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Sample records for horizontal semicircular canal

  1. Changes in monkey horizontal semicircular canal afferent responses after spaceflight

    NASA Technical Reports Server (NTRS)

    Correia, M. J.; Perachio, A. A.; Dickman, J. D.; Kozlovskaia, I. B.; Sirota, M. G.; Iakushin, S. B.; Beloozerova, I. N.

    1992-01-01

    Extracellular responses from single horizontal semicircular canal afferents in two rhesus monkeys were studied after recovery from a 14-day biosatellite (Cosmos 2044) orbital spaceflight. On the 1st postflight day, the mean gain for 9 different horizontal canal afferents, tested using one or several different passive yaw rotation waveforms, was nearly twice that for 20 horizontal canal afferents similarly tested during preflight and postflight control studies. Adaptation of the afferent response to passive yaw rotation on the 1st postflight day was also greater. These results suggest that at least one component of the vestibular end organ (the semicircular canals) is transiently modified after exposure to 14 days of microgravity. It is unclear whether the changes are secondary to other effects of microgravity, such as calcium loss, or an adaptive response. If the response is adaptive, then this report is the first evidence that the response of the vestibular end organ may be modified (presumably by the central nervous system via efferent connections) after prolonged unusual vestibular stimulation. If this is the case, the sites of plasticity of vestibular responses may not be exclusively within central nervous system vestibular structures, as previously believed.

  2. The Semicircular Canal Microphonic

    NASA Technical Reports Server (NTRS)

    Rabbitt, R. D.; Boyle, R.; Highstein, S. M.; Dalton, Bonnie P. (Technical Monitor)

    2002-01-01

    Present experiments were designed to quantify the alternating current (AC) component of the semicircular canal microphonic for angular motion stimulation as a function of stimulus frequency and amplitude. The oyster toadfish, Opsanus tau, was used as the experimental model. Calibrated mechanical indentation of the horizontal canal duct was used as a stimulus to generate hair-cell and afferent responses reproducing those present during head rotation. Sensitivity to polarization of the endolymph DC voltage re: perilymph was also investigated. Modulation of endolymph voltage was recorded using conventional glass electrodes and lock-in amplification over the frequency range 0.2-80 Hz. Access to the endolymph for inserting voltage recording and current passing electrodes was obtained by sectioning the anterior canal at its apex and isolating the cut ends in air. For sinusoidal stimulation below approx.10 Hz, the horizontal semicircular canal AC microphonic was nearly independent of stimulus frequency and equal to approximately 4 microV per micron indent (equivalent to approx. 1 microV per deg/s). A saturating nonlinearity decreasing the microphonic gain was present for stimuli exceeding approx.3 micron indent (approx. 12 deg/s angular velocity). The phase was not sensitive to the saturating nonlinearity. The microphonic exhibited a resonance near 30Hz consistent with basolateral current hair cell resonance observed previously in voltage-clamp records from semicircular canal hair cells. The magnitude and phase of the microphonic exhibited sensitivity to endolymphatic polarization consistent with electro-chemical reversal of hair cell transduction currents.

  3. Head Direction Cell Activity Is Absent in Mice without the Horizontal Semicircular Canals.

    PubMed

    Valerio, Stephane; Taube, Jeffrey S

    2016-01-20

    Head direction (HD) cells fire when an animal faces a particular direction in its environment, and they are thought to represent the neural correlate of the animal's perceived spatial orientation. Previous studies have shown that vestibular information is critical for generating the HD signal but have not delineated whether information from all three semicircular canals or just the horizontal canals, which are primarily sensitive to angular head rotation in the horizontal (yaw) plane, are critical for the signal. Here, we monitored cell activity in the anterodorsal thalamus (ADN), an area known to contain HD cells, in epstatic circler (Ecl) mice, which have a bilateral malformation of the horizontal (lateral) semicircular canals. Ecl mice and their littermates that did not express the mutation (controls) were implanted with recording electrodes in the ADN. Results confirm the important role the horizontal canals play in forming the HD signal. Although normal HD cell activity (Raleigh's r > 0.4) was recorded in control mice, no such activity was found in Ecl mice, although some cells had activity that was mildly modulated by HD (0.4 > r > 0.2). Importantly, we also observed activity in Ecl mice that was best characterized as bursty--a pattern of activity similar to an HD signal but without any preferred firing direction. These results suggest that the neural structure for the HD network remains intact in Ecl mice, but the absence of normal horizontal canals results in an inability to control the network properly and brings about an unstable HD signal. Significance statement: Cells in the anterior dorsal thalamic nucleus normally fire in relation to the animal's directional heading with respect to the environment--so-called head direction cells. To understand how these head direction cells generate their activity, we recorded single-unit activity from the anterior dorsal thalamus in transgenic mice that lack functional horizontal semicircular canals. We show that the

  4. Head Direction Cell Activity Is Absent in Mice without the Horizontal Semicircular Canals

    PubMed Central

    Valerio, Stephane

    2016-01-01

    Head direction (HD) cells fire when an animal faces a particular direction in its environment, and they are thought to represent the neural correlate of the animal's perceived spatial orientation. Previous studies have shown that vestibular information is critical for generating the HD signal but have not delineated whether information from all three semicircular canals or just the horizontal canals, which are primarily sensitive to angular head rotation in the horizontal (yaw) plane, are critical for the signal. Here, we monitored cell activity in the anterodorsal thalamus (ADN), an area known to contain HD cells, in epstatic circler (Ecl) mice, which have a bilateral malformation of the horizontal (lateral) semicircular canals. Ecl mice and their littermates that did not express the mutation (controls) were implanted with recording electrodes in the ADN. Results confirm the important role the horizontal canals play in forming the HD signal. Although normal HD cell activity (Raleigh's r > 0.4) was recorded in control mice, no such activity was found in Ecl mice, although some cells had activity that was mildly modulated by HD (0.4 > r > 0.2). Importantly, we also observed activity in Ecl mice that was best characterized as bursty—a pattern of activity similar to an HD signal but without any preferred firing direction. These results suggest that the neural structure for the HD network remains intact in Ecl mice, but the absence of normal horizontal canals results in an inability to control the network properly and brings about an unstable HD signal. SIGNIFICANCE STATEMENT Cells in the anterior dorsal thalamic nucleus normally fire in relation to the animal's directional heading with respect to the environment—so-called head direction cells. To understand how these head direction cells generate their activity, we recorded single-unit activity from the anterior dorsal thalamus in transgenic mice that lack functional horizontal semicircular canals. We show that

  5. Preserved otolith organ function in caspase-3 deficient mice with impaired horizontal semicircular canal function

    PubMed Central

    Armstrong, Patrick A; Wood, Scott J; Shimizu, Naoki; Kuster, Kael; Perachio, Adrian; Makishima, Tomoko

    2015-01-01

    Genetically engineered mice are valuable models for elucidation of auditory and vestibular pathology. Our goal was to establish a comprehensive vestibular function testing system in mice using: 1) horizontal angular vestibular-ocular reflex (hVOR) to evaluate semicircular canal function, and 2) otolith-ocular reflex (OOR) to evaluate otolith organ function, and to validate the system by characterizing mice with vestibular dysfunction. We used pseudo-off vertical axis rotation (pOVAR) to induce an otolith-only stimulus using a custom-made centrifuge. For the OOR, horizontal slow phase eye velocity (HEV) and vertical eye position (VEP) was evaluated as a function of acceleration. Using this system, we characterized hVOR and OOR in the caspase-3 (Casp3) mutant mice. Casp3 −/− mice had severely impaired hVOR gain, while Casp3 +/− mice had an intermediate response compared to WT mice. Evaluation of OOR revealed that at low to mid frequencies and stimulus intensity, Casp3 mutants and WT mice had similar responses. At higher frequencies and stimulus intensity, the Casp3 mutants displayed mildly reduced otolith organ related responses. These findings suggest that the Casp3 gene is important for the proper function of the semicircular canals but less important for the otolith organ function. PMID:25827332

  6. Otx1 gene-controlled morphogenesis of the horizontal semicircular canal and the origin of the gnathostome characteristics.

    PubMed

    Mazan, S; Jaillard, D; Baratte, B; Janvier, P

    2000-01-01

    The horizontal semicircular canal of the inner ear is a unique feature of gnathostomes and is predated by the two vertical semicircular canals, which are already present in lampreys and some fossil, armored jawless vertebrates regarded as close relatives of gnathostomes. Inactivation in mice of the orthodenticle-related gene Otx1 results in the absence of this structure. In bony fishes and tetrapods (osteichthyans), this gene belongs to a small multigene family comprising at least two orthology classes, Otx1 and Otx2. We report that, as in the mouse, xenopus and zebrafish, Otx1- and Otx2-related genes are present in a chondrichthyan, the dogfish Scyliorhinus canicula, with an Otx1 expression domain in the otocyst very similar to those observed in osteichthyans. A strong correlation is thus observed in extant vertebrates between the distribution of the horizontal semicircular canal and the presence of an Otx1 ortholog expressed in the inner ear, which supports the hypothesis that the absence of this characteristic in Otx1-/- mice may correspond to an atavism. The same conclusion applies to two other gnathostome-specific characteristics also deleted in Otx1-/- mice, the utriculosaccular duct and the ciliary process. Together with functional analyses of Otx1 and Otx2 genes in mice and comparative analyses of the Otx gene families characterized in chordates, these discoveries lead to the hypothesis that some of the anatomic characteristics of gnathostomes have appeared quite suddenly and almost simultaneously in vertebrate evolution, possibly as a consequence of gene functional diversifications following duplications of an ancestral chordate gene. PMID:11252561

  7. Fluidmechanics of semicircular canals revisited

    NASA Astrophysics Data System (ADS)

    Obrist, Dominik

    2008-05-01

    In this work we find the exact solution for the flow field in a semicircular canal which is the main sensor for angular motion in the human body. When the head is rotated the inertia of the fluid in the semicircular canal leads to a deflection of sensory hair cells which are part of a gelatinous structure called cupula. A modal expansion of the governing equation shows that the semicircular organ can be understood as a dynamic system governed by duct modes and a single cupular mode. We use this result to derive an explicit expression for the displacement of the cupula as a function of the angular motion of the head. This result shows in a mathematically and physically clean way that the semicircular canal is a transducer for angular velocity.

  8. Unilateral horizontal semicircular canal occlusion induces serotonin increase in medial vestibular nuclei: a study using microdialysis in vivo coupled with HPLC-ECD.

    PubMed

    Zhang, Ke; Li, Qian; Xu, Jia; Liu, Junxiu; Ke, Jia; Kang, Wei; Li, Tao; Ma, Furong

    2015-06-01

    Unilateral single semicircular canal occlusion (USSCO) is an effective treatment for some cases of intractable vertigo. All patients suffer behavioural imbalance caused by surgery, and then recover with a resumption of vestibular function. However, the compensation mechanism has not been fully evaluated. Findings suggest that serotonin (5-HT) is released from nerve terminals, and plays a vital role in the plasticity of the central nervous system. In this study, we performed surgery of unilateral single semicircular canal occlusion (USSCO) on guinea pigs, and investigated the change of 5-HT by in vivo microdialysis of the medial vestibular nucleus (MVN) coupled with high-performance liquid chromatography and electrochemical detection (HPLC-ECD). A total of 12 guinea pigs were divided randomly into two groups, namely the USSCO group and the control group. Animals in the USSCO group underwent surgery of lateral horizontal semicircular canal occlusion, and those in the control group experienced the same operation but just to expose the horizontal semicircular canal without occlusion. Vestibular disturbance symptoms were observed in the case of the USSCO group, e.g. head tilting, and forced circular movements and spontaneous nystagmus at postoperative days 1 and 3. The basal level of 5-HT was determined to be 316.78 ± 16.62 nM. It elevated to 448.85 ± 24.56 nM at one day following occlusion (P = 0.001). The increase was completely abolished with the vestibular dysfunction recovery. The results showed that unilateral horizontal semicircular canal occlusion could increase the 5-HT level in MVN. 5-HT may play a significant role in the process of central vestibular compensation with residual vestibular function. PMID:25943376

  9. Adaptation of primate vestibuloocular reflex to altered peripheral vestibular inputs. I. Frequency-specific recovery of horizontal VOR after inactivation of the lateral semicircular canals

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.; Arai, Y.; Suzuki, J.

    1996-01-01

    1. The adaptive plasticity of the vestibuloocular reflex (VOR) following a selective lesion of the peripheral vestibular organs was investigated in rhesus monkeys whose lateral semicircular canals were inactivated by plugging of the canal lumen in both ears. Gain and phase of horizontal, vertical, and torsional slow-phase eye velocity were determined from three-dimensional eye movement recordings obtained acutely after the plugging operation, as well as in regular intervals up to 10 mo later. 2. Acutely after plugging, horizontal VOR was minimal during yaw rotation with gains of < 0.1 at all frequencies. Horizontal VOR gain gradually increased over time, reaching gains of 0.4-0.5 for yaw oscillations at 1.1 Hz approximately 5 mo after lateral canal inactivation. This response recovery was strongly frequency dependent: horizontal VOR gains were largest at the highest frequency tested and progressively decreased for lower frequencies. Below approximately 0.1 Hz, no consistent horizontal VOR could be elicited even 10 mo after plugging. 3. The frequency-dependent changes in gain paralleled changes in horizontal VOR phase. Below approximately 0.1-0.05 Hz large phase leads were present, similarly as in semicircular canal primary afferents. Smaller phase leads were also present at higher frequencies, particularly at 1.1 Hz (the highest frequency tested). 4. Consistent with the afferent-like dynamics of the adapted horizontal VOR, per- and postrotatory horizontal responses to constant-velocity yaw rotations were short lasting. Time constants of the slow-phase eye velocity envelope of the horizontal postrotatory nystagmus were approximately 2 s. Nonetheless, a consistent horizontal optokinetic afternystagmus was evoked in plugged animals. 5. A torsional component that was absent in intact animals was consistently present during yaw rotation acutely after lateral canal inactivation and remained approximately constant thereafter. The frequency response characteristics of this

  10. Lateralization of horizontal semicircular canal canalolithiasis and cupulopathy using bow and lean test and head-roll test.

    PubMed

    Kim, Chang-Hee; Kim, Yong Gyu; Shin, Jung Eun; Yang, Young Soo; Im, Donghyuk

    2016-10-01

    Accurate lateralization is important to improve treatment outcomes in horizontal semicircular canal (HSCC) benign paroxysmal positional vertigo (BPPV). To determine the involved side in HSCC-BPPV, the intensity of nystagmus has been compared in a head-roll test (HRT) and the direction of nystagmus was evaluated in a bow and lean test (BLT). The aim of this study is to compare the results of a BLT with those of a HRT for lateralization of HSCC-canalolithiasis and cupulopathy (heavy cupula and light cupula), and evaluate treatment outcomes in patients with HSCC-canalolithiasis. We conducted retrospective case reviews in 66 patients with HSCC-canalolithiasis and 63 patients with HSCC-cupulopathy. The affected side was identified as the direction of bowing nystagmus on BLT in 55 % (36 of 66) of patients with canalolithiasis, which was concordant with the HRT result in 67 % (24 of 36) of cases (concordant group). Lateralization was determined by comparison of nystagmus intensity during HRT in 30 patients who did not show bowing or leaning nystagmus. The remission rate after the first treatment was 71 % (17 of 24) in the concordant group and 45 % (5 of 11) in the discordant group. Both bowing and leaning nystagmus were observed in all patients with cupulopathy, and the side of the null plane was identified as the affected side. In conclusion, bowing and/or leaning nystagmus were observed in only 55 % of patients with HSCC-canalolithiasis, and the first treatment based on the result of BLT alone was effective in only 45 % of the patients in whom the BLT and HRT were discordant, which may suggest that the usefulness of BLT in lateralizing the HSCC-canalolithiasis may be limited. PMID:26758464

  11. Contribution of irregular semicircular canal afferents to the horizontal vestibuloocular response during constant velocity rotation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Perachio, A. A.

    1993-01-01

    1. The effects of constant anodal currents (100 microA) delivered bilaterally to both labyrinths on the horizontal vestibuloocular response (VOR) were studied in squirrel monkeys during steps of angular velocity in the dark. We report that bilateral anodal currents decreased eye velocity approximately 30-50% during the period of galvanic stimulation without a change in the time constant of VOR. The decrease in eye velocity, present during steps of angular velocity, was not observed during sinusoidal head rotation at 0.2, 0.5, and 1 Hz. The results suggest that responses from irregular vestibular afferents influence VOR amplitude during constant velocity rotation.

  12. The Age-Related Orientational Changes of Human Semicircular Canals

    PubMed Central

    Lyu, Hui-Ying; Chen, Ke-Guang; Yin, Dong-Ming; Hong, Juan; Yang, Lin; Zhang, Tian-Yu; Dai, Pei-Dong

    2016-01-01

    Objectives Some changes are found in the labyrinth anatomy during postnatal development. Although the spatial orientation of semicircular canals was thought to be stable after birth, we investigated the age-related orientational changes of human semicircular canals during development. Methods We retrospectively studied the computed tomography (CT) images of both ears of 76 subjects ranged from 1 to 70 years old. They were divided into 4 groups: group A (1–6 years), group B (7–12 years), group C (13–18 years), and group D (>18 years). The anatomical landmarks of the inner ear structures were determined from CT images. Their coordinates were imported into MATLAB software for calculating the semicircular canals orientation, angles between semicircular canal planes and the jugular bulb (JB) position. Differences between age groups were analyzed using multivariate statistics. Relationships between variables were analyzed using Pearson analysis. Results The angle between the anterior semicircular canal plane and the coronal plane, and the angle between the horizontal semicircular canal plane and the coronal plane were smaller in group D than those in group A (P<0.05). The JB position, especially the anteroposterior position of right JB, correlated to the semicircular canals orientation (P<0.05). However, no statistically significant differences in the angles between ipsilateral canal planes among different age groups were found. Conclusion The semicircular canals had tendencies to tilt anteriorly simultaneously as a whole with age. The JB position correlated to the spatial arrangement of semicircular canals, especially the right JB. Our calculation method helps detect developmental and pathological changes in vestibular anatomy. PMID:27090280

  13. The primate semicircular canal system and locomotion

    PubMed Central

    Spoor, Fred; Garland, Theodore; Krovitz, Gail; Ryan, Timothy M.; Silcox, Mary T.; Walker, Alan

    2007-01-01

    The semicircular canal system of vertebrates helps coordinate body movements, including stabilization of gaze during locomotion. Quantitative phylogenetically informed analysis of the radius of curvature of the three semicircular canals in 91 extant and recently extinct primate species and 119 other mammalian taxa provide support for the hypothesis that canal size varies in relation to the jerkiness of head motion during locomotion. Primate and other mammalian species studied here that are agile and have fast, jerky locomotion have significantly larger canals relative to body mass than those that move more cautiously. PMID:17576932

  14. Semicircular Canal Geometry, Afferent Sensitivity And Animal Behavior

    PubMed Central

    Hullar, Timothy A.

    2008-01-01

    The geometry of the semicircular canals has been used in evolutionary studies to predict the behaviors of extinct animals. These predictions have relied on an assumption that the responses of the canals can be determined from their dimensions, and that an organism’s behavior can be determined from these responses. However, the relationship between a canal’s sensitivity and its size is not well known. An intraspecies comparison among canal responses in each of three species (cat, squirrel monkey, and pigeon) was undertaken to evaluate various models of canal function and determine how their dimensions may be related to afferent physiology. All models predicted the responses of the cat afferents, but the models performed less well for squirrel monkey and pigeon. Possible causes for this discrepancy include incorrectly assuming that afferent responses accurately represent canal function, or errors in current biophysical models of the canals. These findings leave open the question as to how reliably canal anatomy can be used to estimate afferent responses and how closely afferent responses are related to behavior. Other labyrinthine features—such as orientation of the horizontal canal, which is reliably held near earth-horizontal across many species—may be better to use when extrapolating the posture and related behavior of extinct animals from labyrinthine morphology. PMID:16550591

  15. Spatial orientation of semicircular canals and afferent sensitivity vectors in pigeons.

    PubMed

    Dickman, J D

    1996-09-01

    Rotational head motion in vertebrates is detected by the semicircular canal system, whose innervating primary afferent fibers carry information about movement in specific head planes. The semicircular canals have been qualitatively examined over a number of years, and the canal planes have been quantitatively characterized in several animal species. The present study first determined the geometric relationship between individual semicircular canals and between the canals and the stereotactic head planes in pigeons. Stereotactic measurements of multiple points along the circumference of the bony canals were taken, and the measured points fitted with a three-dimensional planar surface. Direction normals to the plane's surface were calculated and used to define angles between semicircular canal pairs. Because of the unusual shape of the anterior semicircular canals in pigeons, two planes, a major and a minor, were fitted to the canal's course. Calculated angle values for all canals indicated that the horizontal and posterior semicircular canals are nearly orthogonal, but the anterior canals have substantial deviations from orthogonality with other canal planes. Next, the responses of the afferent fibers that innervate each of the semicircular canals to 0.5 Hz sinusoidal rotation about an earth-vertical axis were obtained. The head orientation relative to the rotation axis was systematically varied so that directions of maximum sensitivity for each canal afferent could be determined. These sensitivity vectors were then compared with the canal plane direction normals. The afferents that innervated specific semicircular canals formed homogeneous clusters of sensitivity vectors in different head planes. The horizontal and posterior afferents had average sensitivity vectors that were largely co-incident with the innervated canal plane direction normals. Anterior canal afferents, however, appeared to synthesize contributions from the major and minor plane components of the

  16. Spatial orientation of semicircular canals and afferent sensitivity vectors in pigeons

    NASA Technical Reports Server (NTRS)

    Dickman, J. D.

    1996-01-01

    Rotational head motion in vertebrates is detected by the semicircular canal system, whose innervating primary afferent fibers carry information about movement in specific head planes. The semicircular canals have been qualitatively examined over a number of years, and the canal planes have been quantitatively characterized in several animal species. The present study first determined the geometric relationship between individual semicircular canals and between the canals and the stereotactic head planes in pigeons. Stereotactic measurements of multiple points along the circumference of the bony canals were taken, and the measured points fitted with a three-dimensional planar surface. Direction normals to the plane's surface were calculated and used to define angles between semicircular canal pairs. Because of the unusual shape of the anterior semicircular canals in pigeons, two planes, a major and a minor, were fitted to the canal's course. Calculated angle values for all canals indicated that the horizontal and posterior semicircular canals are nearly orthogonal, but the anterior canals have substantial deviations from orthogonality with other canal planes. Next, the responses of the afferent fibers that innervate each of the semicircular canals to 0.5 Hz sinusoidal rotation about an earth-vertical axis were obtained. The head orientation relative to the rotation axis was systematically varied so that directions of maximum sensitivity for each canal afferent could be determined. These sensitivity vectors were then compared with the canal plane direction normals. The afferents that innervated specific semicircular canals formed homogeneous clusters of sensitivity vectors in different head planes. The horizontal and posterior afferents had average sensitivity vectors that were largely co-incident with the innervated canal plane direction normals. Anterior canal afferents, however, appeared to synthesize contributions from the major and minor plane components of the

  17. Matters of simulation of the semicircular canal system

    NASA Technical Reports Server (NTRS)

    Gurfinkel, V. S.; Petukhov, S. V.

    1977-01-01

    A scale model of the human semicircular canal system was developed based on the theory of dynamic similitude. This enlarged model makes it convenient to conduct tests on the vestibular processes and dynamics in the semicircular canals. Tests revealed hydromechanical interaction between canals, with asymmetry of the conditions of movement of the endolymph in the canals in opposite directions. A type of vestibular reactions, occurring with angular oscillations of the head, was predicted and demonstrated using this model and human test subjects.

  18. Semicircular canals as a primary etiological factor in motion sickness.

    NASA Technical Reports Server (NTRS)

    Miller, E. F., II; Graybiel, A.

    1972-01-01

    Data are presented which support the view that the semicircular canals of humans can act as the essential factor for the production of motion sickness and the evocation of symptoms characteristic of this malady in the absence of 'motion.' Quantitative grading of acute symptoms demonstrated that motion sickness can be evoked by stimuli which are adequately provocative and unique for the canals. These results are compared with those of two provocative rotational tests that introduce Coriolis (cross-coupled angular acceleration) forces or generate a rotating linear acceleration vector. Wide interindividual differences but only slight intraindividual differences among the six provocative test conditions are revealed, indicating that individuals usually possess an overall susceptibility to motion which is relatively independent of its type. The fact that typical symptoms of motion sickness were also produced by bithermal irrigation of several subjects who represented a wide range of susceptibility adds to the evidence that semicircular canals can act as the primary etiological factor in this malady.

  19. Intranasal scopolamine affects the semicircular canals centrally and peripherally.

    PubMed

    Weerts, Aurélie P; Putcha, Lakshmi; Hoag, Stephen W; Hallgren, Emma; Van Ombergen, Angelique; Van de Heyning, Paul H; Wuyts, Floris L

    2015-08-01

    Space motion sickness (SMS), a condition caused by an intravestibular conflict, remains an important obstacle that astronauts encounter during the first days in space. Promethazine is currently the standard treatment of SMS, but scopolamine is used by some astronauts to prevent SMS. However, the oral and transdermal routes of administration of scopolamine are known to have substantial drawbacks. Intranasal administration of scopolamine ensures a fast absorption and rapid onset of therapeutic effect, which might prove to be suitable for use during spaceflights. The aim of this study was to evaluate the effects of intranasally administered scopolamine (0.4 mg) on the semicircular canals (SCCs) and the otoliths. This double-blind, placebo-controlled study was performed on 19 healthy male subjects. The function of the horizontal SCC and the vestibulo-ocular reflex, as well as the saccular function and utricular function, were evaluated. Scopolamine turned out to affect mainly the SCCs centrally and peripherally but also the utricles to a lesser extent. Centrally, the most probable site of action is the medial vestibular nucleus, where the highest density of muscarinic receptors has been demonstrated and afferent fibers from the SCCs and utricles synapse. Furthermore, our results suggest the presence of muscarinic receptors in the peripheral vestibular system on which scopolamine has a suppressive effect. Given the depressant actions on the SCCs, it is suggested that the pharmacodynamic effect of scopolamine may be attributed to the obliteration of intravestibular conflict that arises during (S)MS. PMID:25953832

  20. Changes of ampulla pressure in the semicircular canal of pigeons by caloric stimulation

    NASA Astrophysics Data System (ADS)

    Wada, Yoshiro; Suzuki, Hiroyuki; Watanabe, Satoru

    Still now several hypotheses about the mechanisms of the caloric nystagmus have been in conclusive. In this study we confirmed the convection effect and the volume change effect of the endolymph in horizontal semicircular canal following the caloric stimulation using pigeons ( Columba livia). Although the direction of the caloric nystagmus depended on the head position and the stimulus site of calorization, the caloric nystagmus disappeared after plugging of horizontal semicircular canal. On the other hand, the ampulla pressure increased by cold calorization and decreased by hot calorization and these pressure changes had no relation to the head position. These results show that the main role of the mechanisms of the caloric nystagmus under 1G is the convection effect but the volume change effect may act on the caloric nystagmus not only under 1G but also under microgravity.

  1. Low-frequency otolith and semicircular canal interactions after canal inactivation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Merfeld, D. M.; Hess, B. J.

    2000-01-01

    During sustained constant velocity and low-frequency off-vertical axis rotations (OVAR), otolith signals contribute significantly to slow-phase eye velocity. The adaptive plasticity of these responses was investigated here after semicircular canal plugging. Inactivation of semicircular canals results in a highly compromised and deficient vestibulo-ocular reflex (VOR). Based on the VOR enhancement hypothesis, one could expect an adaptive increase of otolith-borne angular velocity signals due to combined otolith/canal inputs after inactivation of the semicircular canals. Contrary to expectations, however, the steady-state slow-phase velocity during constant velocity OVAR decreased in amplitude over time. A similar progressive decrease in VOR gain was also observed during low-frequency off-vertical axis oscillations. This response deterioration was present in animals with either lateral or vertical semicircular canals inactivated and was limited to the plane(s) of the plugged canals. The results are consistent with the idea that the low-frequency otolith signals do not simply enhance VOR responses. Rather, the nervous system appears to correlate vestibular sensory information from the otoliths and the semicircular canals to generate an integral response to head motion.

  2. Prototype neural semicircular canal prosthesis using patterned electrical stimulation.

    PubMed

    Gong, W; Merfeld, D M

    2000-05-01

    The design of a prototype semicircular canal prosthesis is presented along with preliminary results. This device measures angular velocity of the head (+/-500 degrees/s) using a piezoelectric vibrating gyroscope. With a digital filter this velocity is filtered to match the dynamic characteristics of the semicircular canals, which are the physiological rotation sensors of the vestibular system. This digitally filtered signal is used to modulate the pulse rate of electrical stimulation. The pulse rate is varied between 50 and 250 Hz via a sigmoidal lookup table relating pulse rate to angular velocity; the steady-state rate is 150 Hz. A current source utilizes these timing pulses to deliver charge balanced, cathodic-first, biphasic, current pulses to the nerves innervating the semicircular canal via platinum electrodes. Power is supplied via lithium batteries. dc/dc converters are used to generate regulated +/-5 V supplies from the batteries. All of the components are contained in a small, lightweight, Nylon box measuring roughly 43 mm x 31 mm x 25 mm, which can be mounted on the top of an animal's head. This device has been tested in guinea pigs having surgically implanted platinum electrodes, and the results show that the prosthesis can provide a rotational cue to the nervous system. PMID:10925955

  3. Building a better semicircular canal: could we balance any better?

    NASA Astrophysics Data System (ADS)

    Squires, Todd

    2004-03-01

    Every vertebrate organism uses fluid-filled semicircular canals (SCCs) to sense rotation -- and thus to balance, navigate and hunt. Whereas the size of most organs typically scales with the size of the organism itself, the SCC are all about the same size -- whether in lizards, mice, humans, or whales. What is so special about these dimensions? We consider fluid flow in the canals and elastic deformations of a sensory membrane, and isolate physical and physiological constraints required for successful SCC function. We demonstrate that the `parameter space' open to evolution is almost completely constrained; furthermore, the most sensitive possible SCC has dimensions that are remarkably close to those common to all vertebrates.

  4. Locomotor head movements and semicircular canal morphology in primates

    PubMed Central

    Malinzak, Michael D.; Kay, Richard F.; Hullar, Timothy E.

    2012-01-01

    Animal locomotion causes head rotations, which are detected by the semicircular canals of the inner ear. Morphologic features of the canals influence rotational sensitivity, and so it is hypothesized that locomotion and canal morphology are functionally related. Most prior research has compared subjective assessments of animal “agility” with a single determinant of rotational sensitivity: the mean canal radius of curvature (R). In fact, the paired variables of R and body mass are correlated with agility and have been used to infer locomotion in extinct species. To refine models of canal functional morphology and to improve locomotor inferences for extinct species, we compare 3D vector measurements of head rotation during locomotion with 3D vector measures of canal sensitivity. Contrary to the predictions of conventional models that are based upon R, we find that axes of rapid head rotation are not aligned with axes of either high or low sensitivity. Instead, animals with fast head rotations have similar sensitivities in all directions, which they achieve by orienting the three canals of each ear orthogonally (i.e., along planes at 90° angles to one another). The extent to which the canal configuration approaches orthogonality is correlated with rotational head speed independent of body mass and phylogeny, whereas R is not. PMID:23045679

  5. An electrokinetic model of transduction in the semicircular canal.

    PubMed

    O'Leary, D P

    1970-09-01

    Transduction in the semicircular canal was studied by focusing an infrared beam on either side of exposed ampullae from the posterior canals of Rana pipiens. The direction of fluid movement resulting from a stimulus was inferred by observing the polarity of the change in afferent impulse mean rate relative to the spontaneous value. On the basis of the accepted functional polarization of this receptor, the results indicate that fluid moved toward the warmer side of the ampulla. Convection and thermal reception were shown to be unlikely explanations for these results. Morover, cupular displacements toward the warmer side would not be expected. Because thermo-osmosis can cause fluid to move toward the warmer side in a gelatin membrane, the results can be interpreted as evidence that thermo-osmosis occurred in the gelatinous cupula and influenced the transduction mechanism. Thermo-osmosis of liquids appears to be due to an electric field that is set up in a charged membrane; hence, the hair cells might have detected an electric field that occurred in the cupula during thermo-osmosis. Electroreception might be an important link in the transduction of physiological stimuli also. Rotational stimuli could result in weak electric fields in the cupula by the mechanoelectric effect. Cupular displacements could be important for large stimuli, but extrapolations to threshold stimuli suggest displacements of angstrom amplitudes. Therefore, electroreception by the hair cells could be an explanation of the great sensitivity that has been observed in the semicircular canal and other labyrinthine receptors. PMID:5496906

  6. An Electrokinetic Model of Transduction in the Semicircular Canal

    PubMed Central

    O'Leary, Dennis P.

    1970-01-01

    Transduction in the semicircular canal was studied by focusing an infrared beam on either side of exposed ampullae from the posterior canals of Rana pipiens. The direction of fluid movement resulting from a stimulus was inferred by observing the polarity of the change in afferent impulse mean rate relative to the spontaneous value. On the basis of the accepted functional polarization of this receptor, the results indicate that fluid moved toward the warmer side of the ampulla. Convection and thermal reception were shown to be unlikely explanations for these results. Morover, cupular displacements toward the warmer side would not be expected. Because thermo-osmosis can cause fluid to move toward the warmer side in a gelatin membrane, the results can be interpreted as evidence that thermo-osmosis occurred in the gelatinous cupula and influenced the transduction mechanism. Thermo-osmosis of liquids appears to be due to an electric field that is set up in a charged membrane; hence, the hair cells might have detected an electric field that occurred in the cupula during thermo-osmosis. Electroreception might be an important link in the transduction of physiological stimuli also. Rotational stimuli could result in weak electric fields in the cupula by the mechanoelectric effect. Cupular displacements could be important for large stimuli, but extrapolations to threshold stimuli suggest displacements of angstrom amplitudes. Therefore, electroreception by the hair cells could be an explanation of the great sensitivity that has been observed in the semicircular canal and other labyrinthine receptors. PMID:5496906

  7. Inactivation of Semicircular Canals Causes Adaptive Increases in Otolith-driven Tilt Responses

    NASA Technical Reports Server (NTRS)

    Angelaki, Dora E.; Newlands, Shawn D.; Dickman, J. David

    2002-01-01

    Growing experimental and theoretical evidence suggests a functional synergy in the processing of otolith and semicircular canal signals for the generation of the vestibulo-ocular reflexes (VORs). In this study we have further tested this functional interaction by quantifying the adaptive changes in the otolith-ocular system during both rotational and translational movements after surgical inactivation of the semicircular canals. For 0.1- 0.5 Hz (stimuli for which there is no recovery of responses from the plugged canals), pitch and roll VOR gains recovered during earth- horizontal (but not earth-vertical) axis rotations. Corresponding changes were also observed in eye movements elicited by translational motion (0.1 - 5 Hz). Specifically, torsional eye movements increased during lateral motion, whereas vertical eye movements increased during fore-aft motion. The findings indicate that otolith signals can be adapted according to compromised strategy that leads to improved gaze stabilization during motion. Because canal-plugged animals permanently lose the ability to discriminate gravitoinertial accelerations, adapted animals can use the presence of gravity through otolith-driven tilt responses to assist gaze stabilization during earth-horizontal axis rotations.

  8. Pathways for the vestibulo-ocular reflex excitation arising from semicircular canals of rabbits.

    PubMed

    Ito, M; Nisimaru, N; Yamamoto, M

    1976-01-26

    In anesthetized albino rabbits, ampullary branches of the vestibular nerve were stimulated electrically. Prominent and stable reflex contraction was induced in extra-ocular muscles by applying single current pulses of relatively long duration, 3-5 msec. Survey with a glass microelectrode revealed that, during application of relatively wide pulses to a canal, primary vestibular fibers discharged impulses repetitively at a rate as high as 300-1400/sec and that after being transmitted across second-order vestibular neurons these impulses built up summated EPSPs in oculomotor neurons, large enough to trigger off motoneuronal discharges. From each semicircular canal, prominent reflex contraction was evoked selectively in two muslces; from the anterior canal in the ipsilateral superior rectus and contralateral inferior oblique; from the horizontal canal in the ipsilateral medial rectus and contralateral lateral rectus; and from the posterior rectus. Acute lesion experiments indicated that signals for this excitation reached IIIrd and IVth nuclei via three different pathways; from the anterior canal through the ipsilateral brachium conjunctivum, from the horizontal canal through the ipsilateral fasciculus longitudinalis medialis and from the posterior canal through the contralateral fasciculus longitudinalis medialis. PMID:1253858

  9. Building a better semicircular canal: could we balance any better?

    NASA Astrophysics Data System (ADS)

    Squires, Todd

    2003-11-01

    Every vertebrate organism uses fluid-filled semi-circular canals (SCC) to sense angular rotation -- and thus to balance, navigate, and hunt. Whereas the size of most organs typically scales with the size of the organism itself, the SCC are all about the same size--whether in lizards, mice, humans or whales. What is so special about these dimensions? We consider fluid flow in the canals and elastic deformations of a sensory membrane, and isolate physical and physiological constraints required for successful SCC function. We demonstrate that the `parameter space' open to evolution is almost completely constrained; furthermore, the most sensitive possible SCC has dimensions that are remarkably close to those common to all vertebrates.

  10. Semicircular Canals Circumvent Brownian Motion Overload of Mechanoreceptor Hair Cells

    PubMed Central

    Muller, Mees; Heeck, Kier

    2016-01-01

    Vertebrate semicircular canals (SCC) first appeared in the vertebrates (i.e. ancestral fish) over 600 million years ago. In SCC the principal mechanoreceptors are hair cells, which as compared to cochlear hair cells are distinctly longer (70 vs. 7 μm), 10 times more compliant to bending (44 vs. 500 nN/m), and have a 100-fold higher tip displacement threshold (< 10 μm vs. <400 nm). We have developed biomechanical models of vertebrate hair cells where the bundle is approximated as a stiff, cylindrical elastic rod subject to friction and thermal agitation. Our models suggest that the above differences aid SCC hair cells in circumventing the masking effects of Brownian motion noise of about 70 nm, and thereby permit transduction of very low frequency (<10 Hz) signals. We observe that very low frequency mechanoreception requires increased stimulus amplitude, and argue that this is adaptive to circumvent Brownian motion overload at the hair bundles. We suggest that the selective advantage of detecting such low frequency stimuli may have favoured the evolution of large guiding structures such as semicircular canals and otoliths to overcome Brownian Motion noise at the level of the mechanoreceptors of the SCC. PMID:27448330

  11. Functional Implications of Ubiquitous Semicircular Canal Non-Orthogonality in Mammals

    PubMed Central

    Berlin, Jeri C.; Kirk, E. Christopher; Rowe, Timothy B.

    2013-01-01

    The ‘canonical model’ of semicircular canal orientation in mammals assumes that 1) the three ipsilateral canals of an inner ear exist in orthogonal planes (i.e., orthogonality), 2) corresponding left and right canal pairs have equivalent angles (i.e., angle symmetry), and 3) contralateral synergistic canals occupy parallel planes (i.e., coplanarity). However, descriptions of vestibular anatomy that quantify semicircular canal orientation in single species often diverge substantially from this model. Data for primates further suggest that semicircular canal orthogonality varies predictably with the angular head velocities encountered in locomotion. These observations raise the possibility that orthogonality, symmetry, and coplanarity are misleading descriptors of semicircular canal orientation in mammals, and that deviations from these norms could have significant functional consequences. Here we critically assess the canonical model of semicircular canal orientation using high-resolution X-ray computed tomography scans of 39 mammal species. We find that substantial deviations from orthogonality, angle symmetry, and coplanarity are the rule for the mammals in our comparative sample. Furthermore, the degree to which the semicircular canals of a given species deviate from orthogonality is negatively correlated with estimated vestibular sensitivity. We conclude that the available comparative morphometric data do not support the canonical model and that its overemphasis as a heuristic generalization obscures a large amount of functionally relevant variation in semicircular canal orientation between species. PMID:24260256

  12. Changes of endolymphatic pressure in the semicircular canal of pigeon by caloric stimulation

    NASA Astrophysics Data System (ADS)

    Wada, Y.; Suzuki, H.; Watanabe, S.

    1994-08-01

    It gets into difficult to explain the mechanism of caloric nystagmus only by convection theory from results of microgravity experiments. One of the other theories is an occurrence of a relative volume change due to a temperature change. Since the volume change must lead to a pressure change after caloric stimulation, we tried to measure the ampulla pressure of the horizontal semicircular canal in pigeons (Columba livia) using an improved servo micropipette system. The main result was that the ampulla pressure increased by cooling and decreased by heating. The changes of the ampulla pressure depended on the temperature change but were not influenced by the pigeon's head position.

  13. Determinants of Spatial and Temporal Coding by Semicircular Canal Afferents

    PubMed Central

    Highstein, Stephen M.; Rabbitt, Richard D.; Holstein, Gay R.; Boyle, Richard D.

    2010-01-01

    The vestibular semicircular canals are internal sensors that signal the magnitude, direction, and temporal properties of angular head motion. Fluid mechanics within the 3-canal labyrinth code the direction of movement and integrate angular acceleration stimuli over time. Directional coding is accomplished by decomposition of complex angular accelerations into 3 biomechanical components—one component exciting each of the 3 ampullary organs and associated afferent nerve bundles separately. For low-frequency angular motion stimuli, fluid displacement within each canal is proportional to angular acceleration. At higher frequencies, above the lower corner frequency, real-time integration is accomplished by viscous forces arising from the movement of fluid within the slender lumen of each canal. This results in angular velocity sensitive fluid displacements. Reflecting this, a subset of afferent fibers indeed report angular acceleration to the brain for low frequencies of head movement and report angular velocity for higher frequencies. However, a substantial number of afferent fibers also report angular acceleration, or a signal between acceleration and velocity, even at frequencies where the endolymph displacement is known to follow angular head velocity. These non-velocity-sensitive afferent signals cannot be attributed to canal biomechanics alone. The responses of non-velocity-sensitive cells include a mathematical differentiation (first-order or fractional) imparted by hair-cell and/or afferent complexes. This mathematical differentiation from velocity to acceleration cannot be attributed to hair cell ionic currents, but occurs as a result of the dynamics of synaptic transmission between hair cells and their primary afferent fibers. The evidence for this conclusion is reviewed below. PMID:15845995

  14. Anatomy of the lamprey ear: morphological evidence for occurrence of horizontal semicircular ducts in the labyrinth of Petromyzon marinus

    USGS Publications Warehouse

    Maklad, Adel; Reed, Caitlyn; Johnson, Nicholas S.; Fritzsch, Bernd

    2014-01-01

    In jawed (gnathostome) vertebrates, the inner ears have three semicircular canals arranged orthogonally in the three Cartesian planes: one horizontal (lateral) and two vertical canals. They function as detectors for angular acceleration in their respective planes. Living jawless craniates, cyclostomes (hagfish and lamprey) and their fossil records seemingly lack a lateral horizontal canal. The jawless vertebrate hagfish inner ear is described as a torus or doughnut, having one vertical canal, and the jawless vertebrate lamprey having two. These observations on the anatomy of the cyclostome (jawless vertebrate) inner ear have been unchallenged for over a century, and the question of how these jawless vertebrates perceive angular acceleration in the yaw (horizontal) planes has remained open. To provide an answer to this open question we reevaluated the anatomy of the inner ear in the lamprey, using stereoscopic dissection and scanning electron microscopy. The present study reveals a novel observation: the lamprey has two horizontal semicircular ducts in each labyrinth. Furthermore, the horizontal ducts in the lamprey, in contrast to those of jawed vertebrates, are located on the medial surface in the labyrinth rather than on the lateral surface. Our data on the lamprey horizontal duct suggest that the appearance of the horizontal canal characteristic of gnathostomes (lateral) and lampreys (medial) are mutually exclusive and indicate a parallel evolution of both systems, one in cyclostomes and one in gnathostome ancestors.

  15. CT detection of facial canal dehiscence and semicircular canal fistula: Comparison with surgical findings

    SciTech Connect

    Fuse, Takeo; Tada, Yuichiro; Aoyagi, Masaru; Sugai, Yukio

    1996-03-01

    The purpose of this study was to determine the accuracy of high resolution CT (HRCT) in the detection of facial canal dehiscence and semicircular canal fistula, the preoperative evaluation of both of which is clinically very important for ear surgery. We retrospectively reviewed the HRCT findings in 61 patients who underwent mastoidectomy at Yamagata University between 1989 and 1993. The HRCT images were obtained in the axial and semicoronal planes using 1 mm slice thickness and 1 mm intersection gap. In 46 (75%) of the 61 patients, the HRCT image-based assessment of the facial canal dehiscence coincided with the surgical findings. The data for the facial canal revealed sensitivity of 66% and specificity of 84%. For semicircular canal fistula. in 59 (97%) of the 61 patients, the HRCT image-based assessment and the surgical findings coincided. The image-based assessment in the remaining two patients, who both had massive cholesteatoma, was false-positive. HRCT is useful in the diagnosis of facial canal dehiscence and labyrinthine fistula, but its limitations should also be recognized. 12 refs., 3 figs., 6 tabs.

  16. Lateral semicircular canal fistula in cholesteatoma: diagnosis and management.

    PubMed

    Meyer, Anais; Bouchetemblé, Pierre; Costentin, Bertrand; Dehesdin, Danièle; Lerosey, Yannick; Marie, Jean-Paul

    2016-08-01

    The objective of this retrospective study was to present the authors' experience on the management of labyrinthine fistula secondary to cholesteatoma. 695 patients, who underwent tympanoplasty for cholesteatoma, in a University Hospital between 1993 and 2013 were reviewed, to select only those with labyrinthine fistulas. 42 patients (6%) had cholesteatoma complicated by fistula of the lateral semicircular canal (LSCC). The following data points were collected: symptoms, pre- and postoperative clinical signs, surgeon, CT scan diagnosis, fistula type, surgical technique, preoperative vestibular function and audiometric outcomes. Most frequent symptoms were unspecific, such as otorrhea, hearing loss and dizziness. However, preoperative high-resolution computed tomography predicted fistula in 88 %. Using the Dornhoffer and Milewski classification, 16 cases (38 %) were identified as stage 1, 22 (52 %) as stage II, and 4 (10 %) as stage III. The choice between open or closed surgical procedure was independent of the type of fistulae. The cholesteatoma matrix was completely removed from the fistula and immediately covered by autogenous material. In eight patients (19 %), the canal was drilled with a diamond burr before sealing with autologous tissue. After surgery, hearing was preserved or improved in 76 % of the patients. There was no statistically significant relationship between the extent of the labyrinthine fistula and the hearing outcome. In conclusion, a complete and nontraumatic removal of the matrix cholesteatoma over the fistula in a one-staged procedure and its sealing with bone dust and fascia temporalis, with sometimes exclusion of the LSCC, is a safe and effective procedure to treat labyrinthine fistula. PMID:26351038

  17. Mechanical amplification by hair cells in the semicircular canals

    PubMed Central

    Rabbitt, Richard D.; Boyle, Richard; Highstein, Stephen M.

    2010-01-01

    Sensory hair cells are the essential mechanotransducers of the inner ear, responsible not only for the transduction of sound and motion stimuli but also, remarkably, for nanomechanical amplification of sensory stimuli. Here we show that semicircular canal hair cells generate a mechanical nonlinearity in vivo that increases sensitivity to angular motion by amplification at low stimulus strengths. Sensitivity at high stimulus strengths is linear and shows no evidence of amplification. Results suggest that the mechanical work done by hair cells contributes ∼97 zJ/cell of amplification per stimulus cycle, improving sensitivity to angular velocity stimuli below ∼5°/s (0.3-Hz sinusoidal motion). We further show that mechanical amplification can be inhibited by the brain via activation of efferent synaptic contacts on hair cells. The experimental model was the oyster toadfish, Opsanus tau. Physiological manifestation of mechanical amplification and efferent control in a teleost vestibular organ suggests the active motor process in sensory hair cells is ancestral. The biophysical basis of the motor(s) remains hypothetical, but a key discriminating question may involve how changes in somatic electrical impedance evoked by efferent synaptic action alter function of the motor(s). PMID:20133682

  18. Acoustic effects of a superior semicircular canal dehiscence: a temporal bone study.

    PubMed

    Luers, J C; Pazen, D; Meister, H; Lauxmann, M; Eiber, A; Beutner, D; Hüttenbrink, K B

    2015-03-01

    A dehiscence of the superior semicircular canal is said to be responsible for a number of specific and unspecific ear symptoms and possible a conductive hearing loss of up to 40 dB. As in vivo a dehiscence would not be opened against air, but is naturally patched with dura and the brain, it was our aim to investigate the effects of an superior semicircular canal dehiscence on the air conduction hearing in fresh human temporal bones with different boundary conditions. At ten fresh human temporal bones, we investigated the transmission of sound energy through the middle and inner ear using a round window microphone and laser Doppler vibrometer for perilymph motions inside the dehiscence. After baseline measurements, the superior semicircular canal was opened. We investigated the change of the transfer function when the canal is opened against air (pressure equivalent water column), against a water column and when it is patched with a layer of dura. Opening the superior semicircular canal resulted in a loss of sound transmission of maximal 10-15 dB only in frequencies below 1 kHz. When covering the dehiscence with a water column, the conductive hearing component was reduced to 6-8 dB. Placing a dura patch on top of the dehiscence resulted in a normalization of the transfer function. If our experiments are consistent with the conditions in vivo, then superior semicircular canal dehiscence does not lead to an extensive and clinically considerable conductive air conduction component. PMID:24381023

  19. Tympanometric findings in superior semicircular canal dehiscence syndrome.

    PubMed

    Castellucci, A; Brandolini, C; Piras, G; Modugno, G C

    2013-04-01

    The diagnostic role of audio-impedancemetry in superior semicircular canal dehiscence (SSCD) disease is well known. In particular, since the first reports, the presence of evoked acoustic reflexes has represented a determining instrumental exhibit in differential diagnosis with other middle ear pathologies that are responsible for a mild-low frequencies air-bone gap (ABG). Even though high resolution computed tomography (HRCT) completed by parasagittal reformatted images still represents the diagnostic gold standard, several instrumental tests can support a suspect of labyrinthine capsule dehiscence when "suggestive" symptoms occur. Objective and subjective audiometry often represents the starting point of the diagnostic course aimed at investigating the cause responsible for the so-called "intra-labyrinthine conductive hearing loss". The purpose of this study is to evaluate the role of tympanometry, in particular of the inter-aural asymmetry ratio in peak compliance as a function of different mild-low frequencies ABG on the affected side, in the diagnostic work-up in patients with unilateral SSCD. The working hypothesis is that an increase in admittance of the "inner-middle ear" conduction system due to a "third mobile window" could be detected by tympanometry. A retrospective review of the clinical records of 45 patients with unilateral dehiscence selected from a pool of 140 subjects diagnosed with SSCD at our institution from 2003 to 2011 was performed. Values of ABG amplitude on the dehiscent side and tympanometric measurements of both ears were collected for each patient in the study group (n = 45). An asymmetry between tympanometric peak compliance of the involved side and that of the contralateral side was investigated by calculating the inter-aural difference and the asymmetry ratio of compliance at the eardrum. A statistically significant correlation (p = 0.015 by Fisher's test) between an asymmetry ratio ≥ 14% in favour of the pathologic ear and an ABG

  20. Turning Semicircular Canal Function on Its Head: Dinosaurs and a Novel Vestibular Analysis

    PubMed Central

    Georgi, Justin A.; Sipla, Justin S.; Forster, Catherine A.

    2013-01-01

    Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this method fails to discriminate bipedal from quadrupedal non-avian dinosaurs. Because they exhibit a broad range of relative head sizes, we use dinosaurs to test the hypothesis that semicircular ducts scale more closely with head size. Comparing the area enclosed by each semicircular canal to estimated body mass and to two different measures of head size, skull length and estimated head mass, reveals significant patterns that corroborate a connection between physical parameters of the head and semicircular canal morphology. Head mass more strongly correlates with anterior semicircular canal size than does body mass and statistically separates bipedal from quadrupedal taxa, with bipeds exhibiting relatively larger canals. This morphologic dichotomy likely reflects adaptations of the vestibular system to stability demands associated with terrestrial locomotion on two, versus four, feet. This new method has implications for reinterpreting previous studies and informing future studies on the connection between locomotion type and vestibular function. PMID:23516495

  1. Use of Steinhausen's model for describing periodic Coriolis star nystagmus. [biodynamics of semicircular canal system

    NASA Technical Reports Server (NTRS)

    Valentinuzzi, M.

    1973-01-01

    Phase lag, maximal slow phase velocity, and beat frequency were measured in periodic Coriolis star nystagmus. The results have been described by Steinhausen's model of the semicircular canal system. Estimates of the biophysical constants have been obtained. It is concluded that this model is a good functional approximation for describing, and also for interpreting, the behavior of the system.

  2. Integration of semicircular canal and otolith information for multisensory orientation stimuli

    NASA Technical Reports Server (NTRS)

    Ormsby, C. C.; Young, L. R.

    1977-01-01

    This paper presents a model for the perception of dynamic orientation resulting from stimuli which involve both the otoliths and the semicircular canals. The model was applied to several multisensory stimuli and its predictions evaluated. In all cases, the model predictions were in substantial agreement with the known illusions or with the relevant experimental data.

  3. Lateral Semicircular Canal Asymmetry in Idiopathic Scoliosis: An Early Link between Biomechanical, Hormonal and Neurosensory Theories?

    PubMed Central

    Hitier, Martin; Hamon, Michèle; Denise, Pierre; Lacoudre, Julien; Thenint, Marie-Aude; Mallet, Jean-François; Moreau, Sylvain; Quarck, Gaëlle

    2015-01-01

    Introduction Despite its high incidence and severe morbidity, the physiopathogenesis of adolescent idiopathic scoliosis (AIS) is still unknown. Here, we looked for early anomalies in AIS which are likely to be the cause of spinal deformity and could also be targeted by early treatments. We focused on the vestibular system, which is suspected of acting in AIS pathogenesis and which exhibits an end organ with size and shape fixed before birth. We hypothesize that, in adolescents with idiopathic scoliosis, vestibular morphological anomalies were already present at birth and could possibly have caused other abnormalities. Materials and Methods The vestibular organ of 18 adolescents with AIS and 9 controls were evaluated with MRI in a prospective case controlled study. We studied lateral semicircular canal orientation and the three semicircular canal positions relative to the midline. Lateral semicircular canal function was also evaluated by vestibulonystagmography after bithermal caloric stimulation. Results The left lateral semicircular canal was more vertical and further from the midline in AIS (p = 0.01) and these two parameters were highly correlated (r = -0.6; p = 0.02). These morphological anomalies were associated with functional anomalies in AIS (lower excitability, higher canal paresis), but were not significantly different from controls (p>0.05). Conclusion Adolescents with idiopathic scoliosis exhibit morphological vestibular asymmetry, probably determined well before birth. Since the vestibular system influences the vestibulospinal pathway, the hypothalamus, and the cerebellum, this indicates that the vestibular system is a possible cause of later morphological, hormonal and neurosensory anomalies observed in AIS. Moreover, the simple lateral SCC MRI measurement demonstrated here could be used for early detection of AIS, selection of children for close follow-up, and initiation of preventive treatment before spinal deformity occurs. PMID:26186348

  4. Analysis of intraindividual and intraspecific variation in semicircular canal dimensions using high-resolution x-ray computed tomography.

    PubMed

    Welker, Kelli L; Orkin, Joseph D; Ryan, Timothy M

    2009-10-01

    The semicircular canal system tracks head rotation and provides sensory input for the reflexive stabilization of gaze and posture. The purpose of this study was to investigate the intraspecific and intraindividual variation in the size of the three semicircular canals. The right and left temporal bones were extracted from 31 individuals of the short-tailed shrew (Blarina brevicauda) and scanned on a high-resolution x-ray computed tomography system. The radius of curvature was calculated for each of the three semicircular canals for each side. Paired t-tests and independent sample t-tests indicated no significant differences in canal size between the right and left canals of the same individuals or between those of males and females of the same species. Pearson product moment correlation analyses demonstrated that there was no significant correlation between canal size and body mass in this sample. PMID:19619167

  5. A geometric analysis of semicircular canals and induced activity in their peripheral afferents in the rhesus monkey

    NASA Technical Reports Server (NTRS)

    Reisine, H.; Simpson, J. I.; Henn, V.

    1988-01-01

    Experiments were carried out to determine anatomically the planes of the semicircular canals of two juvenile rhesus monkeys, using plastic casts of the semicircular canals, and the anatomical measurements were related to the directional coding of neural signals transmitted by primary afferents innervating the same simicircular canals. In the experiments, animals were prepared for monitoring the eye position by the implantation of silver-silver chloride electrodes into the bony orbit. Following the recording of semicircular canal afferent activity, the animals were sacrificed; plastic casting resin was injected into the bony canals; and, when the temporal bone was demineralized and removed, the coordinates of points spaced along the circumference of the canal casts were measured. A comparison of the sensitivity vectors determined in these experiments and the anatomical measures showed that the average difference between a sensitivity vector and its respective normal vector was 6.3 deg.

  6. Behavior of the Posterior Semicircular Canal After Dix-Hallpike Maneuver

    PubMed Central

    e Maia, Francisco Carlos Zuma; Albernaz, Pedro Luiz Mangabeira; Cal, Renato Valério

    2016-01-01

    The objective of the present study is to analyze the quantitative vestibulo-ocular responses in a group of patients with benign paroxysmal positional vertigo (BPPV) canalolithiasis and compare these data with the data of the tridimensional biomechanical model. This study was conducted on 70 patients that presented idiopathic posterior semicircular canal canalolithiasis. The diagnosis was obtained by Dix-Hallpike maneuvers recorded by videonystagmograph. The present study demonstrates that there is a significant correlation between the intensity of the nystagmus and its latency in cases of BPPV-idiopathic posterior semicircular canal canalolithiasis type. These findings are in agreement with those obtained in a tridimensional biomechanical model and are not related to the patients’ age. PMID:27588161

  7. Behavior of the Posterior Semicircular Canal After Dix-Hallpike Maneuver.

    PubMed

    E Maia, Francisco Carlos Zuma; Albernaz, Pedro Luiz Mangabeira; Cal, Renato Valério

    2016-04-20

    The objective of the present study is to analyze the quantitative vestibulo-ocular responses in a group of patients with benign paroxysmal positional vertigo (BPPV) canalolithiasis and compare these data with the data of the tridimensional biomechanical model. This study was conducted on 70 patients that presented idiopathic posterior semicircular canal canalolithiasis. The diagnosis was obtained by Dix-Hallpike maneuvers recorded by videonystagmograph. The present study demonstrates that there is a significant correlation between the intensity of the nystagmus and its latency in cases of BPPV-idiopathic posterior semicircular canal canalolithiasis type. These findings are in agreement with those obtained in a tridimensional biomechanical model and are not related to the patients' age. PMID:27588161

  8. Production of endolymph in the semicircular canal of the frog Rana esculenta.

    PubMed Central

    Bernard, C; Ferrary, E; Sterkers, O

    1986-01-01

    The mechanisms of secretion of endolymph were studied in vitro in the isolated inner ear of the frog. Prior to in vitro experiments, the composition of perilymph was evaluated in vivo and compared to that of plasma. Composition of perilymph resembled that of an extracellular fluid, although Na and Cl concentrations were higher and K concentration was lower in perilymph than in plasma water. No difference in Ca and Mg concentrations was observed between these two fluids. Osmolality averaged 227 mosmol/kg H2O in perilymph and 183 mosmol/kg H2O in plasma. Endolymph in frog inner ear corresponded in chemical pattern to mammalian endolymph. K and Na concentrations in endolymph collected from the ampulla of the posterior vertical semicircular canal averaged 121.1 mM and 2.5 mM, respectively. Osmolality of endolymph was 237 mosmol/kg H2O. K and Na concentrations were unaltered when inner ears were incubated for 24 h either at 15 degrees C or at 4 degrees C. Addition of ouabain (10(-4) M) to the perilymph-like bathing solution altered greatly Na and K composition of endolymph after incubation for 3 h at 15 degrees C. The Na and K concentration gradients between endolymph and the bath were abolished after incubation for 24 h. Ligatures of the posterior vertical semicircular canal were performed at different sites to isolate some parts of the canal, i.e. the ampulla and the non-ampullar duct. K concentration in the ampulla after incubation for 24 h remained as high as 20 times that in the bath. This K gradient was abolished in the presence of ouabain (10(-4) M). High K concentration could be maintained in the non-ampullar part of the semicircular canal only if the latter communicated with the ampulla. It is concluded that endolymph is actively secreted into the ampulla of the semicircular canal. Na+-K+-activated ATPase in the ampullar dark cells may energize the ouabain sensitive ionic transports that are involved in the production of endolymph. Endolymph secreted into the

  9. Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo Presenting with Torsional Downbeating Nystagmus: An Apogeotropic Variant

    PubMed Central

    Vannucchi, Paolo; Pecci, Rudi; Giannoni, Beatrice

    2012-01-01

    The aim of this study is to verify the hypothesis that free-floating particles could sometimes localize into the distal portion of the non ampullary arm of the posterior semicircular canal (PSC) so that assuming the Dix-Hallpike's positions, the clot could move towards the ampulla eliciting a inhibitory torsional-down beating paroxysmal positional nystagmus (PPNy), instead of typical excitatory torsional-up beating PPNy. Among 45 patients with vestibular signs suggesting anterior semicircular canal paroxysmal positional vertigo (PPV), collected from February 2003 to August 2006, we detected a group of 6 subjects whose clinical findings showed a singular behaviour during follow-up. At the first check-up, all patients were submitted to different types of physical manoeuvres for ASC canalolithiasis. Patients were controlled during the same session and after one week. When we found that nystagmus was qualitatively changed we adopted the appropriate physical therapies for that sign. At a next check-up, after having performed some physical therapies, all patients had a typical PSC PPNy of the opposite side, with respect to that of the ASC initially diagnosed. Basing on these observations we conclude that PSC PPV, similarly to lateral semicircular canal PPV, could manifests in a apogeotropic variant. PMID:22969807

  10. Semicircular canals and agility: the influence of size and shape measures

    PubMed Central

    Cox, Philip G; Jeffery, Nathan

    2010-01-01

    The semicircular canals of the inner ear sense angular accelerations and decelerations of the head and enable co-ordination of posture and body movement, as well as visual stability. Differences of agility and spatial sensitivity among species have been linked to interspecific differences in the relative size of the canals, particularly the radius of curvature (R) and the ratio of the canal plane area to streamline length (P/L). Here we investigate the scaling relationships of these two size variables and also out-of-plane torsion in the three semicircular canals (anterior, posterior and lateral), in order to assess which is more closely correlated with body size and locomotor agility. Measurements were computed from 3D landmarks taken from magnetic resonance images of a diverse sample of placental mammals encompassing 16 eutherian orders. Body masses were collected from the literature and an agility score was assigned to each species. The R and P/L of all three semicircular canals were found to have highly significant positive correlations with each other and no statistical difference was found between the slope of 2P/L against R and 1. This indicated that, contrary to initial hypotheses, there is little difference between 2P/L and R as measures of semicircular canal size. A measure of the in-plane circularity of the canal was obtained by dividing 2P/L by R and out-of-plane torsion was measured as angular deviation from a plane of best fit. It was predicted that deviations from in-plane and out-of-plane circularity would increase at small body size due to the constraints of fitting a proportionately larger canal into a smaller petrous bone. However, neither measurement was found to have a significant correlation with body mass, indicating that deviations from circularity (both in-plane and out-of-plane) are not sufficient to alter P/L to an extent that would impact the sensitivity of the canals. 2P/L and R were both shown to be significantly correlated with

  11. Semicircular canals and agility: the influence of size and shape measures.

    PubMed

    Cox, Philip G; Jeffery, Nathan

    2010-01-01

    The semicircular canals of the inner ear sense angular accelerations and decelerations of the head and enable co-ordination of posture and body movement, as well as visual stability. Differences of agility and spatial sensitivity among species have been linked to interspecific differences in the relative size of the canals, particularly the radius of curvature (R) and the ratio of the canal plane area to streamline length (P/L). Here we investigate the scaling relationships of these two size variables and also out-of-plane torsion in the three semicircular canals (anterior, posterior and lateral), in order to assess which is more closely correlated with body size and locomotor agility. Measurements were computed from 3D landmarks taken from magnetic resonance images of a diverse sample of placental mammals encompassing 16 eutherian orders. Body masses were collected from the literature and an agility score was assigned to each species. The R and P/L of all three semicircular canals were found to have highly significant positive correlations with each other and no statistical difference was found between the slope of 2P/L against R and 1. This indicated that, contrary to initial hypotheses, there is little difference between 2P/L and R as measures of semicircular canal size. A measure of the in-plane circularity of the canal was obtained by dividing 2P/L by R and out-of-plane torsion was measured as angular deviation from a plane of best fit. It was predicted that deviations from in-plane and out-of-plane circularity would increase at small body size due to the constraints of fitting a proportionately larger canal into a smaller petrous bone. However, neither measurement was found to have a significant correlation with body mass, indicating that deviations from circularity (both in-plane and out-of-plane) are not sufficient to alter P/L to an extent that would impact the sensitivity of the canals. 2P/L and R were both shown to be significantly correlated with

  12. Semicircular canal, saccular and utricular function in patients with bilateral vestibulopathy: analysis based on etiology

    PubMed Central

    Bremova, Tatiana; Kremmyda, Olympia; Strupp, Michael

    2014-01-01

    The diagnosis of bilateral vestibulopathy (BV) is typically established based on bilateral semicircular canal dysfunction. The degree to which both otolith organs—the saccule and utricle—are also impaired in BV is not wellestablished, particularly with respect to the etiology and severity of BV. The aim of this study was to evaluate semicircular canal, saccular and utricular function in patients with BV due to aminoglycoside ototoxicity and bilateral Menière’s disease, and with different severities of BV. Caloric and head impulse testing were used as measures of canal function. Cervical vestibular-evoked myogenic potentials (cVEMP) and ocular VEMPs (oVEMP) were used as measures of saccular and utricular function, respectively. We enrolled 34 patients with BV and 55 controls in a prospective case–control study. Patients with BV were less likely to have saccular (61 %) or utricular (64 %) dysfunction relative to canal dysfunction (100 %). Utricular function differed significantly between patients by etiologic group: the poorest function was found in patients with BV due to aminoglycoside toxicity, and the best function in Menière’s disease patients. Canal and saccular function did not vary according to etiology. Further, utricular but not saccular function was significantly correlated with canal function. Saccular and utricular function had the strongest association with Dizziness Handicap Inventory scores relative to canal function. These data suggest that when a patient with BV is identified in a clinical context, oVEMP testing is the most sensitive test in distinguishing between aminoglycoside toxicity and bilateral Menière’s disease. Both cVEMP and oVEMP testing may be considered to evaluate the functional impact on the patient. PMID:23104126

  13. Directional coding of three-dimensional movements by the vestibular semicircular canals.

    PubMed

    Rabbitt, R D

    1999-06-01

    A morphologically descriptive mathematical model was developed to study the role of labyrinthine geometry in determining sensitivities of each semicircular canal to angular motion stimuli in three-dimensional (3D) space. For this, equations describing viscous flow of the endolymph and poro-elastic response of the cupulae were coupled together and solved within a 3D reconstructed geometry. Results predict the existence of prime rotational directions about which the labyrinth resolves 3D angular movements into separate vectorial components. The components are predicted to be transmitted to the brain separately, one coded by each canal nerve. Prime directions predicted by the model are non-orthogonal, distinct from the anatomical canal planes, and distinct from the directions of rotation which elicit maximal responses of individual canal nerves. They occur for each canal along the intersection of the two null planes defined by its sister canals. Hence, rotation about a prime direction excites only one canal nerve. This contrasts the situation for rotations about anatomical canal planes, or about maximal response directions, where the model predicts activation of multiple canal nerves. The prime directions are sensitive to labyrinthine morphology and, hence, are predicted to vary between species and, to a lesser extent, vary between individual animals. Prime directions were estimated in the present work using a mathematical model, but could be determined experimentally based on the directional sensitivities of individual canal nerves. The model also predicts the existence of dominant eigenmodes and time constants associated with rotation in each of the prime directions. Results may have implications regarding the central representation of angular head movements in space as well as the neuronal mappings between three-canal afferent inputs and motor outputs. PMID:10420568

  14. Functional recovery of anterior semicircular canal afferents following hair cell regeneration in birds

    NASA Technical Reports Server (NTRS)

    Boyle, Richard; Highstein, Stephen M.; Carey, John P.; Xu, Jinping

    2002-01-01

    Streptomycin sulfate (1.2 g/kg i.m.) was administered for 5 consecutive days to 5-7-day-old white Leghorn chicks; this causes damage to semicircular canal hair cells that ultimately regenerate to reform the sensory epithelium. During the recovery period, electrophysiological recordings were taken sequentially from anterior semicircular canal primary afferents using an indentation stimulus of the canal that has been shown to mimic rotational stimulation. Chicks were assigned to an early (14-18 days; n = 8), intermediate (28-34 days; n = 5), and late (38-58 days; n = 4) period based on days after treatment. Seven untreated chicks, 15-67 days old, provided control data. An absence of background and indent-induced discharge was the prominent feature of afferents in the early period: only "silent" afferents were encountered in 5/8 experiments. In several of these chicks, fascicles of afferent fibers were seen extending up to the epithelium that was void of hair cells, and intra- and extracellular biocytin labeling revealed afferent processes penetrating into the supporting cell layer of the crista. In 3/8 chicks 74 afferents could be characterized, and they significantly differed from controls (n = 130) by having a lower discharge rate and a negligible response to canal stimulation. In the intermediate period there was considerable variability in discharge properties of 121 afferents, but as a whole the number of "silent" fibers in the canal nerve diminished, the background rate increased, and a response to canal stimulation detected. Individually biocytin-labeled afferents had normal-appearing terminal specializations in the sensory epithelium by 28 days poststreptomycin. In the late period, afferents (n = 58) remained significantly different from controls in background discharge properties and response gain. The evidence suggests that a considerable amount of variability exists between chicks in the return of vestibular afferent function following ototoxic injury and

  15. Optimizing the Vertebrate Vestibular Semicircular Canal: Could We Balance Any Better?

    NASA Astrophysics Data System (ADS)

    Squires, Todd M.

    2004-11-01

    The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has “optimally designed.” Four geometric parameters characterize the SCC, and “building materials” of given physical properties are assumed. Identifying physical and physiological constraints on SCC operation, we find the most sensitive SCC has dimensions consistent with available data. Since natural selection involves optimization, this approach may find broader use in understanding biological structures.

  16. Three-dimensional analysis of vestibular efferent neurons innervating semicircular canals of the gerbil

    NASA Technical Reports Server (NTRS)

    Purcell, I. M.; Perachio, A. A.

    1997-01-01

    areas of efferent terminal fields display a trend from smallest to largest for the central, peripheral, and planum types, respectively. Neurons that innervate the central zone of the crista do not extend into the peripheral or planum regions. Conversely, those neurons with terminal fields in the peripheral or planum regions do not innervate the central zone of the sensory neuroepithelium. The central zone of the crista is innervated preferentially by efferent neurons with cell bodies located in the ipsilateral group e. The peripheral and planum zones of the crista are innervated preferentially by efferent neurons with cell bodies located in the contralateral group e. A model incorporating our anatomic observations is presented describing an ipsilateral closed-loop feedback between ipsilateral efferent neurons and the periphery and an open-loop feed-forward innervation from contralateral efferent neurons. A possible role for the vestibular efferent neurons in the modulation of semicircular canal afferent response dynamics is proposed.

  17. Evaluation of the vertical semicircular canal function by the pendular rotation test: a study on patients with benign paroxysmal positional vertigo.

    PubMed

    Iida, M; Igarashi, M; Naitoh, A; Ishida, K; Endo, K; Nomura, K; Sakai, M

    1997-01-01

    The pendular rotation test (non-damped) in a head-tilted position, 60 degrees backward and then rotated 45 degrees either to the right or left, was performed in 6 patients with benign paroxysmal positional vertigo. The stimulus mode was amplitude = 360 degrees, frequency = 0.1 Hz, and the maximal speed = 114 degrees/s. By this test procedure, it was possible to evaluate the excitability of vertical semicircular canals. Using an infra-red CCD camera and a personal computer system, the evoked nystagmus was analysed. A statistically significant difference (p < 0.05) in the maximal slow-phase eye velocity of vertical nystagmus was found between those from the anterior semicircular canal and those from the posterior semicircular canal. The excitability of the posterior semicircular canal in the affected ear was found to be lower than that of the anterior semicircular canal. PMID:9279865

  18. The contribution of otoliths and semicircular canals to the perception of two-dimensional passive whole-body motion in humans.

    PubMed

    Ivanenko, Y P; Grasso, R; Israël, I; Berthoz, A

    1997-07-01

    1. Perception of two-dimensional (2-D) whole-body passive motion in the horizontal plane was studied in twelve blindfolded healthy volunteers: pure rotation in place (180 deg), linear motion (4.5 m) and a semicircular trajectory (radius, 1.5 m; angular acceleration, 0.2 rad s-2) were applied in random sequence by means of a remote-controlled robot equipped with a racing-car seat. The seat orientation in the horizontal plane was controlled by the experimenter, independent of the robot trajectory. Thus different degrees of otolith-canal interaction were obtained. The maximal linear acceleration during the semicircular trajectory was 0.1 g; however, the linear acceleration vector was complex as it rotated relative to the subject's head. 2. In the first of two sessions, subjects were instructed to maintain an angular pointer oriented towards a remote (15 m) previously seen target during the passive movements. In the second session they had to make a drawing of the path of the perceived trajectory, after the movement was finished. 3. The results showed that, on average, the movement of the pointer matched the dynamics of the rotatory component of the 2-D motion well. This suggests that, in the range of linear accelerations used in this study, no appreciable influence of otolith input on canal-mediated perception of angular motion occurred. 4. The curvature of the drawn paths was mostly explained by the input to the semicircular canals. Subjects' reconstruction of motion did not account for the directional dynamics of the input to the otoliths occurring during passive motion. 5. This finding proves that reconstructing trajectory in space does not imply a mathematically perfect transformation of the linear and angular motion-related inputs into a Cartesian or polar 2-D representation. Physiological constraints on the interaction between motion direction and change of heading play an important role in motion perception. PMID:9234209

  19. Neural processing of gravito-inertial cues in humans. I. Influence of the semicircular canals following post-rotatory tilt

    NASA Technical Reports Server (NTRS)

    Zupan, L. H.; Peterka, R. J.; Merfeld, D. M.; Peterson, B. W. (Principal Investigator)

    2000-01-01

    Sensory systems often provide ambiguous information. Integration of various sensory cues is required for the CNS to resolve sensory ambiguity and elicit appropriate responses. The vestibular system includes two types of sensors: the semicircular canals, which measure head rotation, and the otolith organs, which measure gravito-inertial force (GIF), the sum of gravitational force and inertial force due to linear acceleration. According to Einstein's equivalence principle, gravitational force is indistinguishable from inertial force due to linear acceleration. As a consequence, otolith measurements must be supplemented with other sensory information for the CNS to distinguish tilt from translation. The GIF resolution hypothesis states that the CNS estimates gravity and linear acceleration, so that the difference between estimates of gravity and linear acceleration matches the measured GIF. Both otolith and semicircular canal cues influence this estimation of gravity and linear acceleration. The GIF resolution hypothesis predicts that inaccurate estimates of both gravity and linear acceleration can occur due to central interactions of sensory cues. The existence of specific patterns of vestibuloocular reflexes (VOR) related to these inaccurate estimates can be used to test the GIF resolution hypothesis. To investigate this hypothesis, we measured eye movements during two different protocols. In one experiment, eight subjects were rotated at a constant velocity about an earth-vertical axis and then tilted 90 degrees in darkness to one of eight different evenly spaced final orientations, a so-called "dumping" protocol. Three speeds (200, 100, and 50 degrees /s) and two directions, clockwise (CW) and counterclockwise (CCW), of rotation were tested. In another experiment, four subjects were rotated at a constant velocity (200 degrees /s, CW and CCW) about an earth-horizontal axis and stopped in two different final orientations (nose-up and nose-down), a so

  20. Mechanical versus CO2 laser occlusion of the posterior semicircular canal in humans.

    PubMed

    Antonelli, P J; Lundy, L B; Kartush, J M; Burgio, D L; Graham, M D

    1996-05-01

    The purpose of this study was to compare the effectiveness of mechanical and laser-assisted posterior semicircular canal occlusion (PCO) for the treatment of intractable benign paroxysmal positional vertigo (BPPV). Twelve consecutive patients with intractable BPPV underwent PCO by three surgeons, six with mechanical PCO and six with CO2 laser-assisted PCO. PCO eliminated positional vertigo in all patients treated with the laser and five of six patients treated without the laser. Dysequilibrium was present in all patients immediately postoperatively. This resolved in all patients treated with the CO2 laser but in only two of six patients treated without the laser (p = 0.03). Patients were hospitalized for dysequilibrium for an average of 5.2 and 2.8 days for the mechanical and laser-assisted groups, respectively. Preoperative and postoperative hearing was not significantly different between the groups. No clinically significant postoperative hearing loss was encountered in either group. These results suggest that PCO is an effective treatment for intractable BPPV. The incidence of dysequilibrium that persists following PCO may be reduced by using the CO2 laser to seal the membranous canal prior to occluding the bony canal. PMID:8817019

  1. State-space receptive fields of semicircular canal afferent neurons in the bullfrog

    NASA Technical Reports Server (NTRS)

    Paulin, M. G.; Hoffman, L. F.

    2001-01-01

    Receptive fields are commonly used to describe spatial characteristics of sensory neuron responses. They can be extended to characterize temporal or dynamical aspects by mapping neural responses in dynamical state spaces. The state-space receptive field of a neuron is the probability distribution of the dynamical state of the stimulus-generating system conditioned upon the occurrence of a spike. We have computed state-space receptive fields for semicircular canal afferent neurons in the bullfrog (Rana catesbeiana). We recorded spike times during broad-band Gaussian noise rotational velocity stimuli, computed the frequency distribution of head states at spike times, and normalized these to obtain conditional pdfs for the state. These state-space receptive fields quantify what the brain can deduce about the dynamical state of the head when a single spike arrives from the periphery. c2001 Elsevier Science B.V. All rights reserved.

  2. Development of the otolith organs and semicircular canals in the Japanese red-bellied newt, Cynops pyrrhogaster

    NASA Technical Reports Server (NTRS)

    Wiederhold, M. L.; Yamashita, M.; Larsen, K. A.; Batten, J. S.; Koike, H.; Asashima, M.

    1995-01-01

    The sequence in which the otoliths and semicircular canals and their associated sensory epithelia appear and develop in the newt are described. Three-dimensional reconstruction of serial sections through the otic vesicle of newt embryos from stages 31 through 58 demonstrate the first appearance, relative position and growth of the otoliths. A single otolith is first seen in stage 33 embryos (approximately 9 days old); this splits into separate utricular and saccular otoliths at stage 40 (13 days). The lateral semicircular canal is the first to appear, at stage 41 (14 days). The anterior and posterior canals appear approximately one week later and the vestibular apparatus is essentially fully formed at stage 58 (approximately 5 weeks). The data reported here will serve as ground-based controls for fertilized newt eggs flown on the International Microgravity Laboratory-2 Space Shuttle flight, to investigate the influence of microgravity on the development of the gravity-sensing organs.

  3. Responses of the frog primary vestibular afferents to direct vibration of the semicircular canal

    NASA Technical Reports Server (NTRS)

    Orlov, I. V.

    1980-01-01

    Responses of primary afferents (PA) of lateral semicircular canal to sinusoidal vibration of the canal wall within the range 0.05-200 Hz (mean amplitudes 5-15 microns) in immobilized frogs were studied. Dynamic characteristics (gain, phase) of relative linear velocity of the vibrator (micron X/s) were examined. At 0.2 Hz, the gain was 5.35 + or - 3.19 imp X/s /micron X/s (mean; S.D.; n=14) and linearly decreased if the frequency rose. Phase lag of relative velocity at 0.05 Hz was 49.8 deg + or - 16.5 deg (n=13) and at 1 Hz 97 deg + or - 9.4 deg (n=22). At 100 Hz phase lag was about 240 deg. Three groups of PA are described: wide range PA reacting in the range from 0.05 up to 60-180 Hz; high frequency PA responding in the range from 20-40 up to 100-150 Hz; and low frequency PA responding in the range from 0.05 up to 2-20 Hz.

  4. The Effect of Superior Semicircular Canal Dehiscence on Intracochlear Sound Pressures

    NASA Astrophysics Data System (ADS)

    Nakajima, Hideko Heidi; Pisano, Dominic V.; Merchant, Saumil N.; Rosowski, John J.

    2011-11-01

    Semicircular canal dehiscence (SCD) is a pathological opening in the bony wall of the inner ear that can result in conductive hearing loss. The hearing loss is variable across patients, and the precise mechanism and source of variability is not fully understood. We use intracochlear sound pressure measurements in cadaveric preparations to study the effects of SCD size. Simultaneous measurement of basal intracochlear sound pressures in scala vestibuli (SV) and scala tympani (ST) quantifies the complex differential pressure across the cochlear partition, the stimulus that excites the partition. Sound-induced pressures in SV and ST, as well as stapes velocity and ear-canal pressure are measured simultaneously for various sizes of SCD followed by SCD patching. At low frequencies (<600 Hz) our results show that SCD decreases the pressure in both SV and ST, as well as differential pressure, and these effects become more pronounced as dehiscence size is increased. For frequencies above 1 kHz, the smallest pinpoint dehiscence can have the larger effect on the differential pressure in some ears. These effects due to SCD are reversible by patching the dehiscence.

  5. Sensory transduction at the frog semicircular canal: how hair cell membrane potential controls junctional transmission

    PubMed Central

    Martini, Marta; Canella, Rita; Rubbini, Gemma; Fesce, Riccardo; Rossi, Maria Lisa

    2015-01-01

    At the frog semicircular canals, the afferent fibers display high spontaneous activity (mEPSPs), due to transmitter release from hair cells. mEPSP and spike frequencies are modulated by stimulation that activates the hair cell receptor conductance. The relation between receptor current and transmitter release cannot be studied at the intact semicircular canal. To circumvent the problem, we combined patch-clamp recordings at the isolated hair cell and electrophysiological recordings at the cytoneural junction in the intact preparation. At isolated hair cells, the K channel blocker tetraethylammonium (TEA) is shown to block a fraction of total voltage-dependent K-conductance (IKD) that depends on TEA concentration but not on membrane potential (Vm). Considering the bioelectric properties of the hair cell, as previously characterized by this lab, a fixed fractional block of IKD is shown to induce a relatively fixed shift in Vm, provided it lies in the range −30 to −10 mV. The same concentrations of TEA were applied to the intact labyrinth while recording from single afferent fibers of the posterior canal, at rest and during mechanical stimulation. At the peak of stimulation, TEA produced increases in mEPSP rate that were linearly related to the shifts produced by the same TEA concentrations (0.1–3 mM) in hair cell Vm (0.7–5 mV), with a slope of 29.8 Hz/mV. The membrane potential of the hair cell is not linearly related to receptor conductance, so that the slope of quantal release vs. receptor conductance depends on the prevailing Vm (19.8 Hz/nS at −20 mV; 11 Hz/nS at −10 mV). Changes in mEPSP peak size were negligible at rest as well as during stimulation. Since ample spatial summation of mEPSPs occurs at the afferent terminal and threshold-governed spike firing is intrinsically nonlinear, the observed increases in mEPSP frequency, though not very large, may suffice to trigger afferent spike discharge. PMID:26157360

  6. Semicircular Horizontal Approach in Breast Reduction: Clinical Experience in 38 Cases

    PubMed Central

    Shin, Hee Su; Jung, Sung Gyun; Lee, Doo Hyung; Roe, Young; Cha, Jong Hyun

    2015-01-01

    Background Various techniques are used for performing breast reduction. Wise-pattern and vertical scar techniques are the most commonly employed approaches. However, a vertical scar in the mid-lower breast is prominent and aesthetically less pleasant. In contrast, a semicircular horizontal approach does not leave a vertical scar in the mid breast and transverse scars can be hidden in the inframammary fold. In this paper, we describe the experiences and results of semicircular horizontal breast reductions performed by a single surgeon. Methods Between September 1996 and October 2013, our senior author used this technique in 38 cases in the US and at our institution. We used a superiorly based semicircular incision, where the upper skin paddle was pulled down to the inframammary fold with the nipple-areola complex pulled through the keyhole. Results The average total reduction per breast was 584 g, ranging from 286 to 794 g. The inferior longitudinal pedicle was used in all the cases. The average reduction of the distance from the sternal notch to the nipple was 13 cm (range, 11-15 cm). The mean decrease in the bra cup size was 1.7 cup sizes (range, a decrease of 1 to 3). We obtained very satisfactory results with a less noticeable scar, no complication such as necrosis of the nipple or the skin flap, wound infection, aseptic necrosis of the breast tissue, or wound dehiscence. One patient had a small hematoma that resolved spontaneously. Conclusions This technique is straightforward and easy to learn, and offers a safe, effective, and predictable way for treating mammary hypertrophy. PMID:26217565

  7. A Mathematical Model of Human Semicircular Canal Geometry: A New Basis for Interpreting Vestibular Physiology

    PubMed Central

    Curthoys, Ian S.; Todd, Michael J.; Magnussen, John S.; Taubman, David S.; Aw, Swee T.; Halmagyi, G. Michael

    2009-01-01

    We report a precise, simple, and accessible method of mathematically measuring and modeling the three-dimensional (3D) geometry of semicircular canals (SCCs) in living humans. Knowledge of this geometry helps understand the development and physiology of SCC stimulation. We developed a framework of robust techniques that automatically and accurately reconstruct SCC geometry from computed tomography (CT) images and are directly validated using micro-CT as ground truth. This framework measures the 3D centroid paths of the bony SCCs allowing direct comparison and analysis between ears within and between subjects. An average set of SCC morphology is calculated from 34 human ears, within which other geometrical attributes such as nonplanarity, radius of curvature, and inter-SCC angle are examined, with a focus on physiological implications. These measurements have also been used to critically evaluate plane fitting techniques that reconcile many of the discrepancies in current SCC plane studies. Finally, we mathematically model SCC geometry using Fourier series equations. This work has the potential to reinterpret physiology and pathophysiology in terms of real individual 3D morphology. Electronic supplementary material The online version of this article (doi:10.1007/s10162-009-0195-6) contains supplementary material, which is available to authorized users. PMID:19949828

  8. Convergence of limb, visceral, and vertical semicircular canal or otolith inputs onto vestibular nucleus neurons

    NASA Technical Reports Server (NTRS)

    Jian, B. J.; Shintani, T.; Emanuel, B. A.; Yates, B. J.

    2002-01-01

    The major goal of this study was to determine the patterns of convergence of non-labyrinthine inputs from the limbs and viscera onto vestibular nucleus neurons receiving signals from vertical semicircular canals or otolith organs. A secondary aim was to ascertain whether the effects of non-labyrinthine inputs on the activity of vestibular nucleus neurons is affected by bilateral peripheral vestibular lesions. The majority (72%) of vestibular nucleus neurons in labyrinth-intact animals whose firing was modulated by vertical rotations responded to electrical stimulation of limb and/or visceral nerves. The activity of even more vestibular nucleus neurons (93%) was affected by limb or visceral nerve stimulation in chronically labyrinthectomized preparations. Some neurons received non-labyrinthine inputs from a variety of peripheral sources, including antagonist muscles acting at the same joint, whereas others received inputs from more limited sources. There was no apparent relationship between the spatial and dynamic properties of a neuron's responses to tilts in vertical planes and the non-labyrinthine inputs that it received. These data suggest that non-labyrinthine inputs elicited during movement will modulate the processing of information by the central vestibular system, and may contribute to the recovery of spontaneous activity of vestibular nucleus neurons following peripheral vestibular lesions. Furthermore, some vestibular nucleus neurons with non-labyrinthine inputs may be activated only during particular behaviors that elicit a specific combination of limb and visceral inputs.

  9. Convergence of limb, visceral, and vertical semicircular canal or otolith inputs onto vestibular nucleus neurons.

    PubMed

    Jian, B J; Shintani, T; Emanuel, B A; Yates, B J

    2002-05-01

    The major goal of this study was to determine the patterns of convergence of non-labyrinthine inputs from the limbs and viscera onto vestibular nucleus neurons receiving signals from vertical semicircular canals or otolith organs. A secondary aim was to ascertain whether the effects of non-labyrinthine inputs on the activity of vestibular nucleus neurons is affected by bilateral peripheral vestibular lesions. The majority (72%) of vestibular nucleus neurons in labyrinth-intact animals whose firing was modulated by vertical rotations responded to electrical stimulation of limb and/or visceral nerves. The activity of even more vestibular nucleus neurons (93%) was affected by limb or visceral nerve stimulation in chronically labyrinthectomized preparations. Some neurons received non-labyrinthine inputs from a variety of peripheral sources, including antagonist muscles acting at the same joint, whereas others received inputs from more limited sources. There was no apparent relationship between the spatial and dynamic properties of a neuron's responses to tilts in vertical planes and the non-labyrinthine inputs that it received. These data suggest that non-labyrinthine inputs elicited during movement will modulate the processing of information by the central vestibular system, and may contribute to the recovery of spontaneous activity of vestibular nucleus neurons following peripheral vestibular lesions. Furthermore, some vestibular nucleus neurons with non-labyrinthine inputs may be activated only during particular behaviors that elicit a specific combination of limb and visceral inputs. PMID:12012162

  10. Radiographic Features of Superior Semicircular Canal Dehiscence in the Setting of Chronic Ear Disease

    PubMed Central

    Gentry, Lindell R.; Kennedy, Tabassum A.; Gubbels, Samuel P.

    2013-01-01

    Objective To determine if radiologic chronic otitis media (COM), both with and without cholesteatoma, is associated with superior semicircular canal dehiscence (SSCD). Study Design Retrospective review of consecutive high-resolution computed tomography (HRCT) scans of the temporal bone. Setting Tertiary care medical center Patients Two-hundred consecutive patients undergoing HRCT of the temporal bone beginning January 1st, 2012. Intervention Imaging was evaluated by three reviewers (two neuroradiologists and one neurotologist). All scans were assessed for the presence of SSCD, cholesteatoma, chronic otomastoiditis, tegmen dehiscence, and for abnormalities of the cochlea, vestibule, facial nerve, and temporal bone vasculature. Main Outcome Measure Ears with COM associated with chronic otomastoiditis or cholesteatoma were compared to those without COM with respect to the presence of SSCD or other temporal bone abnormalities. Statistical analysis was performed to assess for differences between the groups studied. Results 194 patients (388 ears) were included. Cholesteatoma was identified in 48 ears (12.4%) and chronic otomastoiditis in 62 ears (16%). Ten ears with cholesteatoma had ipsilateral SSCD and 8 ears with chronic otomastoiditis had ipsilateral SSCD. In 340 ears without either cholesteatoma or chronic otomastoiditis, SSCD was found in 18 (5.3%). SSCD was found to occur significantly more often in patients with ipsilateral radiologic cholesteatoma. No cases of SSCD were associated with cochlear, facial nerve, or vascular abnormalities. Conclusion Our findings suggest that COM with cholesteatoma is associated with the presence of SSCD, although the nature of this association is unclear. PMID:24136312

  11. Electrical filtering in gerbil isolated type I semicircular canal hair cells

    NASA Technical Reports Server (NTRS)

    Rennie, K. J.; Ricci, A. J.; Correia, M. J.

    1996-01-01

    1. Membrane potential responses of dissociated gerbil type I semicircular canal hair cells to current injections in whole cell current-clamp have been measured. The input resistance of type I cells was 21.4 +/- 14.3 (SD) M omega, (n = 25). Around the zero-current potential (Vz = -66.6 +/- 9.3 mV, n = 25), pulsed current injections (from approximately -200 to 750 pA) produced only small-amplitude, pulse-like changes in membrane potential. 2. Injecting constant current to hyperpolarize the membrane to around -100 mV resulted in a approximately 10-fold increase in membrane resistance. Current pulses superimposed on this constant hyperpolarization produced larger and more complex membrane potential changes. Depolarizing currents > or = 200 pA caused a rapid transient peak voltage before a plateau. 3. Membrane voltage was able to faithfully follow sine-wave current injections around Vz over the range 1-1,000 Hz with < 25% attenuation at 1 kHz. A previously described K conductance, IKI, which is active at Vz, produces the low input resistance and frequency response. This was confirmed by pharmacologically blocking IKI. This conductance, present in type I cells but not type II hair cells, would appear to confer on type I cells a lower gain, but a much broader bandwidth at Vz, than seen in type II cells.

  12. Interaction of semicircular canal stimulation with carotid baroreceptor reflex control of heart rate

    NASA Technical Reports Server (NTRS)

    Convertino, V. A.

    1998-01-01

    The carotid-cardiac baroreflex contributes to the prediction of orthostatic tolerance; experimental attenuation of the reflex response leads to orthostatic hypotension in humans and animals. Anecdotal observations indicate that rotational head movements about the vertical axis of the body can also induce orthostatic bradycardia and hypotension through increased parasympathetic activity. We therefore measured the chronotropic response to carotid baroreceptor stimulation in 12 men during varying conditions of vestibulo-oculomotor stimulation to test the hypothesis that stimulation of the semicircular canals associated with head movements in the yaw plane inhibits cardioacceleration through a vagally mediated baroreflex. Carotid-cardiac baroreflex response was assessed by plotting R-R intervals (ms) at each of 8 neck pressure steps with their respective carotid distending pressures (mmHg). Calculated baroreflex gain (maximal slope of the stimulus-response relationship) was measured under 4 experimental conditions: 1) sinusoidal whole-body yaw rotation of the subject in the dark without visual fixation (combined vestibular-oculomotor stimulation); 2) yaw oscillation of the subject while tracking a small head-fixed light moving with the subject (vestibular stimulation without eye movements); 3) subject stationary while fixating on a small light oscillating in yaw at the same frequency, peak acceleration, and velocity as the chair (eye movements without vestibular stimulation); and 4) subject stationary in the dark (no eye or head motion). Head motion alone and with eye movement reduced baseline baroreflex responsiveness to the same stimulus by 30%. Inhibition of cardioacceleration during rotational head movements may have significant impact on functional performance in aerospace environments, particularly in high-performance aircraft pilots during high angular acceleration in aerial combat maneuvers or in astronauts upon return from spaceflight who already have

  13. Efferent Control of Hair Cell and Afferent Responses in the Semicircular Canals

    PubMed Central

    Boyle, Richard; Rabbitt, Richard D.; Highstein, Stephen M.

    2009-01-01

    The sensations of sound and motion generated by the inner ear are controlled by the brain through extensive centripetal innervation originating within the brain stem. In the semicircular canals, brain stem efferent neurons make synaptic contacts with mechanosensory hair cells and with the dendrites of afferent neurons. Here, we examine the relative contributions of efferent action on hair cells and afferents. Experiments were performed in vivo in the oyster toadfish, Opsanus tau. The efferent system was activated via electrical pulses to the brain stem and sensory responses to motion stimuli were quantified by simultaneous voltage recording from afferents and intracellular current- and/or voltage-clamp recordings from hair cells. Results showed synaptic inputs to both afferents and hair cells leading to relatively long-latency intracellular signaling responses: excitatory in afferents and inhibitory in hair cells. Generally, the net effect of efferent action was an increase in afferent background discharge and a simultaneous decrease in gain to angular motion stimuli. Inhibition of hair cells was likely the result of a ligand-gated opening of a major basolateral conductance. The reversal potential of the efferent-evoked current was just below the hair cell resting potential, thus resulting in a small hyperpolarization. The onset latency averaged about 90 ms and latency to peak response was 150–400 ms. Hair cell inhibition often outlasted afferent excitation and, in some cases, latched hair cells in the “off” condition for >1 s following cessation of stimulus. These features endow the animal with a powerful means to adjust the sensitivity and dynamic range of motion sensation. PMID:19571186

  14. Integration of Semi-Circular Canal and Otolith Cues for Direction Discrimination during Eccentric Rotations

    PubMed Central

    Soyka, Florian; Bülthoff, Heinrich H.; Barnett-Cowan, Michael

    2015-01-01

    Humans are capable of moving about the world in complex ways. Every time we move, our self-motion must be detected and interpreted by the central nervous system in order to make appropriate sequential movements and informed decisions. The vestibular labyrinth consists of two unique sensory organs the semi-circular canals and the otoliths that are specialized to detect rotation and translation of the head, respectively. While thresholds for pure rotational and translational self-motion are well understood surprisingly little research has investigated the relative role of each organ on thresholds for more complex motion. Eccentric (off-center) rotations during which the participant faces away from the center of rotation stimulate both organs and are thus well suited for investigating integration of rotational and translational sensory information. Ten participants completed a psychophysical direction discrimination task for pure head-centered rotations, translations and eccentric rotations with 5 different radii. Discrimination thresholds for eccentric rotations reduced with increasing radii, indicating that additional tangential accelerations (which increase with radius length) increased sensitivity. Two competing models were used to predict the eccentric thresholds based on the pure rotation and translation thresholds: one assuming that information from the two organs is integrated in an optimal fashion and another assuming that motion discrimination is solved solely by relying on the sensor which is most strongly stimulated. Our findings clearly show that information from the two organs is integrated. However the measured thresholds for 3 of the 5 eccentric rotations are even more sensitive than predictions from the optimal integration model suggesting additional non-vestibular sources of information may be involved. PMID:26322782

  15. Efferent innervation of turtle semicircular canal cristae: comparisons with bird and mouse

    PubMed Central

    Jordan, Paivi M.; Fettis, Margaret; Holt, Joseph C.

    2014-01-01

    In the vestibular periphery of nearly every vertebrate, cholinergic vestibular efferent neurons give rise to numerous presynaptic varicosities that target hair cells and afferent processes in the sensory neuroepithelium. Although pharmacological studies have described the postsynaptic actions of vestibular efferent stimulation in several species, characterization of efferent innervation patterns and the relative distribution of efferent varicosities among hair cells and afferents are also integral to understanding how efferent synapses operate. Vestibular efferent markers, however, have not been well characterized in the turtle, one of the animal models utilized by our laboratory. Here, we sought to identify reliable efferent neuronal markers in the vestibular periphery of turtle, to utilize these markers to understand how efferent synapses are organized, and to compare efferent neuronal labeling patterns in turtle with two other amniotes using some of the same markers. Efferent fibers and varicosities were visualized in the semicircular canal of Red-Eared Turtles (Trachemys scripta elegans), Zebra Finches (Taeniopygia guttata), and mice (Mus musculus) utilizing fluorescent immunohistochemistry with antibodies against choline acetyltransferase (ChAT). Vestibular hair cells and afferents were counterstained using antibodies to myosin VIIa and calretinin. In all species, ChAT labeled a population of small diameter fibers giving rise to numerous spherical varicosities abutting type II hair cells and afferent processes. That these ChAT-positive varicosities represent presynaptic release sites were demonstrated by colabeling with antibodies against the synaptic vesicle proteins synapsin I, SV2, or syntaxin and the neuropeptide calcitonin gene-related peptide (CGRP). Comparisons of efferent innervation patterns among the three species are discussed. PMID:25560461

  16. Efferent innervation of turtle semicircular canal cristae: comparisons with bird and mouse.

    PubMed

    Jordan, Paivi M; Fettis, Margaret; Holt, Joseph C

    2015-06-01

    In the vestibular periphery of nearly every vertebrate, cholinergic vestibular efferent neurons give rise to numerous presynaptic varicosities that target hair cells and afferent processes in the sensory neuroepithelium. Although pharmacological studies have described the postsynaptic actions of vestibular efferent stimulation in several species, characterization of efferent innervation patterns and the relative distribution of efferent varicosities among hair cells and afferents are also integral to understanding how efferent synapses operate. Vestibular efferent markers, however, have not been well characterized in the turtle, one of the animal models used by our laboratory. Here we sought to identify reliable efferent neuronal markers in the vestibular periphery of turtle, to use these markers to understand how efferent synapses are organized, and to compare efferent neuronal labeling patterns in turtle with two other amniotes using some of the same markers. Efferent fibers and varicosities were visualized in the semicircular canal of red-eared turtles (Trachemys scripta elegans), zebra finches (Taeniopygia guttata), and mice (Mus musculus) utilizing fluorescent immunohistochemistry with antibodies against choline acetyltransferase (ChAT). Vestibular hair cells and afferents were counterstained using antibodies to myosin VIIa and calretinin. In all species, ChAT labeled a population of small diameter fibers giving rise to numerous spherical varicosities abutting type II hair cells and afferent processes. That these ChAT-positive varicosities represent presynaptic release sites were demonstrated by colabeling with antibodies against the synaptic vesicle proteins synapsin I, SV2, or syntaxin and the neuropeptide calcitonin gene-related peptide. Comparisons of efferent innervation patterns among the three species are discussed. PMID:25560461

  17. Response of semicircular canal dependent units in vestibular nuclei to rotation of a linear acceleration vector without angular acceleration

    PubMed Central

    Benson, A. J.; Guedry, F. E.; Jones, G. Melvill

    1970-01-01

    1. Recent experiments have shown that rotation of a linear acceleration vector round the head can generate involuntary ocular nystagmus in the absence of angular acceleration. The present experiments examine the suggestion that adequate stimulation of the semicircular canals may contribute to this response. 2. Decerebrate cats were located in a stereotaxic device on a platform, slung from four parallel cables, which could be driven smoothly round a circular orbit without inducing significant angular movement of the platform. This Parallel Swing Rotation (PSR) generated a centripetal acceleration of 4·4 m/sec2 which rotated round the head at 0·52 rev/sec. 3. The discharge frequency of specifically lateral canal-dependent neural units in the vestibular nuclei of cats was recorded during PSR to right and left, and in the absence of motion. The dynamic responses to purely angular motion were also examined on a servo-driven turntable. 4. Without exception all proven canal-dependent cells examined (twenty-nine cells in nine cats) were more active during PSR in the direction of endolymph circulation assessed to be excitatory to the unit, than during PSR in the opposite direction. 5. The observed changes in discharge frequency are assessed to have been of a magnitude appropriate for the generation of the involuntary oculomotor response induced by the same stimulus in the intact animal. 6. The findings suggest that a linear acceleration vector which rotates in the plane of the lateral semicircular canals can be an adequate stimulus to ampullary receptors, though an explanation which invokes the modulation of canal cells by a signal dependent upon the sequential activation of macular receptors cannot be positively excluded. PMID:5501270

  18. Superior-semicircular-canal dehiscence: effects of location, shape, and size on sound conduction.

    PubMed

    Kim, Namkeun; Steele, Charles R; Puria, Sunil

    2013-07-01

    The effects of a superior-semicircular-canal (SSC) dehiscence (SSCD) on hearing sensitivity via the air-conduction (AC) and bone-conduction (BC) pathways were investigated using a three-dimensional finite-element (FE) model of a human middle ear coupled to the inner ear. Dehiscences were modeled by removing a section of the outer bony wall of the SSC and applying a zero-pressure condition to the fluid surface thus exposed. At each frequency, the basilar-membrane velocity, vBM, was separately calculated for AC and BC stimulation, under both pre- and post-dehiscence conditions. Hearing loss was calculated as the difference in the maximum magnitudes of vBM between the pre- and post-dehiscence conditions representing a change in hearing threshold. In this study, BC excitations were simulated by applying rigid-body vibrations to the model along the directions of the (arbitrarily defined) x, y, and z axes of the model. Simulation results are consistent with previous clinical measurements on patients with an SSCD and with results from earlier lumped-element electrical-circuit modeling studies, with the dehiscence decreasing the hearing threshold (i.e., increasing vBM) by about 35 dB for BC excitation at low frequencies, while for AC excitation the dehiscence increases the hearing threshold (i.e., decreases vBM) by about 15 dB. A new finding from this study is that the initial width (defined as the width of the edge of the dehiscence where the flow of the fluid-motion wave from the oval window meets it for the first time) on the vestibular side of the dehiscence has more of an effect on vBM than the area of the dehiscence. Analyses of dehiscence effects using the FE model further predict that changing the direction of the BC excitation should have an effect on vBM, with vBM being about 20 dB lower due to BC excitation parallel to the longitudinal direction of the BM in the hook region (the x direction) as compared to excitations in other directions (y and z). BC excitation

  19. Superior semicircular canal dehiscence syndrome as assessed by oVEMP and temporal bone computed tomography imaging.

    PubMed

    Thabet, Elsaeid M; Abdelkhalek, Ahmad; Zaghloul, Hesham

    2012-05-01

    To evaluate the role of oVEMP and multidetector CT scan in patients with superior canal dehiscence syndrome. Prospective study was conducted on nine patients with superior canal dehiscence syndrome (5 females, 4 males) age ranged 19-49 with mean age of 32.7 ± 9.3 years, complaining of intolerance to loud sounds and/or oscillopsia. The mean duration of illness was 18.7 ± 6.9 months, nine normal individuals as control (age and gender matched) were also included in the study. All of them underwent oVEMP and MDCT scan. Patients were of bilateral normal hearing sensitivity with no conductive impairment. All of the studied subjects (patients and controls) had identifiable contralateral oVEMP responses. MDCT scan showed dehiscence in all the patients. The dehiscence was unilateral (n = 7) and bilateral [n = 2 the other ear had a defect of 2 mm and thus was excluded from the study for fear or false diagnosis of Superior semicircular canal dehiscence syndrome (SCDS)]. Unlike the normal subject (nI = 0.94 µV ± 0.03 and pI = -0.42 µV ± 0.09), with stimulation of the affected side in SCDS, there were augmented amplitude responses (nI = 2.64 µV ± 0.35 and pI = -3.10 µV ± 0.44) in the eye contralateral to the stimulus "contralateral to the lesion". Mean oVEMP threshold for SCDS ears were 82.5 ± 7.55 dBnHL compared to 100 ± 5.77 dBnHL of the control ears. We concluded that combination of physiological and anatomical information from oVEMP and MDCT increased accuracy for diagnosis of dehiscence of superior semicircular canal. PMID:22193872

  20. A Multi-channel Semicircular Canal Neural Prosthesis Using Electrical Stimulation to Restore 3D Vestibular Sensation

    PubMed Central

    Della Santina, Charles C.; Migliaccio, Americo A.; Patel, Amit H.

    2009-01-01

    Bilateral loss of vestibular sensation can be disabling. Those afflicted suffer illusory visual field movement during head movements, chronic disequilibrium and postural instability due to failure of vestibulo-ocular and vestibulo-spinal reflexes. A neural prosthesis that emulates the normal transduction of head rotation by semicircular canals could significantly improve quality of life for these patients. Like the 3 semicircular canals in a normal ear, such a device should at least transduce 3 orthogonal (or linearly separable) components of head rotation into activity on corresponding ampullary branches of the vestibular nerve. We describe the design, circuit performance and in vivo application of a head-mounted, semi-implantable multi-channel vestibular prosthesis that encodes head movement in 3 dimensions as pulse-frequency-modulated electrical stimulation of 3 or more ampullary nerves. In chinchillas treated with intratympanic gentamicin to ablate vestibular sensation bilaterally, prosthetic stimuli elicited a partly compensatory angular vestibulo-ocular reflex in multiple planes. Minimizing misalignment between the axis of eye and head rotation, apparently caused by current spread beyond each electrode’s targeted nerve branch, emerged as a key challenge. Increasing stimulation selectivity via improvements in electrode design, surgical technique and stimulus protocol will likely be required to restore AVOR function over the full range of normal behavior. PMID:17554821

  1. Horizontal canal benign paroxysmal positional vertigo: diagnosis and treatment of 37 patients.

    PubMed

    Maranhão, Eliana Teixeira; Maranhão Filho, Péricles

    2015-06-01

    Benign paroxysmal positional vertigo (BPPV), the most frequent cause of vertigo is associated with high morbidity in the elderly population. The most common form is linked to debris in the posterior semicircular canal. However, there has been an increasing number of reported BPPV cases involving the horizontal canals. The purpose of this article is to highlight the clinical features, diagnosis, and treatment in 37 patients with horizontal canal BPPV; twenty-six with geotropic nystagmus, and eleven with the apogeotropic form. Treatment consisted of the Gufoni manoeuver in eighteen patients (48.6%), the barbecue 360° maneuver in twelve patients (32.4%), both manoeuvers in four patients (10.8%), both manoeuvers plus head shaking in one patient (2.7%), and the Gufoni maneuver plus head shaking in two patients. Cupulolithiasis patients were asked to sleep in a forced prolonged position. We obtained a complete resolution of vertigo and nystagmus in 30 patients (81.0%) on the initial visit. PMID:26083883

  2. Temporal dynamics of semicircular canal and otolith function following acute unilateral vestibular deafferentation in humans.

    PubMed

    Tian, Jun-ru; Ishiyama, Akira; Demer, Joseph L

    2007-04-01

    Dynamic changes of deficits in canal and otolith vestibulo-ocular reflexes (VORs) to high acceleration, eccentric yaw rotations were investigated in five subjects aged 25-65 years before and at frequent intervals 3-451 days following unilateral vestibular deafferentation (UVD) due to labyrinthectomy or vestibular neurectomy. Eye and head movements were recorded using magnetic search coils during transients of directionally random, whole-body rotation in darkness at peak acceleration 2,800 degrees/s2. Canal VORs were characterized during rotation about a mid-otolith axis, viewing a target 500 cm distant until rotation onset in darkness. Otolith VOR responses were characterized by the increase in VOR gain during identical rotation about an axis 13 cm posterior to the otoliths, initially viewing a target 15 cm distant. Pre-UVD canal gain was directionally symmetrical, averaging 0.87 +/- 0.02 (+/-SEM). Contralesional canal gain declined from pre-UVD by an average of 22% in the first 3-5 days post-UVD, before recovering to an asymptote of close 90% of pre-UVD level at 1-3 months. This recovery corresponded to resolution of spontaneous nystagmus. Ipsilesional gain declined to 59%, and showed no consistent recovery afterwards. Pre-UVD otolith gain was directionally symmetrical, averaging 0.56 +/- 0.02. Immediately after UVD, the contralesional otolith gain declined to 0.30 +/- 0.02, and did not recover. Ipsilesional otolith gain declined profoundly to 0.08 +/- 0.03 (P < 0.01), and never recovered. In contrast to the modest and directionally symmetrical effect of UVD on the human otolith VOR during pure translational acceleration, otolith gain during eccentric yaw rotation exhibited a profound and lasting deficit that might be diagnostically useful in lateralizing otolith pathology. Most recovery of the human canal gain to high acceleration transients following UVD is for contralesional head rotation, occurring within 3 months as spontaneous nystagmus resolves. PMID

  3. Semicircular canal morphogenesis in the zebrafish inner ear requires the function of gpr126 (lauscher), an adhesion class G protein-coupled receptor gene

    PubMed Central

    Geng, Fan-Suo; Abbas, Leila; Baxendale, Sarah; Holdsworth, Celia J.; Swanson, A. George; Slanchev, Krasimir; Hammerschmidt, Matthias; Topczewski, Jacek; Whitfield, Tanya T.

    2013-01-01

    Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression. PMID:24067352

  4. Calcium current in type I hair cells isolated from the semicircular canal crista ampullaris of the rat.

    PubMed

    Almanza, Angélica; Vega, Rosario; Soto, Enrique

    2003-12-24

    The low voltage gain in type I hair cells implies that neurotransmitter release at their afferent synapse should be mediated by low voltage activated calcium channels, or that some peculiar mechanism should be operating in this synapse. With the patch clamp technique, we studied the characteristics of the Ca(2+) current in type I hair cells enzymatically dissociated from rat semicircular canal crista ampullaris. Calcium current in type I hair cells exhibited a slow inactivation (during 2-s depolarizing steps), was sensitive to nimodipine and was blocked by Cd(2+) and Ni(2+). This current was activated at potentials above -60 mV, had a mean half maximal activation of -36 mV, and exhibited no steady-state inactivation at holding potentials between -100 and -60 mV. This data led us to conclude that hair cell Ca(2+) current is most likely of the L type. Thus, other mechanisms participating in neurotransmitter release such as K(+) accumulation in the synaptic cleft, modulation of K(+) currents by nitric oxide, participation of a Na(+) current and possible metabotropic cascades activated by depolarization should be considered. PMID:14642642

  5. Numerical simulation of the role of the utriculo-endolymphatic valve in the rotation-sensing capabilities of semicircular canals.

    PubMed

    Shen, Shuang; Sun, Xiuzhen; Yu, Shen; Liu, Yingxi; Su, Yingfeng; Zhao, Wei; Liu, Wenlong

    2016-06-14

    The utriculo-endolymphatic valve (UEV) has an uncertain function, but its opening and closure have been predicted to maintain a constant endolymphatic pressure within the semicircular canals (SCCs) and the utricle of the inner ear. Here, the study׳s aim was to examine the role of the UEV in regulating the capabilities of the 3 SCCs in sensing angular acceleration by using the finite element method. The results of the developed model showed endolymphatic flow and cupula displacement patterns in good agreement with previous experiments. Moreover, the open valve was predicted to permit endolymph exchange between the 2 parts of the membranous labyrinth during head rotation and, in comparison to the closed valve, to result in a reinforced endolymph flow in the utricle and an enhanced or weakened cupula deflection. Further, the model predicted an increase in the size of the orifice would result in greater endolymph exchange and thereby to a greater impact on cupula deflection. The model findings suggest the UEV plays a crucial role in the preservation of inner ear sensory function. PMID:27059257

  6. Upper third molar internal structural organization and semicircular canal morphology in Plio-Pleistocene South African cercopithecoids.

    PubMed

    Beaudet, Amélie; Dumoncel, Jean; Thackeray, John Francis; Bruxelles, Laurent; Duployer, Benjamin; Tenailleau, Christophe; Bam, Lunga; Hoffman, Jakobus; de Beer, Frikkie; Braga, José

    2016-06-01

    Despite the abundance of cercopithecoids in the fossil record, especially in South Africa, and the recent development of morphometric approaches, uncertainties regarding the taxonomic identification of isolated cranio-dental specimens remain. Because cercopithecoids, nearly always found in stratigraphic association with hominin remains in Plio-Pleistocene deposits, are considered as sensitive ecological and chronological biomarkers, a significant effort should be made to clarify their palaeobiodiversity by assessing additional reliable morphological diagnostic criteria. Here we test the relevance of both molar crown internal structure and bony labyrinth morphology for discrimination of fossil cercopithecoid species. We use microtomographic-based 3D virtual imaging and quantitative analyses to investigate tooth endostructural organization and inner ear shape in 29 craniodental specimens from the South African sites of Kromdraai, Makapansgat, Sterkfontein and Swartkrans and provide the first detailed description of the internal structural condition characterizing this Plio-Pleistocene primate assemblage. Our preliminary results show that enamel-dentine junction morphology could be informative for discriminating highly autapomorphic taxa such as Theropithecus, while semicircular canal shape is tentatively proposed as an efficient criterion for diagnosing Dinopithecus ingens. Further research in virtual paleoprimatology may contribute to the identification of unassigned isolated fossil remains and shed new light on the internal craniodental morphology of extinct primate taxa. PMID:27260177

  7. Power Reflectance as a Screening Tool for the Diagnosis of Superior Semicircular Canal Dehiscence

    PubMed Central

    Merchant, Gabrielle R.; Röösli, Christof; Niesten, Marlien E. F.; Hamade, Mohamad A.; Lee, Daniel J.; McKinnon, Melissa L.; Ulku, Cagatay H.; Rosowski, John J.; Merchant, Saumil N.; Nakajima, Hideko Heidi

    2014-01-01

    Hypothesis Power reflectance (PR) measurements in ears with Superior Canal Dehiscence (SCD) have a characteristic pattern, whose detection can assist in diagnosis. Background The aim of this study is to determine if PR coupled with a novel detection algorithm can perform well as a fast, non-invasive, and easy screening test for SCD. The screening test is to determine if patients with various vestibular and/or auditory symptom(s) should be further considered for more expensive and invasive tests that better define the diagnosis of SCD (and other third-window lesions). Methods PR was measured in patients diagnosed with SCD by high-resolution CT. The study included 40 ears from 32 patients with varying symptoms (e.g., with and without conductive hearing loss, vestibular symptoms, and abnormal auditory sensations). Results PR results were compared to previously published norms, and showed that SCD is commonly associated with a PR notch near 1 kHz. An analysis algorithm was designed to detect such notches and to quantify their incidence in affected and normal ears. Various notch detection thresholds yielded sensitivities of 80%–93%, specificities of 69%–72%, negative predictive value of 84%–93% and positive predictive value of 67%. Conclusion This study shows evidence that PR measurements together with the proposed notch-detecting algorithm can be used to quickly and effectively screen patients for third-window lesions such as SCD in the early stages of a diagnostic workup. PMID:25076227

  8. The variability of inner ear orientation in saurischian dinosaurs: testing the use of semicircular canals as a reference system for comparative anatomy.

    PubMed

    Marugán-Lobón, Jesús; Chiappe, Luis M; Farke, Andrew A

    2013-01-01

    The vestibular system of the inner ear houses three semicircular canals-oriented on three nearly-orthogonal planes-that respond to angular acceleration stimuli. In recent years, the orientation of the lateral semicircular canal (LSC) has been regularly used to determine skull orientations for comparative purposes in studies of non-avian dinosaurs. Such orientations have been inferred based on fixing the LSC to a common set of coordinates (parallel to the Earth's horizon), given that the orientation to gravity of this sensory system is assumed constant among taxa. Under this assumption, the LSC is used as a baseline (a reference system) both to estimate how the animals held their heads and to describe craniofacial variation among dinosaurs. However, the available data in living birds (extant saurischian dinosaurs) suggests that the orientation of the LSC in non-avian saurischian dinosaurs could have been very variable and taxon-specific. If such were the case, using the LSC as a comparative reference system would cause inappropriate visual perceptions of craniofacial organization, leading to significant descriptive inconsistencies among taxa. Here, we used Procrustes methods (Geometric Morphometrics), a suite of analytical tools that compares morphology on the basis of shared landmark homology, to show that the variability of LSC relative to skull landmarks is large (ca. 50°) and likely unpredictable, thus making it an inconsistent reference system for comparing and describing the skulls of saurischian (sauropodomorph and theropod) dinosaurs. In light of our results, the lateral semicircular canal is an inconsistent baseline for comparative studies of craniofacial morphology in dinosaurs. PMID:23940837

  9. Major potassium conductance in type I hair cells from rat semicircular canals: characterization and modulation by nitric oxide.

    PubMed

    Chen, J W; Eatock, R A

    2000-07-01

    Mammalian vestibular organs have two types of hair cell, type I and type II, which differ morphologically and electrophysiologically. Type I hair cells alone express an outwardly rectifying current, I(K, L), which activates at relatively negative voltages. We used whole cell and patch configurations to study I(K,L) in hair cells isolated from the sensory epithelia of rat semicircular canals. I(K,L) was potassium selective, blocked by 4-aminopyridine, and permeable to internal cesium. It activated with sigmoidal kinetics and was half-maximally activated at -74.5 +/- 1.6 mV (n = 35; range -91 to -50 mV). It was a very large conductance (91 +/- 8 nS at -37 mV; 35 nS/pF for a cell of average size). Patch recordings from type I cells revealed a candidate ion channel with a conductance of 20-30 pS. Because I(K,L) was activated at the resting potential, the cells had low input resistances (R(m)): median 25 MOmega at -67 mV versus 1.3 GOmega for type II cells. Consequently, injected currents comparable to large transduction currents (300 pA) evoked small (

  10. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. II. Responses after canal plugging

    NASA Technical Reports Server (NTRS)

    Lasker, D. M.; Backous, D. D.; Lysakowski, A.; Davis, G. L.; Minor, L. B.

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral plugging of the three semicircular canals. During the period (1-4 days) that animals were kept in darkness after plugging, the gain during steps of acceleration (3, 000 degrees /s(2), peak velocity = 150 degrees /s) was 0.61 +/- 0.14 (mean +/- SD) for contralesional rotations and 0.33 +/- 0.03 for ipsilesional rotations. Within 18-24 h after animals were returned to light, the VOR gain for contralesional rotations increased to 0. 88 +/- 0.05, whereas there was only a slight increase in the gain for ipsilesional rotations to 0.37 +/- 0.07. A symmetrical increase in the gain measured at the plateau of head velocity was noted after animals were returned to light. The latency of the VOR was 8.2 +/- 0. 4 ms for ipsilesional and 7.1 +/- 0.3 ms for contralesional rotations. The VOR evoked by sinusoidal rotations of 0.5-15 Hz, +/-20 degrees /s had no significant half-cycle asymmetries. The recovery of gain for these responses after plugging was greater at lower than at higher frequencies. Responses to rotations at higher velocities for frequencies >/=4 Hz showed an increase in contralesional half-cycle gain, whereas ipsilesional half-cycle gain was unchanged. A residual response that appeared to be canal and not otolith mediated was noted after plugging of all six semicircular canals. This response increased with frequency to reach a gain of 0.23 +/- 0.03 at 15 Hz, resembling that predicted based on a reduction of the dominant time constant of the canal to 32 ms after plugging. A model incorporating linear and nonlinear pathways was used to simulate the data. The coefficients of this model were determined from data in animals with intact vestibular function. Selective increases in the gain for the linear and nonlinear pathways predicted the changes in recovery observed after canal plugging. An increase in gain of

  11. Long-term results of middle fossa plugging of superior semicircular canal dehiscences: clinically and instrumentally demonstrated efficiency in a retrospective series of 16 ears.

    PubMed

    Thomeer, Hans; Bonnard, Damien; Castetbon, Vincent; Franco-Vidal, Valérie; Darrouzet, Patricia; Darrouzet, Vincent

    2016-07-01

    The objective of this study is to report the surgical outcome after middle fossa approach (MFA) plugging in patients suffering from a superior semi-circular canal dehiscence (SCD) syndrome. This is a retrospective case review. Tertiary referral center. Sixteen ears in 13 patients with a SCD syndrome suffering from severe and disabling vestibular symptoms with a bony dehiscence on CT scan >3 mm and decreased threshold of cervical vestibular evoked potentials (cVEMPs). We assessed preoperatively: clinical symptoms, hearing, cVEMPs threshold, size of dehiscence and videonystagmography (VNG) with caloric and 100 Hz vibratory tests. Postoperatively, we noted occurrences of neurosurgical complication, evolution of audiological and vestibular symptoms, and evaluation of cVEMP data. Tullio's phenomenon was observed in 13 cases (81.3 %) and subjectively reported hearing loss in seven (43.7 %). All patients were so disabled that they had to stop working. No neurosurgical complications were observed in the postoperative course. In three cases (16.6 %), an ipsilateral and transitory immediate postoperative vestibular deficit associated with a sensorineural hearing loss (SNHL) was noted, which totally resolved with steroids and bed rest. All patients were relieved of audiological and vestibular symptoms and could return to normal activity with a mean follow-up of 31.1 months (range 3-95). No patient had residual SNHL. cVEMPs were performed in 14 ears postoperatively and were normalized in 12 (85.7 %). Two of the three patients operated on both sides kept some degree of unsteadiness and oscillopsia. MFA plugging of the superior semi-circular canal is an efficient and non-hearing deteriorating procedure. PMID:26205152

  12. Efficacy of cervical and ocular vestibular-evoked myogenic potentials in evaluation of benign paroxysmal positional vertigo of posterior semicircular canal.

    PubMed

    Singh, Niraj Kumar; Apeksha, Kumari

    2016-09-01

    Benign paroxysmal positional vertigo (BPPV) constitutes a major proportion of the population with peripheral vestibulopathies. Although the freely floating otoconia within the semicircular canals is responsible for the symptoms of BPPV, the source of the otoconia debris is mainly believed to be the otolith organs. Therefore, the pathology in either or both the otolith organs appears a logical proposition. Cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP), being the tests for functional integrity of the otolith organs, appear promising for investigating otolith involvement in BPPV. While recent evidences are suggestive of equivocal findings for cVEMP, there are only a few studies on oVEMP. Additionally, both these potentials have never been explored in the same set of individuals with BPPV. Therefore, the present study aimed to evaluate the functional integrity of the otolith organs through cVEMP and oVEMP in individuals with posterior canal BPPV. Thirty-one individuals with unilateral posterior canal BPPV and 31 age- and gender-matched healthy controls underwent 500 Hz tone-burst-evoked cVEMP and oVEMP. The results demonstrated no significant group difference on any of the cVEMP parameters (p > 0.05). A similar trend was noticed for the latency-related parameters of oVEMP. However, the peak-to-peak amplitude was significantly smaller in the affected ears of individuals with BPPV than their unaffected ears and the ears of healthy controls (p < 0.05). The BPPV group showed significantly higher inter-aural amplitude difference ratio than the healthy controls (p < 0.05). Further, the sensitivity and specificity of oVEMP were also found to be far superior to those of cVEMP. Thus, the outcome of the present study revealed involvement of utricle rather than saccule in posterior canal BPPV, and therefore, oVEMP appears to be better suited to clinical investigation than cVEMP in individuals with posterior canal BPPV. PMID:26718546

  13. The correlated blanching of synaptic bodies and reduction in afferent firing rates caused by transmitter-depleting agents in the frog semicircular canal

    NASA Technical Reports Server (NTRS)

    Guth, P.; Norris, C.; Fermin, C. D.; Pantoja, M.

    1993-01-01

    Synaptic bodies (SBs) associated with rings of synaptic vesicles and well-defined, pre- and post-synaptic membrane structures are indicators of maturity in most hair cell-afferent nerve junctions. The role of the SBs remains elusive despite several experiments showing that they may be involved in storage of neurotransmitter. Our results demonstrate that SBs of the adult posterior semicircular canal (SCC) cristae hair cells become less electron dense following incubation of the SCC with the transmitter-depleting drug tetrabenazine (TBZ). Objective quantification and comparison of the densities of the SBs in untreated and TBZ-treated frog SCC demonstrated that TBZ significantly decreased the electron density of SBs. This reduction in electron density was accompanied by a reduction in firing rates of afferent fibers innervating the posterior SCC. A second transmitter-depleting drug, guanethidine, previously shown to reduce the electron density of hair cell SBs, also reduced the firing rates of afferent fibers innervating the posterior SCC. In contrast, the electron density of dense granules (DG), similar in size and shape to synaptic bodies (SB) in hair cells, did not change after incubation in TBZ, thus indicating that granules and SBs are not similar in regard to their electron density. The role of SBs in synaptic transmission and the transmitter, if any, stored in the SBs remain unknown. Nonetheless, the association of the lessening of electron density with a reduction in afferent firing rate provides impetus for the further investigation of the SB's role in neurotransmission.

  14. Neural processing of gravito-inertial cues in humans. II. Influence of the semicircular canals during eccentric rotation.

    PubMed

    Merfeld, D M; Zupan, L H; Gifford, C A

    2001-04-01

    All linear accelerometers, including the otolith organs, respond equivalently to gravity and linear acceleration. To investigate how the nervous system resolves this ambiguity, we measured perceived roll tilt and reflexive eye movements in humans in the dark using two different centrifugation motion paradigms (fixed radius and variable radius) combined with two different subject orientations (facing-motion and back-to-motion). In the fixed radius trials, the radius at which the subject was seated was held constant while the rotation speed was changed to yield changes in the centrifugal force. In variable radius trials, the rotation speed was held constant while the radius was varied to yield a centrifugal force that nearly duplicated that measured during the fixed radius condition. The total gravito-inertial force (GIF) measured by the otolith organs was nearly identical in the two paradigms; the primary difference was the presence (fixed radius) or absence (variable radius) of yaw rotational cues. We found that the yaw rotational cues had a large statistically significant effect on the time course of perceived tilt, demonstrating that yaw rotational cues contribute substantially to the neural processing of roll tilt. We also found that the orientation of the subject relative to the centripetal acceleration had a dramatic influence on the eye movements measured during fixed radius centrifugation. Specifically, the horizontal vestibuloocular reflex (VOR) measured in our human subjects was always greater when the subject faced the direction of motion than when the subjects had their backs toward the motion during fixed radius rotation. This difference was consistent with the presence of a horizontal translational VOR response induced by the centripetal acceleration. Most importantly, by comparing the perceptual tilt responses to the eye movement responses, we found that the translational VOR component decayed as the subjective tilt indication aligned with the tilt of

  15. Superior Semicircular Canal Dehiscence (SSCD)

    MedlinePlus

    ... content Facebook Twitter LinkedIn Pinterest About Contact FAQ Vestibular Disorders Association Login Donate Now Subscribe To V-newS Main menu About Vestibular Disorders Educational Resources Finding Help & Support Resources for ...

  16. Canals

    ERIC Educational Resources Information Center

    Winkleman, Michael

    1974-01-01

    In the mid-1800's, the canal system in the U.S. was thriving. But, by the end of that century, roads and railways had replaced these commercial thoroughfares. Renewed interest in the abandoned canals is now resulting in renovation and ecological site development in Pennsylvania and New Jersey. (MA)

  17. [Benign paroxysmal positional vertigo. Differential diagnosis of posterior, horizontal and anterior canalolithiasis].

    PubMed

    Steddin, S; Brandt, T

    1994-08-01

    Evidence is presented that all typical features of benign paroxysmal positioning vertigo can be explained by canalolithiasis rather than by cupulolithiasis. A free floating clot of "heavy" inorganic particles gravitates to the most dependent part of the canal as soon as the patient's head is moved in a way that alters the angle between the canal's plane and the gravity vector. Based on the canalolithiasis mechanism we describe how characteristics of the thus elicited nystagmus differ if the posterior, the horizontal or the anterior semicircular canal is causative. PMID:7969646

  18. Visual-vestibular interaction in humans during earth-horizontal axis rotation

    NASA Technical Reports Server (NTRS)

    Wall, Conrad, III; Furman, Joseph M. R.

    1990-01-01

    Visual-vestibular interaction using 60 percent constant velocity earth horizontal axis yaw rotation, simulating both the horizontal semicircular canals and the otolith organs, was measured in seven human subjects. Subjects were tested with their eyes open in the dark (EOD) while fixating upon a target rotating with them (FIX), and while observing stationary optokinetic stripes (VVR). Resulting nystagmus slow component velocity (SCV) was analyzed for EOD, FIX, and VVR conditions. It is concluded that the visual-vestibular interactions during EHA differ significantly from those during rotation about the vertical; specifically, there is a nonlinear interaction between linear acceleration and optokinetic nystagmus.

  19. Two major cuticular proteins are required for assembly of horizontal laminae and vertical pore canals in rigid cuticle of Tribolium castaneum.

    PubMed

    Noh, Mi Young; Kramer, Karl J; Muthukrishnan, Subbaratnam; Kanost, Michael R; Beeman, Richard W; Arakane, Yasuyuki

    2014-10-01

    The insect exoskeleton is composed of cuticle primarily formed from structural cuticular proteins (CPs) and the polysaccharide chitin. Two CPs, TcCPR27 and TcCPR18, are major proteins present in the elytron (highly sclerotized and pigmented modified forewing) as well as the pronotum (dorsal sclerite of the prothorax) and ventral abdominal cuticle of the red flour beetle, Tribolium castaneum. Both CPs belong to the CPR family, which includes proteins that have an amino acid sequence motif known as the Rebers & Riddiford (R&R) consensus sequence. Injection of double-stranded RNA (dsRNA) for TcCPR27 and TcCPR18 resulted in insects with shorter, wrinkled, warped and less rigid elytra than those from control insects. To gain a more comprehensive understanding of the roles of CPs in cuticle assembly, we analyzed for the precise localization of TcCPR27 and the ultrastructural architecture of cuticle in TcCPR27- and TcCPR18-deficient elytra. Transmission electron microscopic analysis combined with immunodetection using gold-labeled secondary antibody revealed that TcCPR27 is present in dorsal elytral procuticle both in the horizontal laminae and in vertical pore canals. dsRNA-mediated RNA interference (RNAi) of TcCPR27 resulted in abnormal electron-lucent laminae and pore canals in elytra except for the boundary between these two structures in which electron-dense molecule(s) apparently accumulated. Insects subjected to RNAi for TcCPR18 also had disorganized laminae and pore canals in the procuticle of elytra. Similar ultrastructural defects were also observed in other body wall regions with rigid cuticle such as the thorax and legs of adult T. castaneum. TcCPR27 and TcCPR18 are required for proper formation of the horizontal chitinous laminae and vertical pore canals that are critical for formation and stabilization of rigid adult cuticle. PMID:25042128

  20. Algorithm of semicircular laser spot detection based on circle fitting

    NASA Astrophysics Data System (ADS)

    Wang, Zhengzhou; Xu, Ruihua; Hu, Bingliang

    2013-07-01

    In order to obtain the exact center of an asymmetrical and semicircular aperture laser spot, a method for laser spot detection method based on circle fitting was proposed in this paper, threshold of laser spot image was segmented by the method of gray morphology algorithm, rough edge of laser spot was detected in both vertical and horizontal direction, short arcs and isolated edge points were deleted by contour growing, the best circle contour was obtained by iterative fitting and the final standard round was fitted in the end. The experimental results show that the precision of the method is obviously better than the gravity model method being used in the traditional large laser automatic alignment system. The accuracy of the method to achieve asymmetrical and semicircular laser spot center meets the requirements of the system.

  1. Vertical eye movements during horizontal head impulse test: a new clinical sign of superior vestibular neuritis.

    PubMed

    D'Onofrio, F

    2013-12-01

    In some patients suffering from acute unilateral peripheral vestibular deficit, the head impulse test performed towards the affected side reveals the typical catch-up saccade in the horizontal plane, and an oblique, mostly vertical, upward catch-up saccade after the rotation of the head towards the healthy side. Three cases are reported herein, which have been studied using slow motion video analysis of the eye movements captured by a high-speed webcam (90 fps). The clinical evidence is discussed and a pathophysiological explanation is proposed, consisting in a selective hypofunction of the superior semicircular canal during superior vestibular neuritis. PMID:24376299

  2. Earth horizontal axis rotational responses in patients with unilateral peripheral vestibular deficits

    NASA Technical Reports Server (NTRS)

    Furman, Joseph M. R.; Kamerer, Donald B.; Wall, Conrad, III

    1989-01-01

    The vestibulo-ocular reflex (VOR) of five patients with surgically confirmed unilateral peripheral vestibular lesions is evaluated. Testing used both earth vertical axis (EVA) and earth horizontal axis (EHA) yaw rotation. Results indicated that the patients had short VOR time constants, asymmetric responses to both EVA and EHA rotation, and normal EHA modulation components. These findings suggest that unilateral peripheral vestibular loss causes a shortened VOR time constant even with the addition of dynamic otolithic stimulation and causes an asymmetry in semicircular canal-ocular reflexes and one aspect of otolith-ocular reflexes.

  3. Canal and otolith vestibulo-ocular reflexes to vertical and off vertical axis rotations in children learning to walk.

    PubMed

    Wiener-Vacher, S R; Toupet, F; Narcy, P

    1996-09-01

    In order to determine the characteristics of the vestibulo-ocular reflexes (VORs) as a function of age and posturo-motor development, a group of 26 normal children (6 to 25 months old) were tested at three different stages of posturo-motor control: prior to as well as during the first attempts to walk without support, and during the first year of independent walking. The test consisted of electro-oculographic (EOG) recordings of the VOR responses to horizontal semi-circular canal and otolith stimulations. The canal VOR was elicited in seated subjects by rotatory impulsions about a vertical axis (acceleration and deceleration both at 40 degrees/s2, separated by a rotation at 60 degrees/s velocity). The otolith VOR was elicited by inclining the rotating chair by 9 degrees respect to gravity. For the canal VOR, the time constant and the highest initial slow phase velocity were measured. The otolith VOR was characterized by the amplitude of the modulation and the bias (offset of baseline from zero) of the slow phase velocity averaged over 10 to 20 rotation cycles, for both the horizontal and vertical components of the response. The pooled values of these data show that canal VOR parameters did not vary significantly either with age of the children or with their stage of posturo-motor control. However, the otolith VOR parameters changed during the period of learning to walk: the modulation of the horizontal component increased and the modulation of the vertical component decreased significantly. Thus the ability to walk without support is marked by a significant change in the otolith but not canal responses; since the vestibular sensory organs develop anatomically at the same rate these results indicate that central nervous system processors of canal and otolith information develop independently. PMID:8908240

  4. Micromotional studies of utricular and canal afferents

    NASA Technical Reports Server (NTRS)

    Lewis, Edwin R.

    1989-01-01

    The long-range goal of this research was to refine our understanding of the sensitivity of the vestibular components of the ear to very-low-amplitude motion, especially, the role of gravity in this sensitivity. We focused on the American bullfrog--a common animal subject for vestibular sensory research. Our principal experimental method was to apply precise, sinusoidal microrotational stimuli to an anesthetized animal subject, to record the resulting responses in an individual vestibular nerve fiber from the intact ear, and to use intracellular dye to trace the fiber and thus identify the vestibular sensor that gave rise to it. In this way, we were able to identify specific micromotional sensitivities and to associate those sensitivities definitely with specific sensors. Furthermore, by recording from nerve fibers after they leave the intact inner-ear cavity, we were able to achieve these identifications without interrupting the delicate micromechanics of the inner ear. We were especially concerned with the relative roles of the utricle and the anterior semicircular canal in the sensing of microrotational motion of the head about horizontal axes, and with the role of gravity in mediating that sensing process in the utricle. The functional characterization of individual nerve fibers was accomplished with a conventional analytical tool, the cycle histogram, in which the nerve impulse rate was plotted against the phase of the sinusoidal stimulus.

  5. User manual for semi-circular compact range reflector code: Version 2

    NASA Technical Reports Server (NTRS)

    Gupta, Inder J.; Burnside, Walter D.

    1987-01-01

    A computer code has been developed at the Ohio State University ElectroScience Laboratory to analyze a semi-circular paraboloidal reflector with or without a rolled edge at the top and a skirt at the bottom. The code can be used to compute the total near field of the reflector or its individual components at a given distance from the center of the paraboloid. The code computes the fields along a radial, horizontal, vertical or axial cut at that distance. Thus, it is very effective in computing the size of the sweet spot for a semi-circular compact range reflector. This report describes the operation of the code. Various input and output statements are explained. Some results obtained using the computer code are presented to illustrate the code's capability as well as being samples of input/output sets.

  6. Size limitations in semicircular duct systems

    PubMed

    Muller

    1999-06-01

    The present article discusses mechanical requirements and limitations which are applicable to the construction of the system of semicircular ducts, especially to its size. The simplified case of a single, uniform duct system has been considered which can be described by a second order equation of motion. The principal functional quantities for this rotation-sensor are: (1) response speed; (2) sensitivity; and (3) regular flow. The response speed of a single, uniform semicircular duct is characterized by the short time constant (T2) which is dependent on the duct radius (r). Its estimated range is from 0.04 ms in the smallest to 140 ms in the largest known labyrinth. The sensitivity is characterized by the maximal endolymph displacement after a step stimulus (xmax). Its estimated range is from 0.0016 &mgr;m to 5.97 mm (6.56 decades!), assuming an input angular velocity of omega=1 rad s-1. The Reynolds number is a measure for an undisturbed laminar flow. Its estimated range varies from 7.38.10(-4)to 45.1 for omega=1 rad s-1. The above data follow from graphs in which, for a single uniform duct, circuit radius (R) is plotted against duct radius (r) for labyrinths of 233 species belonging to different vertebrate-groups. A relation R =38.9. r1.60was determined. The smallest labyrinth was found in a carp larva (Cyprinus), the largest in a whale shark (Rhincodon). Large whales possess labyrinths of average mammalian size. It is revealed that semicircular duct size is bound by requirements concerning regular flow and by a too low response speed for large labyrinths, and by a too low sensitivity for small labyrinths. Other important quantities are mechanical amplification factors which are a consequence of more complex vestibular constructions than a single uniform duct circuit. Allometric relationships are interpreted as compromises between the quantities mentioned. A hypothesis for the relatively large semicircular duct sizes of fishes, especially Elasmobranchii, compared

  7. Ground motions around a semicircular canyon with a dipping edge under SH plane wave incidence

    NASA Astrophysics Data System (ADS)

    Chang, Kao-Hao; Tsaur, Deng-How; Wang, Jeen-Hwa

    2016-01-01

    In order to explore the spatial distribution and temporal variation of ground motions near a semicircular canyon with a dipping edge, a simplified mathematical model is constructed. Based on the region-matching technique, a Fourier-Bessel series solution for the plane SH-wave excitation is derived and then applied to theoretically simulate the seismic response of the canyon. The use of the adequate wavefunctions and a newly derived Graf's addition formula can solve the unknown expansion coefficients. Parametric analyses with respect to the frequency of input motion, angle of incidence, and canyon geometry are illustrated. Both frequency- and time-domain computations are presented. The canonical case, a completed semicircular canyon, which has the exact analytical solution, and the horizontally truncated case analyzed in previous works are considered as particular cases of the proposed general model. Comparisons with boundary-element solutions show good agreement. Steady-state results show that the phenomenon of wave focusing tends to be significant when the incident angle bends toward the horizontal ground surface. Propagation and attenuation of scattered waves that originated from the surficial anomaly are exhibited in transient-state simulations.

  8. 21. REAR OF OLD FAITHFUL INN, LOOKING NORTH. SEMICIRCULAR SIDE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. REAR OF OLD FAITHFUL INN, LOOKING NORTH. SEMI-CIRCULAR SIDE DINING ROOM, NOW CALLED THE BEAR PIT WAS ADDED IN 1927. (TAKEN FROM CHERRY-PICKER) - Old Faithful Inn, 900' northeast of Snowlodge & 1050' west of Old Faithful Lodge, Lake, Teton County, WY

  9. Design and performance of a multichannel vestibular prosthesis that restores semicircular canal sensation in rhesus monkey

    PubMed Central

    Chiang, Bryce; Fridman, Gene Y.; Dai, Chenkai; Rahman, Mehdi A.; Della Santina, Charles C.

    2012-01-01

    In normal individuals, the vestibular labyrinths sense head movement and mediate reflexes that maintain stable gaze and posture. Bilateral loss of vestibular sensation causes chronic disequilibrium, oscillopsia, and postural instability. We describe a new multichannel vestibular prosthesis (MVP) intended to restore modulation of vestibular nerve activity with head rotation. The device comprises motion sensors to measure rotation and gravitoinertial acceleration, a microcontroller to calculate pulse timing, and stimulator units that deliver constant-current pulses to microelectrodes implanted in the labyrinth. This new MVP incorporates many improvements over previous prototypes, including a 50% decrease in implant size, a 50% decrease in power consumption, a new microelectrode array design meant to simplify implantation and reliably achieve selective nerve-electrode coupling, multiple current sources conferring ability to simultaneously stimulate on multiple electrodes, and circuitry for in vivo measurement of electrode impedances. We demonstrate the performance of this device through in vitro bench-top characterization and in vivo physiological experiments with a rhesus macaque monkey. PMID:21859631

  10. The relative roles of the otolith organs and semicircular canals in producing space motion sickness

    NASA Technical Reports Server (NTRS)

    Parker, D. E.

    1998-01-01

    Inflight and post-landing "immunity" to the "coriolis sickness susceptibility test", observed during the Skylab M131 experiment, suggests that the otolith organs play a major role in space motion sickness (SMS). This view is supported by the report that ocular counter-torsion asymmetries correlate with SMS incidence and severity. Further data indicate that sensory-motor adaptation to microgravity includes a process whereby central interpretation of otolith signals is biased from "tilt" toward translation. However, unexpected responses to linear acceleration suggest the importance of graviceptors distributed throughout the body in addition to the vestibular otolith organs. Research is needed to assess distributed graviceptor effects.

  11. 3. ELEVATION. FROM SOUTH WITH CANAL PRISM. Canal Road ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. ELEVATION. FROM SOUTH WITH CANAL PRISM. - Canal Road Bridge, Canal Road spanning Delaware Canal Diversion, Locks 22 & 23 in Delaware Canal State Park in Williams Township, Raubsville, Northampton County, PA

  12. 11. REMNANTS OF FLUME BOX WITHIN CANAL. NOTE THE UPRIGHT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. REMNANTS OF FLUME BOX WITHIN CANAL. NOTE THE UPRIGHT SIDE POSTS BOLTED TO BASE STRINGER AND HORIZONTAL BOARD SIDE WALLS. VIEW IS TO THE SOUTHEAST. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO

  13. Otolith-Canal Convergence In Vestibular Nuclei Neurons

    NASA Technical Reports Server (NTRS)

    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.

  14. Head movements suggest canal and otolith projections are activated during galvanic vestibular stimulation.

    PubMed

    Kim, J

    2013-12-01

    Three-dimensional changes in the angular orientation of the head were monitored during galvanic vestibular stimulation (GVS) delivered through electrodes implanted bilaterally in the tensor tympani muscle of the guinea-pig middle ear. Bilateral GVS was delivered by passing current between both ears with the anode situated in one ear and the cathode in the other ear. Unilateral GVS was also delivered between one ear and an indifferent electrode on the skull. Constant-current stimulation caused the head to tilt predominantly within the roll and yaw planes toward an ear stimulated with anodal current and away from an ear stimulated with cathodal current. No significant head tilt in the pitch plane was observed with either bilateral or unilateral GVS. Bilateral GVS was found to induce significantly greater roll head tilt (RHT) and yaw head tilt (YHT) than the same intensity of unilateral anodal or cathodal GVS, but not the sum of responses induced by the two polarities of unilateral GVS. Significant asymmetries were observed in the responses of YHT and RHT for unilateral anodal and cathodal GVS; unilateral cathodal stimulation generated greater head deviation compared with the same intensity of unilateral anodal stimulation. These asymmetric responses are consistent with activation of irregularly discharging afferents, which have been shown previously to exhibit asymmetric responses for anodal and cathodal GVS (Kim and Curthoys, 2004). Together with the observations of previous guinea-pig studies, the results suggest that head movements induced by GVS may be mediated by irregularly discharging afferents innervating the otoliths, and possibly the horizontal semicircular canals. PMID:24021920

  15. Designing Flaps for Closure of Circular and Semicircular Skin Defects

    PubMed Central

    2016-01-01

    Summary: Removing skin lesions from the human body is a simple procedure, but closing the resulting defect may prove a difficult task. The surgeon quite often encounters a problem when the lesion is located in a confined anatomical area where the elasticity of the skin is limited or when the lesion is large. To obviate these difficulties, I present 4 new incisions for closure of circular and semicircular skin defects on difficult parts of the human body such as the scalp, face, axilla, back, and sacrococcygeal areas. This article describes a working model made of white bond paper that can be enlarged or reduced in size using a regular copying machine that can be prepared in advance of surgery to make sure that it adapts to a particular anatomical location. Also, it describes a geometrical analysis in order to determine the distortion of the minimal tension lines of the skin, skin wastage, and length of the suture lines. In summary, it is possible to use a variety of skin incisions, taking advantage of the minimal tension lines of the skin and also taking into consideration the anatomical characteristics of the region involved. PMID:27104106

  16. Free-surface flow over a semi-circular obstruction

    NASA Astrophysics Data System (ADS)

    Lowery, Kristen; Liapis, Stergios

    1999-05-01

    The fully non-linear free-surface flow over a semi-circular bottom obstruction was studied numerically in two dimensions using a mixed Eulerian-Lagrangian formulation. The problem was solved in the time domain that allows the prediction of a number of transient phenomena, such as the generation of upstream advancing solitary waves, as well as the simulation of wave breaking. A parametric study was performed for a range of values of the depth-based Froude number up to 2.5 and non-dimensional obstacle heights, up to 0.9. When wave breaking does not occur, three distinct flow regimes were identified: subcritical, transcritical and supercritical. When breaking occurs it may be of any type: spilling, plunging or surging. In addition, for values of the Froude number close to 1, the upstream solitary waves break. A systematic study was undertaken to define the boundaries of each type of breaking and non-breaking pattern and to determine the drag and lift coefficients, free-surface profile characteristics and transient behavior. Copyright

  17. Root canal irrigants

    PubMed Central

    Kandaswamy, Deivanayagam; Venkateshbabu, Nagendrababu

    2010-01-01

    Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are discussed. We performed a Medline search for English-language papers published untill July 2010. The keywords used were ‘root canal irrigants’ and ‘endodontic irrigants.’ The reference lists of each article were manually checked for additional articles of relevance. PMID:21217955

  18. 56. CROSS SECTIONS OF CANAL AND TUNNELS. POWER CANAL, SALT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. CROSS SECTIONS OF CANAL AND TUNNELS. POWER CANAL, SALT RIVER RESERVOIR Courtesy of U.S.G.S., Reclamation Service - Roosevelt Power Canal & Diversion Dam, Parallels Salt River, Roosevelt, Gila County, AZ

  19. Bitter Root Irrigation district canal, looking east, typical section (canal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Bitter Root Irrigation district canal, looking east, typical section (canal full) - Bitter Root Irrigation Project, Bitter Root Irrigation Canal, Heading at Rock Creek Diversion Dam, West of U.S. Highway 93, Darby, Ravalli County, MT

  20. 9. BLACK RIVER CANAL CANAL (RIGHT), DISCHARGE GATE (BACKGROUND), ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. BLACK RIVER CANAL - CANAL (RIGHT), DISCHARGE GATE (BACKGROUND), FARMER'S TURNOUT (LEFT), AND LATERAL NO. 14 (FOREGROUND). VIEW TO SOUTHEAST - Carlsbad Irrigation District, Black River Canal, 15 miles Southeast of Carlsbad near Malaga, Carlsbad, Eddy County, NM

  1. 8. BLACK RIVER CANAL LOOKING DOWN CANAL WITH LATERAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. BLACK RIVER CANAL - LOOKING DOWN CANAL WITH LATERAL TURNOUT NO. 1 ON THE RIGHT. VIEW TO THE SOUTHEAST - Carlsbad Irrigation District, Black River Canal, 15 miles Southeast of Carlsbad near Malaga, Carlsbad, Eddy County, NM

  2. 14. MAIN CANAL CANAL CHECKGATES, JUST BELOW DARK CANYON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. MAIN CANAL - CANAL CHECKGATES, JUST BELOW DARK CANYON SIPHON, VIEW TO NORTHEAST - Carlsbad Irrigation District, Main Canal, 4 miles North to 12 miles Southeast of Carlsbad, Carlsbad, Eddy County, NM

  3. 6. O'BRIAN CANAL/DENVERHUDSON CANAL BIFURCATION POINT The O'Brian Canal is ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. O'BRIAN CANAL/DENVER-HUDSON CANAL BIFURCATION POINT The O'Brian Canal is flowing to the left; the Denver-Hudson Canal is flowing to the right - O'Brian Canal, South Platte River Drainage Area Northest of Denver, Brighton, Adams County, CO

  4. Surgical management of 2 different presentations of ear canal atresia in dogs.

    PubMed

    Béraud, Romain

    2012-04-01

    A 6-year-old French spaniel and a 14-month-old German shepherd dog were diagnosed with ear canal atresia. Based on presentation, computed tomography, and auditory function evaluation, the first dog underwent excision of the horizontal ear canal and bulla curettage, and the second underwent re-anastomosis of the vertical canal to the external meatus. Both dogs had successful outcomes. PMID:23024390

  5. Surgical management of 2 different presentations of ear canal atresia in dogs

    PubMed Central

    Béraud, Romain

    2012-01-01

    A 6-year-old French spaniel and a 14-month-old German shepherd dog were diagnosed with ear canal atresia. Based on presentation, computed tomography, and auditory function evaluation, the first dog underwent excision of the horizontal ear canal and bulla curettage, and the second underwent re-anastomosis of the vertical canal to the external meatus. Both dogs had successful outcomes. PMID:23024390

  6. GABAB-mediated modulation of ionic conductances in type I hair cells isolated from guinea-pig semicircular canals.

    PubMed

    Lapeyre, P N; Kolston, P J; Ashmore, J F

    1993-04-23

    Mammalian vestibular type I hair cells (VIHCs) are innervated by an afferent synaptic calyx which contains vesicles and is immunoreactive for GABA. We describe here the effects of GABA on electrophysiological properties and on cytosolic free-calcium levels ([Ca2+]i) of VIHCs isolated from guinea-pig ampullae. Whole-cell tight-seal macroscopic currents recorded from VIHCs showed that 100 microM GABA induced a decrease in the outward currents elicited by depolarizing membrane potentials. These are known to comprise potassium calcium-dependent currents. This effect was mimicked by baclofen, a GABAB agonist, and was not affected by picrotoxin, a GABAA antagonist. GABA also induced an increase in the inward current elicited at hyperpolarized membrane potentials in 50% of the tested cells. Single channel recording in cell-attached patches revealed that externally applied GABA produced a decrease and an increase in the open probability of 170 pS and 45 pS and of 15 pS channels, respectively. In imaging experiments using the dye Fura-2 to measure [Ca2+]i, the only reversible modulation of [Ca2+]i observed in response to GABA application was a decrease. These results demonstrate a modulation of calcium and potassium conductances by GABA, via GABAB receptors, in guinea-pig VIHCs. PMID:7685230

  7. Otolith-Canal Convergence in Vestibular Nuclei Neurons

    NASA Technical Reports Server (NTRS)

    Dickman, J. David

    1996-01-01

    During manned spaceflight, acute vestibular disturbances often occur, leading to physical duress and a loss of performance. Vestibular adaptation to the weightless environment follows within two to three days yet the mechanisms responsible for the disturbance and subsequent adaptation are still unknown In order to understand vestibular system function in space and normal earth conditions the basic physiological mechanisms of vestibular information co coding must be determined. Information processing regarding head movement and head position with respect to gravity takes place in the vestibular nuclei neurons that receive signals From the semicircular canals and otolith organs in the vestibular labyrinth. These neurons must synthesize the information into a coded output signal that provides for the head and eye movement reflexes as well as the conscious perception of the body in three-dimensional space The current investigation will for the first time. determine how the vestibular nuclei neurons quantitatively synthesize afferent information from the different linear and angular acceleration receptors in the vestibular labyrinths into an integrated output signal. During the second year of funding, progress on the current project has been focused on the anatomical orientation of semicircular canals and the spatial orientation of the innervating afferent responses. This information is necessary in order to understand how vestibular nuclei neurons process the incoming afferent spatial signals particularly with the convergent otolith afferent signals that are also spatially distributed Since information from the vestibular nuclei is presented to different brain regions associated with differing reflexive and sensory functions it is important to understand the computational mechanisms used by vestibular neurons to produce the appropriate output signal.

  8. Optimization of the mechanical performance of a two-duct semicircular duct system--part 1: dynamics and duct dimensions.

    PubMed

    Muller, M; Verhagen, J H G

    2002-06-21

    The classical representation of the semicircular duct system consists of three separate duct circuits. The ducts are, however, in reality, hydrodynamically interconnected. Muller & Verhagen (1988a,b) derived equations for the mechanical behaviour of an interconnected system with three ducts (anterior, posterior and horizontal). An analytical solution of these equations would, however, be too complex to provide surveyable formulae. A system of two interconnected ducts avoids this complexity whilst keeping the essentials of the coupling of ducts intact. The solution of the equation of motion leads to expressions for time constants and maximal endolymph excursions which are functions of morphological parameters, viz. the ratios of radii (gamma) and lengths (lambda) of the common vestibular part (crus commune or utriculus) and the ducts. The system possesses two short time constants which are shown to have similar values. The maximum endolymph displacements in the two ducts after a steplike stimulus are the products of the respective initial velocities and combinations of time constants. The initial velocities depend strongly on the position of the labyrinth with respect to the excitating rotation vector. Measured data of gamma and lambda are compared with the theoretical results. For gamma, excellent agreement was found. lambda is treated elsewhere. PMID:12151258

  9. Semi-circular microgrooves to observe active movements of individual Navicula pavillardii cells.

    PubMed

    Umemura, Kazuo; Haneda, Takahiro; Tanabe, Masashi; Suzuki, Akira; Kumashiro, Yoshikazu; Itoga, Kazuyoshi; Okano, Teruo; Mayama, Shigeki

    2013-03-01

    We performed a trajectory analysis of movements of Navicula pavillardii diatom cells that were confined to semi-circular microgrooves with several different curvature radii. Using the semi-circular micropattern, we succeeded in observing change of velocity of the same cell before and after the stimulation by N,N-dimethyl-p-toluidine (DMT). Because the looped grooves had longer contour length than straight grooves, it was effective to achieve the long term observation of the stimulated active cells. Although average velocity of 150 cells was significantly increased with DMT, the maximum velocity (19 μm/s) of the cells was not increased after the DMT injection. This may suggest that existence of the mechanical limit of the velocity of the diatom cells. Secondly, trajectories of individual cell movements along the walls of the semi-circular microgrooves were analyzed in detail. As a result, the velocity of the cells was not affected by the curvature radii of the grooves although the trajectories indicated an obvious restriction of area of the cell motion. This suggests that the surface of the diatom is effective in minimizing the frictional force between the cell body and the wall of a groove. Finally, a simple model of cell motion in the semi-circular groove was proposed to clarify the relationships among the forces that determine cell movement. PMID:23337812

  10. Panama Canal capacity analysis

    SciTech Connect

    Bronzini, M.S.

    1995-04-27

    Predicting the transit capacities of the various Panama Canal alternatives required analyzing data on present Canal operations, adapting and extending an existing computer simulation model, performing simulation runs for each of the alternatives, and using the simulation model outputs to develop capacity estimates. These activities are summarized in this paper. A more complete account may be found in the project final report (TAMS 1993). Some of the material in this paper also appeared in a previously published paper (Rosselli, Bronzini, and Weekly 1994).

  11. Modification of the Cervico-ocular Reflex by Canal Plugging

    PubMed Central

    Yakushin, Sergei B.; Tarasenko, Yelena; Raphan, Theodore; Suzuki, Jun-Ichi; Della Santina, Charles C.; Minor, Lloyd B.; Cohen, Bernard

    2016-01-01

    The cervico-ocular reflex (COR) has a low gain in normal animals. In this study, we determined whether COR gain increases were specific to the low/midband frequency range, which is the range over which the angular vestibulo-ocular reflex (aVOR) is compromised by plugging. The gain and phase of the yaw and pitch COR and aVOR were compared in normal monkeys and those with all six semicircular canals or only the lateral canal plugged. During experiments animals sat with the body fixed to a chair and the head fixed in space. The body was oscillated about body-yaw and body-pitch axes over a frequency range of 0.05–6 Hz, with amplitude <10°. For normal animals, both yaw and pitch eye velocities were compensatory to the relative velocity of the head with respect to the body. The gains were 0.1–0.2 at frequencies below 1 Hz and decreased to zero as stimulus frequency increased above 1 Hz. Canal-plugged animals had COR gains close to 1.0 at low frequencies, decreasing to ≈0.6 at 0.5 Hz and to 0.2 for stimulus frequencies above 3 Hz. The phase of eye velocity was 180° relative to head-re-body velocity at frequencies below 0.5 Hz and shifted toward 270° as frequencies were increased to 4 Hz. This study demonstrates that adaptation of COR gain is tuned to a frequency range at which the aVOR is compromised by the canal plugging. PMID:19645881

  12. 54. View of junction of unlined canal and lined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  13. 55. View of junction of unlined canal and lined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    55. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  14. Ear canal cholesteatoma.

    PubMed

    Holt, J J

    1992-06-01

    Although cholesteatomas are more commonly found in the middle ear and the mastoid, the disease can occur in the external ear canal. All cases of ear canal cholesteatoma treated by the author were reviewed. There were nine ears in seven patients, who had an average age of 62 years. The lesions ranged in size from a few millimeters to extensive mastoid destruction. Smaller lesions can be managed by frequent cleaning as an office procedure. Larger lesions require surgery, either canaloplasty or mastoidectomy. The otolaryngologist should suspect this disease in the elderly. Microscopic examination of the ear with meticulous cleaning of all wax, especially in elderly patients, is most useful in detecting early disease. Frequent applications of mineral oil to the canal should be used in the management of the disease and to prevent recurrence. PMID:1376388

  15. 23. VIEW OF GRAND CANAL, SHOWING NEW ALIGNMENT CANAL ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. VIEW OF GRAND CANAL, SHOWING NEW ALIGNMENT CANAL ON RIGHT. THIS PHOTO WAS TAKEN FROM APPROXIMATELY THE SAME SPOT AS THE PREVIOUS PHOTOGRAPH (AZ-17-22). Photographer: Kevin Kreisel-Coons, May 1990 - Grand Canal, North side of Salt River, Tempe, Maricopa County, AZ

  16. 56. View of lined canal looking east toward unlined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. View of lined canal looking east toward unlined canal, from road bridge crossing lined canal. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  17. Integrated plasmonic semi-circular launcher for dielectric-loaded surface plasmon-polariton waveguide.

    PubMed

    Li, Xiaowei; Huang, Lingling; Tan, Qiaofeng; Bai, Benfeng; Jin, Guofan

    2011-03-28

    A semi-circular plasmonic launcher integrated with dielectric-loaded surface plasmon-polaritons waveguide (DLSPPW) is proposed and analyzed theoretically, which can focus and efficiently couple the excited surface plasmon polaritons (SPPs) into the DLSPPW via the highly matched spatial field distribution with the waveguide mode in the focal plane. By tuning the incident angle or polarization of the illuminating beam, it is shown that the launcher may be conveniently used as a switch or a multiplexer that have potential applications in plasmonic circuitry. Furthermore, from an applicational point of view, it is analyzed how the coupling performance of the launcher can be further improved by employing multiple semi-circular slits. PMID:21451682

  18. Love canal questions

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    The Environmental Protection Agency (EPA) conducted a 3-month monitoring study of the Love Canal area near Niagara Falls, N.Y., after the federal government pronounced that a potential health risk existed due to chemical waste dumps. In 1982 the Department of Health and Human Services (HHS) decided that the area was habitable, subject to implementation of effective safeguards against leakage from the canal and to cleaning up of the contaminants. Now, the Congressional Office of Technology Assessment (OTA) has announced that, with the information available, it is not possible to demonstrate with certainty that unsafe levels do not exist within the so-called “emergency declaration area” (EDA).

  19. The evolutionary genetics of canalization.

    PubMed

    Flatt, Thomas

    2005-09-01

    Evolutionary genetics has recently made enormous progress in understanding how genetic variation maps into phenotypic variation. However why some traits are phenotypically invariant despite apparent genetic and environmental changes has remained a major puzzle. In the 1940s, Conrad Hal Waddington coined the concept and term "canalization" to describe the robustness of phenotypes to perturbation; a similar concept was proposed by Waddington's contemporary Ivan Ivanovich Schmalhausen. This paper reviews what has been learned about canalization since Waddington. Canalization implies that a genotype's phenotype remains relatively invariant when individuals of a particular genotype are exposed to different environments (environmental canalization) or when individuals of the same single- or multilocus genotype differ in their genetic background (genetic canalization). Consequently, genetic canalization can be viewed as a particular kind of epistasis, and environmental canalization and phenotypic plasticity are two aspects of the same phenomenon. Canalization results in the accumulation of phenotypically cryptic genetic variation, which can be released after a "decanalizing" event. Thus, canalized genotypes maintain a cryptic potential for expressing particular phenotypes, which are only uncovered under particular decanalizing environmental or genetic conditions. Selection may then act on this newly released genetic variation. The accumulation of cryptic genetic variation by canalization may therefore increase evolvability at the population level by leading to phenotypic diversification under decanalizing conditions. On the other hand, under canalizing conditions, a major part of the segregating genetic variation may remain phenotypically cryptic; canalization may therefore, at least temporarily, constrain phenotypic evolution. Mechanistically, canalization can be understood in terms of transmission patterns, such as epistasis, pleiotropy, and genotype by environment

  20. Elastic-plastic behavior of a semicircular frame being pressed against a rigid plane

    NASA Astrophysics Data System (ADS)

    Zhang, X. W.; Yang, J. L.; Yu, T. X.

    2008-08-01

    As a simplified structural model, a semicircular frame is used to study the crashworthiness behavior of an aircraft fuselage. The quasi-static large elastic-plastic deformation of a semicircular frame in the process of its being pressed against a rigid ground is analyzed. First, based on the linear elastic assumption, the quasi-static large deformation contact process of the frame can be divided into three phases, i.e., point contact, line contact and post-buckling. By means of a shooting method, the relations between the displacement and contact force as well as the distribution of bending moment in the three phases are obtained. Then, by assuming an elastic, perfectly-plastic moment-curvature relationship for the semi-circular frame, the contact process is analyzed in detail to reveal the plastic collapse mechanism, the traveling of plastic hinge and the force-displacement relationship. In order to verify the analysis, a preliminary experiment was conducted, in which two types of half rings with clamped ends were pressed by a rigid plate. In addition, a numerical simulation is also conducted by employing ABAQUS to analyze both rectangular cross-sectional beam and I-beam. Finally, the theoretical predictions are compared with the experimental results and numerical solutions, showing that the elastic-plastic analysis can predict the contact process very well.

  1. Stress Intensity Factors of Semi-Circular Bend Specimens with Straight-Through and Chevron Notches

    NASA Astrophysics Data System (ADS)

    Ayatollahi, M. R.; Mahdavi, E.; Alborzi, M. J.; Obara, Y.

    2016-04-01

    Semi-circular bend specimen is one of the useful test specimens for determining fracture toughness of rock and geo-materials. Generally, in rock test specimens, initial cracks are produced in two shapes: straight-edge cracks and chevron notches. In this study, the minimum dimensionless stress intensity factors of semi-circular bend specimen (SCB) with straight-through and chevron notches are calculated. First, using finite element analysis, a suitable relation for the dimensionless stress intensity factor of SCB with straight-through crack is presented based on the normalized crack length and half-distance between supports. For evaluating the validity and accuracy of this relation, the obtained results are then compared with numerical and experimental results reported in the literature. Subsequently, by performing some experiments and also finite element analysis of the SCB specimen with chevron notch, the minimum dimensionless stress intensity factor of this specimen is obtained. Using the new equation for the dimensionless stress intensity factor of SCB with straight-through crack and an analytical method, i.e., Bluhm's slice synthesis method, the minimum (critical) dimensionless stress intensity factor of chevron notched semi-circular bend specimens is calculated. Good agreement is observed between the results of two mentioned methods.

  2. 10. VIEW EAST, RECESS AREA WITH BOTTOM HORIZONTAL BEAM FOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. VIEW EAST, RECESS AREA WITH BOTTOM HORIZONTAL BEAM FOR EAST GATE - Bald Eagle Cross-Cut Canal Lock, North of Water Street along West Branch of Susquehanna River South bank, 500 feet East of Jay Street Bridge, Lock Haven, Clinton County, PA

  3. Leiomyoma of External Auditory Canal.

    PubMed

    George, M V; Puthiyapurayil, Jamsheeda

    2016-09-01

    This article reports a case of piloleiomyoma of external auditory canal, which is the 7th case of leiomyoma of the external auditory canal being reported and the 2nd case of leiomyoma arising from arrectores pilorum muscles, all the other five cases were angioleiomyomas, arising from blood vessels. A 52 years old male presented with a mass in the right external auditory canal and decreased hearing of 6 months duration. Tumor excision done by end aural approach. Histopathological examination report was leiomyoma. It is extremely rare for leiomyoma to occur in the external auditory canal because of the non-availability of smooth muscles in the external canal. So it should be considered as a very rare differential diagnosis for any tumor or polyp in the ear canal. PMID:27508144

  4. Distributed control at Love canal

    SciTech Connect

    McPherson, G.; Rider, G.J.; Sadowski, B.; Moore, M.

    1994-09-01

    Love Canal is known worldwide as the site of one of the worst non-nuclear environmental disasters in modern history. For 12 years, a Niagara Falls, New York chemical company used the canal bed as a chemical dump. This article discusses the computerized control of equipment used to remove the toxic materials from the ground under Love Canal, and how the minimization of maintenance is reducing maintenance costs and increasing operator safety.

  5. Nasopalatine canal cyst: often missed

    PubMed Central

    Srivastava, Saurabh; Misra, Neeta; Agarwal, Rashmi; Pandey, Praveen

    2013-01-01

    Nasopalatine canal cyst may occur within the nasopalatine canal or in the soft tissues of the palate, at the opening of the canal, where it is called the ‘cyst of the palatine papilla’. These are normally asymptomatic, constituting casual radiological findings. We present a case report of a male patient with infected nasopalatine canal cyst seen clinically as swelling over palate. Radiographic interpretation should be thoroughly performed for maxillary anterior region and any occlusal radiograph in routine radiography to screen this entity and must be distinguished from other maxillary anterior radiolucencies by the clinician. PMID:23536642

  6. Analysis and evaluation of relative positions of mandibular third molar and mandibular canal impacts

    PubMed Central

    Kim, Hang-Gul

    2014-01-01

    Objectives This study used cone-beam computed tomography (CBCT) images to categorize the relationships between the mandibular canal and the roots and investigated the prevalence of nerve damage. Materials and Methods Through CBCT images, contact and three-dimensional positional relationships between the roots of the mandibular third molar and the mandibular canal were investigated. With this data, prevalence of nerve damage according to the presence of contact and three-dimensional positional relationships was studied. Other factors that affected the prevalence of nerve damage were also investigated. Results When the mandibular third molar and the mandibular canal were shown to have direct contact in CBCT images, the prevalence of nerve damage was higher than in other cases. Also, in cases where the mandibular canal was horizontally lingual to the mandibular third molar and the mandibular canal was vertically at the cervical level of the mandibular third molar, the prevalence of nerve damage was higher than in opposite cases. The percentage of mandibular canal contact with the roots of the mandibular third molar was higher when the mandibular canal was horizontally lingual to the mandibular third molar. Finally, the prevalence of nerve damage was higher when the diameter of the mandibular canal lumen suddenly decreased at the contact area between the mandibular canal and the roots, as shown in CBCT images. Conclusion The three-dimensional relationship of the mandibular third molar and the mandibular canal can help predict nerve damage and can guide patient expectations of the possibility and extent of nerve damage. PMID:25551092

  7. ASTER Suez Canal

    NASA Technical Reports Server (NTRS)

    2000-01-01

    One of the most important waterways in the world, the Suez Canal runs north to south across the Isthmus of Suez in northeastern Egypt. This image of the canal covers an area 36 kilometers (22 miles) wide and 60 kilometers (47 miles) long in three bands of the reflected visible and infrared wavelength region. It shows the northern part of the canal, with the Mediterranean Sea just visible in the upper right corner. The Suez Canal connects the Mediterranean Sea with the Gulf of Suez, an arm of the Red Sea. The artificial canal provides an important shortcut for ships operating between both European and American ports and ports located in southern Asia, eastern Africa, and Oceania. With a length of about 195 kilometers (121 miles) and a minimum channel width of 60 meters (197 feet), the Suez Canal is able to accommodate ships as large as 150,000 tons fully loaded. Because no locks interrupt traffic on this sea level waterway, the transit time only averages about 15 hours. ASTER acquired this scene on May 19, 2000.

    Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five

  8. 15. ROUTE OF CANAL NORTHWEST OF THE DILLON CEMETERY. CANAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. ROUTE OF CANAL NORTHWEST OF THE DILLON CEMETERY. CANAL PASSES BELOW HILLSIDE IN FOREGROUND, THROUGH THE LOWER EDGE OF THE TREES ON LEFT, ON FAR SIDE OF SMALL VALLEY JUST RIGHT OF CENTER, AND AROUND THE PROMINENT POINT ON THE RIGHT. VIEW IS TO THE EAST-SOUTHEAST. - Snake River Ditch, Headgate on north bank of Snake River, Dillon, Summit County, CO

  9. REACTOR CANAL AFTER IT HAS BEEN TILED. WATER FILLS CANAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTOR CANAL AFTER IT HAS BEEN TILED. WATER FILLS CANAL PART WAY TO TOP. CAMERA FACES WEST. INL NEGATIVE NO. 3993-A. Unknown Photographer, 12/28/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  10. Mitigating Shock Waves Using Solid Obstacles with Semi-Circular Grooves

    NASA Astrophysics Data System (ADS)

    Amen, Nicholas; Cajal, Arturo; Eliasson, Veronica

    2015-11-01

    An experimental investigation was performed to assess the effectiveness of multiple obstacles with semi-circular grooves placed along a logarithmic spiral curve as a method to attenuate a shock wave. Previous research has shown that the use of multiple obstacles arranged in a log spiral configuration can attenuate a shock wave by reducing the energy of the wave. In this study, four different obstacle cross-sections in the same log spiral configuration were considered. All spirals had square cross-sections with zero, one, two, or three semi-circular grooves in each face. They were placed inside a shock tube where the incident, reflected, and transmitted shocks were visualized with high-speed schlieren imaging and the pressure histories were recorded with four pressure transducers. Each case was studied varying shock Mach numbers between M =1.1 and M =1.5. The pressure traces were used to establish incident, reflected, and transmitted shock strength and wave speed. Results for the zero groove case were compared to that of the one, two, and three groove cross-sections which show that increasing the number of grooves has a profound effect on the generation of the reflected wave and impacts the transmitted wave via vortex generation behind the spiral.

  11. Active concentration of vorticity along the leading edge of a semi-circular wing

    NASA Astrophysics Data System (ADS)

    Williams, David; Collins, Jesse; Colonius, Tim

    2007-11-01

    Leading-edge vorticity concentration plays a key role in lift enhancement for insect flight, swept wings on aircraft, and in unsteady flows through the formation of the dynamic stall vortex. Using 16 spatially localized pulsed-blowing actuators, we are able to concentrate the vorticity at the leading edge of a wing with a semi-circular planform. The experiments are done in a wind tunnel with a model chord Reynolds number of 68,000. Peak vorticity values double those of the unforced case result in an 80 percent increase in lift on the wing relative to the unforced post-stall lift. The semi-circular wing obtains lift coefficients approximately 35 percent larger than a rectangular planform wing with a comparable aspect ratio. The sweep of the wing's leading edge is believed to establish a spanwise transport of vorticity, contributing to the stabilization of the leading edge vortex. Closed-loop control of the wing plunging motion in an unsteady flow stream is demonstrated by modulating the strength of the leading-edge vorticity via a proportional-derivative controller.

  12. Controversy at Love Canal.

    PubMed

    Paigen, B

    1982-06-01

    A cancer researcher reviews the events surrounding the toxic waste contamination at Love Canal with emphasis on the political nature of the controversy about its health impact. Antagonism between the community and the New York State Department of Health was fueled by several factors: the state's awareness that it gained from delay in investigation, disagreement on health problems to be studied, control over the information gathering process, silencing of opposition opinion, and the violation of norms of scientific behavior. The author calls for the establishment of standards of ethical behavior for scientists in such situations, standards for conflict resolution, and means of appeal for those injured. PMID:7107238

  13. Horizontal drilling technology advances

    SciTech Connect

    Not Available

    1991-03-04

    Horizontal drilling technology is making further advances in the Texas Austin chalk play as such drilling continues to spread in many U.S. land areas. One company has completed a Cretaceous Austin chalk oil well with the longest horizontal well bore in Texas and what at 1 1/6 miles is believed to be the world's longest medium radius horizontal displacement.

  14. Horizontal drilling developments

    SciTech Connect

    Gust, D.

    1997-05-01

    The advantages of horizontal drilling are discussed. Use of horizontal drilling has climbed in the past half decade as technology and familiarity offset higher costs with higher production rates and greater recoveries from new and existing wells. In essence, all types of horizontal wells expose a larger section of the reservoir to the wellbore with a resulting increase in flow rates. (A horizontal well may also be drilled to provide coning control or to intersect vertical fractures.) Thus, drilling horizontally, both onshore and offshore, reduces the number of wells necessary to develop a field.

  15. Proposal for a simple and effective diagrammatic representation of root canal configuration for better communication amongst oral radiologists and clinicians

    PubMed Central

    Gupta, Saurabh Kumar; Saxena, Payal

    2015-01-01

    Objectives Root canal anatomy has been proved to be a complex canal configuration system. The negotiation and cleaning of this system is essential for successful root canal treatment. The present root canal classification systems are unable to transfer the clinically relevant information about the canal system from the oral radiologist to the treating clinician. Thus, a simple and effective diagrammatic representation of the canal system, depicting the major canals, important changes during their course along with other relevant information has been presented. Methods The proposed representation consists of five horizontal lines dividing the tooth into four segments from the point of reference to apical foramen. Each line has been designated with different line style. The diagrammatic images, one anterior and one posterior multi-rooted tooth, are given for easy understanding of the orientation of image. The whole image can be saved in portable network graphics format and can be imported to any word processing document. The image can be printed in the reporting sheet. Result Applying the same proposal, some of the diagrammatic representations have been showed. Conclusion This proposal for diagrammatic representation of root canal configuration can be helpful in getting an approximate distribution of the canals in a relatively simple manner. This scheme also provides valuable clinical information about the root canal system, which the other classifications fail to represent. PMID:26937372

  16. Otolith and Vertical Canal Contributions to Dynamic Postural Control

    NASA Technical Reports Server (NTRS)

    Black, F. Owen

    1999-01-01

    The objective of this project is to determine: 1) how do normal subjects adjust postural movements in response to changing or altered otolith input, for example, due to aging? and 2) how do patients adapt postural control after altered unilateral or bilateral vestibular sensory inputs such as ablative inner ear surgery or ototoxicity, respectively? The following hypotheses are under investigation: 1) selective alteration of otolith input or abnormalities of otolith receptor function will result in distinctive spatial, frequency, and temporal patterns of head movements and body postural sway dynamics. 2) subjects with reduced, altered, or absent vertical semicircular canal receptor sensitivity but normal otolith receptor function or vice versa, should show predictable alterations of body and head movement strategies essential for the control of postural sway and movement. The effect of altered postural movement control upon compensation and/or adaptation will be determined. These experiments provide data for the development of computational models of postural control in normals, vestibular deficient subjects and normal humans exposed to unusual force environments, including orbital space flight.

  17. Root Canal Therapy of a Mandibular First Molar with Five Root Canals: A Case Report

    PubMed Central

    Reyhani, Mohammad Frough; Rahimi, Saeed; Shahi, Shahriar

    2007-01-01

    A mandibular first molar requiring root canal therapy was found with five canals, three mesial canals, and two distal canals. Initially, four canals (mesiobuccal, mesiolingual, distobuccal, and distolingual) were identified. The mesiobuccal and mesiolingual canals were found in their normal locations, and a fifth canal was noted between these two. This case demonstrates a rare anatomical configuration and supplements previous reports of the existence of such configurations in mandibular first molars. PMID:24298291

  18. A Case of Labyrinthine Fistula by Cholesteatoma Mimicking Lateral Canal Benign Paroxysmal Positional Vertigo

    PubMed Central

    Shim, Dae Bo; Ko, Kyung Min; Song, Mee Hyun

    2014-01-01

    Acute peripheral vestibulopathy, of which the chief complaint is positional vertigo, comprises benign paroxysmal positional vertigo (BPPV), labyrinthitis, labyrinthine fistula, and cerebellopontine angle tumors. Since the typical presentation of labyrinthine fistulas may be sensorineural hearing loss, positional vertigo, or disequilibrium, it is often difficult to distinguish from BPPV or Meniere's disease. Herein we report a 61-year-old female patient with typical symptoms and signs attributable to geotropic type variant of the lateral semicircular canal BPPV on the left side, who eventually was confirmed as having a labyrinthine fistula from chronic otitis media with cholesteatoma on the left side. This is another case where, even in the presence of isolated vertigo showing typical findings of acute peripheral vestibulopathy, other otologic symptoms and signs must not be overlooked. PMID:25558413

  19. 173. CANAL TENDER OPERATING LOCK MACHINERY ON THE MORRIS CANAL. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    173. CANAL TENDER OPERATING LOCK MACHINERY ON THE MORRIS CANAL. AS THE LOCK TENDER TURNS THE CRANK, A SMALL COGGED WHEEL (PINION) ON THE CRANK TURNS A LARGER COGGED WHEEL, (MAIN GEAR). MAIN GEAR ENGAGES A COGGED BAR CALLED A TRAVELLER WHICH MOVES FORWARD OR BACK DEPENDING ON WHICH WAY THE CRANK IS TURNED. CONNECTED TO THE TRAVELLER ARE TO LONG RODS (GATE ARMS) WHICH IN TURN ARE CONNECTED TO THE GATE'S TOP BEAM (ONE FOR EACH GATE). AS THE TRAVELLER MOVES FORWARD THE GATE ARMS EXTEND PUSHING THE GATES OPEN. - Morris Canal, Phillipsburg, Warren County, NJ

  20. Free vibrations of thin-walled semicircular graphite-epoxy composite frames

    NASA Technical Reports Server (NTRS)

    Carden, Huey D.; Noor, Ahmed K.; Peters, Jeanne M.

    1990-01-01

    A detailed study is made of the effects of variations in lamination and material parameters of thin walled composite frames on their vibrational characteristics. The structures considered are semicircular thin walled frames with I and J sections. The flanges and webs of the frames are modeled by using 2-D shell and plate finite elements. A mixed formulation is used with the fundamental unknowns consisting of both the generalized displacements and stress resultants in the frame. The frequencies and modes predicted by the 2-D finite element model are compared with those obtained from experiments, as well as with the predictions of a non-dimensional thin walled beam finite element model. A detailed study is made of the sensitivity of the vibrational response to variations in the fiber orientation, material properties of the individual layers, and boundary conditions.

  1. Free vibrations of thin-walled semicircular graphite-epoxy composite frames

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Carden, Huey D.; Peters, Jeanne M.

    1990-01-01

    A detailed study is made of the effects of variations in lamination and material parameters of thin walled composite frames on their vibrational characteristics. The structures considered are semicircular thin walled frames with I and J sections. The flanges and webs of the frames are modelled by using 2-D shell and plate finite elements. A mixed formulation is used with the fundamental unknowns consisting of both the generalized displacements and stress resultants in the frames. The frequencies and modes predicted by the 2-D finite element model are compared with those obtained from experiments, as well as with the predictions of a 1-D thin walled beam finite element model. A detailed study is made of the sensitivity of the vibrational response to variations in the fiber orientation, material properties of the individual layers, and boundary conditions.

  2. Surgical management of special cases of intractable Meniere's disease: unilateral cases with intact canals and bilateral cases.

    PubMed

    Kitahara, Tadashi; Kondoh, Kazumasa; Morihana, Tetsuo; Okumura, Shin-ichi; Mishiro, Yasuo; Kubo, Takeshi

    2004-05-01

    If a clinician seeks to allow patients with vertigo to return to work as soon as possible, it is very important to determine the appearance of vestibular symptoms during convalescence just after treatment, as well as the long-term results. Apprehensive patients with vertigo may undergo severe psychological torment if treatment requires long-term rest in bed before they can return to daily life. In this paper, we observed postoperative vestibular symptoms (subjective sensation and objective nystagmus) in 50 patients with intractable Meniere's disease, including cases from our previous preliminary report, during the period of convalescence just after endolymphatic sac drainage and steroid instillation surgery (EDSS). All symptoms were eliminated within 8 days after EDSS. There was no significant difference in the duration of any vestibular symptoms between bilateral (n = 8) and unilateral cases (n = 42). This result indicates that EDSS could be as safe a treatment for bilateral Meniere's disease as for unilateral disease. In unilateral cases with intact semicircular canal function (n = 17), postoperative evoked vestibular sensation, positional, and positioning (Dix-Hallpike) nystagmus disappeared significantly earlier than in those with canal paresis (n = 25). This result indicates that EDSS could keep the vestibular peripheral function of patients with unilateral Meniere's disease with intact canals quite stable after surgery. Therefore, EDSS could be recommended as an initial, less-invasive surgical treatment for intractable Meniere's disease, especially in unilateral cases with intact canals and in bilateral cases. PMID:15174769

  3. Black Anal Canal: Acute Necrosis

    PubMed Central

    Martins, Catarina; Gonçalves, Cláudia; Alves, Paulo; Gil, Inês; Canhoto, Manuela; Silva, Filipe; Cotrim, Isabel; Amado, Cristina; Eliseu, Liliana; Vasconcelos, Helena

    2016-01-01

    Acute ischemia of the rectum or anal canal resulting in necrosis is extremely uncommon because both the rectum and the anal canal have excellent blood supplies. We present a case with spontaneous necrosis of the anal canal without rectal involvement. Surgical debridement was accomplished, and the recovery was uneventful. The patient was elderly, with probable atherosclerotic arterial disease, and presented with hypotension. Due to the lack of other precipitating factors, the hypoperfusion hypothesis seems to be the most suitable in this case. To the best of our knowledge, no similar cases have been reported in the literature on this subject.

  4. Method for Constructing Standardized Simulated Root Canals.

    ERIC Educational Resources Information Center

    Schulz-Bongert, Udo; Weine, Franklin S.

    1990-01-01

    The construction of visual and manipulative aids, clear resin blocks with root-canal-like spaces, for simulation of root canals is explained. Time, materials, and techniques are discussed. The method allows for comparison of canals, creation of any configuration of canals, and easy presentation during instruction. (MSE)

  5. The facial nerve canal in patients with Bell's palsy: an investigation by high-resolution computed tomography with multiplanar reconstruction.

    PubMed

    Murai, Aya; Kariya, Shin; Tamura, Kouzou; Doi, Akira; Kozakura, Kenichi; Okano, Mitsuhiro; Nishizaki, Kazunori

    2013-07-01

    Facial nerve edema is an important finding in Bell's palsy patients. Inflammation may cause facial nerve edema, and mechanical compression and ischemic change of the facial nerve may occur in the facial nerve canal. A few studies have reported the dimensions of the facial nerve canal using conventional computed tomography or human temporal bone sections. However, the cross-sectional area of the facial nerve canal has not been fully understood. Therefore, the cross-sectional area of the facial nerve canal was measured in patients with unilateral Bell's palsy by computer tomography with multiplanar reconstruction. Sixteen patients with unilateral Bell's palsy were enrolled. Computed tomography of the temporal bone was performed, and perpendicular images to the facial nerve canal were reconstructed by the multiplanar reconstruction technique. The cross-sectional area of the facial nerve canal on the affected and unaffected sides was measured at the labyrinthine segment, the horizontal segment, and the mastoid segment. Both in the labyrinthine and horizontal segments, the mean cross-sectional area of the facial nerve canal was significantly smaller on the affected side than on the unaffected side. There was no significant difference between the affected and unaffected sides in the cross-sectional area of the facial nerve canal in the mastoid segment. The labyrinthine segment was the narrowest segment in the facial nerve canal. These findings suggest that the facial nerve is vulnerable, especially in the labyrinthine segment of the facial nerve canal, and a narrow facial nerve canal may be one of the risk factors for Bell's palsy. PMID:23143560

  6. The Love Canal: Beyond science?

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    When in 1978, the New York State Department of Health issued the report, ‘Love Canal—Public Health Time Bomb,’ the serious effects of chemical waste contamination in the Love Canal area became an issue of national concern. A few ‘studies’ since then have produced results in concert with those of initial reports that described ‘conditions of acute health effects’ as being linked to hazardous wastes incorporated in landfill in the Love Canal site near Niagara Falls, New York. Now that a ‘blue ribbon’ panel of experts from the medical sciences has reviewed the problems of Love Canal, however, a different view has emerged. The ‘Report of the Governors' Panel to Review Scientific Studies and the Development of Public Policy on Problems Resulting from Hazardous Wastes,’ transmitted in October of this year, identifies the following factors about the health effects at Love Canal:

  7. Ultrasonic cleaning of root canals

    NASA Astrophysics Data System (ADS)

    Verhaagen, Bram; Boutsioukis, Christos; Jiang, Lei-Meng; Macedo, Ricardo; van der Sluis, Luc; Versluis, Michel

    2011-11-01

    A crucial step during a dental root canal treatment is irrigation, where an antimicrobial fluid is injected into the root canal system to eradicate all bacteria. Agitation of the fluid using an ultrasonically vibrating miniature file has shown significant improvement in cleaning efficacy over conventional syringe irrigation. However, the physical mechanisms underlying the cleaning process, being acoustic streaming, cavitation or chemical activity, and combinations thereof, are not fully understood. High-speed imaging allows us to visualize the flow pattern and cavitation in a root canal model at microscopic scales, at timescales relevant to the cleaning processes (microseconds). MicroPIV measurements of the induced acoustic streaming are coupled to the oscillation characteristics of the file as simulated numerically and measured with a laser vibrometer. The results give new insight into the role of acoustic streaming and the importance of the confinement for the cleaning of root canals.

  8. Looking back at Love Canal

    SciTech Connect

    Deegan, J. Jr.

    1987-05-01

    In the first part of this series (ES and T, April 1987, pp. 328-31) it was pointed out that the methods and conclusions of EPA's Love Canal Study were the subject of some controversy in the environmental community. Others defended the agency's approaches and methods. Part 2 makes no attempt to resolve the controversy; its purpose is to present the results and conclusions of the Love Canal.

  9. Centering ability and dentin removal of rotary systems in curved root canals

    PubMed Central

    Moradi, Saeed; Talati, Ali; Monajem Zadeh, Ali

    2009-01-01

    INTRODUCTION: The aim of this study was to compare centering ability and dentin removal of three rotary systems in curved root canals of extracted teeth. MATERIALS AND METHODS: Sixty root canals of mandibular first molars with curvatures ranging between 25-35o were divided into three groups of 20 teeth each. Based on pre-instrumentation radiographs that assessed the angle and the radius of canal curvatures, teeth with curvatures were equally spread between the three groups. The root canals were sectioned horizontally at two levels before preparation and then remounted onto the muffle. All root canals were prepared using a low-torque control motor with Mtwo or Medin or Race instruments. Cross sectional images were obtained before and after instrumentation. Cross-sectional area and centering ability were evaluated. The data were analyzed using the one-way ANOVA and Tukey tests. RESULTS: Neither instrument fracture nor permanent deformation occurred during preparations. The best centering ability was obtained by Mtwo instruments compare to Race and Medin instruments. In the coronal and middle sections, Mtwo removed less dentin than Race and Medin; while the difference in the apical section was not significant. CONCLUSION: Under the conditions of this study, the debridement of root canals was more conservative with Mtwo. The canals prepared with these instruments were better centered in all three regions of the root. PMID:24003328

  10. Limitations of navigation through Nubaria canal, Egypt

    PubMed Central

    Samuel, Magdy G.

    2013-01-01

    Alexandria port is the main Egyptian port at the Mediterranean Sea. It is connected to the Nile River through Nubaria canal, which is a main irrigation canal. The canal was designed to irrigate eight hundred thousand acres of agricultural lands, along its course which extends 100 km. The canal has three barrages and four locks to control the flow and allow light navigation by some small barges. Recently, it was decided to improve the locks located on the canal. More than 40 million US$ was invested in these projects. This decision was taken to allow larger barges and increase the transported capacity through the canal. On the other hand, navigation through canals and restricted shallow waterways is affected by several parameters related to both the channel and the vessel. Navigation lane width as well as vessel speed and maneuverability are affected by both the channel and vessel dimensions. Moreover, vessel dimensions and speed will affect the canal stability. In Egypt, there are no guide rules for navigation through narrow and shallow canals such Nubaria. This situation threatens the canal stability and safety of navigation through it. This paper discussed the characteristics of Nubaria canal and the guide rules for navigation in shallow restricted water ways. Dimensions limitation for barges navigating through Nubaria canal is presented. New safe operation rules for navigation in Nubaria canal are also presented. Moreover, the implication of navigation through locks on canal discharge is estimated. PMID:25685482

  11. Differences in gait velocity and trunk acceleration during semicircular turning gait with and without bag in females of very advanced age

    PubMed Central

    Shin, Sun-Shil; Yoo, Won-Gyu

    2016-01-01

    [Purpose] Gait velocity and trunk acceleration during semicircular turning gait with and without carrying a hand-held bag were compared in females of very advanced age. [Subjects and Methods] Ten female volunteers of very advanced age who could walk independently were recruited for this study. Gait velocity and trunk acceleration were measured using an accelerometer during semicircular turning gait with and without carrying a hand-held bag. [Results] Gait velocity during semicircular turning gait was greater with the bag than without the bag. [Conclusions] Trunk stability during semicircular turning gait was higher when the subjects carried a bag. Additional arm load could be considered during gait training in females of very advanced age.

  12. Integration of Canal and Otolith Inputs by Central Vestibular Neurons Is Subadditive for Both Active and Passive Self-Motion: Implication for Perception

    PubMed Central

    Carriot, Jerome; Jamali, Mohsen; Brooks, Jessica X.

    2015-01-01

    Traditionally, the neural encoding of vestibular information is studied by applying either passive rotations or translations in isolation. However, natural vestibular stimuli are typically more complex. During everyday life, our self-motion is generally not restricted to one dimension, but rather comprises both rotational and translational motion that will simultaneously stimulate receptors in the semicircular canals and otoliths. In addition, natural self-motion is the result of self-generated and externally generated movements. However, to date, it remains unknown how information about rotational and translational components of self-motion is integrated by vestibular pathways during active and/or passive motion. Accordingly, here, we compared the responses of neurons at the first central stage of vestibular processing to rotation, translation, and combined motion. Recordings were made in alert macaques from neurons in the vestibular nuclei involved in postural control and self-motion perception. In response to passive stimulation, neurons did not combine canal and otolith afferent information linearly. Instead, inputs were subadditively integrated with a weighting that was frequency dependent. Although canal inputs were more heavily weighted at low frequencies, the weighting of otolith input increased with frequency. In response to active stimulation, neuronal modulation was significantly attenuated (∼70%) relative to passive stimulation for rotations and translations and even more profoundly attenuated for combined motion due to subadditive input integration. Together, these findings provide insights into neural computations underlying the integration of semicircular canal and otolith inputs required for accurate posture and motor control, as well as perceptual stability, during everyday life. PMID:25716854

  13. Horizontal well planning

    SciTech Connect

    Schuh, F.J. )

    1991-03-01

    Interest in horizontal drilling has exploded at a rate well above even the most optimistic projections. Certainly, this technique will not end with the Bakken and Austin Chalk plays. However, future reservoirs will undoubtedly require much more complicated well designs and multi-disciplined technical interaction than has been used so far. The horizontal drilling costs are too high to permit resolving of all the technical issues by trial and error. A multi-disciplinary team approach will be required in order for horizontal drilling to achieve its economic potential.

  14. Stratospheric aerosols in the intertropical convergence zone, Panama Canal zone

    NASA Technical Reports Server (NTRS)

    Farlow, N. H.; Ferry, G. V.; Lem, H. Y.; Hayes, D. M.

    1979-01-01

    To investigate whether injection sources of the stratospheric aerosol layer could be detected in the tropical stratosphere, an examination of the aerosol vertical and horizontal size distribution around the Intertropical Convergence Zone (ITCZ) at the Panama Canal Zone was performed during the summer of 1977. By comparing these data with similar measurements in temperate and polar regions, it was hoped to discover variations in particle size that would indicate whether a young aerosol is forming and entering the stratosphere at the ITCZ; where the aerosol matures; and finally, where it reenters the troposphere. The methods used in the investigations and the results obtained from the analyses are described.

  15. Investigation of otolith responses using ground based vestibular research facility

    NASA Technical Reports Server (NTRS)

    Correia, Manning J.; TABARACCI

    1989-01-01

    The general goal was to examine tilt sensitivity of horizontal semicircular canal afferents. Computer programs were tested which controlled the short axis centrifuge at the Vestibular Research Facility, acquired action potentials and produced data reduction analyses including histograms and gain and phase calculations. A pre-amplifier was also developed for the acquisition of action potentials. The data were gathered that can be used to contribute toward the understanding of the tilt sensitivity of semicircular canal afferents in the unanesthetized gerbil preparation.

  16. Assessing morphology and function of the semicircular duct system: introducing new in-situ visualization and software toolbox.

    PubMed

    David, R; Stoessel, A; Berthoz, A; Spoor, F; Bennequin, D

    2016-01-01

    The semicircular duct system is part of the sensory organ of balance and essential for navigation and spatial awareness in vertebrates. Its function in detecting head rotations has been modelled with increasing sophistication, but the biomechanics of actual semicircular duct systems has rarely been analyzed, foremost because the fragile membranous structures in the inner ear are hard to visualize undistorted and in full. Here we present a new, easy-to-apply and non-invasive method for three-dimensional in-situ visualization and quantification of the semicircular duct system, using X-ray micro tomography and tissue staining with phosphotungstic acid. Moreover, we introduce Ariadne, a software toolbox which provides comprehensive and improved morphological and functional analysis of any visualized duct system. We demonstrate the potential of these methods by presenting results for the duct system of humans, the squirrel monkey and the rhesus macaque, making comparisons with past results from neurophysiological, oculometric and biomechanical studies. Ariadne is freely available at http://www.earbank.org. PMID:27604473

  17. Assessing morphology and function of the semicircular duct system: introducing new in-situ visualization and software toolbox

    PubMed Central

    David, R.; Stoessel, A.; Berthoz, A.; Spoor, F.; Bennequin, D.

    2016-01-01

    The semicircular duct system is part of the sensory organ of balance and essential for navigation and spatial awareness in vertebrates. Its function in detecting head rotations has been modelled with increasing sophistication, but the biomechanics of actual semicircular duct systems has rarely been analyzed, foremost because the fragile membranous structures in the inner ear are hard to visualize undistorted and in full. Here we present a new, easy-to-apply and non-invasive method for three-dimensional in-situ visualization and quantification of the semicircular duct system, using X-ray micro tomography and tissue staining with phosphotungstic acid. Moreover, we introduce Ariadne, a software toolbox which provides comprehensive and improved morphological and functional analysis of any visualized duct system. We demonstrate the potential of these methods by presenting results for the duct system of humans, the squirrel monkey and the rhesus macaque, making comparisons with past results from neurophysiological, oculometric and biomechanical studies. Ariadne is freely available at http://www.earbank.org. PMID:27604473

  18. Conventional Versus Digital Radiography in Detecting Root Canal Type in Maxillary Premolars: An in Vitro Study

    PubMed Central

    Moshfeghi, Mahkameh; Sajadi, Soodabeh Sadat; Sajadi, Sepideh; Shahbazian, Majid

    2013-01-01

    Objective: Successful endodontic therapy depends on adequate mechanical and chemical debridement of the canal which requires knowledge of the canal morphology. Conventional radiography has been used to evaluate the canal type; however, direct digital radiography has recently been practiced for this purpose due to the shortcomings of conventional radiography. The aim of the present study was to compare the accuracy of digital and conventional radiography taken at 0° and 30° angles in the diagnosis of the canal type of extracted maxillary premolars. Materials and Methods: This diagnostic study was performed on 90 extracted maxillary premolars. Conventional and digital radiographies were taken of all teeth at 0° and 30° horizontal angles. The images were assessed by an oral and maxillofacial radiologist. The clearing technique was used as the gold standard. The canal type was determined using Weine classification. The agreement between each one of the 4 radiographic modalities and gold standard was determined by kappa statistics. Results: The kappa values for the agreement of parallel conventional, 30° conventional, parallel digital and 30° digital modalities with the clearing technique were 0.059, 0.215, 0.043 and 0.391, respectively. Parallel modalities were unable to determine the tooth canal type. Radiographic images taken at 30° significantly determined the canal type, although only a poor level of agreement was noted between the two modalities and the clearing technique. Conclusion: All modalities had limited value to determine the root canal type in maxillary premolars. However, direct digital imaging taken at 30° angle showed the highest accuracy for canal type assessment. PMID:23724205

  19. A mathematical approach enabling the calculation of the total endolymph flow in the semicircular ducts.

    PubMed

    Muller, M; Verhagen, J H

    1988-10-21

    1. A mathematical treatment of the flow inside the vertebrate labyrinth is given. The main difference to former theories (e.g. the "torsion pendulum" theory) is that the entire system formed by the three semicircular ducts, interconnected by the crus commune and the utriculus, is considered, instead of a single duct circuit. 2. The theory consists of a geometrical description of a labyrinth rotating in space, the solution of the continuity equation, determination of the initial velocities in all the ducts in a "cupulometry" experiment and derivation of the equation of motion (e.o.m.). 3. Equations for a system consisting of two ducts and for the classical single-duct system are special cases of the three-duct system. 4. Three different methods for the solution of the e.o.m. are described: an analytical one, a Runge-Kutta simulation and an "asymptotic" method. The last method includes approximations of the solution of the e.o.m. on a long and a short time scale. Its advantage is that it gives an insight based on rather manageable formulae. 5. The physiological basis of the presented theory, biological applications and verification are given in a separate paper (Muller & Verhagen, 1988). PMID:3255008

  20. Corinth Canal, Greece

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Isthmus of Corinth has played a very important role in the history of Greece. It is the only land bridge between the country's north (Attica) and south (Peloponnese). It is a 6 km wide tongue of land separating the Gulf of Corinth from the Saronic Sea. Populations, armies and commodities have got to move through it. In the 6th century BCE, the Greeks built the Diolkos, a 10 meter-wide stone roadway to pull ships across the Isthmus on wooden cylinders and wheeled vehicles. In 1882, a canal was started and completed 11 years later. It is 6343 meters long, 25 meters wide, and 8 meters deep.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 25.3 by 37.7 kilometers (15.7 by 23.4 miles) Location: 37.9 degrees North latitude, 23 degrees East longitude

  1. Assessment of the effects of superior canal dehiscence location and size on intracochlear sound pressures.

    PubMed

    Niesten, Marlien E F; Stieger, Christof; Lee, Daniel J; Merchant, Julie P; Grolman, Wilko; Rosowski, John J; Nakajima, Hideko Heidi

    2015-01-01

    Superior canal dehiscence (SCD) is a defect in the bony covering of the superior semicircular canal. Patients with SCD present with a wide range of symptoms, including hearing loss, yet it is unknown whether hearing is affected by parameters such as the location of the SCD. Our previous human cadaveric temporal bone study, utilizing intracochlear pressure measurements, generally showed that an increase in dehiscence size caused a low-frequency monotonic decrease in the cochlear drive across the partition, consistent with increased hearing loss. This previous study was limited to SCD sizes including and smaller than 2 mm long and 0.7 mm wide. However, the effects of larger SCDs (>2 mm long) were not studied, although larger SCDs are seen in many patients. Therefore, to answer the effect of parameters that have not been studied, this present study assessed the effect of SCD location and the effect of large-sized SCDs (>2 mm long) on intracochlear pressures. We used simultaneous measurements of sound pressures in the scala vestibuli and scala tympani at the base of the cochlea to determine the sound pressure difference across the cochlear partition - a measure of the cochlear drive in a temporal bone preparation - allowing for assessment of hearing loss. We measured the cochlear drive before and after SCDs were made at different locations (e.g. closer to the ampulla of the superior semicircular canal or closer to the common crus) and for different dehiscence sizes (including larger than 2 mm long and 0.7 mm wide). Our measurements suggest the following: (1) different SCD locations result in similar cochlear drive and (2) larger SCDs produce larger decreases in cochlear drive at low frequencies. However, the effect of SCD size seems to saturate as the size increases above 2-3 mm long and 0.7 mm wide. Although the monotonic effect was generally consistent across ears, the quantitative amount of change in cochlear drive due to dehiscence size varied across ears

  2. 11. VIEW OF HORIZONTAL MIXER (GedgeGray Co., Lockland, Ohio), LOCATED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. VIEW OF HORIZONTAL MIXER (Gedge-Gray Co., Lockland, Ohio), LOCATED IN THE BASEMENT, MIXED ANIMAL FEED TO ORDER. THE WATER-POWERED MIXER WAS SUPERSEDED BY TWO ELECTRIC-POWERED VERTICAL MIXERS, ADDED IN THE 1940S. Photographer: Louise Taft Cawood, July 1986 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH

  3. Erie Canal Technology: Stump Pullers

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2013-01-01

    Many years ago I saw a picture of a huge set of wheels that was used to remove tree stumps during the construction of the Erie Canal (1817-1825) and was intrigued by its use of leverage, mechanical advantage, and torque. Figure 1 is a scale model of the device based on my memory of the (lost) picture and published accounts.

  4. Erie Canal Technology: Stump Pullers

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2013-10-01

    Many years ago I saw a picture of a huge set of wheels that was used to remove tree stumps during the construction of the Erie Canal (1817-1825) and was intrigued by its use of leverage, mechanical advantage, and torque. Figure 1 is a scale model of the device based on my memory of the (lost) picture and published accounts.

  5. Using the Semi-Circular Bending Test to Investigate the Interaction Between Hydraulic and Natural Fractures

    NASA Astrophysics Data System (ADS)

    Wang, W.; Olson, J. E.; Prodanovic, M.

    2014-12-01

    Micro-seismic data shows that hydraulic fracture propagation is a complex process. When hydraulic fractures interact with pre-existing natural fractures, it can result in a complex fracture network. The interaction depends on in-situ stresses, rock and natural fracture mechanical properties, approach angle and hydraulic fracture treatment parameters. Most simulation studies treat natural fractures as frictional interfaces with cohesive properties. However, from core observation, partially cemented and fully cemented natural fractures are widely present and it is not clear that whether they fit the common description or not. In this study, semi-circular bending experiments are utilized to examine the fracture propagation paths. Synthetic hydrostone samples with embedded inclusions of different mechanical properties are used to mimic rock and cemented natural fractures. Simulation results are generated using finite element software ABAQUS. The extended finite element method (XFEM) capability of ABAQUS allows the fracture initiation and propagation along a solution dependent path without the need for re-meshing. The simulation results are used to explain the experimental observations. In a series of experiment and modeling work, we assess the influence of the fracture approach angle, inclusion strength, and inclusion thickness on fracture propagation. Current results indicate the fracture propagation direction is strongly influenced by pre-existing inclusions. The propagating fractures tend to cross the inclusion when the approach angle is high and divert into the inclusion when the approach angle is low. The crossing surface is thus not a clean cut, but with a jog distance that depends on the inclusion thickness and approach angle. Results imply that if hydraulic fractures have lower approach angles to pre-existing natural fractures, the ultimate fracture network is going to have higher complexity. The thickness of natural fractures can also add to the complexity.

  6. Horizontal drilling spurs optimism

    SciTech Connect

    Crouse, P.C. )

    1991-02-01

    1990 proved to be an exciting year for horizontal wells. This budding procedure appears to be heading for the mainstream oil and gas market, because it can more efficiently recover hydrocarbons from many reservoirs throughout the world. This paper reports on an estimated 1,000 wells that were drilled horizontally (all laterals) in 1990, with the Austin Chalk formation of Texas accounting for about 65% of all world activity. The Bakken Shale play in Montana and North Dakota proved to be the second most active area, with an estimated 90 wells drilled. Many operators in this play have indicated the bloom may be off the Bakken because of poor results outside the nose of the formation, further complicated by some of the harshest rock, reservoir and completion problems posed to horizontal technology.

  7. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  8. Horizontal Advanced Tensiometer

    SciTech Connect

    Hubbell, Joel M.; Sisson, James B.

    2004-06-22

    An horizontal advanced tensiometer is described that allows the monitoring of the water pressure of soil positions, particularly beneath objects or materials that inhibit the use of previous monitoring wells. The tensiometer includes a porous cup, a pressure transducer (with an attached gasket device), an adaptive chamber, at least one outer guide tube which allows access to the desired horizontal position, a transducer wire, a data logger and preferably an inner guide tube and a specialized joint which provides pressure on the inner guide tube to maintain the seal between the gasket of the transducer and the adaptive chamber.

  9. Diffraction of planar shock waves over half-diamond and semicircular cylinders: An experimental and numerical comparison

    SciTech Connect

    Glass, I.I.; Kaca, J.; Zhang, D.L. ); Glaz, H.M. ); Bell, J.B.; Trangenstein, J.A. ); Collins, J.P. )

    1990-07-30

    The problem of an incident planar shock interacting with a downstream obstacle is studied here: half-diamond and semicircular cylinders are chosen for the obstacles. Experimental data is taken from the UTIAS shock tube facility; in particular; infinite-fringe inteferograms are analyzed which provides full flowfield data. Numerical results are obtained using a new unsplit version of the second-order Eulerian Godunov scheme for inviscid gas dynamics which is capable of computing on general, body conforming meshes. Detailed comparisons of the two techniques are offered, and excellent agreement is confirmed.

  10. Rotations in a vertebrate setting: evaluation of the symmetry group of the disynaptic canal-neck projection.

    PubMed

    McCollum, Gin; Boyle, Richard

    2004-03-01

    Organizational structures intrinsic to nervous systems can be more precisely analyzed and compared with other logical structures once they are expressed in mathematical languages. A standard mathematical language for expressing organizational structure is that of groups. Groups are especially well suited to organizational structures involving multiple symmetries such as spatial structures. The vestibular system is widely believed to mediate many neural functions involving spatial structure. The vestibular nuclei receive direct projections from the vestibular endorgans, the semicircular canals and the otolith organs. The near-orthogonal directions of the semicircular canals are embedded in the bone. However, those canal directions are external to the nervous system. This study addresses the way the three-dimensional space of rotations is also embedded in the group structure of neural connectivity. Although we know a great deal about physical rotation, it is not clear that nervous systems organize rotations in the same way as physicists do. It would make sense for nervous systems to organize rotations in such a way as to provide physiologically relevant information about performing or compensating for rotations. The vestibular nuclei, which might be expected to display an organization that binds rotations into a rotation space, do not give a clear organization. This may be because of the multiplicity of spatial functions performed by the vestibular nuclei; rather than one spatial organization, the vestibular nuclei are likely to accommodate multiple, related spatial organizations. This study evaluates one particular data set from the literature that specifies the organization of the disynaptic canal-neck projection; other projections and neuronal populations may have other intrinsic organizations. The data are evaluated directly for their symmetry group. In the symmetry group, the vertebrate requirement that physiology have a right and left is found to be satisfied

  11. The suppression effect of a periodic surface with semicircular grooves on the high power microwave long pill-box window multipactor phenomenon

    SciTech Connect

    Zhang, Xue Wang, Yong; Fan, Junjie; Zhong, Yong; Zhang, Rui

    2014-09-15

    To improve the transmitting power in an S-band klystron, a long pill-box window that has a disk with grooves with a semicircular cross section is theoretically investigated and simulated. A Monte-Carlo algorithm is used to track the secondary electron trajectories and analyze the multipactor scenario in the long pill-box window and on the grooved surface. Extending the height of the long-box window can decrease the normal electric field on the surface of the window disk, but the single surface multipactor still exists. It is confirmed that the window disk with periodic semicircular grooves can explicitly suppress the multipactor and predominantly depresses the local field enhancement and the bottom continuous multipactor. The difference between semicircular and sharp boundary grooves is clarified numerically and analytically.

  12. The suppression effect of a periodic surface with semicircular grooves on the high power microwave long pill-box window multipactor phenomenon

    NASA Astrophysics Data System (ADS)

    Zhang, Xue; Wang, Yong; Fan, Junjie; Zhong, Yong; Zhang, Rui

    2014-09-01

    To improve the transmitting power in an S-band klystron, a long pill-box window that has a disk with grooves with a semicircular cross section is theoretically investigated and simulated. A Monte-Carlo algorithm is used to track the secondary electron trajectories and analyze the multipactor scenario in the long pill-box window and on the grooved surface. Extending the height of the long-box window can decrease the normal electric field on the surface of the window disk, but the single surface multipactor still exists. It is confirmed that the window disk with periodic semicircular grooves can explicitly suppress the multipactor and predominantly depresses the local field enhancement and the bottom continuous multipactor. The difference between semicircular and sharp boundary grooves is clarified numerically and analytically.

  13. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Joint, Vertical Cross Bracing End Detail - Ceylon Covered Bridge, Limberlost Park, spanning Wabash River at County Road 900 South, Geneva, Adams County, IN

  14. Horizontal geophone transducer assembly

    SciTech Connect

    Hefer, F.W.

    1985-06-25

    The geophone transducer comprises in combination: a geophone capable of detecting horizontal seismic waves, and a rigid casing having a gimbal chamber. A gimbal is provided inside the chamber on which the geophone is mounted for limited free angular movement in one direction only. The gimbal includes in one preferred embodiment a viscous liquid in which the geophone is only partially submerged while it is supported by a U-shaped bracket which is mounted for rotation about a fixed axis.

  15. 160. Photocopy of drawing (taken from Twin Falls Canal Company ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    160. Photocopy of drawing (taken from Twin Falls Canal Company Field Book #361 #86, page 1). SCALE DRAWING, CANAL HEADGATES AND CANAL SURVEY, 'A' LINE. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

  16. Management of Six Root Canals in Mandibular First Molar

    PubMed Central

    Gomes, Fabio de Almeida; Sousa, Bruno Carvalho

    2015-01-01

    Success in root canal treatment is achieved after thorough cleaning, shaping, and obturation of the root canal system. This clinical case describes conventional root canal treatment of an unusual mandibular first molar with six root canals. The prognosis for endodontic treatment in teeth with abnormal morphology is unfavorable if the clinician fails to recognize extra root canals. PMID:25685156

  17. Optimization of the mechanical performance of a two-duct semicircular duct system--part 2: excitation of endolymph movements.

    PubMed

    Muller, M; Verhagen, J H G

    2002-06-21

    The endolymph flow inside the semicircular ducts is analytically investigated by considering a system of two hydrodynamically interconnected ducts. Rotation of this system adds an amount of motion (momentum) to parts of it. This results in an endolymph flow in generally all vestibular parts. The "external impulses" are the impulses which emerge by rotation of exclusively a particular vestibular part. The real impulses can be calculated from a set of equations which contain the external impulses. Analytical expressions are derived for the initial velocities in the ducts and for the maximum endolymph displacements. These formulae contain the external impulses and the ratios of: (1) the radii of crus commune and ducts (gamma), (2) the lengths of crus commune and ducts (lambda). It was proven that an interconnected system composed of two ducts, and also a system composed of two such semicircular duct systems, behaves as a pure rotation transducer (like a single duct does), also when it is rotated excentrically. Duct systems with polygonal and circular geometries were used to evaluate whether an optimal value of lambda would exist (gamma was already considered elsewhere). Optimum values of lambda in a range of about 0.10-0.52 were found. This rather wide range of values agrees with values from measurements. Optimization of an interconnected duct system appeared to be equal to optimization of a system composed of separate ducts. PMID:12151259

  18. Pathologic diagnosis of central centrifugal cicatricial alopecia on horizontal sections.

    PubMed

    Miteva, Mariya; Tosti, Antonella

    2014-11-01

    The pathologic findings in Central Centrifugal Cicatricial Alopecia (CCCA) have not been studied systematically in horizontal sections. Our objective was to establish the pathologic features, and their frequency in horizontal sections of scalp biopsies obtained from patients with clinically and histologically proven CCCA. Serial horizontal sections of 51 cases were evaluated retrospectively. All biopsies were assessed at 4 levels and at least on 24 horizontal sections. The most common pathologic findings were follicular miniaturization (81% of the cases); premature desquamation of the inner root sheath (96%), focal preservation of the sebaceous glands (94%), which in most of these cases appeared as surrounding "in a hug" an intact vellus follicle; compound follicular structures with perifollicular fibrosis and/or inflammation (89%), lamellar hyperkeratosis/parakeratosis in the hair canal (79%), absent or mild inflammation (77%), and naked hair shafts (68%). Horizontal sections are useful in CCCA to identify early or focal disease and to provide the clinician with better information on the presence of follicular miniaturization, inflammation, and scarring, which can be used to tailor the treatment to the individual patient. PMID:25222198

  19. Developmental spinal canal stenosis and somatotype.

    PubMed Central

    Nightingale, S

    1989-01-01

    The hypothesis that somatotype and cervical spine developmental canal stenosis may be associated has been investigated by anthropometry and measurement of lateral projection cervical spine radiographs. A significant association of canal size with somatotype has been found such that those with developmentally narrow canals are more likely to have relatively shorter long-bones, particularly in the upper arm, and longer trunks. Images PMID:2769282

  20. Complicated canal morphology of mandibular first premolar

    PubMed Central

    Pallavi, Vyapaka; Kumar, Janga Ravi; Mandava, Ramesh Babu; Rao, Subramanian Hari

    2015-01-01

    The aim of this article was to report an unusual anatomic variation of mandibular first premolar, with one root and three distinct canals, which leave pulp chamber and merge short of apex to exit as two separate apical foramina. The incidence of three canals existing as two apical foramina has only been documented in the literature by a few case reports. To achieve successful endodontic treatment, the clinician has to identify the different canal configurations and treat them properly. PMID:26538977

  1. Chlorhexidine as a canal irrigant: a review.

    PubMed

    Ryan, Steven

    2010-06-01

    The use of an irrigant during root canal therapy is an important factor in the cleaning and disinfecting of the root canal system. While sodium hypochlorite has been used for decades as a primary irrigant, other irrigants have been investigated as alternatives. This article reviews chlorhexidine as a canal irrigant, explores its different properties, and provides the dental practitioner with information to help make a more informed decision when choosing an irrigant. PMID:20583503

  2. A comparison of stainless steel and nickel-titanium K-files in curved root canals.

    PubMed

    Chan, A W; Cheung, G S

    1996-11-01

    The purpose of this study was to determine the effects of hand instrumentation using traditional stainless steel K-files and nickel-titanium K-files on the final shape of curved root canals. A total of 24 moderately curved canals in the mesial roots in extracted human mandibular first molars were randomly divided into two groups. These were instrumented manually using either stainless steel or nickel-titanium, K-files with the stepdown technique. The cross-sectional shape of each canal at three different horizontal levels were captured, before and after instrumentation, into a computer for comparison using image analyser software. Three parameters at each level were evaluated: (i) amount of dentine removed; (ii) least remaining dentine thicknesses on mesial and furcal aspects; and (iii) the amount and direction of canal transportation. The results showed that the two file types removed similar amounts of dentine at all three levels examined. The nickel-titanium files left a thicker layer of dentine on both the mesial and furcal aspects than stainless steel files. However, the difference was not significant (pooled T-test, P > 0.05). Both types of files transported the centre of the canals but the nickel-titanium instrument seemed to be safer because of the reduced amount of transportation towards the danger areas. PMID:10332236

  3. Hypoglossal canal size and hominid speech

    PubMed Central

    DeGusta, David; Gilbert, W. Henry; Turner, Scott P.

    1999-01-01

    The mammalian hypoglossal canal transmits the nerve that supplies the motor innervation to the tongue. Hypoglossal canal size has previously been used to date the origin of human-like speech capabilities to at least 400,000 years ago and to assign modern human vocal abilities to Neandertals. These conclusions are based on the hypothesis that the size of the hypoglossal canal is indicative of speech capabilities. This hypothesis is falsified here by the finding of numerous nonhuman primate taxa that have hypoglossal canals in the modern human size range, both absolutely and relative to oral cavity volume. Specimens of Australopithecus afarensis, Australopithecus africanus, and Australopithecus boisei also have hypoglossal canals that, both absolutely and relative to oral cavity volume, are equal in size to those of modern humans. The basis for the hypothesis that hypoglossal canal size is indicative of speech was the assumption that hypoglossal canal size is correlated with hypoglossal nerve size, which in turn is related to tongue function. This assumption is probably incorrect, as we found no apparent correlation between the size of the hypoglossal nerve, or the number of axons it contains, and the size of the hypoglossal canal in a sample of cadavers. Our data demonstrate that the size of the hypoglossal canal does not reflect vocal capabilities or language usage. Thus the date of origin for human language and the speech capabilities of Neandertals remain open questions. PMID:9990105

  4. Love Canal: environmental and toxicological studies

    SciTech Connect

    Kim, C.S.

    1981-01-01

    The New York State Department of Health has been involved at the Love Canal since 1978. The State has carried out numerous environmental and toxicological studies. The major purposes for these studies were to define how Love Canal contaminants might be escaping into the environment at large, what paths contaminant migration might take, and what toxicological effects Love Canal chemicals might have individually and together. Although underground contaminant migration was hypothesized along swales and underground utility bedding, these mechanisms have been proven not to be operative except for some migration along the utility bedding under Frontier Avenue. In general no underground migration has occurred outside the confines of the three city blocks that contain the Love Canal referred to as the ''first ring''. Studies have been confused by apparent burial of waste materials in areas proximate but not directly connected to the Love Canal. Migration of Love Canal leachate has occurred through storm sewers. Love Canal contaminants have reached creeks to the north and the Niagara River to the south through storm sewer transport. In spite of finding 2, 3, 7, 8 tetrachlorodibenzoparadioxin (TCDD), toxicological studies in situ and through exposure to volatile components in Love Canal soils do not indicate unusual toxicity. Animal studies continue in an attempt to determine the teratogenic and fetotoxic potential of Love Canal chemicals under different routes of exposure.

  5. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  6. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  7. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  8. 5 CFR 315.601 - Appointment of former employees of the Canal Zone Merit System or Panama Canal Employment System.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Canal Zone Merit System or Panama Canal Employment System. 315.601 Section 315.601 Administrative... employees of the Canal Zone Merit System or Panama Canal Employment System. (a) Agency authority. This... Zone Merit System, which was in effect before March 31, 1982, or under the Panama Canal...

  9. SECTION OF CANAL AT PROPOSED McLELLAN DRIVE INTERCHANGE, SHOWING CANAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SECTION OF CANAL AT PROPOSED McLELLAN DRIVE INTERCHANGE, SHOWING CANAL (RIGHT), BRIDAL TRAIL (CENTER) AND PEDESTRIAN/BICYCLE TRAIL (RIGHT). VIEW TO NORTH - High Line Canal, Mouth of South Platte River to confluence with Second Creek, Denver, Denver County, CO

  10. Horizontal drilling in shallow reservoirs

    SciTech Connect

    Murray, W.F. Jr.; Schrider, L.A.; Haynes, C.D.; Mazza, R.L.

    1992-06-01

    The objectives of this joint horizontal drilling effort by the US DOE and Belden & Blake in the complex, low permeability Clinton Sandstone will focus on the following objectives: (1) apply horizontal drilling technology in hard, abrasive, and tight Clinton Sandstone; (2) evaluate effects of multiple hydraulic fracturing in a low permeability horizontal wellbore; (3) assess economic viability of horizontal drilling in the Clinton and similar tight gas sands.

  11. Horizontal drilling in shallow reservoirs

    SciTech Connect

    Murray, W.F. Jr.; Schrider, L.A.; Haynes, C.D.; Mazza, R.L.

    1992-01-01

    The objectives of this joint horizontal drilling effort by the US DOE and Belden Blake in the complex, low permeability Clinton Sandstone will focus on the following objectives: (1) apply horizontal drilling technology in hard, abrasive, and tight Clinton Sandstone; (2) evaluate effects of multiple hydraulic fracturing in a low permeability horizontal wellbore; (3) assess economic viability of horizontal drilling in the Clinton and similar tight gas sands.

  12. Long-Period Cultural Noise: The Panama Canal Seiche

    NASA Astrophysics Data System (ADS)

    McNamara, D. E.; Hutt, C. R.; Ringler, A.; Gee, L. S.

    2009-12-01

    Traditionally, the spectral composition of human generated or “cultural” seismic noise is dominated by short-period (SP) energy (<1s). In this study, we present evidence for long-period (LP) cultural noise (100-200s) at the USGS Global Seismographic Network (GSN) station CU.BCIP, located at the Smithsonian Tropical Research Institute (STRI) on Barro Colorado Island (BCI) in the Panama Canal. The LP seismic energy has a strong diurnal signal, with highest power during the daytime when traffic through the Panama Canal is the heaviest, ~1 ship every 10 minutes. The lowest power occurs during the late-night/early-morning hours, when container ship traffic slows to ~1 ship every hour. Spectral power observations are corroborated with data recorded by a water-level meter located approximately 80m from the seismic station, indicating that water waves are the primary source of the LP seismic signal. We show that the observed water waves are a “seiche” induced by the wakes of container ship traffic in the canal. As passing ships disturb the water surface, standing waves are induced by the summation of propagating waves, traveling in opposite directions, due to reflections off the opposite shorelines of the Panama Canal. Vertical harmonic motion results as gravity seeks to restore the horizontal surface of the body of water to a state of hydrostatic equilibrium. The longest natural-period of a seiche in an enclosed body of water is a function of basin depth and length and can be computed by a common oceanographic relationship, known as the Merian formula. For a reasonable range of Panama Canal dimensions in the vicinity of BCI, (depths from 15 to 30m and lengths from 700 to 1500m), the predicted dominant period of a seiche is between 100-200s, consistent with our seismic spectral power observations. Small rhythmic seiches are always present in disturbed enclosed bodies of water and are most often caused by either meteorological effects (wind and atmospheric pressure

  13. 63. PLANS FOR PROPOSED HISTORICAL CANAL SECTION AND PUBLIC BOAT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. PLANS FOR PROPOSED HISTORICAL CANAL SECTION AND PUBLIC BOAT LAUNCH RAMP Plan Sheet D-29976, Venice Canals Rehabilitation, Sheet 25 of 26 (delineated by Manuel Bartolome, November 1991) - Venice Canals, Community of Venice, Los Angeles, Los Angeles County, CA

  14. 10. DETAIL, SOUTHEAST SPAN THROUGH CANAL, VIEW BLOCKED BY STEEL, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL, SOUTHEAST SPAN THROUGH CANAL, VIEW BLOCKED BY STEEL, CLAD COUNTER WEIGHT, WATER SPAN RAISED OUT OF VIEW - Cape Cod Canal Lift Bridge, Spanning Cape Cod Canal, Buzzards Bay, Barnstable County, MA

  15. 3. August, 1971. VIEW ALONG CANAL SHOWING BORDER PATH AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. August, 1971. VIEW ALONG CANAL SHOWING BORDER PATH AND BRIDGE FOR INSPECTION - ABOUT ONE MILE FROM CANAL HEAD. - Hurricane Irrigation Canal, State Route 15 Vicinity, Hurricane, Washington County, UT

  16. OBLIQUE VIEW OF NORTHWEST SIDE OF 2195 SOUTHWEST CANAL STREET, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OBLIQUE VIEW OF NORTHWEST SIDE OF 2195 SOUTHWEST CANAL STREET, VIEW TOWARDS SOUTHEAST - St. Lucie Canal, Lock No. 1, Attendant's Quarters, St. Lucie, Cross State Canal, Okeechobee Intracoastal Waterway, Stuart, Martin County, FL

  17. OBLIQUE VIEW OF SOUTHEAST SIDE OF 2195 SOUTHWEST CANAL STREET, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OBLIQUE VIEW OF SOUTHEAST SIDE OF 2195 SOUTHWEST CANAL STREET, VIEW TOWARDS NORTH - St. Lucie Canal, Lock No. 1, Attendant's Quarters, St. Lucie, Cross State Canal, Okeechobee Intracoastal Waterway, Stuart, Martin County, FL

  18. 2. BLACK RIVER CANAL SUPPLY FROM END OF MAIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. BLACK RIVER CANAL - SUPPLY FROM END OF MAIN CANAL TO BLACK RIVER. VIEW TO SOUTHWEST - Carlsbad Irrigation District, Black River Canal, 15 miles Southeast of Carlsbad near Malaga, Carlsbad, Eddy County, NM

  19. 15. VIEW OF GAGE IRRIGATION CANAL NEAR HILLTOP DRIVE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. VIEW OF GAGE IRRIGATION CANAL NEAR HILLTOP DRIVE AND BARTON ROAD, SHOWING END OF SIPHON. CANAL FOLLOWS CONTOUR OF HILL UNDER DIRT ROAD - Gage Irrigation Canal, Running from Santa Ana River to Arlington Heights, Riverside, Riverside County, CA

  20. 11. 'Y' CONNECTOR TO PICACHO RESERVOIR ON MAIN CANAL. VIEW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. 'Y' CONNECTOR TO PICACHO RESERVOIR ON MAIN CANAL. VIEW LOOKING WEST FROM MAIN CANAL - San Carlos Irrigation Project, Marin Canal, Amhurst-Hayden Dam to Picacho Reservoir, Coolidge, Pinal County, AZ

  1. Lock No. 1 St. Lucie Canal. Sector gates, internal struts ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Lock No. 1- St. Lucie Canal. Sector gates, internal struts- nose beams. - St. Lucie Canal, St. Lucie Lock No. 1, St. Lucie, Cross State Canal, Okeechobee Intracoastal Waterway, Stuart, Martin County, FL

  2. Dundee Canal Industrial Historic District, Beginning at George Street in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Dundee Canal Industrial Historic District, Beginning at George Street in Passaic & extending north along Dundee Canal approximately 1.2 miles to Canal headgates opposite East Clifton Avenue in Clifton, Passaic, Passaic County, NJ

  3. Five Canalled and Three-Rooted Primary Second Mandibular Molar

    PubMed Central

    Selvakumar, Haridoss; Kavitha, Swaminathan; Bharathan, Rajendran; Varghese, Jacob Sam

    2014-01-01

    A thorough knowledge of root canal anatomy and its variation is necessary for successful completion of root canal procedures. Morphological variations such as additional root canals in human deciduous dentition are rare. A mandibular second primary molar with more than four canals is an interesting example of anatomic variations, especially when three of these canals are located in the distal root. This case shows a rare anatomic configuration and points out the importance of looking for additional canals. PMID:25147744

  4. Five canalled and three-rooted primary second mandibular molar.

    PubMed

    Selvakumar, Haridoss; Kavitha, Swaminathan; Bharathan, Rajendran; Varghese, Jacob Sam

    2014-01-01

    A thorough knowledge of root canal anatomy and its variation is necessary for successful completion of root canal procedures. Morphological variations such as additional root canals in human deciduous dentition are rare. A mandibular second primary molar with more than four canals is an interesting example of anatomic variations, especially when three of these canals are located in the distal root. This case shows a rare anatomic configuration and points out the importance of looking for additional canals. PMID:25147744

  5. Root Canal Treatment of a Maxillary Second Premolar with Two Palatal Root Canals: A Case Report.

    PubMed

    Golmohammadi, Maryam; Jafarzadeh, Hamid

    2016-01-01

    Accurate diagnosis of the root canal morphology and anatomy is essential for thorough shaping and cleaning of the entire root canal system and consequent successful treatment. This report describes a case of maxillary second premolar with two roots and three root canals (two mesial and distal palatal canals). The case report underlines the importance of complete knowledge about root canal morphology and possible variations, coupled with clinical and radiographic examination in order to increase the ability of clinicians to treat difficult cases. PMID:27471538

  6. Root Canal Treatment of a Maxillary Second Premolar with Two Palatal Root Canals: A Case Report

    PubMed Central

    Golmohammadi, Maryam; Jafarzadeh, Hamid

    2016-01-01

    Accurate diagnosis of the root canal morphology and anatomy is essential for thorough shaping and cleaning of the entire root canal system and consequent successful treatment. This report describes a case of maxillary second premolar with two roots and three root canals (two mesial and distal palatal canals). The case report underlines the importance of complete knowledge about root canal morphology and possible variations, coupled with clinical and radiographic examination in order to increase the ability of clinicians to treat difficult cases. PMID:27471538

  7. Horizontal baffle for nuclear reactors

    DOEpatents

    Rylatt, John A.

    1978-01-01

    A horizontal baffle disposed in the annulus defined between the core barrel and the thermal liner of a nuclear reactor thereby physically separating the outlet region of the core from the annular area below the horizontal baffle. The horizontal baffle prevents hot coolant that has passed through the reactor core from thermally damaging apparatus located in the annulus below the horizontal baffle by utilizing the thermally induced bowing of the horizontal baffle to enhance sealing while accommodating lateral motion of the baffle base plate.

  8. Metoptic canal, duplication of the optic canal and Warwick’s foramen in human orbits.

    PubMed

    Bertelli, Eugenio

    2014-01-01

    The region of the optic strut is sometimes traversed by some minor canals whose incidence and general characteristics have never been studied. As such canals could be the route for vessels that could interfere in the surgery of the orbital apex, we undertook a detailed anatomical study on a vast collection of dry skulls. The examination of 943 dry adult skulls and 360 foetal skulls was carried out to precise the anatomy of canals in the optic strut area, their development and relationships with the optic canal. A canal traversing the optic strut was present in 8.54 % of the orbits. Based on diameter, position within the optic strut, and thickness of the bony plate separating it from the optic canal or from the superior orbital fissure, the canals piercing the optic strut were classified into four types, which include the well-known duplication of the optic canal, different aspects of the metoptic canal and a type of canal that to our knowledge has never been reported. Warwick’s foramen was found in 0.74 % of orbits. The area of the optic strut is the frequent site of canals joining the orbit with the middle cranial fossa. Some of them can host the ophthalmic artery; others could be run by minor vessels which, however, could be the source of annoying bleedings in surgical procedures. PMID:23959928

  9. [Upper lateral incisor with 2 canals].

    PubMed

    Fabra Campos, H

    1991-01-01

    Clinical case summary of the patient with an upper lateral incisor with two root canals. The suspicion that there might be an anatomic anomaly in the root that includes a complex root canal system was made when an advanced radicular groove was detected in the lingual surface or an excessively enlarged cingulum. PMID:1659854

  10. 33 CFR 117.1045 - Hood Canal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Hood Canal. 117.1045 Section 117.1045 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Washington § 117.1045 Hood Canal. The draw of the...

  11. 33 CFR 117.1045 - Hood Canal.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Hood Canal. 117.1045 Section 117.1045 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Washington § 117.1045 Hood Canal. The draw of the...

  12. 33 CFR 117.438 - Company Canal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Company Canal. 117.438 Section 117.438 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Louisiana § 117.438 Company Canal. (a) The draw of...

  13. GENERAL VIEW OF TUMALO FEED CANAL (RIGHT) AND BEND FEED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GENERAL VIEW OF TUMALO FEED CANAL (RIGHT) AND BEND FEED CANAL (LEFT) INTERSECTION. LOOKING SOUTHEAST - Tumalo Irrigation District, Tumalo Project, West of Deschutes River, Tumalo, Deschutes County, OR

  14. Analysis of extremal lift behavior of a semicircular airfoil in a turbulent airflow at a near-zero angle of attack

    NASA Astrophysics Data System (ADS)

    Isaev, S. A.; Miau, J.-J.; Sudakov, A. G.; Usachov, A. E.

    2015-08-01

    The experimentally discovered phenomenon of lift drop for a semicircular airfoil in a turbulent airflow at a near-zero angle of attack has been numerically analyzed with multiblock computational technologies using a shear-stress-transfer model modified with allowance for the curvature of flow lines.

  15. Clinical management of infected root canal dentin.

    PubMed

    Love, R M

    1996-08-01

    Several hundred different species of bacteria are present in the human intraoral environment. Bacterial penetration of root canal dentin occurs when bacteria invade the root canal system. These bacteria may constitute a reservoir from which root canal reinfection may occur during or after endodontic treatment. The learning objective of this article is to review endodontic microbiology, update readers on the role of bacteria in pulp and periapical disease, and discuss the principles of management of infected root canal dentin. Complete debridement, removal of microorganisms and affected dentin, and chemomechanical cleansing of the root canal are suggested as being the cornerstones of successful endodontic therapy, followed by intracanal medication to remove residual bacteria, when required. PMID:9242125

  16. On two-dimensional water waves in a canal

    NASA Astrophysics Data System (ADS)

    Kozlov, Vladimir; Kuznetsov, Nikolay

    2003-07-01

    This Note deals with an eigenvalue problem that contains a spectral parameter in a boundary condition. The problem for the two-dimensional Laplace equation describes free, time-harmonic water waves in a canal having uniform cross-section and bounded from above by a horizontal free surface. It is shown that there exists a domain for which at least one of eigenfunctions has a nodal line with both ends on the free surface. Since Kuttler essentially used the non-existence of such nodal lines in his proof of simplicity of the fundamental sloshing eigenvalue in the two-dimensional case, we propose a new variational principle for demonstrating this latter fact. To cite this article: V. Kozlov, N. Kuznetsov, C. R. Mecanique 331 (2003).

  17. The study of thermal tunable coupling between a Superconducting photonic crystal waveguide and semi-circular photonic crystal

    NASA Astrophysics Data System (ADS)

    Oskooi, Somayeh; Barvestani, Jamal

    2016-08-01

    Through the present study, we investigated the light coupling between superconducting photonic crystal waveguide and a semi-circular photonic crystal. By using the finite difference time domain method, we evaluated the coupling efficiency between the mentioned structures at the various temperatures for different waveguide sizes. Calculation demonstrated that the coupling efficiency strongly depended on the temperature of the superconductor. The peak value of the coupling efficiency was influenced by the size of the nearest neighbor rods of waveguide. The results have shown that it is possible to obtain high efficiency at the desired temperature with proper selection of physical parameters in far-infrared frequency region. This structure has great potential in the optical integration and other areas.

  18. Guided implant surgery with modification of the technique involving the raising of a semicircular miniflap: A preliminary study

    PubMed Central

    Viña, José; Maestre, Laura; Peñarrocha, David; Balaguer, José

    2012-01-01

    Objective: An evaluation is made of pain, swelling and peri-implant attached mucosal width after implant-based rehabilitation involving guided surgery and a modification of the technique with the raising of a semicircular miniflap, in single and partial replacements. Study design: A case-control study was carried out. The study group consisted of 12 patients with the placement of 19 implants using a guided surgery and miniflap technique. The control group consisted of 12 patients with the placement of 22 implants using the conventional technique. Each patient scored postoperative swelling and pain by means of a visual analog scale (VAS). Attached vestibular mucosa width was evaluated 12 weeks after implant placement. Results: Twelve operations were carried out in each group. Immediate aesthetics were established for all implants of the study group. One implant failed in each group. Maximum pain was recorded after 6 hours in both groups (mean VAS score 4 and 4.9 in the study and control group, respectively). Maximum swelling was recorded after 24 hours (mean VAS score 2.5) in the study group and on the second day (mean VAS score 3.4) in the control group. The mean attached vestibular mucosa width was 2.9 mm in the study group and 3.2 mm in the control group. Conclusion: In this preliminary study, guided implant surgery with a semicircular miniflap in single and partial replacements resulted in slightly less postoperative pain and swelling than with the conventional implant technique. The attached vestibular mucosa width was greater in the control group, though the differences were very small. Key words:Guided surgery, flapless surgery, miniflap, peri-implant mucosa. PMID:22549666

  19. HORIZONTAL BOILING REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  20. Horizontally shaken impact pendulums

    NASA Astrophysics Data System (ADS)

    Alexander, T. J.; Xu, Y.; Sidhu, H.

    2016-03-01

    We consider two pendulum masses attached to the same pivot point and which interact with each other through Hertzian impacts. We show that this splitting of the mass leads to an instability in the conservative case, in which initially synchronized large amplitude motion may evolve into out-of-phase (impacting) motion. We then study in detail the response of the impacting masses in the presence of damping and driving through horizontal shaking of the pivot point. We find that synchronized modes are usually accompanied by small amplitude quasi-periodic, or even chaotic, impacts and a number of multi-period solutions may appear in the bifurcation diagram. We reveal the existence and stability of a number of impact modes and scan the frequency response of the system to a series of initial conditions to identify which modes may be more easily generated in experiment.

  1. Looking back at Love Canal

    SciTech Connect

    Deegan, J. Jr.

    1987-04-01

    The comprehensive environmental study which describes the results of a monitoring program conducted by EPA at Love Canal is evaluated by EPA's former study director. Attention is focused on the episode's history and the agency's study methods. The aim of the program was to constitute a study team, design a monitoring study, reprogram and reallocate the financial resources needed to conduct the study, and identify and employ contractors who would collect and analyze environmental samples. The agency was directed to ensure the quality of the data acquired from various environmental media and analyzed by numerous laboratories; to integrate, interpret, and report the data; and to assess, from an environmental perspective, the habitability of the area.

  2. Panama Canal Watershed Experiment- Agua Salud Project

    USGS Publications Warehouse

    Stallard, Robert F.; Ogden, Fred L.; Elsenbeer, Helmut; Hall, Jefferson S.

    2010-01-01

    The Agua Salud Project utilizes the Panama Canal’s (Canal) central role in world commerce to focus global attention on the ecosystem services provided by tropical forests. The Canal was one of the great engineering projects in the world. Completed in 1914, after almost a decade of concerted effort, its 80 km length greatly shortened the voyage between the Atlantic and Pacific Oceans. An entire class of ships, the Panamax, has been constructed to maximize the amount of cargo that can be carried in a Canal passage. In today’s parlance, the Canal is a “green” operation, powered largely by water (Table 1). The locks, three pairs on each end with a net lift of 27 meters, are gravity fed. For each ton of cargo that is transferred from ocean to ocean, about 13 tons of water (m3) are used. Lake Gatún forms much of the waterway in the Canal transect. Hydroelectricity is generated at the Gatún dam, whenever there is surplus water, and at Madden Dam (completed in 1936) when water is transferred from Lake Alhajuela to Lake Gatún. The Canal watershed is the source of drinking water for Panama City and Colon City, at either end of the Canal, and numerous towns in between.

  3. How to bond to root canal dentin

    NASA Astrophysics Data System (ADS)

    Nica, Luminita; Todea, Carmen; Furtos, Gabriel; Baldea, Bogdan

    2014-01-01

    Bonding to root canal dentin may be difficult due to various factors: the structural characteristic of the root canal dentin, which is different from that of the coronal dentin; the presence of the organic tissue of the dental pulp inside the root canal, which has to be removed during the cleaning-shaping of the root canal system; the smear-layer resulted after mechanical instrumentation, which may interfere with the adhesion of the filling materials; the type of the irrigants used in the cleaning protocol; the type of the sealer and core material used in the obturation of the endodontic space; the type of the materials used for the restoration of the endodontically treated teeth. The influence of the cleaning protocol, of the root canal filling material, of the type of the adhesive system used in the restoration of the treated teeth and of the region of the root canal, on the adhesion of several filling and restorative materials to root canal dentin was evaluated in the push-out bond strength test on 1-mm thick slices of endodontically treated human teeth. The results showed that all these factors have a statistically significant influence on the push-out bond strength. Formation of resin tags between radicular dentin and the investigated materials was observed in some of the samples at SEM analysis.

  4. Horizontal drilling in shallow reservoirs

    SciTech Connect

    Murray, W.F. Jr.; Schrider, L.A.; McCallister, J.V.; Mazza, R.L.

    1993-12-31

    Belden & Blake and the US DOE will cofund a horizontal well to be drilled in the Clinton Sandstone as part of the DOE`s multi well program titled ``Horizontal Drilling in Shallow Geologic Complex Reservoirs.`` This well will be located in Mahoning County, Ohio in an area which has demonstrated above average Clinton gas production. To the best of our knowledge, this will be the first horizontal well drilled to the Clinton Sand formation in Ohio. Since many of the remaining Clinton Sand drilling sites are of poorer reservoir quality, they may not be developed unless technology such as horizontal drilling can be successfully demonstrated.

  5. Maxillary First Molar with Two Root Canals

    PubMed Central

    Rahimi, Saeed; Ghasemi, Negin

    2013-01-01

    Knowledge regarding the anatomic morphology of maxillary molars is absolutely essential for the success of endodontic treatment. The morphology of the permanent maxillary first molar has been reviewed extensively; however, the presence of two canals in a two-rooted maxillary first molar has rarely been reported in studies describing tooth and root canal anatomies. This case report presents a patient with a maxillary first molar with two roots and two root canals, who was referred to the Department of Endodontics, Tabriz University of Medical Sciences, Iran. PMID:23862051

  6. 6. VIEW SHOWING WOODEN FLUMES ACROSS MARICOPA CANAL. SUCH FLUMES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. VIEW SHOWING WOODEN FLUMES ACROSS MARICOPA CANAL. SUCH FLUMES WERE USED TO CARRY WATER FROM ONE CANAL TO ANOTHER, BEFORE THE CANAL COMPANIES WERE BOUGHT BY THE GOVERNMENT, AND THE SYSTEM UNIFIED. Photographer unknown, no date - Grand Canal, North side of Salt River, Tempe, Maricopa County, AZ

  7. 158. Photocopy of transit book (taken from Twin Falls Canal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    158. Photocopy of transit book (taken from Twin Falls Canal Company Transit Book #404T, Page 3, #46, Division One). START OF MAIN CANAL SURVEY, TWIN FALLS COUNTY, MILNER, IDAHO. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

  8. 154. Photocopy of transit book (taken from Twin Falls Canal ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    154. Photocopy of transit book (taken from Twin Falls Canal Company Surveyor's Transit Book #405T, Page 2, #46 Division One). STATEMENT OF SIGHT-SETTING FOR 1903 SURVEY TO ALIGN SOUTH SIDE CANAL, TWIN FALLS COUNTY, MILNER, IDAHO. - Milner Dam & Main Canal: Twin Falls Canal Company, On Snake River, 11 miles West of city of Burley, Idaho, Twin Falls, Twin Falls County, ID

  9. 103. CANAL AT THE ENTRANCE TO THE POMPTON FEEDER NEAR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    103. CANAL AT THE ENTRANCE TO THE POMPTON FEEDER NEAR MOUNTAIN VIEW, NEW JERSEY. THE POMPTON FEEDER BOATS TO TRAVEL NORTH 4.26 MILES TO TO POMPTON AS WELL AS PROVIDING THE MAIN CANAL WITH WATER FROM GREENWOOD LAKE. A MODIFIED QUEEN POST TRUSS BRIDGE SPANS THE CANAL IN THE FOREGROUND. - Morris Canal, Phillipsburg, Warren County, NJ

  10. Seepage investigations of Noyes Canal, Menard County, Texas

    USGS Publications Warehouse

    Yost, Ivan Dale

    1953-01-01

    At the request of the U.S. Department of Agriculture, Soil Conservation Service, and the Menard Irrigation Company, a seepage investigation was made on Noyes Canal (Menard Irrigation Company Canal) in Menard County, Texas, from the headgates of the canal to where the canal empties back into the San Saba River.