Horizontal Axis Of Rotation Research Articles

Eye movements induced by gravitational force and by angular acceleration: their relationship.

The relationship between putative 'canal' and 'otolith' function was studied by using both vertical axis and horizontal axis (barbecue spit) rotations. The vestibulo-ocular reflex (VOR) with eyes closed of 7 normal subjects during vertical axis rotation was characterized (0.02 to 1.67 Hz) using pseudorandom acceleration. Gain and phase points were calculated. The long time constant of the VOR was then estimated from the phase points using a simple linear systems model. The same subjects were also tested with eyes closed using earth horizontal axis rotations. Constant velocity rotation (60 degrees/sec) produced a periodic oscillation in the slope of the slow component of nystagmus known as the 'modulation component'. The amplitude of this component was averaged for clockwise and counterclockwise runs. For the 7 subjects, the amplitude of averaged modulation component correlated with the low-frequency phase values (r = 0.82 to 0.89) and VOR long time constant estimates (r = -0.95) obtained during vertical axis rotations. These data suggest a complementary relationship between responses to linear and to angular accelerations. Subjects having eye movement responses which are less sensitive to low-frequency angular acceleration also tend to have relatively greater responses to changing linear accelerations.

Comparison of retruded axis articular mountings with and without applied muscular force

The study reported compared the positions of the horizontal axis of rotation of the condyles when R.A.P. registrations were taken on seven subjects using; (1) An anterior jig with chinpoint guidance. (2) An anterior jig with chinpoint guidance and applied muscle force by the subject. (3) An anterior jig with bilateral manipulation (i.e. bilateral support of the body of the mandible by the operator). The results showed that the most superior positions were obtained with the technique using the anterior jig with chinpoint guidance and applied muscle force, which was also the most inconsistent technique. The technique using the anterior jig with chinpoint guidance was most consistent, and the mean difference between retruded axis position and intercuspal position using this technique was 0.31 mm on the right side and 0.34 mm on the left side.

Vibration measurements of the perch saccular otolith

1. The vertical movement of different parts of the perch saccular otolith was measured with a laser vibrometer during horizontal vibration of the fish back and forth along its long axis. Data were obtained at four different frequencies within the audible range of the fish. Vibration at these frequencies caused very little vertical movement of the skull. 2. No vertical oscillations of the otolith were detected at 20 Hz, whereas both ends of the otolith showed vertical vibrations at 40, 90 and 220 Hz. An area of minimum vertical movement appeared around the midpoint of the otolith at these frequencies, thus indicating the existence of a horizontal axis of rotation. 3. It is argued that the stimulation technique is a reasonable approximation to underwater sound exposure. The measurements thus support the idea of a coarse, peripheral frequency analysis in fish based on a frequency dependent pattern of sound induced otolith movements.

A design of a new restitution instrument

A design is described regarding a new restitution instrument. Characteristics of the instrument are as following :(1) non-tilting projectors of the instrument, (2) fixed optical system, (3) minimum elements of relative orientation: two swing, oneX-tilt of left projector, oneY-tilt of right projector andZ-motion.Chosen the elements of orientation as (3), only one tilt about one axis for one projector is sufficient for the relative orientation, which simplify the mechanism of the instrument.To accomplih (1), the instrument is constructed as illustrated in Fig. 3 by means of the stereo-gram. In this figure, ABis a horizontal rotation axis about which a device ABCDEF is rotated. Two guid railsEF, CDare fixed to the device so that the carriagePQTUbe able to move along the rails. The carriage is moved by the guid rodGRwhich is through a sleeved pivotRfixed to the middle of the carriage. A short spindleTUattached also to the carriage, the endSof the guid rodSAmove along the spindle, another end of the rodSAis through the sleeved pivotHfixed to the negative carrier by a gimbal system.The movementS, or the tilt of the rodSAregarding to the rodRG, corresponds to a tilt of the projector. The verification is shown in Fig. 5 and formula (1) - (6) .

A solar cooker for developing countries

A durable solar cooker designed specifically with a view to fabrication in centralized workshops in developing countries is described. The mirror system comprises twelve identical 29.3-cm diameter concave glass mirrors mounted in a frame in a two-axis azimuthal mounting. By using an asymmetrical mirror system and positioning the horizontal axis of rotation at the center of curvature of the image field, all reflected radiation falls on the bottom—and not on the sides—of the cooking pot. Over 500 watts are delivered in bright sunlight. Except for the mirrors, the construction is entirely of iron and the total material cost (including mirrors) is under $8.

ORIENTATION OF THE ROTATION-AXIS RELATIVE TO GRAVITY: ITS INFLUENCE ON NYSTAGMUS AND THE SENSATION OF ROTATION.

Subjective phenomena and nystagmus were compared under two conditions of rotation, one in which the axis of rotation was vertical, i.e., aligned with gravity, and one in which the rotation-axis was horizontal. When the axis of rotation was horizontal, normal subjects exhibited nystagmus and sensations of rotation for periods of three minutes (and longer); deceleration produced very brief post-rotational reactions. L-D subjects, men presumed to be without vestibular function, did not exhibit nystagmus or report sensations similar to those of normal subjects for either the vertical or horizontal axis of rotation. Because prolonged nystagmus occurred almost exclusively in normal subjects when the rotation axis was horizontal, it is concluded that vestibular function is a necessary condition for this response and that it may be dependent upon the continuous reorientation of the otolith system relative to gravity. The results emphasize the importance of increasing our range of experimental observations to check the accuracy of theoretical predictions.

Lord Kelvin's Work on Gyrostatics 8

V.—Gyrostatic Theory of Elasticity.Note.—In the explanation of steady precession, near the foot of the first column of p. 715 of NATURE of February 25, the words, “the horizontal axis A of the couple,” referred to a cut, which, owing to an accident, could not be given. But Fig. 6 there printed, and repeated here on page 21. will serve instead. In that, as indicated in the small diagram at the bottom of the figure, the axis of angular momentum-the spia-axis-is to be supposed drawn towards the right, from the centre of the gyrostat along the (horizontal) axis of rotation, and the axis of the couple horizontally from the centre towards the observer. The dotted arc, marked 90°, should be continued round to the axis marked mkw. The angle 90° is that between the spin-axis and the couple-axis.—A.G.