| Records |
| Author |
Zhao, N., Zhang, W., Liu, Y., Samson, E. L., Chen, Y., & Cao, G. |
Title  |
Improving Nighttime Light Imagery With Location-Based Social Media Data |
Type |
Journal Article |
| Year |
2018 |
Publication |
IEEE Transactions on Geoscience and Remote Sensing |
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| Volume |
57 |
Issue |
4 |
Pages |
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| Keywords |
Remote Sensing |
| Abstract |
Location-based social media have been extensively utilized in the concept of “social sensing” to exploit dynamic information about human activities, yet joint uses of social sensing and remote sensing images are underdeveloped at present. In this paper, the close relationship between the number of Twitter users and brightness of nighttime lights (NTL) over the contiguous United States is calculated and geotagged tweets are then used to upsample a stable light image for 2013. An associated outcome of the upsampling process is the solution of two major problems existing in the NTL image, pixel saturation, and blooming effects. Compared with the original stable light image, digital number (DN) values of the upsampled stable light image have larger correlation coefficients with gridded population (0.47 versus 0.09) and DN values of the new generation NTL image product (0.56 versus 0.52), i.e., the Visible Infrared Imaging Radiometer Suite day/night band image composite. In addition, total personal incomes of states are disaggregated to each pixel in proportion to the DN value of the pixel in the NTL images and then aggregate by counties. Personal incomes distributed by the upsampled NTL image are closer to the official demographic data than those distributed by the original stable light image. All of these results explore the potential of geotagged tweets to improve the quality of NTL images for more accurately estimating or mapping socioeconomic factors. |
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IDA @ intern @ |
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2353 |
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Neri, L.; Coscieme, L.; Giannetti, B.F.; Pulselli, F.M. |
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Imputing missing data in non-renewable empower time series from night-time lights observations |
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Journal Article |
| Year |
2018 |
Publication |
Ecological Indicators |
Abbreviated Journal |
Ecological Indicators |
| Volume |
84 |
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Pages |
106-118 |
| Keywords |
Remote Sensing |
| Abstract |
Emergy is an environmental accounting tool, with a specific set of indicators, that proved to be highly informative for sustainability assessment of national economies. The empower, defined as emergy per unit time, is a measure of the overall flow of resources used by a system in order to support its functioning. Continuous time-series of empower are not available for most of the world countries, due to the large amount of data needed for its calculation year by year. In this paper, we aim at filling this gap by means of a model that facilitates reconstruction of continuous time series of the non-renewable component of empower for a set of 57 countries of the world from 1995 to 2012. The reconstruction is based on a 3 year global emergy dataset and on the acknowledged relationships between the use of non-renewables, satellite observed artificial lights emitted at night, and Gross Domestic Product. Results show that this method provides accurate estimations of non-renewable empower at the country scale. The estimation model can be extended onward and backward in time and replicated for more countries, also using higher-resolution satellite imageries newly available. Besides representing an important advancement in emergy theory, this information is helpful for monitoring progresses toward Sustainable Development and energy use international goals. |
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1470160X |
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LoNNe @ kyba @ |
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1706 |
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Watson, L.A.; Phillips, A.J.K.; Hosken, I.T.; McGlashan, E.M.; Anderson, C.; Lack, L.C.; Lockley, S.W.; Rajaratnam, S.M.W.; Cain, S.W. |
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Increased sensitivity of the circadian system to light in delayed sleep-wake phase disorder |
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Journal Article |
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2018 |
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The Journal of Physiology |
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J Physiol |
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in press |
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Human Health |
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KEY POINTS: This is the first study to demonstrate an altered circadian phase shifting response in a circadian rhythm sleep disorder. Patients with Delayed Sleep-Wake Phase Disorder (DSWPD) demonstrate greater sensitivity of the circadian system to the phase delaying effects of light. Increased circadian sensitivity to light is associated with later circadian timing within both control and DSWPD groups. DSWPD patients had a greater sustained pupil response after light exposure. Treatments for DSWPD should consider sensitivity of the circadian system to light as a potential underlying vulnerability, making patients susceptible to relapse. ABSTRACT: Patients with Delayed Sleep-Wake Phase Disorder (DSWPD) exhibit delayed sleep-wake behavior relative to desired bedtime, often leading to chronic sleep restriction and daytime dysfunction. The majority of DSWPD patients also display delayed circadian timing in the melatonin rhythm. Hypersensitivity of the circadian system to phase delaying light is a plausible physiological basis for DSWPD vulnerability. We compared the phase shifting response to a 6.5-h light exposure ( approximately 150 lux) between male patients with diagnosed DSWPD (n = 10; aged 22.4 +/- 3.3 years) and male healthy controls (n = 11; aged 22.4 +/- 2.4 years). Salivary dim light melatonin onset (DLMO) was measured under controlled conditions in dim light (<3 lux) before and after light exposure. Correcting for the circadian time of the light exposure, DSWPD patients exhibited 31.5% greater phase delay shifts than healthy controls. In both groups, a later initial phase of the melatonin rhythm was associated with greater magnitude of phase shifts, indicating that increased circadian sensitivity to light may be a factor that contributes to delayed phase, even in non-clinical groups. DSWPD patients also had reduced pupil size following the light exposure, and showed a trend towards increased melatonin suppression during light exposure. These findings indicate that, for patients with DSWPD, assessment of light sensitivity may be an important factor that can inform behavioral therapy, including minimization of exposure to phase-delaying night-time light. This article is protected by copyright. All rights reserved. |
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Monash Institute of Cognitive and Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia |
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English |
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0022-3751 |
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PMID:30281150 |
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no |
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GFZ @ kyba @ |
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2026 |
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Brüning, A.; Kloas, W.; Preuer, T.; Hölker, F. |
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Influence of artificially induced light pollution on the hormone system of two common fish species, perch and roach, in a rural habitat |
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Journal Article |
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2018 |
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Conservation Physiology |
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6 |
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1 |
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Animals |
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Almost all life on earth has adapted to natural cycles of light and dark by evolving circadian and circannual rhythms to synchronize behavioural and physiological processes with the environment. Artificial light at night (ALAN) is suspected to interfere with these rhythms. In this study we examined the influence of ALAN on nocturnal melatonin and sex steroid blood concentrations and mRNA expression of gonadotropins in the pituitary of European perch (Perca fluviatilis) and roach (Rutilus rutilus). In a rural experimental setting, fish were held in net cages in drainage channels experiencing either additional ALAN of ~15 lx at the water surface or natural light conditions at half-moon. No differences in melatonin concentrations between ALAN and natural conditions were detected. However, blood concentration of sex steroids (17β-estradiol; 11-ketotestosterone) as well as mRNA expression of gonadotropins (luteinizing hormone, follicle stimulating hormone) was reduced in both fish species. We conclude that ALAN can disturb biological rhythms in fish in urban waters. However, impacts on melatonin rhythm might have been blurred by individual differences, sampling methods and moonlight. The effect of ALAN on biomarkers of reproduction suggests a photo-labile period around the onset of gonadogenesis, including the experimental period (August). Light pollution therefore has a great potential to influence crucial life history traits with unpredictable outcome for fish population dynamics. |
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2051-1434 |
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GFZ @ kyba @ |
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1858 |
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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 |
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Journal Article |
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2018 |
Publication |
Journal of Small Satellites |
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7 |
Issue |
2 |
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719-732 |
| Keywords |
Remote Sensing |
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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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NC @ ehyde3 @ |
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