Cegep de Sherbrooke

Sherbrooke, Canada

Cegep de Sherbrooke

Sherbrooke, Canada

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Aube M.,Cegep de Sherbrooke | Kocifaj M.,Slovak Academy of Sciences | Kocifaj M.,Comenius University | Zamorano J.,Complutense University of Madrid | And 2 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2016

Artificial Light at Night (ALAN) may have various environmental impacts ranging from compromising the visibility of astronomical objects to the perturbation of circadian cycles in animals and humans. In the past much research has been carried out to study the impact of ALAN on the radiance of the night sky during clear sky conditions. This was mainly justified by the need for a better understanding of the behavior of ALAN propagation into the environment in order to protect world-class astronomical facilities. More recently, alongside to the threat to the natural starry sky, many issues have emerged from the biological science community. It has been shown that, nearby or inside cities, the presence of cloud cover generally acts as an amplifier for artificial sky radiance while clouds behave as attenuators for remote observers. In this paper we show the spectral behavior of the zenith sky radiance amplification factor exerted by clouds inside a city. We compare in-situ measurements made with the spectrometer SAND-4 with a numerical model applied to the specific geographical context of the Universidad Complutense de Madrid in Spain. © 2016 Elsevier Ltd.


Aube M.,Cegep de Sherbrooke
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2015

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane. © 2015 The Authors. All rights reserved.


Kocifaj M.,Slovak Academy of Sciences | Aube M.,CEGEP de Sherbrooke | Kohut I.,Slovak Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2010

Nowadays, light pollution is a permanent problem at many observatories around the world. Elimination of excessive lighting during the night is not only about reduction of the total luminous power of ground-based light sources, but also involves experimenting with the spectral features of single lamps. Astronomical photometry is typically made at specific wavelengths, and thus the analysis of the spectral effects of light pollution is highly important. Nevertheless, studies on the spectral behaviour of night light are quite rare. Instead, broad-band or integral quantities (such as sky luminance) are preferentially measured and modelled. The knowledge of night-light spectra is necessary for the proper interpretation of narrow-band photometry data. In this paper, the night-sky radiances in the nominal spectral lines of the B (445 nm) and V (551 nm) filters are determined numerically under clear-sky conditions. Simultaneously, the corresponding sky-luminance patterns are computed and compared against the spectral radiances. It is shown that spectra, patterns and distances of the most important light sources (towns) surrounding an observatory are essential for determining the light pollution levels. In addition, the optical characteristics of the local atmosphere can change the angular behaviour of the sky radiance or luminance. All these effects are evaluated for two Slovakian observatories: Stará Lesná and Vartovka. © 2010 The Authors. Journal compilation © 2010 RAS.


Desroches J.-F.,Cegep de Sherbrooke | Schueler F.W.,Bishops Mills Natural History Center
Canadian Field-Naturalist | Year: 2010

In May-June 2002, as part of a survey of a variety of taxa in the James Bay region of Ontario and Québec, we surveyed the poorly documented herpetofauna of this region. In Ontario we visited sites near Moosonee that FWS had previously surveyed in 1971-1972, and continued ongoing herpetological monitoring around Cochrane. In Québec we surveyed the inland James Bay Road, and roads to four settlements along the coast. American Toad (Anaxyrus americanus), Spring Peeper (Pseudacris crucifer), and Wood Frog (Lithobates sylvaticus) were widespread and abundant throughout. Blue-spotted Salamander (Ambystoma laterale) and Garter Snake (Thamnophis sirtalis) were widespread and common in Québec and at the study site near Cochrane. We obtained the first taped calls and voucher specimen of the Boreal Chorus Frog (Pseudacris maculata) from Québec, and failed to find it at the settlement and airport of Moosonee where it had been present in 1972. A significant range extension was for the Two-lined Salamander (Eurycea bislineata), which we found 200 km north of its previously known range in northwestern Québec. Despite extensive searches, the species was not found north of 52°05'N. The Mink Frog (Lithobates septentrionalis) was widespread and relatively common in Québec, but was sought but not found in Ontario. The Leopard Frog (Lithobates pipiens) was only found at two Québec sites, including one where it was reported in 1974, but it has not been found at any of the Ontario sites where it was found in the 1970's. We present some suggestions for the further study of the herpetofauna of the area, and review evidence for contacts between eastern and western lineages of widespread species.


Aube M.,Cegep de Sherbrooke | Kocifaj M.,Slovak Academy of Sciences
Monthly Notices of the Royal Astronomical Society | Year: 2012

Astronomical observations are increasingly limited by light pollution, which is a product of the over-illumination of the night sky. To predict both the angular distribution of scattered light and the ground-reaching radiative fluxes, a set of models has been introduced in recent decades. Two distinct numerical tools, MSNsR Au and ILLUMINA, are compared in this paper, with the aim of identifying their strengths and weaknesses. The numerical experiment comprises the simulation of spectral radiances in the region of the Canary Islands. In particular, the light fields near the Roque de los Muchachos and Teide observatories are computed under various turbidity conditions. It is shown that ILLUMINA has enhanced accuracy at low elevation angles. However, ILLUMINA is time-consuming because of the two scattering orders incorporated into the calculation scheme. Under low-turbidity conditions and for zenith angles smaller than 70° the two models agree well, and thus can be successfully applied to typical cloudless situations at the majority of observatories. MSNsR Au is well optimized for large-scale simulations. In particular, the grid size is adapted dynamically depending on the distance between a light source and a hypothetical observer. This enables rapid numerical modelling for large territories. MSNsR Au is also well suited for the mass modelling of night-sky radiances after ground-based light sources are hypothetically changed. This enables an optimum design of public lighting systems and a time-efficient evaluation of the optical effects related to different lamp spectra or different lamp distributions. ILLUMINA provides two diagnostic geographical maps to help local authorities concerned about light-pollution control. The first map allows the identification of the relative contribution of each ground element to the observed sky radiance at a given viewing angle, while the second map gives the sensitivity, basically saying how each ground element contributes per lumen installed. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.


Aube M.,Cegep de Sherbrooke | Roby J.,Cegep de Sherbrooke | Kocifaj M.,Slovak Academy of Sciences
PLoS ONE | Year: 2013

Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies. © 2013 Aubé et al.


Baillargeon P.,Cegep de Sherbrooke | Caron-Duval E.,Cegep de Sherbrooke | Pellerin E.,Cegep de Sherbrooke | Gagne S.,Cegep de Sherbrooke | Dory Y.L.,Université de Sherbrooke
Crystals | Year: 2016

Isomorphous crystals of two diacetylene derivatives with carbamate functionality (BocNH-CH2-diyne-X, where X = H or Br) have been obtained. The main feature of these structures is the original 2D arrangement (as supramolecular sheets or walls) in which the H bond and halogen bond have a prominent effect on the whole architecture. The two diacetylene compounds harbor neighboring carbamate (Boc protected amine) and conjugated alkyne functionalities. They differ only by the nature of the atom located at the penultimate position of the diyne moiety, either a hydrogen atom or a bromine atom. Both of them adopt very similar 2D wall organizations with antiparallel carbamates (as in antiparallel beta pleated sheets). Additional weak interactions inside the same walls between molecular bricks are H bond interactions (diyne-H…O=C) or halogen bond interactions (diyne-Br…O=C), respectively. Based on crystallographic atom coordinates, DFT (B3LYP/6-31++G(d,p)) and DFT (M06-2X/6-31++G(d,p)) calculations were performed on these isostructural crystals to gain insight into the intermolecular interactions. © 2016 by the authors; licensee MDPI, Basel, Switzerland.


Aube M.,Cegep de Sherbrooke | Roby J.,Cegep de Sherbrooke
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2014

In 2007, the area around the Mont-Mégantic Observatory (MMO) was officially certified by the International Dark-Sky Association and the Royal Astronomy Association of Canada as the first International Dark Sky Reserve (IDSR). In order to be able to investigate the impact of Artificial Light at Night on night sky brightness before and after the establishment of the IDSR, we used a heterogeneous artificial sky brightness model including an implicit calculation of 2nd order scattering (ILLUMINA) developed by Martin Aubé[U+05F3]s group. This model generates three kinds of outputs: the sky radiance at the given site, observing angle and wavelength and the corresponding contribution and sensitivity maps. The maps allow for the identification of the origin of the sky radiance according to each part of the surrounding territory. For summer clear sky conditions, the results show that replacing light fixtures within a 25. km radius around the MMO with cut-off High Pressure Sodium devices and reducing the total installed radiant power to ~40% of its initial level are very efficient ways of reducing artificial sky brightness. The artificial sky brightness reduction at zenith observed after the establishment of the IDSR was ~50% in the 546. nm mercury spectral line, while the reduction obtained in the 569. nm sodium line was ~30%. A large part of that reduction can be associated to the reduction in radiant power. The contribution and sensitivity maps highlight critical zones where any changes in the lighting infrastructure have the most important impact on sky brightness at the MMO. Contribution and sensitivity maps have been used to analyze the detailed origin of sky brightness reduction. The results of this study are intended to support authorities in the management of their lighting infrastructure with the goal of reducing sky brightness. The results have been shared with MMO officials and are being used as a tool to improve sky quality at the observatory. © 2014 Elsevier Ltd.


In 2005 and 2009, two species of Cyprinidae, the Northern Redbelly Dace, Phoxinus eos, and the Golden Shiner, Notemigonus crysoleucas, were collected northeast of their know range, in Québec. These new records, indeed range extensions, are presented here with a short discussion on the fish fauna of the area and on the possibility of introductions. En 2005 et en 2009, deux espèces de Cyprinidés, soit le Méné ventre-rouge, Phoxinus eos, et le Méné jaune, Notemigonus crysoleucas, ont été capturées au nord-est de leur répartition connue au Québec. Ces nouvelles mentions, qui constituent des extensions d'aire, sont ici présentées de même qu'une courte discussion sur l'ichtyofaune de la région et la possibilité d'introductions.


PubMed | Cegep de Sherbrooke
Type: Journal Article | Journal: Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2015

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aub et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane.

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