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At least 19 recordsLinked to original sources
PubMed2002

Preference and motivation of laying hens to eat under different illuminances and the effect of illuminance on eating behaviour.

1. In experiment 1, 10 laying hens were given the choice to eat food pellets from any of 4 food bowls illuminated by overhead, incandescent luminaires at <1, 6, 20 or 200 lux. During a trial hens were allowed to eat for 5 min. After each minute had elapsed (from the start of eating) the light sources were extinguished and the illuminances re-assigned to the food bowls in a random manner. Each hen received two trials, one where the food was freely available and another where it was hidden in a sand and gravel mix. 2. The hens chose to eat for most time in the brightest (200 lux) and least in the dimmest (<1 lux) environments for both free and hidden food (free: 5.9, 10.5, 10.4, 15.7s for increasing illuminance; Hidden: 5.5, 9.8, 9.1 and 15.7s. 3. In experiment 2, 9 hens were trained to peck at either an illuminated or unilluminated panel to access a food reward behind a guillotine door for 3 s. Five hens were trained to peck the illuminated panel to access food brightly lit (200 lux) or the unilluminated panel to access food dimly lit (<1 lux); 4 hens were trained vice versa. The flock was then divided into three groups of three, and three treatments imposed on each group in a Latin-square arrangement. In treatment 1, one peck at either panel allowed access to the chosen light environment (F1:F1). In treatment 2, 5 pecks were required to access food brightly lit on a variable ratio, but only one to access food dimly lit (ratio V5:F1). In treatment 3, the variable ratio was increased to V10:F1 to access food in the light. 4. Over 40 trials for each hen, the mean number of attempts to eat food in the light (where the panel which allowed access to food brightly lit was pecked at least once) was 34.5 for F1:F1, 12.1 for V5:F1 and 8.5 for V10:F1. The mean number of food rewards taken in bright light was 34.5, 3.1 and 1.8, respectively. For both variables, the difference between F1:F1 and V5:F1 was significant but not between V5:F1 and V10:F1. By interpolation of the 'attempts' data, it was estimated that hens would work 2.3 times harder to gain access to food brightly lit than for food dimly lit. 5. In experiment 3, the influence of the same illuminances applied over a food bowl as in experiment 1 (<1, 6, 20 or 200 lux) on the number of pecks/min, food consumed/min, food consumed/peck and the force of pecks was examined. 6. The amount of food consumed was lowest in the dimmest environment (3.1 vs 7.5, 7.4 and 7.1 g/ min for increasing illuminance, respectively); as was the number of pecks (35.6 vs. 125.0, 123.1, and 125.4 pecks/min respectively for increasing illuminance). The amount consumed per peck did not vary significantly with illuminance. The mean peck force showed a trend to be lowest in the dimmest environment (5.3 vs. 6.6, 7.0 and 6.6 N respectively, for increasing illuminance). 7. Overall, the hens showed a preference and appeared motivated to eat in bright as opposed to dim light. The hens were unwilling to eat at low illuminances although the 'efficiency' of eating (g/peck) was not impaired significantly. These data may have implications for novel lighting systems and those where hens are required to eat in the dark or in very dim light.

Animal Feed↗
PubMed2003

Surface color perception under two illuminants: the second illuminant reduces color constancy.

This study investigates color perception in a scene with two different illuminants. The two illuminants, in opposite corners, simultaneously shine on a (simulated) scene with an opaque dividing wall, which controls how much of the scene is illuminated by each source. In the first experiment, the height of the dividing wall was varied. This changed the amount of each illuminant reaching objects on the opposite side of the wall. Results showed that the degree of color constancy decreased when a region on one side of the wall had cues to both illuminants, suggesting that cues from the second illuminant are detrimental to color constancy. In a later experiment, color constancy was found to improve when the specular highlight cues from the second illuminant were altered to be consistent with the first illuminant. This corroborates the influence of specular highlights in surface color perception, and suggests that the reduced color constancy in the first experiment is due to the inconsistent, though physically correct, cues from the two illuminants.

Color Perception↗
PubMed2000

Characterization of natural illuminants in forests and the use of digital video data to reconstruct illuminant spectra.

We describe illumination spectra in forests and show that they can be accurately recovered from recorded digital video images. Natural illuminant spectra of 238 samples measured in temperate forests were characterized by principal-component analysis. The spectra can be accurately approximated by the mean and the first two principal components. Compared with illumination under open skies, the loci of forest illuminants are displaced toward the green region in the chromaticity plots, and unlike open sky illumination they cannot be characterized by correlated color temperature. We show that it is possible to recover illuminant spectra accurately from digital video images by a linear least-squares-fit estimation technique. The use of digital video data in spectral analysis provides a promising new approach to the studies of the spatial and temporal variation of illumination in natural scenes and the understanding of color vision in natural environments.

Color↗
PubMed1988

ATP formation onset lag and post-illumination phosphorylation initiated with single-turnover flashes. II. Two modes of post-illumination phosphorylation driven by either delocalized or localized proton gradient coupling.

Two modes of chloroplast membrane post-illumination phosphorylation were detected, using the luciferin-luciferase ATP assay, one of which was not influenced by added permeable buffer (pyridine). That finding provides a powerful new tool for studying proton-membrane interactions during energy coupling. When ADP and Pi were added to the thylakoid suspension after a train of flashes [similar to the traditional post-illumination phosphorylation protocol (termed PIP- here)], the post-illumination ATP yield was influenced by pyridine as expected, in a manner consistent with the ATP formation, in part, being driven by protons present in the bulk inner aqueous phase, i.e., through a delocalized protonmotive force. However, when ADP and Pi were present during the flash train (referred to as PIP+), and ATP formation occurred during the flash train, the post-illumination ATP yield was unaffected by the presence of pyridine, consistent with the hypothesis that localized proton gradients were driving ATP formation. To test this hypothesis further, the pH and flash number dependence of the PIP- and PIP+ ATP yields were measured, the results being consistent with the above hypothesis of dual compartment origins of protons driving post-illumination ATP formation. Measuring proton accumulation during the attainment of the threshold energization level when no delta psi component was allowed to form (+ valinomycin, K+), and testing for pyridine effects on the proton uptake, reveals that the onset of ATP formation requires the accumulation of about 60 nmol H+ (mg Chl)-1. Between that level and about 110-150 nmol H+ (mg Chl)-1, the accumulation appears to be absorbed by localized-domain membrane buffering groups, the protons of which do not equilibrate readily with the inner aqueous (lumen) phase. Post-illumination phosphorylation driven by the dissipation of the domain protons was not affected by pyridine (present in the lumen), even though the effective pH in the domains must have been well into the buffering range of the pyridine. That finding provides additional insight into the localized domains, namely that protons can be absorbed by endogenous low pK buffering groups, and released at a low enough pH (less than or equal to 5.7 when the external pH was 8, less than or equal to 4.7 at pH 7 external) to drive significant ATP formation when no further proton production occurs due to the redox turnovers.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1992

The True Daylight Illuminator (TDI): a less expensive source of illumination for color vision screening.

This experiment was designed to examine the feasibility of using the True Daylight Illuminator (TDI) as an illumination option for conducting color vision screening with the Ishihara Test(s). The MacBeth Easel Lamp was designed to provide proper illumination for performing color vision screening with a variety of pseudoisochromatic (PIC) plate tests including the Ishihara. However, over the years, the MacBeth Lamp has become so expensive that many smaller programs cannot afford to purchase one. This problem has promoted the use of alternate light sources that have had a deleterious effect on test results and in some instances contributed to job discrimination. Recently the MacBeth Division of the Kollmorgan Corporation discontinued the manufacture of the MacBeth Lamp due to lack of demand. Thus, it is important to find an inexpensive illumination option for conducting color vision screening. Two groups of subjects were used to compare test results for the 24-plate edition of the Ishihara Test using both the MacBeth Lamp and the True Daylight Illuminator. The first group contained 45 subjects with inherited color defective vision. The second group was made up of 30 color normals. The Nagel anomaloscope was used to confirm the color vision status of the subjects in both groups. Statistics to test the significance of differences between group means clearly demonstrated that there were no significant differences between the mean error scores of the two groups for these two pieces of equipment. Thus, it was concluded that the TDI can be used in lieu of the MacBeth Easel Lamp for screening color vision with the Ishihara test.

Adolescent↗
PubMed1992

Survival strategies of plasmid-carrier and plasmidless Escherichia coli strains under illuminated and non-illuminated conditions, in a fresh water ecosystem.

A comparative study, in illuminated and non-illuminated systems, was made to determine the survival strategies of plasmid-carrier and plasmidless bacteria in sterile river water. Two strains of Escherichia coli from river water were selected: one plasmidless, EC1, and one antibiotic-resistant strain, EC7, which showed plasmid bands. By matings with EC7 as donor and E. coli K12 strain J62 as recipient, transconjugants were generated, the J62(7) strain, which showed both antibiotic resistance and plasmid bands. Ethidium bromide curing of the EC7 strain generated the EC7(2) strain which showed a partial loss of resistance and a reorganization of plasmid bands. Under non-illuminated conditions the total number of cells detected by direct count and the number of culturable cells (injured and non-injured cells) remained practically constant throughout the period of incubation. In the illuminated systems, however, the number of cfu decreased in four of the five strains studied. The greatest decreases are those of the J62 strain, followed by those of the J62(7), EC1, EC7(2) and EC7 strains. Differences in survival strategies as a consequence of the presence or absence of plasmids are discussed.

Colony Count, Microbial↗
PubMed1988

ATP formation onset lag and post-illumination phosphorylation initiated with single-turnover flashes. III. Characterization of the ATP formation onset lag and post-illumination phosphorylation for thylakoids exhibiting localized or bulk-phase delocalized energy coupling.

When 100 mM KCl replaced sucrose in a chloroplast thylakoid stock suspension buffer, the membranes were converted from a localized proton gradient to a delocalized proton gradient energy coupling mode. The KCl-suspended but not the sucrose-suspended thylakoids showed pyridine-dependent extensions of the ATP onset lag and pyridine effects on post-illumination phosphorylation. The ATP formation assays were performed in a medium of identical composition, using about a 200-fold dilution of the stock thylakoid suspension; hence the different responses were due to the pretreatment, and not the conditions present in the phosphorylation assay. Such permeable buffer effects on ATP formation provide a clear indicator of delocalized proton gradients as the driving force for phosphorylation. The pyridine-dependent increases in the onset lags (and effects on post-illumination phosphorylation) were not due to different ionic conductivities of the membranes (measured by the 515 nm electrochromic absorption change), H+/e- ratios, or electron transport capacities for the two thylakoid preparations. Thylakoid volumes and [14C]pyridine equilibration were similar with both preparations. The KCl-induced shift toward a bulk-phase delocalized energy coupling mode was reversed when the thylakoids were placed back in a low-salt medium. Proton uptake, at the ATP-formation energization threshold flash number, was much larger in the KCl-treated thylakoids and they also had a longer ATP formation onset lag, when no pyridine was present. These results are consistent with the salt treatment exposing additional endogenous buffering groups for interaction with the proton gradient. The concomitant appearance of the pyridine buffer effects implies that the additional endogenous buffering groups must be located on proteins directly exposed in the aqueous lumen phase. Kinetic analysis of the decay of the post-illumination phosphorylation in the two thylakoid preparations showed different apparent first-order rate constants, consistent with there being two different compartments contributing to the proton reservoirs that energize ATP formation. We suggest that the two compartments are a membrane-phase localized compartment operative in the sucrose-treated thylakoids and the bulk lumen phase into which protons readily equilibrate in the KCl-treated thylakoids.

Adenosine Triphosphate↗
PubMed1997

Study on illuminance and visual properties of flammable illumination.

In order to investigate the physical, economical, physiological and psychological aspects regarding ancient lighting, two series of experiment were performed. At first a darkroom (1.3 x 4.5 m, Ht: 2.7 m) was constructed. In experiment I, illuminance and consumption rate of fuel were measured. The Japanese classic candle, plant oil and animal fat yield 1.12, 0.30-0.62 and 0.05 lux at 1.0 m distance, respectively. The illuminance was reduced to about 50% by and on which was a lighting tool of folkcraft. The burning duration of plant oil was about two weeks to 180 ml when it burned 4 hours per one day. In experiment II, 15 young females were examined regarding the visual properties such as visual acuity, readability of newspaper and discrimination of color under the simulated illumination of candle. The visual acuity was 0.42 under 0.16 lux. It needed more than 1.44 lux to read a newspaper. In the color discrimination test, yellowish green was most difficult, silver or long wave range colors were easy.

Adult↗
PubMed2002

Environmental remediation by an integrated microwave/UV illumination technique. 3. A microwave-powered plasma light source and photoreactor to degrade pollutants in aqueous dispersions of TiO2 illuminated by the emitted UV/visible radiation.

The characteristic features of a novel double-quartz cylindrical plasma photoreactor (DQCPP) were assessed by examining the photodegradation of rhodamine-B dye (RhB+) in aqueous TiO2 dispersions irradiated simultaneously by both microwave radiation and UV/visible radiation emitted from a microwave-powered (MW, 2.45 GHz) electrodeless mercury lamp. The features of the DQCPP lamp are given and discussed in terms of the experimental output UV energy in the wavelength ranges 210-300 and 310-400 nm for applied MW powers from 74 to 621 W. The DQCPP and a water-cooled DQCPP reactor absorbed more than 50% MW radiation (50-88 and 50-75%, respectively). The emitted light irradiance scaled sublinearly with applied MW power. Relative to the DQCPP lamp, loss of irradiance by the water-cooled DQCPP lamp was approximately 28-46% at 250 nm and approximately 41-58% at 360 nm in the range of MW power used. The smallest loss occurred at 178.9 W at which the degradation of RhB+ was subsequently examined by UV/visible spectroscopy and by total organic carbon analyses. Highly intense mercury lines were seen at 365, 404, 435, 546, and 579 nm (those below 365 nm were more than 10 times weaker). About 80% of the RhB+ solution was photomineralized after 60 min of irradiation of the aqueous RhB+/TiO2 dispersion with the DQCPP lamp; no UV/ visible spectral features of RhB+ were evident at wavelengths below 250 nm after 30 min. Possible effects of microwave radiation and temperature on the degradative process are described.

Coloring Agents↗