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Author Figura, J.; Haughwout, C.; Cahoy, K.; Welle, R.; Hardy, B.; Pack, D.; Bosh, A.
Title Initial Demonstration of an Uplink LED Beacon to a Low Earth Orbiting CubeSat Type Journal Article
Year 2018 Publication Journal of Small Satellites Abbreviated Journal
Volume 7 Issue 2 Pages 719-732
Keywords Remote Sensing
Abstract In this study, an uplink light-emitting diode (LED) beacon that can enable a CubeSat to locate a laser communication ground station was designed, constructed, and tested, and detection of the beacon from low Earth orbit (LEO) with a CMOS camera on the AeroCube-5 CubeSat was demonstrated. The LED beacon described is an alternative to the near-infrared laser beacons commonly used in laser communication systems, and has the potential to be cheaper, easier to point, and to require less regulatory coordination than a laser beacon, while performing the same function. An optical design is detailed, consisting of an array of 80 green LEDs with a center wavelength of 528 nm, producing 15.9 watts of free-space optical power, focused to a beamwidth of 8.12 degrees full-widthhalf-max (FWHM). A link budget is presented that shows the beacon is detectable by a CubeSat-mounted camera with a 7.9 mm diameter aperture and a silicon CMOS detector. A prototype beacon comprised of an LED array, focusing optics, thermal control, and tracking mechanisms was designed and constructed, and laboratory measurements of the beam profile and optical power of the prototype beacon using an optical power meter are presented herein. A field test is also described, in which the beacon was deployed at Wallace Astrophysical Observatory in the early morning of May 15, 2017 and imaged with a camera on AeroCube-5. The array is successfully identified in a sequence of five images taken by the CubeSat, demonstrating the viability of LED uplink beacons with CubeSat imagers.
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Call Number NC @ ehyde3 @ Serial 2108
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Author Min, B.; O'Keeffe, Z.; Zhang, F.
Title Whose Power Gets Cut? Using High-Frequency Satellite Images to Measure Power Supply Irregularity Type Book Whole
Year 2017 Publication Policy Research Working Papers Abbreviated Journal
Volume Issue Pages
Keywords Remote Sensing
Abstract In many parts of the developing world, access to electricity is uneven and inconsistent, characterized by frequent and long hours of power outages. Many countries now engage in systematic load shedding because of persistent power shortages. When and where electricity is provided can have important impacts on welfare and growth. But quantifying those impacts is difficult because utility-level data on power outages are rarely available and not always reliable. This paper introduces a new method of tracking power outages from outer space. This measure identifies outage-prone areas by detecting excess fluctuations in light outputs. To develop these measures, the study processed the complete historical archive of sub-orbital Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) nighttime imagery captured over South Asia on every night since 1993. The analysis computes annual estimates of the Power Supply Irregularity index for all 600,000 villages in India from 1993 to 2013. The Power Supply Irregularity index measures are consistent with ground-based measures of power supply reliability from the Indian Human Development Survey, and with feeder-level outage data from one of the largest utilities in India. The study's methods open new opportunities to study the determinants of power outages as well as their impacts on welfare.
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Publisher The World Bank Place of Publication Editor
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Call Number NC @ ehyde3 @ Serial 2109
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Author Pattison, P.M.; Tsao, J.Y.; Brainard, G.C.; Bugbee, B.
Title LEDs for photons, physiology and food Type Journal Article
Year 2018 Publication Nature Abbreviated Journal Nature
Volume 563 Issue 7732 Pages 493-500
Keywords Lighting; Human Health; Plants; Review
Abstract Lighting based on light-emitting diodes (LEDs) not only is more energy efficient than traditional lighting, but also enables improved performance and control. The colour, intensity and distribution of light can now be controlled with unprecedented precision, enabling light to be used both as a signal for specific physiological responses in humans and plants, and as an efficient fuel for fresh food production. Here we show how a broad and improved understanding of the physiological responses to light will facilitate greater energy savings and provide health and productivity benefits that have not previously been associated with lighting.
Address Utah State University, Logan, UT, USA
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Language English Summary Language Original Title
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ISSN 0028-0836 ISBN (up) Medium
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Notes PMID:30464269 Approved no
Call Number GFZ @ kyba @ Serial 2110
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Author Liu, Q.; Manning, A.J.; Duston, J.
Title Light intensity and suppression of nocturnal plasma melatonin in Arctic charr (Salvelinus alpinus) Type Journal Article
Year 2018 Publication Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology Abbreviated Journal Comp Biochem Physiol A Mol Integr Physiol
Volume in press Issue Pages
Keywords Animals
Abstract The problem of early sexual maturation among farmed Arctic charr and other salmonids can be effectively reduced by 24h light overwinter, provided it is bright enough to over-ride interference from the natural daylength cycle. To determine the threshold light intensity to suppress the nocturnal elevation of plasma melatonin, three groups of individually tagged fish (n=26-28/group ca. 1040g) were reared on 12h light: 12h dark (LD 12:12) and subjected to nighttime light intensities of either 50-65, 0.1-0.3 or 0 (control) lux for five months (November to April). Daytime light intensity was 720-750lx. Diel plasma melatonin profiles in both November and April were similar; mean daytime levels ranged from 20 to 100pg/ml, and nighttime levels were inversely proportional to light intensity. In the control group at 0lx, plasma melatonin increased about four-fold after lights-off, ranging between 320 and 430pg/ml. Nighttime light intensity of 0.1-0.3lx halved plasma melatonin levels to 140-220pg/ml, and 50-65lx further reduced the levels to one quarter of the control group, 68-108pg/ml. Among the lit groups, daytime plasma melatonin levels were about 20-30pg/ml, significantly lower than the nocturnal levels suggesting the diel hormonal rhythm was not completely abolished. Fish grew steadily from about 1100g to 1600g between November and April, independent of light intensity (P=.67). Overall, the study demonstrated the sensitivity of pineal melatonin hormone to different light intensities in Arctic charr.
Address Department of Animal Science and Aquaculture, Dalhousie University, Agricultural Campus, Truro, NS B2N 5E3, Canada
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Language English Summary Language Original Title
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ISSN 1095-6433 ISBN (up) Medium
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Notes PMID:30471350 Approved no
Call Number GFZ @ kyba @ Serial 2111
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Author Nang, E.E.K.; Abuduxike, G.; Posadzki, P.; Divakar, U.; Visvalingam, N.; Nazeha, N.; Dunleavy, G.; Christopoulos, G.I.; Soh, C.-K.; Jarbrink, K.; Soljak, M.; Car, J.
Title Review of the potential health effects of light and environmental exposures in underground workplaces Type Journal Article
Year 2019 Publication Tunnelling and Underground Space Technology Abbreviated Journal Tunnelling and Underground Space Technology
Volume 84 Issue Pages 201-209
Keywords Human Health; Review
Abstract Underground workplaces are an important element in modern urban planning. As a result, an increasing but unquantified proportion of the population is being regularly exposed to them. We narratively reviewed the literature on the range of possible environmental exposures, and the possible health effects, to identify future research directions. There is a large but mainly observational research literature on likely underground exposures, including effects of artificial lighting, shift working and light at night on circadian disruptions and associated health effects. There are five studies comparing underground and aboveground environments. Shift working, artificial lighting and poor sleep quality leading to circadian disruption is one physiologic pathway. Working underground may increase exposure to these risks, and may also be associated with vitamin D deficiency, sick building syndrome, excessive noise, radon exposure, and negative psychological effects. In order to plan appropriate interventions, we need to expand our knowledge of the health effects of underground environments. Larger and longer-term studies are required to measure a range of human factors, environmental exposures and confounders. Controlled trials with health economic analyses of new lighting technologies are also required.
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ISSN 0886-7798 ISBN (up) Medium
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Notes Approved no
Call Number GFZ @ kyba @ Serial 2112
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