Novel use of differential image velocity invariants to categorize ciliary motion defects

2011 ◽  
Author(s):  
Shannon Quinn ◽  
Richard Francis ◽  
Cecilia Lo ◽  
Chakra Chennubhotla
Keyword(s):  
Image Velocity ◽  
Ciliary Motion

Mixing of solutions by coordinated ciliary motion in Vorticella convallaria and patterning method for microfluidic applications

2013 ◽  
Vol 188 ◽  
pp. 1255-1262 ◽  
Author(s):  
Moeto Nagai ◽  
Yo Hayasaka ◽  
Kei Kato ◽  
Takahiro Kawashima ◽  
Takayuki Shibata
Keyword(s):  
Ciliary Motion

Comment on Dr. Gilmour's views on feeding by hemichordates and lophophorates

1982 ◽  
Vol 60 (12) ◽  
pp. 3466-3468 ◽  
Author(s):  
Richard R. Strathmann
Keyword(s):  
Particle Capture ◽  
Ciliary Motion

Observations on motion of captured particles, films of ciliary motion during particle capture, and physical theories of the motion of particles and water contradict substantial parts of Dr. Gilmour's accounts of ciliary feeding by hemichordates and lophophorates. (T. H. J. Gilmour. 1982. Feeding in tornaria larvae and the development of gill slits in enteropneust hemichordates. Can. J. Zool. 60. This issue.)

Human Gaze Stabilization During Natural Activities: Translation, Rotation, Magnification, and Target Distance Effects

1997 ◽  
Vol 78 (4) ◽  
pp. 2129-2144 ◽  
Author(s):  
Benjamin T. Crane ◽  
Joseph L. Demer
Keyword(s):  
Slip Velocity ◽  
Active Role ◽  
Target Distance ◽  
Viewing Condition ◽  
Gaze Stabilization ◽  
Visual Pursuit ◽  
Image Velocity ◽  
Gain Enhancement ◽  
Distance Effects ◽  
Vestibulo Ocular Reflex

Crane, Benjamin T. and Joseph L. Demer. Human gaze stabilization during natural activities: translation, rotation, magnification, and target distance effects. J. Neurophysiol. 78: 2129–2144, 1997. Stability of images on the retina was determined in 14 normal humans in response to rotational and translational perturbations during self-generated pitch and yaw, standing, walking, and running on a treadmill. The effects on image stability of target distance, vision, and spectacle magnification were examined. During locomotion the horizontal and vertical velocity of images on the retina was <4°/s for a visible target located beyond 4 m. Image velocity significantly increased to >4°/s during self-generated motion. For all conditions of standing and locomotion, angular vestibulo-ocular reflex (AVOR) gain was less than unity and varied significantly by activity, by target distance, and among subjects. There was no significant correlation( P > 0.05) between AVOR gain and image stability during standing and walking despite significant variation among subjects. This lack of correlation is likely due to translation of the orbit. The degree of orbital translation and rotation varied significantly with activity and viewing condition in a manner suggesting an active role in gaze stabilization. Orbital translation was consistently antiphase with rotation at predominant frequencies <4 Hz. When orbital translation was neglected in computing gaze, computed image velocities increased. The compensatory effect of orbital translation allows gaze stabilization despite subunity AVOR gain during natural activities. Orbital translation decreased during close target viewing, whereas orbital rotation decreased while wearing telescopic spectacles. As the earth fixed target was moved closer, image velocity on the retina significantly increased ( P < 0.05) for all activities except standing. Latency of the AVOR increased slightly with decreasing target distance but remained <10 ms for even the closest target. This latency was similar in darkness or light, indicating that the visual pursuit tracking is probably not important in gaze stabilization. Trials with a distant target were repeated while subjects wore telescopic spectacles that magnified vision by 1.9 or 4 times. Gain of the AVOR was enhanced by magnified vision during all activities, but always to a value less than spectacle magnification. Gain enhancement was greatest during self-generated sinusoidal motion at 0.8 Hz and was less during standing, walking, and running. Image slip velocity on the retina increased with increasing magnification. During natural activities, slip velocity with telescopes increased most during running and least during standing. Latency of the visually enhanced AVOR significantly increased with magnification ( P < 0.05), probably reflecting a contribution of the visual pursuit system. The oculomotor estimate of target distance was inferred by measuring binocular convergence, as well as from monocular parallax during head translation. In darkness, target distance estimates obtained by both techniques were less accurate than in light, consistently overestimating for near and underestimating for far targets.

scholarly journals Swimming like algae: biomimetic soft artificial cilia

2013 ◽  
Vol 10 (78) ◽  
pp. 20120666 ◽  
Author(s):  
Sina Sareh ◽  
Jonathan Rossiter ◽  
Andrew Conn ◽  
Knut Drescher ◽  
Raymond E. Goldstein
Keyword(s):  
Smart Materials ◽  
Fluid Transport ◽  
Metal Composite ◽  
Ionic Polymer ◽  
Piecewise Constant ◽  
Ciliary Motion ◽  
Thrust Generation ◽  
Artificial Cilia ◽  
Segmentation Pattern ◽  
Polymer Metal

Cilia are used effectively in a wide variety of biological systems from fluid transport to thrust generation. Here, we present the design and implementation of artificial cilia, based on a biomimetic planar actuator using soft-smart materials. This actuator is modelled on the cilia movement of the alga Volvox , and represents the cilium as a piecewise constant-curvature robotic actuator that enables the subsequent direct translation of natural articulation into a multi-segment ionic polymer metal composite actuator. It is demonstrated how the combination of optimal segmentation pattern and biologically derived per-segment driving signals reproduce natural ciliary motion. The amenability of the artificial cilia to scaling is also demonstrated through the comparison of the Reynolds number achieved with that of natural cilia.

A model for the estimate of local image velocity by cells in the visual cortex

1990 ◽  
Vol 239 (1295) ◽  
pp. 129-161 ◽  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Spatial Integration ◽  
Temporal Area ◽  
Image Velocity ◽  
Tuning Curves ◽  
Spatio Temporal ◽  
Local Image

Some computational theories of motion perception assume that the first stage en route to this perception is the local estimate of image velocity. However, this assumption is not supported by data from the primary visual cortex. Its motion sensitive cells are not selective to velocity, but rather are directionally selective and tuned to spatio-temporal frequen­cies. Accordingly, physiologically based theories start with filters selec­tive to oriented spatio-temporal frequencies. This paper shows that computational and physiological theories do not necessarily conflict, because such filters may, as a population, compute velocity locally. To prove this point, we show how to combine the outputs of a class of frequency tuned filters to detect local image velocity. Furthermore, we show that the combination of filters may simulate ‘Pattern’ cells in the middle temporal area (MT), whereas each filter simulates primary visual cortex cells. These simulations include three properties of the primary cortex. First, the spatio-temporal frequency tuning curves of the in­dividual filters display approximate space-time separability. Secondly, their direction-of-motion tuning curves depend on the distribution of orientations of the components of the Fourier decomposition and speed of the stimulus. Thirdly, the filters show facilitation and suppression for responses to apparent motions in the preferred and null directions, respect­ively. It is suggested that the MT’s role is not to solve the aperture problem, but to estimate velocities from primary cortex information. The spatial integration that accounts for motion coherence may be postponed to a later cortical stage.

scholarly journals New image velocity code explains contrast and center-surround effects in MT neurons

2010 ◽  
Vol 9 (8) ◽  
pp. 664-664
Author(s):  
J. A. Perrone ◽  
R. J. Krauzlis
Keyword(s):  
Image Velocity ◽  
Mt Neurons

Adaptive visual servoing scheme free of image velocity measurement for uncertain robot manipulators

Automatica ◽  
2013 ◽  
Vol 49 (5) ◽  
pp. 1304-1309 ◽  
Author(s):  
Fernando Lizarralde ◽  
Antonio C. Leite ◽  
Liu Hsu ◽  
Ramon R. Costa
Keyword(s):  
Velocity Measurement ◽  
Visual Servoing ◽  
Robot Manipulators ◽  
Image Velocity ◽  
Uncertain Robot

scholarly journals I. On the embryogeny of comatula rosacea (Linck)

1859 ◽  
Vol 9 ◽  
pp. 600-601
Keyword(s):  
Granular Matter ◽  
Reproductive Organs ◽  
Areolar Tissue ◽  
Young Larva ◽  
Characteristic Form ◽  
Male And Female ◽  
Pale Yellow ◽  
Ciliary Motion ◽  
Female Reproductive Organs

The author briefly described the male and female reproductive organs of Comatula. When the ova are mature, and before impregnation, they are protruded and remain hanging from the ovarian orifice, entangled in the areolar tissue of the everted ovary. In this position impregnation appears usually to take place. After segmentation of the yelk, a solid nucleus is formed in the centre of the mulberry yelk-mass. This nucleus becomes invested in a special membrane, and into this embryonic mass the remainder of the yelk is gradually absorbed. Ciliary motion is observed at various points on the surface of the inclosed embryo, which finally assumes its characteristic form. The young larva, on escaping from the egg, consists of a homogeneous mass of pale-yellow granular matter, with scattered nuclei, cells, and oil-globules. It is barrel-shaped, and girded at intervals with about five broad ciliated bands.

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