PERCEIVED CHROMA AND HUE CHANGES OF COLOURS AT HIGH ILLUMINANCE LEVELS DUE TO HUNT EFFECT

2021 ◽  
Author(s):  
Y. Kawashima ◽  
Y. Ohno
Keyword(s):  
The Other ◽  
Light Levels ◽  
Perception Model ◽  
Vision Experiment ◽  
Indoor Lighting

The purpose of this study is to quantify the Hunt Effect in a range from indoor lighting levels to outdoor daylight levels so that a perception model of Hunt Effect for lighting can be developed with outdoor daylight as the reference. Our previous study experimentally quantified the perceived chroma changes due to the Hunt Effect at 100 lx and 1000 lx. To extend this to light levels closer to outdoor daylight, a vision experiment was conducted at ≈1000 lx and ≈6000 lx for red, green, yellow, and blue patches. A reference patch on one side of a double booth at 1000 lx was compared to a set of 20 test patches on the other side of the booth at ≈6000 lx using haploscopic view condition. Results showed that the perceived chroma changes are much smaller and insignificant compared to the results between 100 lx and 1000 lx found in our previous study.

scholarly journals Chromatic discrimination in the presence of incremental and decremental rod pedestals

2008 ◽  
Vol 25 (3) ◽  
pp. 399-404 ◽  
Author(s):  
DINGCAI CAO ◽  
ANDREW J. ZELE ◽  
JOEL POKORNY
Keyword(s):  
The Other ◽  
Light Levels

Signals from rods can alter chromatic discrimination. Here, chromatic discrimination ellipses were determined in the presence of rod incremental and decremental pedestals at mesopic light levels. The data were represented in a relative cone Troland space, normalized by discrimination thresholds measured along the cardinal axes without a rod pedestal. In the quadrant of cone space where L-cone relative to M-cone excitation increased, and S-cone excitation decreased, rod incremental pedestals degraded chromatic discrimination, and rod decremental pedestals improved chromatic discrimination. Discrimination in the other three quadrants of cone space was unaffected by the incremental or decremental rod pedestals. A second experiment measured chromatic discrimination under conditions where cone pedestals were matched to the appearances of the incremental and decremental rod pedestals. Based on the matching pedestal data, discrimination then could be measured independently along the cardinal axes using either chromatic [L/(L + M); S/(L + M)] or luminance (L + M) pedestal components. The discrimination data altered by the rod pedestals were similar to chromatic cone pedestals for L/M increment discrimination, but similar to luminance cone pedestals for S decrement discrimination. The results indicated that the rod and cone signals combined differently in determining chromatic discrimination for different post-receptoral pathways.

scholarly journals 018 EFFECTS OF ANCYMIDOL, PACLOBUTRAZOL, AND UNICONAZOLE ON GROWTH AND FLOWERING OF ACHIMENES cv HILDA UNDER TWO LIGHT LEVELS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 430b-430
Author(s):  
J. C. Vlahos
Keyword(s):  
Plant Height ◽  
Light Level ◽  
The Other ◽  
Growth Retardants ◽  
Axillary Shoots ◽  
Full Sunlight ◽  
Foliar Sprays ◽  
Light Levels ◽  
Mode Of Application ◽  
Reduced Light

Plants of Achimenes cv Hilda were treated with foliar sprays of Ancymidol, Paclobutrazol and Uniconazole at 3 different concentrations each, and were placed in a greenhouse at 21°C under 2 light levels (0 and 40% light exclusion) for 12 weeks. Reduced light level decreased plant height, number of axillary shoots and flowers. The three growth retardants in any concentration, supressed development of axillary shoots and flowers. Ancymidol at 25 and 50 mg.1-1, Uniconazole at 5 mg.1-1 and Paclobutrazol at 25, 50 or 100 mg.1-1 decreased plant height and number of leaf whorls. Number of rhizomes was reduced by the 3 chemicals at the highest concentration only. Paclobutrazol was most effective than the other 2 growth retardants. Effects of treatments were more pronounced under shade rather than in full sunlight. Days to anthesis was not affected by any of the treatments except by Paclobutrazol at 100 mg.1-1. The use of these growth retardants in concentration and mode of application similar to those used in this study is not recommended for “Hilda” as height retardation significantly reduces number of flowers

scholarly journals Antagonistic Components of the Late Receptor Potential in the Barnacle Photoreceptor Arising from Different Stages of the Pigment Process

1973 ◽  
Vol 62 (1) ◽  
pp. 105-128 ◽  
Author(s):  
S. Hochstein ◽  
B. Minke ◽  
P. Hillman
Keyword(s):  
Strong Dependence ◽  
Red Light ◽  
Receptor Potential ◽  
Photoreceptor Cells ◽  
The Other ◽  
Light Levels ◽  
Early Receptor Potential ◽  
Late Receptor Potential ◽  
A Cell ◽  
532 Nm

The late receptor potential (LRP) recorded in barnacle photoreceptor cells exhibits, at high light levels, a strong dependence on the color of the stimulus and of the preceding adaptation. Most strikingly, red illumination of a cell previously adapted to blue light results in a depolarization which may last for up to 30 min after the light goes off, while blue illumination of a cell previously adapted to red light cuts short this extended depolarization or prevents its induction by a closely following red light. Comparison of the action spectra for the stimulus-coincident LRP and for the extended depolarization and its curtailment with those previously measured for the early receptor potential (ERP) confirms that these phenomena derive from the same bi-stable pigment as the ERP. The stimulus-coincident response and the extended depolarization appear to arise from substantial activation of the stable 532 nm state of the pigment, while activation of the stable 495 state depresses or prevents the extended depolarization and probably also depresses the stimulus-coincident response. Since either process can precede the other, with mutually antagonistic effects, one is not simply the reversal of the other; they must be based on separate mechanisms. Furthermore, comparison with ERP kinetics shows that both processes involve mechanisms additional to the pigment changes, as seen in the ERP. A model is proposed and discussed for the LRP phenomena and their dependences on wavelength, intensity, and duration of illumination based on excitor-inhibitor interactions.

Understanding Older Adults’ Perception and Usage of Indoor Lighting in Independent Senior Living

2021 ◽  
pp. 193758672098861
Author(s):  
Daejin Kim ◽  
Carl Chang ◽  
Jennifer Margrett
Keyword(s):  
Older Adults ◽  
Successful Aging ◽  
Well Being ◽  
Vision Impairment ◽  
Retirement Community ◽  
Smart Devices ◽  
Lighting Condition ◽  
Smart Lighting ◽  
Light Levels ◽  
Indoor Lighting

The main purpose of this research is to examine the lighting condition and residents’ perception of lighting in a senior retirement community in order to understand various environmental issues related to lighting. Also, this research aims to suggest a new lighting solution to compensate for older adults’ vision impairment and challenges at home for a successful aging place. In the normal aging process, more than 30% of older adults have a vision impairment, which negatively affects health and well-being of older adults such as limited activities, falling, loneliness, depression, anxiety, and a sense of control. Via a mixed method study design, residents in senior living communities were asked to describe the adequacy of light levels and specific tasks and needs related to lighting at their home. In addition to the survey and interview, indoor lighting assessments were conducted during the in-home session. The research findings highlighted older adults’ experience and perception of lighting in their homes. Paired-sample t test indicated that there were statistically significant differences in light levels between normal conditions and full capacity conditions in all spaces. In order to address various challenges which older adults have been experiencing in their home for a long time, this research suggests new smart lighting platform which provides a proper level of illumination in older adult’s homes. Such a smart platform is proactive and can dynamically adjust the smart devices or lighting fixtures in situ, while older adults are performing certain tasks.

scholarly journals Color, activity period, and eye structure in four lineages of ants: pale, nocturnal species have evolved larger eyes and larger facets than their dark, diurnal congeners

2021 ◽  
Author(s):  
Robert A. Johnson ◽  
Ronald L. Rutowski
Keyword(s):  
Visual Acuity ◽  
Activity Pattern ◽  
The Other ◽  
Activity Period ◽  
Low Light ◽  
Size Dependent ◽  
Light Levels ◽  
Nocturnal Species ◽  
The Difference ◽  
Diurnal Species

The eyes of insects display an incredible diversity of adaptations to enhance vision across the gamut of light levels that they experience. One commonly studied contrast is the difference in eye structure between nocturnal and diurnal species, with nocturnal species typically having features that enhance eye sensitivity such as larger eyes, larger eye facets, and larger ocelli. In this study, we compared eye structure between workers of closely related nocturnal and diurnal above ground foraging ant species (family Formicidae) in four genera (Myrmecocystus, Aphaenogaster, Temnothorax, Veromessor). In all four genera, nocturnal species tend to have little cuticular pigment (pale), while diurnal species are fully pigmented (dark), hence we could use cuticle coloration as a surrogate for activity pattern. Across three genera (Myrmecocystus, Aphaenogaster, Temnothorax), pale species, as expected for nocturnally active animals had larger eyes, larger facet diameters, and larger visual spans compared to their dark, more day active congeners. This same pattern occurred for one pale species of Veromessor, but not the other. There were no consistent differences between nocturnal and diurnal species in interommatidial angles and eye parameters both within and among genera. Hence, the evolution of eye features that enhance sensitivity in low light levels do not appear to have consistent correlated effects on features related to visual acuity. A survey across several additional ant genera found numerous other pale species with enlarged eyes, suggesting these traits evolved multiple times within and across genera. We also compared size of the anterior ocellus in workers of pale versus dark species of Myrmecocystus. In species with larger workers, the anterior ocellus was smaller in pale than in dark species, but this difference mostly disappeared for species with smaller workers. Presence of the anterior ocellus also was size-dependent in the two largest pale species.

Legibility of Numbers as a Function of Contrast and Illumination

1967 ◽  
Vol 9 (5) ◽  
pp. 455-460 ◽  
Author(s):  
Charles M. Williams
Keyword(s):  
Reaction Time ◽  
Short Duration ◽  
Relative Position ◽  
Reaction Times ◽  
Important Variable ◽  
The Other ◽  
Stimulus Array ◽  
White Background ◽  
Light Levels ◽  
Speed And Accuracy

While contrast is recognized as an important variable affecting legibility, scant information of what happens in the mid-ranges is available. Thus nine contrast conditions consisting of black or white lettering on white, black, or grey backgrounds were compared under three levels of illumination —0.06, 0.60, and 6.0 footcandles. 18 Ss were asked to search a stimulus array for a particular stimulus and then indicate its relative position among the other stimuli. Reaction time and errors were recorded. Illumination proved to be the single most important factor. Significant differences in performance were observed between the contrast conditions under poor illumination. It was concluded that for recognition tasks of short duration, varying contrast within wide limits has little effect on speed and accuracy of performance as long as illumination remains above 0.60 footcandles. Black lettering on a white background and white lettering on a black background did not differ significantly and were associated with the shortest reaction times and the least number of errors at all light levels.

scholarly journals The Effects of Depth-Related Environmental Factors on Traits in Acropora cervicornis Raised in Nurseries

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 212
Author(s):  
Claudia Patricia Ruiz-Diaz ◽  
Carlos Toledo-Hernández ◽  
Juan Luis Sánchez-González ◽  
Brenda Betancourt
Keyword(s):  
Global Climate Change ◽  
Global Climate ◽  
Seawater Temperature ◽  
The Other ◽  
Acropora Cervicornis ◽  
Light Levels ◽  
Survival And Growth ◽  
The Caribbean ◽  
Slight Advantage

Populations of Acropora cervicornis, one of the most important reef-building corals in the Caribbean, have been declining due to human activities and global climate change. This has prompted the development of strategies such as coral farms, aimed at improving the long-term viability of this coral across its geographical range. This study focuses on comprehending how seawater temperature (ST), and light levels (LL) affect the survival and growth of A. cervicornis fragments collected from three reefs in Culebra, Puerto Rico. These individuals were fragmented into three pieces of the similar sizes and placed in farms at 5, 8, and 12 m depth. The fragments, ST and LL were monitored for 11 months. Results show that fragments from shallow farms exhibit significantly higher mortalities when compared to the other two depths. Yet, growth at shallow farms was nearly 24% higher than at the other two depths. Corals grew fastest during winter, when temperature and LL were lowest, regardless of the water depth. Fragment mortality and growth origin were also influenced by reef origin. We conclude that under the current conditions, shallow farms may offer a slight advantage over deep ones provided the higher growth rate at shallow farms and the high fragment survival at all depths.

White Appearance for Optimal Text-Background Lightness Combination Document Layout on a Tablet Display under Normal Light Levels

2021 ◽  
Vol 2021 (29) ◽  
pp. 188-192
Author(s):  
Huang Hsin-Pou ◽  
Li Hung-Chung ◽  
Wei Minchen ◽  
Huang Yu-Cheng
Keyword(s):  
The Other ◽  
Visual Comfort ◽  
Light Levels ◽  
Other Hand ◽  
Document Layout ◽  
Normal Light

In the study, two psychophysical experiments are carried out to understand the visual comfort and white appearance of a tablet display. Twenty-four observers assess the visual comfort of document layouts, and eleven observers rate the whiteness percentage of the stimulus under normal light levels with a CCT of 6500 K. The result of the experiment for visual comfort indicates that a combination of black text with a light grey background presents the better visual comfort. On the other hand, the finding of the white appearance experiment shows that the observers rate the stimulus with CCT of 6515 K and a Duv of 0 as the whitest.

scholarly journals Spread of Risk Information Through Microblogs: Twitter Users with More Mutual Connections Relay News That is More Dreadful

2019 ◽  
Author(s):  
Masashi Komori ◽  
Asako Miura ◽  
Naohiro Matsumura ◽  
Kai Hiraishi ◽  
Kazutoshi Maeda
Keyword(s):  
Information Exchange ◽  
Risk Information ◽  
High Ratio ◽  
The Other ◽  
Network Information ◽  
Perception Model ◽  
Social Sharing ◽  
Twitter Users ◽  
Network Information Exchange ◽  
Transmission Pathways

In elucidating the spread of risk information through microblogging, it is important to understand the behaviors of numerous average users, in addition to the activities of authorities. We followed the transmission pathways of 10 actual widely spread tweets concerning several risk information topics, including natural disasters, nuclear disasters, and infectious diseases, and we identified the types of risk that affected retweeting by classifying each tweet based on Slovic’s risk perception model. Furthermore, we examined the types of users who did and did not retweet the information. Users with few connections in the form of followers (i.e., people who are following a user) or followees (people a user is following), or with a low ratio of mutual followers within their connections, had a tendency to retweet a large amount of risk information, regardless of the type of risk involved. On the other hand, users with a high ratio of mutual followers exhibited a greater tendency to retweet risk information when it was perceived as dreadful, though they did not retweet risk information much on the whole. These results suggest that there are two mechanisms by which risk information is spread within the Twitter network: information exchange and social sharing of personal reactions.

Stromatoporoids from the Famennian (Devonian) Wabamun Formation, Normandville oilfield, north–central Alberta, Canada

1988 ◽  
Vol 62 (03) ◽  
pp. 411-419 ◽  
Author(s):  
Colin W. Stearn
Keyword(s):  
Patch Reef ◽  
Abundant Species ◽  
The Other ◽  
North Central ◽  
Biotic Crisis

Stromatoporoids are the principal framebuilding organisms in the patch reef that is part of the reservoir of the Normandville field. The reef is 10 m thick and 1.5 km2in area and demonstrates that stromatoporoids retained their ability to build reefal edifices into Famennian time despite the biotic crisis at the close of Frasnian time. The fauna is dominated by labechiids but includes three non-labechiid species. The most abundant species isStylostroma sinense(Dong) butLabechia palliseriStearn is also common. Both these species are highly variable and are described in terms of multiple phases that occur in a single skeleton. The other species described areClathrostromacf.C. jukkenseYavorsky,Gerronostromasp. (a columnar species), andStromatoporasp. The fauna belongs in Famennian/Strunian assemblage 2 as defined by Stearn et al. (1988).

Sign in / Sign up

Export Citation Format

Share Document