scholarly journals Optical Sensitivity of Camera-Like Eyes to White Light

Vision ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 44
Author(s):  
Irina P. Shepeleva
Keyword(s):  
White Light ◽  
Spatial Summation ◽  
Resolving Power ◽  
Model Organisms ◽  
Ambient Light ◽  
Light Conditions ◽  
Optical Sensitivity ◽  
Transmission Electron ◽  
Gastropod Mollusks ◽  
Convenient Model

Gastropod mollusks are convenient model organisms for studying the functioning of the visual system. The purpose of this work is to estimate the value of the optical sensitivity to white light for the camera-like eyes of gastropod mollusks and humans and analyze its effect on the spatial resolving power in two regions of the retina: in the center—for single photoreceptors of the first/second type in a mollusk and single cones in humans—and in the periphery—for single photoreceptors of the first/second type in a mollusk, as well as for single rods/cones and their groups, subject to spatial summation in humans. The methods of histology, light and transmission electron microscopy, morphometry, calculations and methods of statistical analysis are used in the work. In a mollusk, with a fixed pupil area, the value of the optical sensitivity of the eye to white light in the center of the retina for single photoreceptors of the first/second type is 0.5/0.006 μm2·sr and in the periphery of the retina, 0.9/0.009 μm2·sr. In humans, at the minimum and maximum pupil area, respectively, the value of the optical sensitivity of the eye to white light in the center of the retina (foveola) for single cones varies from 0.00053 to 0.028 μm2·sr, and in the periphery of the retina (far periphery) for single rods from 0.011 to 0.575 μm2·sr, for single cones from 0.025 to 1.319 μm2·sr, for the groups of rods from 3859 to 204,094 μm2·sr and for the groups of cones from 2.5 to 131 μm2·sr. The value of the optical sensitivity of the eyes to white light for single photoreceptors of the first/second type in both regions of the retina in a mollusk, as well as for single cones in the center and groups of rods/cones in the periphery of the retina in humans, corresponds to the ambient light conditions during periods of activity and does not affect the spatial resolving power.

scholarly journals Spatial Resolving Power and Contrast Sensitivity Are Adapted for Ambient Light Conditions in Australian Myrmecia Ants

2019 ◽  
Vol 7 ◽  
Author(s):  
Yuri Ogawa ◽  
Laura A. Ryan ◽  
Ravindra Palavalli-Nettimi ◽  
Olivia Seeger ◽  
Nathan S. Hart ◽  
...  
Keyword(s):  
Contrast Sensitivity ◽  
Resolving Power ◽  
Ambient Light ◽  
Light Conditions

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

A comparative study on the cold type and thermal type field emission guns used in the same electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 58-59
Author(s):  
M. Iwatsuki ◽  
Y. Kokubo ◽  
Y. Harada
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Signal To Noise Ratio ◽  
Electron Source ◽  
Resolving Power ◽  
Optical Source ◽  
Experimental Conditions ◽  
High Brightness ◽  
Illumination System ◽  
Transmission Electron

On accout of its high brightness, small optical source size, and minimal energy spread, the field emission gun (FEG) has the advantage that it provides the conventional transmission electron microscope (TEM) with a highly coherent illumination system and directly improves the resolving power and signal-to-noise ratio of the scanning electron microscope (SEM). The FEG is generally classified into two types; the cold field emission (C-FEG) and thermal field emission gun (T-FEG). The former, in which a field emitter is used at the room temperature, was successfully developed as an electron source for the SEM. The latter, in which the emitter is heated to the temperature range of 1000-1800°K, was also proved to be very suited as an electron source for the TEM, as well as for the SEM. Some characteristics of the two types of the FEG have been studied and reported by many authors. However, the results of the respective types have been obtained separately under different experimental conditions.

scholarly journals Improved CoChR Variants Restore Visual Acuity and Contrast Sensitivity in a Mouse Model of Blindness under Ambient Light Conditions

2019 ◽  
Vol 27 (6) ◽  
pp. 1195-1205 ◽  
Author(s):  
Tushar H. Ganjawala ◽  
Qi Lu ◽  
Mitchell D. Fenner ◽  
Gary W. Abrams ◽  
Zhuo-Hua Pan
Keyword(s):  
Visual Acuity ◽  
Mouse Model ◽  
Contrast Sensitivity ◽  
Ambient Light ◽  
Light Conditions

Understanding of Capping Effects on the Tip Shape Evolution and on the Atom Probe Data of Bulk LaAlO3 Using Transmission Electron Microscopy

2017 ◽  
Vol 23 (2) ◽  
pp. 329-335 ◽  
Author(s):  
Chang-Min Kwak ◽  
Young-Tae Kim ◽  
Chan-Gyung Park ◽  
Jae-Bok Seol
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Resolving Power ◽  
Shape Evolution ◽  
Oxide Materials ◽  
Field Evaporation ◽  
Laser Illumination ◽  
Transmission Electron ◽  
Mass Resolving Power

AbstractTwo challenges exist in laser-assisted atom probe tomography (APT). First, a drastic decline in mass-resolving power is caused, not only by laser-induced thermal effects on the APT tips of bulk oxide materials, but also the associated asymmetric evaporation behavior; second, the field evaporation mechanisms of bulk oxide tips under laser illumination are still unclear due to the complex relations between laser pulse and oxide materials. In this study, both phenomena were investigated by depositing Ni- and Co-capping layers onto the bulk LaAlO3 tips, and using stepwise APT analysis with transmission electron microscopy (TEM) observation of the tip shapes. By employing the metallic capping, the heating at the surface of the oxide tips during APT analysis became more symmetrical, thereby enabling a high mass-resolving power in the mass spectrum. In addition, the stepwise microscopy technique visualized tip shape evolution during APT analysis, thereby accounting for evaporation sequences at the tip surface. The combination of “capping” and “stepwise APT with TEM,” is applicable to any nonconductors; it provides a direct observation of tip shape evolution, allows determination of the field evaporation strength of oxides, and facilitates understanding of the effects of ultrafast laser illumination on an oxide tip.

scholarly journals White Light —White Heat: The use of Fire as a Light and Heat Source in an Atrium House in Roman Pompeii

2021 ◽  
Vol 13 (1) ◽  
pp. 59-75
Author(s):  
Henrik Boman
Keyword(s):  
Heat Source ◽  
White Light ◽  
Light Conditions ◽  
Human Eye ◽  
Dark Shadow ◽  
Interior Walls

This article concerns the distribution of fire as light and heat source within the insula investigated by the ongoing Swedish Pompeii Project. Here the author suggests that fire installations as kitchens, ovens and baths were clustered in specific areas within this insula, and the installations were not efficiently used to heat the dwelling areas of the house. It is also proposed that the surfaces of the interior walls and floors of the Roman atrium house were polished in purpose to reflect and distribute light and, which is emphasised in the article, to soften the transition between brightly lit areas and areas in dark shadow. This contrast had to be eliminated for the human eye to adopt to the light conditions in the room and by that, to make the light as efficient as possible.

scholarly journals Far-Red Light Acclimation for Improved Mass Cultivation of Cyanobacteria

Metabolites ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 170 ◽  
Author(s):  
Alla Silkina ◽  
Bethan Kultschar ◽  
Carole A. Llewellyn
Keyword(s):  
Biomass Production ◽  
White Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Industrial Biotechnology ◽  
Light Conditions ◽  
Light Emitting ◽  
Mass Cultivation ◽  
Chlorogloeopsis Fritschii ◽  
Bioactive Product

Improving mass cultivation of cyanobacteria is a goal for industrial biotechnology. In this study, the mass cultivation of the thermophilic cyanobacterium Chlorogloeopsis fritschii was assessed for biomass production under light-emitting diode white light (LEDWL), far-red light (FRL), and combined white light and far-red light (WLFRL) adaptation. The induction of chl f was confirmed at 24 h after the transfer of culture from LEDWL to FRL. Using combined light (WLFRL), chl f, a, and d, maintained the same level of concentration in comparison to FRL conditions. However, phycocyanin and xanthophylls (echinone, caloxanthin, myxoxanthin, nostoxanthin) concentration increased 2.7–4.7 times compared to LEDWL conditions. The productivity of culture was double under WLFRL compared with LEDWL conditions. No significant changes in lipid, protein, and carbohydrate concentrations were found in the two different light conditions. The results are important for informing on optimum biomass cultivation of this species for biomass production and bioactive product development.

The Effects on Visually Impaired Children of Viewing Fluorescent Stimuli under Black-Light Conditions

1998 ◽  
Vol 92 (5) ◽  
pp. 313-321 ◽  
Author(s):  
S.J. LaGrow ◽  
J-P Leung ◽  
S. Leung ◽  
P. Yeung
Keyword(s):  
Visual Acuity ◽  
White Light ◽  
Visually Impaired ◽  
Low Vision ◽  
Visual Performance ◽  
Light Conditions ◽  
Black Light ◽  
High Acuity ◽  
Impaired Children ◽  
Visually Impaired Children

In this study, 30 children with low vision (divided into a high and a low visual acuity group) were presented with stimuli under four conditions (white stimuli-white light, orange stimuli-white light, white stimuli-black light, and orange stimuli-black light) and were asked to rank their preferences for the four conditions. The goal was to determine the effects of the various combinations of stimuli and lighting on the children's visual performance. The orange stimuli viewed under black light resulted in the best performance overall, benefited the low-acuity group more than the high-acuity group, and was the most-preferred condition for both groups.

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