efficiency. The aims of this study were to compare the walking efficiency of VIP on trapezoidal- and sinusoidal-section LIs using an optoelectronic motion analysis system. VIP displayed a significantly longer stance phase, a shorter swing phase and shorter step and stride lengths when they walked on the sinusoidal LI than when they walked on the trapezoidal LI. Compared with the trapezoidal LI, VIP walking on the sinusoidal LI displayed significantly lower joint ranges of motion. The centre of mass lateral displacement was wider for VIP walking on the sinusoidal LI than on the trapezoidal LI. Some significant differences were also found in sighted persons walking on both LIs. In conclusion, the trapezoidal shape enabled visually impaired subjects to walk more efficiently, whereas the sinusoidal shape caused dynamic balance problems. STATEMENT OF RELEVANCE: These findings suggest that VIP can walk more efficiently, with a lower risk of falls, on trapezoidal-section than on sinusoidal-section LIs. These results should be considered when choosing the most appropriate ground tactile surface indicators for widespread use.

  3. Crashworthiness Analysis and Evaluation of Fuselage Section with Sub-floor Composite Sinusoidal Specimens

    Directory of Open Access Journals (Sweden)

    H.L. Mou

    Full Text Available Abstract Crashworthiness is one of the main concerns in civil aviation safety particularly with regard to the increasing ratio of carbon fiber reinforced plastic (CFRP in aircraft primary structures. In order to generate dates for model validations, the mechanical properties of T700/3234 were obtained by material performance tests, and energy-absorbing results were gained by quasi-static crushing tests of composite sinusoidal specimens. The correctness of composite material model and single-layer finite element model of composite sinusoidal specimens were verified based on the simulation results and test results that were in good agreement. A typical civil aircraft fuselage section with composite sinusoidal specimens under cargo floor was suggested. The crashworthiness of finite element model of fuselage section was assessed by simulating the vertical drop test subjected to 7 m/s impact velocity, and the influences of different thickness of sub-floor composite sinusoidal specimens on crashworthiness of fuselage section were also analyzed. The simulation results show that the established finite element model can accurately simulate the crushing process of composite sinusoidal specimens; the failure process of fuselage section is more stable, and the safety of occupants can be effectively improved because of the smaller peak accelerations that was limited to human tolerance, a critical thickness of sub-floor composite sinusoidal specimens can restrict the magnitude of acceleration peaks, which has certain reference values for enhancing crashworthiness capabilities of fuselage section and improving the survivability of passengers.

  4. Balancing awareness: Vestibular signals modulate visual consciousness in the absence of awareness.

    Science.gov (United States)

    Salomon, Roy; Kaliuzhna, Mariia; Herbelin, Bruno; Blanke, Olaf

    2015-11-01

    The processing of visual and vestibular information is crucial for perceiving self-motion. Visual cues, such as optic flow, have been shown to induce and alter vestibular percepts, yet the role of vestibular information in shaping visual awareness remains unclear. Here we investigated if vestibular signals influence the access to awareness of invisible visual signals. Using natural vestibular stimulation (passive yaw rotations) on a vestibular self-motion platform, and optic flow masked through continuous flash suppression (CFS) we tested if congruent visual-vestibular information would break interocular suppression more rapidly than incongruent information. We found that when the unseen optic flow was congruent with the vestibular signals perceptual suppression as quantified with the CFS paradigm was broken more rapidly than when it was incongruent. We argue that vestibular signals impact the formation of visual awareness through enhanced access to awareness for congruent multisensory stimulation. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. [Presbyastasis and application of vestibular rehabilitation in geriatrics].

    Science.gov (United States)

    Costa de Araujo, P; Demanez, L; Lechien, J; Bauvir, P; Petermans, J

    2011-03-01

    Balance disorders can have a major functional impact among the elderly. The main risk is falling. Three elements are implicated in the loss of balance: vision, proprioception and the vestibular system. This article will discuss mainly vestibular damage and its implications. The assessment of balance disorders, particularly in geriatric patients, is based on validated scales composed of several items. These provide scores and are based on the results of chronometric measurements. They can be useful for the application of Vestibular Rehabilitation (VR), a technique improving the adaptation and autonomy of these patients. Vestibular rehabilitation is therefore part of an overall support, the goal of therapy being to improve daily life and to reduce the risk of falls.

  6. Vestibular signals in primate cortex for self-motion perception.

    Science.gov (United States)

    Gu, Yong

    2018-04-21

    The vestibular peripheral organs in our inner ears detect transient motion of the head in everyday life. This information is sent to the central nervous system for automatic processes such as vestibulo-ocular reflexes, balance and postural control, and higher cognitive functions including perception of self-motion and spatial orientation. Recent neurophysiological studies have discovered a prominent vestibular network in the primate cerebral cortex. Many of the areas involved are multisensory: their neurons are modulated by both vestibular signals and visual optic flow, potentially facilitating more robust heading estimation through cue integration. Combining psychophysics, computation, physiological recording and causal manipulation techniques, recent work has addressed both the encoding and decoding of vestibular signals for self-motion perception. Copyright © 2018. Published by Elsevier Ltd.

  7. Inner ear malformations in siblings presenting with vestibular ...

    African Journals Online (AJOL)

    Any child presenting with vestibular symptoms should be referred for an audiological assessment. I R T Butler, MMed ... rhythmically to music. The patient was ... was enrolled in an intensive speech therapy programme at age 2 years 7 months.

  8. Distinct spontaneous shrinkage of a sporadic vestibular schwannoma

    DEFF Research Database (Denmark)

    Huang, Xiaowen; Cayé-Thomasen, Per; Stangerup, Sven-Eric

    2013-01-01

    on "shrinkage" or "negative growth" or "regression" or "involution" of the tumor were selected, and the contents on the rate, extent and mechanism of spontaneous tumor shrinkage were extracted and reviewed. The reported rate of spontaneous shrinkage of vestibular schwannoma is 5-10% of patients managed......We present a case with outspoken spontaneous vestibular schwannoma shrinkage and review the related literature. The patient was initially diagnosed with a left-sided, intrameatal vestibular schwannoma, which subsequently grew into the cerebello-pontine angle (CPA), followed by total shrinkage...... of the CPA component without any intervention over a 12-year observation period. The literature on spontaneous tumor shrinkage was retrieved by searching the subject terms "vestibular schwannoma, conservative management" in PubMed/MEDLINE database, without a time limit. Of the published data, the articles...

  9. Caloric vestibular stimulation in aphasic syndrome

    Directory of Open Access Journals (Sweden)

    David eWilkinson

    2013-12-01

    Full Text Available Caloric vestibular stimulation (CVS is commonly used to diagnose brainstem disorder but its therapeutic application is much less established. Based on the finding that CVS increases blood flow to brain structures associated with language and communication, we assessed whether the procedure has potential to relieve symptoms of post-stroke aphasia. Three participants, each presenting with chronic, unilateral lesions to the left hemisphere, were administered daily CVS for 4 consecutive weeks. Relative to their pre-treatment baseline scores, two of the three participants showed significant improvement on both picture and responsive naming at immediate and one-week follow-up. One of these participants also showed improved sentence repetition, and another showed improved auditory word discrimination. No adverse reactions were reported. These data provide the first, albeit tentative, evidence that CVS may relieve expressive and receptive symptoms of aphasia. A larger, sham-controlled study is now needed to further assess efficacy.

  10. Vestibular syndrome in giant anteater (Myrmecophaga tridactyla)

    OpenAIRE

    Oliveira, Fabricio Singaretti de; Gubulin Carvalho, Paula Fernanda; Bueno de Camargo, Mauro Henrique; Delfini, Aline; Martins, Leandro [UNESP

    2009-01-01

    A síndrome vestibular é uma afecção bem descrita em animais domésticos e pouco relatada em selvagens. Este relato descreveu essa afecção de origem central em uma fêmea adulta de tamanduá-bandeira (Myrmecophaga tridactyla), caquética, apresentando deambulação em círculos, hipermetria extensora nos membros torácicos, desvio da cabeça e nistagmo espontâneo horizontal e posicional vertical. O animal foi alimentado por sonda oral, 2x/dia e instituiu-se tratamento com dexametasona subcutânea na dos...

  11. Outcome after translabyrinthine surgery for vestibular schwannomas

    DEFF Research Database (Denmark)

    Springborg, Jacob Bertram; Fugleholm, Kåre; Poulsgaard, Lars

    2012-01-01

    The objective of this article is to study the outcome after translabyrinthine surgery for vestibular schwannomas, with special focus on the facial nerve function. The study design is a case series from a national centralized database and it is set in two University Hospitals in Denmark....... Participants were 1244 patients who underwent translabyrinthine surgery during a period of 33 years from 1976 to 2009. Main outcome measures were tumor removal, intraoperative facial nerve preservation, complications, and postoperative facial nerve function. In 84% patients, the tumor was totally resected...... and in ~85% the nerve was intact during surgery. During 33 years, 12 patients died from complications to surgery and ~14% had cerebrospinal fluid leakage. Before surgery, 74 patients had facial paresis and 46% of these improved after surgery. In patients with normal facial function, overall ~70% had a good...

  12. Timing of neuron development in the rodent vestibular system

    Science.gov (United States)

    Keefe, J. R.

    1982-01-01

    The timing of cell generation (onset and duration) in the developing rat vestibular and proprioceptive systems is investigated. The results clearly indicate a defined time-span for generation of all neurons in the central nervous system nuclei studied. This cytogenetic period in both vestibular and proprioceptive sensory nuclei is determined to occur during and immediately after placentation, a potentially critical period for spaceflight exposure due to alterations in maternal physiology.

  13. Morphological analysis of the vestibular aqueduct by computerized tomography images

    International Nuclear Information System (INIS)

    Marques, Sergio Ricardo; Smith, Ricardo Luiz; Isotani, Sadao; Alonso, Luis Garcia; Anadao, Carlos Augusto; Prates, Jose Carlos; Lederman, Henrique Manoel

    2007-01-01

    Objective: In the last two decades, advances in the computerized tomography (CT) field revise the internal and medium ear evaluation. Therefore, the aim of this study is to analyze the morphology and morphometric aspects of the vestibular aqueduct on the basis of computerized tomography images (CTI). Material and method: Computerized tomography images of vestibular aqueducts were acquired from patients (n = 110) with an age range of 1-92 years. Thereafter, from the vestibular aqueducts images a morphometric analysis was performed. Through a computerized image processing system, the vestibular aqueduct measurements comprised of its area, external opening, length and the distance from the vestibular aqueduct to the internal acoustic meatus. Results: The morphology of the vestibular aqueduct may be funnel-shaped, filiform or tubular and the respective proportions were found to be at 44%, 33% and 22% in children and 21.7%, 53.3% and 25% in adults. The morphometric data showed to be of 4.86 mm 2 of area, 2.24 mm of the external opening, 4.73 mm of length and 11.88 mm of the distance from the vestibular aqueduct to the internal acoustic meatus, in children, and in adults it was of 4.93 mm 2 , 2.09 mm, 4.44 mm, and 11.35 mm, respectively. Conclusions: Computerized tomography showed that the vestibular aqueduct presents high morphological variability. The morphometric analysis showed that the differences found between groups of children and adults or between groups of both genders were not statistically significant

  14. Early and phasic cortical metabolic changes in vestibular neuritis onset.

    Directory of Open Access Journals (Sweden)

    Marco Alessandrini

    Full Text Available Functional brain activation studies described the presence of separate cortical areas responsible for central processing of peripheral vestibular information and reported their activation and interactions with other sensory modalities and the changes of this network associated to strategic peripheral or central vestibular lesions. It is already known that cortical changes induced by acute unilateral vestibular failure (UVF are various and undergo variations over time, revealing different cortical involved areas at the onset and recovery from symptoms. The present study aimed at reporting the earliest change in cortical metabolic activity during a paradigmatic form of UVF such as vestibular neuritis (VN, that is, a purely peripheral lesion of the vestibular system, that offers the opportunity to study the cortical response to altered vestibular processing. This research reports [(18F]fluorodeoxyglucose positron emission tomography brain scan data concerning the early cortical metabolic activity associated to symptoms onset in a group of eight patients suffering from VN. VN patients' cortical metabolic activity during the first two days from symptoms onset was compared to that recorded one month later and to a control healthy group. Beside the known cortical response in the sensorimotor network associated to vestibular deafferentation, we show for the first time the involvement of Entorhinal (BAs 28, 34 and Temporal (BA 38 cortices in early phases of symptomatology onset. We interpret these findings as the cortical counterparts of the attempt to reorient oneself in space counteracting the vertigo symptom (Bas 28, 34 and of the emotional response to the new pathologic condition (BA 38 respectively. These interpretations were further supported by changes in patients' subjective ratings in balance, anxiety, and depersonalization/derealization scores when tested at illness onset and one month later. The present findings contribute in expanding

  15. Vestibular Function in Adults With Epilepsy of Unknown Etiology.

    Science.gov (United States)

    Hamed, Sherifa A; Tohamy, Amal M; Oseilly, Amira M

    2017-09-01

    This study aimed to evaluate vestibular function in adults with chronic epilepsy of unknown etiology in the inter-ictal period. Epilepsy is a chronic medical disorder. Life-long therapy may be required in one-third of patients. Epilepsy is associated with comorbid somatic conditions which impairs patients' quality of life. This cross-sectional study included 28 with generalized tonic clonic (GTC) convulsions and 14 and 3 with temporal (TLE) and frontal lobe (FLE) epilepsies with secondary generalization (all were on regular carbamazepine therapy) and 40 healthy control subjects. The patients' mean age was 34.97 ± 7.35 years and the duration of illness was 18.75 ± 7.99 years. All underwent videonystagmography (VNG). Compared with controls, patients had frequent vestibular symptoms including dizziness (62.22%) (p = 0.0001) and sense of imbalance (44.44%) (p = 0.0001). Eleven patients (24.44%) had central vestibular dysfunction (p = 0.0001); 9 (20%) had mixed vestibular dysfunction and one (2.22%) had peripheral vestibular dysfunction (p = 0.0001). Abnormalities were observed in saccadic (44.4%) and pursuit (42.2%) eye movements, optokinetic nystagmus (42.2%) and positioning/positional (11.11%) and caloric (13.33%) testing. TLE and FLE were associated with more VNG abnormalities than GTC. No significant differences were observed in the demographic and clinical characteristics between patients with and without VNG abnormalities. Vestibular manifestations are frequent in patients with epilepsy. This may be a result of the permanent damaging effect of chronic epilepsy on the vestibular cortical areas and/or a toxic effect from prolonged carbamazepine therapy on the peripheral and central vestibular systems.

  16. Quality of life in patients after vestibular Schwannoma surgery

    OpenAIRE

    Hajná, Barbora

    2011-01-01

    TVestibular schwannoma is a benign tumor that arises from the Schwann cells of the vestibular nerve. Unilateral hearing loss, tinnitus, facial and trigeminal dysfunction and vertigo are the most common symptoms. Surgical removal of the tumor is one of the treatment modalities of this disease. Surgical excision usually involves the complete vestibular nerve resection and there is also a risk of cochlear and facial nerve lesion. This thesis deals with changes in quality of life in patients afte...

  17. DFT study on the galvanic interaction between pyrite (100) and galena (100) surfaces

    International Nuclear Information System (INIS)

    Ke, Baolin; Li, Yuqiong; Chen, Jianhua; Zhao, Cuihua; Chen, Ye

    2016-01-01

    Graphical abstract: - Highlights: • Galvanic interaction is weakened with the increase of contact distance. • Electronic transfer mainly occurs on the contact layers. • Galvanic effect enhances nucleophilicity of galena and electrophilicity of pyrite. • Presence of H_2O increases the galvanic interaction. - Abstract: The galvanic interaction between pyrite and galena surface has been investigated using density functional theory (DFT) method. The calculated results show that galvanic interactions between pyrite and galena surface are decreased with the increase of contact distance. The galvanic interactions still occurs even the distance larger than the sum of two atoms radius (≈2.8 Å), and the limit distance of galvanic interaction between galena and pyrite surface is about 10 Å, which is consistent with the quantum tunneling effect. Through Mulliken charge population calculation, it is found that electrons transfer from galena to pyrite. For galena surface, Pb 6s and 6p states lose electrons and S 3p state loses a small amount of electrons, which causes the electron loss of galena. For pyrite surface, Fe 4p state obtains large numbers of electrons, resulting in the decrease of positive charge of Fe atom. However, the 3p state of S atom loses a small numbers of electrons. The reactivity of mineral surface has also been studied by calculating the frontier orbitals of minerals. Results suggest that the highest occupied molecular orbital (HOMO) coefficients of galena are increased whereas those of pyrite are decreased with the enhancing galvanic interaction, indicating that the oxidation of galena surface would be enhanced due to the galvanic interaction. The Fukui indices and dual descriptor values of surface atoms suggest that the nucleophilicity of the galena surface increases, meanwhile, the electrophilicity of pyrite surface increases with the decrease of the contact distance. In addition, the density of states (DOS) of atoms results show that the

  18. Corrosion by galvanic coupling on the steam generator auxiliary feedwater pumps at the level of the steam-tight boxes

    International Nuclear Information System (INIS)

    Dordonat, M.; Huet, M.

    1994-01-01

    Corrosion by galvanic coupling in steam generator auxiliary pump is coming from electroplated chromium cracks for the rotor steel, and from chemical KANIGEN nickel cracks for the steam-tight boxes black steel. To avoid galvanic coupling between Cr coating and the rotor steel, first an electrolytic Ni coating is done followed by an electrolytic Cr coating. To avoid galvanic coupling between black steel and graphite rings, black steel is replaced by 316L steel. (A.B.). 1 ref., 7 figs

  19. Isolation and culture of adult mouse vestibular nucleus neurons

    Science.gov (United States)

    Him, Aydın; Altuntaş, Serap; Öztürk, Gürkan; Erdoğan, Ender; Cengiz, Nureddin

    2017-12-19

    Background/aim: Isolated cell cultures are widely used to study neuronal properties due to their advantages. Although embryonic animals are preferred for culturing, their morphological or electrophysiological properties may not reflect adult neurons, which may be important in neurodegenerative diseases. This paper aims to develop a method for preparing isolated cell cultures of medial vestibular nucleus (MVN) from adult mice and describe its morphological and electrophysiological properties.Materials and methods: Vestibular nucleus neurons were mechanically and enzymatically isolated and cultured using a defined medium with known growth factors. Cell survival was measured with propidium iodide, and electrophysiological properties were investigated with current-clamp recording.Results: Vestibular neurons grew neurites in cultures, gaining adult-like morphological properties, and stayed viable for 3 days in culture. Adding bovine calf serum, nerve growth factor, or insulin-like growth factor into the culture medium enhanced neuronal viability. Current-clamp recording of the cultured neurons revealed tonic and phasic-type neurons with similar input resistance, resting membrane potential, action potential amplitude, and duration. Conclusion: Vestibular neurons from adult mice can be cultured, and regenerate axons in a medium containing appropriate growth factors. Culturing adult vestibular neurons provides a new method to study age-related pathologies of the vestibular system.

  20. Galvanic corrosion: a microsystems device integrity and reliability concern

    Science.gov (United States)

    Miller, David C.; Hughes, William L.; Wang, Zhong L.; Gall, Ken; Stoldt, Conrad R.

    2006-01-01

    We have studied the corrosion of phosphorus-doped polySi when contacted to a gold metallization layer and exposed to various hydrofluoric acid (HF) based chemistries, including mixtures with HCl, C IIH 6O, H IIO, NH 4F, Triton-X-100, as well as vapor-based HF. Here, we utilize optical-, electron-, and atomic-force-microscopy, optical interferometry, as well as instrumented indentation ("nanoindentation") to characterize test and reference specimens exposed to the various HF solutions. These measurements provide information concerning the appearance, roughness, physical dimensions, hardness, elastic modulus, and reverse phase transformation activity of the various polysilicon specimens. In general, some of the chemistries produced time-dependent darkening or "staining" visibly seen on free surfaces, roughening and attack at grain boundaries, nano-scale pitting of the free surfaces, decrease in thickness, decrease in hardness and mechanical modulus, and diminished elbow and reverse excursion activity for those silicon specimens electrically connected to metal. Change in performance is attributed to the formation of a galvanic cell during the HF immersion, and the corresponding damage driven by an anodic current. The results here can be used to explain previous work, which focused on the change in performance of designated MEMS diagnostic structures.

  1. Methanol oxidation at platinized copper particles prepared by galvanic replacement

    Directory of Open Access Journals (Sweden)

    Ioanna Mintsouli

    2016-04-01

    Full Text Available Bimetallic Pt-Cu particles have been prepared by galvanic replacement of Cu precursor nanoparticles, upon the treatment of the latter with a chloro-platinate acidic solution. The resulting particles, typically a few tens of nm large, were supported on high surface area carbon (Vulcan® XC–72R, Cabot and tested as electrodes. Surface electrochemistry in deaerated acid solutions was similar to that of pure Pt, indicating the existence of a Pt shell (hence the particles are denoted as Pt(Cu. Pt(Cu/C supported catalysts exhibit superior carbon monoxide and methanol oxidation activity with respect to their Pt/C analogues when compared on a per electroactive surface area basis, due to the modification of Pt activity by Cu residing in the particle core. However, as a result of large particle size and agglomeration phenomena, Pt(Cu/C are still inferior to Pt/C when compared on a mass specific activity basis.

  2. Study on the wiping gas jet in continuous galvanizing line

    Science.gov (United States)

    Kweon, Yong-Hun; Kim, Heuy-Dong

    2011-09-01

    In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.

  3. Synthesis of chromium containing pigments from chromium galvanic sludges

    International Nuclear Information System (INIS)

    Andreola, F.; Barbieri, L.; Bondioli, F.; Cannio, M.; Ferrari, A.M.; Lancellotti, I.

    2008-01-01

    In this work the screening results of the scientific activity conducted on laboratory scale to valorise chromium(III) contained in the galvanic sludge as chromium precursor for ceramic pigments are reported. The valorisation of this waste as a secondary raw material (SRM) is obtained by achievement of thermal and chemical stable crystal structures able to color ceramic material. Two different pigments pink CaCr 0.04 Sn 0.97 SiO 5 and green Ca 3 Cr 2 (SiO 4 ) 3 were synthesized by solid-state reactions using dried Cr sludge as chromium oxide precursor. The obtained pigments were characterized by X-ray diffraction and SEM analysis. Furthermore the color developed in a suitable ceramic glaze was investigated in comparison with the color developed by the pigments prepared from pure Cr 2 O 3 . The characterization carried out corroborates the thermal and chemical stability of the synthesized pigments and, especially for the Cr-Sn pink pigment, the powders develop an intense color that is very similar to the color developed by the pigments obtained starting from pure Cr 2 O 3

  4. Galvanic Cell Type Sensor for Soil Moisture Analysis.

    Science.gov (United States)

    Gaikwad, Pramod; Devendrachari, Mruthyunjayachari Chattanahalli; Thimmappa, Ravikumar; Paswan, Bhuneshwar; Raja Kottaichamy, Alagar; Makri Nimbegondi Kotresh, Harish; Thotiyl, Musthafa Ottakam

    2015-07-21

    Here we report the first potentiometric sensor for soil moisture analysis by bringing in the concept of Galvanic cells wherein the redox energies of Al and conducting polyaniline are exploited to design a battery type sensor. The sensor consists of only simple architectural components, and as such they are inexpensive and lightweight, making it suitable for on-site analysis. The sensing mechanism is proved to be identical to a battery type discharge reaction wherein polyaniline redox energy changes from the conducting to the nonconducting state with a resulting voltage shift in the presence of soil moisture. Unlike the state of the art soil moisture sensors, a signal derived from the proposed moisture sensor is probe size independent, as it is potentiometric in nature and, hence, can be fabricated in any shape or size and can provide a consistent output signal under the strong aberration conditions often encountered in soil moisture analysis. The sensor is regenerable by treating with 1 M HCl and can be used for multiple analysis with little read out hysteresis. Further, a portable sensor is fabricated which can provide warning signals to the end user when the moisture levels in the soil go below critically low levels, thereby functioning as a smart device. As the sensor is inexpensive, portable, and potentiometric, it opens up avenues for developing effective and energy efficient irrigation strategies, understanding the heat and water transfer at the atmosphere-land interface, understanding soil mechanics, forecasting the risk of natural calamities, and so on.

  5. Galvanic enhancement for high pressure leaching of chalcopyrite

    Directory of Open Access Journals (Sweden)

    Kim D.H.

    2016-01-01

    Full Text Available This study was conducted to evaluate the galvanic enhancement of the pressure oxidation (POX leaching of a chalcopyrite/chalcocite concentrate, which is believed to take place via a redox reaction. Cu recoveries of >90% could be achieved during POX leaching of this chalcopyrite/chalcocite concentrate at 200°C and 0.7 MPa initial oxygen pressure within 2h in a pressure reactor lined with titanium, which were 18-28% higher than for the same leaching using the teflon liner. A slow heating time seems to produce more sulphur coating, reducing the leaching performance, yielding much lower Cu recovery when the teflon lining was used, although this does not greatly affect the other case when the reactor was lined with titanium. The introduction of an electronic conductor, in this case the titanium surface, is believed to enhance this redox process, in which the oxidation of copper minerals and sulphur to sulphate at the anodic sites (mineral surface encountered during POX leaching takes place simultaneously with the reversible oxidation/reduction of the Fe2+/Fe3+couple and oxygen reduction on titanium.

  6. The activation controlled galvanic corrosion of Carbon Steel/Zinc couple in deaerated stirred 0.2 N HCl

    International Nuclear Information System (INIS)

    Saeed, F. M. M.; Slaiman, Q. J. M.

    2005-01-01

    The effect of galvanic coupling of carbon steel to zinc (C.S. /Zn) in Deaerated 0.2 N HCl was studied using the multiple zero resistance technique to measure the galvanic current (Ig) and the coupling potential (Ecop,) versus time for the coupled metals. It was found that altering area ratio (AR) (Cathode/Anode) of the coupled metals and increasing temperature played an important role in the increasing corrosion rate as well as changing the galvanic factor (GF), galvanic current (Ig), and dissolution current (Id), in most of the cases. (author)

  7. A Galvanic Sensor for Monitoring the Corrosion Condition of the Concrete Reinforcing Steel: Relationship Between the Galvanic and the Corrosion Currents

    Directory of Open Access Journals (Sweden)

    Elsa Vaz Pereira

    2009-10-01

    Full Text Available This work reports a study carried out on the design and performance of galvanic and polarization resistance sensors to be embedded in concrete systems for permanent monitoring of the corrosion condition of reinforcing steel, aiming to establish a correlation between the galvanic currents, Igal, and the corrosion currents, Icorr, estimated from the polarization resistance, Rp. Sensors have been tested in saturated Ca(OH2 aqueous solutions, under a variety of conditions, simulating the most important parameters that can accelerate the corrosion of concrete reinforcing steel, such as carbonation, ingress of chloride ions, presence or absence of O2. For all the conditions, the influence of temperature (20 to 55 ºC has also been considered. From this study, it could be concluded that the galvanic currents are sensitive to the various parameters following a trend similar to that of the Rp values. A relationship between the galvanic and the corrosion current densities was obtained and the limiting values of the Igal, indicative of the state condition of the reinforcing steel for the designed sensor, were established.

  8. Influence of stripping and cooling atmospheres on surface properties and corrosion of zinc galvanizing coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yasakau, K.A., E-mail: kyasakau@ua.pt [Department of Materials and Ceramic Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Giner, I. [Universität Paderborn, Fakultät NW—Department Chemie, Technische und Makromolekulare Chemie, Warburger Strasse 100, D-33098 Paderborn (Germany); Vree, C. [Salzgitter Mannesmann Forschung, GmbH Division Surface Technology, Eisenhüttenstrasse 99, 38239 Salzgitter (Germany); Ozcan, O.; Grothe, R. [Universität Paderborn, Fakultät NW—Department Chemie, Technische und Makromolekulare Chemie, Warburger Strasse 100, D-33098 Paderborn (Germany); Oliveira, A. [Department of Materials and Ceramic Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Grundmeier, G. [Universität Paderborn, Fakultät NW—Department Chemie, Technische und Makromolekulare Chemie, Warburger Strasse 100, D-33098 Paderborn (Germany); Ferreira, M.G.S. [Department of Materials and Ceramic Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Zheludkevich, M.L. [Department of Materials and Ceramic Engineering, CICECO—Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal); Department of Corrosion and Surface Technology, Institute of Materials Research Helmholtz-Zentrum Geesthacht, Max-Planck Str. 1, 21502 Geesthacht (Germany)

    2016-12-15

    Highlights: • Stripping/cooling atmosphere affects surfaces chemical composition of Zn and Zn-Al-Mg galvanized coatings. • Higher peel forces of model adhesive films were obtained on zinc alloys samples prepared under nitrogen atmosphere. • Localized corrosion attack originates at grain boundaries on Zn galvanized coating. • Visible dissolution of MgZn{sub 2} phase was observed by in situ AFM only at binary eutectics and not at ternary ones. - Abstract: In this work the influence of stripping/cooling atmospheres used after withdrawal of steel sheet from Zn or Zn-alloy melt on surface properties of Zn (Z) and Zn-Al-Mg (ZM) hot-dip galvanizing coatings has been studied. The aim was to understand how the atmosphere (composed by nitrogen (N{sub 2}) or air) affects adhesion strength to model adhesive and corrosive behaviour of the galvanized substrates. It was shown that the surface chemical composition and Volta potential of the galvanizing coatings prepared under the air or nitrogen atmosphere are strongly influenced by the atmosphere. The surface chemistry Z and ZM surfaces prepared under N{sub 2} contained a higher content of metal atoms and a richer hydroxide density than the specimens prepared under air atmosphere as assessed by X-ray photoelectron spectroscopy (XPS). The induced differences on the microstructure of the galvanized coatings played a key role on the local corrosion induced defects as observed by means of in situ Atomic force microscopy (AFM). Peel force tests performed on the substrates coated by model adhesive films indicate a higher adhesive strength to the surfaces prepared under nitrogen atmosphere. The obtained results have been discussed in terms of the microstructure and surface chemical composition of the galvanizing coatings.

  9. Influence of stripping and cooling atmospheres on surface properties and corrosion of zinc galvanizing coatings

    International Nuclear Information System (INIS)

    Yasakau, K.A.; Giner, I.; Vree, C.; Ozcan, O.; Grothe, R.; Oliveira, A.; Grundmeier, G.; Ferreira, M.G.S.; Zheludkevich, M.L.

    2016-01-01

    Highlights: • Stripping/cooling atmosphere affects surfaces chemical composition of Zn and Zn-Al-Mg galvanized coatings. • Higher peel forces of model adhesive films were obtained on zinc alloys samples prepared under nitrogen atmosphere. • Localized corrosion attack originates at grain boundaries on Zn galvanized coating. • Visible dissolution of MgZn_2 phase was observed by in situ AFM only at binary eutectics and not at ternary ones. - Abstract: In this work the influence of stripping/cooling atmospheres used after withdrawal of steel sheet from Zn or Zn-alloy melt on surface properties of Zn (Z) and Zn-Al-Mg (ZM) hot-dip galvanizing coatings has been studied. The aim was to understand how the atmosphere (composed by nitrogen (N_2) or air) affects adhesion strength to model adhesive and corrosive behaviour of the galvanized substrates. It was shown that the surface chemical composition and Volta potential of the galvanizing coatings prepared under the air or nitrogen atmosphere are strongly influenced by the atmosphere. The surface chemistry Z and ZM surfaces prepared under N_2 contained a higher content of metal atoms and a richer hydroxide density than the specimens prepared under air atmosphere as assessed by X-ray photoelectron spectroscopy (XPS). The induced differences on the microstructure of the galvanized coatings played a key role on the local corrosion induced defects as observed by means of in situ Atomic force microscopy (AFM). Peel force tests performed on the substrates coated by model adhesive films indicate a higher adhesive strength to the surfaces prepared under nitrogen atmosphere. The obtained results have been discussed in terms of the microstructure and surface chemical composition of the galvanizing coatings.

  10. Galvanic corrosion evaluation of high activity nuclear waste container metals components

    International Nuclear Information System (INIS)

    Semino, C.J.

    1990-04-01

    The final disposal container for vitrified high-level waste is assumed to have three metallic layers: a stainless steel inner layer, and external one of a metal to be selected and a thick lead layer (10 cm) in the middle. As design limit, the container shall act as an engineering barrier, granting the isolation of the radionuclides for approximately 1000 years. Preliminary titanium-lead galvanic couple tests showed that titanium behaved always as a cathode in the galvanic couple, promoting the galvanic corrosion of lead. This corrosion study focused on the behaviour of lead-AISI 304 stainless steel and lead-carbon steel (SAE 1010 and 1020) galvanic couples with different area relationships, temperature and media composition. High purity lead (99,999%) and commercial lead (99,9%) were used for galvanic couples tests. Tests were performed at 75, 50, 45 and 40 deg. C. Test solution was either synthetic groundwater, a suspension of 10% bentonite in groundwater, or synthetic sea water. The synthetic sea water was used at 100, 50 and 25% concentration by dilution with distilled water. Tests with lead-304 stainless steel galvanic couples showed that lead always behaves as an anode, corroding preferentially. Very low lead corrosion rates were found in lead-carbon steel galvanic couple in 10% bentonite suspension in synthetic groundwater test at 75 deg. C. An increase of carbon content in steel has very little influence on steel corrosion rate. Commercial lead has a higher corrosion rate and presented a more pronounced attack than high purity lead. Its corrosion rate is at least twice when lead-carbon steel area relationship increases from 1:10 to 1:40. There are higher steel corrosion rates in sea water than in groundwater. Lead behaves as a cathode to the end of the test. 8 refs, 85 figs, 10 tabs

  11. Effect of hot-dip galvanizing processes on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel

    Science.gov (United States)

    Kuang, Chun-fu; Zheng, Zhi-wang; Wang, Min-li; Xu, Quan; Zhang, Shen-gen

    2017-12-01

    A C-Mn dual-phase steel was soaked at 800°C for 90 s and then either rapidly cooled to 450°C and held for 30 s (process A) or rapidly cooled to 350°C and then reheated to 450°C (process B) to simulate the hot-dip galvanizing process. The influence of the hot-dip galvanizing process on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel (DP600) was investigated using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. The results showed that, in the case of process A, the microstructure of DP600 was composed of ferrite, martensite, and a small amount of bainite. The granular bainite was formed in the hot-dip galvanizing stage, and martensite islands were formed in the final cooling stage after hot-dip galvanizing. By contrast, in the case of process B, the microstructure of the DP600 was composed of ferrite, martensite, bainite, and cementite. In addition, compared with the yield strength (YS) of the DP600 annealed by process A, that for the DP600 annealed by process B increased by approximately 50 MPa because of the tempering of the martensite formed during rapid cooling. The work-hardening coefficient ( n value) of the DP600 steel annealed by process B clearly decreased because the increase of the YS affected the computation result for the n value. However, the ultimate tensile strength (UTS) and elongation ( A 80) of the DP600 annealed by process B exhibited less variation compared with those of the DP600 annealed by process A. Therefore, DP600 with excellent comprehensive mechanical properties (YS = 362 MPa, UTS = 638 MPa, A 80 = 24.3%, n = 0.17) was obtained via process A.

  12. Postural Control in Bilateral Vestibular Failure: Its Relation to Visual, Proprioceptive, Vestibular, and Cognitive Input.

    Science.gov (United States)

    Sprenger, Andreas; Wojak, Jann F; Jandl, Nico M; Helmchen, Christoph

    2017-01-01

    Patients with bilateral vestibular failure (BVF) suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC), visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance. Between-group analysis revealed larger postural sway in BVF patients on eye closure; but with the eyes open, BVF did not differ from healthy controls (HCs). Head tilts and horizontal head shaking increased sway but did not differ between groups. In the dual task condition, BVF patients maintained posture indistinguishable from controls. On foam and tandem stance, postural sway was larger in BVF, even with the eyes open. The best predictor for the severity of bilateral vestibulopathy was standing on foam with eyes closed. Postural control of our BVF was indistinguishable from HCs once visual and proprioceptive feedback is provided. This distinguishes them from patients with vestibulo-cerebellar disorders or functional dizziness. It confirms previous reports and explains that postural unsteadiness of BVF patients can be missed easily if not examined by conditions of visual and/or proprioceptive deprivation. In fact, the best predictor for vestibular hypofunction (VOR gain) was examining patients standing on foam with the eyes closed. Postural sway in that condition increased with the severity of vestibular impairment but not with disease duration. In the absence of visual control, impaired otolith input destabilizes BVF with head retroflexion. Stimulating deficient SSC does not distinguish patients from controls possibly reflecting a shift of intersensory weighing toward proprioceptive-guided postural control. Accordingly, proprioceptive

  13. Postural Control in Bilateral Vestibular Failure: Its Relation to Visual, Proprioceptive, Vestibular, and Cognitive Input

    Directory of Open Access Journals (Sweden)

    Andreas Sprenger

    2017-09-01

    Full Text Available Patients with bilateral vestibular failure (BVF suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC, visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance. Between-group analysis revealed larger postural sway in BVF patients on eye closure; but with the eyes open, BVF did not differ from healthy controls (HCs. Head tilts and horizontal head shaking increased sway but did not differ between groups. In the dual task condition, BVF patients maintained posture indistinguishable from controls. On foam and tandem stance, postural sway was larger in BVF, even with the eyes open. The best predictor for the severity of bilateral vestibulopathy was standing on foam with eyes closed. Postural control of our BVF was indistinguishable from HCs once visual and proprioceptive feedback is provided. This distinguishes them from patients with vestibulo-cerebellar disorders or functional dizziness. It confirms previous reports and explains that postural unsteadiness of BVF patients can be missed easily if not examined by conditions of visual and/or proprioceptive deprivation. In fact, the best predictor for vestibular hypofunction (VOR gain was examining patients standing on foam with the eyes closed. Postural sway in that condition increased with the severity of vestibular impairment but not with disease duration. In the absence of visual control, impaired otolith input destabilizes BVF with head retroflexion. Stimulating deficient SSC does not distinguish patients from controls possibly reflecting a shift of intersensory weighing toward proprioceptive-guided postural control. Accordingly

  14. Postural Control in Bilateral Vestibular Failure: Its Relation to Visual, Proprioceptive, Vestibular, and Cognitive Input

    Science.gov (United States)

    Sprenger, Andreas; Wojak, Jann F.; Jandl, Nico M.; Helmchen, Christoph

    2017-01-01

    Patients with bilateral vestibular failure (BVF) suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC), visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance. Between-group analysis revealed larger postural sway in BVF patients on eye closure; but with the eyes open, BVF did not differ from healthy controls (HCs). Head tilts and horizontal head shaking increased sway but did not differ between groups. In the dual task condition, BVF patients maintained posture indistinguishable from controls. On foam and tandem stance, postural sway was larger in BVF, even with the eyes open. The best predictor for the severity of bilateral vestibulopathy was standing on foam with eyes closed. Postural control of our BVF was indistinguishable from HCs once visual and proprioceptive feedback is provided. This distinguishes them from patients with vestibulo-cerebellar disorders or functional dizziness. It confirms previous reports and explains that postural unsteadiness of BVF patients can be missed easily if not examined by conditions of visual and/or proprioceptive deprivation. In fact, the best predictor for vestibular hypofunction (VOR gain) was examining patients standing on foam with the eyes closed. Postural sway in that condition increased with the severity of vestibular impairment but not with disease duration. In the absence of visual control, impaired otolith input destabilizes BVF with head retroflexion. Stimulating deficient SSC does not distinguish patients from controls possibly reflecting a shift of intersensory weighing toward proprioceptive-guided postural control. Accordingly, proprioceptive

  15. An Adaptive Filter for the Removal of Drifting Sinusoidal Noise Without a Reference.

    Science.gov (United States)

    Kelly, John W; Siewiorek, Daniel P; Smailagic, Asim; Wang, Wei

    2016-01-01

    This paper presents a method for filtering sinusoidal noise with a variable bandwidth filter that is capable of tracking a sinusoid's drifting frequency. The method, which is based on the adaptive noise canceling (ANC) technique, will be referred to here as the adaptive sinusoid canceler (ASC). The ASC eliminates sinusoidal contamination by tracking its frequency and achieving a narrower bandwidth than typical notch filters. The detected frequency is used to digitally generate an internal reference instead of relying on an external one as ANC filters typically do. The filter's bandwidth adjusts to achieve faster and more accurate convergence. In this paper, the focus of the discussion and the data is physiological signals, specifically electrocorticographic (ECoG) neural data contaminated with power line noise, but the presented technique could be applicable to other recordings as well. On simulated data, the ASC was able to reliably track the noise's frequency, properly adjust its bandwidth, and outperform comparative methods including standard notch filters and an adaptive line enhancer. These results were reinforced by visual results obtained from real ECoG data. The ASC showed that it could be an effective method for increasing signal to noise ratio in the presence of drifting sinusoidal noise, which is of significant interest for biomedical applications.

  16. Electronically Tunable Quadrature Sinusoidal Oscillator with Equal Output Amplitudes during Frequency Tuning Process

    Directory of Open Access Journals (Sweden)

    Den Satipar

    2017-01-01

    Full Text Available A new configuration of voltage-mode quadrature sinusoidal oscillator is proposed. The proposed oscillator employs two voltage differencing current conveyors (VDCCs, two resistors, and two grounded capacitors. In this design, the use of multiple/dual output terminal active building block is not required. The tuning of frequency of oscillation (FO can be done electronically by adjusting the bias current of active device without affecting condition of oscillation (CO. The electronic tuning can be done by controlling the bias current using a digital circuit. The amplitude of two sinusoidal outputs is equal when the frequency of oscillation is tuned. This makes the sinusoidal output voltages meet good total harmonic distortions (THD. Moreover, the proposed circuit can provide the sinusoidal output current with high impedance which is connected to external load or to another circuit without the use of buffer device. To confirm that the oscillator can generate the quadrature sinusoidal output signal, the experimental results using VDCC constructed from commercially available ICs are also included. The experimental results agree well with theoretical anticipation.

  17. Effect of confinement on bond strength of hot-dip galvanized lap splices in concrete structures

    International Nuclear Information System (INIS)

    Fakhran, Mazen

    2004-01-01

    Galvanizing the reinforcing steel is one of the methods used to protect bars against corrosion. Galvanizing is a hot dip process where the reinforcing bars are immersed in an aqueous pre flux solution of zinc ammonium chloride at a controlled temperature between 840 and 850 degrees F. In 2001, a research program was started at AUB to evaluate experimentally the effect of hot dip galvanizing on the bond capacity of tension lap splices anchored in full-scale beam specimens designed to fail in bond splitting mode. The test results indicated that the use of galvanized bars had a negligible effect on bond strength of reinforcement in normal strength. However, galvanizing caused an average of 20 percent decrease in bond strength of reinforcement in high strength concrete. The primary objective of research reported in this thesis, is the need to find a solution to eliminate the bond reduction of galvanized bars in high strength concrete. It is significant to evaluate the positive effect of the addition of transverse reinforcement in the splice region. The hypothesis to be tested is that such transverse reinforcement will insure uniform bond stress distribution over the entire splice region, thus mobilizing all bar lugs along the splice in the stress transfer mechanism between the bar and the surrounding concrete. Such mechanism might reduce the significant decrease in bond strength in high strength concrete due to galvanizing. To achieve this objective, eighteen full-scale beam specimens were tested in positive bending. Each beam was reinforced with bars spliced in a constant moment region at midspam. The splice length was chosen in such a way that the beams failed in bond splitting of the concrete cover in the splice region. The main variables were type of coating (black or galvanized bars), bar size (20, 25 and 32 mm), and amount of transverse reinforcement in the splice region (0, 2 or 4 stirrups). The test results indicated that confinement did not have a significant

  18. Combined ocular and cervical vestibular evoked myogenic potential in individuals with vestibular hyporeflexia and in patients with Ménière's disease.

    Science.gov (United States)

    Silva, Tatiana Rocha; de Resende, Luciana Macedo; Santos, Marco Aurélio Rocha

    The vestibular evoked myogenic potential is a potential of mean latency that measures the muscle response to auditory stimulation. This potential can be generated from the contraction of the sternocleidomastoid muscle and also from the contraction of extraocular muscles in response to high-intensity sounds. This study presents a combined or simultaneous technique of cervical and ocular vestibular evoked myogenic potential in individuals with changes in the vestibular system, for use in otoneurologic diagnosis. To characterize the records and analyze the results of combined cervical and ocular VEMP in individuals with vestibular hyporeflexia and in those with Ménière's disease. The study included 120 subjects: 30 subjects with vestibular hyporeflexia, 30 with Ménière's disease, and 60 individuals with normal hearing. Data collection was performed by simultaneously recording the cervical and ocular vestibular evoked myogenic potential. There were differences between the study groups (individuals with vestibular hyporeflexia and individuals with Ménière's disease) and the control group for most of wave parameters in combined cervical and ocular vestibular evoked myogenic potential. For cervical vestibular evoked myogenic potential, it was observed that the prolongation of latency of the P13 and N23 waves was the most frequent finding in the group with vestibular hyporeflexia and in the group with Ménière's disease. For ocular vestibular evoked myogenic potential, prolonged latency of N10 and P15 waves was the most frequent finding in the study groups. Combined cervical and ocular vestibular evoked myogenic potential presented relevant results for individuals with vestibular hyporeflexia and for those with Ménière's disease. There were differences between the study groups and the control group for most of the wave parameters in combined cervical and ocular vestibular evoked myogenic potential. Copyright © 2016 Associação Brasileira de Otorrinolaringologia

  19. Galvanic interactions of HE15 /MDN138 & HE15 /MDN250 alloys in natural seawater

    Science.gov (United States)

    Parthiban, G. T.; Subramanian, G.; Muthuraman, K.; Ramakrishna Rao, P.

    2017-06-01

    HE15 is a heat treatable high strength alloy with excellent machinability find wide applications in aerospace and defence industries. In view of their excellent mechanical properties, workability, machinability, heat treatment characteristics and good resistance to general and stress corrosion cracking, MDN138 & MDN250 have been widely used in petrochemical, nuclear and aerospace industries. The galvanic corrosion behaviour of the metal combinations HE15 /MDN138 and HE15 /MDN250, with 1:1 area ratio, has been studied in natural seawater using the open well facility of CECRI's Offshore Platform at Tuticorin for a year. The open circuit potentials of MDN138, MDN250 and HE15 of the individual metal, the galvanic potential and galvanic current of the couples HE15 /MDN138 and HE15 /MDN250 were periodically monitored throughout the study period. The calcareous deposits on MDN138 and MDN250 in galvanic contact with HE15 were analyzed using XRD. The electrochemical behaviors of MDN138, MDN250 and HE15 in seawater have been studied using an electrochemical work station. The surface characteristics of MDN138 and MDN250 in galvanic contact with HE15 have been examined with scanning electron microscope. The results of the study reveal that HE15 offered required amount of protection to MDN138 & MDN250.

  20. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

    Science.gov (United States)

    Xu, Yunze; Li, Kaiqiang; Liu, Liang; Yang, Lujia; Wang, Xiaona; Huang, Yi

    2016-01-01

    In this paper, a new kind of carbon steel (CS) and stainless steel (SS) galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER) method and zero resistance ammeter (ZRA) technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR) and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH)2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete. PMID:27618054

  1. Experimental Study on Rebar Corrosion Using the Galvanic Sensor Combined with the Electronic Resistance Technique

    Directory of Open Access Journals (Sweden)

    Yunze Xu

    2016-09-01

    Full Text Available In this paper, a new kind of carbon steel (CS and stainless steel (SS galvanic sensor system was developed for the study of rebar corrosion in different pore solution conditions. Through the special design of the CS and SS electronic coupons, the electronic resistance (ER method and zero resistance ammeter (ZRA technique were used simultaneously for the measurement of both the galvanic current and the corrosion depth. The corrosion processes in different solution conditions were also studied by linear polarization resistance (LPR and the measurements of polarization curves. The test result shows that the galvanic current noise can provide detailed information of the corrosion processes. When localized corrosion occurs, the corrosion rate measured by the ER method is lower than the real corrosion rate. However, the value measured by the LPR method is higher than the real corrosion rate. The galvanic current and the corrosion current measured by the LPR method shows linear correlation in chloride-containing saturated Ca(OH2 solution. The relationship between the corrosion current differences measured by the CS electronic coupons and the galvanic current between the CS and SS electronic coupons can also be used to evaluate the localized corrosion in reinforced concrete.

  2. A study on the flow-accelerated corrosion characteristics of galvanically coupled dissimilar metals

    International Nuclear Information System (INIS)

    Choi, Yoon Seok; Kim, Jung Gu

    2002-01-01

    The flow-accelerated corrosion characteristics of a carbon steel(CS) coupled to stainless steel(SS) were investigated in deaerated alkaline-chloride solutions with velocities (0, 0.2, 0.4 and 0.6 m/s), pH (8, 9 and 10) and temperatures (25, 50 and 75 .deg. C). The electrochemical properties of specimens were investigated by potentiodynamic test and galvanic corrosion test using RCE (Rotating Cylinder Electrode). CS did not show passive behavior while SS show passive behavior in the alkaline-chloride solution. Galvanic corrosion tests were conducted as a function of flow velocities, pH and temperature. The galvanic current density increases with increasing flow velocity and temperature, but decreased with increasing pH. Flow velocity had a small effect on the galvanic current density at 25 .deg. C, whereas the flow velocity increased galvanic current density significantly at 50 and 75 .deg. C. This might be due to the increased solubility of magnetite at the higher temperature

  3. A Noble Approach of Process Automation in Galvanized Nut, Bolt Manufacturing Industry

    Directory of Open Access Journals (Sweden)

    Akash Samanta

    2012-05-01

    Full Text Available Corrosion costs money”, The Columbus battle institute estimates that corrosion costs Americans more than $ 220 billion annually, about 4.3% of the gross natural product [1].Now a days due to increase of pollution, the rate of corrosion is also increasing day-by-day mainly in India, so, to save the steel structures, galvanizing is the best and the simplest solution. Due to this reason galvanizing industries are increasing day-by-day since mid of 1700s.Galvanizing is a controlled metallurgical combination of zinc and steel that can provide a corrosion resistance in a wide variety of environment. In fact, the galvanized metal corrosion resistance factor can be some 70 to 80 times greater that the base metal material. Keeping in mind the importance of this industry, a noble approach of process automation in galvanized nut-bolt  manufacturing plant is presented here as nuts and bolts are the prime ingredient of any structure. In this paper the main objectives of any industry like survival, profit maximization, profit satisfying and sales growth are fulfilled. Furthermore the environmental aspects i.e. pollution control and energy saving are also considered in this paper. The whole automation process is done using programmable logic controller (PLC which has number of unique advantages like being faster, reliable, requires less maintenance and reprogrammable. The whole system has been designed and tested using GE, FANUC PLC.

  4. Effects of supporting electrolyte on galvanic deposition of Cu2O crystals

    International Nuclear Information System (INIS)

    Wang Lida; Liu Guichang; Xue Dongfeng

    2011-01-01

    Highlights: → The effects of electrolyte on the galvanic deposition of Cu 2 O crystals have been investigated. → The chemical nature of supporting electrolyte plays important roles in the galvanic deposition of Cu 2 O crystals. → Cubic Cu 2 O crystals are formed in chloride electrolytes. → Truncated octahedral Cu 2 O crystals are produced in nitrate, sulfate and fluoride electrolytes. - Abstract: The effects of introduced supporting electrolyte on the galvanic deposition of Cu 2 O crystals have been investigated using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD). The results show that the chemical nature of supporting electrolytes plays very important roles in the galvanic deposition of Cu 2 O crystals. The chloride stabilizes the (1 0 0) planes of Cu 2 O crystals, resulting in the formation of cubic crystals, while nitrate, sulfate and fluoride stabilize the (1 1 1) planes of Cu 2 O crystals, leading to the deposition of truncated octahedral and octahedral Cu 2 O crystals. It provides a facile way to control the morphology of galvanically obtained Cu 2 O crystals by indirectly adjusting the inorganic adsorption agents.

  5. Influence of stripping and cooling atmospheres on surface properties and corrosion of zinc galvanizing coatings

    Science.gov (United States)

    Yasakau, K. A.; Giner, I.; Vree, C.; Ozcan, O.; Grothe, R.; Oliveira, A.; Grundmeier, G.; Ferreira, M. G. S.; Zheludkevich, M. L.

    2016-12-01

    In this work the influence of stripping/cooling atmospheres used after withdrawal of steel sheet from Zn or Zn-alloy melt on surface properties of Zn (Z) and Zn-Al-Mg (ZM) hot-dip galvanizing coatings has been studied. The aim was to understand how the atmosphere (composed by nitrogen (N2) or air) affects adhesion strength to model adhesive and corrosive behaviour of the galvanized substrates. It was shown that the surface chemical composition and Volta potential of the galvanizing coatings prepared under the air or nitrogen atmosphere are strongly influenced by the atmosphere. The surface chemistry Z and ZM surfaces prepared under N2 contained a higher content of metal atoms and a richer hydroxide density than the specimens prepared under air atmosphere as assessed by X-ray photoelectron spectroscopy (XPS). The induced differences on the microstructure of the galvanized coatings played a key role on the local corrosion induced defects as observed by means of in situ Atomic force microscopy (AFM). Peel force tests performed on the substrates coated by model adhesive films indicate a higher adhesive strength to the surfaces prepared under nitrogen atmosphere. The obtained results have been discussed in terms of the microstructure and surface chemical composition of the galvanizing coatings.

  6. Enhancement of Otolith Specific Ocular Responses Using Vestibular Stochastic Resonance

    Science.gov (United States)

    Fiedler, Matthew; De Dios, Yiri E.; Esteves, Julie; Galvan, Raquel; Wood, Scott; Bloomberg, Jacob; Mulavara, Ajitkumar

    2011-01-01

    Introduction: Astronauts experience disturbances in sensorimotor function after spaceflight during the initial introduction to a gravitational environment, especially after long-duration missions. Our goal is to develop a countermeasure based on vestibular stochastic resonance (SR) that could improve central interpretation of vestibular input and mitigate these risks. SR is a mechanism by which noise can assist and enhance the response of neural systems to relevant, imperceptible sensory signals. We have previously shown that imperceptible electrical stimulation of the vestibular system enhances balance performance while standing on an unstable surface. Methods: Eye movement data were collected from 10 subjects during variable radius centrifugation (VRC). Subjects performed 11 trials of VRC that provided equivalent tilt stimuli from otolith and other graviceptor input without the normal concordant canal cues. Bipolar stochastic electrical stimulation, in the range of 0-1500 microamperes, was applied to the vestibular system using a constant current stimulator through electrodes placed over the mastoid process behind the ears. In the VRC paradigm, subjects were accelerated to 216 deg./s. After the subjects no longer sensed rotation, the chair oscillated along a track at 0.1 Hz to provide tilt stimuli of 10 deg. Eye movements were recorded for 6 cycles while subjects fixated on a target in darkness. Ocular counter roll (OCR) movement was calculated from the eye movement data during periods of chair oscillations. Results: Preliminary analysis of the data revealed that 9 of 10 subjects showed an average increase of 28% in the magnitude of OCR responses to the equivalent tilt stimuli while experiencing vestibular SR. The signal amplitude at which performance was maximized was in the range of 100-900 microamperes. Discussion: These results indicate that stochastic electrical stimulation of the vestibular system can improve otolith specific responses. This will have a

  7. MR imaging features and clinical value of vestibular aqueduct and endolymphatic sac in patients with large vestibular aqueduct syndrome

    International Nuclear Information System (INIS)

    Fang Zheming; Lou Xin; Lan Lan; Wang Hui; Wang Qiuju; Wu Nanzhou; Zhang Xiaojing

    2012-01-01

    Objective: To investigate MR imaging features of endolymphatic sac and vestibular aqueduct in patients with large vestibular aqueduct syndrome (LVAS) and its correlation with hearing loss. Methods: MR imaging findings of LVAS were analyzed in 31 cases (62 ears) retrospectively. MR imaging features were grouped into 4 types. In the first type, the signals of endolymphatic and vestibular aqueduct were hypointense without any hyperintense area. In the second type, the signals of endolymphatic sac and vestibular were hyperintense which were confined within vestibular fissure. In the third type, the area from vestibular aqueduct backward out of the edge of the petrous bone was hyperintense, but its lower boundary was above posterior semicircular. In the fourth type the area which was hyperintense was below the posterior semicircular. To avoid errors in visual inspection, the hyperintense and hypointense area of endolymphatic and the signal intensity of vestibular aqueduct and cerebrospinal fluid (CSF) were measured. The differences of signal intensity among the vestibular endolymphatic sac between the high-signal areas and low signal areas were compared with paired t-test. The correlation of the endolymphatic sac MRI classification and degree of hearing loss was analyzed by corrected Chi-square test and Spearman correlation analysis. Result: Ten ears belonged to type Ⅰ (moderate hearing loss in 1 ear,severe in 4 ears,profound in 5 ears), 17 ears belonged to type Ⅱ (moderate hearing loss in 1 ear; severe in 5 ears,profound in 11 ears), 23 ears to type Ⅲ (moderate hearing loss in 3 ear, severe in 5 ears, profound in 15 ears) and 12 ears belonged to Ⅳ (mild hearing loss in 1 ear, moderate in 1 ear, severe 3 ear, profound in 7 ears). The boundary between hyperintense and hypointense area was clear, and the signal intensity ratios was 2.02 ± 0.06. The signal ratios of hyperintense and hypointense area to vestibular and CSF were 0.95 ±0.12, 0.49 ±0.10, 0.99 ± 0

  8. Efficacy of Stochastic Vestibular Stimulation to Improve Locomotor Performance During Adaptation to Visuomotor and Somatosensory Distortion.

    Science.gov (United States)

    Temple, David R; De Dios, Yiri E; Layne, Charles S; Bloomberg, Jacob J; Mulavara, Ajitkumar P

    2018-01-01

    Astronauts exposed to microgravity face sensorimotor challenges affecting balance control when readapting to Earth's gravity upon return from spaceflight. Small amounts of electrical noise applied to the vestibular system have been shown to improve balance control during standing and walking under discordant sensory conditions in healthy subjects, likely by enhancing information transfer through the phenomenon of stochastic resonance. The purpose of this study was to test the hypothesis that imperceptible levels of stochastic vestibular stimulation (SVS) could improve short-term adaptation to a locomotor task in a novel sensory discordant environment. Healthy subjects (14 males, 10 females, age = 28.7 ± 5.3 years, height = 167.2 ± 9.6 cm, weight = 71.0 ± 12.8 kg) were tested for perceptual thresholds to sinusoidal currents applied across the mastoids. Subjects were then randomly and blindly assigned to an SVS group receiving a 0-30 Hz Gaussian white noise electrical stimulus at 50% of their perceptual threshold (stim) or a control group receiving zero stimulation during Functional Mobility Tests (FMTs), nine trials of which were done under conditions of visual discordance (wearing up/down vision reversing goggles). Time to complete the course (TCC) was used to test the effect of SVS between the two groups across the trials. Adaptation rates from the normalized TCCs were also compared utilizing exponent values of power fit trendline equations. A one-tailed independent-samples t -test indicated these adaptation rates were significantly faster in the stim group ( n = 12) than the control ( n = 12) group [ t (16.18) = 2.00, p = 0.031]. When a secondary analysis was performed comparing "responders" (subjects who showed faster adaptation rates) of the stim ( n = 7) group to the control group ( n = 12), independent-samples t -tests revealed significantly faster trial times for the last five trials with goggles in the stim group "responders" than the controls. The data

  9. New Canonic Active RC Sinusoidal Oscillator Circuits Using Second-Generation Current Conveyors with Application as a Wide-Frequency Digitally Controlled Sinusoid Generator

    OpenAIRE

    Abhirup Lahiri

    2011-01-01

    This paper reports two new circuit topologies using second-generation current conveyors (CCIIs) for realizing variable frequency sinusoidal oscillators with minimum passive components. The proposed topologies in this paper provide new realizations of resistance-controlled and capacitor-controlled variable frequency oscillators (VFOs) using only four passive components. The first topology employs three CCIIs, while the second topology employs two CCIIs. The second topology provides an advantag...

  10. Light scattering by sinusoidal surfaces: illumination windows and harmonics in standards.

    Science.gov (United States)

    Marx, E; Lettieri, T R; Vorburger, T V

    1995-03-01

    Sinusoidal surfaces can be used as material standards to help calibrate instruments that measure the angular distribution of the intensity of light scattered by arbitrary surfaces, because the power in the diffraction peaks varies over several orders of magnitude. The calculated power in the higher-order diffraction peaks from sinusoidal surfaces expressed in terms of Bessel functions is much smaller than the values determined from angular distributions that are measured or computed from measured profiles, both of which are determined mainly by the harmonic contents of the profile. The finite size of the illuminated area, represented by an illumination window, gives rise to a background that is much larger than the calculated power in the higher-order peaks. For a rectangular window of a size equal to an even number of periods of the sinusoid, a computation of the power distribution produces minima at or near the location of the diffraction angles for higher-order diffraction angles.

  11. New Canonic Active RC Sinusoidal Oscillator Circuits Using Second-Generation Current Conveyors with Application as a Wide-Frequency Digitally Controlled Sinusoid Generator

    Directory of Open Access Journals (Sweden)

    Abhirup Lahiri

    2011-01-01

    Full Text Available This paper reports two new circuit topologies using second-generation current conveyors (CCIIs for realizing variable frequency sinusoidal oscillators with minimum passive components. The proposed topologies in this paper provide new realizations of resistance-controlled and capacitor-controlled variable frequency oscillators (VFOs using only four passive components. The first topology employs three CCIIs, while the second topology employs two CCIIs. The second topology provides an advantageous feature of frequency tuning through two grounded elements. Application of the proposed circuits as a wide-frequency range digitally controlled sinusoid generator is exhibited wherein the digital frequency control has been enabled by replacing both the capacitors by two identical variable binary capacitor banks tunable by means of the same binary code. SPICE simulations of the CMOS implementation of the oscillators using 0.35 μm TSMC CMOS technology parameters and bipolar implementation of the oscillators using process parameters for NR200N-2X (NPN and PR200N-2X (PNP of bipolar arrays ALA400-CBIC-R have validated their workability. One of the oscillators (with CMOS implementation is exemplified as a digitally controlled sinusoid generator with frequency generation from 25 kHz to 6.36 MHz, achieved by switching capacitors and with power consumption of 7 mW in the entire operating frequency range.

  12. Unilateral vestibular deafferentation-induced changes in calcium signaling-related molecules in the rat vestibular nuclear complex.

    Science.gov (United States)

    Masumura, Chisako; Horii, Arata; Mitani, Kenji; Kitahara, Tadashi; Uno, Atsuhiko; Kubo, Takeshi

    2007-03-23

    Inquiries into the neurochemical mechanisms of vestibular compensation, a model of lesion-induced neuronal plasticity, reveal the involvement of both voltage-gated Ca(2+) channels (VGCC) and intracellular Ca(2+) signaling. Indeed, our previous microarray analysis showed an up-regulation of some calcium signaling-related genes such as the alpha2 subunit of L-type calcium channels, calcineurin, and plasma membrane Ca(2+) ATPase 1 (PMCA1) in the ipsilateral vestibular nuclear complex (VNC) following unilateral vestibular deafferentation (UVD). To further elucidate the role of calcium signaling-related molecules in vestibular compensation, we used a quantitative real-time polymerase chain reaction (PCR) method to confirm the microarray results and investigated changes in expression of these molecules at various stages of compensation (6 h to 2 weeks after UVD). We also investigated the changes in gene expression during Bechterew's phenomenon and the effects of a calcineurin inhibitor on vestibular compensation. Real-time PCR showed that genes for the alpha2 subunit of VGCC, PMCA2, and calcineurin were transiently up-regulated 6 h after UVD in ipsilateral VNC. A subsequent UVD, which induced Bechterew's phenomenon, reproduced a complete mirror image of the changes in gene expressions of PMCA2 and calcineurin seen in the initial UVD, while the alpha2 subunit of VGCC gene had a trend to increase in VNC ipsilateral to the second lesion. Pre-treatment by FK506, a calcineurin inhibitor, decelerated the vestibular compensation in a dose-dependent manner. Although it is still uncertain whether these changes in gene expression are causally related to the molecular mechanisms of vestibular compensation, this observation suggests that after increasing the Ca(2+) influx into the ipsilateral VNC neurons via up-regulated VGCC, calcineurin may be involved in their synaptic plasticity. Conversely, an up-regulation of PMCA2, a brain-specific Ca(2+) pump, would increase an efflux of Ca

  13. The Effect of Vestibular Rehabilitation Therapy Program on Sensory Organization of Deaf Children With Bilateral Vestibular Dysfunction

    Directory of Open Access Journals (Sweden)

    Amir Abbas Ebrahimi

    2018-01-01

    Full Text Available The purpose of this study was to determine the effect of vestibular rehabilitation therapy program on the sensory organization of deaf children with bilateral vestibular dysfunction. This cross-sectional and analytic study was conducted on 24 students between the age of 7 and 12 years (6 girls and 18 boys with the profound sensorineural hearing loss (PTA>90 dB. They were assessed through the balance subtest in Bruininks-Oseretsky test of motor proficiency (BOTMP. For children which the total score of the balance subtest was 3 standard deviation lower than their peers with typical development, vestibular function testing was completed pre-intervention. Posturography Sensory organization testing (SOT was completed pre- and post-intervention with SPS (Synapsys, Marseille, France. Children with bilateral vestibular impairment were randomly assigned to either the exercise or control group. Exercise intervention consisted of compensatory training, emphasizing enhancement of visual and somatosensory function, and balance training. The exercise group entered in vestibular rehabilitation therapy program for 8 weeks. The children initially participating in the control group were provided the exercise intervention following the post-test. Based on the results there was significant difference in condition 5 and 6, areas of limits of stability (LOS, vestibular ratio and global score in posturography at the end of the intervention, but there was no significant difference in the control group in posturography (P<0.05. The results indicated that testing of vestibular, and postural control function, as well as intervention for deficiencies identified, should be included in deaf children rehabilitation program.

  14. Deconvolution of the vestibular evoked myogenic potential.

    Science.gov (United States)

    Lütkenhöner, Bernd; Basel, Türker

    2012-02-07

    The vestibular evoked myogenic potential (VEMP) and the associated variance modulation can be understood by a convolution model. Two functions of time are incorporated into the model: the motor unit action potential (MUAP) of an average motor unit, and the temporal modulation of the MUAP rate of all contributing motor units, briefly called rate modulation. The latter is the function of interest, whereas the MUAP acts as a filter that distorts the information contained in the measured data. Here, it is shown how to recover the rate modulation by undoing the filtering using a deconvolution approach. The key aspects of our deconvolution algorithm are as follows: (1) the rate modulation is described in terms of just a few parameters; (2) the MUAP is calculated by Wiener deconvolution of the VEMP with the rate modulation; (3) the model parameters are optimized using a figure-of-merit function where the most important term quantifies the difference between measured and model-predicted variance modulation. The effectiveness of the algorithm is demonstrated with simulated data. An analysis of real data confirms the view that there are basically two components, which roughly correspond to the waves p13-n23 and n34-p44 of the VEMP. The rate modulation corresponding to the first, inhibitory component is much stronger than that corresponding to the second, excitatory component. But the latter is more extended so that the two modulations have almost the same equivalent rectangular duration. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Stereotactic radiation therapy for large vestibular schwannomas

    International Nuclear Information System (INIS)

    Mandl, Ellen S.; Meijer, Otto W.M.; Slotman, Ben J.; Vandertop, W. Peter; Peerdeman, Saskia M.

    2010-01-01

    Background and purpose: To evaluate the morbidity and tumor-control rate in the treatment of large vestibular schwannomas (VS) after stereotactic radiation therapy in our institution. Material and methods: Twenty-five consecutive patients (17 men, 8 women) with large VS (diameter 3.0 cm or larger), treated with stereotactic radiotherapy (SRT) or stereotactic radiosurgery (SRS) between 1992 and 2007, were retrospectively studied after a mean follow-up period of three years with respect to tumor-control rate and complications. Results: Actuarial 5-year maintenance of pre-treatment hearing level probability of 30% was achieved. Five of 17 patients suffered permanent new facial nerve dysfunction. The actuarial 5-year facial nerve preservation probability was 80%. Permanent new trigeminal nerve neuropathy occurred in two of 15 patients, resulting in an actuarial 5-year trigeminal nerve preservation probability of 85%. Tumor progression occurred in four of 25 (16%) patients. The overall 5-year tumor control probability was 82%. Conclusion: Increased morbidity rates were found in patients with large VS treated with SRT or SRS compared to the published series on regular sized VS and other smaller retrospective studies on large VS.

  16. Corrosion behaviour and galvanic coupling of titanium and welded titanium in LiBr solutions

    International Nuclear Information System (INIS)

    Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D.

    2007-01-01

    Corrosion resistance and galvanic coupling of Grade 2 commercially pure titanium in its welded and non-welded condition were systematically analyzed in LiBr solutions. Galvanic corrosion was evaluated through two different methods: anodic polarization (according to the Mixed Potential Theory) and electrochemical noise (using a zero-resistance ammeter). Samples have been etched to study the microstructure. The action of lithium chromate as corrosion inhibitor has been evaluated. Titanium and welded titanium showed extremely low corrosion current densities and elevated pitting potential values (higher than 1 V). The results of both methods, anodic polarization and electrochemical noise, showed that the welded titanium was always the anodic element of the pair titanium-welded titanium, so that its corrosion resistance decreases due to the galvanic effect

  17. Galvanic Interaction between Chalcopyrite and Pyrite with Low Alloy and High Carbon Chromium Steel Ball

    Directory of Open Access Journals (Sweden)

    Asghar Azizi

    2013-01-01

    Full Text Available This study was aimed to investigate the galvanic interaction between pyrite and chalcopyrite with two types of grinding media (low alloy and high carbon chromium steel ball in grinding of a porphyry copper sulphide ore. Results indicated that injection of different gases into mill altered the oxidation-reduction environment during grinding. High carbon chromium steel ball under nitrogen gas has the lowest galvanic current, and low alloy steel ball under oxygen gas had the highest galvanic current. Also, results showed that the media is anodic relative to pyrite and chalcopyrite, and therefore pyrite or chalcopyrite with a higher rest potential acted as the cathode, whilst the grinding media with a lower rest potential acted as the anode, when they are electrochemically contacted. It was also found that low alloy steel under oxygen produced the highest amount of EDTA extractable iron in the slurry, whilst high carbon chromium steel under nitrogen atmosphere led to the lowest amount.

  18. Galvanic coupling effects for module-mounting elements of ground-mounted photovoltaic power station

    Directory of Open Access Journals (Sweden)

    Pierozynski Boguslaw

    2017-12-01

    Full Text Available This communication reports on the concerns associated with possible generation of galvanic coupling effects for construction materials that are used to manufacture mounting assemblies for ground-mounted photovoltaic (PV power stations. For this purpose, six macro-corrosion galvanic cells were assembled, including: hot-dip Zn/Magnelis®-coated steel/Al and stainless steel (SS/Al cells. Corrosion experiments involved continuous, ca. three-month exposure of these couplings in 3 wt.% NaCl solution, conducted at room temperature for a stable pH value of around 8. All corrosion cells were subjected to regular assessment of galvanic current-density and potential parameters, where special consideration was given to compare the corrosion behaviour of Zn-coated steel samples with that of Magnelis®-coated electrodes. Characterization of surface condition and elemental composition for examined materials was carried-out by means of SEM and EDX spectroscopy techniques.

  19. Photo-galvanic effect in Bi2Se3 thin films with ionic liquid gating

    Science.gov (United States)

    Pan, Yu; Richardella, Anthony; Lee, Joon Sue; Flanagan, Thomas; Samarth, Nitin

    2013-03-01

    A key challenge in three dimensional (3D) topological insulators (TIs) is to reveal the helical spin-polarized surface states via electrical transport measurements. A recent study [Nature Nanotech. 7, 96 (2012)] showed that circularly polarized light can be used to generate and control photocurrents in the 3D TI Bi2Se3, even at photon energies that are well above the bulk band gap. Symmetry considerations suggest that this ``photo-galvanic effect'' arises purely from photo-currents induced in the surface Dirac states. To gain insights into this phenomenon, we have carried out systematic measurements of the photo-galvanic effect in electrically gated MBE-grown Bi2Se3 thin films of varying thickness. By using an ionic liquid as an optically transparent gate, we map out the behavior of the photo-galvanic effect as a function of Fermi energy over a temperature range 5 K <= T <= 300 K. Supported by ONR and NSF.

  20. Prevention of Crevice Corrosion of STS 304 Stainless Steel by a Mg-alloy Galvanic Anode

    International Nuclear Information System (INIS)

    Lim, U. J.; Yun, B. D.; Kim, J. J.

    2006-01-01

    Prevention of crevice corrosion was studied for STS 304 stainless steel using a Mg-alloy galvanic anode in solutions with various specific resistivity. The crevice corrosion and corrosion protection characteristics of the steel was investigated by the electrochemical polarization and galvanic corrosion tests. Experimental results show that the crevice corrosion of STS 304 stainless steel does not occur in solutions of high specific resistivity, but it occurs in solutions of low specific resistivity like in solutions with resistivities of 30, 60 and 115 Ω · m. With decreasing specific resistivity of the solution, the electrode potential of STS 304 stainless steel in the crevice is lowered. The potential of STS 304 stainless steel in the crevice after coupling is cathodically polarized more by decreasing specific resistivity indicating that the crevice corrosion of STS 304 stainless steel is prevented by the Mg-alloy galvanic anode

  1. Effect of hot dip galvanization on the fatigue strength of steel bolted connections

    Directory of Open Access Journals (Sweden)

    S.M.J. Razavi

    2017-07-01

    Full Text Available Hot dip galvanized steel bolted joints has been tested under fatigue loading to evaluate the effect of galvanizing coating on the fatigue strength of S355 structural steel. The experimental results showed that the decrease of the fatigue life of coated specimens in comparison with that of uncoated joints is very limited and the results are in good agreement with Eurocode detail category, without substantial reductions. The procedure for coating and preparation of the bolted joints is described in detail in this paper providing a useful tool for engineers involved in similar practical applications. The experimental results are compared with the previously published data on central hole notched galvanized and not treated specimens characterized by the same geometry.

  2. Otolith-Canal Convergence In Vestibular Nuclei Neurons

    Science.gov (United States)

    Dickman, J. David; Si, Xiao-Hong

    2002-01-01

    The current final report covers the period from June 1, 1999 to May 31, 2002. The primary objective of the investigation was to determine how information regarding head movements and head position relative to gravity is received and processed by central vestibular nuclei neurons in the brainstem. Specialized receptors in the vestibular labyrinths of the inner ear function to detect angular and linear accelerations of the head, with receptors located in the semicircular canals transducing rotational head movements and receptors located in the otolith organs transducing changes in head position relative to gravity or linear accelerations of the head. The information from these different receptors is then transmitted to central vestibular nuclei neurons which process the input signals, then project the appropriate output information to the eye, head, and body musculature motor neurons to control compensatory reflexes. Although a number of studies have reported on the responsiveness of vestibular nuclei neurons, it has not yet been possible to determine precisely how these cells combine the information from the different angular and linear acceleration receptors into a correct neural output signal. In the present project, rotational and linear motion stimuli were separately delivered while recording responses from vestibular nuclei neurons that were characterized according to direct input from the labyrinth and eye movement sensitivity. Responses from neurons receiving convergent input from the semicircular canals and otolith organs were quantified and compared to non-convergent neurons.

  3. Vestibular dysfunction in Turner syndrome: a case report.

    Science.gov (United States)

    Baxter, Michael; Agrawal, Yuri

    2014-02-01

    Turner syndrome is a well-known cause of sensorineural hearing loss, and the lack of estrogen has been implicated in cochlear dysfunction. It has never been associated with vestibular dysfunction. We report a case of a patient with Turner syndrome who was found to have bilateral vestibular dysfunction based on video-oculography (VOG) testing. A single patient with a history of Turner syndrome who was found to have significant bilateral vestibular dysfunction. After noticing a deficit in the vestibulo-ocular reflexes on qualitative horizontal head impulse examination, the patient underwent VOG testing. VOG testing quantatively measures angular vestibulo-ocular reflex (AVOR) gain in the horizontal semicircular canal plane. AVOR gain represents the eye movement response to a head movement; in normal individuals the eye movement is fully compensatory and gain values are close to unity. VOG results showed AVOR gains of 0.29 and 0.36 on the right and left sides, respectively. We have presented a case of a woman with Turner syndrome with asymptomatic vestibular dysfunction demonstrated with VOG testing. Although there is a documented relationship between Turner syndrome and sensorineural hearing loss, there are no previous studies or case reports linking Turner syndrome and vestibular dysfunction. Additional research and added vigilance in monitoring Turner syndrome patients may be warranted.

  4. Impaired math achievement in patients with acute vestibular neuritis.

    Science.gov (United States)

    Moser, Ivan; Vibert, Dominique; Caversaccio, Marco D; Mast, Fred W

    2017-12-01

    Broad cognitive difficulties have been reported in patients with peripheral vestibular deficit, especially in the domain of spatial cognition. Processing and manipulating numbers relies on the ability to use the inherent spatial features of numbers. It is thus conceivable that patients with acute peripheral vestibular deficit show impaired numerical cognition. Using the number Stroop task and a short math achievement test, we tested 20 patients with acute vestibular neuritis and 20 healthy, age-matched controls. On the one hand, patients showed normal congruency and distance effects in the number Stroop task, which is indicative of normal number magnitude processing. On the other hand, patients scored lower than healthy controls in the math achievement test. We provide evidence that the lower performance cannot be explained by either differences in prior math knowledge (i.e., education) or slower processing speed. Our results suggest that peripheral vestibular deficit negatively affects numerical cognition in terms of the efficient manipulation of numbers. We discuss the role of executive functions in math performance and argue that previously reported executive deficits in patients with peripheral vestibular deficit provide a plausible explanation for the lower math achievement scores. In light of the handicapping effects of impaired numerical cognition in daily living, it is crucial to further investigate the mechanisms that cause mathematical deficits in acute PVD and eventually develop adequate means for cognitive interventions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Influence of cochlear implantation on peripheral vestibular receptor function.

    Science.gov (United States)

    Krause, Eike; Louza, Julia P R; Wechtenbruch, Juliane; Gürkov, Robert

    2010-06-01

    The objectives of this study were 1) to assess the influence of a cochlear implantation on peripheral vestibular receptor function in the inner ear in the implant and in the nonimplant side, and 2) to analyze a possible correlation with resulting vertigo symptoms. Prospective clinical study. Cochlear implant center at tertiary referral hospital. A total of 32 patients, aged 15 to 83 years, undergoing cochlear implantation were assessed pre- and postoperatively for caloric horizontal semicircular canal response and vestibular-evoked myogenic potentials of the sacculus, and postoperatively for subjective vertigo symptoms. Patients with vertigo were compared with patients without symptoms with regard to the findings of the vestibular function tests. Cochlear implantation represents a significant risk factor for horizontal semicircular canal impairment (P 0.05). Cochlear implantation is a relevant risk factor for damage of peripheral vestibular receptor function. Therefore, preservation not only of residual hearing function but also of vestibular function should be aimed for, by using minimally invasive surgical techniques. Copyright 2010 American Academy of Otolaryngology-Head and Neck Surgery Foundation. Published by Mosby, Inc. All rights reserved.

  6. Estimation of the second heart sound split using windowed sinusoidal models

    DEFF Research Database (Denmark)

    Sæderup, Rasmus Gundorf; Hoang, Poul; Winther, Simon

    2018-01-01

    to the potential overlap between A2 and P2. In this paper, a model-based approach is proposed where both A2 and P2 are modeled as windowed sinusoids with their sum forming the S2 signal. Estimation of the model parameters and the S2 split form a non-convex optimization problem, where a local minimum is obtained...... using a sequential optimization procedure. First, the window parameters are found as the solution to a regularized least squares problem. Then, the frequencies and phases of the sinusoids are found by locating the maximal peaks of the heart signals’ frequency magnitudes, and using the corresponding...

  7. Association between vestibular function and motor performance in hearing-impaired children.

    Science.gov (United States)

    Maes, Leen; De Kegel, Alexandra; Van Waelvelde, Hilde; Dhooge, Ingeborg

    2014-12-01

    The clinical balance performance of normal-hearing (NH) children was compared with the balance performance of hearing-impaired (HI) children with and without vestibular dysfunction to identify an association between vestibular function and motor performance. Prospective study. Tertiary referral center. Thirty-six children (mean age, 7 yr 5 mo; range, 3 yr 8 mo-12 yr 11 mo) divided into three groups: NH children with normal vestibular responses, HI children with normal vestibular responses, and HI children with abnormal vestibular function. A vestibular test protocol (rotatory and collic vestibular evoked myogenic potential testing) in combination with three clinical balance tests (balance beam walking, one-leg hopping, one-leg stance). Clinical balance performance. HI children with abnormal vestibular test results obtained the lowest quotients of motor performance, which were significantly lower compared with the NH group (p beam walking and one-leg stance; p = 0.003 for one-leg hopping). The balance performance of the HI group with normal vestibular responses was better in comparison with the vestibular impaired group but still significantly lower compared with the NH group (p = 0.020 for balance beam walking; p = 0.001 for one-leg stance; not significant for one-leg hopping). These results indicate an association between vestibular function and motor performance in HI children, with a more distinct motor deterioration if a vestibular impairment is superimposed to the auditory dysfunction.

  8. Morphology and electrophysiology of the vestibular organ in the guinea pig

    NARCIS (Netherlands)

    Oei, Markus Lee Yang Murti

    2003-01-01

    To obtain more information about the anatomy and function of the vestibular organ in normal and pathological conditions, evaluation methods are needed. For experimental purposes, the vestibular organ of the guinea pig is often used as a model for the human vestibular organ. The purpose of the

  9. Evaluation of diagnostic tests of the otolith organs and their application in various vestibular pathologies

    NARCIS (Netherlands)

    Winters, S.M.

    2014-01-01

    Current vestibular testing is limited. The general function of the vestibular system on both sides of the head can be tested, and one part of the peripheral vestibular organ, the horizontal semicircular canal, can be tested unilaterally. However, recently a test for the function of the otolith

  10. Prognostic investigation of galvanic corrosion precursors in aircraft structures and their detection strategy

    Science.gov (United States)

    James, Robin; Kim, Tae Hee; Narayanan, Ram M.

    2017-04-01

    Aluminum alloys have been the dominant materials for aerospace construction in the past fifty years due to their light weight, forming and alloying, and relative low cost in comparison to titanium and composites. However, in recent years, carbon fiber reinforced polymers (CFRPs) and honeycomb materials have been used in aircrafts in the quest to attain lower weight, high temperature resistance, and better fuel efficiency. When these two materials are coupled together, the structural strength of the aircraft is unparalleled, but this comes at a price, namely galvanic corrosion. Previous experimental results have shown that when CFRP composite materials are joined with high strength aluminum alloys (AA7075-T6 or AA2024-T3), galvanic corrosion occurs at the material interfaces, and the aluminum is in greater danger of corroding, particularly since carbon and aluminum are on the opposite ends of the galvanic series. In this paper, we explore the occurrence of the recognizable precursors of galvanic corrosion when CFRP plate is coupled to an aluminum alloy using SS-304 bolts and exposed to environmental degradation, which creates significant concerns for aircraft structural reliability. The galvanic corrosion software package, BEASY, is used to simulate the growth of corrosion in the designed specimen after which a microwave non-destructive testing (NDT) technique is explored to detect corrosion defects that appear at the interface of this galvanic couple. This paper also explores a loaded waveguide technique to determine the dielectric constant of the final corrosion product at the Q-band millimeter-wave frequency range (33-50 GHz), as this can be an invaluable asset in developing early detection strategies.

  11. Electrochemical characteristics of a carbon fibre composite and the associated galvanic effects with aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z., E-mail: zuojia.liu@gmail.com; Curioni, M.; Jamshidi, P.; Walker, A.; Prengnell, P.; Thompson, G.E.; Skeldon, P.

    2014-09-30

    Highlights: • Exposed carbon fibres on two defined regions (“front” and “side”) are a focus of the investigation in NaCl electrolyte. • The exposed carbon fibres on the side and front regions are responsible for a high cathodic current density. • The NaCl + CuSO{sub 4} electrolyte was used to investigate the cathodic polarization behaviour of the exposed carbon fibres. • Galvanic coupling behaviour between the composite and aluminium alloys (AA7075-T6 and AA1050) was measured in NaCl electrolyte. • The higher galvanic current density measured on AA1050 alloy introduced a higher dissolution rate than the AA7075-T6 alloy. - Abstract: The electrochemical behaviour of a carbon fibre reinforced epoxy matrix composite in 3.5% NaCl and 3.5% NaCl + 0.5 M CuSO{sub 4} electrolytes was examined by potentiodynamic polarisation, potentiostatic polarisation and scanning electron microscopy. Exposed carbon fibres on two defined regions (“front” and “side”) are a focus of the investigation. The large size of the exposed carbon fibres on the side region is responsible for a higher cathodic current density than the front region in the NaCl electrolyte. The deposition of copper on the front surface of composite confirmed that the significantly higher cathodic current resulted from the exposure of the fibres to the NaCl electrolyte. Galvanic coupling between the composite and individual aluminium alloys (AA7075-T6 and AA1050) was used to measure galvanic potentials and galvanic current densities. The highly alloyed AA7075-T6 alloy and its high population density of cathodic sites compared to the AA1050 acted to reduce the galvanic effect when coupled to the composite front or side regions.

  12. Preventing the embrittling by hydrogen when galvanizing high-grade steel

    Energy Technology Data Exchange (ETDEWEB)

    Paatsch, W.

    1987-09-01

    Galvanic precipitation of a double layer consisting of a dull nickel layer overlaid with a brilliant zinc layer on low-alloyed high-strength steel grades leads to the forming of zinc-nickel alloy layers during the subsequent heat treatment. According to traction tests carried out on high-strength steel grades, as well as to hydrogen permeability tests, this process prevents embrittling by hydrogen which might be caused by galvanic process sequences - and creates a diffusion block at the same time. The alloy layers have an excellent corrosion resistance and temperature stability.

  13. Analysis of the corrosion products on galvanized steels by FTIR spectroscopy

    International Nuclear Information System (INIS)

    Kasperek, J.

    1998-01-01

    FTIR reflectance spectroscopy has been used for the characterization of products formed by an accelerated wet ageing test on industrial hot-dip galvanized steel. Several aluminium contents are selected. Various products have been detected in this study. The kind and amount vary with the substrate, the type of ageing test used, the relative humidity level and the temperature. The galvanized coatings studied show a mixed zinc-aluminium compound, Zn 6 Al 2 (OH) 16 CO 3 .4H 2O. This phase is observed from the first exposure time on all coatings regardless of the amount of aluminium. Contrary to zinc, no basic aluminium compound has been detected. (orig.)

  14. Digitally Controlled Offline Converter with Galvanic Isolation Based on an 8-bit Microcontroller

    DEFF Research Database (Denmark)

    Jakobsen, Lars Tønnes; Andersen, Michael Andreas E.

    2007-01-01

    This paper presents an offline AC/DC converter with digital control and galvanic isolation that can be implemented using cheap commercially available components. An ATMEL ATTiny26 8-bit microcontroller is used to control the converter. The microcontroller is placed on the secondary side of the co......This paper presents an offline AC/DC converter with digital control and galvanic isolation that can be implemented using cheap commercially available components. An ATMEL ATTiny26 8-bit microcontroller is used to control the converter. The microcontroller is placed on the secondary side...

  15. Galvanic and stress corrosion of copper canisters in repository environment. A short review

    International Nuclear Information System (INIS)

    Hermansson, H.P.; Koenig, M.

    2001-02-01

    The Swedish Nuclear Power Inspectorate, SKI, has studied different aspects of canister and copper corrosion as part of the general improvement of the knowledge base within the area. General and local corrosion has earlier been treated by experiments as well as by thermodynamic calculations. For completeness also galvanic and stress corrosion should be treated. The present work is a short review, intended to indicate areas needing further focus. The work consists of two parts, the first of which contains a judgement of statements concerning risk of galvanic corrosion of copper in the repository. The second part concerns threshold values for the stress intensity factor of stress corrosion in copper. A suggestion is given on how such values possibly could be measured for copper at repository conditions. In early investigations by SKB, galvanic corrosion is not mentioned or at least not treated. In later works it is treated but often in a theoretical way without indications of any further treatment or investigation. Several pieces of work indicate that further investigations are required to ensure that different types of corrosion, like galvanic, cannot occur in the repository environment. There are for example effects of grain size, grain boundary conditions, impurities and other factors that could influence the appearance of galvanic corrosion that are not treated. Those factors have to be considered to be completely sure that galvanic corrosion and related effects does not occur for the actual canister in the specific environment of the repository. The circumstances are so specific, that a rather general discussion indicating that galvanic corrosion is not probable just is not enough. Experiments should also be performed for verification. It is concluded that the following specific areas, amongst others, could benefit from further consideration. Galvanic corrosion of unbreached copper by inhomogeneities in the environment and in the copper metal should be addressed

  16. Self-oscillating Galvanic Isolated Bidirectional Very High Frequency DC-DC Converter

    DEFF Research Database (Denmark)

    Pedersen, Jeppe Arnsdorf; Madsen, Mickey Pierre; Knott, Arnold

    2015-01-01

    This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has to be synch......This paper describes a galvanic isolated bidirectional Very High Frequency (VHF = 30 MHz - 300MHz) ClassE converter. The reason for increasing the switching frequency is to minimize the passive components in the converter. To make the converter topology bidirectional the rectifier has...

  17. Galvanic and stress corrosion of copper canisters in repository environment. A short review

    Energy Technology Data Exchange (ETDEWEB)

    Hermansson, H.P.; Koenig, M. [Studsvik Nuclear AB, Nykoeping (Sweden)

    2001-02-01

    The Swedish Nuclear Power Inspectorate, SKI, has studied different aspects of canister and copper corrosion as part of the general improvement of the knowledge base within the area. General and local corrosion has earlier been treated by experiments as well as by thermodynamic calculations. For completeness also galvanic and stress corrosion should be treated. The present work is a short review, intended to indicate areas needing further focus. The work consists of two parts, the first of which contains a judgement of statements concerning risk of galvanic corrosion of copper in the repository. The second part concerns threshold values for the stress intensity factor of stress corrosion in copper. A suggestion is given on how such values possibly could be measured for copper at repository conditions. In early investigations by SKB, galvanic corrosion is not mentioned or at least not treated. In later works it is treated but often in a theoretical way without indications of any further treatment or investigation. Several pieces of work indicate that further investigations are required to ensure that different types of corrosion, like galvanic, cannot occur in the repository environment. There are for example effects of grain size, grain boundary conditions, impurities and other factors that could influence the appearance of galvanic corrosion that are not treated. Those factors have to be considered to be completely sure that galvanic corrosion and related effects does not occur for the actual canister in the specific environment of the repository. The circumstances are so specific, that a rather general discussion indicating that galvanic corrosion is not probable just is not enough. Experiments should also be performed for verification. It is concluded that the following specific areas, amongst others, could benefit from further consideration. Galvanic corrosion of unbreached copper by inhomogeneities in the environment and in the copper metal should be addressed

  18. Immunocytochemical and stereological analysis of GABA(B) receptor subunit expression in the rat vestibular nucleus following unilateral vestibular deafferentation.

    Science.gov (United States)

    Zhang, Rong; Ashton, John; Horii, Arata; Darlington, Cynthia L; Smith, Paul F

    2005-03-10

    The process of behavioral recovery that occurs following damage to one vestibular labyrinth, vestibular compensation, has been attributed in part to a down-regulation of GABA(B) receptors in the vestibular nucleus complex (VNC) ipsilateral to the lesion, which could potentially reduce commissural inhibition from the contralateral VNC. In this study, we tested the possibility that this occurs through a decrease in the expression of either the GABA(B1) or GABA(B2) subunits of the GABA(B) receptor. We used Western blotting to quantify the expression of these subunits in the VNC at 10 h and 50 h following unilateral vestibular deafferentation (UVD) or sham surgery in rats. We then used immunocytochemistry and stereological counting methods to estimate the number of neurons expressing these subunits in the MVN at 10 h and 2 weeks following UVD or sham surgery. Compared to sham controls, we found no significant changes in either the expression of the two GABA(B) receptor subunits in the VNC or in the number of MVN neurons expressing these GABA(B) receptor subunits post-UVD. These results suggest that GABA(B) receptor expression does not change substantially in the VNC during the process of vestibular compensation.

  19. Vestibular myogenic and acoustical brainstem evoked potentials in neurological practice

    Directory of Open Access Journals (Sweden)

    O. S. Korepina

    2012-01-01

    Full Text Available Along with the inspection of acoustical cortex and brainstem EP in neurologic, otoneurologic and audiologic practice recently start to use so-called vestibular evoked myogenic potentials (VEMP. It is shown, that at ear stimulation by a loud sound and record of sterno-cleidomastoid contraction is possible to estimate function of the inferior vestibular nerve and vestibulospinal pathways, a sacculo-cervical reflex. In article some methodical and clinical questions of application of these kinds are presented. Combine research acoustic brainstem EP and VEMP allows to confirm effectively lesions of acoustical and vestibular ways at brainstem. The conclusion becomes, that this kind of inspection is important for revealing demielinisation and defeats in vestibulospinal tract, that quite often happens at MS, and at estimation of efficiency of treatment

  20. The effects of aging on clinical vestibular evaluations

    Directory of Open Access Journals (Sweden)

    Maxime eMaheu

    2015-09-01

    Full Text Available Balance disorders are common issues for aging populations due to the effects of normal aging on peripheral vestibular structures. These changes affect the results of vestibular function evaluations and make the interpretation of these results more difficult. The objective of this article is to review the current state of knowledge of clinically relevant vestibular measures. We will first focus on otolith function assessment methods cVEMP and oVEMP, then the caloric and vHIT methods for semi-circular canals assessment. cVEMP and oVEMP are useful methods, though research on the effects of age for some parameters are still inconclusive. vHIT results are largely independent of age as compared to caloric stimulation and should therefore be preferred for the evaluation of the semi-circular canals function.

  1. Visual gravitational motion and the vestibular system in humans

    Directory of Open Access Journals (Sweden)

    Francesco eLacquaniti

    2013-12-01

    Full Text Available The visual system is poorly sensitive to arbitrary accelerations, but accurately detects the effects of gravity on a target motion. Here we review behavioral and neuroimaging data about the neural mechanisms for dealing with object motion and egomotion under gravity. The results from several experiments show that the visual estimates of a target motion under gravity depend on the combination of a prior of gravity effects with on-line visual signals on target position and velocity. These estimates are affected by vestibular inputs, and are encoded in a visual-vestibular network whose core regions lie within or around the Sylvian fissure, and are represented by the posterior insula/retroinsula/temporo-parietal junction. This network responds both to target motions coherent with gravity and to vestibular caloric stimulation in human fMRI studies. Transient inactivation of the temporo-parietal junction selectively disrupts the interception of targets accelerated by gravity.

  2. Migraine patients consistently show abnormal vestibular bedside tests

    Directory of Open Access Journals (Sweden)

    Eliana Teixeira Maranhão

    2015-01-01

    Full Text Available Migraine and vertigo are common disorders, with lifetime prevalences of 16% and 7% respectively, and co-morbidity around 3.2%. Vestibular syndromes and dizziness occur more frequently in migraine patients. We investigated bedside clinical signs indicative of vestibular dysfunction in migraineurs.Objective To test the hypothesis that vestibulo-ocular reflex, vestibulo-spinal reflex and fall risk (FR responses as measured by 14 bedside tests are abnormal in migraineurs without vertigo, as compared with controls.Method Cross-sectional study including sixty individuals – thirty migraineurs, 25 women, 19-60 y-o; and 30 gender/age healthy paired controls.Results Migraineurs showed a tendency to perform worse in almost all tests, albeit only the Romberg tandem test was statistically different from controls. A combination of four abnormal tests better discriminated the two groups (93.3% specificity.Conclusion Migraine patients consistently showed abnormal vestibular bedside tests when compared with controls.

  3. Migraine patients consistently show abnormal vestibular bedside tests.

    Science.gov (United States)

    Maranhão, Eliana Teixeira; Maranhão-Filho, Péricles; Luiz, Ronir Raggio; Vincent, Maurice Borges

    2016-01-01

    Migraine and vertigo are common disorders, with lifetime prevalences of 16% and 7% respectively, and co-morbidity around 3.2%. Vestibular syndromes and dizziness occur more frequently in migraine patients. We investigated bedside clinical signs indicative of vestibular dysfunction in migraineurs. To test the hypothesis that vestibulo-ocular reflex, vestibulo-spinal reflex and fall risk (FR) responses as measured by 14 bedside tests are abnormal in migraineurs without vertigo, as compared with controls. Cross-sectional study including sixty individuals - thirty migraineurs, 25 women, 19-60 y-o; and 30 gender/age healthy paired controls. Migraineurs showed a tendency to perform worse in almost all tests, albeit only the Romberg tandem test was statistically different from controls. A combination of four abnormal tests better discriminated the two groups (93.3% specificity). Migraine patients consistently showed abnormal vestibular bedside tests when compared with controls.

  4. Visual gravitational motion and the vestibular system in humans.

    Science.gov (United States)

    Lacquaniti, Francesco; Bosco, Gianfranco; Indovina, Iole; La Scaleia, Barbara; Maffei, Vincenzo; Moscatelli, Alessandro; Zago, Myrka

    2013-12-26

    The visual system is poorly sensitive to arbitrary accelerations, but accurately detects the effects of gravity on a target motion. Here we review behavioral and neuroimaging data about the neural mechanisms for dealing with object motion and egomotion under gravity. The results from several experiments show that the visual estimates of a target motion under gravity depend on the combination of a prior of gravity effects with on-line visual signals on target position and velocity. These estimates are affected by vestibular inputs, and are encoded in a visual-vestibular network whose core regions lie within or around the Sylvian fissure, and are represented by the posterior insula/retroinsula/temporo-parietal junction. This network responds both to target motions coherent with gravity and to vestibular caloric stimulation in human fMRI studies. Transient inactivation of the temporo-parietal junction selectively disrupts the interception of targets accelerated by gravity.

  5. Rapid adaptation of multisensory integration in vestibular pathways

    Directory of Open Access Journals (Sweden)

    Jerome eCarriot

    2015-04-01

    Full Text Available Sensing gravity is vital for our perception of spatial orientation, the control of upright posture, and generation of our every day activities. When an astronaut transitions to microgravity or returns to earth, the vestibular input arising from self-motion will not match the brain’s expectation. Our recent neurophysiological studies have provided insight into how the nervous system rapidly reorganizes when vestibular input becomes unreliable by both 1 updating its internal model of the sensory consequences of motion and 2 up-weighting more reliable extra-vestibular information. These neural strategies, in turn, are linked to improvements in sensorimotor performance (e.g., gaze and postural stability, locomotion, orienting and perception characterized by similar time courses. We suggest that furthering our understanding of the neural mechanisms that underlie sensorimotor adaptation will have important implications for optimizing training programs for astronauts before and after space exploration missions and for the design of goal-oriented rehabilitation for patients.

  6. Assessment of the risk of fall, related to visual stimulation, in patients with central vestibular disorders.

    Science.gov (United States)

    Suárez, H; Musé, P; Suárez, A; Arocena, M

    2001-01-01

    In order to assess the influence of visual stimulation in the triggering of imbalance and falls in the elderly population, the postural responses of 18 elderly patients with central vestibular disorders and clinical evidence of instability and falls were studied while receiving different types of visual stimuli. The stimulation conditions were: (i) no specific stimuli; (ii) smooth pursuit with pure sinusoids of 0.2 Hz as foveal stimulation; and (iii) optokinetic stimulation (OK) as retinal stimuli. Using a platform AMTI Accusway platform, the 95% confidence ellipse (CE) and sway velocity (SV) were evaluated with a scalogram using wavelets in order to assess the relationship between time and frequency in postural control. Velocity histograms were also constructed in order to observe the distribution of velocity values during the recording. A non-homogeneous postural behavior after visual stimulation was found among this population. In five of the patients the OK stimulation generated: (i) significantly higher average values of CE ( > 3.4+/-0.69 cm2); (ii) a significant increase in the average values of the SV ( > 3.89+/-1.15 cm/s) and a velocity histogram with a homogeneous distribution between 0 and 18 cm/s; and (iii) a scalogram with sway frequencies of up to 4 Hz distributed in both the X and Y directions (backwards and forwards and lateral) during visual stimulation with arbitrary units of energy density > 5. These three qualitative and quantitative aspects could be "markers" of visual dependence in the triggering of the mechanism of lack of equilibrium and hence falls in some elderly patients and should be considered in order to prevent falls and also to assist in the rehabilitation program of these patients.

  7. Using Low Levels of Stochastic Vestibular Stimulation to Improve Balance Function.

    Directory of Open Access Journals (Sweden)

    Rahul Goel

    Full Text Available Low-level stochastic vestibular stimulation (SVS has been associated with improved postural responses in the medio-lateral (ML direction, but its effect in improving balance function in both the ML and anterior-posterior (AP directions has not been studied. In this series of studies, the efficacy of applying low amplitude SVS in 0-30 Hz range between the mastoids in the ML direction on improving cross-planar balance function was investigated. Forty-five (45 subjects stood on a compliant surface with their eyes closed and were instructed to maintain a stable upright stance. Measures of stability of the head, trunk, and whole body were quantified in ML, AP and combined APML directions. Results show that binaural bipolar SVS given in the ML direction significantly improved balance performance with the peak of optimal stimulus amplitude predominantly in the range of 100-500 μA for all the three directions, exhibiting stochastic resonance (SR phenomenon. Objective perceptual and body motion thresholds as estimates of internal noise while subjects sat on a chair with their eyes closed and were given 1 Hz bipolar binaural sinusoidal electrical stimuli were also measured. In general, there was no significant difference between estimates of perceptual and body motion thresholds. The average optimal SVS amplitude that improved balance performance (peak SVS amplitude normalized to perceptual threshold was estimated to be 46% in ML, 53% in AP, and 50% in APML directions. A miniature patch-type SVS device may be useful to improve balance function in people with disabilities due to aging, Parkinson's disease or in astronauts returning from long-duration space flight.

  8. Motor Performance is Impaired Following Vestibular Stimulation in Ageing Mice

    Science.gov (United States)

    Tung, Victoria W. K.; Burton, Thomas J.; Quail, Stephanie L.; Mathews, Miranda A.; Camp, Aaron J.

    2016-01-01

    Balance and maintaining postural equilibrium are important during stationary and dynamic movements to prevent falls, particularly in older adults. While our sense of balance is influenced by vestibular, proprioceptive, and visual information, this study focuses primarily on the vestibular component and its age-related effects on balance. C57Bl/6J mice of ages 1, 5–6, 8–9 and 27–28 months were tested using a combination of standard (such as grip strength and rotarod) and newly-developed behavioral tests (including balance beam and walking trajectory tests with a vestibular stimulus). In the current study, we confirm a decline in fore-limb grip strength and gross motor coordination as age increases. We also show that a vestibular stimulus of low frequency (2–3 Hz) and duration can lead to age-dependent changes in balance beam performance, which was evident by increases in latency to begin walking on the beam as well as the number of times hind-feet slip (FS) from the beam. Furthermore, aged mice (27–28 months) that received continuous access to a running wheel for 4 weeks did not improve when retested. Mice of ages 1, 10, 13 and 27–28 months were also tested for changes in walking trajectory as a result of the vestibular stimulus. While no linear relationship was observed between the changes in trajectory and age, 1-month-old mice were considerably less affected than mice of ages 10, 13 and 27–28 months. Conclusion: this study confirms there are age-related declines in grip strength and gross motor coordination. We also demonstrate age-dependent changes to finer motor abilities as a result of a low frequency and duration vestibular stimulus. These changes showed that while the ability to perform the balance beam task remained intact across all ages tested, behavioral changes in task performance were observed. PMID:26869921

  9. Motor performance is impaired following vestibular stimulation in ageing mice.

    Directory of Open Access Journals (Sweden)

    Victoria W.K. Tung

    2016-02-01

    Full Text Available Balance and maintaining postural equilibrium are important during stationary and dynamic movements to prevent falls, particularly in older adults. While our sense of balance is influenced by vestibular, proprioceptive, and visual information, this study focuses primarily on the vestibular component and its age-related effects on balance. C57Bl/6J mice of ages 1, 5-6, 8-9 and 27-28 months were tested using a combination of standard (such as grip strength and rotarod and newly-developed behavioural tests (including balance beam and walking trajectory tests with a vestibular stimulus. In the current study, we confirm a decline in fore-limb grip strength and gross motor coordination as age increases. We also show that a vestibular stimulus of low frequency (2-3 Hz and duration can lead to age-dependent changes in balance beam performance, which was evident by increases in latency to begin walking on the beam as well as the number of times hind-feet slip from the beam. Furthermore, aged mice (27-28 months that received continuous access to a running wheel for 4 weeks did not improve when retested. Mice of ages 1, 10, 13, and 27-28 months were also tested for changes in walking trajectory as a result of the vestibular stimulus. While no linear relationship was observed between the changes in trajectory and age, 1-month-old mice were considerably less affected than mice of ages 10, 13, and 27-28 months. Conclusion: This study confirms there are age-related declines in grip strength and gross motor coordination. We also demonstrate age-dependent changes to finer motor abilities as a result of a low frequency and duration vestibular stimulus. These changes showed that while the ability to perform the balance beam task remained intact across all ages tested, behavioural changes in task performance were observed.

  10. Motor Performance is Impaired Following Vestibular Stimulation in Ageing Mice.

    Science.gov (United States)

    Tung, Victoria W K; Burton, Thomas J; Quail, Stephanie L; Mathews, Miranda A; Camp, Aaron J

    2016-01-01

    Balance and maintaining postural equilibrium are important during stationary and dynamic movements to prevent falls, particularly in older adults. While our sense of balance is influenced by vestibular, proprioceptive, and visual information, this study focuses primarily on the vestibular component and its age-related effects on balance. C57Bl/6J mice of ages 1, 5-6, 8-9 and 27-28 months were tested using a combination of standard (such as grip strength and rotarod) and newly-developed behavioral tests (including balance beam and walking trajectory tests with a vestibular stimulus). In the current study, we confirm a decline in fore-limb grip strength and gross motor coordination as age increases. We also show that a vestibular stimulus of low frequency (2-3 Hz) and duration can lead to age-dependent changes in balance beam performance, which was evident by increases in latency to begin walking on the beam as well as the number of times hind-feet slip (FS) from the beam. Furthermore, aged mice (27-28 months) that received continuous access to a running wheel for 4 weeks did not improve when retested. Mice of ages 1, 10, 13 and 27-28 months were also tested for changes in walking trajectory as a result of the vestibular stimulus. While no linear relationship was observed between the changes in trajectory and age, 1-month-old mice were considerably less affected than mice of ages 10, 13 and 27-28 months. this study confirms there are age-related declines in grip strength and gross motor coordination. We also demonstrate age-dependent changes to finer motor abilities as a result of a low frequency and duration vestibular stimulus. These changes showed that while the ability to perform the balance beam task remained intact across all ages tested, behavioral changes in task performance were observed.

  11. Plasticity during vestibular compensation: the role of saccades

    Directory of Open Access Journals (Sweden)

    Hamish Gavin MacDougall

    2012-02-01

    Full Text Available This paper is focussed on one major aspect of compensation: the recent behavioural findings concerning oculomotor responses in human vestibular compensation and their possible implications for recovery after unilateral vestibular loss (UVL. New measurement techniques have provided new insights into how patients recover after UVL and have given clues for vestibular rehabilitation. Prior to this it has not been possible to quantify the level of function of all the peripheral vestibular sense organs. Now it is. By using vestibular-evoked myogenic potentials to measure utricular and saccular function and by new video head impulse testing to measure semicircular canal function to natural values of head accelerations. With these new video procedures it is now possible to measure both slow phase eye velocity and also saccades during natural head movements. The present evidence is that there is little or no recovery of slow phase eye velocity responses to natural head accelerations. It is doubtful as to whether the modest changes in slow phase eye velocity to small angular accelerations are functionally effective during compensation. On the other hand it is now clear that saccades can play a very important role in helping patients compensate and return to a normal lifestyle. Preliminary evidence suggests that different patterns of saccadic response may predict how well patients recover. It may be possible to train patients to produce more effective saccadic patterns in the first days after their unilateral loss. Some patients do learn new strategies, new behaviours, to conceal their inadequate VOR but when those strategies are prevented from operating by using passive, unpredictable, high acceleration natural head movements, as in the head impulse test, their vestibular loss can be demonstrated. It is those very strategies which the tests exclude, which may be the cause of their successful compensation.

  12. Visual and proprioceptive interaction in patients with bilateral vestibular loss.

    Science.gov (United States)

    Cutfield, Nicholas J; Scott, Gregory; Waldman, Adam D; Sharp, David J; Bronstein, Adolfo M

    2014-01-01

    Following bilateral vestibular loss (BVL) patients gradually adapt to the loss of vestibular input and rely more on other sensory inputs. Here we examine changes in the way proprioceptive and visual inputs interact. We used functional magnetic resonance imaging (fMRI) to investigate visual responses in the context of varying levels of proprioceptive input in 12 BVL subjects and 15 normal controls. A novel metal-free vibrator was developed to allow vibrotactile neck proprioceptive input to be delivered in the MRI system. A high level (100 Hz) and low level (30 Hz) control stimulus was applied over the left splenius capitis; only the high frequency stimulus generates a significant proprioceptive stimulus. The neck stimulus was applied in combination with static and moving (optokinetic) visual stimuli, in a factorial fMRI experimental design. We found that high level neck proprioceptive input had more cortical effect on brain activity in the BVL patients. This included a reduction in visual motion responses during high levels of proprioceptive input and differential activation in the midline cerebellum. In early visual cortical areas, the effect of high proprioceptive input was present for both visual conditions but in lateral visual areas, including V5/MT, the effect was only seen in the context of visual motion stimulation. The finding of a cortical visuo-proprioceptive interaction in BVL patients is consistent with behavioural data indicating that, in BVL patients, neck afferents partly replace vestibular input during the CNS-mediated compensatory process. An fMRI cervico-visual interaction may thus substitute the known visuo-vestibular interaction reported in normal subject fMRI studies. The results provide evidence for a cortical mechanism of adaptation to vestibular failure, in the form of an enhanced proprioceptive influence on visual processing. The results may provide the basis for a cortical mechanism involved in proprioceptive substitution of vestibular

  13. Kv1 channels and neural processing in vestibular calyx afferents

    Directory of Open Access Journals (Sweden)

    Frances L Meredith

    2015-06-01

    Full Text Available Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K+ channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K+ channels could help alleviate vestibular dysfunction on earth and in space.

  14. Kv1 channels and neural processing in vestibular calyx afferents.

    Science.gov (United States)

    Meredith, Frances L; Kirk, Matthew E; Rennie, Katherine J

    2015-01-01

    Potassium-selective ion channels are important for accurate transmission of signals from auditory and vestibular sensory end organs to their targets in the central nervous system. During different gravity conditions, astronauts experience altered input signals from the peripheral vestibular system resulting in sensorimotor dysfunction. Adaptation to altered sensory input occurs, but it is not explicitly known whether this involves synaptic modifications within the vestibular epithelia. Future investigations of such potential plasticity require a better understanding of the electrophysiological mechanisms underlying the known heterogeneity of afferent discharge under normal conditions. This study advances this understanding by examining the role of the Kv1 potassium channel family in mediating action potentials in specialized vestibular afferent calyx endings in the gerbil crista and utricle. Pharmacological agents selective for different sub-types of Kv1 channels were tested on membrane responses in whole cell recordings in the crista. Kv1 channels sensitive to α-dendrotoxin and dendrotoxin-K were found to prevail in the central regions, whereas K(+) channels sensitive to margatoxin, which blocks Kv1.3 and 1.6 channels, were more prominent in peripheral regions. Margatoxin-sensitive currents showed voltage-dependent inactivation. Dendrotoxin-sensitive currents showed no inactivation and dampened excitability in calyces in central neuroepithelial regions. The differential distribution of Kv1 potassium channels in vestibular afferents supports their importance in accurately relaying gravitational and head movement signals through specialized lines to the central nervous system. Pharmacological modulation of specific groups of K(+) channels could help alleviate vestibular dysfunction on earth and in space.

  15. Vertigo with sudden hearing loss: audio-vestibular characteristics.

    Science.gov (United States)

    Pogson, Jacob M; Taylor, Rachael L; Young, Allison S; McGarvie, Leigh A; Flanagan, Sean; Halmagyi, G Michael; Welgampola, Miriam S

    2016-10-01

    Acute vertigo with sudden sensorineural hearing loss (SSNHL) is a rare clinical emergency. Here, we report the audio-vestibular test profiles of 27 subjects who presented with these symptoms. The vestibular test battery consisted of a three-dimensional video head impulse test (vHIT) of semicircular canal function and recording ocular and cervical vestibular-evoked myogenic potentials (oVEMP, cVEMP) to test otolith dysfunction. Unlike vestibular neuritis, where the horizontal and anterior canals with utricular function are more frequently impaired, 74 % of subjects with vertigo and SSNHL demonstrated impairment of the posterior canal gain (0.45 ± 0.20). Only 41 % showed impairment of the horizontal canal gains (0.78 ± 0.27) and 30 % of the anterior canal gains (0.79 ± 0.26), while 38 % of oVEMPs [asymmetry ratio (AR) = 41.0 ± 41.3 %] and 33 % of cVEMPs (AR = 47.3 ± 41.2 %) were significantly asymmetrical. Twenty-three subjects were diagnosed with labyrinthitis/labyrinthine infarction in the absence of evidence for an underlying pathology. Four subjects had a definitive diagnosis [Ramsay Hunt Syndrome, vestibular schwannoma, anterior inferior cerebellar artery (AICA) infarction, and traction injury]. Ischemia involving the common-cochlear or vestibulo-cochlear branches of the labyrinthine artery could be the simplest explanation for vertigo with SSNHL. Audio-vestibular tests did not provide easy separation between ischaemic and non-ischaemic causes of vertigo with SSNHL.

  16. The Vestibular Effects of Repeated Low-Level Blasts.

    Science.gov (United States)

    Littlefield, Philip D; Pinto, Robin L; Burrows, Holly L; Brungart, Douglas S

    2016-01-01

    The objective of this study was to use a prospective cohort of United States Marine Corps (USMC) instructors to identify any acute or long-term vestibular dysfunction following repeated blast exposures during explosive breaching training. They were assessed in clinic and on location during training at the USMC Methods of Entry School, Quantico, VA. Subjects received comprehensive baseline vestibular assessments and these were repeated in order to identify longitudinal changes. They also received shorter assessments immediately following blast exposure in order to identify acute findings. The main outcome measures were the Neurobehavioral Symptom Inventory, vestibular Visual Analog Scale (VAS) of subjective vestibular function, videonystagmography (VNG), vestibular evoked myogenic potentials (VEMP), rotary chair (including the unilateral centrifugation test), computerized dynamic posturography, and computerized dynamic visual acuity. A total of 11 breachers and 4 engineers were followed for up to 17 months. No acute effects or longitudinal deteriorations were identified, but there were some interesting baseline group differences. Upbeat positional nystagmus was common, and correlated (p<0.005) with a history of mild traumatic brain injury (mTBI). Several instructors had abnormally short low-frequency phase leads on rotary chair testing. This study evaluated breaching instructors over a longer test period than any other study, and the results suggest that this population appears to be safe from a vestibular standpoint at the current exposure levels. Upbeat positional nystagmus correlated with a history of mTBI in this population, and this has not been described elsewhere. The data trends also suggest that this nystagmus could be an acute blast effect. However, the reasons for the abnormally short phase leads seen in rotary chair testing are unclear at this time. Further investigation seems warranted.

  17. Repeat Gamma Knife surgery for vestibular schwannomas

    Science.gov (United States)

    Lonneville, Sarah; Delbrouck, Carine; Renier, Cécile; Devriendt, Daniel; Massager, Nicolas

    2015-01-01

    Background: Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases. Methods: A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases. Results: Mean follow-up duration was 46 months (range 24–110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment. Conclusions: Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment. PMID:26500799

  18. Vestibular schwannoma and fitness to fly.

    Science.gov (United States)

    Pons, Yoann; Raynal, Marc; Hunkemöller, Iris; Lepage, Pierre; Kossowski, Michel

    2010-10-01

    When a pilot is referred for vestibular schwannoma (VS), his or her fitness to fly may be questioned. The objective of this retrospective study was to describe a series of VS cases in a pilot population and to discuss their fitness to fly options. Between September 2002 and March 2010, the ENT/Head and Neck Surgery Department of the National Pilot Expertise Center conducted nearly 120,000 expert consultations for 40,000 pilots. We examined the files of 10 pilots who were referred to our 2 national experts for VS. At the time of the expert consultation, hypoacusis was present in nine cases (four with total deafness), tinnitus in one case, and vertigo in nine cases. In our series, only 2 of the 10 pilots experienced a negative impact on their fitness to fly. Decisions on fitness to fly were based on several factors: minimally disturbed audition, i.e., less than a 35-dB hearing loss with a good speech discrimination score; good balance, i.e., no reported difficulties; no spontaneous nystagmus recorded on videonystagmography (VNG); no postural deviation; and a normal head-shaking test. The delay and the VS's evolution between diagnosis and expert consultation are important because the selection of a treatment to control VS is critical in minimizing the possible associated complications. When a pilot is referred for VS, his or her fitness to fly is determined by the size of the tumor, balance, auditory status, and the follow-up results of these findings. The complications that may arise from VS treatments must also be considered.

  19. [Cavernous haemangiomas: hearing and vestibular inaugural symptoms].

    Science.gov (United States)

    Dumas, G; Schmerber, S

    2004-11-01

    Cavernous haemangiomas (cavernomas)(CH) are relatively rare (2% of cranial tumoral pathology) vascular malformations mostly observed in the central nervous system. Their most common topographical site in brain stem is midline in the pons, for which clinical course may mimic symptoms of peripheral origin (sudden deafness, fluctuating hearing loss, Meniere-like vertigo). To establish the correlation between the clinical manifestations of hearing and balance disturbance and the anatomical site within the pons of cavernous haemangiomas, and to describe their clinical features, and the findings on auditory brainstem response (ABR) and magnetic resonance imaging (MRI). To propose a literature review about CH and its implications. We made a retrospective review of the histories of three patients aged 24, 44 and 45 years, diagnosed as having cavernomas of the brainstem in which audiometric evaluation, videonystagmography (VNG), ABR and imaging techniques lead to the diagnosis of intracranial cavernoma. The clinical and radiological files were reviewed and a direct relationship between symptoms and localization was found in all 3 patients, especially in relation to our understanding of the auditory and vestibular pathways within the brainstem. The literature regarding cavernomas of the pons is reviewed and the clinical, neuroimage, pathological, natural course and management aspects of the disease are discussed. We recommend the use of cerebral MRI for initial diagnosis which shows a typical rosette-like appearance with a heterogeneous signal on T2-weighted images, along with follow-up and investigation into similar profiles among family members. At present there is no consensus about the treatment to follow when cavernomas are located in the brain stem. There is no specific medical treatment for this condition, and surgery is indicated only exceptionally. Anticoagulant therapy, platelet-dispersing medication and violent sports activities are contraindicated.

  20. A Stimulator ASIC Featuring Versatile Management for Vestibular Prostheses.

    Science.gov (United States)

    Dai Jiang; Demosthenous, Andreas; Perkins, Timothy; Xiao Liu; Donaldson, Nick

    2011-04-01

    This paper presents a multichannel stimulator ASIC for an implantable vestibular prosthesis. The system features versatile stimulation management which allows fine setting of the parameters for biphasic stimulation pulses. To address the problem of charge imbalance due to rounding errors, the digital processor can calculate and provide accurate charge correction. A technique to reduce the data rate to the stimulator is described. The stimulator ASIC was implemented in 0.6-μ m high-voltage CMOS technology occupying an area of 2.27 mm(2). The measured performance of the ASIC has been verified using vestibular electrodes in saline.

  1. Vestibular migraine: the most frequent entity of episodic vertigo.

    Science.gov (United States)

    Dieterich, Marianne; Obermann, Mark; Celebisoy, Nese

    2016-04-01

    Vestibular migraine (VM) is the most common cause of episodic vertigo in adults as well as in children. The diagnostic criteria of the consensus document of the International Bárány Society for Neuro-Otology and the International Headache Society (2012) combine the typical signs and symptoms of migraine with the vestibular symptoms lasting 5 min to 72 h and exclusion criteria. Although VM accounts for 7% of patients seen in dizziness clinics and 9% of patients seen in headache clinics it is still underdiagnosed. This review provides an actual overview on the pathophysiology, the clinical characteristics to establish the diagnosis, the differential diagnosis, and the treatment of VM.

  2. Liver sinusoidal endothelial cells induce immunosuppressive IL-10-producing Th1 cells via the Notch pathway

    NARCIS (Netherlands)

    Neumann, Katrin; Rudolph, Christine; Neumann, Christian; Janke, Marko; Amsen, Derk; Scheffold, Alexander

    2015-01-01

    Under homeostasis, liver sinusoidal endothelial cells (LSECs) shift intrahepatic T-cell responses towards tolerance. However, the role of LSECs in the regulation of T-cell-induced liver inflammation is less clear. Here, we studied the capacity of LSECs to modulate pro-inflammatory Th1-cell

  3. Band structure and optical properties of sinusoidal superlattices: ZnSe1-xTex

    International Nuclear Information System (INIS)

    Yang, G.; Lee, S.; Furdyna, J. K.

    2000-01-01

    This paper examines the band structure and optical selection rules in superlattices with a sinusoidal potential profile. The analysis is motivated by the recent successful fabrication of high quality ZnSe 1-x Te x superlattices in which the composition x varies sinusoidally along the growth direction. Although the band alignment in the ZnSe 1-x Te x sinusoidal superlattices is staggered (type II), they exhibit unexpectedly strong photoluminescence, thus suggesting interesting optical behavior. The band structure of such sinusoidal superlattices is formulated in terms of the nearly-free-electron (NFE) approximation, in which the superlattice potential is treated as a perturbation. The resulting band structure is unique, characterized by a single minigap separating two wide, free-electron-like subbands for both electrons and holes. Interband selection rules are derived for optical transitions involving conduction and valence-band states at the superlattice Brillouin-zone center, and at the zone edge. A number of transitions are predicted due to wave-function mixing of different subband states. It should be noted that the zone-center and zone-edge transitions are especially easy to distinguish in these superlattices because of the large width of the respective subbands. The results of the NFE approximation are shown to hold surprisingly well over a wide range of parameters, particularly when the period of the superlattice is short. (c) 2000 The American Physical Society

  4. A Perceptual Model for Sinusoidal Audio Coding Based on Spectral Integration

    NARCIS (Netherlands)

    Van de Par, S.; Kohlrausch, A.; Heusdens, R.; Jensen, J.; Holdt Jensen, S.

    2005-01-01

    Psychoacoustical models have been used extensively within audio coding applications over the past decades. Recently, parametric coding techniques have been applied to general audio and this has created the need for a psychoacoustical model that is specifically suited for sinusoidal modelling of

  5. A perceptual model for sinusoidal audio coding based on spectral integration

    NARCIS (Netherlands)

    Van de Par, S.; Kohlrauch, A.; Heusdens, R.; Jensen, J.; Jensen, S.H.

    2005-01-01

    Psychoacoustical models have been used extensively within audio coding applications over the past decades. Recently, parametric coding techniques have been applied to general audio and this has created the need for a psychoacoustical model that is specifically suited for sinusoidal modelling of

  6. Comparison between the water activation effects by pulsed and sinusoidal helium plasma jets

    Science.gov (United States)

    Xu, Han; Liu, Dingxin; Xia, Wenjie; Chen, Chen; Wang, Weitao; Liu, Zhijie; Wang, Xiaohua; Kong, Michael G.

    2018-01-01

    Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2-, and O2-/ONOO- induced by the pulsed plasma jet have higher concentrations, and the proportional difference increases with the discharge power. However, the emission intensities of OH(A) and O(3p5P) are higher for the sinusoidal plasma jet, which may be attributed to its higher gas temperature since more water vapor could participate in the plasma. In addition, the efficiency of bacterial inactivation induced by the pulsed plasma jet is higher than that for the sinusoidal plasma jet, in accordance with the concentration relation of aqueous reactive species for the two types of plasma jets.

  7. Efficiency enhancement of a self-propelled pitching profile using non-sinusoidal trajectories

    Science.gov (United States)

    Mekadem, M.; Chihani, E.; Oualli, H.; Hanchi, S.; Bouabdallah, A.; Gad-El-Hak, M.

    2017-11-01

    A symmetrical profile is subjected to non-sinusoidal pitching motion. The airfoil has a chord length c = 0.006 m and a semi-circular leading edge with a diameter of D = 0.001 m. The extrados and intrados are two straight lines that intersect at a tapered trailing edge, and the pitching pivot point is positioned at the leading edge. The pitching frequency is in the range of 1 based upon the maximum profile thickness D varies in the range of 35 <= Re <= 210 , which matches insect's Reynolds numbers. The foil movement is executed using the dynamic mesh technique and a user defined function (UDF). The adopted mesh has 70,445 nodes with 5,1960 quadrilateral cells. The results are in good agreement with prior experiments, and, compared to sinusoidal oscillations, show that non-sinusoidal flapping trajectories lead to advancing velocity increase of 550%. Additionally, if improved propulsive efficiency is sought, non-sinusoidal flapping lead to better thrust.

  8. Measurement of definite integral of sinusoidal signal absolute value third power using digital stochastic method

    Directory of Open Access Journals (Sweden)

    Beljić Željko

    2017-01-01

    Full Text Available In this paper a special case of digital stochastic measurement of the third power of definite integral of sinusoidal signal’s absolute value, using 2-bit AD converters is presented. This case of digital stochastic method had emerged from the need to measure power and energy of the wind. Power and energy are proportional to the third power of wind speed. Anemometer output signal is sinusoidal. Therefore an integral of the third power of sinusoidal signal is zero. Two approaches are proposed for the third power calculation of the wind speed signal. One approach is to use absolute value of sinusoidal signal (before AD conversion for which there is no need of multiplier hardware change. The second approach requires small multiplier hardware change, but input signal remains unchanged. For the second approach proposed minimal hardware change was made to calculate absolute value of the result after AD conversion. Simulations have confirmed theoretical analysis. Expected precision of wind energy measurement of proposed device is better than 0,00051% of full scale. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR32019

  9. A Perceptual Model for Sinusoidal Audio Coding Based on Spectral Integration

    Directory of Open Access Journals (Sweden)

    Jensen Søren Holdt

    2005-01-01

    Full Text Available Psychoacoustical models have been used extensively within audio coding applications over the past decades. Recently, parametric coding techniques have been applied to general audio and this has created the need for a psychoacoustical model that is specifically suited for sinusoidal modelling of audio signals. In this paper, we present a new perceptual model that predicts masked thresholds for sinusoidal distortions. The model relies on signal detection theory and incorporates more recent insights about spectral and temporal integration in auditory masking. As a consequence, the model is able to predict the distortion detectability. In fact, the distortion detectability defines a (perceptually relevant norm on the underlying signal space which is beneficial for optimisation algorithms such as rate-distortion optimisation or linear predictive coding. We evaluate the merits of the model by combining it with a sinusoidal extraction method and compare the results with those obtained with the ISO MPEG-1 Layer I-II recommended model. Listening tests show a clear preference for the new model. More specifically, the model presented here leads to a reduction of more than 20% in terms of number of sinusoids needed to represent signals at a given quality level.

  10. Iron Losses in Electrical Machines Due to Non Sinusoidal Alternating Fluxes

    DEFF Research Database (Denmark)

    Ritchie, Ewen; Walker, J.A.; Dorrell, D. G.

    2007-01-01

    This paper shows how the flux waveform in the core of an electrical machine can be vary non- sinusoidally which complicates the calculation of the iron loss in a machine. A set of tests are conducted on a steel sample using an Epstein square where harmonics are injected into the flux waveform which...... of a machine....

  11. Stress singularities in a model of a wood disk under sinusoidal pressure

    Science.gov (United States)

    Jay A. Johnson; John C. Hermanson; Steven M. Cramer; Charles Amundson

    2005-01-01

    A thin, solid, circular wood disk, cut from the transverse plane of a tree stem, can be modeled as a cylindrically orthotropic elastic material. It is known that a stress singularity can occur at the center of a cylindrically orthotropic disk subjected to uniform pressure. If a solid cylindrically orthotropic disk is subjected to sinusoidal pressure distributions, then...

  12. Focal increase of blood flow in the cerebral cortex of man during vestibular stimulation

    DEFF Research Database (Denmark)

    Friberg, L; Olsen, T S; Roland, P E

    1985-01-01

    This study is an attempt to reveal projection areas for vestibular afferents to the human brain. Changes in regional cerebral blood flow (rCBF) were measured over 254 cortical regions during caloric vestibular stimulation with warm water (44 degrees C). rCBF was measured when the external auditory...... meatus was irrigated with water at body temperature as a control to vestibular stimulation. During vestibular stimulation there was only a single cortical area, located in the superior temporal region, which showed a consistent focal activation in the hemisphere contralateral to the stimulated side...... stimulation that gives rise to the associated conscious vestibular sensation of vertigo....

  13. Vestibular evoked myogenic potentials: an overview Potencial evocado miogênico vestibular: uma visão geral

    Directory of Open Access Journals (Sweden)

    Renato Cal

    2009-06-01

    Full Text Available The vestibular evoked myogenic potential (VEMP test is a relatively new diagnostic tool that is in the process of being investigated in patients with specific vestibular disorders. Briefly, the VEMP is a biphasic response elicited by loud clicks or tone bursts recorded from the tonically contracted sternocleidomastoid muscle, being the only resource available to assess the function of the saccule and the lower portion of the vestibular nerve. AIM: In this review, we shall highlight the history, methods, current VEMP status, and discuss its specific application in the diagnosis of the Ménière's Syndrome.O teste do potencial evocado miogênico vestibular (PEMV é um instrumento diagnóstico relativamente novo e ainda em processo de validação em estudos com pacientes portadores de desordens vestibulares específicas. De forma resumida, o PEMV é uma resposta bifásica em resposta a estímulos sonoros gravados a partir de contrações do músculo esternocleidomastóideo e é o único recurso existente para avaliar a função do sáculo e da divisão inferior do nervo vestibular. OBJETIVO: Nesta revisão iremos destacar a história, método de realização, situação atual da pesquisa envolvendo o PEMV, além de discutir as suas aplicações específicas no diagnóstico da síndrome de Ménière.

  14. An experimental study on flow friction and heat transfer of water in sinusoidal wavy silicon microchannels

    Science.gov (United States)

    Huang, Houxue; Wu, Huiying; Zhang, Chi

    2018-05-01

    Sinusoidal wavy microchannels have been known as a more heat transfer efficient heat sink for the cooling of electronics than normal straight microchannels. However, the existing experimental study on wavy silicon microchannels with different phase differences are few. As a result of this, in this paper an experimental study has been conducted to investigate the single phase flow friction and heat transfer of de-ionized water in eight different sinusoidal wavy silicon microchannels (SWSMCs) and one straight silicon microchannel (SMC). The SWSMCs feature different phase differences (α  =  0 to π) and different relative wavy amplitudes (β  =  A/l  =  0.05 to 0.4), but the same average hydraulic diameters (D h  =  160 µm). It is found that both flow friction constant fRe and the Nusselt number depend on the phase difference and relative wavy amplitude. For sinusoidal wavy microchannels with a relative wavy amplitude (β  =  0.05), the Nusselt number increased noticeably with the phase difference for Re  >  250, but the effect was insignificant for Re  reducing the wavy wave length induced higher pressure drop and apparent friction constant fRe, while the Nusselt number increased with relative wavy amplitude for Re  >  300. The results indicate that the thermal resistances of sinusoidal wavy silicon microchannels were generally lower than that of straight silicon microchannels, and the thermal resistance decreased with the increase in relative wavy amplitude. The enhancement of thermal performance is attributed to the flow re-circulation occurring in the corrugation troughs and the secondary flows or Dean vortices introduced by curved channels. It is concluded that silicon sinusoidal wavy microchannels provide higher heat transfer rate albeit with a higher flow friction, making it a better choice for the cooling of high heat flux electronics.

  15. Dynamic Characteristics of Ventilatory and Gas Exchange during Sinusoidal Walking in Humans.

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Fukuoka

    Full Text Available Our present study investigated whether the ventilatory and gas exchange responses show different dynamics in response to sinusoidal change in cycle work rate or walking speed even if the metabolic demand was equivalent in both types of exercise. Locomotive parameters (stride length and step frequency, breath-by-breath ventilation (V̇E and gas exchange (CO2 output (V̇CO2 and O2 uptake (V̇O2 responses were measured in 10 healthy young participants. The speed of the treadmill was sinusoidally changed between 3 km·h-1 and 6 km·h-1 with various periods (from 10 to 1 min. The amplitude of locomotive parameters against sinusoidal variation showed a constant gain with a small phase shift, being independent of the oscillation periods. In marked contrast, when the periods of the speed oscillations were shortened, the amplitude of V̇E decreased sharply whereas the phase shift of V̇E increased. In comparing walking and cycling at the equivalent metabolic demand, the amplitude of V̇E during sinusoidal walking (SW was significantly greater than that during sinusoidal cycling (SC, and the phase shift became smaller. The steeper slope of linear regression for the V̇E amplitude ratio to V̇CO2 amplitude ratio was observed during SW than SC. These findings suggested that the greater amplitude and smaller phase shift of ventilatory dynamics were not equivalent between SW and SC even if the metabolic demand was equivalent between both exercises. Such phenomenon would be derived from central command in proportion to locomotor muscle recruitment (feedforward and muscle afferent feedback.

  16. Vestibular Compensation in Unilateral Patients Often Causes Both Gain and Time Constant Asymmetries in The VOR

    Directory of Open Access Journals (Sweden)

    Mina eRanjbaran

    2016-03-01

    Full Text Available The vestibulo-ocular reflex (VOR is essential in our daily life to stabilize retinal images during head movements. Balanced vestibular functionality secures optimal reflex performance which can be distorted in case of peripheral vestibular lesions. Luckily, vestibular compensation in different neuronal sites restores VOR function to some extent over time. Studying vestibular compensation gives insight into the possible mechanisms for plasticity in the brain.In this work, novel experimental analysis tools are employed to reevaluate the VOR characteristics following unilateral vestibular lesions and compensation. Our results suggest that following vestibular lesions, asymmetric performance of the VOR is not only limited to its gain. Vestibular compensation also causes asymmetric dynamics, i.e. different time constants for the VOR during leftward or rightward passive head rotation. Potential mechanisms for these experimental observations are provided using simulation studies.

  17. Immunohistochemical profile of cytokines and growth factors expressed in vestibular schwannoma and in normal vestibular nerve tissue.

    Science.gov (United States)

    Taurone, Samanta; Bianchi, Enrica; Attanasio, Giuseppe; Di Gioia, Cira; Ierinó, Rocco; Carubbi, Cecilia; Galli, Daniela; Pastore, Francesco Saverio; Giangaspero, Felice; Filipo, Roberto; Zanza, Christian; Artico, Marco

    2015-07-01

    Vestibular schwannomas, also known as acoustic neuromas, are benign tumors, which originate from myelin-forming Schwann cells. They develop in the vestibular branch of the eighth cranial nerve in the internal auditory canal or cerebellopontine angle. The clinical progression of the condition involves slow and progressive growth, eventually resulting in brainstem compression. The objective of the present study was to investigate the expression level and the localization of the pro-inflammatory cytokines, transforming growth factor-β1 (TGF-β1) interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α), as well as the adhesion molecules, intracellular adhesion molecule-1 and vascular endothelial growth factor (VEGF), in order to determine whether these factors are involved in the transformation and development of human vestibular schwannoma. The present study investigated whether changes in inflammation are involved in tumor growth and if so, the mechanisms underlying this process. The results of the current study demonstrated that pro-inflammatory cytokines, including TGF-β1, IL-1β and IL-6 exhibited increased expression in human vestibular schwannoma tissue compared with normal vestibular nerve samples. TNF-α was weakly expressed in Schwann cells, confirming that a lower level of this cytokine is involved in the proliferation of Schwann cells. Neoplastic Schwann cells produce pro-inflammatory cytokines that may act in an autocrine manner, stimulating cellular proliferation. In addition, the increased expression of VEGF in vestibular schwannoma compared with that in normal vestibular nerve tissue, suggests that this factor may induce neoplastic growth via the promotion of angiogenesis. The present findings suggest that inflammation may promote angiogenesis and consequently contribute to tumor progression. In conclusion, the results of the present study indicated that VEGF and pro-inflammatory cytokines may be potential therapeutic targets in vestibular

  18. Intracavity OptoGalvanic Spectroscopy Not Suitable for Ambient Level Radiocarbon Detection

    NARCIS (Netherlands)

    Paul, Dipayan; Meijer, Harro

    2015-01-01

    IntraCavity OptoGalvanic Spectroscopy as a radiocarbon detection technique was first reported by the Murnick group at Rutgers University, Newark, NJ, in 2008. This technique for radiocarbon detection was presented with tremendous potentials for applications in various fields of research.

  19. Influence of the Manufacturing Process on Defects in the Galvanized Coating of High Carbon Steel Wires.

    Science.gov (United States)

    Gelfi, Marcello; Solazzi, Luigi; Poli, Sandro

    2017-03-06

    This study is a detailed failure analysis of galvanized high carbon steel wires, which developed coating cracks during the torsion test performed as a quality control at the end of the manufacturing process. Careful visual inspections showed that the cracks are already present in the coating before the torsion test. In order to explain the origin of these cracks, systematic metallographic investigations were performed by means of optical and scanning electron microscope on both the wires and the rods that have been cold drawn to produce the wire. The chemical composition of the galvanized coatings was evaluated by means of energy dispersive spectroscopy. Micro bidimensional X-ray diffraction experiments were also performed to measure the residual stresses in the galvanized coating. The results showed that the failure is related to two main factors: the relatively high content of silicon in the steel and the unsuitable cooling rate of the rods at the exit from the galvanizing bath. The mechanism proposed to explain the origin of the defects was supported by Finite Elements Methods simulations and verified with in-plant tests. The proper countermeasures were then applied and the problem successfully solved.

  20. A new method for the compensation of ohmic drop in galvanic cells

    NARCIS (Netherlands)

    Kooijman, D.J.; Sluyters, J.H.

    Generally the ohmic potential drop in a galvanic cell that occurs if a rectangular pulse is led through the cell, is compensated by means of a well-known bridge circuit. A better method making use of a phase reverter is described and its features are discussed. Exchange current densities up to 1200

  1. Galvanic detection of sulfur dioxide in ambient air at trace levels by anodic oxidation

    NARCIS (Netherlands)

    Lindqvist, F.

    1978-01-01

    A continuous method for the measurement of SO2 in ambient air at trace levels is described. The principle of detection is based on the anodic oxidation of SO2 in a galvanic cell. A differential measuring technique with a cell with two anodes and one cathode is used; background and noise current are

  2. Influence of the Manufacturing Process on Defects in the Galvanized Coating of High Carbon Steel Wires

    Directory of Open Access Journals (Sweden)

    Marcello Gelfi

    2017-03-01

    Full Text Available This study is a detailed failure analysis of galvanized high carbon steel wires, which developed coating cracks during the torsion test performed as a quality control at the end of the manufacturing process. Careful visual inspections showed that the cracks are already present in the coating before the torsion test. In order to explain the origin of these cracks, systematic metallographic investigations were performed by means of optical and scanning electron microscope on both the wires and the rods that have been cold drawn to produce the wire. The chemical composition of the galvanized coatings was evaluated by means of energy dispersive spectroscopy. Micro bidimensional X-ray diffraction experiments were also performed to measure the residual stresses in the galvanized coating. The results showed that the failure is related to two main factors: the relatively high content of silicon in the steel and the unsuitable cooling rate of the rods at the exit from the galvanizing bath. The mechanism proposed to explain the origin of the defects was supported by Finite Elements Methods simulations and verified with in-plant tests. The proper countermeasures were then applied and the problem successfully solved.

  3. Analysis of the Inhibition Layer of Galvanized Dual-Phase Steels

    International Nuclear Information System (INIS)

    Wang, K. K.; Wang, H. P.; Chang, L.; Gan, D.; Chen, T. R.; Chen, H. B.

    2012-01-01

    The formation of the Fe-Al inhibition layer in hot-dip galvanizing is a confusing issue for a long time. This study presents a characterization result on the inhibition layer formed on C-Mn-Cr and C-Mn-Si dual-phase steels after a short time galvanizing. The samples were annealed at 800 .deg. C for 60 s in N 2 -10% H 2 atmosphere with a dew point of -30 .deg. C, and were then galvanized in a bath containing 0.2%Al. X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was employed for characterization. The TEM electron diffraction shows that only Fe 2 Al 5 intermetallic phase was formed. No orientation relationship between the Fe 2 Al 5 phase and the steel substrate could be identified. Two peaks of Al 2p photoelectrons, one from metallic aluminum and the other from Al 3+ ions, were detected in the inhibition layer, indicating that the layer is in fact a mixture of Fe 2 Al 5 and Al 2 O 3 . TEM/EDS analysis verifies the existence of Al 2 O 3 in the boundaries of Fe 2 Al 5 grains. The nucleation of Fe 2 Al 5 and the reduction of the surface oxide probably proceeded concurrently on galvanizing, and the residual oxides prohibited the heteroepitaxial growth of Fe 2 Al 5

  4. Standard guide for conducting and evaluating galvanic corrosion tests in electrolytes

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1981-01-01

    1.1 This guide covers conducting and evaluating galvanic corrosion tests to characterize the behavior of two dissimilar metals in electrical contact in an electrolyte under low-flow conditions. It can be adapted to wrought or cast metals and alloys. 1.2 This guide covers the selection of materials, specimen preparation, test environment, method of exposure, and method for evaluating the results to characterize the behavior of galvanic couples in an electrolyte. Note 1—Additional information on galvanic corrosion testing and examples of the conduct and evaluation of galvanic corrosion tests in electrolytes are given in Refs (1) through (7). 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicabil...

  5. Media Research with a Galvanic Skin Response Biosensor: Some Kids Work Up a Sweat!

    Science.gov (United States)

    Clariana, Roy B.

    This study considers the galvanic skin response (GSR) of sixth-grade students (n=20) using print, video, and microcomputer segments. Subjects received all three media treatments, in randomized order. Data for analysis consisted of standardized test scores and GSR measures; a moderate positive relationship was shown between cumulative GSR and…

  6. Zinc toxicity among galvanization workers in the iron and steel industry.

    Science.gov (United States)

    El Safty, Amal; El Mahgoub, Khalid; Helal, Sawsan; Abdel Maksoud, Neveen

    2008-10-01

    Galvanization is the process of coating steel or cast iron pieces with zinc, allowing complete protection against corrosion. The ultimate goal of this work was to assess the effect of occupational exposure to zinc in the galvanization process on different metals in the human body and to detect the association between zinc exposure and its effect on the respiratory system. This study was conducted in 111 subjects in one of the major companies in the iron and steel industry. There were 61 subjects (workers) who were involved in the galvanization process. Fifty adult men were chosen as a matched reference group from other departments of the company. All workers were interviewed using a special questionnaire on occupational history and chest diseases. Ventilatory functions and chest X rays were assessed in all examined workers. Also, complete blood counts were performed, and serum zinc, iron, copper, calcium, and magnesium levels were tested. This study illustrated the relation between zinc exposure in the galvanization process and high zinc levels among exposed workers, which was associated with a high prevalence rate of metal fume fever (MFF) and low blood copper and calcium levels. There was no statistically significant difference between the exposed and control groups with regards to the magnesium level. No long-term effect of metals exposure was detected on ventilatory functions or chest X rays among the exposed workers.

  7. Expectancy, False Galvanic Skin Response Feedback, and Systematic Desensitization in the Modification of Phobic Behavior

    Science.gov (United States)

    Lick, John

    1975-01-01

    This study compared systematic desensitization and two pseudotherapy manipulations with and without false galvanic skin response feedback after every session suggesting improvement in the modification of intense snake and spider fear. The results indicated no consistent differences between the three treatment groups. (Author)

  8. ENVIRONMENTAL AND ECONOMIC ASPECTS OF ANTICORROSION PROTECTION BY HOT-DIP GALVANIZED METHOD REBARS IN CONCRETE

    Directory of Open Access Journals (Sweden)

    Hegyi Andreea

    2015-05-01

    Full Text Available The implementation of the sustainable development concept is nowadays a key issue in almost all human activities. For the constructions domain an European strategy has already been elaborated. Among its goals are also the use of long lasting materials and the reduction of repair costs. This paper presents an interdisciplinary study concerning the efficiency of the use of hot-dip galvanized rebar for concrete structures. Experimental results about corrosion kinetics of coated and usual steel reinforcement embedded in concrete, subjected to chlorine ions attack, are analyzed. Electrochemical methods as chronoamperometry and linear polarization have been used. Corrosion potential values recorded for galvanized steel embedded in concrete indicate an uncertain corrosion activation process up to a rate of 2.5 % calcium chloride relative to concrete. For rates of 5% CaCl2 and more the corrosion process is activated. For unprotected steel bars embedded in concrete the corrosion activation process started at all calcium chloride studied rates and higher corrosion potential values has been registered than for the hot-dip galvanized ones, at the same rates. Economical assessments have been done using entire lifetime cost analysis of the reinforced concrete structures. Despite that the hotdip galvanization is a rather expansive procedure, when taking into account the whole expected life span, the use of zinc coating proves to be efficient both from structural and financial approaches.

  9. Cold metal transfer spot plug welding of AA6061-T6-to-galvanized steel for automotive applications

    International Nuclear Information System (INIS)

    Cao, R.; Huang, Q.; Chen, J.H.; Wang, Pei-Chung

    2014-01-01

    Highlights: • Two Al-to-galvanized steel spot plug welding joints were studied by CMT method. • The optimum process variables for the two joints were gotten by orthogonal test. • Connection mechanism of the two joints were discussed. -- Abstract: In this study, cold metal transfer (CMT) spot plug joining of 1 mm thick Al AA6061-T6 to 1 mm thick galvanized steel (i.e., Q235) was studied. Welding variables were optimized for a plug weld in the center of a 25 mm overlap region with aluminum 4043 wire and 100% argon shielding gas. Microstructures and elemental distributions were characterized by scanning electron microscopy with energy dispersive X-ray spectrometer. Mechanical testing of CMT spot plug welded joints was conducted. It was found that it is feasible to join Al AA6061T6-to-galvanized steel by CMT spot plug welding method. The process variables for two joints with Al AA6061T6-to-galvanized mild steel and galvanized mild steel-to-Al AA6061T6 are optimized. The strength of CMT spot welded Al AA6061T6-to-galvanized mild steel is determined primarily by the strength and area of the brazed interface. While, the strength of the galvanized mild steel-to-Al AA6061T6 joint is mainly dependent upon the area of the weld metal

  10. Effects of Mg on corrosion resistance of Al galvanically coupled to Fe

    International Nuclear Information System (INIS)

    Hyun, Youngmin; Kim, Heesan

    2013-01-01

    Effects of magnesium and pH on corrosion of aluminum galvanically coupled to iron have studied by using potentio- dynamic and static tests for polarization curves, Mott-Schottky test for analysis of semiconductor property, and GD-AES and XPS for film analysis. Pitting potential was sensitive to magnesium as an alloying element but not to pH, while passive current was sensitive to pH but not to magnesium. It was explained with, instead of point defect model (PDM), surface charge model describing that the ingression of chloride depends on the state of surface charge and passive film at film/solution interface is affected by pH. In addition, galvanic current of aluminum electrically coupled to iron was not affected by magnesium in pH 8.4, 0.2M citrate solution but was increased by magnesium at the solution of pH 9.1. The galvanic current at pH 9.1 increased with time at the initial stage and after the exposure of about 200 minute, decreased and stabilized. The behavior of the galvanic current was related with the concentration of magnesium at the surface. It agreed with the depletion of magnesium at the oxide surface by using glow discharge atomic emission spectroscopy (GD-AES). In addition, pitting potential of pure aluminum was reduced in neutral pH solution where chloride ion maybe are competitively adsorbed on pure aluminum. It was confirmed by the exponential decrease of pitting potential with log of [Cl - ] around 0.025 M of [Cl - ] and linear decrease of the pitting potential. From the above results, unlike magnesium, alloying elements with higher electron negativity, lowering isoelectric point (ISE), are recommended to be added to improve pitting corrosion resistance of aluminum and its alloys in neutral solutions as well as their galvanic corrosion resistance in weakly basic solutions

  11. Effects of Mg on corrosion resistance of Al galvanically coupled to Fe

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Youngmin; Kim, Heesan [Hongik Univ., Sejong (Korea, Republic of)

    2013-01-15

    Effects of magnesium and pH on corrosion of aluminum galvanically coupled to iron have studied by using potentio- dynamic and static tests for polarization curves, Mott-Schottky test for analysis of semiconductor property, and GD-AES and XPS for film analysis. Pitting potential was sensitive to magnesium as an alloying element but not to pH, while passive current was sensitive to pH but not to magnesium. It was explained with, instead of point defect model (PDM), surface charge model describing that the ingression of chloride depends on the state of surface charge and passive film at film/solution interface is affected by pH. In addition, galvanic current of aluminum electrically coupled to iron was not affected by magnesium in pH 8.4, 0.2M citrate solution but was increased by magnesium at the solution of pH 9.1. The galvanic current at pH 9.1 increased with time at the initial stage and after the exposure of about 200 minute, decreased and stabilized. The behavior of the galvanic current was related with the concentration of magnesium at the surface. It agreed with the depletion of magnesium at the oxide surface by using glow discharge atomic emission spectroscopy (GD-AES). In addition, pitting potential of pure aluminum was reduced in neutral pH solution where chloride ion maybe are competitively adsorbed on pure aluminum. It was confirmed by the exponential decrease of pitting potential with log of [Cl{sup -}] around 0.025 M of [Cl{sup -}] and linear decrease of the pitting potential. From the above results, unlike magnesium, alloying elements with higher electron negativity, lowering isoelectric point (ISE), are recommended to be added to improve pitting corrosion resistance of aluminum and its alloys in neutral solutions as well as their galvanic corrosion resistance in weakly basic solutions.

  12. Microbiologically influenced corrosion of galvanized steel by Desulfovibrio sp. and Desulfosporosinus sp. in the presence of Ag–Cu ions

    Energy Technology Data Exchange (ETDEWEB)

    Ilhan-Sungur, Esra, E-mail: esungur@istanbul.edu.tr [Istanbul University, Faculty of Science, Department of Biology, 34134 Vezneciler, Istanbul (Turkey); Unsal-Istek, Tuba [Istanbul University, Faculty of Science, Department of Biology, 34134 Vezneciler, Istanbul (Turkey); Cansever, Nurhan [Yıldız Technical University, Faculty of Chemistry-Metallurgy, Metallurgical and Materials Engineering Department, 34210 Esenler, Istanbul (Turkey)

    2015-07-15

    The effects of Ag–Cu ions on the microbiologically induced corrosion of galvanized steel in the presence of Desulfovibrio sp. and Desulfosporosinus sp. were investigated. The corrosion behavior of galvanized steel was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy. The biofilm, corrosion products and Ag–Cu ions on the surfaces were investigated by using scanning electron microscopy, energy dispersive X-ray spectrometry and elemental mapping. The biofilm layer formed by the Desulfovibrio sp. was stable covering the all surface of galvanized steel coupons, while that by Desulfosporosinus sp. was intermittent, highly porous and heterogeneous. It was found that both of the sulfate reducing bacteria species accelerated corrosion of the galvanized steel. However, it was detected that Desulfosporosinus sp. was more corrosive for galvanized steel than Desulfovibrio sp. Scanning electron microscopy images showed that Desulfovibrio sp. and Desulfosporosinus sp. in biofilm clustered into patches on the galvanized steel surface when the culture contained toxic Ag–Cu ions. The ions affected the growth of the sulfate reducing bacteria strains in different ways and hence the corrosion behaviors. It was observed that the Ag–Cu ions affected negatively growth of Desulfosporosinus sp. especially after 24 h of exposure leading to a decrease in the corrosion rate of galvanized steel. However, Desulfovibrio sp. showed more corrosive effect in the presence of the ions according to the ions-free culture. Energy dispersive X-ray spectrometry analysis showed that corrosion products on the surfaces were mainly composed of Zn, S, Na, O and P. - Highlights: • Galvanized steel was corroded by Desulfosporosinus sp. and Desulfovibrio sp. • Desulfosporosinus sp. is more corrosive than Desulfovibrio sp. • The Ag–Cu ions affected corrosion behavior of Desulfosporosinus sp. and Desulfovibrio sp. on galvanized steel.

  13. Microbiologically influenced corrosion of galvanized steel by Desulfovibrio sp. and Desulfosporosinus sp. in the presence of Ag–Cu ions

    International Nuclear Information System (INIS)

    Ilhan-Sungur, Esra; Unsal-Istek, Tuba; Cansever, Nurhan

    2015-01-01

    The effects of Ag–Cu ions on the microbiologically induced corrosion of galvanized steel in the presence of Desulfovibrio sp. and Desulfosporosinus sp. were investigated. The corrosion behavior of galvanized steel was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy. The biofilm, corrosion products and Ag–Cu ions on the surfaces were investigated by using scanning electron microscopy, energy dispersive X-ray spectrometry and elemental mapping. The biofilm layer formed by the Desulfovibrio sp. was stable covering the all surface of galvanized steel coupons, while that by Desulfosporosinus sp. was intermittent, highly porous and heterogeneous. It was found that both of the sulfate reducing bacteria species accelerated corrosion of the galvanized steel. However, it was detected that Desulfosporosinus sp. was more corrosive for galvanized steel than Desulfovibrio sp. Scanning electron microscopy images showed that Desulfovibrio sp. and Desulfosporosinus sp. in biofilm clustered into patches on the galvanized steel surface when the culture contained toxic Ag–Cu ions. The ions affected the growth of the sulfate reducing bacteria strains in different ways and hence the corrosion behaviors. It was observed that the Ag–Cu ions affected negatively growth of Desulfosporosinus sp. especially after 24 h of exposure leading to a decrease in the corrosion rate of galvanized steel. However, Desulfovibrio sp. showed more corrosive effect in the presence of the ions according to the ions-free culture. Energy dispersive X-ray spectrometry analysis showed that corrosion products on the surfaces were mainly composed of Zn, S, Na, O and P. - Highlights: • Galvanized steel was corroded by Desulfosporosinus sp. and Desulfovibrio sp. • Desulfosporosinus sp. is more corrosive than Desulfovibrio sp. • The Ag–Cu ions affected corrosion behavior of Desulfosporosinus sp. and Desulfovibrio sp. on galvanized steel

  14. Predictors of vertigo in patients with untreated vestibular schwannoma.

    Science.gov (United States)

    Andersen, Jan Fredrik; Nilsen, Kathrin Skorpa; Vassbotn, Flemming Slinning; Møller, Per; Myrseth, Erling; Lund-Johansen, Morten; Goplen, Frederik Kragerud

    2015-04-01

    Previous studies have shown that vertigo is the most powerful negative predictor of quality of life in patients with vestibular schwannomas, but the variability in vertigo symptom severity is still poorly understood. We wanted to find out whether vertigo could be related to objective parameters such as tumor size, location, vestibular nerve function, hearing, and postural stability in patients with untreated vestibular schwannomas. Baseline data from prospective cohort study. Tertiary referral center. Four hundred thirty-four consecutive patients with unilateral VS diagnosed on MRI. Mean age 56 years (range 16-84 yr). Fifty-three percent women. Diagnostic, with a medical history, otolaryngological examination, pure-tone and speech audiometry, MRI, posturography, and videonystagmography with bithermal caloric tests. Dizziness measured on a 100-mm visual analog scale (VAS). Secondary outcome measures were canal paresis and postural imbalance (static and dynamic posturography). Three hundred three patients (70%) completed the VAS. Severe dizziness, defined as VAS 75 or greater, was reported by 9% of the patients. Larger tumors were associated with higher risk of postural instability and canal paresis. Moderate to severe dizziness was associated with postural imbalance and canal paresis, and possibly with small to medium-sized tumors. Postural instability was related to tumor size and canal paresis when measured by dynamic, but not with static, posturography. A minority of VS patients experience severe vestibular symptoms related to canal paresis and postural instability. A curvilinear relationship is hypothesized between tumor size and dizziness.

  15. Task-dependent vestibular feedback responses in reaching

    NARCIS (Netherlands)

    Keyser, J.; Medendorp, W.P.; Selen, L.P.J.

    2017-01-01

    When reaching for an earth-fixed object during self-rotation, the motor system should appropriately integrate vestibular signals and sensory predictions to compensate for the intervening motion and its induced inertial forces. While it is well established that this integration occurs rapidly, it is

  16. Medial vestibular connections with the hypocretin (orexin) system

    Science.gov (United States)

    Horowitz, Seth S.; Blanchard, Jane; Morin, Lawrence P.

    2005-01-01

    The mammalian medial vestibular nucleus (MVe) receives input from all vestibular endorgans and provides extensive projections to the central nervous system. Recent studies have demonstrated projections from the MVe to the circadian rhythm system. In addition, there are known projections from the MVe to regions considered to be involved in sleep and arousal. In this study, afferent and efferent subcortical connectivity of the medial vestibular nucleus of the golden hamster (Mesocricetus auratus) was evaluated using cholera toxin subunit-B (retrograde), Phaseolus vulgaris leucoagglutinin (anterograde), and pseudorabies virus (transneuronal retrograde) tract-tracing techniques. The results demonstrate MVe connections with regions mediating visuomotor and postural control, as previously observed in other mammals. The data also identify extensive projections from the MVe to regions mediating arousal and sleep-related functions, most of which receive immunohistochemically identified projections from the lateral hypothalamic hypocretin (orexin) neurons. These include the locus coeruleus, dorsal and pedunculopontine tegmental nuclei, dorsal raphe, and lateral preoptic area. The MVe itself receives a projection from hypocretin cells. CTB tracing demonstrated reciprocal connections between the MVe and most brain areas receiving MVe efferents. Virus tracing confirmed and extended the MVe afferent connections identified with CTB and additionally demonstrated transneuronal connectivity with the suprachiasmatic nucleus and the medial habenular nucleus. These anatomical data indicate that the vestibular system has access to a broad array of neural functions not typically associated with visuomotor, balance, or equilibrium, and that the MVe is likely to receive information from many of the same regions to which it projects.

  17. Bilateral Vestibular Deficiency: Quality of Life and Economic Implications.

    Science.gov (United States)

    Sun, Daniel Q; Ward, Bryan K; Semenov, Yevgeniy R; Carey, John P; Della Santina, Charles C

    2014-06-01

    Bilateral vestibular deficiency (BVD) causes chronic imbalance and unsteady vision and greatly increases the risk of falls; however, its effects on quality of life and economic impact are not well defined. To quantify disease-specific and health-related quality of life, health care utilization, and economic impact on individuals with BVD in comparison with those with unilateral vestibular deficiency (UVD). Cross-sectional survey study of patients with BVD or UVD and healthy controls at an academic medical center. Vestibular dysfunction was diagnosed by means of caloric nystagmography. Survey questionnaire. Health status was measured using the Dizziness Handicap Index (DHI) and Health Utility Index Mark 3 (HUI3). Economic burden was estimated using participant responses to questions on disease-specific health care utilization and lost productivity. Fifteen patients with BVD, 22 with UVD, and 23 healthy controls participated. In comparison with patients with UVD and controls, patients with BVD had significantly worse DHI (P work days (P life and imposes substantial economic burdens on individuals and society. These results underscore the limits of adaptation and compensation in BVD. Furthermore, they quantify the potential benefits of prosthetic restoration of vestibular function both to these individuals and to society.

  18. Normalization reduces intersubject variability in cervical vestibular evoked myogenic potentials.

    Science.gov (United States)

    van Tilburg, Mark J; Herrmann, Barbara S; Guinan, John J; Rauch, Steven D

    2014-09-01

    Cervical vestibular evoked myogenic potentials are used to assess saccular and inferior vestibular nerve function. Normalization of the VEMP waveform has been proposed to reduce the variability in vestibular evoked myogenic potentials by correcting for muscle activation. In this study, we test the hypothesis that normalization of the raw cervical VEMP waveform causes a significant decrease in the intersubject variability. Prospective cohort study. Large specialty hospital, department of otolaryngology. Twenty healthy subjects were used in this study. All subjects underwent cervical vestibular evoked myogenic potential testing using short tone bursts at 250, 500, 750, and 1,000 Hz. Both intersubject and intrasubject variability was assessed. Variability between raw and normalized peak-to-peak amplitudes was compared using the coefficient of variation. Intrasubject variability was assessed using the intraclass correlation coefficient and interaural asymmetry ratio. cVEMPs were present in most ears. Highest peak-to-peak amplitudes were recorded at 750 Hz. Normalization did not alter cVEMP tuning characteristics. Normalization of the cVEMP response caused a significant reduction in intersubject variability of the peak-to-peak amplitude. No significant change was seen in the intrasubject variability. Normalization significantly reduces cVEMP intersubject variability in healthy subjects without altering cVEMP characteristics. By reducing cVEMP amplitude variation due to nonsaccular, muscle-related factors, cVEMP normalization is expected to improve the ability to distinguish between healthy and pathologic responses in the clinical application of cVEMP testing.

  19. Current concepts and future approaches to vestibular rehabilitation.

    Science.gov (United States)

    Tjernström, Fredrik; Zur, Oz; Jahn, Klaus

    2016-04-01

    Over the last decades methods of vestibular rehabilitation to enhance adaptation to vestibular loss, habituation to changing sensory conditions, and sensory reweighting in the compensation process have been developed. However, the use of these techniques still depends to a large part on the educational background of the therapist. Individualized assessment of deficits and specific therapeutic programs for different disorders are sparse. Currently, vestibular rehabilitation is often used in an unspecific way in dizzy patients irrespective of the clinical findings. When predicting the future of vestibular rehabilitation, it is tempting to foretell advances in technology for assessment and treatment only, but the current intense exchange between clinicians and basic scientists also predicts advances in truly understanding the complex interactions between the peripheral senses and central adaptation mechanisms. More research is needed to develop reliable techniques to measure sensory dependence and to learn how this knowledge can be best used--by playing off the patient's sensory strength or working on the weakness. To be able using the emerging concepts, the neuro-otological community must strive to educate physicians, physiotherapists and nurses to perform the correct examinations for assessment of individual deficits and to look for factors that might impede rehabilitation.

  20. Comparative analysis of vestibular ecomorphology in birds.

    Science.gov (United States)

    Benson, Roger B J; Starmer-Jones, Ethan; Close, Roger A; Walsh, Stig A

    2017-12-01

    The bony labyrinth of vertebrates houses the semicircular canals. These sense rotational accelerations of the head and play an essential role in gaze stabilisation during locomotion. The sizes and shapes of the semicircular canals have hypothesised relationships to agility and locomotory modes in many groups, including birds, and a burgeoning palaeontological literature seeks to make ecological interpretations from the morphology of the labyrinth in extinct species. Rigorous tests of form-function relationships for the vestibular system are required to support these interpretations. We test the hypothesis that the lengths, streamlines and angles between the semicircular canals are related to body size, wing kinematics and flying style in birds. To do this, we applied geometric morphometrics and multivariate phylogenetic comparative methods to a dataset of 64 three-dimensional reconstructions of the endosseous labyrinth obtained using micro-computed tomography scanning of bird crania. A strong relationship between centroid size of the semicircular canals and body size indicates that larger birds have longer semicircular canals compared with their evolutionary relatives. Wing kinematics related to manoeuvrability (and quantified using the brachial index) explain a small additional portion of the variance in labyrinth size. We also find strong evidence for allometric shape change in the semicircular canals of birds, indicating that major aspects of the shape of the avian labyrinth are determined by spatial constraints. The avian braincase accommodates a large brain, a large eye and large semicircular canals compared with other tetrapods. Negative allometry of these structures means that the restriction of space within the braincase is intense in small birds. This may explain our observation that the angles between planes of the semicircular canals of birds deviate more strongly from orthogonality than those of mammals, and especially from agile, gliding and flying

  1. Vestibular factors influencing the biomedical support of humans in space.

    Science.gov (United States)

    Lichtenberg, B K

    1988-01-01

    This paper will describe the biomedical support aspects of humans in space with respect to the vestibular system. The vestibular system is thought to be the primary sensory system involved in the short-term effects of space motion sickness although there is increasing evidence that many factors play a role in this complex set of symptoms. There is the possibility that an individual's inner sense of orientation may be strongly coupled with the susceptibility to space motion sickness. A variety of suggested countermeasures for space motion sickness will be described. Although there are no known ground-based tests that can predict space motion sickness, the search should go on. The long term effects of the vestibular system in weightlessness are still relatively unknown. Some preliminary data has shown that the otoconia are irregular in size and distribution following extended periods of weightlessness. The ramifications of this data are not yet known and because the data was obtained on lower order animals, definitive studies and results must wait until the space station era when higher primates can be studied for long durations. This leads us to artificial gravity, the last topic of this paper. The vestibular system is intimately tied to this question since it has been shown on Earth that exposure to a slow rotating room causes motion sickness for some period of time before adaptation occurs. If the artificial gravity is intermittent, will this mean that people will get sick every time they experience it? The data from many astronauts returning to Earth indicates that a variety of sensory illusions are present, especially immediately upon return to a 1-g environment. Oscillopsia or apparent motion of the visual surround upon head motion along with inappropriate eye motions for a given head motion, all indicate that there is much to be studied yet about the vestibular and CNS systems reaction to a sudden application of a steady state acceleration field like 1-g. From

  2. Photo-electrochemical Investigation of Radiation-Enhanced Galvanic Coupling and Hydrogen Permeation in TPBAR-related Materials

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-02

    Research conducted in FY17 used photo-electrochemical methods to investigate the potential for radiationenhanced galvanic coupling in tritium-producing burnable absorber rod (TPBAR) materials. Specifically, a laboratory electrochemical cell was coupled with UV light in order to perform electrochemical opencircuit voltage and galvanic current measurements, techniques that have been used successfully in previous studies to replicate galvanic processes in reactor settings. UV irradiation can mimic reactor-like behavior because, similar to both directly and indirectly ionizing radiation, UV photons with energy greater than the band gap of the material will generate free charge carriers (electrons and holes) and can substantially alter the passivating effect of metal oxides.

  3. Photo-electrochemical Investigation of Radiation-Enhanced Galvanic Coupling and Hydrogen Permeation in TPBAR-related Materials

    International Nuclear Information System (INIS)

    Larsen, G.

    2017-01-01

    Research conducted in FY17 used photo-electrochemical methods to investigate the potential for radiationenhanced galvanic coupling in tritium-producing burnable absorber rod (TPBAR) materials. Specifically, a laboratory electrochemical cell was coupled with UV light in order to perform electrochemical opencircuit voltage and galvanic current measurements, techniques that have been used successfully in previous studies to replicate galvanic processes in reactor settings. UV irradiation can mimic reactor-like behavior because, similar to both directly and indirectly ionizing radiation, UV photons with energy greater than the band gap of the material will generate free charge carriers (electrons and holes) and can substantially alter the passivating effect of metal oxides.

  4. Microstructure and failure behavior of dissimilar resistance spot welds between low carbon galvanized and austenitic stainless steels

    International Nuclear Information System (INIS)

    Marashi, P.; Pouranvari, M.; Amirabdollahian, S.; Abedi, A.; Goodarzi, M.

    2008-01-01

    Resistance spot welding was used to join austenitic stainless steel and galvanized low carbon steel. The relationship between failure mode and weld fusion zone characteristics (size and microstructure) was studied. It was found that spot weld strength in the pullout failure mode is controlled by the strength and fusion zone size of the galvanized steel side. The hardness of the fusion zone which is governed by the dilution between two base metals, and fusion zone size of galvanized carbon steel side are dominant factors in determining the failure mode

  5. Prediction of Balance Compensation After Vestibular Schwannoma Surgery.

    Science.gov (United States)

    Parietti-Winkler, Cécile; Lion, Alexis; Frère, Julien; Perrin, Philippe P; Beurton, Renaud; Gauchard, Gérome C

    2016-06-01

    Background Balance compensation after vestibular schwannoma (VS) surgery is under the influence of specific preoperative patient and tumor characteristics. Objective To prospectively identify potential prognostic factors for balance recovery, we compared the respective influence of these preoperative characteristics on balance compensation after VS surgery. Methods In 50 patients scheduled for VS surgical ablation, we measured postural control before surgery (BS), 8 (AS8) days after, and 90 (AS90) days after surgery. Based on factors found previously in the literature, we evaluated age, body mass index and preoperative physical activity (PA), tumor grade, vestibular status, and preference for visual cues to control balance as potential prognostic factors using stepwise multiple regression models. Results An asymmetric vestibular function was the sole significant explanatory factor for impaired balance performance BS, whereas the preoperative PA alone significantly contributed to higher performance at AS8. An evaluation of patients' balance recovery over time showed that PA and vestibular status were the 2 significant predictive factors for short-term postural compensation (BS to AS8), whereas none of these preoperative factors was significantly predictive for medium-term postoperative postural recovery (AS8 to AS90). Conclusions We identified specific preoperative patient and vestibular function characteristics that may predict postoperative balance recovery after VS surgery. Better preoperative characterization of these factors in each patient could inform more personalized presurgical and postsurgical management, leading to a better, more rapid balance recovery, earlier return to normal daily activities and work, improved quality of life, and reduced medical and societal costs. © The Author(s) 2015.

  6. Ocular vestibular evoked myogenic potential elicited from binaural air-conducted stimulations: clinical feasibility in patients with peripheral vestibular dysfunction.

    Science.gov (United States)

    Iwasaki, Shinichi; Egami, Naoya; Inoue, Aki; Kinoshita, Makoto; Fujimoto, Chisato; Murofushi, Toshihisa; Yamasoba, Tatsuya

    2013-07-01

    Ocular vestibular evoked myogenic potentials (oVEMPs) to binaural air-conducted stimulation (ACS) may provide a convenient way of assessing the crossed vestibulo-ocular reflex in patients with vestibular dysfunction as well as in healthy subjects. To investigate the clinical feasibility of using oVEMPs in response to binaural ACS to assess normal subjects and patients with vestibular dysfunction. The study investigated 24 normal subjects (14 men and 10 women, aged from 23 to 60 years) and 14 patients with unilateral peripheral vestibular dysfunction. Each subject underwent oVEMP testing in response to monaural ACS and binaural ACS (500 Hz tone burst, 135 dBSPL). In normal subjects, bilateral oVEMPs were elicited in 75% of subjects in response to monaural ACS and in 91% in response to binaural ACS. Asymmetry ratios (ARs) of the responses to binaural ACS were significantly smaller than those of the responses to monaural ACS (p binaural ACS. Approximately 30% of patients showed reduced ARs to binaural ACS relative to monaural ACS, primarily due to contamination by uncrossed responses elicited in healthy ears.

  7. Refractory episodic vertigo: role of intratympanic gentamicin and vestibular evoked myogenic potentials,

    Directory of Open Access Journals (Sweden)

    Erika Celis-Aguilar

    Full Text Available Abstract Introduction: Even today, the treatment of intractable vertigo remains a challenge. Vestibular ablation with intratympanic gentamicin stands as a good alternative in the management of refractory vertigo patients. Objective: To control intractable vertigo through complete saccular and horizontal canal vestibular ablation with intratympanic gentamicin treatment. Methods: Patients with refractory episodic vertigo were included. The inclusion criteria were: unilateral ear disease, moderate to profound sensorineural hearing loss, and failure to other treatments. Included patients underwent 0.5-0.8 mL of gentamicin intratympanic application at a 30 mg/mL concentration. Vestibular ablation was confirmed by the absence of response on cervical vestibular evoked myogenic potentials and no response on caloric tests. Audiometry, electronystagmography with iced water, and vestibular evoked myogenic potentials were performed in all patients. Results: Ten patients were included; nine patients with Meniere's disease and one patient with (late onset delayed hydrops. Nine patients showed an absent response on vestibular evoked myogenic potentials and no response on caloric tests. The only patient with low amplitude on cervical vestibular evoked myogenic potentials had vertigo recurrence. Vertigo control was achieved in 90% of the patients. One patient developed hearing loss >30 dB. Conclusions: Cervical vestibular evoked myogenic potentials confirmed vestibular ablation in patients treated with intratympanic gentamicin. High-grade vertigo control was due to complete saccular and horizontal canal ablation (no response to iced water in electronystagmography and no response on cervical vestibular evoked myogenic potentials.

  8. The two dynamical states in sinusoidal potentials: An analog simulation experiment

    Science.gov (United States)

    Sawkmie, Ivan Skhem; Mahato, Mangal C.

    2018-04-01

    The phenomenon of stochastic resonance (SR) is usually found to occur theoretically as well as experimentally in bi-stable systems [1]. Recently, it was numerically shown that SR is found to occur in underdamped (friction coefficient γ) sinusoidal potentials also. The occurrence of SR is explained in terms of two competing dynamical states of trajectories as a response to the external periodic drive. We setup an analog simulation experiment similar to the analog simulation work done earlier to study stochastic nonlinear dynamics [2], to verify the existence of the two dynamical states and to investigate the occurrence of SR in sinusoidal potentials obtained earlier [3]. We discuss our experimental setup and the results obtained in detail.

  9. Compact broadband polarization beam splitter using a symmetric directional coupler with sinusoidal bends.

    Science.gov (United States)

    Zhang, Fan; Yun, Han; Wang, Yun; Lu, Zeqin; Chrostowski, Lukas; Jaeger, Nicolas A F

    2017-01-15

    We design and demonstrate a compact broadband polarization beam splitter (PBS) using a symmetric directional coupler with sinusoidal bends on a silicon-on-insulator platform. The sinusoidal bends in our PBS suppress the power exchange between two parallel symmetric strip waveguides for the transverse-electric (TE) mode, while allowing for the maximum power transfer to the adjacent waveguide for the transverse-magnetic (TM) mode. Our PBS has a nominal coupler length of 8.55 μm, and it has an average extinction ratio (ER) of 12.0 dB for the TE mode, an average ER of 20.1 dB for the TM mode, an average polarization isolation (PI) of 20.6 dB for the through port, and an average PI of 11.5 dB for the cross port, all over a bandwidth of 100 nm.

  10. Levitation performance of high-T{sub c} superconductor in sinusoidal guideway magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu 610031 (China)], E-mail: asclab@asclab.cn; Wang, J.S.; Jing, H.; Jiang, M.; Zheng, J.; Wang, S.Y. [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu 610031 (China)

    2008-12-01

    The vertical component of the Halbach array's magnetic field exhibits a sinusoid distribution because of the closed magnetic flux area between two neighbouring poles, so this field can be regarded as the sinusoidal magnetic field. This article mainly discusses the influence of the closed flux region on the levitation performance of the bulk high-temperature superconductor (HTS). Moreover, the levitation performance is compared between the closed and diverging region of magnetic flux. The experimental results can be analyzed by the magnetic circuit theory and the frozen-image model. The analysis indicates that the closed region of magnetic flux can influence the levitation performance of bulk HTS obviously and provide an extra useful guidance force. These conclusions are helpful to optimize the HTS Maglev system.

  11. New Results on Single-Channel Speech Separation Using Sinusoidal Modeling

    DEFF Research Database (Denmark)

    Mowlaee, Pejman; Christensen, Mads Græsbøll; Jensen, Søren Holdt

    2011-01-01

    We present new results on single-channel speech separation and suggest a new separation approach to improve the speech quality of separated signals from an observed mix- ture. The key idea is to derive a mixture estimator based on sinusoidal parameters. The proposed estimator is aimed at finding...... mixture estimator used in binary masks and the Wiener filtering approach, it is observed that the proposed method achieves an acceptable perceptual speech quality with less cross- talk at different signal-to-signal ratios. Moreover, the method is independent of pitch estimates and reduces the computational...... complexity of the separation by replacing the short-time Fourier transform (STFT) feature vectors of high dimensionality with sinusoidal feature vectors. We report separation results for the proposed method and compare them with respect to other benchmark methods. The improvements made by applying...

  12. [Defibrotide therapy for patients with sinusoidal obstruction syndrome after hematopoietic stem cell transplantation].

    Science.gov (United States)

    Yakushijin, Kimikazu; Okamura, Atsuo; Ono, Kanako; Kawano, Yuko; Kawano, Hiroki; Funakoshi, Yohei; Kawamori, Yuriko; Nishikawa, Shinichiro; Minagawa, Kentaro; Sada, Akiko; Shimoyama, Manabu; Yamamoto, Katsuya; Katayama, Yoshio; Matsui, Toshimitsu

    2009-01-01

    Sinusoidal obstruction syndrome (SOS) is one of the life-threatening complications caused by endothelial damage to the hepatic sinusoids after hematopoietic stem cell transplantation. However, a satisfactory treatment for SOS has not yet been established. Defibrotide has anti-thrombotic, anti-ischemic, anti-inflammatory, and thrombolytic properties without systemic anticoagulant effects. We treated eight post-transplant SOS patients with defibrotide. Three patients responded to the therapy and the initial response was observed within a week. In addition to the improvement of liver function, rapid recovery of response to diuretic drugs followed by the improvement of renal function was observed. All of the five patients with respiratory dysfunction died despite administration of defibrotide, suggesting that early treatment might lead to better outcomes. There were no severe adverse effects directly due to defibrotide administration. Defibrotide seems to be a promising treatment for SOS, and the initiation of a clinical study in Japan would be important.

  13. CFD study on NACA 4415 airfoil implementing spherical and sinusoidal Tubercle Leading Edge.

    Science.gov (United States)

    Aftab, S M A; Ahmad, K A

    2017-01-01

    The Humpback whale tubercles have been studied for more than a decade. Tubercle Leading Edge (TLE) effectively reduces the separation bubble size and helps in delaying stall. They are very effective in case of low Reynolds number flows. The current Computational Fluid Dynamics (CFD) study is on NACA 4415 airfoil, at a Reynolds number 120,000. Two TLE shapes are tested on NACA 4415 airfoil. The tubercle designs implemented on the airfoil are sinusoidal and spherical. A parametric study is also carried out considering three amplitudes (0.025c, 0.05c and 0.075c), the wavelength (0.25c) is fixed. Structured mesh is utilized to generate grid and Transition SST turbulence model is used to capture the flow physics. Results clearly show spherical tubercles outperform sinusoidal tubercles. Furthermore experimental study considering spherical TLE is carried out at Reynolds number 200,000. The experimental results show that spherical TLE improve performance compared to clean airfoil.

  14. Flow and heat transfer characteristics in a channel having furrowed wall based on sinusoidal wave

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiansheng; Gao, Xiaoming; Li, Weiyi [Tianjin University, Tianjin (Switzerland)

    2015-11-15

    The effect of wall geometry on the flow and heat transfer in a channel with one lower furrowed and an upper flat wall kept at a uniform temperature is investigated by large eddy simulation. Three channels, one with sinusoidal wavy surface having the ratio (amplitude to wavelength) α/λ=0.05 and the other two with furrowed surface derived from the sinusoidal curve, are considered. The numerical results show that the streamwise vortices center is located near the lower wall and vary along the streamwise on various furrow surfaces. The furrow geometry increases the pressure drag and decreases the friction drag of the furrowed surface compared with that of the smooth surface; consequently, the total drag is increased for the augment of pressure drag. As expected, the heat transfer performance has been improved. Finally, a thermal performance factor is defined to evaluate the performance of the furrowed wall.

  15. Characterization of Cochlear, Vestibular and Cochlear-Vestibular Electrically Evoked Compound Action Potentials in Patients with a Vestibulo-Cochlear Implant

    Directory of Open Access Journals (Sweden)

    T. A. K. Nguyen

    2017-11-01

    Full Text Available The peripheral vestibular system is critical for the execution of activities of daily life as it provides movement and orientation information to motor and sensory systems. Patients with bilateral vestibular hypofunction experience a significant decrease in quality of life and have currently no viable treatment option. Vestibular implants could eventually restore vestibular function. Most vestibular implant prototypes to date are modified cochlear implants to fast-track development. These use various objective measurements, such as the electrically evoked compound action potential (eCAP, to supplement behavioral information. We investigated whether eCAPs could be recorded in patients with a vestibulo-cochlear implant. Specifically, eCAPs were successfully recorded for cochlear and vestibular setups, as well as for mixed cochlear-vestibular setups. Similarities and slight differences were found for the recordings of the three setups. These findings demonstrated the feasibility of eCAP recording with a vestibulo-cochlear implant. They could be used in the short term to reduce current spread and avoid activation of non-targeted neurons. More research is warranted to better understand the neural origin of vestibular eCAPs and to utilize them for clinical applications.

  16. Realization of Electronically Tunable Current- Mode Multiphase Sinusoidal Oscillators Using CFTAs

    OpenAIRE

    Prungsak Uttaphut

    2012-01-01

    An implementation of current-mode multiphase sinusoidal oscillators is presented. Using CFTA-based lossy integrators, odd and odd/even phase systems can be realized with following advantages. The condition of oscillation and frequency of oscillation can be orthogonally tuned. The high output impedances facilitate easy driving an external load without additional current buffers. The proposed MSOs provide odd or even phase signals that are equally spaced in phase and equal amplitude. The circui...

  17. Highly enhanced avalanche probability using sinusoidally-gated silicon avalanche photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Shingo; Namekata, Naoto, E-mail: nnao@phys.cst.nihon-u.ac.jp; Inoue, Shuichiro [Institute of Quantum Science, Nihon University, 1-8-14 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Tsujino, Kenji [Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan)

    2014-01-27

    We report on visible light single photon detection using a sinusoidally-gated silicon avalanche photodiode. Detection efficiency of 70.6% was achieved at a wavelength of 520 nm when an electrically cooled silicon avalanche photodiode with a quantum efficiency of 72.4% was used, which implies that a photo-excited single charge carrier in a silicon avalanche photodiode can trigger a detectable avalanche (charge) signal with a probability of 97.6%.

  18. [The sequential use of local vacuum magnetotherapy and papaverine electrophoresis with sinusoidal modulated currents in impotence].

    Science.gov (United States)

    Karpukhin, I V; Bogomol'nyĭ, V A

    1997-01-01

    105 patients with chronic nonspecific prostatitis were examined and treated with papaverin electrophoresis using sinusoidal modulated currents (SMC) and local vacuum magnetotherapy (LVMT). Papaverin SMC electrophoresis and LVMT stimulated cavernous circulation. The highest stimulation was achieved at successive use of LVMT and the electrophoresis. LVMT followed by the electrophoresis maintained good cavernous circulation for 5-6 hours after the procedure in the course of which several spontaneous erections were observed.

  19. Visual-vestibular integration motion perception reporting

    Science.gov (United States)

    Harm, Deborah L.; Reschke, Millard R.; Parker, Donald E.

    1999-01-01

    Self-orientation and self/surround-motion perception derive from a multimodal sensory process that integrates information from the eyes, vestibular apparatus, proprioceptive and somatosensory receptors. Results from short and long duration spaceflight investigations indicate that: (1) perceptual and sensorimotor function was disrupted during the initial exposure to microgravity and gradually improved over hours to days (individuals adapt), (2) the presence and/or absence of information from different sensory modalities differentially affected the perception of orientation, self-motion and surround-motion, (3) perceptual and sensorimotor function was initially disrupted upon return to Earth-normal gravity and gradually recovered to preflight levels (individuals readapt), and (4) the longer the exposure to microgravity, the more complete the adaptation, the more profound the postflight disturbances, and the longer the recovery period to preflight levels. While much has been learned about perceptual and sensorimotor reactions and adaptation to microgravity, there is much remaining to be learned about the mechanisms underlying the adaptive changes, and about how intersensory interactions affect perceptual and sensorimotor function during voluntary movements. During space flight, SMS and perceptual disturbances have led to reductions in performance efficiency and sense of well-being. During entry and immediately after landing, such disturbances could have a serious impact on the ability of the commander to land the Orbiter and on the ability of all crew members to egress from the Orbiter, particularly in a non-nominal condition or following extended stays in microgravity. An understanding of spatial orientation and motion perception is essential for developing countermeasures for Space Motion Sickness (SMS) and perceptual disturbances during spaceflight and upon return to Earth. Countermeasures for optimal performance in flight and a successful return to Earth require

  20. Core losses of a permanent magnet synchronous motor with an amorphous stator core under inverter and sinusoidal excitations

    Science.gov (United States)

    Yao, Atsushi; Sugimoto, Takaya; Odawara, Shunya; Fujisaki, Keisuke

    2018-05-01

    We report core loss properties of permanent magnet synchronous motors (PMSM) with amorphous magnetic materials (AMM) core under inverter and sinusoidal excitations. To discuss the core loss properties of AMM core, a comparison with non-oriented (NO) core is also performed. In addition, based on both experiments and numerical simulations, we estimate higher (time and space) harmonic components of the core losses under inverter and sinusoidal excitations. The core losses of PMSM are reduced by about 59% using AMM stator core instead of NO core under sinusoidal excitation. We show that the average decrease obtained by using AMM instead of NO in the stator core is about 94% in time harmonic components.