Apparent Rotation of a Line Superimposed upon Radially Expanding and Contracting Backgrounds

Perception ◽  
1981 ◽  
Vol 10 (3) ◽  
pp. 265-271 ◽  
Author(s):  
Michael T Swanston ◽  
Nicholas J Wade
Keyword(s):  
Oblique Line ◽  
Relative Orientation ◽  
Head Movements ◽  
Apparent Rotation ◽  
Stationary Observer ◽  
Horizontal Grating

An oblique line superimposed on a vertical or horizontal grating appears to rotate when the whole pattern is expanded or contracted. The apparent rotation occurs with head movements towards or away from a stationary grating, or with zooming a grating relative to a stationary observer. The magnitude and direction of the apparent rotation is dependent upon the relative inclination of the line to the grating and is most pronounced with a relative orientation of 45°.

Factors Influencing the Apparent Rotation of a Line on Radially Transformed Backgrounds

Perception ◽  
1983 ◽  
Vol 12 (3) ◽  
pp. 313-322 ◽  
Author(s):  
Nicholas J Wade ◽  
Michael T Swanston ◽  
Hiroshi Ono ◽  
Peter M Wenderoth
Keyword(s):  
Spatial Frequency ◽  
Oblique Line ◽  
Zoom Lens ◽  
Television System ◽  
Vertical Grating ◽  
Apparent Rotation ◽  
Factors Influencing ◽  
Constant Rate ◽  
Orientation Anisotropy ◽  
Angular Subtense

The expansion and contraction of a display consisting of a stationary grating with a superimposed inclined line leads to the apparent rotation of the line. This phenomenon has been investigated in six experiments with the use of a television system with a motorized zoom lens to effect such transformations. The maximum apparent line rotation occurs with the line at 45° to the grating. In experiment 1 a greater magnitude of apparent rotation was found with a vertical grating and an oblique line than vice versa. Zoom-out (contraction) also produced greater rotation than zoom-in (expansion). The orientation anisotropy was not dependent upon the orientation of the display to the retinal meridian (experiment 2): the extent of apparent line rotation was approximately the same with a vertical grating when the head was upright or tilted so that the retinal meridian was at 45°. At a constant rate of zooming, a zoom duration of 2 s produced a larger apparent line rotation than one of 1 s, but it was not influenced by the initial angular subtense of the superimposed line (experiment 3). Neither the spatial frequency of the grating nor the width of the line affected the apparent rotation (experiments 4, 5, and 6). Experiment 5 compared the apparent rotation when the display was zoomed (i) with a fixed surround and (ii) with a surround that also expanded during zooming. The magnitude of rotation in the latter condition was reduced to about 25% of that with a fixed surround. The results are discussed in terms of the discrepancy between the perceived transformations of the background grating and the superimposed line.

The orientation of sickle hemoglobin fibers within fascicles

1988 ◽  
Vol 46 ◽  
pp. 400-401
Author(s):  
Christopher A. Miller ◽  
Bridget Carragher ◽  
William A. McDade ◽  
Robert Josephs
Keyword(s):  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Relative Orientation ◽  
Unit Cell ◽  
Red Cell ◽  
High Ph ◽  
Sickle Hemoglobin ◽  
Polar Crystal ◽  
Helical Configuration

Highly ordered bundles of deoxyhemoglobin S (HbS) fibers, termed fascicles, are intermediates in the high pH crystallization pathway of HbS. These fibers consist of 7 Wishner-Love double strands in a helical configuration. Since each double strand has a polarity, the odd number of double strands in the fiber imparts a net polarity to the structure. HbS crystals have a unit cell containing two double strands, one of each polarity, resulting in a net polarity of zero. Therefore a rearrangement of the double strands must occur to form a non-polar crystal from the polar fibers. To determine the role of fascicles as an intermediate in the crystallization pathway it is important to understand the relative orientation of fibers within fascicles. Furthermore, an understanding of fascicle structure may have implications for the design of potential sickling inhibitors, since it is bundles of fibers which cause the red cell distortion responsible for the vaso-occlusive complications characteristic of sickle cell anemia.

The coprecipitation of Cr3P and Cr in Cu

1988 ◽  
Vol 46 ◽  
pp. 764-765
Author(s):  
M.J. Witcomb ◽  
U. Dahmen ◽  
K.H. Westmacott
Keyword(s):  
Orientation Relationship ◽  
Interface Structure ◽  
Model System ◽  
Relative Orientation ◽  
Age Hardening ◽  
Precipitation Behavior ◽  
Solution Treated ◽  
Small Needle ◽  
Diffraction Patterns ◽  
Interface Structures

Cu-Cr age-hardening alloys are of interest as a model system for the investigation of fcc/bcc interface structures. Several past studies have investigated the morphology and interface structure of Cr precipitates in a Cu matrix (1-3) and good success has been achieved in understanding the crystallography and strain contrast of small needle-shaped precipitates. The present study investigates the effect of small amounts of phosphorous on the precipitation behavior of Cu-Cr alloys.The same Cu-0.3% Cr alloy as was used in earlier work was rolled to a thickness of 150 μm, solution treated in vacuum at 1050°C for 1h followed by quenching and annealing for various times at 820 and 863°C.Two laths and their corresponding diffraction patterns in an alloy aged 2h at 820°C are shown in correct relative orientation in Fig. 1. To within the limit of accuracy of the diffraction patterns the orientation relationship was that of Kurdjumov-Sachs (KS), i.e. parallel close-packed planes and directions.

Role of pinnae and head movements in localizing pure tones 1The authors would like to thank Mr. Remi Humbert for implementing the experiment in Turbo Pascal and for his further assistance.

1999 ◽  
Vol 58 (3) ◽  
pp. 170-179 ◽  
Author(s):  
Barbara S. Muller ◽  
Pierre Bovet
Keyword(s):  
Sound Source ◽  
Head Movement ◽  
Movement Analysis ◽  
Head Movements ◽  
Sound Sources ◽  
Localization Accuracy ◽  
Sound Effects ◽  
Posterior Quadrant ◽  
Localization Performance ◽  
Pure Tones

Twelve blindfolded subjects localized two different pure tones, randomly played by eight sound sources in the horizontal plane. Either subjects could get information supplied by their pinnae (external ear) and their head movements or not. We found that pinnae, as well as head movements, had a marked influence on auditory localization performance with this type of sound. Effects of pinnae and head movements seemed to be additive; the absence of one or the other factor provoked the same loss of localization accuracy and even much the same error pattern. Head movement analysis showed that subjects turn their face towards the emitting sound source, except for sources exactly in the front or exactly in the rear, which are identified by turning the head to both sides. The head movement amplitude increased smoothly as the sound source moved from the anterior to the posterior quadrant.

Comparison of Quantified Ipsilateral and Contralateral Head Movements in Patients with Frontal and Temporal Lobe Epilepsies

2004 ◽  
Vol 35 (03) ◽  
Author(s):  
P Wagner ◽  
J Cunha ◽  
C Mauerer ◽  
C Vollmar ◽  
B Feddersen ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Head Movements

Robust algorithms for relative orientation

2001 ◽  
Vol 36 (1) ◽  
pp. 35-38 ◽  
Author(s):  
Judit Somogyi ◽  
L. Battha
Keyword(s):  
Relative Orientation ◽  
Robust Algorithms

Carotid Artery Dynamics During Head Movements: A Reason for Concern With Regard to Carotid Stenting?

2003 ◽  
Vol 10 (5) ◽  
pp. 862-869 ◽  
Author(s):  
A. W. Floris Vos ◽  
Matteus A. M. Linsen ◽  
J. Tim Marcus ◽  
Jos C. van den Berg ◽  
Jan Albert Vos ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Carotid Stenting ◽  
Head Movements

Postural Control during Downward Head Movements in Young Subjects

2007 ◽  
Vol 29 (3) ◽  
pp. 205-212
Author(s):  
Junko Fukushima ◽  
Tadayoshi Asaka ◽  
Natsumi Ikeda ◽  
Yumi Ito
Keyword(s):  
Postural Control ◽  
Head Movements ◽  
Young Subjects
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