13,261 research outputs found
Systematic biases in human heading estimation.
Heading estimation is vital to everyday navigation and locomotion. Despite extensive behavioral and physiological research on both visual and vestibular heading estimation over more than two decades, the accuracy of heading estimation has not yet been systematically evaluated. Therefore human visual and vestibular heading estimation was assessed in the horizontal plane using a motion platform and stereo visual display. Heading angle was overestimated during forward movements and underestimated during backward movements in response to both visual and vestibular stimuli, indicating an overall multimodal bias toward lateral directions. Lateral biases are consistent with the overrepresentation of lateral preferred directions observed in neural populations that carry visual and vestibular heading information, including MSTd and otolith afferent populations. Due to this overrepresentation, population vector decoding yields patterns of bias remarkably similar to those observed behaviorally. Lateral biases are inconsistent with standard bayesian accounts which predict that estimates should be biased toward the most common straight forward heading direction. Nevertheless, lateral biases may be functionally relevant. They effectively constitute a perceptual scale expansion around straight ahead which could allow for more precise estimation and provide a high gain feedback signal to facilitate maintenance of straight-forward heading during everyday navigation and locomotion
Seven views on approximate convexity and the geometry of K-spaces
As in Hokusai's series of paintings "Thirty six views of mount Fuji" in which
mount Fuji's is sometimes scarcely visible, the central topic of this paper is
the geometry of -spaces although in some of the seven views presented
-spaces are not easily visible. We study the interplay between the behaviour
of approximately convex (and approximately affine) functions on the unit ball
of a Banach space and the geometry of Banach K-spaces.Comment: 2 figure
Sensorless position control of permanent magnet motors with pulsating current injection and compensation of motor end-effects
Blazar properties: an update from recent results
After a brief critical overview of the main properties of blazars and their
classification, some significant results from recent multiwavelength
observations are summarized, in the context of the jet physics.Comment: 5 pages, 2 figures. Invited talk at the 2nd Heidelberg workshop:
"High-Energy Gamma-rays and Neutrinos from Extra-Galactic Sources", January
13-16, 2009, to be published in Int. J. Mod. Phys. D. Updated reference
End effects in linear tubular motors and compensated position sensorless control based on pulsating voltage injection
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