Effect of Ambient Lighting on Frequency Dependence in Transcranial Electrical Stimulation-Induced Phosphenes

2021 ◽  
Author(s):  
Ian Evans ◽  
Stephen Palmisano ◽  
Rodney J. Croft
Keyword(s):  
Frequency Dependence ◽  
Quadratic Function ◽  
Linear Increase ◽  
Stimulation Frequency ◽  
Transcranial Electrical Stimulation ◽  
Lighting Condition ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Phosphene Threshold ◽  
Within Subjects

Abstract Inconsistencies have been found in the relationship between ambient lighting conditions and frequency-dependence in transcranial electric current stimulation (tECS) induced phosphenes. Using a within-subjects design across lighting condition (dark, mesopic [dim], photopic [bright]) and tECS stimulation frequency (10, 13, 16, 18, 20 Hz), this study determined phosphene detection thresholds in 24 subjects receiving tECS using an FPz-Cz montage. Minima phosphene thresholds were found at 16 Hz in mesopic, 10 Hz in dark and 20 Hz in photopic lighting conditions, with these thresholds being substantially lower for mesopic than both dark (60% reduction) and photopic (56% reduction), conditions. Further, whereas the phosphene threshold-stimulation frequency relation was linear in the dark (increasing with frequency) and photopic (decreasing with frequency) conditions, a quadratic function was found for the mesopic condition (where it followed the linear increase of the dark condition from 10-16 Hz, and the linear decrease of the photopic condition from 16-20 Hz). The results clearly demonstrate that ambient lighting is an important factor in the detection of tECS-induced phosphenes, and that mesopic conditions are most suitable for obtaining overall phosphene thresholds.

Modelling incomplete chromatic adaptation on a display under different ambient illuminations

2019 ◽  
Vol 2019 (1) ◽  
pp. 231-236
Author(s):  
Rui Peng ◽  
Ming Ronnier Luo ◽  
Mingkai Cao
Keyword(s):  
Lower Degree ◽  
Chromatic Adaptation ◽  
White Background ◽  
Color Stimulus ◽  
Lighting Condition ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Illuminance Level ◽  
Adaptation Factor

The purposes of this study was to investigate the chromatic adaptation and adaptive whites on a display under various ambient lighting conditions with different chromaticity and illuminance. An image including black text and white background was rendered by means of the CAT02 chromatic adaptation transform, into 42 different white stimuli varying at 6 CCTs and 7 Duv levels. Twenty observers assessed the neutral white evaluations of each color stimulus via psychophysical experiments. The optimization based on the neutral white stimulus under each ambient lighting condition suggested a lower degree of chromatic adaptation under the conditions with a lower CCT and a lower illuminance level. The results were used to model the adaptive display white and the incomplete adaptation factor (D) for CAT02 under different ambient illumiantions.

Flight By Periscope: Making Takeoffs and Landings; The Influence of Image Magnification, Practice, and Various Conditions of Flight

1966 ◽  
Vol 8 (1) ◽  
pp. 13-40 ◽  
Author(s):  
Stanley N. Roscoe ◽  
Scott G. Hasler ◽  
Dora J. Dougherty
Keyword(s):  
Image Magnification ◽  
Flight Experience ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Experience Effects ◽  
Detailed Determination ◽  
Accuracy Speed

The proficiency with which pilots can make takeoffs and landings using a periscope as the only source of outside visibility was studied under various conditions of flight. A detailed determination was made of the effects of variations in image magnification upon landing accuracy. Speed of transition to flight by periscope was related to flight experience. Effects of various weather, runway surface, and ambient lighting conditions upon flight by periscope were investigated.

A Practical Tool for Ambient Illumination Comparisons at Dusk/Dawn

2016 ◽  
Vol 60 (1) ◽  
pp. 470-474 ◽  
Author(s):  
Hilary Lam ◽  
Sayf Gani ◽  
Randy Mawson ◽  
Jason Young ◽  
Erin Potma
Keyword(s):  
Human Perception ◽  
Time Lapse ◽  
Time Of Day ◽  
Ambient Illumination ◽  
Adjustment Factor ◽  
Lighting Conditions ◽  
Accurate Knowledge ◽  
Ambient Lighting ◽  
Practical Tool ◽  
Sky Conditions

Nighttime visibility is an important consideration in collision reconstruction and personal injury investigation. Decreased contrast in low ambient lighting conditions can greatly affect human perception and response. Because ambient lighting levels change rapidly at dawn and dusk, forensic investigators must have an accurate knowledge of the time of day and the cloud conditions at the time of the incident before initiating a nighttime visibility assessment. Previously, human factors experts attempting re-enactments at dawn or dusk have had to wait for sky conditions that match those at the time of the incident, making the investigation of those cases extremely difficult, if not unfeasible. In this study, an ambient illumination equivalency tool has been developed based on a database of time-lapse light meter readings collected by the authors. This new tool can be used to facilitate nighttime visibility assessments on any day by providing a time adjustment factor to account for the changes in ambient illuminance due to differences in the cloud conditions between the day of the incident and the day of the re-enactment.

scholarly journals Software package for testing three-dimensional shape measurement methods using structured lighting

2021 ◽  
Vol 2057 (1) ◽  
pp. 012087
Author(s):  
S V Dvoynishnikov ◽  
V O Zuev ◽  
I K Kabardin ◽  
D V Kulikov ◽  
V V Rahmanov
Keyword(s):  
Software Package ◽  
Three Dimensional ◽  
Measurement Methods ◽  
Shape Measurement ◽  
Structured Lighting ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Dimensional Shape ◽  
Shadow Maps ◽  
Three Dimensional Shape

Abstract This work aims at creating a universal software package for the development and testing of triangulation methods using structured lighting for measuring the three-dimensional geometry of objects in difficult ambient lighting conditions. As a result, a software package meeting the stated requirements is created. Lighting is based on the Fong model. A method for preloading objects is implemented to optimize the operation of the software package. An accelerated method for creating shadow maps is proposed and implemented. The developed software package is shown to successfully perform all required functions.

Clinical Study of the Influence of Ambient Lighting Conditions on the Mesh Quality of an Intraoral Scanner

2020 ◽  
Vol 29 (8) ◽  
pp. 651-655 ◽  
Author(s):  
Marta Revilla‐León ◽  
Sai Ganesh Subramanian ◽  
Mutlu Özcan ◽  
Vinayak Raman Krishnamurthy
Keyword(s):  
Clinical Study ◽  
Mesh Quality ◽  
Intraoral Scanner ◽  
Lighting Conditions ◽  
Ambient Lighting

The relationship between ambient lighting conditions, absolute dark-adapted thresholds, and rhodopsin in black and hypopigmented mice

2004 ◽  
Vol 21 (6) ◽  
pp. 925-934 ◽  
Author(s):  
GERARD H. DALY ◽  
JESSICA M. DILEONARDO ◽  
NATALIE R. BALKEMA ◽  
GRANT W. BALKEMA
Keyword(s):  
Bright Light ◽  
Visual Sensitivity ◽  
Segment Length ◽  
Single Strain ◽  
Photoreceptor Layer ◽  
Lighting Conditions ◽  
Ambient Lighting ◽  
Dim Light ◽  
Albino Mice ◽  
The Relationship

Significant variation in absolute dark-adapted thresholds is observed both within and between strains of mice with differing ocular pigmentation levels. Differences in threshold within a single strain are related to the Williams' photostasis effect, that is, photoreceptor rhodopsin levels are dependent upon ambient lighting conditions. To examine threshold differences among strains, we equalized rhodopsin levels by maintaining albino mice (c2J/c2J) at 2 × 10−4 cd/m2 (dim light) and black mice at 2 × 102 cd/m2 (bright light). This resulted in ocular rhodopsin levels for albino mice (albino—dim) of 494 ± 11 pmoles/eye and rhodopsin levels for black mice (black—bright) of 506 ± 25 pmoles/eye. For comparison, rhodopsin levels in black mice maintained in dim light are 586 ± 46 pmoles/eye and 217 ± 46 pmoles/eye in albino mice maintained in bright light. We found similar dark-adapted thresholds (6.38 log cd/m2vs. 6.47 log cd/m2)) in albino and black mice with equivalent rhodopsin determined with a water maze test. This suggests that dark-adapted thresholds are directly related to rhodopsin levels regardless of the level of ocular melanin. The number of photoreceptors, photoreceptor layer thickness, and outer segment length did not differ significantly between albino (dark) and black mice (bright). These results demonstrate that the visual sensitivity defect found in hypopigmented animals is secondary to abnormal rhodopsin regulation and that hypopigmented animals have either an improper input to the photostasis mechanism or that the photostasis mechanism is defective.

scholarly journals Intellectual productivity under task ambient lighting

2016 ◽  
Vol 50 (2) ◽  
pp. 237-252 ◽  
Author(s):  
H Ishii ◽  
H Kanagawa ◽  
Y Shimamura ◽  
K Uchiyama ◽  
K Miyagi ◽  
...  
Keyword(s):  
Objective Evaluation ◽  
Average Concentration ◽  
Cognitive Tasks ◽  
Colour Temperature ◽  
Time Ratio ◽  
Lighting Conditions ◽  
Concentration Time ◽  
Ambient Lighting ◽  
Normal Colour ◽  
Intellectual Productivity

An experiment was conducted to evaluate intellectual productivity in three lighting conditions: (a) conventional ambient lighting, (b) task ambient lighting with normal colour temperature (5000 K) and (c) task ambient lighting with high colour temperature (6200 K). In the experiment, cognitive tasks were given to 24 participants. The concentration time ratio, which is a quantitative and objective evaluation index of the degree of concentration, was measured. The results showed that the average concentration time ratio under the task ambient lighting with high colour temperature was 72.5%, which was 5.0% points higher than that under the conventional ambient lighting. It is believed that intellectual work can be performed better when the concentration time ratio is high.

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