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See detailSupervised detection of exoplanets in high-contrast imaging sequences
Gómez González, Carlos ULiege; Absil, Olivier ULiege; Van Droogenbroeck, Marc ULiege

in Astronomy and Astrophysics (in press)

Context. Post-processing algorithms play a key role in pushing the detection limits of high-contrast imaging (HCI) instruments. State-of-the-art image processing approaches for HCI enable the production ... [more ▼]

Context. Post-processing algorithms play a key role in pushing the detection limits of high-contrast imaging (HCI) instruments. State-of-the-art image processing approaches for HCI enable the production of science-ready images relying on unsupervised learning techniques, such as low-rank approximations, for generating a model point spread function (PSF) and subtracting the residual starlight and speckle noise. Aims. In order to maximize the detection rate of HCI instruments and survey campaigns, advanced algorithms with higher sensitivities to faint companions are needed, especially for the speckle-dominated innermost region of the images. Methods. We propose a reformulation of the exoplanet detection task (for ADI sequences) that builds on well-established machine learning techniques to take HCI post-processing from an unsupervised to a supervised learning context. In this new framework, we present algorithmic solutions using two different discriminative models: SODIRF (random forests) and SODINN (neural networks). We test these algorithms on real ADI datasets from VLT/NACO and VLT/SPHERE HCI instruments. We then assess their performances by injecting fake companions and using receiver operating characteristic analysis. This is done in comparison with state-of-the-art ADI algorithms, such as ADI principal component analysis (ADI-PCA). Results. This study shows the improved sensitivity versus specificity trade-off of the proposed supervised detection approach. At the diffraction limit, SODINN improves the true positive rate by a factor ranging from ∼2 to ∼10 (depending on the dataset and angular separation) with respect to ADI-PCA when working at the same false-positive level. Conclusions. The proposed supervised detection framework outperforms state-of-the-art techniques in the task of discriminating planet signal from speckles. In addition, it offers the possibility of re-processing existing HCI databases to maximize their scientific return and potentially improve the demographics of directly imaged exoplanets. [less ▲]

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See detailRandom size-assortative mating despite size-dependent fecundity in a Neotropical amphibian with explosive reproduction
Székely, Diana ULiege; Székely, Paul; Denoël, Mathieu ULiege et al

in Ethology (in press)

Sexual selection theory predicts that, when body size is correlated with fecundity, there should be fitness advantages for mate choice of the largest females. Moreover, because larger males are expected ... [more ▼]

Sexual selection theory predicts that, when body size is correlated with fecundity, there should be fitness advantages for mate choice of the largest females. Moreover, because larger males are expected to monopolize the largest females, this should result in an assortative mating based on body size. Although such patterns could be expected in both explosive and prolonged breeders, non-assortative mating should be more widespread in species under time constraints. However, patterns of sexual selection are largely unexplored in explosive breeding species, and contrasting patterns have been found previously. We expect that the active choice of partners may be particularly risky when the time period during which sexual partners are available is severely limited. Therefore, to avoid missing an entire reproductive act, males and females should pair irrespective of traits, such as body size. We tested this hypothesis by investigating the mating patterns of the Pacific horned toad, Ceratophrys stolzmanni, a short-lived fossorial species inhabiting Neotropical dry forests. This species is particularly adequate to test our prediction because it reproduces explosively over the course of a single night per year. Although the number of eggs laid was proportional to the size of females, and individuals of both sexes showed variation in body size, there was no assortative mating based either on size, body condition or age of mates. Egg size was not influenced by either female size or clutch size. The larger body size of females compared to males is likely due to fecundity selection, i.e. the selective pressure that enhances reproductive output. Although we cannot dismiss the possibility that individuals could select their partners based on other criteria than those related to size or age, the results fit well our prediction, showing that the explosive breeding makes improbable an active choice of partners in both sexes and therefore favours a random mating pattern. [less ▲]

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See detailCyanobacteria inhabiting biological soil crusts of a polar desert: Sør Rondane Mountains, Antarctica
Pushkareva, Ekaterina; Pessi, Igor S; Namsaraev, Zorigto et al

in Systematic and Applied Microbiology (in press)

Molecular and morphological methods were applied to study cyanobacterial community composition in biological soil crusts (BSCs) from four areas (two nunataks and two ridges) in the Sør Rondane Mountains ... [more ▼]

Molecular and morphological methods were applied to study cyanobacterial community composition in biological soil crusts (BSCs) from four areas (two nunataks and two ridges) in the Sør Rondane Mountains, Antarctica. The sampling sites serve as control areas for open top chambers (OTCs) which were placed in 2010 at the time of sample collection and will be compared with BSC samples taken from the OTCs in future. Cyanobacterial cell biovolume was estimated using epifluorescence microscopy, which revealed the dominance of filamentous cyanobacteria in all studied sites except the Utsteinen ridge, where unicellular cyanobacteria were the most abundant. Cyanobacterial diversity was studied by a combination of molecular fingerprinting methods based on the 16S rRNA gene (denaturing gradient gel electrophoresis (DGGE) and 454 pyrosequencing) using cyanobacteria specific primers. The number of DGGE sequences obtained per site was variable and, therefore, a high-throughput method was later employed to improve the diversity coverage. Consistent with previous surveys in Antarctica, both methods showed that filamentous cyanobacteria such as Leptolyngbya sp., Phormidium sp. and Microcoleus sp. were dominant in the studied sites. In addition, the studied localities differed in substrate type, climatic conditions and soil parameters, which likely resulted in differences in cyanobacterial community composition. Furthermore, the BSC growing on gneiss pebbles had lower cyanobacterial abundances than BSCs associated to granitic substrates. [less ▲]

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See detailHume
Lejeune, Guillaume ULiege

Book published by Ellipses (in press)

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See detailThe Fight against Atomism and Pluralism. A Note on the Hegelian Legacy in Bradley
Lejeune, Guillaume ULiege

in Rosaye, JEan-Paul; Marshall, C. (Eds.) L'idéalisme britannique (in press)

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See detailInstinkt oder Entschluss? Anfang des Philosophierens bei Kant, Descartes und Bradley
Lejeune, Guillaume ULiege

in Asmuth, Christoph; Rasmussen, Jespers (Eds.) Anfang der Philosophie (in press)

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See detailLes Bandes dessinées opaques de Pascal Leyder. A propos de "Comix Covers"
Dejasse, Erwin ULiege

in Rommens, Aarnoud; Crucifix, Benoît; Dejasse, Erwin (Eds.) et al Comics and Abstraction (in press)

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See detailCe Spirou qui m'emmerde
Dejasse, Erwin ULiege

in Meesters, Gert; Vrydaghs, David; Hagelstein, Maud (Eds.) Spirou en héritage (titre provisoire) (in press)

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See detailOrganometallic mediated radical polymerization of vinylidene fluoride
Banerjee, Sanjib; Ladmiral, Vincent; Debuigne, Antoine ULiege et al

in Angewante Chemie Intenational Edition (in press)

An unprecedented level of control for the radical polymerization of vinylidene fluoride (VDF), yielding well-defined PVDF (up to 14,500 g/mol) with low dispersity (≤1.32), was achieved using ... [more ▼]

An unprecedented level of control for the radical polymerization of vinylidene fluoride (VDF), yielding well-defined PVDF (up to 14,500 g/mol) with low dispersity (≤1.32), was achieved using organometallic mediated radical polymerization (OMRP) with an organocobalt compound as initiator. The high chain-end fidelity was demonstrated by the synthesis of PVDF- and PVAc-containing di-and tri-block copolymers. DFT calculations rationalize the efficient reactivation of both head and tail chain end dormant species. [less ▲]

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See detailValidated assessment of gait sub-phase durations in older adults using an accelerometer-based ambulatory system
Boutaayamou, Mohamed ULiege; GILLAIN, Sophie ULiege; Schwartz, Cédric ULiege et al

in Proceedings of the 11th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2018) (in press)

Validated extraction of gait sub-phase durations using an ambulatory accelerometer-based system is a current unmet need to quantify subtle changes during the walking of older adults. In this paper, we ... [more ▼]

Validated extraction of gait sub-phase durations using an ambulatory accelerometer-based system is a current unmet need to quantify subtle changes during the walking of older adults. In this paper, we describe (1) a signal processing algorithm to automatically extract not only durations of stride, stance, swing, and double support phases, but also durations of sub-phases that refine the stance and swing phases from foot-worn accelerometer signals in comfortable walking of older adults, and (2) the validation of this extraction using reference data provided by a gold standard system. The results show that we achieve a high agreement between our method and the reference method in the extraction of (1) the temporal gait events involved in the estimation of the phase/sub-phase durations, namely heel strike (HS), toe strike (TS), toe-off (TO), maximum of heel clearance (MHC), and maximum of toe clearance (MTC), with an accuracy and precision that range from ‒3.6 ms to 4.0 ms, and 6.5 ms to 12.0 ms, respectively, and (2) the gait phase/sub-phase durations, namely stride, stance, swing, double support phases, and HS to TS, TO to MHC, MHC to MTC, and MTC to HS sub-phases, with an accuracy and precision that range from ‒4 ms to 5 ms, and 9 ms to 15 ms, respectively, in comfortable walking of a thirty-eight older adults ( (mean ± standard deviation) 71.0 ± 4.1 years old). This demonstrates that the developed accelerometer-based algorithm can extract validated temporal gait events and phase/sub-phase durations, in comfortable walking of older adults, with a promising degree of accuracy/precision compared to reference data, warranting further studies. [less ▲]

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See detailAn H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme-Adaptive Optics System
Kühn, Jonas; Serabyn, Eugene; Lozi, Julien et al

in Publications of the Astronomical Society of the Pacific (in press)

The vector vortex is a coronagraphic imaging mode of the recently commissioned Subaru Coronagraphic Extreme-Adaptive Optics (SCExAO) platform on the 8-m Subaru Telescope. This multi-purpose high-contrast ... [more ▼]

The vector vortex is a coronagraphic imaging mode of the recently commissioned Subaru Coronagraphic Extreme-Adaptive Optics (SCExAO) platform on the 8-m Subaru Telescope. This multi-purpose high-contrast visible and near-infrared (R- to K-band) instrument is not only intended to serve as a VLT-class "planet-imager" instrument in the Northern hemisphere, but also to operate as a technology demonstration testbed ahead of the ELTs-era, with a particular emphasis on small inner-working angle (IWA) coronagraphic capabilities. The given priority to small-IWA imaging led to the early design choice to incorporate focal-plane phase-mask coronagraphs. In this context, a test H-band vector vortex liquid crystal polymer waveplate was provided to SCExAO, to allow a one-to-one comparison of different small-IWA techniques on the same telescope instrument, before considering further steps. Here we present a detailed overview of the vector vortex coronagraph, from its installation and performances on the SCExAO optical bench, to the on-sky results in the extreme AO regime, as of late 2016/early 2017. To this purpose, we also provide a few recent on-sky imaging examples, notably high-contrast ADI detection of the planetary-mass companion \kappa Andromedae b, with a signal-to-noise ratio above 100 reached in less than 10 mn exposure time. [less ▲]

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See detailFrancesco Guicciardini, une vie de lettres
Miesse, Hélène ULiege

Book published by Classiques Garnier (in press)

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See detailThe law of attraction: identification of Volatiles Organic Compound emitted by potatoes as wireworm attractants
La Forgia, Diana ULiege; Verheggen, François ULiege

in Communications in Agricultural and Applied Biological Sciences (in press)

Wireworms (Coleoptera: Elateridae) are common polyphagous soil pests of various crops, including maize and potatoes, inflicting severe economic damage (Parker and Howard 2001). Their management with ... [more ▼]

Wireworms (Coleoptera: Elateridae) are common polyphagous soil pests of various crops, including maize and potatoes, inflicting severe economic damage (Parker and Howard 2001). Their management with pesticides is often not successful or sustainable and more research on biological alternatives is required. One of these alternatives could be the use of traps baited with attractive volatile organic compounds (VOCs) in association with a microbial control agent. In this paper, we describe the methodology followed to identify volatile organic molecules with potential as wireworms attractants. We previously observed that cut potato tubers place on the soil surface were highly attractive for wireworms. To identify the attractive cues released by potato tubers, we defined three specific objectives: 1) developing a behavioral assay suitable for the study of wireworm orientation behavior; 2) profiling VOCs released by potato tubers; 3) evaluating the role of the identified VOCs on wireworms foraging behavior. [less ▲]

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See detailAgroforestry for ruminants: a review of trees and shrubs as fodder in silvopastoral temperate and tropical production systems
Vandermeulen, Sophie; Ramirez Restrepo, Carlos; Beckers, Yves ULiege et al

in Animal production science (in press)

Among the oldest agroforestry systems, silvopastoralism uses shrubs and trees to feed ruminants. The practice is common in extensive livestock production systems, while the intensification of grass-based ... [more ▼]

Among the oldest agroforestry systems, silvopastoralism uses shrubs and trees to feed ruminants. The practice is common in extensive livestock production systems, while the intensification of grass-based systems in the past century has led to the removal of woody species from agricultural temperate landscapes. In Europe however, woody species are promoted again on grasslands through environment-friendly policies due to the ecosystem services they provide such as carbon sequestration, control of soil erosion, limitation of air-borne pollutants and biodiversity conservation. Positive effects of browse on rumen digestion and parasite control have also been documented across different plant species and regions. Under optimal conditions, feeding ruminants from woody fodder sustains animal production. Nonetheless, limitations can restrict the use of woody forage into animal diets, such as the presence of anti-nutritive and toxic compounds. The incorporation of this resource in ruminant feeding systems raises the question of the management of the interface between the plant and the animal. Various management systems are practiced. Temperate species such as Salix spp. and Populus spp. are fed to sheep and cattle in fodder blocks or by pruning trees in New Zealand, and Fraxinus spp. or Corylus avellana in hedgerows supply forage to livestock in Belgium, while Leucaena leucocepahala and Desmanthus spp. browsing is common in Australia. Nowadays, ensiling and pelleting techniques are being developed as a way to store browse forage. As the renewed interest in using shrubs and trees to feed ruminants is recent, especially in temperate regions, additional research about introducing optimally this resource within systems is needed. [less ▲]

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See detailFrom SEM images to elastic responses: a stochastic multiscale analysis of UD fiber reinforced composites
Wu, Ling ULiege; Chung, Chi Nghia; Major, Zoltan et al

in Composite Structures (in press)

In this work, the elastic response of unidirectional fiber (UD) reinforced composites is studied in a stochastic multiscale way. First, the micro-structure of UD carbon fiber reinforced composites is ... [more ▼]

In this work, the elastic response of unidirectional fiber (UD) reinforced composites is studied in a stochastic multiscale way. First, the micro-structure of UD carbon fiber reinforced composites is statistically studied based on SEM images of its cross-section and an algorithm to generate numerical micro-structures with an equivalent random distribution of fibers is developed. In particular, based on the images spatial analysis, the empirical statistical descriptors are considered as dependent variables and represented using the copula framework, allowing generating micro-structure realizations used as Stochastic Volume Elements (SVEs). Second, a stochastic scale transition is conducted through the homogenization of SVEs. With a view to the use of the resulting meso-scale random field in structural stochastic analyzes, the homogenization is performed in two steps in order to respect the statistical content from the micro-meter-long SVEs to the millimeter-long structural finite elements. To this end, the computational homogenization is applied in a hierarchy model: i) Micro-structure generator produces Small SVEs (SSVEs) which are homogenized; ii) Big SVEs (BSVEs) are constructed from the SSVEs. Finally, it is shown on simple illustrative examples that the scatter of the (homogenized) stress distribution in a composite ply can be simulated by means of the developed methodology. [less ▲]

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See detailPhenotyping of Brassica napus L. plantlets affected during in vitro growth by the presence of epoxiconazole
Durenne, Bastien ULiege; Blondel, Alodie; Ducat, Nathalie et al

in Acta Horticulturae (in press)

Epoxiconazole like others triazole fungicides are known to be persistent in the soil. Several studies using foliar application experiments demonstrated the effect of its triazole metabolite as plant ... [more ▼]

Epoxiconazole like others triazole fungicides are known to be persistent in the soil. Several studies using foliar application experiments demonstrated the effect of its triazole metabolite as plant growth regulator through the anti-gibberellin activity. And notably, the reduction of Brassica napus L. growth can be attributed to the inhibition of gibberellin biosynthesis at the stage of conversion of ent-kaurene to ent-kaurenoic acid. We describe here an in vitro experiment studying the relationship between epoxiconazole in culture medium (0 mg L⁻¹, 0.120 mg L⁻¹ and 0.200 mg L⁻¹) and the phenotyping (root and shoot growth) of three varieties of winter rapeseeds (Brassica napus L. var. Catalina, var. ES Astrid and var. Toccata). Plantlets fungicide content was quantified using the QuEChERS extraction method following by an automated UHPLC-MS/MS analysis. Results showed that the shoots and roots growth of Brassica napus L. plantlets was significantly inhibited by epoxiconazole at 0.120 mg L⁻¹ independently of the variety. The concentration of 0.200 mg L⁻¹ leaded to necrosis and anthocyanosis symptoms and can be considered as lethal for in vitro growing explants. The huge epoxiconazole absorption by rapeseed plantlets clearly showed a dose-dependent relationship and was closely similar for the three varieties. [less ▲]

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