scholarly journals Evaluation of the panoramic image formation in different anatomic positions

2010 ◽  
Vol 21 (5) ◽  
pp. 458-462 ◽  
Author(s):  
Daniela Brait Silva Ladeira ◽  
Adriana Dibo da Cruz ◽  
Solange Maria de Almeida ◽  
Frab Norberto Bóscolo
Keyword(s):  
Horizontal Plane ◽  
Image Formation ◽  
Vertical Axis ◽  
Image Size ◽  
Radiographic Image ◽  
Middle Portion ◽  
Image Layer ◽  
Acrylic Plate ◽  
Recorded Data ◽  
Digital Caliper

The aim of this study was to determine size, shape and position of the image layer by evaluation of the radiographic image formation in different anatomic positions. A customized phantom was made of a rectangular acrylic plate measuring 14 cm² and 0.3 cm thick, with holes spaced 0.5 cm away and arranged in rows and columns. Each column was separately filled with 0.315 cm diameter metal spheres to acquire panoramic radiographs using the Orthopantomograph OP 100 unit. The customized phantom was placed on the mental support of the device, with its top surface kept parallel to the horizontal plane, and was radiographed at three different heights from the horizontal plane, i.e., the orbital, occlusal and mandibular symphysis levels. The images of the spheres were measured using a digital caliper to locate the image layer. The recorded data were analyzed statistically by the Student'-t test, ANOVA and Tukey' test (?=0.05). When the image size of spheres in horizontal and vertical axes were compared, statistically significant differences (p<0.05) were observed in all areas, portions of the image layer and heights of horizontal plane evaluated. In the middle portion of the image layer, differences in the image size of spheres were observed only along the horizontal axis (p<0.05), whereas no differences were observed along the vertical axis (p>0.05). The methodology used in this determined the precise size, shape and position of the image layer and differences in magnification were observed in both the horizontal and vertical axes.

Sensorimotor aspects of high-speed artificial gravity: II. The effect of head position on illusory self motion

2003 ◽  
Vol 12 (5-6) ◽  
pp. 283-289
Author(s):  
Fred W. Mast ◽  
Nathaniel J. Newby ◽  
Laurence R. Young
Keyword(s):  
Healthy Subjects ◽  
Horizontal Plane ◽  
High Speed ◽  
Semicircular Canals ◽  
Vertical Axis ◽  
Head Position ◽  
Artificial Gravity ◽  
Axis Of Rotation ◽  
Self Motion

The effects of cross-coupled stimuli on the semicircular canals are shown to be influenced by the position of the subject's head with respect to gravity and the axis of rotation, but not by the subject's head position relative to the trunk. Seventeen healthy subjects made head yaw movements out of the horizontal plane while lying on a horizontal platform (MIT short radius centrifuge) rotating at 23 rpm about an earth-vertical axis. The subjects reported the magnitude and duration of the illusory pitch or roll sensations elicited by the cross-coupled rotational stimuli acting on the semicircular canals. The results suggest an influence of head position relative to gravity. The magnitude estimation is higher and the sensation decays more slowly when the head's final position is toward nose-up (gravity in the subject's head x-z-plane) compared to when the head is turned toward the side (gravity in the subject's head y-z-plane). The results are discussed with respect to artificial gravity in space and the possible role of pre-adaptation to cross-coupled angular accelerations on earth.

Spatial organization of visual messages of the rabbit's cerebellar flocculus. II. Complex and simple spike responses of Purkinje cells

1988 ◽  
Vol 60 (6) ◽  
pp. 2091-2121 ◽  
Author(s):  
W. Graf ◽  
J. I. Simpson ◽  
C. S. Leonard
Keyword(s):  
Purkinje Cells ◽  
Horizontal Plane ◽  
Rotation Axis ◽  
Modulation Depth ◽  
Vertical Axis ◽  
Axis Orientation ◽  
Complex Spike ◽  
Full Field ◽  
Simple Spike ◽  
Dominant Eye

1. Complex and simple spike responses of Purkinje cells were recorded in the flocculus of anesthetized, paralyzed rabbits during rotating full-field visual stimuli produced by a three-axis planetarium projector. 2. On the basis of the spatial properties of their complex spike responses, floccular Purkinje cells could be placed into three distinct classes called Vertical Axis, Anterior (45 degrees) Axis and Posterior (135 degrees) Axis. The first two classes occurred in both monocular and binocular forms; the third class was encountered only in binocular form. For the binocular response forms, stimulation through one eye, called the dominant eye, elicited a stronger modulation of the complex spike firing rate than did stimulation of the other eye. The approximate orientation of that axis about which full-field rotation elicited the deepest modulation (the preferred axis) when presented to the dominant eye served as the class label. These classes are the same as those determined qualitatively for inferior olive neurons in the previous paper (47). The present study provides a quantitative description of their spatial tuning. 3. For Vertical Axis cells, the dominant eye was ipsilateral with respect to the flocculus recording site. The preferred axis was vertical and null (no-response) axes were in the horizontal plane. For the binocular response form of Vertical Axis cells (less than 10% of this class), the direction preferences for the two eyes were synergistic with respect to rotation about the vertical axis. 4. The dominant eye for the Anterior (45 degrees) Axis cells was contralateral, with the preferred axis oriented in the horizontal plane at approximately 45 degrees contralateral azimuth. The modulation depth showed a close to cosine relation with the angle between the preferred axis and the stimulus rotation axis. The average orientation (n = 10) for the dominant eye preferred axis, determined by the best-fit sinusoid, was 47 degrees contralateral azimuth. The preferred axis orientation for the ipsilateral (nondominant) eye in the binocular response forms was between 45 and 90 degrees azimuth in the horizontal plane. A null axis for each eye was at approximately 90 degrees to the preferred axis. 5. The Posterior (135 degrees) Axis cells were encountered only in binocular response forms. The dominant eye was ipsilateral, with the preferred axis oriented at approximately 135 degrees ipsilateral azimuth close to the horizontal plane. The modulation depth showed a close to cosine relation with the angle between the preferred axis and the stimulus rotation axis.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Design and Prototyping of a Partially Decoupled 4-DOF 3T1R Parallel Manipulator With High-Load Carrying Capacity

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Sébastien Briot ◽  
Vigen Arakelian ◽  
Sylvain Guégan
Keyword(s):  
Carrying Capacity ◽  
Horizontal Plane ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Experimental Validation ◽  
Vertical Axis ◽  
High Load ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Fixed Orientation

In this paper, a new four degrees of freedom 3T1R parallel manipulator with high-load carrying capacity is presented. This manipulator generates Schönflies motions, in which the moving platform carries out three independent translations and one rotation about one axis of fixed orientation. The particularity of the proposed architecture is the decoupling of the displacements of the platform in the horizontal plane from the platform’s translation along the vertical axis. Such a decoupling allows the cancellation of the gravity loads on the actuators, which displace the platform in the horizontal plane. A prototype of the proposed manipulator with four degrees of freedom and an experimental validation of the suggested concept are also presented. Two cases have been examined on the built prototype: a manipulator with payload and one without. It was shown that the input torques of actuators displacing the platform in the horizontal plane for these two cases are the same; i.e., the payload does not bring any load to the actuators.

Secondary Surveillance Radar and Airborne Transponder System

1961 ◽  
Vol 65 (606) ◽  
pp. 407-411
Author(s):  
G. G. Roberts
Keyword(s):  
Traffic Control ◽  
Horizontal Plane ◽  
Vertical Plane ◽  
Beam Width ◽  
Vertical Axis ◽  
High Coverage ◽  
Beam Shape ◽  
Height Range ◽  
Cathode Ray Tube ◽  
Position Indicator

The use of primary pulsed radar as a surveillance instrument in Air Traffic Control is familiar to most, and is a direct development of the various ground radars current in the last war. The wavelengths generally employed are 10 cms. for more local control, and 50 cms. for long range and high coverage. The primary radar depends for its information on reflection from the target aircraft of sequences of pulses of electromagnetic energy radiated by the aerial, and displays this information as a “paint” on a P.P.I. (Plan-Position Indicator) cathode ray tube giving range and bearing relative to the radar site. The radar beam is fan-shaped, narrow in the horizontal plane to a few degrees, and wide in the vertical plane to provide adequate vertical cover. The beam is made to scan through the target by a rotation of the aerial about a vertical axis up to a rate of 14 r.p.m. The beam width in the horizontal plane is necessarily kept narrow to provide adequate discrimination between targets at the same range but different bearings. The primary radar is frequently associated with a height-finding radar in which the beam shape is reversed, having a narrow angular cross section in the vertical plane. In this case the aerial is made to nod up and down along an appropriate azimuth selected by the controller, and the height of an aircraft is displayed on a height-range cathode ray tube.

scholarly journals Targetting and optomotor space in the leaf-hopper Empoasca vitis (Gothe) (Hemiptera: Cicadellidae)

1996 ◽  
Vol 199 (3) ◽  
pp. 731-740 ◽  
Author(s):  
J Brackenbury
Keyword(s):  
Vertical Axis ◽  
Spatial Integration ◽  
Image Size ◽  
Axial Resolution ◽  
Empoasca Vitis ◽  
Image Area ◽  
Intermediate Image ◽  
Vertical Bars ◽  
Jump Trajectory ◽  
Angular Coordinates

The accuracy with which the visuomotor system of Empoasca vitis can prescribe a jump trajectory towards a bright, uniformly illuminated target shape was investigated. The targets consisted of discs, rings or bars cut out of black card and mounted in front of a source of stroboscopic light diffused through translucent paper. The targets varied in size, subtending angles of 7-110 &deg; to the insect's eye. Target resolution was measured independently along the horizontal and vertical axes and was defined in terms of the standard deviation of the horizontal (s.d.x) or vertical (s.d.y) angular coordinates of the take-off paths measured with respect to the geometric centre of the target. In all cases involving single connected images, the point towards which jumping was directed coincided with the geometric centre of the image area (the light centroid). This meant, for example, that the insects specifically targetted the dark core of a ring of light. No formal features of the target shapes, such as light-dark boundaries, were targetted. Vertical axial resolution was independent of image size (mean s.d.y for all image sizes 6.9 &deg;), but horizontal axial resolution only achieved this minimal value at intermediate image sizes (approximately 30-60 &deg;). When two separate but identical target shapes (vertical bars) were presented at different horizontal separations, the dark area between them was accurately targetted up to target separations of approximately 30-50 &deg;. At greater separations, there was an increasing tendency to target one or other of the two shapes. From these experiments it is concluded that, in the frontal visual field, spatial integration can be performed to an accuracy (as defined in these experiments) of 7 &deg;x7 &deg;. Performance deteriorates outside an optimal range of image sizes, and this is faithfully reflected in the decline in horizontal axial resolution when jumping. However, this decline in visual performance is not reflected in target resolution along the vertical axis because it is masked by a biomechanical constraint, i.e. the inability of the legs to set take-off angles outside a narrow range of 30-60 &deg; to the horizontal.

Eye Movements of the Crab Leptograpsus Variegatus Elicited by Imposed Leg Movements

1982 ◽  
Vol 98 (1) ◽  
pp. 151-173
Author(s):  
D. VARJÜ ◽  
D.C. SANDEMAN
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Frequency Response ◽  
Functional Significance ◽  
Horizontal Plane ◽  
Vertical Axis ◽  
Horizontal Component ◽  
Eye Rotation ◽  
Freely Moving ◽  
Leg Movements

1. The horizontal component of eyestalk movements elicited by moving the legs of blinded crabs is described. 2. The animals' bodies were fixed to a stand and the legs were supported on either a sphere or platform and subjected to movement around the three major axes (yaw, pitch, and roll). Both sinusoidal and stepped movements of the legs were studied. 3. The effect of moving the legs on one side only, homolateral or contralateral to the eyestalk was also studied. 4. The eyestalk excursion elicited by sinusoidal leg excursion around the vertical axis (yaw) is a nearly linear function of the leg excursions over the range of 1–40° peak to peak at 0.1 Hz. The amplification of the system is about 0.4 when the animal's legs are supported on a ball, and 0.8-1.0 when the legs are supported on a platform. 5. The frequency response of the system to yaw is nearly flat for eye excursions of 16° peak to peak, over the range of 0.005-0.1 Hz. 6. The visual system has a powerful braking effect on the eye rotation, when this is generated by the imposed leg movements. 7. Eyestalk responses to yaw can be interpreted to be compensatory in that they stabilize the eyes in space in freely moving animals. 8. Eyestalk movements to pitch and roll are complex. In roll, their horizontal component indicates the presence of considerable rectification in the leg proprioceptor-eye system. 9. The functional significance of the eyestalk movements in the horizontal plane is discussed. Note:

scholarly journals Three-dimensional tuning of head direction cells in rats

2019 ◽  
Vol 121 (1) ◽  
pp. 4-37 ◽  
Author(s):  
Michael E. Shinder ◽  
Jeffrey S. Taube
Keyword(s):  
Horizontal Plane ◽  
Reference Frames ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Ventral Surface ◽  
Three Dimensions ◽  
Head Direction ◽  
Horizontal Canal ◽  
Cell Responses ◽  
The Earth

Head direction (HD) cells fire when the animal faces that cell’s preferred firing direction (PFD) in the horizontal plane. The PFD response when the animal is oriented outside the earth-horizontal plane could result from cells representing direction in the plane of locomotion or as a three-dimensional (3D), global-referenced direction anchored to gravity. To investigate these possibilities, anterodorsal thalamic HD cells were recorded from restrained rats while they were passively positioned in various 3D orientations. Cell responses were unaffected by pitch or roll up to ~90° from the horizontal plane. Firing was disrupted once the animal was oriented >90° away from the horizontal plane and during inversion. When rolling the animal around the earth-vertical axis, cells were active when the animal’s ventral surface faced the cell’s PFD. However, with the rat rolled 90° in an ear-down orientation, pitching the rat and rotating it around the vertical axis did not produce directionally tuned responses. Complex movements involving combinations of yaw-roll, but usually not yaw-pitch, resulted in reduced directional tuning even at the final upright orientation when the rat had full visual view of its environment and was pointing in the cell’s PFD. Directional firing was restored when the rat’s head was moved back-and-forth. There was limited evidence indicating that cells contained conjunctive firing with pitch or roll positions. These findings suggest that the brain’s representation of directional heading is derived primarily from horizontal canal information and that the HD signal is a 3D gravity-referenced signal anchored to a direction in the horizontal plane. NEW & NOTEWORTHY This study monitored head direction cell responses from rats in three dimensions using a series of manipulations that involved yaw, pitch, roll, or a combination of these rotations. Results showed that head direction responses are consistent with the use of two reference frames simultaneously: one defined by the surrounding environment using primarily visual landmarks and a second defined by the earth’s gravity vector.

Responses of Neurons in the Nucleus of the Basal Optic Root to Translational and Rotational Flowfields

1999 ◽  
Vol 81 (1) ◽  
pp. 267-276 ◽  
Author(s):  
Douglas R. W. Wylie ◽  
Barrie J. Frost
Keyword(s):  
Optic Flow ◽  
Horizontal Plane ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Mesencephalic Reticular Formation ◽  
Companion Paper ◽  
Direction Selectivity ◽  
Large Field ◽  
Adjacent Area

Wylie, Douglas R. W. and Barrie J. Frost. Responses of Neurons in the nucleus of the basal optic root to translational and rotational flowfields. J. Neurophysiol. 81: 267–276, 1999. The nucleus of the basal optic root (nBOR) receives direct input from the contralateral retina and is the first step in a pathway dedicated to the analysis of optic flowfields resulting from self-motion. Previous studies have shown that most nBOR neurons exhibit direction selectivity in response to large-field stimuli moving in the contralateral hemifield, but a subpopulation of nBOR neurons has binocular receptive fields. In this study, the activity of binocular nBOR neurons was recorded in anesthetized pigeons in response to panoramic translational and rotational optic flow. Translational optic flow was produced by the “translator” projector described in the companion paper, and rotational optic flow was produced by a “planetarium projector” described by Wylie and Frost. The axis of rotation or translation could be positioned to any orientation in three-dimensional space. We recorded from 37 cells, most of which exhibited a strong contralateral dominance. Most of these cells were located in the caudal and dorsal aspects of the nBOR complex and many were localized to the subnucleus nBOR dorsalis. Other units were located outside the boundaries of the nBOR complex in the adjacent area ventralis of Tsai or mesencephalic reticular formation. Six cells responded best to rotational flowfields, whereas 31 responded best to translational flowfields. Of the rotation cells, three preferred rotation about the vertical axis and three preferred horizontal axes. Of the translation cells, 3 responded best to a flowfield simulating downward translation of the bird along a vertical axis, whereas the remaining 28 responded best to flowfields resulting from translation along axes in the horizontal plane. Seventeen of these cells preferred a flowfield resulting from the animal translating backward along an axis oriented ∼45° to the midline, but the best axes of the remaining eleven cells were distributed throughout the horizontal plane with no definitive clustering. These data are compared with the responses of vestibulocerebellar Purkinje cells.

Maximization of Workspace Volume of 3-DOF Spatial Parallel Manipulators

2002 ◽  
Vol 124 (2) ◽  
pp. 347-350 ◽  
Author(s):  
Karol Miller
Keyword(s):  
Western Australia ◽  
Horizontal Plane ◽  
Patent Application ◽  
Vertical Axis ◽  
Parallel Manipulators ◽  
Delta Robot

In this work we investigate the influence of motor axes orientation on the workspace volume of 3-DOF manipulators, showing that the Delta configuration is not optimal. The configuration characterized by α=ArcTan1/2≈35.26°—the inclination of each motor axis to the horizontal plane (for the Delta robot α=0°), and β=60°—the rotation of each motor with respect to the vertical axis (for the Delta robot β=0°), known as the New University of Western Australia Robot (NUWAR) is shown to be advantageous over the Delta configuration in terms of workspace volume and shape. These results led to the construction of a prototype and an Australian Patent application.

Sign in / Sign up

Export Citation Format

Share Document