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See detailComparison of IUE and HST diagnostic of the Jovian aurorae
Thomas, Alexandre ULg; Prangé; Ballester, G. E. et al

in Bulletin of the American Astronomical Society (1994, June 01)

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See detailComparison Of Jupiter's Infrared And Uv Aurorae With Simultaneous And Near-simultaneous HST And Ground-based Observations
Lystrup, Makenzie B; Radioti, Aikaterini ULg; Bonfond, Bertrand ULg et al

Conference (2010, October)

Jupiter's UV aurorae have been observed extensively for the last twenty years using the Hubble Space Telescope and the infrared aurorae have been investigated using ground-based telescope observations ... [more ▼]

Jupiter's UV aurorae have been observed extensively for the last twenty years using the Hubble Space Telescope and the infrared aurorae have been investigated using ground-based telescope observations. The two wavelength regimes complement each other; the UV is a tracer of inputs from the magnetosphere while the infrared emissions from the H3+ molecular ion show how the ionosphere responds to those inputs. Between 1995 and 2000 Spectroscopic, J.E.P Connerney & T. Satoh carried out observations with the NSFCAM imaging instrument at the NASA Infrared Telescope Facility. Results from this data set have been published, although the entire data set has not been examined and there has been only limited comparison with the UV. We reanalyze this data set in order to statistically characterize the infrared aurora and compare with the UV. Here we present a detailed study of simultaneous and near-simultaneous observations of the UV (STIS instrument on HST) and infrared northern aurorae made on July 26, 1998 and December 16, 2000. The comparative study addresses the main oval emissions, satellite footprints, and polar aurorae. M. Lystrup is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-0802021. [less ▲]

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See detailComparison of Kohonen's Self-Organizing Map algorithm and principal component analysis in the exploratory data analysis of a groundwater quality dataset
Peeters, Luk; Dassargues, Alain ULg

(2006)

Groundwater monitoring networks typically yield large, multivariate datasets. Analysis and interpretation of these datasets starts with an exploratory data analysis in order to summarize the available ... [more ▼]

Groundwater monitoring networks typically yield large, multivariate datasets. Analysis and interpretation of these datasets starts with an exploratory data analysis in order to summarize the available data, extract useful information and formulate hypotheses for further research. Exploratory data analysis is mostly focussed on finding related variables and groupings of similar observations. Traditionally multivariate statistical techniques like principal component analysis (PCA) are used for this purpose. In PCA a linear dimensionality reduction of the original, high dimensional dataset is carried out in order to identify orthogonal directions (principal components) of maximum variance in the dataset based on linear combinations of correlated variables. Projections of the original data in the subspace defined by the principal components can be used to identify groups in the data and to reveal relationships between variables (Davis, 1986). In this study, principal component analysis is compared to Kohonen's self-organizing map (SOM) algorithm. The SOM-algorithm is an artificial neural network technique designed to carry out a non-parametric regression process that is mainly used to represent high-dimensional, nonlinearly related data items in a topology-preserving, often two-dimensional display, and to perform unsupervised classification and clustering (Kohonen, 1995). Both PCA and SOM are applied to a hydrochemical dataset from a monitoring network in two sandy, phreatic aquifers in Central Belgium. The monitoring network consists of 47 monitoring wells each equipped with three filters at different depths, in which 14 variables are measured. The first aquifer, the Diest sands aquifer is of Late Miocene age and consists of coarse, glauconiferous sands and sandstones (Laga et al., 2001). The second aquifer, the Brussels sands aquifer, is of Middle Eocene age and is an heterogeneous formation consisting of an alteration of highly and poorly calcareous sands, locally silicified (Laga et al., 2001). Both techniques succeed in distinguishing between both aquifers and reveal the relationships between variables. The main advantage of PCA is the mathematical quantification of correlation between variables and the expression of the original data in the subspace defined by the principal components. The visualization of the SOM-analysis on the other hand allows a straightforward interpretation of the dataset structure in which even non-linear relationships between variables can be identified. Additionally, the SOM-algorithm can handle a limited amount of missing values in the dataset, contrary to PCA. [less ▲]

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See detailComparison of learning curves and skill transfer between classical and robotic laparoscopy according to the viewing conditions: implications for training
Blavier, Adelaïde ULg; Gaudissart, Quentin; Cadière, Guy-Bernard et al

in American Journal of Surgery (2007), 194(1), 115-121

BACKGROUND: The purpose of this study was to evaluate the perceptual (2-dimensional [2D] vs. 3-dimensional [3D] view) and instrumental (classical vs. robotic) impacts of new robotic system on learning ... [more ▼]

BACKGROUND: The purpose of this study was to evaluate the perceptual (2-dimensional [2D] vs. 3-dimensional [3D] view) and instrumental (classical vs. robotic) impacts of new robotic system on learning curves. METHODS: Forty medical students without any surgical experience were randomized into 4 groups (classical laparoscopy with 3D-direct view or with 2D-indirect view, robotic system in 3D or in 2D) and repeated a laparoscopic task 6 times. After these 6 repetitions, they performed 2 trials with the same technique but in the other viewing condition (perceptive switch). Finally, subjects performed the last 3 trials with the technique they never used (technical switch). Subjects evaluated their performance answering a questionnaire (impressions of mastery, familiarity, satisfaction, self-confidence, and difficulty). RESULTS: Our study showed better performance and improvement in 3D view than in 2D view whatever the instrumental aspect. Participants reported less mastery, familiarity, and self-confidence and more difficulty in classical laparoscopy with 2D-indirect view than in the other conditions. CONCLUSIONS: Robotic surgery improves surgical performance and learning, particularly by 3D view advantage. However, perceptive and technical switches emphasize the need to adapt and pursue training also with traditional technology to prevent risks in conversion procedure. [less ▲]

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See detailComparison of less lethal 40 mm sponge projectile and the 37 mm projectile for injury assessment on human thorax
Nsiampa Ndompetelo, ULg; Robbe, Cyril ULg

in 10th International Conference on the mechanical and physical behaviour of materials under dynamic loading, Freiburg 2-7 September 2012 (2012)

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See detailComparison of levels of cytosol estrogen receptors with "arterial" and "venous" concentrations of gonadic steroids in mammary tumors.
Duvivier, Joseph; Colin, Claude; Hustin, Jean et al

in Clinica Chimica Acta (1981), 112(1), 21-32

Plasma steroid concentrations measured in the post-menopausal women with breast cancer showed a close correlation between the various androgens. The post-menopausal women exhibited a correlation between ... [more ▼]

Plasma steroid concentrations measured in the post-menopausal women with breast cancer showed a close correlation between the various androgens. The post-menopausal women exhibited a correlation between estrogen receptors (ER) and "arterial" 17 alpha-hydroxyprogesterone levels in the breast. ER levels expressed as a function of plasma (arterial) steroid (P/17 P) molar concentration ratio were distributed within a hyperbola, suggesting the existence of a control mechanism for breast cell ER levels. [less ▲]

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See detailComparison of liaison N-tact PTH (diasorin) and N-tact PTH SPIRMA (diasorin) in hemodialyzed patients
Cavalier, Etienne ULg; Delanaye, Pierre ULg; Krzesinski, Jean-Marie ULg et al

in Clinical Chemistry & Laboratory Medicine (2005), 43(8), 890-891

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See detailComparison of linkage and association strategies for quantitative traits using the COGA dataset
McQueen, M. B.; Murphy, A.; Kraft, P. et al

in Genetic Epidemiology. Supplement (2005), 29(Suppl I), 1-9

Genome scans using dense single-nucleotide polymorphism ( SNP) data have recently become a reality. It is thought that the increase in information content for linkage analysis as a result of the denser ... [more ▼]

Genome scans using dense single-nucleotide polymorphism ( SNP) data have recently become a reality. It is thought that the increase in information content for linkage analysis as a result of the denser scans will help refine previously identified linkage regions and possibly identify new regions not identifiable using the sparser, microsatellite scans. In the context of the dense SNP scans, it is also possible to consider association strategies to provide even more information about potential regions of interest. To circumvent the multiple-testing issues inherent in association analysis, we use a recently developed strategy, implemented in PBAT, which screens the data to identify the optimal SNPs for testing, without biasing the nominal significance level. We compare the results from the PBAT analysis to that of quantitative linkage analysis on chromosome 4 using the Collaborative Study on the Genetics of Alcoholism data, as released through Genetic Analysis Workshop 14. [less ▲]

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See detailComparison of linkage and association strategies for quantitative traits using the COGA dataset.
McQueen, M. B.; Murphy, A.; Kraft, P. et al

in BMC Genetics (2005), 6 Suppl 1

ABSTRACT : Genome scans using dense single-nucleotide polymorphism (SNP) data have recently become a reality. It is thought that the increase in information content for linkage analysis as a result of the ... [more ▼]

ABSTRACT : Genome scans using dense single-nucleotide polymorphism (SNP) data have recently become a reality. It is thought that the increase in information content for linkage analysis as a result of the denser scans will help refine previously identified linkage regions and possibly identify new regions not identifiable using the sparser, microsatellite scans. In the context of the dense SNP scans, it is also possible to consider association strategies to provide even more information about potential regions of interest. To circumvent the multiple-testing issues inherent in association analysis, we use a recently developed strategy, implemented in PBAT, which screens the data to identify the optimal SNPs for testing, without biasing the nominal significance level. We compare the results from the PBAT analysis to that of quantitative linkage analysis on chromosome 4 using the Collaborative Study on the Genetics of Alcoholism data, as released through Genetic Analysis Workshop 14. [less ▲]

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See detailComparison of Lohmann white and Lohmann brown strains in embryo physiology
Tona, K.; Agbo, K.; Kamers, B. et al

in International Journal of Poultry Science (2010), 9(9), 907-910

Chicken post-hatch performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters have received little ... [more ▼]

Chicken post-hatch performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters have received little attention. A total of 1,200 hatching eggs produced by Lohmann Brown (LB) and Lohman White (LW) breeders of the same age were studied. Between 62 and 150 h of incubation, eggs Resonance Frequency (RF) was measured as indicator of early embryonic development. Also, albumen pH was measured between setting and d 8 of incubation. From d 10 to 18 of incubation, remaining albumen and embryos were weighed. During the last days of incubation, hatching occurrences were monitored after every four hours and hatched chicks were recorded. Results indicate that RF of LWeggs were lower than that of LB eggs (p<0.01) and starting time point of RF decrease occurred earlier in LB eggs than in LW eggs. Albumen pH of LB eggs was lower than that of LW eggs at day 8 of incubation. Remaining albumen weight at 14 and 16 d of incubation was lower in LB than in LW (p<0.05) while embryo weights increased more rapidly in LB strain than in LW strain. It is concluded that LB and LW embryos have different growth trajectories and should be incubated at different conditions. © Asian Network for Scientific Information, 2010. [less ▲]

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See detailComparison of Machine Learning techniques for atmospheric pollutant monitoring in a Kraft pulp mill
Sainlez, Matthieu ULg; Heyen, Georges ULg

Conference (2011, November)

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data ... [more ▼]

In this paper, machine learning techniques are compared to predict nitrogen oxide (NOx) pollutant emission from the recovery boiler of a Kraft pulp mill. Starting from a large database of raw process data related to a Kraft recovery boiler, we consider a regression problem in which we are trying to predict the value of a continuous variable. Generalization is done on the worst case configuration possible to make sure the model is adequate: the training period concerns stationary operations while test periods mainly focus on NOx emissions during transient operations. This comparison involves neural network techniques (i.e., static multilayer perceptron and dynamic NARX network), tree-based methods and multiple linear regression. We illustrate the potential of a dynamic neural approach compared to the others in this prediction task. [less ▲]

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See detailComparison of magnetotail magnetic flux estimates based on global auroral images and simultaneous solar wind—magnetotail measurements
Shukhtina, M. A.; Sergeev, V. A.; Dejong, A. D. et al

in Journal of Atmospheric & Solar-Terrestrial Physics (2010), 72

We compared simultaneous magnetotail magnetic flux F estimates, (1) based on in situ spacecraft measurements in the tail and solar wind (F[SUB]T[/SUB]) with (2) the polar cap magnetic flux, estimated from ... [more ▼]

We compared simultaneous magnetotail magnetic flux F estimates, (1) based on in situ spacecraft measurements in the tail and solar wind (F[SUB]T[/SUB]) with (2) the polar cap magnetic flux, estimated from global auroral images (using proton-induced or electron-induced emissions, F[SUB]p[/SUB] or F[SUB]e[/SUB], respectively). Simultaneous F[SUB]p[/SUB] and F[SUB]e[/SUB] estimates gave the correlation coefficient CC=0.74, indicating that these measures are not absolutely precise. Regression analysis of F[SUB]T[/SUB] versus F[SUB]e[/SUB] and F[SUB]p[/SUB] gave CC values 0.73 and 0.50, correspondingly. F[SUB]T[/SUB] values, containing closed magnetic flux, are systematically higher than F[SUB]p[/SUB] and F[SUB]e[/SUB] by 20-30%. Motivated by diverse results, published by different groups, we reanalyzed the F dependence on the dayside merging electric field E[SUB]m[/SUB] for different dynamical states. The linear regression F(E[SUB]m[/SUB]) for substorm onsets shows a large slope ˜0.07-0.12GWb/(mV/m) for all F[SUB]p[/SUB], F[SUB]e[/SUB] and F[SUB]T[/SUB], confirming the loading-unloading substorm scheme. For SMC intervals this slope is only 0.03 GWb/(mV/m). [less ▲]

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See detailComparison of marketing strategies of retailers of organic beef
Aertsens, Joris; Stassart, Pierre M ULg; Jamar, D. et al

in Quality Management and Quality Assurance in Food Chains (2005)

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See detailComparison of mechanical efficiency of two microstructures of Ti5553 alloy in the case of bolted flanges submitted to tensile loading
Van Hoof, T.; Ben Bettaieb, Mohamed ULg; Lani, F. et al

in Steel Research International (2010), 81(9), 1148-1152

A combination of numerical and experimental methods is used to compare the efficiency of two microstructures of Ti5553 titanium alloy in an industrial test case. The test case consists in two parts of ... [more ▼]

A combination of numerical and experimental methods is used to compare the efficiency of two microstructures of Ti5553 titanium alloy in an industrial test case. The test case consists in two parts of sectors of aircraft engine stators linked together by an Inconel bolt and submitted to tensile loading. The efficiency of these microstructures is evaluated by using finite element (FE) models. The chosen FE models take into account elasto-visco-plastic material behaviors, contact with friction (bolt heads/flanges and flange/flange), and the initial bolt tightening. The parameters of the elasto-visco-plastic (EVP) material law are adjusted from experimental results extracted from tensile tests performed on Inconel, and Ti5553 alloys. Viscous properties are observed at different strain rates. The studied alloy is assumed to be plastically isotropic. In order to compare the fracture resistance of both microstructures, a micro-mechanical (damage based) rupture model ([4]) is used as a FE post-processing step. [less ▲]

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See detailComparison of mesozooplankton faecal pellet characteristics from the Southern North Sea and the Mediterranean Sea during spring bloom conditions
Frangoulis, Constantin; Hecq, Jean-Henri ULg

in Gislason, Astthor; Gorsky, Gabriel (Eds.) Proceedings of the « Joint ICES / CIESM Workshop to Compare Zooplankton Ecology and Methodologies between the Mediterranean and the North Atlantic (WKZEM) » (2010, February)

Mesozooplankton faecal pellets participate in the carbon and nutrient cycles, in the nutrition of marine organisms, and in the transport of toxins, pollutants, and sediments. The importance of this role ... [more ▼]

Mesozooplankton faecal pellets participate in the carbon and nutrient cycles, in the nutrition of marine organisms, and in the transport of toxins, pollutants, and sediments. The importance of this role depends on their nature and production, which are highly variable parameters that, in turn, depend on many factors. For example, a phytoplankton bloom may significantly change the nature of mesozooplankton faecal pellets because it affects their shape, content, density, and volume. The aim of the present study is to compare the eutrophic Southern North Sea and the oligotrophic Bay of Calvi in the Meditenanean Sea with respect to the seasonal variability of faecal pellet characteristics (shape, size, sinking speed, density) during bloom conditions. [less ▲]

Detailed reference viewed: 21 (2 ULg)