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Peer Reviewed
See detailComparison of necrotoxigenic Escherichia coli isolates from farm animals and humans
Mainil, Jacques ULg; Jacquemin, E.; Pohl, P. et al

in Veterinary Microbiology (1999), 70

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See detailComparison of Neuromuscular Block of Atracurium and Rocuronium in Adults
Hans, Pol ULg; Brichant, Jean-François ULg; Franzen, A. et al

in Acta Anaesthesiologica Belgica (1996), 47(2), 53-8

We studied the time-course of action of atracurium 0.5 mg kg-1 and rocuronium 0.6 mg kg-1 in 24 healthy adult patients. Anesthesia was induced with thiopentone and sufentanil, and maintained with 50 ... [more ▼]

We studied the time-course of action of atracurium 0.5 mg kg-1 and rocuronium 0.6 mg kg-1 in 24 healthy adult patients. Anesthesia was induced with thiopentone and sufentanil, and maintained with 50% nitrous oxide and 1% enflurane in oxygen. Neuromuscular transmission was monitored by stimulating the ulnar nerve at the wrist and measuring the acceleration of the thumb using the TOF-Guard accelerograph monitor. Supramaximal stimuli of 0.2 ms duration were applied in a single twitch stimulation mode at 1 Hz frequency until completion of block, and in train-of four (TOF) sequence at 2 Hz every 15 sec thereafter. Onset time was longer with atracurium (mean +/- SD:90 +/- 18 sec) than with rocuronium (49 +/- 6 sec). Clinical duration of action (Tl25) was longer with atracurium (52.3 +/- 7.2 min) than with rocuronium (40.0 +/- 6.4 min). Recovery index (Tl25-Tl75) and time for TOF ratio to recover to 0.75 were 17.8 +/- 4.2 and 73.9 +/- 8.8 min with atracurium, and 13.8 +/- 4.1 and 70.4 +/- 14.1 min with rocuronium. The differences between both groups were statistically significant except the difference in the time for TOF to return to 0.75. [less ▲]

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See detailComparison of noise, hot and cold contrast of eight tomographic camera models.
Seret, Alain ULg; Nguyen, Thibaut

in European Journal of Nuclear Medicine and Molecular Imaging (2006), 33(S2), 282

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See detailComparison of non-linear growth models to describe the growth curve in West African Dwarf Sheep
Gbangboche, A. B.; Gleke-Kakai, R.; Albuquerque, L. G. et al

in Animal (2008), 2(7), 1003-1012

The objectives of this study were to compare the goodness of fit of four non-linear growth models, i.e. Brody, Gompertz, Logistic and Von Bertalanffy, in West African Dwarf (WAD) sheep. A total of 5274 ... [more ▼]

The objectives of this study were to compare the goodness of fit of four non-linear growth models, i.e. Brody, Gompertz, Logistic and Von Bertalanffy, in West African Dwarf (WAD) sheep. A total of 5274 monthly weight records from birth up to 180 days of age from 889 lambs, collected during 2001 to 2004 in Betecoucou breeding farm in Benin were used. In the preliminary analysis, the General Linear Model Procedure of the Statistical Analysis Systems Institute was applied to the dataset to identify the significant effects of the sex of lamb (male and female), type of birth (single and twin), season of birth (rainy season and dry season), parity of dam (1, 2 and 3) and year of birth (2001, 2002, 2003 and 2004) on the observed birth weight and monthly weight up to 6 months of age. The models parameters (A, B and k), coefficient of determination (R2), mean square error (MSE) were calculated using language of technical computing package Matlab􏰀 R , 2006. The mean values of A, B and k were substituted into each model to calculate the corresponding Akaike’s Information Criterion (AIC). Among the four growth functions, the Brody model has been selected for its accuracy of fit according to the higher R2, lower MSE and AIC. Finally, the parameters A, B and k were adjusted in Matlab􏰀 R , 2006 for the sex of lamb, year of birth, season of birth, birth type and the parity of ewe, providing a specific slope of the Brody growth curve. The results of this study suggest that Brody model can be useful for WAD sheep breeding in Betecoucou farm conditions through growth monitoring. [less ▲]

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See detailComparison of O2 IR and NO UV night airglow variations on Mars and Venus
Brecht; Bougher, S. W.; Gérard, Jean-Claude ULg et al

Conference (2009, May)

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See detailComparison of output-only methods for condition monitoring of industrials systems
Rutten, Christophe ULg; Nguyen, Viet Ha; Golinval, Jean-Claude ULg

in Journal of Physics: Conference Series (2011), 305

In the field of structural health monitoring or machine condition monitoring, the activation of nonlinear dynamic behavior complicates the procedure of damage or fault detection. Blind source separation ... [more ▼]

In the field of structural health monitoring or machine condition monitoring, the activation of nonlinear dynamic behavior complicates the procedure of damage or fault detection. Blind source separation (BSS) techniques are known as efficient methods for damage diagnosis. However, most of BSS techniques repose on the assumption of the linearity of the system and the need of many sensors. This article presents some possible extensions of those techniques that may improve the damage detection, e.g. Enhanced-Principal Component Analysis (EPCA), Kernel PCA (KPCA) and Blind Modal Identification (BMID). The advantages of EPCA rely on its rapidity of use and its reliability. The KPCA method, through the use of nonlinear kernel functions, allows to introduce nonlinear dependences between variables. BMID is adequate to identify and to detect damage for generally damped systems. In this paper, damage is firstly examined by Stochastic Subspace Identification (SSI); then the detection is achieved by comparing subspace features between the reference and a current state through statistics and the concept of subspace angle. Industrial data are used as illustration of the methods. [less ▲]

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See detailComparison of ozone-induced effects on lung mechanics and hemodynamics in the rabbit.
Delaunois, Annie ULg; Segura, P.; Montano, L. M. et al

in Toxicology and Applied Pharmacology (1998), 150(1), 58-67

The effects of rabbit exposure to ozone (O3)(0.4 ppm for 4 h) on pulmonary mechanical properties and hemodynamics have been investigated on the isolated perfused lung model. Tracheal pressure, airflow ... [more ▼]

The effects of rabbit exposure to ozone (O3)(0.4 ppm for 4 h) on pulmonary mechanical properties and hemodynamics have been investigated on the isolated perfused lung model. Tracheal pressure, airflow, and tidal volume were measured in order to calculate lung resistance (RL) and dynamic compliance (Cdyn). Using the arterial/venous/double occlusion method, the total pressure gradient (deltaPT) was partitioned into four components (arterial, pre-, postcapillary and venous). Dose-response curves to acetylcholine (ACh), substance P (SP), and histamine were constructed in lungs isolated from rabbits immediately or 48 h after air or O3 exposure O3 induced a significant increase in the baseline value of deltaPt, more markedly 48 h after the exposure. Immediately after the exposure, O3 partly inhibited the ACh-, SP-, and histamine-induced decreases in Cdyn and increases in RL. This inhibitory effect was still in part present 48 h after O3 treatment. In the groups studied immediately after exposure, O3 did not significantly modify the ACh-, SP-, and histamine-induced vasoconstriction. Forty-eight hours after exposure, O3 induced a contractile response to ACh and SP in the arterial segment but decreased the response to histamine. We conclude that O3 can induce direct vascular constriction. Directly, but also 48 h after exposure, O3 can inhibit the ACh-, SP-, and histamine-induced changes in lung mechanical properties. Ozone can also induce some changes in the intensity and in the location of the vascular responses to ACh, SP, and histamine. [less ▲]

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See detailComparison of parameterization schemes for solving the discrete material optimization problem of composite structures
Duysinx, Pierre ULg; Guillermo Alonso, Maria ULg; Gao, Tong et al

Conference (2013, September)

In the context of weight reduction challenges in aerospace, automotive, and energy engineering problems, composite materials are gaining a revived interested. Because of the problem complexity and the ... [more ▼]

In the context of weight reduction challenges in aerospace, automotive, and energy engineering problems, composite materials are gaining a revived interested. Because of the problem complexity and the large number of design variables, their design of composite structures is greatly facilitated by using optimization techniques. While several formulations have been proposed for composite structure design, Stegmann and Lund [1] have showed that composite optimization can take advantage of the topology optimization approach. The fundamental idea of the Discrete Material Optimization (DMO) approach is 1/ to formulate the composite optimization problem as an optimal material selection problem in which the different laminates and ply orientations are considered as different materials and 2/ to solve the optimization problem using continuous existence variables. To transform the discrete problem into a continuous one, one introduces a suitable parametrization identifying each material by a unique set of design variables while the material properties are expressed as a weighted sum of all candidate materials. Using DMO approach, one can solve within a common approach, different design problems such as laminate distribution problem, stacking sequence optimization... The inherent difficulties of the discrete material selection using topology optimization are 1/ to find efficiency interpolation and penalization schemes of the material properties and 2/ to be able to tailor an efficient solution algorithm to handle very large scale optimization problems. Besides the reference DMO scheme by Lund and his co-authors, other interpolation schemes have been proposed: In this paper, work we are considering and comparing DMO with two other schemes namely the Shape Function with Penalization Parameterization (SFP) by Bruyneel [2] and it recent extension, the Bi-value Coding Parametrization (BCP) by Gao et al. [3]. In particular, the work considers the different schemes in the perspective of solving large-scale industrial applications. The work considers several aspects of the different schemes: • Nature of the different interpolation schemes, • Penalization strategies (power law (SIMP), RAMP, Tsai-Halpin or polynomial), • Number of design variables, the size and complexity of the optimization problem, • Sensitivity to local optima, to the initial design variable, and the development of continuous penalization techniques, • Ability to be extended to various formulations from compliance problems to local restrictions and buckling. As a major drawback, DMO, SFP and BCP approaches increase dramatically the number of design variables. Because of the computational burden to solve the optimization problems, in most of DMO implementations, the considered structural responses are generally limited to compliance-like objective functions. In order to extend the DMO formulation, the work investigates the selection of the most appropriate and efficient optimization algorithms to handle the problems. Different schemes of the sequential convex programming are compared. At first the classic schemes MMA and CONLIN are tested. Then more advanced schemes of the MMA family (Bruyneel et al. [4]) are experimented. The work and the comparisons are carried out on several numerical applications related to the selection of optimal local fibre orientations (with up to 36 candidate material orientations) in membrane and shell aerospace or automotive structures. The various numerical test problems include academic examples and benchmarks inspired by industrial applications. [less ▲]

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See detailComparison of parameterization schemes for solving the discrete material optimization problem of composite structures
Duysinx, Pierre ULg; Guillermo Alonso, Maria ULg; Tong, Gao et al

in Halftka, Raphael; KIM, Nam Ho (Eds.) Proceeding of the 10th World Congress on Structural And Multidisciplinary Optimization (2013, May 19)

Optimal design of composite structures can be formulated as an optimal selection of material in a list of different laminates. Based on the seminal work by Stegmann and Lund, the optimal problem can be ... [more ▼]

Optimal design of composite structures can be formulated as an optimal selection of material in a list of different laminates. Based on the seminal work by Stegmann and Lund, the optimal problem can be stated as a topology optimization problem with multiple materials. The research work carries out a large investigation of different interpolation and penalization schemes for the optimal material selection problem. Besides the classical Design Material Optimization (DMO) scheme and the recent Shape Function with Penalization (SFP) scheme by Bruyneel, the research introduces a generalization of the SFP approach using a bi-value coding parameterization (BCP) by Gao, Zhang and Duysinx. The paper provides a comparison of the different parameterization approaches. It also proposes alternative penalization schemes and it investigates the effect of the power penalization. Finally, we discuss the solution aspects in the perspective of solving large-scale industrial applications. The conclusions are illustrated by a numerical application for the compliance maximization of an in-plane composite ply. [less ▲]

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See detailA comparison of parametric and non-parametric distance functions: with application to European Railways
Coelli, Tim; Perelman, Sergio ULg

in European Journal of Operational Research (1999), (117), 326-339

In this paper we use multi-output distance functions to investigate technical inefficiency in European railways. The principle aim of the paper is to compare the results obtained from the three ... [more ▼]

In this paper we use multi-output distance functions to investigate technical inefficiency in European railways. The principle aim of the paper is to compare the results obtained from the three alternative methods of estimating multioutput distance functions. Namely, the construction of a parametric frontier using linear programming; data envelopment analysis (DEA) and corrected ordinary least squares (COLS). Input-orientated, output-orientated and constant returns to scale (CRS) distance functions are estimated and compared. The results indicate a strong degree of correlation between the input- and output-orientated results for each of the three methods. There are also significant correlations observed between the results obtained using the alternative estimation methods. The strongest correlations being between the parametric linear programming and the COLS methods. Finally, the paper concludes with the suggestion that a combination of the technical efficiency scores, obtained from the three different methods, be used as the preferred set of scores. This idea is borrowed from the time-series forecasting literature. [less ▲]

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See detailComparison of parametric excitation and excitation of an elastic stay cable
Denoël, Vincent ULg; Degée, Hervé ULg

in Proceedings of the 7th European Conference on Structural Dynamics (2008)

In cable-stayed bridge applications, the vertical vibrations of a bridge deck induce vertical motions of the cable anchors that may cause large amplitudes oscillations of the cables. This vertical motion ... [more ▼]

In cable-stayed bridge applications, the vertical vibrations of a bridge deck induce vertical motions of the cable anchors that may cause large amplitudes oscillations of the cables. This vertical motion is not collinear with the cable chord and can be split into a transverse and an axial component. The latter one is responsible for a parametric excitation. Since this phenomenon leads to serious dynamic instability, whereas the transverse component provides simple resonances only, the transverse anchor motion is often disregarded or considered in a separate analysis. However, because of the cable’s non linear behaviour, the response of the cable under both components cannot simply be added. It is thus important to consider at once this actual “cable excitation”, rather than approaching it by an axial excitation, as often reported in the study of parametric excitations. In this paper, the difference between the two modes of excitation is illustrated with a finite element model. The simplicity of the model allows an efficient parametric study of the vibrations of a cable under both excitations, for various cable inclinations and anchor frequencies. [less ▲]

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See detailComparison of participants and non-participants to the ORISCAV-LUX population-based study on cardiovascular risk factors in Luxembourg
Alkerwi, A; Sauvageot, N; Couffignal, S et al

in Atherosclerosis. Supplements (2009), 204(2), 624-635

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See detailComparison of participants and non-participants to the ORISCAV-LUX population-based study on cardiovascular risk factors in Luxembourg.
Alkerwi, Ala'a; Sauvageot, Nicolas; Couffignal, Sophie et al

in BMC Medical Research Methodology (2010), 10

BACKGROUND: Poor response is a major concern in public health surveys. In a population-based ORISCAV-LUX study carried out in Grand-Duchy of Luxembourg to assess the cardiovascular risk factors, the non ... [more ▼]

BACKGROUND: Poor response is a major concern in public health surveys. In a population-based ORISCAV-LUX study carried out in Grand-Duchy of Luxembourg to assess the cardiovascular risk factors, the non-response rate was not negligible. The aims of the present work were: 1) to investigate the representativeness of study sample to the general population, and 2) to compare the known demographic and cardiovascular health-related profiles of participants and non-participants. METHODS: For sample representativeness, the participants were compared to the source population according to stratification criteria (age, sex and district of residence). Based on complementary information from the "medical administrative database", further analysis was carried out to assess whether the health status affected the response rate. Several demographic and morbidity indicators were used in the univariate comparison between participants and non-participants. RESULTS: Among the 4452 potentially eligible subjects contacted for the study, there were finally 1432 (32.2%) participants. Compared to the source population, no differences were found for gender and district distribution. By contrast, the youngest age group was under-represented while adults and elderly were over-represented in the sample, for both genders. Globally, the investigated clinical profile of the non-participants was similar to that of participants. Hospital admission and cardiovascular health-related medical measures were comparable in both groups even after controlling for age. The participation rate was lower in Portuguese residents as compared to Luxembourgish (OR = 0.58, 95% CI: 0.48-0.69). It was also significantly associated with the professional status (P < 0.0001). Subjects from the working class were less receptive to the study than those from other professional categories. CONCLUSION: The 32.2% participation rate obtained in the ORISCAV-LUX survey represents the realistic achievable rate for this type of multiple-stage, nationwide, population-based surveys. It corresponds to the expected rate upon which the sample size was calculated. Given the absence of discriminating health profiles between participants and non-participants, it can be concluded that the response rate does not invalidate the results and allows generalizing the findings for the population. [less ▲]

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See detailComparison of patient's voice quality for T1A glottis carcinoma after endoscopic laser surgery or radiotherapy
Poncelet, Mélanie; DEMEZ, Pierre ULg; Moreau, Pierre ULg et al

Conference (2014, July 30)

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See detailComparison of PCDD/Fs and cPCBs levels in commercial pasteurized cow's milk in Wallonia (Belgium)
Focant, Jean-François ULg; Pirard, C.; Andre, J.-E. et al

in Organohalogen Compounds (2001), 51

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See detailComparison of performance, water intake and feeding behaviour of weaned pigs fed either pellets or meal
Laitat, Martine ULg; Vandenheede, Marc ULg; Desiron, Alain et al

in Animal Science (1999), 69

Performance, water intake and feeding behaviour of two groups of 30 (trial 1), 40 (trial 2) or 50 (trial 3) weaned pigs offered either pellets ol meal of the same formulation were compared. Average daily ... [more ▼]

Performance, water intake and feeding behaviour of two groups of 30 (trial 1), 40 (trial 2) or 50 (trial 3) weaned pigs offered either pellets ol meal of the same formulation were compared. Average daily weight gains (ADG) were higher for pigs given pellets rather than meal in trials 2 (413 v. 363 g/day P < 0.001) and 3 (356 v. 324 g/day, P < 0.05). Mean daily water intake (DWI) was higher with meal than with pellets but only during trial 1 (2.31 y. 1.65 l/day, P < 0.01). The occupation time (OT) and the number of animals using the feeder simultaneously (N) were higher when pigs were given meal rather than pellets, whatever the animal density: trial 1: 82.6 v. 69.9% (P = 0.05) and 3.8 v. 2.3 (P < 0.01); trial 2: 90.9 v. 77.9% (P > 0.05) and 5.2 v. 3.1 (P < 0.01); trial 3: 96.2 v. 83.6% (P < 0.05) and 5.9 v. 3.8 (P < 0.01). When using pellets, OT and N were always significantly lower during the night than during the day but when using meal in groups of 40 and 50, OT during the night was almost as high as during the day. The greater the group size, the lower were ADG (both diets) and DWI (only with meal) and the higher were OT and N (both diets). Furthermore, significant linens and curvilinear regressions of DWI, OT and N according to time were calculated. In conclusion, pigs need more time to eat meal than to eat pellets. Thus the number of pigs per feeder has to be adapted to the food presentation. Too high number of pigs per feeder impairs feeding behaviour and eventually welfare, by preventing preferential diurnal feeding activity and this may affect productivity [less ▲]

Detailed reference viewed: 72 (0 ULg)