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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 local outliers detection techniques in spatial multivariate data
Ernst, Marie ULg; Haesbroeck, Gentiane ULg

in Data Mining & Knowledge Discovery (2017), 31(2), 371399

Outlier detection techniques in spatial data should allow to identify two types of outliers: global and local ones. Local outliers typically have non-spatial attributes that strongly differ from those ... [more ▼]

Outlier detection techniques in spatial data should allow to identify two types of outliers: global and local ones. Local outliers typically have non-spatial attributes that strongly differ from those observed on their neighbors. Detecting local outliers requires to be able to work locally, on neighborhoods, in order to take into account the spatial dependence between the statistical units under consideration, even though the outlyingness is usually measured on the non-spatial variables. Many procedures have been outlined in the literature, but their number reduces when one wants to deal with multivariate non-spatial attributes. In this paper, focus is on the multivariate context. A review of existing procedures is done. A new approach, based on a two-step improvement of an existing one, is also designed and compared with the benchmarked methods by means of examples and simulations. [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 detailA comparison of measurements from ATMOS and instruments aboard the ER-2 aircraft: Halogenated gases
Chang, A. Y.; Salawitch, R. J.; Michelsen, H. A. et al

in Geophysical Research Letters (1996), 23(17), 2393--2396

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See detailA comparison of measurements from ATMOS and instruments aboard the ER-2 aircraft: Tracers of atmospheric transport
Chang, A. Y.; Salawitch, R. J.; Michelsen, H. A. et al

in Geophysical Research Letters (1996), 23(17), 2389--2392

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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 detailA comparison of medetomidine and its active enantiomer dexmedetomidine when administered with ketamine in mice
Burnside, Wesley; Flecknell, Paul; Cameron, Angus et al

in BMC Veterinary Research (2013), 9(48),

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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 ▲]

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See detailA Comparison of Methods for Photospheric Abundance Determinations in K-Type Stars
Affer, L.; Micela, G.; Morel, Thierry ULg et al

in Chemical Abundances and Mixing in Stars in the Milky Way and its Satellites, ESO ASTROPHYSICS SYMPOSIA. ISBN 978-3-540-34135-2. Springer-Verlag, 2006, p. 31 (2006)

We have performed a detailed abundance analysis of six inactive K-type stars using high-resolution optical spectra. We have used three different techniques and compared the results obtained in order to ... [more ▼]

We have performed a detailed abundance analysis of six inactive K-type stars using high-resolution optical spectra. We have used three different techniques and compared the results obtained in order to establish their respective merits and faults. The two spectroscopic methods give consistent results suggesting that non- LTE effects are small, whereas the â mixedâ spectroscopic-photometric method leads to photospheric parameters and abundances systematically lower than those obtained with the other two. We have also determined the starsâ positions in H-R diagrams and made a comparison between the gravities derived from the ionization equilibrium of the iron lines and from the evolutionary tracks: the agreement is reasonably good. [less ▲]

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See detailComparison of methods for quantifying active layer dynamics and bedload discharge in armoured gravel-bed rivers
Houbrechts, Geoffrey ULg; Van Campenhout, Jean ULg; Levecq, Yannick ULg et al

in Earth Surface Processes & Landforms (2012), 37

Several methods were employed in the Ardennian rivers (Belgium) to determine the depth of the active layer mobilized during floods and to evaluate the bedload discharge associated with these events. The ... [more ▼]

Several methods were employed in the Ardennian rivers (Belgium) to determine the depth of the active layer mobilized during floods and to evaluate the bedload discharge associated with these events. The use of scour chains has shown that the depth of the active layer is systematically less than the b-axis of the average particle size (D50) of the elements which compose the surface layer of the riffles. This indicates that only a partial transport exists during low magnitude floods. The bedload discharge has been evaluated by combining data obtained using the scour chains technique and the distance covered by tracers. Quantities of sediment transported during frequent floods are relatively low (0 02 t km–2) due to the armour layer which protects the subsurface material. These low values are also related to the fact that the distance calculated for mobilized bedload only applies to tracers fitted with PIT (passive integrated transponder)-tags (diameter>20 mm), whereas part of the bedload discharge is composed of sand and fine gravel transported over greater distances than the pebbles. The break-up of the armour layer was observed only once, for a decennial discharge. During this event, the bedload discharge increased considerably (2 t km–2). The use of sediment traps, data from dredging and a Helley–Smith sampler confirm the low bedload transport in Ardennian rivers in comparison to the bedload transport in other geomorphological contexts. This difference is explained by the presence of an armoured layer but also by the imbricated structures of flat bed elements which increase the resistance to the flow. Finally, the use of the old iron industry wastes allowed to quantify the thickness of the bed reworked over the past centuries. In the Lembrée River, the river-bed contains slag elements up to a depth of about 50 cm, indicating that exceptional floods may rework the bed to a considerable depth. [less ▲]

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See detailComparison of methods for the detection and extrapolation of trends in groundwater quality
Visser, Ate; Dubus, Igor; Broers, Hans Peter et al

in Journal of Environmental Monitoring (2009)

Land use changes and the intensification of agriculture since the 1950s have resulted in a deterioration of groundwater quality in many European countries. For the protection of groundwater quality, it is ... [more ▼]

Land use changes and the intensification of agriculture since the 1950s have resulted in a deterioration of groundwater quality in many European countries. For the protection of groundwater quality, it is necessary to (1) assess the current groundwater quality status, (2) detect changes or trends in groundwater quality, (3) assess the threat of deterioration and (4) predict future changes in groundwater quality. A variety of approaches and tools can be used to detect and extrapolate trends in groundwater quality, ranging from simple linear statistics to distributed 3D groundwater contaminant transport models. In this paper we report on a comparison of four methods for the detection and extrapolation of trends in groundwater quality: (1) statistical methods, (2) groundwater dating, (3) transfer functions, and (4) deterministic modeling. Our work shows that the selection of the method should firstly be made on the basis of the specific goals of the study (only trend detection or also extrapolation), the system under study, and the available resources. For trend detection in groundwater quality in relation to diffuse agricultural contamination, a very important aspect is whether the nature of the monitoring network and groundwater body allows the collection of samples with a distinct age or produces samples with a mixture of young and old groundwater. We conclude that there is no single optimal method to detect trends in groundwater quality across widely differing catchments. [less ▲]

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See detailComparison of Micro-objective Nonparametric Statistical Matching Techniques for Integration of Different Survey Data
Eftekhar, Hamed ULg; Cools, Mario ULg

in The Transportation Research Board (TRB) 96th Annual Meeting (2017, January 11)

Lack of information is often reported as one of the main study limitations in transport research. Other data sources provide an important opportunity, as the information from these data sources might be ... [more ▼]

Lack of information is often reported as one of the main study limitations in transport research. Other data sources provide an important opportunity, as the information from these data sources might be fully exploited when they are integrated using an appropriate mathematical framework. This paper determines which data integration techniques can be adopted in the context of road safety, and which criteria should be used to assess the quality of the integrated dataset. The paper contributes to the literature by providing a comparison of different techniques that allow the tabulation of the joint micro-data. To compare the suitability of different Statistical Matching techniques, data from the 2012 Belgium Road Safety Institute (BRSI) Attitude Survey and data from the 2010 Belgian National Household Travel Survey (BELDAM) are integrated. In particular, the socio-economic factor "Income" is being matched to the BRSI Attitude Survey data. The paper discusses and compares different non-parametric micro-objective Statistical Matching techniques, in which the “Income” variable from the BELDAM survey was added to the BRSI Attitude Survey. Based on similarity/dissimilarity measures, the Rank hot-deck Statistical Matching yielded the best result, which is in line with the existing literature. Moreover, from the results, it can be concluded that statistical data matching is a practically applicable technique, which can help overcome the lack of additional information. Further research should focus on using the integrated datasets with an attempt of expanding the scope of variables, and explicitly testing for omitted variable bias. [less ▲]

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See detailComparison of microleakage of photo-cured composites using three different light sources: halogen lamp, LED and argon laser: an in vitro study
Tielemans, M.; Compère, Philippe ULg; Geerts, Sabine ULg et al

in Lasers in Medical Science (2009), 24(1), 1-5

In this study, we compared the microleakage of composite fillings cured with halogen bulb, LED and argon ion laser (488 nm). Twenty-four extracted human molars were divided randomly in three groups. Six ... [more ▼]

In this study, we compared the microleakage of composite fillings cured with halogen bulb, LED and argon ion laser (488 nm). Twenty-four extracted human molars were divided randomly in three groups. Six cavities were prepared on the coronal part of each tooth. Standard cavities (1.7 x 2 mm) were prepared. Cavities were acid etched, sealed with Scotch Bond 1 and filled by a hybrid composite. Cavities were exposed to one light source, thermocycled and immersed in a 2% methylene blue dye solution. Dye penetration in the leakage of cavities was recorded using a digital optical microscope. Mean values of percentage of dye penetrations in microleakages of cavities were 49.303 +/- 5.178% for cavities cured with LED, 44.486 +/- 6.075% with halogen bulb and 36.647 +/- 5.936% for those cured by argon laser. Statistically significant difference exists between cavities cured by halogen vs LED (P < 0.01), halogen vs laser (P < 0.001) and LED vs laser (P < 0.001). The lowest microleakage was observed in the cavities and composites cured with argon ion laser. [less ▲]

Detailed reference viewed: 95 (8 ULg)