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See detailComparison of cross-field pitting in fresh, dried and charcoalified softwoods
Gerards, Thomas ULg; Damblon, Freddy ULg; Wauthoz, B. et al

in Iawa Journal (2007), 28(1), 49-60

Cross-field pitting is one of the most reliable characters for softwood identifi cation. During charcoalification, a range of severe qualitative and quantitative modifications may occur in cross-field ... [more ▼]

Cross-field pitting is one of the most reliable characters for softwood identifi cation. During charcoalification, a range of severe qualitative and quantitative modifications may occur in cross-field pitting. As most fossil or archaeological wood remains are preserved as charcoal (fusain), the question arises whether these modifications hamper the accurate identification of some taxa. This work is a systematic biometric study of a wide range of gymnosperm cross-field pitting after experimental charcoalification. We focused on the window-like, piceoid, taxodioid, cupressoid, araucarioid and podocarpoid cross-field pitting types. Our main results are the following: 1) Cross-field pits of wood specimens dried out before charcoalification are hidden by a thin closing wall; in this case, it is often impossible to discriminate between the various types of cross-field pitting. 2) Piceoid cross-field pitting becomes taxodioid-like after charcoalification. 3) Biometric study of charred softwood cross-field pitting dimensions shows that the ratios between height and width of pit aperture and border allow us to distinguish and characterise four types of pitting (window-like, piceoid, taxodioid, cupressoid + araucarioid + podocarpoid [= CAP]). The discrimination within the CAP type requires further investigation. [less ▲]

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See detailComparison of Data Transfer Methods between Meshes in the Frame of the Arbitrary Lagrangian Eulerien Formalism
Bussetta, Philippe ULg; Boman, Romain ULg; Ponthot, Jean-Philippe ULg

in Proceedings of "Fifth International Conference on Advanced COmputationalMethods in ENgineering" (2011, November)

In nonlinear solid Mechanics, the Arbitrary Lagrangian Eulerian (ALE) formalism is a common way to avoid mesh distortion when very large deformations occur in the modelled process. Usually, the ALE ... [more ▼]

In nonlinear solid Mechanics, the Arbitrary Lagrangian Eulerian (ALE) formalism is a common way to avoid mesh distortion when very large deformations occur in the modelled process. Usually, the ALE resolution procedure is based on an “operator split”, the second part of which is a Data Transfer between two meshes sharing the same topology (same number of nodes and same number of element neighbours for each of them). Thanks to this interesting property, classical ALE transfer algorithms can bemuchmore optimised in terms of CPU time than the ones that are used in the frame of a complete remeshing. However, the resulting CPU-efficient transfer schemes suffer from two main drawbacks. The first one is a spurious crosswind diffusion coming from the corner fluxes that have been neglected. The second issue is the number of explicit transfer steps which may become very large when the element size decreases. In this paper, these classical ALE Data Transfer methods are compared to more general algorithms which do not make any assumption on the topology of both meshes. [less ▲]

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See detailComparison of Data Transfer Methods between two different meshes
Bussetta, Philippe ULg; Ponthot, Jean-Philippe ULg

in Proceedings of "IV International Conference on Computational Methods for Coupled Problems in Science and Engineering" (2011, June)

Many problems solved with the finite element method require more than one mesh (i.e. one specific mesh for each Physic or a remeshing is needed). The Data Transfer Method used, has a great importance in ... [more ▼]

Many problems solved with the finite element method require more than one mesh (i.e. one specific mesh for each Physic or a remeshing is needed). The Data Transfer Method used, has a great importance in the capacity to solve the problem and in the reliability of the solution. In general, the data is composed of two kinds of fields (defined thanks to the nodal values or at the integration points). In this paper, the more used Data Transfer Method is compared with the Data Transfer Methods based on a Weak Form (using Mortar Element or Finite Volume). [less ▲]

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See detailComparison of deposition images obtained by use of an ultrafine 99m-technetium-labeled carbon dry aerosol with ventilation images obtained by use of 81m-krypton gas for evaluation of pulmonary dysfunction in calves.
Votion, Dominique ULg; Coghe, J. D.; Lekeux, Pierre ULg

in American Journal of Veterinary Research (2001), 62(12), 1881-6

OBJECTIVE: To characterize the accuracy of an ultrafine 99m-technetium-labeled carbon dry aerosol for use in assessment of regional ventilation in calves with pulmonary dysfunction. ANIMALS: 7 Belgian ... [more ▼]

OBJECTIVE: To characterize the accuracy of an ultrafine 99m-technetium-labeled carbon dry aerosol for use in assessment of regional ventilation in calves with pulmonary dysfunction. ANIMALS: 7 Belgian White and Blue calves. PROCEDURE: The ultrafine aerosol was assessed by comparing deposition (D) images with ventilation (V) images obtained by use of 81 m-krypton (81mKr) gas via D-to-V ratio (D:V) image analysis in calves during spontaneous breathing (SB) and during experimentally induced pulmonary dysfunction (ePD). RESULTS: Mismatching index (LrTot) calculated on the D:V images revealed a good match (LrTot, 0.96 +/- 0.01) between D and V distribution patterns in calves during SB. Calculation of the ultrafine aerosol penetration index relative to 81mKr (PIRel) revealed preferential distribution of the ultrafine aerosol in lung parenchyma (PIRel, 1.13 +/- 0.11). In ePD, heterogeneity in the D:V distribution was observed (LrTot, 0.78 +/- 0.10) as a result of ultrafine aerosol particles impaction in airways as indicated by PIRel (0.66 +/- 0.16) and a proportion of pixels more radioactive in D images, compared with V images, that was located in the central part of the lung (475 +/- 77% in ePD vs 32.8 +/- 5.7% in SB). However, this central deposition did not prevent visual examination of the entire ventilated lung. CONCLUSIONS AND CLINICAL RELEVANCE: The ultrafine aerosol appears suitable for use in examination of ventilated parts of lungs of cattle, even those with impaired pulmonary function. However, airway impaction of ultrafine aerosol particles impedes the quantification of regional ventilation in cattle with abnormal lung function. [less ▲]

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See detailComparison of Destructive Methods to Appraise the Mechanical Integrity of a Concrete Surface
Courard, Luc ULg; Bissonnette, Benoît; Vaysburd, Alex et al

in Concrete Repair Bulletin (2012), 25(4), 22-30

Depending on the technique being used, the concrete removal operation prior to repair can be harmful to the residual concrete skin left on the structure. Whenever a tight bond between the repair and the ... [more ▼]

Depending on the technique being used, the concrete removal operation prior to repair can be harmful to the residual concrete skin left on the structure. Whenever a tight bond between the repair and the old concrete is required, the soundness of the prepared surface should thus be assessed. Although this is widely recognized, there is no standard method intended to characterize the integrity of a concrete substrate after concrete removal. This paper presents the results of an investigation intended to assess and compare quantitatively different test methods, namely the Schmidt rebound hammer, the pull-out test and the pull-off test, to evaluate superficial mechanical integrity of a substrate after concrete removal operations. Although it does not yield a precise evaluation of compressive strength, the Schmidt rebound hammer test is recognized as a useful tool for performing quick surveys to assess concrete uniformity. The pull-off test is very well correlated with the splitting-tensile test, but it is not suited for vertical and overhead surfaces. The Capo pull-out test has limited interest for surface preparation, as it is applicable to flat surfaces only. Conversely, the accelerated pull-out test showed interesting potential as a simple and relatively rapid means for assessing the mechanical integrity of a concrete surface prior to repair for any type of concrete surface. More work is definitely required to refine the procedures and develop performance criteria. Nevertheless, it appears from the results generated in this study that the combination Schmidt hammer / pull-off test could fill the needs for the evaluation of horizontal surfaces after concrete removal, while the combination Schmidt hammer / accelerated pull-out test could be used effectively on vertical and overhead surfaces. [less ▲]

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See detailA comparison of diagnosis of pregnancy in the goat via transrectal ultrasound scanning, progesterone, and pregnancy-associated glycoprotein assays
Gonzalez, Fernando; Cabrera, F.; Batista, M. et al

in Theriogenology (2004), 62(6), 1108-1115

Real-time ultrasound scanning (US) via the transrectal route, progesterone (P4) assay, and pregnancy-associated glycoprotein (PAG) detection can be used to diagnose pregnancy at around 3 weeks after ... [more ▼]

Real-time ultrasound scanning (US) via the transrectal route, progesterone (P4) assay, and pregnancy-associated glycoprotein (PAG) detection can be used to diagnose pregnancy at around 3 weeks after breeding. Although several studies have been carried out to evaluate each of these different methods individually, it is difficult to establish adequate comparisons due to differences, such as the breed of goat, age, and farming conditions, among others. The aim of the present paper is to compare the accuracy of diagnosis of pregnancy using transrectal US, P4 assay and PAG detection at the same time and on the same animals. Canary dairy goats (n = 143) were synchronized with an 11-day fluorogestone acetate (FGA) intravaginal sponge followed by PGF(2 alpha), and eCG 2 days before the FGA withdrawal. Blood samples were collected on Days 20, 22, 24, and 26 after mating to determine P4 and PAG concentrations. Transrectal US examinations were performed at the same time. There were 79 pregnant goats and another 64 non-pregnant. The US via the transrectal method and the determination of PAG concentrations provide very accurate pregnancy diagnosis at 24-26 days after breeding; on the contrary, P4 assay on plasma samples performed on Day 22 after breeding was accurate, in this case, in detecting pregnant animals but did not always detect the non-pregnant does. [less ▲]

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See detailComparison of different approaches to evaluate External Quality Assessment Data.
Coucke, Wim; China, Bernard; Delattre, Isabelle et al

in Clinica Chimica Acta (2012), 413(5-6), 582-6

In EQA programs, Z-scores are used to evaluate laboratory performance. They should indicate poorly performing laboratories, regardless of the presence of outliers. For this, two different types of ... [more ▼]

In EQA programs, Z-scores are used to evaluate laboratory performance. They should indicate poorly performing laboratories, regardless of the presence of outliers. For this, two different types of approaches exist. The first type are "outlier-based" approaches, which first exclude outlying values, calculate the average and standard deviation on the remaining data and obtain Z-scores for all values (e.g., Grubbs and Dixon). The second type includes the "robust" approaches (e.g., Tukey and Qn or the algorithm recommended by ISO). The different approaches were assessed by randomly generated samples from the Normal and Student t distributions. Part of the sample data were contaminated with outliers. The number of false and true outliers was recorded and subsequently, Positive and Negative Predictive Values were derived. Also, the sampling mean and variability were calculated for location and scale estimators. The various approaches performed similarly for sample sizes above 10 and when outliers were at good distance from the centre. For smaller sample sizes and closer outliers, however, the approaches performed quite differently. Tukey's method was characterised by a high true and a high false outlier rate, while the ISO and Qn approaches demonstrated weak performance. Grubbs test yielded overall the best results. [less ▲]

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See detailComparison of different impulse response measurement techniques
Stan, Guy-Bart; Embrechts, Jean-Jacques ULg; Archambeau, Dominique

in Journal of the Audio Engineering Society (2002), 50(4), 249-262

The impulse response of an acoustical space or transducer is one of its most important characterizations. In order to perform the measurement of their impulse responses, four of the most suitable methods ... [more ▼]

The impulse response of an acoustical space or transducer is one of its most important characterizations. In order to perform the measurement of their impulse responses, four of the most suitable methods are compared: MLS (maximum-length sequence), IRS (inverse repeated sequence), time-stretched pulses, and SineSweep. These methods have already been described in the literature. Nevertheless, the choice of one of them depending on the measurement conditions is critical. Therefore an extensive comparison has been realized. This comparison was done through the implementation and realization of a complete, fast, reliable, and cheap measurement system. Finally, a conclusion for the use of each method according to the principal measurement conditions is presented. It is shown that in the presence of nonwhite noise, the MLS and IRS techniques seem to be more accurate. On the contrary, in quiet environments the logarithmic SineSweep method seems to be the most appropriate. [less ▲]

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See detailComparison of different methods for characterizing multi-walled carbon nanotubes
Gommes, Cédric ULg; Blacher, Silvia ULg; Dupont-Pavlovsky, N. et al

in Colloids and Surfaces A : Physicochemical and Engineering Aspects (2004), 241(1-3), 155-164

Four complementary and independent methods are used to characterize nanotube samples: (i) TEM observation coupled with image analysis, (ii) nitrogen and krypton adsorption isotherm analysis, (iii ... [more ▼]

Four complementary and independent methods are used to characterize nanotube samples: (i) TEM observation coupled with image analysis, (ii) nitrogen and krypton adsorption isotherm analysis, (iii) thermogravimetry and (iv) wide angle X-ray scattering. The methodology is discussed on the basis of two multi-walled carbon nanotube samples produced by the CCVD technique with very different reaction rates. It is shown that the total amount of deposited carbon is larger for the sample produced at the higher rate, that the fraction of nanotubes in the deposited carbon does not seem to be significantly different, but that the crystallinity of the nanotubes wall is larger for the sample produced at the lowest reaction rate. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailComparison Of Different Methods For Detecting Gene-Gene Interactions In Case-Control Data
Cattaert, Tom ULg; Rial Garcia, J. A.; Gusareva, Elena ULg et al

Poster (2011, September 19)

It is generally believed that epistasis makes an important contribution to the genetic architecture of complex disease, and numerous statistical and bioinformatics methods have been developed to detect it ... [more ▼]

It is generally believed that epistasis makes an important contribution to the genetic architecture of complex disease, and numerous statistical and bioinformatics methods have been developed to detect it. We compare several state-of-the-art epistasis detection methods in terms of empirical power, type-I error control, and CPU time. The methods compared include Model-Based Multifactor Dimensionality Reduction (MB-MDR) [1, 2], BOolean Operation-based Screening and Testing (BOOST) [3], EPIBLASTER [4], Random Jungle (RJ) [5], Logistic Regression and PLINK. Our comparative study is based on an extensive simulation study using different two-locus models, exhibiting both main effects and epistasis [3]. In these simulations, 100 SNPs are generated, no LD between them. All genotypes are assumed to be in Hardy-Weinberg equilibrium. Furthermore, 2 disease-associated SNPs are selected, with MAFs set to 0.1, 0.2 and 0.4. The MAFs of the non-disease associated SNPs are uniformly distributed on [0.05, 0.5]. In order to achieve high accuracy in empirical power estimation, all simulation settings involve 1000 replicates. All methods are applied to WTCCC Crohn's Disease data. [1] Calle, M.L. et al. (2008), Tech. Rep. No. 24, Dep. of Systems Biology, Univ. de Vic [2] Cattaert, T. et al. (2011), Ann. Hum. Gen. 75, 78-89 [3] Wan, X. et al. (2010), Am. J. Hum. Gen. 87, 325-340 [4] Kam-Thong, T. et al. (2011), Eur. J. Hum. Gen. 19, 465-471 [5] Schwartz, D.F. et al. (2010), Bioinf. 26, 1752-1758 [less ▲]

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See detailComparison of different non-linear equations and corresponding unitarization schemes
Selyugin, O. V.; Cudell, Jean-René ULg

in Proceedings of science (2006)

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See detailComparison of Different Selection Strategies in Monte-Carlo Tree Search for the Game of Tron
Perrick, Pierre; Lupien St-Pierre, David ULg; Maes, Francis ULg et al

in IEEE Conference on Computational and Intelligence in Games 2012 (2012)

Monte-Carlo Tree Search (MCTS) techniques are essentially known for their performance on turn-based games, such as Go, for which players have considerable time for choosing their moves. In this paper, we ... [more ▼]

Monte-Carlo Tree Search (MCTS) techniques are essentially known for their performance on turn-based games, such as Go, for which players have considerable time for choosing their moves. In this paper, we apply MCTS to the game of Tron, a simultaneous real-time two-player game. The fact that players have to react fast and that moves occur simultaneously creates an unusual setting for MCTS, in which classical selection policies such as UCB1 may be suboptimal. In this paper, we perform an empirical comparison of a wide range of selection policies for MCTS applied to Tron, with both deterministic policies (UCB1, UCB1-Tuned, UCB-V, UCBMinimal, OMC-Deterministic, MOSS) and stochastic policies (Epsilon-greedy, EXP3, Thompson Sampling, OMC-Stochastic, PBBM). From the experiments, we observe that UCB1-Tuned has the best behavior shortly followed by UCB1. Even if UCB-Minimal is ranked fourth, this is a remarkable result for this recently introduced selection policy found through automatic discovery of good policies on generic multi-armed bandit problems. We also show that deterministic policies perform better than stochastic ones for this problem. [less ▲]

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See detailComparison of different techniques for inoculation of "Candidatus Phytoplasma mali" on apple and periwinkle in biological indexing procedure.
Aldaghi, M.; Massart, Sébastien ULg; Roussel, S. et al

in Communications in agricultural and applied biological sciences (2007), 72(4), 779-784

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See detailComparison of different techniques for inoculation of Candidatus phytoplasma mali in biological indexing
Aldaghi, M.; Massart, Sébastien ULg; Roussel, S. et al

Poster (2007)

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See detailComparison of different treatments of atrial fibrillation in the horse
Lekeux, Pierre ULg; Muylle, Etienne; Henroteaux, Marc ULg et al

in Zentralblatt für Veterinarmedizin. Reihe A (1981), 28(6), 475-480

In view of the disadvantages of the traditional method of atrial defibrillation, three different methods of treatment (intravenous perfusion of quinidine sulphate, intravenous perfusion of ... [more ▼]

In view of the disadvantages of the traditional method of atrial defibrillation, three different methods of treatment (intravenous perfusion of quinidine sulphate, intravenous perfusion of dihydroquinidine gluconate and repeated oral administration of quinidine sulphate) moere tested in 6 horses (7 attacks) from the point of view of efficacy, quantity of drug required, duration and convenience of the treatment, and toxicity. The authors conclude that the intravenous perfusion of quinidine sulphate under continuous ECG monitoring seems to be the method of choke for the treatment of atrial fibrillation in the horse. [less ▲]

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See detailA comparison of different types of commercial FBP and OSEM SPECT reconstruction software
Seret, Alain ULg; Forthomme, Julien

in Journal of Nuclear Medicine Technology (2009), 37(3), 179-187

This study aimed at comparing the performance of filtered backprojection (FBP) and ordered subset expectation maximisation (OSEM) reconstruction algorithms available in several types of commercial SPECT ... [more ▼]

This study aimed at comparing the performance of filtered backprojection (FBP) and ordered subset expectation maximisation (OSEM) reconstruction algorithms available in several types of commercial SPECT software. Methods: Numerical simulations of SPECT acquisitions of two phantoms were used: the NEMA line used for the assessment of SPECT resolution and a phantom with uniform, hot and cold rod compartments. The investigated types of software were: General Electric Xeleris and Vision, Philips Jetstream, Segami Mirage, Siemens eSoft and Icon, and Sopha Medical Vision XT. For FBP, no filtering and filtering of the projections with either Butterworth (order 3 or 6) or Hanning filters at various cut-off frequencies were considered. For OSEM, the number of subsets was 1, 4, 8, or 16 and the number of iterations was chosen to obtain a product number of iterations times the number of subsets equal to 16, 32, 48 or 64. The line phantom enabled us to obtain the reconstructed central, radial and tangential full-widths at half-maximum. The uniform compartment of the second phantom delivered the mean reconstructed pixel values and the standard deviations from which the coefficients of variation were calculated. Hot and cold contrasts were obtained from its rod compartments. Results: For FBP, full-widths at half-maximum, mean pixel values, coefficients of variation and contrasts were almost software independent. The only exceptions were: smaller (0.5 mm) full-widths at half-maximum for Vision, larger mean pixel values for Vision and XT, and better contrasts for Vision and XT for some filtering conditions. For OSEM, full-widths at half-maximum differed between the different types of software from 0.1 to 2.5 mm but these were almost independent of the number of subsets or iterations. There was a high dependence of the mean pixel value on the type of software used and a moderate dependence of the coefficient of variation. The contrasts were almost software independent. Mean pixel value varied greatly with the number of iterations for Mirage and Vision, and the coefficient of variation increased with the number of iterations for all types of software. The mean pixel value, the coefficient of variation and the contrasts were almost constant for a fixed product number of iterations times the number of subsets, whatever the number of subsets or iterations. Conclusion: Most of the types of software were equivalent for FBP or OSEM reconstruction. However, a few differences were observed for some types of software and should be considered when using them. [less ▲]

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