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Author Kocifaj, M.; Bará, S.
Title (down) Two-index model for characterizing site-specific night sky brightness patterns Type Journal Article
Year 2019 Publication Monthly Notices of the Royal Astronomical Society Abbreviated Journal
Volume 490 Issue 2 Pages 1953-1960
Keywords Skyglow
Abstract The determination of the all-sky radiance distribution produced by artificial light sources is a computationally demanding task that generally requires intensive calculations. In this paper, we develop an analytical formulation that provides the all-sky radiance distribution produced by an artificial light source as an explicit and analytical function of the observation direction, depending on two single parameters that characterize the overall effects of the atmosphere. One of these parameters is related to the effective attenuation of the light beams, whereas the other accounts for the overall asymmetry of the combined scattering processes in molecules and aerosols. Using this formulation, a wide range of all-sky radiance distributions can be efficiently and accurately calculated in a short time. This substantial reduction in the number of required parameters, in comparison with other approaches that are currently used, is expected to facilitate the development of new applications in the field of light pollution research.
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Series Volume Series Issue Edition
ISSN 0035-8711 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2704
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Author Kyba, C.C.M.; Ruhtz, T.; Lindemann, C.; Fischer, J.; Hölker, F.
Title (down) Two camera system for measurement of urban uplight angular distribution Type Journal Article
Year 2013 Publication AIP Conf. Proc Abbreviated Journal
Volume 1531 Issue 568 Pages
Keywords Instrumentiation
Abstract The angular distribution function of light emitted from cities is unknown, and represents the most important systematic error in skyglow simulations. We describe a method for measuring this distribution using a two camera system mounted on an aerial platform. We present preliminary results from a test flight using such a system, taken over the city of Berlin on July 14, 2011.
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Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 467
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Author Roenneberg, T.; Foster, R.G.
Title (down) Twilight Times: Light and the Circadian System Type Journal Article
Year 1997 Publication Photochemistry and Photobiology Abbreviated Journal Photochem Photobiol
Volume 66 Issue 5 Pages 549-561
Keywords Human Health
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Language Summary Language Original Title
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ISSN 0031-8655 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number LoNNe @ kagoburian @ Serial 800
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Author Raiewski, E.E.; Elliott, J.A.; Evans, J.A.; Glickman, G.L.; Gorman, M.R.
Title (down) Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles Type Journal Article
Year 2012 Publication Chronobiology International Abbreviated Journal Chronobiol Int
Volume 29 Issue 9 Pages 1206-1215
Keywords Animals; Circadian Rhythm/*physiology; Cricetinae; Male; Melatonin/blood/*secretion; Mesocricetus/blood/*physiology; Motor Activity/physiology; Phodopus/blood/*physiology; Photoperiod; Species Specificity
Abstract The daily pattern of blood-borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the DS of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within approximately 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset and duration of nocturnal secretion.
Address Department of Psychology, and Center for Chronobiology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0109, USA. eraiewski@ucsd.edu
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Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0742-0528 ISBN Medium
Area Expedition Conference
Notes PMID:23003567 Approved no
Call Number IDA @ john @ Serial 85
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Author Zhao, N.; Cao, G.; Zhang, W.; Samson, E.L.
Title (down) Tweets or nighttime lights: Comparison for preeminence in estimating socioeconomic factors Type Journal Article
Year 2018 Publication ISPRS Journal of Photogrammetry and Remote Sensing Abbreviated Journal ISPRS Journal of Photogrammetry and Remote Sensing
Volume 146 Issue Pages 1-10
Keywords Remote Sensing
Abstract Nighttime lights (NTL) imagery is one of the most commonly used tools to quantitatively study socioeconomic systems over large areas. In this study we aim to use location-based social media big data to challenge the primacy of NTL imagery on estimating socioeconomic factors. Geo-tagged tweets posted in the contiguous United States in 2013 were retrieved to produce a tweet image with the same spatial resolution of the NTL imagery (i.e., 0.00833° × 0.00833°). Sum tweet (the total number of tweets) and sum light (summed DN value of the NTL image) of each state or county were obtained from the tweets and the NTL images, respectively, to estimate three important socioeconomic factors: personal income, electric power consumption, and fossil fuel carbon dioxide emissions. Results show that sum tweet is a better measure of personal income and electric power consumption while carbon dioxide emissions can be more accurately estimated by sum light. We further exploited that African-Americans adults are more likely than White seniors to post geotagged tweets in the US, yet did not find any significant correlations between proportions of the subpopulations and the estimation accuracy of the socioeconomic factors. Existence of saturated pixels and blooming effects and failure to remove gas flaring reduce quality of NTL imagery in estimating socioeconomic factors, however, such problems are nonexistent in the tweet images. This study reveals that the number of geo-tagged tweets has great potential to be deemed as a substitute of brightness of NTL to assess socioeconomic factors over large geographic areas.
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
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ISSN 0924-2716 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 1994
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