Last 7 days
Bookmark and Share    
Full Text
See detailLes théories représentationnelles : panorama introductif
Gauvry, Charlotte ULg

in Dewalque, Arnaud; Gauvry, Charlotte (Eds.) Conscience et représentation. Introduction aux théories représentationnelles de l'esprit (in press)

Introduction au volume

Detailed reference viewed: 14 (1 ULg)
Full Text
See detailHedge fund styles and macroeconomic uncertainty
Platania, Federico ULg; Lambert, Marie ULg

E-print/Working paper (in press)

This paper examines the dynamic trading strategies implemented by hedge fund managers using a Kalman filter of hedge fund betas across styles. We further investigate the risk drivers of dynamic trades ... [more ▼]

This paper examines the dynamic trading strategies implemented by hedge fund managers using a Kalman filter of hedge fund betas across styles. We further investigate the risk drivers of dynamic trades, examining which conditioning/macroeconomic variables strongly lead the time variation in fund trades. We report the significance of macroeconomic factors such as interest rates, dividend yield, GDP growth and US unemployment. We show that hedge fund managers do control the intensity of their exposures according to economic uncertainty and that differences between up- and down-market regimes can be observed. Commonly, Hedge funds tend to dislike high-dividend paying stocks. Besides, all hedge fund styles are shown to display pro-cyclical exposures towards directional equity factors as well as credit and liquidity risks. Small growth stocks, however, are revealed to be crisis investments whose allocation increases with unemployment, inflation or volatility. As volatility increases, the value of growth options embedded into growth stocks indeed increases. Growth stocks are shown to hedge market reversals and volatility. The outperformance of growth companies in recessions might also relate to their cost flexibility. Allocation to small stocks embed strong micro risks and might also constitute a hedge in economic slowdowns. This might explain why some funds with such a particular investment focus appear to be countercyclical. [less ▲]

Detailed reference viewed: 12 (1 ULg)
Full Text
See detailMarket efficiency and hedge fund trading strategies
Platania, Federico ULg; Lambert, Marie ULg; Papageorgiou, Nicolas

E-print/Working paper (in press)

Stock and option markets can at times reflect differing information. We identify three reasons for the presence of these periods of "disagreement" between the cash and derivatives markets: 1) high ... [more ▼]

Stock and option markets can at times reflect differing information. We identify three reasons for the presence of these periods of "disagreement" between the cash and derivatives markets: 1) high volatility and noise trading; 2) high level of risk aversion; 3) speculation versus hedging trades. This paper investigates the role that hedge funds, a proxy for sophisticated investors, play in the price discovery process between stock and option markets and the disagreement/agreement periods. We observe that a disparity in information between the two markets is often associated with deleveraging in directional exposures and reversal strategies. Posterior to the event, active tactical asset allocation in small and value factor investing takes place. We investigate four specific macro events which resulted in significant rebalancing by hedge fund manegers: the Thai Baht depreciation, the Dot-com bubble, the credit crunch and the Nasdaq correction. [less ▲]

Detailed reference viewed: 7 (1 ULg)
Full Text
Peer Reviewed
See detailPlanetary Sapce Weather: Scientific Aspects and Future Perspectives
Plainaki; Lilensten; Radioti, Aikaterini ULg et al

in Space Science Reviews (in press)

Detailed reference viewed: 12 (1 ULg)
Full Text
Peer Reviewed
See detailNon-homogeneous Beatty sequences leading to invariant games
Cassaigne, Julien; Duchêne, Eric; Rigo, Michel ULg

in SIAM Journal on Discrete Mathematics (in press)

We characterize pairs of complementary non-homogeneous Beatty sequences $(A_n)_{n>0}$ and $(B_n)_{n>0}$, with the restriction $A_1=1$ and $B_1\geq 3$, for which there exists an invariant take-away game ... [more ▼]

We characterize pairs of complementary non-homogeneous Beatty sequences $(A_n)_{n>0}$ and $(B_n)_{n>0}$, with the restriction $A_1=1$ and $B_1\geq 3$, for which there exists an invariant take-away game having $\{(A_n,B_n),(B_n,A_n)\mid n> 0\}\cup\{(0,0)\}$ as set of $P$-positions. Using the notion of Sturmian word arising in combinatorics on words, this characterization can be translated into a decision procedure relying only on a few algebraic tests about algebraicity or rational independence. This work partially answers to a question of Larsson et al. raised in Larsson et al. [less ▲]

Detailed reference viewed: 11 (1 ULg)
Full Text
Peer Reviewed
See detailOptimized approach to retrieve information on atmospheric carbonyl sulfide (OCS) above the Jungfraujoch station and change in its abundance since 1995
Lejeune, Bernard ULg; Mahieu, Emmanuel ULg; Vollmer, M. K. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (in press)

In this paper, we present an optimized retrieval strategy for carbonyl sulfide (OCS), using Fourier transform infrared (FTIR) solar observations made at the high-altitude Jungfraujoch station in the Swiss ... [more ▼]

In this paper, we present an optimized retrieval strategy for carbonyl sulfide (OCS), using Fourier transform infrared (FTIR) solar observations made at the high-altitude Jungfraujoch station in the Swiss Alps. More than 200 lines of the nu3 fundamental band of OCS have been systematically evaluated and we selected 4 microwindows on the basis of objective criteria minimizing the effect of interferences, mainly by solar features, carbon dioxide and water vapor absorption lines, while maximizing the information content. Implementation of this new retrieval strategy provided an extended time series of the OCS abundance spanning the 1995-2015 time period, for the study of the long-term trend and seasonal variation of OCS in the free troposphere and stratosphere. Three distinct periods characterize the evolution of the tropospheric partial columns: a first decreasing period (1995-2002), an intermediate increasing period (2002-2008), and the more recent period (2008-2015) which shows no significant trend. Our FTIR tropospheric and stratospheric time series are compared with new in situ gas chromatography mass spectrometry (GCMS) measurements performed by Empa (Laboratory for Air Pollution/Environmental Technology) at the Jungfraujoch since 2008, and with space-borne solar occultation observations by the ACE-FTS instrument on-board the SCISAT satellite, respectively, and they show good agreement. The OCS signal recorded above Jungfraujoch appears to be closely related to anthropogenic sulfur emissions. [less ▲]

Detailed reference viewed: 37 (11 ULg)
Full Text
Peer Reviewed
See detailChapitre XIII. Droit du travail
Kéfer, Fabienne ULg

in Watté, Nadine; Lecocq, Pascale (Eds.) Droit de la Belgique (in press)

Présentation succincte du droit du travail Belge

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
See detailLes troubles du sommeil chez l'enfant autiste, quel rôle pour le pédopsychiatre?
Abate Ekollo, Joëlle; Malchair, Alain ULg

in Acta Psychiatrica Belgica (in press)

Les troubles du sommeil sont fréquents chez l’enfant et leurs origines sont diverses. Ces troubles ont leur ancrage dans le développement neurophysiologique et psychoaffectif de l’enfant. Les enfants ... [more ▼]

Les troubles du sommeil sont fréquents chez l’enfant et leurs origines sont diverses. Ces troubles ont leur ancrage dans le développement neurophysiologique et psychoaffectif de l’enfant. Les enfants souffrant de troubles du spectre autistique présentent un déficit de sommeil, qui peut durer jusqu’à l’adolescence. Les troubles du spectre autistique comportent des comorbidités multiples, dont des altérations du sommeil. Ils sont importants à caractériser dans cette population, car ils peuvent avoir un impact négatif sur les comportements diurnes. Par ailleurs, ils entrainent souvent des difficultés au sein de la famille. La prise en charge doit avant tout prendre en compte le contexte environnemental afin d’améliorer les habitudes et l’hygiène du sommeil. Des questionnaires ainsi que des agendas de sommeil ont été remplis par des parents afin de démontrer l’importance d’une évaluation et d’une prise en compte des troubles du sommeil chez les enfants souffrant d’autisme en consultation pédopsychiatrique. [less ▲]

Detailed reference viewed: 147 (1 ULg)
Full Text
Peer Reviewed
See detailQuadratic reformulations of nonlinear binary optimization problems
Anthony, Martin; Boros, Endre; Crama, Yves ULg et al

in Mathematical Programming (in press)

Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these ... [more ▼]

Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the objective function is a quadratic polynomial. However, no similarly efficient methods are available for the higher degree case. Since high degree objectives are becoming increasingly important in certain application areas, such as computer vision, various techniques have been recently developed to reduce the general case to the quadratic one, at the cost of increasing the number of variables. In this paper we initiate a systematic study of these quadratization approaches. We provide tight lower and upper bounds on the number of auxiliary variables needed in the worst-case for general objective functions, for bounded-degree functions, and for a restricted class of quadratizations. Our upper bounds are constructive, thus yielding new quadratization procedures. Finally, we completely characterize all ``minimal'' quadratizations of negative monomials. [less ▲]

Detailed reference viewed: 100 (8 ULg)
Full Text
Peer Reviewed
See detailParametric Stein operators and variance bounds
Ley, Christophe; Swan, Yvik ULg

in Brazilian Journal of Probability and Statistics (in press)

Detailed reference viewed: 26 (9 ULg)
Full Text
See detailCharles Travis, La vision est-elle intentionnelle ?
Ambroise, Bruno; Gauvry, Charlotte ULg

in Dewalque, Arnaud; Gauvry, Charlotte (Eds.) Conscience et représentation. Controverses récentes en philosophie de l'esprit (in press)

Detailed reference viewed: 34 (1 ULg)
Full Text
Peer Reviewed
See detailUtiliser les potentialités phénoménotechniques de la Théorie Anthropologique du Didactique : quel prix payer ?
Schneider-Gilot, Marguerite ULg

in Travaux relatifs à la Théorie Anthropologique du Didactique (Université de Toulouse) (in press)

Detailed reference viewed: 12 (1 ULg)
Peer Reviewed
See detailHumnétriai… Un rite mis en images chez Philostrate
Pironti, Gabriella; Pirenne-Delforge, Vinciane ULg

in Calame, Claude; Ellinger, Pierre (Eds.) Du récit au rituel par la forme esthétique : pragmatique cultuelle des formes discursives et des images en Grèce ancienne (in press)

Detailed reference viewed: 27 (1 ULg)
Full Text
Peer Reviewed
See detailFrom mechanical to chemical impact of anchoring in seagrasses: the premises of anthropogenic patch generation in Posidonia oceanica meadows
Abadie, Arnaud ULg; Lejeune, Pierre; Pergent, Gérard et al

in Marine Pollution Bulletin (in press)

Intensive anchoring of leisure boats in seagrass meadows leads to mechanical damages. This anthropogenic impact creates bare mat patches that are not easily recolonized by the plant. Several tools are ... [more ▼]

Intensive anchoring of leisure boats in seagrass meadows leads to mechanical damages. This anthropogenic impact creates bare mat patches that are not easily recolonized by the plant. Several tools are used to study human impacts on the structure of seagrass meadows but they are not able to assess the indirect and long term implication of mechanical destruction. We chose to investigate the possible changes in the substrate chemistry given contrasted boat impacts. Our observations show that hydrogen sulfide concentrations remain high at 15 and 20 m depth (42.6 µM and 18.8 µM) several months after the highest period of anchoring during the summer. Moreover, our multidisciplinary study reveals that anchoring impacts of large boats at 15 and 20 m depth can potentially change the seascape structure. By taking into account both structural and chemical assessments, different managing strategies must be applied for coastal areas under anthropogenic pressures. [less ▲]

Detailed reference viewed: 68 (11 ULg)
Full Text
Peer Reviewed
See detailL’évaluation de la formation : comment la rendre utile pour les participants ? Constats et proposition de cinq stratégies d’évaluation partenariale
Faulx, Daniel ULg; Danse, Cédric ULg

in Evaluer : Journal International de Recherche en Education et Formation (in press)

Detailed reference viewed: 51 (3 ULg)
Peer Reviewed
See detailThe workers’ speeches in the daily life scenes of the XIXth-Dynasty tombs at Deir el-Medina and its vicinity
Motte, Aurore ULg

in "Deir el-Medina and the Theban Necropolis in Contact: Describing the interactions within and outside the community of workmen" (in press)

In this paper, I study the workers’ speeches (“Reden and Rufe”) in the 19th-Dynasty tombs of Deir el-Medina and its surroundings. For this period, only three tombs in Deir el-Medina (TT 212, TT 217, and ... [more ▼]

In this paper, I study the workers’ speeches (“Reden and Rufe”) in the 19th-Dynasty tombs of Deir el-Medina and its surroundings. For this period, only three tombs in Deir el-Medina (TT 212, TT 217, and TT 266) and one in the Theban necropolis (TT 16) preserve such texts. The goal of this paper is twofold. First, it aims at showing that, after falling into disuse in elite tombs, workers’ speeches appear in the tombs of craftsmen and the upper middle class, further evidence of the “democratisation” phenomenon during the 19th Dynasty. A wall relief fragment of the craftsman Meryptah from Saqqara (18th-19th Dynasty) indicates that this phenomenon was not restricted to the Theban area. The second goal of this paper is to determine what kind of language is used in 19th-Dynasty workers’ speeches, since this literary genre is sometimes thought to be written in the vernacular. I argue that it is a mimetic language, “à-la-manière-de,” more than an actual colloquial language. Regarding this question, the tombs of Ipuy (TT 217) and Amennakht (TT 266) lead to a dead-end because of their fragmentary state. The tomb of Ramose (TT 212) and the tomb of Panehsy and his wife Tarenu (TT 16), on the other hand, reveal Late Egyptian linguistic features. But, because their owners belong to a lower social class than the elite, it might suggest a reinterpretation of the rules specific to the literary genre of the workers’speeches (possible diastratic/diaphasic variation). [less ▲]

Detailed reference viewed: 11 (1 ULg)
See detailRestaurer la Lumière. Les effets luminodynamiques de la Tour cybernétique de Nicolas Schöffer à Liège
Verbeeck, Muriel ULg; D'Haenens, Manon ULg

in Lumière et patrimoine (in press)

Cette communication porte sur la nécessaire conservation préventive de la Tour Schöffer, en amont du chantier de restauration prévu pour 2015.

Detailed reference viewed: 44 (12 ULg)
Full Text
Peer Reviewed
See detailA large strain hyperelastic viscoelastic-viscoplastic-damage constitutive model based on a multi-mechanism non-local damage continuum for amorphous glassy polymers
Nguyen, Van Dung ULg; Lani, Frédéric; Pardoen, Thomas et al

in International Journal of Solids and Structures (in press)

A large strain hyperelastic phenomenological constitutive model is proposed to model the highly nonlinear, rate-dependent mechanical behavior of amorphous glassy polymers under isothermal conditions. A ... [more ▼]

A large strain hyperelastic phenomenological constitutive model is proposed to model the highly nonlinear, rate-dependent mechanical behavior of amorphous glassy polymers under isothermal conditions. A corotational formulation is used through the total Lagrange formalism. At small strains, the viscoelastic behavior is captured using the generalized Maxwell model. At large strains beyond a viscoelastic limit characterized by a pressure-sensitive yield function, which is extended from the Drucker-Prager one, a viscoplastic region follows. The viscoplastic flow is governed by a non-associated Perzyna-type flow rule incorporating this pressure-sensitive yield function and a quadratic flow potential in order to capture the volumetric deformation during the plastic process. The stress reduction phenomena arising from the post-peak plateau and during the failure stage are considered in the context of a continuum damage mechanics approach. The post-peak softening is modeled by an internal scalar, so-called softening variable, whose evolution is governed by a saturation law. When the softening variable is saturated, the rehardening stage is naturally obtained since the isotropic and kinematic hardening phenomena are still developing. Beyond the onset of failure characterized by a pressure-sensitive failure criterion, the damage process leading to the total failure is controlled by a second internal scalar, so-called failure variable. The final failure occurs when the failure variable reaches its critical value. To avoid the loss of solution uniqueness when dealing with the continuum damage mechanics formalism, a non-local implicit gradient formulation is used for both the softening and failure variables, leading to a multi-mechanism non-local damage continuum. The pressure sensitivity considered in both the yield and failure conditions allows for the distinction under compression and tension loading conditions. It is shown through experimental comparisons that the proposed constitutive model has the ability to capture the complex behavior of amorphous glassy polymers, including their failure. [less ▲]

Detailed reference viewed: 44 (24 ULg)