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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]

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]

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]

• Photoperiod 16L:8D results in higher PC production than constant illumination. • Synechococcus sp. PCC6715 exhibits T1 type of pigmentation. • PCC6715 genome lacks genes encoding proteins constituting phycoerythrins. • PCC 6715 strain is unable to undergo full complementary chromatic adaptation. • High cultivation temperature prevents microbial contamination. The effect of light colour and light regime on growth and production of the thermostable C-phycocyanin (PC) by the thermophilic cyanobacterium Synechococcus 6715 in the tubular photobioreactor has been analysed. The highest specific growth rate (1.918 d−1) and biomass concentration (5.11 g VS ⋅L−1) were observed under constant illumination of the red light. However, the PC concentration in volatile solids (e.g blue light 30.68 ± 0.8 mg PC ⋅g VS −1 PP and 21.7 ± 1 mg PC ⋅g VS −1 CI) as well as per photobioreactor unit volume (e.g red light 122.66 ± 2.28 mg PC ⋅L−1 PP and 74.71 ± 8.43 mg PC ⋅L−1 PP) was higher in the 16L:8D photoperiod. The obtained PC purity was higher in the case of photoperiod (≈1.5). PCC6715 lacks genes encoding phycoerythrins what suggests T1 type of pigmentation. Although changes in biomass pigmentation were not significant, the strain was able to adapt its photosystem what can be used in the optimization of PC production by application of different light colours. [ABSTRACT FROM AUTHOR]