| Records |
| Author |
Dacke, M.; Byrne, M.J.; Baird, E.; Scholtz, C.H.; Warrant, E.J. |
| Title |
How dim is dim? Precision of the celestial compass in moonlight and sunlight |
Type |
Journal Article |
| Year |
2011 |
Publication |
Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |
Abbreviated Journal |
Philos Trans R Soc Lond B Biol Sci |
| Volume |
366 |
Issue |
1565 |
Pages |
697-702 |
| Keywords |
Animals; Beetles/*physiology; Behavior, Animal; *Moon; *Sunlight; Video Recording |
| Abstract |
Prominent in the sky, but not visible to humans, is a pattern of polarized skylight formed around both the Sun and the Moon. Dung beetles are, at present, the only animal group known to use the much dimmer polarization pattern formed around the Moon as a compass cue for maintaining travel direction. However, the Moon is not visible every night and the intensity of the celestial polarization pattern gradually declines as the Moon wanes. Therefore, for nocturnal orientation on all moonlit nights, the absolute sensitivity of the dung beetle's polarization detector may limit the precision of this behaviour. To test this, we studied the straight-line foraging behaviour of the nocturnal ball-rolling dung beetle Scarabaeus satyrus to establish when the Moon is too dim--and the polarization pattern too weak--to provide a reliable cue for orientation. Our results show that celestial orientation is as accurate during crescent Moon as it is during full Moon. Moreover, this orientation accuracy is equal to that measured for diurnal species that orient under the 100 million times brighter polarization pattern formed around the Sun. This indicates that, in nocturnal species, the sensitivity of the optical polarization compass can be greatly increased without any loss of precision. |
| Address |
Department of Biology, University of Lund, Helgonavagen 3, 223 62 Lund, Sweden. marie.dacke@cob.lu.se |
| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0962-8436 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
PMID:21282173; PMCID:PMC3049003 |
Approved |
no |
| Call Number |
IDA @ john @ |
Serial |
34 |
| Permanent link to this record |
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| Author |
Fiorentin, P.; Boscaro, F. |
| Title |
A method for measuring the light output of video advertising reproduced by LED billboards |
Type |
Journal Article |
| Year |
2019 |
Publication |
Measurement |
Abbreviated Journal |
Measurement |
| Volume |
138 |
Issue |
|
Pages |
25-33 |
| Keywords |
Lighting; Energy; Instrumentation; Planning; Light-emitting diode displays; Photometry; Video recording; Image analysis; CCD image sensors; Luminance; Glare |
| Abstract |
Improving knowledge of the light output of digital billboards is important to better assess their effect on driver distraction when they are installed along roads. In this work the emission of an LED based billboard is measured when playing advertising video-clips. In particular the average and the maximum values of the luminance are evaluated. The same video-clips are also analyzed when shown on an LCD monitor, aiming at separating the variability of the videos and of the playing device. The results allow to evaluate an utilization factor of the billboard: the videos have an average luminance around 11% and a peak luminance of 35% of the maximum luminance obtainable from the billboard. The power consumption of the billboard is measured, aside the photometric analysis. The luminance of the device are found linearly dependent on both the power and the effective current absorbed by the device from the grid, with a discrepancy within 6%. It could be a useful information for billboard manufacturers to qualify their product when they do not own photometric instruments. |
| Address |
Department of Industrial Engineering, University of Padova, Padova, Italy; pietro.fiorentin(at)unipd.it |
| Corporate Author |
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Thesis |
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| Publisher |
Elsevier |
Place of Publication |
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Editor |
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| Language |
English |
Summary Language |
English |
Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0263-2241 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
no |
| Call Number |
GFZ @ kyba @ |
Serial |
2214 |
| Permanent link to this record |
