scholarly journals Morphological and behavioral limit of visual resolution in temperate (Hippocampus abdominalis) and tropical (Hippocampus taeniopterus) seahorses

2011 ◽  
Vol 28 (4) ◽  
pp. 351-360 ◽  
Author(s):  
HIE RIN LEE ◽  
KEELY M. BUMSTED O’BRIEN
Keyword(s):  
Fast Moving ◽  
Visually Guided ◽  
Resolution Limit ◽  
Theoretical Limit ◽  
Visual Resolution ◽  
Reactive Distance ◽  
Density Decrease ◽  
Foveal Center ◽  
Hippocampus Abdominalis ◽  
Lens Radius

AbstractSeahorses are visually guided feeders that prey upon small fast-moving crustaceans. Seahorse habitats range from clear tropical to turbid temperate waters. How are seahorse retinae specialized to mediate vision in these diverse environments? Most species of seahorse have a specialization in their retina associated with acute vision, the fovea. The purpose of this study was to characterize the fovea of temperate Hippocampus abdominalis and tropical H. taeniopterus seahorses and to investigate their theoretical and behavioral limits of visual resolution. Their foveae were identified and photoreceptor (PR) and ganglion cell (GC) densities determined throughout the retina and topographically mapped. The theoretical limit of visual resolution was calculated using formulas taking into account lens radius and either cone PR or GC densities. Visual resolution was determined behaviorally using reactive distance. Both species possess a rod-free convexiclivate fovea. PR and GC densities were highest along the foveal slope, with a density decrease within the foveal center. Outside the fovea, there was a gradual density decrease towards the periphery. The theoretically calculated visual resolution on the foveal slope was poorer for H. abdominalis (5.25 min of arc) compared with H. taeniopterus (4.63 min of arc) based on PR density. Using GC density, H. abdominalis (9.81 min of arc) had a lower resolution compared with H. taeniopterus (9.04 min of arc). Behaviorally, H. abdominalis had a resolution limit of 1090.64 min of arc, while H. taeniopterus was much smaller, 692.86 min of arc. Although both species possess a fovea and the distribution of PR and GC is similar, H. taeniopterus has higher PR and GC densities on the foveal slope and better theoretical and behaviorally measured visual resolution compared to H. abdominalis. These data indicate that seahorses have a well-developed acute visual system, and tropical seahorses have higher visual resolution compared to temperate seahorses.

Cone spacing and the visual resolution limit

1987 ◽  
Vol 4 (8) ◽  
pp. 1514 ◽  
Author(s):  
David R. Williams ◽  
Nancy J. Coletta
Keyword(s):  
Resolution Limit ◽  
Visual Resolution

scholarly journals Toward the Ultimate-High-Speed Image Sensor: From 10 ns to 50 ps

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2407 ◽  
Author(s):  
Anh Nguyen ◽  
Vu Dao ◽  
Kazuhiro Shimonomura ◽  
Kohsei Takehara ◽  
Takeharu Etoh
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
Image Sensor ◽  
Image Sensors ◽  
Frame Rate ◽  
Resolution Limit ◽  
Performance Indices ◽  
Theoretical Limit ◽  
Theoretical Derivation ◽  
Trade Offs

The paper summarizes the evolution of the Backside-Illuminated Multi-Collection-Gate (BSI MCG) image sensors from the proposed fundamental structure to the development of a practical ultimate-high-speed silicon image sensor. A test chip of the BSI MCG image sensor achieves the temporal resolution of 10 ns. The authors have derived the expression of the temporal resolution limit of photoelectron conversion layers. For silicon image sensors, the limit is 11.1 ps. By considering the theoretical derivation, a high-speed image sensor designed can achieve the frame rate close to the theoretical limit. However, some of the conditions conflict with performance indices other than the frame rate, such as sensitivity and crosstalk. After adjusting these trade-offs, a simple pixel model of the image sensor is designed and evaluated by simulations. The results reveal that the sensor can achieve a temporal resolution of 50 ps with the existing technology.

scholarly journals High turbidity levels alter coral reef fish movement in a foraging task

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cait Newport ◽  
Oliver Padget ◽  
Theresa Burt de Perera
Keyword(s):  
Sensory Systems ◽  
Visual Signals ◽  
Foraging Efficiency ◽  
Fish Movement ◽  
Visually Guided ◽  
Experimental Protocol ◽  
Reactive Distance ◽  
High Turbidity ◽  
Foraging Task ◽  
The Impact

AbstractSensory systems allow animals to detect and respond to stimuli in their environment and underlie all behaviour. However, human induced pollution is increasingly interfering with the functioning of these systems. Increased suspended sediment, or turbidity, in aquatic habitats reduces the reactive distance to visual signals and may therefore alter movement behaviour. Using a foraging task in which fish (Rhinecanthus aculeatus) had to find six food sites in an aquarium, we tested the impact of high turbidity (40–68 NTU; 154 mg/L) on foraging efficiency using a detailed and novel analysis of individual movements. High turbidity led to a significant decrease in task efficacy as fish took longer to begin searching and find food, and they travelled further whilst searching. Trajectory analyses revealed that routes were less efficient and that fish in high turbidity conditions were more likely to cover the same ground and search at a slower speed. These results were observed despite the experimental protocol allowing for the use of alternate sensory systems (e.g. olfaction, lateral line). Given that movement underlies fundamental behaviours including foraging, mating, and predator avoidance, a reduction in movement efficiency is likely to have a significant impact on the health and population dynamics of visually-guided fish species.

scholarly journals High contrast, moving targets in an emerging target paradigm promote fast visuomotor responses during visually guided reaching

2021 ◽  
Author(s):  
Rebecca A Kozak ◽  
Brian D Corneil
Keyword(s):  
Upper Limb ◽  
Fast Moving ◽  
Reaction Times ◽  
Short Latency ◽  
High Contrast ◽  
Visually Guided ◽  
Muscle Recruitment ◽  
Moving Targets ◽  
Large Magnitude ◽  
Limb Muscles

Humans have a remarkable capacity to rapidly interact with the surrounding environment, often by transforming visual input into motor output on a moment-to-moment basis. But what visual features promote rapid reaching? High contrast, fast-moving targets elicit strong responses in the superior colliculus (SC), a structure associated with express saccades and implicated in rapid electromyographic (EMG) responses on upper limb muscles. To test the influence of stimulus properties on rapid reaches, we had human subjects perform visually guided reaches to moving targets varied by speed (experiment 1) or speed and contrast (experiment 2), in an emerging target paradigm which has recently been shown to robustly elicit fast visuomotor responses. Our analysis focused on stimulus-locked responses (SLRs) on upper limb muscles. SLRs appear within <100 ms of target presentation, and as the first wave of muscle recruitment, they have been hypothesized to arise from the SC. Across 32 subjects studied in both experiments, 97% expressed SLRs in the emerging target paradigm, whereas only 69% expressed SLRs in an immediate response paradigm towards static targets. Faster moving targets (experiment 1) evoked large magnitude SLRs, while high contrast fast moving targets (experiment 2) evoked short latency, large magnitude SLRs. In some instances, SLR magnitude exceeded the magnitude of movement aligned activity. Both large magnitude and short latency SLRs were correlated with short latency reach reaction times. Our results support the hypothesis that, in scenarios requiring expedited responses, a subcortical pathway originating in the SC elicits the earliest wave of muscle recruitment, expediting reaction times.

Localization of immunolabels by electron microscopy and image averaging

1983 ◽  
Vol 41 ◽  
pp. 282-283
Author(s):  
J. Frank ◽  
P.-Y. Sizaret ◽  
A. Verschoor ◽  
J. Lamy
Keyword(s):  
Electron Microscopy ◽  
Single Particle ◽  
Attachment Site ◽  
Uranyl Acetate ◽  
Limulus Polyphemus ◽  
Resolution Limit ◽  
Electron Microscopic ◽  
Image Averaging ◽  
Top View ◽  
Better Than

The accuracy with which the attachment site of immunolabels bound to macromolecules may be localized in electron microscopic images can be considerably improved by using single particle averaging. The example studied in this work showed that the accuracy may be better than the resolution limit imposed by negative staining (∽2nm).The structure used for this demonstration was a halfmolecule of Limulus polyphemus (LP) hemocyanin, consisting of 24 subunits grouped into four hexamers. The top view of this structure was previously studied by image averaging and correspondence analysis. It was found to vary according to the flip or flop position of the molecule, and to the stain imbalance between diagonally opposed hexamers (“rocking effect”). These findings have recently been incorporated into a model of the full 8 × 6 molecule.LP hemocyanin contains eight different polypeptides, and antibodies specific for one, LP II, were used. Uranyl acetate was used as stain. A total of 58 molecule images (29 unlabelled, 29 labelled with antl-LPII Fab) showing the top view were digitized in the microdensitometer with a sampling distance of 50μ corresponding to 6.25nm.

High Resolution Specimen Area Imaged Under Negligible Field Aberrations

1970 ◽  
Vol 28 ◽  
pp. 540-541 ◽  
Author(s):  
T. Yanaka ◽  
K. Shirota
Keyword(s):  
High Resolution ◽  
Field Distribution ◽  
Image Space ◽  
Beam Deflection ◽  
Objective Lens ◽  
Resolution Limit ◽  
Leakage Flux ◽  
Specimen Area ◽  
Points Of View ◽  
Aberration Theory

It is significant to note field aberrations (chromatic field aberration, coma, astigmatism and blurring due to curvature of field, defined by Glaser's aberration theory relative to the Blenden Freien System) of the objective lens in connection with the following three points of view; field aberrations increase as the resolution of the axial point improves by increasing the lens excitation (k2) and decreasing the half width value (d) of the axial lens field distribution; when one or all of the imaging lenses have axial imperfections such as beam deflection in image space by the asymmetrical magnetic leakage flux, the apparent axial point has field aberrations which prevent the theoretical resolution limit from being obtained.

Contrast from epitaxially sandwiched macromolecules

1978 ◽  
Vol 36 (2) ◽  
pp. 226-227
Author(s):  
M. Talianker ◽  
D.G. Brandon
Keyword(s):  
Gold Film ◽  
Lattice Defect ◽  
Gold Foil ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Resolution Limit ◽  
Transmission Electron ◽  
Crystal Lattice Defect ◽  
Void Effect ◽  
Lattice Resolution

A new specimen preparation technique for visualizing macromolecules by conventional transmission electron microscopy has been developed. In this technique the biopolymer-molecule is embedded in a thin monocrystalline gold foil. Such embedding can be performed in the following way: the biopolymer is deposited on an epitaxially-grown thin single-crystal gold film. The molecule is then occluded by further epitaxial growth. In such an epitaxial sandwich an occluded molecule is expected to behave as a crystal-lattice defect and give rise to contrast in the electron microscope.The resolution of the method should be limited only by the precision with which the epitaxially grown gold reflects the details of the molecular structure and, in favorable cases, can approach the lattice resolution limit.In order to estimate the strength of the contrast due to the void-effect arising from occlusion of the DNA-molecule in a gold crystal some calculations were performed.

New Aspects in the Design of Electron Optical Magnification Systems

1972 ◽  
Vol 30 ◽  
pp. 606-607
Author(s):  
Willem H.J. Andersen
Keyword(s):  
Electron Microscope ◽  
Imaging System ◽  
Chromatic Aberration ◽  
Research Tool ◽  
Energy Losses ◽  
Objective Lens ◽  
Theoretical Limit ◽  
Optical Magnification ◽  
Chromatic Aberrations ◽  
High Degree

Electron microscope design, and particularly the design of the imaging system, has reached a high degree of perfection. Present objective lenses perform up to their theoretical limit, while the whole imaging system, consisting of three or four lenses, provides very wide ranges of magnification and diffraction camera length with virtually no distortion of the image. Evolution of the electron microscope in to a routine research tool in which objects of steadily increasing thickness are investigated, has made it necessary for the designer to pay special attention to the chromatic aberrations of the magnification system (as distinct from the chromatic aberration of the objective lens). These chromatic aberrations cause edge un-sharpness of the image due to electrons which have suffered energy losses in the object.There exist two kinds of chromatic aberration of the magnification system; the chromatic change of magnification, characterized by the coefficient Cm, and the chromatic change of rotation given by Cp.

Low-voltage, high-resolution scanning electron microscopy of polymers

1987 ◽  
Vol 45 ◽  
pp. 466-467 ◽  
Author(s):  
S. J. Krause ◽  
W.W. Adams ◽  
S. Kumar ◽  
T. Reilly ◽  
T. Suziki
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Voltage ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Resolution Limit ◽  
Crossover Point ◽  
New Generation ◽  
Beam Damage ◽  
Scanning Electron

Scanning electron microscopy (SEM) of polymers at routine operating voltages of 15 to 25 keV can lead to beam damage and sample image distortion due to charging. Imaging polymer samples with low accelerating voltages (0.1 to 2.0 keV), at or near the “crossover point”, can reduce beam damage, eliminate charging, and improve contrast of surface detail. However, at low voltage, beam brightness is reduced and image resolution is degraded due to chromatic aberration. A new generation of instruments has improved brightness at low voltages, but a typical SEM with a tungsten hairpin filament will have a resolution limit of about 100nm at 1keV. Recently, a new field emission gun (FEG) SEM, the Hitachi S900, was introduced with a reported resolution of 0.8nm at 30keV and 5nm at 1keV. In this research we are reporting the results of imaging coated and uncoated polymer samples at accelerating voltages between 1keV and 30keV in a tungsten hairpin SEM and in the Hitachi S900 FEG SEM.

Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

1975 ◽  
Vol 33 ◽  
pp. 664-665
Author(s):  
Mircea Fotino
Keyword(s):  
Experimental Approach ◽  
Chromatic Aberration ◽  
Resolving Power ◽  
Biological Research ◽  
Specimen Thickness ◽  
Resolution Limit ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

Sign in / Sign up

Export Citation Format

Share Document