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See detailDetection of Defects in Concrete With Ground Penetrating Radar
Van der Wielen, Audrey ULg; Courard, Luc ULg; Nguyen, Frédéric ULg

in ESPSC 2011: European Symposium on Polymers in Sustainable Construction (Czarnecki Symposium) (2011, September)

Ground Penetrating Radar (GPR) is a nondestructive technique particularly well adapted to the inspection of concrete structures and can help to determine the structure inner geometry or to detect damaged ... [more ▼]

Ground Penetrating Radar (GPR) is a nondestructive technique particularly well adapted to the inspection of concrete structures and can help to determine the structure inner geometry or to detect damaged areas. When the GPR is used on structures containing thin layers, for example the sealing layer of a bridge or the void into a masonry wall, it is important for the radar user to know the minimum thickness required to detect and estimate the thickness of those layers. The theory of thin layer detection is based on a sine wave but, in reality, the GPR emits a complicated pulse, which undergoes attenuation into the layer. To see the influence of those realistic conditions on the reflection coefficient of a thin layer, we combined experimental measurements and numerical FDTD simulations. The experimental results matched the numerical predictions well, presenting a fast attenuation compared to the theoretical predictions. Nevertheless, for thicknesses inferior to λ/11, the reflection coefficient could still be considered as linearly dependent of the thickness to wavelength ratio. [less ▲]

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See detailDetection of defects on fruits by machine vision and unsupervised segmentation
Kleynen, Olivier; Destain, Marie-France ULg

in AgEng 2004 Conference (2004, September)

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images ... [more ▼]

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images are acquired by conventional RGB cameras and defect segmentation is performed by algorithms based on Bayes' rules. The efficiency of these methods can be improved firstly by acquiring images with a dedicated vision system (multi-spectral imager) and secondly by implementing unsupervised segmentation methods (method derived from the 'mean shift' procedure of Camaniciu and Meer, 2002). [less ▲]

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See detailDetection of defects on fruits by machine vision and unsupervised segmentation
Kleynen, Olivier; Destain, Marie-France ULg

in AgEng 2004 Conference - Engineering the fuiture (2004)

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images ... [more ▼]

Defect detection on fruits by machine vision is a complex task. Indeed, the sound tissue colour is not uniform and the defects present a wide variability in colour, shape and texture. Mostly often, images are acquired by conventional RGB cameras and defect segmentation is performed by algorithms based on Bayes'rules. The efficiency of these methods can be improved firstly by acquiring images with a dedicated vision system (multi-spectal imager) and secondly by implementing unsupervised segmentation methods (based on the 'mean shift' procedure; Comaniciu and Meer, 2002). [less ▲]

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See detailDetection of differential host susceptibility to the marine oomycete pathogen Eurychasma dicksonii by real-time PCR: not all algae are equal.
Gachon, Claire M. M.; Strittmatter, Martina; Müller, Dieter G. et al

in Applied and environmental microbiology (2009), 75(2), 322--8

In the marine environment, a growing body of evidence points to parasites as key players in the control of population dynamics and overall ecosystem structure. However, their prevalence and impact on ... [more ▼]

In the marine environment, a growing body of evidence points to parasites as key players in the control of population dynamics and overall ecosystem structure. However, their prevalence and impact on marine macroalgal communities remain virtually unknown. Indeed, infectious diseases of seaweeds are largely underdocumented, partly because of the expertise required to diagnose them with a microscope. Over the last few years, however, real-time quantitative PCR (qPCR) has emerged as a rapid and reliable alternative to visual symptom scoring for monitoring pathogens. Thus, we present here a qPCR assay suitable for the detection and quantification of the intracellular oomycete pathogen Eurychasma dicksonii in its ectocarpalean and laminarialean brown algal hosts. qPCR and microscopic observations made of laboratory-controlled cultures revealed that clonal brown algal strains exhibit different levels of resistance against Eurychasma, ranging from high susceptibility to complete absence of symptoms. This observation strongly argues for the existence of a genetic determinism for disease resistance in brown algae, which would have broad implications for the dynamics and genetic structure of natural populations. We also used qPCR for the rapid detection of Eurychasma in filamentous brown algae collected in Northern Europe and South America and found that the assay is specific, robust, and widely applicable to field samples. Hence, this study opens the perspective of combining large-scale disease monitoring in the field with laboratory-controlled experiments on the genome model seaweed Ectocarpus siliculosus to improve our understanding of brown algal diseases. [less ▲]

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See detailDetection of differential item functioning using the lasso approach
Magis, David ULg; Tuerlinckx, Francis; De Boeck, Paul

in Journal of Educational & Behavioral Statistics (2015), 40

This paper proposes a novel approach to detect differential item functioning (DIF) among dichotomously scored items. Unlike standard DIF methods that perform an item-by-item analysis, we propose the “LR ... [more ▼]

This paper proposes a novel approach to detect differential item functioning (DIF) among dichotomously scored items. Unlike standard DIF methods that perform an item-by-item analysis, we propose the “LR lasso DIF method”: logistic regression (LR) model is formulated for all item responses. The model contains item specific intercepts, an effect of the sum score and item-group interaction (i.e. DIF) effects, with a lasso penalty on all DIF parameters. Optimal penalty parameter selection is investigated through several known information criteria (AIC, BIC and cross-validation) as well as through a newly developed alternative. A simulation study was conducted to compare the global performance of the suggested “LR lasso DIF” method to the logistic regression and Mantel-Haenszel methods (in terms of false alarm and hit rates). It is concluded that for small samples the LR lasso DIF approach globally outperforms the logistic regression method, and also the Mantel-Haenszel method, especially in the presence of item impact, while it yields similar results with larger samples. [less ▲]

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See detailDetection of differential item functioning using the lasso approach
Magis, David ULg; Tuerlinckx, Francis; De Boeck, Paul

Conference (2014, July 22)

The purpose of this talk is to present a novel approach to detect differential item functioning (DIF) among dichotomously scored items. Unlike standard DIF methods that perform an item-by-item analysis ... [more ▼]

The purpose of this talk is to present a novel approach to detect differential item functioning (DIF) among dichotomously scored items. Unlike standard DIF methods that perform an item-by-item analysis, we consider a logistic regression model including item-group interaction (i.e. DIF) effects of all items simultaneously. The method is based on penalized maximum likelihood estimation of a model with a lasso penalty on all possible DIF parameters. Optimal penalty parameter selection is investigated through several known information criteria (such as AIC and BIC) as well as a newly developed weighted alternative. A simulation study was conducted to compare the global performance of the suggested “lasso DIF” method to the logistic regression and Mantel-Haenszel methods, and to evaluate the different optimal penalty parameter selection methods. It is concluded that for small samples the lasso DIF approach globally outperforms the logistic regression method, and also the Mantel-Haenszel method, especially in the presence of item impact, while it yields similar results with larger samples. [less ▲]

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See detailDetection of differential item functioning with the difR package
Magis, David ULg; Béland, Sébastien; Tuerlinckx, Francis et al

Poster (2010, July)

The purpose of this talk is to briefly present the package difR of the software R. This package permits to identify differential item functioning (DIF) with several parametric or nonparametric methods ... [more ▼]

The purpose of this talk is to briefly present the package difR of the software R. This package permits to identify differential item functioning (DIF) with several parametric or nonparametric methods. Nonparametric methods include: Mantel-Haenszel, standardization, logistic regression and Breslow-Day. Available parametric methods are the Lord’s chi-square test, the Raju’s area method, and the likelihood-ratio test. Some methods for DIF identification in multiple groups (generalized Mantel-Haenszel, generalized Lord’s test) are also available. The presentation focuses on the package and its potential, rather than on the included methods. Its performance will be illustrated with an example data set. [less ▲]

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See detailDetection of differential item functioning: crossed random-effects models and robust diagnostics tools
Magis, David ULg; De Boeck, Paul

Scientific conference (2008, September)

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See detailDetection of disease resistance and susceptibility alleles in pigs using oligonucleotide microarray hybridization
Pastoret, Soumya; Ameels, Hélène; Bossiroy, Frédérique et al

in Journal of Veterinary Diagnostic Investigation (2012), 24(3), 479-488

A multiplex DNA microarray chip aimed at the identification of allelic polymorphisms was developed for simultaneous detection of swine disease resistance genes underlying malignant hyperthermia (RYR ... [more ▼]

A multiplex DNA microarray chip aimed at the identification of allelic polymorphisms was developed for simultaneous detection of swine disease resistance genes underlying malignant hyperthermia (RYR ), postweaning diarrhea, edema disease (FUT1), neonatal diarrhea (MUC4), and influenza (MX1). The on-chip detection was performed with fragmented polymerase chain reaction (PCR)-amplified products. Particular emphasis was placed on the reduction of the number of PCR reactions required. The targets were biotin labeled during the PCR reaction, and the arrays were detected using a colorimetric methodology. Target recognition was provided by specific capture probes designed for each susceptible or resistant allelic variant. Sequencing was chosen as the golden standard to assess chip’s accuracy. All genotypes retrieved from the microarray (476) fitted with sequencing data in spite of the fact that each pig was heterozygote for at least 1 target gene. [less ▲]

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See detailDetection of diverse mould species growing on building materials by gas sensor arrays and pattern recognition
Kuske, Martyna; Padilla, M.; Romain, Anne-Claude ULg et al

in Sensors and actuators. B, Chemical (2006), 119(1), 33-40

This work explores the detection of moulds growing in different building materials by using a metal oxide sensor array. Four moulds species have been considered. Pattern classification provides detection ... [more ▼]

This work explores the detection of moulds growing in different building materials by using a metal oxide sensor array. Four moulds species have been considered. Pattern classification provides detection rates on the order of 80-85% for different species. Drift degrades only slightly these values subsequent test 4 months later. [less ▲]

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See detailDetection of early sympathetic cardiovascular neuropathy by squatting test in NIDDM.
Marfella, R.; Salvatore, T.; Giugliano, D. et al

in Diabetes Care (1994), 17(2), 149-51

OBJECTIVE--To determine the role of the squatting test in the detection of early sympathetic neuropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS--Three ... [more ▼]

OBJECTIVE--To determine the role of the squatting test in the detection of early sympathetic neuropathy in patients with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS--Three groups of nonsmoking, nonobese subjects were studied: 10 healthy subjects, 10 NIDDM patients without autonomic neuropathy (AN), and 10 NIDDM patients with AN defined by the presence of a pathological deep-breathing value. All subjects were given three postural tests: lying-to-standing, sitting-to-standing, and squatting test. Heart rate (HR) and finger arterial pressure were recorded with a noninvasive technique. RESULTS--Blood pressure (BP) fall (expressed as decremental area) was not significantly different among the groups at standing up after sitting or lying. By contrast, a significantly greater BP drop occurred in NIDDM patients with AN (1,123 +/- 245 mm2) compared with NIDDM patients without AN (460 +/- 232 mm2) or normal subjects (429 +/- 138 mm2, P < 0.001). The HR increase after all the orthostatic maneuvers was smaller in diabetic patients with AN (P < 0.01) compared with that recorded in other groups. Significant correlations were observed between BP fall after squatting and either the expiration:inspiration ratio at deep breathing (r = -0.77, P < 0.001) or the duration of diabetes (r = 0.76, P < 0.001). CONCLUSIONS--The intrinsic orthostatic load of the squatting test, which is greater than conventional postural maneuvers, makes the squatting test an easy and useful test to detect early orthostatic dysregulation in NIDDM. [less ▲]

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See detailDetection of Echinococcus multilocularis in wild boars in France using PCR techniques against larval form
Boucher, J. M.; Hanosset, R.; Augot, D. et al

in Veterinary Parasitology (2005), 129(3-4), 259-266

Recently, new data have been collected on the distribution and ecology of Echinococcus multilocularis in European countries. Different ungulates species such as pig, goat, sheep, cattle and horse are ... [more ▼]

Recently, new data have been collected on the distribution and ecology of Echinococcus multilocularis in European countries. Different ungulates species such as pig, goat, sheep, cattle and horse are known to host incomplete development of larval E. multilocularis. We report a case of E. multilocularis portage in two wild boars from a high endemic area in France (Department of Jura). Histological examination was performed and the DNA was isolated from hepatic lesions then amplified by using three PCR methods in two distinct institutes. Molecular characterisation of PCR products revealed 99% nucleotide sequence homology with the specific sequence of the U1 sn RNA gene of E. multilocularis, 99 and 99.9% nucleotide sequence homology with the specific sequence of the cytochrome oxydase gene of Echinococcus genus and 99.9% nucleotide sequence homology with a genomic DNA sequence of Echinococcus genus for the first and the second wild boar, respectively. (c) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailDetection of eye movements specific to drowsiness and their relation with subjective assessment of sleepiness in PVT: A cognitive ergonomic approach
Blavier, Adelaïde ULg; Montagnino, Cédric; Wertz, Jérôme ULg et al

Conference (2014, February 24)

Drowsiness is one of the major factors explaining accidents, particularly in traffic accidents but also in work situations with serious consequences (e.g. medicine). The drowsiness may be assessed by ... [more ▼]

Drowsiness is one of the major factors explaining accidents, particularly in traffic accidents but also in work situations with serious consequences (e.g. medicine). The drowsiness may be assessed by diverse measures that vary from physiological and unconscious data (e.g. EEG) to subjective and conscious evaluation. In their daily life, people are used to evaluate their drowsiness by subjective assessment and research observes a great inter-individual variation in this evaluation. Moreover, the subjective evaluation is dependent on the situation and the risk perceived by the person (e.g., new versus usual situations, simple versus complex environments, etc.). In this theoretical context, our purpose was to investigate the links between 1) objective performance (reaction time) measured by a psychomotor vigilance task (PVT), 2) data from eye movements and 3) subjective assessment of drowsiness (measured with Karolinska Sleepiness Scale, KSS). 12 persons, aged from 20 to 56, participated individually. They were asked to respect a 60% sleep deprivation during the night before the experiment and to not drink any energy drinks the day of the experiment. The experiment was conducted between 1 and 3 PM after a heavy lunch in order to increase the circadian effect. Moreover, the temperature of the room was 25° in order to increase drowsiness. Each participant was asked to perform 4 PVT. However, although 100% of participants performed the first two PVT, only 66% were able to perform the third PVT and only 33% of participants performed the fourth and last PVT. Our results showed an effect of time on objective performance, eye movements and subjective assessment of drowsiness in PVT 1 and 2: significant increase of reaction time, increase of eye closure and perclos, reduction of pupil diameter and increase of subjective drowsiness estimation (KSS). Only the frequency and duration of blinks remained constant across time. In PVT 3 and 4, data from eye movements and objective performance (reaction time) did not vary anymore across the time. Only the subjective estimation of drowsiness (KSS) continued to increase. Furthermore, subjective estimation of drowsiness was differently correlated with eye movements and objective performance across the PVT; it was significantly correlated with reaction time (PVT 1,2,3), blink frequency and duration (PVT 1,2,3), perclos (PVT 1,2,3,4), eye closure (PVT 2,3), pupil diameter (PVT 1,2,3,4). These results are discussed and integrated in an ergonomic approach in order to analyze the links between objective performance, eye movements and subjective assessment of drowsiness. [less ▲]

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See detailDetection of eye movements specific to drowsiness and their relation with subjective assessment: A cognitive ergonomic approach.
Blavier, Adelaïde ULg; Montagnino, Cédric; Wertz, Jérôme ULg et al

Poster (2014, May 27)

Drowsiness is one of the major factors explaining accidents, particularly in traffic accidents but also in work situations with serious consequences (e.g. medicine). The drowsiness may be assessed by ... [more ▼]

Drowsiness is one of the major factors explaining accidents, particularly in traffic accidents but also in work situations with serious consequences (e.g. medicine). The drowsiness may be assessed by diverse measures that vary from physiological and unconscious data (e.g. EEG) to subjective and conscious evaluation. In their daily life, people are used to evaluate their drowsiness by subjective assessment and research observes a great inter-individual variation in this evaluation. Moreover, the subjective evaluation is dependent on the situation and the risk perceived by the person (e.g., new versus usual situations, simple versus complex environments, etc.). In this theoretical context, our purpose was to investigate the links between 1) objective performance (reaction time) measured by a psychomotor vigilance task (PVT), 2) data from eye movements and 3) subjective assessment of drowsiness (measured with Karolinska Sleepiness Scale, KSS). 12 persons, aged from 20 to 56, participated individually. They were asked to respect a 60% sleep deprivation during the night before the experiment and to not drink any energy drinks the day of the experiment. The experiment was conducted between 1 and 3 PM after a heavy lunch in order to increase the circadian effect. Moreover, the temperature of the room was 25° in order to increase drowsiness. Each participant was asked to perform 4 PVT. However, although 100% of participants performed the first two PVT, only 66% were able to perform the third PVT and only 33% of participants performed the fourth and last PVT. Our results showed an effect of time on objective performance, eye movements and subjective assessment of drowsiness in PVT 1 and 2: significant increase of reaction time, increase of eye closure and perclos, reduction of pupil diameter and increase of subjective drowsiness estimation (KSS). Only the frequency and duration of blinks remained constant across time. In PVT 3 and 4, data from eye movements and objective performance (reaction time) did not vary anymore across the time. Only the subjective estimation of drowsiness (KSS) continued to increase. Furthermore, subjective estimation of drowsiness was differently correlated with eye movements and objective performance across the PVT; it was significantly correlated with reaction time (PVT 1,2,3), blink frequency and duration (PVT 1,2,3), perclos (PVT 1,2,3,4), eye closure (PVT 2,3), pupil diameter (PVT 1,2,3,4). These results are discussed and integrated in an ergonomic approach in order to analyze the links between objective performance, eye movements and subjective assessment of drowsiness. [less ▲]

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See detailDetection of food antigens in dog foods used as elimination diets
Ricci, Rebecca; Granato, A; Palagiano, C et al

in Castrillo, Carlos (Ed.) Congress Proceedings 15th Congress ESVCN (2011, September)

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See detailDetection of forest fragmentation gradients and intensities.
Bogaert, Jan ULg; Salvador-Van Eysenrode, David; Van Hecke, Piet et al

in Maudsley, M; Marshall, J. (Eds.) Heterogeneity in Landscape Ecology: Pattern and Scale (1999)

Detailed reference viewed: 16 (6 ULg)
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See detailDetection of frequency spacings in the young O-type binary HD 46149 from CoRoT photometry
Degroote, P.; Briquet, Maryline ULg; Auvergne, M. et al

in Astronomy and Astrophysics (2010), 519

<BR /> Aims: Using the CoRoT space based photometry of the O-type binary HD 46149, stellar atmospheric effects related to rotation can be separated from pulsations, because they leave distinct signatures ... [more ▼]

<BR /> Aims: Using the CoRoT space based photometry of the O-type binary HD 46149, stellar atmospheric effects related to rotation can be separated from pulsations, because they leave distinct signatures in the light curve. This offers the possibility of characterising and exploiting any pulsations seismologically. <BR /> Methods: Combining high-quality space based photometry, multi-wavelength photometry, spectroscopy and constraints imposed by binarity and cluster membership, the detected pulsations in HD 46149 are analyzed and compared with those for a grid of stellar evolutionary models in a proof-of-concept approach. <BR /> Results: We present evidence of solar-like oscillations in a massive O-type star, and show that the observed frequency range and spacings are compatible with theoretical predictions. Thus, we unlock and confirm the strong potential of this seismically unexplored region in the HR diagram. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.Based on observations made with the ESO telescopes at La Silla Observatory under the ESO Large Programme LP182.D-0356.Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. [less ▲]

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