Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 11 (1 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 549 (8 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 57 (22 ULg)
Peer Reviewed
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 ▲]

Detailed reference viewed: 72 (5 ULg)
Full Text
See detailComparison of different non-linear equations and corresponding unitarization schemes
Selyugin, O. V.; Cudell, Jean-René ULg

in Proceedings of science (2006)

Detailed reference viewed: 3 (0 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 35 (5 ULg)
Full Text
Peer Reviewed
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

Detailed reference viewed: 15 (3 ULg)
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)

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 71 (4 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 118 (3 ULg)
Peer Reviewed
See detailComparison of different X-ray computed tomography techniques for the quantitative characterisation of the 3D microstructure of pear fruit tissue
Verboven, Pieter; Kerckhofs, Greet ULg; Mebatsion, Hibru K. et al

in Proceedings: Busse, G., Van Hemelrijck, D., Solodov, I., Anastasopoulos, A. (Eds.) (2007)

Detailed reference viewed: 12 (3 ULg)
Peer Reviewed
See detailComparison of Eae, Tir, Esp a and Esp b Genes of Bovine and Human Attaching and Effacing Escherichia Coli by Multiplex Polymerase Chain Reaction
China, B.; Goffaux, F.; Pirson, V. et al

in FEMS Microbiology Letters (1999), 178(1), 177-82

Attaching and effacing Escherichia coli (AEEC) virulence genes include the eae, the tir, the espA and the espB genes. These genes have been sequenced from several AEEC strains. The sequences alignments ... [more ▼]

Attaching and effacing Escherichia coli (AEEC) virulence genes include the eae, the tir, the espA and the espB genes. These genes have been sequenced from several AEEC strains. The sequences alignments revealed the presence of constant and variable regions. Multiplex polymerase chain reactions were developed, in order to determine the subtype of each gene present in a particular isolate. AEEC strains isolated from calves dead of diarrhea, from healthy calves and from infected humans were compared. The same pathotypes were found in sick and healthy calves but in inverted proportion. These pathotypes were also found in human AEEC. Although, the human EHEC strains from serotype O157 possessed their own pathotype. [less ▲]

Detailed reference viewed: 10 (1 ULg)
Full Text
Peer Reviewed
See detailComparison of Egg Composition and Conservation Ability in Two Belgian Local Breeds and One Commercial Strain
Moula, Nassim ULg; Antoine-Moussiaux, Nicolas ULg; Farnir, Frédéric ULg et al

in International Journal of Poultry Sciences (2009), 8(8), 768-774

The study was conducted to evaluate the egg quality of two Belgian local chicken breeds (the Ardennaise and the Famennoise) and to compare it with a commonly bred commercial strain (Lohmann brown). Two ... [more ▼]

The study was conducted to evaluate the egg quality of two Belgian local chicken breeds (the Ardennaise and the Famennoise) and to compare it with a commonly bred commercial strain (Lohmann brown). Two criteria were used to describe egg quality: egg composition (measured through yolk to albumen ratio) and its stability during conservation (measured through pH). Egg weight, size, composition as well as albumen pH were measured on 140 eggs. Measurements were performed at days 0, 7, 14 and 21 after laying. The egg weight was highest in the Lohmann strain (62.86 g), followed by the Famennoise breed (55.51 g) and lowest in the Ardennaise (50.31 g). Yolk to albumen ratio was significantly higher in the Ardennaise (0.53) when compared with the Famennoise (0.49) and Lohmann breeds (0.43). Albumen pH at laying was lowest in the Lohmann when compared with the local breeds. However, no statistical differences among the three breeds could be detected for this parameter at days 14 or 21 postlaying. The high pH in local breed eggs is often reported to be caused by a lower conservation ability. The present results suggest some physiologically higher pH at laying not resulting from defaults in conservation. As a measure of egg freshness, pH must be adapted by the various poultry breeds. [less ▲]

Detailed reference viewed: 104 (46 ULg)
Peer Reviewed
See detailComparison of ENFA and GLM modelling for summer habitat suitability of the sperm whale in the northwestern Mediterranean Sea
Praca, Emilie; Gannier, Alexandre; Das, Krishna ULg et al

Conference (2007)

Detailed reference viewed: 18 (2 ULg)
Full Text
Peer Reviewed
See detailComparison of external morphological traits of newborns to inner morphological traits of the dam in the double-muscled Belgian Blue Beef breed
Coopman, F.; Gengler, Nicolas ULg; Groen, A. F. et al

in Journal of Animal Breeding & Genetics (2004), 121(2), 128-134

In the double-muscled (DM) Belgian Blue Beef (BBB) breed, caesarean section (CS) is used as a routine management tool to prevent dystocia. This practice is criticized on animal welfare grounds. With ... [more ▼]

In the double-muscled (DM) Belgian Blue Beef (BBB) breed, caesarean section (CS) is used as a routine management tool to prevent dystocia. This practice is criticized on animal welfare grounds. With unassisted (natural) births, difficulties arise because of disproportion between the sizes of the newborn and inner pelvic sizes of the dam. In this study external morphological traits of newborns are compared with inner morphological traits of the dam. Results of this study indicate that in the DM-BBB, CS is the only means to successful calving. Therefore, no calving ease scores are available to select for less dystocia in this breed. Selection for fewer CS must be achieved by focusing on lower birth weight (BW) and decreased muscular conformation at birth, both having a sufficiently high heritability. Simultaneously, pelvic sizes of the dam should be increased. It is very likely that the look of the DM-BBB will change when selecting for less dystocia. [less ▲]

Detailed reference viewed: 20 (2 ULg)