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Colour in the classroom, either in isolation or in conjunction with other environmental factors, is an element that has been widely discussed in the scientific literature, albeit not systematically. On the other hand, its evolution towards coloured light, made possible in recent years by light emitting diode (LED) technology, has hardly found a place among researchers. Despite the progressive rise of smart classrooms, intelligent learning environments or references by some authors to "dynamic lighting", its analogous concept, "dynamic colour", hardly appears in reviews of the scientific literature. This exploratory, quasi-experimental study shows how coloured light affects the learning process in primary school classroom environments, integrating cognitive processes, instrumental learning and affective processes, and helping to define the dynamic potential of its use. The experimental part has been carried out for four weeks, collecting data that are analysed descriptively, comparatively with the control group and in the internal variance of the experimental group. The results show positive influence tendencies in the cognitive and affective processes of the students, although not so much in instrumental learning. [ABSTRACT FROM AUTHOR]

Nowadays, lighting planning is predominantly determined by the need to meet physically measurable requirements that are often based on current lighting standards. However, meeting the minimum technical requirements of the standards is no guarantee for a visually appealing light environment. Instead, requirements based on perceived light qualities also need to be included to achieve better user comfort. Taking perception-based qualities into consideration when creating a light environment is, for many, not an easy task. In addition, a common terminology for perceived light qualities is currently lacking, both in industry and in research. The aim of this paper is, therefore, to explore how perceived light qualities of white light sources can be described when employing user-centric measures. The focus was on the qualities of light colour and diffuse and distinct light since these qualities have a great impact on the visual impression of light. The perception was assessed by applying analytical sensory analysis to lighting products, a method found to be promising in previous work. The methodology is based on analytical measurement by the human senses, which is particularly valuable when developing a general terminology. Since sensory analysis is still quite new to the topic of lighting, the applicability of using the methodology to assess lighting in a real context was also investigated. The results of the studies showed that the perception of light qualities can be described using further concepts in addition to those currently used. For light colour, the concepts of reddish, bluish, yellowish, and greenish light colours proved suitable for providing a richer description of the quality. The concepts of diffuse and distinct light satisfactorily captured variations in light contrast produced by shadows, reflections, and sparkles. In addition, the studies revealed that analytical sensory analysis was applicable for assessing the perception of lighting in a real-world context. The latter means that knowledge gained in the laboratory can be translated into real environments. The user-centric measures investigated in this paper have contributed to the terminology related to perceived light qualities. These can complement the physical measures in lighting planning to promote light environments that are not only energy efficient and meet technical requirements, but also cater for increased user comfort. Doi: 10.28991/ESJ-2023-07-02-022 Full Text: PDF

The purpose of this study was to analyse the effects of light colour on rabbit reproductive performance and the expression of key follicular development genes. Rabbits (n = 1,068, 5 months old, 3.6–4.4 kg live body weight) were divided randomly into four groups, housed individually in wire mesh cages and exposed to red, green, blue, and white light-emitting diode (LED) light (control). The lighting schedule was 16 L : 8 D-15 d / 150 lx / 6:00 am–22:00 pm (3 d preartificial insemination to 12 d postartificial insemination). Red light and white light affected the conception rate and kindling rate and increased the total litter size at birth (p < 0.05). The effects of red light on litter size at weaning, litter weight at weaning, and individual weight at weaning increased compared with the green and blue groups. The effects of red light on live litter size at birth were increased compared with those in the blue group (p < 0.05). Compared to white light, green and blue light reduced the number of secondary follicles (p < 0.05). Compared to red light, green and blue light reduced the number of tertiary follicles (p < 0.05). Compared with white light, red LED light resulted in greater ovarian follicle stimulating hormone receptor and luteinizing hormone receptor mRNA expression (p < 0.05). Compared with green and blue LED light, red LED light resulted in greater B-cell lymphom-2 mRNA expression (p < 0.05). Compared with green LED light, red LED light inhibited FOXO1 mRNA expression in rabbit ovaries (p < 0.05). Red light can affect the reproductive performance of female rabbits and the expression of key genes for follicular development.

Snubnose pompano (Trachinotus blochii) are widely cultured in the world. Light colours are among factors affecting fish performance in captivity. Snubnose pompano larvae often reared under white light. However, no study supports its choice or informs the extent of its effect or its constituent colour. The study investigated the influence of green, blue, yellow, purple, and white lights on growth, survival, cortisol, body composition, and digestive enzymes activities of one-day post-hatch Snubnose pompano larvae reared in light magenta tanks under a photoperiod of 24 Light:0 Dark hours for 25 days. Overall, the best growth performance of snubnose pompano larvae was in purple and white, and green lights during early and late larval stages, respectively. White light promoted survival rate while that of green light reduced. Larvae were less stressed and had enhanced body contents under white and purple light environments. Purple and yellow lights influenced low trypsin and pepsin activities. The study reports for the first time the effect of the light colour environment on the digestive enzyme activities and body composition of the finfish larvae. Generally, the study provides novel insights on optimal light colour in the larval rearing protocol of this species. Through this study, the use of white light during the first feeding (zero to four days post-hatch) and purple light in later stages (five days post-hatch until metamorphosis) is encouraged while discourages green and yellow lights in the larval rearing of Snubnose pompano.

This study aimed to systematically analyse the differences in emotions evoked by the same colour, depending on whether it is an object or light colour. To this end, an assessment was conducted using mock experimental spaces created with either object or light colours (red, green, blue and yellow) and with different levels of illuminance (10 lx or 100 lx). The participants comprised 30 graduate students (19 men; 20–30 years) majoring in colour and lighting, and the vocabulary selected for emotional assessment included the words 'comfortable', 'stable', 'tense', 'anxious', 'cool' and 'warm'. The results demonstrated differences between participants' emotional reactions to the object colour and light colour environments when the same colour was used. For red, green and blue, the object colour was rated higher than the light colour for positive responses of 'comfortable' and 'stable'. For yellow, however, the response differed only slightly between object colour and light colour. Finally, emotional differences varied significantly depending on illuminance level for object colour but not for light colour. [ABSTRACT FROM AUTHOR]

In order to establish a lighting regime suitable for rabbit farms in East China, the effects of lighting schedule, intensity and colour on the reproductive performance of rabbit does were evaluated by three experiments, respectively. In experiment 1, does were exposed to different lighting schedules: 16L:8D-continuous, 16L:8D-18d (6 d before artificial insemination (AI) to 12 d post-AI), 16L:8D-6d (6 d before AI to the day of AI) and 12L:12D-continuous. In experiment 2, does were exposed to different light intensities: 40 lx, 60 lx, 80 lx and 120 lx. In experiment 3, does were exposed to different light colours: white, yellow, blue and red. For all experiments, conception rate, kindling rate and pre-weaning mortality were calculated; litter size at birth, litter weight at birth, litter size at weaning, litter weight at weaning and individual kit weight at weaning were recorded. Results showed that none of the reproductive parameters of does were affected by the application of 16L:8D-18d lighting schedule compared with the continuous 16L:8D group (P>0.05). Moreover, rabbits does exposed to 80 lx light performed as well as those under 120 lx light in conception rate, kindling rate, litter size (total and alive) at birth and litter weight at birth (P>0.05). Furthermore, the exposures of 60 lx and 80 lx light were beneficial for litter weight at weaning. In addition, red light had a positive effect, as it led to a larger litter size and litter weight at weaning and lower pre-weaning mortality than white light (P<0.05). In summary, a 16L:8D photoperiod with 80 lx red light from 6 d before AI to 12 d post-AI is recommended for use in breeding of rabbit does according to our results. [ABSTRACT FROM AUTHOR]

A closed system for plant production with artificial light is an innovative method of plant cultivation. The objective of this study was to investigate the effect of light colour on rooting cuttings and subsequent growth of chrysanthemum (Chrysanthemum × grandiflorum Ramat./Kitam.) During the experiments, the following conditions were maintained: photoperiod 16 h or 10 h, temperature 22 °C, relative humidity of 65–70%. LED lamps emitted the following light colours: white, blue, white + blue (50:50), and red + blue (75:25). For all light spectra, the photosynthetic photon flux density (PPFD) was 50 μmol m−2 s−1. The effectiveness of exposure to different light colours was measured with parameters: cutting weight (g), cutting length (cm), length of roots, and index of leaf greenness (SPAD). The measurements referred to plant features determining plant quality, i.e., the number of flower buds and flower head, the diameter of the flower head, height of plants, index of leaf greenness (SPAD), the number of leaves, and the fresh and dry weights of aboveground parts of plants. The rooting of cuttings and subsequent growth are integral processes in the cultivation of potted chrysanthemums. Both were differently affected by the colour of light from LED lamps. The exposure to red + blue light resulted in the highest leaf greenness index (SPAD) value and the shortest cuttings with the longest roots. White + blue light significantly influenced most of the growth parameters, except the height of the plants and the number of leaves.

INTRODUCTION: Some Alzheimer’s Disease (AD) patients respond to chromatic light stimulus, which mayinfluence intrinsically photosensitive retinal ganglion cells (ipRGCs), due to factors common to both AD andAge-Related Macular Disease (AMD).OBJECTIVES: In this study, short light pulses of three colours were introduced to a novel diagnostic procesure for AD patients such as classification techniques using waveform features of pupil light reflexs (PLRs), and their prediction performances were evaluated.METHOD: PLRs to 1s pulses of red, blue and white stimuli shown at high and low photopic levels followedby a 7s restoration process were recorded after the stimuli were shown to 7 AD patients and 12 non-ADparticipants (aged 42-89). Features of waveform shapes of PLRs in 5 dimensions and 15 features of PLRs were extracted.RESULTS: In a classification analysis, most non-AD participants were correctly identified using the samelevel of performance we reported when PLRs for red and blue stimuli were used to measure the performanceof AD patients. There were significant differences in some of the features of PLRs extracted from the twogroups (AD and non-AD participants), particularly with the features for blue light stimuli in high brightness,which produced significant reactions in AD patients. The classification performance of using 15 features ofthe response to blue light stimuli was the highest among responses for all three colours, and was higher than the performance using the procedure in the previous study. Also, a few of the features extracted using the three colours of stimuli changed significantly across age ranges (70 and under, 71-80, and over 80), so these may indicate factors related to ageing.CONCLUSION: These results confirm that some specific features of PLRs, in particular the response to blue light, can indicate the existence of AD in patients. Also, a few of the features may reveal factors related toageing during evaluations which use PLRs. This evidence may help in the better understanding of features of PLRs.

INTRODUCTION: Some Alzheimer's Disease (AD) patients respond to chromatic light stimulus, which may influence intrinsically photosensitive retinal ganglion cells (ipRGCs), due to factors common to both AD and Age-Related Macular Disease (AMD). OBJECTIVES: In this study, short light pulses of three colours were introduced to a novel diagnostic procesure for AD patients such as classification techniques using waveform features of pupil light reflexs (PLRs), and their prediction performances were evaluated. METHOD: PLRs to 1s pulses of red, blue and white stimuli shown at high and low photopic levels followed by a 7s restoration process were recorded after the stimuli were shown to 7 AD patients and 12 non-AD participants (aged 42-89). Features of waveform shapes of PLRs in 5 dimensions and 15 features of PLRs were extracted. RESULTS: In a classification analysis, most non-AD participants were correctly identified using the same level of performance we reported when PLRs for red and blue stimuli were used to measure the performance of AD patients. There were significant differences in some of the features of PLRs extracted from the two groups (AD and non-AD participants), particularly with the features for blue light stimuli in high brightness, which produced significant reactions in AD patients. The classification performance of using 15 features of the response to blue light stimuli was the highest among responses for all three colours, and was higher than the performance using the procedure in the previous study. Also, a few of the features extracted using the three colours of stimuli changed significantly across age ranges (70 and under, 71-80, and over 80), so these may indicate factors related to ageing. CONCLUSION: These results confirm that some specific features of PLRs, in particular the response to blue light, can indicate the existence of AD in patients. Also, a few of the features may reveal factors related to ageing during evaluations which use PLRs. This evidence may help in the better understanding of features of PLRs. [ABSTRACT FROM AUTHOR]

Culicoides biting midges (Diptera: Ceratopogonidae) are vectors of a range of orbiviruses that cause important veterinary diseases such as bluetongue and African horse sickness. The effective monitoring of Culicoides species diversity and abundance, both at livestock and near potential wildlife hosts, is essential for risk management. The Onderstepoort 220‐V ultraviolet (UV) light trap is extensively used for this purpose. Reducing its power requirements by fitting low‐energy light‐emitting diodes (LEDs) can lead to greater flexibility in monitoring. A comparison of the efficiency of the 220‐V Onderstepoort trap (8‐W fluorescent UV light) with the efficiency of the 220‐V or 12‐V Onderstepoort traps fitted with red, white, blue or green LEDs or a 12‐V fluorescent Onderstepoort trap demonstrated the 220‐V Onderstepoort trap to be the most efficient. All the results showed nulliparous Culicoides imicola Kieffer females to be the dominant grouping. Despite the lower numbers collected, 12‐V traps can be used in field situations to determine the most abundant species. Tests showed that 220‐V fluorescent ultraviolet light traps were more efficient than 220‐V traps fitted with red, white, blue or green LEDs for the collection of livestock‐associated Culicoides species.Similarly, 220‐V fluorescent UV traps collected greater numbers of Culicoides than 12‐V fluorescent traps or 12‐V white, blue or green LED traps.Despite the lower numbers collected, 12‐V traps can be used in field situations to effectively determine Culicoides species composition, population age structure and the most abundant species in an area. [ABSTRACT FROM AUTHOR]

The concept of the smart city raised several technological and scientific issues including light pollution. There are various negative impacts of light pollution on economy, ecology, and heath. This paper deals with the census of the colour of light emitted by lamps used in a city environment. To this end, we derive a light bulb colour estimator based on Bayesian reasoning, directional data, and image formation model in which the usual concept of reflectance is not used. All choices we made are devoted to designing an algorithm which can be run almost in real-time. Experimental results show the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In this study we investigated the influence of artificial light at night (ALAN) of different intensities (0, 1, 10, 100 lx) and different colours (blue, green, red) on the daily melatonin rhythm and mRNA expression of gonadotropins in roach Rutilus rutilus, a ubiquitous cyprinid, which occur in standing and moderately flowing freshwater habitats of central Europe. Melatonin concentrations were significantly lowered under nocturnal white light already at 1 lx. Low intensity blue, green and red ALAN lowered the melatonin levels significantly in comparison to a dark control. We conclude that ALAN can disturb melatonin rhythms in roach at very low intensities and at different wavelengths and thus light pollution in urban waters has the potential to impact biological rhythms in fish. However, mRNA expression of gonadotropins was not affected by ALAN during the period of the experiments. Thus, suspected implications of ALAN on reproduction of roach could not be substantiated. [ABSTRACT FROM AUTHOR]

Artificial light at night has shown a remarkable increase over the past decades. Effects are reported for many species groups, and include changes in presence, behaviour, physiology and life-history traits. Among these, bats are strongly affected, and how bat species react to light is likely to vary with light colour. Different spectra may therefore be applied to reduce negative impacts. We used a unique set-up of eight field sites to study the response of bats to three different experimental light spectra in an otherwise dark and undisturbed natural habitat. We measured activity of three bat species groups around transects with light posts emitting white, green and red light with an intensity commonly used to illuminate countryside roads. The results reveal a strong and spectrum-dependent response for the slowflying Myotis and Plecotus and more agile Pipistrellus species, but not for Nyctalus and Eptesicus species. Plecotus and Myotis species avoided white and green light, but were equally abundant in red light and darkness. The agile, opportunistically feeding Pipistrellus species were significantly more abundant around white and green light, most likely because of accumulation of insects, but equally abundant in red illuminated transects compared to dark control. Forest-dwelling Myotis and Plecotus species and more synanthropic Pipistrellus species are thus least disturbed by red light. Hence, in order to limit the negative impact of light at night on bats, white and green light should be avoided in or close to natural habitat, but red lights may be used if illumination is needed. [ABSTRACT FROM AUTHOR]

Light pollution is increasing exponentially, but its impact on animal behaviour is still poorly understood. For songbirds, the most repeatable finding is that artificial night lighting leads to an earlier daily onset of dawn singing. Most of these studies are, however, correlational and cannot entirely dissociate effects of light pollution from other effects of urbanization. In addition, there are no studies in which the effects of different light colours on singing have been tested. Here, we investigated whether the timing of dawn singing in wild songbirds is influenced by artificial light using an experimental set-up with conventional street lights. We illuminated eight previously dark forest edges with white, green, red or no light, and recorded daily onset of dawn singing during the breeding season. Based on earlier work, we predicted that onset of singing would be earlier in the lighted treatments, with the strongest effects in the early-singing species. However, we found no significant effect of the experimental night lighting (of any colour) in the 14 species for which we obtained sufficient data. Confounding effects of urbanization in previous studies may explain these results, but we also suggest that the experimental night lighting may not have been strong enough to have an effect on singing.

Avian literature reports the modulation of ‘photoperiodic gonadal responses’ by the temporal phase relation of serotonergic and dopaminergic oscillations in Japanese quail. But, the modulation of ‘light colour responses’ by the temporal synergism of neural oscillations is not yet known. Hence the present study was designed to investigate the interaction of the light colour (blue, red) and the phase relation of neural oscillations in the reproductive regulation of Japanese quail. Three week old male Japanese quail were divided into two groups and maintained under a long day length condition (16 L:8D) and were exposed to a 30 lux intensity of blue LED (light emitting diode) (B LED) and a red LED light (R LED). At the age of 15.5 weeks, quail of one subgroup of B LED were injected with serotonin precursor (5-HTP) and dopamine precursor ( l -DOPA) 12 hrs apart (B LED + 12-hr) and those of the R LED group were injected with the same drugs (5 mg/100 g body weight over a period of thirteen days) but 8 hrs apart (R LED + 8-hr). The remaining subgroups of both the light colour groups (B LED & R LED) received normal saline twice daily and served as controls. Cloacal gland volume was recorded weekly until 35.5 weeks of age when the study was terminated and reproductive parameters (testicular volume, GSI, seminiferous tubule diameter and plasma testosterone) were assessed. Results indicate that the 8-hr temporal phase relation of neural oscillations suppresses reproductive activity even during the photosensitive phase of the red light exposed quail (R LED + 8-hr) compare to the R LED controls. On the other hand, the 12-hr temporal phase relation stimulates the gonadal development of the B LED + 12-hr quail compared to the B LED controls which after completing one cycle entered into a regressive phase and remained sexually quiescent. These experiments suggest that the temporal phase relations of circadian neural oscillations, in addition to modulating the classical photoperiodic responses, may also modulate the gonadal responses to blue (suppressive) and red (stimulatory) light. These studies led us to conclude that the temporal phase relation of serotonergic and dopaminergic oscillations is not only an important regulator of avian reproduction but may also override the classical effects of light colours in Japanese quail. [ABSTRACT FROM AUTHOR]

Melatonin affects physiological processes that have circadian and seasonal cycles and causes behavioural changes in nearly all organisms, ranging from bacteria to mammals. However, no studies have focused on the presence, biosynthetic pathway, and rhythms of melatonin in bivalves, which are considered as the class of molluscs with the highest economic value. Here, the metabolic pathway and tissue distribution of melatonin, tissue transcription profiles of melatonin-related genes [key synthases arylalkylamine N-acetyltransferase type 2 and 5 (aanat2 , aanat5), N-acetylserotonin methyltransferase (asmt), and melatonin receptor type 1 A1 and C3 (MTNR1A1 , MTNR1C3)], daily changes in melatonin, transcripts of genes, and effects of four lights (blue, cyan, orange, and red) during the night on melatonin secretion were studied in a bivalve species, razor clam Sinonovacula constricta. Our results showed the presence of complete metabolic and circadian entrainment pathways of melatonin. The melatonin content in the lymphocytes and labial palp was higher than that in the other studied tissues, and aanat2 , aanat5 , asmt , MTNR1A1 , and MTNR1C3 mRNA levels were the highest in the labial palp. Melatonin fluctuated rhythmically in lymphocytes and labial palps and increased at night. Similarly, aanat2 , aanat5 , asmt , MTNR1A1 , and MTNR1C3 mRNA levels were rhythmic in the labial palp, peaking at night. In addition, blue light effectively inhibited the nocturnal secretion of melatonin in the clam. In summary, our results suggest that melatonin plays a role in light signal transduction and the circadian system in S. constricta. • Melatonin could be biosynthesized by the clam Sinonovacula constricta. • Labial palp probably is an important tissue where melatonin exerted its function. • The biosynthesis and secretion of melatonin in the clam are enhanced under the dark phase of the photoperiod. • Blue light inhibits melatonin production in the clam. [ABSTRACT FROM AUTHOR]

We tested the effects of monochromatic light on the specific growth rate (SGR), feed intake and feed efficiency (FE) of juvenile pikeperch, Sander lucioperca (L.). Pikeperch were reared individually for 42 days in aquaria covered with blue, green, yellow or red gelatin filters or white paper (control; n=5). Linear regression analysis indicated a significant positive effect of longer wavelengths of light on the condition factor (CF), FE and SGR. The final weight, SGR and CF were significantly higher in fish reared under red than under white light, and FE was better under green, yellow and red light than under white light (Dunnett's post hoc test, P<0.05) while blue was comparable to white light in terms of the measured parameters. After the growth trial, the spectral sensitivity of photoreceptor cells in the retina was tested using microspectrophotometry, which revealed the presence of rods with λmax at ca. 530 nm and two cone classes, absorbing maximally at ca. 535 and 603 nm, all containing a porphyropsin-based pigment. These results suggest that the presence of mid and long wavelength-sensitive cones enhances visual sensitivity under mid-wavelength and long-wavelength environments, and thus supports the finding that longer wavelengths of incoming light can improve FE and SGR of the cultivated pikeperch. [ABSTRACT FROM AUTHOR]

In the present research, a new surface coating method (dissolving-coating method) that is on the basis of dissolution mechanism was designed. Substantially transparent antimony doped tin oxide (ATO) particles were used instead of carbon black as conductive particles. ATO coated polyester (PET) fibres and ATO coated polycaprolactam (PA6) fibres were prepared by the traditional coating method and the dissolving–coating method respectively. The electrical conductivity, mechanical property and launderability of the coated fibres were discussed. For the characterisation, a laser particle size distribution analyser was used to analyse the size distribution of ATO. Scanning electron microscopy (SEM) and transmittance electron microscopy (TEM) were used for the observation of ATO particles and fibre surface. Electron probe was carried out to make an elemental analysis of the fibre. [ABSTRACT FROM AUTHOR]

In an attempt to increase the accuracy of roost emergence counts for a monitoring programme, the exits of two Pipistrellus pygmaeus roosts were illuminated with light of different colours and intensities. Light intensity affected bat emergence more than light colour. At one roost there was no significant difference in the bat emergence pattern between when the roost exit received no illumination and when it was illuminated with red light. The use of the latter is proposed to increase the accuracy of bat roost emergence counts. [Copyright &y& Elsevier]