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See detailComparison between principal component analysis and independent component analysis in EEG modelling
Bugli, Céline; Lambert, Philippe ULg

in Biometrical Journal = Biometrische Zeitschrift (2007), 49

Principal Component Analysis (PCA) is a classical technique in statistical data analysis, feature extraction and data reduction, aiming at explaining observed signals as a linear combination of orthogonal ... [more ▼]

Principal Component Analysis (PCA) is a classical technique in statistical data analysis, feature extraction and data reduction, aiming at explaining observed signals as a linear combination of orthogonal principal components. Independent Component Analysis (ICA) is a technique of array processing and data analysis, aiming at recovering unobserved signals or ‘sources’ from observed mixtures, exploiting only the assumption of mutual independence between the signals. The separation of the sources by ICA has great potential in applications such as the separation of sound signals (like voices mixed in simultaneous multiple records, for example), in telecommunication or in the treatment of medical signals. However, ICA is not yet often used by statisticians. In this paper, we shall present ICA in a statistical framework and compare this method with PCA for electroencephalograms (EEG) analysis.We shall see that ICA provides a more useful data representation than PCA, for instance, for the representation of a particular characteristic of the EEG named event-related potential (ERP). [less ▲]

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See detailComparison between Pulmonary Resistance and Penh in Anaesthetised Rats with Tracheal Diameter Reduction and after Carbachol Inhalation
Kirschvink, N.; Vincke, G.; Onclinx, C. et al

in Journal of Pharmacological & Toxicological Methods (2005), 51(2, Mar-Apr), 123-128

Introduction: Single-chambered barometric whole-body plethysmography is frequently used as a noninvasive lung function test. However, the validity of the enhanced Pause (Penh), an index of airflow ... [more ▼]

Introduction: Single-chambered barometric whole-body plethysmography is frequently used as a noninvasive lung function test. However, the validity of the enhanced Pause (Penh), an index of airflow limitation, remains controversial. We compared Penh with pulmonary resistance (R(L)) to test whether Penh detects tracheal subobstruction and carbachol-induced airflow limitation in spontaneously breathing, anaesthetised rats. Methods: Fourteen male Sprague-Dawley rats underwent tracheal catheterisation, followed by measurements of R(L) and Penh. Six rats underwent tracheal subobstruction by the consecutive insertion into the lumen of the tracheal tube of two catheters of decreasing diameter. Eight rats received an inhaled saline challenge, followed by two noncumulative nebulizations of carbachol (1.25 mg/mL, 1 min). Results: In rats with tracheal calibre reductions, R(L) significantly increased at each reduction (0.218+/-0.052 vs. 0.417+/-0.058 vs. 0.820+/-0.258 cm H(2)O/mL s, p<0.05), whereas Penh only increased after the last reduction (1.88+/-0.25 vs. 2.47+/-0.26, p<0.05). Increases (Delta) of R(L) and Penh were not correlated. In comparison to postsaline values, carbachol induced a significant increase of Penh (1.93+/-0.44 vs. 4.05+/-1.45, p<0.005) and R(L) (0.137+/-0.04 vs. 0.284+/-0.084 cm H(2)O/mL.s, p<0.005). DeltaPenh and DeltaR(L) were significantly correlated (r=0.80, p<0.05). Discussion: This study showed, by comparing Penh with R(L), that single-chambered plethysmography measuring Penh allows to detect carbachol-induced airflow limitation in spontaneously breathing, anaesthetised Sprague-Dawley rats, but poorly detects an increase in R(L) due to tracheal calibre reductions. These findings suggest that Penh might be only be used as an index of airflow limitation under well-defined experimental conditions. [less ▲]

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See detailA comparison between pulse contour analysis and Doppler echocardiographic measurements of cardiac output in awake horses
Guidi, E; Amory, Hélène ULg; Borde, Laura ULg et al

in In Proceedings of the 3rd Annual Congress of the European College of Equine Internal Medicine (ECEIM) (2009)

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See detailComparison between Radioactive Aerosol, Technegas and Krypton for Ventilation Imaging in Healthy Calves
Coghe, Joost; Votion, Dominique ULg; Lekeux, Pierre ULg

in Veterinary Journal (2000), 160(1), 25-32

The use of lung scintigraphy in calves necessitates the validation of a ventilation (V) imaging agent compatible with clinical applications. This study aimed at defining the value of an inhaled ... [more ▼]

The use of lung scintigraphy in calves necessitates the validation of a ventilation (V) imaging agent compatible with clinical applications. This study aimed at defining the value of an inhaled radioactive aerosol (99mTc-DTPA) and a 'pseudogas' (Technegas) in the assessment of regional V in healthy conscious calves by comparing 99mTc-DTPA and Technegas deposition (D) images to V(V) images obtained from the steady-state inhalation of the short half-life krypton 81 (81mKr) gas. Images were compared by analysis of radioactivity distribution in computer-generated regions of interest within the right lung and D to V ratio images were generated in order to highlight areas of mismatching between 99mTc-DTPA or Technegas and 81mKr distributions. Results of this analysis showed that the 99mTc-DTPA aerosol droplets were unable to reach the lung parenchyma because of significant particle impaction in the major conducting airways. Better definition of the ventilated lung was obtained when using Technegas because of minimal deposition in conducting airways. Furthermore, the Technegas and 81mKr distribution patterns were highly equivalent. [less ▲]

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See detailComparison between satellite and in situ sea surface temperature data in the Western Mediterranean Sea
Alvera Azcarate, Aïda ULg; Troupin, Charles ULg; Barth, Alexander ULg et al

in Ocean Dynamics (2011), 61(6), 767-778

A comparison between in situ and satellite sea surface temperature (SST) is presented for the western Mediterranean Sea during 1999. Several international databases are used to extract in situ data (World ... [more ▼]

A comparison between in situ and satellite sea surface temperature (SST) is presented for the western Mediterranean Sea during 1999. Several international databases are used to extract in situ data (World Ocean Database (WOD), MEDAR/Medatlas, Coriolis Data Center, International Council for the Exploration of the Sea (ICES) and International Comprehensive Ocean-Atmosphere Data Set (ICOADS)). The in situ data are classified into different platforms or sensors (CTD, XBT, drifters, bottles, ships), in order to assess the relative accuracy of these type of data respect to AVHRR (Advanced Very High Resolution Radiometer) SST satellite data. It is shown that the results of the error assessment vary with the sensor type, the depth of the in situ measurements, and the database used. Ship data are the most heterogeneous data set, and therefore present the largest differences with respect to in situ data. A cold bias is detected in drifter data. The differences between satellite and in situ data are not normally distributed. However, several analysis techniques, as merging and data assimilation, usually require Gaussian-distributed errors. The statistics obtained during this study will be used in future work to merge the in situ and satellite data sets into one unique estimation of the SST. [less ▲]

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See detailComparison between single-beat and multiple-beat methods for estimation of right ventricular contractility.
Lambermont, Bernard ULg; Segers, Patrick; Ghuysen, Alexandre ULg et al

in Critical Care Medicine (2004), 32(9), 1886-90

OBJECTIVE: It was investigated whether pharmacologically induced changes in right ventricular contractility can be detected by a so-called "single-beat" method that does not require preload reduction ... [more ▼]

OBJECTIVE: It was investigated whether pharmacologically induced changes in right ventricular contractility can be detected by a so-called "single-beat" method that does not require preload reduction. DESIGN: Prospective animal research. SETTING: Laboratory at a large university medical center. SUBJECTS: Eight anesthetized pigs. INTERVENTIONS: End-systolic elastance values obtained by a recently proposed single-beat method (Eessb) were compared with those obtained using the reference multiple-beat method (Eesmb). MEASUREMENTS AND MAIN RESULTS: Administration of dobutamine increased Eesmb from 1.6 +/- 0.3 to 3.8 +/- 0.5 mm Hg/mL (p =.001), whereas there was only a trend toward an increase in Eessb from 1.5 +/- 0.2 to 1.7 +/- 0.4 mm Hg/mL. Esmolol decreased Eesmb from 1.7 +/- 0.3 to 1.1 +/- 0.2 mm Hg/mL (p =.006), whereas there was only a trend for a decrease in Eessb from 1.5 +/- 0.2 to 1.3 +/- 0.1. CONCLUSIONS: The present method using single-beat estimation to assess right ventricular contractility does not work as expected, since it failed to detect either increases or decreases in right ventricular contractility induced by pharmacologic interventions. [less ▲]

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See detailComparison between Solution-Phase Stability and Gas-Phase Kinetic Stability of Oligodeoxynucleotide Duplexes
Gabelica, Valérie ULg; De Pauw, Edwin ULg

in Journal of Mass Spectrometry [=JMS] (2001), 36(4), 397-402

The relative kinetic stabilities of different 16-mer oligonucleotide duplexes were investigated by source collision-induced dissociation (CID) in a heated capillary electrospray ion source. They were ... [more ▼]

The relative kinetic stabilities of different 16-mer oligonucleotide duplexes were investigated by source collision-induced dissociation (CID) in a heated capillary electrospray ion source. They were compared with the relative stabilities in solution obtained by thermal denaturation monitored by UV spectrophotometry. The results clearly show that both hydrogen bonding and base stacking interactions that are present in solution are maintained in the gas phase. This suggests that the electrospray process preserves the double-helix structure of DNA. A step by step opening of the double helix structure is proposed for the gas-phase dissociation, competing with the covalent bond cleavage of bases. We also draw attention to the fact that by source CID, it is the kinetic stability of the complexes that is probed. In particular, this implies that only complexes of the same size can be compared. [less ▲]

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See detailA comparison between subjective and objective methods for evaluating the vocal accuracy of a popular song
Larrouy, Pauline ULg; Lévêque, Yohana; Giovanni, Antoine et al

Poster (2012, July 25)

Vocal accuracy of a sung performance can be evaluated by two methods: acoustical analyses and subjective judgements. For one decade, acoustic analyses have been presented as a more reliable solution to ... [more ▼]

Vocal accuracy of a sung performance can be evaluated by two methods: acoustical analyses and subjective judgements. For one decade, acoustic analyses have been presented as a more reliable solution to evaluate vocal accuracy, avoiding the limitation of experts’ perceptive system and their variability. This paper presents for the first time a direct comparison of these methods. 166 occasional singers were asked to sing the popular song « Happy Birthday ». Acoustic analyses were performed to quantify the pitch interval deviation, the number of contour errors and the number of tonality modulations for each recording. Additionally, eighteen experts in singing voice or music rated the global pitch accuracy of these performances. The results showed a high inter-rater concordance within the judges. In addition, a high correlation occurred between acoustic measurements and subjective rating. The total model of acoustic analyses explained 81% of the variance of the judges’ scores. Their rating was influenced by both tonality modulations and interval deviations. This study highlights the congruence between objective and subjective measurements of vocal accuracy while the assessment is done by music or singing voice experts. Our results confirm the relevance of the “pitch interval deviation” criterion in vocal accuracy assessment. Furthermore, the “number of tonality modulations” is a salient criterion in perceptive rating and should be taken into account in studies using acoustical analyses. [less ▲]

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See detailComparison between swabbing and destructive methods for microbiological pig carcass sampling.
Ghafir, Yasmine; Daube, Georges ULg

in Letters in Applied Microbiology (2008), 47

Aims: To compare the Belgian swabbing sampling method for pig carcasses with the reference destructive method with regard to Escherichia coli and aerobic plate counts, Salmonella and Campylobacter ... [more ▼]

Aims: To compare the Belgian swabbing sampling method for pig carcasses with the reference destructive method with regard to Escherichia coli and aerobic plate counts, Salmonella and Campylobacter prevalence and their relationship. Methods and Results: Recovery was significantly lower for the swabbing method and corresponded to a recovery of 36% for E. coli counts and 81% for aerobic plate counts in comparison with the destructive method. There was no significant difference between the swabbing and destructive sampling methods for the prevalence of Salmonella or Campylobacter. A higher median for E. coli counts was detected for samples where Salmonella or Campylobacter were detected. The same association was also observed between the median for aerobic plate counts and the presence of Campylobacter. Conclusions: The method of swabbing used, covering 600 cm2 on each half-pig carcass, is efficient for the sampling of pig carcasses in comparison with the reference destructive method. Significance and Impact of the Study: This study describes an efficient method for microbiological pig carcass sampling. The Belgian swabbing method should continue to be used to allow the follow up of bacterial contamination in the Belgian meat production chain. [less ▲]

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See detailComparison between temporal pressure and ERT signals in a bubble column
Fransolet, Emmanuelle; Toye, Dominique ULg; Crine, Michel ULg et al

Conference (2002)

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See detailComparison between the charring rate model and the conductive model of Eurocode 5
Cachim, Paulo B.; Franssen, Jean-Marc ULg

in Fire & Materials (2009), 33

Eurocode 5, Part 1-2, presents several models for the calculation of fire resistance of timber structures. These models are based on the hypothesis that for temperatures above 300°C, wood is no longer ... [more ▼]

Eurocode 5, Part 1-2, presents several models for the calculation of fire resistance of timber structures. These models are based on the hypothesis that for temperatures above 300°C, wood is no longer able to sustain any stress, which makes the determination of the location of the 300°C isotherm decisive for the result provided by the models. In this paper, the charring rate model and the conductive model presented in Eurocode 5, part 1-2 are compared regarding the determination of the location of 300°C isotherm. The main wood parameters investigated are density, moisture content and anisotropy. the almost complete independence of the charring rate model from these parameters leads to some inconsistencies between the models. To reduce thse inconsistencies some proposals to improve the conductive and the charring rate models are presented. [less ▲]

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See detailComparison between the GIRBAS Scale and the Acoustic and Aerodynamic Measures Provided by EVA for the Assessment of Dysphonia following Unilateral Vocal Fold Paralysis.
Morsomme, Dominique ULg; Jamart, Jacques; Wery, Carine et al

in Folia Phoniatrica et Logopaedica (2001), 53(6), 317-25

The aim of this study is to establish relevant objective parameters for evaluating dysphonia following unilateral vocal fold paralysis. To do so, the study compares objective and perceptual voice measures ... [more ▼]

The aim of this study is to establish relevant objective parameters for evaluating dysphonia following unilateral vocal fold paralysis. To do so, the study compares objective and perceptual voice measures. The objective measures were obtained using a voice analysis software (Evaluation Vocale Assistee), whereas the perceptual measures were established with the GIRBAS Scale (grade, instability, roughness, breathiness, asthenia, and strain). All measurements were performed on 40 voice samples: 28 dysphonic subjects with unilateral laryngeal paralysis, and 12 control subjects. The intra- and inter-judge agreements were fairly good, at least for control subjects. The six GIRBAS measures obtained from the pathological voices were higher than those from the control voices (p < 0.001) and the correlation between both groups was good. Grade, breathiness and asthenia correlated with the objective parameters that express the aperiodicity of the phonatory signal (p < 0.01), namely, the coefficient of variability of the fundamental frequency, the coefficient of variability of intensity, and jitter. Our findings suggest that the perceptual reality of laryngeal paralysis-induced dysphonia depends more on grade, breathiness and asthenia than it does on roughness or instability. [less ▲]

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See detailComparison between the Natural Postnatal Maturation and the Spermine-Induced Maturation of the Rat Intestine
Peulen, Olivier ULg; Pirlet, Christine; Klimek, Monique ULg et al

in Archives of Physiology & Biochemistry (1998), 106(1), 46-55

In the suckling rats, orally provided spermine induced structural and biochemical changes in the intestine, which are characteristics of the postnatal maturation. This induced maturation was compared to ... [more ▼]

In the suckling rats, orally provided spermine induced structural and biochemical changes in the intestine, which are characteristics of the postnatal maturation. This induced maturation was compared to that occurring spontaneously. Eight mumol spermine were administered orally once a day, for one or three days, to suckling rats which were 11 days old at the beginning of the experiment. The animals were killed 0, 2, 4, 6, 8, 10 hours or 3 days after the first treatment. Control rats from the same litter were treated in the same way but received only the vehicle. In order to complete the study of the naturally occurring maturation, another group of rats was killed when they were 12, 13, 15, 16, 17, 18, 19, 20, 21 or 30 days old. Animal and intestine weights were measured. Disaccharidase specific activity, and protein, DNA and RNA contents were estimated in the small intestine. Histological and ultrastructural aspects of the intestinal mucosa were examined. For all these parameters, the maturation induced by spermine ingestion appeared close to that occurring naturally at weaning. Consequently, dietary spermine induces all the morphological and biochemical modifications characterizing the intestinal postnatal maturation in the suckling rat suggesting a role of the polyamines in the naturally occurring processes. [less ▲]

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See detailComparison between the SMM and GEMINI++ de-excitation models
Mancusi, Davide ULg; Cugnon, Joseph ULg; Boudard, A. et al

in Proceedings to the Satellite Meeting on Nuclear Spallation Reactions, International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators 2009 (2010)

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See detailA comparison between the TEC computed using GPS and ionosonde measurements
Warnant, René ULg; Jodogne, Jean-Claude

in Acta Geodaetica et Geophysica Hungarica (1998), 33(1), 147-153

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