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Author |
Kocifaj, M.; Kómar, L. |
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Title |
A role of aerosol particles in forming urban skyglow and skyglow from distant cities |
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Journal Article |
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Year |
2016 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
MNRAS |
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Volume |
458 |
Issue |
1 |
Pages |
438-448 |
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Keywords |
Skyglow; scattering; atmospheric effects; artificial light; numerical modeling; GIS-based modeling; light pollution |
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Abstract  |
Aerosol particles may represent the largest uncertainty about skyglow change in many locations under clear sky conditions. This is because aerosols are ubiquitous in the atmosphere and influence the ground-reaching radiation in different ways depending on their concentrations, origins, shapes, sizes, and compositions. Large particles tend to scatter in Fraunhofer diffraction regime, while small particles can be treated in terms of Rayleigh formalism. However, the role of particle microphysics in forming the skyglow still remains poorly quantified. We have shown in this paper that the chemistry is somehow important for backscattering from large particles that otherwise work as efficient attenuators of light pollution if composed of absorbing materials. The contribution of large particles to the urban skyglow diminishes as they become more spherical in shape. The intensity of backscattering from non-absorbing particles is more-or-less linearly decreasing function of particle radius even if number size distribution is inversely proportional to the fourth power of particle radius. This is due to single particle backscattering that generally increases steeply as the particle radius approaches large values. Forward scattering depends on the particle shape but is independent of the material composition, thus allowing for a simplistic analytical model of skyglow from distant cities. The model we have developed is based on mean value theorem for integrals and incorporates the parametrizable Garstang's emission pattern, intensity decay along optical beam path, and near-forward scattering in an atmospheric environment. Such model can be used by modellers and experimentalists for rapid estimation of skyglow from distant light sources. |
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ICA, Slovak Academy of Sciences, Dúbravská Road 9, 845 03 Bratislava, Slovak Republic; kocifaj(at)savba.sk |
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Oxford Journals |
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English |
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English |
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IDA @ john @ |
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1361 |
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Author |
Jiang, S.; Wei, G.; Zhang, Z.; Wang, Y.; Xu, M.; Wang, Q.; Das, P.; Liu, B. |
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Title |
Detecting the Dynamics of Urban Growth in Africa Using DMSP/OLS Nighttime Light Data |
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Journal Article |
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Year |
2021 |
Publication |
Land |
Abbreviated Journal |
Land |
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10 |
Issue |
1 |
Pages |
13 |
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Keywords |
Remote Sensing |
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Abstract |
Africa has been experiencing a rapid urbanization process, which may lead to an increase in unsustainable land use and urban poverty. Assessing the spatiotemporal characteristics of urbanization dynamics is especially important and needed for the sustainable development of Africa. Satellite-based nighttime light (NTL) data are widely used to monitor the dynamics of urban growth from global to local scales. In this study, urban growth patterns across Africa were analyzed and discussed using stable nighttime light datasets obtained from DMSP/OLS (the Defense Meteorological Satellite Program’s Operational Line-scan System) spanning from 1992 to 2013. We partitioned the nighttime lighting areas into three types (low, medium, and high) using thresholds derived from the Brightness Gradient (BG) method. Our results indicated that built-up areas in Africa have increased rapidly, particularly those areas with low nighttime lighting types. Countries with higher urbanization levels in Africa, like South Africa, Algeria, Egypt, Nigeria, and Libya, were leading the brightening trend. The distribution of nighttime lighting types was consistent with the characteristics of urban development, with high nighttime lighting types showed up at the urban center, whereas medium and low nighttime lighting types appeared in the urban-rural transition zone and rural areas respectively. The impacts of these findings on the future of African cities will be further proposed. |
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2073-445X |
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GFZ @ kyba @ |
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3233 |
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Author |
Wang, J.; Qu, S.; Peng, K.; Feng, Y. |
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Title |
Quantifying Urban Sprawl and Its Driving Forces in China |
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Journal Article |
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2019 |
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Discrete Dynamics in Nature and Society |
Abbreviated Journal |
Discrete Dynamics in Nature and Society |
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2019 |
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1-14 |
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Keywords |
Remote Sensing |
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Abstract |
Against the background that urbanization has proceeded quickly in China over the last two decades, a limited number of empirical researches have been performed for analyzing the measurement and driving forces of urban sprawl at the national and regional level. The article aims at using remote sensing derived data and administrative data (for statistical purposes) to investigate the development status of urban sprawl together with its driving forces. Compared with existing studies, NPP/VIIRS data and LandScan data were used here to examine urban sprawl from two different perspectives: urban population sprawl and urban land sprawl. Furthermore, we used population density as a counter-indicator of urban sprawl, and the regression results also prove the superiority of the urban sprawl designed by us. The main results show that the intensity of urban population sprawl and urban land sprawl has been enhanced. However, the upside-down between the inflow of migrants and the supply of urban construction land among different regions aggravates the intensity of urban sprawl. According to the regression analyses, the driving mechanism of urban sprawl in the eastern region relying on land finance and financial development has lost momentum for the limitation of urban construction land supply. The continuous outflow of population and loosely land supply have accelerated the intensity of urban land sprawl in the central and western regions. The findings of the article may help people to realize that urban sprawl has become a staggering reality among Chinese cities; thereby urban planners as well as policymakers should make some actions to hinder the urban sprawl. |
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1026-0226 |
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GFZ @ kyba @ |
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2379 |
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Alaimo, A.; Linares, G.G.; Bujjamer, J.M.; Gorojod, R.M.; Alcon, S.P.; Martinez, J.H.; Baldessari, A.; Grecco, H.E.; Kotler, M.L. |
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Title |
Toxicity of blue led light and A2E is associated to mitochondrial dynamics impairment in ARPE-19 cells: implications for age-related macular degeneration |
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Journal Article |
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Year |
2019 |
Publication |
Archives of Toxicology |
Abbreviated Journal |
Arch Toxicol |
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93 |
Issue |
5 |
Pages |
1401-1415 |
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Keywords |
Vision; age-related macular degeneration; Eye; Eye Diseases; blue light |
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Age-related macular degeneration (AMD) is a multifactorial retinal disease characterized by a progressive loss of central vision. Retinal pigment epithelium (RPE) degeneration is a critical event in AMD. It has been associated to A2E accumulation, which sensitizes RPE to blue light photodamage. Mitochondrial quality control mechanisms have evolved to ensure mitochondrial integrity and preserve cellular homeostasis. Particularly, mitochondrial dynamics involve the regulation of mitochondrial fission and fusion to preserve a healthy mitochondrial network. The present study aims to clarify the cellular and molecular mechanisms underlying photodamage-induced RPE cell death with particular focus on the involvement of defective mitochondrial dynamics. Light-emitting diodes irradiation (445 +/- 18 nm; 4.43 mW/cm(2)) significantly reduced the viability of both unloaded and A2E-loaded human ARPE-19 cells and increased reactive oxygen species production. A2E along with blue light, triggered apoptosis measured by MC540/PI-flow cytometry and activated caspase-3. Blue light induced mitochondrial fusion/fission imbalance towards mitochondrial fragmentation in both non-loaded and A2E-loaded cells which correlated with the deregulation of mitochondria-shaping proteins level (OPA1, DRP1 and OMA1). To our knowledge, this is the first work reporting that photodamage causes mitochondrial dynamics deregulation in RPE cells. This process could possibly contribute to AMD pathology. Our findings suggest that the regulation of mitochondrial dynamics may be a valuable strategy for treating retinal degeneration diseases, such as AMD. |
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Address |
Departamento de Quimica Biologica, Facultad de Ciencias Exactas y Naturales, Instituto de Quimica Biologica Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Pabellon 2, Ciudad Universitaria, 1428, Buenos Aires, Argentina. kotler@qb.fcen.uba.ar |
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0340-5761 |
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PMID:30778631 |
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GFZ @ kyba @ |
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2229 |
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Author |
Secondi, J.; Davranche, A.; Théry, M.; Mondy, N.; Lengagne, T.; Isaac, N. |
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Title |
Assessing the effects of artificial light at night on biodiversity across latitude – Current knowledge gaps |
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Journal Article |
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2019 |
Publication |
Global Ecology and Biogeography |
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Global Ecol Biogeogr |
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in press |
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geb.13037 |
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Ecology; biodiversity; Review |
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Abstract |
Aim
Exposure to artificial light at night (ALAN) is a risk factor for organisms. Considering the spread and increasing intensity of night brightness across the globe, and the key role of light at all biological levels, alterations of ecosystems are expected. Yet, we cannot predict the severity of the effects of ALAN in several biomes because little information is available outside the temperate zone. We reviewed current knowledge and identified traits that could be targeted to fill this knowledge gap in order to contribute to the elaboration of a biogeographical framework for the study of ALAN at the global scale.
Location
Global.
Time period
Current and next decades.
Methods
We analysed the latitudinal variation in ALAN and focused on environmental factors that vary with latitude but that have been overlooked. We reviewed biological traits that exhibit latitudinal variation and depend on light and photoperiod and compiled information about the predicted changes in human demography and road networks across different world regions.
Results
Cloud cover amplifies ALAN far away from urbanized areas. Because of the higher frequency of overcast sky nights, exposure effects may be stronger both at high latitudes and across a large fraction of the intertropical zone, although at different times of the year. Intertropical biomes host the largest fraction of global biodiversity. Although currently they are not the most exposed to ALAN, their human populations are growing, and urbanized areas and road networks are expanding. Hence, ALAN could have strong ecological consequences, with cloud cover as an aggravating factor.
Perspectives
Knowledge gaps currently limit our ability to predict the effects of ALAN in different biomes. Therefore, it will be important to start investigating the consequences of this novel environmental factor across the globe, in order to develop a relevant theoretical framework. |
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Corporate Author |
Wiley |
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English |
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English |
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1466-822X |
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GFZ @ kyba @ |
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2758 |
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