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See detailFeasibility study of a UV Photometer on-board a 3U Cubesat for the study of bright massive stars
Desselle, Richard ULg

Scientific conference (2017, September 15)

Feasibility study of a UV Photometer on-board a 3U Cubesat for the study of bright massive stars

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See detailASTA -- Theoretical Stellar Astrophysics and Asteroseismology
Godart, Mélanie ULg

Scientific conference (2017, September 15)

Theoretical Stellar Physics and Asteroseismology

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See detailPresentation of CSL Signal Processing Laboratory - First STAR Workshop on 15/09/2017
Orban, Anne ULg

Scientific conference (2017, September 15)

Presentation of the Signal Processing laboratory of the Centre Spatial de Liège

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See detailMusic in the Operating Room
XHAUFLAIRE, Gaël ULg; Albert, Louisa; Gengoux, Monique

Poster (2017, September 15)

Listening to music during surgery has a subjective benefit to patients under local anesthesia. Its setting up during quiet routine oculoplastic surgery is easy and inexpensive. When subject to some ... [more ▼]

Listening to music during surgery has a subjective benefit to patients under local anesthesia. Its setting up during quiet routine oculoplastic surgery is easy and inexpensive. When subject to some elementary precautions, there is no increased risk. [less ▲]

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See detailHow classroom teachers do take the ‘Physical Activity Pauses at School’ (PAPS)? A project implemented in Wallonia
Cloes, Marc ULg; Cloes, Stéphanie

Conference (2017, September 15)

In Wallonia, special efforts are needed in order to respect the international recommendations on physical activity in youth. School is definitely considered as a central pillar in the promotion of an ... [more ▼]

In Wallonia, special efforts are needed in order to respect the international recommendations on physical activity in youth. School is definitely considered as a central pillar in the promotion of an active lifestyle. The aim of this study was to analyze the implementation process of daily activity breaks called ‘Physical Activity Pause at School’ (PAPS) in 6 primary schools of the Liege area. 23 classroom teachers were involved. They had to propose at least one PAPS/day during the 15-16 school year. Diary, questionnaires, focus groups and interviews were used for data collecting. Two thirds of the subjects continued until the end. The videos were not systematically used. Four teachers’ profiles were identified: Innovators, Invested, Careful, and Disengaged. 12 factors facilitating or limitating the involvement of the teachers have been analyzed. The study comes to a model of concrete actions to respect in order to increase the chances of success in the implementation of such project. [less ▲]

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See detailPush-Pull strategy to control aphids in Belgium and China
Xu, Qingxuan ULg

Doctoral thesis (2017)

Wheat (Triticum aestivum L.) is one of the most cultivated crops in temperate climates. As its pests are mainly controlled with insecticides which are harmful to the environment and human health ... [more ▼]

Wheat (Triticum aestivum L.) is one of the most cultivated crops in temperate climates. As its pests are mainly controlled with insecticides which are harmful to the environment and human health, alternative practices such as intercropping have been studied for their potential to promote biological control. Fifty original research papers were obtained from a systematic search of the peer-reviewed literature. Results from a vote-counting analysis indicated that, in the majority of studies, pest abundance was significantly reduced in intercropping systems compared with pure stands. However, the occurrence of their natural enemies as well as predation and parasitism rates were not significantly increased. Nevertheless, other practices could be combined with intercropping to favour natural enemies and enhance pest control. Dispersal of viruses is intimately tied to their vectors. Aphids are known to invest in costly antipredator behavior when perceiving cues of predators. Before presenting the results and the answers to the previous questions, a brief research was conducted in order to have an overview of the intercropping on the spread of aphids, to assess the potential impact of intercropping systems attracting natural enemies on the virus transmission. We studied aphid antipredator behavior in intercropping with wheat-broad bean (Vicia faba L.) as a model. The bird cherry-oat aphid, Rhopalosiphum padi Linnaeus, is an important vector of the barley yellow dwarf virus. The effects of two natural aphid enemies, adult and larvae of the seven-spot ladybeetle, Coccinella septempunctata Linneaus, on R. padi dispersion was studied under laboratory conditions. Results show that the total number of aphids was higher in intercropping than monoculture in treatments without ladybeetles, while the contrary was observed in the presence of ladybeetle larvae. These results might be explained by the non-host plant chemical cues and the physical barrier that was broad-bean plants confusing R. padi when searching for their host plants after being dropped from wheat by predators (i.e. associational resistance). After make sure that the intercropping can reduce the dispersal of aphids in the presence of predators, in fine potentially limiting virus dispersal, especially shortly after aphids colonize plants. Next step will be to solve how to increase the number of natural enemies of intercropping in Belgium and China. Semiochemical substances have been tested to enhance biological control, with inconsistent results. Combining semiochemical and intercropping can be an interesting way to maximize pest control. In Belgium, a two-year setup involving wheat–pea strip intercropping combined with the release of E-β-farnesene (EBF) or methyl salicylate (MeSA) was tested as a push–pull strategy to simultaneously repell aphids and attract beneficials. Two types of slow-release formulation (i.e., oil and alginate beads) containing EBF or MeSA were deployed with intercropping. The abundance of aphids was significantly decreased, hoverfly larvae and mummified aphids increased on both pea plants and wheat tillers by the release of oil-formulated EBF and MeSA. The proportion parasitism of aphids-parasitism rate was also increased by treating both crops in both years. Releasing EBF through oil rather than alginate beads proved significantly better for attracting natural enemies and reducing aphids. Aphids were negatively correlated with the density of hoverflies (both adults and larvae) and numbers of mummies. We also tested the combining in China and the experiments were set-up: wheat-pea strip intercropping solely, intercropping combined with the release of EBF, and intercropping combined with the release of MeSA, each treatment repeated three times. The total number of aphids throughout the growing season was significantly decreased in treatments with releases of semiochemicals compared to intercropping solely. The effect was stronger with MeSA than with EBF on the control of R. padi, and hoverflies and lacewings were twice more numerous in MeSA. All these results showed that combining intercropping with the release of EBF or MeSA formulated in oil can significantly reduce aphid density and attract their natural enemies. Therefore, the combination of both strategies could help farmers reduce the use of insecticides. [less ▲]

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See detailDevelopment of inversion techniques in Asteroseismology
Buldgen, Gaël ULg

Doctoral thesis (2017)

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See detailAdvanced data processing for high-contrast imaging - Pushing exoplanet direct detection limits with machine learning
Gómez González, Carlos ULg

Doctoral thesis (2017)

Since ancient times, mankind has wondered whether other solar systems exist around other stars somewhere in the Universe. It took many centuries to finally prove the existence of extra-solar planetary ... [more ▼]

Since ancient times, mankind has wondered whether other solar systems exist around other stars somewhere in the Universe. It took many centuries to finally prove the existence of extra-solar planetary systems. Nowadays, more than 3500 exoplanets have been discovered, mostly thanks to indirect detection methods. Indeed, the task of directly detecting exoplanets through high-contrast imaging (HCI) is a formidable challenge, and has only been enabled in the last decade thanks to advances in instrumentation and dedicated image processing algorithms. This last component of the exoplanet direct imaging pipeline is what ultimately pushes the detection limits and sensitivity of HCI instruments and survey campaigns. Unfortunately, the HCI community has been slow in adopting the latest developments in data management and machine learning for analyzing the increasing amount of available data. This dissertation is an attempt to fill in this very gap, and develops at the interface of computer science, machine learning, statistics, and astrophysics. This work contributes to the field of data processing for HCI in two main ways. On one hand, I have developed an open source \texttt{Python} library for taking HCI data from the raw state up to the characterization of companions. It implements state-of-the-art approaches and is positioning itself as one of the de facto software solutions for building HCI pipelines. I have also participated to the critical analysis of data from different first and second generation HCI instruments. On the other hand, I have approached the task of exoplanet detection in angular differential imaging sequences from a computer vision and machine learning perspective. This interdisciplinary work has led to novel algorithmic solutions, extending unsupervised learning techniques widely used in HCI and proposing advanced supervised learning approaches based on cutting-edge deep learning models. My novel algorithms have been presented using a robust performance assessment framework to produce large comparative performance studies. These studies show the improved sensitivity vs specificity trade-off of the proposed supervised detection approach. The proposed algorithms bring 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 detailEconomic Development and Structural Change
Van Neuss, Leif ULg

Doctoral thesis (2017)

This doctoral dissertation contributes to the understanding of structural change, often defined as the process of reallocation of economic activity and resources across the three broad sectors agriculture ... [more ▼]

This doctoral dissertation contributes to the understanding of structural change, often defined as the process of reallocation of economic activity and resources across the three broad sectors agriculture (primary sector), manufacturing (secondary sector) and services (tertiary sector). Increasingly connected to the study of modern growth, the analysis of structural change has known an important revival over recent decades, due in part to the economic concerns associated with the movement of deindustrialization that has particularly affected the world’s most economically successful countries since the last third of the 20th century. These concerns have indeed fed many discussions on the causes and consequences of structural change, as well as on the role of policy instruments in driving and accompanying the inter-sectoral reallocation of activity. The first part of the thesis gets particularly interested in the driving forces behind the process of structural change. It begins by placing structural change in a very long historical perspective, notably shedding light on the factors that contributed to the emergence of the Industrial Revolution, an event characterized by the acceleration of structural change and traditionally considered as a turning point in the history of mankind because it eventually brought about modernity. It then analyzes the main causes of structural change in market economies, putting a particular emphasis on two mechanisms of structural change that have been largely overlooked in the recent multi-sector growth literature: changes in input-output (sectoral) linkages and changes in comparative advantage via globalization and trade. With respect to trade, an empirical analysis reveals that global exchanges have the potential to influence significantly and substantially a country’s sectoral patterns of employment, and that the estimated contribution of trade, especially of trade with developing countries, to recent structural change (deindustrialization) in affluent countries may be revised upwards when resorting to better-suited indicators of trade in manufactures. The second part of this doctoral thesis deals more with the economic effects of structural change. In particular, it proposes a new shift-share method, which is an accounting method aimed at computing the impact of the economic structure - or structural change - on a territory’s economic performance. By way of illustration, it provides an application to manufacturing employment in the Belgian provinces between 1995 and 2007. [less ▲]

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See detailManaging and authenticating non-institutional users in Alma: two experiences
Brownlie, Helen; De Groof, Robert ULg; Renaville, François ULg

Conference (2017, September 12)

The management of patron information within Alma is primarily reliant on two systems – the creation and updating of patron information by an external system such as student management or HR systems or ... [more ▼]

The management of patron information within Alma is primarily reliant on two systems – the creation and updating of patron information by an external system such as student management or HR systems or internally within Alma itself. A recent survey of the Alma community indicated the majority of institutions utilize a mixture of these external and internal processes. In addition to providing access to affiliated staff and students more than 89% of institutions responded that they provided user accounts to non-affiliated users such as the general public, members of other academic institutions, alumni, etc. Providing authenticated access to library services for the latter group relies heavily on Alma for password management. This presentation will outline the processes in place at the University of Otago and at the University of Liège for managing and authenticating non-institutional users and the possible effect of Ex Libris' proposed changes to internal authentication. [less ▲]

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See detailContent Working Group Report 2016-2017
Renaville, François ULg; Varjabedian, Kathy

Conference (2017, September 11)

Report on the activities in 2016-2017 of the Content Working Group (previously Knowledge Base Advisory Board [KBAB]).

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See detailIdentification et analyse fonctionnelle de nouveaux variants d’épissage du CD46 des bovidés, le (co)-récepteur du virus BVD/MD
Alzamel, Nidal ULg

Doctoral thesis (2017)

The pestivirus bovine viral diarrhea virus (BVDV) is known to bind to the CD46 molecule, which subsequently promotes entry of the virus. Mapping of the BVD-virion-binding site has shown that two peptides ... [more ▼]

The pestivirus bovine viral diarrhea virus (BVDV) is known to bind to the CD46 molecule, which subsequently promotes entry of the virus. Mapping of the BVD-virion-binding site has shown that two peptides, 66EQIV69 and 82GQVLAL87, located on antiparallel beta sheets in the most distal complement control protein module (CCP1), provide the attachment platform. In the present study, we reveal new CD46-encoding transcripts that are predicted to encode CCP1-containing soluble forms. Further, we show that the serum of most adult cattle contains soluble CD46 (sCD46) and that a recombinant soluble isoform neutralizes BVDV infectivity in an in vitro assay. We have then established an ELISA for determination of plasma sCD46 in a large cohort of animals. Overall, serum sCD46 amounts to 8 ± 18 ng/mL (mean ± SD, n = 543), with a IC [95-105] ranging from 6,4 to 9,8 ng/mL and extreme values between 0 and 178 ng/mL. We found that sCD46 is not detectable in fetal and neonatal sera and that its plasma concentration increases progressively up to adulthood. We also detected high- and low-sCD46 performers and show that this phenotype does not depend of environment. As modern rearing techniques make it possible to disseminate genetically-determined phenotypes very quickly in a population, a large-scale study examining whether high-sCD46 animals provide epidemiological protection against BVDV infection and transmission should be undertaken [less ▲]

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See detailExtracting oscillating components from nonstationary time series: A wavelet-induced method
Deliège, Adrien ULg; Nicolay, Samuel ULg

in Physical Review. E : Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics (2017), 96

This paper consists in the description and application of a method called wavelet-induced mode extraction (WIME) in the context of time-frequency analysis. WIME aims to extract the oscillating components ... [more ▼]

This paper consists in the description and application of a method called wavelet-induced mode extraction (WIME) in the context of time-frequency analysis. WIME aims to extract the oscillating components that build amplitude modulated-frequency modulated signals. The essence of this technique relies on the successive extractions of the dominant ridges of wavelet-based time-frequency representations of the signal under consideration. Our tests on simulated examples indicate strong decomposition and reconstruction skills, trouble-free handling of crossing trajectories in the time-frequency plane, sharp performances in frequency detection in the case of mode-mixing problems, and a natural tolerance to noise. These results are compared with those obtained with empirical mode decomposition. We also show that WIME still gives meaningful results with real-life data, namely, the Oceanic Niño Index. [less ▲]

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See detailAn update on ozone profile trends for the period 2000 to 2016
Steinbrecht, Wolfgang; Froidevaux, Lucien; Fuller, Ryan et al

in Atmospheric Chemistry and Physics (2017), 17(17), 10675-10690

Ozone profile trends over the period 2000 to 2016 from several merged satellite ozone data sets and from ground-based data by four techniques at stations of the Network for the Detection of Atmospheric ... [more ▼]

Ozone profile trends over the period 2000 to 2016 from several merged satellite ozone data sets and from ground-based data by four techniques at stations of the Network for the Detection of Atmospheric Composition Change indicate significant ozone increases in the upper stratosphere, between 35 and 48 km altitude (5 and 1 hPa). Near 2 hPa (42 km), ozone has been increasing by about 1.5 % per decade in the tropics (20°S to 20°N), and by 2 to 2.5 % per decade in the 35° to 60° latitude bands of both hemispheres. At levels below 35 km (5 hPa), 2000 to 2016 ozone trends are smaller and not statistically significant. The observed trend profiles are consistent with expectations from chemistry climate model simulations. Using three to four more years of observations and updated data sets, this study confirms positive trends of upper stratospheric ozone already reported, e.g., in the WMO/UNEP Ozone Assessment 2014, or by Harris et al. (2015). The additional years, and the fact that nearly all individual data sets indicate these increases, give enhanced confidence. Nevertheless, a thorough analysis of possible drifts and differences between various data sources is still required, as is a detailed attribution of the observed increases to declining ozone depleting substances and to stratospheric cooling. Ongoing quality observations from multiple independent platforms are key for verifying that recovery of the ozone layer continues as expected. [less ▲]

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See detailContributions to deep reinforcement learning and its applications in smartgrids
François-Lavet, Vincent ULg

Doctoral thesis (2017)

Reinforcement learning and its extension with deep learning have led to a field of research called deep reinforcement learning. Applications of that research have recently shown the possibility to solve ... [more ▼]

Reinforcement learning and its extension with deep learning have led to a field of research called deep reinforcement learning. Applications of that research have recently shown the possibility to solve complex decision-making tasks that were previously believed extremely difficult for a computer. Yet, deep reinforcement learning requires caution and understanding of its inner mechanisms in order to be applied successfully in the different settings. As an introduction, we provide a general overview of the field of deep reinforcement learning. In the first part of this thesis, we provide an analysis of reinforcement learning in the particular setting of a limited amount of data and in the general context of partial observability. In this setting, we focus on the tradeoff between asymptotic bias (suboptimality with unlimited data) and overfitting (additional suboptimality due to limited data), and theoretically show that while potentially increasing the asymptotic bias, a smaller state representation decreases the risk of overfitting. An original theoretical contribution relies on expressing the quality of a state representation by bounding $L_1$ error terms of the associated belief states. We also discuss and empirically illustrate the role of other parameters to optimize the bias-overfitting tradeoff: the function approximator (in particular deep learning) and the discount factor. In addition, we investigate the specific case of the discount factor in the deep reinforcement learning setting case where additional data can be gathered through learning. In the second part of this thesis, we focus on a smartgrids application that falls in the context of a partially observable problem and where a limited amount of data is available (as studied in the first part of the thesis). We consider the case of microgrids featuring photovoltaic panels (PV) associated with both long-term (hydrogen) and short-term (batteries) storage devices. We propose a novel formalization of the problem of building and operating microgrids interacting with their surrounding environment. In the deterministic assumption, we show how to optimally operate and size microgrids using linear programming techniques. We then show how to use deep reinforcement learning to solve the operation of microgrids under uncertainty where, at every time-step, the uncertainty comes from the lack of knowledge about future electricity consumption and weather dependent PV production. [less ▲]

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See detailDiscours en hommage à François Bovesse
Behrendt, Christian ULg

Speech/Talk (2017)

Discours d'Hommage prononcé le 11 septembre 2017 au Palais provincial de Namur

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See detailA tiny magic drawing board to track the penetration of magnetic flux in superconductors
Silhanek, Alejandro ULg

Conference (2017, September 11)

Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit ... [more ▼]

Local polarization of a magnetic layer, a well-known method for storing information, has found its place in numerous applications such as the popular magnetic drawing board toy or the widespread credit cards and computer hard drives. Here we experimentally show that a similar principle can be applied for imprinting the trajectory of quantum units of flux (vortices), travelling in a superconducting film (Nb), into a soft magnetic layer of permalloy (Py). In full analogy with the magnetic drawing board, vortices act as tiny magnetic scribers leaving a wake of polarized magnetic media in the Py board. The mutual interaction between superconducting vortices and ferromagnetic domains has been investigated by the magneto-optical imaging technique. For thick Py layers, the stripe magnetic domain pattern guides both the smooth magnetic flux penetration as well as the abrupt vortex avalanches in the Nb film. It is however in thin Py layers without stripe domains where superconducting vortices leave the clearest imprints of locally polarized magnetic moment along their paths. In all cases, we observe that the flux is delayed at the border of the magnetic layer. Our findings open the quest for optimizing magnetic recording of superconducting vortex trajectories. [less ▲]

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See detailNos cours d'eau, une source d'énergie renouvelable passée, présente et future
Erpicum, Sébastien ULg

Conference given outside the academic context (2017)

L’exploitation de l’énergie hydraulique, verte & renouvelable, a façonné au fil des siècles nombre de nos cours d’eau. Dans le contexte actuel de décentralisation de la production électrique ... [more ▼]

L’exploitation de l’énergie hydraulique, verte & renouvelable, a façonné au fil des siècles nombre de nos cours d’eau. Dans le contexte actuel de décentralisation de la production électrique & d’exploitation des sources non polluantes, l’hydroélectricité trouve un regain d’intérêt qui peut souvent s’accompagner de la remise en valeur d’un patrimoine bâti d’exception. La conférence détaillera ces points & les illustrera par de nombreux exemples. Parmi ceux-ci, la turbine hydroélectrique récemment mise en service au centre de Comblain-au-Pont, avec l’aide de la Région Wallonne, pour assurer l’autonomie énergétique de la Maison communale. [less ▲]