Paleomagnetic Results from the Perijá Mountains, VenezuelaAn Example of Vertical Axis Rotation

2003 ◽  
Author(s):  
Wulf A. Gose ◽  
Adrián Perarnau ◽  
Jesús Castillo
Keyword(s):  
Vertical Axis ◽  
Axis Rotation

Zircon geochronology and paleomagnetism of an Archean harzburgite intrusion, eastern Bighorn Mountains, Wyoming

2020 ◽  
Vol 57 (1) ◽  
pp. 21-40
Author(s):  
Alexandra Wallenberg ◽  
Michelle Dafov ◽  
David Malone ◽  
John Craddock
Keyword(s):  
Hanging Wall ◽  
Vertical Axis ◽  
Shear Zones ◽  
Strike Slip ◽  
Zircon Geochronology ◽  
Weighted Mean ◽  
Mafic Complex ◽  
Laramide Orogeny ◽  
Axis Rotation ◽  
Bighorn Mountains

A harzburgite intrusion, which is part of the trailside mafic complex) intrudes ~2900-2950 Ma gneisses in the hanging wall of the Laramide Bighorn uplift west of Buffalo, Wyoming. The harzburgite is composed of pristine orthopyroxene (bronzite), clinopyroxene, serpentine after olivine and accessory magnetite-serpentinite seams, and strike-slip striated shear zones. The harzburgite is crosscut by a hydrothermally altered wehrlite dike (N20°E, 90°, 1 meter wide) with no zircons recovered. Zircons from the harzburgite reveal two ages: 1) a younger set that has a concordia upper intercept age of 2908±6 Ma and a weighted mean age of 2909.5±6.1 Ma; and 2) an older set that has a concordia upper intercept age of 2934.1±8.9 Ma and a weighted mean age 2940.5±5.8 Ma. Anisotropy of magnetic susceptibility (AMS) was used as a proxy for magmatic intrusion and the harzburgite preserves a sub-horizontal Kmax fabric (n=18) suggesting lateral intrusion. Alternating Field (AF) demagnetization for the harzburgite yielded a paleopole of 177.7 longitude, -14.4 latitude. The AF paleopole for the wehrlite dike has a vertical (90°) inclination suggesting intrusion at high latitude. The wehrlite dike preserves a Kmax fabric (n=19) that plots along the great circle of the dike and is difficult to interpret. The harzburgite has a two-component magnetization preserved that indicates a younger Cretaceous chemical overprint that may indicate a 90° clockwise vertical axis rotation of the Clear Creek thrust hanging wall, a range-bounding east-directed thrust fault that accommodated uplift of Bighorn Mountains during the Eocene Laramide Orogeny.

Three-Dimensional Computation during Off-Vertical Axis Rotation (OVAR) in Monkeys

2006 ◽  
Vol 65 (6) ◽  
pp. 429-439 ◽  
Author(s):  
Keisuke Kushiro ◽  
Jun Maruta
Keyword(s):  
Three Dimensional ◽  
Vertical Axis ◽  
Axis Rotation

Modeling 3-D Slow Phase Velocity Estimation During Off-Vertical-Axis Rotation (OVAR)

1992 ◽  
Vol 2 (1) ◽  
pp. 1-14
Author(s):  
Charles Schnabolk ◽  
Theodore Raphan
Keyword(s):  
Polarization Vector ◽  
Vertical Axis ◽  
Cross Product ◽  
Interesting Property ◽  
Velocity Estimation ◽  
Three Dimensions ◽  
Slow Phase ◽  
Head Orientation ◽  
Head Velocity ◽  
Axis Rotation

Off-vertical-axis rotation (OVAR) in darkness generates continuous compensatory eye velocity. No model has yet been presented that defines the signal processing necessary to estimate head velocity in three dimensions for arbitrary rotations during OVAR. The present study develops a model capable of estimating all 3 components of head velocity in space accurately. It shows that processing of two patterns of otolith activation, one delayed with respect to the other, for each plane of eye movement is not sufficient. (A pattern in this context is an array of signals emanating from the otoliths. Each component of the array is a signal corresponding to a class of otolith hair cells with a given polarization vector as described by Tou and Gonzalez in 1974.) The key result is that estimation of head velocity in space can be achieved by processing three temporally displaced patterns, each representing a sampling of gravity as the head rotates. A vector cross product of differences between pairs of the sampled gravity vectors implements the estimation. An interesting property of this model is that the component of velocity about the axis of rotation reduces to that derived previously using the pattern estimator model described by Raphan and Schnabolk in 1988 and Fanelli et al in 1990. This study suggests that the central nervous system (CNS) maintains a current as well as 2 delayed representations of gravity at every head orientation during rotation. It also suggests that computing vector cross products and implementing delays may be fundamental operations in the CNS for generating orientation information associated with motion.

Vestibulo-ocular function in anxiety disorders

2007 ◽  
Vol 16 (4-5) ◽  
pp. 209-215
Author(s):  
Joseph M. Furman ◽  
Mark S. Redfern ◽  
Rolf G. Jacob
Keyword(s):  
Panic Disorder ◽  
Anxiety Disorders ◽  
Semicircular Canal ◽  
Constant Velocity ◽  
Vertical Axis ◽  
Velocity Storage ◽  
Movement Response ◽  
Ocular Reflex ◽  
Axis Rotation ◽  
High Degree

Previous studies of vestibulo-ocular function in patients with anxiety disorders have suggested a higher prevalence of peripheral vestibular dysfunction compared to control populations, especially in panic disorder with agoraphobia. Also, our recent companion studies have indicated abnormalities in postural control in patients with anxiety disorders who report a high degree of space and motion discomfort. The aim of the present study was to assess the VOR, including the semicircular canal-ocular reflex, the otolith-ocular reflex, and semicircular canal-otolith interaction, in a well-defined group of patients with anxiety disorders. The study included 72 patients with anxiety disorders (age 30.6 +/− 10.6 yrs; 60 (83.3% F) and 29 psychiatrically normal controls (age 35.0 +/minus; 11.6 yrs; 24 (82.8% F). 25 patients had panic disorder; 47 patients had non-panic anxiety. Patients were further categorized based on the presence (45 of 72) or absence (27 of 72) of height phobia and the presence (27 of 72) or absence (45 of 72) of excessive space and motion discomfort (SMD). Sinusoidal and constant velocity earth-vertical axis rotation (EVAR) was used to assess the semicircular canal-ocular reflex. Constant velocity off-vertical axis rotation (OVAR) was used to assess both the otolith-ocular reflex and static semicircular canal-otolith interaction. Sinusoidal OVAR was used to assess dynamic semicircular canal-otolith interaction. The eye movement response to rotation was measured using bitemporal electro-oculography. Results showed a significantly higher VOR gain and a significantly shorter VOR time constant in anxiety patients. The effect of anxiety on VOR gain was significantly greater in patients without SMD as compared to those with SMD. Anxiety patients without height phobia had a larger OVAR modulation. We postulate that in patients with anxiety, there is increased vestibular sensitivity and impaired velocity storage. Excessive SMD and height phobia seem to have a mitigating effect on abnormal vestibular sensitivity, possibly via a down-weighting of central vestibular pathways.

Verticality Perception During Off-Vertical Axis Rotation

2007 ◽  
Vol 97 (5) ◽  
pp. 3256-3268 ◽  
Author(s):  
R.A.A. Vingerhoets ◽  
J.A.M. Van Gisbergen ◽  
W. P. Medendorp
Keyword(s):  
Time Course ◽  
Rotation Speed ◽  
Interaction Model ◽  
Vertical Axis ◽  
Subsequent Increase ◽  
Dynamic Component ◽  
Visual Vertical ◽  
Axis Rotation ◽  
Highly Correlated ◽  
Perceptual Changes

During prolonged rotation about a tilted yaw axis, often referred to as off-vertical axis rotation (OVAR), a percept of being translated along a conical path slowly emerges as the sense of rotation subsides. Recently, we found that these perceptual changes are consistent with a canal–otolith interaction model that attributes the illusory translation percept to improper interpretation of the ambiguous otolith signals. The model further predicts that the illusory translation percept must be accompanied by slowly worsening tilt underestimates. Here, we tested this prediction in six subjects by measuring the time course of the subjective visual vertical (SVV) during OVAR stimulation at three different tilt-rotation speed combinations, in complete darkness. Throughout the 2-min run, at each left-ear-down and right-ear-down position, the subject indicated whether a briefly flashed line deviated clockwise or counterclockwise from vertical to determine the SVV with an adaptive staircase procedure. Typically, SVV errors indicating tilt underestimation were already present at rotation onset and then increased exponentially to an asymptotic value, reached at about 60 s after rotation onset. The initial error in the SVV was highly correlated to the response error in a static tilt control experiment. The subsequent increase in error depended on both rotation speed and OVAR tilt angle, in a manner predicted by the canal–otolith interaction model. We conclude that verticality misjudgments during OVAR reflect a dynamic component linked to canal–otolith interaction, superimposed on a tilt-related component that is also expressed under stationary conditions.

scholarly journals Effects of visual stimulation using a flat screen under off-vertical axis rotation conditions on the semicircular ocular reflex and otolith-ocular reflex

2020 ◽  
Vol 79 (3) ◽  
pp. 164-170
Author(s):  
Fumihiro Mochizuki ◽  
Yasuhiro Miyamoto ◽  
Yoshiyuki Sasano ◽  
Kotaro Arai ◽  
Hiroshi Nishimoto ◽  
...  
Keyword(s):  
Visual Stimulation ◽  
Vertical Axis ◽  
Ocular Reflex ◽  
Flat Screen ◽  
Axis Rotation

Eye Movements and Motion Perception Induced by Off-vertical Axis Rotation (OVAR) at Small Angles of Tilt after Spaceflight

1995 ◽  
Vol 115 (5) ◽  
pp. 603-609 ◽  
Author(s):  
Gilles Clement ◽  
Christian Darlot ◽  
Anna Petropoulos ◽  
Alain Berthoz
Keyword(s):  
Eye Movements ◽  
Motion Perception ◽  
Vertical Axis ◽  
Axis Rotation

scholarly journals Vertical axis rotation (or lack thereof) of the eastern Mongolian Altay Mountains: Implications for far-field transpressional mountain building

2018 ◽  
Vol 736 ◽  
pp. 31-46 ◽  
Author(s):  
Laura C. Gregory ◽  
Conall Mac Niocaill ◽  
Richard T. Walker ◽  
Gantulga Bayasgalan ◽  
Tim J. Craig
Keyword(s):  
Vertical Axis ◽  
Far Field ◽  
Mountain Building ◽  
Altay Mountains ◽  
Axis Rotation
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