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Author Stone, J.E.; Phillips, A.J.K.; Ftouni, S.; Magee, M.; Howard, M.; Lockley, S.W.; Sletten, T.L.; Anderson, C.; Rajaratnam, S.M.W.; Postnova, S.
Title Generalizability of A Neural Network Model for Circadian Phase Prediction in Real-World Conditions Type Journal Article
Year 2019 Publication Scientific Reports Abbreviated Journal Sci Rep
Volume 9 Issue 1 Pages 11001
Keywords Human Health; Instrumentation
Abstract A neural network model was previously developed to predict melatonin rhythms accurately from blue light and skin temperature recordings in individuals on a fixed sleep schedule. This study aimed to test the generalizability of the model to other sleep schedules, including rotating shift work. Ambulatory wrist blue light irradiance and skin temperature data were collected in 16 healthy individuals on fixed and habitual sleep schedules, and 28 rotating shift workers. Artificial neural network models were trained to predict the circadian rhythm of (i) salivary melatonin on a fixed sleep schedule; (ii) urinary aMT6s on both fixed and habitual sleep schedules, including shift workers on a diurnal schedule; and (iii) urinary aMT6s in rotating shift workers on a night shift schedule. To determine predicted circadian phase, center of gravity of the fitted bimodal skewed baseline cosine curve was used for melatonin, and acrophase of the cosine curve for aMT6s. On a fixed sleep schedule, the model predicted melatonin phase to within +/- 1 hour in 67% and +/- 1.5 hours in 100% of participants, with mean absolute error of 41 +/- 32 minutes. On diurnal schedules, including shift workers, the model predicted aMT6s acrophase to within +/- 1 hour in 66% and +/- 2 hours in 87% of participants, with mean absolute error of 63 +/- 67 minutes. On night shift schedules, the model predicted aMT6s acrophase to within +/- 1 hour in 42% and +/- 2 hours in 53% of participants, with mean absolute error of 143 +/- 155 minutes. Prediction accuracy was similar when using either 1 (wrist) or 11 skin temperature sensor inputs. These findings demonstrate that the model can predict circadian timing to within +/- 2 hours for the vast majority of individuals on diurnal schedules, using blue light and a single temperature sensor. However, this approach did not generalize to night shift conditions.
Address School of Physics, University of Sydney, Sydney, New South Wales, Australia
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2045-2322 ISBN Medium
Area Expedition Conference
Notes PMID:31358781; PMCID:PMC6662750 Approved no
Call Number GFZ @ kyba @ Serial (down) 2667
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Author Todd, J.J.; Barakat, B.; Tavassoli, A.; Krauss, D.A.
Title The Moon’s Contribution to Nighttime Illuminance in Different Environments Type Journal Article
Year 2015 Publication Proceedings of the Human Factors and Ergonomics Society Annual Meeting Abbreviated Journal Proceedings of the Human Factors and Ergonomics Society Annual Meeting
Volume 59 Issue 1 Pages 1056-1060
Keywords Moonlight
Abstract The moon’s contribution to illuminance was investigated in order to determine the role it may play in providing a level of illuminance suitable to perform everyday tasks in nighttime outdoor environments. The level of illuminance provided in an area void of artificial lighting was compared to illuminance in an urban environment. Moon phase affected illuminance only in the absence of urban lighting. This effect was lost when controlling for altitude and azimuth, suggesting the moon’s location in the sky has a more significant effect on illuminance than the phase of the moon. These results are discussed in relation to our current understanding and experience of navigating and operating in nighttime environments.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1541-9312 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial (down) 2666
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Author Nagai, N.; Ayaki, M.; Yanagawa, T.; Hattori, A.; Negishi, K.; Mori, T.; Nakamura, T.J.; Tsubota, K.
Title Suppression of Blue Light at Night Ameliorates Metabolic Abnormalities by Controlling Circadian Rhythms Type Journal Article
Year 2019 Publication Investigative Ophthalmology & Visual Science Abbreviated Journal Invest Ophthalmol Vis Sci
Volume 60 Issue 12 Pages 3786-3793
Keywords Human Health; Animals
Abstract Purpose: Light-emitting diodes that emit high-intensity blue light are associated with blue-light hazard. Here, we report that blue light disturbs circadian rhythms by interfering with the clock gene in the suprachiasmatic nucleus (SCN) and that suppression of blue light at night ameliorates metabolic abnormalities by controlling circadian rhythms. Methods: C57BL/6J mice were exposed to 10-lux light for 30 minutes at Zeitgeber time 14 for light pulse with blue light or blue-light cut light to induce phase shift of circadian rhythms. Phase shift, clock gene expression in SCN, and metabolic parameters were analyzed. In the clinical study, healthy participants wore blue-light shield eyewear for 2 to 3 hours before bed. Anthropometric data analyses, laboratory tests, and sleep quality questionnaires were performed before and after the study. Results: In mice, phase shift induced with a blue-light cut light pulse was significantly shorter than that induced with a white light pulse. The phase of Per2 expression in the SCN was also delayed after a white light pulse. Moreover, blood glucose levels 48 hours after the white light pulse were higher than those after the blue-cut light pulse. Irs2 expression in the liver was decreased with white light but significantly recovered with the blue-cut light pulse. In a clinical study, after 1 month of wearing blue-light shield eyeglasses, there were improvements in fasting plasma glucose levels, insulin resistance, and sleep quality. Conclusions: Our results suggest that suppression of blue light at night effectively maintains circadian rhythms and metabolism.
Address Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
Corporate Author Thesis
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0146-0404 ISBN Medium
Area Expedition Conference
Notes PMID:31504080 Approved no
Call Number GFZ @ kyba @ Serial (down) 2665
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Author Rybnikova, N.A.; Portnov, B.A.
Title Mapping geographical concentrations of economic activities in Europe using light at night (LAN) satellite data Type Journal Article
Year 2014 Publication International Journal of Remote Sensing Abbreviated Journal International Journal of Remote Sensing
Volume 35 Issue 22 Pages 7706-7725
Keywords Remote Sensing
Abstract Data on geographical concentrations of economic activities, such as manufacturing, construction, wholesale and retail trade, financial services, etc., are important for identifying clusters of economic activities (EAs) and concentrations of forces behind them. However, such data are essentially sparse due to limited reporting by individual countries and administrative entities. For example, at present, Eurostat provides EA data for <50% of all regional subdivisions of the third tier of the Nomenclature of Territorial Units for Statistics (NUTS3). Measurements of light at night (LAN), as captured by satellite sensors, are likely to differ in intensity, depending on the source. As a result, LAN levels can become a marker for EAs; the present study attempts to verify this possibility. As the present analysis indicates, the inclusion of LAN intensities in multivariate models (in addition to standard economic and locational variables) helps to explain up to 88.8% of the EA variation, performing especially well for manufacturing, construction, and agriculture (the adjusted coefficient of determination (R2-adjusted) is in the range of 0.754–0.888). The study thus confirms the feasibility of using LAN satellite measurements for reconstructing geographical patterns of EAs, information that may be restricted or is unavailable due to sparse or incomplete reporting.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0143-1161 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial (down) 2664
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Author Chen, S.; Li, W.; Yang, S.; Zhang, B.; Li, T.; Du, Y.; Yang, M.; Zhao, H.
Title Evaluation method and reduction measures for the flicker effect in road lighting using fixed Low Mounting Height Luminaires Type Journal Article
Year 2019 Publication Tunnelling and Underground Space Technology Abbreviated Journal Tunnelling and Underground Space Technology
Volume 93 Issue Pages 103101
Keywords Lighting; Vision
Abstract Low Mounting Height Luminaires (LMHL) are used in many cities on viaducts, cross-sea and cross-river bridges due to their unique advantages. However, the flicker effect is an important factor that needs to be considered in road lighting using fixed LMHL. At present, there are not many researchers in the field of international lighting. Previous types of road lighting design were based on the method of the tunnel lighting flicker effect. At the same time, the flicker effect is mainly based on the subjective feelings of people but is not quantified. In this paper, the Flicker Index (FI) is calculated by measuring the parameters of streetlamps to evaluation flicker effect. Secondly, the suggestion to offset the flicker effect in CIE 88-2004 “Guide for the Lighting of Road Tunnels and Underpasses” is to limit the speed of the vehicle and adjust the road light spacing to avoid the flicker sensitive area on human eyes, while ignoring the essential problem of how the flicker effect is generated through the energy level of the stimulating optical signal. Two factors affecting the strength of the flicker effect are proposed: energy ratio and duty cycle. The duty cycle, in time, refers to the proportion of the strong and weak flashing signals during the period; in space, it refers to the proportional relationship between the length of the luminaire and the distance between the lamps, which is related to the running speed of the vehicle. It is consistent with the CIE recommendations for flicker. Thirdly, the essence of the flicker effect is the problem of the energy level of the stimulus signal. This study investigated the reduction in the brightness of the light source, hence reducing the energy of the visual stimulation signal to the human eye in order to judge the degree of fatigue in human vision. The experimental results show that the degree of fatigue in human vision decreases when the brightness of the experimental light source decreases. Therefore, the key to changing the flicker effect of LMHL is to reduce the contrast between the surface brightness of the luminaire and the brightness of the spatial background.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0886-7798 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial (down) 2663
Permanent link to this record