Researchers test light-activated analgesia in mice

2017 ◽  
Keyword(s):  
Test Light

scholarly journals The influence of coloured surrounds and coloured backgrounds on visual thresholds

1932 ◽  
Vol 110 (768) ◽  
pp. 448-482 ◽  
Keyword(s):  
Dark Adaptation ◽  
Retinal Area ◽  
Scattering Of Light ◽  
Test Light

The present observations were a development of previous work on the effect of lights of different wave-lengths on each other when superimposed on the same retinal area (Roaf, 1928). The methods used were (a) to measure the threshold of a test light when shining alongside a modifying light, and (6) to measure the threshold when the modifying light shone on the same part of the retina as the test light, thus forming a background for it. It was assumed in that paper that by measuring the threshold of the test light when shining alongside the modifying light the observer’s eye would be in the same state of dark adaptation as when the two lights were superimposed, but it was pointed out that adaptation might be local and that “scattering” of light might have affected the results (Roaf, 1928, p. 254).

scholarly journals Polyamine Metabolism under Different Light Regimes in Wheat

2021 ◽  
Vol 22 (21) ◽  
pp. 11717
Author(s):  
Orsolya Kinga Gondor ◽  
Judit Tajti ◽  
Kamirán Áron Hamow ◽  
Imre Majláth ◽  
Gabriella Szalai ◽  
...  
Keyword(s):  
Gene Expression ◽  
Fine Tuning ◽  
Polyamine Metabolism ◽  
Light Conditions ◽  
Light Regimes ◽  
Test Light ◽  
Lower Light ◽  
The Relationship ◽  
Back Conversion ◽  
Gene Expression Levels

Although the relationship between polyamines and photosynthesis has been investigated at several levels, the main aim of this experiment was to test light-intensity-dependent influence of polyamine metabolism with or without exogenous polyamines. First, the effect of the duration of the daily illumination, then the effects of different light intensities (50, 250, and 500 μmol m–2 s–1) on the polyamine metabolism at metabolite and gene expression levels were investigated. In the second experiment, polyamine treatments, namely putrescine, spermidine and spermine, were also applied. The different light quantities induced different changes in the polyamine metabolism. In the leaves, light distinctly induced the putrescine level and reduced the 1,3-diaminopropane content. Leaves and roots responded differently to the polyamine treatments. Polyamines improved photosynthesis under lower light conditions. Exogenous polyamine treatments influenced the polyamine metabolism differently under individual light regimes. The fine-tuning of the synthesis, back-conversion and terminal catabolism could be responsible for the observed different polyamine metabolism-modulating strategies, leading to successful adaptation to different light conditions.

scholarly journals Chromatic assimilation unaffected by perceived depth of inducing light

2004 ◽  
Vol 21 (3) ◽  
pp. 373-376 ◽  
Author(s):  
STEVEN K. SHEVELL ◽  
DINGCAI CAO
Keyword(s):  
Depth Perception ◽  
Binocular Disparity ◽  
Neural Mechanism ◽  
Relative Depth ◽  
Test Field ◽  
Neural Process ◽  
Test Light ◽  
Chromatic Assimilation ◽  
Field Organization ◽  
Receptive Field Organization

Chromatic assimilation is a shift toward the color of nearby light. Several studies conclude that a neural process contributes to assimilation but the neural locus remains in question. Some studies posit a peripheral process, such as retinal receptive-field organization, while others claim the neural mechanism follows depth perception, figure/ground segregation, or perceptual grouping. The experiments here tested whether assimilation depends on a neural process that follows stereoscopic depth perception. By introducing binocular disparity, the test field judged in color was made to appear in a different depth plane than the light that induced assimilation. The chromaticity and spatial frequency of the inducing light, and the chromaticity of the test light, were varied. Chromatic assimilation was found with all inducing-light sizes and chromaticities, but the magnitude of assimilation did not depend on the perceived relative depth planes of the test and inducing fields. We found no evidence to support the view that chromatic assimilation depends on a neural process that follows binocular combination of the two eyes' signals.

LRT Digest 3: New colour metrics and their use

2019 ◽  
Vol 51 (5) ◽  
pp. 657-681 ◽  
Author(s):  
PR Boyce ◽  
JR Stampfli
Keyword(s):  
Light Source ◽  
Comprehensive Approach ◽  
Source Spectrum ◽  
Light Sources ◽  
Colour Properties ◽  
Executive Summary ◽  
Colour Temperature ◽  
Test Light ◽  
High Level ◽  
Colour Rendering

Executive summary The two metrics traditionally used to quantify the colour properties of light sources are the correlated colour temperature and the CIE General Colour Rendering Index. With the arrival of LEDs as a major light source questions began to be asked about the merits of both of these metrics. The question asked about correlated colour temperature was how far should the chromaticity of a light source be allowed to depart from the Planckian locus before the light emitted could no longer be said to be white? A tolerance to such a departure ( Duv) already existed but now gathered much more attention. The questions asked about the CIE General Colour Rendering Index were more searching. The limitations of the CIE General Colour Rendering Index were explored and, as a result, several alternative approaches to quantifying the colour rendition properties of light sources were proposed. The most comprehensive approach was produced by the Illuminating Engineering Society of North America, first in its Technical Memorandum IES TM-30-15 and more recently in its revision, Technical Memorandum ANSI/IES TM-30-18, which has been accepted as an American Standard. Both these documents describe a system that contains two high-level summary metrics: One for the average fidelity, i.e. how accurately a test light source renders 99 colour samples relative to how they are rendered under a reference illuminant, and the other for the average colourfulness, i.e. the overall increase or decrease in colourfulness of the same colour samples under the same test light source compared to the same reference illuminant. Associated with these overall average metrics are a number of more detailed metrics and graphical presentations. These aim to quantify and illustrate the variations in fidelity and the direction and magnitude of the shifts in chroma and hue around the hue circle. Compared to the CIE General Colour Rendering Index or the CIE Fidelity Index, a metric published by the CIE in 2017, ANSI/IES TM-30-18 provides a more comprehensive approach to quantifying and understanding the effects of light source spectrum on the perception of colour. Unfortunately, the new colour metrics described in IES TM-30-15 and ANSI/IES TM-30-18 have not yet been accepted by the CIE. Despite this, some light source manufacturers have started to provide information on their products expressed in terms of the ANSI/IES TM-30-18 colour metrics and designers are beginning to request them. The expectation is that, eventually, the ANSI/IES TM-30-18 metrics will be adopted by many countries and authorities, because they provide a much more comprehensive description of the colour properties of a light source than the CIE General Colour Rendering Index. This will be of value to light source manufacturers and lighting designers as well as those who prepare lighting codes and guides. It is expected that in the future the minimum set of data considered acceptable for describing the colour properties of a light source are likely to be the correlated colour temperature and the associated Duv value, the CIE Fidelity Index or the matching ANSI/IES TM-30-18 Fidelity Index, together with the ANSI/IES TM-30-18 Gamut Index and the ANSI/IES TM-30-18 Colour Vector Graphic.

Phototaktische Reaktion von Asplanchna priodonta bei monochromatischem Reizlicht/Phototactic Reactions of Asplanchna priodonta to Monochromatic Light

1979 ◽  
Vol 34 (1-2) ◽  
pp. 148-152 ◽  
Author(s):  
Horst Hertel
Keyword(s):  
Spectral Sensitivity ◽  
Monochromatic Light ◽  
Rapid Decrease ◽  
Sensitivity Curve ◽  
Test Light ◽  
Asplanchna Priodonta ◽  
Light Stimuli ◽  
Spectral Sensitivity Curve ◽  
The Way

Abstract 1. The spectral sensitivity curve of the positive phototactic reaction of the rotifer Asplanchna priodon ta has a triple peak. The maxima lie at 363 nm, 453 nm and 552 nm.2. In the shortest wavelength tested and in the area of 453 to 594 nm was the precision of the phototactic orientation found to be high. In between lies a minimum at 395 nm, above 594 nm occurs a rapid decrease in phototactic orientation.3. No wavelength specific differences in the way of orientation were found when using dif­ ferent monochromatic test light stimuli. This leads the same mixture of photopigments.

The Test Light Affects Quantitation of the Afferent Pupillary Defect

Ophthalmology ◽  
1987 ◽  
Vol 94 (1) ◽  
pp. 53-55 ◽  
Author(s):  
David J. Browning ◽  
James S. Tiedeman
Keyword(s):  
Test Light

Very-long-term chromatic adaptation: Test of gain theory and a new method

2008 ◽  
Vol 25 (3) ◽  
pp. 411-414 ◽  
Author(s):  
SUZANNE C. BELMORE ◽  
STEVEN K. SHEVELL
Keyword(s):  
New Method ◽  
Chromatic Adaptation ◽  
Adaptation Period ◽  
Ambient Illumination ◽  
Long Wavelength ◽  
Room Illumination ◽  
Light Levels ◽  
Test Light ◽  
Adaptation Test

This research had two goals. First, a new method of very-long-term chromatic adaptation was compared to an older method of long-wavelength ambient illumination. In the new method, the observer viewed for 1 h per day for 12 or 14 days a CRT screen composed of oriented lines that appeared red. One observer also replicated a previous procedure (Neitz et al., 2002) in which she was exposed to long-wavelength room illumination for 4 h per day for 14 days. For both methods, equilibrium yellow was measured each day about 20 h after the end of the adaptation period. Both methods of very-long-term chromatic adaptation gave similar results. Second, shifts in equilibrium yellow were measured over a 30:1 range of light levels to determine if changes in color percepts were explained solely by a gain change in cone sensitivities (von Kries coefficient law). The magnitude of shift of equilibrium yellow depended on the level of the test light, which was not consistent with a gain theory of very-long-term chromatic adaptation.

Sign in / Sign up

Export Citation Format

Share Document