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Author Wright, K.P.J.; McHill, A.W.; Birks, B.R.; Griffin, B.R.; Rusterholz, T.; Chinoy, E.D.
Title Entrainment of the human circadian clock to the natural light-dark cycle Type Journal Article
Year 2013 Publication Current Biology : CB Abbreviated Journal Curr Biol
Volume 23 Issue 16 Pages 1554-1558
Keywords Human Health; Adult; Circadian Clocks/*radiation effects; Female; Humans; *Lighting; Male; *Photoperiod; *Sunlight; Young Adult; Circadian Rhythm
Abstract The electric light is one of the most important human inventions. Sleep and other daily rhythms in physiology and behavior, however, evolved in the natural light-dark cycle [1], and electrical lighting is thought to have disrupted these rhythms. Yet how much the age of electrical lighting has altered the human circadian clock is unknown. Here we show that electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min:9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time such that the beginning of the internal biological night occurs at sunset and the end of the internal biological night occurs before wake time just after sunrise. In addition, we find that later chronotypes show larger circadian advances when exposed to only natural light, making the timing of their internal clocks in relation to the light-dark cycle more similar to earlier chronotypes. These findings have important implications for understanding how modern light exposure patterns contribute to late sleep schedules and may disrupt sleep and circadian clocks.
Address Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309-0354, USA. kenneth.wright@colorado.edu
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Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0960-9822 ISBN Medium
Area Expedition Conference
Notes PMID:23910656; PMCID:PMC4020279 Approved no
Call Number LoNNe @ christopher.kyba @ Serial 505
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Author Kocifaj, M.; Solano Lamphar, H.A.
Title Quantitative analysis of night skyglow amplification under cloudy conditions Type Journal Article
Year 2014 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal Monthly Notices of the Royal Astronomical Society
Volume 443 Issue 4 Pages 3665-3674
Keywords Skyglow; radiative transfer; scattering; atmospheric effects; light pollution; methods: numerical
Abstract The radiance produced by artificial light is a major source of nighttime over-illumination. It can, however, be treated experimentally using ground-based and satellite data. These two types of data complement each other and together have a high information content. For instance, the satellite data enable upward light emissions to be normalized, and this in turn allows skyglow levels at the ground to be modelled under cloudy or overcast conditions. Excessive night lighting imposes an unacceptable burden on nature, humans and professional astronomy. For this reason, there is a pressing need to determine the total amount of downwelling diffuse radiation. Undoubtedly, cloudy periods can cause a significant increase in skyglow as a result of amplification owing to diffuse reflection from clouds. While it is recognized that the amplification factor (AF) varies with cloud cover, the effects of different types of clouds, of atmospheric turbidity and of the geometrical relationships between the positions of an individual observer, the cloud layer, and the light source are in general poorly known. In this paper the AF is quantitatively analysed considering different aerosol optical depths (AODs), urban layout sizes and cloud types with specific albedos and altitudes. The computational results show that the AF peaks near the edges of a city rather than at its centre. In addition, the AF appears to be a decreasing function of AOD, which is particularly important when modelling the skyglow in regions with apparent temporal or seasonal variability of atmospheric turbidity. The findings in this paper will be useful to those designing engineering applications or modelling light pollution, as well as to astronomers and environmental scientists who aim to predict the amplification of skyglow caused by clouds. In addition, the semi-analytical formulae can be used to estimate the AF levels, especially in densely populated metropolitan regions for which detailed computations may be CPU-intensive. These new results are of theoretical and experimental significance as they will motivate experimentalists to collect data from various regions to build an overall picture of the AF, and will encourage modellers to test the consistency with theoretical predictions.
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ISSN 0035-8711 ISBN Medium
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Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 538
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Author Duriscoe, D.M.
Title Measuring Anthropogenic Sky Glow Using a Natural Sky Brightness Model. Type Journal Article
Year 2013 Publication Publications of the Astronomical Society of the Pacific Abbreviated Journal
Volume 125 Issue 933 Pages 1370-1382
Keywords Skyglow
Abstract Anthropogenic sky glow (a result of light pollution) combines with the natural background brightness of the night sky when viewed by an observer on the earth’s surface. In order to measure the anthropogenic component accurately, the natural component must be identified and subtracted. A model of the moonless natural sky brightness in the V-band was constructed from existing data on the Zodiacal Light, an airglow model based on the van Rhijn function, and a model of integrated starlight (including diffuse galactic light) constructed from images made with the same equipment used for sky brightness observations. The model also incorporates effective extinction by the atmosphere and is improved at high zenith angles (>80°) by the addition of atmospheric diffuse light. The model may be projected onto local horizon coordinates for a given observation at a resolution of 0.05° over the hemisphere of the sky, allowing it to be accurately registered with data images obtained from any site. Zodiacal Light and integrated starlight models compare favorably with observations from remote dark sky sites, matching within ± 8 nL over 95% of the sky. The natural airglow may be only approximately modeled, errors of up to ± 25 nL are seen when the airglow is rapidly changing or has considerable character (banding); ± 8 nL precision may be expected under favorable conditions. When subtracted from all-sky brightness data images, the model significantly improves estimates of sky glow from anthropogenic sources, especially at sites that experience slight to moderate light pollution.
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Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 539
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Author Myers, L.; Christian, K.; Kirchner, R.
Title Flowering responses of 48 lines of oilseed rape (Brassica spp.) to vernalization and daylength Type Journal Article
Year 1982 Publication Australian Journal of Agricultural Research Abbreviated Journal Aust. J. Agric. Res.
Volume 33 Issue 6 Pages 927
Keywords Plants
Abstract Forty-eight lines of Brassica spp, of diverse origins were grown in the glasshouse either under natural daylengths or daylengths extended to 16 h by artificial illumination. Plants were either unvernalized or had been subjected to 6 weeks at 8¦C day and 6¦C night temperatures as seedlings. Lines could be classified into two major groups, according to whether or not vernalization or long photoperiods were essential for 50% flowering within 21 weeks. In six lines, both vernalization and long days were essential for prompt flowering, while only five lines did not respond to either treatment. Strong interactions between lines and treatments were found in the number of leaves and subtended buds at flowering. The results show that a wide range of responses is obtainable from material currently available, offering considerabk, scope for adaptation to different environments.
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Language Summary Language Original Title
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ISSN 0004-9409 ISBN Medium
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Notes Approved no
Call Number IDA @ intern @ Serial 2369
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Author Aubé, M.; Franchomme-Fossé, L.; Robert-Staehler, P.; Houle, V.
Title Light pollution modeling and detection in a heterogeneous environment: toward a night time aerosol optical depth retrieval method. Type Journal Article
Year 2005 Publication Proceedings of SPIE 2005 -- Volume 5890, San Diego, California, USA. Abbreviated Journal
Volume 5890 Issue Pages
Keywords Skyglow; aerosol optical depth;  remote sensing; light pollution; artificial skyglow
Abstract Tracking the Aerosol Optical Depth (AOD) is of particular importance in monitoring aerosol contributions to global radiative forcing. Until now, the two standard techniques used for retrieving AOD were; (i) sun photometry, and (ii) satellite based approaches, such as based DDV (Dense Dark Vegetation) inversion algorithms. These methods are only available for use during daylight time since they are based on direct or indirect observation of sunlight. Few attempts have been made to measure AOD behaviour at night. One such method uses spectrally ­ calibrated stars as reference targets but the number of available stars is limited. This is especially true for urban sites where artificial lighting hides most  of these stars. In this research, we  attempt  to provide an alternate method, one  which exploits artificial sky glow or light pollution. This methodology links a 3D light pollution model with in situ light pollution measurements. The basic idea is to adjust an AOD value into the model in order to fit measured light pollution. This method requires an accurate model that includes spatial heterogeneity in lighting angular geometry, in lighting spectral dependence, in ground spectral reflectance and in topography. This model, named ILLUMINA, computes 1st and 2nd order molecular and aerosol scattering, as well as aerosol absorption. These model features represent major improvements to previous light pollution models. Therefore, new possibilities for light pollution studies will arise, many of which are of particular interest to the astronomical community. In this paper we will present a first sensitive study applied to the ILLUMINA model.
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Notes Approved no
Call Number LoNNe @ kagoburian @ Serial 554
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