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See detailInvestigating Hardy-Weinberg equilibrium in case-control or cohort studies or meta-analysis.
Ziegler, Andreas; Van Steen, Kristel ULg; Wellek, Stefan

in Breast Cancer Research and Treatment (2011), 128(1), 197-201

Yu et al. (Breast Cancer Res Treat 117:675-677, 2009) recently stated that testing for deviation from Hardy-Weinberg equilibrium (HWE) is necessary to identify systematic genotyping errors in case-control ... [more ▼]

Yu et al. (Breast Cancer Res Treat 117:675-677, 2009) recently stated that testing for deviation from Hardy-Weinberg equilibrium (HWE) is necessary to identify systematic genotyping errors in case-control studies. They criticized a meta-analytic study for the deviation from HWE in the case group of one study. The aim of this article is twofold. First, we derive recommendations on how to test for deviations from HWE in different study designs. Second, we develop a meta-analytic framework for assessing compatibility with HWE or measuring deviation from HWE. The authors sketch the possible reasons behind deviation from HWE and provide guidelines for proper investigation of HWE deviations in different study designs. The authors argue that the standard HWE chi(2) lack of fit test is logically flawed and provide a logically unflawed approach for measuring deviation from HWE using confidence intervals. The proposed method is applicable to meta-analyses of both case-control or cohort association studies. The proposed approach is illustrated using the meta-analysis criticized by Yu et al. Heterogeneity between studies can be assessed. The critique of Yu et al. to the article of Frank et al. (Breast Cancer Res Treat 111:139-144, 2008) can be refuted. Even more, validity of HWE can be proven for the pooled control sample. The authors advocate the use of a confidence interval-based approach to assess HWE. The latter should only be investigated in control populations. In multicenter studies or meta-analysis, deviation from HWE should be analyzed using a meta-analytic approach. [less ▲]

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See detailInvestigating iron and organic matter incorporation in growing sea ice
Janssens, J.; Delille, Bruno ULg; de Jong et al

Conference (2014, March)

High concentration of exopolysacharides (EPS) and iron have been found in sea ice surrounding the Antarctic continent. However, the mechanisms leading to that enrichment remain unclear. Scavenging of iron ... [more ▼]

High concentration of exopolysacharides (EPS) and iron have been found in sea ice surrounding the Antarctic continent. However, the mechanisms leading to that enrichment remain unclear. Scavenging of iron by organic matter in seawater and entrainment during sea ice formation are thought to be responsible for the accumulation of iron in sea ice. EPS could also play a role in the iron passive chelative scavenging process in sea ice and in the increase of iron bioavailability. Our study investigates the processes responsible for the accumulation of iron (dissolved, particulate and total dissolvable iron), EPS, dissolved and particulate organic matter, macro-nutrients (silicic acid, nitrate and nitrite, phosphoric acid and ammonium), chlorophyll a and sea ice algae in young sea ice during an Australian-lead spring voyage off East Antarctica (SIPEX II September – November 2012) and a German-lead winter voyage to the Weddell Sea (AWECS June – August 2013). We used a combination of field- (“in situ”) and laboratory- based sea ice growth time-series experiments. In addition different types of newly formed sea ice as pancake ice, grey ice, frost flowers and slush were collected during both voyages as a means to compare and validate the experimental data. To our knowledge, this is the first report on the biogeochemical properties of newly formed Antarctic pack ice samples in the winter. Ice temperature, salinity and textures are also presented to support the biogeochemical observations at the onset of sea ice formation. [less ▲]

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See detailInvestigating Prostaglandin E2 activation of the p38 pathway of oesophageal squamous cell carcinoma
Rambout, Xavier ULg

Master's dissertation (2008)

Background, aim and objectives: Oesophageal squamous cell carcinoma (OSCC) is an endemic disease. Epidemiologic studies driven by investigation of Sammon in a region with one of the highest prevalence ... [more ▼]

Background, aim and objectives: Oesophageal squamous cell carcinoma (OSCC) is an endemic disease. Epidemiologic studies driven by investigation of Sammon in a region with one of the highest prevalence, linked a predisposition to develop OSCC to a high consumption of maize via reflux disease and chronic oesophagitis. In that context, it was postulated that prostaglandin E2 (PGE2), a hormone derived from a main component of maize, continuously triggers activation of proliferation and inflammation pathways. This work aimed at assessing the role of p38, a mitogen-activated protein kinase (MAPK), in the potential of PGE2 to trigger cellular proliferation, transcription and expression of proliferative (Cyclin D1) and inflammatory (IL-6) mediators in a human epithelial oesophageal cell line (Het1a). Methods: The proliferation potential of PGE2 via p38 was assessed by MTT assay on Het1a. The effect of H2O2 treatments was also assessed as a positive control. Then, RNA and protein samples were extracted from that cell line previously PGE2-treated. Transcription and expression profiles were studied over time respectively by quantitative polymerase chain reaction (qPCR) and western blot. The role of p38 was assessed by addition of a specific inhibitor, SB203580, to the cells under investigation. Results and Discussion: It was shown that PGE2 alone could not trigger proliferation of the Het1a cell line. Though, the effect of p38 might be positive. Acute H2O2 treatments turned out encouraging in the development of a model of p38 activation. Regulation of Cyclin D1 and IL-6 transcription was suggested to occur through PGE2 and via the p38 pathway. The Cyclin D1 and IL-6 transcripts were respectively overexpressed and downregulated in a bimodal manner, the second peak relying exclusively on p38 activation. Both observations could be supported by a positive feedback theory involving cyclooxygenase (COX)-2. Conclusions: Even though PGE2 was shown not to be sufficient to promote Het1a proliferation, regulation of Cyclin D1 and IL-6 transcription via p38 was observed. Furthermore, the expression profile might support the Sammon-Pink theory. [less ▲]

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See detailInvestigating relationships between Landsat ETM+ data and LAI in a semi-arid grassland of northwest China
Lu, L; Li, X; Ma, M G et al

in Geoscience and Remote Sensing Symposium, 2004. Proceedings IGARSS '04. (2004)

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See detailInvestigating rock-slope failures in the Tien Shan: State-of-the-art and perspectives of international cooperation (M111).
Strom, A.; Korup, O.; Abdrakhmatov, K. et al

Scientific conference (2005)

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See detailInvestigating State Reconstruction from Scarce Synchronized Phasor Measurements
Glavic, Mevludin; Van Cutsem, Thierry ULg

in Proceedings of the IEEE Trondheim Power Tech 2011 conference (2011, June)

Synchronized phasor measurements can potentially track the system dynamics between two classical state estimations. However, in the PMU configurations available nowadays and in the near future, those ... [more ▼]

Synchronized phasor measurements can potentially track the system dynamics between two classical state estimations. However, in the PMU configurations available nowadays and in the near future, those measurements are too scarce for the whole system state to be estimated. Therefore, we investigate the possibility to reconstruct coherent, time-synchronized system states from the available PMU data. State reconstruction is formulated as an optimization problem. The objective is to minimize, in the space of bus powers, the distance between the reconstructed state and the last state estimate provided by a standard state estimator. PMU data are imposed as equality constraints. Furthermore, the placement of PMUs near generators is advocated for higher accuracy of state reconstruction. The performance and potential benefits of the approach are illustrated by processing snapshots obtained from detailed time simulation of a test system subject to a disturbance and corrective actions. [less ▲]

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See detailInvestigating the Effects of Training and Techno-Pedagogical Support
Lecomte, Béatrice ULg; Van de Poël, Jean-François ULg; Verpoorten, Dominique ULg et al

Conference (2013, December)

This communication presents a quantitative-qualitative research conducted among 225 teachers and teaching assistants who have benefited from the education technologies training program provided by our ... [more ▼]

This communication presents a quantitative-qualitative research conducted among 225 teachers and teaching assistants who have benefited from the education technologies training program provided by our eCampus department at IFRES (University of Liege, Belgium) since 2011. The data collected are used to a) describe and characterize the public who attended these training sessions, b) identify the types of training programs chosen by the attendees, and c) to explore the influence of those sessions on the techno-pedagogical development of teachers. That effect is manifested by a change of mental representations or by "acting out" in terms of integrating technology into teaching practices. [less ▲]

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See detailInvestigating the factors for fermentative biohydrogen improvement: original bioreactors design and hydrogen partial pressure effect
Beckers, Laurent ULg; Hiligsmann, Serge ULg; Hamilton, Christopher ULg et al

in WHEC 2012, Toronto June 3rd - 7th (2012, June 05)

The anaerobic production of hydrogen from biomass offers the potential production of usable biogas from a variety of renewable resources. However, in order to produce hydrogen at high yields and ... [more ▼]

The anaerobic production of hydrogen from biomass offers the potential production of usable biogas from a variety of renewable resources. However, in order to produce hydrogen at high yields and production rates the biotechnological process needs to be further optimized and efficient bioreactors must be designed [1]. At the CWBI, a continuous horizontal rotating cylinder bioreactor has been designed and investigated to produce biohydrogen from glucose by the strain Clostridium butyricum [2] at good yields (1,9molH2•molglucose-1) and production rates (48,6mmolH2•Lmilieu-1.molhexose-1•h-1). This reactor has an internal volume of 2.3L and a small working volume (300ml) (fig.1). It enhances the hydrogen production rates (by about three times more than a completely stirred bioreactor) by partially immobilizing the bacteria on the porous support. Moreover, the rotating cylinder design enables efficient H2 gas transfer from the liquid phase increasing hydrogen yields by about 25% compared to a completely stirred bioreactor [3-4]. Other original bioreactors, such as a trickle bed, have been built with the same aim of lowering the hydrogen partial pressure and led to similar results. Our work shows the importance of a good liquid to gas transfers in the biohydrogen-producing reactors to reach higher performances. [less ▲]

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See detailInvestigating the Impact of Different Thermal Comfort Models for Zero Energy Buildings in Hot Climates
Attia, Shady ULg; Hensen, JLM

in Proceeding of: Conference on Energy and Indoor Environment for Hot Climates (2014, February 24)

The selection of a thermal comfort model has a major impact on energy consumption of Net Zero Energy Buildings (NZEBs) in hot climates. The objective of this paper is to compare the influence of using ... [more ▼]

The selection of a thermal comfort model has a major impact on energy consumption of Net Zero Energy Buildings (NZEBs) in hot climates. The objective of this paper is to compare the influence of using different comfort models for zero energy buildings in hot climates. The paper compares the impact of applying Givoni’s model, ASHRAE 55 adaptive comfort standard, EN 15251 adaptive comfort standard and EN ISO 7730 on energy consumption and comfort. Using ZEBO and EnergyPlus for energy simulation, an existing prototype of a residential apartment module will be used to evaluate energy performance and thermal comfort in two parametric series. The first one is the result of coupling natural ventilation and mechanical cooling and the second one is guided coupling natural ventilation, mechanical cooling and ceiling fans. Results show a significant difference of cooling loads and total energy generation for the compared comfort models. However, the study remains theoretical and requires post occupancy evaluation for a better reliability of the results. [less ▲]

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See detailInvestigating the intraspecific biodiversity of the threatened rodent Leopoldamys neilli in Southeast Asia
Latinne, Alice ULg; Waengsothorn, Surachit; Herbreteau, Vincent et al

Conference (2010, September 23)

We study the phylogeography of Leopoldamys neilli, a threatened murine rodent species endemic to limestone karsts of Thailand, in order to assess the influence of its endemicity to karstic habitat on its ... [more ▼]

We study the phylogeography of Leopoldamys neilli, a threatened murine rodent species endemic to limestone karsts of Thailand, in order to assess the influence of its endemicity to karstic habitat on its intraspecific biodiversity and phylogeographic pattern. Samples of L. neilli were collected in limestone karsts from 20 localities in seven provinces of Thailand. Two mitochondrial markers, the cytochrome b gene (cytb) and the cytochrome c oxydase subunit I gene (COI), were sequenced for 115 L. neilli individuals. A nuclear fragment, the β-fibrinogen intron 7 (bfibr), was amplified in a subset of 65 samples. Phylogenetic reconstructions and median joining networks were used to explore relationships between haplotypes of the studied populations. Haplotype and nucleotide diversities of the main lineages were estimated for each locus. Divergence times of the main lineages of L. neilli were estimated using Bayesian inference. The demographic histories of the main lineages of L.neilli were also examined. Our study gave evidence of a strong geographic structure of the genetic diversity for L. neilli. Six highly differentiated genetic lineages were observed in the phylogenetic and phylogeographic analyses. These lineages are allopatric and correspond to particular regions of Thailand. They exhibit very high degree of genetic divergence and gene flows between them are extremely low. Within each lineage, the levels of haplotype and nucleotide diversities are very low for each gene. These results suggest a severe fragmentation of L. neilli’s populations, correlated to the fragmented distribution of its habitat and highlight its high endemicity to limestone karsts. The strong phylogeographic pattern of L. neilli and the very ancient separation of some lineages could be explained by the geological history of Thailand during Tertiary and Quaternary era. In conclusion, this study revealed an unexpectedly high level of intraspecific biodiversity within the species L. neilli. These results consolidate the importance to strengthen the protection of limestone habitats and to preserve not only their huge interspecific but also intraspecific biodiversity. [less ▲]

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See detailInvestigating the morphology/rheology interrelationships in immiscible polymer blends
Martin, P. P.; Carreau, P. J.; Favis, B. D. et al

in Journal of Rheology (2000), 44(3), 569-583

Morphological changes in immiscible polymer blends have been studied in shear flow using an original method based on quenching following deformation of molten samples Relaxation effects wete expected to ... [more ▼]

Morphological changes in immiscible polymer blends have been studied in shear flow using an original method based on quenching following deformation of molten samples Relaxation effects wete expected to be negligible during cooling and, hence, the real shear-induced blend microstructure could be analyzed The method has been successfully applied to follow morphological changes of immiscible blends composed of polystyrene and relatively high amounts of high-density polyethylene during creep experiments. The final steady-state morphology appeared to be intimately related to the applied shear stress and total deformation. Coalescence as well as large deformation and orientation of the dispersed phase panicles have been observed depending on the flow conditions The variations with time of the blend rheological properties and morphological observations are in qualitative agreement. [less ▲]

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See detailInvestigating the performance of model order reduction techniques for nonlinear radiative heat transfer problems
Hickey, D.; Masset, Luc ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the International Conference on Advanced Computational Methods in Engineering (2011)

The problem of nonlinear radiative heat transfer is one of great importance to the aerospace industry. However, analysing large-scale, nonlinear, multiphysical, dynamical structures, by using mathematical ... [more ▼]

The problem of nonlinear radiative heat transfer is one of great importance to the aerospace industry. However, analysing large-scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally expensive. This provides motivation for the development of Model-Order Reduction (MOR) techniques capable of reducing simulation times without the loss of important information. The objective is to demonstrate the method of Proper Orthogonal Decompostition (POD) as a technique for nonlinear MOR. The nonlinear radiative exchanges between a linear benchmark beam within an external box (Figure 1) are analysed and a reduction procedure for this fully coupled, nonlinear, multiphysical, thermomechanical system is established. The solution to the strongly coupled, thermomechanical equations of motion is found by making use of an extended version of the implicit generalized-alpha scheme. In the reduced model, the residual of the unreduced system of equations need to be evaluated at each Newton iteration of each time step. In order to optimise the efficiency of the reduction method it is shown that the internal forces can be split into their linear and nonlinear counterparts. Only the nonlinear terms change at each time step, thus only these terms need to remain in the iterative loop significantly reducing the number of parameters that are to be computed at each step. These efficiency improvements to the method are discussed and the results are given. [less ▲]

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See detailInvestigating the relationship between ground-measured LAI and vegetation indices in an alpine meadow, north-west China.
Lu, L; Li, X; Huang, C L et al

in International Journal of Remote Sensing (2005), 26(20), 4471-4484

Detailed reference viewed: 5 (1 ULg)
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See detailInvestigating the role of myostatin in the determinism of double muscling characterizing Belgian Texel sheep
Marcq, Fabienne ULg; El Barkouki, S.; Elsen, J.-M. et al

(1998)

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See detailInvestigating the tinnitus brain using resting-state fMRI
Maudoux, Audrey ULg; Vanneste, Sven; De Ridder, Dirk et al

Conference (2012, June)

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See detailInvestigating the tinnitus brain using resting-state fMRI.
Maudoux, Audrey ULg; Vanneste, Sven; De Ridder, Dirk et al

Conference (2012, June)

Detailed reference viewed: 10 (0 ULg)
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See detailInvestigating the Variability in Daily Traffic Counts Trough the Use of ARIMAX and SARIMAX Models: Assessing the Effect of Holidays on two diverse site locations
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 88th Annual Meeting of the Transportation Research Board (DVD-ROM) (2009)

In this paper, daily traffic counts are explained and forecasted by different modeling philosophies, namely the ARIMAX and SARIMA(X) modeling approaches. Special emphasis is put on the investigation of ... [more ▼]

In this paper, daily traffic counts are explained and forecasted by different modeling philosophies, namely the ARIMAX and SARIMA(X) modeling approaches. Special emphasis is put on the investigation of the seasonality in the daily traffic data and on the identification and comparison of holiday effects at different site locations. To get prior insight in the cyclic patterns present in the daily traffic counts, spectral analysis provides the required framework to highlight periodicities in the data. Data originating from single inductive loop detectors, collected in 2003, 2004 and 2005, are used for the analyses. Four traffic count locations are investigated in this study, an upstream and downstream traffic count location on a highway that is excessively used by commuters and an upstream and downstream traffic count location on a highway that is typified by leisure traffic. The different modeling techniques pointed out that weekly cycles appear to determine the variation in daily traffic counts. The comparison between seasonal effects and holiday effects at different site locations revealed that both the ARIMAX and SARIMAX modeling approach are valid frameworks for the identification and quantification of possible influencing effects. The technique yielded the insight that holiday effects play a noticeable role on highways that are excessively used by commuters, while holiday effects have a more ambiguous effect on highways typified for their leisure traffic. Modeling of daily traffic counts on secondary roads, and simultaneous modeling of both the underlying reasons of travel and revealed traffic patterns, certainly are challenges for further research. [less ▲]

Detailed reference viewed: 23 (0 ULg)