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See detailOn the effects of inhomogeneities in high excitation H II regions
Manfroid, Jean ULg

in Astrophysics & Space Science (1978), 53

The hypothesis that observations of inhomogeneities in H II regions would be changed by adopting a filling factor other than one is investigated by comparing models of H II regions with filling factors of ... [more ▼]

The hypothesis that observations of inhomogeneities in H II regions would be changed by adopting a filling factor other than one is investigated by comparing models of H II regions with filling factors of one and one eighth. Attention is given to conditions when the hydrogen and helium fronts are close together, i.e. high excitation H II regions. Results obtained through use of an iterative scheme, whereby the nebula is divided into concentric shells with variable thickness, indicate that some emission lines, e.g., O II, S II, S III, N II, are substantially altered when the filling factor is smaller than one [less ▲]

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See detailOn the electrochemical polymerization of acrylonitrile and N-vinylpyrrolidone : new insight into the mechanism
Jérôme, Robert ULg; Mertens, Marc; Martinot, Lucien

in Advanced Materials (1995), 7(9), 807-809

The protection of metals against environmental attack can be achieved by coating the metal with a protective organic film. Poor adhesion of the organic film to the metal surface has, however, limited the ... [more ▼]

The protection of metals against environmental attack can be achieved by coating the metal with a protective organic film. Poor adhesion of the organic film to the metal surface has, however, limited the success of this approach. Here it is demonstrated that polyacrylonitride can be elecrografted onto a nickel surface producing a strongly adherent film. The transformation of the organic film could also open the way to new polymer-metal composites. [less ▲]

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See detailOn the embryonic form of Nematobothrium filarina
Van Beneden, Édouard ULg

in Quarterly Journal of Microscopical Science (The) (1870), 2(10), 136-143

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See detailOn the emission lines in the spectrum of BD +20° 2465
Swings, Polydore ULg; Struve, Otto

in Publications of the Astronomical Society of the Pacific [=PASP] (1941), 53

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See detailOn the Emission Spectrum of Orion
Manfroid, Jean ULg

in Astronomy and Astrophysics (1977), 57

Abstract image available at: http://cdsads.u-strasbg.fr/abs/1977A&A....57..303M

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See detailOn the Encoding of Proteins for Disordered Regions Prediction
Becker, Julien ULg; Maes, Francis; Wehenkel, Louis ULg

in PLoS ONE (2013)

Disordered regions, i.e., regions of proteins that do not adopt a stable three-dimensional structure, have been shown to play various and critical roles in many biological processes. Predicting and ... [more ▼]

Disordered regions, i.e., regions of proteins that do not adopt a stable three-dimensional structure, have been shown to play various and critical roles in many biological processes. Predicting and understanding their formation is therefore a key sub-problem of protein structure and function inference. A wide range of machine learning approaches have been developed to automatically predict disordered regions of proteins. One key factor of the success of these methods is the way in which protein information is encoded into features. Recently, we have proposed a systematic methodology to study the relevance of various feature encodings in the context of disulfide connectivity pattern prediction. In the present paper, we adapt this methodology to the problem of predicting disordered regions and assess it on proteins from the 10th CASP competition, as well as on a very large subset of proteins extracted from PDB. Our results, obtained with ensembles of extremely randomized trees, highlight a novel feature function encoding the proximity of residues according to their accessibility to the solvent, which is playing the second most important role in the prediction of disordered regions, just after evolutionary information. Furthermore, even though our approach treats each residue independently, our results are very competitive in terms of accuracy with respect to the state-of-the-art. A web-application is available at http://m24.giga.ulg.ac.be:81/x3Disorder. [less ▲]

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See detailOn the estimation of estuarine contaminant fluxes
Regnier, P.; Mouchet, Anne ULg; Ronday, François ULg et al

in ICES proceedings of the Scientific Symposium on the 1993 North Sea Quality Status Report (1996)

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See detailOn the evaluation of the through thickness residual stresses distribution of cold formed profiles
Rossi, Barbara ULg; Habraken, Anne ULg; Pascon, Frédéric ULg

in 10th International ESAFORM Conference on Material Forming : ESAFORM, Zaragoza, 18-20 April 2007 (2007)

The aim of this research is to evaluate the through thickness residual stresses distribution in the walls and in the corners of a cold-formed open section made of a material presenting a non linear ... [more ▼]

The aim of this research is to evaluate the through thickness residual stresses distribution in the walls and in the corners of a cold-formed open section made of a material presenting a non linear hardening behaviour. To get results as close as possible to the reality, the complete process is modeled, including coiling and uncoiling of the sheet before the cold bending of the corner itself. The elastic springback after flattening as well as after final shaping are also taken into account. In order to validate the model in predicting the residual stresses distribution, the presented results are confronted to experimental measurements and FE results collected from the literature. [less ▲]

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See detailOn the evolution and expression of Chlamydomonas reinhardtii nucleus-encoded transfer RNA genes
Cognat, Valerie; Deragon, Jean*-Marc; Vinogradova, Elizaveta et al

in Genetics (2008), 179(1), 113-123

In Chlamydomonas reinhardtii, 259 tRNA genes were identified and classified into 49 tRNA isoaccepting families. By constructing phylogenetic trees, we determined the evolutionary history for each tRNA ... [more ▼]

In Chlamydomonas reinhardtii, 259 tRNA genes were identified and classified into 49 tRNA isoaccepting families. By constructing phylogenetic trees, we determined the evolutionary history for each tRNA gene family. The majority of the IRNA sequences are more closely related to their plant counterparts than to animals ones. Northern experiments also permitted LIS to show that at least one member of each IRNA isoacceptor family is transcribed and correctly processed in vivo. A short stretch of T residues known to be a signal for termination of polymerase III transcription was found downstream of most IRNA genes. It allowed us to propose that the vast majority of the IRNA genes are expressed and to confirm that numerous IRNA genes separated by short spacers are indeed cotranscribed. Interestingly, in silico analyses and hybridization experiments show that the cellular IRNA abundance is correlated with the number of tRTNA genes and is adjusted to the codon usage to optimize translation efficiency. Finally, we studied the origin of SINEs, short interspersed elements related to tRNAs, whose presence in Chlamydomonas is exceptional. Phylogenetic analysis strongly suggests that tRNA(Asp)-related SINEs originate front a prokaryotic-type IRNA either horizontally transferred from a bacterium or originally present in mitochondria or chloroplasts. [less ▲]

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See detailOn the evolution of an H II region and the structure of its ionization fronts
Manfroid, Jean ULg

in Astronomy and Astrophysics (1977), 61

Abstract image available at: http://cdsads.u-strasbg.fr/abs/1977A&A....61..437M

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See detailOn the evolution of ionized gas around hot stars
Manfroid, Jean ULg

in Astrophysics & Space Science (1976), 41

The initial evolution of a uniform H II region around a star of 36 solar masses is described. The general equations of the problem are solved numerically by a finite-difference method. Forbidden-line ... [more ▼]

The initial evolution of a uniform H II region around a star of 36 solar masses is described. The general equations of the problem are solved numerically by a finite-difference method. Forbidden-line emission by ions of C, N, O, and Ne is taken into account. [less ▲]

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See detailOn the exact solutions of the Lipkin-Meshkov-Glick model
Debergh, N.; Stancu, Floarea ULg

in Journal of Physics : A Mathematical & General (2001), A34

We present the many-particle Hamiltonian model of Lipkin, Meshkov and Glick in the context of deformed polynomial algebras and show that its exact solutions can be easily and naturally obtained within ... [more ▼]

We present the many-particle Hamiltonian model of Lipkin, Meshkov and Glick in the context of deformed polynomial algebras and show that its exact solutions can be easily and naturally obtained within this formalism. The Hamiltonian matrix of each $j$ multiplet can be split into two submatrices associated to two distinct irreps of the deformed algebra. Their invariant subspaces correspond to even and odd numbers of particle-hole excitations. [less ▲]

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See detailOn the Existence of a Solution for Turbomachinery Blade Design
Demeulenaere, Alain; Léonard, Olivier ULg

in Proceedings of the 4th Belgian National Congress on Theoretical and Applied Mechanics (1997)

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See detailOn the existence of heavy tetraquarks
Stancu, Floarea ULg

in Ricerca Scientifica ed Educazione Permanente (2006), (Suppl. 126), 319-328

Previous work done in collaboration with David Brink is reviewed in the light of the recent observation of new charmonium-like resonances which can be interpreted as tetraquarks. In the framework of a ... [more ▼]

Previous work done in collaboration with David Brink is reviewed in the light of the recent observation of new charmonium-like resonances which can be interpreted as tetraquarks. In the framework of a schematic quark model the spectrum of c¯cq¯q tetraquarks is presented. [less ▲]

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See detailOn the existence of ion-acoustic double layers in two-electron temperature plasmas
Verheest, F.; Cattaert, Tom ULg; Hellberg, M. A. et al

in Physics of Plasmas (2006), 13(4), 9

Earlier Sagdeev pseudopotential treatments of ion-acoustic double layers in plasmas with two electron populations were based on a model in which both electron densities were described by isothermal ... [more ▼]

Earlier Sagdeev pseudopotential treatments of ion-acoustic double layers in plasmas with two electron populations were based on a model in which both electron densities were described by isothermal Boltzmann distributions. Using a more recent fluid-dynamical approach, with polytropic equations of state indices gamma(j), one finds analytically that no double layers can be formed for gamma(j)>= 3/2, due to total rarefaction of the cooler electrons or infinite compression of the ions. For gamma(j)< 3/2, rarefactive double layers occur, but, just below 3/2, at unrealistically small cool electron densities or large Mach numbers. As gamma(j) decreases towards 1, these constraints become less restrictive and go over smoothly to those known from Boltzmann studies. Contrary to what appears in the literature, very weak compressive double layers can also be found for Boltzmann electrons, but only for soliton conditions barely above the existence threshold; i.e., marginally super-ion-acoustic. Any slight increase in the critical Mach number destroys the possibility of having positive double layers, and, within the limits of numerical accuracy, no window could be found for gamma(j)not equal 1, where compressive double layers exist.(c) 2006 American Institute of Physics. [less ▲]

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See detailOn the existence of maximum likelihood estimates in logistic regression models
Albert, Adelin ULg; Anderson, JA.

in Biometrika (1984)

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See detailOn the exploitation of chaos to build reduced-order models
Kerschen, Gaëtan ULg; Feeny, B. F.; Golinval, Jean-Claude ULg

in Computer Methods in Applied Mechanics & Engineering (2003), 192(13-14), 1785-1795

The present study focuses on the model reduction of non-linear systems. The proper orthogonal decomposition is exploited to compute eigenmodes from time series of displacement. These eigenmodes, called ... [more ▼]

The present study focuses on the model reduction of non-linear systems. The proper orthogonal decomposition is exploited to compute eigenmodes from time series of displacement. These eigenmodes, called the proper orthogonal modes, are optimal with respect to energy content and are used to build a low-dimensional model of the non-linear system. For this purpose, the proper orthogonal modes obtained from a chaotic orbit are considered. Indeed, such an orbit is assumed to cover a portion of the phase space of higher dimension, and hence of greater measure. This higher dimensional data is further assumed to contain more information about the system dynamics than data of a lower-dimensional periodic orbit. In an example, it is shown that the modes for this particular behaviour are more representative of the system dynamics than any other set of modes extracted from a non-chaotic response. This is applied to a buckled beam with two permanent magnets and the reduced-order model is validated using both qualitative and quantitative comparisons. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailOn the exploitation of chaos to build reduced-order models
Kerschen, Gaëtan ULg; Feeny, B. F.; Golinval, Jean-Claude ULg

in International Conference on Noise and Vibration Engineering, Leuven, 2002 (2002, September)

The present study focuses on the model reduction of non-linear systems. The proper orthogonal decomposition is exploited to compute eigenmodes from time series of displacement. These eigenmodes, called ... [more ▼]

The present study focuses on the model reduction of non-linear systems. The proper orthogonal decomposition is exploited to compute eigenmodes from time series of displacement. These eigenmodes, called the proper orthogonal modes, are optimal with respect to energy content and are used to build a low-dimensional model of the non-linear system. For this purpose, the proper orthogonal modes obtained from a chaotic orbit are considered. Indeed, such an orbit is assumed to cover the phase space more uniformly. It is shown that the modes for this particular behaviour are more representative of the system dynamics than any other set of modes extracted from a non-chaotic response. This is applied to a buckled beam with two permanent magnets and the reduced-order model is validated using both qualitative and quantitative comparisons. [less ▲]

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See detailOn the Expressiveness of Real and Integer Arithmetic Automata
Boigelot, Bernard ULg; Rassart, Stéphane; Wolper, Pierre ULg

in Lecture Notes in Computer Science (1998), 1443

If read digit by digit, a n-dimensional vector of integers represented in base r can be viewed as a word over the alphabet r to the n. It has been known for some time that, under this encoding, the sets ... [more ▼]

If read digit by digit, a n-dimensional vector of integers represented in base r can be viewed as a word over the alphabet r to the n. It has been known for some time that, under this encoding, the sets of integer vectors recognizable by finite automata are exactly those definable in Presburger arithmetic if independence with respect to the base is required, and those definable in a slight extension of Presburger arithmetic if only a specific base is considered. Using the same encoding idea, but moving to infinite words, finite automata on infinite words can recognize sets of real vectors. This leads to the question of which sets of real vectors are recognizable by finite automata, which is the topic of this paper. We show that the recognizable sets of real vectors are those definable in the theory of reals and integers with addition and order, extended with a special base-dependent predicate that tests the value of a specified digit of a number. Furthermore, in the course of proving that sets of vectors defined in this theory are recognizable by finite automata, we show that linear equations and inequations have surprisingly compact representations by automata, which leads us to believe that automata accepting sets of real vectors can be of more than theoretical interest. [less ▲]

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See detailOn the extensions of Barlow-Proschan importance index and system signature to dependent lifetimes
Marichal, Jean-Luc; Mathonet, Pierre ULg

in Journal of Multivariate Analysis (2013), 115

For a coherent system the Barlow-Proschan importance index, defined when the component lifetimes are independent, measures the probability that the failure of a given component causes the system to fail ... [more ▼]

For a coherent system the Barlow-Proschan importance index, defined when the component lifetimes are independent, measures the probability that the failure of a given component causes the system to fail. Iyer (1992) extended this concept to the more general case when the component lifetimes are jointly absolutely continuous but not necessarily independent. Assuming only that the joint distribution of component lifetimes has no ties, we give an explicit expression for this extended index in terms of the discrete derivatives of the structure function and provide an interpretation of it as a probabilistic value, a concept introduced in game theory. This enables us to interpret Iyer's formula in this more general setting. We also discuss the analogy between this concept and that of system signature and show how it can be used to define a symmetry index for systems. [less ▲]

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