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Levin, N., & Phinn, S. (2016). Illuminating the capabilities of Landsat 8 for mapping night lights. Remote Sensing of Environment, 182, 27–38.
Abstract: Remote sensing of night-lights has been enhanced in recent years with the availability of the new VIIRS Day and Night band, the commercial EROS-B satellite and astronaut photographs from the International Space Station. However, dedicated space-borne multispectral sensors offering radiance calibrated night lights imagery are yet to be launched. Here we examined the capabilities of Landsat 8 to acquire night time light images of the Earth. Examining seven night-time Landsat 8 scenes, we found that brightly lit areas in both urban (Berlin, Las Vegas, Nagoya and Tel-Aviv) and gas flares (Basra, Kuwait) areas were detected in all eight bands of Landsat 8. The threshold for detection of lit areas was approximately 0.4 W/m2/μm/sr in bands 1â5 and 8 of Landsat 8. This threshold level was higher than Landsat dark noise levels, and slightly lower than post launch Landsat 8 OLI band dependent noise equivalent radiance difference levels. Drawing on this, we call on the USGS to plan an annual night-time acquisition of urban and gas flares areas globally, and to enable the performance of the future Landsat 10 to be established in a way that it will be sensitive enough to image the Earth at night, thus performing as Nightsat during the night.
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Akacem, L. D., Wright, K. P. J., & LeBourgeois, M. K. (2016). Bedtime and evening light exposure influence circadian timing in preschool-age children: A field study. Neurobiol Sleep Circadian Rhythms, 1(2), 27–31.
Abstract: Light exposure and sleep timing are two factors that influence inter-individual variability in the timing of the human circadian clock. The aim of this study was to quantify the degree to which evening light exposure predicts variance in circadian timing over and above bedtime alone in preschool children. Participants were 21 children ages 4.5-5.0 years (4.7 +/- 0.2 years; 9 females). Children followed their typical sleep schedules for 4 days during which time they wore a wrist actigraph to assess sleep timing and a pendant light meter to measure minute-by-minute illuminance levels in lux. On the 5th day, children participated in an in-home dim-light melatonin onset (DLMO) assessment. Light exposure in the 2 h before bedtime was averaged and aggregated across the 4 nights preceding the DLMO assessment. Mean DLMO and bedtime were 19:22 +/- 01:04 and 20:07 +/- 00:46, respectively. Average evening light exposure was 710.1 +/- 1418.2 lux. Children with later bedtimes (lights-off time) had more delayed melatonin onset times (r=0.61, p=0.002). Evening light exposure was not independently associated with DLMO (r=0.32, p=0.08); however, a partial correlation between evening light exposure and DLMO when controlling for bedtime yielded a positive correlation (r=0.46, p=0.02). Bedtime explained 37.3% of the variance in the timing of DLMO, and evening light exposure accounted for an additional 13.3% of the variance. These findings represent an important step in understanding factors that influence circadian phase in preschool-age children and have implications for understanding a modifiable pathway that may underlie late sleep timing and the development of evening settling problems in early childhood.
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Delhey, K., & Peters, A. (2016). Implications for conservation of anthropogenic impacts on visual communication and camouflage. Conserv Biol, 31(1), 30–39.
Abstract: Anthropogenic environmental impacts can disrupt the sensory environment of animals and affect important processes from mate choice to predator avoidance. Currently these effects are best understood for auditory and chemo-sensory modalities and recent reviews highlight their importance for conservation. Here we summarise how anthropogenic changes to the visual environment (ambient light, transmission, backgrounds) affect visual communication and camouflage, and highlight implications for conservation. These implications are particularly evident for disrupted camouflage due to its tight links with survival while the conservation importance of impaired visual communication is less well-documented. Such effects can be potentially severe when they affect critical processes such as pollination or species recognition. However, when impaired mate choice does not lead to hybridization, the conservation consequences are less clear. We suggest that the demographic effects of human impacts on visual communication and camouflage will be particularly strong when: (a) human-induced modifications to the visual environment are evolutionary novel, that is, very different from natural variation, (b) affected species and populations have low levels of intraspecific (genotypic and phenotypic) variation and low levels of behavioural, sensory or physiological plasticity and (c) the processes affected are directly related to survival (camouflage), species recognition, or number of offspring produced, rather than offspring quality or attractiveness. The evidence summarized here suggests that anthropogenic effects on the visual environment might be of similar conservation concerns as those on other sensory modalities. This article is protected by copyright. All rights reserved.
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Xiaolong, G., Mo, Z., Xian, L., Ce, S., Changbin, S., & Ying, L. (2016). Effects of LED light quality on the growth, metabolism, and energy budgets of Haliotis discus discus. Aquaculture, 453, 31–39.
Abstract: In this study, a bioenergetics approach was used to examine the effects of different LED light qualities (red, orange, blue, green light, natural light and a dark setting) on the growth and survival of the abalone Haliotis discus discus, and its physiological response mechanism under different light qualities. The results suggest that under blue or green light, the survival rate, specific growth rate, food intake, and food conversion efficiency of H. d. discus were significantly lower than in those groups under red or orange light (P < 0.05). Under red or orange light, pepsin, amylase and cellulose activity was significantly higher than those in any other light quality group (P < 0.05), whereas lipase activity exhibited no significant difference among the light quality groups (P > 0.05). Under blue or green light, lactate dehydrogenase activity and lactic acid content were higher (P < 0.05), suggesting enhanced anaerobic metabolism. Under blue or green light, H. d. discus lost more energy via excretion, feces and respiration than was acquired from its food. Under red or orange light, H. d. discus acquired more energy from its food and lost less energy via excretion and feces; as a result, its assimilation efficiency (K1) and net growth efficiency (K2) were significantly higher than those of any other group (P < 0.05). Therefore, we suggest that red or orange light should be used as a light source for the aquaculture of H. d. discus.
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Duriscoe, D. M. (2016). Photometric indicators of visual night sky quality derived from all-sky brightness maps. JQSRT, 181, 33–45.
Abstract: Wide angle or fisheye cameras provide a high resolution record of artificial sky glow, which results from the scattering of escaped anthropogenic light by the atmosphere, over the sky vault in the moonless nocturnal environment. Analysis of this record yields important indicators of the extent and severity of light pollution. The following indicators were derived through numerical analysis of all-sky brightness maps: zenithal, average all-sky, median, brightest, and darkest sky brightness. In addition, horizontal and vertical illuminance, resulting from sky brightness were computed. A natural reference condition to which the anthropogenic component may be compared is proposed for each indicator, based upon an iterative analysis of a high resolution natural sky model. All-sky brightness data, calibrated in the V band by photometry of standard stars and converted to luminance, from 406 separate data sets were included in an exploratory analysis. Of these, six locations representing a wide range of severity of impact from artificial sky brightness were selected as examples and examined in detail. All-sky average brightness is the most unbiased indicator of impact to the environment, and is more sensitive and accurate in areas of slight to moderate light pollution impact than zenith brightness. Maximum vertical illuminance provides an excellent indicator of impacts to wilderness character, as does measures of the brightest portions of the sky. Zenith brightness, the workhorse of field campaigns, is compared to the other indicators and found to correlate well with horizontal illuminance, especially at relatively bright sites. The median sky brightness describes a brightness threshold for the upper half of the sky, of importance to telescopic optical astronomy. Numeric indicators, in concert with all-sky brightness maps, provide a complete assessment of visual sky quality at a site.
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