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See detailOn the statistical assessment of small sample classification
Noirhomme, Quentin ULg; Lesenfants, Damien ULg; Gomez, Francisco et al

Conference (2013, December)

Classifiers start to be used in medical application to infer diagnosis. Their results are assessed through either a binomial or a permutation test. Distributions built from classification of random data ... [more ▼]

Classifiers start to be used in medical application to infer diagnosis. Their results are assessed through either a binomial or a permutation test. Distributions built from classification of random data with cross-validation, did not follow the theoretical binomial distribution, showing that binomial test was not conservative enough. A permutation test is thus recommended. [less ▲]

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See detailOn the Streptomyces albus G DD carboxypeptidase mechanism of action of penicillin, vancomycin, and ristocetin
Leyh-Bouille, Mélina; Ghuysen, Jean-Marie ULg; Nieto, Manuel et al

in Biochemistry (1970), 9(15), 2971-2975

The activity of the D-alanyl-D carboxypeptidase from the penicillin-resistant Streptomyces albus G is not or very little affected by penicillins and related antibiotics. The molecular basis for the ... [more ▼]

The activity of the D-alanyl-D carboxypeptidase from the penicillin-resistant Streptomyces albus G is not or very little affected by penicillins and related antibiotics. The molecular basis for the mechanism of action of penicillin is discussed. The Streptomyces albus G D-alanyl-D carboxypeptidase appears as a model for the study of a mechanism of penicillin resistance that does not involve the enzymatic degradation of the antibiotic. Vancomycin and ristocetin are shown to inhibit the hydrolysis of sensitive peptides by the Streptomyces albus G D-alanyl-D carboxypeptidase and the mechanism of inhibition is discussed. [less ▲]

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See detailOn the strong and selective isotope effect in the UV excitation of N2 with implications toward the nebula and Martian atmosphere
Muskatel, B. H.; Remacle, Françoise ULg; Thiemens, Mark et al

in Proceedings of the National Academy of Sciences of the United States of America (2011), 108(15), 6020-6025

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See detailOn the structural analogy between D-alanyl-D-alanine terminated peptides and β-lactam antibiotics
Brasseur, Josette ULg; Dive, Georges ULg; Ghuysen, Jean-Marie ULg

in European Journal of Medicinal Chemistry (1984), 4

Structural analogy between D-alanyl-D-alanine terminated peptides (and analogues) of varying substrate activity toward D-alanyl-D-alanine-cleaving peptidases, and bicyclic fused ring azetidinone ... [more ▼]

Structural analogy between D-alanyl-D-alanine terminated peptides (and analogues) of varying substrate activity toward D-alanyl-D-alanine-cleaving peptidases, and bicyclic fused ring azetidinone structures of varying inactivating potency toward the same enzymes has been exa-mihed by comparing the relative spatial disposition of the carboxylate function at the C-terminal position and the amide function at the N-terminal position with respect to the scissile amide bond at the central position. The observed variations in the geometric parameters and the molecular electrostatic potential maps generated by these functional groups suggest multiple modes of binding. In the monobactam sulfazecin, the relative disposition of at least the scissile amide bond and the terminal sulphamate group is comparable to that of the corresponding functions in the bicyclic β-lactams. [less ▲]

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See detailOn the structure of liquid IV-VI semiconductors
Raty, Jean-Yves ULg; Gaspard, Jean-Pierre ULg; Bionducci, M. et al

in Journal of Non-Crystalline Solids (1999), 250-252

The crystalline structure of most stoichiometric IV-VI semiconductors can be viewed as a distortion of the NaCl structure; the distortion amplitude depends on the components. As a result, corrugated ... [more ▼]

The crystalline structure of most stoichiometric IV-VI semiconductors can be viewed as a distortion of the NaCl structure; the distortion amplitude depends on the components. As a result, corrugated planes of covalently bonded atoms are linked by dispersion (Van der Waals) forces. Neutron scattering experiments were performed on the liquid phases of a series of IV-VI compounds (GeS, GeSe, GeTe, SnS, SnSe and SnTe). We show that the evolution of the local order is correlated with the conductivity measurements [less ▲]

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See detailOn the structure of liquid tellurium
Bichara, C.; Raty, Jean-Yves ULg; Gaspard, Jean-Pierre ULg

in Journal of Non-Crystalline Solids (1996), 205-207

The atomic structure and the bonding mechanism in liquid tellurium are investigated by a tight binding Monte Carlo technique. The chain structure is preserved but a third covalent bond emerges with an ... [more ▼]

The atomic structure and the bonding mechanism in liquid tellurium are investigated by a tight binding Monte Carlo technique. The chain structure is preserved but a third covalent bond emerges with an intermediate interatomic separation (3.15 Aring). In addition a bond length alternation inside the chain appears in agreement with recent EXAFS experiments and the valence angles are significantly reduced. The electronic structure is studied and particular attention is paid to the modifications of lone pair interactions in the liquid structure [less ▲]

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See detailOn the structure of the nebula M 2-9
Kohoutek, L.; Surdej, Jean ULg

in Astronomy and Astrophysics (1980), 85

The structure of planetary nebula M 2-9 has been investigated on direct plates taken with the ESO 3.6 m-telescope in 1977-78. Compared with the photographs from 1952, 1971, and 1973 the main condensations ... [more ▼]

The structure of planetary nebula M 2-9 has been investigated on direct plates taken with the ESO 3.6 m-telescope in 1977-78. Compared with the photographs from 1952, 1971, and 1973 the main condensations in the wings show a remarkable shift approximately in the W-E direction which can be explained as a rotating motion about the nebular axis of symmetry (N-S axis). The angular velocity seems to increase with the distance from the core. Two faint loops extending to about 1 arcmin on each side of the core and lying on the nebular axis were discovered. The very elongated shape of the nebula indicates the presence of an anisotropic velocity field in it. [less ▲]

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See detailOn the structure-sensitivity of 2-butanol dehydrogenation over Cu/SiO2 cogelled xerogel catalysts
Lambert, Stéphanie ULg; Cellier, Caroline; Ferauche, Fabrice et al

in Catalysis Communications (2007), 8

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See detailOn the substrate specificity of bacterial DD-peptidases: evidence from two series of peptidoglycan-mimetic peptides
Anderson, J. W.; Adediran, S. A.; Charlier, Paulette ULg et al

in Biochemical Journal (2003), 373(Part 3), 949-955

The reactions between bacterial DD-peptidases and beta-lactam antibiotics have been studied for many years. Less well understood are the interactions between these enzymes and their natural substrates ... [more ▼]

The reactions between bacterial DD-peptidases and beta-lactam antibiotics have been studied for many years. Less well understood are the interactions between these enzymes and their natural substrates, presumably the peptide moieties of peptidoglycan. In general, remarkably little activity has previously been demonstrated in vitro against potential peptide substrates, although in many cases the peptides employed were non-specific and not homologous with the relevant peptidoglycan. In this paper, the specificity of a panel of DD-peptidases against elements of species-specific D-alanyl-D-alanine peptides has been assessed. In two cases, those of soluble, low-molecular-mass DD-peptidases, high activity against the relevant peptides has been demonstrated. In these cases, the high specificity is towards the free N-terminus of the peptidoglycan fragment. With a number of other enzymes, particularly high-molecular-mass DD-peptidases, little or no activity against these peptides was observed. In separate experiments, the reactivity of the enzymes against the central, largely invariant, peptide stem was examined. None of the enzymes surveyed showed high activity against this structural element although weak specificity in the expected direction towards the one structural variable (D-gammaGln versus D-gammaGlu) was observed. The current state of understanding of the activity of these enzymes in vitro is discussed. [less ▲]

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See detailOn the symmetry of the age field of a passive tracer released into a one-dimensional fluid flow by a point-source
Deleersnijder, E.; Delhez, Eric ULg; Crucifix, M. et al

in Bulletin de la Société Royale de Liège (2001), 70

Tracer is released from a point-source into an incompressible, one-dimensional fluid flow, with constant velocity and diffusivity. The age of a tracer parcel, which is defined as the time elapsed since ... [more ▼]

Tracer is released from a point-source into an incompressible, one-dimensional fluid flow, with constant velocity and diffusivity. The age of a tracer parcel, which is defined as the time elapsed since leaving the source, may be evaluated as the ratio of the age concentration to the tracer concentration. The latter are governed by two partial differential equations. Time-dependent analytical solutions are derived, which show that the age is symmetric with respect to the source. This is astonishing, since it could have been expected that the age would reflect somehow the strong asymmetry of the tracer concentration, which tends to be much larger on the downstream side of the source than on the upstream side. Some finite-difference counterparts of this problem are seen to lead to age fields which, in their steady-state limit, are also symmetric with respect to the source. This is believed to be helpful to interpret the results of numerical models of complex fluid flows in which the age is introduced as a diagnostic variable. [less ▲]

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See detailOn the TEC short-term forecast with corrections based on the average ionospheric response to background and storm-time geomagnetic conditions
Stankov, Stanimir; Warnant, René ULg; Kozarev, R.

in Geophysical Research Abstracts (2009, April), 11(Abs. No EGU2009-13283),

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See detailOn the transferability of concepts and its significance for landscape ecology.
Bogaert, Jan ULg; Barima, Y S S

in JME : Journal of Mediterranean Ecology (2008), 9

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See detailOn the understanding of the physical changes in inulin powder as a function of water activity.
Ronkart, Sébastien; Paquot, Michel ULg; Goffin, Dorothée ULg et al

Poster (2006, December)

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See detailOn the use and computation of likelihood ratios in clinical chemistry.
Albert, Adelin ULg

in Clinical Chemistry (1982), 28(5), 1113-9

The clinical relevance of likelihood ratios (L-values) for revising the physician's diagnostic probabilities has been recognized. However, the calculation of L-values, particularly in the case of ... [more ▼]

The clinical relevance of likelihood ratios (L-values) for revising the physician's diagnostic probabilities has been recognized. However, the calculation of L-values, particularly in the case of quantitative or mixed quantitative-binary test results, raises problems that have not yet been addressed. Based on a very general assumption that yields a simple functional form for the likelihood ratio, a method is developed that allows such calculations regardless of the nature and the number of clinical laboratory tests to be interpreted simultaneously. Hence the notion of predictive value (posterior probability) is extended from binary or dichotomized tests to quantitative tests, and from univariate to multivariate clinical laboratory results. The simplicity and flexibility of this approach eliminates difficulties in computation arising from the addition of new data to an existing data base. It is hoped that this method will now allow L-values to be reported along with the original test results in daily laboratory practice. [less ▲]

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See detailOn the use of a diffusion model for acoustically coupled rooms
Billon, Alexis ULg; Valeau, Vincent; Sakout, Anas et al

in Journal of the Acoustical Society of America (2006), 120(4), 2043-2054

A numerical model is proposed to predict the reverberant sound field in a system of two coupled volumes that are connected through an open aperture. The model is based on the numerical implementation of a ... [more ▼]

A numerical model is proposed to predict the reverberant sound field in a system of two coupled volumes that are connected through an open aperture. The model is based on the numerical implementation of a diffusion model that has already been applied to predict the sound-energy distribution and the sound decay in single rooms. In comparison with the statistical theory, the proposed approach permits the prediction of the sound field by taking into account the sound source location and the receiver locations as well as the transition from one room to the other at the coupling aperture. Moreover, the diffusion model results match satisfactorily the experimental data in terms of sound-pressure level and reverberation times, both in the room containing the source and in the receiving room. Simulations with a ray-based model are also carried out, leading to results similar to those of the diffusion model, but at a cost of larger computation times. [less ▲]

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See detailOn the use of a truly–mixed formulation in topology optimization with global stress–constraints
Bruggi, Matteo; Duysinx, Pierre ULg

in Proceeding of the 8th World Congress on Structural and Multidisciplinary Optimization (2009, June)

The work refers to the field of topology optimization for bidimensional structures and addresses the case in which global stress–constraints are considered to improve final designs. Most of the previous ... [more ▼]

The work refers to the field of topology optimization for bidimensional structures and addresses the case in which global stress–constraints are considered to improve final designs. Most of the previous research tackles this topic relying on classical displacement–based finite elements where stresses are recovered via post–processing techniques. The work conversely investigates the use of a truly–mixed formulation where stresses are independent variables of the problem while displacements play the secondary role of Lagrangian multiplier. The implemented discretization is based on a composite triangular element whose features may be advantageously exploited in stress–constrained topology optimization. The discretization is checkerboard–free and allows to tackle topology optimization with element–based constraints without introducing any additional filtering technique. The high accuracy in the evaluation of the average stresses is expected to improve the efficiency of the numerical procedure, especially in the case of a single global constraint that has to govern the whole domain. The adopted discretization also passes the robustness condition even in the case of incompressible materials and this allows to menage strength constraints also for rubber–like components. Basing on these ideas, numerical investigations are carried out to test preliminary applications of the truly–mixed technique coupled with topology optimization and global stress–constraints. To handle the well–known singularity problem, that affects the constraints imposition, an alternative scheme is herein adopted instead of a classical "–relaxation. An example where a homogenous stress distribution is expected is firstly tested, having the aim of pointing out the main features of the proposed procedure. Afterwards, numerical simulations address a classical L–shaped specimen, pointing out pros and cons of the approach. [less ▲]

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See detailOn the use of adhesion parameters to validate models specified using systems of affine differential equations
Jaeger, Jonathan ULg; Lambert, Philippe ULg

E-print/Working paper (2012)

A strategy for the selection of system of differential equations is proposed based on Bayesian ODE-penalized B-spline approach. It estimates the ODE parameters, approximates the solution of the ODE model ... [more ▼]

A strategy for the selection of system of differential equations is proposed based on Bayesian ODE-penalized B-spline approach. It estimates the ODE parameters, approximates the solution of the ODE model and quantifies the suitability of the proposed differential equations to model the dynamics of the observed state functions. Simulation study confirms that these ODE-adhesion parameters are able to question a system of differential equations as a descriptor of the dynamics in the state functions. This methodology is illustrated on a pharmacokinetic study. [less ▲]

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See detailOn the Use of Automata-based Techniques in Symbolic Model Checking: invited address
Legay, Axel; Wolper, Pierre ULg

in Electronic Notes in Theoretical Computer Science (2006, March 09), 150(1), 3-8

Checking infinite-state systems is frequently done by encoding infinite sets of states as regular languages. Computing such a regular representation of, say, the reachable set of states of a system ... [more ▼]

Checking infinite-state systems is frequently done by encoding infinite sets of states as regular languages. Computing such a regular representation of, say, the reachable set of states of a system requires acceleration techniques that can finitely compute the effect of an unbounded number of transitions. Among the acceleration techniques that have been proposed, one finds both specific and generic techniques. Specific techniques exploit the particular type of system being analyzed, e.g. a system manipulating queues or integers, whereas generic techniques only assume that the transition relation is represented by a finite-state transducer, which has to be iterated. In this paper, we survey two generic techniques that have been presented in [B. Boigelot and A. Legay and P. Wolper, Iterating Transducers in the Large, Proc. 15th Int. Conf. on Computer Aided Verification, Boulder, USA, Lecture Notes in Computer Science, volume 2725, year 2003, pages 223–235] and [B. Boigelot and A. Legay and P. Wolper, Omega-Regular Model Checking, Proc. 10th Int. Conf. on Tools and and Algorithms for the Construction and Analysis of Systems, Barcelona, Spain, Lecture Notes in Computer Science, volume 2988, year 2004, pages 561–575]. Those techniques build on earlier work, but exploits a number of new conceptual and algorithmic ideas, often induced with the help of experiments, that give it a broad scope, as well as good performance. [less ▲]

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