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See detailPB 8783: the first sdO star suitable for asteroseismic modeling?
Van Grootel, Valérie ULiege; Randall, Suzanna K.; Latour, Marilyn et al

E-print/Working paper (in press)

Pulsating hot B subdwarfs (sdB) have become one of the showcases of asteroseismology. Thanks to the combination of rich observed pulsation spectra and state-of-the-art modeling tools it is possible to ... [more ▼]

Pulsating hot B subdwarfs (sdB) have become one of the showcases of asteroseismology. Thanks to the combination of rich observed pulsation spectra and state-of-the-art modeling tools it is possible to tightly constrain fundamental parameters such as the stellar mass for these compact, evolved objects in the core He-burning phase of evolution. In comparison, the exploitation of sdO pulsators - hotter stars thought to be in a more advanced evolutionary stage - is still in its infancy. While a small number have been identified in Globular Clusters (GCs), they are extremely rare among the field population. It was recently suggested that PB8783, one of the very first sdB pulsators discovered in 1997, may in fact be an unrecognized hot sdO star with very similar properties to the GC sdO pulsators. Here, we present new very high-quality spectroscopy as well as an asteroseismic analysis of this star with the aim of solving the mystery of its nature. [less ▲]

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See detailThe Date of Plutarch's De Tranquillitate Animi
Demulder, Bram ULiege

E-print/Working paper (in press)

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See detailThe Firm Size Distribution in Belgium
Artige, Lionel ULiege; Bignandi, Sousso ULiege

E-print/Working paper (2020)

The shape of the firm size distribution (FSD) looks similar in all market economies but its approximation by a parametric distribution, a necessary information to build a general model of firm dynamics ... [more ▼]

The shape of the firm size distribution (FSD) looks similar in all market economies but its approximation by a parametric distribution, a necessary information to build a general model of firm dynamics, remains much debated. In this paper, we use an exclusive comprehensive database on Belgian firms. We show that the lognormal distribution is a better approximation of the empirical FSD than the power law distribution. This result holds true at the aggregate, sectoral and regional levels. [less ▲]

Detailed reference viewed: 31 (13 ULiège)
See detailModels of Law and Regulation for AI
De Cooman, Jérôme ULiege; Petit, Nicolas

E-print/Working paper (2020)

This paperdiscusses models of law and regulation of Artificial Intelligence (“AI”). The discussion focuses on four models: the black letter model, the emergent model, the ethical model, and the risk ... [more ▼]

This paperdiscusses models of law and regulation of Artificial Intelligence (“AI”). The discussion focuses on four models: the black letter model, the emergent model, the ethical model, and the risk regulation model. All four models currently inform, individually or jointly, integrally or partially, consciously or unconsciously, law and regulatory reform towards AI. We describe each model’s strengths and weaknesses, discuss whether technological evolution deserves to be accompanied by existing or new laws, and propose a fifth model based on externalities with a moral twist. [less ▲]

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See detailIndustry 4.0: An empirical analysis of its adoption in Wallonia
Paseyro Mayol, Joaquin ULiege; Gautier, Axel ULiege; Neysen, Nicolas ULiege

E-print/Working paper (2020)

This paper studies the factors influencing the adoption of digital technologies in the manufacturing sector; the so called Industry 4.0 phenomenon. We focus on the adoption of three particular ... [more ▼]

This paper studies the factors influencing the adoption of digital technologies in the manufacturing sector; the so called Industry 4.0 phenomenon. We focus on the adoption of three particular technologies (Predictive Maintenance, Smart Production and Advanced Planning) in the Belgian region of Wallonia. In line with the claims of related qualitative studies, our findings suggest that smaller firms, which have a more restricted access to financial resources, are less prone to adopt these technologies. Our results are compatible with the notion that more digitally mature firms are more prone to be adopters. Moreover, we do not find evidence supporting the claim that more profitable firms are more likely to be adopters. Finally, we present indicative evidence regarding the efficacy of the regional governmental program which aimed to increase the diffusion of Industry 4.0. [less ▲]

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See detailModelling and Assessing the Impact of the DSO Remuneration Strategy on its Interaction with Electricity Users
Manuel de Villena Millan, Miguel ULiege; Gautier, Axel ULiege; Ernst, Damien ULiege et al

E-print/Working paper (2020)

This paper presents a simulation-based methodology for assessing the impact of employing different distribution system operator’s remuneration strategies on the economic sustainability of electrical ... [more ▼]

This paper presents a simulation-based methodology for assessing the impact of employing different distribution system operator’s remuneration strategies on the economic sustainability of electrical distribution systems. The proposed methodology accounts for the uncertainties posed by the integration of distributed electricity generation resources, and the roll out of smart-meters. The different remuneration strategies analysed in this paper include notably new distribution tariffs based on individual peak power consumption and time-dependent rates that are contingent on the time of energy consumption, both requiring smart-meters to work. The distributed electricity generation resources are modelled through an optimisation framework and an investment decision process that gradually deploys household photovoltaic installations depending on their profitability and the electricity charges, including the distribution rates. The impact of the distribution system operator’s remuneration strategy is measured by an accurate modelling of the remuneration mechanism of this entity, which can adapt to various distribution tariff designs. We analyse this impact over a discrete time horizon. Our methodology is illustrated with several examples of distribution tariffs including old –based on energy consumption or on per-connection fees– as well as new –based on power consumption or time-of use fees– designs. Finally, we provide a comprehensive sensitivity analysis of the proposed simulation environment to the main parameters of the methodology. [less ▲]

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See detailCeramica comune da mensa e da dispensa di Roma
Dienst, Simon ULiege

E-print/Working paper (2020)

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See detailCeramica da cucina di Roma
Dienst, Simon ULiege

E-print/Working paper (2020)

Detailed reference viewed: 29 (2 ULiège)
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See detailI want to be an Open Scientist! Research evaluation and incentives to boost Open Science and research careers
Tanlongo, Federica; O’Neill, Gareth; Kurapati, Shalini et al

E-print/Working paper (2020)

Everybody is talking about Open Science and FAIR data but can you really make a living (and a good career) out of it? Will my career get better if I FAIRify my data? Or will it just make my head ache ... [more ▼]

Everybody is talking about Open Science and FAIR data but can you really make a living (and a good career) out of it? Will my career get better if I FAIRify my data? Or will it just make my head ache? When someone will evaluate my research, will the fact that my data complies with all the Open Science best practices matter? Or am I just losing time I should rather spend publishing on whatever journal I can lay hands on? And where am I supposed to learn how to be fair and open anyway? The right answer to these questions is crucial to the career choices and expectations of many students and young researchers, yes, but it is also the point which can make the difference between succeeding or failing in establishing Open Science (and ultimately Good Science). To be able to shift the research evaluation system in Europe in order to produce quality and reliable data, to set up a working incentive system for individual researchers and organisations is one of the keys to a widespread uptake of Open Science and FAIR practices. And being so crucial a point, we believe that researchers, Research Infrastructures, scientific organisations should have a say in this. That’s why we proposed an interactive session where good ideas, innovative pilots, proposed policies from all across Europe were presented and discussed. [less ▲]

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See detailConversation japonaise sur les bienfaits de la sémiotique
Badir, Sémir ULiege; Leone, Massimo

E-print/Working paper (2020)

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See detailNutritional status of inmates in the Central Prison of Mbuji-Mayi, Democratic Republic of Congo
De Coninck, Gérard; Okenge Ngongo, Leon; Ilunga Ilunga, Félicien et al

E-print/Working paper (2020)

Background: The nutritional situation in prisons of developing countries and the health status of inmates remain a major human rights concern. The objective of the study was to assess the nutritional ... [more ▼]

Background: The nutritional situation in prisons of developing countries and the health status of inmates remain a major human rights concern. The objective of the study was to assess the nutritional status of inmates jailed in a prison of the Democratic Republic of Congo (DRC). Methods: This cross-sectional study was conducted over a 4-month period in the Central Prison of Mbuji-Mayi, DRC. Three hundred inmates were selected according to the Malnutrition Universal Screening Tool (MUST). Severe malnutrition was defined according to Buzby index and Nutritional Risk Index (NRI). Data were analyzed by logistic regression. Results: The inmates were aged between 18 and 70 years and primarily males (88.7%). Of them, 24% were suffering from severe malnutrition and 62% of moderate malnutrition as based on the NRI. At the time of study, 88% of inmates were incarcerated for more than 6 months. Multivariate logistic regression analysis showed that factors independently associated with severe malnutrition were incarceration of more than 6 months (OR=5.1; 95% CI [1.5-17.4]), origin of food (prison vs. family or NGO) (OR=4.7; 95% CI [1.6-13.8]) but also presence of tuberculosis, human immunodeficiency virus and/or intestinal infections (OR=2.6; 95% CI [1.4-4.7]). Conclusions: The nutritional situation in the Central Prison of Mbuji-Mayi is precarious. There is urgent need to supply enough nutrient-rich food to improve health of inmates. [less ▲]

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See detailLa terre sigillée africaine - productions C, C/E et E
Dienst, Simon ULiege

E-print/Working paper (2020)

Detailed reference viewed: 22 (4 ULiège)
See detailLa céramique à vernis noir
Dienst, Simon ULiege

E-print/Working paper (2020)

Detailed reference viewed: 24 (3 ULiège)
See detailLa terre sigillée africaine - productions A, A/D et D
Dienst, Simon ULiege

E-print/Working paper (2020)

Detailed reference viewed: 24 (4 ULiège)
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See detailAllocation of locally generated electricity in renewable energy communities
Manuel de Villena Millan, Miguel ULiege; Mathieu, Sébastien ULiege; Vermeulen, Eric et al

E-print/Working paper (2020)

This paper introduces a methodology to perform an ex-post allocation of locally generated electricity among the members of a renewable energy community. Such an ex-post allocation takes place in a ... [more ▼]

This paper introduces a methodology to perform an ex-post allocation of locally generated electricity among the members of a renewable energy community. Such an ex-post allocation takes place in a settlement phase where the financial exchanges of the community are based on the production and consumption profiles of each member. The proposed methodology consists of an optimisation framework which (i) minimises the sum of individual electricity costs of the community members, and (ii) can enforce minimum self-sufficiency rates –proportion of electricity consumption covered by local production– on each member, enhancing the economic gains of some of them. The latter capability aims to ensure that members receive enough incentives to participate in the renewable energy community. This framework is designed so as to provide a practical approach that is ready to use by community managers, which is compliant with current legislation on renewable energy communities. It computes a set of optimal repartition keys, which represent the percentage of total local production given to each member – one key per metering period per member. These keys are computed based on an initial set of keys provided in the simulation, which are typically contractual i.e., agreed upon between the member and the manager the renewable energy community. This methodology is tested in a broad range of scenarios, illustrating its ability to optimise the operational costs of a renewable energy community. [less ▲]

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See detailThe norito-granitic zone of Puntervoll-Lia (Rogaland anorthosite province, S. Norway): evolution of a genetic model
Duchesne, Jean-Clair ULiege

E-print/Working paper (2020)

The norito-granitic zone is a thin septum of highly deformed banded rocks squeezed between two anorthosite massifs, the Egersund-Ogna (EGOG) and the Håland massifs. The dominant lithologies are a norito ... [more ▼]

The norito-granitic zone is a thin septum of highly deformed banded rocks squeezed between two anorthosite massifs, the Egersund-Ogna (EGOG) and the Håland massifs. The dominant lithologies are a norito-anorthosite association gradationally passing into a norito-granitic association. A first genetic model was proposed in which a norite intruded in the foliated margin of the EGOG anorthosite was migmatitized and metasomatically transformed into an anorthosite. This model was not confirmed by later studies and finally the norito-anorthosite association was considered as a particular facies of the anorthosite margin. New studies of the Glypstad septum between EGOG and the Bjerkreim-Sokndal layered intrusion reveal that the norito-granitic association results from the deformation of a magma in which anatectic melts were mingled with a high-alumina basalt, parental to the EGOG anorthosite. [less ▲]

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See detailH is for The Hangman’s Game (2007) by Karen King-Aribisala
Ledent, Bénédicte ULiege

E-print/Working paper (2020)

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See detailInfluence of model formulation on the critical morphological acceleration factor: an analytical study
Dewals, Benjamin ULiege; Archambeau, Pierre ULiege; Pirotton, Michel ULiege et al

E-print/Working paper (2020)

The morphological acceleration factor (Morfac) has been used for over two decades to speed-up long term morphodynamic simulations. However, the Morfac values are usually set heuristically and hardly any ... [more ▼]

The morphological acceleration factor (Morfac) has been used for over two decades to speed-up long term morphodynamic simulations. However, the Morfac values are usually set heuristically and hardly any study investigated theoretically the critical Morfac value leading to a predefined level of accuracy. In this research, we evaluated theoretically the critical Morfac value from the analysis of the amplitude and phase errors induced by the use of Morfac. While the few existing studies focused only on relatively low Froude numbers and a single mathematical formulation of the morphodynamic model, we consider here a significantly wider range of Froude numbers, including supercritical flow, and we compare four different model formulations. We show that the model formulation leading to the highest critical Morfac values for subcritical flow is not the same as for supercritical flow. [less ▲]

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See detailAnalogies entre deux querelles relatives à l'enseignement des mathématiques en Belgique
Bair, Jacques ULiege

E-print/Working paper (2020)

Depuis la création du royaume de Belgique, l’enseignement de base des mathématiques a connu dans ce pays deux importantes querelles : la guerre entre infinicoles et infinifuges au début du 19e siècle et ... [more ▼]

Depuis la création du royaume de Belgique, l’enseignement de base des mathématiques a connu dans ce pays deux importantes querelles : la guerre entre infinicoles et infinifuges au début du 19e siècle et la guerre des mathématiques modernes durant la seconde moitié du 20e siècle. Ces deux épisodes historiques présentent des analogies qui vont être analysées dans cet article. Sont en présence deux clans avec des visions différentes sur la nécessité ou non de renouveler le savoir à enseigner, de modifier l’approche didactique, d’accorder de l’importance à l’aspect utilitaire de la discipline. Au surplus, dans les deux cas, le camp des conservateurs et des adeptes d’un enseignement simple et axé sur les applications était emmené avec ardeur par un liégeois, professeur à l’Université de Liège ; on pourrait y voir une manifestation de l’« esprit liégeois ». [less ▲]

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Peer Reviewed
See detailLes migrations environnementales : un nouvel objet d’enseignement
Merenne-Schoumaker, Bernadette ULiege

E-print/Working paper (2020)

À partir d'idées reçues sur les migrants climatiques et environnementaux, l'autrice examine la difficulté à nommer et à quantifier ce phénomène avant de faire le point sur l'état actuel des connaissances ... [more ▼]

À partir d'idées reçues sur les migrants climatiques et environnementaux, l'autrice examine la difficulté à nommer et à quantifier ce phénomène avant de faire le point sur l'état actuel des connaissances. Elle montre ensuite comment cette question peut s'insérer dans les programmes de géographie de l'enseignement secondaire. Une place particulière est accordée aux documents, aux outils et aux démarches possibles. [less ▲]

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See detailEre « après COVID-19 » : les publicités promeuvent des voitures toujours plus polluantes.
Ozer, Pierre ULiege

E-print/Working paper (2020)

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See detailBank risk-taking and Competition: Does efficiency matter? Evidence from African Banking Industry
Matabaro, Borauzima Luc ULiege; Muller, Aline ULiege

E-print/Working paper (2020)

We contribute to the existing literature on the nexus between competition and risk taking in the banking industry by emphasizing the role of efficiency. We test a modified Martinez-Miera and Repullo (2010 ... [more ▼]

We contribute to the existing literature on the nexus between competition and risk taking in the banking industry by emphasizing the role of efficiency. We test a modified Martinez-Miera and Repullo (2010)’s model which uses a single factor Vasiceck specification to analyze default’s probability for a set of loans. Our results confirm that efficiency plays a non-monotonic role in the competition-risk relationship. On top of confirming the U-shape relationship between competition and risk-taking, our reveal that banks with high and low efficiency take more risk than those with average efficiency ones. We also find that size, diversification index, macroeconomic, institutional play a key role in competition-risking-taking process in African banking industry. Besides, African Cross-border banks display less riskiness and may accordingly enhance financial stability. These results are stable across different robustness checks including alternative measures of competition and specifications and consequently serve for regulatory policies especially for providing very stringent regulatory frameworks to mitigate the implications of competition in terms of financial stability. [less ▲]

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See detailFermeture des frontières nationales : récits en territoire transfrontalier
Caesar, Beate; Dorkel, Nicolas; Marbehant, Sylvain ULiege et al

E-print/Working paper (2020)

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See detail$\pi$ Earth: a 3.14 days Earth-sized Planet from \textit{K2}'s Kitchen served warm by the SPECULOOS Team
Niraula, Prajwal; de Wit, Julien; Rackham, Benjamin V. et al

E-print/Working paper (2020)

We report on the discovery of a transiting Earth-sized (0.95$R_\oplus$) planet around an M3.5 dwarf star at 57\,pc, EPIC~249631677. The planet has a period of $\sim$3.14 days, i.e. ${\sim}\pi$, with an ... [more ▼]

We report on the discovery of a transiting Earth-sized (0.95$R_\oplus$) planet around an M3.5 dwarf star at 57\,pc, EPIC~249631677. The planet has a period of $\sim$3.14 days, i.e. ${\sim}\pi$, with an instellation of 7.5\,S$_{\oplus}$. The detection was made using publicly available data from \textit{K2}'s Campaign 15. We observed three additional transits with SPECULOOS Southern and Northern Observatories, and a stellar spectrum from Keck/HIRES, which allowed us to validate the planetary nature of the signal. The confirmed planet is well suited for comparative terrestrial exoplanetology. While exoplanets transiting ultracool dwarfs present the best opportunity for atmospheric studies of terrestrial exoplanets with the \textit{James Webb Space Telescope}, those orbiting mid-M dwarfs within 100\,pc such as EPIC~249631677b will become increasingly accessible with the next generation of observatories (e.g., \textit{HabEx, LUVOIR, OST}). [less ▲]

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See detailEntretien avec Côme Martin-Karl : « peut-on écrire après Duras ? »
Lansmans, Alexandre ULiege

E-print/Working paper (2020)

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See detailLearning optimal environments using projected stochastic gradient ascent
Bolland, Adrien ULiege; Boukas, Ioannis ULiege; Cornet, François ULiege et al

E-print/Working paper (2020)

In this work, we generalize the direct policy search algorithms to an algorithm we call Direct Environment Search with (projected stochastic) Gradient Ascent (DESGA). The latter can be used to jointly ... [more ▼]

In this work, we generalize the direct policy search algorithms to an algorithm we call Direct Environment Search with (projected stochastic) Gradient Ascent (DESGA). The latter can be used to jointly learn a reinforcement learning (RL) environment and a policy with maximal expected return over a joint hypothesis space of environments and policies. We illustrate the performance of DESGA on two benchmarks. First, we consider a parametrized space of Mass-Spring Damper (MSD) environments. Then, we use our algorithm for optimizing the size of the components and the operation of a small-scale and autonomous energy system, i.e. a solar off-grid microgrid, composed of photovoltaic panels, batteries, etc. The results highlight the excellent performances of the DESGA algorithm. [less ▲]

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See detail新型コロナウィルス時代の情熱とは
Badir, Sémir ULiege

E-print/Working paper (2020)

Detailed reference viewed: 58 (1 ULiège)
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See detailA bio-inspired bistable recurrent cell allows for long-lasting memory
Vecoven, Nicolas ULiege; Ernst, Damien ULiege; Drion, Guillaume ULiege

E-print/Working paper (2020)

Recurrent neural networks (RNNs) provide state-of-the-art performances in a wide variety of tasks that require memory. These performances can often be achieved thanks to gated recurrent cells such as ... [more ▼]

Recurrent neural networks (RNNs) provide state-of-the-art performances in a wide variety of tasks that require memory. These performances can often be achieved thanks to gated recurrent cells such as gated recurrent units (GRU) and long short-term memory (LSTM). Standard gated cells share a layer internal state to store information at the network level, and long term memory is shaped by network-wide recurrent connection weights. Biological neurons on the other hand are capable of holding information at the cellular level for an arbitrary long amount of time through a process called bistability. Through bistability, cells can stabilize to different stable states depending on their own past state and inputs, which permits the durable storing of past information in neuron state. In this work, we take inspiration from biological neuron bistability to embed RNNs with long-lasting memory at the cellular level. This leads to the introduction of a new bistable biologically-inspired recurrent cell that is shown to strongly improves RNN performance on time-series which require very long memory, despite using only cellular connections (all recurrent connections are from neurons to themselves, i.e. a neuron state is not influenced by the state of other neurons). Furthermore, equipping this cell with recurrent neuromodulation permits to link them to standard GRU cells, taking a step towards the biological plausibility of GRU. [less ▲]

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See detailRobustness of Pisot-regular sequences
Charlier, Emilie ULiege; Cisternino, Célia ULiege; Stipulanti, Manon ULiege

E-print/Working paper (2020)

We consider numeration systems based on a d-tuple U=(U_1,...,U_d) of sequences of integers and we define (U,K)-regular sequences through K-recognizable formal series, where K is any semiring. We show that ... [more ▼]

We consider numeration systems based on a d-tuple U=(U_1,...,U_d) of sequences of integers and we define (U,K)-regular sequences through K-recognizable formal series, where K is any semiring. We show that, for any d-tuple U of Pisot numeration systems and any commutative semiring K, this definition does not depend on the greediness of the U-representations of integers. The proof is constructive and is based on the fact that the normalization is realizable by a 2d-tape finite automaton. In particular, we use an ad hoc operation mixing a 2d-tape automaton and a K-automaton in order to obtain a new K-automaton. [less ▲]

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See detailAn Artificial Intelligence Solution for Electricity Procurement in Forward Markets
Théate, Thibaut ULiege; Mathieu, Sébastien ULiege; Ernst, Damien ULiege

E-print/Working paper (2020)

Retailers and major consumers of electricity generally purchase an important percentage of their estimated electricity needs years ahead in the forward market. This long-term electricity procurement task ... [more ▼]

Retailers and major consumers of electricity generally purchase an important percentage of their estimated electricity needs years ahead in the forward market. This long-term electricity procurement task consists of determining when to buy electricity so that the resulting energy cost is minimised, and the forecast consumption is covered. In this scientific article, the focus is set on a yearly base load product from the Belgian forward market, named calendar (CAL), which is tradable up to three years ahead of the delivery period. This research paper introduces a novel algorithm providing recommendations to either buy electricity now or wait for a future opportunity based on the history of CAL prices. This algorithm relies on deep learning forecasting techniques and on an indicator quantifying the deviation from a perfectly uniform reference procurement policy. On average, the proposed approach surpasses the benchmark procurement policies considered and achieves a reduction in costs of 1.65% with respect to the perfectly uniform reference procurement policy achieving the mean electricity price. Moreover, in addition to automating the complex electricity procurement task, this algorithm demonstrates more consistent results throughout the years compared to the benchmark policies. Eventually, the generality of the solution presented makes it well suited for solving other commodity procurement problems. [less ▲]

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See detailA phylodynamic workflow to rapidly gain insights into the dispersal history and dynamics of SARS-CoV-2 lineages
Dellicour, Simon; Durkin, Keith ULiege; Hong, Samuel et al

E-print/Working paper (2020)

Since the start of the COVID-19 pandemic, an unprecedented number of genomic sequences of the causative virus (SARS-CoV-2) have been publicly released. The resulting volume of available genetic data ... [more ▼]

Since the start of the COVID-19 pandemic, an unprecedented number of genomic sequences of the causative virus (SARS-CoV-2) have been publicly released. The resulting volume of available genetic data presents a unique opportunity to gain real-time insights into the pandemic, but also a daunting computational hurdle if analysed with gold-standard phylogeographic methods. We here describe and apply an analytical pipeline that is a compromise between fast and rigorous analytical steps. As a proof of concept, we focus on Belgium, one of the countries with the highest spatial density of sequenced SARS-CoV-2 genomes. At the global scale, our analyses confirm the importance of external introduction events in establishing transmission chains in the country. At the country scale, our spatially-explicit phylogeographic analyses highlight an impact of the national lockdown of mid-March on the dispersal velocity of viral lineages. Our pipeline has the potential to be quickly applied to other countries or regions, with key benefits in complementing epidemiological analyses in assessing the impact of intervention measures or their progressive easement. [less ▲]

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See detailDes infinicoles liégeois
Bair, Jacques ULiege

E-print/Working paper (2020)

L’histoire de l’analyse mathématique est à la fois longue et riche, puisque cette théorie n’a cessé de se développer depuis l’Antiquité en empruntant essentiellement deux voies différentes selon que le ... [more ▼]

L’histoire de l’analyse mathématique est à la fois longue et riche, puisque cette théorie n’a cessé de se développer depuis l’Antiquité en empruntant essentiellement deux voies différentes selon que le concept d’infiniment petit est utilisé ou au contraire proscrit. Les mathématiciens qui exploitent des infiniment petits sont appelés « infinicoles » ; cet adjectif est formé du mot « infini » suivi du suffixe « cole » venant du verbe latin « colere » dont une traduction en français peut être « cultiver ». Ceux qui rejettent les infinitésimaux sont nommés des « infinifuges », car le suffixe « fuge » provient du substantif latin « fuga » signifiant « fuite », de sorte que les infinifuges évitent ou fuient les infiniment. Notre travail est consacré à certains infinicoles qui ne rejettent pas une conception actuelle de l’infini. Plus précisément, nous nous intéressons aux infinicoles qui ont fait appel, dans certains de leurs écrits, à des infiniment petits au sens des pionniers de l’analyse classique, c’est-à-dire aux infinicoles qui n’utilisent pas la théorie weierstrassienne des limites, mais qui recourent plutôt à ce que l’on appelle aujourd’hui l’analyse non standard. Parmi ceux-ci, nous retenons uniquement des liégeois, c’est-à-dire des mathématiciens qui ont habité dans la province de Liège pendant au moins une partie de leur carrière professionnelle. Ils ont tous travaillé, à un moment de leur carrière, à l’Université de Liège (sauf le plus ancien d’entre eux parce que l’Université n’existait pas encore de son temps). Ainsi, neuf mathématiciens sont succinctement présentés. Une liste exhaustive de leur production dans ce domaine figure dans une bibliographie détaillée. [less ▲]

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See detailСтрасти в эпоху COVID
Badir, Sémir ULiege

E-print/Working paper (2020)

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See detailWhen and How Does Law Effectively Reduce the Practice of Female Genital Mutilation/Cutting: A crossborder Study in Burkina Faso and Mali [Policy Brief]
Wouango, Joséphine ULiege; Ostermann, L. Susan; Mwanga, Daniel

E-print/Working paper (2020)

This policy brief summarises key findings from a cross-border study of two neighbouring countries: Burkina Faso, which has a strong FGM/C law, and Mali, which has no specific FGM/C law (Wouango, Ostermann ... [more ▼]

This policy brief summarises key findings from a cross-border study of two neighbouring countries: Burkina Faso, which has a strong FGM/C law, and Mali, which has no specific FGM/C law (Wouango, Ostermann, and Mwanga 2020). The aim of the cross-border study was to explore and compare attitudes and tendencies towards obeying the law and continuing FGM/C practises and to understand the effectiveness of criminal law in combatting FGM/C in both countries. [less ▲]

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See detailDans quelles conditions la loi est-elle efficace pour réduire la pratique des mutilations génitales féminines/excision: Une étude transfrontalière au Burkina Faso et au Mali [Policy Brief]
Wouango, Joséphine ULiege; Ostermann, Susan; Mwanga, Daniel

E-print/Working paper (2020)

Cette note de synthèse résume les principales conclusions d'une étude transfrontalière portant sur deux pays voisins : le Burkina Faso, qui dispose d'une loi forte sur les MGF/E, et le Mali, qui n'a pas ... [more ▼]

Cette note de synthèse résume les principales conclusions d'une étude transfrontalière portant sur deux pays voisins : le Burkina Faso, qui dispose d'une loi forte sur les MGF/E, et le Mali, qui n'a pas de loi spécifique sur les MGF/E (Wouango, Ostermann, et Mwanga 2020). Les objectifs de l'étude transfrontalière étaient d'explorer et de comparer les attitudes et les tendances en matière de respect de la loi et de poursuite de la pratique des MGF/E, et de comprendre l'efficacité du droit pénal dans la lutte contre les MGF/E dans les deux pays. [less ▲]

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See detailLa sagesse des marchés
Choffray, Jean-Marie ULiege

E-print/Working paper (2020)

Soyons précis ! Ne pas croire dans le SARS-CoV-2 – comme seul facteur explicatif de la réalité à laquelle nous sommes confrontés –, n’implique pas d’en nier l’existence ; de ne pas respecter la douleur de ... [more ▼]

Soyons précis ! Ne pas croire dans le SARS-CoV-2 – comme seul facteur explicatif de la réalité à laquelle nous sommes confrontés –, n’implique pas d’en nier l’existence ; de ne pas respecter la douleur de celles et ceux qu’il touche ; de manquer de respect pour le courage et la générosité exemplaires des personnels impliqués ; ou d’en contester les inévitables et sévères conséquences sur le fonctionnement de la société. Tout au contraire, cette posture intellectuelle entraîne la nécessité d’en analyser, scrupuleusement et scientifiquement, toutes les dimensions et implications. La diversité, la complexité et la réflexivité de ces dernières invitent à la patience et à la plus grande circonspection. C’est à ce niveau que les marchés financiers offrent une plateforme technologique et un laboratoire expérimental exceptionnels d’observation, d’analyse et de prévision. Leur sagesse actuelle est un appel à la raison, au comportement responsable, à la vigilance civique, et au retour progressif, mais résolu, à la vie sociale ! [less ▲]

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See detailVers ma réussite en Bac 1 : Positionnement, pistes d'évaluation et de régulation d'un dispositif propédeutique transversal en blended learning
Dupont, Bruno ULiege; Cocinas Garcia, Amélie ULiege

E-print/Working paper (2020)

Ce travail en cours détaille le passage d'un dispositif du présentiel au blended learning d'un dispositif propédeutique de soutien à la réussite en Bac 1 à la Haute École de la Ville de Liège. Sont ... [more ▼]

Ce travail en cours détaille le passage d'un dispositif du présentiel au blended learning d'un dispositif propédeutique de soutien à la réussite en Bac 1 à la Haute École de la Ville de Liège. Sont détaillées le développement du projet, son état actuel, ainsi que ses perspectives de régulation et d'évaluation. [less ▲]

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See detailOral Chloroquine treatment for COVID-19 infection. Available data from literature & field practices on April 20, 2020 (ver 1.8)
Jamoulle, Marc ULiege

E-print/Working paper (2020)

Publications addressing the treatment of COVID-19 by Hydroxychloroquine available on April 20, 2020. gathered sinc March 13, 2020. This compilation does not constitute a recommendation to use the HCQ in ... [more ▼]

Publications addressing the treatment of COVID-19 by Hydroxychloroquine available on April 20, 2020. gathered sinc March 13, 2020. This compilation does not constitute a recommendation to use the HCQ in the treatment of Covid-19 [less ▲]

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See detailModèles mathématiques et confinement
Rigo, Michel ULiege

E-print/Working paper (2020)

En cette période de confinement dû à la crise sanitaire provoquée par le SARS-CoV-2 mieux connu comme Coronavirus, le virus responsable du COVID-19, je voulais comprendre les modèles utilisés par les ... [more ▼]

En cette période de confinement dû à la crise sanitaire provoquée par le SARS-CoV-2 mieux connu comme Coronavirus, le virus responsable du COVID-19, je voulais comprendre les modèles utilisés par les virologues et épidémiologistes du monde entier. Par la même occasion, je m'en vais vous expliquer ces courbes que l'on trouve à longueur de journée dans les média et que l'on souhaite "aplatir". Habitué à la vulgarisation mathématique, je ne suis pourtant pas un spécialiste des mathématiques appliquées et de la modélisation. Il ne nécessite a priori que très peu de connaissances mathématiques : un peu de bon sens et la manipulation des proportions. Il devrait être accessible dès la 4e année de l'enseignement secondaire. [less ▲]

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See detailÉvaluer les effets des différentes mesures de lutte contre le Covid-19, mission impossible?
Paul, Elisabeth ULiege; Ridde, Valéry

E-print/Working paper (2020)

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See detailLong Way to Universal Health Coverage (UHC): Are Policy Dialogue Processes Appropriate to Negotiate Trade-Offs in Africa? The Cases of Benin and Senegal
Paul, Elisabeth ULiege; Fecher-Bourgeois, Fabienne ULiege; Deville, Céline ULiege et al

E-print/Working paper (2020)

The numerous stakeholders involved in the development of universal health coverage (UHC) policies are likely to have diverging interests about which dimensions to prioritize, hence the importance of ... [more ▼]

The numerous stakeholders involved in the development of universal health coverage (UHC) policies are likely to have diverging interests about which dimensions to prioritize, hence the importance of ensuring an effective and transparent policy dialogue. This paper aims to investigate whether or not UHC policy dialogue processes are functioning well in Benin and Senegal. Based on a literature review, we have identified a number of characteristics guaranteeing the quality of policy dialogue processes, which we have integrated into an analytical grid. The quality criteria identified were classified along four dimensions: stakeholder participation, dialogue/negotiation process, quality of situation analysis and decision criteria, and results from the negotiation process. Based on data collected through documentary review, interviews, an electronic survey and the authors’ own experience, we applied that analytical grid to the cases of Benin and Senegal. In both countries, the policy dialogue processes are largely imperfect in terms of many of the quality criteria identified. Decisions were made under strong political leadership, ensuring government coordination and ownership, and strong emphasis has been put on expanding financial risk protection. Yet, both countries perform poorly in a number of dimensions, especially with regards to conflicts of interest, transparency and accountability. None of them has really institutionalized a UHC policy dialogue process, and the UHC policymaking processes have actually bypassed existing health sector coordination mechanisms. The two countries perform well regarding the quality of situation analysis. A small (in the case of Benin) or broader (in the case of Senegal) governmental coalition managed to impose its views, given insufficient stakeholder participation. Policy networks were particularly influential in Senegal. Overall, there are important gaps that reduce the quality of UHC policy dialogue processes, hence explaining the weaknesses in their results in terms of transparency and accountability. Our analytical framework enables us to identify rooms for improvement with regard to country-led negotiation processes relating to UHC. [less ▲]

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See detailA Deep Reinforcement Learning Framework for Continuous Intraday Market Bidding
Boukas, Ioannis ULiege; Ernst, Damien ULiege; Théate, Thibaut ULiege et al

E-print/Working paper (2020)

The large integration of variable energy resources is expected to shift a large part of the energy exchanges closer to real-time, where more accurate forecasts are available. In this context, the short ... [more ▼]

The large integration of variable energy resources is expected to shift a large part of the energy exchanges closer to real-time, where more accurate forecasts are available. In this context, the short-term electricity markets and in particular the intraday market are considered a suitable trading floor for these exchanges to occur. A key component for the successful renewable energy sources integration is the usage of energy storage. In this paper, we propose a novel modelling framework for the strategic participation of energy storage in the European continuous intraday market where exchanges occur through a centralized order book. The goal of the storage device operator is the maximization of the profits received over the entire trading horizon, while taking into account the operational constraints of the unit. The sequential decision-making problem of trading in the intraday market is modelled as a Markov Decision Process. An asynchronous version of the fitted Q iteration algorithm is chosen for solving this problem due to its sample efficiency. The large and variable number of the existing orders in the order book motivates the use of high-level actions and an alternative state representation. Historical data are used for the generation of a large number of artificial trajectories in order to address exploration issues during the learning process. The resulting policy is back-tested and compared against a benchmark strategy that is the current industrial standard. Results indicate that the agent converges to a policy that achieves in average higher total revenues than the benchmark strategy. [less ▲]

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See detailHigh Order Relaxation Methods for Co-simulation of Finite Element and Circuit Solvers
Nshimiyimana, Jean de Dieu ULiege; Plumier, Frédéric; Ndagije, Charles et al

E-print/Working paper (2020)

Coupled problems result in very stiff problems whose char- acteristic parameters differ with several orders in magni- tude. For such complex problems, solving them monolith- ically becomes prohibitive ... [more ▼]

Coupled problems result in very stiff problems whose char- acteristic parameters differ with several orders in magni- tude. For such complex problems, solving them monolith- ically becomes prohibitive. Since nowadays there are op- timized solvers for particular problems, solving uncoupled problems becomes easy since each can be solved indepen- dently with its dedicated optimized tools. Therefore the co-simulation of the sub-problems solvers is encouraged. The design of the transmission coupling conditions between solvers plays a fundamental role. The current paper applies the waveform relaxation methods for co-simulation of the finite element and circuit solvers, investigate the contribu- tion of higher order integration methods and also consid- ers the the theoretical modelling of a boost converter. The method is illustrated on a coupled finite element inductor and a boost converter and focuses on the comparison of the transmission coupling conditions based on the waveform iteration numbers between the two sub-solvers. We demon- strate that for lightly coupled systems the dynamic itera- tions between the sub-solvers depends much on the inter- nal integrators in individual sub-solvers whereas for tightly coupled systems it depends also to the kind of transmission coupling conditions. [less ▲]

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See detailLuciano Curreri e la letteratura
Curreri, Luciano ULiege

E-print/Working paper (2020)

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See detailThe CARMENES search for exoplanets around M dwarfs. Two planets on the opposite sides of the radius gap transiting the nearby M dwarf LP 729-54
Nowak, G.; Luque, R.; Parviainen, H. et al

E-print/Working paper (2020)

We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d ~ 22 pc), bright (J ~ 9 mag) M3.5 dwarf LP 729 ... [more ▼]

We present the discovery and characterisation of two transiting planets observed by the Transiting Exoplanet Survey Satellite (TESS) orbiting the nearby (d ~ 22 pc), bright (J ~ 9 mag) M3.5 dwarf LP 729-54 (TOI-732). We confirm both planets and their association with LP 729-54 via ground-based photometry and determine their masses using precise radial velocities measured with the CARMENES spectrograph. Precise stellar parameters determined from CARMENES high resolution spectra confirm that LP 729-54 is a mid-M dwarf with an effective temperature of T_eff = 3360 +\- 51 K, a surface gravity of log(g) = 4.81 +/- 0.04 (cgs), and an iron abundance of [Fe/H] = 0.09 +/- 0.16 dex, with an inferred mass of M_star = 0.379 +/- 0.016 M_sun and a radius of R_star = 0.382 +/- 0.012 R_sun. The ultra-short period planet LP 729-54 b (P_b = 0.77 d) with a radius of 1.35^{+0.06}_{-0.06} R_earth, a mass of 2.34^{+0.24}_{-0.23} M_earth, and a bulk density of 5.24^{+0.94}_{-0.81} g cm^{-3} joins the population of Earth-size planets with rocky, terrestrial composition. The outer planet, LP 729-54 c, with an orbital period of 12.25 d, radius of 2.42^{+0.10}_{-0.10} R_earth, mass of 6.29^{+0.63}_{-0.61} M_earth, and mean density of 2.45^{+0.44}_{-0.37} g cm^{-3} belongs to the population of dense sub-Neptunes. With the two planets located on opposite sides of the radius gap, this planetary system is an excellent target for testing planetary formation, evolution and atmospheric models. In particular, LP 729-54 c is an ideal object for atmospheric studies with the James Webb Space Telescope. [less ▲]

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See detailThree Short Period Jupiters from TESS
Nielsen, L. D.; Brahm, R.; Bouchy, F. et al

E-print/Working paper (2020)

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period ... [more ▼]

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V=11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 +/- 0.078 Mjup planet in a grazing transit configuration with impact parameter b = 1.17 +0.10/-0.08. As a result the radius is poorly constrained, 2.03 +0.61/-0.49 Rjup. We perform a full phase-curve analysis of the TESS data and detect both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass 1.18 +/- 0.13 Mjup and radius 1.29 +/- 0.02 Rjup. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V=12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V=12.4 G-type star. It has a mass of 0.79 +/- 0.06 Mjup and radius 1.09 +0.08/-0.05 Rjup. Despite having the longest orbital period (P=2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with Fe/H ranging from 0.18 - 0.24. [less ▲]

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See detailSPHERE+: Imaging young Jupiters down to the snowline
Boccaletti, A.; Chauvin, G.; Mouillet, D. et al

E-print/Working paper (2020)

SPHERE (Beuzit et al,. 2019) has now been in operation at the VLT for more than 5 years, demonstrating a high level of performance. SPHERE has produced outstanding results using a variety of operating ... [more ▼]

SPHERE (Beuzit et al,. 2019) has now been in operation at the VLT for more than 5 years, demonstrating a high level of performance. SPHERE has produced outstanding results using a variety of operating modes, primarily in the field of direct imaging of exoplanetary systems, focusing on exoplanets as point sources and circumstellar disks as extended objects. The achievements obtained thus far with SPHERE (~200 refereed publications) in different areas (exoplanets, disks, solar system, stellar physics...) have motivated a large consortium to propose an even more ambitious set of science cases, and its corresponding technical implementation in the form of an upgrade. The SPHERE+ project capitalizes on the expertise and lessons learned from SPHERE to push high contrast imaging performance to its limits on the VLT 8m-telescope. The scientific program of SPHERE+ described in this document will open a new and compelling scientific window for the upcoming decade in strong synergy with ground-based facilities (VLT/I, ELT, ALMA, and SKA) and space missions (Gaia, JWST, PLATO and WFIRST). While SPHERE has sampled the outer parts of planetary systems beyond a few tens of AU, SPHERE+ will dig into the inner regions around stars to reveal and characterize by mean of spectroscopy the giant planet population down to the snow line. Building on SPHERE's scientific heritage and resounding success, SPHERE+ will be a dedicated survey instrument which will strengthen the leadership of ESO and the European community in the very competitive field of direct imaging of exoplanetary systems. With enhanced capabilities, it will enable an even broader diversity of science cases including the study of the solar system, the birth and death of stars and the exploration of the inner regions of active galactic nuclei. [less ▲]

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See detailNote relative à l’Agenda urbain de l’UE
Lejeune, Zoé ULiege; Claeys, Dorian ULiege

E-print/Working paper (2020)

Cette note explique le processus de l'Agenda urbain de l'UE pour toute personne ou autorité intéressée de mieux comprendre la dynamique.

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See detailA Real-Time Receding-Horizon Transmission Voltages Control using Sensitivity Matrix and Bias
Glavic, Mevludin ULiege

E-print/Working paper (2020)

In this paper, a simplified multi-step recedinghorizon controller is introduced to control the violations in transmission voltages and stop developing long-term voltage instabilities. The system model is ... [more ▼]

In this paper, a simplified multi-step recedinghorizon controller is introduced to control the violations in transmission voltages and stop developing long-term voltage instabilities. The system model is derived from the context of quadratic dynamic matrix control and is represented as a set of linear constraints derived from sensitivity analysis and bias terms acting as modelling error corrector. Resulting multi-step optimization is highly structured convex quadratic programming problem for which reliable standard codes are available. The goal of proposed controller is to achieve high performances with simplified system model relying on reliable optimization solver. The Nordic32 test system is used for evaluating the performance of proposed controller and its comparison with existing closely related approaches focusing on minimization of expensive controls (load shedding). [less ▲]

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See detailElectron-lattice interplays in LaMnO 3 from canonical Jahn-Teller distortion notations
Schmitt, Michaël ULiege; Zhang, Yajun; Mercy, Alain ULiege et al

E-print/Working paper (2020)

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See detailSeraing, ville post-industrielle en pleine reconversion, se penche sur le défi de la réactivation de son bâti vacant
Lejeune, Zoé ULiege

E-print/Working paper (2020)

Interview avec la ville de Seraing dans le cadre de sa participation au réseau URBACT "AltBau" qui travaille à une stratégie de réactivation des immeubles inoccupés.

Detailed reference viewed: 36 (1 ULiège)
See detailImmigration, Welfare and Inequality: How Much Does the Labor Market Specification Matter?
Docquier, Frédéric; Ikhenaode, Bright Isaac; Scheewel, Hendrik ULiege

E-print/Working paper (2020)

Macroeconomic models are increasingly used to quantify the welfare and inequality effects of immigration in the OECD countries. Existing studies differ in the way they formalize the labor market responses ... [more ▼]

Macroeconomic models are increasingly used to quantify the welfare and inequality effects of immigration in the OECD countries. Existing studies differ in the way they formalize the labor market responses for immigrants and natives, which in turn govern the strength of the other transmission channels (e.g., public finances, price index, or total factor productivity). In this paper, we build a general equilibrium model that allows to gauge the role of the labor market specification. We parameterize the model for 20 selected OECD member states and compare several specifications involving different assumptions concerning labor supply decisions, unemployment rates and wage formation, as well as different calibration strategies. Endogenizing unemployment and participation generates slightly more optimistic results. However, these labor market mechanisms do not reverse the findings of models based on simpler assumptions and have little effects on cross-country differences in responses to immigration. The labor market specification is less important than the calibration of the elasticity of substitution between immigrants and natives. [less ▲]

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See detailLe pouvoir poétique des images de cinéma
Badir, Sémir ULiege

E-print/Working paper (2020)

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See detailSalon de l’auto 2020 : des voitures « toujours plus durables et plus propres ». Vraiment ?
Ozer, Pierre ULiege

E-print/Working paper (2020)

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See detailUn savant dans l'Ouest : Jean-Charles Houzeau de Lehaie ou l'évolutionnisme nomade
Royen, Virgile ULiege

E-print/Working paper (2020)

Ce récit raconte l'exil de Jean-Charles Houzeau de Lehaie, astronome belge, dans le Nouveau Monde. Son esprit indépendant et son opposition à l'esclavage dans le contexte de la Guerre de Sécession le ... [more ▼]

Ce récit raconte l'exil de Jean-Charles Houzeau de Lehaie, astronome belge, dans le Nouveau Monde. Son esprit indépendant et son opposition à l'esclavage dans le contexte de la Guerre de Sécession le conduisirent régulièrement à arpenter ou vivre en terres sauvages. Au cours de ces pérégrinations exotiques, Houzeau réalisa de nombreuses observations sur la faune, qu'il compila en deux épais volumes, les Études sur les Facultés mentales des animaux comparées à celles de l’Homme. Un livre qui n'ambitionnait pas moins de devancer Darwin lui-même... [less ▲]

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See detailBlanche est la mort
Frankignoulle, Pierre ULiege

E-print/Working paper (2020)

Une nouvelle de 17 pages

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See detailInterstellar comet 2I/Borisov as seen by MUSE: C2, NH2 and red CN detections
Bannister, Michele T.; Opitom, Cyrielle; Fitzsimmons, Alan et al

E-print/Working paper (2020)

We report the clear detection of C$_2$ and of abundant NH$_2$ in the first prominently active interstellar comet, 2I/Borisov. We observed 2I on three nights in November 2019 at optical wavelengths 4800 ... [more ▼]

We report the clear detection of C$_2$ and of abundant NH$_2$ in the first prominently active interstellar comet, 2I/Borisov. We observed 2I on three nights in November 2019 at optical wavelengths 4800--9300 Åwith the Multi-Unit Spectroscopic Explorer (MUSE) integral-field spectrograph on the ESO/Very Large Telescope. These data, together with observations close in time from both 0.6-m TRAPPIST telescopes, provide constraints on the production rates of species of gas in 2I's coma. From the MUSE detection on all epochs of several bands of the optical emission of the C$_2$ Swan system, a rich emission spectrum of NH$_2$ with many highly visible bands, and the red (1-0) bandhead of CN, together with violet CN detections by TRAPPIST, we infer production rates of $Q$(C$_2$) = $1.1\times10^{24}$ mol s$^{-1}$, $Q$(NH$_2$) = $4.8\times10^{24}$ mol s$^{-1}$ and $Q$(CN) = $(1.8\pm0.2)\times 10^{24}$ mol s$^{-1}$. In late November at 2.03~au, 2I had a production ratio of C$_2$/CN$=0.61$, only barely carbon-chain depleted, in contrast to earlier reports measured further from the Sun of strong carbon-chain depletion. Thus, 2I has shown evolution in its C$_2$ production rate: a parent molecule reservoir has started sublimating. At $Q$(NH$_2$)/$Q$(CN) = 2.7, this second interstellar object is enriched in NH$_2$, relative to the known Solar System sample. [less ▲]

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See detailAn Application of Deep Reinforcement Learning to Algorithmic Trading
Théate, Thibaut ULiege; Ernst, Damien ULiege

E-print/Working paper (2020)

This scientific research paper presents an innovative approach based on deep reinforcement learning (DRL) to solve the algorithmic trading problem of determining the optimal trading position at any point ... [more ▼]

This scientific research paper presents an innovative approach based on deep reinforcement learning (DRL) to solve the algorithmic trading problem of determining the optimal trading position at any point in time during a trading activity in the stock market. It proposes a novel DRL trading policy so as to maximise the resulting Sharpe ratio performance indicator on a broad range of stock markets. Denominated the Trading Deep Q-Network algorithm (TDQN), this new DRL approach is inspired from the popular DQN algorithm and significantly adapted to the specific algorithmic trading problem at hand. The training of the resulting reinforcement learning (RL) agent is entirely based on the generation of artificial trajectories from a limited set of stock market historical data. In order to objectively assess the performance of trading strategies, the research paper also proposes a novel, more rigorous performance assessment methodology. Following this new performance assessment approach, promising results are reported for the TDQN algorithm. [less ▲]

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See detailUn risque d'instrumentalisation de l'histoire
Franck, Thomas ULiege

E-print/Working paper (2020)

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See detailSiting Renewable Power Generation Assets with Combinatorial Optimization
Berger, Mathias ULiege; Radu, David-Constantin ULiege; Dubois, Antoine ULiege et al

E-print/Working paper (2020)

This paper studies the problem of siting renewable power generation assets using large amounts of climatological data. The problem is cast as a combinatorial optimisation problem seeking to maximise ... [more ▼]

This paper studies the problem of siting renewable power generation assets using large amounts of climatological data. The problem is cast as a combinatorial optimisation problem seeking to maximise spatiotemporal complementarity between sites while accounting for electrical load level and chronology. Model properties are closely analysed and a formal connection with the problem of maximising a submodular set function subject to a cardinality constraint is established. A custom solution method combining relaxation-based and local search algorithms is also proposed and benchmarked against state-of-the art methods using a realistic instance comprising tens of thousands of variables inspired by the problem of siting onshore wind power plants in Europe. Results show that for the present application, the proposed solution method is competitive with state-of-the-art methods both in terms of computing time and solution quality, as it reaches objective values at least as good as the proposed benchmarks on most instances studied and clearly outperforms them on a number of occasions. In addition, results highlight the importance of combining a relaxation-based method with a local search algorithm to produce high-quality solutions for this application. [less ▲]

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See detailCombining optimization and simulation for microgrid sizing
Dakir, Selmane ULiege; Cornélusse, Bertrand ULiege

E-print/Working paper (2020)

The sizing of a microgrid is a crucial process to ensure safe, efficient and economical operations. It must consider a variety of technologies and the whole life of the project. Hence degradation and ... [more ▼]

The sizing of a microgrid is a crucial process to ensure safe, efficient and economical operations. It must consider a variety of technologies and the whole life of the project. Hence degradation and reinvestment must be accounted for. However, the control algorithm also influences the sizing result, especially if the microgrid is grid-tied, which offers several revenue streams and presents additional constraints such as time-varying connection limits. All this leads to a sizing problem that is large and non-convex. This paper presents a flexible approach to approximate the solution of this problem. The latter is decomposed in three nested sub-problems: the control and simulation of a microgrid for a given configuration and initial state; the evaluation of a configuration and control policy on a sample of representative days; the optimization of the configuration. Case studies highlight the importance of accounting for the control policy and device evolution along their lifetime. [less ▲]

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See detailYAAI: Yet another age inequality
Beckers, Jean-Marie ULiege

E-print/Working paper (2020)

Detailed reference viewed: 43 (1 ULiège)
See detailAlzheimer s disease genetic risk and sleep phenotypes: association with more slow-waves and daytime sleepiness
Muto, Vincenzo ULiege; Koshmanova, Ekaterina ULiege; Ghaemmaghami, Pouya  et al

E-print/Working paper (2020)

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See detailMotivation in schizophrenia: a theory-driven approach using time-series network analysis
Thonon, Bénédicte ULiege; Contreras, Alba; Laroi, Frank ULiege

E-print/Working paper (2020)

Motivational negative symptoms are an important obstacle to the daily functioning of individuals with schizophrenia. A better understanding of associated processes would help to identify targets for ... [more ▼]

Motivational negative symptoms are an important obstacle to the daily functioning of individuals with schizophrenia. A better understanding of associated processes would help to identify targets for interventions. We redefined a theoretical model of motivation in schizophrenia combining cognitive, behavioural and emotional/hedonic processes. Further, we used Experience Sampling Method (ESM) and network analyses to provide a clearer understanding of potential causal factors that may influence the daily course of motivation. Using a 14-day paradigm ESM in 7 participants with schizophrenia spectrum disorders, we examined the interplay between the processes derived from the proposed model. We estimated both contemporaneous and temporal networks using multilevel vector autoregressive analyses for time-series. The contemporaneous network showed that motivation was central and strongly related to levels of energy and (self-)confidence. The temporal network showed that savouring processes (i.e. reminiscence and projection into the future) were the most influential and had an impact on later motivation, mood, effort, energy, (self-)confidence, and dysfunctional beliefs. These findings provide evidence in favour of the motivational model presented in this study, shedding new light on the understanding of motivation in schizophrenia and specifically identifying energy levels, confidence, and savouring skills as likely beneficial targets for interventions. [less ▲]

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See detailOptimal grid regulation with heterogeneous prosumers
Gautier, Axel ULiege; Jacqmin, Julien; Poudou, Jean-Christophe

E-print/Working paper (2020)

We study how metering technologies and tariffs influence heterogeneous energy consumers' decisions to become prosumers by investing in photovoltaic (PV) panels, and the effect of those choices on the cost ... [more ▼]

We study how metering technologies and tariffs influence heterogeneous energy consumers' decisions to become prosumers by investing in photovoltaic (PV) panels, and the effect of those choices on the cost recovery of grid operations. We show that net metering (where prosumers face the same price whether they buy or sell energy) leads to too much PV investment compared to the first-best outcome. We also find that consumers are attracted into prosumption independent of their self-consumption profile, i.e. the extent to which their energy consumption correlates with their production. When a net purchasing system is in place (where prosumers are charged a different price for the energy they buy from the grid than for the energy they export to the grid), consumers with relatively high levels of self-consumption are more likely to invest in PV installations, which is desirable from an efficiency standpoint as these prosumers exchange less with the grid. Even when the regulator lacks information about the self-consumption rate of prosumers, net purchasing can achieve the first-best outcome. [less ▲]

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See detailExpansions in Cantor real bases
Charlier, Emilie ULiege; Cisternino, Célia ULiege

E-print/Working paper (2020)

We introduce and study series expansions of real numbers with an arbitrary Cantor real base. In doing so, we generalize both representations of real numbers in real bases and through Cantor series. We ... [more ▼]

We introduce and study series expansions of real numbers with an arbitrary Cantor real base. In doing so, we generalize both representations of real numbers in real bases and through Cantor series. We show fundamental properties of these new representations, each of which extends existing results on representations in a real base. In particular, we prove a generalization of Parry's theorem characterizing sequences of nonnegative integers that are the greedy representations of some real number in the interval [0,1). We pay special attention to periodic Cantor real bases, which we call alternate bases. In this case, we show that the associated shift is sofic if and only if all quasi-greedy shifted expansions of 1 are ultimately periodic. [less ▲]

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Peer Reviewed
See detailGenebank Platform: GreenPass puts germplasm distribution in the fast lane
Massart, Sébastien ULiege; Major, Michael; Kumar, Lava

E-print/Working paper (2020)

Detailed reference viewed: 23 (1 ULiège)
Peer Reviewed
See detailNotice VANDERRYDT Hippolyte
Georges, Martin ULiege

E-print/Working paper (2020)

Biographie et bibliographie de Hippolyte Vanderrydt (1857 – 1929). Ingénieur, enseignant de l'ULB et de l'Université Nouvelle, militant socialiste (POB), premier traducteur en langue française du livre II ... [more ▼]

Biographie et bibliographie de Hippolyte Vanderrydt (1857 – 1929). Ingénieur, enseignant de l'ULB et de l'Université Nouvelle, militant socialiste (POB), premier traducteur en langue française du livre II (1900) et III (1901-1902) du Capital de Karl Marx avec Julian Borchardt, corédacteur de la Charte de Quaregnon, collaborateur des journaux Le Peuple et L’Avenir social sous le pseudonyme de « LUX », enseignant à la Centrale d’éducation ouvrière et à l’École ouvrière supérieure. [less ▲]

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See detailAssessing the Economic Value of Renewable Resource Complementarity for Power Systems: an ENTSO-E Study
Radu, David-Constantin ULiege; Berger, Mathias ULiege; Dubois, Antoine ULiege et al

E-print/Working paper (2020)

Complementarity of variable renewable energy sources (RES) in both space and time has received a great deal of attention recently however, its value for power systems is still not properly understood ... [more ▼]

Complementarity of variable renewable energy sources (RES) in both space and time has received a great deal of attention recently however, its value for power systems is still not properly understood. This research gap is tackled in the current work by evaluating the benefits of siting RES assets according to resource complementarity criteria. For this purpose, a two-stage method is employed. First, the complementarity between RES is assessed and the locations sets that maximize it are selected using an integer programming model. Subsequently, the outcome of the first stage is used within an expansion planning framework which identifies the optimal system design and serves as basis for assessing the economic value of RES complementarity for power systems. The analysis is conducted on a realistic case study targeting the deployment of 450GW of offshore wind in Europe by 2050. Results show that siting based on RES complementarity is particularly attractive when the power density of wind developments is relatively high and when the inter-annual variability of the underlying resource is considered. More specifically, such a siting strategy leads to yearly savings between 0.3 and 1.2 billion EUR compared with conventional schemes seeking to deploy generation capacity at the most productive locations. [less ▲]

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See detailIncreased cortical excitability and reduced brain response propagation during attentional lapses
Cardone, Paolo ULiege; Van Egroo, Maxime ULiege; Chylinski, Daphné ULiege et al

E-print/Working paper (2020)

Modern lifestyle curtails sleep and increases nighttime work and leisure activities. This has a deleterious impact on vigilance and attention, exacerbating chances of committing attentional lapses, with ... [more ▼]

Modern lifestyle curtails sleep and increases nighttime work and leisure activities. This has a deleterious impact on vigilance and attention, exacerbating chances of committing attentional lapses, with potential dramatic outcomes. A full characterization of the brain mechanisms associated with lapses is still lacking. Here, we investigated the brain signature of attentional lapses and assessed whether cortical excitability and brain response propagation were modified during lapses and whether these modifications changed with aging. We compared electroencephalogram (EEG) responses to transcranial magnetic stimulation (TMS) during lapse and no-lapse periods while performing a continuous attentional/vigilance task at night, after usual bedtime. Data were collected in healthy younger (N=12; 18-30 y) and older individuals (N=12; 50- 70 y) of both sexes. Amplitude and slope of the first component of the TMS-Evoked Potential (TEP) and Response Scattering (ReSc) were used to assess cortical excitability and brain response propagation, respectively. In line with our predictions, TEP during lapses was characterized by larger amplitude and slope. We further found that ReSc over the cortical surface was lower during lapses. Importantly, cortical excitability increase and response propagation decrease during lapse did not significantly differ between age groups. These results demonstrate that attentional lapses are associated with transient increase of excitability, and decrease in response propagation and effective connectivity. This pattern is similar to what is observed during sleep, suggesting that lapses reflect a sleep-like phenomenon. These findings could contribute to develop models aimed to predicting and preventing lapses in real life situations. [less ▲]

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See detailMental resilience in the Corona lockdown: First empirical insights from Europe
Veer, Ilya; Riepenhausen, Antje; Zerban, Matthias et al

E-print/Working paper (2020)

Background: The current Corona pandemic is not only a threat to physical health. First data from China and Europe indicate that symptoms of anxiety and depression and perceptions of stress rise ... [more ▼]

Background: The current Corona pandemic is not only a threat to physical health. First data from China and Europe indicate that symptoms of anxiety and depression and perceptions of stress rise significantly as a consequence of the pandemic. There are also anecdotal reports of increased domestic violence, divorce, and suicide rates. Hence, the Corona crisis is also a mental health crisis. There is urgent need for knowledge about factors that can protect mental health (resilience factors) in this world-wide crisis, which is different in nature from other crises that have so far been studied in resilience research. Methods: Potential resilience factors, exposure to Corona-specific and general stressors, as well as internalizing symptoms were assessed online in N=5000 adult Europeans. Resilience, as an outcome, was conceptualized as good mental health despite stressor exposure and measured as the inverse residual between actual and predicted symptom total score. Preregistered hypotheses (osf.io/r6btn) were tested with multiple regression models and mediation analyses. Results: Results confirmed our primary hypothesis that positive appraisal style (PAS) is positively associated with resilience(p<0.001). The resilience factor PAS also mediated the positive association between perceived social support (PSS) and resilience (p<0.001). In comparison with other resilience factors, positive appraisal specifically of the consequences of the Corona crisis was the single strongest factor. Conclusions: This research identifies modifiable protective factors that can be targeted by public mental health efforts. Future work will have to identify potential group differences in the effectiveness of these resilience factors, for improved prevention planning [less ▲]

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See detailIdiographic analyses of motivation and related processes in participants with schizophrenia following a therapeutic intervention for negative symptoms
Thonon, Bénédicte ULiege; Van Aubel, Evelyne; Lafit, Ginette et al

E-print/Working paper (2020)

Background: Motivational negative symptoms hinder quality of life and daily functioning of individuals with schizophrenia spectrum disorders. A recently developed intervention, Switch, has shown promising ... [more ▼]

Background: Motivational negative symptoms hinder quality of life and daily functioning of individuals with schizophrenia spectrum disorders. A recently developed intervention, Switch, has shown promising effects on negative symptoms and functional outcomes. Switch targets multiple cognitive, emotional and behavioural processes associated with motivation and goal directed behaviours. We aimed to investigate its effects on motivation and associated processes and explore the dynamics between the processes. Methods: We used a single case approach (n = 3), with a pre-post and follow-up assessment design, which also included ambulatory assessments (experience sampling method, ESM; and step count). We computed autoregressive lag 1 models to evaluate the effects of the intervention on daily motivation levels and related processes, descriptive pie-charts, and vector autoregressive modelling to reveal the dynamics of the processes over time. Results: The intervention was beneficial for each participant according to traditional evaluations of motivational negative symptoms, apathy, daily functioning and quality of life. The effects on the ESM variables revealed distinct outcomes for each individual. The dynamics between the various processes differed between participants, and fluctuated within participants (when comparing baseline, intervention phase, and follow-up). Conclusions: This study used an innovative approach to look at the efficacy of an intervention. The intervention seems to lead to significant improvements. The mechanisms of change need to be further investigated. [less ▲]

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See detailCompletion/Drop out and Time to Degree in the PhD track: A Conceptual Literature Review
Aerts, Stéphanie ULiege; Haesbroeck, Gentiane ULiege; Klenkenberg, Sophie ULiege

E-print/Working paper (2020)

Understanding the attrition among PhD candidates and modelling the mean or median time to degree according to certain factors have been at the center of the research interest in higher education for a ... [more ▼]

Understanding the attrition among PhD candidates and modelling the mean or median time to degree according to certain factors have been at the center of the research interest in higher education for a long time. This paper presents a conceptual literature review divided into two parts. First, the multitude of factors used to explain the doctoral outcome is presented and results concerning their impact are summarized. We also propose explanations for potentially controversial findings and advice on the proper use of these factors. Then, an overview of the most common statistical techniques employed is displayed. The authors argue that some techniques are more adapted than others to deal with such data and the issues of interest and they give recommendations about the most appropriate techniques. They also highlight some of the key points that are essential to consider in order to conduct an adequate statistical analysis when dealing with PhD data. An overall conclusion is that there is much variability in the factors and their definitions, the same comment holding for the techniques. This explains why studies end up with different (sometimes controversial) results. [less ▲]

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See detailFighting against homesickness
Lara Guerrero, Larisa Viridiana ULiege

E-print/Working paper (2020)

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See detailAge dating of an early Milky Way merger via asteroseismology of the naked-eye star ν Indi
Chaplin, W. J.; Serenelli, A. M.; Miglio, A. et al

E-print/Working paper (2020)

Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct ... [more ▼]

Over the course of its history, the Milky Way has ingested multiple smaller satellite galaxies1. Although these accreted stellar populations can be forensically identified as kinematically distinct structures within the Galaxy, it is difficult in general to date precisely the age at which any one merger occurred. Recent results have revealed a population of stars that were accreted via the collision of a dwarf galaxy, called Gaia–Enceladus1, leading to substantial pollution of the chemical and dynamical properties of the Milky Way. Here we identify the very bright, naked-eye star ν Indi as an indicator of the age of the early in situ population of the Galaxy. We combine asteroseismic, spectroscopic, astrometric and kinematic observations to show that this metal-poor, alpha-element-rich star was an indigenous member of the halo, and we measure its age to be 11.0 ± 0.7 (stat) ± 0.8 (sys) billion years. The star bears hallmarks consistent with having been kinematically heated by the Gaia–Enceladus collision. Its age implies that the earliest the merger could have begun was 11.6 and 13.2 billion years ago, at 68% and 95% confidence, respectively. Computations based on hierarchical cosmological models slightly reduce the above limits. © 2020, The Author(s), under exclusive licence to Springer Nature Limited. [less ▲]

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See detailTranscending the transcendental: Towards a constructive critical sociology
Frère, Bruno ULiege; Jaster, Dan

E-print/Working paper (2020)

This article calls for a rethinking of critical sociology. The popular Bourdieusian paradigm effectively highlighted how domination persists, but its negative foundation removes the voices of actors by ... [more ▼]

This article calls for a rethinking of critical sociology. The popular Bourdieusian paradigm effectively highlighted how domination persists, but its negative foundation removes the voices of actors by privileging sociological knowledge as capable of identifying transcendental categories of thought. Latourian critical theory arose in opposition to this privileging, but underplayed the roles of domination and power dynamics, and thus critique. We propose a perspective that evades the transcendental perspective which relies on pure negation but allows critique; a more positive critical sociology. This alternative perspective is founded on processualist, phenomenological, pragmatic, and utopian perspectives, which levels the distinction between social scientists and social actors. Focusing on process, not privileged knowledge of transcendental truths, emphasizes actors’ own critical capacities: critical scholars do not dominate, but help actors build better worlds based on their own perspectives and pasts. Thus, critical sociology does not negate actors, reducing them to unconscious reifiers, but recognizes that people utilize their pasts to challenge power structures and create better futures based on their imaginations.   [less ▲]

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See detailThe Sociology of Critique. Towards a Grammatical Approach to Social Action.
Frère, Bruno ULiege; Cervera-Marzal, Manuel ULiege

E-print/Working paper (2020)

This article is concerned with the notion of “grammar” as it has been developed at the core of Luc Boltanski and Laurent Thévenot’s pragmatic sociology. This notion is particularly useful for articulating ... [more ▼]

This article is concerned with the notion of “grammar” as it has been developed at the core of Luc Boltanski and Laurent Thévenot’s pragmatic sociology. This notion is particularly useful for articulating the normative elements that motivate and justify social action. But a specific case – that of civil disobedience – has led us to identify an epistemological difficulty that this paradigm cannot successfully resolve in its current state. To achieve this resolution, and thus to reverse our fieldwork out of the theoretical impasse into which pragmatic sociology risks driving it, we suggest that the paradigm’s concept of grammar should be modified by drawing on Ludwig Wittgenstein’s definition. [less ▲]

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See detailPrivate Equity and Employee Welfare
Lambert, Marie ULiege; Moreno Miranda, Nicolas ULiege; Phalippou, Ludovic

E-print/Working paper (2020)

Employees give lower ratings to their companies following a Private Equity Leveraged Buy-Out (PE/LBO) transaction. The analysis of ten million ratings on di erent well- being aspects and of thousands of ... [more ▼]

Employees give lower ratings to their companies following a Private Equity Leveraged Buy-Out (PE/LBO) transaction. The analysis of ten million ratings on di erent well- being aspects and of thousands of written comments, indicates that the cause is likely to stem from the di erent management style of PE-owned companies. Ratings decrease much less, or at all, for employees i) who are in management positions, ii) whose company was already PE-owned before (only changed owner), iii) whose company was acquired by a non-PE rm or went public, iv) who do not mention PE in their reviews. Ratings of company culture and of management are those decreasing the most. The words culture and management are those most frequently mentioned in negative comments. These results indicate that LBO transactions exacerbate a gap between the welfare of management and that of the rest of the employees, which we show exist across all companies. [less ▲]

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See detailIdentifier des Activités Génératrices de Revenus
Vermeulen, Cédric ULiege

E-print/Working paper (2020)

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See detailMentors’ Motives and Mentoring Functions Associated with Mentoring of Social and Commercial New Ventures
Yusubova, Ayna ULiege; Xhauflair, Virginie ULiege; Pichault, François ULiege

E-print/Working paper (2020)

Although mentoring has been advanced as an important mechanism of incubator and accelerator programs for overcoming the resource constraints of commercial and social new ventures, it has traditionally ... [more ▼]

Although mentoring has been advanced as an important mechanism of incubator and accelerator programs for overcoming the resource constraints of commercial and social new ventures, it has traditionally focused on the entrepreneur's perspective and neglected the mentor's perspective, particularly the examination of mentors' motivations and behavior. In both commercial and social entrepreneurship literature, little or no academic attention has been given as to why a person with resources and knowledge would provide assistance and support for the growth of new ventures. This study examines the motives mentors have for providing developmental support to social and commercial new ventures. Based on qualitative interviews with eighteen mentors from in total ten accelerator and incubator programs located in Belgium, we show a more comprehensive view of the diversity of mentors' motives and functions, by identifying similarities and differences between both types of new ventures mentoring processes. Implications of the findings and suggestions for future research are presented. [less ▲]

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See detailAgency costs of dry powder
Lambert, Marie ULiege; Scivoletto, Alexandre ULiege; Tykvova, Tereza

E-print/Working paper (2020)

About $2tn has been raised but have not yet been invested in private equity funds. This amount of non-invested capital or “dry powder” has raised numerous concerns regarding potential pressure to invest ... [more ▼]

About $2tn has been raised but have not yet been invested in private equity funds. This amount of non-invested capital or “dry powder” has raised numerous concerns regarding potential pressure to invest in low-quality companies for these funds with adverse consequence on fund performance. We model the total fee revenue (management fee and carried interest) collected by a private equity sponsor as a function of committed capital, net invested capital as well as the risk and return of the fund investments. We show that higher deal expected returns and higher management fees as associated with a stronger pressure on dry powder. On the other hand, an increase in the carried interest or the existence of a valuable option to delay investment to benefit from better opportunities reduce this pressure. We run an empirical analysis using 12,779 leveraged buyout deals from the US over the period 1980 – 2019 that supports our predictions from the theoretical model. Moreover, dry powder pressure is associated with investment distortions. It leads to inflated deal prices, lower returns and lower leverage. [less ▲]

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See detailProfiling novel high-conductivity 2D semiconductors
Sohier, Thibault ULiege; Gibertini, Marco; Marzari, Nicola

E-print/Working paper (2020)

When complex mechanisms are involved, pinpointing high-performance materials within large databases is a major challenge in materials discovery. We focus here on phonon-limited conductivities, and study ... [more ▼]

When complex mechanisms are involved, pinpointing high-performance materials within large databases is a major challenge in materials discovery. We focus here on phonon-limited conductivities, and study 2D semiconductors doped by field effects. Using state-of-the-art density-functional perturbation theory and Boltzmann transport equation, we discuss 11 monolayers with outstanding transport properties. These materials are selected from a computational database of exfoliable materials providing monolayers that are dynamically stable and that do not have more than 6 atoms per unit cell. We first analyze electron-phonon scattering in two well-known systems: electron-doped InSe and hole-doped phosphorene. Both are single-valley systems with weak electron-phonon interactions, but they represent two distinct pathways to fast transport: a steep and deep isotropic valley for the former and strongly anisotropic electron-phonon physics for the latter. We identify similar features in the database and compute the conductivities of the relevant monolayers. This process yields several high-conductivity materials, some of them only very recently emerging in the literature (GaSe, Bi$_2$SeTe$_2$, Bi$_2$Se$_3$, Sb$_2$SeTe$_2$), others never discussed in this context (AlLiTe$_2$, BiClTe, ClGaTe, AuI). Comparing these 11 monolayers in detail, we discuss how the strength and angular dependency of the electron-phonon scattering drives key differences in the transport performance of materials despite similar valley structure. We also discuss the high conductivity of hole-doped WSe$_2$, and how this case study shows the limitations of a selection process that would be based on band properties alone. [less ▲]

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See detailPerturbations in dynamical models of whole-brain activity dissociate between the level and stability of consciousness
Sanz Perl; Pallavicini, Carla; Pérez Ipiña, Ignacio et al

E-print/Working paper (2020)

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See detailRemote Renewable Hubs for Synthetic Fuel Production
Berger, Mathias ULiege; Richel, Aurore ULiege; Ernst, Damien ULiege

E-print/Working paper (2020)

This paper proposes a framework to study the economics of producing carbon neutral synthetic fuels in remote locations with abundant, high-quality renewable energy resources. More precisely, a mixed ... [more ▼]

This paper proposes a framework to study the economics of producing carbon neutral synthetic fuels in remote locations with abundant, high-quality renewable energy resources. More precisely, a mixed integer linear programming model enabling the analysis and end-to-end optimization of the full supply chain is introduced along with a novel energy system representation facilitating the formulation of such models. An open source software implementation is also made available. The model is leveraged to study the production of carbon neutral synthetic methane from wind and solar energy in North Africa. Results show that the cost of synthetic methane delivery to northwestern European consumers would be around 100 EUR/MWh for wind-powered systems and around 190 EUR/MWh for solar-only systems, based on conservative short-term technology cost estimates. This cost difference can be explained by the fact that key energy conversion technologies such as methanation are fairly inflexible, while wind has higher capacity factors and smoother production profiles than solar, resulting in reduced flexibility requirements and eventual cost savings. [less ▲]

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See detailNetwork tariffs and the integration of prosumers: the Case of Wallonia
Manuel de Villena Millan, Miguel ULiege; Jacqmin, Julien; Fonteneau, Raphaël ULiege et al

E-print/Working paper (2020)

In Wallonia, Belgium's southern region, the distribution component of the overall electricity retail tariff is essentially volumetric, i.e. based on the user' energy consumption (in euro/kWh). Residential ... [more ▼]

In Wallonia, Belgium's southern region, the distribution component of the overall electricity retail tariff is essentially volumetric, i.e. based on the user' energy consumption (in euro/kWh). Residential prosumers, moreover, are connected to the grid via a net-metering system. In this paper, we rely on a multi-agent tariff simulator -- developed in Manuel de Villena et al. (2019) — calibrated to this specific regional context to model the integration of prosumers into the distribution grid. This simulator enables us to highlight how the emergence of prosumers impacts the distribution network tariff, and to evaluate several tariff reforms currently under discussion. Without smart meters, short-run reforms can only change the structure of the tariff paid, either to all consumers or to prosumers only. In the long run, with smart meters, we consider both the introduction of a net-purchasing system and of a tariff with a capacity component. Our analysis highlights one key added value of smart meters: they can ensure a fair and sustainable financing of the distribution network. [less ▲]

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See detailFigures du retraducteur
Belleflamme, Clémence ULiege

E-print/Working paper (2019)

Compte-rendu de la journée d'étude "Figures du retraducteur" organisée par le CIRTI le 11 décembre 2019 à l'Université de Liège.

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See detailDe retraducción a recepción...
Belleflamme, Clémence ULiege

E-print/Working paper (2019)

Informe del coloquio “Figures du retraducteur” (Figuras del retraductor), organizado por el Centro Interdisciplinar de Investigación en Traducción e Interpretación (CIRTI), que tuvo lugar el 11 de ... [more ▼]

Informe del coloquio “Figures du retraducteur” (Figuras del retraductor), organizado por el Centro Interdisciplinar de Investigación en Traducción e Interpretación (CIRTI), que tuvo lugar el 11 de diciembre de 2019 en la Universidad de Lieja. En él se dieron cita traductores y traductólogos para reflexionar sobre la retraducción —entendida como una nueva traducción de un texto que ya se ha traducido a la misma lengua con anterioridad— y, más particularmente, sobre las distintas facetas de la tarea del retraductor. Se pasa revista a las distintas ponencias, con un enfoque en el vínculo que se puede establecer entre retraducción y recepción. [less ▲]

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See detailOn the origin of jotunite
Duchesne, Jean-Clair ULiege

E-print/Working paper (2019)

Detailed reference viewed: 46 (8 ULiège)
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Peer Reviewed
See detailEmissions de CO2 liées à la navigation aérienne à Liège Airport
Ozer, Pierre ULiege

E-print/Working paper (2019)

Detailed reference viewed: 356 (39 ULiège)
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See detailPaper Formats of the Mamluk Period: The Contribution of Mamluk Chancery Paper
Bauden, Frédéric ULiege

E-print/Working paper (2019)

Detailed reference viewed: 188 (8 ULiège)
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See detailMCMCI: A code to fully characterise an exoplanetary system
Bonfanti, Andrea ULiege; Gillon, Michaël ULiege

E-print/Working paper (2019)

Useful information can be retrieved by analysing the transit light curve of a planet-hosting star or induced radial velocity oscillations. However, inferring the physical parameters of the planet, such as ... [more ▼]

Useful information can be retrieved by analysing the transit light curve of a planet-hosting star or induced radial velocity oscillations. However, inferring the physical parameters of the planet, such as mass, size, and semi-major axis, requires preliminary knowledge of some parameters of the host star, especially its mass or radius, which are generally inferred through theoretical evolutionary models. We seek to present and test a whole algorithm devoted to the complete characterisation of an exoplanetary system thanks to the global analysis of photometric or radial velocity time series combined with observational stellar parameters derived either from spectroscopy or photometry. We developed an integrated tool called MCMCI. This tool combines the Markov chain Monte Carlo (MCMC) approach of analysing photometric or radial velocity time series with a proper interpolation within stellar evolutionary isochrones and tracks, known as isochrone placement, to be performed at each chain step, to retrieve stellar theoretical parameters such as age, mass, and radius. We tested the MCMCI on the HD 219134 multi-planetary system hosting two transiting rocky super Earths and on WASP-4, which hosts a bloated hot Jupiter. Even considering different input approaches, a final convergence was reached within the code, we found good agreement with the results already stated in the literature and we obtained more precise output parameters, especially concerning planetary masses. The MCMCI tool offers the opportunity to perform an integrated analysis of an exoplanetary system without splitting it into the preliminary stellar characterisation through theoretical models. Rather this approach favours a close interaction between light curve analysis and isochrones, so that the parameters recovered at each step of the MCMC enter as inputs for purposes of isochrone placement. [less ▲]

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See detailUn croyant grincheux. Recension de Romans et nouvelles de J.-K. Huysmans
Lansmans, Alexandre ULiege

E-print/Working paper (2019)

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See detailEen gedicht belicht. Over De moordenaars van Paul van Ostaijen
Spinoy, Erik ULiege

E-print/Working paper (2019)

This text offers a rereading of the well-known poem 'De moordenaars' by Flemish expressionist poet Paul van Ostaijen in light of the numerous references to contemporary popular culture that can be found ... [more ▼]

This text offers a rereading of the well-known poem 'De moordenaars' by Flemish expressionist poet Paul van Ostaijen in light of the numerous references to contemporary popular culture that can be found in the text. [less ▲]

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See detailColumn generation algorithms for the wafer-to-wafer integration problem
Dokka, Trivikram; Crama, Yves ULiege; Duvillié, Guillerme et al

E-print/Working paper (2019)

We consider the wafer-to-wafer integration problem that arises in the manufacturing of integrated circuits. We propose an exact, state-of-the-art branch-and-price optimization algorithm for this problem ... [more ▼]

We consider the wafer-to-wafer integration problem that arises in the manufacturing of integrated circuits. We propose an exact, state-of-the-art branch-and-price optimization algorithm for this problem, and we derive a price-and-branch heuristic from this algorithm. We have implemented these two algorithms, as well as a simple sequential heuristic algorithms, and we have conducted extensive experiments to test their performance. The results allow us to establish the range of the size of the instances that can be solved to optimality by our branch-and-price algorithm. We also identify ranges of the different instance parameters for which the two heuristics perform relatively well. [less ▲]

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Peer Reviewed
See detailImplementation of the EPPO in Belgium: Making the Best of a (Politically) Forced Marriage?
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E-print/Working paper (2019)

Detailed reference viewed: 28 (3 ULiège)