Research on GM-APD lidar intense information correction technology based on target distance

In the developing vertebrate nervous system the survival of neurons becomes dependent on the supply of a neurotrophic factor from their targets when their axons reach these targets. To determine how the onset of neurotrophic factor dependency is coordinated with the arrival of axons in the target field, we have studied the growth and survival of four populations of cranial sensory neurons whose axons have markedly different distances to grow to reach their targets. Axonal growth rate both in vivo and in vitro is related to target distance; neurons with more distant targets grow faster. The onset trophic factor dependency in culture is also related to target distance; neurons with more distant targets survive longer before becoming trophic factor dependent. These data suggest that programmes of growth and survival in early neurons play an important role in coordinating the timing of trophic interactions in the developing nervous system.

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Effect of lens-to-target distance on the determination of Cr in water by laser-induced breakdown spectroscopy and electro-deposition method

Journal of Analytical Atomic Spectrometry ◽

10.1039/d1ja00275a ◽

2021 ◽

Author(s):

Qiuyun Wang ◽

Ting Ge ◽

Yitong Liu ◽

Anmin Chen ◽

Suyu Li ◽

...

Keyword(s):

Target Distance ◽

Laser Induced Breakdown Spectroscopy ◽

Deposition Method ◽

Electro Deposition ◽

Breakdown Spectroscopy ◽

Laser Induced Breakdown

This paper studied the effect of lens-to-target distance (LTTD) on the determination of Cr in water by laser-induced breakdown spectroscopy and electro-deposition (ED) method. First, the metal ED method realized...

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Effect of Jet-to-Jet Distance and Pipe Position on Flow and Heat Transfer Features of Active Clearance Control Systems

10.1115/gt2021-59158 ◽

2021 ◽

Author(s):

Lorenzo Cocchi ◽

Alessio Picchi ◽

Bruno Facchini ◽

Riccardo Da Soghe ◽

Lorenzo Mazzei ◽

...

Keyword(s):

Heat Transfer ◽

Target Surface ◽

Reynolds Numbers ◽

Metal Plate ◽

Target Distance ◽

Target Plate ◽

Ir Camera ◽

Supply Pipe ◽

Heating Up ◽

Clearance Control

Abstract The goal of the present work is to investigate the effect of supply pipe position on the heat transfer features of various active clearance control (ACC) geometries, characterized by different jet-to-jet distances. All geometries present 0.8 mm circular impingement holes arranged in a single row. The jets generated by such holes cool a flat target surface, which is replicated by a metal plate in the experimental setup. Measurements are performed using the steady-state technique, obtained by heating up the target plate thanks to an electrically heated Inconel foil applied on the side of the target opposite to the jets. Temperature is also measured on this side by means of an IR camera. Heat transfer is then evaluated thanks to a custom designed finite difference procedure, capable of solving the inverse conduction problem on the target plate. The effect of pipe positioning is studied in terms of pipe-to-target distance (from 3 to 11 jet diameters) and pipe orientation (i.e. rotation around its axis, from 0° to 40° with respect to target normal direction), while the investigated jet Reynolds numbers range from 6000 to 10000. The obtained results reveal that heat transfer is maximized for a given pipe-to-target distance, dependent on both jet-to-jet distance and target surface extension. Pipe rotation also affects the cooling features in a non-monotonic way, suggesting the existence of different flow regimes related to jet inclination.

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Saccadic Gain Modification: Visual Error Drives Motor Adaptation

Journal of Neurophysiology ◽

10.1152/jn.1998.80.5.2405 ◽

1998 ◽

Vol 80 (5) ◽

pp. 2405-2416 ◽

Cited By ~ 129

Author(s):

Josh Wallman ◽

Albert F. Fuchs

Keyword(s):

Target Location ◽

Rhesus Macaques ◽

Motor Adaptation ◽

Saccadic Eye Movements ◽

Target Distance ◽

Error Signal ◽

Gain Adaptation ◽

Horizontal Saccade ◽

Corrective Saccades ◽

Visual Error

Wallman, Josh and Albert F. Fuchs. Saccadic gain modification: visual error drives motor adaptation. J. Neurophysiol. 80: 2405–2416, 1998. The brain maintains the accuracy of saccadic eye movements by adjusting saccadic amplitude relative to the target distance (i.e., saccade gain) on the basis of the performance of recent saccades. If an experimenter surreptitiously moves the target backward during each saccade, thereby causing the eyes to land beyond their targets, saccades undergo a gradual gain reduction. The error signal driving this conventional saccadic gain adaptation could be either visual (the postsaccadic distance of the target from the fovea) or motoric (the direction and size of the corrective saccade that brings the eye onto the back-stepped target). Similarly, the adaptation itself might be a motor adjustment (change in the size of saccade for a given perceived target distance) or a visual remapping (change in the perceived target distance). We studied these possibilities in experiments both with rhesus macaques and with humans. To test whether the error signal is motoric, we used a paradigm devised by Heiner Deubel. The Deubel paradigm differed from the conventional adaptation paradigm in that the backward step that occurred during the saccade was brief, and the target then returned to its original displaced location. This ploy replaced most of the usual backward corrective saccades with forward ones. Nevertheless, saccadic gain gradually decreased over hundreds of trials. Therefore, we conclude that the direction of saccadic gain adaptation is not determined by the direction of corrective saccades. To test whether gain adaptation is a manifestation of a static visual remapping, we decreased the gain of 10° horizontal saccades by conventional adaptation and then tested the gain to targets appearing at retinal locations unused during adaptation. To make the target appear in such “virgin territory,” we had it jump first vertically and then 10° horizontally; both jumps were completed and the target spot extinguished before saccades were made sequentially to the remembered target locations. Conventional adaptation decreased the gain of the second, horizontal saccade even though the target was in a nonadapted retinal location. In contrast, the horizontal component of oblique saccades made directly to the same virgin location showed much less gain decrease, suggesting that the adaptation is specific to saccade direction rather than to target location. Thus visual remapping cannot account for the entire reduction of saccadic gain. We conclude that saccadic gain adaptation involves an error signal that is primarily visual, not motor, but that the adaptation itself is primarily motor, not visual.

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Viewing Target Distance Influences the Vestibulo-Ocular Reflex Gain when Assessed Using the Video Head Impulse Test

Audiology and Neurotology ◽

10.1159/000493845 ◽

2018 ◽

Vol 23 (5) ◽

pp. 285-289 ◽

Cited By ~ 2

Author(s):

Patricia Castro ◽

Sara Sena Esteves ◽

Florencia Lerchundi ◽

David Buckwell ◽

Michael A. Gresty ◽

...

Keyword(s):

Head Movements ◽

Target Distance ◽

Head Impulse Test ◽

Video Head Impulse Test ◽

Gaze Stabilization ◽

Head Impulse ◽

Ocular Reflex ◽

Significant Difference ◽

Vestibulo Ocular Reflex ◽

Reflex Gain

Gaze stabilization during head movements is provided by the vestibulo-ocular reflex (VOR). Clinical assessment of this reflex is performed using the video Head Impulse Test (vHIT). To date, the influence of different fixation distances on VOR gain using the vHIT has not been explored. We assessed the effect of target proximity on the horizontal VOR using the vHIT. Firstly, we assessed the VOR gain in 18 healthy subjects with 5 viewing target distances (150, 40, 30, 20, and 10 cm). The gain increased significantly as the viewing target distance decreased. A second experiment on 10 subjects was performed in darkness whilst the subjects were imagining targets at different distances. There were significant inverse relationships between gain and distance for both the real and the imaginary targets. There was a statistically significant difference between light and dark gains for the 20- and 40-cm distances, but not for the 150-cm distance. Theoretical VOR gains for different target distances were calculated and compared with those found in light and darkness. The increase in gain observed for near targets was lower than predicted by geometrical calculations, implying a physiological ceiling effect on the VOR. The VOR gain in the dark, as assessed with the vHIT, demonstrates an enhancement associated with a reduced target distance.

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

Journal of Neurophysiology ◽

10.1152/jn.1997.78.4.2129 ◽

1997 ◽

Vol 78 (4) ◽

pp. 2129-2144 ◽

Cited By ~ 82

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.

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