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See detailAn iterative maximum a posteriori estimation of proficiency level to detect multiple local likelihood maxima
Magis, David ULg; Raîche, Gilles

in Applied Psychological Measurement (2010), 34

In this article the authors focus on the issue of the nonuniqueness of the maximum likelihood (ML) estimator of proficiency level in item response theory (with special attention to logistic models). The ... [more ▼]

In this article the authors focus on the issue of the nonuniqueness of the maximum likelihood (ML) estimator of proficiency level in item response theory (with special attention to logistic models). The usual maximum a posteriori (MAP) method offers a good alternative within that framework; however, this article highlights some drawbacks of its use. The authors then propose an iteratively based MAP estimator (IMAP), which can be useful in detecting multiple local likelihood maxima. The efficiency of the IMAP estimator is studied and is compared to the ML and MAP methods by means of a simulation study. [less ▲]

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See detailIterative multi-task sequence labeling for predicting structural properties of proteins
Maes, Francis ULg; Becker, Julien ULg; Wehenkel, Louis ULg

in ESANN 2011 (2011)

Developing computational tools for predicting protein structural information given their amino acid sequence is of primary importance in protein science. Problems, such as the prediction of secondary ... [more ▼]

Developing computational tools for predicting protein structural information given their amino acid sequence is of primary importance in protein science. Problems, such as the prediction of secondary structures, of solvent accessibility, or of disordered regions, can be expressed as sequence labeling problems and could be solved independently by existing machine learning based sequence labeling approaches. But, since these problems are closely related, we propose to rather approach them jointly in a multi-task approach. To this end, we introduce a new generic framework for iterative multi-task sequence labeling. We apply this - conceptually simple but quite effective - strategy to jointly solve a set of five protein annotation tasks. Our empirical results with two protein datasets show that the proposed strategy significantly outperforms the single-task approaches. [less ▲]

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See detailIterative pruning PCA improves resolution of highly structured populations.
Intarapanich, Apichart; Shaw, Philip J.; Assawamakin, Anunchai et al

in BMC bioinformatics (2009), 10

BACKGROUND: Non-random patterns of genetic variation exist among individuals in a population owing to a variety of evolutionary factors. Therefore, populations are structured into genetically distinct ... [more ▼]

BACKGROUND: Non-random patterns of genetic variation exist among individuals in a population owing to a variety of evolutionary factors. Therefore, populations are structured into genetically distinct subpopulations. As genotypic datasets become ever larger, it is increasingly difficult to correctly estimate the number of subpopulations and assign individuals to them. The computationally efficient non-parametric, chiefly Principal Components Analysis (PCA)-based methods are thus becoming increasingly relied upon for population structure analysis. Current PCA-based methods can accurately detect structure; however, the accuracy in resolving subpopulations and assigning individuals to them is wanting. When subpopulations are closely related to one another, they overlap in PCA space and appear as a conglomerate. This problem is exacerbated when some subpopulations in the dataset are genetically far removed from others. We propose a novel PCA-based framework which addresses this shortcoming. RESULTS: A novel population structure analysis algorithm called iterative pruning PCA (ipPCA) was developed which assigns individuals to subpopulations and infers the total number of subpopulations present. Genotypic data from simulated and real population datasets with different degrees of structure were analyzed. For datasets with simple structures, the subpopulation assignments of individuals made by ipPCA were largely consistent with the STRUCTURE, BAPS and AWclust algorithms. On the other hand, highly structured populations containing many closely related subpopulations could be accurately resolved only by ipPCA, and not by other methods. CONCLUSION: The algorithm is computationally efficient and not constrained by the dataset complexity. This systematic subpopulation assignment approach removes the need for prior population labels, which could be advantageous when cryptic stratification is encountered in datasets containing individuals otherwise assumed to belong to a homogenous population. [less ▲]

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See detailIterative solution of high-frequency multiple-scattering problems using finite elements
Geuzaine, Christophe ULg; Vion, Alexandre ULg; V Sabariego, Ruth ULg

in Proceedings of the IVth European Conference on Computational Mechanics (ECCM 2010) (2010)

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See detailIterative solvers and stabilisation for mixed electrostatic and magnetostatic formulations
Deliège, Geoffrey ULg; Rosseel, Eveline; Vandewalle, Stefan

in Journal of Computational & Applied Mathematics (2008), 215(2), 348-356

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See detailIterative Solvers for Large Pressure Dependent Problems
Boman, Romain ULg; Colantonio, Laurent; Ponthot, Jean-Philippe ULg

in Huétink, J.; Baaijens, F. P. T. (Eds.) Proceedings of the Sixth International Conference on Numerical Methods in Industrial Forming Processes (1998, June)

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the ... [more ▼]

In this paper, we present a stress update scheme for non-deviatoric elastoviscoplastic models, which can be considered as an extension of the radial return method for classical plasticity. We use the unconditionally stable backward Euler scheme to obtain the viscoplastic solution at each increment. To solve the large sparse non symmetric iteration matrix, we use the GMRES method. This fast iterative solver, in conjunction with an appropriate preconditioner, can save a lot a memory and CPU time when 3D problem are considered. A comparison between direct and iterative solvers will be discussed on two applications of cold compaction of powders. [less ▲]

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See detailIteratively extending time horizon reinforcement learning
Ernst, Damien ULg; Geurts, Pierre ULg; Wehenkel, Louis ULg

in Machine Learning: ECML 2003, 14th European Conference on Machine Learning (2003)

Reinforcement learning aims to determine an (infinite time horizon) optimal control policy from interaction with a system. It can be solved by approximating the so-called Q-function from a sample of four ... [more ▼]

Reinforcement learning aims to determine an (infinite time horizon) optimal control policy from interaction with a system. It can be solved by approximating the so-called Q-function from a sample of four-tuples (x(t), u(t), r(t), x(t+1)) where x(t) denotes the system state at time t, ut the control action taken, rt the instantaneous reward obtained and x(t+1) the successor state of the system, and by determining the optimal control from the Q-function. Classical reinforcement learning algorithms use an ad hoc version of stochastic approximation which iterates over the Q-function approximations on a four-tuple by four-tuple basis. In this paper, we reformulate this problem as a sequence of batch mode supervised learning problems which in the limit converges to (an approximation of) the Q-function. Each step of this algorithm uses the full sample of four-tuples gathered from interaction with the system and extends by one step the horizon of the optimality criterion. An advantage of this approach is to allow the use of standard batch mode supervised learning algorithms, instead of the incremental versions used up to now. In addition to a theoretical justification the paper provides empirical tests in the context of the "Car on the Hill" control problem based on the use of ensembles of regression trees. The resulting algorithm is in principle able to handle efficiently large scale reinforcement learning problems. [less ▲]

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See detailItinéraire d’une fable : le Loup et le Chien
Pietquin, Paul ULg; Dachy, Françoise; Debrux, Thomas et al

in Etudes Classiques (Namur, Belgium) (1994), 62

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See detailL'itinéraire de Candide Wizo : un élément de datation des oeuvres anti-adoptianistes d'Alcuin? Note sur les lettres 41 et 204 de la correspondance d'Alcuin
Close, Florence ULg

in Revue d'Histoire Ecclésiastique (2008), 103(1), 5-26

In E. Dummler’s edition of Alcuin’s correspondence, L. 41 bears the date 794-795. This chronological indication has never been refuted. However, the topics dealt with in this document obviously refer to ... [more ▼]

In E. Dummler’s edition of Alcuin’s correspondence, L. 41 bears the date 794-795. This chronological indication has never been refuted. However, the topics dealt with in this document obviously refer to the second adoptianist problem (797-799), during which Candidus Wido acted as an intermediary between the Frankish court and the abbey of St. Martin de Tours. A critical reading, carefully taking into account the itinerary of Alcuin’s disciple, leads one to assign the writing of L.41 to the autumn of 798. It is, moreover, advisable to amend the critical commentary consecrated to L. 204 in the Clavis des auteurs latins du moyen age. Clavis Wizo did not present the Contra Felicem libri V11 to the court. [less ▲]

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See detailUn itinéraire du Sart Tilman
Frankignoulle, Pierre ULg; Merch, Marie-Christine ULg

E-print/Working paper (2010)

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See detailItinéraire géologique et paleontologique dans la carrière d'Ampsin (Amay, Belgique)
Barchy, Laurent; Marion, Jean-Marc ULg; Poty, Edouard ULg

Diverse speeche and writing (2008)

Close to the museum "Master of the Fire" at Ampsin (Amay, Belgium), an abandoned quarry is used to present both the local and regional geologic history, and the fauna and flora related to the site. For ... [more ▼]

Close to the museum "Master of the Fire" at Ampsin (Amay, Belgium), an abandoned quarry is used to present both the local and regional geologic history, and the fauna and flora related to the site. For all. [less ▲]

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See detailLes itinéraires cliniques
ERPICUM, Marie ULg

Scientific conference (2014, May 09)

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See detailItinéraires sylvicoles pour la production de frêne de qualité
Claessens, Hugues ULg

Book published by Faculté universitaire des sciences agronomiques de Gembloux (1997)

This paper presents ash in Wallonia (Southern Belgium) and defines its silviculture in the respect of its characteristics (light demanding species, fast juvenile growth, site fertility demanding) and its ... [more ▼]

This paper presents ash in Wallonia (Southern Belgium) and defines its silviculture in the respect of its characteristics (light demanding species, fast juvenile growth, site fertility demanding) and its wood market ( joinery wood, slicing). Two silvicultural ways are presented : “intensive silviculture” and “near-to-nature silviculture”, that are both based upon very similar guidelines (heavy and early thinnings in relation to objective-trees, short rotation, early harvesting) but differ by planting spacings and technical ways used to obtain a high quality butt log. At last, the influence of the proposed ash silviculture is evaluated from a biodiversity point of view, and some ways to preserve the floristic diversity dynamic are suggested. [less ▲]

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See detailItracoanzole in human aspergillosis revisited.
Pierard, Gérald ULg; Kharfi, M.; Salomon-Neira, M. D. et al

in Journal de Mycologie Médicale (2004), 14

Itraconazole is a broad spectrum antifungal agent of the bis-triazole class. The drug is an important option in the management of many human mycoses including various clinical presentations of ... [more ▼]

Itraconazole is a broad spectrum antifungal agent of the bis-triazole class. The drug is an important option in the management of many human mycoses including various clinical presentations of aspergillosis. Indeed, the compound exhibits potent in vitro antifungal activity against Aspergillus spp. and shows variable fungicidal effect against the different species and strains. After amphotericin B, itraconazole has been the very first agent, and the first azole antifungal to have demonstrated clinical efficacy in aspergillosis. In vivo, the antifungal efficacy of itraconazole has been demonstrated in several types of aspergillosis both in immunocompetent and immunocompromised animal models. The drug administered in its oral or intravenous formulations displays non-linear plasma pharmacokinetics. Despite best current therapies, the outcome of invasive aspergillosis may remain dismal. Fungal cells can induce enormous damage on a background of immunosuppression. Medical help comes often too slow or is too weak. It will be a long time before the ideal strategy is found for an effective prophylaxis or for the optimal therapy of disseminated and invasive aspergillosis. In spite of this limitation, itraconazole has a definite chemotherapeutic effect in experimental aspergillosis. Non-comparative clinical data of itraconazole in the treatment of suspected or proven invasive aspergillosis indicate response rates at least similar and possibly superior to those of amphotericin B. Itraconazole has clearly improved the clinical outcome in some of the less immunosuppressed patients with invasive aspergillosis. The experience with itraconazole for induction therapy of invasive aspergillosis is more limited in profoundly neutropenic patients. Itraconazole has an important role for consolidation and maintenance therapy of patients with invasive aspegillosis. Itraconazole oral cyclodextrin solution is particularly suitable in these indications. Novel combination and sequential therapies involving itraconazole with other antifungals are promising. Itraconazole is usually well tolerated, but a potential for drug interactions exists, mediated through the cytochrome P450 3A4 system. This possibility should be considered when itraconazole is used as part of a multi-drug regimen. [less ▲]

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See detailItraconazole corneofungimetry bioassay on Malassezia species.
Pierard, Gérald ULg; Arrese Estrada, Jorge ULg; Pierard, Claudine ULg

in Mycoses (2004), 47(9-10), 418-21

Yeasts of the genus Malassezia are part of the normal skin biocenosis and are involved in a series of distinct skin disorders and specific dermatomycoses in man and animals. Several species are currently ... [more ▼]

Yeasts of the genus Malassezia are part of the normal skin biocenosis and are involved in a series of distinct skin disorders and specific dermatomycoses in man and animals. Several species are currently distinguished. Their relative in vitro susceptibility to antifungals appears different according to the species and to the nature and route of administration of the drug. Corneofungimetry is an ex vivo bioassay allowing to test the fungal response on human stratum corneum following oral intake of a given antifungal by volunteers. Two series of cyanoacrylate skin surface strippings (CSSS) were harvested from the volar forearm of 30 volunteers before and after a 2-week treatment with itraconazole 200 mg daily. They were coated by olive oil and inoculated with suspensions of seven different Malassezia spp. After a 1-week culture on CSSS, the amount of viable yeasts was assessed using neutral red staining assisted by computerized image analysis. Growth of the seven species was not similar on the CSSS from untreated stratum corneum. The ranking order from the most proliferative to the least was M. restricta, M. sympodialis, M. globosa, M. furfur, M. obtusa, M. slooffiae and M. pachydermatis. Their growth was abated to almost the same level after itraconazole treatment. It is concluded that in vivo treatment with itraconazole is highly active against all Malassezia spp. colonizing the human stratum corneum. [less ▲]

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See detailThe iturin and fengycin families of lipopeptides are key factors in antagonism of Bacillus subtilis toward Podosphaera fusca
Romero, D.; de Vicente, A.; Rakotoaly, R. H. et al

in Molecular Plant-Microbe Interactions [=MPMI] (2007), 20(4), 430-440

Podosphaera fusca is the main causal agent of cucurbit powdery mildew in Spain. Four Bacillus subtilis strains, UMAF6614, UMAF6619, UMAF6639, and UMAF8561, with proven ability to suppress the disease on ... [more ▼]

Podosphaera fusca is the main causal agent of cucurbit powdery mildew in Spain. Four Bacillus subtilis strains, UMAF6614, UMAF6619, UMAF6639, and UMAF8561, with proven ability to suppress the disease on melon in detached leaf and seedling assays, were subjected to further analyses to elucidate the mode of action involved in their biocontrol performance. Cell-free supernatants showed antifungal activities very close to those previously reported for vegetative cells. Identification of three lipopeptide antibiotics, surfactin, fengycin, and iturin A or bacillomycin, in butanolic extracts from cell-free culture filtrates of these B. subtilis strains pointed out that antibiosis could be a major factor involved in their biocontrol ability. The strong inhibitory effect of purified lipopeptide fractions corresponding to bacillomycin, fengycin, and iturin A on P fusca conidia germination, as well as the in situ detection of these lipopeptides in bacterial-treated melon leaves, provided interesting evidence of their putative involvement in the antagonistic activity. Those results were definitively supported by site-directed mutagenesis analysis, targeted to suppress the biosynthesis of the different lipopeptides. Taken together, our data have allowed us to conclude that the iturin and fengycin families of lipopeptides have a major role in the antagonism of B. subtilis toward P fusca. [less ▲]

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See detailIUE and other new observations of the slow nova RR Tel
Penston, M. V.; Benvenuti, P.; Cassatella, A. et al

in Monthly Notices of the Royal Astronomical Society (1983), 202

IUE satellite UV spectra of RR Tel covering 1150-3200 A at high and low dispersion through both large and small apertures are reported, and a list of 431 lines is presented which gives measured wavelength ... [more ▼]

IUE satellite UV spectra of RR Tel covering 1150-3200 A at high and low dispersion through both large and small apertures are reported, and a list of 431 lines is presented which gives measured wavelength, intensity, and full width at half maximum. Over three-quarters of the lines are identified, and a correlation is noted between line width and ionization energy. The lines identified, which include common species ionized from one to four times, are generally resonance, forbidden or semiforbidden lines but also include the recombination lines for C, O and Ne. Many Fe II lines are present. Forbidden line wavelengths are used to define intersystem separations of energy levels in some species. The continuum energy distribution yielded by low dispersion data is not due to a simple recombination of gaseous emission processes and a hot star or accretion disk, but the very high ratio of the energy in the lines to that in the continuum of 2.4 indicates that a high temperature source must be present. [less ▲]

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See detailIUE and other new observations of the slow nova RR Tel.
Penston, M. V.; Benvenuti, P.; Cassatella, A. et al

in NASA Conference Publication (1981)

Not Available

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