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See detailExamining the Effect of Earnings Management on Bid-Ask Spread and Market Liquidity
Sougné, Danielle ULg; Ajina, Aymen ULg

E-print/Working paper (2014)

The main purpose of this paper is to argue the extent that earnings management lowers liquidity. It should increase information asymmetry and impair trading liquidity. Using a sample of French firms from ... [more ▼]

The main purpose of this paper is to argue the extent that earnings management lowers liquidity. It should increase information asymmetry and impair trading liquidity. Using a sample of French firms from 2008 to 2011, we find that firms that manage earnings have wider bid-ask spreads. Our results are robust for both of two well established measures of market liquidity. Therefore the empirical results indicate that firms that exhibit greater earnings management are associated with lower market liquidity. These findings are in line with adverse selection and shed light on the role corporate governance devices can play in the consideration of shareholder interest’s protection, which leads to improved stock market liquidity levels. [less ▲]

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See detailProposition de révisions de l'arrêté n° 018/MEF/SG/DGF/DFCOM du 31 janvier 2013 fixant les procédures d'attribution et de gestion des forêts communautaires
Moumbogou, Carl; Boldrini, Sylvie; Morin, Amélie et al

E-print/Working paper (2014)

Detailed reference viewed: 19 (3 ULg)
See detailFrench Texts in Medieval Cambridge
Morato, Nicola ULg

E-print/Working paper (2014)

Detailed reference viewed: 7 (1 ULg)
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See detailBott type periodicity for the higher octonions
Kreusch, Marie ULg

E-print/Working paper (2014)

We study the series of complex nonassociative algebras $\bbO_n$ and real nonassociative algebras $\bbO_{p,q}$ introduced in~\cite{MGO2011}. These algebras generalize the classical algebras of octonions ... [more ▼]

We study the series of complex nonassociative algebras $\bbO_n$ and real nonassociative algebras $\bbO_{p,q}$ introduced in~\cite{MGO2011}. These algebras generalize the classical algebras of octonions and Clifford algebras. The algebras $\bbO_{n}$ and $\bbO_{p,q}$ with $p+q=n$ have a natural $\Z_2^n$-grading, and they are characterized by cubic forms over the field $\Z_2$. We establish a periodicity for the algebras~$\bbO_{n}$ and $\bbO_{p,q}$ similar to that of the Clifford algebras $\mathrm{Cl}_{n}$ and~$\mathrm{Cl}_{p,q}$. [less ▲]

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See detailHubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
Knutson, Heather A.; Dragomir, Diana; Kreidberg, Laura et al

E-print/Working paper (2014)

Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets ... [more ▼]

Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's scanning mode to measure the wavelength-dependent transit depth in thirty individual bandpasses. Our averaged differential transmission spectrum has a median 1 sigma uncertainty of 19 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 17 sigma level. They are a good match for flat models corresponding to either a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of a mbar or higher. [less ▲]

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See detailLettre d'information trimestrielle n° 13 du projet DACEFI 2
Meunier, Quentin; Moumbogou, Carl; Boldrini, Sylvie et al

E-print/Working paper (2014)

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See detailWASP-20b and WASP-28b: a hot Saturn and a hot Jupiter in near-aligned orbits around solar-type stars
Anderson, D. R.; Collier Cameron, A.; Hellier, C. et al

E-print/Working paper (2014)

We report the discovery of the planets WASP-20b and WASP-28b along with measurements of their sky-projected orbital obliquities. WASP-20b is an inflated, Saturn-mass planet (0.31 $M_{\rm Jup}$; 1.46 $R ... [more ▼]

We report the discovery of the planets WASP-20b and WASP-28b along with measurements of their sky-projected orbital obliquities. WASP-20b is an inflated, Saturn-mass planet (0.31 $M_{\rm Jup}$; 1.46 $R_{\rm Jup}$) in a 4.9-day, near-aligned ($\lambda = 8.1 \pm 3.6^\circ$) orbit around CD-24 102 ($V$=10.7; F9). WASP-28b is an inflated, Jupiter-mass planet (0.91 $M_{\rm Jup}$; 1.21 $R_{\rm Jup}$) in a 3.4-day, near-aligned ($\lambda = 8 \pm 18^\circ$) orbit around a $V$=12, F8 star. As intermediate-mass planets in short orbits around aged, cool stars ($7^{+2}_{-1}$ Gyr for WASP-20 and $5^{+3}_{-2}$ Gyr for WASP-28; both with $T_{\rm eff}$ < 6250 K), their orbital alignment is consistent with the hypothesis that close-in giant planets are scattered into eccentric orbits with random alignments, which are then circularised and aligned with their stars' spins via tidal dissipation. [less ▲]

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See detailEn el laboratorio de la ciencia ficción hispánica: una entrevista
Ceballos Viro, Alvaro ULg

E-print/Working paper (2014)

Detailed reference viewed: 20 (3 ULg)
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See detailLettre d'Information N° 12 projet Dacefi
Meunier, Quentin; Mezui Mba, C.; Boldrini, Sylvie et al

E-print/Working paper (2014)

Detailed reference viewed: 24 (1 ULg)
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See detailExperimental Study and Statistical Modeling of an Injection Scroll Compressor Operating with R407c.
Quoilin, Sylvain ULg

E-print/Working paper (2014)

This working paper describes an experimental study carried out on a refrigeration scroll compressor with and without vapour injection. The test rig designed for that purposed allows evaluating the ... [more ▼]

This working paper describes an experimental study carried out on a refrigeration scroll compressor with and without vapour injection. The test rig designed for that purposed allows evaluating the performance over a wide range of operating conditions, by varying the supply pressure, the injection pressure, the exhaust pressure, the supply superheating and the injection superheating. 97 Steady-state points are measured, with a maximum isentropic efficiency of 64.1% and a maximum consumed electrical power of 13.1 kW. A critical analysis of the experimental results is then carried out to evaluate the quality of the data using a machine learning method. This method based on Gaussian Processes regression, is used to build a statistical operating map of the compressor as a function of the different inputs. This statistical operating map can then be compared to the experimental data points to evaluate their accuracy. [less ▲]

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See detailZola in Sciascia. Una nota su Candido
Curreri, Luciano ULg

E-print/Working paper (2014)

Detailed reference viewed: 95 (3 ULg)
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See detailVisibilité des femmes d'affaires dans la presse d'affaires francophone belge
Cornet, Annie ULg; dubois, valérie

E-print/Working paper (2014)

Detailed reference viewed: 15 (0 ULg)
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See detailVon Themara nach Belgrad und zurück: Burkhard Spinnens Roman "Nevena"
Dupont, Bruno ULg

E-print/Working paper (2014)

Detailed reference viewed: 13 (2 ULg)
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See detailCerebral functional connectivity periodically (de)synchronizes with anatomical constraints
Liegeois, Raphaël ULg; Sepulchre, Rodolphe ULg; LAUREYS, Steven ULg

E-print/Working paper (2014)

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber ... [more ▼]

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber tractography. Instead of a static analysis based on the correlation between SC and the FC averaged over the entire fMRI time series, we propose a dynamic analysis, based on the time evolution of the correlation between SC and a suitably windowed FC. Assessing the statistical significance of the time series against random phase permutations, our data show a pronounced peak of significance for time window widths around 20-30 TR (40-60 sec). Using the appropriate window width, we show that FC patterns oscillate between phases of high modularity, primarily shaped by anatomy, and phases of low modularity, primarily shaped by inter-network connectivity. Building upon recent results in dynamic FC, this emphasizes the potential role of SC as a transitory architecture between different highly connected resting state FC patterns. Finally, we show that networks implied in consciousness-related processes, such as the default mode network (DMN), contribute more to these brain-level fluctuations compared to other networks, such as the motor or somatosensory networks. This suggests that the fluctuations between FC and SC are capturing mind-wandering effects. [less ▲]

Detailed reference viewed: 16 (4 ULg)
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See detailNonparametric regression with cross-sectional data: an alternative to conditional product-limit estimators
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

Suppose the random vector (X,Y) satisfies the nonparametric regression model Y=m(X)+varepsilon, where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions and the error varepsilon ... [more ▼]

Suppose the random vector (X,Y) satisfies the nonparametric regression model Y=m(X)+varepsilon, where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions and the error varepsilon has zero mean and finite variance conditionally on X=x. The pair (X,Y) is obtained by cross-sectional sampling involving left-truncated and right-censored responses. The considered model is completely nonparametric but the conditional truncation distribution is assumed to be known. The novelty of this work is twofold: first, it extends the results on cross-sectional data to the conditional case and second, it generalizes the length bias results in the conditional case to right censoring and to any truncation distribution. New estimators for m(.) and sigma²(.) are constructed and relevant tools are used to quickly provide the main asymptotic properties for this kind of estimators. Extensive simulations are carried out and show that the new estimators outperform classical nonparametric estimators for left-truncated and right-censored data (when the truncation model is known). Finally, a data set on the mortality of diabetics is analyzed. [less ▲]

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See detailInflated discrete Beta regression models for Likert and discrete rating scale outcomes
Taverne, Cédric; Lambert, Philippe ULg

E-print/Working paper (2014)

Discrete ordinal responses such as Likert scales are regularly proposed in questionnaires and used as dependent variable in modeling. The response distribution for such scales is always discrete, with ... [more ▼]

Discrete ordinal responses such as Likert scales are regularly proposed in questionnaires and used as dependent variable in modeling. The response distribution for such scales is always discrete, with bounded support and often skewed. In addition, one particular level of the scale is frequently inflated as it cumulates respondents who invari- ably choose that particular level (typically the middle or one extreme of the scale) without hesitation with those who chose that alternative but might have selected a neighboring one. The inflated discrete beta regression (IDBR) model addresses those four critical characteristics that have never been taken into account simultaneously by existing models. The mean and the dispersion of rates are jointly regressed on covariates using an underlying beta distribution. The probability that choosers of the inflated level invariably make that choice is also regressed on covariates. Simulation studies used to evaluate the statistical properties of the IDBR model suggest that it produces more precise predictions than competing models. The ability to jointly model the location and dispersion of (the distribution of) an ordinal response, as well as to characterize the profile of subject selecting an ”inflated” alternative are the most relevant features of the IDBR model. It is illustrated with the analysis of the political positioning on a ”left-right” scale of the Belgian respondents in the 2012 European Social Survey. [less ▲]

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See detailIntentionality as Disposition
Boccaccini, Federico ULg

E-print/Working paper (2014)

Detailed reference viewed: 14 (2 ULg)
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See detailEstimation of the error distribution in nonparametric regression with cross-sectional data
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

In this article, we study the nonparametric regression model Y=m(X)+varepsilon where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions, and the error varepsilon has zero mean ... [more ▼]

In this article, we study the nonparametric regression model Y=m(X)+varepsilon where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions, and the error varepsilon has zero mean and finite variance conditionally on X=x. The problem consists in estimating the cumulative distribution function of the error in a nonparametric way when the couple (X,Y) is obtained by cross-sectional sampling while the positive response Y can be right-censored. We propose a new estimator for the error distribution function based on the estimators of m(.) and sigma²(.) described in Heuchenne and Laurent 2014. A bootstrap procedure is developed to solve the critical problem of the smoothing parameter choice. We assess the performance of the proposed estimator through simulations. Finally, a data set based on the mortality of diabetics is analyzed. (Heuchenne Cédric and Laurent Géraldine, Nonparametric regression with cross-sectional data: an alternative to conditional product-limit estimators, 2014) [less ▲]

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See detailLa psychologie morale de Brentano
Boccaccini, Federico ULg

E-print/Working paper (2014)

Detailed reference viewed: 14 (0 ULg)
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See detailWhat roles for energy cooperatives in the diffusion of distributed generation technologies?
Bauwens, Thomas ULg

E-print/Working paper (2014)

Whereas a centralized model of electricity infrastructure is still dominant today, many scholars advocate the diffusion of distributed generation technologies, implying geographically dispersed and small ... [more ▼]

Whereas a centralized model of electricity infrastructure is still dominant today, many scholars advocate the diffusion of distributed generation technologies, implying geographically dispersed and small-scale generation units located close to consumers. However, there exist various barriers of different natures to a large-scale penetration of these technologies. In this article, we focus on the behavioral and psychological ones, emphasizing the roles that citizens have to play in this issue. More specifically, we explore a specific way of involving citizens in such diffusion, namely energy cooperatives. After presenting the driving forces of the emergence of cooperative firms in the energy sector, we examine the assets of the cooperative ownership structure from the perspectives of behavioral economics and social psychology. Our analysis enables us to build a model of how cooperatives may enhance consumer engagement in the diffusion of distributed generation technologies. This provides a basic theoretical framework for future empirical research. [less ▲]

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See detailIntegrating the weight of history into the alignment framework: the case of distributed generation technologies
Bauwens, Thomas ULg

E-print/Working paper (2014)

Whereas a centralized energy supply system is still dominant today, the energy sector is currently witnessing the development of small-scale and more geographically dispersed generation units, so-called ... [more ▼]

Whereas a centralized energy supply system is still dominant today, the energy sector is currently witnessing the development of small-scale and more geographically dispersed generation units, so-called distributed generation technologies. So-called "alignment framework" proposes a very useful approach to look at this evolution. Yet, we argue in this paper that this framework does not fully take into account the inertia associated with past technological and institutional choices that may hinder future changes. Relying on the concept of socio-technical lock-in, we illustrate this point with the case of the diffusion of distributed generation technologies. Based on this analysis, we propose an adaptation of the alignment framework to integrate these elements. [less ▲]

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See detailThe role of segmentation and investor recognition trough the lens of cross-listing activity
Mouchette, Xavier ULg; Carrieri, Francesca; Muller, Aline ULg

E-print/Working paper (2014)

Detailed reference viewed: 34 (11 ULg)
Peer Reviewed
See detailHedwig Margrethe Elisabeth von Ranzau
Henneau, Marie-Elisabeth ULg

E-print/Working paper (2014)

Detailed reference viewed: 25 (0 ULg)
See detailPhysician induced demand for C-sections: does the convenience incentive matter?
Lefevre, Mélanie ULg

E-print/Working paper (2014)

This paper investigates whether physicians induce demand for C-sections in the days preceding leisure periods. I reject that doctors are meaningfully increasing the number of primary cesareans to ... [more ▼]

This paper investigates whether physicians induce demand for C-sections in the days preceding leisure periods. I reject that doctors are meaningfully increasing the number of primary cesareans to accommodate their own preferences for control of deliveries around holiday Mondays. Using a sample of more than 1,300,000 deliveries, I can estimate that the induced demand due to convenience is close to zero. A small signi cant e ect is found for women having had a previous C-section. While I replicate previous results of lower C-section rates on leisure periods, I show that they are due to the way doctors schedule planned cesareans rather than to an induced demand for reason of physicians' convenience. If induced demand occurs, the decision takes place in the labor room and is not planned in advance. [less ▲]

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See detailSize Matters, Book Value does not! The Fama-French empirical CAPM revisited
Lambert, Marie ULg; Hübner, Georges ULg

E-print/Working paper (2014)

The Fama and French (F&F) factors do not reliably estimate the size and book-to-market effects. Our paper shows that the former has been underestimated in the US market while the latter overestimated. We ... [more ▼]

The Fama and French (F&F) factors do not reliably estimate the size and book-to-market effects. Our paper shows that the former has been underestimated in the US market while the latter overestimated. We do so by replacing F&F’s independent rankings by the conditional ones introduced by Lambert and Hübner (2013), over which we improve the sorting procedure. This new specification better reflects the properties of the individual risk premiums. We emphasize a much stronger size effect than conventionally documented. As a major related outcome, the alternative risk factors deliver less specification errors when used to price passive investment indices [less ▲]

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See detailAn assessment of cross-listed firms’ diversification potential
Mouchette, Xavier ULg; Muller, Aline ULg

E-print/Working paper (2014)

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See detailA Supervised Machine Learning Approach to Variable Branching in Branch-And-Bound
Marcos Alvarez, Alejandro ULg; Louveaux, Quentin ULg; Wehenkel, Louis ULg

E-print/Working paper (2014)

We present in this paper a new approach that uses supervised machine learning techniques to improve the performances of optimization algorithms in the context of mixed-integer programming (MIP). We focus ... [more ▼]

We present in this paper a new approach that uses supervised machine learning techniques to improve the performances of optimization algorithms in the context of mixed-integer programming (MIP). We focus on the branch-and-bound (B&B) algorithm, which is the traditional algorithm used to solve MIP problems. In B&B, variable branching is the key component that most conditions the efficiency of the optimization. Good branching strategies exist but are computationally expensive and usually hinder the optimization rather than improving it. Our approach consists in imitating the decisions taken by a supposedly good branching strategy, strong branching in our case, with a fast approximation. To this end, we develop a set of features describing the state of the ongoing optimization and show how supervised machine learning can be used to approximate the desired branching strategy. The approximated function is created by a supervised machine learning algorithm from a set of observed branching decisions taken by the target strategy. The experiments performed on randomly generated and standard benchmark (MIPLIB) problems show promising results. [less ▲]

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See detailParametric conditional variance estimation in location-scale models with censored data
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

Suppose the random vector (X,Y) satisfies the regression model Y=m(X)+sigma(X)*varepsilon, where m(.)=E(Y|.), sigma²(.)=Var(Y|.) belongs to some parametric class {sigma _theta(.): theta in Theta} and ... [more ▼]

Suppose the random vector (X,Y) satisfies the regression model Y=m(X)+sigma(X)*varepsilon, where m(.)=E(Y|.), sigma²(.)=Var(Y|.) belongs to some parametric class {sigma _theta(.): theta in Theta} and varepsilon is independent of X. The response Y is subject to random right censoring and the covariate X is completely observed. A new estimation procedure is proposed for sigma_theta(.) when m(.) is unknown. It is based on nonlinear least squares estimation extended to conditional variance in the censored case. The consistency and asymptotic normality of the proposed estimator are established. The estimator is studied via simulations and an important application is devoted to fatigue life data analysis. [less ▲]

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See detailDes royaumes aux nations ? L’Europe barbare aux Ve-VIe siècles
Fialon, Sabine ULg

E-print/Working paper (2014)

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See detailL’intervention militaire internationale au Kosovo
Pierre, Alexia ULg

E-print/Working paper (2014)

This paper aims first to explore the international armed intervention in Kosovo, formalized through the Allied Force Operation headed by the Nato. A second part is dedicated to the legal aspects of this ... [more ▼]

This paper aims first to explore the international armed intervention in Kosovo, formalized through the Allied Force Operation headed by the Nato. A second part is dedicated to the legal aspects of this intervention regarding the international norms. [less ▲]

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Peer Reviewed
See detailAcoustic velocity measurements for evaluating bed stability parameters
Duma, Diana ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

E-print/Working paper (2014)

Assessing the stability of riverbeds is a major issue in many aspects of hydraulic and river engineering. Although the Shields diagram remains the most widely accepted approach, it faces a number of ... [more ▼]

Assessing the stability of riverbeds is a major issue in many aspects of hydraulic and river engineering. Although the Shields diagram remains the most widely accepted approach, it faces a number of shortcomings. In particular, its ability to reflect the influence of turbulence on sediment motion becomes questionable when it is applied under strongly non-uniform flow conditions, which are of high practical relevance in hydraulic engineering. Therefore, new approaches were proposed, which relate the degree of damage of gravel beds to so-called bed stability parameters depending explicitly on the local intensity of flow turbulence. However, these new bed stability parameters are much more demanding in term of detailed description of the flow field and, in all studies so far, they were estimated based only on Laser Doppler Velocimetry or Particle Image Velocimetry. Here, we investigate for the first time the suitability of acoustic velocity measurement techniques to evaluate these bed stability parameters. The experiments focus on smooth-to-rough transitions and a quasi-uniform configuration is used as a reference. Flow velocities were obtained using two complementary devices: an Ultrasonic Velocity Profiler and a 3D Acoustic Doppler Velocimeter. The new experimental results show that relatively robust estimates of the new stability parameters can be obtained from the 3D acoustic measurements. [less ▲]

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See detailCerebral functional connectivity periodically (de)synchronizes with anatomical constraints
Liegeois, Raphaël ULg

E-print/Working paper (2014)

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber ... [more ▼]

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber tractography. Instead of a static analysis based on the correlation between SC and the FC averaged over the entire fMRI time series, we propose a dynamic analysis, based on the time evolution of the correlation between SC and a suitably windowed FC. Assessing the statistical significance of the time series against random phase permutations, our data show a pronounced peak of significance for time window widths around 20-30 TR (40-60 sec). Using the appropriate window width, we show that FC patterns oscillate between phases of high modularity, primarily shaped by anatomy, and phases of low modularity, primarily shaped by inter-network connectivity. Building upon recent results in dynamic FC, this emphasizes the potential role of SC as a transitory architecture between different highly connected resting state FC patterns. Finally, we show that networks implied in consciousness-related processes, such as the default mode network (DMN), contribute more to these brain-level fluctuations compared to other networks, such as the motor or somatosensory networks. This suggests that the fluctuations between FC and SC are capturing mind-wandering effects. [less ▲]

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See detailActive network management for electrical distribution systems: problem formulation and benchmark
Gemine, Quentin ULg; Ernst, Damien ULg; Cornélusse, Bertrand ULg

E-print/Working paper (2014)

In order to operate an electrical distribution network in a secure and cost-efficient way, it is necessary, due to the rise of renewable energy-based distributed generation, to develop Active Network ... [more ▼]

In order to operate an electrical distribution network in a secure and cost-efficient way, it is necessary, due to the rise of renewable energy-based distributed generation, to develop Active Network Management (ANM) strategies. These strategies rely on short-term policies that control the power injected by generators and/or taken off by loads in order to avoid congestion or voltage problems. While simple ANM strategies would curtail the production of generators, more advanced ones would move the consumption of loads to relevant time periods to maximize the potential of renewable energy sources. However, such advanced strategies imply solving large-scale optimal sequential decision-making problems under uncertainty, something that is understandably complicated. In order to promote the development of computational techniques for active network management, we detail a generic procedure for formulating ANM decision problems as Markov decision processes. We also specify it to a 75-bus distribution network. The resulting test instance is available at http://www.montefiore.ulg.ac.be/~anm/ . It can be used as a test bed for comparing existing computational techniques, as well as for developing new ones. A solution technique that consists in an approximate multistage program is also illustrated on the test instance. [less ▲]

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Peer Reviewed
See detailStatistically Bundled Shewhart Control Charts for Monitoring Delivery Chains Systems
Foster, Earnest; Faraz, Alireza ULg; Heuchenne, Cédric ULg

E-print/Working paper (2014)

Continuous monitoring of Delivery Time variables by means of control charts in a delivery chain is a very recent application of Statistical Process Control (SPC) to the service sector. The aim of the ... [more ▼]

Continuous monitoring of Delivery Time variables by means of control charts in a delivery chain is a very recent application of Statistical Process Control (SPC) to the service sector. The aim of the proposed method is to provide supply chain decision makers with an easy to be managed tool monitoring the current functioning state of the delivery chain. The implementation of SPC control charts makes it possible to limit over-corrections to false alarm conditions and to maintain at an acceptable level the safety stock, with a consequent reduction of the overall management costs of the delivery chain. An illustrative example shows the proposed control chart implementation in a real delivery chain. [less ▲]

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See detailVorosweep: a fast generalized crystal growing Voronoi diagram generation algorithm
Mouton, Thibaud; Béchet, Eric ULg

E-print/Working paper (2014)

We propose a new algorithm for generating quickly approximate generalized Voronoi diagrams of point sites associated to arbitrary convex distance metric in the Euclidian plane. This algorithm produces ... [more ▼]

We propose a new algorithm for generating quickly approximate generalized Voronoi diagrams of point sites associated to arbitrary convex distance metric in the Euclidian plane. This algorithm produces connected cells by emulating the growth of crystals starting at the point sites, in order to reduce the complexity of the diagram. The main practical contribution is the Vorosweep package which is the reference implementation of the algorithm. Experimental results and benchmarks are given to demonstrate the versatility of this approach. [less ▲]

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Peer Reviewed
See detailL'expérience internationale étudiante: un atout pour une carrière internationale?
Robert, Jocelyne ULg; Carrabs, Vincenzo

E-print/Working paper (2014)

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See detailLarge deviation spectra based on wavelet leaders
Bastin, Françoise ULg; Esser, Céline ULg; Jaffard, Stéphane ULg

E-print/Working paper (2014)

We introduce a new multifractal formalism, based on distributions of wavelet leaders, which allows to detect non-concave and decreasing multifractal spectra, and we investigate the properties of the ... [more ▼]

We introduce a new multifractal formalism, based on distributions of wavelet leaders, which allows to detect non-concave and decreasing multifractal spectra, and we investigate the properties of the associated function spaces. [less ▲]

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See detailA multifractal formalism based on the Sν spaces: From theory to practice
Esser, Céline ULg; Kleyntssens, Thomas ULg; Nicolay, Samuel ULg

E-print/Working paper (2014)

We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non ... [more ▼]

We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non-concave spectra, where other multifractal formalisms only lead to the concave hull of the spectra. [less ▲]

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See detailLes portfolio : vers une évaluation plus intégrée et plus cohérente avec la notion complexe de compétence
Poumay, Marianne ULg; Maillart, Christelle ULg

E-print/Working paper (2014)

Ce chapitre prend résolument le parti du témoignage et construit sur l’expérience des auteures. Il choisit quelques référents théoriques, qu’il illustre ensuite par deux expériences ciblées, l’une chez ... [more ▼]

Ce chapitre prend résolument le parti du témoignage et construit sur l’expérience des auteures. Il choisit quelques référents théoriques, qu’il illustre ensuite par deux expériences ciblées, l’une chez les étudiants en logopédie/orthophonie et l’autre chez les étudiants en pédagogie de l’enseignement supérieur, deux programmes de l’Université de Liège. Il conclut sur quelques réflexions et perspectives. [less ▲]

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See detailLes fondations en Belgique
Mernier, Amélie ULg; Xhauflair, Virginie ULg

E-print/Working paper (2014)

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See detailDe stichtingen in Belgie
Mernier, Amélie ULg; Xhauflair, Virginie ULg

E-print/Working paper (2014)

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See detailThree WASP-South transiting exoplanets: WASP-74b, WASP-83b \amp WASP-89b
Hellier, C.; Anderson, D. R.; Collier Cameron, A. et al

E-print/Working paper (2014)

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See detailSix newly-discovered hot Jupiters transiting F/G stars: WASP-87b, WASP-108b, WASP-109b, WASP-110b, WASP-111b \amp WASP-112b
Anderson, D. R.; Brown, D. J. A.; Collier Cameron, A. et al

E-print/Working paper (2014)

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See detailQue pouvons-nous attendre du sommet européen de décembre 2013 ?
Dumoulin, André ULg

E-print/Working paper (2013)

Hypothèses autour des décisions attendues du sommet UE spécial défense prévu en décembre 2013 avec les différentes écoles de pensée

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See detailQuadratization of symmetric pseudo-Boolean functions
Anthony, Martin; Boros, Endre; Crama, Yves ULg et al

E-print/Working paper (2013)

A pseudo-Boolean function is a real-valued function $f(x)=f(x_1,x_2,\ldots,x_n)$ of $n$ binary variables; that is, a mapping from $\{0,1\}^n$ to ${\bbr}$. For a pseudo-Boolean function $f(x)$ on $\{0,1 ... [more ▼]

A pseudo-Boolean function is a real-valued function $f(x)=f(x_1,x_2,\ldots,x_n)$ of $n$ binary variables; that is, a mapping from $\{0,1\}^n$ to ${\bbr}$. For a pseudo-Boolean function $f(x)$ on $\{0,1\}^n$, we say that $g(x,y)$ is a quadratization of $f$ if $g(x,y)$ is a quadratic polynomial depending on $x$ and on $m$ auxiliary binary variables $y_1,y_2,\ldots,y_m$ such that $f(x)= \min \{ g(x,y) : y \in \{0,1\}^m \} $ for all $x \in \{0,1\}^n$. By means of quadratizations, minimization of $f$ is reduced to minimization (over its extended set of variables) of the quadratic function $g(x,y)$. This is of some practical interest because minimization of quadratic functions has been thoroughly studied for the last few decades, and much progress has been made in solving such problems exactly or heuristically. A related paper initiated a systematic study of the minimum number of auxiliary $y$-variables required in a quadratization of an arbitrary function $f$ (a natural question, since the complexity of minimizing the quadratic function $g(x,y)$ depends, among other factors, on the number of binary variables). In this paper, we determine more precisely the number of auxiliary variables required by quadratizations of \emph{symmetric} pseudo-Boolean functions $f(x)$, those functions whose value depends only on the Hamming weight of the input $x$ (the number of variables equal to 1). [less ▲]

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See detailEstimation and approximation in multidimensional dynamics
Frasso, Gianluca ULg; Jaeger, Jonathan ULg; Lambert, Philippe ULg

E-print/Working paper (2013)

Differential equations (DEs) are commonly used to describe dynamic systems evolving in one (ordinary differential equations or ODEs) or in more than one dimensions (partial differential equations or PDEs ... [more ▼]

Differential equations (DEs) are commonly used to describe dynamic systems evolving in one (ordinary differential equations or ODEs) or in more than one dimensions (partial differential equations or PDEs). In real data applications the parameters involved in the DE models are usually unknown and need to be estimated from the available measurements together with the state function. In this paper, we present frequentist and Bayesian approaches for the joint estimation of the parameters and of the state functions involved in PDEs. We also propose two strategies to include differential (initial and/or boundary) conditions in the estimation procedure. We evaluate the performances of the proposed strategy on simulated and real data applications. [less ▲]

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See detailWat kunnen wij verwachten van de Europese top van december 2013 ?
Dumoulin, André ULg

E-print/Working paper (2013)

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See detailWhat can we expect from the December 2013 European Summit ?
Dumoulin, André ULg

E-print/Working paper (2013)

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See detailSpline approximation to conditional Archimedean copula
Lambert, Philippe ULg

E-print/Working paper (2013)

We propose a flexible copula model to describe changes with a covari- ate in the dependence structure of (conditionally exchangeable) random variables. The starting point is a spline approximation to the ... [more ▼]

We propose a flexible copula model to describe changes with a covari- ate in the dependence structure of (conditionally exchangeable) random variables. The starting point is a spline approximation to the generator of an Archimedean copula. Changes in the dependence structure with a covariate x are modelled by flexible regression of the spline coefficients on x. The performances and properties of the spline estimate of the reference generator and the abilities of these conditional models to approximate conditional copulas are studied through simulations. Inference is made using Bayesian arguments with posterior distributions explored using im- portance sampling or adaptive MCMC algorithms. The modelling strategy is illustrated with two examples. [less ▲]

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See detailAccord Canada-UE: la nouvelle approche d'exemption culturelle et ses implications
Vlassis, Antonios ULg

E-print/Working paper (2013)

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See detailUne épaule sur laquelle s'appuyer
Forthomme, Bénédicte ULg

E-print/Working paper (2013)

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See detailCos: A Typical Example of Hellenistic Religion?
Paul, Stéphanie ULg

E-print/Working paper (2013)

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See detailLe samedi 15 août 778
Rolland, Jean-Noël ULg

E-print/Working paper (2013)

Battle of Roncevaux Pass and his historical context. Roncesvalles is famous in History and legend for the defeat of Charlemagne and the death of Roland in 778, during the battle of Roncevaux Pass, when ... [more ▼]

Battle of Roncevaux Pass and his historical context. Roncesvalles is famous in History and legend for the defeat of Charlemagne and the death of Roland in 778, during the battle of Roncevaux Pass, when Charlemagne's rear guard was destroyed by Basque tribes. [less ▲]

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See detailDaniel Kehlmann: Ich und Kaminski
Hackbarth, Sabine ULg; Dupont, Bruno ULg

E-print/Working paper (2013)

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See detailThree irradiated and bloated hot Jupiters: WASP-76b, WASP-82b & WASP-90b
West, R. G.; Almenara, J.-M.; Anderson, D. R. et al

E-print/Working paper (2013)

We report three new transiting hot-Jupiter planets discovered from the WASP surveys combined with radial velocities from OHP/SOPHIE and Euler/CORALIE and photometry from Euler and TRAPPIST. All three ... [more ▼]

We report three new transiting hot-Jupiter planets discovered from the WASP surveys combined with radial velocities from OHP/SOPHIE and Euler/CORALIE and photometry from Euler and TRAPPIST. All three planets are inflated, with radii 1.7-1.8 Rjup. All orbit hot stars, F5-F7, and all three stars have evolved, post-MS radii (1.7-2.2 Rsun). Thus the three planets, with orbits of 1.8-3.9 d, are among the most irradiated planets known. This reinforces the correlation between inflated planets and stellar irradiation. [less ▲]

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See detailModèle discret de type 'Timing of Events'
Lejeune, Bernard ULg

E-print/Working paper (2013)

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See detailSearching for Terrestrial Planets Orbiting in the Habitable Zone of Ultra-Cool Stars and Brown Dwarfs
Demory, Brice-Olivier; Seager, Sara; Lissauer, Jack et al

E-print/Working paper (2013)

We propose to use Kepler in 2-wheel mode to conduct a detailed search for Earth-sized planets orbiting ultra-cool stars and brown dwarfs (spectral types from M7 to L3). This population of objects presents ... [more ▼]

We propose to use Kepler in 2-wheel mode to conduct a detailed search for Earth-sized planets orbiting ultra-cool stars and brown dwarfs (spectral types from M7 to L3). This population of objects presents several advantages for exoplanet surveys. First, ultra-cool stars and brown dwarfs are small and thus result in favorable planet-to-star area ratios. Second, because of their low effective temperature, the inner edge of their habitable zone is extremely close (2 to 3 days only). Third, our targets are bright at infrared wavelengths, which will enable detailed follow-up studies. Our program therefore represents a unique opportunity to find a transiting Earth-size exoplanet for which atmospheric features (including biosignatures) could be detected with near-to-come facilities such as JWST. Such exoplanet has not been discovered yet. Kepler in 2-wheel mode provides the required stability and photometric precision to make this survey successful. Our initial target sample includes 60 ultra-cool stars and brown dwarfs from which we expect to detect at least one transiting planet. We propose to monitor each source for 4 days, resulting in a total program duration of ~240 days. [less ▲]

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See detailRevealed preference tests of collectively rational consumption behavior: formulations and algorithms
Talla Nobibon, Fabrice; Cherchye, Laurens; Crama, Yves ULg et al

E-print/Working paper (2013)

This paper focuses on revealed preference tests of the collective model of household consumption. We start by showing that the decision problems corresponding to testing collective rationality are {\sc np ... [more ▼]

This paper focuses on revealed preference tests of the collective model of household consumption. We start by showing that the decision problems corresponding to testing collective rationality are {\sc np}-complete. This makes the application of these tests problematic for (increasingly available) large(r) scale data sets. We then present two approaches to overcome this negative result. First, we introduce exact algorithms based on mixed-integer programming ({\sc mip}) formulations of the collective rationality tests, which can be usefully applied to medium sized data sets. Next, we propose simulated annealing heuristics, which allow for efficient testing of the collective model in the case of large data sets. We illustrate our methods by a number of computational experiments based on Dutch labor supply data. [less ▲]

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See detailLettre d'information trimestrielle du projet DACEFI 2 - Retour sur l'attribution des premières forêts communautaires du Gabon
Meunier, Quentin; Moumbogou, Carl; Morin, Amélie et al

E-print/Working paper (2013)

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See detailPhysician Induced Demand for C-Sections: Does the Convenience Incentive Matter?
Lefevre, Mélanie ULg

E-print/Working paper (2013)

This paper investigates whether physicians induce demand for C-sections in the days preceding leisure periods. I reject that doctors are meaningfully increasing the number of cesareans to accommodate ... [more ▼]

This paper investigates whether physicians induce demand for C-sections in the days preceding leisure periods. I reject that doctors are meaningfully increasing the number of cesareans to accommodate their own preferences for control of deliveries around holiday Mondays. Using a sample of more than 1,300,000 deliveries, I can precisely estimate that the induced demand due to convenience is close to zero. While I replicate previous results of lower C-section rates on leisure periods, I show that they are due to the way doctors schedule planned cesareans rather than to an induced demand for reason of physicians' convenience. [less ▲]

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See detailInvestir Ou Mourir ? Il Faut Choisir…
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

Investir : c’est croire en l’avenir. C’est renoncer en partie au présent pour donner vie au futur. C’est tourner le dos aux « Bouffeurs d’espoir » et à l’illusoire confort du statu quo. Enfin, et surtout ... [more ▼]

Investir : c’est croire en l’avenir. C’est renoncer en partie au présent pour donner vie au futur. C’est tourner le dos aux « Bouffeurs d’espoir » et à l’illusoire confort du statu quo. Enfin, et surtout, c’est oser «Oser » ! La distance séparant le discours public de la performance économique avérée suffit à démontrer l’incompréhension des mécanismes de création de richesse de ceux qui sont censés en avoir la maîtrise et les mettre en œuvre. Il est peu de domaines où les illusions, et autres idées fausses, ont un succès tel qu’elles amènent l’observateur aguerri à s’interroger sur le profit que d’aucuns pourraient en tirer. L’objet de ce document est de partager le fruit d’une réflexion menée sur le thème de l’Investissement, forme proéminente et condition première de l’activité économique, au moment où certains s’interrogent sur son encadrement et cherchent à en limiter la liberté. [less ▲]

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See detailLes Draps de lit
Demoulin, Laurent ULg

E-print/Working paper (2013)

Les Draps de lit est une pièce de théâtre inédite de Jean-Philippe Toussaint, antérieure à La Salle de bain. Elle est ici éditée avec un apparat critique: variantes et notes critiques.

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See detailChicago Gospel Festival June 2013
Sacré, Robert ULg

E-print/Working paper (2013)

Compte-rendu avec photos

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See detailLa gouvernance des coopératives en situation de conflit et de post-conflit
Niyungeko, Thadée ULg; Huybrechts, Benjamin ULg

E-print/Working paper (2013)

If governance has become, for many years, as a matter of paramount importance in traditional companies (Berle & Means, 1932), microfinance institutions have also not escaped this need (Rock et al. 1998 ... [more ▼]

If governance has become, for many years, as a matter of paramount importance in traditional companies (Berle & Means, 1932), microfinance institutions have also not escaped this need (Rock et al. 1998), there are about thirty years. Considered essential to address issues related to economic and social development (Wélé, 2009), governance is also emerging as an undeniable factor for to strengthen the financial performance and to increase awareness in microfinance institutions (Rock et al., 1998; Labie, 2001 Helms, 2006). Several authors have contributed to the understanding of corporate governance by using a variety of theoretical approaches (Jensen & Meckling (1976), Fama and Jensen (1983a) for Shareholders approach, Freeman (1984), Donaldson & Preston (1995) Hung (1998) for the stakeholder approach, Meyer and Rowan (1977), Mertens (2010), Muth & Donaldson (1998), Berle & Means (1932); Labie (2005a) for alternative approaches). Applied individually in cooperatives and organizations, these approaches have proved rather one-dimensional and illuminate one aspect of the Boards of Directors (Cornforth, 2004). Hence the need for an approach that integrates the insights of these perspectives has been felt. Thus, a perspective in terms of paradox (Cornforth, 2004) helped to highlight the dilemmas, paradoxes and tensions that boards of directors are facing. Several researchers have used this paradox perspective in different organizations (Demb & Neubauer, 1992 Wood, 1996; Sundaramurthy & Lewis, 2003), but it also did not take long. Criticized for focusing only on the board, this perspective paradox is also alleged to ignore the role of contextual factors. However, as argued by DiMaggio & Powell (1983), Meyer and Rowan (1977), environmental factors play an undeniable role in the way organizations make isomorphic. Rijpens & Adam (2011) also point out that the internal and external factors to the organization involved in the debate on the governance model adopted. Hudon and Seibel (2007) argue that conflicts and disasters seriously affect the socio-economic institutions, public governance, networks and social relations of citizens, including those related to the exchange or transfer of financial resources. This article examines the influence of armed conflict on the cooperatives’ governance. It is built around three fundamental questions. (1) What overlay the systems of cooperatives governance? (2) What is the theoretical model of governance adapted to cooperatives working in conflict situations? (3) How an armed conflict does it influence the cooperatives governance? To answer these questions, this article assumes, first, the confrontation of existing theoretical approaches in the literature on corporate governance in general and cooperatives in particular. It then develops a model of governance adapted to the conflict. Finally, that model will be tested after data collect from a qualitative field study based on the triangulation of information resources and interviews with key players in organizations under study in a country where microfinance institutions have evolved conflict situations. The results will be presented in another article. [less ▲]

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See detailDo consumers pay more for what they value more? The case of local milk-based dairy products in Senegal
Lefevre, Mélanie ULg

E-print/Working paper (2013)

Senegalese consumers seem to prefer local fresh milk-based dairy products rather than the ones produced with imported powder. However, market prices of both products do not appear to be different. This ... [more ▼]

Senegalese consumers seem to prefer local fresh milk-based dairy products rather than the ones produced with imported powder. However, market prices of both products do not appear to be different. This paper addresses this puzzle. First, I confirm the preference for local products. Using choice-based-conjoint data, I evaluate that Senegalese consumers are willing to pay a positive and significant premium for these products. Then, I identify the determinants of prices, based on a unique dataset of milk products characteristics. Evidence suggests that consumers' misinformation regarding the product composition prevents them from allocating a higher price to local milk-based products. [less ▲]

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See detailBlues on The Fox , Blues Festival Aurora June 2013
Sacré, Robert ULg

E-print/Working paper (2013)

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See detailAn overview of the foundations' sector in Belgium
Mernier, Amélie ULg

E-print/Working paper (2013)

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See detailInnovations in IT Organization Design: Is the Public Sector Really a Special Case?
Markus, M. Lynne; Jacobson, Dax D.; Lisein, Olivier ULg et al

E-print/Working paper (2013)

IT organization design, consisting of IT governance (decision rights) and IT organization structure, is believed to affect organizational performance. This paper describes the IT organization design ... [more ▼]

IT organization design, consisting of IT governance (decision rights) and IT organization structure, is believed to affect organizational performance. This paper describes the IT organization design choices of the 50 U.S. state governments. Significant movement toward greater centralization was observed (particularly for IT services). States appeared to have adopted IT organization design innovations previously pioneered in the private sector, contrary to conventional wisdom founded on well-documented differences between the two sectors. Two commonly used explanations of IT organization design choices were examined for their ability to account for the unexpected findings — contingency and institutional theories. Both explanations were partially successful in explaining the results, but further theoretical development is needed to integrate those theories and more empirical research is needed to advance the field’s knowledge of IT organization design. [less ▲]

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See detailQuelques considérations sur la présomption de titularité des droits d'auteur dans la loi du 30 juin 1994 relative au droit d'auteur et aux droits voisins.
Kouembeu Tagne, Jean Jacques ULg

E-print/Working paper (2013)

Nous avons choisi d'axer notre raisonnement sur la problématique de la présomption de titularité des droits d’auteur dans la loi du 30 juin 1994 relative au droit d'auteur et aux droits voisins. Que ... [more ▼]

Nous avons choisi d'axer notre raisonnement sur la problématique de la présomption de titularité des droits d’auteur dans la loi du 30 juin 1994 relative au droit d'auteur et aux droits voisins. Que signifie-t-elle ? Quelles sont les conditions nécessaires à sa mise en œuvre ? Comment les démonter ? [less ▲]

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See detailThe HARPS search for southern extra-solar planets. XXXIV. A planetary system around the nearby M dwarf GJ163, with a super-Earth possibly in the habitable zone
Bonfils, X.; Lo Curto, G.; Correia, A. C. M. et al

E-print/Working paper (2013)

The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting ... [more ▼]

The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting GJ163 (HIP19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ163 over a period of 8 years. We searched the RV time series for coherent signals and found 5 distinct periodic variabilities. We investigated the stellar activity and casted doubts on the planetary interpretation for 2 signals. Before more data can be acquired we concluded that at least 3 planets are orbiting GJ163. They have orbital periods of P_b=8.632+-0.002, P_c=25.63+-0.03 and P_d=604+-8 days and minimum masses msini = 10.6+-0.6, 6.8+-0.9, and 29+-3 M_Earth, respectively. We hold our interpretations for the 2 additional signals with periods P_(e)=19.4 and P_(f)=108 days. The inner pair presents an orbital period ratio of 2.97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. GJ163c, in particular, is a super-Earth with an equilibrium temperature of T_eq = (302+-10) (1-A)^(1/4) K and may lie in the so called habitable zone for albedo values (A=0.34-0.89) moderately higher than that of Earth (A_Earth=0.2-0.3). [less ▲]

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See detailUne leçon de Poker Menteur
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

L’évolution de la situation de la société Exide Technologies (Nasdaq : XIDE) offre à l’investisseur potentiel une superbe leçon de « Poker Menteur ». Dans la mesure où les marchés ne produisent pas ... [more ▼]

L’évolution de la situation de la société Exide Technologies (Nasdaq : XIDE) offre à l’investisseur potentiel une superbe leçon de « Poker Menteur ». Dans la mesure où les marchés ne produisent pas souvent ce type de « Quasi-expérience », j’ai décidé d’en reconstruire l’histoire et d’en suivre le développement. En partageant ces observations, mon objectif est de transformer une décision d’investissement réalisée dans des « Conditions Extrêmes » en une expérience susceptible d’être conceptualisée et transmise à d’autres. De plus, la solution à cette situation exceptionnelle pourrait constituer un cas d’école dans le domaine des partenariats public-privé à susciter dans le cadre de la transition énergétique d’un Etat ou d’une région. Temps réel oblige…, trois révisions de ce document sont prévues, en fin de semaine, dans le mois à venir. [less ▲]

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See detailGabriel package: software for education and research
Olive, Gilles ULg

E-print/Working paper (2013)

Today, personal computers are part of our life either at home, at work or at school. Even if the computer power increases, the software are more and more complicated, asking more and more time for ... [more ▼]

Today, personal computers are part of our life either at home, at work or at school. Even if the computer power increases, the software are more and more complicated, asking more and more time for learning it or for obtaining a result. It becomes important to have in labs as well as at school small fast software using empirical equations. We report here about the use but more particularly the algorithms, the equations and the data sets of three software belonging to the Gabriel package. The first one, Gabriel Nathalie II, is a calculator with many functionality's. It is possible to calculate the pKa or to simulate the chemical shift in 31P NMR of amino-phosphonate. Moreover it is also able to dertimine the thermodynamics data of bisphosphonate binding to human bones. The second one, Gabriel Calculatrice Savon, is used to calculate the amount of alkali needed for making a soap according to the amount and the nature of fat but also the viscosity of some oils at a desired temperature. And at least Gabriel Data Analysis is a software devoted to data analysis. Today, software for research can be used for educational and educational software can be useful for research. [less ▲]

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See detailApproximation Algorithms for Multi-Dimensional Vector Assignment Problems
Dokka, Trivikram; Crama, Yves ULg; Spieksma, Frits C.R.

E-print/Working paper (2013)

We consider a special class of axial multi-dimensional assignment problems called multi-dimensional vector assignment (MVA) problems. An instance of the MVA problem is defined by $m$ disjoint sets, each ... [more ▼]

We consider a special class of axial multi-dimensional assignment problems called multi-dimensional vector assignment (MVA) problems. An instance of the MVA problem is defined by $m$ disjoint sets, each of which contains the same number $n$ of $p$-dimensional vectors with nonnegative integral components, and a cost function defined on vectors. The cost of an $m$-tuple of vectors is defined as the cost of their component-wise maximum. The problem is now to partition the $m$ sets of vectors into $n$ $m$-tuples so that no two vectors from the same set are in the same $m$-tuple and so that the total cost of the $m$-tuples is minimized. The main motivation comes from a yield optimization problem in semi-conductor manufacturing. We consider two classes of polynomial-time heuristics for MVA, namely, hub heuristics and sequential heuristics, and we study their approximation ratio. In particular, we show that when the cost function is monotone and subadditive, hub heuristics, as well as sequential heuristics, have finite approximation ratio for every fixed $m$. Moreover, we establish better approximation ratios for certain variants of hub heuristics and sequential heuristics when the cost function is monotone and submodular, or when it is additive. We provide examples to illustrate the tightness of our analysis. Furthermore, we show that the MVA problem is APX-hard even for the case $m=3$ and for binary input vectors. Finally, we show that the problem can be solved in polynomial time in the special case of binary vectors with fixed dimension $p$. [less ▲]

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See detailLe pape François se trompe-t-il ?
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

La crise de panique généralisée à laquelle nous avons assisté depuis 2007/2008 – pour reprendre l’analyse qu’en fait l’homme le mieux informé du monde, Ben Bernanke –, n’est rien d’autre que le double ... [more ▼]

La crise de panique généralisée à laquelle nous avons assisté depuis 2007/2008 – pour reprendre l’analyse qu’en fait l’homme le mieux informé du monde, Ben Bernanke –, n’est rien d’autre que le double d’une crise de confiance trouvant son origine dans l’accélération de l’information et la difficulté du pouvoir politique à en percevoir et à en accepter les conséquences. [less ▲]

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See detailNegociations commerciales : le retour permanent de l’exception culturelle
Vlassis, Antonios ULg

E-print/Working paper (2013)

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See detailLes FAQs du tableau de bord - Mythes et réalités du tableau de bord à l'ère de la mondialisation
Van Caillie, Didier ULg

E-print/Working paper (2013)

Ce document synthétise en 8 questions clés l'état de notre expérience en matière de conception et d'implémentation d'un tableau de bord dans une organisation, privée ou publique, grande ou petite. Les 8 ... [more ▼]

Ce document synthétise en 8 questions clés l'état de notre expérience en matière de conception et d'implémentation d'un tableau de bord dans une organisation, privée ou publique, grande ou petite. Les 8 questions abordées sont : 1. Qu’est-ce qu’un tableau de bord ? 2. Quelle est son utilité pour une organisation à l’ère de la mondialisation ? 3. Quels sont les prérequis à l’utilisation d’un tableau de bord ? 4. Faut-il un tableau de bord unique ou plusieurs tableaux de bord ? 5. Quels indicateurs intégrer au tableau de bord ? 6. Quelle forme donner à un tableau de bord ? 7. Quelle forme donner aux indicateurs retenus ? 8. Comment piloter le projet "Conception & implémentation d’un tableau de bord" ? [less ▲]

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See detailAlexander Kluge et Heiner Müller, ou quand l'interview devient un art
Dupont, Bruno ULg

E-print/Working paper (2013)

Les interviews entre Alexander Kluge et Heiner Müller dans les années nonante sont devenues légendaires, à tel point qu'on les considère comme une partie de l'œuvre du dramaturge de la RDA. Elles sont le ... [more ▼]

Les interviews entre Alexander Kluge et Heiner Müller dans les années nonante sont devenues légendaires, à tel point qu'on les considère comme une partie de l'œuvre du dramaturge de la RDA. Elles sont le témoin de l'irruption de Kluge dans l'audiovisuel allemand, ainsi que de la pensée et la parole de Müller. La publication de leur recueil en français permet de revivre ces dialogues, fruit de la rencontre de deux artistes hors-normes. Diffusés il y a vingt ans, ces échanges sont toujours actuels. Cet article explique pourquoi. [less ▲]

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See detailLa fin d'une époque...?
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

Il est des moments exceptionnels dans la vie qui rappellent les lignes de fracture de l’histoire. C’est, peut-être, ce que notre monde moderne vit aujourd’hui. Dans ce document, et avant que nous ne ... [more ▼]

Il est des moments exceptionnels dans la vie qui rappellent les lignes de fracture de l’histoire. C’est, peut-être, ce que notre monde moderne vit aujourd’hui. Dans ce document, et avant que nous ne vivions ce qui pourrait être un printemps, ou un automne « chaud », il m’a paru utile de mettre un peu d’ordre dans mes observations sur « L’air du temps. » Pas d’autre ambition pour ce texte, donc, que de chercher à comprendre les événements passés, et de prendre date sur les nuages qui s’amoncellent ! [less ▲]

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See detailRetour au travail après une longue absence...
Mairiaux, Philippe ULg

E-print/Working paper (2013)

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See detailSOUTHERN BLUES NIGHT , Heerlen (NL) 17e ed. , 15 mars 2013
Sacré, Robert ULg

E-print/Working paper (2013)

C.R. de la 17e Southern Blues Night , le 15 mars 2013 à Heerlen ( Nl) + photos ; Khalif Wailin' Walter , Mud Morganfield, Heritage Blues Orchestra, James Harman, Enrico Crivellaro, Gene Taylor, ....

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See detailLes nouvelles dispositions légales pour la récupération de bois abandonnés
Meunier, Quentin; Moumbogou, Carl; Vermeulen, Cédric ULg

E-print/Working paper (2013)

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See detailLa superposition des permis forestiers, des permis miniers et des futures forêts communautaires
Morin, Amélie; Moumbogou, Carl; Meunier, Quentin et al

E-print/Working paper (2013)

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