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| Author |
Konkal, P.; Ganesh, C.B. |
| Title |
Exposure to low or high light intensity affects pituitary-testicular activity in the fish Oreochromis mossambicus |
Type |
Journal Article |
| Year |
2018 |
Publication |
Aquaculture |
Abbreviated Journal |
Aquaculture |
Volume  |
497 |
Issue |
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Pages |
109-116 |
| Keywords |
Animals |
| Abstract |
Light is an important factor for the successful reproduction of most fish. In this investigation, effect of different light intensities on pituitary-testis axis was studied for a period of 21 days, under normal photoperiodic regime in the tilapia Oreochromis mossambicus. The mean numbers of spermatogonia (Sg), primary spermatocytes (Ps), secondary spermatocytes (Ss), early spermatids (Est) and late spermatids (Lst) did not show significant difference between fish exposed to moderate light intensity (MLI) and initial controls or controls, whereas the mean numbers of Sg were significantly lower in fish exposed to low light intensity (LLI) compared to those of initial controls, controls and MLI groups. However, the mean numbers of Ps, Ss, Est and Lst were significantly lower in fish exposed to LLI and high light intensity (HLI) compared to those of other experimental groups. Furthermore, in the pituitary gland, weakly immunoreactive luteinizing hormone (LH) secreting cells were observed in the proximal pars distalis (PPD) region in fish exposed to LLI and HLI in contrast to the intense immunolabelling of these cells in initial controls, controls and MLI groups. The androgen receptors showed diminished immunoreactivity in the Sertoli cells along the seminiferous lobules of the testis in fish exposed to LLI and HLI, whereas the strongly immunoreactive androgen receptors were observed in the Sertoli cells in initial controls, controls and MLI groups. Taken together, these results indicate that long-term exposure to low or high light intensity light suppresses spermatogenetic process and that this inhibition is due to reduced secretory activity of LH cells in the pituitary gland and androgen secretion in the testis of the fish O. mossambicus. |
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0044-8486 |
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GFZ @ kyba @ |
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1974 |
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Kocifaj, M.; Kómar, L.; Lamphar, H.; Wallner, S. |
| Title |
Are population-based models advantageous in estimating the lumen outputs from light-pollution sources? |
Type |
Journal Article |
| Year |
2020 |
Publication |
Monthly Notices of the Royal Astronomical Society: Letters |
Abbreviated Journal |
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| Volume |
496 |
Issue |
1 |
Pages |
L138-L141 |
| Keywords |
Remote Sensing |
| Abstract |
The total lumen output (TLO) from ground-based artificial light sources is required in a wide range of light-pollution models currently in use. No realistic assessment of diffuse light levels in the nocturnal environment is possible if the information on TLO is missing. Traditional approaches to skyglow modelling, if no lighting inventory is available, foresee to estimate TLO based on population and average amount of lumens per capita. However, we show in this letter that a model based on the area of artificially lit surfaces can reduce uncertainties in estimating TLO by 25 per cent for compact urban areas of defined centres and autonomous character and even 50 per cent for diffuse cities with small satellite towns interacting closely with the main city. The new model could be of great significance to the community of light-pollution researchers, especially astronomers, physicists, and modellers who use TLO routinely in light-pollution characterization. |
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1745-3925 |
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UP @ altintas1 @ |
Serial |
3181 |
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| Author |
Kocifaj, M.; Bará, S. |
| Title |
Aerosol characterization using satellite remote sensing of light pollution sources at night |
Type |
Journal Article |
| Year |
2020 |
Publication |
Monthly Notices of the Royal Astronomical Society: Letters |
Abbreviated Journal |
MNRAS |
| Volume |
495 |
Issue |
1 |
Pages |
L76-L80 |
| Keywords |
Skyglow; Radiative transfer; Light scattering; Aerosols |
| Abstract |
A demanding challenge in atmospheric research is the night-time characterization of aerosols using passive techniques, that is, by extracting information from scattered light that has not been emitted by the observer. Satellite observations of artificial night-time lights have been used to retrieve some basic integral parameters, like the aerosol optical depth. However, a thorough analysis of the scattering processes allows one to obtain substantially more detailed information on aerosol properties. In this letter, we demonstrate a practicable approach for determining the aerosol particle size number distribution function in the air column, based on the measurement of the angular radiance distribution of the scattered light emitted by night- time lights of cities and towns, recorded from low Earth orbit. The method is self-calibrating and does not require the knowledge of the absolute city emissions. The input radiance data are readily available from several spaceborne platforms, like the VIIRS-DNB radiometer onboard the Suomi-NPP satellite. |
| Address |
Faculty of Mathematics, Physics, and Informatics, Comenius University, Mlynska Dolina, 842 48 Bratislava, Slovakia; Miroslav.Kocifaj(at)savba.sk |
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OUP |
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English |
Summary Language |
English |
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1745-3925 |
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IDA @ john @ |
Serial |
2910 |
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Wallner, S.; Kocifaj, M.; Komar, L.; Solano-Lamphar, H.A. |
| Title |
Night-sky imaging as a potential tool for characterization of total lumen output from small and medium-sized cities |
Type |
Journal Article |
| Year |
2020 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
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| Volume |
494 |
Issue |
4 |
Pages |
5008-5017 |
| Keywords |
Skyglow |
| Abstract |
In this article, the asymptotic formula developed in past work and applied to predict skyglow due to distant sources was evolved, with the objective of characterizing small and medium-sized cities in the observer's surroundings. To enable this, a combination of theoretical computations and in situ measurements is needed, aiming to distinguish between dominant and smaller light-emitting sources, with the latter usually being camouflaged when measuring the night sky. Furthermore, for numerical modelling of skyglow, few of the most important parameters, specifically the amount of total lumens installed and radiated to the upward hemisphere, can be derived. Astronomical observatories, in particular, can profit from this concept, since they are usually situated far away from large cities but can still be surrounded by smaller villages and towns. We present a detailed description of how theoretical computations are combined with all-sky photometry in order to obtain the properties mentioned. Results are compared with satellite data, showing that, regarding approximations undertaken for processing, they are comparable, underlining the functionality of our approach. The idea of including in situ observations enables us to quantify the impact of small and medium-sized cities globally and independent of location, as long as measurements were conducted outside light domes. In addition, the presented work may be of major interest to the light-pollution community if conducting long-term observations of cities, since the quality of commonly used satellite data is going to decrease in the future, due to blindness in short wavelengths and upcoming conversions of public lighting systems to blue-enlightened LEDs. |
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0035-8711 |
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no |
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GFZ @ kyba @ |
Serial |
2911 |
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| Author |
Bará, S.; Aubé, M.; Barentine, J.; Zamorano, J. |
| Title |
Magnitude to luminance conversions and visual brightness of the night sky |
Type |
Journal Article |
| Year |
2020 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
MNRAS |
| Volume |
493 |
Issue |
2 |
Pages |
2429–2437 |
| Keywords |
Skyglow; light pollution; atmospheric effects; techniques: photometric; methods: numerical; luminance |
| Abstract |
The visual brightness of the night sky is not a single-valued function of its brightness in other photometric bands, because the transformations between photometric systems depend on the spectral power distribution of the skyglow. We analyze the transformation between the night sky brightness in the Johnson-Cousins V band (mV, measured in magnitudes per square arcsecond, mpsas) and its visual luminance (L, in SI units cd m−2) for observers with photopic and scotopic adaptation, in terms of the spectral power distribution of the incident light. We calculate the zero-point luminances for a set of skyglow spectra recorded at different places in the world, including strongly light-polluted locations and sites with nearly pristine natural dark skies. The photopic skyglow luminance corresponding to mV = 0.00 mpsas is found to vary between 1.11–1.34 × 105 cd m−2 if mV is reported in the absolute (AB) magnitude scale, and between 1.18–1.43 × 105 cd m−2 if a Vega scale for mV is used instead. The photopic luminance for mV = 22.0 mpsas is correspondingly comprised between 176 and 213 μcd m−2 (AB), or 187 and 227 μcd m−2 (Vega). These constants tend to decrease for increasing correlated color temperatures (CCT). The photopic zero-point luminances are generally higher than the ones expected for blackbody radiation of comparable CCT. The scotopic-to-photopic luminance ratio (S/P) for our spectral dataset varies from 0.8 to 2.5. Under scotopic adaptation the dependence of the zero-point luminances with the CCT, and their values relative to blackbody radiation, are reversed with respect to photopic ones. |
| Address |
Departamento de Física Aplicada, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia; salva.bara(at)usc.gal |
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Oxford Academic |
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English |
Summary Language |
English |
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IDA @ john @ |
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2825 |
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