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Author Ruger, M.; St Hilaire, M.A.; Brainard, G.C.; Khalsa, S.-B.S.; Kronauer, R.E.; Czeisler, C.A.; Lockley, S.W.
Title Human phase response curve to a single 6.5 h pulse of short-wavelength light Type Journal Article
Year 2013 Publication The Journal of Physiology Abbreviated Journal J Physiol
Volume 591 Issue Pt 1 Pages 353-363
Keywords Adolescent; Adult; Body Temperature; Circadian Rhythm/*physiology; Female; Humans; *Light; Male; Melatonin/physiology; Young Adult; blue light; melatonin; photic response; whort-wavelength
Abstract The photic resetting response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase response curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18-30 years) were studied for 9-10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 muW cm(-2), 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of -2.6 h and 1.3 h, respectively. The 480 nm PRC induced approximately 75% of the response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure.
Address Circadian Physiology Program, Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA. mrueger@rics.bwh.harvard.edu
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ISSN 0022-3751 ISBN Medium
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Notes PMID:23090946; PMCID:PMC3630790 Approved no
Call Number IDA @ john @ Serial (down) 239
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Author Warrant, E.J.; Johnsen, S.
Title Vision and the light environment Type Journal Article
Year 2013 Publication Current Biology : CB Abbreviated Journal Curr Biol
Volume 23 Issue 22 Pages R990-4
Keywords photobiology; animals; physiology of vision; photodetection
Abstract Almost all animals, no matter how humble, possess eyes. Only those that live in total darkness, such as in a pitch-dark cave, may lack eyes entirely. Even at tremendous depths in the ocean — where the only lights that are ever seen are rare and fitful sparks of bioluminescence — most animals have eyes, and often surprisingly well-developed eyes. And despite their diversity (there are currently ten generally recognised optical types) all eyes have evolved in response to the remarkably varied light environments that are present in the habitats where animals live. Variations in the intensity of light, as well as in its direction, colour and dominant planes of polarisation, have all had dramatic effects on visual evolution. In the terrestrial habitats where we ourselves have most recently evolved, the light environment can vary quite markedly from day to night and from one location to another. In aquatic habitats, this variation can be orders of magnitude greater. Even though the ecologies and life histories of animals have played a major role in visual evolution, it is arguably the physical limitations imposed on photodetection by a given habitat and its light environment that have defined the basic selective pressures that have driven the evolution of eyes.
Address Department of Biology, University of Lund, Solvegatan 35, S-22362 Lund, Sweden. Electronic address: Eric.Warrant@biol.lu.se
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Language English Summary Language Original Title
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Series Volume Series Issue Edition
ISSN 0960-9822 ISBN Medium
Area Expedition Conference
Notes PMID:24262832 Approved no
Call Number IDA @ john @ Serial (down) 235
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Author Small, C.; Elvidge, C.D.
Title Night on Earth: Mapping decadal changes of anthropogenic night light in Asia Type Journal Article
Year 2013 Publication International Journal of Applied Earth Observation and Geoinformation Abbreviated Journal International Journal of Applied Earth Observation and Geoinformation
Volume 22 Issue Pages 40-52
Keywords Urban; Night light; DMSP-OLS; Landsat; Zipf; Asia; India; China; Nightsat; remote sensing; light at night; satellite
Abstract The defense meteorological satellite program (DMSP) operational linescan system (OLS) sensors have imaged emitted light from Earth's surface since the 1970s. Temporal overlap in the missions of 5 OLS sensors allows for intercalibration of the annual composites over the past 19 years (Elvidge et al., 2009). The resulting image time series captures a spatiotemporal signature of the growth and evolution of lighted human settlements and development. We use empirical orthogonal function (EOF) analysis and the temporal feature space to characterize and quantify patterns of temporal change in stable night light brightness and spatial extent since 1992. Temporal EOF analysis provides a statistical basis for representing spatially abundant temporal patterns in the image time series as uncorrelated vectors of brightness as a function of time from 1992 to 2009. The variance partition of the eigenvalue spectrum combined with temporal structure of the EOFs and spatial structure of the PCs provides a basis for distinguishing between deterministic multi-year trends and stochastic year-to-year variance. The low order EOFs and principal components (PC) space together discriminate both earlier (1990s) and later (2000s) increases and decreases in brightness. Inverse transformation of these low order dimensions reduces stochastic variance sufficiently so that tri-temporal composites depict potentially deterministic decadal trends. The most pronounced changes occur in Asia. At critical brightness threshold we find an 18% increase in the number of spatially distinct lights and an 80% increase in lighted area in southern and eastern Asia between 1992 and 2009. During this time both China and India experienced a &#8764;20% increase in number of lights and a &#8764;270% increase in lighted area – although the timing of the increase is later in China than in India. Throughout Asia a variety of different patterns of brightness increase are apparent in tri-temporal brightness composites – as well as some conspicuous areas of apparently decreasing background luminance and, in many places, intermittent light suggesting development of infrastructure rather than persistently lighted development. Vicarious validation using higher resolution Landsat imagery verifies multiple phases of urban growth in several cities as well as the consistent presence of low DN (<&#8764;15) background luminance for many agricultural areas. Lights also allow us to quantify changes in the size distribution and connectedness of different intensities of development. Over a wide range of brightnesses, the size distributions of spatially contiguous lighted area are consistent with power laws with exponents near &#8722;1 as predicted by Zipf's Law for cities. However, the larger lighted segments are much larger than individual cities; they correspond to vast spatial networks of contiguous development (Small et al., 2011).
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ISSN 0303-2434 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial (down) 222
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Author Mazor, T.; Levin, N.; Possingham, H.P.; Levy, Y.; Rocchini, D.; Richardson, A.J.; Kark, S.
Title Can satellite-based night lights be used for conservation? The case of nesting sea turtles in the Mediterranean Type Journal Article
Year 2013 Publication Biological Conservation Abbreviated Journal Biological Conservation
Volume 159 Issue Pages 63-72
Keywords Artificial night lights; Caretta caretta; Chelonia mydas; Coastal conservation; Satellite imagery; Sea turtle conservation
Abstract Artificial night lights pose a major threat to multiple species. However, this threat is often disregarded in conservation management and action because it is difficult to quantify its effect. Increasing availability of high spatial-resolution satellite images may enable us to better incorporate this threat into future work, particularly in highly modified ecosystems such as the coastal zone. In this study we examine the potential of satellite night light imagery to predict the distribution of the endangered loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtle nests in the eastern Mediterranean coastline. Using remote sensing tools and high resolution data derived from the SAC-C satellite and the International Space Station, we examined the relationship between the long term spatial patterns of sea turtle nests and the intensity of night lights along Israel’s entire Mediterranean coastline. We found that sea turtles nests are negatively related to night light intensity and are concentrated in darker sections along the coast. Our resulting GLMs showed that night lights were a significant factor for explaining the distribution of sea turtle nests. Other significant variables included: cliff presence, human population density and infrastructure. This study is one of the first to show that night lights estimated with satellite-based imagery can be used to help explain sea turtle nesting activity at a detailed resolution over large areas. This approach can facilitate the management of species affected by night lights, and will be particularly useful in areas that are inaccessible or where broad-scale prioritization of conservation action is required.
Address ARC Centre of Excellence for Environmental Decisions, School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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ISSN 0006-3207 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial (down) 213
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Author Li, X.; Ge, L.; Chen, X.
Title Detecting Zimbabwe's Decadal Economic Decline Using Nighttime Light Imagery Type Journal Article
Year 2013 Publication Remote Sensing Abbreviated Journal Remote Sensing
Volume 5 Issue 9 Pages 4551-4570
Keywords Zimbabwe; economic decline; nighttime light; DMSP-OLS; remote sensing; light at night
Abstract Zimbabwe’s economy declined between 2000 and 2009. This study detects the economic decline in different regions of Zimbabwe using nighttime light imagery from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP-OLS). We found a good correlation (coefficient = 0.7361) between Zimbabwe’s total nighttime light (TNL) and Gross Domestic Product (GDP) for the period 1992 to 2009. Therefore, TNL was used as an indicator of regional economic conditions in Zimbabwe. Nighttime light imagery from 2000 and 2008 was compared at both national and regional scales for four types of regions. At the national scale, we found that nighttime light in more than half of the lit area decreased between 2000 and 2008. Moreover, within the four region types (inland mining towns, inland agricultural towns, border towns and cities) we determined that the mining and agricultural sectors experienced the most severe economic decline. Some of these findings were validated by economic survey data, proving that the nighttime light data is a potential data source for detecting the economic decline in Zimbabwe.
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ISSN 2072-4292 ISBN Medium
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Notes Approved no
Call Number IDA @ john @ Serial (down) 212
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